检索结果-南通市图书馆

Interplay between temperature-dependent strengthening mechanisms and mechanical stability in high-performance austenitic stainless steels

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2182-2188页

作者： mohammad javad sohrabi Hamed Mirzadeh Saeed Sadeghpour Milad Zolfipour Aghdam Abdol Reza Geranmayeh Reza Mahmudi School of Metallurgy and Materials Engineering College of EngineeringUniversity of Tehran14395-515 TehranIran Centre for Advanced Steels Research Materials and Mechanical EngineeringUniversity of Oulu90014 OuluFinland Department of Mechanical Engineering College of EngineeringUniversity of Tehran14395-515 TehranIran

The effects of deformation temperature on the transformation-induced plasticity(TRIP)-aided 304L,twinning-induced plasti-city(TWIP)-assisted 316L,and highly alloyed stable 904L austenitic stainless steels were compared for the first time to tune the mechan-ical properties,strengthening mechanisms,and strength-ductility *** this purpose,the scanning electron microscopy(SEM),electron backscattered diffraction(EBSD),X-ray diffraction(XRD),tensile testing,work-hardening analysis,and thermodynamics calcu-lations were *** induced plasticity effects led to a high temperature-dependency of work-hardening behavior in the 304L and 316L stainless *** the deformation temperature increased,the metastable 304L stainless steel showed the sequence of TRIP,TWIP,and weakening of the induced plasticity mechanism;while the disappearance of the TWIP effect in the 316L stainless steel was also ***,the solid-solution strengthening in the 904L superaustenitic stainless steel maintained the tensile properties over a wide temper-ature range,surpassing the performance of 304L and 316L stainless *** this regard,the dependency of the total elongation on the de-formation temperature was less pronounced for the 904L alloy due to the absence of additional plasticity *** results re-vealed the importance of solid-solution strengthening and the associated high friction stress for superior mechanical behavior over a wide temperature range.

关键词： austenitic stainless steels mechanical behavior stacking fault energy metastability mechanical twinning

A Nonlinear Coordinated Approach to Enhance the Transient Stability of Wind Energy-Based Power Systems

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2020年第4期7卷 1087-1097页

作者： mohammad javad Morshed the Department of Electrical and Computer Engineering University of Louisiana at LafayetteLafayetteLA 70504 USA

This paper proposes a novel framework that enables the simultaneous coordination of the controllers of doubly fed induction generators(DFIGs) and synchronous generators(SGs).The proposed coordination approach is based on the zero dynamics method aims at enhancing the transient stability of multi-machine power systems under a wide range of operating conditions. The proposed approach was implemented to the IEEE39-bus power systems. Transient stability margin measured in terms of critical clearing time along with eigenvalue analysis and time domain simulations were considered in the performance assessment. The obtained results were also compared to those achieved using a conventional power system stabilizer/power oscillation(PSS/POD) technique and the interconnection and damping assignment passivity-based controller(IDA-PBC). The performance analysis confirmed the ability of the proposed approach to enhance damping and improve system’s transient stability margin under a wide range of operating conditions.

关键词： Doubly fed induction generator(DFIG) excitation controller multi-machine power system synchronous generator(SG) transient stability zero dynamics

Optimal PD/PID control of smart base isolated buildings equipped with piezoelectric friction dampers

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2013年第1期12卷 39-54页

作者： Sadegh Etedali mohammad Reza sohrabi Saeed Tavakoli .Department of Civil Engineering Faculty of EngineeringUniversity of Sistan and Baluchestan Department of Civil Engineering Faculty of EngineeringUniversity of Sistan and Baluchestan Faculty of Electrical and Computer Engineering University of Sistan and Baluchestan

Long-period pulses in near-field earthquakes lead to large displacements in the base of isolated *** dissipate energy in isolated structures using semi-active control,piezoelectric friction dampers（PFD） can be *** performance of a PFD is highly dependent on the strategy applied to adjust its contact *** this paper,the seismic control of a benchmark isolated building equipped with PFD using PD/PID controllers is *** genetic algorithms,these controllers are optimized to create a balance between the performance and robustness of the closed-loop structural *** advantage of this technique is that the controller forces can easily be *** addition,the structure is equipped with only a single sensor at the base floor to measure the base *** seven pairs of earthquakes and nine performance indices,the performance of the closed-loop system is ***,the results are compared with those given by two well-known methods：the maximum possive operation of piezoelectric friction dampers and LQG *** simulation results show that the proposed controllers perform better than the others in terms of simultaneous reduction of floor acceleration and maximum displacement of the ***,they are able to reduce the displacement of the isolator systems for different earthquakes without losing the advantages of isolation.

