检索结果-南通市图书馆

A global harmony search algorithm for finding optimal capacitor location and size in distribution networks

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2015年第5期22卷 1748-1761页

作者： reza Sirjani Melkamu Gamene Bade Cyprus International University Faculty of Engineering Nicosia Northern Cyprus Mersin 10 Turkey

Shunt capacitors are broadly applied in distribution systems to scale down power losses, improve voltage profile and boost system capacity. The amount of capacitors added and location of deployment in the system highly determine the advantage of compensation. A novel global harmony search(GHS) algorithm in parallel with the backward/ forward sweep power flow technique and radial harmonic power flow was used to investigate the optimal placement and sizing of capacitors in radial distribution networks for minimizing power loss and total cost by taking account load unbalancing, mutual coupling and harmonics. The optimal capacitor placement outcomes show that the GHS algorithm can reduce total power losses up to 60 k W and leads to more than 18% of cost saving. The results also demonstrate that the GHS algorithm is more effective in minimization of power loss and total costs compared with genetic algorithm(GA), particle swarm optimization(PSO) and harmony search(HS) algorithm. Moreover, the proposed algorithm converges within 800 iterations and is faster in terms of computational time and gives better performance in finding optimal capacitor location and size compared with other optimization techniques.

关键词： optimal capacitor placement harmonics unbalancing harmony search algorithm

Preparation of La-Mo-V mixed-oxide systems and their application in the direct synthesis of acetic acid

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2008年第3期17卷 213-224页

作者： Hamid reza Arandiyan Matin Parvari Chemical Engineering Department Iran University of Science and Technology

In this study, mixed metal oxides developed with a perovskite-type structure that show great potential for use in catalysis. Perovskite oxide catalysts with the composition LaMoxV1-xOn （x = 0.1, 0.3, 0.5, 0.7, and 0.9） have been synthesized by the sol-gel method and then used in the ethane dry reforming reaction for the direct synthesis of acetic acid. The influence of the nature of the metallic source （metal, nitrate, acetylacetonate, and ammonium） on gel formation has been studied by Fourier-transform infrared spectroscopy （FT-IR） and thermogravimetric analysis （TGA-DTA）. After calcination, the obtained perovskites were characterized by X-ray diffraction （XRD） and energy-dispersive X-ray spectrometry （EDS） coupled with scanning electron microscopy （SEM）. The catalysts were then subjected to thermo-programmed reduction （TPR）. The surface area （BET） was found to increase from 2.6 m^2/g （x = 0.1） to 5.1 m2/g （x = 1.0） with increasing molybdenum content following calcinations at 750 °C, and pure LaMoxV1-xOn perovskite was obtained with good homogeneity. The catalysts have been characterized by XRD, SEM, EDS, and carbon analysis （CA）. The results indicate that through this synthesis it is possible to obtain highly crystalline, homogeneous and pure solids, with well-defined structures. The direct synthesis of acetic acid from ethane over the perovskite catalysts was studied at temperatures between 450 and 850 °C and elevated pressures between 1 and 8 bar. It was found that the yield of acetic acid and the selectivity of its formation could be increased by incorporating more molybdenum into the perovskite structure. The experimental studies have shown that the calcination temperature and the molybdenum content have a significant influence on the catalytic activity. Amongst the catalysts tested, LaMo0.7V0.3O4.2 exhibited the best activity and stability.

