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  • Modelling
  • Springer  (29)
  • American Institute of Physics
  • American Institute of Physics (AIP)
  • 2005-2009  (5)
  • 1990-1994  (24)
  • 1960-1964
  • 1955-1959
  • 1950-1954
  • 1
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    Springer
    In:  Berlin, Springer, vol. 3, no. ALEX(01)-FR-77-01, AFTAC Contract F08606-76-C-0025, pp. 329, (ISBN: 3-540-27983-0, XII + 238 p., 77 illus., 13 in colour with CD-ROM)
    Publikationsdatum: 2006
    Beschreibung: Contents: Data Analysis in Earth Sciences - Introduction to MATLAB - Univariate Statistics - Bivariate Statistics - Time-Series Analysis - Signal Processing - Spatial Data including Digital Elevation Models - Image Processing including Processing and Georeferencing of Satellite Images - Multivariate Statistics; IfGW Uni Potsdam
    Schlagwort(e): Data analysis / ~ processing ; Modelling ; software ; Textbook of geophysics ; Statistical investigations ; digital signal analysis (also DSP) ; DSP ; Time series analysis ; Digital elevation model ; geographic ; coordinates ; Mapping ; Toolbox
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  • 2
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    Springer
    In:  Amsterdam, Springer, vol. 1, pp. 225, (1-4020-3353-2)
    Publikationsdatum: 2005
    Schlagwort(e): Tsunami(s) ; Earthquake risk ; Earthquake precursor: prediction research ; Review article ; Early warning systems (earthquakes, volcanic eruptions, tsunamis etc.) ; Modelling ; NATHAZ ; measurement, ; tsunami ; model, ; data ; assimilation, ; data ; inversion, ; tsunami ; warning, ; tsunameters, ; forecast, ; hazard ; mitigation
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  • 3
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    Springer
    In:  Professional Paper, Perspectives in Modern Seismology, Berlin, Springer, vol. 105, 223 pp., no. 231, pp. 13-30, (ISBN: 3-540-23712-7)
    Publikationsdatum: 2005
    Schlagwort(e): Earthquake risk ; Site amplification ; Strong motions ; Earthquake engineering, engineering seismology ; Synthetic seismograms ; NOISE ; Nakamura ; Modelling ; Cologne ; DFNK ; Faecke ; Facke
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  • 4
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    Springer
    In:  Bull., Polar Proj. OP-O3A4, Perspectives in Modern Seismology, London, Springer, vol. 201, no. XVI:, pp. 169-184, (ISBN: 3-540-23712-7)
    Publikationsdatum: 2005
    Schlagwort(e): Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Geodesy ; Finite Element Method ; Modelling ; Three dimensional ; Seismology ; Early warning systems (earthquakes, volcanic eruptions, tsunamis etc.) ; Bucharest ; Romania ; Earthquake risk
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2017-04-04
    Beschreibung: Ground deformation occurring on the southern flank of Mt Etna volcano during the JulyAugust 2001 eruption was monitored by GPS measurements along an EW profile crossing the fissure system. This profile was measured eight times during the eruption, using the 'stop and go' semi-kinematic technique. Horizontal and vertical displacements between GPS surveys are reported for each station. The most significant event is a deformation episode occurring during the first week of the eruption, between 2527 July. Displacements were measured on benchmarks close to the eruptive fissure and the tensile 1989 fracture. Data inversions for measured displacements were performed using the Okada model. The model shows the narrowing of the 2001 dyke accompanied by a dextral dislocation along an east-dipping fault, parallel to the 1989 fracture.
