一种新型的弧焊焊缝跟踪超声传感系统

本文利用声电匹配和聚焦声透镜技术，研制出１．１５ＭＨｚ高灵敏度，高分辨率空气超声传感器，设计了单片机信号采集，处理，控制软硬件系统和纠偏执行机构，首次实现扫描式，固定式超声传感器二维自动跟踪，跟踪精神模纵向均达到了０．５ｍｍ。     

电弧超声焊缝跟踪的试验研究

利用声发射探头接收的电弧超声信号进行焊缝跟踪检测。结果表明：对称位置接收到的声发射信号的相位差和幅值差可以作为电弧超声焊缝跟踪的依据。     

专利信息

一种用于射线探伤底片分析管理方法，工业应用的相控阵超声检测方法，全数字式相控阵超声波无损检测的图像重建方法，相控阵超声检测系统控制声束聚焦扫描和接收的方法，悬浮式跟踪钢管超声自动探伤装置     

用声发射传感器的焊缝跟踪控制研究

基于缝隙对声发射波传播有影响的现象，作者研制成一种利用声发射－微处理器控制的焊缝跟踪系统。本文叙述了缝隙对声发射波传播的影响和焊缝跟踪控制装置的设计。试验表明这种焊缝跟踪控制装置是灵敏的，它能克服偏差，正确跟踪直焊缝和曲线焊缝。     

单电源驱动双超声压缩振子的系统研制

传统的单超声电源一般只能驱动单个超声振子,根据实际情况需要,提出了采用单个超声电源同时驱动两个超声振子的新方法。在测试和比较单个超声换能器和双超声换能器的阻抗特性的基础上,进行了基于FPGA的双超声压缩系统的电源设计,设计了电源的硬件电路及以FPGA为核心的控制系统。该控制系统采用最大电流法和相位差法相结合的方法实现频率自动跟踪功能。通过双超声、单超声和无超声压缩生物质的对比实验,验证了该电源能很好地驱动双超声振子有效、稳定地工作,双超声压缩效果优于单超声和无超声压缩。     

超声发生器频率跟踪的控制

介绍了单片机控制的电流反馈式超声发生器的系统结构，分析了频率自动跟踪的原理及实现方法，完成了变步长频率跟踪的软件设计，保证了频率跟踪速度和搜索精度。     

铝质高压绝缘子超声无损表征

利用超声无损表征原理对烧成温度分别为1230℃、1260℃及1290℃的铝质瓷坯料样品进行了测试分析，讨论其组织状态随温度的变化情况。研究表明，与1230℃和1290℃的样品相比，超声波在1260℃的样品中声衰减系数较小、主频偏移小。分析认为，在陶瓷材料的组织成分稳定的情况下，声衰减系数的变化主要受孔隙率的影响，并随着孔隙率的增大，声衰减增大。SEM观察结果与超声分析结果相符合，说明超声回波功率谱分析用于铝质瓷材料的表征与评价是可行的。     

35CrMo钢弹性应力与超声纵横波的声时比关系

利用拉伸试验机和超声应力检测仪，对水电机组蜗壳螺栓(35CrMo钢)进行轴向拉伸，测定其在拉伸过程中的应力值及其对应的超声横波和纵波传播时间，获得横波与纵波的声时比，建立弹性应力与超声横波与纵波声时比之间的定量关系，为利用超声波实时测定螺栓弹性应力提供依据。结果表明，在35CrMo钢所承受的轴向弹性应力处于钢的弹性变形范围内时，超声横波与纵波声时比与弹性应力之间呈线性关系。对该模型进行误差分析，结果表明，利用超声横波与纵波测定的应力值与实际应力值之间的误差为0.04%～2.08%,满足工程要求。     

基于多自由度超声检测系统的声图象分析

介绍了一种新型的多自由度超声检测系统的图象分析模块，阐述了系统中声图象的获取方法，根据声图象的特殊性，采用了适合声图象分析的数字图象处理和模式识别的方法，实现了对声图象缺陷的定量和定性的分析。     

复合材料无损检测方法

介绍国内外常用的复合材料无损检测方法，如超声检测法、X射线检验法、计算机层析照相检测法、微波检测法、声-超声检测法和声发射检测法等的原理、应用范围和进展，最后介绍声发射技术应用于检测复合材料飞轮损伤与断裂的初步研究情况。     

