查询词典 numerical analysis

Theoretical analysis and numerical results show that the new reconstruction algorithm can reduce the computational complexity and greatly improve the numerical stability.

理论分析和数值试验都表明，这种新的重建算法较常用的Newton-Raphson类算法，不仅数值稳定性有较大的提高，而且计算量有所减少。

With the development of the numerical value method, the simulation technology of numerical value analysis is applied widely and improved.

数值计算方法的迅速发展使得数值模拟技术得到广泛的应用和提高。

In this topic, the dynamic analysis methods for piezoelectric vibrator are studied systematically based on the theoretical model, FEM numerical experimentation and FEM governing equation for given compound-mode vibrator, and some valuable conclusions are obtained. The main work accomplished is summarized as follows: 1.Elaborate the main modeling methods for piezoelectric vibrator and the significance and necessity to study the dynamic characteristics of piezoelectric vibrator which emphasize the urgency of this paper. 2.Take the bending deformation induced by piezoelectric ceramic as example, the energy transfer mechanism of electric energy to mechanical energy are analyzed; the motion and force transfer mechanism are analyzed for the longitudinal-bending vibrator. 3.Based on mode assumption and Hamilton principle, the coupling model of piezoelectric vibrator of linear USM is built; moreover, the equivalent circuit model is obtained and a coupling equation represents the relation between electric parameters and mechanical parameters is derived which provides foundation to match the vibrator and driving circuit. 4.Combine the constitutive equation of piezoelectric ceramic with elastic-dynamical equation, geometric equation in force field and the Maxwell equation in electric field and the corresponding boundary condition equation, the FEM control equation for piezoelectric vibrator of USM to solve dynamic electro-mechanical coupling field is established by employing the principle of virtual displacement. The equation lays the foundation to study the non-linear constitutive equation of piezoelectric ceramic driven by high-power. 5.Define the dynamic indexes of characteristic of vibrator and carry out variable parameters simulation by calculating the model parameters and the electric characteristics of vibrator are simulated according to the equivalent circuit model. By numerical experimentation, the working mode of vibration of vibrator and the shock excitation results of the working frequency band which provides the mode frequency to realize bimodal are analyzed. Detailed calculation of the electro-mechanical coupling field parameters is made by programming the FEM control equation.

本课题从理论模型、有限元数值试验、有限元控制模型等方面以复合振动模式振子为例对超声电机压电振子的动力学特性及其分析方法进行了全面系统地研究，得出了许多有价值的结论，主要概括如下： 1、阐述了目前针对超声电机压电振子的主要建模方法，对压电振子动态特性的研究意义和必要性进行了论述，突出了本文研究内容的迫切性； 2、以压电陶瓷诱发弹性体发生弯曲变形为例，分析了压电陶瓷通过诱发应变来实现机电能量转换的机理；对基于纵弯模式的压电振子的运动及动力传递机理进行了分析； 3、基于模态假定，利用分析动力学的Hamilton原理，建立了面向直线超声电机压电振子的机电耦合动力学模型，并据此建立了压电振子的等效电路模型，导出了电参量与动力学特性参量的耦合方程，为压电振子与驱动电路的匹配提供了依据； 4、从压电陶瓷的本构方程出发，综合力场的弹性动力学方程、几何方程、电场的麦克斯韦方程以及相应的边界条件方程，采用虚位移原理，建立了压电振子动态问题机电耦合场求解的有限元控制方程，为研究其大功率驱动下的非线性本构模型奠定了基础； 5、界定压电振子的动力学特性指标，对压电振子的机电耦合动力学模型参数进行计算及变参数仿真；依据等效电路模型，对压电振子的电学特性进行了仿真分析；通过有限元数值实验，对压电振子工作模态附近的模态振型及工作频率附近的频段进行了激振效果分析，找出了实现模态简并的激振频率；利用有限元控制方程，通过编程计算，对压电振子的力电耦合场参数进行了详细计算，得出了一些有价值的结论。

Based on the dynamic equation, the transport and acceleration of out-flowing ionospheric ions in the magnetosphere are studied by means of finding the ion distribution function. They include two parts: the study of static ion distribution with analysis and numerical compute; the study of ion acceleration by induced electric feild in the period of dipolarization of taillike geomagnetic lines in the substorm expansion phase with the numerical simulation of the ion distribution function.