关键词： acetic acid catalyst perovskite activity LaMoxV1-xOn

Perfect GMR effect in gapped graphene-based ferromagnetic normal ferromagnetic junctions

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2015年第4期24卷 405-410页

作者： Hossein Karbaschi Gholam reza Rashedi Department of Physics University of Isfahan

We investigate the quantum transport property in gapped graphene-based ferromagnetic/normal/ferromagnetic （FG/NG/FG） junctions by using the Dirac-Bogoliubov-de Gennes equation. The graphene is fabricated on SiC and BN substrates separately, so carders in FG/NG/FG structures are considered as massive relativistic particles. Transmission prob- ability, charge, and spin conductances are studied as a function of exchange energy of ferromagnets （h）, size of graphene gap, and thickness of normal graphene region （L） respectively. Using the experimental values of Fermi energy in the normal graphene part （EFN - 400 meV） and energy gap in graphene （260 meV for SiC and 50 meV for BN substrate）, it is shown that this structure can be used for both spin-up and spin-down polarized current. The latter case has different behavior of gapped FG/NG/FG from that of gapless FG/NG/FG structures. Also perfect charge giant magnetoresistance is observed in a range of E FN - mv 2 F〈h〈E FN＋mv 2 F.

关键词： graphene spin-polarized current giant magnetoresistance nanoscale structures

Border-search and jump reduction method for size optimization of spatial truss structures

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2019年第1期13卷 123-134页

作者： Babak DIZANGIAN Mohammad reza GHASEMI Department of Civil Engineering Velayat UniversityIranshahr ***Iran Department of Civil Engineering University of Sistan and BaluchestanZahedan ***Iran

This paper proposes a sensitivity-based border-search and jump reduction method for optimum design of spatial *** is considered as a two-phase optimization approach,where at the first phase,the first local optimum is found by few analyses,after the whole searching space is limited employing an efficient random strategy,and the second phase involves finding a sequence of local optimum points using the variables sensitivity with respect to corresponding values of constraints *** reach the global solution at phase two,a sequence of two sensitivity-based operators of border-search operator and jump operator are introduced until convergence is *** analysis is performed using numerical finite difference *** do structural analysis,a link between open source software of OpenSees and MATLAB was *** truss problems were attempted for optimization in order to show the fastness and efficiency of proposed *** were compared with those reported in the *** shows that the proposed method is competitive with the other optimization methods with a significant reduction in number of analyses carried.

关键词： optimum design sensitivity analysis reduction method spatial tresses OpenSees

The investigation and optimization of drag reduction in turbulent flow of Newtonian fluid passing through horizontal pipelines using functionalized magnetic nanophotocatalysts and lecithin

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2020年第1期28卷 63-75页

作者： Nadia Esfandiari reza Zareinezhad Zahra Habibi Department of Chemical Engineering Marvdasht BranchIslamic Azad UniversityMarvdashtIran

The nanophotocatalysts were synthesized in four stages and evaluated by FTIR, FESEM and VSM analysis. The influence of nanofluids containing functionalized magnetic Ti O2 nanophotocatalyst and dipalmitoylphosphatidylcholine lecithin in drag reduction of turbulent flow in four horizontal pipelines was studied. The effective parameters on drag reduction(nanoparticle concentration, surfactant concentration, p H and Re number) were investigated and optimized in each pipeline using response surface method. The drag reduction in 1/2 " galvanized, 3/4" galvanized, 1/2 "five-layer and 1/2" cuprous pipelines was found 99.1%, 92.5%, 87.6% and 85.2%, respectively. The model adequacy was measured using ANOVA. Based on the high determination coefficient, more than 95% of variance of experimental data in all pipelines was described by quadratic model.

关键词： Drag reduction Lecithin Functionalized magnetic nanophotocatalyst Turbulent flow Response surface

Second-order cone AC optimal power flow: convex relaxations and feasible solutions

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 268-280页

作者： Zhao YUAN Mohammad reza HESAMZADEH Department of Electric Power and Energy Systems KTH Royal Institute of Technology

Optimal power flow(OPF) is the fundamental mathematical model to optimize power system *** on conic relaxation, Taylor series expansion and McCormick envelope, we propose three convex OPF models to improve the performance of the second-order cone alternating current OPF(SOC-ACOPF) model. The underlying idea of the proposed SOC-ACOPF models is to drop assumptions of the original SOC-ACOPF model by convex relaxation and approximation methods.A heuristic algorithm to recover feasible ACOPF solution from the relaxed solution of the proposed SOC-ACOPF models is developed. The proposed SOC-ACOPF models are examined through IEEE case studies under various load scenarios and power network congestions. The quality of solutions from the proposed SOC-ACOPF models is evaluated using MATPOWER(local optimality) and LINDOGLOBAL(global optimality). We also compare numerically the proposed SOC-ACOPF models with other two convex ACOPF models in the *** numerical results show robust performance of the proposed SOCACOPF models and the feasible solution recovery algorithm.

