责任感和建设性

今年5月底，我参加了在沈阳和大连召开的“百万吨乙烯装置配套重大装备技术交流会”，此次技术交流会是为落实国家发改委关于积极推进百万吨级乙烯建设工程装备国产化的要求，进一步做好国产化技术论证工作，由机械工业联合会和中石油、中石化共同研究召开的。国家主管部门、制造商和应用行业客户三方专家会聚一堂，会议上中石化、中石油有关部门和专家介绍了百万吨乙烯装置的工艺和技术要求，     

回顾和展望

我们怀着十分喜悦的心情，迎来了1995年。“本刊”编辑部全体同志向多年来关心爱护、支持本刊的广大读者和作者，向刊物编委会全体委员，刊物董事会全体成员致以亲切的问候。刚刚过去的1994年，我们国家在深化改革和宏观调控两个方面均取得了很大的成绩。液压气动密封行业广大职工团结奋斗，努力探索，克服种种困难，积极稳步地推动着行业朝着预期的目标发展，取得了不少成绩，这些成绩表现为：企业的自我开发和成套能力有了长足进步，行业的装备及制造水平有了明显改善；产品质量稳步提高；生产销售同步增长，各项经济指标稳步上升；对外合…     

纠正和预防措施论谈

在贯彻ISO9001标准时，纠正和预防措施这一要素是一项难度大、要求高且极其重要的管理活动，不论是认证机构的现场审核还是认证后的复审，有关专家都强调指出了“纠正和预防措施”基本没有达到预期效果，因为企业的多数人都往往习惯于纠正，就事论事地解决问题，而不是在纠正措施上下功夫，甚至没有制定出纠正和预防措施。笔者根据贯标认证工作中的实践，意在本文中阐述一下正确实施纠正和预防措施的重要意义及应注意的事项，阐明应如何正确实施纠正和预防措施控制程序，使纠正和预防措施在企业贯标认证过程中起到应有的作用，以便持续改…     

倒角和锥度自动标注在UG中的研究和实现

在机械制图中，通常需要进行大量的倒角和锥度的标注工作。但UG中并没有专门的倒角和锥度的标注工具，用户需要进行繁琐的标注操作。针对这一问题，利用UG的二次开发工具，进行了相应的程序开发，简化了倒角和锥度的标注，取得了良好的效果。     

高速加工和动平衡

1前言 高速加工，由于采用很高的切削速度和进给速度，从而大大缩短加工时间以及获得很高的加工精度和表面质量，并导致节省加工工序，简化生产工艺流程和减少生产设备，因而高速加工具有显著的技术经济效益。自20世纪80年代中期兴起高速加工以来，在至今的约20年中获得了迅速发展，并相继在航空、航天和汽车工业以及模具制造业等领域里得到了广泛应用．     

栀子和水栀子品质的定性分析和探讨

本文采用分光光度法对栀子和水栀子的品质进行了初步的定性分析。通过对各地产的新鲜样品进行分析表明，栀子和水栀子均有相同的特征吸收光谱。此外，无论青果、成熟鲜果或陈旧果实均在２３８ｎｍ波长附近处有特征吸收，可作为栀子和水栀子定性鉴别的要点。     

吸附器的制造和检验

我公司为临泉化工股份有限公司和安徽昊源集团公司生产的15台吸附器，是脱碳系统中的关键设备，为Ⅰ类压力容器。操作压力为正压与负压频繁交替作用，介质特性为易燃、易爆，属于易疲劳破坏设备，对制造和检验提出了较高的要求。为此，我们制定了严格的施工工艺和严密的检验方法，确保产品能够按时交货，保证了产品质量符合图样和用户的要求。     

网络连着你和我

《机械工人》的读者朋友们，本刊的每期杂志中都有大量的行业信息和专业技术论文，更有一些为您精心安排的深度报道，我们很希望能及时得到大家的回应和反馈。现在好了，我们为您开通了网络论坛和网上评论，网刊互动不但延伸了杂志的品牌影响力，也可以及时方便快捷地和网友沟通，我们感觉到和大家大心灵上是相通的。     

互感分压器和互感分流器的误差和实际应用

本文介绍互感分压器和分流器的结构、误差和实际应用。二者的结构和误差计算公式相同，因而有的仪器可分别作为分压器和分流器使有。实际应用主要有：检定电流和电压互感器，检定电阻分流器和分压器，进行阻抗和导纳比较以及检定互感器校验仪整检装置和互感器校验仪的同相盘。文中对检定结果的误差计算作了分析和推导。     

企业信息化进程和发展趋势

本文阐明了企业信息化的含义和 内容，论述了其由来，演变和发展趋势，还论述了企业信息化过程的长期性，艰巨性和紧迫性。     

累积和控制图与传统控制图同时监控过程均值

质量管理中广泛使用的休哈特控制图，对异常原因引起的均值大的偏移比较有效，但对于小的持续的偏移却不敏感；累积和控制图对小的持续性偏移有效。但对瞬间偏移不敏感。在过程质量的监控中，同时采用这两种控制图来进行监控，包容了两种控制图的优点，弥补了彼此的不足。在一定条件下，提出了一种新的控制图——累积和和休哈特混合控制图，效果明显优于累积和控制图或休哈特控制图。     

Control charts for monitoring the mean vector and the covariance matrix of bivariate processes

In this article, we propose new control charts for monitoring the mean vector and the covariance matrix of bivariate processes. The traditional tools used for this purpose are the T ² and the |S| charts. However, these charts have two drawbacks: (1) the T ² and the |S| statistics are not easy to compute, and (2) after a signal, they do not distinguish the variable affected by the assignable cause. As an alternative to (1), we propose the MVMAX chart, which only requires the computation of sample means and sample variances. As an alternative to (2), we propose the joint use of two charts based on the non-central chi-square statistic (NCS statistic), named as the NCS charts. Once the NCS charts signal, the user can immediately identify the out-of-control variable. In general, the synthetic MVMAX chart is faster than the NCS charts and the joint T ² and |S| charts in signaling processes disturbances.     