The arrangement of cells in a net. IV

A tessellation of Dirichlet polygons is generated from a pattern of points distributed at random over a rectangular grid, and a simple method is devised to disturb the clumps that are a characteristic feature of such a pattern, by subjecting the pattern to a clustering process. The process consists in applying a regular, periodic variation to the line-spacing of the grid. If the period of the variation is sufficiently small, or sufficiently large, the clumping is found to be scarcely affected by the clustering; but there is a narrow range of scale within which the two aggregative processes appear to interfere with each other. This interference is accompanied by a sudden and marked change in the topological properties of neighboring polygons of the tessellation, and an attempt is made to describe this change quantitatively in terms of previously established parameters. The importance of finding a physical counterpart of this geometrical effect is stressed.     

"君子之交":"水"的诱惑——一种教育学的思考

君子之交是一种非完整性的交往关系，理性的交往关系和符号化的交往关系。教育是需要不断补充的行为，大学教师决非传道、授业、解惑所能涵盖，大学师生关系的理想亦不是君子之交。相反，君子之交却行使着一种阻隔、疏远大学师生关系之功效。     

A new triangle element for the axisymmetric UBET

UBET is a useful technique for the analysis of forging and other metal forming processes. However, geometrical shape of a element used in this technique is limited to a rectangle or a right angle triangle. To overcome this problem, an arbitrary shape triangle element which define a kinematically admissible velocity field using stream function is proposed and applied to the UBET. Although, this triangle element is a proper element to be used for the analysis of plane strain problem, it has several problems to be applied to axisymmetric problem. Therefore, a new arbitrary shape triangle element which has constant inlet flow at the side of the triangle is developed. On this element, a kinematically admissible velocity field is expressed easily using stream function and a second order isoparametric triangle element. The power consumption is calculated by the numerical integration. Also, a new conversion technique is introduced for the minimization of power consumption, and it makes possible to use many variables on UBET.     

Generation mechanism of polygonal wear of work rolls in a hot leveler and a countermeasure by dynamic absorbers

This paper deals with the polygonal deformation phenomena of work rolls in a reversible hot plate leveler. According to the measurements of deformed rolls and the vibration measurement, a simple model regarding the polygonal deformation as unstable vibration caused by time retardation accompanied by wear on the surfaces of the rolls is proposed. Also, the modal analysis is applied to a general system with time retardation accompanied by wear in order to obtain the equations of motion for each mode and to derive some important parameters. Furthermore, a countermeasure for the polygonal deformation by using dynamic absorbers is considered. The optimal design of a dynamic absorber mounted on a single degree-of-freedom system where the polygonal wear is generated is discussed by applying the optimal design procedure of a dynamic absorber for forced vibration to this self-excited vibration system. As a result, a design in which the system is perfectly stabilized is obtained. This result is applied to a hot leveler as a two degree-of-freedom system through the modal analysis. By numerical analysis, it is confirmed that the hot leveler changes into a perfectly stable system by two dynamic absorbers, and the polygonal wear is not generated at all.     

聚晶金刚石比磨削能的试验研究

本文通过试验研究了PCD材料的比磨削能u与磨削工艺参数的关系。结果表明，随磨削速度vs的提高比磨削能u的变化规律为：低速区，u值较小且增长速度缓慢；中速区，u值快速提高；高速区，u值达一稳态值。随切入深度ap的提高比磨削能u的变化规律为：ap小于某值时，u值快速增长；ap大于某值时：u值达一稳态值。随刀架静刚度Fa的提高比磨削能u的变化规律为：Fa低于某值时，u值以较快速度增长；Fa高于某值时，u值达一稳态值。同时通过分析可知，PCD的磨削机理与比磨削能u存在一定的关系。u值较小时，以疲劳脆性去除为主；u值较大时，随u值的增大疲劳脆性去除的比例减小、机械热去除及热化学去除的比例增大；u值达稳态时，以机械热去除及热化学去除为主，基本不发生疲劳脆性去除。     

