检索结果-南通市图书馆

Exact solutions for nonlinear partial fractional differential equations

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第11期21卷 32-38页

作者： Khaled A.Gepreel saleh Omran Mathematics Department Faculty of ScienceZagazig University Mathematics Department Faculty of ScienceTaif University Mathematics Department Faculty of scienceSouth Valley University

′In this article, we use the fractional complex transformation to convert nonlinear partial fractional differential equations to nonlinear ordinary differential equations. We use the improved （G′/G）-expansion function method to calculate the exact solutions to the time- and space-fractional derivative foam drainage equation and the time- and space-fractional derivative nonlinear KdV equation. This method is efficient and powerful for solving wide classes of nonlinear evolution fractional order equations.

关键词： fractional calculus complex transformation modified Riemann-Liouville derivative im- proved (G′/G)-expansion function method

On Time-Constant Robust Tuning of Fractional Order [Proportional Derivative] Controllers

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2019年第5期6卷 1179-1186页

作者： Vahid Badri Mohammad saleh Tavazoei Electrical Engineering Department Sharif University of TechnologyTehranIran

This paper deals with analyzing a newly introduced method for tuning of fractional order [proportional derivative](FO[PD]) controllers to be used in motion control. By using this tuning method, not only the phase margin and gain crossover frequency are adjustable, but also robustness to variations in the plant time-constant is guaranteed. Conditions on the values of control specifications(desired phase margin and gain crossover frequency) for solution existence in this tuning method are found. Also, the number of solutions is analytically determined in this study. Moreover, experimental verifications are presented to indicate the applicability of the obtained results.

关键词： Fractional order controller robustness solution existence tuning method

Evaluation of sediment contamination in the Red Sea coastal area combining multiple pollution indices and multivariate statistical techniques

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2021年第2期36卷 243-254页

作者： Yousef Saeed saleh Biology Department Faculty of Science Taiz University

In the recent years, the Red Sea coast of Yemen has been severely affected by intensive anthropogenic activities. The current study constitutes a thorough inquiry to evaluate the extent of heavy metals pollution in Yemen’s Red Sea coast sediment and identifies the possible sources of pollution. The concentrations of five metals(copper(Cu), zinc(Zn), cadmium(Cd), lead(Pb), and nickel(Ni)) collected from nine sites along the Red Sea coast of Yemen were assessed using an atomic absorption spectrophotometer(ASS). Sediment quality indices, such as the sediment quality guidelines(SQGs), potential ecological risk(RI), contamination factor(CF), pollution load index(PLI), geoaccumulation index(Igeo), and modified degree of contamination(m Cd) were computed. In addition, multivariate statistical techniques(principal component analysis(PCA),hierarchical cluster analysis, and Pearson’s correlation analysis) were applied to identify the potential sources of metals. The mean concentrations of Cu, Zn, Cd, Pb, and Ni were 51.3, 61.9, 4.02, 9.9, and 33.4 mg/kg dry wt, respectively. The spatial distribution revealed that the metals concentrations were high at the middle zone and low southward of Hodeida city. According to the SQGs, the adverse biological effects of metals were occasionally associated with Cu and Cd, frequently associated with Ni, and not expected to occur with Zn and Pb. The RI indicated that the sediment of the studied sites pose low(RI Ni > Pb > Cd > Cu,whereas the PLI and m Cd indicated that Ras Isa(Site 5) and Urj village(Site 6) were the most polluted ***, cluster analysis, and correlation analysis found that Cd, Pb, and Ni mostly originated from anthropogenic

关键词： Red Sea Heavy metals Pollution Spatial distribution Sediment quality

A Unified Optimization-Based Framework to Adjust Consensus Convergence Rate and Optimize the Network Topology in Uncertain Multi-Agent Systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2021年第9期8卷 1539-1548页

作者： Mohammad Saeed Sarafraz Mohammad saleh Tavazoei Department of Electrical Engineering Sharif University of TechnologyTehran 11365-9363Iran

This paper deals with the consensus problem in an uncertain multi-agent system whose agents communicate with each other through a weighted undirected(primary)*** considered multi-agent system is described by an uncertain state-space model in which the involved matrices belong to some matrix *** the main contribution of the paper,a unified optimization-based framework is proposed for simultaneously reducing the weights of the edges of the primary communication graph(optimizing the network topology)and synthesizing a controller such that the consensus in the considered uncertain multi-agent system is ensured with an adjustable convergence *** the NP-hardness nature of the optimization problem related to the aforementioned framework,this problem is relaxed such that it can be solved by regular LMI ***/practical-based examples are presented to verify the usefulness of the obtained results.

关键词： Convergence-rate element-wise uncertainty robust controller topology design

PID-type Terminal Sliding Mode Control for Permanent Magnet Synchronous Generator-based Enhanced Wind Energy Conversion Systems

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2022年第4期8卷 993-1003页

作者： Mojtaba Nasiri saleh Mobayen Ali Arzani the Solar Energy Applications Group Trinity College DublinDublin 2D02 PN40Ireland Department of Electrical Engineering University of ZanjanZanjanIran the Future Technology Research Center National Yunlin University of Science and TechnologyDouliuYunlin County 64002TaiwanChina the Center for Energy Systems Research(CESR) Tennessee Technological UniversityCookevilleTN 38505USA

The provision of wind farm(WF)grid codes(GCs)has become imperative for sustained grid operations,especially for WFs with permanent-magnet synchronous generator(PMSG)wind energy conversion *** techniques have been developed for executing GC requirements in the event of grid *** the methods,an intriguing strategy is to enhance the performance of back-to-back(BTB)converter *** this research,the PID-type terminal sliding mode control(PID-TSMC)scheme is implemented for both machine-side and grid-side converter-modified controllers of BTB-converter,to reinforce the nonlinear relationship among the state-variable and the control *** application of this control scheme decreases the response time and improves the robustness of the BTB-converter controllers regarding uncertainty of parameters and external *** grid-side converter tracks the maximum power point,contributing to the rapid decrease of generator active power output during *** frees up converter capacity for injecting GC-compliant reactive current into the ***,the machine-side converter regulates DC-link voltage,in which its variations during external disturbances decrease substantially with the *** discussions on the simulations contemplate on the robustness and efficiency of the implemented PID-TSMC strategy in comparison to other BTB-converter control strategies.

