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  • 1
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    Numerical Simulation of Rod-Plate Gap Streamer Discharge in SF6/N2 Gas Mixtures Based on ETG-FCT Method (2015)
    Hindawi
    Details
    Publication Date: 2015-08-05
    Description: The Euler-Taylor-Galerkin flux-corrected transport (ETG-FCT) algorithm for the numerical solution of particle transport equations is described, based on the method developed by Lohner to solve conservation equations in fluid mechanics, and its application is extended to gas discharge problems. To improve the efficiency of computing and reduce numerical error, the nonuniform triangular mesh method is introduced, and the continuity equation is solved by ETG-FCT. The new contributions in this paper include the development of the ETG scheme and its application to rod-plate gap streamer discharge in 50~50% SF6/N2 gas mixtures problems. Results are obtained: the spatial distributions of electron densities, positive ion densities, negative ion densities, photoelectron densities, and the electric field, respectively. The velocities of streamer propagations and the radius of streamer obtained from the proposed model are in good agreement with experimental and simulation results in literature. The results also prove that the ETG-FCT method is valid.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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  • 2
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    The Research of Temperature Compensation for Thermopile Sensor Based on Improved PSO-BP Algorithm (2015)
    Hindawi
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    Publication Date: 2015-08-14
    Description: When thermopile sensor is used for safety monitoring of equipment in industrial environments, particularly for measuring the thermal radiation information of device, the measured result of this kind of sensor is usually affected by ambient temperature due to its unique structure. An improved PSO-BP algorithm is proposed for temperature compensation of thermopile sensor and correcting the error in the condition of the system accuracy requirements reduced by temperature. The core of improved PSO-BP algorithm is to improve the certainty of initial weights and thresholds that belonged to BP neural network and then train the samples by using BP neural network for enhancing the generalization ability and stability of system. The experimental results show that the proposed PSO-BP network outperforms other similar algorithms with faster convergence speed, lower errors, and higher accuracy.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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  • 3
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    Concise Synthesis and Antidiabetic Effect of Three Natural Triterpenoid Saponins Isolated from Fadogia ancylantha (Makoni tea) (2015)
    Wiley
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    Publication Date: 2015-09-14
    Description: The first concise synthesis of the bidesmosidic oleanolic acid saponins 1 – 3 isolated from Fadogia ancylantha (Makoni tea) have been accomplished through a ‘one-pot sequential glycosylation’ strategy with two glycosyl 1-(trichloroacetimidate)s as glycosyl donors. The synthesized natural products 1 – 3 were then evaluated for their inhibitory activities against α -glucosidase, α -amylase, and lipase. Among the assayed compounds 1 – 3 , compound 1 showed strong α -glucosidase and α -amylase inhibition, with IC 50 values of 160 and 180 μ M , respectively. Moreover, compounds 2 and 3 showed strong inhibition against α -glucosidase and lipase, with the respective IC 50 values of 170 and 190 μ M , and 190 and 200 μ M .
    Print ISSN: 0018-019X
    Electronic ISSN: 1522-2675
    Topics: Chemistry and Pharmacology
    Published by Wiley
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  • 4
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    GTDM: A DTN Routing on Noncooperative Game Theory in a City Environment (2015)
    Hindawi
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    Publication Date: 2015-06-02
    Description: The performance of delay tolerant networks (DTNs) can be influenced by movement model in different application environments. The existing routing algorithms of DTNs do not meet the current city environments due to the large differences in node densities, social characteristics, and limited energy. The key indicators of DTNs such as success delivery ratio, average delivery latency, network lifetime, and network overhead ratio can influence the performances of civil DTNs applications. Aiming to improve the key indicators of DTNs in city environments, this paper presents a fixed sink station based structure and a more proper routing algorithm named Game Theory Based Decision Making (GTDM). GTDM shows decision-making process for neighborhood selection and packet delivering strategy which is based on the noncooperative game theory method and city environment characteristics. GTDM performance is evaluated using numerical simulations under Working Day Movement (WDM) model and the results suggested that GTDM outperforms other traditional DTNs routing approaches, such as Epidemic and Prophet algorithms.
