铁道车辆减振器的数字设计

应用适用于现代车辆悬挂系统的设计与制造的液压减振器动态数学模型,有效描述研究模型参数与减振器的内部结构、零部件设置与减振器动态特性的关系. 将液压减振器动态数学模型作为用户模型加入MSC Adams,进行车辆系统动力学数值仿真研究. 以提速客车转向架CW 200为实例,应用液压减振器动态数学模型进行车辆悬挂系统参数的数值优化研究. 线路试验表明,应用新研制的减振器可明显改进车辆系统动力学性能.     

减振器叠加节流阀片非线性特性仿真分析

研究减振器节流阀系非线性特性优化问题。对减振器叠加节流阀系结构以及阻尼力分段特性进行分析,分别建立了减振器叠加阀系的固体力学模型和流体力学模型,利用adina软件的固体模块、流体模块及流固耦合模块进行流固耦合动态响应分析,得到了减振器叠加节流阀系的非线性节流特性、叠加节流阀片动态响应特性、减振器节流阀系流场特性。此方法克服了传统建模方法的缺陷,对减振器阀系优化设计以及特性分析具有实际参考价值。     

程序配电器减振器等效模拟及动强度分析

为优化橡胶减振器与程序配电器的性能参数匹配,提高程序配电器的安全性和可靠性,在Patran中采用等效模拟的方法进行某橡胶减振器结构的有限元建模,分析连接螺栓的动态强度特性,并通过试验进行特性验证.结果证明所采用的建模方法和仿真技术可行.     

车用双筒式液压减振器外特性建模仿真

针对汽车悬架弹性元件易产生振动的问题,为行驶的平顺性,以车用双简式液压减振器的结构原理为基础,根据弯曲变形系数、常通节流孔面积和阀片预变形量,给出了减振器开阀速度点的数学解析式.采用开阀速度点和节流阀开度及流量与压力之间的关系,建立了减振器速度特性的分段数学模型.通过对数学模型施加一定的激励信号,对减振器特性进行仿真.仿真结果表明所建立的仿真模型是正确的,对减振器设计有一定的指导意义.     

非线性半主动悬架系统模糊控制策略

为了实现复杂非线性车辆半主动悬架系统的减振控制,对整个系统的动力学特性和磁流变减振器的特性进行分析,得到期望的阻尼力变化趋势,并由此提出一种直接针对减振器电流的新型模糊控制策略.该策略构建了以车身加速度、减振器两端速度差以及悬架动行程作为输入的三维控制结构,并将其简化为二维结构,同时引入减振器的设计思想制定了非对称的模...     

阀片型减振器的外特性仿真

本文应用流体力学和弹性力学的理论，推导出了阀片型减振器阻尼力的计算公式，并对长安微车的后减振器进行了测绘和计算。在此基础上，用Ｃ语言编制了计算程序，对阀片型减振器的示功图和速度特性曲线进行了仿真。     

减振器试验平台及其测控系统研究

减振器是机车转向架上一个很重要的部件,它与弹簧一起构成弹簧减振装置。现有的试验规范以测试示功图为主要目的,国内试验平台多为开环、机械式,存在许多不合理之处。改进的试验方案为闭环控制方式,可测量减振器的阻尼特性、示功图等参数。结合该测控系统,探讨了在Win32环境下开发实时测控软件应该注意的问题,如提高过程控制软件的实时性、扩展对硬件的访问和操作、OOP程序设计、故障诊断和查询专家系统设计等。     

最优控制理论在人车路磁流变半主动悬架中的应用

基于半主动悬架车辆的1/4动力学模型,论述了磁流变液特性及磁流变减振器的工作原理,推导了在随机最优控制理论下可调阻尼力和状态变量之间的关系,应用matlab/simulink编制了人车路模型的仿真程序,并以简化模型为例,考察了在磁流变阻尼器控制下的人车路平顺性问题.计算结果表明,与没有磁流变减振器的被动悬架相比较,该减振器的应用能够较好的改善汽车的平顺性,对提高人体的舒适性以及进一步深入研究该系统的振动,改善道路的振动特性有一定的指导意义.     

超级单胎牵引车振动仿真分析和优化

针对某超级单胎牵引车的驾驶室振动问题,在MD Adams中建立该牵引车的刚柔耦合模型,采用平顺性随机试验测量的加速度值作为输入进行仿真,与试验结果对比验证该动力学模型的准确性.通过进行整车系统模态分析、车速灵敏度分析和频率响应分析,找出引起驾驶室振动加剧的主要原因,即在特定车速下路面激励频率与驾驶室固有频率接近,形成共振.对驾驶室悬架系统的减振器特性参数进行优化,降低驾驶室的振动加速度响应,实现该款牵引车平顺性的性能提升.     

针对机车低频晃车问题的频变阻尼减振器仿真分析研究

针对某型高速机车车体横向低频晃动问题,提出一种将传统抗蛇行减振器替换为频变阻尼减振器(FSD)的抑制方法.首先,应用Simpack建立该机车动力学模型,从车体振动频域分布对车体横向低频晃动特性进行分析,分析表明车体横向晃动频率在1-2Hz之间;然后,建立频率阀的CFD计算模型和FSD减振器数值简化模型;最后,对比应用传...     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.