关键词： Back-to-back converter grid code PMSG-based wind turbine terminal sliding mode control

Criteria for Response Monotonicity Preserving in Approximation of Fractional Order Systems

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

IEEE/CAA Journal of Automatica Sinica 2016年第4期3卷 422-429页

作者： Mohammad saleh Tavazoei IEEE Electrical Engineering Department Sharif University of Technology

In approximation of fractional order systems,a significant objective is to preserve the important properties of the original *** monotonicity of time/frequency responses is one of these properties whose preservation is of great importance in approximation *** this importance,the issues of monotonicity preservation of the step response and monotonicity preservation of the magnitude-frequency response are independently investigated in this *** these investigations,some conditions on approximating filters of fractional operators are found to guarantee the preservation of step/magnitude-frequency response monotonicity in approximation *** conditions are also simplified in some special *** addition,numerical simulation results are presented to show the usefulness of the obtained conditions.

关键词： Fractional order system approximation step response magnitude-frequency response monotonicity

Performance of beacon safety message dissemination in Vehicular Ad hoc NETworks (VANETs)

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第12期8卷 1990-2004页

作者： YOUSEFI saleh FATHY Mahmood BENSLIMANE Abderrahim Computer Engineering Faculty Iran University of Science and TechnologyNarmak Tehran 16846-13114 Tehran Iran Laboratoire d'Informatique d'Avignon LIA 339 chemin des Meinajaries BP 1228-84911 Avignon cedex 9 France

Currently, there is a growing belief that putting an IEEE 802.11-like radio into road vehicles can help the drivers to travel more safely. Message dissemination protocols are primordial for safety vehicular applications. There are two types of safety messages which may be exchanged between vehicles: alarm and beacon. In this paper we investigate the feasibility of deploying safety applications based on beacon message dissemination through extensive simulation study and pay special attention to the safety requirements. Vehicles are supposed to issue these messages periodically to announce to other vehicles their current situation and use received messages for preventing possible unsafe situations. We evaluate the performance of a single-hop dissemination protocol while taking into account the quality of service (QoS) metrics like delivery rate and delay. We realize that reliability is the main concern in beacon message dissemination. Thus, a new metric named effective range is defined which gives us more accurate facility for evaluating QoS in safety applications specifically. Then, in order to improve the performance, the effects of three parameters including vehicle's transmission range, message transmission's interval time and message payload size are studied. Due to special characteristics of the safety applications, we model the relationship between communication-level QoS and application-level QoS and evaluate them for different classes of safety applications. As a conclusion, the current technology of IEEE 802.11 MAC layer has still some challenges for automatic safety applications but it can provide acceptable QoS to driver assistance safety applications.

关键词： Safety applications Inter-vehicle communications Vehicular Ad hoc NETworks (VANETs) Application level QoS Effective range

Buoyant Marangoni convection of nanofluids in square cavity

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2015年第9期36卷 1169-1184页

作者： H.saleh I.HASHIM School of Mathematical Sciences Universiti Kebangsaan Malaysia Solar Energy Research Institute Universiti Kebangsaan Malaysia Research Institute Center for Modeling & Computer Simulation(RI/CM&CS)King Fahd University of Petroleum & Minerals

The buoyant Marangoni convection heat transfer in a differentially heated cavity is numerically studied. The cavity is filled with water-Ag, water-Cu, water-Al2O3, and water-TiO2 nanofiuids. The governing equations are based on the equations involving the stream function, vorticity, and temperature. The dimensionless forms of the governing equations are solved by the finite difference （FD） scheme consisting of the alternating direction implicit （ADI） method and the tri-diagonal matrix algorithm （TDMA）. It is found that the increase in the nanoparticle concentration leads to the decrease in the flow rates in the secondary cells when the convective thermocapillary and the buoyancy force have similar strength. A critical Marangoni number exists, below which increasing the Marangoni number decreases the average Nusselt number, and above which increasing the Marangoni number increases the average Nusselt number. The nanoparticles play a crucial role in the critical Marangoni number.

关键词： finite difference method Marangoni convection nanofluid

Flow Reversal of Fully-Developed Mixed MHD Convection in Vertical Channels

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2010年第2期27卷 138-140页

作者： H. saleh, I. Hashim Centre for Modelling and Data Analysis School of Mathematical Sciences Universiti Kebangsaan Malaysia 43600 UKM Bangi Selangor Malaysia

The present analysis is concerned with flow reversal phenomena of the fully-developed laminar combined free and forced MHD convection in a vertical parallel-plate channel. The effect of viscous dissipation is taken into account. Flow reversal adjacent to the cold （or hot） wall is found to exist within the channel as Gr/Re is above （or below） a threshold value. Parameter zones for the occurrence of reversed flow are presented.

关键词： Chinese climate network complex systems small world community