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Acta Metallurgica Sinica(English Letters) 2016年第1期29卷 39-45页

作者： Mohsen Hajizamani Mostafa Alizadeh seyed Ahmad Jenabali-Jahromi Department of Metals Institute of Science and High Technology and Environmental SciencesGraduate University of Advanced Technology Department of Materials Science and Engineering School of EngineeringShiraz University

A thermomechanical process （TMP） consisting of three cycles of cold pressing at 154 MPa and liquid-phase sintering at 600 ℃ for 30 min in each cycle was applied to modify the microstructure of nanostructured A1-Zn-Mg alloy. The alloy powders were produced by mechanical alloying. Also, solid-state sintering at 550℃ for 90 min was done to compare the results with those obtained from the TMP. The powders and the thermomechanically （TM） processed samples were analyzed by XRD to reveal the present phases in addition to calculating the crystallite size changes by the Wil- liamson-Hall method. Moreover, scanning electron microscope was employed to observe the morphology of the powder and the microstructures of the sintered and the TM processed samples. The results revealed that the TMP affected the microstructure noticeably as well as the microhardness by removing the continuous grain boundary porosities and uniform distribution of the intermetallic phase particles as well as obtaining a near globular microstructure after the second cycle. Also, the average grain sizes in the first and the second cycles of the TMP were lower than those of the sintered sample. Furthermore, nanocrystalline grains were stable up to the second cycle of the TMP.

关键词： Thermomechanical processing AI-Zn-Mg alloy Intermetallics Sintering Grain growth

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

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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

Numerical Simulation of the Mechanical Properties of Sintered and Bonded Perforated Hollow Sphere Structures (PHSS)

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Journal of Materials Science & Technology 2010年第8期26卷 730-736页

作者： Andreas chsner seyed Mohammad Hossein Hosseini Markus Merkel Department of Applied Mechanics Technical University of Malaysia Centre for Mass and Mechanical Transport in Engineering Materials The University of Newcastle CallaghanNewSouth Wales 2308Australia Department of Mechanical Engineering University of Applied Sciences Aalen

This paper investigated the uniaxial mechanical properties of a new type of hollow sphere structures. For this new type, the sphere shell was perforated by several holes in order to open the inner sphere volume and surface. The mechanical properties, i.e. elastic properties and initial yield stress of perforated hollow sphere structures （PHSS） in a primitive cubic arrangement were numerically evaluated for different hole diameters and different joining techniques of the hollow spheres. The results are compared to classical configurations without perforation.

关键词： Mechanical properties Cellular material Porous structure Finite element method

Numerical study of power production from tidal energy in the Khuran Channel and its feedback on background hydrodynamics

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Acta Oceanologica Sinica 2022年第5期41卷 173-182页

作者： Davood Shariatmadari seyed Mostafa Siadatmousavi Cyrus Ershadi Civil Engineering Department Faculty of Technology and EngineeringUniversity of HormozganHormozganBandar Abbas***Iran School of Civil Engineering Iran University of Science and TechnologyTehran***Iran

This study focuses on the development of a farm of tidal turbines in the Khuran *** important factors include the location of turbines and their hydrodynamic effects on the environment.A three-dimensional circulation model for the Persian Gulf is employed for the comprehensive evaluation of the tidal energy potential throughout the study *** model is validated by using in situ observations of water level and current *** appropriate potential points for extracting the tidal energy were identified in the Persian Gulf using the model *** Khuran Channel,located in the north of Qeshm Island,was found to be the best place to extract tidal energy inside the Persian *** adding the term of momentum losses to the governing equations,the feedback of extracting energy on the hydrodynamic around Qeshm Island was *** simulation results show that the average daily power production of a tidal farm with 99 turbines for one month is approximately 1.3 *** tidal farm also has a significant impact on the water level inside the Khuran Channel,especially near the tidal farm where these fluctuations exceed 4 *** change in the current speed caused by wake reaches 0.4 m/*** effects were active up to 7 km downstream of the *** current velocity was also estimated to be 1.6 m/s and 2.1 m/s during the spring and ebb tides within the channel,respectively.

