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A Low Power and High Bandwidth Anti Aliasing Filter with Transconductance Structure for DAB Receivers

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通讯和计算机（中英文版） 2011年第5期8卷 373-380页

作者： mohammad mehdi farhad Sattar Mirzakuchaki Engineering-Department of Electronic Islamic Azad University Saveh branch Saveh 39197-15179 lran Electrical Engineering Department Electronic Research Center Iran University of Science ＆ Technology Tehran 16846 Iran

Identification of Pitch Dynamics of An Autonomous Underwater Vehicle Using Sensor Fusion

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China Ocean Engineering 2019年第5期33卷 563-572页

作者： Seid farhad Abtahi mohammad mehdi Alishahi Ehsan Azadi Yazdi Department of Mechanical Engineering Shiraz University

This paper presents a method for identification of the hydrodynamic coefficients of the dive plane of an autonomous underwater vehicle. The proposed identification method uses the governing equations of motion to estimate the coefficients of the linear damping, added mass and inertia, cross flow drag and control. Parts of data required by the proposed identification method are not measured by the onboard instruments. Hence, an optimal fusion algorithm is devised which estimates the required data accurately with a high sampling rate. To excite the dive plane dynamics and obtain the required measurements, diving maneuvers should be performed. Hence, a reliable controller with satisfactory performance and stability is needed. A cascaded controller is designed based on the coefficients obtained using a semi-empirical method and its robustness to the uncertainties is verified by the μ-analysis method. The performance and accuracy of the identification and fusion algorithms are investigated through 6-DOF numerical simulations of a realistic autonomous underwater vehicle.

关键词： autonomous underwater vehicles hydrodynamic coefficients system identification robust control sensor fusion parameter estimation numerical methods

Reliability and sensitivity analysis of wedge stability in the abutments of an arch dam using artificial neural network

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Earthquake Engineering and Engineering Vibration 2022年第4期21卷 1019-1033页

作者： Hasan Mostafaei farhad Behnamfar mohammad Alembagheri Department of Civil Engineering Isfahan University of TechnologyIsfahan 84156-83111Iran Department of Civil and Environmental Engineering Tarbiat Modares UniversityTehran 11155-9313Iran

In this study,the seismic stability of arch dam abutments is investigated within the framework of the probabilistic method.A large concrete arch dam is considered with six wedges for each *** seismic safety of the dam abutments is studied with quasi-static analysis for different hazard *** Londe limit equilibrium method is utilized to calculate the stability of the wedges in the *** the finite element method is time-consuming,the neural network is used as an alternative for calculating the wedge safety *** training the neural network,1000 random samples are generated and the dam response is *** direction of applied acceleration is changed within 5-degree intervals to reveal the critical direction corresponding to the minimum safety *** Latin hypercube sampling(LHS)is employed for sample generation,and the safety level is determined with reliability *** sample numbers of 1000,2000 and 4000 are used to examine the average and standard deviation of the *** global sensitivity analysis is used to identify the effects of random variables on the abutment *** is shown that friction,cohesion and uplift pressure have the most significant effects on the wedge stability variance.

关键词： arch dam seismic reliability artificial neural network Latin hypercube sampling sensitivity analysis wedge abutment

Cobalt supported on CNTs-covered γ-and nano-structured alumina catalysts utilized for wax selective Fischer-Tropsch synthesis

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Journal of Natural Gas Chemistry 2012年第6期21卷 713-721页

作者： mohammad Reza Hemmati mohammad Kazemeini farhad Khorasheh Jamshid Zarkesh Alimorad Rashidi Sharif University of Technology(SUT) Department of Chemical & Petroleum Engineering Research Institute of Petroleum Industry(RIPI)

Cobalt supported on carbon nanotubes （CNTs）-covered alumina has been recently developed and successfully utilized as a catalyst in Fischer-Tropsch synthesis （FTS）. Problems associated with shaping of Co/CNTs into extrudates or pellets as well as catalyst attrition rendered these materials unfavorable for industrial applications. In this investigation regular γ- and nano-structured （N-S） alumina as well as CNTs-covered regular γ- and N-S-alumina supports were impregnated by cobalt nitrate solution to make new cobalt-based catalysts which were also promoted by Ru. The catalysts were characterized and tested in a micro reactor to evaluate their applicability in FTS. γ-Al2O3 was prepared by calcination of bohemite and N-S-Al2O3 was prepared by sol-gel method using aluminum chloride as starting material. Catalyst evaluations indicated that N-S-Al2O3 was superior to regular γ-Al2O3 and that CNTs-covered alumina supports were favored over non-covered ones in terms of activity and heavy hydrocarbon selectivity. These were justified by porosimetric characteristics of the catalysts and existence of CNTs points of view. CNTs-covered catalysts also showed higher wax selectivity and better resistance to deactivation. Furthermore, TPR analysis indicated that the cobalt aluminate phase, which is responsible for the permanent deactivation of alumina supported Co-based catalysts, did not form on alumina supported Co-based catalysts covered with CNTs due to weaker interactions between cobalt and alumina.

