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  • Artikel  (226)
  • Berkeley Electronic Press (now: De Gruyter)
  • Elektrotechnik, Elektronik, Nachrichtentechnik  (147)
  • Chemie und Pharmazie  (66)
  • Sociologie  (13)
  • 1
    Digitale Medien
    Digitale Medien
    An Argument against Arguments for Enhancement (2008)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2008, 1, art12 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: The treatment-enhancement distinction is difficult to make, and defenders of enhancement often base their case on that. Critics of enhancement, however, often have prototypical cases of enhancement-oriented interventions in mind, and the ethics of these can be evaluated on a case by case basis. Things like intelligence enhancement may have adverse effects on equality and utility. If the equality and utility effects of such enhancements were sufficiently severe, then restrictions would be called for. We need to think more about how to make tradeoffs between liberty, equality, and utility--and we need to know more about the extent to which each of these is at stake--before reaching conclusions about the ethics of, and appropriate social policy regarding, human enhancement.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art12
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  • 2
    Digitale Medien
    Digitale Medien
    Preserving Humanity - and Technology? A Response to de Grey (2008)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2008, 1, art11 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: Aubrey de Grey's enthusiasm may or may not be infectious, but it is certainly palpable. And it adds a dimension to the discussion the priority that should be given to life-extension/anti-ageing research of which he seems to be unaware. For on the cusp of developments in emerging technologies we find ourselves button-holed by enthusiasts whose ``transhumanist" visions importunately press upon us the most radical understanding of their implications. My suspicion is that the transhumanist mini-insurgency is partly responsible for the general failure of the policy establishment to summon up the courage and vision to address the implications of emerging technologies at all. The insurgents' effort at ``branding" these technologies as transhumanist (like that of the Raelian flying-saucer cult, a decade ago, to claim cloning as their own) does no favors to the technology. The irony is that de Grey and his fellow-visionaries, far from generating consensus enthusiasm for emerging technology applications, are making them too hot to handle.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art11
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  • 3
    Digitale Medien
    Digitale Medien
    Genetic Enhancement and Procreative Autonomy (2008)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2008, 1, art9 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: Liberal eugenics according to one version is distinguished from authoritarian eugenics on the basis that the choice of enhancement is devolved to parents. The argument for liberal eugenics combines a commitment to the right of parents to autonomy - in reproductive decisions and in the upbringing of children - and a parity claim that there is no morally significant difference between ante-natal and post-natal alterations of a child. The article reviews the putative constraints on parental choice, and assesses some criticisms of the parity claim. It concludes that a liberal commitment to social justice is in tension with a liberal commitment to parental choice, but judges that the former commitment does not entail the authoritarian eugenics which is represented as the alternative to liberal eugenics.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art9
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  • 4
    Digitale Medien
    Digitale Medien
    In Support of Human Enhancement (2008)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2008, 1, art10 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: This short comment presents arguments in support of human enhancement.What is enhancement? Surely it is a procedure that improves our functioning: any intervention which increases our general capabilities for human flourishing. We exclude from consideration those procedures often termed ``enhancements" that are of dubious overall benefit (for example breast or penis augmentation, or the taking of anabolic steroids to increase muscle mass). Equally we are not talking of ``designer" modifications which are more akin to aesthetic or fashion preferences than to improvements: hair colour, eye colour, or physique. An enhancement (as we are using the term) is something of benefit to the individual.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art10
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  • 5
    Digitale Medien
    Digitale Medien
    Performance of Statistical Process Control Tools under Different Plant Operation Strategies (2008)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 3 (2008), S. 4 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The outputs of statistical process control (SPC) tools developed for fault detection are comparatively examined while applied to actual data collected in an industrial plant. The influence of added information gathered from the plant operation under different strategies is analyzed. Particularly, standard principal component analysis (PCA), kernel PCA and the Hotelling's T2 charts are inspected for a reported problem. The effect of training the tools either with an extended historic databank obtained under standard operation, or including also non-conventional conditions, is studied. The ability of the tools to provide a specific alarm and identify the responsible variable is examined by analyzing the contributions per variable to the SPE and the T2 statistics. In addition, the capacity of the tested tools to adapt to a new operation strategy is compared.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol3/iss1/4
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  • 6
    Digitale Medien
    Digitale Medien
    Generous Funding for Interventive Aging Research Now? (2008)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2008, 1, art13 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: This article examines Aubrey de Grey's case for allocating substantial funding to interventive biogerontological research immediately. The conclusion is that the case is inconclusive and that scientific analyses of costs and probabilities would be needed to defend it properly.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art13
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  • 7
    Digitale Medien
    Digitale Medien
    Dynamic Model for Polyethylene Production in a Multizone Circulating Reactor (2008)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 3 (2008), S. 1 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The multizone circulating reactor (MZCR) technology is a newly announced reactor design for solid-catalyzed gas-phase polymerization. The process is characterized by two hydrodynamically distinct but interconnecting polymerization zones, thus forming a continuous loop of polymer flow between the said zones. In the present study, a dynamic model for the MZCR reactor is developed to illustrate the basic dynamic behavior of the new reactor design; the model is used to study the copolymerization of ethylene with butene. Several parameter sensitivity analyses are performed to show the computer-simulated time responses for reactor temperature, number-average molecular weight, weight-average molecular weight, catalyst feed rate and the monomer concentration along the reactor length.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol3/iss1/1
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  • 8
    Digitale Medien
    Digitale Medien
    A Modeling and Optimization Tool for the Expandable Polystyrene Batch Process (2008)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 3 (2008), S. 3 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Expandable Polystyrene (EPS), a material of the insulation productions and packages, is commonly produced in a batch process. The control of the batch process is based on predefined process recipes and process parameters such as mixing properties. The EPS production has to be able to satisfy the aims and quality requirements of the markets, which causes additional demands on the process control. In this paper we demonstrate the optimization and modeling application for the EPS-batch process. The application consists of a production optimization tool and a simulation tool for the process parameters based on the Multi-Layer Perceptron network (MLP) with retrain properties. The software can be used at the operational level as well as at the process management level. The features are programmed into standalone software built up in the Matlab environment and it is tailored for the needs of the EPS production company StyroChem Ltd. The results show that the application can offer an efficient tool to economize production and storage costs.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol3/iss1/3
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  • 9
    Digitale Medien
    Digitale Medien
    Investigation and Modeling of Splashing in the Peirce Smith Converter (2008)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 3 (2008), S. 2 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: To investigate the factors affecting splashing in Peirce-Smith copper converters of Sarcheshmeh copper complex, South-East Iran, a laboratory scale model with dimensions one eighth of the actual converter was designed and assembled. The model was filled with water. Air was impinged onto the water. The sequence of events was subsequently recorded using high speed cameras. Factors affecting splashing such as blowing angle, volumetric flow rate of air, and the distance of the blowers from water surface were studied.Using a value of 2.65×10-11 for Morton dimensionless number, it was found that splashing may be reduced by 75% if the air speed in the tuyeres is reduced from 155 m/s to 30 m/s while the nozzle distance from the melt free surface is between 2 to 0.5 meters.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol3/iss1/2
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  • 10
    Digitale Medien
    Digitale Medien
    Transient Behavior Analysis of Induction Generator at Three-Phase Fault Condition (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 2, art1 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In recent years, renewable energy generation has been coming up for effective use of natural energy, such as wind energy. Induction generators consisting squirrel-cage rotors are widely used as wind generators because of their salient features like robust rotor design, simplicity in the construction, maintenance free operation, etc. In this paper, it is derived that the transient current, electromechanical torque, and active power taking into account rotor speed change of induction generators at three-phase fault conditions. The output equations of the induction generator has nonlinearity, and the speed-time characteristic in a fault period is also expressed by the nonlinear equation. The approximation to derive analytical formulas for transient conditions is proposed, and the transient behavior of the induction generator is analyzed by the developed equations. The simulation block diagram in MATLAB/SIMULINK is constituted using the system equation in consideration of the nonlinearity of the induction generator. The simulation results obtained from each theoretical analysis are in close agreement with that of results obtained using MATLAB/SIMULINK simulation. Furthermore, theoretical discussion also developed to determine the fault phase angle and the time at which maximum transient currents flow in the system.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss2/art1
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  • 11
    Digitale Medien
    Digitale Medien
    Electric Load Management Using Electricity Tariff Algorithm (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 5, art3 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The tariff is the best incentive factor for the industrial customer today to reduce the peak load. This paper describes different methods of pricing electricity. It is important to study the influence of the tariff on the industrial loads and the costs of electricity before ILM can be implemented. This paper is interested in studying the economic aspects of fixed and operating cost, other factors affecting the generation economy, distribution of power, etc. Costs of supplying electricity to consumers are also considered. A utility can influence its customers' load by providing financial incentives through the prices charged for electricity at different times of use. By designing discriminatory time of use tariffs in which the prices of electricity corresponds to the marginal cost of supply, a utility provides appropriate signals to the customer to increase consumption of electricity at off peak periods. The proposed algorithm is implemented to a real system in operation.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss5/art3
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  • 12
    Digitale Medien
    Digitale Medien
    Neuro-Wavelet Approach to Time-Series Signals Prediction: An Example of Electricity Load and Pool-Price Data (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 2, art5 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Accurate electricity load and pool-price forecasting can provide a set of vital predicted information that helps generation, transmission and retailer participating companies to bid strategically into a deregulated electricity market in order to maximize their profits and increase returns to their stakeholders. Although a number of forecasting methods have been proposed to solve the short-term and long-term electricity load forecast, pool-price forecasting is a relatively new research area. In this article, we propose an autoregressive approach, based on a wavelet multiscale decomposition, for the prediction of one-hour ahead load and pool price based respectively on historical electricity load, and pool-price data. This approach is based on a multiple resolution decomposition of the signal using the redundant Haar à trous wavelet transform whose advantage is taking into account the asymmetric nature of the time-varying data. There is an additional computational advantage in that there is no need to re-compute the wavelet transform (wavelet coefficients) of the full signal if the electricity and pool price data (time series) is regularly updated. We assess results produced by this multiscale autoregressive method, in both linear and nonlinear variants, with single resolution autoregressive, multilayer perceptron, Elman recurrent neural network and the general regression neural network models. The input data consists of historical load and pool price data, which is collected over a period of 3 years (1999-2001), used for training, and 1 year (2002) used for testing. Experimental results are based on the New South Wales (Australia) electricity load and pool price data that is provided by the National Electricity Market Management Company.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss2/art5
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  • 13
    Digitale Medien
    Digitale Medien
    Application of Trajectory Sensitivity for the Evaluation of the Effect of TCSC Placement on Transient Stability (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 1, art4 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper investigates the use of trajectory sensitivity analysis (TSA) technique for assessing the transient stability of a power system at various operating conditions. The effect of placement of a thyristor controlled series compensator (TCSC) as well as the influence of the change in firing angle is also discussed. The TCSC is modeled by a variable capacitor, the value of which changes with the firing angle. The systems studied are the WSCC 3-machine, 9-bus system and IEEE 16 machine 68 bus system. The results using TSA are validated by PSCAD/EMTDC simulation.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss1/art4
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  • 14
    Digitale Medien
    Digitale Medien
    Distributed Generation Capacity Evaluation Using Combined Genetic Algorithm and OPF (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 2, art7 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A range of techniques has been proposed to define the optimal locations and capacities of distributed generation (DG) as a means of ensuring that the maximum amount of DG can be connected to existing and future networks. However, there are limitations inherent in these methods, not least in finding the best combination of sites for connecting a predefined number of DGs. Here, a method combining optimal power flow and genetic algorithms aims to meet this requirement. Its use would be in enabling Distribution Network Operators to search a network for the best sites and capacities available to strategically connect a defined number of DGs among a large number of potential combinations. Some applications of the proposed methodology confirmed its effectiveness in sitting and sizing an assigned number of DG units.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss2/art7
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  • 15
    Digitale Medien
    Digitale Medien
