探讨电流变效应及其相关教学问题

1947年,美国人温斯洛发现了电流变现象,引起了全世界科学家的研究热情,这种利用电场控制物质形态变化的现象能够将电信号指令变成机械动作,促进了与此相关的一系列科学研究的进程。电流变效应使电流变材料具备了工程应用的价值,已在工程领域的阻尼可调节的隔振器、制动力可调节的制动器等方面取得了极大的成就,目前电流变技术已广泛应用于航空航天、生产自动化、汽车船舶、机器人工程、武器控制、农业机械等领域。文章介绍了电流变效应,并探讨了大学物理教学引入电流变效应的相关教学问题。     

电流变液纤维化结构的研究

基于偶极近似,运用电动力学方法研究了电流变液中悬浮颗粒在外电场作用下其形状的变化和微粒排列的取向,并计算了其形状的相对变化率,探讨了电流变液产生相变的微观机制．     

一种机动车前轮悬架的设计及应用

该文介绍一种新型机动车前轮悬架,它由主、副减振器以及减振弹簧组成,其中减振弹簧由三个螺旋弹簧并联组成,在承受不同载荷时,减振弹簧刚度值随之变化。在主减振器与副减振器间存在较小夹角,并随载荷不同而发生变化,有利于改善了阻尼系数。这种结构提高驾驶时的舒适性,特别适合在单前轮机动车上使用。     

可变阻尼对汽车悬架系统振动性能影响分析

通过建立1/4悬架系统的理论数模,分析阻尼系数影响系统的幅频特性.在不同的振动频率范围内,阻尼的相应变化将改善悬架系统的输出性能.     

β-环糊精―有机酸包合物材料的电流变性能研究

用β-环糊精(简称β-CD)、对甲苯磺酸、磺基水杨酸、对氨基苯磺酸、对苯二甲酸、α-萘乙酸和2,6-吡啶二羧酸为原料,采用固相反应,合成了新型的电流变材料———以β-环糊精为主体、磺基水杨酸等有机酸为客体的包合物.研究了材料的组成结构与材料电流变性能的关系.结果表明:包合对甲苯磺酸和磺基水杨酸可以明显的提高主体β-环糊精的电流变性能,β-环糊精与磺基水杨酸的包合物有最高的电流变活性.     

磁流变阻尼器的应用

磁流变流体与电流变流体一起被称为新兴的智能软物质，它具有液一固两相转换的可逆性、连续可控性和响应快速等高技术特征，在液压、振动制动、驱动密封等的主动和自适应控制中具有广阔的应用前景．本讨论了磁流变液的组成、性质，比较了磁流变液与电流变液的不同性质，介绍了磁流变阻尼器的工作模式及其应用．     

Using an evidential reasoning approach for portfolio assessments in a project-based learning engineering design course

The purpose of this study is to analyse the feasibility of an evidential reasoning (ER) method for portfolio assessments and comparison of the results found with those based on a traditional holistic judgement. An ER approach has been incorporated into portfolio assessment of an undergraduate engineering design course delivered as a project-based learning (PBL) course and the calculated utility interval means of the student results compared with weighted rubric means based on a traditional holistic judgement. The findings show the ER method superior to the traditional holistic judgement in that ER is capable of incorporating, firstly, assessors' ignorance of information concerning the portfolio development and content and, secondly, incomplete portfolio information. The ER approach is a commendable alternative to traditional holistic judgement of PBL portfolios, since it provides additional information, increases accuracy and is easier to use.     

圆环形薄板大挠度变形有限元分析比较研究

环形薄板是汽车减振器中的一个重要零件,属于典型的大挠度非线性变形,传统的计算方法要么产生误差较大,或者计算繁琐不利于工程应用。本文借助于现代分析软件,利用有限元分析方法对汽车减振器中不同规格环形薄板的大挠度变形情况进行了研究。根据von Kármán提出的微分方程,结合钱氏摄动法给出了求解大挠曲变形的解析表达式,拟合出了解析式中的待定系数的数学表达式,并针对固定半径比、内/外径等不同情况进行了计算分析和误差比较。数值计算证明,使用的方法合理可靠,求解精度高、简单快捷实用,误差在3%以下,完全可以满足工程设计分析的需要。     

圆盘式电流变传动机构的优化设计

讨论圆盘式电流变传动机构的优化设计，它涉及机构的动态品质、电流变流体的物理性能和装置的结构参数，并给出圆盘直径、剪切速度、极化力和粘性力之间的关系。     

落球法测电流变液粘度的实验研究

通过对电流变液中落球的运动分析，间接求出电流变液的表现粘度，并与旋转粘度计的实测数据对比，得出一定条件下，落球法测电流变液粘度的方法是可行的，为简易测定电流变液的粘度提供了方法。     

电流变液及其物理机理

回顾了电流变液的研究概况，介绍了电流变液的电流变特性，分析了电流变效应的物理机理，阐述了电流变效应的影响因素。     

电流变液机理和料的研究

从物理角度阐述了电流变液机制,分析了作用于电流变液内悬浮颗粒上的力,并综述了电流变液物理模型和电流变液的发展概况.     