    Beschreibung: Published
    Beschreibung: 336-341
    Beschreibung: partially_open
    Schlagwort(e): GPS ; Ground deformation ; Modelling ; Volcano monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Format: 513 bytes
    Format: 467775 bytes
    Format: text/html
    Format: application/pdf
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Engineering with computers 10 (1994), S. 12-21 
    ISSN: 1435-5663
    Schlagwort(e): Aluminium electrolysis ; Expert systems ; Modelling ; Simulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Notizen: Abstract A workstation-based simulator of an aluminium electrolytic cell has been constructed. A mathematical model of the cell is integrated with a database and a knowledge base, and the simulator serves as a tool for the training of personnel and for research related to cell dynamics and cell control. When used in conjunction with an expert system, it provides a powerful decision-making tool or an efficient supervisory system. The mathematical model, the simulator itself, the user environment, the interactive simulation procedure as well as examples of the use of the simulator are presented in detail.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Annals of operations research 54 (1994), S. 97-117 
    ISSN: 1572-9338
    Schlagwort(e): Modelling ; interconnection ; side payments ; game theory ; environment ; transboundary pollution ; multiple objective games ; repeated games ; tensor games ; tradeoff ; Pareto equilibrium ; Nash equilibrium ; Folk theorem ; prisoners' dilemma ; JEL C70 ; Q28
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Notizen: Abstract Some features of international environmental problems are considered. A basic problem is to induce countries to adopt a cooperative approach. One of the instruments to induce countries to cooperate is an exchange of concessions in fields of relative strengths, such as swapping trade concessions for cooperation on international environmental problems. This instrument will be modelled in this paper with tensor games. Both tradeoff and non-tradeoff tensor games will be addressed, with emphasis on tradeoff tensor games with linear strict weights. The relationship between the Pareto equilibria of a non-tradeoff tensor game and the Nash equilibria of the associated tradeoff tensor games will be studied. Due to structural similarities between tensor games and repeated multiple objective games, some attention will also be paid to the latter. Relationships between objects related to Folk theorems for the tradeoff tensor game with completely additive weights and the corresponding objects for its constituting isolated games will be studied. Since many international environmental problems have prisoners' dilemma characteristics, it is analyzed how interconnection may enhance cooperation in prisoners' dilemma games.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Neural computing & applications 2 (1994), S. 183-204 
    ISSN: 1433-3058
    Schlagwort(e): Neural nets ; Genetic algorithms ; Attitude control ; Euler equations ; Adaptive control ; Satellites ; Modelling ; Prediction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract It has previously been demonstrated that for smooth dynamic systems, using relatively few sample points from a single trajectory, a neural network can be trained to perform very accurate short-term prediction over a large part of the phase space. In this paper, we exploit the capability of a Locally Predictive Network (LPN) to derive an adaptive control architecture for a satellite equipped with controllable, bidirectional thrusters on each of the three principal axes. It is assumed that a hardware implementation of the neural network is available. The inputs for the network are a small history of system states up to the present time and a set of current control inputs, the outputs are the next system state. Once the LPN has been trained successfully, at each time step a genetic algorithm searches the space of hypothetical control inputs. Given a set of control signals, the LPN is used to predict the state of the system at the next sample point. This enables the ‘fitness’ of each set of hypothetical control torques to be evaluated very rapidly. In effect, the genetic algorithm determines a satisfactory solution to the inverse kinematic problem in time to apply the solution (set of control torques) at the next control point. With the exception of the neuromodelling (which is repeated only when the system dynamics change), the whole process is then repeated. The results presented indicate that such an architecture is easily able to master the attitude control problem for arbitrary slew angles, with arbitrary a priori unknowndynamics and noise in the sensor system.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    The international journal of advanced manufacturing technology 9 (1994), S. 375-381 
    ISSN: 1433-3015
    Schlagwort(e): Control applications ; Digital signal processing ; Modelling ; Process control ; Simulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract An enhanced Petri-net class is defined as a model suitable for describing sequence control. A sequence controller is proposed and both its software and hardware design are presented and evaluated. The use of a digital signal processor as a fast CPU in addition to suitable algorithms allows the controller to be used for real-time applications.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    AI & society 8 (1994), S. 17-28 
    ISSN: 1435-5655
    Schlagwort(e): Expert systems ; Modelling ; Qualitative modelling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract Fundamental assumptions behind qualitative modelling are critically considered and some inherent problems in that modelling approach are outlined. The problems outlined are due to the assumption that a sufficient set of symbols representing the fundamental features of the physical world exists. That assumption causes serious problems when modelling continuous systems. An alternative for intelligent system building for cases not suitable for qualitative modelling is proposed. The proposed alternative combines neural networks and quantitative modelling.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 172 (1993), S. 251-256 