    Intelligent Approach for Fault Diagnosis in Power Transmission Systems Using Support Vector Machines (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 4, art3 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper presents an approach for identifying the faulted line section and fault location on transmission systems using support vector machines (SVMs) for diagnosis/post-fault analysis purpose. Power system disturbances are often caused by faults on transmission lines. When fault occurs on a transmission system, the protective relay detects the fault and initiates the tripping operation, which isolates the affected part from the rest of the power system. Based on the fault section identified, rapid and corrective restoration procedures can thus be taken to minimize the power interruption and limit the impact of outage on the system. The approach is particularly important for post-fault diagnosis of any mal-operation of relays following a disturbance in the neighboring line connected to the same substation. This may help in improving the fault monitoring/diagnosis process, thus assuring secure operation of the power systems. In this paper we compare SVMs with radial basis function neural networks (RBFNN) in data sets corresponding to different faults on a transmission system. Classification and regression accuracy is reported for both strategies. Studies on a practical 24-Bus equivalent EHV transmission system of the Indian Southern region is presented for indicating the improved generalization with the large margin classifiers in enhancing the efficacy of the chosen model.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss4/art3
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  • 16
    Digitale Medien
    Digitale Medien
    A Hybrid Decision Tree Model for Fast Voltage Contingency Screening and Ranking (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 4, art7 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper presents a new decision tree (DT) based approach for fast voltage contingency screening and ranking for on-line applications in energy management systems. The hybrid decision tree model is developed to learn all the selected contingencies simultaneously, therefore fewer DTs are required. To reduce the size and improve the accuracy of the decision tree, the K-class problem is converted into the set of K two-class problems, and separate decision tree modules are trained for each of the two class problems. All the selected contingencies are presented to the filter module, which is trained to separate them in critical and non-critical contingency classes, which reduces the burden on ranking modular DT. The critical contingencies screened out by the filter module are presented to the ranking modular decision tree for their further ranking. To measure the severity of contingencies, bus voltage violation based scalar performance index is used. Full AC load flow is performed to generate the training and testing patterns for the proposed hybrid decision tree, under each contingency. The effectiveness of the proposed approach is tested on IEEE test systems. Once trained, a hybrid decision tree method gives fast and accurate screening and ranking of contingencies for unknown load patterns.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss4/art7
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  • 17
    Digitale Medien
    Digitale Medien
    A Novel Load Compensation Algorithm under Unbalanced and Distorted Supply Voltages (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 5, art1 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In this paper, a novel control algorithm is proposed to compensate the unbalanced and non-linear loads in a three-phase four-wire system using active power filters. The algorithm results in balanced and sinusoidal source currents under unbalanced and distorted three-phase supply voltages. The algorithm makes use of the positive sequence extraction of the supply voltage and the theory of instantaneous symmetrical components. To illustrate the concept, a three-phase four-wire system with unbalanced and non-linear load is considered for compensation. The detailed simulation and experimental results are presented to validate the proposed method.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss5/art1
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  • 18
    Digitale Medien
    Digitale Medien
    Identification of External Power System Linear Dynamic Equivalents as MIMO Feedback Blocks for the Study System (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 5, art6 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The necessity of dynamic equivalents for power system analysis has been well known since the expansion of large interconnected power networks, and has been discussed during the last decades. The present paper proposes a new method for constructing dynamic equivalents of power systems. In this method, at the first step the ``study system" is modeled completely via a single machine-infinite bus modeling procedure. Then the ``external system" is identified as a MIMO feedback block of this model in such a manner that can include dynamic effects of the latter on the behavior of the former. The method is successfully experimented on a part of the Iranian southern network.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss5/art6
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  • 19
    Digitale Medien
    Digitale Medien
    Synchronous Generators Modeling and Control Using the Framework of Individual Channel Analysis and Design: Part 1 (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 5, art4 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In this paper a comprehensive dynamical assessment of a high order synchronous generator plant is carried out using the Individual Channel Analysis and Design (ICAD) framework -a multivariable control engineering tool that allows robustness and system performance evaluations. The great benefits of ICAD are elucidated and contrasted to those provided by the long-time honored block diagram representations. Several models used for the small signal stability analysis of synchronous generators are evaluated under the framework of ICAD. The study, which builds on pioneering work, reveals the great advantages of carrying out control system analysis and design with higher order generator models. Moreover, careful analysis of the ICAD's Multivariable Structure Function (MSF) helps to explain, formally, why some operating conditions of the control system are more critical than others. Furthermore, correct interpretations of MSFs are amenable to robust and stable control system designs. Two kinds of studies are considered in the paper; one assesses operation under various power factor conditions and the other under a varying tie-line reactance. The control system design and stability and structural robustness assessment of the system are presented in the second part of this paper. Moreover, results obtained under the ICAD framework are compared with those arising from conventional controllers.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss5/art4
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  • 20
    Digitale Medien
    Digitale Medien
    Model of Noise Source for HF Interference Calculation in a Converter Station (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 6, art3 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: For high-frequency (HF) interference in an HVDC converter station, the modeling of the noise source which causes interference with the power line carrier (PLC) remains a problem. Based on the profound analysis of the basic principles on which HF noise in PLC band is produced during the commutation process, the equivalent model of the HVDC valve with a snubber circuit is applied to the simulation of the GUI-GUANG HVDC project in PSCAD/EMTDC. Then spectrum plots of the noise source in the frequency domain are obtained by FFT analysis of the voltage waveforms gained from the simulation. Through analyzing the spectrum characteristics of the noise source in various operating modes, the main factors influencing the level of HF noise are found. Furthermore, a modified empirical model used to calculate the level of the noise source is introduced, with particular explanation of the physical quantities used in the model. The spectra of the noise source gained from the modified empirical model and from the simulation are compared with an actual spectrum based on the GUI-GUANG HVDC project. The results show that the modified empirical model can meet the requirement of HF interference calculation.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss6/art3
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  • 21
    Digitale Medien
    Digitale Medien
    A Multi-Level Methodology for Conceptual Reaction-Separation Process Design (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 2 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Generic technology is presented for the optimal screening of reaction and separation process interactions. The proposed scheme enables the use of particularly rich superstructure formulations that are comprised of two types of generic synthesis units with flexible representation modes. A reaction unit enables a detailed representation of the reaction and a conceptual representation of separation systems is facilitated through separation task units. Possible process design interactions are embedded in the superstructure formulations as combinations of generic units. The design options are explored using stochastic optimisation techniques suitable for this class of problems. The synthesis scheme supports the decision making process in early process design stages and prepares problem definitions for later stages. Conceptual screening functionalities reveal design insights into the performance of complex reaction-separation systems based on the limited modelling information available early in design. This enables the identification and inclusion of the relevant design information into the superstructure formulations employed in the subsequent design stages.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/2
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  • 22
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    Digitale Medien
    Learning to Control pH Processes at Multiple Time Scales: Performance Assessment in a Laboratory Plant (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 7 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This article presents a solution to pH control based on model-free learning control (MFLC). The MFLC technique is proposed because the algorithm gives a general solution for acid-base systems, yet is simple enough for implementation in existing control hardware. MFLC is based on reinforcement learning (RL), which is learning by direct interaction with the environment. The MFLC algorithm is model free and satisfying incremental control, input and output constraints. A novel solution of MFLC using multi-step actions (MSA) is presented: actions on multiple time scales consist of several identical primitive actions. This solves the problem of determining a suitable fixed time scale to select control actions so as to trade off accuracy in control against learning complexity. An application of MFLC to a pH process at laboratory scale is presented, showing that the proposed MFLC learns to control adequately the neutralization process, and maintain the process in the goal band. Also, the MFLC controller smoothly manipulates the control signal.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/7
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  • 23
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    Digitale Medien
    Inference of Chemical Reaction Networks Using Hybrid S-system Models (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 10 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This article demonstrates, using simulations, the potential of the S-system formalism for the inference of unknown chemical reaction networks from simple experimental data, such as that typically obtained from laboratory scale reaction vessels. Virtually no prior knowledge of the products and reactants is assumed. S-systems are a power law formalism for the canonical approximate representation of dynamic non-linear systems. This formalism has the useful property that the structure of a network is dictated only by the values of the power law parameters. This means that network inference problems (e.g. inference of the topology of a chemical reaction network) can be recast as parameter estimation problems. The use of S-systems for network inference from data has been reported in a number of biological fields, including metabolic pathway analysis and the inference of gene regulatory networks. Here, the methodology is adapted for use as a hybrid modelling tool to facilitate the reverse engineering of chemical reaction networks using time series concentration data from fed-batch reactor experiments. The principle of the approach is demonstrated with noisy simulated data from fed-batch reactor experiments using a hypothetical reaction network comprising 5 chemical species involved in 4 parallel reactions. A co-evolutionary algorithm is employed to evolve the structure and the parameter values of the S-system equations concurrently. The S-system equations are then interpreted in order to construct a network diagram that accurately reflects the underlying chemical reaction network.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/10
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  • 24
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    Digitale Medien
    Spatial and Temporal Resolution in Data-Driven Process Modeling of an Integrated Newsprint Mill (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 13 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Like many globalized industries, the pulp and paper sector finds itself with an increasingly demanding clientele, who continually expect a better and cheaper product. An important design strategy being employed to address this objective is through an analysis of the vast quantity of process and product data accumulated in plant-wide data historians, in order to improve operations. Mill processes are multivariate, meaning that the interactions between the variables are as important as the variables themselves. Process relationships must therefore be modeled as a group, using an appropriate simulation technique like Multivariate Analysis (MVA), with suitable data pre-processing to account for process upsets and other disturbances. In a previous paper, using an Eastern Canadian newsprint mill as an industrial case study, we showed that it was possible to find statistically significant correlations between wood chip refiner operation, intermediate pulp quality, and final paper quality using data-driven models. This was true even though some important process parameters went unmeasured, process lags changed with time, and the operation of key equipment items changed gradually with use. The present study compares the use of different timescales and combinations of unit operations to determine which ones yield the best MVA simulations. Because plant operating data were used, and experimental design was not practical, it is possible that some of the correlations found could be attributable to coincidence. We therefore added and removed variables and time periods to explore the validity of the models. The best MVA models were obtained by using a shorter (1-hour) data timescale, although use of a weighted-average filter helped to bridge the gap between these faster readings and the slower paper quality trends.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/13
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  • 25
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    Digitale Medien
    Optimization of the Variable Reflux Ratio in a Batch Distillation Column through a Heuristic Method (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 12 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The manuscript is focused on the optimization of a batch distillation column that is actually formulated in terms of control problem. The final objective is finding the optimal time-dependent reflux profile. In order to fulfill the call for simplicity and functionality from the industries, the reflux profile was approximated by means of a piece-wise function with three time intervals. A first-principles model, derived from the literature, proved to be a good trade-off between computational effort and accuracy. The capacity factor (CAP), defined as the on-specification products produced per time unit, is the performance index that must be maximized. The optimization problem was solved by a specifically modified Simplex method that demonstrated a good behavior in case of discontinuous objective function. Finally, a graphical analysis of the capacity factor was performed to show the irregularities of such a function.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/12
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  • 26
    Digitale Medien
    Digitale Medien
    Sliding-mode Observer for Uncertainty Estimation in a Class of Chemical Reactor: A Differential-Algebraic Approach (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 10 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The problem of the on-line estimation of the reaction heat in a continuous stirred tank reactor from temperature measurements is addressed in this paper. The proposed uncertainty observer is based on differential algebraic techniques, such that the algebraic observability condition of the uncertainty from noisy temperature measurements is easily verified and the observer structure is very simple, which lead to feasible implementation. The observer proposed is robust against noisy measurements and sustained disturbances. The good performance of the observer is shown by means of numerical simulations and is compared with a nonlinear Luenberger-type observer.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/10
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  • 27
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    Digitale Medien
    Passivity Based Dynamic Controllability Analysis for Multi-Unit Processes (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 7 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In this paper, a simple dynamic controllability analysis is developed to analyze the achievable control performance of different control structures for multi-unit processes. Based on the concept of passive systems, this approach extends the concepts of Decentralized Integral Controllability (DIC) and Block-Decentralized Integral Controllability (BDIC) so that process dynamics are considered. By using particular multipliers that represent different control structures, the frequency ranges in which perfect control may be achieved by multi-loop, multi-unit (block diagonal) and multivariable controllers are estimated. This bandwidth indicates the swiftness of the feedback control systems (e.g., the time the control systems take to reject a disturbance).
