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Constant frequency operation of parallel resonant converter for constant-current constant-voltage battery charger applications

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Journal of Modern Power Systems and Clean Energy 2019年第1期7卷 186-199页

作者： taha Nurettin GüCIN Muhammet BIBEROGLU Bekir FINCAN Energy Systems Engineering Department University of Yalova Electrical Engineering Department Istanbul Technical University

This paper proposes a design and control approach to parallel resonant converter(PRC) based battery *** proposed approach is particularly suitable for the constant-current constant-voltage(CC-CV)charging method, which is the most commonly utilized *** the PRC is operated at two different frequencies for each CC and CV charging modes, this approach eliminates the need for complicated control techniques such as the frequency-control and *** proposed method not only simplifies the design and implementation processes of the converter unit but also simplifies the design of output filter configuration and decreases the number of the required components for the control of the *** proposed method is confirmed by two experimental *** results show that the designed charger circuit ensured a very stable constant current in CC charging phase, where the charging current is fixed to 1.75 *** a voltage increase in CV phase is observed, the charger circuit is able to decrease the charging current to 0.5 A in CV phase, as depicted in battery *** efficiency of the charger is figured out to be in the range of 86%-93% in the first setup, while it is found to be in the range of 78%-88% in the second setup,where a high frequency transformer is employed.

关键词： Resonant converter Parallel resonant converter Battery charger Constant-current constant-voltage(CC-CV)charging

An Improved Security Scheme for IEC 61850MMS Messages in Intelligent Substation Communication Networks

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Journal of Modern Power Systems and Clean Energy 2020年第3期8卷 591-595页

作者： taha Selim Ustun S.M.Suhail Hussain Fukushima Renewable Energy Institute AIST(FREA)FukushimaJapan Research Institute of the Energy Frontier TsukubaJapan

Advanced connectivity in substations brings along cybersecurity considerations. Especially, the use of standardized data objects and message structures stipulated by IEC 61850 makes them much more vulnerable to unauthorized access and manipulation. In order to tackle these vulnerabilities, different methods are investigated by researchers all over the world. An important aspect of such efforts is the real-time performance consideration since power systems are bound by the rules of physics and all control/communication tasks need to be completed in a certain time frame. Security schemes for substation communication have been proposed in the recent literature. However, they must be improved to ensure a full security solution. Recently published IEC 62351 standard aims to fill this gap. Node authentication is vital for substation communication networks based on IEC 61850 to mitigate a variety of attacks such as man-in-the-middle(MITM) attack. This short communication presents a node authentication mechanism based on transport layer security(TLS) with certificates to address this knowledge gap. It also investigates the real-time performance by implementing the proposed scheme with Python.

关键词： IEC 62351 standard certificate authority cer-tificate-based authentication cybersecurity smart grid

A new hybrid algorithm for global optimization and slope stability evaluation

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Journal of Central South University 2013年第11期20卷 3265-3273页

作者： taha Mohd Raihan Khajehzadeh Mohammad Eslami Mahdiyeh Civil and Structural Engineering Department National University of Malaysia Civil Engineering Department Anar BranchIslamic Azad University Electrical Engineering Department Science and Research BranchIslamic Azad University

A new hybrid optimization algorithm was presented by integrating the gravitational search algorithm （GSA） with the sequential quadratic programming （SQP）, namely GSA-SQP, for solving global optimization problems and minimization of factor of safety in slope stability analysis. The new algorithm combines the global exploration ability of the GSA to converge rapidly to a near optimum solution. In addition, it uses the accurate local exploitation ability of the SQP to accelerate the search process and find an accurate solution. A set of five well-known benchmark optimization problems was used to validate the performance of the GSA-SQP as a global optimization algorithm and facilitate comparison with the classical GSA. In addition, the effectiveness of the proposed method for slope stability analysis was investigated using three ease studies of slope stability problems from the literature. The factor of safety of earth slopes was evaluated using the Morgenstern-Price method. The numerical experiments demonstrate that the hybrid algorithm converges faster to a significantly more accurate final solution for a variety of benchmark test functions and slope stability problems.

