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Semi-hot Stamping as an Improved Process of Hot Stamping

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Journal of Materials Science & technology 2011年第4期27卷 369-376页

作者： Malek Naderi Mostafa Ketabchi Mahmoud abbasi Wolfgang Bleck Department of Mining and Metallurgy Amirkabir University of Technology Department of Ferrous Metallurgy RWTH-Aachen University

Reducing the forming load, deletion of springback, increasing the formability of sheets as well as producing high strength parts are the main reasons to apply hot stamping process. Hot stamping process and 22MnB5 steels are the state of the art process and grades, respectively; however novel processes and steel grades are under considerations. In the current research, behavior of the steel grade MSW1200 blanks under semi and fully hot stamping processes was characterized. During semi-hot stamping process, the blank was firstly heated to a temperature of about 650℃ and then formed and quenched in the die assembly, simultaneously. Microstructure and mechanical properties of semi and fully hot stamped blanks were studied and the results were compared with those of normally water/air quenched blanks. The hot stamped blanks attained the strength values as high as water quenched blanks. The highest ductility and consequently, the best formability were achieved for the blank which had been semi-hot stamped. It was concluded that for the mentioned steel, semi-hot stamping process could be considered as an improved thermo-mechanical process which not only guaranteed a high formability, but also led to ultra high strength values.

关键词： Semi-hot stamping Hot stamping MSW1200 steel Mechanical properties

Finite element model updating for structural damage detection using transmissibility data

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 87-101页

作者： Ahmad Izadi Akbar Esfandiari Department of Maritime Engineering Amirkabir University of TechnologyTehran 15875-4413Iran

This paper presents a new finite element model updating method for estimating structural parameters and detecting structural damage location and severity based on the structural responses(output-only data).The method uses the sensitivity relation of transmissibility data through a least-squares algorithm and appropriate normalization of the extracted *** proposed transmissibility-based sensitivity equation produces a more significant number of equations than the sensitivity equations based on the frequency response function(FRF),which can estimate the structural parameters with higher *** abilities of the proposed method are assessed by using numerical data of a two-story two-bay frame model and a plate structure *** evaluating different damage cases,the number,location,and stiffness reduction of the damaged elements and the severity of the simulated damage have been accurately *** reliability and stability of the presented method against measurement and modeling errors are examined using error-contaminated *** parameter estimation results prove the method’s capabilities as an accurate model updating algorithm.

关键词： damage detection model updating output-only transmissibility sensitivity equation

Recent Advances in Fibrous Materials for Hydroelectricity Generation

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Nano-Micro Letters 2025年第2期17卷 109-133页

作者： Can Ge Duo Xu Xiao Feng Xing Yang Zheheng Song Yuhang Song Jingyu Chen Yingcun Liu Chong Gao Yong Du Zhe Sun Weilin Xu Jian Fang College of Textile and Clothing Engineering Soochow UniversitySuzhou 215123People’s Republic of China National Engineering Laboratory for Modern Silk Soochow UniversitySuzhou 215123People’s Republic of China State Key Laboratory of New Textile Materials and Advanced Processing Technologies Wuhan Textile UniversityWuhan 430200People’s Republic of China Institute of Functional Nano&Soft Materials(FUNSOM) Soochow UniversitySuzhou 215123People’s Republic of China Department of Electrical and Computer Engineering University of MassachusettsAmherstMA 01003USA Department of Materials Imperial College LondonSouth Kensington CampusLondon SW72AZUK College of Textile Science and Engineering Zhejiang Sci-Tech UniversityHangzhou 310018People’s Republic of China School of Materials Science and Engineering Shanghai Institute of Technology100 Haiquan RoadShanghai 201418People’s Republic of China

Depleting fossil energy sources and conventional polluting power generation pose a threat to sustainable *** generation from ubiquitous and spontaneous phase transitions between liquid and gaseous water has been considered a promising strategy for mitigating the energy *** materials with unique flexibility,processability,multifunctionality,and practicability have been widely applied for fibrous materials-based hydroelectricity generation(FHG).In this review,the power generation mechanisms,design principles,and electricity enhancement factors of FHG are first ***,the fabrication strategies and characteristics of varied constructions including 1D fiber,1D yarn,2D fabric,2D membrane,3D fibrous framework,and 3D fibrous gel are ***,the advanced functions of FHG during water harvesting,proton dissociation,ion separation,and charge accumulation processes are analyzed in ***,the potential applications including power supply,energy storage,electrical sensor,and information expression are also ***,some existing challenges are considered and prospects for future development are sincerely proposed.

