检索结果-南通市图书馆

Charge structure factors of doped armchair nanotubes in the presence of electron-phonon interaction

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2020年第9期29卷 415-422页

作者： Hamed Rezania farshad Azizi Department of Physics Razi UniversityKermanshahIran

We present the behaviors of both dynamical and static charge susceptibilities of doped armchair nanotubes using the Green function approach in the context of Holstein-model ***,the effects of magnetization and gap parameter on the the plasmon modes of armchair nanotube are investigated via calculating correlation function of charge density *** phase approximation has been implemented to find the interacting dynamical charge *** electrons in this systems interacts with each other by mediation of dispersionless Holstein *** results show that the increase of gap parameter leads to decreasing intensity of charge collective *** the frequency position of the collective mode tends to higher frequencies due to the gap *** the number of collective excitation mode decreases with chemical potential in the presence of electron-phonon *** the temperature dependence of static charge structure factor of armchair nanotubes is *** effects of the gap parameter,magnetization and electron-phonon interaction on the static structure factor are addressed in details.

关键词： armchair nanotube Green's function

Effect of methane content and the oscillating electric field between electrodes on atmospheric Ar/methane plasma jet and DLC coating deposition

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2020年第8期22卷 76-89页

作者： Reza SAFARI farshad SOHBATZADEH Department of Atomic and Molecular Physics Faculty of Basic SciencesUniversity of MazandaranBabolsar 47416Iran

In this work,the effects of the methane gas flow and the internal oscillating electric field between electrodes on radio-frequency(RF)atmospheric pressure argon/methane plasma jet and process of diamond-like carbon(DLC)film deposition have been *** of RF atmospheric Ar/methane plasma jet such as active species density,length,electron temperature,appearance and ionization process of argon/methane plasma jet are changed due to the changing of methane flow content and electric field vector and its *** increasing methane flow,the formation of C2 hydrocarbon and CH band content is decreased because injected electrical energy to a mixture of Ar/methane gases is insufficient to stabilize the ionization process of methane gas and the electrical-chemical reaction rate is *** shortening the gas gap between two electrodes,electric field strength and its gradient are increased leading to more energy injection to the ***-chemical reactions are strengthened leading to increasing the CH band *** phenomena introduce the Ar/methane plasma jet in different modes causing to deposit the DLC film with different structures and *** using quartz glass and alumina ceramic as dielectric barriers tubes,RF atmospheric pressure Ar/methane plasma jet has been used to deposit DLC coating in different *** methane content and shortening the gas gap leads to decreasing sp3 bonded content and the quality of the deposited film.

关键词： RF atmospheric plasma methane flow electric field

Core designing of a new type of TVS-2M FAs:neutronics and thermal-hydraulics design basis limits

在线全文

学校读者我要写书评

暂无评论

Frontiers in Energy 2021年第1期15卷 256-278页

作者： Saeed GHAEMI farshad FAGHIHI Department of Nuclear Engineering School of Mechanical EngineeringShiraz UniversityShiraz 71936-16548Iran Radiation Research Center Shiraz UniversityShiraz 71936Iran Lonizing and Non-Ionizing Radiation Center Shiraz University of Medical ScienceShirazIran

One of the most important aims of this study is to improve the core of the current VVER reactors to achieve more burn-up(or more cycle length)and more intrinsic *** is an independent study on the Russian new proposed FAs,called TVS-2M,which would be applied for the future advanced *** important aspects of neutronics as well as thermal hydraulics investigations(and analysis)of the new type of Fas are conducted,and results are compared with the standards PWR *** TVS-2M FA contains gadolinium-oxide which is mixed with UO_(2)(for different Gd densities and U-235 enrichments which are given herein),but the core does not contain *** new type TVS-2M Fas are modeled by the SARCS software package to find the PMAXS format for three states of CZP and HZP as well as HFP,and then the whole core is simulated by the PARCS code to investigate transient *** addition,the WIMS-D5 code is suggested for steady core modeling including TVS-2M FAs and/or TVS *** neutronics aspects such as the first cycle length(first cycle burn up in terms of MWthd/kgU),the critical concentration of boric acid at the BOC as well as the cycle length,the axial,and radial power peaking factors,differential and integral worthy of the most reactive CPS-CRs,reactivity coefficients of the fuel,moderator,boric acid,and the under-moderation estimation of the core are conducted and benchmarked with the PWR ***,the burn-up calculations indicate that the 45.6 d increase of the first cycle length(which corresponds to 1.18 MWthd/kgU increase of burnup)is the best improving aim of the new FA type called ***,thermal-hydraulics core design criteria such as MDNBR(based on W3 correlation)and the maximum of fuel and clad temperatures(radially and axially),are investigated,and discussed based on the CDBL.