关键词： gravitational search algorithm sequential quadratic programming hybrid algorithm global optimization slope stability

Salt response of the freshwater microalga Scenedesmus obliquus(Turp.)Kutz is modulated by the algal growth phase

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Journal of Oceanology and Limnology 2020年第3期38卷 802-815页

作者： taha Mohamed EL-KATONY Magda Faiz EL-ADL Department of Botany and Microbiology Faculty of ScienceDamietta UniversityNew Damietta City 34517Egypt

Growth and biochemical responses of the coenobial green alga Scenedesmus obliquus to salinity stress were monitored across different phases of *** alga was cultured on BG11 growth medium and subjected to 0,30,100,and 200 mmol/L NaCl for a period of 20 d,during which algal cultures were harvested at 4-d *** salinity-induced inhibition of algal growth was accompanied with prolongation of timing of the different growth *** sharp and progressive salinity-induced inhibition of algal growth rate during the early phase of growth points to salt shock but moderation of inhibition at the subsequent stages of growth means algal acclimation to *** concentrations of chlorophylls a and b,soluble sugars,proteins as well as those of K+and Na+in the alga exhibited peaks at the initiation of the exponential phase of growth,with increasing magnitude in proportion to the increase in the level of ***,whereas soluble sugars of the alga peaked at initiation of the exponential phase,starch concentration progressively increased with culture age,reaching saturation towards the stationary *** the salinity-induced increase in soluble sugars was most evident at the early stages of growth the reverse was true for *** present results point to fast acclimation of *** to salt stress post a brief salt shock,utilizing soluble sugars,K+and Na+for osmotic *** salinity from 0 to 200 mmol/L NaCl led to progressive increase in soluble sugars,proteins,K+and Na+concentrations of the algal cells,particularly at the early stages of ***,the salinity-induced increase in chlorophyll concentration approached a limit at 100 mmol/L NaCl whereas that in starch concentration was more evident at the later stages of growth.

关键词： carbohydrates growth phase minerals protein salt stress Scenedesmus obliquus

Preparation and application of amino functionalized mesoporous nanofiber membrane via electrospinning for adsorption of Cr^(3+) from aqueous solution

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Journal of Environmental Sciences 2012年第4期24卷 610-616页

作者： Ahmed A.taha Junlian Qiao Fengting Li Bingru Zhang College of Environmental Science and Engineering UNEP Tongji Institute of Environment for Sustainable DevelopmentState Key Laboratory of Pollution Control and Resource ReuseTongji University

Novel amino （-NH2） functionalized mesoporous polyvinyl pyrrolidone （PVP）/SiO2 composite nanofiber membranes were fabricated by a one-step electrospinning method using poly （vinyl alcohol） and tetraethyl orthosilicate （TEOS） mixed with cationic surfactant, cety｜trimethyl ammonium bromide （CTAB） as the structure directing agent. Ureidopropyltriethoxysilane was used for functionalization of the internal pore surfaces. The membranes were characterized by scanning electron microscopy （SEM）, high-resolution transmission electron microscopy （HRTEM） images, X-ray diffraction （XRD）, Fourier-transform infrared spectroscopy （FT-IR）, element analyzer and Nz adsorption-desorption isotherms, The nanofiber diameters, average pore diameters and surface areas were 100-700 nm, 2.86 nm and 873,62 m2/g, respectively. These mesoporous membranes functionalized with -NH2 groups exhibited very high adsorptions properties based on the adsorption of Cr3＋ from an aqueous solution. Equilibrium adsorption was achieved after approximately 20 rain and more than 97% of chronium ions in the solution were removed. The membrane could be regenerated through acidification.

关键词： mesoporous electrospinning nanofiber amino groups adsorption

Mitigation of the blast load effects on a building structure using newly composite structural configurations

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Defence Technology（防务技术） 2021年第1期17卷 75-84页

作者： Ahmed K.taha M.S.Zahran Zhengguo Gao School of Transportation Science and Engineering Beihang University(Beijing University of Aeronautics and Astronautics)Beijing100191PR China Department of Civil Engineering Military Technical CollegeEgypt

In this study,a nonlinear three-dimensional hydrocode numerical simulation was carried out using AUTODYN-3D to investigate the effect of blasting of a high explosive material(TNT)against several configurations of the composite *** numerical models were carried out to study the effect of varying the thickness of the walls and the effect of adding an air layer or aluminum foam layer inside two layers of concrete in mitigating the effect of blast waves on the structure *** results showed that increasing the thickness of walls has a good effect on mitigating the effect of blast *** a layer of air was added,the effect of blast waves was exaggerated,while when a layer of aluminum foam was added the blast wave effects were mitigated with a reasonable percentage.

