A matrix approach to the representation of tolerance zones and clearances

This paper presents a matrix approach coupled to the notion of constraints for the representation of tolerance zones within CAD/CAM (computer-aided design and manufacture) systems. The proposed theory, reproduces themeasurable ornon-invariant displacements associated with various types of tolerance zone. This is done using the homogeneous transforms commonly associated with robotic modelling.This matrix representation is completed by a set of inequalities defining the bounds of the tolerance zones. Moreover, the generation of the model and its mathematical definition allows for its use in the representation of clearances and for the computation of tolerance transfer. An example illustrates the application of the model to a simplified gear pump mechanism.     

提高弧齿锥齿轮加工质量的工艺措施

分析了“用小齿轮配切成品大齿轮”工艺的可行性和应用情况;介绍了“硬齿面刮削”中比较合理的切削措施;对提高淬硬弧齿锥齿轮的加工质量具有现实意义。     

压力机成本-公差模型及质量损失模型研究

本文以压力机的公差与配合为研究对象,运用数学函数方法,在满足装配目标的情况下,主要研究了指数模型、改进的指数模型、负平方模型、倒数幂指数模型、多项式模型和复合模型的各种形式,以及三种质量损失函数。对压力机尺寸链中各组成环的公差进行合理分配,以达到降低成本之目的。     

A structural modeling on food safety knowledge,attitude, and behaviour among Bum Bum Island community of Semporna,Sabah

The objective of this study was to evaluate the relationship among food safety knowledge, attitude and behavior in Bum Bum Island community, Semporna, Sabah. Proportional stratified sampling method was used in this survey. A total of 250 respondents were selected randomly from ten villages in Bum Bum Island. Face-to-face interview was conducted to complete the questionnaire. In general, respondents exhibited average food safety knowledge level especially in their awareness of personal hygiene and kitchenware hygiene. Food safety attitude of the community was found strongly affected their food safety behavior in positive way, which was proven by the highest standard β among variables tested (β₁ = 0.885, p < 0.05). However, food safety knowledge was negatively affected the food safety behavior of the respondents (β₁ = −0.128, p < 0.05). Our result confirmed that Structural Equation Modeling (SEM) was successfully used to model the relationship among food safety knowledge, attitude and behavior.     

Is more always better? Investigating the task-technology fit theory in an online user context

We used Task-Technology Fit (TTF) theory to examine the drivers and consequences of successful task completion by a user in an online context. The theory suggests that the fit between characteristics of the task and those of the website predicts user performance and behavioral intentions. Our hypotheses were tested using the input of two large scale studies performed in twelve industries and involving 13,135 participants. Results, which were replicated in a proximate culture, lend support to the predictions of Task-Technology Fit theory. The site information quality and ease of use were the only technology factors that significantly drove the users to a successful completion of their information tasks, rather than the site's graphical attractiveness, interactivity, security and privacy factors. The findings further suggested that focusing on the enhancement of site characteristics that have low fit with the task is not effective as it resulted in slowing the successful completion of the online task.     

二次函数拟合在工程技术经济领域中的应用

本文通过作者在工程技术经济领域应用二次函数拟合方法解决实际问题的经验总结，就该方法在工程技术经济领域中的应用提出了一些个人的观点和体会。     

Statistical Control of a Gaussian Process

The optimal statistical control of a simple production process which has only two underlying states, in control and out of control, is studied. The produced items are assumed to have a measurable quality characteristic which has a normal distribution with known variance. When the process leaves control the mean of thii distribution shifts from μ₀ to μ₁, both assumed known. Costs are associated with the quality of an item and with repairing the process which returns it to a state of control. Other than immediately after repair, the process state is assumed unknown. This report gives a statistical control rule which, based on the quality history of produced items, tells when to repair the machine. The rule given minimizes the time average of the total cost of repairs plus quality.     

椭圆-矩形的静动态不适合边界算法

在求解Packing问题、机器人路径规划、虚拟装配、碰撞检测等常用到椭圆-矩形的不干涉算法。针对椭圆和矩形分别在静止、运动状态下的不干涉问题,该文在Adamowicz&Albano的NFP基础上,给出了椭圆-矩形的静、动态不适合边界(NoFitBoundary,NFB)的定义,用图形变换方法证明了静态不适合边界是由4条线段和4段椭圆弧组成的对称曲八边形,给出了对称曲八边形顶点计算公式,提出了椭圆-矩形的静、动态不干涉算法。该算法简单且具有一定的应用价值。     

薄壁轴瓦过盈配合可靠性分析及改进

本文讨论了薄壁轴瓦在装配和半圆周长检测状态下的应力分析,给出了合理的计算方法,并进行了试验研究。研究表明,试验结果与所给计算方法的结果相当吻合;轴瓦与座孔表面的摩擦系数将影响其过盈配合的可靠性。     

激光辐照对长波HgCdTe光导探测器电学参数的影响

对长波HgCdTe光导探测器进行了低于其永久损伤阈值的变功率激光辐照 ,测量辐照前后器件的电阻 温度特性 ,用电阻 温度特性研究材料参数的方法对实验结果进行拟合 ,结果表明辐照后HgCdTe探测器件的组分变大 ,并由此计算得到探测器性能突变后 ,器件的电子迁移率与电子浓度均有一定程度减小。认为这可能是由于激光辐照的热效应使N型HgCdTe光导器件的表面及体内均产生的一定的变化所致