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DEM Numerical Simulation of Abrasive Wear Characteristics of a Bioinspired Ridged Surface

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Journal of Bionic Engineering 2010年第2期7卷 175-181页

作者： mohammad Almagzoub mohammad Carlo Menon Key Laboratory of Bionic Engineering Jilin University College of Biological and Agricultural Engineering Jilin University MENRVA Group Simon Fraser University

This paper presents numerical investigations into a ridged surface whose design is inspired by the geometry of a Farrer’*** objective of the performed research is to assess if the proposed Bioinspired Ridged Surface (BRS) can potentiallyimprove wear resistance of soil-engaging components used in agricultural machinery and to validate numerical simulationsperformed using software based on the Discrete Element Method (DEM).The wear performance of the BRS is experimentallydetermined and also compared with a conventional flat *** size of soil particles and relative velocities between theabrasive sand and the testing surfaces are *** results show that the numerical simulations are in agreement withthe experimental results and support the hypothesis that abrasive wear is greatly reduced by substituting a conventional flatsurface with the BRS.

关键词： bioinspired ridged surface abrasive wear numerical simulation Discrete Element Method (DEM)

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

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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

A fast and accurate dynamic relaxation scheme

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Frontiers of Structural and Civil Engineering 2019年第1期13卷 176-189页

作者： mohammad REZAIEE-PAJAND mohammad mohammadI-KHATAMI Department of Civil Engineering Ferdowsi University of MashhadMashhadIran

Dynamic relaxation method (DRM)is one of the suitable numerical procedures for nonlinear structural *** the fictitious inertia and damping forces to the static equation,and turning it to the dynamic system,are the basis of this *** selection of the DRM artificial factors leads to the better convergence rate and efficient *** study aims to increase the numerical stability,and to decrease the analysis *** fulfil this objective,the reduction rate of analysis error for consecutive iterations is *** on this formulation,a new time step is found for the viscous dynamic *** combining this novel relationship with the other DRM factors,various geometrical nonlinear structures,such as trusses,frames,and shells,are *** obtained results verify the efficiency of authors'scheme.

关键词： viscous dynamic relaxation time step displacement error geometric nonlinear analysis

Biomechanics of knee joint during forward-walking and drop-landing after anterior cruciate ligament reconstruction:finite element and gait analysis

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Acta Mechanica Sinica 2024年第11期40卷 53-75页

作者： Midiya Khademi mohammad Haghpanahi mohammad Razi Ali Sharifnezhad mohammad Nikkhoo Department of Biomedical Engineering Science and Research BranchIslamic Azad UniversityTehran ***Iran Department of Mechanical Engineering Iran University of Science and TechnologyTehran ***Iran Department of Orthopedics Iran University of Medical SciencesTehran ***Iran Department of Sport Biomechanics and Technology Sport Science Research InstituteTehran ***Iran

The anterior cruciate ligament plays a crucial role in maintaining stability within the knee joint,particularly for athletes who frequently experience its *** study presents a novel approach using personalized three-dimensional(3D)parametric finite element modeling of the knee joint to simulate the treatment following anterior cruciate ligament reconstruction(ACLR)in both forward walking(FW)and drop landing(DL)*** study encompasses two distinct cohorts:five healthy athletes and five ACLR *** motion analysis was conducted on both cohorts,with the ACLR patient group evaluated at 6 and 9 months post-surgery.A comprehensive 3D parametric model of the knee joint was meticulously *** findings reveal a notable reduction in stress on crucial knee structures such as the autograft,meniscus,and cartilages over time for both FW and DL tasks following ACLR,with a reduction in tissue tension of approximately 9.5%and 37%for FW and DL,*** personalized model not only facilitates the investigation of knee joint tissue biomechanics post-ACLR but also aids in estimating the return-to-sports timeline for *** accommodating individual tissue geometries and incorporating patient-specific kinetic data,this model enhances our comprehension of post-ACLR biomechanics across various functional tasks,thereby optimizing rehabilitation strategies.

关键词： Anterior cruciate ligament reconstruction(ACLR) Forward walking(FW) Drop landing(DL) Knee finite element model Gait analysis

Particle swarm optimization algorithm for simultaneous optimal placement and sizing of shunt active power conditioner(APC)and shunt capacitor in harmonic distorted distribution system

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Journal of Central South University 2017年第9期24卷 2035-2048页

作者： mohammadi mohammad Department of Electrical Engineering Borujerd BranchIslamic Azad UniversityBorujerdIran

Due to development of distribution systems and increase in electricity demand,the use of capacitor banks *** the other point of view,nonlinear loads generate and inject considerable harmonic currents into power *** this condition if capacitor banks are not properly selected and placed in the power system,they could amplify and propagate these harmonics and deteriorate power quality to unacceptable *** attention of disadvantages of passive filters,such as occurring resonance,nowadays the usage of this type of harmonic compensator is *** the other side,one of parallel multi-function compensating devices which are recently used in distribution system to mitigate voltage sag and harmonic distortion,performs power factor correction,and improves the overall power quality as active power conditioner(APC).Therefore,the utilization of APC in harmonic distorted system can affect and change the optimal location and size of shunt capacitor bank under harmonic distortion *** paper presents an optimization algorithm for improvement of power quality using simultaneous optimal placement and sizing of APC and shunt capacitor banks in radial distribution networks in the presence of voltage and current *** algorithm is based on particle swarm optimization(PSO).The objective function includes the cost of power losses,energy losses and those of the capacitor banks and APCs.