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss2/7
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  • 28
    Digitale Medien
    Digitale Medien
    Mathematical Modelling of the Self-Heating Process in Compost Piles (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 8 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: We model the increase in temperature in compost piles or landfill sites due to micro-organisms undergoing exothermic reactions. The model incorporates the heat release due to biological activity within the pile and the heat release due to the oxidation of cellulosic materials. The heat release rate due to biological activity is modelled by a function which is a monotonic increasing function of temperature over a particular range and followed by a monotone decreasing function of temperature. This functionality represents the fact that micro-organisms die or become dormant at high temperatures. The heat release due to the oxidation reaction is modelled by the usual manner using Arrhenius kinetics. The bifurcation behaviour is investigated for two-dimensional slab geometries to determine the critical sizes of the compost piles.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss2/8
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  • 29
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    Digitale Medien
    A MINLP Solution for Pellet Reactor Modeling (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 7 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A fluidized bed reactor for phosphate precipitation and removal from wastewater is modeled according to a two-step procedure. The first modeling phase, based on the development of a thermodynamic model for the computation of phosphate conversion, previously presented elsewhere is not reported here. The second step is related to the reactor modeling in the core of this paper. The pellet reactor is modeled as a reactor network involving a set of elementary cells representing ideal flow patterns. All the potential solutions are imbedded into a superstructure and the modeling problem is expressed as a MINLP problem. The MINLP problem is solved by means of the GAMS package, first for two flow rate values corresponding to two experimental fluidized bed behaviours, and then for the two flow rates considered simultaneously. In each case, the problem consists in finding an output concentration as close as possible to the experimental output concentration. Three objective functions are studied. The results are compared with those of Montastruc et al. (2004) who used a different numerical procedure. Whatever the considered case, the solutions found are structurally simpler than the ones of Montastruc et al. (2004). A major assessment of this study is that the reactor efficiency can easily be deduced, without any precise knowledge of some key parameters such as the density and thickness of the calcium phosphate layer. Finally a last numerical study concerning the superstructure definition shows that too complex a superstructure does not provide significant refinements on the solution.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/7
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  • 30
    Digitale Medien
    Digitale Medien
    Molecular Simulation Study of Vapor-Liquid Equilibrium of Morse Fluids (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 8 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The Morse potential energy function (PEF) is considered regarding the characterization of interaction forces of particles with tuning parameters. Phase coexistence of Morse fluids is predicted for different steepness and range of the PEF parameters using the grand-canonical transition matrix Monte Carlo (GC-TMMC) method, with quantification of the parameter S, which is the product of a constant with a unit of reciprocal length and the equilibrium distance between two molecules. We found that a lower limit of S exists bounded by infinite critical temperature. The critical properties of the vapor-liquid equilibrium curves are estimated using a rectilinear diameter method and a scaling law approach. A Clausius-Clayperon type relation of S and critical temperature is derived in this work. Vapor-liquid surface tension of Morse fluids by finite size scaling and GC-TMMC is also reported. Surface tensions are found to be higher at lower S.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/8
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  • 31
    Digitale Medien
    Digitale Medien
    Simulation of the Coke Calcining Processes in Rotary Kilns (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 20 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The objective of this study is to simulate the green petroleum coke calcining processes using the simulation program HYSYS and using actual industrial data. Because counter-current mass flow is not allowed in the HYSYS program, the kiln was described by using fictive streams and unit operations. By the simulation, it is possible to predict the operating conditions that control the contents of undesirable impurities in the calcined petroleum coke, namely, sulfur, volatile matter and moisture contents. It also gives the desirable calcined petroleum coke properties such as density. Apart from the metal contents, the simulation allows the coke calciner to utilize any type of green coke regardless of the undesirable impurities. This is done without resorting to the costly blend from different types of green cokes. Simulation is also effective in controlling and optimizing calcination processes' variables. From the simulation it was found that it is possible to process any type of green coke for varying sulfur, volatile matter and water content by adjusting the amount of tertiary air and/or fuel. Two simulation cases were studied for low and high volatile matter contents of 8.5 and 14.7 wt% in the feed. Mass flow rates of fuel and tertiary air were both increased in the first case, while no fuel was required in the second case. The benefit from this is to reduce the operating costs.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/20
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  • 32
    Digitale Medien
    Digitale Medien
    Determining the Optimized Controller Parameters Using a Hybrid GA-SQP Technique (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 30 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Dynamic simulation and optimization of a hydrogenation reactor system were developed and investigated in the present work. The process mainly consists of three adiabatic fixed bed hydrogenation reactors in series in addition to one heater before the first reactor and three coolers after each reactor for interstage cooling. The feed flow rate to the unit, the feed temperature or the carbon monoxide content of the feed may change and cause variations of the outlet temperature of reactors. Therefore, it is essential to control the inlet temperature of each reactor. There is a temperature controller before each reactor and also one after the third reactor. The tuning parameters of the controllers were optimized in three different cases, taking into account the process constraints. In each case, a special disturbance was forced to the process. Because of catalyst deactivation, the inlet temperature of reactors must be increased during the running period in order to have the desired conversion. Therefore, the optimal inlet temperature profile was determined based on SOR, MOR and EOR data. Optimization of the process was done by the use of a hybrid GA-SQP method. The new hybrid method was developed to overcome the difficulties of both methods. The genetic algorithm (GA) which is a stochastic method, is relatively slow, but is not sensitive to the initial point. In contrast, sequential quadratic programming (SQP) method is a deterministic method which is fast, but very sensitive to the initial point and gets trapped in local optima. In the newly developed hybrid method, the SQP method speeds the solving procedure, while the GA enables the algorithm to escape from local optima. An industrial acetylene hydrogenation system was used to provide the necessary data to adjust kinetics and to validate the approach.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/30
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  • 33
    Digitale Medien
    Digitale Medien
    The Equilibrium Network: A New Approach for Simulation and Visualization of Aqueous Electrolyte Systems (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 22 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new simulation method for investigating mixed aqueous electrolyte systems at thermodynamic equilibrium is presented. Based on the commercial simulation package IPSEpro, a graphical procedure for assembling equilibrium systems followed by simultaneous solution of the underlying equation system was developed. At graphical setup, species and reactions objects are connected by the information of activity and stoichiometry in a network-like manner. Consequently, the resulting equations of mass action, the electro-neutrality and balance conditions are solved incorporating the Pitzer activity coefficient model and equilibrium constants from thermodynamic standard data. The method developed allows fast and flexible application of the complex thermodynamic principles to engineering tasks. The modeling approach and all basic models for graphical input and simultaneous solution of coupled equilibrium conditions are explained. For demonstration of the simulation method, example simulations for the systems of H2SO4-H2O, CaSO4-H2SO4-H2O and NaCl-CaSO4-CO2-H2O are described and evaluated successfully.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/22
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  • 34
    Digitale Medien
    Digitale Medien
    Should We 'Cure' Aging? A Reply to de Grey (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2007, 1, art7 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: This is a reply to the discussion piece Life Span Extension Research and Public Debate: Societal Considerations, Studies in Ethics, Law, and Technology by Audrey de Grey. Having read the article there seem to be four messages. The first being, that longevity/immortality research faces rejection, resistance and neglect from `classic anti-aging' researchers, policy makers, the funding system and the public. The second being that the `pro-aging' trance is illogical; the third being that not pushing for longevity and immortality research is immoral; and the fourth being that so far no valid reason for opposing longevity and immortality has been generated and that we will deal with potential problems if and when they appear. My message in this invited comment is 1) that de Grey is right with his first point; 2) that his second point is debatable and depends on certain assumptions; 3) that his third point is even on weaker feet and debatable (Morals and ethics are social and cultural constructions and depending on ones frame of reference something can be seen as moral and ethical or not. This is a whole different paper as to who decides which morals and ethics are right and wrong and can't be covered here.) and 4) that the longevity and immortality research exhibits the same discourse problems as the other new and emerging technology discourses, namely that its makes light of potential and real social risks that it tailors to a minority of the world and ignores the marginalized majority of the world.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art7
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  • 35
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    Digitale Medien
    Development of Web Based Computer Package for the Simulation of Thermal Desalination Processes (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 14 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A computer package based on visual basic code is developed for single and multiple effect evaporation desalination systems (SEE and MEE). The package features design calculations of heat transfer area, power consumption, and costing. The package is user-friendly and is equipped with interactive menus for report and form printing, file saving and retrieving, help files, and tutorial. The computer code is designed to run a default design case and also allows the user to change variables within pre-specified practical ranges. A rigorous process model is used in the package, which is based on detailed fundamental material and energy balance equations, well-proven correlations for the heat transfer coefficients, physical properties, and thermodynamic losses. Illustrations of the package displays are presented together with a number of case studies. Model predictions generated from the code are validated against actual field data and they showed a very good agreement. Future plans involve development of design simulator for the multistage flash desalination (MSF) and reverse osmosis (RO).
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/14
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  • 36
    Digitale Medien
    Digitale Medien
    Mathematical Modeling of Supercritical Fluid Extraction of Fatty Acids from Trout Powder: Correlation of Mass Transfer Parameters (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 17 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Supercritical fluid extraction (SCFE) has been introduced as an excellent method especially for food and pharmaceutical industries. Trout powder was selected as a source of high amount of valuable materials such as essential fatty acids (FAs). In this work, a mathematical model is introduced to simulate the transitional behavior of the extraction process. This model is able to explain the variation of FAs concentration profile in the bulk and solid phases versus the time of extraction. Effects of main operational parameters such as pressure (280 to 340 bar) and temperature (310 to 326 K) on the extraction yields were investigated in the supercritical fluid extraction system of laboratory scale and the results were compared with that information obtained from the solution of the model. In order to describe solid-solvent interactions, a linear equilibrium relationship was used in the model. Partial differential mass balance equations for the solid and fluid phases were solved numerically using an implicit method. The effective diffusivity into the particle pores and mass transfer coefficient to the bulk phase were the model parameters and they were correlated at different temperatures and pressures by fitting the results of the model to the experiments. The axial diffusivity and equilibrium coefficient of solid-solvent were kept constant in whole range of the operational conditions and they were estimated as the model constants.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/17
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  • 37
    Digitale Medien
    Digitale Medien
    Extended Modeling Framework for Heat and Power Integration in Batch and Semi-continuous Processes (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 24 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Flexible manufacturing and processing, which are becoming crucial for companies that wish to remain competitive in today's changing market environment, require the detailed modeling of process operations, as well as the incorporation of utility consumption modeling and energy integration strategies. In this paper, a comprehensive modeling environment for heat and power integration in batch and semi-continuous processes is presented. Moreover, a general procedure concerning utility generation and utility system design optimization is described. This framework has been tested and evaluated as part of an industrial case study. The results obtained indicate that the general design methodology developed is effective for process integration of time-dependent processes with combined heat and power.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/24
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  • 38
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    Digitale Medien
    Social Perspectives and Genetic Enhancement: Whose Perspective? Whose Choice? (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2007, 1, art3 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: This paper's account of the core issues at stake in relation to genetic enhancement is presented as an alternative to mainstream liberal defenses of enhancement. The mainstream arguments are identified as being associated with reproductive autonomy, individual choice, and a `neutral', passive interpretation of technology. The alternative account is associated with the perspective of `woman' or child-bearer, with a fundamental concern for social justice, and an understanding of society in both a global and a contextual sense. This paper adopts a theoretical framework informed by feminist ethics, particularly a feminist ethic of care. The paper begins by outlining some of the key points of the care perspective, highlighting how this contrasts with a mainstream `justice' perspective, and illustrating how this is reflected in arguments relating to genetic enhancement. The paper then turns to a consideration of how a care perspective might be applied to questions of genetic enhancement, and how this may bring forward new issues. This includes in particular a consideration of IVF technologies and how applying understandings from research into this area brings forward usually unaddressed concerns in considering genetic enhancement. The final section of the paper covers some of the questions that there is space to ask once the narrow focus on individual rights is overcome.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art3
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  • 39
    Digitale Medien
    Digitale Medien
