检索结果-南通市图书馆

An improved porous media model for nuclear reactor analysis

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2016年第1期27卷 117-140页

作者： roozbeh Vadi Kamran Sepanloo Schools of Nuclear Safety Research and Radiation Protection Nuclear Science and Technology Research InstituteEnd of North Karegar Ave.P.O.Box:14359-836TehranIran

In this study, two modifications are proposed to mitigate drawbacks of the conventional approach of using the ‘‘Porous Media Model''(PMM) for nuclear reactor analysis. In the conventional approach, whole reactor core simplifies to a single porous medium and also, the resistance coefficients that are essential to using this model are constant values. These conditions impose significant errors and restrict the applications of the model for many cases,including accident analysis. In this article, the procedures for calculating the coefficients are modified by introducing a practical algorithm. Using this algorithm will result in obtaining each coefficient as a function of mass flow ***, the method of applying these coefficients to the reactor core is modified by dividing the core into several porous media instead of one. In this method, each porous medium comprises a single fuel assembly. PMM with these two modifications is termed ‘‘multi-region PMM'' in this study. Then, the multi-region PMM is introduced to a new CFD-based thermo-hydraulic code that is specifically devised for combining with neutronic *** CITVAP code, which solves multi-group diffusion equations, is the selected as the neutronic part for this study. The resulting coupled code is used for simulation of natural circulation in a MTR. A new semi-analytic method,based on steady-state CFD analysis is developed to verify the results of this case. Results demonstrate considerable improvement, compared to the conventional approach.

关键词：多孔介质模型模型分析反应器传统方法应用程序流体力学分析稳态计算 PMM

Catalytic effect of lucunary heteropolyanion containing molybdenum and tungsten atoms on decolorization of direct blue 71

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2011年第12期22卷 1501-1504页

作者： Masoumeh Tabatabaee Maria roozbeh Mandana roozbeh Department of Chemistry Yazd BranchIslamic Azad UniversityYazdIran

In this research,a lucunary Keggin structure,[PMo_2W_9O_（39）]^（7-） was selected as an efficient homogenous catalyst for degradation of an azo dye（direct blue 71） and a simple method was developed for degradation of *** method is based on the oxidation of azo dye in the presence of a lucunary Keggin form of polyoxometalates,K_7[PMo_2W_9O_（39）]？ 19H_2O,as a homogenous catalyst at room *** reaction is monitored spectrophotometrically by measuring the absorbance of dye atλ=585 *** parameters including concentration of catalyst,concentration of H_2O_2,pH and reaction time were investigated and optimized. Results show that K_7[PMo_2W_9O_（39）]？ 19H_2O is more efficient in the presence of hydrogen *** of dye in the presence of the catalyst and H_2O_2 could lead to the disappearance approximately 65%of dye after 60 *** degradation for the same experiment performed in the absence of catalyst or in the absence of H_2O_2 was 22%or 5%*** 87% azo dyes has been eliminated after 90 min in the presence of catalyst,H_2O_2 and optimize conditions（0.6 g/L of K_7[PMo_（2-） W_9O_（39）H_9H_2O,0.08 mol/L hydrogen peroxide and room temperature）.

关键词： Degradation Homogenous catalyst Polyoxometalates Lucunary Keggin structure

Effects of residue management and nitrogen fertilizer rates on accumulation of soil residual nitrate and wheat yield under no-tillage system in south-west of Iran

在线全文

学校读者我要写书评

暂无评论

International Soil and Water Conservation Research 2021年第1期9卷 116-126页

作者： Majid roozbeh Majid Rajaie Agricultural Engineering Research Department Darab Agricultural Research StationFars Agricultural and Natural Resources Research and Education CenterAREEOIran Soil and Water Research Department Darab Agricultural Research StationFars Agricultural and Natural Resources Research and Education CenterAREEOIran

Conservation tillage,residue management and optimizing nitrogen(N)fertilization are important stra-tegies for soil and water conservation and sustainability of agricultural *** order to evaluate the effects of various residue management methods and N fertilizer rates on some soil quality indicators,accumulation of residual soil nitrate,and wheat yield under no till system,a split-plot experiment was arranged in a randomized complete block design with three *** plots were three residue management methods,including retaining(R.M1),removing(R.M2)and shredding(R.M3)of corn *** subplots consisted of four N fertilizer rates,100(N1),150(N2),200(N3),and 250(N4)kg N ha^(-1) from urea *** results showed that soil organic carbon and total N in R.M1 and R.M3 treatments increased at the depth of 0-15 cm as compared to *** maximum accumulation of soil nitrate was observed in R.M1 x N4 and R.M3 x N4 interactions at the soil depth of *** results of this study showed that R.M1 x N3 and R.M3 x N3 interactions had a greater impact on wheat yield than the sole effect of R.M1 or *** to our findings,application of 200 kg N ha^(-1) in combination with R.M1 which had once less tractor passing for mechanical shredding than R.M3,can contribute effectively to improve soil quality indicators,control soil residual nitrate and subsequently produce more wheat grain yield in the south-west of Iran.

