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建立原假设和备择假设是进行假设检验的第一步.如何设立假设检验中的原假设和备择假设,是学生和初学者普遍困扰的问题.而根据奈曼—皮尔逊准则,原假设和备择假设的地位不对等.本文对如何建立假设检验中的原假设和备择假设进行了讨论,给出了几个建立原假设和备择假设的原则. 相似文献
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假设检验的原假设的设立原则为保护原假设.这一原则一般只适用于单侧假设检验问题.而对于双侧参数假设检验,通常只把参数相等的假设设为原假设,并不需要遵守上面的原则.这一现象在教科书中的解释并不是很充分,本文在正态分布总体的前提下,从功效函数和小概率事件原理等角度给出这一问题的较为详细的统计解释. 相似文献
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在解题教学中注重优化假设的数学思想与方法 ,探索解题的思路和规律 ,能培养学生的直觉思维、发散思维和想象力 .在各类的数学问题中 ,有许多的题目可由条件和结论的特殊性与一般性的辩证关系 ,采用优化假设思想 ,创设新的解题思路 ,优化解题过程 .优化假设通过恰当的假设处理问题 ,优化出新的解题方法与思路 .优化假设是科学的发现、创造的方法之一 ,在优化假设过程中 ,体现了假设、猜想、优化等数学思想 ,渗透了数学其他的方法和思路 ,在高考和数学竞赛题中有许多数学问题能采用此方法给予解决 .1 假设条件特殊化优化解题思路一个命题成… 相似文献
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针对假设检验中"对一个具体问题,在相同的显著性水平α下进行假设检验,如果交换原假设和备择假设,得到的结论可能完全相反"这一问题进行分析,并给出根据实际问题的要求如何正确建立原假设和备择假设的方法. 相似文献
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研究一类多目标分式规划的二阶对称对偶问题.在二阶F-凸性假设下给出了对偶问题的弱对偶、强对偶和逆对偶定理.并在对称和反对称假设下研究了该问题的自身对偶性. 相似文献
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本文考虑了n维带边流形上的k-Yamabe问题.当2 k≤n/2时,假设方程是具有变分结构的.在之前的文献中,人们都是假设流形是局部共形平坦的.当k=2时,在较弱的假设下,本文可以推广已有的k-Yamabe问题的结论.特别地,本文证明了,当n4、边界的平均曲率非负、且流形的Yamabe常数比标准半球面的Yamabe常数严格小时,2-Yamabe问题是可解的. 相似文献
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《Finite Elements in Analysis and Design》2009,45(1):52-59
This paper deals with pressure-based finite element analysis of fluid–structure systems considering the coupled fluid and structural dynamics. The present method uses two-dimensional fluid elements and structural line elements for the numerical simulation of the problem. The equations of motion of the fluid, considered inviscid and compressible, are expressed in terms of the pressure variable alone. The solution of the coupled system is accomplished by solving the two systems separately with the interaction effects at the fluid–solid interface enforced by an iterative scheme. Non-divergent pressure and displacement are obtained simultaneously through iterations. The Galerkin weighted residual method-based FE formulation and the iterative solution procedure are explained in detail followed by some numerical examples. Numerical results are compared with the existing solutions to validate the code for sloshing with fluid–structure coupling. 相似文献
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A. N. Doludenko 《Computational Mathematics and Mathematical Physics》2017,57(9):1550-1557
The Richtmyer–Meshkov and Rayleigh–Taylor instabilities in viscoplastic (Bingham) fluids are studied in two-dimensional setting. The evolution of the Richtmyer–Meshkov instability in a Bingham fluid is analyzed as compared with its evolution in a Newtonian fluid. The critical amplitude of the initial perturbation in the velocity field is estimated. Numerical results obtained for Richtmyer–Meshkov and Rayleigh–Taylor instabilities in a Bingham fluid are presented and compared with those obtained for a Newtonian fluid. 相似文献
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A two-station network with controllable inputs and sequencing control, proposed by Wein (Oper. Res. 38:1065–1078, 1990), is analyzed. A control is sought to minimize holding cost subject to a throughput constraint. In a Lagrangian formulation, input vanishes in the fluid limit. Several alternative fluid models, including workload formulations, are analyzed to develop a heuristic policy for the stochastic network. Both the fluid heuristic and Wein’s diffusion solution are compared with the optimal policy by solving the dynamic program. Examples with up to six customer classes, using Poisson arrival and service processes, are presented. The fluid heuristic does well at sequencing control but the diffusion gives additional, and better, information on input control. The fluid analysis, in particular whether the fluid priorities are greedy, aids in determining whether the fluid heuristic contains useful information. 相似文献
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K. A. Landman 《Studies in Applied Mathematics》1983,69(1):51-73