关键词： seismic isolation semi-active control piezoelectric friction dampers PD/PID controllers

Fuzzy TOPSIS method to primary crusher selection for Golegohar Iron Mine(Iran)

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2014年第11期21卷 4352-4359页

作者： mohammad javad Rahimdel mohammad Karamoozian Department of Mining Engineering Sahand University of TechnologyTabriz 51335-1996 Iran Faculty of Mining Engineering Petroleum and Geophysics Shahrood University of TechnologyShahrood 361999 5161 Iran

Selection of the crusher required a great deal of design regarding to the mine planning. Selection of suitable primary crusher from all of available primary crushers is a multi-criterion decision making(MCDM) problem. The present work explores the use of technique for order performance by similarity to ideal solution(TOPSIS) with fuzzy set theory to select best primary crusher for Golegohar Iron Mine in Iran. Gyratory, double toggle jaw, single toggle jaw, high speed roll crusher, low speed sizer, impact crusher, hammer mill and feeder breaker crushers have been considered as alternatives. Also, the capacity, feed size, product size, rock compressive strength, abrasion index and application of primary crusher for mobile plants were considered as criteria for solution of this MCDM problem. To determine the order of the alternatives, closeness coefficient is defined by calculating the distances to the fuzzy positive ideal solution(FPIS) and fuzzy negative ideal solution(FNIS). Results of our work based on fuzzy TOPSIS method show that the gyratory is the best primary crusher for the studied mine.

关键词： primary crusher multi-criterion decision making(MCDM) technique for order performance by similarity to ideal solution fuzzy set theory Golegohar Iron Mine gyratory crusher

Application of Statistical Methods to Biomarkers for Geochemical Evaluation and Genetic Type Determination of Gas Condensates in the Persian Gulf and Coastal Fars,Southern Iran

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2022年第4期96卷 1246-1256页

作者： mohammad javad SEIDY mohammad Hossein SABERI Petroleum Engineering Department Semnan UniversitySemnanIran The New Technology Campus Petroleum Engineering DepartmentSemnan UniversitySemnanIran

In a comprehensive geochemical study,the genetic relationships among 14 samples of gas condensates from the Persian Gulf were investigated for the purpose of evaluating the respective source rocks in terms of both age and sedimentary *** analysis was used for categorization and determination of a certitude range to determine the genetic type of the condensate families in the studied *** samples were collected from Late Permian-Triassic reservoirs(Dalan and Kangan formations)located in 6 gasfields(gas condensate)hosting some of Iran’s most important gas/gas condensate *** by gas chromatography-mass spectrometry(GC-MS),a total of 16 biomarker parameters(10 maturity-related parameters and 6 sedimentary environment-related parameters)were used to evaluate the samples in terms of thermal maturity(and hence their positions in the maturity chart),the sedimentary environment of the source rock and the *** of Hierarchical Clustering Analysis(HCA)and Principal Component Analysis(PCA)to the collected data led to the categorization of the samples into three main genetic groups,Ⅰ-Ⅲ.GroupsⅠandⅢwere found to be located in the east and the west of the Persian Gulf,respectively,while GroupⅡwas developed between the two other groups.

关键词： gas condensate satistical methods genetic linkage thermal maturation Persian Gulf Coastal Fars

A Sliding Mode Approach to Enhance the Power Quality of Wind Turbines Under Unbalanced Voltage Conditions

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2期6卷 566-574页

作者： mohammad javad Morshed Afef Fekih IEEE the Department of Electrical and Computer Engineering University of Louisiana at Lafayette

An integral terminal sliding mode-based control design is proposed in this paper to enhance the power quality of wind turbines under unbalanced voltage conditions. The design combines the robustness, fast response, and high quality transient characteristics of the integral terminal sliding mode control with the estimation properties of disturbance observers. The controller gains were auto-tuned using a fuzzy logic *** effectiveness of the proposed design was assessed under deep voltage sag conditions and parameter variations. Its dynamic response was also compared to that of a standard SMC *** performance analysis and simulation results confirmed the ability of the proposed approach to maintain the active power,currents, DC-link voltage and electromagnetic torque within their acceptable ranges even under the most severe unbalanced voltage conditions. It was also shown to be robust to uncertainties and parameter variations, while effectively mitigating chattering in comparison with the standard SMC.