    ISSN: 1432-1351
    Schlagwort(e): Foraging ; Optimality ; Modelling ; Energetics ; Apis mellifera
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The analysis of foraging behaviour with optimization models has been used widely in recent years. Studies on nectar collection in the honeybee have been among the examples cited repeatedly in favour of the approach. These studies (based on the “energy-maximizing” hypothesis) have now been challenged in a recent paper by Varjú and Núñez (1991). These authors claim that the observed behaviour can be explained without reference to this hypothesis and even without energetic considerations. Moreover, they maintain that the observations support the “information-exchange” hypothesis, an alternative preferred by the authors. In this paper the arguments used by Varjú and Núñez (1991) are shown to be erroneous in several respects. A recurrent problem results from confusing causal and functional questions. In addition, their analysis fails to distinguish between statistically inferred and normative models, misinterprets the nature of observations and misrepresents the predictions of the energy-maximizing hypothesis. Whereas the information-exchange hypothesis is a plausible alternative, the evidence cited by the authors cannot distinguish between the two competing explanations but rather suggests that energy is important. Varjú and Núñez (1991) do not specify the meaning of “information” so that their hypothesis cannot generate specific predictions.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    The international journal of advanced manufacturing technology 8 (1993), S. 329-343 
    ISSN: 1433-3015
    Schlagwort(e): S-shaped learning curve ; Industrial innovations ; Modelling ; Forecasting ; Simulation modelling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Algorithms are derived for the four-parameter transfer function S-shaped curve, using a least-squared-error (LSE) method for an exponential function. The S-shaped curve is just one in a family of industrial dynamics learning-curve models of increasing complexity which may be used to replicate and forecast the start-up of industrial innovations. Controlled experiments are undertaken, via simulation of “message” and “noise”, to test the modelling and forecasting capabilities of the algorithms. A number of strategies are introduced to improve forecasting performance, such as “boots-trapping”, sequential and parallel adaptation, and alternatively adopting the simplified three-parameter S-curve model. Four examples of modelling industrial innovations via the transfer function learning curve models are presented. The paper concludes that although there is now the capability to model the general four-parameter S-curve, its applications are limited. This is because simpler (and hence less accurate) transfer function models tend to be more robust.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Neural computing & applications 1 (1993), S. 17-22 
    ISSN: 1433-3058
    Schlagwort(e): Adaptive architecture ; Construction ; Modelling ; Neural networks ; Pruning
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract A constructive algorithm is proposed for feed-forward neural networks which uses node-splitting in the hidden layers to build large networks from smaller ones. The small network forms an approximate model of a set of training data, and the split creates a larger, more powerful network which is initialised with the approximate solution already found. The insufficiency of the smaller network in modelling the system which generated the data leads to oscillation in those hidden nodes whose weight vectors cover regions in the input space where more detail is required in the model. These nodes are identified and split in two using principal component analysis, allowing the new nodes to cover the two main modes of the oscillating vector. Nodes are selected for splitting using principal component analysis on the oscillating weight vectors, or by examining the Hessian matrix of second derivatives of the network error with respect to the weights.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Neural computing & applications 1 (1993), S. 268-279 
    ISSN: 1433-3058
    Schlagwort(e): Neural nets ; Dynamic systems ; Modelling ; Euler equations ; Chaos ; Prediction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract In contrast to recent work aimed at using neural networks for relatively ‘long term’ prediction of time series, this paper examines how neural networks designed for short term prediction can form very good approximation models, valid over a large region of the phase space, after having been trained on as few as 500 pointsfrom a single trajectory of the underlying dynamic system. This is illustrated using four dynamic systems of increasing complexity, including a simple chaotic system and a more realistic system describing rigid body rotation using orthogonal torques under a chaotic control regime.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 35 (1993), S. 61-66 
    ISSN: 1573-0867
    Schlagwort(e): Modelling ; pH buffer capacity ; phosphate rock ; soil pH ; soil moisture content
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract An incubation experiment was carried out under glasshouse conditions to determine the ability of the Kirk and Nye model to predict the dissolution of a reactive phosphate rock in an acidic soil. The model accurately predicted the extent of the dissolution over time. However, the predictions were found to be highly sensitive to soil pH, pH buffer capacity and soil moisture content. The procedures used to measure these parameters need to be closely examined when using the model. Soil pH buffer capacity should be defined over a restricted pH range and the soil moisture content should be closely monitored over time.
