检索结果-南通市图书馆

Numerical simulation of compression corner flows at Mach number 9

Chinese Journal of Aeronautics 2020年第6期33卷 1611-1624页

作者： amjad APASHA Khalid AJUHANY Department of Aerospace Engineering King Abdulaziz UniversityJeddah 21589Saudi Arabia

A hypersonic vehicle encounters a wide range of conditions during its complete flight *** flight conditions may vary from low to high Mach numbers with varying angles of *** near-wall viscous dissipation associated with flows at combined high Mach and Reynolds numbers leads to significant wall heat transfer rates and shear *** shock wave/boundary-layer interaction results in a flow separation region,which commonly augments total pressure losses in the flow and lowers the efficiency of aerodynamic control surfaces such as fins installed on a *** standard turbulence models,when used to resolve such flows,result in incorrect separation bubble size for large separated ***,it results in an inaccurate aerodynamic load,such as the wall pressures,skin friction distribution,and heat transfer *** previous studies,the application of the shock-unsteadiness correction to the standard two-equation k-ωturbulence model improved the separation bubble size leading to an accurate pressure prediction and shock definition with the assumption of constant Prandtl *** the present work,the new shock-unsteadiness modification to the k-ωturbulence model is applied to the hypersonic compression corner *** new model with variable Prandtl number is based on the model parameter,which depends upon the local density *** computed wall pressures,heat flux and flow field are compared to the experimental data.A parametric study is carried out by varying compression deflection angles,free stream Reynolds number and wall temperatures to compute the flow field and wall data accurately,particularly in the shock boundary layer interaction *** new shockunsteadiness modified k-ωmodel with variable Prandtl number shows an accurate prediction of initial pressure rise location,pressure distribution in the plateau region and heat flux in comparison to the standard k-ωmodel.

关键词： Boundary layer Expansion fan Heat transfer Hypersonic flows Separation length Shock-unsteadiness model Shock wave Turbulence model Turbulent Prandtl number

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Solitons and quasi-Grammians of the generalized lattice Heisenberg magnet model

引用

Communications in Theoretical Physics 2023年第8期75卷 42-53页

作者： Zeeshan amjad Bushra Haider Department of Physics University of the PunjabQuaid-e-Azam CampusLahore-54590Pakistan

In this paper,we study the discrete Darboux and standard binary Darboux transformation for the generalized lattice Heisenberg magnet *** calculate the quasi-Grammian solutions by the iteration of standard binary Darboux ***,we derive the explicit matrix solutions for the binary Darboux matrix and then reduce them to the elementary Darboux matrix and plot the dynamics of solutions.

关键词： quasi-Grammian discrete integrable systems binary Darboux transformation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Modeling Date Palm Trunk Fibers (DPTF) Packed Bed Adsorption Performances for Cadmium Removal from Aqueous Wastewater

引用

Fluid Dynamics & Materials Processing 2023年第6期19卷 1535-1549页

作者： Ahmad S.Awad Banan hudaib Waid Omar Mechanical Engineering Department Faculty of Engineering TechnologyAl-Balqa Applied UniversityAmman11134Jordan Chemical Engineering Department Faculty of Engineering TechnologyAl-Balqa Applied UniversityAmman11134Jordan

In this study,the potential of a low-cost bio-adsorbent,taken directly from Date Palm Trunk Fibers(DPTF)agricultural wastes,for cadmium ions removal from wastewaters is *** performances of this adsorbent are evaluated by building breakthrough curves at different bed heights and flow rates while keeping other parameters,such as the initial feed concentration,pH,and particle size,*** results indicate that the maximum cadmium adsorption capacity of DTPF can be obtained from the Thomas model as 51.5 mg/g with the most extended mass transfer zone of 83 min at the lowest flow rate at 5 ml/*** saturation concentrations(NO)and the rate constant(kab)obtained from the BDST(bed depth service time)model are 7022.16 mg/l and 0.0536 l/***,*** the Yon-Nelsen Model,it is found that operating at a lower flow rate leads to a larger value of the elapsed needed time to reach a 50%*** Wolborska model indicates that the bed capacity increases with decreasing the flow rate,and the adsorbent can achieve a greater external mass transfer kinetic coefficient(2.271/min)at a higher flow rate.

