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Analytical dynamic solution of a flexible cable-suspended manipulator

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Frontiers of Mechanical Engineering 2013年第4期8卷 350-359页

作者： mahdi BAMDAD Mechatronics Research Laboratory College of Mechanical EngineeringShahrood University of Technology

Cable-suspended manipulators are used in large scale applications with,heavy in weight and long in span *** seems impractical to maintain cable assumptions of smaller robots for large scale *** interactions among the cables,platforms and actuators can fully evaluate the coupled dynamic *** structural flexibility of the cables becomes more pronounced in large *** this paper,an analytic solution is provided to solve cable ***,a closed form solution can be adopted to improve the dynamic response to *** output is provided by the optimal torque generation subject to the actuator limitations in a mechatronic ***,the performance of the proposed algorithm is examined through simulations.

关键词： parallel robot flexible cable suspended robot dynamic

A new robust fuzzy method for unmanned flying vehicle control

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Journal of Central South University 2015年第6期22卷 2166-2182页

作者： Mojtaba Mirzaei Mohammad Eghtesad Mohammad mahdi Alishahi Department of Mechanical Engineering Shiraz University

A new general robust fuzzy approach was presented to control the position and the attitude of unmanned flying vehicles(UFVs). Control of these vehicles was challenging due to their nonlinear underactuated behaviors. The proposed control system combined great advantages of generalized indirect adaptive sliding mode control(IASMC) and fuzzy control for the UFVs. An on-line adaptive tuning algorithm based on Lyapunov function and Barbalat lemma was designed, thus the stability of the system can be guaranteed. The chattering phenomenon in the sliding mode control was reduced and the steady error was also alleviated. The numerical results, for an underactuated quadcopter and a high speed underwater vehicle as case studies, indicate that the presented adaptive design of fuzzy sliding mode controller performs robustly in the presence of sensor noise and external disturbances. In addition, online unknown parameter estimation of the UFVs, such as ground effect and planing force especially in the cases with the Gaussian sensor noise with zero mean and standard deviation of 0.5 m and 0.1 rad and external disturbances with amplitude of 0.1 m/s2 and frequency of 0.2 Hz, is one of the advantages of this method. These estimated parameters are then used in the controller to improve the trajectory tracking performance.

关键词： adaptive fuzzy sliding-mode control unmanned flying vehicle control underactuated system Lyapunov stability high speed underwater vehicle

Hybrid Dynamic Neural Network and PID Control of Pneumatic Artificial Muscle Using the PSO Algorithm

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International Journal of Automation and computing 2020年第3期17卷 428-438页

作者： mahdi Chavoshian Mostafa Taghizadeh Mahmood Mazare School of Mechanical Engineering Sh.Beheshti UniversityTehran 16589-53571Iran

Pneumatic artificial muscles(PAM)have been recently considered as a prominent challenge regarding pneumatic actuators specifically for rehabilitation and medical *** accomplishing accurate control of the PAM is comparatively complicated due to time-varying behavior,elasticity and ambiguous characteristics,a high performance and efficient control approach should be *** of the mentioned challenges,limited course length is another predicament with the PAM *** this regard,this paper proposes a new hybrid dynamic neural network(DNN)and proportional integral derivative(PID)controller for the position of the *** order to enhance the proficiency of the controller,the problem under study is designed in the form of an optimization *** the potential of particle swarm optimization,it has been applied to optimally tune the PID-DNN *** verify the performance of the proposed controller,it has been implemented on a real-time system and compared to a conventional sliding mode *** and experimental results show the effectiveness of the proposed controller in tracking the reference signals in the entire course of the PAM.