    Materialart: Digitale Medien
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  • 16
    ISSN: 1432-1254
    Schlagwort(e): Insect development ; Soil temperature ; Modelling ; Egg hatch ; Corn rootworm
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geographie , Physik
    Notizen: Abstract A model for egg hatching of the western corn rootworm,Diabrotica virgifera virgifera LeConte, was tested at several locations in Ontario, Canada, during the 1989 and 1990 seasons. The model required soil temperatures as input and was tested using measured and modelled data. Modelled soil temperatures at 5 and 10 cm depths were obtained from empirically and physically based models. The physically based model provided better estimates of soil temperatues, but both models slightly underestimated the temperatures. Predicted egg hatching, using measured and modelled soil temperature at 5 and 10 cm depths for all locations, compared reasonably well with the observations of egg hatching. When using modelled soil temperatures, the egg developmental model performed better using soil temperatures from the physically based model. However, both soil temperature models provided sufficiently accurate temperature values for use in the egg developmental model. Unlike the empirically based model, the physically based model was not site-specific and its application to larger areas appeared feasible.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 31 (1993), S. 569-575 
    ISSN: 1741-0444
    Schlagwort(e): Cardiovascular system ; Flow rate ; Lower-body negative pressure ; Modelling ; Simulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The paper reports a theoretical investigation into the effects of lower-body negative pressure on blood flow through the human cardiovascular system. The human cardiovascular system is modelled as a closed network of arteries, arterioles, capillaries, venules and veins of different lengths and cross-sections. The pumping action is provided by the contraction of the ventricles. The model has been analysed using the finite-element method. The pertinent equations incorporating the effects of lower-body negative pressure for the pressures and flow velocities have been derived, and the quantitative results have been computed. Percentage changes in flow velocities, pressure drops and conductances under the application of lower-body negative pressure in the various segments and organs of the entire cardiovascular system are obtained. The lower-body negative pressure has no effect on the flow rates in carotid, ulnar and coronary arteries, nor on the supply of blood to the upper extremities, kidneys, spleen and liver. The major effects are found in the lower extremities.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Annals of biomedical engineering 20 (1992), S. 181-194 
    ISSN: 1573-9686
    Schlagwort(e): Ventilation ; Square-wave hypoxic transients ; Sustained hypoxia ; Modelling ; Dynamic end-tidal forcing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract A two-component dynamic model was used to describe the ventilatory response to sustained hypoxia in humans. One component (Xs) represents the stimulating effects of hypoxia and the other component (Xd), the hypoxic ventilatory decline. The total ventilatory response to hypoxia is represented by the sum of the two components. A nonlinearity is included to account for the nonlinear steady-state ventilatory response to hypoxia. A sensitivity analysis of the model indicates that, with a step change in $$F_{ETO_2 }$$ as the input, all the parameters can be estimated from the data except for the nonlinearity. The relative sensitivity of the parameters from the model analysis was confirmed in an experimental study. However, comparing steps into hypoxia versus steps out of hypoxia we found a decrease in the gains of both components. The most likely explanation for the decrease in the gains is that the combination of Xs and Xd is not entirely additive. Other models may be required to completely describe the ventilatory response to inputs more complex than steps.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 30 (1992), S. 656-659 
    ISSN: 1741-0444
    Schlagwort(e): Compliance ; Echo-Doppler ; Mitral valve ; Modelling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 30 (1992), S. 576-583 
    ISSN: 1741-0444
    Schlagwort(e): Arterial bifurcation ; Digital angiography ; Image processing ; Modelling ; Reconstruction ; Segmentation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The paper presents a method to model an arterial bifurcation from a pair of X-ray angiographic images. It is the initial step of a reconstruction process aiming at detecting and quantifying abnormal sites located on bifurcations. The method proposed consists of two steps. First, each image is independently segmented to extract the vessels in the images. The algorithm uses dynamic programming first to find the bifurcation centrelines from the original images, and secondly to extract vessel edges from the morphological gradient images, under a constraint of parallelism with the previously detected centrelines. Then, a three-dimensional bifurcation model is built by adapting cylinders around the three-dimensional bifurcation centrelines. These cylinders are obtained as a stack of binary orientable ellipses fitted to the projection densities in the corresponding cross-sections. Results obtained on simulated data, phantom and femoral bifurcations are displayed.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Lasers in medical science 6 (1991), S. 373-378 
    ISSN: 1435-604X
    Schlagwort(e): Heat necrosis ; Modelling ; Nd-YAG laser ; Dog aorta
