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  • 1
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    Mobile Device Based Dynamic Key Management Protocols for Wireless Sensor Networks (2015)
    Hindawi
    Details
    Publication Date: 2015-08-17
    Description: In recent years, wireless sensor network (WSN) applications have tended to transmit data hop by hop, from sensor nodes through cluster nodes to the base station. As a result, users must collect data from the base station. This study considers two different applications: hop by hop transmission of data from cluster nodes to the base station and the direct access to cluster nodes data by mobile users via mobile devices. Due to the hardware limitations of WSNs, some low-cost operations such as symmetric cryptographic algorithms and hash functions are used to implement a dynamic key management. The session key can be updated to prevent threats of attack from each communication. With these methods, the data gathered in wireless sensor networks can be more securely communicated. Moreover, the proposed scheme is analyzed and compared with related schemes. In addition, an NS2 simulation is developed in which the experimental results show that the designed communication protocol is workable.
    Print ISSN: 1687-725X
    Electronic ISSN: 1687-7268
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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  • 2
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    Determination of Nicotine in Tobacco by Chemometric Optimization and Cation-Selective Exhaustive Injection in Combination with Sweeping-Micellar Electrokinetic Chromatography (2015)
    Hindawi
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    Publication Date: 2015-05-27
    Description: Nicotine is a potent chemical that excites the central nervous system and refreshes people. It is also physically addictive and causes dependence. To reduce the harm of tobacco products for smokers, a law was introduced that requires tobacco product containers to be marked with the amount of nicotine as well as tar. In this paper, an online stacking capillary electrophoresis (CE) method with cation-selective exhaustive injection sweeping-micellar electrokinetic chromatography (CSEI-sweeping-MEKC) is proposed for the optimized analysis of nicotine in tobacco. A higher conductivity buffer (160 mM phosphate buffer (pH 3)) zone was injected into the capillary, allowing for the analytes to be electrokinetically injected at a voltage of 15 kV for 15 min. Using 50 mM sodium dodecyl sulfate and 25% methanol in the sweeping buffer, nicotine was detected with high sensitivity. Thus, optimized conditions adapted from a chemometric approach provided a 6000-fold increase in the nicotine detection sensitivity using the CSEI-sweeping-MEKC method in comparison to normal CZE. The limits of detection were 0.5 nM for nicotine. The stacking method in combination with direct injection which matrix components would not interfere with assay performance was successfully applied to the detection of nicotine in tobacco samples.
    Print ISSN: 2090-8865
    Electronic ISSN: 2090-8873
    Topics: Chemistry and Pharmacology
    Published by Hindawi
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  • 3
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    A Novel Framework Based on ACO and PSO for RNA Secondary Structure Prediction (2013)
    Hindawi
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    Publication Date: 2013-09-12
    Description: Prediction of RNA structure is a useful process for creating new drugs and understanding genetic diseases. In this paper, we proposed a particle swarm optimization (PSO) and ant colony optimization (ACO) based framework (PAF) for RNA secondary structure prediction. PAF consists of crucial stem searching (CSS) and global sequence building (GSB). In CSS, a modified ACO (MACO) is used to search the crucial stems, and then a set of stems are generated. In GSB, we used a modified PSO (MPSO) to construct all the stems in one sequence. We evaluated the performance of PAF on ten sequences, which have length from 122 to 1494. We also compared the performance of PAF with the results obtained from six existing well-known methods, SARNA-Predict, RnaPredict, ACRNA, PSOfold, IPSO, and mfold. The comparison results show that PAF could not only predict structures with higher accuracy rate but also find crucial stems.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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  • 4
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    Solution of Point Reactor Neutron Kinetics Equations with Temperature Feedback by Singularly Perturbed Method (2013)
    Hindawi
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    Publication Date: 2013-09-29
    Description: The singularly perturbed method (SPM) is proposed to obtain the analytical solution for the delayed supercritical process of nuclear reactor with temperature feedback and small step reactivity inserted. The relation between the reactivity and time is derived. Also, the neutron density (or power) and the average density of delayed neutron precursors as the function of reactivity are presented. The variations of neutron density (or power) and temperature with time are calculated and plotted and compared with those by accurate solution and other analytical methods. It is shown that the results by the SPM are valid and accurate in the large range and the SPM is simpler than those in the previous literature.
