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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

An evaluation of central Iran’s protected areas under different climate change scenarios (A Case on Markazi and Hamedan provinces)

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Journal of Mountain science 2020年第1期17卷 68-82页

作者： Peyman KARAMI sahar REZAEI shabnam sHADLOO Morteza naderi Department of Environmental sciences Faculty of Natural Resources and Environment SciencesMalay er UniversityMalayer65719-95863HamedanIran Department of Environmental sciences Faculty of Natural Resources and Environment SciencesUniversity of GuilanSowmehsara419961-3778GuilanIran Department of Environmental sciences Faculty of Agriculture and Natural SciencesArak UniversityArak 38156-8-8349Iran

Global climate change poses a new challenge for species and can even push some species toward an extinction vortex. The most affected organisms are those with narrow tolerance to the climatic factors but many large mammals such as ungulates with a wider ecological niche are also being affected indirectly. Our research mainly used wild sheep in central Iran as a model species to explore how the suitable habitats will change under different climatic scenarios and to determine if current borders of protected areas will adequately protect habitat requirements. To create habitat models we used animal-vehicle collision points as an input for species presence data. We ran habitat models using Max Ent modeling approach under different climatic scenarios of the past, present and future(under the climatic scenarios for minimum(RCP2.6) and maximum(RCP8.5) CO2 concentration trajectories). We tried to estimate the overlap and the width of the ecological niche using relevant metrics. In order to analyze the effectiveness of the protected areas, suitable maps were concerted to binary maps using True skill statistic(Tss) threshold and measured the similarity of the binary maps for each scenario using Kappa index. In order to assess the competence of the present protected areas boundary in covering the distribution of species, two different scenarios were employed, which are ensemble scenario 1: an ensemble of the binary maps of the species distribution in Mid-Holocene, present, and RCP2.6;and ensemble scenario 2: an ensemble of binary suitability maps in Mid-Holocene, present, and RCP8.5. Then, the borders of modeled habitats with the boundaries of 23 existing protected areas in two central provinces in Iran were compared. The predicted species distribution under scenario 1(RCP2.6) was mostly similar to its current distribution(Kappa = 0.53) while the output model under scenario 2(RCP8.5) indicated a decline in the species distribution range. Under the first ensemble scenario, curr

关键词： Climatic scenarios species Distribution Modeling Protected area Niche modeling Wild sheep

Kinetic studies of the oxidative coupling of methane over the Mn/Na_2WO_4/siO_2 catalyst

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Journal of Natural Gas Chemistry 2009年第1期18卷 25-34页

作者： seyed mehdi Kamali shahri seyed mehdi Alavi Reaction Engineering Lab. Chemical Engineering Department Iran University of Science and Technology Tehran-Iran

Oxidative coupling of methane is a direct way to obtain C2 hydrocarbon, and Mn-Na-W/siO2 catalyst is the most promising among all the catalysts. The 2%Mn/5%Na2WO4/siO2 catalyst was prepared by the incipient wetness impregnation method. A 7-step heterogeneous reaction model of the oxidative coupling of methane to C2 hydrocarbons was conducted by co-feeding methane and oxygen at a total pressure of 1 bar over the catalyst. The kinetic measurements were carried out in a micro-catalytic fixed bed reactor. The kinetic data were obtained at the appropriate range of reaction conditions （4 kPa〈Po2 〈20 kPa, 20 kPa〈PcH4〈80 kPa, 800 ℃〈T〈900℃）. The proposed reaction kinetic scheme consists of three primary and four consecutive reaction steps. The conversions of hydrocarbons and carbon oxides were evaluated by applying Langmuir-Hinshelwood type rate equations. Power-law rate equation was applied only for the water-gas shift reaction. In addition, the effects of operating conditions on the reaction rate were studied. The proposed kinetic model can predict the conversion of methane and oxygen as well as the yield of C2 hydrocarbons and carbon oxides with an average accuracy of ± 15%.