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract A model has been developed to calculate distal tissue necrosis in vascular tissue after application of a 100μ laser pulse from a Nd-YAG laser (5 kW peak pulse power on a 0.13 mm2 spot size). The model assumes that the temperature profile in the tissue is proportional to the laser light fluence rate and that the distal tissue necrosis depth is that depth in the tissue where there is a temperature increase of 42 °C minus the etch rate (ablation depth per laser pulse). The fluence rate has been calculated using the diffusion approximation to the radiative transport equation. The tissue optical parameters (absorption and reduced scattering coefficients) have been derived from published data. The etch rate used (10μm per pulse) is derived from in vivo experimental results. The model predicts a damage depth varying between 0 and 2.33 mm (mean 1.10 mm) and this is compared with an experimental result (0.77 mm) in dog aorta.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 27 (1991), S. 215-231 
    ISSN: 1573-0867
    Schlagwort(e): Modelling ; water flow ; nitrogen transport ; nitrogen cycle ; root uptake
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A model is presented for the simulation of water flow, heat flow, and nitrate and ammonium transport. Two approaches are used for modelling plant water uptake as well as for plant nitrogen uptake. Nitrogen transformations are accounted for in a very simple way. This paper focuses mainly on water flow modelling, solute transport, and water uptake. Richards' equation is used to model water flow in layered soil profiles with a great variety of boundary conditions. Solute transport is simulated with either a simple convection dispersion equation or with a two-region physical non-equilibrium model to distinguish between mobile and immobile water and solute exchange between these two regions. A macroscopic sink term is added to Richards' equation to account for plant water uptake. This term can be calculated along two different approaches, one of which is based on the concept of root water potential. The root water potential is then continuously optimized to minimize the difference between the climatic demand and the uptake rate. Simulation results are compared with field data from the Netherlands to illustrate the degree to which the model is able to predict water flow, solute transport and plant water uptake. The root water potential optimization model seems to provide the best prediction of water distribution. In particular the shape of the profile, revealing uptake patterns, is quite well reproduced with this model. Comparison of simulated and observed water content profiles seems also to reveal the presence of preferential pathways. The comparisons show also how predicted solute distributions can be improved by using a two-region approach rather than a simple convection-dispersion model.
    Materialart: Digitale Medien
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    International journal of biometeorology 35 (1991), S. 239-251 
    ISSN: 1432-1254
    Schlagwort(e): Modelling ; Ecology ; Response functions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geographie , Physik
    Notizen: Abstract This article describes the further development and new applications of the already well-known method of response functions. This method is used to present the quantitative evaluation of the reactions of various ecological and biological systems to environmental impacts. Two ecological problems were chosen as examples: the model of growth and development of cereal crops and the model of pollutant dynamics in the elementary ecosystem. In each case the results are given of the evaluation of parameters and the testing of models. It is shown that the method of response functions allows resolution of the wide range of ecological problems with sufficient accuracy, and some new theoretical results are presented. For example, based on the existing hypotheses of higher plant development, a biological time scale has been worked out. The method was elaborated to determine the minimum time of development, which is a genetically stipulated characteristic of a species and is realized when all environmental factors are optimal.
    Materialart: Digitale Medien
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 86 (1991), S. 414-418 
    ISSN: 1432-1939
    Schlagwort(e): Daphnia ; Modelling ; Energy allocation ; Starvation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Models incorporating the energetics of individual daphnids (Cladocera) have been developed to predict the effect of environmental variables, particularly food availability, on population dynamics. One of them, that of Kooijman (1986), assumes that all assimilated energy enters a storage compartment prior to use in production and metabolism, and that under starvation the stores are used to support maintenance, reproduction and somatic growth, in that order of priority. This predicts that, under starvation, reproduction and growth will continue for a time, and that after they cease death will be immediate. Another model, that of McCauley et al. (1990), assumes that assimilated energy is used directly for maintenance and production, and that stores are accumulated to support maintenance metabolism under starvation. This predicts that growth and reproduction should cease immediately upon starvation and that death will not be immediate. We have carried out laboratory experiments, manipulating starvation time, on Daphnia magna to distinguish between these two models. The results support features of both models in that reproduction, but not growth, ceases upon starvation. We therefore developed a third model in which both maintenance and growth are supported from stores under starvation, with maintenance taking priority over growth under these conditions.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 32 (1991), S. 573-578 
    ISSN: 1612-1112
    Schlagwort(e): Continuous counter-current chromatography ; Preparative scale ; Carbohydrates ; Modelling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The separation of industrial carbohydrate feedstocks using a preparative scale, moving port, semi-continuous, counter-current, chromatographic refiner (SCCR) has been carried out successfully. Over 90% product-purities at throughputs up to 32.3 kg sugar solids m−3 resin h−1 were achieved. The fructose and glucose-rich product concentrations reached 13% w/v and 25.4% w/v respectively. The continuous operation was simulated successfully using the “theoretical plate” modelling approach. Good agreement between experimental and simulated profiles was obtained.