    Print ISSN: 1687-6075
    Electronic ISSN: 1687-6083
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Hindawi
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  • 5
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    An Energy-Efficient and Relay Hop Bounded Mobile Data Gathering Algorithm in Wireless Sensor Networks (2015)
    Hindawi
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    Publication Date: 2015-05-15
    Description: Recent studies reveal that great benefit can be achieved by employing mobile collectors to gather data in wireless sensor networks. Since the mobile collector can traverse the transmission range of each sensor, the energy of nodes may be saved near maximally. However, for directly receiving data packet from every node, the length of mobile collector route should be very long. Hence it may significantly increase the data gathering latency. To solve this problem, several algorithms have been proposed. One of them called BRH-MDG found that data gathering latency can be effectively shortened by performing proper local aggregation via multihop transmissions and then uploading the aggregated data to the mobile collector. But, the BRH-MDG algorithm did not carefully analyze and optimize the energy consumption of the entire network. In this paper, we propose a mathematical model for the energy consumption of the LNs and present a new algorithm called EEBRHM. The simulation results show that under the premise of bounded relay hop, compared with BRH-MDG, EEBRHM can prolong the networks lifetime by 730%.
    Print ISSN: 1550-1329
    Electronic ISSN: 1550-1477
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 6
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    Study of Transition Region of p-Type SiO:H as Window Layer in a-Si:H/a-SiGe:H Multijunction Solar Cells (2016)
    Hindawi
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    Publication Date: 2016-08-09
    Description: We have studied the p-type hydrogenated silicon oxide (:H) films prepared in the amorphous-to-microcrystalline transition region as a window layer in a-Si:H/a-:H multijunction solar cells. By increasing the -to- flow ratio () from 10 to 167, the :H(p) films remained amorphous and exhibited an increased hydrogen content from 10.2% to 12.2%. Compared to the amorphous :H(p) film prepared at low , the :H(p) film deposited at of 167 exhibited a higher bandgap of 2.04 eV and a higher conductivity of 1.15 × 10−5 S/cm. With the employment of :H(p) films prepared by increasing from 10 to 167 in a-Si:H single-junction cell, the FF improved from 65% to 70% and the efficiency increased from 7.4% to 8.7%, owing to the enhanced optoelectrical properties of :H(p) and the improved p/i interface. However, the cell that employed :H(p) film with over 175 degraded the p/i interface and degraded the cell performance, which were arising from the onset of crystallization in the window layer. Compared to the cell using standard a-:H(p), the a-Si:H/a-:H tandem cells employing :H(p) deposited with of 167 showed an improved efficiency from 9.3% to 10.3%, with of 1.60 V, of 9.3 mA/cm2, and FF of 68.9%.
    Print ISSN: 1110-662X
    Electronic ISSN: 1687-529X
    Topics: Electrical Engineering, Measurement and Control Technology , Energy, Environment Protection, Nuclear Power Engineering
    Published by Hindawi
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  • 7
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    Physicochemical Characteristics of River Water Downstream of a Large Tropical Hydroelectric Dam (2016)
    Hindawi
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    Publication Date: 2016-08-29
    Description: Water quality in the downstream river of a hydroelectric dam may be affected by the structural design and operation. To date, little is known about the water quality downstream of the largest dam in Malaysia, the Bakun hydroelectric dam. Therefore, the objective of the study was to determine the water quality downstream of the dam when the spillway was closed and when it was opened. Results of the study indicate that the dam plays a significant role in regulating the water quality downstream of it. When the spillway was closed, pH and oxygen were lower in the river where DO was below 5 mg/L. When the spillway was opened, the water quality improved in terms of oxygen content (〉8.0 mg/L), total sulphide (TS), and chemical oxygen demand (COD) but deteriorated in terms of five-day biochemical oxygen demand (BOD5), total ammonia nitrogen (TAN), and total phosphorus (TP). Additionally, the intensity of the impacts, particularly BOD5, COD, and TAN, shows a declining trend as distance from the dam increases. This study shows that impacts on the water quality extend to a distance of 32 km from the dam particularly turbidity and DO and opening the spillway changes the water quality significantly.
