查询词典 hourglass

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。

Disk within androecium, nectariferous, flattened, annular, cup-shaped, pulvinate, or sometimes columnar, bell-shaped, conic, or hourglass-shaped.

花盘 在雄蕊群内，分泌蜜汁，扁平，环状，杯形，枕状，或者有时柱形，铃形，圆锥形，或者沙漏形。

Later the sand ran out of the hourglass by the binnacle and he turned it and rang the ship's bell.

过了一会儿，他看到罗盘操作台旁边的沙漏计时器已经漏光了砂子。

Among the many remarkable final projects that have been proposed and presented at the end of the course have been a Renaissance hourglass blown in the MIT glass shop and set into a frame turned on our set shop lathe; a four harness loom built by a student who then wove cloth on it; a number of chain mail tunics and coifs; a wide variety of costume and furniture pieces and electrified period lighting fixtures.

在以往的课程中，学生们构想并于期末展示出了很多优秀的作品，比如一个文艺复兴时期的沙漏，它是学生在麻省理工学院的玻璃工作坊吹制、并在我们布景工作坊的车床上成形的；一台由学生制作的四综纺织机，制作者真正用它来织布；许多锁子甲束腰外衣和头巾；各式各样的服饰、家俱和电气化时代的照明设备。

The copper clepsydra was also called a water clock, hourglass, and sandglass.

铜壶滴漏又叫"漏刻"、"刻漏"、"壶漏"、"漏壶"。

Meshing properties and application of major conical surface double envelope Hourglass worm gearing;2. In this paper, the regularities of undercutting and topping of major conical surface envelope hourglass worm is researched.

分析了大锥面包络环面蜗杆的齿顶变尖和根切规律，并通过和平面包络环面蜗杆的比较，得出其在根切和齿顶变尖这两个方面具有比平面包络蜗杆更优良的性能，因而是一种在实际中可替代平面包络、具有广泛应用前景的新型包络蜗杆传动。

On the condition of "many-head" and "small drive ratio",the plane double enveloping hourglass worm can not settle the problem of undercutting and sharpening simultaneously.It has devoted to a new type hourglass worm_sphere double enveloping hourglass worm.

考虑到平面二次包络环面蜗杆传动在多头小传动比条件下根切与齿顶变尖的矛盾很难同时解决且啮合性能较差，介绍了一种新型环面蜗杆传动——球面二次包络环面蜗杆传动。

On the basis of the research on the model of the planar enveloping hourglass meshing surface, the software is developed in which the design environment of enveloping hourglass worm pairs is parameterized.

在平面包络环面啮合型面的精确建模等研究的基础上，进行了包络传动副啮合副参数化设计环境的软件开发。

Furthermore, the reconstituted model of planar enveloping hourglass meshing surface is established in the light of the research of 3D surface reconstituted algorithm, and 3D error of the real planar enveloping hourglass meshing surface is derived accordingly.

利用计算机处理技术，提出了测头半径补偿的算法，进行了三维型面重构算法的研究，建立平面包络环面啮合型面重构模型，在此基础上获取了平面包络环面啮合型面三维误差。

Abrasive disk for accurately grinding TI worm,as well as grinding method similar to that for globoid worm or planer enveloping hourglass worm,is used to machine hourglass worm,making the TI worm match with the worm wheel which has the same tooth surface shape as that of abrasive disk,and thus forming a new-style worm gearing .

采用精确磨削TI蜗杆的砂轮，用类似直廓环面蜗杆或平面包络环面蜗杆的磨削方法加工环面蜗杆，使该蜗杆和齿面形状与砂轮曲面相同的蜗轮相配合，形成一种新型蜗杆传动，给出了这种传动蜗杆副齿面的数学模型，并通过计算机仿真得出了这种传动蜗轮齿面上接触线的形状及分布特征，初步分析了其啮合特点。

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