关键词： renewable energy tidal energy Khuran Channel tidal horizontal axis turbine turbine farm Delft3D

Effects of temperature and input energy on a quasi-three-level emission cross section of Nd^(3+):YAG pumped by a flashlamp

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Chinese Physics B 2012年第9期21卷 328-331页

作者： seyed Ebrahim Pourmand Noriah Bidin Hazri Bakhtiar Advanced Photonic Science Institute Faculty of Science University Teknologi Malaysia

The influence of temperature and input energy on the fluorescence emission cross section of Nd3＋：YAG crystal is studied. The stimulated emission cross sections of quasi-three-level systems are determined in a temperature range from -30 to 60 ℃ and an input energy range from 18 to 75 J. The cross section is found to be decreased when the temperature and the input energy are increased. This is attributed to the thermal broadening mechanism of the emission line. This study is relevant for the development of laser design.

关键词： emission cross section Nd:YAG laser flashlamp fluorescence

APG: A novel python-based ArcGIS toolbox to generate absence-datasets for geospatial studies

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Geoscience Frontiers 2021年第6期12卷 90-104页

作者： seyed Amir Naghibi Hossein Hashemi Biswajeet Pradhan Department of Water Resources Engineering&Center for Advanced Middle Eastern Studies Lund UniversityLundSweden Centre for Advanced Modelling and Geospatial Information Systems(CAMGIS) Faculty of Engineering and Information TechnologyUniversity of Technology SydneyNew South WalesAustralia Department of Energy and Mineral Resources Engineering Sejong UniversityChoongmu-gwan209 Neungdong-ro Gwangjin-guSeoul 05006Republic of Korea Department of Meteorology King Abdulaziz UniversityP.O.Box 80234Jeddah 21589Saudi Arabia Earth Observation Centre Institute of Climate ChangeUniversiti Kebangsaan MalaysiaBangiSelangorMalaysia

One important step in binary modeling of environmental problems is the generation of absence-datasets that are traditionally generated by random sampling and can undermine the quality of *** solve this problem,this study develops the Absence Point Generation(APG)toolbox which is a Python-based ArcGIS toolbox for automated construction of absence-datasets for geospatial *** APG employs a frequency ratio analysis of four commonly used and important driving factors such as altitude,slope degree,topographic wetness index,and distance from rivers,and considers the presence locations buffer and density layers to define the low potential or susceptibility zones where absence-datasets are *** test the APG toolbox,we applied two benchmark algorithms of random forest(RF)and boosted regression trees(BRT)in a case study to investigate groundwater potential using three absence datasets i.e.,the APG,random,and selection of absence samples(SAS)*** BRT-APG and RF-APG had the area under receiver operating curve(AUC)values of 0.947 and 0.942,while BRT and RF had weaker performances with the SAS and Random *** effect resulted in AUC improvements for BRT and RF by 7.2,and 9.7%from the Random dataset,and AUC improvements for BRT and RF by 6.1,and 5.4%from the SAS dataset,*** APG also impacted the importance of the input factors and the pattern of the groundwater potential maps,which proves the importance of absence points in environmental binary *** proposed APG toolbox could be easily applied in other environmental hazards such as landslides,floods,and gully erosion,and land subsidence.

关键词： Absence-dataset Classification Python Machine learning algorithms GIS Groundwater Hydrogeology

Optimization of passive control performance for different hard disk drives subjected to shock excitation

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Journal of Central South University 2017年第4期24卷 891-899页

作者： seyed Rashid Alavi Mehdi Rahmati Saeed Ziaei-Rad Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156-83111 Iran Isfahan Mathematics House Isfahan 81698-51177 Iran

Laptop personal computers(LPCs) and their components are vulnerable devices in harsh mechanical environments. One of the most sensitive components of LPCs is hard disk drive(HDD) which needs to be protected against damages attributable to shock and vibration in order to have better magnetic read/write performance. In the present work, a LPC and its HDD are modeled as two degrees of freedom system and the nonlinear optimization method is employed to perform a passive control through minimizing peak of HDD absolute acceleration caused by a base shock excitation. The presented shock excitation is considered as half-sine pulse of acceleration. In addition, eleven inequality constraints are defined based on geometrical limitations and allowable intervals of lumped modal parameters. The target of the optimization is to reach optimum modal parameters of rubber mounts and rubber feet as design variables and subsequently propose new characteristics of rubber mounts and rubber feet to be manufactured for the HDD protection against shock excitation. The genetic algorithm and the modified constrained steepest descent algorithm are employed in order to solve the nonlinear optimization problem for three widely-used commercial cases of HDD. Finally, the results of both optimization methods are compared to make sure about their accuracy.