关键词： TVS-2M FAs core design basis limits VVER-1000 analysis mixture of uranium-gadolinium oxides fuels thermal-hydraulics PARCS WIMS-D5

Economic analysis on log damage during logging operation in Caspian Forests

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2013年第3期24卷 585-589页

作者： farshad Keivan Behjou Faculty of Agriculture University of Mohaghegh ArdabiliArdabil Iran P.O.Box:56199-11367

Waste wood was studied in an economic enterprise by logging, function, tree species and log size in four Caspian hardwood sites. Dam- aged logs were recorded with additional information obtained for the location, dimensions and type of damage. The data were analyzed statis- tically to determine significant differences of damage during logging process. The results indicated that animal harvesting systems cause more volume （40.5% of log volume） and value loss （89.5 $.m^-3） to logs than mechanized harvesting systems （13.9% and 6.0 $.m^-3）, also bucking resulted in significantly more volume （9.9% of log volume） and value loss （5.5 $.m-3） when compared to skidding （0.2% of log volume and 0.2 $.m^-3）, decking （0.4% of log volume and 0.2 $.m^-3） and loading （0.2% of log＇s volume and 0.3 $.m^-3） operations. Study showed that the processes of skidding, decking and loading of logs have very little impact on dam- age levels. Volume and value losses of damaged logs are not sensitive to tree species and log size. The information from the field study is impor- tant in creating new guidelines or training to help minimize hardwood log damage during the timber harvesting process.

关键词： log damage forest operations Caspian hardwood forests

Evaluation of soil erodibility factor(k)for loess derived landforms of Kechik watershed in Golestan Province,North of Iran

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2016年第11期13卷 2028-2035页

作者： farshad KIANI Aboutaleb GHEZELSEFLO Dept.of Soil Science Gorgan university of agricultural sciences and natural resourcesGorgan ***Iran Natural resources organization of Golestan province Gorgan ***Iran

The technique proposed by Wischmeier ＆ Smith for estimating the soil erodibility factor is among the most important methods in this regard. Given the high amounts of silt and lime content in loess soils of eastern parts of Golestan province in Iran, this study aims to evaluate the ability of Wischmeier ＆ Smith index to estimate the soil erodibility of this region. Soil erodibility was first obtained by Wischmeier nomograph and then was compared with the actual values obtained by selecting six plots and then performing physical and chemical tests on these samples. Using the nomograph, Wischmeier index was calculated to be about 0.05-0.092 Mg h MJ？1 mm？1. The results showed that Wischmeier index was 182, 4.11, 6 and 0.35 times than actual value in field with half-hour rainfall, Fournier index, SWAT value with half-hour rainfall and SWAT value with Fournier index, respectively. Obtained results showed that erodibility estimated by Wischmeier ＆ Smith index was higher than the actual measured value. Poor performance of this index in loess soils indicates the need for further research in this field.

关键词： Soil erodibility Loess Wischmeier nomograph Iran

Optimally Connected Hybrid Complex Networks with Windmill Graphs Backbone

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2020年第4期33卷 903-929页

作者： SAFAEI farshad BABAEI Amin MOUDI Mehrnaz Faculty of Computer Science and Engineering Shahid Beheshti UniversityTehranIran School of Computer Science Institute for Research in Fundamental SciencesTehranIran Department of Computer Engineering University of Torbat HeydariehTorbat HeydariehIran

The significance of the existing analysis methods in complex networks and easy access to the ever-increasing volume of information present the emergence of proposing new methods in various fields based on complex system ideas. However, these systems are usually faced with various random failures and intelligent attacks. Due to the nature of the components’ behaviors, the occurrence of the failures and faults in their operations and the alteration of their topologies are the most important problems. Since the complex systems are usually used as the infrastructures of other networks, their robustness against failures and the adoption of suitable precautions are necessary. Moreover, the smallworld effect in most complex systems is one of the crucial structural features. The authors found that the relation between these two is not well-known and may even be in conflict in some networks. The main goal in this paper is to achieve an optimal topology by utilizing a robustness-oriented multiobjective trade-off optimization model(edge rewiring) to establish a peaceful relationship between the two requirements. By offering a proposed rewiring method with the small-world effect, which is called core-periphery Windmill property, the authors demonstrated that the generated networks are able to exhibit appropriate robustness even during intelligent attacks. The results obtained in terms of Windmill graphs are presented very good approximations to demonstrate the small-world effect. These graphs are used as the initial core in the construction of the optimized networks’ topologies.

