等加速度

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。

It can be concluded that the feature of position curve of water in jig is the same as the curve of typical damped vibration. In the equations the motion parameters of water in jig, such as velocity, acceleration, force etc. are in a direct proportion to the air pressure, and have a definite non-linear relationship with jigging cycle, thickness, and mobility of jig bed.

结果表明，水流运动的位移曲线特性符合阻尼强迫振动规律，水流运动的位移、速度、加速度、受力、动能等运动参数与跳汰机风压有直接的线性关系，与跳汰周期、阻力、床层松散度等跳汰参数有明确的非线性关系。

Try to do this in time – that would be impossible to do exactly, there are different factors that can affect the time, like file system cache, disk cache, distribution of files on a disk, what else is going on your computer, etc. The accurate estimation of time is possible only for processes which have speed and acceleration as natural characteristics.

尝试这样做的时间-这是不可能做到准确，有不同的因素会影响时间等文件系统缓存，磁盘缓存，磁盘上的文件分配，又是什么将您的计算机上，等时间的准确的估计可能只有进程具有速度和加速度的自然特色。

The minor principal stress of slab, the maximum acceleration in up-down stream direction and permanent deformation of the dam body for three-directional earthquake excitation are obviously different from those for unidirectional and two-directional earthquake loading.

计算表明，多向地震动下的面板峰值小主应力、顺河向峰值加速度及坝体的永久变形均与单向和双向输入时显著不同，实际工程计算时应同时考虑三个方向的地震动；振动型地震激励引起的坝体反应明显大于冲击型地震激励；随着地震动强度的增加，峰值加速度、峰值剪应变、面板应力和周边缝变形等增加；面板刚度对面板的应力值和周边缝的变位具有较大影响，当面板模量取值较低时，计算所得到的"面板"应力集中部位不甚明显，计算结论为新型的"土工膜面板堆石坝"提供了理论依据。

Secondly, the simulative software has been made using MATLAB to simulate the suspensory point load、 velocity、 acceleration and pure toque of speed reducer shaft of pumping unit on any place and the displacement、 velocity、 acceleration of main component of pumping unit and the forces of linked point of two components, so the changes of the motion and the force of pumping unit and the geometry parameters' influence on the main performances of pumping unit have been dynamic analyzed.

其次，利用MATLAB，编制了仿真软什，对抽油机在任意位置时的悬点载荷、速度、加速度和减速器输出轴抓矩以及抽油机主要构件的位移、速度、加速度利各构件连接点的受力等进行了仿真，从而动态地分析了抽油机的运动利受力变化及几何参数对抽油机主要性能的影响情况。

An airdropped mine's acceleration built-in measurement system based on this proposed algorithm had been built. Test results showed that it worked well and could be used for other dynamic measurement applications.

利用此算法设计的空布水雷加速度测试仪，经模拟、空投等试验，可靠、准确获取了水雷在空布过程的加速度变化规律，该算法也可以应用于其它动态参数测试系统中。

The analysis results indicate that the vibration fractional factor with rotating frequency has a close relationship with both rotating speed of rotor and damping of bearing under constant acceleration. When rotating acceleration is small and damping is large, the transient response is not sensitive to the variation of rotating speed; otherwise the imbalance response with constant acceleration and the response in stable state will build up obvious differences near critical rotating speed.

研究结果表明：在恒加速条件下，转子同频振动分量与转子的转速、支承阻尼等因素密切相关，当角加速度较小且阻尼较大时，其瞬态响应对转速的波动不敏感；而当角加速度较大或阻尼较小时，恒加速过程不平衡响应与稳态响应在临界转速附近将产生明显的差异。

In order to contribute to analyse and compute easily setback moving devices on the projectile fuzes,and to make the fuze devisers be able to get the approximate acceleration curves with a few parameters such as tube length and muzzle velocity of the guns,the displacement-time curve and velocity-time curve of gun interior ballistic are fitted with the Logistic models,then the formula of projectile acceleration curves in bore are gotten by the derivation of the formula of fitting velocity-time curve.

为了便于炮弹引信后坐运动机构的分析和计算，能使引信工作者只根据身管长度和炮口速度等少量参数就能获得弹丸膛内加速度近似曲线，运用Logistic函数拟合火炮内弹道的位移－时间曲线和速度－时间曲线，再对拟合得到的速度－时间曲线求导便得到了弹丸膛内加速度近似曲线。

Aiming at the specific mission that intercept the warhead of tactical ballistic missile, the new issue for designing the guidance law is analyzed, and a new guidance method that fit for the mid-course is presented, based on the idea of predicting the intercept point.

针对拦截战术弹道导弹这一特殊任务，分析了导引律设计面临的新问题，提出了以预测拦截命中点为思想的中制导段导引方法，研究了末制导段比例导引律弹道形状和过载分布特点，在此基础上为了改善比例导引律的缺陷，引入了目标机动加速度和导弹轴向加速度等信息，对比例导引律进行了修正，并对导引律中各参数进行了优化。

From the analysis of automobile vibration sources and the human responses to vibration, a mechanic model of man-chair-vehicle system with 13 degrees of freedom is built by vibration pattern analyzing technology. Using the random vibration theory, the calculating methods are developed for parameters, including vibration pattern, transfer function, wheel transient load, and acceleration of seat, automobile ride quality simulation software is developed.

通过分析汽车振动源和人体对振动的反应，用模态综合技术，建立了十三自由度人－椅－车系统的动力学模型，运用随机振动理论，给出了振动形态、传递函数、悬架动挠度、车轮动载荷、座椅加速度等参量的计算方法，开发了一套&汽车平顺性仿真软件&并利用已有的汽车数据，对汽车行驶时的振动特性进行了仿真，得到了重要结论：发动机与轮胎刚度、阻尼，后桥阻尼对驾驶员座椅处的振动影响不大；驾驶员座椅的垂直刚度增加很大时，对垂直方向振动响应比较大；前桥刚度、阻尼对驾驶员座椅处的振动影响较大；前轮胎刚度对前桥振动影响较大，前轮胎刚度增加，则振动加强；后桥刚度对汽车平顺性有一定影响，后桥刚度减小，则座椅处垂直加速度减小。

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