The dynamic response of a small, very viscous liquid droplet composed of a core fluid surrounded by a thin fluid shell is examined as additional fluid is deposited into this incompressible shell. At early times, the shell incorporates the extra mass by ruffling its external surface, and a number of crenations form. These protuberances decrease in size and number over a longer time period, and eventually the droplet again becomes spherical, with an increased radius. This sequence of events and its dependence on the rheological properties of the fluids are studied. These effects compare well qualitatively with those obtained using a surface fluid rather than a finite thickness shell of fluid. The possible implications of this fluid model for the surface ruffling effects observed in cell biology are discussed. 相似文献
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This study investigates free vibration of a thick FG circular plate in contact with an inviscid, and incompressible fluid. Analysis of plate is based on First-order Shear Deformation Reissner–Mindlin Theory (FSDT) with consideration of rotational inertial effects and transverse shear stresses. Potential theory together Bernouli's equation are utilized to obtain the fluid pressure on the free surface of the plate. The governing equation of the oscillatory behavior of the fluid is obtained by solving Laplace equation and satisfying its boundary conditions. The natural frequencies and mode shapes of the plate are determined using Chebyshev polynomials. The effects of the geometrical parameters such as plate thickness to its radius ratio, boundary conditions, fluid density, volume fraction index, and height of the fluid on natural frequencies and mode shapes are investigated. Comparison of analytically outcome of this study is made with similar publications in the literature. 相似文献
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The velocity field and the adequate tangential stress that is induced by the flow due to a constantly accelerating plate in an Oldroyd-B fluid, are determined by means of Fourier sine transforms. The solutions corresponding to a Maxwell, Second grade and Navier–Stokes fluid appear as limiting cases of the solutions obtained here. However, in marked contrast to the solution for a Navier–Stokes fluid, in the case of an Oldroyd-B fluid oscillations are set up which decay exponentially with time. 相似文献
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Jiheng Zhang 《Queueing Systems》2013,73(2):147-193
We study many-server queues with abandonment in which customers have general service and patience time distributions. The dynamics of the system are modeled using measure-valued processes, to keep track of the residual service and patience times of each customer. Deterministic fluid models are established to provide a first-order approximation for this model. The fluid model solution, which is proved to uniquely exist, serves as the fluid limit of the many-server queue, as the number of servers becomes large. Based on the fluid model solution, first-order approximations for various performance quantities are proposed. 相似文献
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L. A. Molotkov 《Journal of Mathematical Sciences》2006,132(1):69-82
The propagation of seismic waves in block two- and three-dimensional fluid media is investigated. For these media, effective
models, which are anisotropic fluids, are established. Formulas for the velocities of wave propagation in these fluid media
are derived and analyzed. Special investigation is conducted in the cases where blocks with different fluids alternate along
the coordinate axes or where blocks filled with a fluid are surrounded by blocks with another fluid. In both cases, the dependence
of the wave velocities in the entire medium on the differences of the densities and the wave velocities in fluid blocks is
studied. Bibliography: 9 titles.
Dedicated to P. V. Krauklis on the occasion of his seventieth birthday
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Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 308, 2004, pp. 124–146. 相似文献