关键词： Doubly fed induction generators(DFIG) fuzzy approach integral terminal sliding mode control(ITSMC) observer power quality voltage unbalances wind turbines

A novel hybrid algorithm based on a harmony search and artificial bee colony for solving a portfolio optimization problem using a mean-semi variance approach

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2016年第1期23卷 181-188页

作者： Seyed mohammad Seyedhosseini mohammad javad Esfahani Mehdi Ghaffari Department of Industrial Engineering Iran University of Science and Technology Young Researchers and Elite Club Naragh BranchIslamic Azad University Department of Industrial Engineering Naragh BranchIslamic Azad University

Portfolio selection is one of the major capital allocation and budgeting issues in financial management, and a variety of models have been presented for optimal selection. Semi-variance is usually considered as a risk factor in drawing up an efficient frontier and the optimal portfolio. Since semi-variance offers a better estimation of the actual risk portfolio, it was used as a measure to approximate the risk of investment in this work. The optimal portfolio selection is one of the non-deterministic polynomial(NP)-hard problems that have not been presented in an exact algorithm, which can solve this problem in a polynomial time. Meta-heuristic algorithms are usually used to solve such problems. A novel hybrid harmony search and artificial bee colony algorithm and its application were introduced in order to draw efficient frontier portfolios. Computational results show that this algorithm is more successful than the harmony search method and genetic algorithm. In addition, it is more accurate in finding optimal solutions at all levels of risk and return.

关键词： portfolio optimizations mean-variance model mean semi-variance model harmony search and artificial bee colony efficient frontier

Micromechanical simulation and experimental investigation of aluminum-based nanocomposites

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2021年第1期17卷 196-201页

作者： mohammad javad Ghasemi mohammad Silani Ali Maleki Mostafa Jamshidian Department of Mechanical Engineering Isfahan University of TechnologyIsfahan84156-83111Iran

Ceramic reinforced metal matrix nanocomposites are widely used in aerospace and auto industries due to their enhanced mechanical and physical *** this research,we investigate the mechanical properties of aluminum/Nano-silica composites through experiments and ***/Nanosilica composite samples with different weight percentages of silica nanoparticles are prepared via powder *** this method,Nano-silica and aluminum powders are mixed and compressed in a mold,followed by sintering at high *** tensile testing of the nanocomposite samples shows that adding one percent of Nano-silica causes a considerable increase in mechanical properties of nanocomposite compared to pure aluminum.A computational micromechanical model,based on a representative volume element of aluminum/silica nanocomposite,is developed in a commercial finite element *** model employs an elastoplastic material model along with a ductile damage model for aluminum matrix and linear elastic model for nano-silica *** careful determination of model parameters from the experimental results of pure aluminum samples prepared by powder metallurgy,the proposed computational model has shown satisfactory agreement with *** validated computational model can be used to perform a parametric study to optimize the microstructure of nanocomposite for enhanced mechanical properties.

关键词： Aluminum/nano-silica composites Powder metallurgy Micromechanics

Enhancing Sound Absorption in Micro-Perforated Panel and Porous Material Composite in Low Frequencies:A Numerical Study Using FEM

在线全文

学校读者我要写书评

暂无评论

Sound & Vibration 2024年第1期58卷 81-100页

作者： mohammad javad SheikhMozafari Department of Occupational Health Engineering School of Public HealthTehran University of Medical SciencesTehranIran

Mitigating low-frequency noise poses a significant challenge for acoustic engineers,due to their long wavelength,with conventional porous sound absorbers showing limitations in attenuating such *** effective strategy involves combining porous materials with micro-perforated plates(MPP)to address this *** the significant impact of structural variables like panel thickness,hole diameter,and air gap on the acoustic characteristics of MPP,achieving the optimal condition demands numerous sample *** impedance tube’s considerable expense for sound absorption measurement and the substantial cost involved in fabricating each sample using a 3D printer underscore the advantage of utilizing simulation methods to attain the optimal *** study focuses on optimizing low-frequency enhancement by investigating key *** the Finite Element Numerical Method(FEM)in COMSOL software,a composite panel was constructed comprising date palm fiber layers,an intervening air layer,and *** study explored the arrangement of these layers and the impact of parameters like hole diameter,plate thickness,and perforation ratio on acoustic *** selected optimal parameter at each stage was consistently maintained for subsequent *** revealed that layer arrangement significantly influenced acoustic *** the MPP layer before the porous material yielded superior low-frequency *** low-frequency behavior involved reducing hole diameter and perforation ratio while increasing plate *** the porous material’s thickness relative to the air layer behind the MPP enhanced absorption peak and resonance *** conclusion,halving the porous layer’s thickness while incorporating an air layer and single MPP proved more effective than using a thick porous *** approach not only reduces costs and space requirements but also enhances low-frequency *** study highlights the precision of

关键词： Micro-perforated panel date palm natural fibers low and middle frequency noise finite element method