查询词典 impact

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。

First, the S-CDMA-HFC system with integrated traffic is introduced and the method of traffic integration is given. Second, the upstream channel capacity of the S-CDMA-HFC system with integrated traffic that has the same rate is analyzed. The chronoff limit and Gaussian approximate equation of the upstream channel cutoff probability are derived. Third, the impact of the selection of the line transmission rate on the upstream channel capacity of the S-CDMA-HFC system with integrated traffic is discussed in detail. The cutoff probability and throughout equations of the upstream channel with different integrated traffic are derived. Fourth, the impact of the power control error on the capacity is discussed. Results show that the power control error will degrade the upstream channel capacity and have different influence on the different traffic. Finally, the capacity requirement of the initialization process is raised. Analytical results show that the initialization process will impact on the capacity slightly.

首先，简单介绍了综合业务S-CDMA-HFC系统，给出了业务综合的方法；然后，分析了具有相同码率的综合业务条件下的S-CDMA-HFC系统上行信道容量，导出上行信道中断概率的切尔诺夫上限和高斯近似公式；然后，详细讨论了基本传输速率的选择对综合业务S-CDMA-HFC系统上行信道容量的影响，导出了不同业务综合条件下上行信道的中断概率和吞吐量公式；然后，讨论了功率控制误差对综合业务S-CDMA-HFC系统上行信道容量的影响，结果表明功率控制误差会使上行信道容量下降，且对不同业务的影响程度是不同的；最后给出了初始接入的容量要求，分析结果表明初始接入将对综合业务S-CDMA-HFC系统上行容量带来影响，但不明显。

In order to testify our whether correction to Rossi's exchange term andthe potential of electron and nucleus is reasonable, we calculate 〓 moleculeelastic differential scattering cross section by electron impact on 100eV, ourresult is obviously better than Rossi's. Then we calculate elastic differentialscattering cross section at 150eV. In order to check the program thatcalculates molecule excitation cross section by electron impact, we calculatehydrogen excitation cross section from ground state to 〓 state at 20eVand 30eV, oxygen excitation cross section from ground state to 〓 state at15eV and 20eV. These calculations are in agreement with other theoreticresults, and experiment measure. Finally, we calculate sulfur moleculeexcitation〓 cross section by electron impact at5eV,7eV,9eV, 11eV, 13eV,15eV, and draw curve of excitation total crosssection corresponding to incident electron energy.

为了核对我们修改的计算激发态的程序是否正确，计算了电子与氢分子碰撞从基态激发到〓态入射能量分别为20eV和30eV时的微分截面以及电子与氧分子碰撞从基态激发到〓态入射能量分别为15eV和20eV时的微分截面，与别人的理论计算结果、实验的测量值基本一致，最后计算了电子与硫分子在5eV、7eV、9eV、11eV、13eV、15eV时的碰撞激发〓截面，作出了电子的入射能量与激发总截面的关系曲线，找出了总截面最大时对应的电子入射能量大约是11电子伏。

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Based on the low-velocity impact test, 4 major modes of low-velocity impact damage including delamination and matrix cracking were taken into account FEM simulation. By using appropriate failure criterion, the low-velocity impact damage of z-pin reinforced laminates can be identified.

从z-pin增韧复合材料层合板低速冲击实验出发，考虑了复合材料层合板在受低速冲击时的分层及基体开裂等四种损伤形式，引入适当的损伤判据，对T300/3234碳纤维树脂基复合材料层合板的低速冲击损伤过程进行有限元模拟。

This characteristic could be qualitatively explained as interference between σ amplitude and π amplitude of electrons final wavefunction. It also depends on the impact parameters: the π amplitude contribution is dominant at small impact parameters, which leads to a symmetric velocity distribution around the internuclear axis. However, At large impact parameters the σ amplitude contribution increases relatively, resulting into a asymmetric electrons velocity distribution around the internuclear axis.

出射电子的上述分布特征可由出射电子波函数σ振幅和π振幅的干涉进行定性解释，σ振幅和π振幅对出射电子波函数的贡献与碰撞参数相关，在小碰撞参数下，π振幅的贡献更加明显；而在大碰撞参数下，σ振幅的贡献更加显著。

Thirdly, the problems of institution investor'optimal liquidation strategy and optimal liquidation time were investigated with the conditions that the price of risky asset followed arithmetic Brown motion and liquidation velocity was limited. The problems involved the following scenes: price impact function was linear expression of liquidation velocity which was boundary closed set with an isolated point; price impact function was stochastic; price impact function was nonlinear.

接着，当风险资产的价格服从算术布朗运动，且对投资者的变现速度做出限制时，研究机构投资者的最优变现策略和最优变现时间问题，其中包括：价格冲击函数为变现速度的线性函数，变现速度是一带有孤立点的有界闭集；价格冲击是随机形式；价格冲击是变现速度的非线性函数。

This paper describes and analyzes the Kronstadt Russian Communist Party after the events occurred before and after the policy notable changes in the political, economic, cultural and other aspects of the Russian Communist Party has made on the corresponding adjustment and the reasons for the changes, but these adjustments and just change to the impact of the establishment of Soviet power is a double impact - both positive and negative and adverse impact.

本文以1921年春，俄国波罗的海舰队主要军事基地喀琅施塔得发生动乱为切入点。喀琅施塔得事件---这是苏维埃政权建设初期的重大政治事件，虽然迅速被苏维埃政府平息了，但是从19世纪20年代年到20世纪80年代的很长一段时间里史学界都把喀琅施塔得事件看做是反对俄共和苏维埃政府的一场叛乱。本文试图通过重组喀琅施塔得事件发生和发展过程，分析喀琅施塔得事件发生原因和结果。

Based on the modified Hertz contact theory and the simplified simulation of impact a new method is approved to calculate the impact force of outrunner blocks in debris flow on structures. Based on a limited parametric study, it is shown that the impact causes plastic deformation on concrete structures at a low velocity.

计算结果表明，泥石流大块石在很小的冲击速度（小于1m/s）下就可能导致混凝土材料冲击接触面上产生塑性变形。

Environmental concerns: the scale of the impact; the severity of the impact; probability of occurrence; duration of impact.

从环境方面考虑：环境影响的规模；环境影响的严重程度；发生的概率；环境影响的持续时间

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了