    Materialart: Digitale Medien
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Journal of intelligent and robotic systems 3 (1990), S. 379-392 
    ISSN: 1573-0409
    Schlagwort(e): Modelling ; manufacturing systems ; approximate method ; queuing network ; birth-death approach ; queues
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau
    Notizen: Abstract An approximation method for modelling a manufacturing system is introduced. The system is considered as a queueing network, where each queue is limited in size, and interarrival and processing times are exponentially distributed. The birth-death approach is considered and an approximation method to reduce the dimension of the model is developed. The results are the marginal probability distribution of the number of units in each queue; other performance indices, such as mean queue lengths, utilizations of the working stations, and throughput can be easily obtained. The general procedure is applied to model, for example, queues in tandem, a split node, and a more complex network of queues. Simulation and, when possible, comparison with the exact solution show an acceptable error level of the proposed method.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 27
    ISSN: 1432-2242
    Schlagwort(e): Genetic effects ; Modelling ; F3 generation ; Single-seed descent
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A design and model are presented to allow the prediction, in early generations, of the mean and distribution of recombinant inbred lines derived from a cross between two parental populations or partially inbred lines. The procedure has been tested in autumn-sown onions (in the UK) using a wide cross between the openpollinated Japanese cultivar, Senshyu, and a partially inbred line derived from the European cultivar, Rawska. The early generations used for prediction included the first self-pollinated generation of the two parental populations and the F3 generation produced from the hybrid population. The predictions were tested by reference to the field performance of a random array of inbred lines, which were produced by single-seed descent (SSD) and had been selfed for three generations. The early generations, used for prediction, and a sample of SSD lines were raised alongside each other in each of two seasons. Within each season, good agreement was found between the predicted and observed performance of the recombinant inbred lines for three characters — yield, quality and maturity. This is used as evidence of the validity of the genetical model and the assumptions made. The effects of genotype x environment interactions prevented predictions made in one season being reliably applied to those made in the other and, therefore, reduce the attraction of this type of prediction study to the plant breeder.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 28 (1990), S. 15-23 
    ISSN: 1741-0444
    Schlagwort(e): Computer simulations ; Control strategies ; Modelling ; Motor behaviour ; Stretch reflex ; Voluntary movements
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract A nonlinear model for the stretch reflex has recently been used to study the interactions between voluntary and reflex controls during fast, targeted movements. The present study explores the topography of a ‘behaviour space’ generated by computer simulations of this model under various combinations of values for the gain parameters and time constants in the model's feedback loops. In general, we define a behaviour space to be any set of behavioural characteristics of the simulated movement, such as movement time, peak acceleration or peak velocity. The mathematical model can therefore be viewed as an M×N dimensional map from its parameter space N to a behaviour space M. Here, a one-dimensional behaviour space is explored. This provides a method for quantitatively comparing the different control strategies that might be employed by the nervous system for integrating reflex and descending signals during fast, voluntary movements. The results indicate that an optimal strategy will employ proprioceptive feedback as a means of fine-tuning the braking and clamping activities of fast, goal-directed movements and that descending signals are primarily important for initiating the movement and for controlling reciprocal patterns of muscle activity during the end phase of the movement.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 29
    ISSN: 1741-0444
    Schlagwort(e): Aortic valve ; Coherence function ; Heart sounds ; Heart/thorax acoustic system ; Mitral valve ; Modelling ; Spectral analysis ; Transfer function
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract A system model based on the simultaneous recording and analysis of the intracardiac and thoracic phonocardiograms to estimate the time-varying properties of the heart/thorax acoustic system of the dog is described. The presence of instrumental noise in the recording of intracardiac phonocardiograms is characterised, and it is demonstrated that its effect on the estimate of the transfer and coherence functions of the system can be quantified and corrected. Application of the model to study the spectral characteristics and the acoustic transmission properties of the mitral component M1 of the first heart sound and of the aortic component A2 of the second heart sound in the dog shows that the heart/thorax acoustic system acts like a bandpass filter having a higher attenuation for A2 than for M1. Between 20 and 100 Hz, the mean attenuation of M1 is 30 dB while that of A2 is 46 dB. Above 100 Hz, the attenuation slope is—12 dB per octave for M1 and—6 dB per octave for A2.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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