    Dynamic Economic Emission Dispatch Using Evolutionary Programming and Fuzzy Satisfying Method (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 4, art1 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Dynamic economic emission dispatch is an extension of the conventional economic emission dispatch problem that takes into consideration the ramp rate limits of the generators. Evolutionary programming based fuzzy satisfying method has been proposed to determine the optimal noninferior generation schedule. This paper treats economy and emission as competing objectives for optimal dispatch, which requires some form of conflict resolution to arrive at a solution. The multi-objective problem is configured as a minimax problem under the assumption that the decision-maker has fuzzy goals for each of the objective functions. The present algorithm employs evolutionary programming technique in solving this problem. The solution methodology can offer a global or near-global noninferior solution for the decision-maker. Numerical results of a sample test system have been presented to demonstrate the performance and applicability of the proposed method. Results obtained from the proposed method are compared to those obtained by fuzzy satisfying method based on simulated annealing technique.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss4/art1
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  • 40
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    Digitale Medien
    Brushless Doubly Fed Reluctance Machines: An Emerging Technology (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 1, art1 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Brushless doubly-fed machines (BDFMs) allow the use of a partially rated inverter and therefore offer reliable, maintenance-free operation at low cost, especially in large power variable speed applications with limited speed ranges such as off-shore wind turbines, pumps etc. However, with a special cage rotor design, the machine has substantial rotor losses, poor efficiency and complicated control being difficult to implement.The BDFM reluctance type, the brushless doubly-fed reluctance machine (BDFRM), can overcome most of the above BDFM deficiencies while retaining all its merits. It has a "cold" reluctance rotor, which makes it more efficient and much easier to model/control than the BDFM.A theoretical study of the BDFRM is very important to gain proper understanding of its unusual operation, the main control features and compromises between optimal performance and the size of the inverter and machine required. This paper will attempt to develop, and provide a comprehensive comparative analysis of, different control strategies for the machine that are suitable for digital implementation.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss1/art1
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  • 41
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    Digitale Medien
    Time-Frequency Spectrum Analysis of Very Fast Transient Currents (VFTC) Generated in a GIS (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 3, art4 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Very Fast Transient Overvoltages (VFTO) and the associated Very Fast Transient Currents (VFTC) generated during switching operations in a Gas Insulated Substation (GIS) couple conductively and inductively to the secondary equipment connected to the GIS. The frequency spectrum of the VFTC gives the dominant frequencies present but cannot provide the time varying current amplitude w.r.t. any particular frequency. Since the transient response of the control circuits is a function of the frequency content of the VFTC, it becomes necessary to segregate the VFTC waveform both in time and frequency scale simultaneously. This has been achieved by employing the GABOR wavelet function and the time-frequency spectrum of the VFTC waveform has been calculated at various locations for a 245 kV GIS during a switching event. The validity of the wavelet model is confirmed by reconstructing the VFTC signal at the GIS-cable termination as well as at the switching point using the time varying current waveforms obtained for different frequencies. Finally, the transient current vs frequency as well as the current vs distance charts are developed for the 245 kV GIS under study during various switching operations.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss3/art4
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  • 42
    Digitale Medien
    Digitale Medien
    A Novel Modulated Power Filter Compensator for Distribution Networks with Distributed Wind Energy (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 3, art6 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: During the last two decades, renewable wind energy has become increasingly popular as a consequence of strong ecological concerns and appealing advantages with regard to economical energy solutions in remote communities. Furthermore, with very large wind farms emerging, the dispersed renewable wind energy is required to be fully connected to the electrical distribution networks. However, the integration of dispersed renewable wind energy will pose a great challenge to the power quality in the distribution networks when the weak nature of the grid in remote areas and the uncertainty of wind are taken into consideration.This paper presents a novel Modulated Power Filter Compensator (MPFC) for the distribution networks with dispersed renewable wind energy interfaced. A tri-loop error driven controller is used to adjust the PWM switching of the modulated power filter compensator. Full power factor correction and power quality improvement is validated under different operation conditions, like load switching and wind velocity excursions. The MPFC device is a member of novel FACTS based compensators developed by the first author.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss3/art6
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  • 43
    Digitale Medien
    Digitale Medien
    A Test on Probabilistic Reliability Evaluation of the Korea Power System (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 2, art2 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The importance and conduct of necessary studies on grid reliability evaluation have become increasingly important in recent years due to the number of blackout events occurring throughout the world. Additionally, quantitative evaluation of transmission system reliability is very important in a competitive electricity environment. The reason is that successful operation of an electric power under a deregulated electricity market depends on transmission system reliability management. This paper suggests that the important input parameters of a probabilistic reliability evaluation tool for the KEPCO-system by sensitivity analysis of high reliability level operation. Simultaneously, it also presents sensitivity analysis probabilistic reliability evaluation of practical KEPCO-system long-term transmission system expansion planning (2006-2010). The tool utilized a Transmission Reliability Evaluation for Large-Scale Systems (TRELSS) which was developed by EPRI and Southern Company Services Inc.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss2/art2
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  • 44
    Digitale Medien
    Digitale Medien
    Modeling of Electric Power Supply Chain Networks with Fuel Suppliers via Variational Inequalities (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 1, art5 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The electric power industry in the United States and in other countries is undergoing profound regulatory and operational changes. The underlying rationale behind these transformations is to move once highly monopolized vertically-integrated industry from a centralized operation approach to a competitive one. The emerging competitive markets and an increase in the number of market participants have, in turn, fundamentally changed not only electricity trading patterns but also the structure of the electric power supply chains. This new framework requires new mathematical and engineering models and associated algorithmic tools. Moreover, the availability of fuels for electric power generation is a topic of both economic importance and national security. This paper uses the model developed by Nagurney and Matsypura (2004, 2006) as the foundation for the introduction of explicit fuel suppliers, in the case of nonrenewable and/or renewable fuels, and their optimizing behavior, into a general electric power supply chain network model along with "direct-supply" generation. We derive the optimality conditions for the various decision-makers, including fuel suppliers, power generators, suppliers, as well as the transmission service providers and the consumers at the demand markets. We establish that the governing equilibrium conditions satisfy a finite-dimensional variational inequality problem. We provide qualitative properties of the equilibrium flow pattern; in particular, existence of a solution and uniqueness under suitable assumptions. Finally, we discuss how the equilibrium fuel supply and electric power flow pattern can be computed.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss1/art5
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  • 45
    Digitale Medien
    Digitale Medien
    Probabilistic Index for Increasing Hourly Transmission Line Ratings (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 4, art4 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The steady state thermal rating of overhead transmission lines is limited by the conductor`s maximum design temperature, which is related to the maximum sag and the loss of tensile strength of the conductors. Traditionally, this overhead transmission lines rating is computed using a deterministic approach, with reference to severe weather conditions. Thus, the application of this method leads to conservative results resulting in under-utilization of conductors. In this paper, a new method based on an hourly probabilistic index is proposed to predict the line thermal rating for each hour of the day; this index is evaluated using the conductor current limit probability density function (pdf). The method uses Bayesian time series models for the weather parameters (ambient temperature, wind speed and wind direction) and calculates the conductor current limit pdf using a Monte Carlo simulation. The probabilistic index is applied by considering measured weather data of both hot and cold seasons; the corresponding lines ratings are reported and analyzed.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss4/art4
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  • 46
    Digitale Medien
    Digitale Medien
    Dynamic Simulation of Reactive Batch Distillation Column for Ethyl Acetate Synthesis (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 5 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A detailed mathematical dynamic model of reactive batch distillation column is formulated for ethyl acetate synthesis and presented in terms of differential and algebraic equations (DAEs). These DAEs are solved using fourth order Runge-Kutta method in MATLAB® to obtain the detailed column dynamics. The simulation results provide the dynamics of reboiler and distillate compositions, reboiler temperature, ethyl acetate purity in the accumulated distillate and conversion of the reactants. These results are analyzed to derive the optimum operating policy, i.e., reflux ratio and batch time.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss2/5
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  • 47
    Digitale Medien
    Digitale Medien
    Liberal Freedoms: Enhancement Is/nt Eugenics? (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2007, 1, art8 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: Genomics and the technologies arising out of the science are often heralded as a means of securing cures for diseases which have proved resistant to the progress of medicine. These, generally hereditary diseases, with advances in genomic science are becoming more understood, but as of yet the possibilities of effective cures, whether through for example somatic or germ-line gene therapy, remain elusive. This has not stopped despite speculation and debate on potential future applications such as the use of genetic technologies in enhancing humans. Curative applications and enhancement applications are inextricably linked however both through the social contexts in which these technologies are to be deployed and the discourses which inform and frame the debates on their use. This article seeks to explore these links and in doing so aims to investigate some of the wider dimensions of the enhancement debate.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art8
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  • 48
    Digitale Medien
    Digitale Medien
    Life Span Extension Research and Public Debate: Societal Considerations (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2007, 1, art5 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: The pace of a given strand of scientific research, whether purely curiosity-driven or motivated by a particular technological goal, is strongly influenced by public attitudes towards its value. In the case of research directed to the radical postponement of aging and the consequent extension of healthy and total lifespans, public opinion is entrenched in a "pro-aging trance" - a state of resolute irrationality. This arises from the entirely rational attitude to a grisly, inevitable and relatively far-off fate: putting it out of one's mind allows one to make the most of what time one has, free of preoccupation with one's demise, and it is immaterial how irrational the arguments that one uses to achieve this are, e.g. by persuading oneself that aging is not such a bad thing after all. As biotechnology increasingly nears the point where aging will no longer be inevitable, however, this studied fatalism has become a core part of the problem, making people reluctant to join the crusade to hasten that technology's arrival. An effective way to address this hesitation is to promote debate about the reasons people give for fearing the defeat of aging, most of which are sociological. Such debate exposes people to the glaring flaws in their own logic. Thus, the more the debate is sustained and promoted, the harder it is for those flaws to be ignored.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art5
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  • 49
    Digitale Medien
    Digitale Medien
    Medical Nanorobotics: Breaking the Trance of Futility in Life Extension Research (A Reply to de Grey) (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2007, 1, art6 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: Biogerontologist Aubrey de Grey has suggested that one of the reasons we as a society invest so little in research on combating aging is because we are in an intellectual trance. We think the effort will be futile: aging is immutable, so why try? A healthy skepticism can be a good thing but it is a major mistake to bet against the irresistible force of inexorable technological progress. Over the next few decades, nanotechnology will come to play a pivotal role in the solution to the problem of human aging. Medical nanorobotics, if it can be made to work, can unquestionably offer convenient solutions to all known causes of age-related damage and most likely can also successfully address any new causes of senescence that remain undiscovered today.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art6
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  • 50
    Digitale Medien
    Digitale Medien
    DSP Based Implementation of Hybrid Fuzzy PI Speed Controller for Direct Torque Controlled Permanent Magnet Synchronous Motor Drive (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 2, art6 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper presents a Digital Signal Processor (DSP) based implementation of Hybrid of Fuzzy Logic Controller (FLC) and Proportional-Integral (PI) speed controller for Direct Torque Controlled (DTC) Permanent Magnet Synchronous Motor (PMSM) drive. The fuzzy membership function is used for hybrid control of these two FLC and PI speed controllers in such a way that at the time of dynamic conditions such as starting, the degree of belonging for FLC speed controller is higher than the PI speed controller and near set point the degree of belonging of PI controller is having higher weightage. The simulation model of the drive system is developed in MATLAB environment with simulink, PSB and FLC toolboxes to analyze the performance of the PMSM drive system. This hybrid speed controller is found suitable for DTC based PMSM drive to maintain the high level of performance while maintaining the excellent response at the time of starting, speed reversal, load perturbation and steady-state operating condition of the drive.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss2/art6
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  • 51
    Digitale Medien
    Digitale Medien
    Radial System Reconfiguration to Minimize Operating Costs in Markets (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 1, art2 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The operating cost of a radial distribution system may be minimized by reducing the amount of real power and reactive power drawn from the transmission system. Presently, real power is being priced through a market clearing scheme all over North America. Reactive power is an ancillary service and its supply would be priced appropriately in the near future through a clearing market structure. A recent US Federal Energy Regulatory Commission staff report [1] has initiated a discussion on the formulation of a reactive power market. When such a market is designed and operated, large customers (distribution corporations) will have to purchase reactive power along with real power from the transmission corporation through an independent system operator. Envisaging such a prospect, this paper proposes a new method of reconfiguring radial systems considering costs of real and reactive power while maintaining an appropriate voltage profile and level of reliable power supply. The proposed method is tested on sample test systems and reported.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss1/art2
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  • 52
    Digitale Medien
    Digitale Medien