关键词： No-tillage Corn residue Total nitrogen Nitrate accumulation Organic carbon

Development of seismic fragility curves for precast concrete frames with cast-in-situ concrete shear-walls

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

Earthquake Engineering and Engineering Vibration 2022年第1期21卷 149-167页

作者： Aliakbar Yahyaabadi roozbeh Talebkhah Mahdi Adibi Faculty of Engineering University of BojnordBojnord 94531-55111Iran

Precast reinforced concrete buildings have been well received in some seismic zones worldwide due to advantages such as the ease and the speed of implementation,and the possibility of working in inappropriate atmospheric *** this research,seismic fragility curves were developed for precast concrete frames with a cast-in-situ concrete shear-wall,concerning the important issues of modeling the precast beam-column joints,construction quality,and soil type *** this purpose,the incremental dynamic analysis(IDA)was conducted for three-dimensional models of 3-,5-,and 8-story buildings under two record sets corresponding to soil types C and D of the NEHRP ***-column joints were modeled using nonlinear rotational springs with rigid links with respect to the finite size of the joint *** demonstrate that the Weibull distribution can be fitted to the damage state capacities better than the lognormal distribution at the intensities that are more than one standard deviation away from the median damage *** seismic vulnerability of precast structures increases at all damage states as the height of the building *** is also observed that soil type has almost no considerable effect on the fragility curve parameters for all damage states considered herein.

关键词： fragility curve incremental dynamic analysis precast beam-column joints construction quality soil type effects

Separation of methane from different gas mixtures using modified silicon carbide nanosheet: Micro and macro scale numerical studies

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2020年第5期28卷 1268-1276页

作者： Golchehreh Bayat roozbeh Saghatchi Jafar Azamat Alireza Khataee Research Laboratory of Advanced Water and Wastewater Treatment Processes Department of Applied ChemistryFaculty of ChemistryUniversity of TabrizTabriz 51666-16471Iran Integrated Manufacturing Technologies Research and Application Center Faculty of Engineering and Natural SciencesSabanci UniversityOrhanliTuzlaIstanbul 34956Turkey Department of Basic Sciences Farhangian UniversityTehranIran Department of Environmental Engineering Gebze Technical UniversityGebze 41400Turkey Institute of Research and Development Duy Tan UniversityDa Nang 550000Viet Nam

This research discusses the separation of methane gas from three different gas mixtures,CH4/H2 S,CH4/N2 and CH4/CO2,using a modified silicon carbide nanosheet(Si CNS)membrane using both molecular dynamics(MD)and computational fluid dynamics(CFD)*** research examines the effects of different structures of the Si CNSs on the separation of these gas *** parameters including the potential of the mean force,separation factor,permeation rate,selectivity and diffusivity are discussed in *** MD simulations showed that the separation of CH4/H2 S,and CH4/CO2 mixtures was successful,while simulation demonstrated a poor result for the CH4/N2 *** effect of temperature on the diffusivity of gas is also discussed,and a correlation is introduced for diffusivity as a function of *** evaluated value for diffusivity is then used in the CFD method to investigate the permeation rate of gas mixtures.

关键词： Gas separation Silicon carbide nanosheets Molecular dynamics Computational fluid dynamics

A review of fluid displacement mechanisms in surfactant-based chemical enhanced oil recovery processes:Analyses of key influencing factors

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2022年第3期19卷 1211-1235页

作者： Ahmed Bashir Amin Sharifi Haddad roozbeh Rafati School of Engineering Kings CollegeUniversity of AberdeenAB243UEUK

Surfactant-based oil recovery processes are employed to lower the interfacial tension in immiscible displacement processes,change the wettability of rock to a more water-wet system and emulsify the oil to displace it in subsurface porous ***,these phenomena can reduce the capillary pressure and enhance spontaneous *** key factors affecting such immiscible displacement process are temperature,salinity and p H of the fluids,surfactant concentration and ***,before any surfactant flooding process is applied,extensive studies of fluid-fluid and rock-fluid interactions are *** use of other chemicals along with surfactants in chemical enhanced oil recovery(c EOR)processes have been widely considered to exploit the synergy of individual chemicals and complement the weakness arises from each of them during immiscible displacement of fluids in porous ***,such combinations of chemicals lead to alkaline-surfactant(AS),surfactantpolymer(SP),alkaline-surfactant-polymer(ASP),and nanoparticle-surfactant(NS)flooding processes,among *** this review study,we categorised the role and displacement mechanisms of surfactants and discussed the key factors to be considered for analysing the fluid displacement in porous media.