    Print ISSN: 1687-725X
    Electronic ISSN: 1687-7268
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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  • 5
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    New gradient methods for sensor selection problems (2019)
    Hindawi
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    Publication Date: 2019
    Description: International Journal of Distributed Sensor Networks, Volume 15, Issue 3, March 2019. 〈br/〉
    Print ISSN: 1550-1477
    Electronic ISSN: 1550-1477
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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  • 6
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    The Wavelength-Locking of High-Power 808 nm Semiconductor Laser (2015)
    Hindawi
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    Publication Date: 2015-08-28
    Description: A distributed feedback (DFB) laser of 808 nm is produced in this paper whose optical power is 2 W, cavity length is 3 mm, and injecting width is 200 μm. A second-order grating formed into an InGaP/GaAs/InGaP multilayer structure provides the optical distributed feedback. The holographic lithography method is adopted to make Bragg gratings in p-waveguide layer (Λ = 240 nm) of the GaAs epitaxial wafers. The best experimental conditions are determined by analyzing the surface morphology and three-dimensional holographic grating. In addition, the output power data and wavelength of the distributed feedback laser emitting at different temperatures are presented. And the wavelength varies with temperature at a rate of 0.062 nm/K. Finally, the conclusion is drawn that this kind of DFB laser has a better temperature stabilized wavelength and narrower line width.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
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  • 7
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    IDUC: An Improved Distributed Unequal Clustering Protocol for Wireless Sensor Networks (2015)
    Hindawi
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    Publication Date: 2015-08-31
    Description: Due to the imbalanced energy consumption among nodes in wireless sensor networks, some nodes die prematurely, which decreases the network lifetime. To solve this problem, existing clustering protocols usually construct unequal clusters by exploiting uneven competition radius. Taking their imperfection on designing the uneven competition radius and intercluster communication into consideration, this paper proposes an improved distributed unequal clustering protocol (IDUC) for wireless sensor networks, where nodes are energy heterogeneous and scattered unevenly. The cores of IDUC are the formation of unequal cluster topology and the construction of intercluster communication routing tree. Compared with previous protocols, IDUC is suitable for various network scenarios, and it can balance the energy consumption more efficiently and extend the lifetime of networks significantly.
    Print ISSN: 1550-1329
    Electronic ISSN: 1550-1477
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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  • 8
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    Inhibition of bleomycin-induced pulmonary fibrosis by bone marrow-derived mesenchymal stem cells might be mediated by decreasing MMP9, TIMP-1, INF-γ and TGF-β (2015)
    Wiley
    Details
    Publication Date: 2015-07-16
    Description: The study was aimed to investigate the mechanism and administration timing of bone marrow-derived mesenchymal stem cells (BMSCs) in bleomycin (BLM)-induced pulmonary fibrosis mice. Thirty-six mice were divided into six groups: control group (saline), model group (intratracheal administration of BLM), day 1, day 3 and day 6 BMSCs treatment groups and hormone group (hydrocortisone after BLM treatment). BMSCs treatment groups received BMSCs at day 1, 3 or 6 following BLM treatment, respectively. Haematoxylin and eosin and Masson staining were conducted to measure lung injury and fibrosis, respectively. Matrix metalloproteinase (MMP9), tissue inhibitor of metalloproteinase-1 (TIMP-1), γ -interferon (INF- γ ) and transforming growth factor β 1 (TGF- β ) were detected in both lung tissue and serum. Histologically, the model group had pronounced lung injury, increased inflammatory cells and collagenous fibres and up-regulated MMP9, TIMP-1, INF- γ and TGF- β compared with control group. The histological appearance of lung inflammation and fibrosis and elevation of these parameters were inhibited in BMSCs treatment groups, among which, day 3 and day 6 treatment groups had less inflammatory cells and collagenous fibres than day 1 treatment group. BMSCs might suppress lung fibrosis and inflammation through down-regulating MMP9, TIMP-1, INF- γ and TGF- β . Delayed BMSCs treatment might exhibit a better therapeutic effect. Copyright © 2015 John Wiley & Sons, Ltd. Highlights are as follows: BMSCs repair lung injury induced by BLM. BMSCs attenuate pulmonary fibrosis induced by BLM. BMSCs transplantation down-regulates MMP9 and TIMP-1. BMSCs transplantation down-regulates INF- γ and TGF- β . Delayed transplantation timing of BMSCs might exhibit a better effect against BLM.
    Print ISSN: 0263-6484
    Electronic ISSN: 1099-0844
    Topics: Biology , Medicine
    Published by Wiley
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  • 9
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    A Reversible Steganography Scheme of Secret Image Sharing Based on Cellular Automata and Least Significant Bits Construction (2015)
    Hindawi
    Details
    Publication Date: 2015-04-21
    Description: Secret image sharing schemes have been extensively studied by far. However, there are just a few schemes that can restore both the secret image and the cover image losslessly. These schemes have one or more defects in the following aspects: (1) high computation cost; (2) overflow issue existing when modulus operation is used to restore the cover image and the secret image; (3) part of the cover image being severely modified and the stego images having worse visual quality. In this paper, we combine the methods of least significant bits construction (LSBC) and dynamic embedding with one-dimensional cellular automata to propose a new lossless scheme which solves the above issues and can resist differential attack and support parallel computing. Experimental results also show that this scheme has the merit of big embedding capacity.
    Print ISSN: 1024-123X
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    Topics: Mathematics , Technology
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  • 10
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    Anomaly Detection and Degradation Prediction of MOSFET (2015)
    Hindawi
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    Publication Date: 2015-06-09
    Description: The MOSFET is an important power electronic transistor widely used in electrical systems. Its reliability has an effect on the performance of systems. In this paper, the failure models and mechanisms of MOSFETs are briefly analyzed. The on-resistance is the key failure precursor parameter representing the degree of degradation. Based on the experimental data, a nonlinear dual-exponential degradation model for MOSFETs is obtained. Then, we present an approach for MOSFET degradation state prediction using a strong tract filter based on the obtained degradation model. Lastly, the proposed algorithm is shown to perform effectively on experimental data. Thus, it can provide early warning and enhance the reliability of electrical systems.
    Print ISSN: 1024-123X
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    Topics: Mathematics , Technology
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