    Multi-Agent Models for Consumer Choice and Retailer Strategies in the Competitive Electricity Market (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 2, art4 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The benefit to end-users of electricity, mainly in terms of low prices, is strictly related to the interaction among the consumers themselves and retailers. The literature on retail competition has highlighted possible distortions in market outcomes due to unresponsive demand and boundedly rational consumers. Hence, a model appropriate to represent this aspect of the market is needed. The paper proposes a general model of the interaction among retailers and consumers in the electricity market based on the theory of multi-agent systems. The model incorporates different assumptions concerning the behavior of the players that corresponds to different levels of interaction in determining the market outcomes. The model is validated interpretively by the results provided in terms of Game Theory equilibrium. The results of an extensive set of simulations on a population of 1,000 consumers is presented and discussed.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss2/art4
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  • 53
    Digitale Medien
    Digitale Medien
    Distributed Generation Communications Utilizing a Real-time FPGA-based Channel Simulator in the ISM Frequency Band (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 1, art3 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Deregulation of the power industry, increases in consumer demand of electricity and mandates to reduce greenhouse gases has significantly heightened the interest in distributed generation (DG). Typical DG sources include wind turbines, fuel cells, micro gas/diesel turbines, small hydro generators and photovoltaics. Currently most of these generation sources are optimized for local operation and thus the potential of DG that is both dispatchable and cost-effective has yet to be fully realized. One key technical challenge is the development of low-cost communications for remote telemetry and control of individual DG sources. Along with cost, other key communication system requirements are modularity, range and reliability. This paper presents a distributed generation communication system (DGCS) that is based on a wide area network (WAN) and local area network (LAN) topology and utilizes two variants of low-cost radio modems (RM) to satisfy the desired connectivity between the DG sites and a centralized control center. For the LAN, low-cost RMs operating in the industrial, scientific, and medical (ISM) frequency band offers point-to-multipoint scalability to multiple DG sites within a limited range. Integration of the ISM RMs with a cellular RM provides connectivity to a WAN or Internet thus providing long-range access to DG sites from any facility that has internet-access. Given the LAN scalability requirement, an ISM field programmable gate array (FPGA) channel simulator was developed to assess DGCS performance using channel impairments such as free-space path loss, multipath reflections, additive white Gaussian noise (AWGN), multiple access interference, and narrowband interference. This study provides the evaluation of two commercially available ISM radio modems and recommendations are made based on LAN requirements such as cost and performance given difficult channel conditions.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss1/art3
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  • 54
    Digitale Medien
    Digitale Medien
    Security Constrained Stochastic Multi-objective Optimal Power Dispatch (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 1, art7 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A stochastic multi-objective line security constrained problem is formulated to minimize non-commensurable objectives viz. operating cost, polluting gaseous emission and variance of active power generation and reactive power generation, with explicit recognition of statistical uncertainties in the thermal power generation cost coefficients, gaseous emission coefficients, power demands and hence power generations and bus voltages, which are considered random variables. Specific technique is put forth to convert the stochastic models into their respective deterministic equivalents. Fuzzy set theory has been exploited to evaluate the different objectives that are quantified by defining their membership functions. Security of transmission lines with respect to expected active power flow is considered in the form of fuzzy objective function. The solution set of such formulated problems is non-inferior due to contradictions among the objectives undertaken. The weighting method is used to simulate the trade-off relationship between the conflicting objectives in the non-inferior domain. Generally, the weights are either simulated or searched in the non-inferior domain. In the paper Evolutionary search technique is implemented to search the 'preferred' weightage pattern in the non-inferior domain, which corresponds to the 'best' compromised solution. Among the non-inferior solutions, the system operator selects the 'preferred' optimal operating point that provides maximum satisfaction level of the most under achieved objective in terms of membership function and is termed as fitness function. The validity of the proposed method has been demonstrated on an IEEE system comprising of 11-nodes, 17-lines and 5-generators.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss1/art7
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  • 55
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    Digitale Medien
    The Vulnerability Analysis of Transmission System Based on the Performance of Mho Relay and SVC (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 1, art6 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The security of the transmission system is dependent on the relays' performance after various disturbances. Undesirable relay operation will trip the lines and lead to cascading events. In this paper the operation margin of mho relays is equivalently redefined as function of bus voltages instead of line impedance. The sensitivities of the operation margin to bus voltage and bus power is applied to quantify the vulnerability of transmission system. The contribution of the shunt compensation by SVC is analyzed based on the sensitivities (control factors) of the operation margin to the shunt susceptance. It is found that the control effect of SVC is approximately linear when the mho relay has relative smaller operation margin. In this range the linear model based on the control factors is accurate enough to simulate the control effect. It is also found that the shunt compensations at different locations may yield opposite effect to the operation margin of the mho relays, which can be easily judged by the value of the control factors.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss1/art6
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  • 56
    Digitale Medien
    Digitale Medien
    Extended Delta Based 15-Phase AC-DC Converter for Variable Frequency Induction Motor Drives (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 5, art5 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper presents the design and analysis of a multi-phase ac-dc converter system for harmonic reduction at the point of common coupling (PCC) in vector controlled induction motor drives (VCIMD's). The design of the proposed 3-phase to 15-phase autotransformer is presented along with the VCIMD. The proposed 15-phase ac-dc converter is found capable of suppressing up to the 29th harmonic in the supply current, along with the power factor improvement close to unity in the wide operating range of the drive. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed ac-dc converter. A set of power quality indices on input ac mains and on dc bus for a VCIMD fed from existing 6-pulse and proposed 15-phase ac-dc converters are also given to compare their performance.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss5/art5
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  • 57
    Digitale Medien
    Digitale Medien
    Fuzzy Expert Approach with Curtailed Controllers for Improved Reactive Power Dispatch (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 3, art7 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper addresses the problem of curtailing the number of control actions using fuzzy expert approach for voltage/reactive power dispatch. It presents an approach using fuzzy set theory for reactive power control with the purpose of improving the voltage profile of a power system. To minimize the voltage deviations from pre-desired values of all the load buses, using the sensitivities with respect to reactive power control variables form the basis of the proposed Fuzzy Logic Control (FLC). Control variables considered are switchable VAR compensators, On Load Tap Changing (OLTC) transformers and generator excitations. Voltage deviations and controlling variables are translated into fuzzy set notations to formulate the relation between voltage deviations and controlling ability of controlling devices. The developed fuzzy system is tested on a few simulated practical Indian power systems and modified IEEE-30 bus system. The performance of the fuzzy system is compared with conventional optimization technique and results obtained are encouraging. Results obtained for a modified IEEE-30 bus test system and a 205-node equivalent EHV system a part of Indian southern grid are presented for illustration purposes. The proposed fuzzy-expert technique is found suitable for on-line applications in energy control centre as the solution is obtained fast with significant speedups with few number of controllers.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss3/art7
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  • 58
    Digitale Medien
    Digitale Medien
    Damping of Inter-Area Oscillation in Power Systems by Static Var Compensator (SVC) Using PMU-Acquired Remote Bus Voltage Angles (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 4, art6 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper presents a novel concept of Static Var Compensator (SVC) damping control using a weighted sum of bus voltage angles of remote generators that are responsible for causing inter-area oscillations in power systems. These remote bus voltage angle signals are acquired through Phasor Measurement Units (PMUs). A time domain simulation study on a 39-bus New England multi-machine system is utilized to show that an SVC auxiliary damping control, based on the derivative of these remote bus voltage angles, is superior to the conventionally employed local signals in damping inter-area oscillations. The effect of transmission delay in the acquisition of remote signals is also presented and a simple mechanism to compensate this delay is proposed and validated. The robustness of the delay compensator is finally shown for a wide range of signal transmission delays. The designed SVC controller shows a superior performance in damping the inter-area oscillations despite the signal transmission delays.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss4/art6
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  • 59
    Digitale Medien
    Digitale Medien
    Decision Tree Based Fault Classification Scheme for Protection of Series Compensated Transmission Lines (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 6, art1 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Series compensation at the midpoint of a transmission line creates problems to conventional protection approaches. A new fault classification technique has been developed for a transmission line with a series capacitor at the midpoint, having different percentages of compensation varying from 25% to 75%. The proposed technique requires three line currents and voltages at each end and computes fundamental phasors of these quantities using a modified version of Full Cycle Discrete Fourier Transform. Using these phasors, the absolute values of three phase impedances are calculated for faulted phase identification. Moreover, the involvement of the ground in the fault is identified using a zero sequence component of the fault current. Using a PSCAD/EMTDC software package, a large test data (28,800) set has been generated with different types of faults and system variables, which includes fault resistances, fault inception angles, fault positions (before and after series capacitor) and variable loading conditions along with wide variations in the source impedances at both ends of a transmission line. The proposed scheme is tested on the said data set and the results are found to be promising. The results indicate that the proposed technique is fast, accurate and robust for a wide variation in system and fault conditions.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss6/art1
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  • 60
    Digitale Medien
    Digitale Medien
    Vulnerability Assessment of Power Grid Using Graph Topological Indices (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 6, art4 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper presents an assessment of the vulnerability of the power grid to blackout using graph topological indexes. Based on a FERC 715 report and the outage reports, the cascading faults of summer WSCC 1996 are reconstructed, and the graphical property of the grid is compared between two cases: when the blackout triggering lines are removed simulating the actual sequence of cascading outages and when the same number of randomly selected lines are removed. The investigation finds that the critical path lengths of the triggering events of the July and August outages of 1996 WSCC blackout are higher than those of no-outage and arbitrary events. In addition, the small world-ness index for each of the outage triggering events is much smaller than that of normal or any no-outage scenario, indicating that events of shifting a network from small world to a random network would be more likely cascaded to wide area outage.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss6/art4
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  • 61
    Digitale Medien
    Digitale Medien
    Analysis and Simulation of Cross-Flow Reactor for Ethylene Epoxidation (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 6 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A steady-state cross-flow reactor for ethylene epoxidation was simulated using industrial data (low oxygen/ethylene feed ratio) and pilot plant data (high oxygen/ethylene feed ratio). A comparison between the conventional fixed-bed reactor and the cross-flow reactor with two types of feeding modes was performed. The present study showed the possibility of enhancing the reactor yield by distributing the ethylene optimally at equal spaced along the reactor for both commercial and pilot plant cases. We have shown that the evenly distributed feeding mode does not increase the desired ethylene oxide yield. The model results confirmed that the cross-flow reactor with ethylene is the best configuration, followed by the conventional fixed-bed reactor and the cross-flow reactor with oxygen, respectively.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/6
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  • 62
    Digitale Medien
    Digitale Medien
    Applications of Computational Fluid Dynamics (CFD) Tools for Gravity Concentrators in Coal Preparation (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 11 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Extensive progress has been made in using CFD tool in the simulation of multiphase flows in some gravity concentrators. Several case studies for calculation of multiphase flows by different numerical models in spiral, dense medium cyclone, water only cyclones, hindered-settling bed separator, heavy medium vessel and jig are reviewed. The Euler-Lagrange approach in calculation of the particle movement and particle-liquid coupling effect are also discussed. The limitation of Euler-Euler models in the treatment of the particles with a size distribution, and disadvantages of discrete element method (DEM) in description of the jigging processes will be presented. The successful two-dimensional simulation of the hindered-settling bed separator, heavy medium vessel and jig by Euler-Lagrange approach is also addressed.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/11
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  • 63
    Digitale Medien
    Digitale Medien
    Instrumentation Network Design for Solids Processes (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 9 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Proper plant control and operation has to be based on measurements of process data at different locations within the process. The design of the instrumentation network is therefore an important step in the design phase of a given process. An advanced instrumentation network design should not only allow process control on a minimum data basis but should enable the plant operator to gain more insights into the functionality and capabilities of his process. For this purpose in-process balancing based on a suitably configured instrumentation network is necessary. To make full use of the measurements the data has to be processed by data reconciliation methods. In the present work an earlier approach by Chmielewski et al. (2002) has been applied to solids processes. This paper shows how the selected approach can be adopted to the measurement and processing of distributed variables, e.g. particle size and densities. An optimal instrumentation with regard to investment cost can be found that ensures that all necessary data for the reconciliation problem can be collected. The application to solids processes is illustrated with the examples of a simple screening-crushing process and a hydrocyclone cascade.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/9
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  • 64
    Digitale Medien
    Digitale Medien