关键词： Alkaline surfactant(AS)flooding Alkaline-surfactant-polymer(ASP)flooding Enhanced oil recovery(EOR) Interfacial tension(IFT) Nanoparticle-surfactant(NS)flooding Surfactant adsorption Surfactant-polymer(SP)flooding Wettability alteration

Dynamic output feedback stabilization of deterministic finite automata via the semi-tensor product of matrices approach

在线全文

学校读者我要写书评

暂无评论

Control Theory and Technology 2021年第2期19卷 170-182页

作者： roozbeh Abolpour Mohsen Raji Parisa Moradi School of Electrical and Computer Engineering Shiraz UniversityShirazIran

This paper deals with the dynamic output feedback stabilization problem of deterministic finite automata(DFA).The static form of this problem is defined and solved in previous studies via a set of equivalent *** this paper,the dynamic output feedback(DOF)stabilization of DFAs is defined in which the controller is supposed to be another *** DFA controller will be designed to stabilize the equilibrium point of the main DFA through a set of proposed equivalent *** has been proven that the design problem of DOF stabilization is more feasible than the static output feedback(SOF)*** simulation examples are provided to illustrate the results of this paper in more *** first example considers an instance DFA and develops SOF and DOF controllers for *** example explains the concepts of the DOF controller and how it will be implemented in the closed-loop *** the second example,a special DFA is provided in which the DOF stabilization is feasible,whereas the SOF stabilization is *** final example compares the feasibility performance of the SOF and DOF stabilizations through applying them to one hundred random-generated *** results reveal the superiority of the DOF stabilization.

关键词： Discrete event dynamic system Finite automata Dynamic output feedback stabilization Semi-tensor product

Low-temperature Magnesiothermic Synthesis of Mesoporous Silicon Carbide from an MCM-48/Polyacrylamide Nanocomposite Precursor

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

Journal of Materials Science & Technology 2013年第3期29卷 255-260页

作者： Zahra Saeedifar Amir Abbas Nourbakhsh roozbeh Javad Kalbasi Ebrahim Karamian Department of Materials Engineering Najafabad BranchIslamic Azad UniversityP.O.Box 517IsfahanIran Department of Materials Engineering Shahreza BranchIslamic Azad UniversityIsfahanIran

Mesoporous silicon carbide with high specific surface area was successfully synthesized from an MCM-48/ polyacrylamide nanocomposite precursor in the temperature range of 550-600 ℃ （below the melting point of Mg） by means of a magnesiothermic reduction process. The MCM-48/polyacrylamide precursor nanocomposite was prepared by in-situ polymerization of acrylamide monomer in the presence of mesoporous MCM-48 synthesized by sol-gel method. The physicochemical properties and microstructures of the nanocomposite precursor and the low-temperature SiC product were characterized by X-ray diffraction （XRD）, differential scanning calorimetry-thermo gravimetric analysis （DSC-TGA）, transmission electron microscopy （TEM） and N2 adsorption-desorption. TEM micrographs and Brunauer-Emmett-Teller （BET） gas adsorption studies showed that the SiC powder was nanocrystalline and had a specific surface area of 330 m2/g and a mesoporosity in the range of 2-10 nm. The presence of an exothermic peak in the DSC trace corresponds to the self-combustion process of the SiC magnesiothermic synthesis. The results also show that the carbon in excess to that required to produce SiC plays a role in the reduction of the SiO2. The mechanism of magnesiothermic synthesis of mesoporous SiC is discussed.

关键词： Silicon carbide Nanocomposite Mesoporous Magnesiothermic reduction In-situ polymerization

Clandestine nanoelectromechanical tags for identification and authentication

在线全文

学校读者我要写书评

暂无评论

Microsystems & Nanoengineering 2020年第1期6卷 87-94页

作者： Sushant Rassay Mehrdad Ramezani Sumaiya Shomaji Swarup Bhunia roozbeh Tabrizian Electrical and Computer Engineering Department University of FloridaGainesvilleFL 32611USA

The realization of truly unclonable identification and authentication tags is the key factor in protecting the global economy from an ever-increasing number of counterfeit ***,we report on the demonstration of nanoscale tags that exploit the electromechanical spectral signature as a fingerprint that is characterized by inherent randomness in fabrication *** from their ultraminiaturized size and transparent constituents,these clandestine nanoelectromechanical tags provide substantial immunity to physical tampering and *** algorithms are developed for digital translation of the spectral signature into binary fingerprints.A large set of tags fabricated in the same batch is used to estimate the entropy of the corresponding fingerprints with high *** tags are also examined under repetitive measurements and temperature variations to verify the consistency of the *** experiments highlight the potential of clandestine nanoelectromechanical tags for the realization of secure identification and authentication methodologies applicable to a wide range of products and consumer goods.

关键词： realization signature transparent