机身装配工人肌肉骨骼损伤调查和人机工效负荷水平研究

本研究的目标是描述西南地区机身装配线上工人的肌肉骨骼系统疾患的状况;评估机身装配线上的人机工效负荷水平。采用了纵向回顾和横向观察的研究方法,借助标准的北欧MSDs问卷和人机负荷水平快速暴露（QEC）观察工具,采用SPSS19.0处理数据,p<0.05以判断显著性水平。61个样本中,过去的12个月里,10人中有9人至少有一个身体部位有过MSDs症状;QEC结果显示颈椎（16.86±1.328）和手腕（42.58±4.931）是人机工效负荷非常高的部位。研究结果显示,安全的工作姿势和技巧培训、工作组织需要加强,工作环境布局和辅助劳动工具设计可以有效降低人机工效负荷水平。     

人工物料搬运作业肌肉疲劳动态发展研究

目的为减少人工物料搬运作业肌肉疲劳累积、降低MSDs风险,设计人工物料搬运实验,研究行走速度为1km/h、2km/h条件下作业人员肌肉疲劳发展情况。方法招募5名大学生参与实验,从主观和客观两个方面测量作业过程中肌肉疲劳数据——肌力(MS)、最大耐受时间(MET)和主观肌肉疲劳评分(RPE),分析作业过程肌肉疲劳发展特征,并构建MET预测模型。结果负荷对肌力以及肌力降幅影响不显著,但显著影响MET;行走速度对肌力降幅影响不显著,但显著影响肌力和MET。     

基于OWAS的人工破拆作业肌肉疲劳骨骼风险分析

目的 探究不良工作姿势对人工破拆作业人员肌肉骨骼损伤(MSDs,Musculoskeletal Disorders)的影响.方法 本文采用工作姿势分析系统(OWAS,Ovako Working Posture Analysis System)对作业人员的不良姿势出现的百分比和负重情况进行分析与评估.结果 数据显示作业人...     

风荷载下单层柱面网壳的动力稳定

以一单层柱面网壳为例,利用Budiansky-Roth准则研究空间结构在风荷载下的动力稳定性。介绍了Budiansky-Roth准则,通过风洞试验获得单层柱面网壳上的风荷载并研究其动力稳定性,讨论了初始几何缺陷、风向角和风压系数的影响,并将动力失稳分析结果与我国规范和阵风响应因子法（GRF法）计算动力响应导致结构破坏的方法作了比较。研究结果表明,空间结构进行风荷载下的稳定性设计时有必要研究其在风荷载下的动力稳定性。     

船用柴油发电机组非线性隔振系统动态特性分析

以计算多体动力学理论为指导,以船舶柴油发电机组的抗冲击研究为背景,建立了柴油发电机组的多体动力学以及线性隔振系统模型,并通过实验验证模型的正确性;在此基础上构建机组的非线性隔振系统,并对机组额定工况以及冲击条件下隔振系统的动态特性进行分析,结果表明非线性隔振系统较线性隔振系统有良好的隔振效果。文中的建模与求解方法较数学建模与求解简单易行,对隔振器选型与安装、非线性隔振器的参数化设计与优化、其它船用机械的抗冲击研究奠定了一定的工程应用基础。     

基于支持向量机的柴油机噪声品质客观评价参量权重分析

以一台6缸柴油机为研究对象,采用分类对偶比较法对采集到的目标机型在多工况下的辐射噪声品质进行主观评价试验,同时选取并计算了可以描述其声音特性的5个客观评价参量,引入支持向量机,建立了柴油机噪声品质预测模型,并借助噪声测试样本验证预测模型的准确性。然后以柴油机噪声品质预测模型为基础构建起客观评价参量的权重分析模型,分析柴油机噪声品质客观评价参量对主观评价结果的影响权重。研究表明,柴油机噪声品质主要受响度和粗糙度两个客观评价参量的影响。此次分析对高声品质柴油机的设计起到了指导性的作用。     