关键词： Dynamic neural network(DNN)control hybrid control pneumatic muscle particle swarm optimization sliding mode control

Dynamic Spatio-Temporal Tweet Mining for Event Detection:A Case Study of Hurricane Florence

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International Journal of Disaster Risk Science 2020年第3期11卷 378-393页

作者： mahdi Farnaghi Zeinab Ghaemi Ali Mansourian GIS Center Department of Physical Geography and Ecosystem ScienceLund University22362 LundSweden Faculty of Geodesy and Geomatics K.N.Toosi University of TechnologyTehranIran Center for Middle Eastern Studies Lund University22100 LundSweden

Extracting information about emerging events in large study areas through spatiotemporal and textual analysis of geotagged tweets provides the possibility of monitoring the current state of a *** study proposes dynamic spatio-temporal tweet mining as a method for dynamic event extraction from geotagged tweets in large study *** introduces the use of a modified version of ordering points to identify the clustering structure to address the intrinsic heterogeneity of Twitter *** precisely calculate the textual similarity,three state-of-theart text embedding methods of Word2vec,GloVe,and Fast Text were used to capture both syntactic and semantic *** impact of selected embedding algorithms on the quality of the outputs was *** combinations of spatial and temporal distances with the textual similarity measure were investigated to improve the event detection *** proposed method was applied to a case study related to 2018 Hurricane *** method was able to precisely identify events of varied sizes and densities before,during,and after the *** feasibility of the proposed method was qualitatively evaluated using the Silhouette coefficient and qualitatively *** proposed method was also compared to an implementation based on the standard density-based spatial clustering of applications with noise algorithm,where it showed more promising results.

关键词： Disaster management Hurricane Florence Natural language processing Spatio-temporal tweet analysis Tweet clustering Twitter

Correlating thermal conductivity of pure hydrocarbons and aromatics via perceptron artificial neural network (PANN) method

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Chinese Journal of Chemical Engineering 2017年第5期25卷 547-554页

作者： Mostafa Lashkarbolooki Ali Zeinolabedini Hezave mahdi Bayat School of Chemical Engineering Babol University of Technology Islamic Azad University Dashtestan Branch Department of Chemical Engineering Faculty of EngineeringUniversity of Bojnord

Accurate estimation of liquid thermal conductivity is highly necessary to appropriately design equipments in different industries. Respect to this necessity, in the current investigation a feed-forward artificial neural network(ANN) model is examined to correlate the liquid thermal conductivity of normal and aromatic hydrocarbons at the temperatures range of 257–338 K and atmospheric pressure. For this purpose, 956 experimental thermal conductivities for normal and aromatic hydrocarbons are collected from different previously published *** the modeling stage, to discriminate different substances, critical temperature(Tc), critical pressure(Pc)and acentric factor(ω) are utilized as the network inputs besides the temperature. During the examination, effects of different transfer functions and number of neurons in hidden layer are investigated to find the optimum network architecture. Besides, statistical error analysis considering the results obtained from available correlations and group contribution methods and proposed neural network is performed to reliably check the feasibility and accuracy of the proposed method. Respect to the obtained results, it can be concluded that the proposed neural network consisted of three layers namely, input, hidden and output layers with 22 neurons in hidden layer was the optimum ANN model. Generally, the proposed model enables to correlate the thermal conductivity of normal and aromatic hydrocarbons with absolute average relative deviation percent(AARD), mean square error(MSE), and correlation coefficient(R^2) of lower than 0.2%, 1.05 × 10^(-7) and 0.9994, respectively.

关键词： Thermal conductivity Artificial neural network Critical properties Hydrocarbons Aromatics

Design and analysis of resonant cavity-enhanced quantum ring inter-subband photodetector with resonant tunneling barriers for terahertz detection

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红外与毫米波学报 2014年第6期33卷 571-576页

作者： mahdi Zavvari Mohammad Karimi Kambiz Abedi Department of Electrical Engineering Urmia BranchIslamic Azad University Department of Electrical Engineering Ahar BranchIslamic Azad University Department of Electrical Engineering Faculty of Electrical and Computer EngineeringShahid Beheshti University

The effect of resonant cavity structure on the performance operation of In As/Ga As quantum ring intersubband photodetector is studied for detection of terahertz radiations *** order to confinement of optical field w ithin active region and consequently enhancement in responsivity of device,tw o periods of Al2O3/Ga As distributed bragg reflectors are used as bottom dielectric mirror and a thin layer of Au material as top mirror of *** further improvement in detectivity,Al0.3Ga0.7As/In0.3Ga0.7As resonant tunneling barriers are included in absorption layers to reduce dark current of *** photodetector show s a peak responsivity of about 0.4(A/W)and quantum efficiency of 1.2%at the w avelength of 80μm(3.75 THz).Furthermore,specific detectivity(D*)of device is calculated and results are compared to conventional quantum ring inter-subband *** predict a D*of^1011(***1/2/W)for device at T=80 K and V=0.4 V w hich is tw o orders of magnitude higher than that of conventional QRIPs.