关键词： Hydroelectricity Fibrous material Streaming potential Ion diffusion

A Combinational Perspective in Stimulating Cooperation in Mobile Ad Hoc Networks

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Journal of Computer Science & technology 2011年第2期26卷 256-268页

作者： Mahshid Rahnamay-Naeini Masoud Sabaei Department of Computer Engineering and Information technology Amirkabir University of Technology Department of Electrical and Computer Engineering University of New Mexico

In wireless ad hoc networks cooperation among nodes cannot always be assumed since nodes with limited resources and different owners are capable of making independent decisions. Cooperation problems in topology control and packet forwarding tasks have been mostly studied separately but these two tasks are not independent. Considering a joint cooperation problem by taking into account dependencies between tasks will result in more reliable and efficient networks. In this paper topology control definition is extended to cover cooperation problem in both packet forwarding and topology control in a single problem. In this definition nodes have to adjust their transmission power and decide on their relay role. This paper models the interactions of nodes as a potential game with two-dimensional utility function. The presented model, named TCFORCE （Topology Control packet FORwarding Cooperation Enforcement）, preserves the network connectivity and reduces the energy consumption by providing cooperative paths between all pairs of nodes in the network.

关键词： game theory non-cooperative packet forwarding topology control wireless ad hoc networks

Evaluation of FEMA-440 for including soil-structure interaction

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Earthquake Engineering and Engineering Vibration 2010年第3期9卷 397-408页

作者： Khoshnoudian F. Behmanesh I. Faculty of Civil Engineering Amirkabir University of Technology Faculty of Civil and Environmental Engineering Tufts University

Replacing the entire soil-structure system with a fixed base oscillator to consider the effect of soil-structure interaction （SSI） is a common analysis method in seismic design. This technique has been included in design procedures such as NEHRP, ASCE, etc. by defining an equivalent fundamental period and damping ratio that can modify the response of the structure. However, recent studies indicate that the effects of SSI should be reconsidered when a structure undergoes a nonlinear displacement demand. In recent documents on Nonlinear Static Procedures （NSPs）, FEMA-440 （2005）, a modified damping ratio of the replacement oscillator was proposed by introducing the ductility of the soil-structure system obtained from pushover analysis. In this paper, the damping defined in FEMA-440 to include the soil-structure interaction effect is evaluated, and the accuracy of the Coefficient Method given in FEMA-440 and the Equivalent Linearization Method is studied. Although the improvements for Nonlinear Static Procedures （NSPs） in FEMA-440 are achieved for a fixed base SDOF structure, the soil effects are not perfectly obtained. Furthermore, the damping definition of a soil-structure system is extended to structures to consider bilinear behavior.

关键词： soil-structure interaction foundation damping inelastic behavior equivalent linearization

Waveform feature monitoring scheme for transformer differential protection

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Journal of Zhejiang university-Science C(Computers and Electronics) 2011年第2期12卷 116-123页

作者： Bahador FANI Mohamad Esmail HAMEDANI GOLSHAN Hosein ASKARIAN ABYANEH Department of Electrical and Computer Engineering Isfahan University of Technology Department of Electrical Engineering Amirkabir University of Technology

We propose a new scheme for transformer differential protection. This scheme uses different characteristics of the differential currents waveforms (DCWs) under internal fault and magnetizing inrush current conditions. The scheme is based on choosing an appropriate feature of the waveform and monitoring it during the post-disturbance instants. For this purpose, the signal feature is quantified by a discrimination function (DF). Discrimination between internal faults and magnetizing inrush currents is carried out by tracking the signs of three decision-making functions (DMFs) computed from the DFs for three phases. We also present a new algorithm related to the general scheme. The algorithm is based on monitoring the second derivative sign of DCW. The results show that all types of internal faults, even those accompanied by the magnetizing inrush, can be correctly identified from the inrush conditions about half a cycle after the occurrence of a disturbance. Another advantage of the proposed method is that the fault detection algorithm does not depend on the selection of thresholds. Furthermore, the proposed algorithm does not require burdensome computations.