关键词： Optimal power flow Conic relaxation McCormick envelope Taylor series expansion Feasible solution

Random vibration of nonlinear structures with stiffness and strength deterioration by modified tail equivalent linearization method

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2019年第3期18卷 597-610页

作者： reza Raoufi Mohsen Ghafory-Ashtiany Department of Civil Engineering Ahvaz Branch Islamic Azad University Ahvaz Iran International Institute of Earthquake Engineering and Seismology (IIEES) Member: Iranian Earthquake Engineering Association (IEEA)

In this research the tail equivalent linearization method (TELM) has been extended to study structures with degrading materials. The responses of such structures to excitations are non-stationary, even if the excitations are stationary. Non-stationary behavior of the system cannot be considered by conventional TELM. Applying the conventional TELM, the only distinction in the design point excitation for two stationary excitations with diff erent durations is in the addition of a zero value part at the beginning of the design point of the longer excitation. This means that the failure probability is the same for the non-stationary systems under excitations with diff erent durations. Therefore, this solution cannot be correct. In this study, in using TELM for systems with degrading materials, hysteretic energy is replaced by average hysteretic energy, calculated by averaging the obtained hysteretic energy of the structure subjected to a few random sample load realization. In this way, the degradation parameters under design point coincide with those under sample load realizations. Since the average of the hysteretic energy is converges very fast, the modifi ed TELM only requires about tens to hundreds solutions of the response in addition to the ordinary calculations of conventional TELM.

关键词： Nonlinear linearization random vibration degradation

Structural optimization of filament wound composite pipes

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2022年第8期16卷 1056-1069页

作者： Roham RAFIEE reza SHAHZADI Hossein SPERESP Faculty of New Science and Technologies University of TehranTehran ***Iran

An optimization procedure is developed for obtaining optimal structural design of filament wound composite pipes with minimum cost utilized in pressurized water and waste-water ***,the short-term and long-term design constraints dictated by international standards are ***,proper computational tools are developed for predicting the structural properties of the composite pipes based on the design architecture of *** developed computational tools are validated by relying on experimental ***,an integrated design-optimization process is developed to minimize the price as the main objective,taking into account design requirements and manufacturing limitations as the constraints and treating lay-up sequence,fiber volume fraction,winding angle,and the number of total layers as design *** developed method is implemented in various case studies,and the results are presented and discussed.

关键词： composite pipes optimization experimental validation computational modeling filament winding

Generating one-,two-,three-and four-scroll attractors from a novel four-dimensional smooth autonomous chaotic system

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2010年第6期19卷 106-114页

作者： Sara Dadras Hamid reza Momeni Automation and Instruments Lab Electrical Engineering DepartmentTarbiat Modares UniversityP.O.Box 14115-143TehranIran

A new four-dimensional quadratic smooth autonomous chaotic system is presented in this paper, which can exhibit periodic orbit and chaos under the conditions on the system parameters. Importantly, the system can generate one-, two-, three- and four-scroll chaotic attractors with appropriate choices of parameters. Interestingly, all the attractors are generated only by changing a single parameter. The dynamic analysis approach in the paper involves time series, phase portraits, Poincare maps, a bifurcation diagram, and Lyapunov exponents, to investigate some basic dynamical behaviours of the proposed four-dimensional system.

关键词： new smooth autonomous four-dimensional chaotic system multi-scroll chaotic attractor Poincare mapping bifurcation Lyapunov exponent