多变异源过程控制与指数加权移动平均控制图的应用研究

改进休哈特控制图能够解决多变异源过程控制虚发警报错误过高的问题,但是对均值偏移的检出力过低。本文研究的目的是将指数加权移动平均(EWMA)控制图用于多变异源过程控制,提高控制图对均值偏移的检出力。通过对多个变异源的方差分析,基于对部分方差估计,给出指数加权移动平均控制图在多变异源过程控制的应用方法。通过计算指数加权移动平均控制图的平均运行长度,并与改进的休哈特控制图作比较,证明指数加权移动平均控制图在检测多变异源过程均值偏移时检出力有较大提高,应用实例的结果表明当偏移量小于1σ时,检出力能提高10倍以上。     

A comparison study of three non-parametric control charts to detect shift in location parameters

Control charts are used as a statistical process control or SPC tool to identify the presence of assignable cause of variation in the process. Despite immense use and acceptability of parametric control charts, non-parametric control charts are an emerging area of recent development in the theory of SPC. The main advantage of non-parametric control charts is that they do not require any knowledge about the underlying distribution of the variable. In this work, we have summarized the different non-parametric control charts for controlling location from a literature survey, viz. control charts based on the sign test, control charts based on the Hodges–Lehmann estimator and control charts based on the Mann–Whitney statistic and compared their efficiency to detect the shift in location while in out of the control state under different situations and identified the best method under the prevailing situation.     

Synthesis of double-crank (drag-link) driven mechanisms with adjustable motion and dwell time ratios

The double-crank mechanism is a versatile nonuniform input source for other mechanism loops generating nonuniform and intermittent motions. This article offers a minimum-maximum velocity ratio chart for the determination of the positions of the double-crank mechanisms for minimum velocity ratios. A set of input-output displacement charts are given for the selection of dynamically efficient double-crank driving loops of multiloop mechanisms, in which the order of the instantaneous dwells can be increased, advance-to-return time ratios and dwell-to-motion time ratios can be generated as specified or be made changeable when desired. These design charts broaden the design opportunities with the double-crank mechanism. Design applications showing the use of these design charts are included in several design examples. It is also shown that these design charts become invaluable for the synthesis of indexing mechanisms free of infinite jerk. Double-crank mechanism is an approximate-constant-velocity coupling mechanism for parallel shafts permitting adjustable offset. Some of these charts are also for the selection of such double-crank mechanisms.     

Control charts for individual observations of a bivariate Poisson process

In this paper, three single-control charts are proposed to monitor individual observations of a bivariate Poisson process. The specified false-alarm risk, their control limits, and ARLs were determined to compare their performances for different types and sizes of shifts. In most of the cases, the single charts presented better performance rather than two separate control charts (one for each quality characteristic). A numerical example illustrates the proposed control charts.     

装配工艺文件的自动生成

装配工艺文件是指导装配人员进行现场装配操作的重要依据 ,对产品的最终质量有着非常重要的影响 ,故制作准确详尽的装配工艺文件是装配工艺规划中的一个极其关键的环节。手工制作装配工艺文件的效率低、工作强度大 ,已不能满足广大企业的需求。装配工艺规划后处理器 (PostAssemblyProcessPlanningManager,PAPPM)是一个基于Pro/Engineer软件平台的功能模块 ,它借助计算机辅助手段 ,根据CAD和CAAPP(ComputerAidedAssemblyPro cessPlanning)的设计结果 ,以人机交互为辅、计算机推理为主的方式生成装配工艺文件。本文结合对PAPPM的介绍 ,探讨了装配工艺文件自动生成中的关键技术。     

Optimal control policy for dependent process steps with over-adjusted means and variances

Over-adjustment to processes may result in shifts in process mean and variance, ultimately affecting the quality of products. An economic adjustment model is developed for the joint design of X̄-S² control charts and ē-S_e² cause-selecting control charts to control both means and variances of two dependent process steps using the Markov chain approach. The objective is to determine the optimal control policy of the proposed control charts, which effectively detect and distinguish the shifts of means and variances on the dependent process steps and minimize the total quality control cost. Application of the proposed control charts is illustrated through a numerical example.     

4M12氧压机吸排气压力对排气量和功耗影响的研究

采用计算机程序优化计算压缩机在变工况运行时的参数 ,得出了 4M 12氧压机Ⅰ级吸气压力和末级排气压力与排气量及功耗的关系曲线 ,这对氧压机优化运行与节能有着重要的指导意义。     

A neural network-based control scheme for monitoring start-up processes and short runs

Traditional control charts are commonly used as a monitoring tool in long-run processes. However, such control charts, due to the need for phase I analysis, are not suitable for start-up processes or short runs. Q control charts have been developed to help monitor start-up processes and short runs. In this article, a back propagation network is proposed for detecting a mean shift in start-up processes and short runs. In-control run length distribution of the control scheme is estimated using simulation study to provide information about the possibility of a false alarm within a specified number of observations. Performance of the proposed control scheme is assessed using different performance measures. It is shown numerically that the proposed control scheme outperforms the CUSUM of Q charts in detecting small to moderate mean shifts.