    A Generalized Kinetic Model for Hydrometallurgical Processes (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 1 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In electrochemical leaching processes the solid must be an electric conductor, e.g., a metal, or a semiconductor, e.g., certain metal sulfides or oxides. Reaction takes place by the transfer of electrons at the solid surface and involves oxidation-reduction processes that take place simultaneously at two different locations not far from each other. At one location, electrons are picked up by a depolarizer, D, in solution, e.g., O2, H+, etc. (the cathodic zone) and at another location metal ions are released in solution (the anodic zone) where they react with reagent C. A single kinetic law derived theoretically is obeyed:Rate = k1k2A[D][C] / (k1[D] + k2[C]) where k1 and k2 are constants, and A is the total surface area of the dissolving solid.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/1
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  • 65
    Digitale Medien
    Digitale Medien
    Parallel Dynamic Artificial Neural Network for Temperature and Moisture Content Predictions in Microwave-Vacuum Dried Tomato Slices (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 23 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Temperature (T) and moisture content (MC) of non-homogenous food undergoing microwave-vacuum (MV) drying (MVD) are directly dependent on microwave power, vacuum pressure, and the product's physical properties. A two-hidden-layer Artificial Neural Network (ANN) model was developed in an earlier study to predict temperature and moisture content of the product at a given time based on the present state of product conditions and process control parameters. This approach either provided lowest error in temperature prediction or in moisture content prediction but not the lowest error in both the prediction parameters simultaneously. The main objective of this work was to improve the performance of the ANN model for temperature and moisture content predictions in MV dried samples. Experimental data obtained from MVD of tomato slices at different drying conditions was normalized and divided into two groups for training and validating. The parallel dynamic ANN model consisted of two double-hidden-layer feed-forward ANN models with varying node numbers (10, 20, and 30). These models were separately trained, simultaneously for moisture content as well as temperature, with the Levenberg-Marquardt algorithm. Inputs for the ANN models were magnetron on-off status, vacuum pressure, temperature, and moisture content at time `ti'. The previous temperature and moisture content data at time `ti-1, i-2, , i-n' where n = 0, 10, 20, and 30 were also added to the input layer. Outputs from the ANN models were temperature and moisture content at time `ti+1'. The results indicated that the dynamic ANN model working in parallel with the previous temperature and moisture content data provided results that are more accurate and required less training time than those of ordinary ANN models. Model simulation may supply essential information regarding temperature and moisture content of non-homogenous foods corresponding to microwave power and vacuum pressure levels to the predictive control system. Therefore, improved drying efficiencies and thermal damage prevention may be achieved.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/23
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  • 66
    Digitale Medien
    Digitale Medien
    Multirate Constrained Predictive Control: Algorithm and Experimental Results (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 13 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Control of multirate systems is a challenging problem due to several reasons such as increased complexity in the design with tighter performance specifications. In this work, an algorithm for multirate constrained predictive control (MCPC) is presented. The multirate predictive control system includes a multirate state estimator, which provides inter-sample estimates of state variables of the process from infrequent and slow measurements. Constraints are addressed rigorously in this framework. The proposed design method is verified via simulation as well as experimentation. The results of the multirate predictive control for temperature control of a stirred tank system are shown and compared with those of a proportional integral (PI) control system.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/13
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  • 67
    Digitale Medien
    Digitale Medien
    Three-Dimensional Hydrodynamics and Reaction Kinetics Analysis in FCC Riser Reactors (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 4 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Fluid catalytic cracking (FCC) is the refinery process for the conversion of high molecular-weight hydrocarbons to produce higher valuable products such as gasoline. The optimization of FCC process is challenging due to the complex interactions between a large number of dependent and independent parameters. One of the most uncertain aspects of a fluid catalytic cracking (FCC) unit is the description of fluid-solid mixing at the riser entrance. Most of the existing models assume an instant mixing of solids and gaseous reactants. However, a finite mixing length at the bottom of the riser may have a pronounced effect on the FCC operation, particularly, when very short residence times are allowed in the current commercial FCC risers. A good solid-fluid mixing is essential to ensure a complete feed vaporization which is important for several reasons including assuring a thorough catalyst to oil contact and minimizing coke deposition. In this study, the Eulerian-Eulerian multiphase flow and the 3-lump kinetic models were used to simulate the hydrodynamics and cracking reactions occurring in the FCC riser reactors. The model demonstrated the capability of commercial CFD code FLUENT 6.2 to describe the flow field in the riser reactor. The model also takes into account the temperature, the heat of reactions and gasoline distribution along the riser height.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss2/4
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  • 68
    Digitale Medien
    Digitale Medien
    Advanced Computational Techniques for Solving Desalination Plant Models Using Neural and Genetic Based Methods (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 29 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Simulation of multi-stage flash (MSF) desalination processes that have a production capacity range between 50,000 to 75,000 m3/d is an intensive computational problem that requires high computer processing speed despite the availability of advanced processing computer power in hand nowadays. In this work, a comparative study is conducted to explore the performance of different numerical techniques to solve large set of nonlinear equations generated by large scale MSF models. These algorithms can be categorized into three groups, namely: conventional numerical approximation methods, multi-objective optimization based methods, and the last group comprises artificial neural networks (ANN) based models and genetic algorithms (GA) based methods. The problem of solving large sets of nonlinear equations with upper and lower constraints is accomplished successfully using all algorithms with different prediction efficiency and speed. The idea of using GA and ANN based algorithms in simulating the MSF model is basically used to generate feasible initial solution estimates that were used as starting guesses for other numerical methods in the former case and to eliminate the step of providing these initial guesses in the later case. Significant reduction of computation effort was attained using ANN-based techniques. The outcome of this work can be utilized to develop new generations of process simulators that are based on well-trained ANNs in order to achieve speedup of computations and to generate more reliable predictions without detracting from accuracy.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/29
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  • 69
    Digitale Medien
    Digitale Medien
    Nonlinear Modelling Application in Distillation Column (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 12 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Distillation columns are widely used in chemical processes and exhibit nonlinear dynamic behavior. In order to gain optimum performance of the distillation column, an effective control strategy is needed. In recent years, model based control strategies such as internal model control (IMC) and model predictive control (MPC) have been revealed as better control systems compared to the conventional method. But one of the major challenges in developing this effective control strategy is to construct a model which is utilized to describe the process under consideration. The purpose of this paper is to provide a review of the models that have been implemented in continuous distillation columns. These models are categorized under three major groups: fundamental models, which are derived from mass, energy and momentum balances of the process, empirical models, which are derived from input-output data of the process, and hybrid models which combine both the fundamental and the empirical model. The advantages and limitations of each group are discussed and compared. The review reveals a remarkable prospect of developing a nonlinear model in this research area. It also shows the discovery of new advance methods in an attempt to gain a nonlinear model that is able to be used in industries. Neural network models have become the most popular framework in nonlinear model development over the last decade even though hybrid models are the most promising method to be applied for future nonlinear model development.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/12
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  • 70
    Digitale Medien
    Digitale Medien
    Simulation and Analysis of Fluid Dynamic Behaviour of Foods during Filling Processes (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 18 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This research presents a model describing the behaviour of a non-Newtonian shear-thinning fluid during aseptic filling processes, in order to determine the influence of the behaviour of fluids on the performance of filling valves in aseptic beverage plants, mainly in terms of the time required to perform the filling process. The ultimate aim of the study is to explore the possibility of improving the accuracy of industrial filling processes, so as to be able to utilise them with high viscosity fluids.The numerical model, exploiting the Finite Elements Method (FEM), was designed using the commercial software Comsol Multiphysics, and validated by comparing the steady state predictions with outcomes of filling experiments performed in industrial laboratories. Hence, subsequent numerical simulations were performed to investigate the transition from laminar to turbulent flow for shear-thinning fluids under different pressure conditions, in 3D time-dependent configurations. Results of the simulations, performed on a low fat yoghurt, show that laminar flow subsists within the whole filling system when the Metzner-Reed Reynolds number at the inlet section of the valve is lower than approx 444.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/18
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  • 71
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    Digitale Medien
    A Unified Approach for Modeling Three-Way Catalytic Converters and NOx Traps with a Minimum Set of Tunable Parameters (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 15 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The demanding legislation for vehicle emissions pushes the automotive industry to the commercialization of advanced exhaust systems. The careful design of each aftertreatment device fitted in exhaust line and the interactions with the engine management, makes modelling an important part of systems engineering for these applications. Almost all catalytic converter models that are found in the literature use tunable parameters which typically address the kinetic terms of chemical reactions. A great effort has been given to the definition of complex reaction schemes and mechanistic description of them in-vitro, in order to assist the advanced design of catalytic washcoats and explain their complex chemistry. This paper presents a systematic effort towards the modelling of advanced commercial exhaust treatment systems, using a unified approach for the different devices. The model used in this work describes the catalytic processes with global reactions, using apparent Arrhenius type rate expressions with L-H kinetics. The model is used to predict transient performance of commercial catalytic converters under legislated test conditions. During these tests the existing uncertainties and intrinsic variations of engine and catalyst operation make the robustness and flexibility of the model prominent targets. Comparison of computed and measured second-by-second emissions demonstrate a high level of modelling accuracy, adequate to fit the behavior of advanced commercial applications of three-way catalytic converters and NOx traps, using a minimum set of 3 tunable parameters for each device.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/15
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  • 72
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    Digitale Medien
    On-line Fault Detection and Isolation for State Space Models Using a Combination of Extended Kalman Filters and the Standardized Innovation Approach (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 27 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This paper presents a Fault Detection and Isolation (FDI) method for stochastic nonlinear dynamic systems. Our contribution consists of showing another method of tackling the problem of the physical origin diagnosis of faults by combining the technique based on the innovations and the technique using the multiple Kalman filters for a nonlinear dynamic system strongly non-stationary. The usefulness of this combination is the implementation of all the faults dynamics if the decision threshold on the standardized innovation exceeds a fixed value. In the other case, one filter is enough to estimate the process state. An algorithm is described and applied to a perfectly stirred chemical reactor functioning in a semi-batch mode. In this paper, the chemical reaction used is an oxido reduction one, the oxidation of sodium thiosulfate by hydrogen peroxide.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/27
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  • 73
    Digitale Medien
    Digitale Medien
    CFD Simulations for Continuous Flow of Bubbles through Gas-Liquid Columns: Application of VOF Method (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 9 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Hydrodynamics study of a continuous bubble chain rising through liquid column has been performed for laboratory scale bubble column using the volume-of-fluid (VOF) approach. The effect of operating and design parameters on the bubble size distribution and rise trajectory has been investigated for air-water system. For the same distributor, simulation results have indicated the formation of small bubbles at low superficial gas velocity and relatively large bubbles at higher velocities. The increase in the hole-size of distributor has shown similar behaviour. Analysis of bubble trajectories for different superficial gas velocities and distributors has demonstrated an oscillatory behaviour exhibited by small bubbles formed at low superficial gas velocity. A reasonable agreement between the predicted values of gas hold-up with the experimental work has validated the present model.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/9
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  • 74
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    Digitale Medien
    Estimating Output Variance in Closed Loop Systems (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 8 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This paper attempts to address a common difficulty encountered when trying to justify a process control revamp or upgrading project -- the ability to quantify potential savings/profits. A relatively simple procedure that is applicable to both continuous and digital controllers is described. Given models of the process and the controller, knowledge of the disturbance frequencies and their variances, the method is able to predict accurately the variance of the controlled output of linear control systems.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/8
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  • 75
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    Digitale Medien
    CFD Simulation of Fine Particle Gravity Separation in Hindered-settling Bed Separators (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 11 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In the modeling of hindered-settling bed separators, the published separation mechanisms are based on differences of particle density and size distributions, without the details of the complexity of particles-liquid interactions. A fluid dynamic model for the separator is developed using the Euler-Lagrangian approach of Computational Fluid Dynamics (CFD). Fluid motion is obtained from solving the movement of liquid governing equations. The damping effect on flow patterns caused by the movement of particles resulting in liquid-particle coupling is included in the models. Effects of particle size, particle density compositions, feed rate, feed water flow rate, and upward fluidizing water flow rate, etc., are simulated in the 2-D separation model. Flow pattern effects on the separation of fine particles in the separators with center downward-flow and side cross-flow feed systems are investigated.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/11
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  • 76
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    Digitale Medien
