推理论

The basic approach of protecting people from being hurt or killed in an accident is to improve crashworthiness of vehicles. This paper starts with discussing theories and methods for vehicle passive safety design, which included experiential methods, analytic methods, multi-body dynamics methods, crash test methods and the finite element method. Emphasis will be paid to the basic FEM theories and algorithms of impact problems. Topics discussed include the governing equation, element discretization, hourglass control, time integration, material model, shell element algorithms and contact-impact algorithms. For more reliable simulation results, this paper then conducts study on how to accurately get material model parameters by combining the FEM method with experimental method, and develops relevant material test machine and parameter calculating software. Based on that, basic typical impact simulation and test validation study are conducted. On the basis of the above work, the paper studies the thin-shell structures'crashworthiness, which was affected by the following factors: spot-weld features, shell thickness, cross-section and pre-deformation. As to vehicle parts'crashworthiness, the paper conducts simulation study of designing energy-absorbing steering system and adaptive airbag system. A practical energy-absorbing steering wheel is designed as an example. In further depth research, the paper suggests several inverse quantificational methods for vehicle crashworthiness design based on the ideal crash characteristics. The above theories and methods are applied with good results through several practical vehicles' crashworthiness design and improvement.

文中对汽车碰撞安全性的设计理论和方法进行了归类和总结，其中包括经验法、解析法、多刚体动力学法、试验法以及有限元方法等；重点介绍了碰撞有限元法的基本理论和有关算法，涉及到有限元求解控制方程、单元离散、沙漏模态控制、时间积分、材料模型和应力修正、薄壳单元算法以及接触碰撞界面算法等，探讨了有限元计算中的材料模型参数获取技术，开发了相应的材料试验装置及材料模型参数反求软件，在此基础上进行了基本的碰撞仿真算例和试验对比研究；文中通过应用有限元方法研究了薄壁构件的碰撞吸能特性，指出了设计薄壁吸能构件时需要考虑的几个主要影响因素，即焊点、壁厚、横截面和预变形等；在关于车辆部件的碰撞安全性能设计中进行了吸能转向机构和自适应安全气囊的仿真研究，提出了吸能转向机构和自适应安全气囊的仿真研究方法；文中最后探讨了整车碰撞性能的设计与改进方法，提出了以理想碰撞特性为目标，采用分段加速度或者根据碰撞时间进行设计的反推设计法、部件吸能仿真优化设计法等量化设计方法，并通过综合应用文中所讨论的相关技术进行了整车碰撞性能的设计与改进实例研究，所选定的车型是大众化的普通轿车和碰撞安全性基础较差的微型面包车，研究结果表明，本文所提出的设计与改进方法是适用而有效的，具有重要的工程实用意义和价值。

This paper quantitates financial risk by constituting the model of measurement financial risk. And the samples are from the public companies'merger and acquisition from 2002 to 2005, this paper demonstrates perfectly the influence of financial risk of acquisition companies from different payment methods. The result of test analysis shows: in one side, the theory of risk-return is unfit in China (by being educed conclusions by other students: different payment methods bring different return, then the author detrusions different payment methods bringing different financial risk, and being tested direct proportion each other); in the other side, this paper answers different payment methods bringing different degree financial risk of acquisition companies: the smallest financial risk from cash payment method, the mean from commingle payment method, the biggest from stock payment method, which can supply reference in the choice of rational companies between payment methods and financial risk .

通过建立企业财务风险度量模型，将企业财务风险量化，并以中国上市公司2002年—2005年间的并购案中所采用的支付方式为样本，对我国上市公司并购中不同支付方式对并购方财务风险的影响做一个较系统、完善的实证检验，一方面从理论上验证了风险-收益理论的在我国的不具有适用性（通过对前人研究结论：不同支付方式带来不同收益，进而反推不同支付方式带来不同的财务风险，验证得出二者成正比关系）；另一方面回答在我国目前市场条件下并购中的不同支付方式引起收购公司不同程度的财务风险，其中现金支付方式下给收购公司带来的财务风险最小；混合支付次之，股票支付方式下财务风险最大，能给企业在并购时选择支付方式与财务风险的最佳组合提供参考。

In this thesis, a semi-classical model of the force on an atom is used to describe the motion of a two-level atom interacting with a standing wave laser field. The velocity dependent force and momentum diffusion are derived through optical Bloch equations by using the matrix form of the continued fraction technique. By investigating the dynamic properties of atoms in laser field, we can control and manipulate the mechanical motion of an atom.