一个ER菜单系统

本文用实体关联模型（ER模型）代替关系模型,使多库文件之间的数据检索,数据库完整性的维护等方面得到较好的处理,其设计和实现是用一个ER菜单来描述,并作为一个前端建立在Foxpro上。     

机械图形的XML数据存储结构设计

研究了XML数据的存储方法,并在比较现有的存储策略的基础上,提出了采取用户定制的方案。随之进行了图形关系模式的逻辑设计,进行了元数据库设计,组件库设计,并建立了ER集成模型。最后分别建立了元数据表,图形实体,风格属性的物理模型。通过对XML数据存储结构的设计能更好的发挥机械图形标记语言的潜能。     

基于Trucksim的城市客车典型工况悬架动载荷提取

以城市客车为平台,分析其车辆动力学各子系统的型式和参数,根据现有积累的试验测试数据,采用Trucksim软件建立整车多体动力学模型。在此基础上,对城市客车制动、转弯、冲击及扭曲等典型运行工况进行动态模拟,提取出悬架系统各部件的受力情况,包括弹簧、减震器等。结果表明,城市客车在冲击工况下悬架整体受载最大。该仿真结果能够为城市客车有限元模型各典型工况下的载荷施加提供精确的输入,有利于提高受力分析的准确度。     

Dynamic Responses Analysis of a Building Structure Subjected to Ground Shock from a Tunnel Explosion

Dynamic responses of a multi-storey building without or with a sliding base-isolation device for ground shock induced by an in-tunnel explosion are numerically analyzed. The effect of an adjacent tunnel in between the building and the explosion tunnel, which affects ground shock propagation , is considered in the analysis. Different modeling methods, such as the eight-node equal-parametric finite element and mass-lumped system, are used to establish the coupling model consisting of the two adjacent tunnels, the surrounding soil medium with the Lysmer viscous boundary condition, and the multi-storey building with or without the sliding base-isolation device. In numerical calculations , a continuous friction model, which is different from the traditional Coulomb friction model, is adopted to improve the computational efficiency and reduce the accumulated errors. Some example analyses are subsequently performed to study the response characteristics of the building and the sliding base-isolation device to ground shock. The effect of the adjacent tunnel in between the building and the explosion tunnel on the ground shock wave propagation is also investigated. The final conclusions based on the numerical results will provide some guidance in engineering practice.     

高校人才培养质量综合评价：一种基于证据推理的方法

作为教学质量监管工作的重要手段,高校人才培养质量评价正发挥着越来越重要的作用。本质上,该问题可看作一个包含定性属性和定量属性的多属性决策问题。证据推理自身技术上的特点决定了它可以用于该类问题的解决。本文建立了高校人才培养质量综合评价的一般体系,提出了基于证据推理的高校人才培养质量综合评价模型,并通过案例,说明了该方法的应用。     

Emotion Regulation in Achievement Situations: An Integrated Model

Achievement emotions are critical because of their impact on success and failure in important domains such as learning. These emotions may be modified via emotion regulation (ER). The dominant process model of ER (PMER) proposed by J. Gross, however, provides a domain-general account of ER strategies and has not had substantial contact with theories of achievement emotions such as R. Pekrun’s control-value theory (CVT) and the academic achievement literature. Moreover, ER has not been a focal point of major theories related to achievement emotions, such as CVT. We propose an integrated model of ER in achievement situations (ERAS) that integrates propositions about the generation of emotions from CVT with propositions about how emotions are regulated and types of ER strategies from PMER. The ERAS model also offers new propositions regarding how different achievement situations, object foci, and time frames, as well as discrete emotions with different appraisal patterns, impact ER strategies.     

Multi-objective Optimal Design of Vibration Absorber with Simple Cell Mapping Algorithm

In this paper, we investigate a multi-objective optimal design of a tuned vibration absorber for a two degrees-of-freedom linear system, in which we take white Gaussian noise as the excitation. We use the simple cell mapping method to obtain solutions to the multi-objective optimization problem. We optimize tuned vibration absorbers in two different configurations. As our objective,we take various features of the response of the power spectrum density function. Our results show that the primary mass vibration with the optimally designed absorber has a lower peak power spectrum value. In addition, the two natural frequencies of the optimized system are further apart than in the non-optimized system, which implies that the absorber has a wider effective region in the frequency domain.     

光学限制器的优化与设计

以激发态吸收材料为例,使用有效三能级模型,介绍了浓度梯度分布光限制器和串级光限制器的设计原理和方法.这两种设计方法能有效提高光限制器的动态范围,达到优化设计的目的.