    Crisp and Fuzzy Optimisation Approaches for Water Network Retrofit (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 6 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Material reuse/recycle has gained much attention in recent years for both economic and environmental reasons. Process integration techniques for water network synthesis have evolved rapidly in the past decade. With in-plant water reuse/recycle, fresh water and wastewater flowrates are reduced simultaneously. In this work, linear programming and mixed integer linear programming models that include piping cost and process constraints are developed to retrofit an existing water network in a paper mill that was not originally designed with process integration techniques. Five scenarios are presented, each representing different aspects of decision-making in real process integration projects. The fifth scenario makes use of fuzzy optimisation to achieve a compromise solution that considers the inherent conflict between maximising water recovery and minimising capital cost for retrofit.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/6
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  • 77
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    Digitale Medien
    Mathematical Analysis of a Novel Formaldehyde Remediation Process (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 1 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The NASA low-temperature oxidation catalyst (Pt/SnO2), originally developed for space-based carbon dioxide laser applications has been recently adapted to address formaldehyde destruction in industrial smoke stack emission streams. A mathematical model is developed that can be used to correlate the observable chemistry occurring on the surfaces of a monolith with the volumetric flow rate of the gas and cross sectional area of catalyst surfaces as well as quantifying process design variables such as pressure or temperature of an exhaust gas stream.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/1
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  • 78
    Digitale Medien
    Digitale Medien
    Hedge's Ultimate Numerical Technique (HUNT) for Steady State Diffusion Problem (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 5 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A more realistic numerical technique hereafter known as Hegde's Ultimate Numerical Technique (HUNT) is developed and demonstrated on a one dimensional and a two dimensional steady state diffusion problem of heat transfer. The available numerical methods developed are based on finite difference technique neglecting the contribution of higher order terms in Taylor series expansion of the function leading to an approximation and the error in the solution. In the present effort of the HUNT, the optimization of the partial derivatives leads to the elimination of the error and justifies the stability and the convergence of the solution. The HUNT procedure based on the interface theory developed by the author, is capable of providing the ultimate optimum solution to all the partial derivatives considered as decision vectors. Even though the HUNT is demonstrated on one dimensional and two dimensional steady state diffusion equations, it does not require rigorous efforts to apply it to three dimensional problems of fluid flow and heat transfer. As pilot exercises the HUNT is demonstrated on a one dimensional circular fin and a two dimensional plate to obtain the temperature distribution. The result is compared with the analytical method and the finite volume method for which the results are available in the literature. To the knowledge of the authors, HUNT is both different and a unique example of its kind.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/5
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  • 79
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    Digitale Medien
    Prediction of Biomedical Waste Load at Centralized Treatment Facility (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 4 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The Local Municipal Corporation operates a centralized treatment facility (CTF) to facilitate effective and safe disposal of hazardous biomedical waste generated from various health care facilities (HCFs) in a region. Managing these wastes is a challenging task due to unpredictable variation in amount of waste received at a CTF. In this paper a mathematical model is presented that predicts the load on CTF as a function of bed occupancy of some representative hospitals in the region. Models are available to predict waste generated from a particular hospital in terms of bed occupancy; however, it is difficult to predict total waste received at CTF that also includes wastes from HCFs other than hospitals. To develop the model, data for the waste generated at source and for waste incinerated at CTF were collected for two consecutive years on daily basis. It was observed that two hospitals are representative of the rate of biomedical waste generation in the region from all HCFs. In two consecutive years, there were significantly different trends in overall waste incinerated at CTF. The reason for variation in waste load at CTF was observed to be due to uneven load on the HCFs in two consecutive years.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/4
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  • 80
    Digitale Medien
    Digitale Medien
    Enhancement in Sport, and Enhancement outside Sport (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2007, 1, art2 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: Sport is one of the first areas in which enhancement has become commonplace. It is also one of the first areas in which the use of enhancement technologies has been heavily regulated. Some have thus seen sport as a testing ground for arguments about whether to permit enhancement. However, I argue that there are fairness-based objections to enhancement in sport that do not apply as strongly in some other areas of human activity. Thus, I claim that there will often be a stronger case for permitting enhancement outside of sport than for permitting enhancement in sport. I end by considering some methodological implications of this conclusion.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art2
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  • 81
    Digitale Medien
    Digitale Medien
    Athlete or Guinea Pig? Sports and Enhancement Research (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2007, 1, art1 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: Bioethics has paid little attention to the issues raised by health in athletic competition, with the single exception of the use of prohibited performance enhancements. However, in competitive athletics, the treatment and prevention of athletic injury and the development of training programs designed to maximize athletic achievement share many characteristics with medical innovation and clinical research, and should be understood to constitute enhancement research.Athletes should, in at least some circumstances, be viewed as vulnerable research subjects, akin to desperate patients. Competitive athletes are often encouraged to sacrifice long-term health benefits for short-term gains; cultural mythology about sports and high-stakes financial investments at the organizational level in team sports exercise great influence on individual athletes' range of choices. Technological advances in training, equipment, and injury treatment serve to raise the bar in competitive athletics, in turn increasing not only the risks of harm but the level of expectation with regard to performance, injury, and recovery. It is common for athletes to seek, and teams to offer, intensive and innovative training regimens from which data are gathered, thus transforming innovation into research.As technology continues to enhance the prospects for athletic enhancement, it is time for bioethics to take a closer look at the way competitive athletics highlights the troubling questions posed by enhancement research.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art1
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  • 82
    Digitale Medien
    Digitale Medien
    Virtue Ethics and Prenatal Genetic Enhancement (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Studies in ethics, law and technology 1.2007, 1, art4 
    Details
    ISSN: 1941-6008
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Sociologie , Technik allgemein
    Notizen: In this paper I argue that the virtue ethics tradition can enhance the moral discourse on the ethics of prenatal genetic enhancements in distinctive and valuable ways. Virtue ethics prescribes we adopt a much more provisional stance on the issue of the moral permissibility of prenatal genetic enhancements. A stance that places great care on differentiating between the different stakes involved with developing different phenotypes in our children and the different possible means (environmental vs. genetic manipulation) available to parents for pursuing legitimate concerns of parental love and virtue. Key components of the virtue ethics account of morality, such as the Aristotelian account of happiness, love and the doctrine of the mean, provide an adequate basis for rejecting the claim that it is morally impermissible for parents to pursue (safe and effective) prenatal enhancements. Furthermore, there is good reason to believe that a virtue ethics account of morality could actually support the stronger claim that utilising such interventions can (in certain contexts) be morally required.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/selt/vol1/iss1/art4
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  • 83
    Digitale Medien
    Digitale Medien
    Dispatch Optimisation of Renewable Energy Generation Participating in a Liberalised Electricity Market (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 3, art1 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper focuses on dispatching of mixed generation portfolio of renewable energy (RE) and non-RE (firm) units. A genetic algorithm (GA) based rolling window approach is developed for solving economic dispatch (ED) problem. Profit maximisation ED problem is formulated and solved which also considers New Electricity Trading Arrangements for England and Wales (NETA) market features. In this problem, a penalty approach is used in order to consider intermittency problem of RE generation output. A single GA technique is also applied for solving the formulated problem. Of these, GA based rolling window approach achieved promising results for a Generator Company, which holds both renewable and fossil fuel units and participates in the short-term market trading. It is also shown that a Generator Company can get more profit by using the possibility of increase in generation output of RE sources from their forecast positions by combining both RE and non-RE units and participating in a NETA-like market trading. This approach allows to some extent the management of uncertainty problem of RE generation output, which also accounts risk associated with power non-delivery.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss3/art1
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  • 84
    Digitale Medien
    Digitale Medien
    A Parametric Unit Commitment Method for Revenue Adequacy Assessment (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 3, art3 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Unit commitment (UC), originally employed to minimize the generating cost of a vertically integrated utility, has become a basic tool for revenue adequacy evaluation by GENeration COmpanies (GENCOs). The strategic role of UC is apparent in those market environments where GENCOs are asked to internalize all costs and the relevant UC decisions within their day-ahead market bids. In this paper, a parametric UC method is presented to assess the convenience of making energy bids for marginal or nearly marginal generation units. The convenience is gauged by the basis of revenue adequacy that is on each unit's ability to cover all expenses and generate profits. Beside UC choices, the parametric UC procedure provides a market price behavior that would make it profitable to commit a certain unit for generation. A Monte Carlo simulation program is employed to find the probability that actual market prices will fulfill the revenue adequacy requirements. Market prices are handled as random variables with multivariate normal distribution, taking into account the correlation between prices at successive time periods. The parametric UC procedure and the Monte Carlo simulation are carried out by using reasonable data of generation units available to some Italian GENCOs.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss3/art3
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  • 85
    Digitale Medien
    Digitale Medien
    Resistance to Tracking of EPDM Aged by Gamma Irradiation under AC and DC Voltages (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 3, art2 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The present paper reports the results of a study of dielectric ageing of Ethylene Propylene Diene Monomer (EPDM) by gamma radiation. EPDM flat specimens were aged under gamma radiation with three different doses. Samples were irradiated in air up to 300 kRad with a dose rate of 51 kRad/h using a 60Co gamma source. The resistance to tracking on applying DC and AC voltage was examined. We found that the DC resistance to tracking is lower than the AC resistance. The tracking resistance under -ve DC voltages are lower than +ve DC values. With the increase in radiation dose, the DC and AC tracking resistances change in a non-linear way. The erosion depth and contact angle affected by radiation have been studied. In addition, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analyses were done, to analyze the morphological changes.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss3/art2
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  • 86
    Digitale Medien
    Digitale Medien
    Maximum Wind Power Capture by Sensorless Rotor Position and Wind Velocity Estimation from Flux Linkage and Sliding Observer (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 2, art3 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In recent developments wind power has been gaining rapid usage as an alternative source of electrical power and there is need to formulate optimized control schemes for power generation. This paper presents a sensorless maximum power point tracking control methodology for a wind power generation system. For the sensorless vector control a sliding mode observer is utilized in the estimation of the rotor speed while the rotor position is estimated based on the flux linkage. The Powell method is introduced to improve the efficiency of the permanent magnet synchronous generator (PMSG) d-axis current optimization. To ensure robustness of the proposed paradigm to parameter variations, the windmill loss coefficients determining the optimal rotor speed are identified online. Results of simulations confirm the effectiveness of the proposed method.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss2/art3
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  • 87
    Digitale Medien
    Digitale Medien
    Steady-State and Dynamic Behavior of a Single-Phase Self-Excited Induction Generator Using a Three-Phase Machine (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 3, art5 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper presents the steady-state and transient behavior of a single-phase self-excited induction generator (SEIG) using a three-phase machine with one shunt and one series excitation capacitors for resistive and inductive loads. The generation scheme consists of one three-phase delta connected induction machine and two capacitors - one connected in parallel with one winding and the other in series with a single-phase load. The dynamic model of the system has been developed as a hybrid model considering the stator phase currents in abc reference frame and the rotor currents in stationary d-q axes reference frame as state variables. The simulated and experimental results are presented for different dynamic conditions such as initiation of self-excitation, load perturbation and short-circuit. The simulated results of the steady-state analysis have been compared with the transient and experimental results and a close agreement between them indicates the accuracy and effectiveness of the approach.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss3/art5
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  • 88
    Digitale Medien
    Digitale Medien
    Expanding an Industrial Load Model for Short-Term Voltage Stability Analysis (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 4, art2 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The present work proposes an extended model representing part of a huge aluminum industry load for short-term voltage stability investigations in time domain. The efforts were concentrated in the expansion of the industrial power distribution system model including explicit representation of the main transformers, capacitors, feeders and induction motors. The extended model is validated through a comparison between computer simulation results and the industry/power system utility recordings. A real sequence of events which took place in the Brazilian North Power System in the year of 2002 causing a complete industry breakdown (loss of bulk supply) was considered here for this purpose.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss4/art2
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  • 89
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    Digitale Medien