关键词： hard disk drive passive control shock excitation sequential quadratic programming genetic algorithm rubber

Assessment of seismic amplification factor of excavation with support system

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Earthquake Engineering and Engineering Vibration 2019年第3期18卷 555-566页

作者： Hamidreza Tavakoli Saman Soleimani Kutanaei seyed Hossein Hosseini Department of Civil Engineering Babol University of Technology P.O. Box 484 Babol Iran Department of Civil Engineering Rouzbahan Institute of Higher Education Sari Iran Department of Civil Engineering Hamedan Branch Islamic Azad University P.O. Box 65181-15743 Hamedan Iran

Retaining walls have been used in many construction projects such as for road and inclined surfaces protection. The damage caused by an earthquake depends on the fundamental frequency, amplitude and the duration of the seismic motion. These parameters strongly depend on the seismic properties of the layers that are near the surface. In the study of retaining walls, in addition to the infl uence of soil, the infl uence of topography is also important. In the present study, site response analysis is performed by using fi nite element software PLAXIS to obtain the eff ect of various factors such as embedded length of the sheet pile, underground water table, length and angle of the nail, shear wave velocity of soil on site eff ect and dynamic response. Moreover, for better understanding of the eff ect of the above parameters, the stability analysis was performed by using shear reduction method. The results show that an increase in the embedded length of the sheet pile and the length of nailing causes an increase in the amplifi cation factor. Moreover, for shear-wave velocity in the range of 200- 600 m/s, the amplifi cation factor increases with increase of the shear-wave velocity due to the decrease of nonlinear behavior.

关键词： amplifi cation factor safety factor shear wave velocity nailing sheet pile

Using Syntactic-Based Kernels for Classifying Temporal Relations

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Journal of Computer Science & Technology 2011年第1期26卷 68-80页

作者： seyed Abolghasem Mirroshandel Gholamreza Ghassem-Sani Mahdy Khayyamian Department of Computer Engineering Sharif University of Technology

Temporal relation classification is one of contemporary demanding tasks of natural language processing. This task can be used in various applications such as question answering, summarization, and language specific information retrieval. In this paper, we propose an improved algorithm for classifying temporal relations, between events or between events and time, using support vector machines （SVM）. Along with gold-standard corpus features, the proposed method aims at exploiting some useful automatically generated syntactic features to improve the accuracy of classification. Accordingly, a number of novel kernel functions are introduced and evaluated. Our evaluations clearly demonstrate that adding syntactic features results in a considerable improvement over the state-of-the-art method of classifying temporal relations.

关键词： temporal relation classification information retrieval text mining support vector machines kernel function

A generalized set of correlations for plus fraction characterization

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Petroleum Science 2012年第3期9卷 370-378页

作者： JAMIALAHMADI Mohamad ZANGENEH Hossein HOSSEINI seyed Sajad Petroleum Engineering Department Petroleum University of Technology Chemical & Petroleum Engineering Department Sharif University of Technology

The importance of accurate determination of the critical properties of plus fractions in prediction of phase behaviour of hydrocarbon mixtures by equations of state is well known in the petroleum industry. It has been stated in various papers （Elsharkawy, 2001） that using the plus fraction as a single group in equation of state calculations reduces the accuracy of the results. However in this work it has been shown that using the proper values of critical temperature and pressure for the plus fraction group can estimate the properties of hydrocarbon mixtures, and they are accurate enough to be used in reservoir engineering and enhanced oil recovery calculations. In this paper, a new method is proposed for calculating the critical properties of plus fractions of petroleum fluids. One can use this method either in predicting critical pressure and temperature of single carbon numbers （SCNs） after the splitting process or in predicting critical pressure and temperature of the plus fraction as a single group. A comparison study is performed against Riazi-Daubert correlation （Riazi and Daubert, 1987） and Sancet correlations （Sancet, 2007） for 25 oil samples taken from 14 fields from southwest Iran. The results indicate the superiority of the proposed method to the Riazi-Daubert and Sancet correlations.

关键词： Plus fraction critical properties correlation single carbon number bubble point calculations