查询词典 impact

The vibro-impact systems are familiar with the non-smooth dynamic systems.The dynamics research of the vibro-impact systems not only is significant in theory but also has practical values in engineering.Firstly,using the Poincaré map method,we get an existent criterion of single impact period-n motion in a two-degree-of-freedom vibro-impact system with damper.It is shown that our conclusions are valid through the numerical simulations.Moreover,the satiability of periodic motions is studied and the correspon...

基于Poincaré映射的方法，通过解析的方法导出了一类具有阻尼的两自由度碰撞振动系统的单碰周期n次谐运动存在性判据，经过数值模拟验证了理论分析的正确性，并给出了分析其稳定性的判别公式，通过数值模拟，讨论系统的局部分岔与全局分岔，同时比较了系统参数变化对其周期运动的影响，发现在强阻尼、弱激励、小质量比、较大恢复系数下系统将会出现较多的有规律的周期碰撞。

In other research we can find this situation:children have myth concept in time unit and time unit conversion, include impact of psychological time, impact of numbers, impact of decimal and impact of sexagesimal.

另外在研究中发现，学童在时间单位量与时间单位转换中的迷思概念，包含心理时间的影响，数字大小的影响，十进位的影响，六十进位的影响。

It analyzed impact principle, and researched viscidity and springiness model of soil. So the relation of impact and soil was found, and the dynamic model of impact bar-soil system was established. After analyzing and researching the model, a better dynamic model with soil impact character was gained.

针对土壤的物理特性，对冲击原理进行分析，并对土壤的粘弹性模型进行研究，建立冲击与土壤之间的联系，为土壤压实冲击测量装置建立了冲击杆—土壤系统的动力学模型，并对模型进行分析研究，简化出更适合土壤冲击特性的动力学模型。

Studies on impactrelated minerals, geochemical anomalies, impact microspherules and microtektites enable us to define frequencies, magnitudes and types of impact bodies of extraterrestrial impact events. Impact layers and ejectas may not only provide distinct event markers in highresolution stratigraphical correlation, but also potential interpretations for the catastrophic changes and their causes of life and global environment.

通过对撞击地层层序的时空变化、所包含的撞击成因矿物、撞击微球粒和微玻璃陨石以及古生物和地球化学异常等的研究，可以了解撞击事件的发生频率、幅度和撞击天体的性质等，也为探索生物和地球环境的灾难性变化及其起因提供了新的思路。

In this dissertation, periodic impact motions in vibro-impact systems are studied, and the existence and stability of superharmonic periodic impact motions are obtained. The critical bifurcation parameter intervals of superharmonic periodic impact motions are deduced, and numerical simulations are used to verify the results.

中文题名碰振或约束系统的全局分析及稳定性研究副题名外文题名 Studies on global analysis and stability in vibro-impact or constraint systems 论文作者张彦梅导师陆启韶教授学科专业一般力学与力学基础研究领域\研究方向学位级别博士学位授予单位北京航空航天大学学位授予日期2002 论文页码总数95页关键词碰振系统转子系统多体系统碰撞振动馆藏号BSLW /2003 /O322 /1 本论文讨论了碰撞振动系统的周期碰撞运动，得到了超谐周期碰撞运动的存在性和稳定性，推导出亚谐周期运动的临界分岔参数区间，并利用数值模拟进行验证。

But, the characteristics of its adhered-elastic fracture in high temperature and brittle fracture in low temperature were discovered during impact load test The impact fracture mechanism of the high-energy nitroamine propellant had been put forward by studying the fracture appearances of impact fracture surface, the expansion of secondary crack and the weakness or failing of mechanical structure combined with the analysis of impact fracture properties and dynamic adhered-elastic properties and structures.

通过研究冲击断裂表界面的断口形貌、二次裂纹的发展、材料的力学结构缺陷或弱点，并结合冲击断裂性能、动态粘弹性能及结构分析，提出了硝胺发射药的冲击断裂破坏机理。

The coal impact breaking mechanism and impact coal cutter were introduced in the paper, the primary task of this project, study on the dynamic characteristic of hydraulic impact system of impact coal cutter, was pointed out.

本文介绍了冲击式破煤机理的提出和冲击式采煤机的研究现状，然后指出了本课题的主要任务是研究液压冲击系统的动态特性。

Friday, rubber, plastics, rubber adhesive tape test series grinding test machine, wear test machine, wear testing machine, folding machine, foam compression stress test machine, foam plastic repeated compression test machines, test material removed machine, Determination of the plastic melt index machine, impact testing machine, heating distortion temperature testing machine, falling ball impact test machine, rigid plastic drop hammer impact test machine, plastic film drop hammer impact testing machine, high temperature ashing furnace, temperature testing machine tape retention, Tape retention test machine, the beginning of sticky tape ball test machine, color device, industrial projectors, coordinate measuring instrument.

五、橡胶、塑胶、胶带试验系列橡胶胶磨试验机、磨耗试验机、耐磨试验机、耐折试验机、泡棉压缩应力试验机、发泡塑反复压缩试验机、试料磨平机、塑胶熔融指数测定机、冲击试验机、加热变形温度试验机、落球冲击试验机、硬质塑胶落锤冲击试验机、塑胶膜落锤冲击试验机、高温灰化炉、恒温胶带保持力试验机、胶带保持力试验机、胶带初粘性滚球试验机、色差仪、工业投影仪、三座标测量仪。

House's air impact moulding is a way to impact the sand with general impact flask in an enclosed impact house.

仓式气冲造型是指在密闭的冲击仓里用普通砂箱进行冲击紧实的一种方法，其关键是砂箱周围冲击仓的间隙体积本文研究了间隙率对仓式气冲造型紧实效果的影

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。

By analyzing several currently-used visual displaying schemes for cranes simulation training, a display concept based on enhanced virtuality is proposed and some key issues in it are discussed. Manipulation based human-computer interaction technology is studied and two typical virtual controller are realized by associating the time or the location parameter of modeling with its movement parameters. A implement method of physical controller is presented based on virtual keyboard mapping technology and a compact and flexible control box prototype is obtained. Using it, users can operate the virtual crane conveniently.

分析了目前起重机模拟培训常用的几种视景显示方案，提出了一种基于增强现实的显示概念，并对其中若干问题的实现方法进行了探讨；研究了基于操纵的人机交互技术，通过时间或造型位置与起重机运动参数之间建立的联系，实现了两种典型的虚拟控制器；提出了一种基于虚拟键盘映射技术的物理控制器解决方案，设计了一个小巧、灵活的控制盒原型，可以方便地操作虚拟起重机并实现有关运动。

These POIs include traffic conditions, weather forecasts, pictures and other POI near the location. We also solve the problems that information provided by general software can not be updated timeliness and the disadvantage of lack of geographical information.

透过Ajax架构的使用来辅助使用者操作，让系统能够提供交通状况、天气预测、实景图片与邻近地点查询的加值POI资讯，解决单机软体所提供的资料无法即时更新的时效性问题，以及地域性资讯缺乏的缺点。