本文在磁层中上行离子的加速与传输理论研究领域中，采用动力论方程，用求解离子分布函数的方法来研究问题：(1)用解析求解和数值计算的方法，对上行离子在不同Kp指数条件下磁场位形中的定态分布进行了研究；(2)用数值模拟计算分布函数的方法，对上行离子在亚暴膨胀相磁场向偶极形驰豫过程中受磁尾的感应电场加速进行了研究。

Incurrent research, aiming at the rupture problem engendered in the shooting process of acertain 5.56mm automatic rifle, the strain and stress distributions on the cartridge caseunder the action of axial pull have been analyzed. Based on the theories of elastic-plasticmechanics and contact mechanics, a mathematic and physical model of the cartridge-caseand chamber system has been set up; and based on the platform of the general softwarepackage APDL of ANSYS for finite element analysis, a parameterized model of thecartridge-case and chamber system has also been established. The method for nonlinearFEA has been adopted to analyze the stress distribution on the entire cartridge-case andchamber system, and the method of contact element has been employed to investigate thecontact stress between the cartridge case and chamber, and then the influences of frictioncoefficient and locking space on the static and dynamic stress and strain response of thecartridge case and chamber to the action of power gas have also been discussed. On thebasis of a lot of numerical tests, a kind of element Plane13, which is concentrated incoupled computation of heat and construction, has been used finally to simulate thetransient response of the cartridge-case and chamber system to the power gas. Throughloading the temporary thermal characteristics of explosive gas in the procedure of emulate, the corresponding transient thermal stress distributed on the entire system under thecombined load of transient thermal stress and transient pressure has been obtained. Owingto these comprehensive considerations, the numerical results obtained in this paperrepresent the actual situations comparatively exactly.

本文针对某5.56mm自动步枪在工作中出现断壳的问题，分析了弹壳在轴向拉力作用下的应力应变；基于弹塑性力学及接触理论，建立了弹壳弹膛系统的数学、物理学模型，在通用有限元ANSYS软件的参数化建模工具APDL平台上，建立了弹壳弹膛系统的参数化模型；采用非线性有限元法计算了弹壳弹膛系统的整体应力，引入接触单元法分析弹壳和弹膛的接触压力，探讨了在不同的摩擦系数和不同的闭锁间隙对弹壳弹膛静、动态响应的影响；本文进行了大量的尝试，最后确定采用热、结构耦合单元Plane13，在计算中加载了火药气体的温度历程，成功的获得了弹壳弹膛系统在瞬态的热载荷和瞬态的压力载荷同时作用下弹壳弹膛系统的热应力数值解，考虑因素全面，比较真实的反映了弹壳弹膛系统在火药气体压力和热载荷下作用的情况。

Consequently, numerical results are used to reveal the effects of the dielectric superstrate to the characteristics of the antenna and are compared with the results from pub-lished references and other numerical solutions for demonstrating the accuracy of the analysis.

最终，通过数值结果揭示出了覆盖介质层对天线特性的影响并且与已发表文献及其他数值方法的结果进行对比，证明了方法的正确性。

Numerical simulations showed the axial velocity in the precessing flow were decreased significantly because of the entrainment of ambient air. The swirling motion, the wall attachment effect and the reverse flow were also found in the numerical flow field. It is shown that the simulation results of the precessing jet flow accord well with the analysis and the previous work.

数值模拟表明旋进射流的轴向流动速度衰减得很快，流场中存在明显的旋流、附壁效应和反向回流现象，所得到的结果与已有的分析结论基本吻合。

From the analysis and comparing with different illustration, it proves that the numerical model used in this paper is correct and the results of numerical study are in agreement with the facticity about the flow field.

通过对数值计算结果的分析和比较，证明数值模拟所用的计算模型是有效的，较好地反映了旋流器内液固两相流场的物理真实性。

To develop reliable numerical simulation tools is very important for the theoretical research, experimental analysis and load designing of Z-pinch implosions. A dedicated Z-pinch implosion physical scheme of the two-dimensional numerical simulation of three-temperature radiation magneto- hydrodynamics code is introduced.

研制了用于Z箍缩内爆数值模拟的二维三温辐射磁流体力学程序，MARED程序适用于不同装置条件、不同负载参数。

In the paper, based on reading and studying a great number of references about fluid dynamic technique and numerical computing methods of flow field, 3-D Numerical simulations and visual analysis of the flow field in hydraulic poppet valve with inside flow work condition were obtained by CFD software Fluent.

本文在参阅大量国内外有关计算流体力学和流场数值计算方法相关资料的基础上，用CFD软件Fluent对内流工况液压锥阀内部流场进行了三维数值模拟及可视化分析。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。