    Robust Approach for Identification of Bad Data in State Estimation Using SLP Technique (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 4, art5 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper proposes a new approach for solving the state estimation problem. The approach is aimed at producing a robust estimator that rejects bad data, even if they are associated with leverage-point measurements. This is achieved by solving a sequence of Linear Programming (LP) problems. Optimization is carried via a new algorithm which is a combination of ``upper bound optimization technique" and ``an improved algorithm for discrete linear approximation". In this formulation of the LP problem, in addition to the constraints corresponding to the measurement set, constraints corresponding to bounds of state variables are also involved, which enables the LP problem more efficient in rejecting bad data, even if they are associated with leverage-point measurements. Results of the proposed estimator on IEEE 39-bus system and a 24-bus EHV equivalent system of the southern Indian grid are presented for illustrative purpose.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss4/art5
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  • 90
    Digitale Medien
    Digitale Medien
    A New Linear Fractional Transformation Based Approach to Power System Robustness Analysis (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 5, art2 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Large power systems are highly complex systems that defy predictions with any degree of certainty. In this paper, an analytical framework for the assessment of small signal stability under operating uncertainty is presented. A rigorous analysis framework for the description of uncertainty in operating conditions is suggested. Using structured singular value theory and optimization tools, techniques for robust stability analysis of complex power systems are then derived and a method to quantify the effect of parametric uncertainties on the stability of critical inter-area modes is presented. A computationally-efficient method for modeling parametric uncertainty based on linear fractional transformation (LFT) theory is investigated and tested. With this approach, it becomes possible to estimate the effects of variations in the parameters of major transmission resources on the nominal stability of critical inter-area modes.The use of the analysis methods is demonstrated on two systems: i) a two-machine test system, and ii) a two-area, 11-bus, 4-machine test system.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss5/art2
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  • 91
    Digitale Medien
    Digitale Medien
    Novel Configuration of 60-Pulse Voltage Source Converter for STATCOM Application (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 5, art7 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The proposed voltage source converter is composed of a series double bridge converter with an auxiliary circuit. The auxiliary circuit injects DC voltage via the mid point of the double bridge converter. The injection ratio and frequency are chosen to convert the standard 12-pulse into 60-pulse configuration without PWM or increasing the number of bridges, thus the voltage and current harmonic can fulfill the THD limit without a conventional filter. The converter is operated under fundamental frequency for the main bridges, thus its switching lose is low. The converter can be widely used in the STATCOM and HVDC system. The paper describes the principles and control strategies of the proposed converter. The operational feasibility of the proposed converter is verified by computer simulation using the PSCAD/EMTDC package.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss5/art7
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  • 92
    Digitale Medien
    Digitale Medien
    Iterative Fault Location Scheme for a Transmission Line Using Synchronized Phasor Measurements (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 6, art2 
    Details
    ISSN: 1553-779X
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This paper describes a new iterative method to locate fault on a single transmission line. The method uses synchronized voltage and current measurements from both line terminals. Using the positive sequence components of the pre-fault and the post-fault phasors, positive sequence source impedances at both terminals are first estimated. Using these source impedances and the line data, the positive sequence bus impedance matrix (Zbus) is formed. Using the properties of Zbus, an iterative algorithm is proposed to locate the fault. This algorithm is tested extensively with data obtained from the EMTP simulation of a long transmission line simulated with distributed parameters in the presence of fault resistance and CT saturation. The simulation results show that the method is very accurate and robust.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/ijeeps/vol8/iss6/art2
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  • 93
    Digitale Medien
    Digitale Medien
    Performance Analysis of Three Controllers for the Polymerisation of Styrene in a Batch Reactor (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 3 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The performance analysis of three advanced non linear controllers is the main focus of this paper. All three controllers are applied for the control of a batch polymerisation reactor which is defined by a very simple kinetic model for the polymerisation of styrene. This simple set of equations describing the polymerisation process is first solved using the sequential strategy i.e. Control Vector Parameterisation (CVP) technique within gPROMS to find optimal initial initiator concentrations and the reactor temperature trajectory necessary to yield desired polymer molecular properties (defined here as fixed values of monomer conversion and number average chain length) in minimum time. The sequential solution strategy has had limited application in solving optimisation problems for polymerisation in batch reactors, most researchers instead employing the Pontryagin's Maximum Principle (PMP) to solve optimal control problems involving these systems.The temperature trajectory obtained from the dynamic optimisation is used as the setpoint to be tracked by the three controllers: Dual Mode control with PID, which is representative of industrial practice, Generic Model Control (GMC) with Neural Networks as online heat release estimator, and Direct Inverse Control (DIC). Published work on the last two controllers as applied to the control of a batch polymerisation reactor is absent from the literature. When the performances of the different controllers are evaluated, it is seen that the GMC-NN controller performs better than the other two for the system under consideration.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/3
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  • 94
    Digitale Medien
    Digitale Medien
    CFD Diagnosis of the Cyclotol Manufacturing Plant: Product Quality and Process Operation (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 2 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The production of cyclotol, a military high explosive used in manufacture of aerial bombs, involves the multiphase mixing of molten TNT, RDX solid particles and water. Textural homogeneity of the final cyclotol mixture and near-zero water composition are critical requirements to minimize bomb-rejection rate and hence improved plant profitability. Although current data reveal significant statistical variation in product quality, detailed investigation of the complex mixing operation does not lend itself to physical experimentation due to the explosive nature of the process. This forestalls opportunities for improved process operation or re-design. To circumvent this constraint, a computational fluid dynamics (CFD) simulation of the industrial-scale process was carried out to understand how current mixing protocols impact on key in-tank profiles such as water draw-down, RDX particles suspension, turbulence kinetic energy, velocity magnitude, vector direction and water-entrainment. The analysis revealed that while the maximum impeller speed allowable to avoid water draw-down is 20 rpm, the minimum speed necessary to suspend the RDX particles for homogeneous mixing is 40 rpm. These opposing requirements are neither accommodated by the present mixing protocols nor achievable with the existing tank design. Even so, the 'mystery' of irrational cyclotol quality has been uncovered by a judicious use of CFD modeling and opened up the possibility of a revised tank design and optimal process operation for superior plant economics.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/2
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  • 95
    Digitale Medien
    Digitale Medien
    Enhanced Explicit Scheme to Solve Transient Heat Conduction Problem (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 4 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Improvement in accuracy without sacrificing stability and convergence of the solution to unsteady diffusion heat transfer problems by computational method of enhanced explicit scheme (EES), has been achieved and demonstrated, through transient one dimensional and two dimensional heat conduction. The truncation error induced in the explicit scheme using finite difference technique is eliminated by optimization of partial derivatives in the Taylor series expansion, by application of interface theory developed by the authors. This theory, in its simple terms gives the optimum values to the decision vectors in a redundant linear equation. The time derivatives and the spatial partial derivatives in the transient heat conduction, take the values depending on the time step chosen and grid size assumed. The time correction factor and the space correction factor defined by step sizes govern the accuracy, stability and convergence of EES. The comparison of the results of EES with analytical results, show decreased error as compared to the result of explicit scheme. The paper has an objective of reducing error in the explicit scheme by elimination of truncation error introduced by neglecting the higher order terms in the expansion of the governing function. As the pilot examples of the exercise, the implementation is aimed at solving one-dimensional and two-dimensional problems of transient heat conduction and compared with the results cited in the referred literature.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/4
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  • 96
    Digitale Medien
    Digitale Medien
    Advanced Modeling of Reactive Separation Units with Structured Packings (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 5 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Reactive separations combining mass transfer with simultaneous chemical reactions within a single column unit provide an important synergistic effect and bring about several advantages. The influence of column internals in reactive separations increases significantly, because these internals have to enhance both separation and reaction and maintain a sound balance between them. To solve this problem, a novel generation of column internals with enhanced mass transfer performance and low pressure drop has been created. Among them, corrugated packings of the regular type or structured packings have gained a wide acceptance.This paper gives a state-of-the-art review of the structured packings modeling methods, focusing on two innovative and particularly promising approaches. The first of them is based on the application of CFD, whereas the second one employs the idea of hydrodynamic analogy between complex and simple flow patterns. Both approaches are illustrated with several case studies.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss1/5
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    Estimation of Moisture Ratio of a Mushroom Undergoing Microwave-vacuum Drying Using Artificial Neural Network and Regression Models (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 25 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The drying rate of a mushroom undergoing microwave-vacuum (MV) drying (MVD) was controlled by moisture dissipation and was dependent on vacuum pressure levels. The main objective of this work was to develop artificial neural network (ANN) model to predict moisture ratio of MV-dried mushrooms. One-hidden-layer feed-forward ANN models were trained and validated with experimental data. The Levenberg-Marquardt algorithm was utilized in regulating the ANN model weights and biases. Inputs for ANN models were vacuum pressure and drying time. Output from ANN models was moisture ratio at a given drying time. Reduced chi-square (X 2) and root mean square error (RMSE), and residual sum of squares (RSS) of the results from ANN models were calculated and compared with those of a modified Page's model (an experimental-based mathematical model), which is commonly used in the literature. The X 2, RMSE, and RSS of the ANN model (2.272 x 10 -5, 4.023 x 10 -3, and 3.204 x 10 -3, respectively) were found to be lower than those of the modified Page's model (6.692 x 10 -4, 2.561 x 10 -2, and 12.98 x 10 -2, respectively). These results indicate that the feed-forward ANN model represented the drying characteristics of mushrooms better than the modified Page's model. Therefore, the ANN model could be considered as a better tool for estimation of the moisture content of mushrooms than by the modified Page's model.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/25
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Forecasting Influent-Effluent Wastewater Treatment Plant Using Time Series Analysis and Artificial Neural Network Techniques (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 3 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: We consider the problem of predicting the future behavior of wastewater treatment plant quality indicators by creating prediction models using historical plant data. One of the main aims of this work is to be able to predict plant operational situations in advance so that corrective actions can be taken in time. Sets of historical plant data, such as BOD, COD and TSS were collected for a local wastewater treatment plant in Doha, the capital of the State of Qatar. These variables characterize the performance of any wastewater treatment plant and can be considered as quality indicators of the plant performance. Data were collected over a period of 4 years for the influent and effluent streams of the station. The plant influent and effluent predictions were performed using different techniques. These include time-series analysis, where the ARIMA (Autoregressive Integrated Moving Average) model was implemented in this case, and two Artificial Neural Networks (ANN) algorithms, namely Adaptive Linear Neuron networks (ADALINE) and Multi-layer Feedforward (ML-FF) neural networks. The predictions from the three techniques were presented and compared. The ML-FF model predictions proved to be more reliable than that of the equivalent ARIMA predictions followed by the ADALINE predictions, particularly for the finial effluent stream variables.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss3/3
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    Simulation of Free Chlorine Decay and Adaptive Chlorine Dosing by Discrete Time-Space Model for Drinking Water Distribution System (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 3 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An ideal drinking water distribution system (DWDS) must supply safe drinking water with free chlorine residual (FCR) in the form of HOCl and OCl- at a required concentration level. The FCR as a disinfectant decreases over time due to chemical reactions in the bulk phase and at the pipe wall in the DWDS. In order to supply drinking water with the FCR concentration within the safety range of 0.2-0.6 mg/l at the points of water consumption, it is important to develop a dynamic model of the FCR using a discrete time-space model (DTSM) that accounts for free chlorine transport in the axial direction by convection, diffusion and the decay kinetic. A DTSM has been developed using Finite Difference Method (FDM) to predict the FCR in single pipes in the DWDS. The DTSM has been computed using Matlab 7.0.1 and tested with step inputs and rectangular pulse inputs to estimate the FCR at any point in the pipes over time. Data found in the literature have been used to validate the DTSM. The modelling and simulation study shows that the water velocity significantly affects the FCR concentration distribution along the pipe. Due to the fluctuation of the drinking water demand, a model-based adaptive chlorine dosing scheme is proposed to control the proper injection of chlorine.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss2/3
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Nonlinear Process Operability Analysis Based on Steady-State Simulation: A Case Study (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 6 
    Details
    ISSN: 1934-2659
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In this paper, the operability of a high-purity distillation column is presented. This process is known to be difficult to control and operate due to the high degree of nonlinearity of the process. The analytical framework used to assess the process operability are the regions of steady-state attainability, recently developed by Rojas et al (2006). This framework is selected because it allows one to assess the viability of applying linear control to a nonlinear process solely based on the process nonlinear steady-state information. In this approach, two operating regions are defined in both input and output spaces, which provide an indication of the inherent difficulty of controlling the nonlinear process using linear output feedback. In order to integrate this operability analysis in process design practice, the analysis is based on a numerical steady-state simulation of the column using ASPEN PLUS®. By using ASPEN Sensitivity Analysis Tool that varies the column inputs across a pre-defined Available Input Space, the steady-state nonlinear map of the column outputs can be generated. Based on these simulation results, the regions of steady-state attainability can be obtained and used to provide insights to the operability properties of this highly non linear system.
    Materialart: Digitale Medien
    URL: http://www.bepress.com/cppm/vol2/iss2/6
    Standort Signatur Erwartet Verfügbarkeit
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