利用CAE技术提高注塑件原料利用率

麦克风上的一个塑料圈，材料采用聚丙烯(PP)，需要大批量生产。由于零件尺寸较小，流道系统总体积相对较大；同时对零件要求较高，不允许使用回料，所以废料较多，原材料浪费严重，增加了企业的生产成本。为减少废料，提高材料利用率，利用CAE技术对此件进行注塑成形过程分析，在保证制件成形和模具加工质量的前提下，优化注塑工艺参数，减小流道尺寸，从而节约了原料，降低了成本。     

Intelligent control planning strategies with neural network/fuzzy coordinator and sensor fusion for robotic part macro/micro-assembly tasks in a partially unknown environment

This paper addresses the problems of the robotic part assembly in a partially unknown environment. The process can be broken down into two phases. First, a macro-assembly, locating various shaped assembly holes or receptacles (targets) in the workspace corresponding to the shapes of the parts and then bringing the part to the corresponding target, despite existing obstacles. This is accomplished by combining a neural network control strategy coordinating with a mobile multiple optical sensor as well as fuzzy optimal controls. Depending on topological relationships among the part’s present position, the position of obstacles, and the target position in the workspace, a specific rulebase from a family of distinct fuzzy rulebases for avoiding obstacles is activated. An entropy function, which is a useful measure of the variability and the information in terms of uncertainty, is introduced to measure its overall performance of a task execution related to the part assembly task. Second, a micro-assembly, placing the part at a position that is ready to mate successfully with the target without jamming. Depending on a mating type, namely, a rightside, a leftside, or a straight approach toward a target, which is determined by fusing sensor information obtained by optical sensors, a specific rulebase is activated. Fuzzy set theory is used to address the uncertainty associated with the macro and the micro-assembly procedures. Using the control of a robotic part assembly task as an example, a systematic method, not a heuristic one, that can determine an optimal rulebase among feasible fuzzy rulebases which can execute the part assembly task successfully, based on a fuzzy entropy is introduced. The degree of uncertainty associated with the part assembly tasks is used as an optimality criterion, e.g. minimum fuzzy entropy, for a specific task execution. The results show the effectiveness of the above methodologies. The proposed technique is applicable to a wide range of robotic tasks including part mating with various shaped parts, pick and place operations, and motion planning.     

Computer simulation applied to an orthogonal three-rod machine tool for machining a complicated three-dimensional surface

A computer simulation approach to machine a complicated three-dimensional surface by using a virtual orthogonal three-rod machine tool is presented. First, based on a Hunt’s parallel mechanism of three degrees of freedom, a three-dimensional virtual orthogonal three-rod machine tool with three degrees of freedom is created with advanced C software. Secondly, a tool spiral path base on the three-dimensional surface of workpiece is constituted. Thirdly, the tool spiral path base of the three-dimensional surface is assembled into a virtual orthogonal three-rod machine tool with some auxiliary links and a new virtual one-degree of freedom mechanism is created. Finally, by analyzing reversing motion, a reasonable input rotation function is determined, and the kinematic curves of the three rods and the feeding process are simulated and analyzed.     

冠型齿坯锻造过程的数值模拟

应用刚塑性有限元法数值模拟锻造加工过程，并以冠型齿坯为例进行模拟分析，结果表明数值模拟能为选择工艺参数、模具设计提供许多有益的信息，是设计模具的有力手段；同时还表明冠型齿坯的锻造分镦粗、预锻、终锻三工步，其中以预锻模的设计最为灵活、重要，合理的设计各工步是保证最终获得合格产品的保证。     

The Impact of a Partially Molten YSZ Particle

In plasma and high velocity oxy-fuel spraying, a certain portion of the injected powder is often not fully molten upon impact onto a substrate. We present numerical results of the impact of a partially molten yttria-stabilized zirconia particle, a material widely used as a thermal barrier. We consider an idealized scenario: the axisymmetric impact of a particle with a solid core, examining only the flow of the molten material around the core. The numerical method is based on the immersed boundary method for treating the interaction of solids and fluid within a computational domain. We present the results of a set of simulations, varying the particle and solid core diameters, and the impact velocity. When the core diameter is small relative to the particle, the impact behavior is similar to the impact of a fully molten droplet. When the core is larger, it promotes considerable splashing, which is undesirable.