关键词：量子环理论研究辐射范围共振吸收层

Study of acoustic bubble cluster dynamics using a lattice Boltzmann model

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Chinese Physics B 2015年第2期24卷 263-270页

作者： mahdi Daemi Mohammad Taeibi-Rahni Hamidreza Massah Aerospace Engineering Department Sharif University of Technology Physics Department Ferdowsi University

The search for the development of a reliable mathematical model for understanding bubble dynamics behavior is an ongoing endeavor.A long list of complex phenomena underlies the physics of this *** the past decades,the lattice Boltzmann method has emerged as a promising tool to address such *** this regard,we have applied a 121-velocity multiphase lattice Boltzmann model to an asymmetric cluster of bubbles in an acoustic field.A problem as a benchmark is studied to check the consistency and applicability of the *** problem of interest is to study the deformation and coalescence phenomena in bubble cluster dynamics,as well as the screening effect on an acoustic multibubble *** has been observed that the LB model is able to simulate the combination of the three aforementioned phenomena for a bubble cluster as a whole and for every individual bubble in the cluster.

关键词： multiphase lattice Boltzmann model acoustic field multi-bubble bubble cluster dynamics cavitation

Hot compression deformation behavior of AISI 321 austenitic stainless steel

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International Journal of Minerals,Metallurgy and Materials 2013年第6期20卷 529-534页

作者： Mehdi haj Hojjatollah Mansouri Reza Vafaei Golam Reza Ebrahimi Ali Kanani Department of Materials Engineering Malek Ashtar University of Technology Department of Materials and Polymer Engineering Faculty of Engineering Hakim Sabzevari University

The hot compression behavior of AISI 321 ll00~C and the strain rates of 0.01-1 s-1 using a Baehr austenitic stainless steel was studied at the temperatures of 950- DIL-805 deformation dilatometer. The hot deformation equations and the relationship between hot deformation parameters were obtained. It is found that strain rate and deformation temperature significantly influence the flow stress behavior of the steel. The work hardening rate and the peak value of flow stress increase with the decrease of deformation temperature and the increase of strain rate. In addition, the activation energy of deformation （Q） is calculated as 433.343 kJ/mol. The microstructural evolution during deformation indicates that, at the temperature of 950~C and the strain rate of 0.01 s-1, small circle-like precipitates form along grain boundaries; but at the temperatures above 950~C, the dissolution of such precipitates occurs. Energy-dispersive X-ray analyses indicate that the precipitates are complex carbides of Cr, Fe, Mn, Ni, and Ti.

关键词： austenitic stainless steel deformation constitutive equations microstructural evolution activation energy

Predicting seismic permanent displacement of soil walls under surcharge based on limit analysis approach

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Earthquake Engineering and Engineering Vibration 2018年第4期17卷 747-759页

作者： Mohammad mahdi Aminpour Mohammad Maleki Ali Ghanbari Faculty of Engineering Bu-Ali Sina University Faculty of Engineering Kharazmi University

Seismic permanent displacement of the soil walls plays an important role in design of these structures. Due to the increase in growth of urban areas and the limitations in use of flat grounds, many structures are built near slopes and retaining walls. During earthquakes, these structures can apply an additional surcharge on the wall. The intensity and location of the surcharge is of considerable importance on the seismic displacements of the soil wall. In this study, by using the limit analysis and upper bound theorem, seismic permanent displacement of the soil wall under surcharge has been analyzed. Thus, a formulation is presented for calculating the yield acceleration and seismic displacement for different surcharge conditions. The effect of seismic acceleration, surcharge intensity, its location and soil properties is investigated. A parameter called the ＂displacement coefficient＂ is proposed, and is a potential modification for Newmark’s sliding-block method.

关键词： limit analysis surcharge soil wall seismic displacement yield acceleration