关键词： shunt capacitor banks active power conditioner multi-objective function particle swarm optimization (PSO) harmonic distorted distribution system

IMC based robust PID controller tuning for disturbance rejection

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Journal of Central South University 2016年第3期23卷 581-597页

作者： mohammad Shamsuzzoha Department of Chemical Engineering King Fahd University of Petroleum and Minerals

It is well-known that the IMC-PID controller tuning gives fast and improved set point response but slow disturbance rejection. A modification has been proposed in IMC-PID tuning rule for the improved disturbance rejection. For the modified IMC-PID tuning rule, a method has been developed to obtain the IMC-PID setting in closed-loop mode without acquiring detailed information of the process. The proposed method is based on the closed-loop step set point experiment using a proportional only controller with gain K_(c0). It is the direct approach to find the PID controller setting similar to classical Ziegler-Nichols closed-loop method. Based on simulations of a wide range of first-order with delay processes, a simple correlation has been derived to obtain the modified IMC-PID controller settings from closed-loop experiment. In this method, controller gain is a function of the overshoot obtained in the closed loop set point experiment. The integral and derivative time is mainly a function of the time to reach the first peak(overshoot). Simulation has been conducted for the broad class of processes and the controllers were tuned to have the same degree of robustness by measuring the maximum sensitivity, Ms, in order to obtain a reasonable comparison. The PID controller settings obtained in the proposed tuning method show better performance and robustness with other two-step tuning methods for the broad class of processes. It has also been applied to temperature control loop in distillation column model. The result has been compared to the open loop tuning method where it gives robust and fast response.

关键词： PI/PID controller step test closed-loop response IMC-PID overshoot

Efficient Wind Turbine Generation Planning for Decreasing Distribution System Company Payments in Real Applications

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Journal of Modern Power Systems and Clean Energy 2022年第1期10卷 81-90页

作者： mohammad Hasan Hemmatpour mohammad Hossein Rezaeian Koochi Electrical Engineering Department Faculty of EngineeringJahrom UniversityJahromIran Department of Electrical Engineering Shahid Bahonar University of KermanKermanIran

Wind energy has posed new challenges in both transmission and distribution systems owing to its uncertain nature. The effect of wind turbines (WTs) on the actual payments charged by upstream networks to distribution system companies (DISCOs) is one challenge. Moreover, when the grid-connected inverters of WT operate in the lead or lag modes, WTs absorb or inject reactive power from the system. This paper proposes an approach to assess the importance of operation modes of WTs to minimize the costs by DISCOs in the presence of system uncertainties. Accordingly, an optimization problem is formulated to minimize the costs to DISCO by determining the optimal locations and sizes of WTs in optimally reconfigured distribution systems. In addition, an improved vector-based swarm optimization (IVBSO) algorithm is proposed because it is highly suitable for vector-based problems. Two distribution systems are used in the simulations to evaluate the proposed algorithm. Firstly, the capabilities of the IVBSO algorithm to determine better solutions over other heuristic algorithms are confirmed using the IEEE 33-bus test system. Secondly, the BijanAbad distribution system (BDS) is used to demonstrate the effectiveness of the proposed optimization problem. Accordingly, the distribution system model, cumulative distribution function of wind speed, and load profile are all extracted from the actual data of the BijanAbad region. Finally, the optimization problem is applied to BDS in both the lead and lag modes of WTs. Results indicate that the total costs of DISCO are lower when WTs operate in the lag mode than in the lead mode.

关键词： Distribution system companies(DISCOs) improved vector-based swarm optimization(IVBSO) reconfiguration wind turbine operation mode

Effect of volume-contraction on incipient fluidization of binary-solid mixtures

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Particuology 2011年第2期9卷 101-106页

作者： mohammad Asif Chemical Engineering Department King Saud University

Towards the development of a predictive model for computing the minimum fluidization velocity, the volume-contraction phenomenon arising from the mixing of unequal solid species is accounted for in the prediction of the bed void fraction of binary-solid mixtures at the incipient fluidization conditions. Com- parison with experimental data obtained from the literature clearly shows that significantly improved predictions are obtained except for cases where the stratification pattern whether arising from the slow defluidization or the difference in the densities of the two species affects the mixing of the constituent species.

关键词： Binary solid mixture Bed void fraction Volume-contraction Minimum fluidization velocity

Approximation of structural damping and input excitation force

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Frontiers of Structural and Civil Engineering 2017年第2期11卷 244-254页

作者： mohammad SALAVATI Institute of Structural Mechanics Faculty of Civil Engineering Bauhaus University Weimar Weimar 99423 Germany

Structural dynamic characteristics are the most significant parameters that play a decisive role in structural damage assessment. The more sensitive parameter to the damage is the damping behavior of the structure. The complexity of structural damping mechanisms has made this parameter to be one of the ongoing research topics. Despite all the difficulties in the modeling of damping, there are some approaches like as linear and nonlinear models which are described as the energy dissipation throughout viscous, material or structural hysteretic and frictional damping mechanisms. In the presence of a mathematical model of the damping mechanisms, it is possible to estimate the damping ratio from the theoretical comparison of the damped and un-damped systems. On the other hand, solving the inverse problem of the input force estimation and its distribution to each SDOFs, from the measured structural responses plays an important role in structural identification process. In this paper model-based damping approximation method and a modelless structural input estimation are considered. The effectiveness of proposed methods has been carded out through analytical and numerical simulation of the lumped mass system and the results are compared with reference data. Consequently, high convergence of the comparison results illustrates the satisfactory of proposed approximation methods.

关键词： structural modal parameters damping identification method input excitation force identification Inverse problem