关键词： effect. utilizing Optimal

Processing of AM60 magnesium alloy by hydrostatic cyclic expansion extrusion at elevated temperature as a new severe plastic deformation method

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2020年第5期27卷 669-677页

作者： farshad Samadpour Ghader Faraji Armin Siahsarani School of Mechanical Engineering College of EngineeringUniversity of TehranTehran11155-4563Iran

Hydrostatic cyclic expansion extrusion(HCEE) process at elevated temperatures is proposed as a method for processing less deformable materials such as magnesium and for producing long ultrafine-grained rods. In the HCEE process at elevated temperatures, high-pressure molten linear low-density polyethylene(LLDPE) was used as a fluid to eliminate frictional forces. To study the capability of the process,AM60 magnesium rods were processed and the properties were investigated. The mechanical properties were found to improve significantly after the HCEE process. The yield and ultimate strengths increased from initial values of 138 and 221 MPa to 212 and 317 MPa, ***, the elongation was enhanced due to the refined grains and the existence of high hydrostatic pressure. Furthermore, the microhardness was increased from HV 55.0 to HV 72.5. The microstructural analysis revealed that ultrafine-grained structure could be produced by the HCEE process. Moreover, the size of the particles decreased, and these particles thoroughly scattered between the grains. Finite element analysis showed that the HCEE was independent of the length of the sample, which makes the process suitable for industrial applications.

关键词： high-pressure fluid elevated temperature severe plastic deformation hydrostatic cyclic expansion extrusion mechanical properties magnesium alloy

Investigation of ex-vessel core catcher for SBO accident in VVER-1000/V528 containment using MELCOR code

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2021年第4期32卷 92-111页

作者： Farhad Salari Ataollah Rabiee farshad Faghihi Department of Nuclear Engineering School of Mechanical EngineeringShiraz UniversityShiraz 71936-16548Iran Radiation Research Center Shiraz UniversityShirazIran Ionizing and Non-Ionizing Research Center Shiraz University of Medical ScienceShirazIran

To mitigate consequences of core melting,an ex-vessel core catcher is investigated in this *** should be obeyed to cool down the corium caused by core *** corium destroys the reactor containment and causes radioactive materials to be released into the environment if it does not cool down *** is important to build a core catcher system for the reception,localization,and cool down of the molten corium during a severe accident resulting from core *** this study,the role of a core catcher in the VVER-1000/v528 reactor containment during a station black out(SBO)accident is evaluated using the MELCOR1.8.6 *** addition,parametric analyses of the SBO for(i)SBO accidents with emergency core cooling system(ECCS)operation,and(ii)without ECCS operation are ***,thermal–hydraulic analyses in dry and wet cavities with/without water are *** investigations include the reduction of gases resulting from molten–corium–concrete interactions(H_(2),CO,CO_(2)).Core melting,gas production,and the pressure/temperature in the reactor containment are ***,a full investigation pertaining to gas release(H_(2),CO,CO_(2))and the pressure/temperature of the core catcher is *** on MELCOR simulations,a core cavity and a perimeter water channel are the best options for corium cooling and a lower radionuclide *** simulation is also theoretically investigated and discussed *** simulation results show that the core catcher system in addition to an internal sacrificial material reduces the containment pressure from 689 to 580 kPa and the corresponding temperature from 394 to 380 ***,it is observed that the amount of gases produced,particularly hydrogen,decreased from 1698 to 1235 ***,the presence of supporting systems,including an ECCS with a core catcher,prolonged the core melting time from 16,430 to 28,630 s(in an SBO accident)and significantly decreased the gases produced.

关键词： Core catcher VVER-1000/V528 Containment SBO accident MELCOR Environmental radionuclide release Corium cooling

Presentation of a multi-index clustering technique for the mathematical programming of block-cave scheduling

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2018年第6期28卷 941-950页

作者： farshad Nezhadshahmohammad Yashar Pourrahimian Hamid Aghababaei Urmia University Urmia ***Iran School of Mining and Petroleum Engineering University of AlbertaEdmonton T6G 1H9Canada Sahand University of Technology Tabriz 5135/1996Iran

Long-term planning is one of the most important stages that determines the distribution of cash flows over the mine life and the feasibility of the project. However, it is not feasible in block caving to generate a production schedule that will provide optimal operating strategies without considering geotechnical constraints. This paper develops a mixed-integer linear programming(MILP) model to optimize the extraction sequence of drawpoints over multiple time horizons of block-cave mines with respect to the draw control systems. A multi-similarity index clustering technique to solve the MILP model in a reasonable time is also presented. Application and comparison of production scheduling based on the draw control system and clustering technique are illustrated using 325 drawpoints over 15 periods. The results show a significant reduction in the size of the MILP model, and in the time required to solve it.

关键词： Production scheduling Block-cave mining Multi-similarity index clustering Draw control system Production rate curve