    Print ISSN: 2090-9063
    Topics: Chemistry and Pharmacology
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  • 8
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    Optimization of μc-Si1−xGex:H Single-Junction Solar Cells with Enhanced Spectral Response and Improved Film Quality (2015)
    Hindawi
    Details
    Publication Date: 2015-06-25
    Description: Effects of RF power on optical, electrical, and structural properties of μc-Si1−xGex:H films was reported. Raman and FTIR spectra from μc-Si1−xGex:H films reflected the variation in microstructure and bonding configuration. Unlike increasing the germane concentration for Ge incorporation, low RF power enhanced Ge incorporation efficiency in μc-Si1−xGex:H alloy. By decreasing RF power from 100 to 50 W at a fixed reactant gas ratio, the optical bandgap of μc-Si1−xGex:H was reduced owing to the increase in Ge content from 11.2 to 23.8 at.%, while Ge-related defects and amorphous phase were increased. Consequently, photo conductivity of 1.62 × 10−5 S/cm was obtained for the μc-Si1−xGex:H film deposited at 60 W. By applying 0.9 μm thick μc-Si1−xGex:H absorber with of 48% and [Ge] of 16.4 at.% in the single-junction cell, efficiency of 6.18% was obtained. The long-wavelength response of μc-Si1−xGex:H cell was significantly enhanced compared with the μc-Si:H cell. In the case of tandem cells, 0.24 μm a-Si:H/0.9 μm μc-Si1−xGex:H tandem cell exhibited a comparable spectral response as 0.24 μm a-Si:H/1.4 μm μc-Si:H tandem cell and achieved an efficiency of 9.44%.
    Print ISSN: 1110-662X
    Electronic ISSN: 1687-529X
    Topics: Electrical Engineering, Measurement and Control Technology , Energy, Environment Protection, Nuclear Power Engineering
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  • 9
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    Transverse Vibration of Axially Moving Functionally Graded Materials Based on Timoshenko Beam Theory (2015)
    Hindawi
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    Publication Date: 2015-06-26
    Description: The transverse free vibration of an axially moving beam made of functionally graded materials (FGM) is investigated using a Timoshenko beam theory. Natural frequencies, vibration modes, and critical speeds of such axially moving systems are determined and discussed in detail. The material properties are assumed to vary continuously through the thickness of the beam according to a power law distribution. Hamilton’s principle is employed to derive the governing equation and a complex mode approach is utilized to obtain the transverse dynamical behaviors including the vibration modes and natural frequencies. Effects of the axially moving speed and the power-law exponent on the dynamic responses are examined. Some numerical examples are presented to reveal the differences of natural frequencies for Timoshenko beam model and Euler beam model. Moreover, the critical speed is determined numerically to indicate its variation with respect to the power-law exponent, axial initial stress, and length to thickness ratio.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
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  • 10
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    Mechanical Fault Diagnosis Using Color Image Recognition of Vibration Spectrogram Based on Quaternion Invariable Moment (2015)
    Hindawi
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    Publication Date: 2015-09-18
    Description: Automatic extraction of time-frequency spectral image of mechanical faults can be achieved and faults can be identified consequently when rotating machinery spectral image processing technology is applied to fault diagnosis, which is an advantage. Acquired mechanical vibration signals can be converted into color time-frequency spectrum images by the processing of pseudo Wigner-Ville distribution. Then a feature extraction method based on quaternion invariant moment was proposed, combining image processing technology and multiweight neural network technology. The paper adopted quaternion invariant moment feature extraction method and gray level-gradient cooccurrence matrix feature extraction method and combined them with geometric learning algorithm and probabilistic neural network algorithm, respectively, and compared the recognition rates of rolling bearing faults. The experimental results show that the recognition rates of quaternion invariant moment are higher than gray level-gradient cooccurrence matrix in the same recognition method. The recognition rates of geometric learning algorithm are higher than probabilistic neural network algorithm in the same feature extraction method. So the method based on quaternion invariant moment geometric learning and multiweight neural network is superior. What is more, this algorithm has preferable generalization performance under the condition of fewer samples, and it has practical value and acceptation on the field of fault diagnosis for rotating machinery as well.
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    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
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