本文利用半经典理论，从二能级原子在激光驻波场中所满足的运动方程出发，推导出密度矩阵元所满足的递推关系，利用矩阵连分数方法求解出密度矩阵元，从而求出依赖于原子运动速度的光压力与动量扩散系数，通过讨论原子在激光场中的动力学行为，为原子在激光场中被囚禁、形成原子列阵以及可控制的量子态，从而为量子信息处理提供理论基础。

Hereto, this article completes demonstrability of the relationship between instruction theory and teaching practice in Engineering-thinking visual angle and elucidatory of related divergent using.

在这种可能性中，对教学理论与教学实践及其关系的认识将会逐步走向全面与深入。至此，本文完成了工程思维视角下教学理论与教学实践关系的初步论证及相关推演。

The solitary wave can be generated considering Goring and Raichlen's movement of a paddle. The proposed original linear solution for the solitary wave generation is expressed in the hypergeometric function. Two disadvantages of the original solution with large trailing wave and skewed wave profile are found by comparing with the theory of solitary wave derived from Boussinesq's equation.

本文并以弱非线性的孤立波造波问题做为解析之对象，由於孤立波造波板速度为一超越函数，造成解析上的困难；本文以 hypergeometric 函数推求常微分方程式之全解，并与理论波形解比较后，发现由於未考虑非线性及分散性过强等问题，使得线性暂态解较理论波形拉长与歪斜，可能无法有效描述孤立波造波问题，故针对线性之分散关系做出修正。

The solitary wave can be generated considering Goring and Raichlen's movement of a paddle. The proposed original linear solution for the solitary wave generation is expressed in the hypergeometric function. Two disadvantages of the original solution with large trailing wave and skewed wave profile are found by comparing with the theory of solitary wave derived from Boussinesq's equation. The difference between the original linear solution and the solitary wave theory results from the nonlinearity and dispersion of generated waves in the flume.

本文并以弱非线性的孤立波造波问题做为解析之对象，由於孤立波造波板速度为一超越函数，造成解析上的困难；本文以 hypergeometric 函数推求常微分方程式之全解，并与理论波形解比较后，发现由於未考虑非线性及分散性过强等问题，使得线性暂态解较理论波形拉长与歪斜，可能无法有效描述孤立波造波问题，故针对线性之分散关系做出修正。

The Jacobin matrix of the multi-body system dynamics was studied based on the spatial operator algebra theory,and the realization of the Jacobin matrix procedure was built in the environment of Matahematic5.2 software.The high effective stepping method can be used to compute velocity and static force,and has a simple math expression.

应用空间算子代数理论，在通用计算机符号演算软件Mathematic5.2的环境下，对多体系统动力学雅可比矩阵进行设计与实现，主要用于速度和静力的高效递推算法，用空间算子代数理论求出雅可比矩阵简洁形式，具有编程效率高、直观等特征。

At last,introducing"coupling matrix library"and utilizing Jourdain'svelocity principle and forward recursive formulation method,the theoryestablished in chapter two and three is successfully extended to couplingdynamical formulation modeling of complex flexible multibody system.

最后，在第二、三章的理论基础上，本文引入"耦合矩阵库"的概念，利用Jourdain速度变分原理和单向递推建模方法，成功地将该理论推广到了复杂柔性多体系统刚-柔耦合动力学程式化建模。

To solve this problem and make the theory of efficiency limit more complete, this project studies the efficiency limit when phase only and spatial quantization are simultaneously considered.

为求改善上述的实用性问题及绕射效率上限的理论完整性，本计画研究同时考虑纯相位及空间量化两个因素的绕射效率上限，其研究包含理论推演及电脑模拟。

Discrete calculus , discrete probability distribution s, discrete Fourier transform s, discrete geometry , discrete logarithm s, discrete differential geometry , discrete exterior calculus , discrete Morse theory , difference equation s, and discrete dynamical system s.

在应用数学中，离散模型连续模型的离散近似。在离散模型中，离散方程are fit to 数据。使用递推关系是这种建模方式的一般方法。时标微积分是差分方程理论与微分方程理论的统一，应用在需要建立离散和连续同步数据模型的领域。

On closer examination, though, this is not a vote for multilateralism but just the opposite.

仔细审视后我们发现，这并非是对多边主义投出的赞成票，而是恰好相反。

Uncovering their weak spots, so I can defeat them.

揭露出他们的弱点，这样我就可以打败他们了。