基于多导体传输线理论的脉冲变压器锥形绕组电压分布数值分析

 为了研究脉冲变压器锥形绕组在脉冲电压作用下的电压分布特性,采用多导体传输线方法,根据实际脉冲变压器锥形绕组的结构,建立了电气参数有限元简化计算模型及等效多导体传输线分析数学模型,以此模型计算了锥形绕组在脉冲电压激励下匝间的电压分布。计算结果表明,此模型可对脉冲变压器锥形绕组的电压分布进行有效计算,对绕组匝间绝缘设计有一定的参考意义。     

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为考察ITER真空室中子屏蔽结构组件对选址地法国Cadarache地震加速度频谱的单点响应情况,根据ITER真空室中子屏蔽组件的设计概念和结构特点,建立了组件结构的有限元分析模型。应用有限元分析软件ANSYS对组件进行了结构模态分析,并基于其结果进行了模态叠加。分析发现,组件结构的低阶振型与高阶振型有差异,且结构与低阶频率发生响应,但引起的位移与应力在允许的范围之内。结果表明,装配体结构更能适应结构抗震性的设计要求。仿真计算的结果为组件结构的优化设计和下一步的工程实现提供了可靠的依据。     

Moving Finite Element Methods for a System of Semi-Linear Fractional Diffusion Equations

This paper studies a system of semi-linear fractional diffusion equations which arise in competitive predator-prey models by replacing the second-order derivatives in the spatial variables with fractional derivatives of order less than two. Moving finite element methods are proposed to solve the system of fractional diffusion equations and the convergence rates of the methods are proved. Numerical examples are carried out to confirm the theoretical findings. Some applications in anomalous diffusive Lotka-Volterra and Michaelis-Menten-Holling predator-prey models are studied.     

水听器线列阵近场声压测量误差实验研究

本文介绍了用于近场声压的测量水听器中阵元水听器测量声压的可靠性检验方法和实验结果,提出了元水听器测量球面波场中声传播衰减的曲线与现想球面波声场中场传播衰减的曲线对比的检验,要用球面声源声中心测量值对收发距离进行修正的方法,实验水池中对线列阵上十元水吸器在球形声源水池中进行了传播衰减曲线的测量分析,验证了基阵的弱散散射性能,表明线阵可用于距离小至1／7波长的极近场的扫描测量。     

Unified a Priori Error Estimate and a Posteriori Error Estimate of CIP-FEM for Elliptic Equations

This paper is devoted to a unified a priori and a posteriori error analysis of CIP-FEM (continuous interior penalty finite element method) for second-order elliptic problems. Compared with the classic a priori error analysis in literature, our technique can easily apply for any type regularity assumption on the exact solution, especially for the case of lower $H^{1+s}$ weak regularity under consideration, where 0 ≤$s$≤ 1/2. Because of the penalty term used in the CIP-FEM, Galerkin orthogonality is lost and Céa Lemma for conforming finite element methods can not be applied immediately when 0≤$s$≤1/2. To overcome this difficulty, our main idea is introducing an auxiliary $C^1$ finite element space in the analysis of the penalty term. The same tool is also utilized in the explicit a posteriori error analysis of CIP-FEM.     

Predictions of pulsed field gradient NMR echo-decays for molecules diffusing in various restrictive geometries. Simulations of diffusion propagators based on a finite element method

Pulsed field gradient NMR diffusometry is a promising tool for investigating structures of porous material through determinations of dynamic displacements of molecules in porous systems. A problem with this approach is the lack of closed analytical expressions for echo-decays in anything but idealized pore geometries. We present here an approach based on calculating the appropriate diffusion propagator by means of finite element calculations. The suggested method is quite general, and can be applied to arbitrary porous systems. The protocol for the calculations is outlined and we show results from some different cases: diffusion in confined geometries and in systems that are spatially inhomogeneous with respect to concentration.