用于皮带及链传动的一种恒张力张紧装置

指出了皮带及链传动现有张紧方法的缺点，设计了一种结构简单、工作可靠的用于皮带及链传动的恒张力控制装置，该装置能自动调整压在皮带或链上的力，在很大挠角范围内保持其张力基本恒定。     

Cable-direct-driven-robot (CDDR) with a 3-link passive serial support

Cable-direct-driven-robots (CDDRs) provided with a passive serial support represent an interesting and rising evolution of planar cable robots. The paper is devoted to present and analyze a novel CDDR robot. The robot consists in a fully actuated CDDR supported against loading normal to the motion plane with a 3-link passive planar serial manipulator. This hybrid structure combines positive features of both parallel and serial architectures, and prevents out-of-plane movements without the necessity for the robot to be supported on the motion plane. The adoption of a 3-link serial manipulator ensures a greater workspace area compared with similar structures that adopt a smaller number of links, and improves specific characteristics of their dynamics. Nevertheless undesired oscillations may occur since the serial manipulator is underconstrained. For this reason damping elements are inserted in the structure. Simulation examples are presented to demonstrate the novel CDDR concept and its dynamics. In addition, a strategy to select proper values of damping coefficients is presented.     

拉矫机破鳞原理的研究

分析总结了拉矫机破鳞理论,研究了拉矫机工艺参数与破鳞效果之间的关系,提出了酸洗拉矫机工艺参数优化的准则,同时就拉矫在破鳞方面的发展提出建议。     

变质工艺对ZL102铝硅合金表面张力的影响

利用回归正交设计法设计了变质处理影响ZL102铝硅合金表面张力的试验方案，利用自行研制的表面张力快速测定仪炉前测定ZL102铝硅合金液的表面张力，建立了变质工艺影响ZL102铝硅合金表面张力的数学模型。结果表明，变质剂加入量对ZL102铝硅合金表面张力影响显著，变质时间次之，变质温度的影响不明显，交互相和二次相的影响可以忽略。进一步试验表明，利用该数学模型求得的表面张力值与实际测量值偏差较小。     

冷喂料胶管生产线的自动控制系统

The current status of colloidal tube production in China and the technique process of the tube prod uction are described in brief． The funct ions and the implementation of the control system, the mathematical model of the PID operation and the block diagram of program are introduced in detail．     

Shoulder and neck complaints in customer relations: individual risk factors and perceived exposures at work

Perceived psychosocial and biomechanical exposures, individual factors and pain in the shoulder and neck were recorded in two groups of female service workers (healthcare and shopping centre workers). The jobs investigated were characterized by ‘much’ direct human relations, ‘little’ sitting and ‘much’ standing, and were light work by physiological or biomechanical criteria but potentially psychosocially demanding. A screening survey (n = 400 females) was the basis for the selected sample (n = 66 females), which was the object of the main investigation of this study. Reliability of the questionnaires was tested in a separate group of female healthcare workers (n = 29). Heart rate recordings through the work day estimated workload. There was a high prevalence of shoulder and neck pain (>50%) for both work groups. In the two populations it proved difficult to explain shoulder and neck pain by reported physical and psychosocial exposures or individual factors, except by the variable ‘perceived general tension’, which clearly differentiated workers with and without pain. The findings in this study indicated, first, that perceived general tension might be an independent risk factor for muscle pain and, second, that this might be related to personality factors. However, this putative relationship must be verified in a longitudinal study. As no variable describing exposures in the working environment was associated with shoulder and neck pain, the question is posed whether such complaints can be considered work-related. Alternatively, the variables used to describe mechanical and psychosocial exposures in this study may have low specificity in characterizing work-related risk factors for service workers with customer relations.     

Reliability analysis of TLP tethers under impulsive loading

In the present study, reliability assessment of Tension Leg Platform (TLP) tethers against maximum tension (i.e. tension exceeding yield) has been carried out under combined action of extreme wave and impulsive forces. For this purpose, a nonlinear dynamic analysis of TLP has been carried out in time domain. A limit state function for maximum tension (i.e. tension exceeding yield) has been derived employing Von-Mises theory of failure. Using this derived limit state function and responses obtained after dynamic analysis under sinusoidal, half-triangular and triangular impulsive forces, reliability assessment of the TLP tethers has been carried out. Design point, important for probabilistic design of tethers, has been located on the failure surface after solving a constrained optimization problem. To study the influence of various random variables on tether reliability, sensitivity analysis has been carried out. Effects of angle of impact; effect of variable submergence; and effect of material yield strength on tether reliability have also been studied on parametric basis. Effect of uncertainty on overall tether reliability has also been discussed to show the importance of quality control in the various design parameters.     

ASTM金属材料拉伸试验方法介绍

介绍了ASTM E8(E8M)标准中的金属材料屈服强度、屈服点伸长率、均匀伸长率、抗拉强度、伸长率和断面收缩率的测量方法，并与我国相应的标准试验方法进行了比较。     

引进冷连轧机厚控系统分析及改进方案

武钢、宝钢两套冷连轧机代表了冷连轧技术发展水平 ,用连轧张力理论对这两套冷连轧机的厚控系统作了深入的分析、讨论 ,给出了其中最主要厚控环节 -连轧AGC和张力AGC的数学模型。对宝钢厚控系统提出了改进方案 ,利用DAGC可以简便地实现穿带、正常轧制、抛尾 ,而不用分别采用APC、恒压力、压力AGC三种控制方式 ,并且DAGC实现恒压力控制有更高的稳定性。