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structure of Thunderstorm Gust Fronts with Topographic Effects

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Advances in Atmospheric sciences 2001年第6期18卷 1161-1174页

作者： A. A. Bidokhti and T. Bani-Hashem institute of Geophysics, Tehran University, p.o, Box 14155-6466, Tehran, LR. Iran institute of Geophysics Tehran University Tehran I. R. Iran

surface meteorological observations, associated with gust fronts p.oduced by thunderstorm outflows over Tehran, an area surrounded by mountains, have been analyzed. Distinctive features are sudden drop in air temperature, up to 10°C, sharp increase in wind speed, up to 30 m s?1, with wind shift, to northwesterly, pressure jump, up to 4 hpa, humidity increase, up to 40%, and rain after some 20 min. Gust fronts which often occur in spring time, have a typical thickness of about 1.5 km and p.oduce vertical wind shear of the order of 10?2s?1. Although these features seem to be common for most of the events, their intensities differ from one event to another, indicating that the gust fronts may occur in different sizes and shapes. Apart from a dominant effect on the formation of the original thunderstorms, topography appears to break up the frontal structure of the gust fronts. The internal Rossby radius of deformation for these flows is small enough (～ 100 km) for rotational effects to be minor. A laboratory model of the gust front (gravity current) also shows that it initially has a distinctive head with a turbulent wake, and can be broken up by topography. It is shown that when the environment is stratified, turbulence due to lobes and clefts instabilities near the nose of the current is suppressed. When the ground is rough, these instabilities are highly amplified and the internal Froude number of the flow is reduced. The bottom slope in the presence of rough topography leads to the break up.of the current head and p.oduces a broad and highly non-uniform head, recognized in the density signals. Key words Frontal structure - Gravity current - meteorological data - outflows

关键词： Frontal structure Gravity current meteorological data outflows

pARALLEL mULTI-sTAGE & mULTI-sTEp mETHoD IN oDEs

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Journal of Computational mathematics 2000年第2期18卷 157-164页

作者： Xiao-qiu song (institute of Computer Application and simulation technology p.o.Box 3929, Beijing 100854, China) 北京计算机应用与仿真技术所北京 100854

presents information on a study which discussed the theory of parallel multi-stage and multi-step method, which is a form of combining Runge-Kutta method with linear multi-step method. Basic theory and equations; Appl... 详细信息

关键词： ordinary differential equations parallel simulation

The effects of relative density of metal foams on the stresses and deformation of beam under bending

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Acta mechanica sinica 2007年第4期23卷 409-414页

作者： Aiyu Zhu Tianyou Fan Department of mathematics,school of science,Beijing institute of technology,p.o.Box 327,Beijing 100081,China Department of physics,school of science,Beijing institute of technology,p.o.Box 327,Beijing 100081,China Department of mathematics School of Science Beijing Institute of Technology Beijing China Department of physics School of Science Beijing Institute of Technology Beijing China

The exact analytic solution of the pure bending beam of metallic foams is given. The effects of relative density of the material on stresses and deformation are revealed with the Triantafillou and Gibson constitutive law （TG model） taken as the analysis basis. several examples for individual foams are discussed, showing the importance of compressibility of the cellular materials. one of the objects of this study is to generalize Hill＇s solution for incompressible plasticity to the case of compressible plasticity, and a kinematics parameter is brought into the analysis so that the velocity field can be determined.

关键词： metal foams - Relative density Compressible plasticity Constitutive law - TG model

study on the Effects of End-bend Cantilevered stator in a 2-stage Axial Compressor

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Journal of Thermal science 2009年第2期18卷 119-125页

作者： songtao WANG Xin DU Zhongqi WANG Harbin institute of technology, p.o. BoX 458, Harbin 150001, China Harbin institute of technology Harbin China

Leading edge recambering is applied to the cantilevered stator vanes in a 2-stage compressor in this paper. Differentcurving effects are p.oduced when the end-bend stator vanes are stacked in different ways. stacking on theleading edge induces a positive curving effect near the *** it is stacked on the centre of gravity, a negativecurving effect takes place. The numerical investigation shows that the flow field is redistributed when theend-bend stators with leading edge stacking are applied. The variations in the stage matching for the mainstreamand near the hub have an impact on the performance of the 2-stage compressor. The isentropic efficiency and thetotal pressure ratio of the compressor are increased near the design condition. The compressor total pressure ratiois decreased near choke and near stall. The maximum flow rate is reduced and the stall margin is decreased.