关键词： Transformer differential protection Differential current waveform Inrush current Fault current Waveform feature Waveform processing

Condition Monitoring of an Industrial Oil Pump Using a Learning Based Technique

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Sound & Vibration 2020年第4期54卷 257-267页

作者： Amin Ranjbar Amir Abolzafl Suratgar Saeed Shiry Ghidary Jafar Milimonfared Distributed and Intelligent Optimization Research Laboratory Department of Electrical EngineeringAmirkabir University of TechnologyTehran***Iran Department of Computer Engineering Amirkabir University of TechnologyTehran***Iran Department of Electrical Engineering Amirkabir University of TechnologyTehran***Iran

This paper proposes an efficient learning based approach to detect the faults of an industrial oil *** proposed method uses the wavelet transform and genetic algorithm(GA)ensemble for an optimal feature extraction *** features,which are dominated through this method,can remarkably represent the mechanical faults in the damaged *** the aim of condition monitoring,we considered five common types of malfunctions such as casing distortion,cavitation,looseness,misalignment,and unbalanced mass that occur during the machine *** proposed technique can determine optimal wavelet parameters and suitable statistical functions to exploit excellent features via an appropriate distance criterion ***,our optimization algorithm chooses the most appropriate feature submatrix to improve the final accuracy in an iterative *** a case study,the proposed algorithms are applied to experimental data gathered from an industrial heavy-duty oil pump installed in Arak Oil Refinery *** experimental results are very promising.

关键词： Condition monitoring fault assessment industrial pump genetic algorithm wavelet packet decomposition

Genetic algorithm application for matching ordinary black oil PVT data

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Petroleum Science 2012年第2期9卷 199-211页

作者： Mohammad Taghizadeh Sarvestani Behnam Sedaee Sola Fariborz Rashidi Department of Petroleum Engineering Amirkabir University of Technology Tehran Iran Institute of Petroleum Engineering University of Tehran Tehran Iran Department of Chemical Engineering Amirkabir University of Technology Tehran Iran

In the study of reservoirs, it is vital that we have a realistic physical model of the reservoir fluid that accurately describes the hydrocarbon system and its properties. The available equations of state （EOS） to model the fluid phase behavior have some inherent deficiencies that may cause erroneous predictions for real reservoir fluids, so these models should be tuned against experimental data by adjusting some parameters. Since there are many matching parameters, tuning the EOS against experimental data is a tedious and difficult work. In this study, a genetic algorithm as an optimization technique is used to solve this regression problem. This study presents a new method that uses a specially designed genetic algorithm to search for suitable regression parameters to match the EOS against measured data. The proposed method has been tested on three real black oil samples. The results show the surprising performance of the developed genetic algorithm to match the experimental data of the selected fluid samples. The main advantage of the used method is its high speed in finding a solution. Also, finding more than one solution, working automatically, confining the role of experts to the last stage, reducing costs and having the possibility of evaluating the different situations are the other advantages of this method to match ordinary black oil PVT data and makes it an ideal method to implement as an automatic EOS tuning algorithm for black oils.

关键词： Equations of state (EOS) tuning genetic algorithms black oil chromosome regression

A novel control strategy for load converter of DC isolated distribution system under unbalanced loading conditions

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Journal of Zhejiang university-Science A(Applied Physics & Engineering) 2009年第6期10卷 890-899页

作者： R.NOROOZIAN M.ABEDI G.B.GHAREHPETIAN S.H.HOSSEINI Department of Electrical Engineering Amirkabir University of Technology Department of Electrical and Computer Engineering Tabriz University

A novel control strategy for the load converter supplying the unbalanced AC load in a DC isolated distribution system is presented. The control algorithm results in balanced and sinusoidal load voltages under unbalanced AC loading. The unbalanced load is characterized in the d-q-0 rotating coordinate based on symmetrical sequence components. Also, the mathematical model of the load converter in both a-b-c and d-q-0 coordinates is derived by using the average large signal model. Then, two control strategies for the load converter are presented. The first one uses the conventional d-q-0 controller to ensure the voltage and current regulation. The second one is a newly proposed control strategy based on the decomposition of the voltage and current into in-stantaneous positive, negative, and zero sequences. These three sequences are controlled independently in their own reference frames as DC signals. The performance of the load converter using these two control strategies is compared. Simulation results show the validity and capability of the newly proposed control strategy.

关键词： Unbalanced load Power quality Symmetrical components Control strategy