关键词： Cadmium ions adsorption fixed bed biodorbent pollutant date palm trunk fibers wastewater treatment breakthrough curves modeling

来源：

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

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

引用

Journal of Environmental Sciences 2007年第4期19卷 396-402页

作者： amjad ALI Khan QAYYUM Husain Department of Biochemistry Faculty of Life Science Aligarh Muslim UniversityAligarh-202 002India.

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.

关键词： decolorization textile dyes polyphenol oxidases potato brinjal wastewater treatment removal of dyes

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Dynamic replication of web contents

引用

Science in China(Series F) 2007年第6期50卷 811-830页

作者： amjad Mahmood Department of Computer Science University of Bahrain Kingdom of Bahrain

The phenomenal growth of the World Wide Web has brought huge increase in the traffic to the popular web sites. Long delays and denial of service experienced by the end-users, especially during the peak hours, continues to be the common problem while accessing popular sites. Replicating some of the objects at multiple sites in a distributed web-server environment is one of the possible solutions to improve the response time/latency. The decision of what and where to replicate requires solving a constraint optimization problem, which is NP-complete in gen- eral. In this paper, we consider the problem of placing copies of objects in a dis- tributed web server system to minimize the cost of serving read and write requests when the web servers have limited storage capacity. We formulate the problem as a 0-1 optimization problem and present a polynomial time greedy algorithm with backtracking to dynamically replicate objects at the appropriate sites to minimize a cost function. To reduce the solution search space, we present necessary condi- tions for a site to have a replica of an object in order to minimize the cost function. We present simulation results for a variety of problems to illustrate the accuracy and efficiency of the proposed algorithms and compare them with those of some well-known algorithms. The simulation results demonstrate the superiority of the proposed algorithms.

关键词： object replication Web distributed web-server system data placement Internet

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Prediction of pressure gradient and hold-up in horizontal liquid-liquid pipe flow

引用

Petroleum Science 2023年第6期20卷 3766-3782页

作者： Syed amjad Ahmed Bibin John School of Mechanical Engineering Vellore Institute of TechnologyIndia Department of Mechanical Engineering C Abdul Hakeem College of Engineering&TechnologyIndia

This paper aims to propose correlations to predict pressure gradient,friction factor and fluid phase hold-up in liquid-liquid horizontal pipe *** develop the correlations,experiments are conducted using high viscous oils(202 and 630 mPa⋅s)in a steel pipe of length 11.25 m and length-to-diameter ratio of *** addition,the experimental data from the literature comprising wide range of flow and fluid properties is *** the analysis,the liquid-liquid pipe flow data is categorized into two as:stratified and *** existing friction factor correlations are modified to incorporate the effects of viscosity of the oil phase,interfacial curvature(contact/wetting angle-in lieu of material of the pipe)and fluid phase *** the two-fluid model of stratified flow,the wall stress and interfacial stress correlations are substituted with superficial velocities of fluids and superficial Reynolds numbers of fluid phases replacing fluid phase velocities and fluid Reynolds ***,for dispersed flow,an effective Reynolds number is described as the sum of superficial Reynolds number of oil and water *** the generally employed mean or mixture Reynolds number with the effective Reynolds number into the existing single-phase turbulent flow friction factor correlation,an effective friction factor for oil-water flow is *** the proposed correlations,the pressure gradient across the oil-water flow and hold-up volume fraction are predicted with significant reduction in error compared with that of conventionally employed *** average error and standard deviation values of−7.06%,20.72%and 0.31%,18.79%are found for stratified flow and dispersed flow respectively.