关键词： kinetic model oxidative coupling of methane reaction rate

Cognitive Power Management in Wireless sensor Networks

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Journal of Computer science & Technology 2015年第6期30卷 1306-1317页

作者： seyed mehdi Tabatabaei Vesal Hakami mehdi Dehghan Department of Computer Engineering and Information Technology Amirkabir University of Technology Tehran 16846-13114 Iran

Dynamic power management （DPM） in wireless sensor nodes is a well-known technique for reducing idle energy consumption. DPM controls a node＇s operating mode by dynamically toggling the on/off status of its units based on predictions of event occurrences. However, since each mode change induces some overhead in its own right, guaranteeing DPM＇s eificiency is no mean feat in environments exhibiting non-determinism and uncertainty with unknown statistics. Our solution suite in this paper, collectively referred to as cognitive power management （CPM）, is a principled attempt toward enabling DPM in statistically unknown settings and gives two different analytical guarantees. Our first design is based on learning automata and guarantees better-than-pure-chance DPM in the face of non-stationary event processes. Our second solution caters tor an even more general setting in which event occurrences may take on an adversarial character. In this case, we formulate the interaction of an individual mote with its environment in terms of a repeated zero-sum game in which the node relies on a no-external-regret procedure to learn its mini-max strategies in an online fashion. We conduct numerical experiments to measure the performance of our schemes in terms of network lifetime and event loss percentage.

关键词： wireless sensor network cognitive power management learning automata external regret zero-sum game

Biomass and carbon stocks in three types of Persian oak(Quercus brantii ***)of Zagros forests in a semi-arid area,Iran

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Journal of Arid Land 2020年第5期12卷 766-774页

作者： Ali MAHDAVI soghra sAIDI Yaghob IRANMANEsH Mostafa naderi Faculty of Agriculture and Natural Resources Ilam UniversityIlam 69315516Iran Research Division of Natural Resources Chaharmahal and Bakhtiari Agricultural and Natural Resources Research and Education CenterAREEOShahrekord ***Iran

Persian oak(Quercus brantii ***)is a dominant tree species of Zagros forests in a semi-arid area,western ***,the capacity of biomass and carbon stocks of these forests is not well *** selected three types of oak,i.e.,seed-originated oak,coppice oak and mixed(seed-originated and coppice)oak of Zagros forests in Dalab valley,Ilam Province,Iran to survey the capacity of biomass and carbon stocks in *** plots with an area of 1000 m2 were systematically and randomly assigned to each type of *** characteristics of trees,such as diameter at breast height(DBH),height,crown diameter and the number of sprouts in each plot were ***,aboveground biomass(AGB),belowground biomass(BGB),aboveground carbon stock(AGCs)and belowground carbon stock(BGCs)of each tree in plots were calculated using allometric *** litterfall biomass(LFB)and litterfall carbon stock(LFCs)were measured in a quadrat with 1 m×1 m in each ***-way analysis of variance and Duncan's test were performed to detect the differences in biomass and carbon stocks among three types of *** showed that AGB,BGB and BGCs were significantly different among three types of *** highest values of AGB,AGCs,BGB and BGCs in seed-originated oak were 76,043.25,14,725.55,36,737.79 and 7362.77 kg/hm2,***,the highest values of LFB and LFCs in seed-originated oak were 3298.33 and 1520.48 kg/hm2,respectively,which were significantly higher than those of the other two types of *** results imply the significant role of seed-originated oak for the regeneration of Zagros *** conservation strategy of seed-originated oak is an important step in the sustainable management of Zagros forests in Iran.

关键词： biomass carbon stock seed-originated forest coppice forest Zagros forest

Porosity parameters in biomaterial science: Definition, impact, and challenges in tissue engineering

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Frontiers of Materials science 2021年第3期15卷 352-373页

作者： mehdi EBRAHIMI Biomedical and Tissue Engineering Prince Philip Dental HospitalThe University of Hong KongHong KongChina