关键词： Fischer-Tropsch synthesis nano-structured alumina gamma alumina carbon nanotubes catalyst deactivation

Effect of nano powder(Al2O3-CaO)addition on the mechanical properties of the polymer blend matrix composite

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Defence Technology（防务技术） 2020年第2期16卷 425-431页

作者： Hayder Abbas Sallal Alaa AAbdul-Hamead farhad mohammad Othman Material Engineering Department University of TechnologyBaghdadIraq

This work describes the preparation and study of the properties of composite nanoparticles prepared by the sol-gel method which consists of two materials(Al2 O3-CaO),and study the effect of these nanoparticles on the mechanical behavior of a polymer blend(EP 4%+96%UPE).The powder was evaluated by X-ray diffraction analysis,scanning electron microscopy analysis(SEM),particle size analysis,and energy dispersive X-ray analysis(EDX).The mechanical behavior of the co mposite material was assessed by tensile test,bending test and hardness *** evaluation results of the composite nanoparticles showed good distribution of the chemical composition between aluminum oxide and calcium oxide,smoothness in particles’size at calcination in high and low temperatures,formation of different shapes of nanoparticles and different(kappa and gamma)phases of the Al2 O *** results of mechanical behavior tests showed marked improvement in the mechanical properties of the resulted composite material,especially at 1.5%,compared with polymer blend material without nano powder *** tensile properties improved about(24 and 14.9)%and bending resistance about(23.5 and16.8)%and hardness by(25 and 22)%when adding particles of size(63.8 and 68.6)***,this reflects the efficiency of the proposed method to manufacture the nanoco mposite powder and the possibility of using this powder as a strengthening material for the composite materials and using these composite materials in bio applications,especially in the fabrication of artificial limbs.

关键词： Composite nanoparticles Sol-gel method Polymer blend matrix Nanocomposites Mechanical properties

NUMERICAL PREDICTIONS AND EXPERIMENTAL VALIDATIONS OF DUCTILE DAMAGE EVOLUTION IN SHEET METAL FORMING PROCESSES

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Acta Mechanica Solida Sinica 2012年第6期25卷 638-650页

作者： farhad Haji Aboutalebi Mahmoud Farzin mohammad Mashayekhi Department of Mechanical Engineering University of Isfahan Department of Mechanical Engineering Isfahan University of Technology

Prediction of forming limit in sheet metal forming is among the most important challenges confronting researchers. In this paper, a fully coupled elastic-plastic-damage model has been developed and implemented into an explicit code. Due to the adoption of the plane stress and finite strain theories, model can predict deformation and damage of parts quickly and accurately. Also, damage initiation, propagation, and fracture in some operations are predicted and validated with experiments. It is concluded that finite strain combined with continuum damage mechanics can be used as a quick tool to predict ductile damage, fracture, and forming limits in sheet metal forming processes.

关键词： ductile damage finite strain fracture sheet metal forming

Melamine trisulfonic acid:A new,efficient and recyclable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones in the absence of solvent

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Chinese Chemical Letters 2011年第3期22卷 318-321页

作者： farhad Shirini mohammad Ali Zolfigol Jalal Albadi Department of Chemistry College of ScienceUniversity of GuilanRasht 41335Islamic Republic of Iran College of Chemistry Bu-Ali Sina UniversityHamadanIslamic Republic of Iran

Melamine trisulfonic acid（MTSA） can be used as an efficient and recyclable catalyst for the promotion of the synthesis of 3,4- dihydropyrimidin-2（1H）-ones/thiones（DHPMs） in the absence of *** reactions were perf... 详细信息

关键词： Melamine trisulfonic acid 3 4-Dihydropyrimidin-2(1H)-ones/thiones Biginelli reaction Aldehydes Solvent-free reactions

Investigation of a Centrifugal Compressor and Study of the Area Ratio and TIP Clearance Effects on Performance

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Journal of Thermal Science 2008年第4期17卷 314-323页

作者： Mahdi Nili-Ahmadabadi Ali Hajilouy-Benisi mohammad Durali farhad Ghadak School of Mechanical Engineering Center of Excellence in Energy ConversionSharif University of Technology Aerospace Engineering Department Emam Hossein University

In this research, the centrifugal compressor of a turbocharger is investigated experimentally and numerically. Performance characteristics of the compressor were obtained experimentally by measurements of rotor speed and flow parameters at the inlet and outlet of the compressor. Three dimensional flow field in the impeller and dif- fuser was analyzed numerically using a full Navier-Stokes program with SST turbulence model. The performance characteristics of the compressor were obtained numerically, which were then compared with the experimental results. The comparison shows good agreement. Furthermore, the effect of area ratio and tip clearance on the performance parameters and flow field was stud- ied numerically. The impeller area ratio was changed by cutting the impeller exit axial width from an initial value of 4.1 mm to a final value of 5.1 mm, resulting in an area ratio from 0.792 to 0.965. For the rotor with exit axial width of 4.6 mm, performance was investigated for tip clearance of 0.0, 0.5 and 1.0 mm. Results of this simula- tion at design point showed that the compressor pressure ratio peaked at an area ratio of 0.792 while the effi- ciency peaked at a higher value of area ratio of 0.878. Also the increment of the tip clearance from 0 to 1 mm resulted in 20 percent efficiency decrease.

关键词： centrifugal compressor area ratio tip clearance effect

Fe(NO_3)_3·9H_2O/Fe(HSO_4)_3:An efficient reagent system for the oxidation of alcohols,thiols and sulfides in the absence of solvent

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Chinese Chemical Letters 2008年第1期19卷 51-54页

作者： farhad Shirini mohammad A.Zolfigol Abdol-Reza Abri Department of Chemistry College of ScienceUniversity of GuilanRasht 41335Iran College of Chemistry Bu-Ali Sina UniversityHamadan 65174Iran

Fe（NO3）3-9H2O/Fe（HSO4）3 was used as an efficient reagent system for the oxidation of alcohols to their corresponding carbonyl compounds. All reactions were performed in the absence of solvent in good to high yields. Under the same reaction conditions, thiols and sulfides were also converted to their corresponding disulfides and sulfoxides, respectively. 2007 farhad Shirini. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

关键词： Alcohols Thiols Sulfides Fe(NO3)3·9H2O Fe(HSO4)3