关键词： Concrete structures Blast waves Numerical simulation TNT

Electrical capacitance volume tomography for measurement soil water infiltration in vessel experiments

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Journal of Central South University 2014年第1期21卷 358-364页

作者： Muhammad Mukhlisin Marlin Ramadhan Baidillah Mohd Raihan taha Department of Civil and Structural Engineering Universiti Kebangsaan MalaysiaBangiSelangor 43600Malaysia Department of Civil Engineering Polytechnic Negeri SemarangJl.Sudarto SHTembalang 50275SemarangIndonesia

Electrical capacitance volume tomography(ECVT) is a recently-developed technique for real-time,non-invasive 3D monitoring of processes involving materials with strong contrasts in dielectric *** work is first application of the method to visualization of water flow in *** describe the principles behind the method,and then demonstrate its use with a simple laboratory infiltration experiment.32 ECVT sensors were installed on the sides of an empty PVC *** was poured into the column at a constant rate,and ECVT data were collected every *** column was then packed with dry sand and again supplied with water at a constant rate with data collected every *** were analyzed to give bulk average water contents,which proved consistent with the water supply *** were also analyzed to give 3D images(216 voxels) allowing visualization of the water distribution during the *** of this work shows that water infiltration into the soil,wall flow,progress of the unstable wetting front and the final water distribution are clearly visible.

关键词： soil water infiltration electrical capacitance volume tomography real time imaging

Modified particle swarm optimization for optimum design of spread footing and retaining wall

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第6期12卷 415-427页

作者： Mohammad KHAJEHZADEH Mohd Raihan taha Ahmed EL-SHAFIE Mahdiyeh ESLAMI Department of Civil Engineering Anar BranchIslamic Azad University Department of Civil and Structural Engineering University Kebangsaan Malaysia Department of Electrical Engineering Anar BranchIslamic Azad University

This paper deals with the economically optimized design and sensitivity of two of the most widely used systems in geotechnical engineering: spread footing and retaining wall. Several recent advanced optimization methods have been developed, but very few of these methods have been applied to geotechnical problems. The current research develops a modified particle swarm optimization (MPSO) approach to obtain the optimum design of spread footing and retaining wall. The algorithm handles the problem-specific constraints using a penalty function approach. The optimization procedure controls all geotechnical and structural design constraints while reducing the overall cost of the structures. To verify the effectiveness and robustness of the proposed algorithm, three case studies of spread footing and retaining wall are illustrated. Comparison of the results of the present method, standard PSO, and other selected methods employed in previous studies shows the reliability and accuracy of the algorithm. Moreover, the parametric performance is investigated in order to examine the effect of relevant variables on the optimum design of the footing and the retaining structure utilizing the proposed method.

关键词： Particle swarm optimization (PSO) Spread footing Retaining wall Sensitivity analysis

Simple Spectrophotometric Methods for the Determination of Meloxicam in Presence of Its Degradation Products

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药物分析杂志 2004年第4期24卷 390-394页

作者： Ellham A. taha National Organization for Drug Control and Research Cairo Egypt

To develope two simple and accurate spectrophotometric methods for the determination of meloxicam( I )in presence of its degradation products, 5 -methyl -2 -aminothiazole ( II )and benzothiazine carboxylic acid( Ill ). Method:Both methods are based on the formation of chelate complexes of the studied drug with uranyl acetate and ferric chloride at room temperature in a methanolic medium. Results:The resulting complexes are stable for 24 hrs and show absorption maxima at 406 nm and 580 nm for uranyl and ferric complexes respectively. These methods are applicable over the concentration ranges of 10 -100 and 37.5 -300 p^g ~ mL-1 with mean recoveries of (99.44 ~ 0. 48 ) % and (99. 42 ~ 0. 45 ) %, and molar absorptivity of 4.67 x 103 and 1. 029 x 103 respectively. Conclusion:Both methods are proved to be stability indicating as no interference was observed with the degradation products. The proposed methods were successfully applied to the determination of the frug in bulk powder, laboratory prepared mixtures containing different percentages of degradation products of the drug in bulk powand pharmaceutical dosage

关键词：分光光度法羧基酸吸收率药物剂量