Porosity parameters are one of the structural properties of the extracellular microenvironment that have been shown to have a great impact on the cellular phenotype and various biological activities such as diffusion of fluid,initial protein adsorption,permeability,cell penetration and migration,ECM deposition,angiogenesis,and rate and pattern of new tissue *** heterogeneity of the study protocols and research methodologies do not allow reliable meta-analysis for definite *** such,despite the huge available literature,no generally accepted consensus is defined for the porosity requirements of specific tissue engineering ***,based on the biomimetic approach,the biological substitutes should replicate the 3D local microenvironment of the recipient site with matching porosity parameters to best support local cells during tissue ***,the porosity of biomaterials should mimic the porosity of the substituting natural tissue and match the clinical *** analysis of the impact of architectures(i.e.,porosity)on biophysical,biochemical,and biological behaviors will support designing smart biomaterials with customized architectural and functional properties that are patient and defect site-specific.

关键词： porosity pore size pore geometry topography tissue engineering

Lack of Association between rs4331426 Polymorphism in the Chr18q11.2 Locus and Pulmonary Tuberculosis in an Iranian Population

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Biomedical and Environmental sciences 2016年第7期29卷 516-520页

作者： Mohammad naderi Mohammad Hashemi Gholamreza Bahari Infectious Diseases and Tropical Medicine Research Center Zahedan University of Medical Sciences Cellular and Molecular Research Center Zahedan University of Medical Sciences epartment of Clinical Biochemistry School of MedicineZahedan University of Medical Sciences

Objective The effect of rs4331426 polymorphism in the Chr18q11.2 locus on pulmonary tuberculosis（PTB） risk was *** This case-control study included 208 PTB patients and 204 healthy *** of the rs4331426 variant was conducted using polymerase chain reaction restriction fragment length *** The frequencies of genotypes AA,AG,and GG polymorphisms were 83.1%,15.9%,and 1.0% in the PTB group and 84.3%,15.2%,and 0.5% in the control group,*** frequency of the minor（G） allele was 8.9% in the PTB group and 8.1% in *** genotype nor allele frequencies of the rs4331426 variant showed statistically significant differences between PTB and *** addition,stratification by sex showed no significant association between the rs4331426 variant and PTB risk in males or *** In conclusion,the results of this study do not support an association between the rs4331426 polymorphism and risk of PTB in an Iranian population.

关键词： Tuberculosis rs4331426 Polymorphism

Introducing the general condition for an operator in curved space to be unitary

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Chinese Physics B 2021年第8期30卷 220-223页

作者： Jafari Matehkolaee mehdi Faculty of Physics Semnan UniversitySemnan35131-19111Iran

We investigate the general condition for an operator to be *** condition is introduced according to the definition of the position operator in curved *** a particular case,we discuss the concept of translation operator in curved space followed by its relation with an anti-Hermitian *** we introduce a universal formula for adjoint of an arbitrary linear *** procedure in this paper is totally different from others,as we explore a general approach based only on the algebra of the *** approach is only discussed for the translation operators in one-dimensional space and not for general operators.

关键词： operator theory algebraic methods unitary operator translation operator

Measuring nanoparticles in liquid with attogram resolution using a microfabricated glass suspended microchannel resonator

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Microsystems & Nanoengineering 2022年第4期8卷 261-270页

作者： mehdi Mollaie Daryani Tomás Manzaneque Jia Wei Murali Krishna Ghatkesar Department of Precision and Microsystems Engineering Delft University of TechnologyDelftThe Netherlands Department of Microelectronics Delft University of TechnologyDelftThe Netherlands Present address:Department of Microelectronics Delft University of TechnologyDelftThe Netherlands

The use of nanoparticles has been growing in various industrial fields,and concerns about their effects on health and the environment have been ***,characterization techniques for nanoparticles are ***,we present a silicon dioxide microfabricated suspended microchannel resonator(sMR)to measure the mass and concentration of nanoparticles in a liquid as they *** measured the mass detection limits of the device using laser Doppler *** limit reached a minimum of 377 ag that correspond to a 34 nm diameter gold nanoparticle or a 243 nm diameter polystyrene particle,when sampled every 30 *** compared the fundamental limits of the measured data with an ideal noiseless measurement of the ***,we measured the buoyant mass of gold nanoparticles in real-time as they flowed through the sMR.

关键词： resonator suspended nanoparticles