关键词： oil-water flow two-fluid model pressure gradient stratified flow dispersed flow

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effect of hot rolling on microstructure and properties of the ZEK100 alloy

引用

Journal of Magnesium and Alloys 2019年第1期7卷 27-37页

作者： amjad Javaid Frank Czerwinski CanmetMATERIALS 183 Longwood Road SouthHamiltonOntario L8P 0A5Canada

Attempts to expand manufacturing capabilities of magnesium-based sheet materials are *** as-cast ZEK100(Mg-1.2Zn-0.35Zr-0.17Nd,in wt%)magnesium alloy was subjected to hot rolling at temperatures from 350℃to 450℃using the laboratory 50 ton reversible mill with preheated rolls to manufacture the 1.5-1.7 mm thick *** rolling temperature affected the sheet properties and an increase in the rolling temperature from 250 to 450℃caused reduction of tensile strength from 257 to 228 MPa ac-companied by a reduction in tensile yield stress from 237 to 185 *** the same time,the alloy elongation increased from 17 to 21%.For the same rolling temperature range,the compressive strength reduced from 418 to 351 *** post-rolling annealing at 450℃led to reduction of both tensile and compressive properties with the largest changes corresponding to the rolling temperature of 350°*** correlation between the alloy grain size after rolling and the sheet properties was established where a reduction in grain size was accompanied by an increase of both the tensile/compressive strength and yield *** on Hall-Petch relationship and an average grain size the correlation developed in this study may be used as the prediction model for properties of the hot rolled magnesium *** results are discussed in terms of recent developments in magnesium sheet alloys and the vital role played in this process by rare earth elements.

关键词： Magnesium alloys Hot deformation Microstructure Rare earths Sheet rolling

来源：

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

A note on teleparallel Killing vector fields in Bianchi type Ⅷ and Ⅸ space-times in teleparallel theory of gravitation

引用

Chinese Physics B 2011年第7期20卷 88-93页

作者： Ghulam Shabbir amjad Ali Suhail Khan Faculty of Engineering Sciences GIK Institute of Engineering Sciences and TechnologyTopiSwabiKhyber PukhtoonkhwaPakistan Department of Basic Sciences University of Engineering and TechnologyPeshawarKhyber PukhtoonkhwaPakistan

In this paper we classify Bianchi type Ⅷ and IX space-times according to their teleparallel Killing vector fields in the teleparallel theory of gravitation by using a direct integration technique. It turns out that the dimensions of the teleparallel Killing vector fields are either 4 or 5. From the above study we have shown that the Killing vector fields for Bianchi type Ⅷ and Ⅸ space-times in the context of teleparallel theory are different from that in general relativity.

关键词： WeitzenbSck geometry teleparallel theory of gravitation conservation laws

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Some new estimates for the commutators of n-dimensional Hausdorff operator

引用

Applied Mathematics(A Journal of Chinese Universities) 2014年第2期29卷 139-150页

作者： HUSSAIN amjad GAO Gui-lian Department of Mathematics COMSATS Institute of Information Technology School of Science Hangzhou Dianzi University

In this paper, we discuss the boundedness of commutators of high dimensional Hausdorff operator He on Herz type spaces. In addition, central BMO estimates for such commutators are also presented.

关键词： Hausdorff operators Commutators Herz Spaces Lipschitz functions CBMO functions.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Response of masonry systems against blast loading

引用

Defence Technology（防务技术） 2021年第4期17卷 1326-1337页

作者： Eid Badshah amjad Naseer Mohammad Ashraf Tauseef Ahmad Department of Civil Engineering UET PeshawarPakistan Electrical Engineering Department CECOS University of IT&Emerging Sciences PeshawarPakistan

In this paper eight successive experimental blast tests with an increasing TNT equivalent charge weights ranging from 0.56 kg to 17.78 kg were conducted on unreinforced,ferrocemented overlay masonry and confined masonry *** pressure-time history caused by the blast was recorded by pressure sensors installed on the test *** resulting damage pattern was observed during each *** zones in the three systems of masonry were *** distances for different damage levels in the three masonry systems were experimentally *** results provide a basis for determining the response of each masonry system against blast ***,efficiency of ferrocemented overlay masonry and confined masonry was found established in mitigation against blast loads.

关键词： Peak over pressure Pressure sensor Composition-B TNT Scaled distance Stand-off distance Charge shape Confined Unreinforced Ferrocemented

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：