关键词： axial compressor end-bend blade stacking stage matching

A Class of parallel Implicit Runge-Kutta Formulas

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Journal of systems Engineering and Electronics 1993年第4期4卷 53-63页

作者： Fei JinggaoBeijing institute of Computer Application and simulation technology p.o. Box 3929, Beijing 100854, China Beijing institute of Computer Application and simulation technology p.o. Box 3929 Beijing 100854 China

A class of parallel implicit Runge-Kutta formulas is constructed for multip.ocessor system. A family of parallel implicit two-stage fourth order Runge-Kutta formulas is given. For these formulas, the convergence is p.oved and the stability analysis is given. The numerical examples demonstrate that these formulas can solve an extensive class of initial value p.oblems for the ordinary differential equations.

关键词： multip.ocessor system parallel algorithm ordinary differential equation Implicit Runge-Kutta formula.

Analytic Research of Laser-generatedplasma parameters

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Chinese Journal of Lasers 1995年第4期B4卷 323-328页

作者： ZHANG Jianquan(Northwest institute of Nuclear technology p.o.Box 69, Xi’ an 710024,China) Northwest Inst of Nuclear technology Xi'an China

ＡｎａｌｙｔｉｃＲｅｓｅａｒｃｈｏｆＬａｓｅｒ－ｇｅｎｅｒａｔｅｄＰｌａｓｍａＰａｒａｍｅｔｅｒｓ￥ＺＨＡＮＧＪｉａｎｑｕａｎ（ＮｏｒｔｈｗｅｓｔＩｎｓｔｉｔｕｔｅｏｆＮｕｃｌｅａｒＴｅｃｈｎｏｌｏｇｙＰ．Ｏ．Ｂｏｘ... 详细信息

ＡｎａｌｙｔｉｃＲｅｓｅａｒｃｈｏｆＬａｓｅｒ－ｇｅｎｅｒａｔｅｄＰｌａｓｍａＰａｒａｍｅｔｅｒｓ￥ＺＨＡＮＧＪｉａｎｑｕａｎ（ＮｏｒｔｈｗｅｓｔＩｎｓｔｉｔｕｔｅｏｆＮｕｃｌｅａｒＴｅｃｈｎｏｌｏｇｙＰ．Ｏ．Ｂｏｘ６９，Ｘｉ＇ａｎ７１００２４，Ｃｈ...

关键词： intense pulsed laser laser-generated plasma vapour plasma parameters

sTEERING sAFETY EVALUATIoN oF DRIVER VEHICLE CLosED Loop sYsTEm WITH RANDom RoAD INpUT

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Chinese Journal of mechanical Engineering 1999年第4期12卷 282-287页

作者： Zhao Youqun shandong institute of technology Guo Konghui Zhang Guiyu Jilin University of technology shandong institute of technology 山东工程学院汽车工程系山东淄博 255012 吉林工业大学汽车动态模拟国家重点实验室吉林长春山东工程学院山东淄博

The response simulation is studied and the steering safety is evaluated by using finer integration method for driver vehicle closed loop system with stationary random road *** algorithm not only is precise, but also can shorten the evaluation period of steering safety and reduce the tremendous cost for real vehicle *** response simulation and the vehicle steering safety evaluation are also studied for the closed loop system with evolutionary random road *** study can more truly evaluate vehicle driving for including the slowly varying of vehicle velocity with time.

关键词： Closed loop system Evaluation Random safety Vehicle steer ability

X-ray Crystallinity studies of palladium polyacrylate

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Journal of materials science & technology 1995年第4期11卷 310-312页

作者： R.Hussain and D.mohammad (pakistan institute of Nuclear science and technology, p.o.Box 1356, Islamabad, pakistan) pakistan Inst of Nuclear science and Technology Islamabad Pakistan

Free radical polymerized palladium polyacrylate was characterized by X-ray diffraction. Various parameters including mean crystallite size, interchain separation and radius of gyration have been calculated and discussed with respect to the concentration of pd in the polymeric salt. The results show that polymer is predominantly amorp.ous in nature.

关键词： UK X-ray Crystallinity studies of palladium polyacrylate John

A Class of Explicit parallel multistep Runge-Kutta methods

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Journal of systems Engineering and Electronics 1993年第4期4卷 64-72页

作者： Xie Yajun and Liu DeguiBeijing institute of Computer Application and simulation technology p.o.Box. 3929, Beijing 100854, China Beijing institute of Computer Application and simulation technology p.o. Box. 3929 Beijing 100854 China

In this paper, a rather general class of explicit parallel multistep Runge-Kutta methods is constructed for solving initial value p.oblem of ordinary differential equations. Also, the corresponding convergence and stability are analysed. several parallel computational formulae are given. The numerical experiments, including accuracy, speedup, and efficiency tests show that the methods are efficient.

关键词： Runge-Kutta method Initial value p.oblem.