制造误差影响齿轮副啮合的接触有限元分析方法

制造误差是影响齿轮副啮合的重要因素,研究其作用机理对齿轮的减振设计具有重要意义。首先基于几种典型制造误差的结构形式提出了一般的精确建模方法,以一对渐开线直齿轮为例,利用接触有限元分析方法对啮合过程进行仿真,发现理想齿轮副和含误差齿轮副啮合过程中的角速度、动态接触力特性表现出显著差异。然后进行单项误差影响齿轮振动的机理研究,分别以齿廓误差和齿距误差为对象,利用傅里叶变换量化分析了不同加工公差等级下的单项制造误差对齿轮副动态传递误差、角加速度特性的影响规律。研究表明:所提出的建模方法可以模拟任意形式的微小量级的制造误差,并体现在接触有限元分析中。不但能够用于精细化研究制造误差对齿轮副啮合过程的影响,还可以通过量化各项啮合特性分析单项误差影响齿轮振动的作用机理,并指导齿轮的减振设计和精度设计等。     

基于遗传支持向量机的柴油机辐射噪声品质预测技术

以一台六缸车用柴油机为例,研究了其在变负荷及转速工况下表面辐射噪声品质情况,为进一步提高整机声品质,开展柴油机结构声学设计奠定了理论基础。研究国内外车用柴油机客观评价特征,并选取响度、尖锐度、粗糙度和波动度来描述辐射噪声的客观评价特征;针对柴油机噪声特点,采用成对比较法开展以专业陪审团人群为目标的满意度评价研究;应用遗传算法优化支持向量机（GA-SVM）建立起该车用柴油机声品质预测模型,并与BP神经网络预测模型进行比较,结果表明,基于遗传算法优化的支持向量机辐射噪声品质预测模型较神经网络建模预测精度更高,能够更准确地反映客观评价参量与主观满意度之间的非线性映射关系。     

模拟凿破作业肌肉疲劳恢复的试验研究

目的为了解人工凿破作业肌肉疲劳恢复发展特征,避免造成累积性伤害(CTD),降低肌肉骨骼疾患(MSDs)风险。方法文中设计并组织模拟凿破作业肌肉疲劳恢复试验,招募20名男性大学生参与试验,测量凿破作业过程和恢复5 min过程中握力、主观疲劳感(RPE)的变化值,探讨钻孔高度对肌肉疲劳恢复发展的影响。结果恢复期握力随时间显著递增,RPE则随时间显著下降;试验结束时握力、RPE与恢复期不同时点均存在显著差异;钻孔高度对试验过程中肌肉疲劳和恢复发展均没有显著影响。结论经5 min恢复期后肌肉疲劳显著恢复,构建的肌肉疲劳恢复预测模型的预测结果与实际情况吻合较好,适用于凿破作业肌肉疲劳恢复的预测和评估。     

含裂纹离心压缩机叶轮结构的振动局部化

针对离心压缩机在复杂运行工况下的失谐与裂纹问题,研究裂纹与失谐对叶轮结构振动响应和振动局部化的影响规律。首先,采用三维有限元模型建立具有复杂几何形状的叶轮结构的定量分析模型,并通过在裂纹界面上定义接触的形式模拟裂纹的呼吸效应。其次,通过采用混合界面模态综合法对系统自由度进行缩减,以解决了采用三维有限元模型分析非线性系统动态响应时所存在的计算量大和收敛困难的问题。最终,采用Monte Carlo方法对含裂纹的失谐叶轮结构进行统计分析,研究随机失谐和裂纹故障对叶轮结构振动局部化的影响规律。结果表明裂纹和失谐都会对结构的振动响应产生显著的影响,并会导致振动能量的集中和振动局部化现象。     

Collaborative agents for production planning and scheduling (CAPPS): a challenge to develop a new software system architecture for manufacturing management in Japan

Considering the frequent changes in market needs, real-time production management will produce huge additional value for manufacturers. As scheduling of shop floor operations is a local and partial decision in enterprises, the distributed local scheduling problems should be integrated at the enterprise level. Since decisions at the shop floor are very valuable, the next generation of production management will be performed as a decentralized system. This paper proposes architecture for scheduling-intensive production management. In the architecture, referred to as collaborative agents for production planning and scheduling, system integration is only achieved by communication among agents, i.e. a system is composed of loose connections between agents. As an implementation method, the paper introduces a standard specification for the communications among agents. The specification is recommended by PSLX, the Japan-based consortium for production planning and scheduling. The paper also shows some emerging business models on scheduling-intensive production management.     

Work-related injuries and musculoskeletal disorders among factory workers in a major city of China

This study describes the frequency of occurrence of work-related injuries and musculoskeletal disorders (MSDs) among factory workers in Shenzhen, China, and examines the determinants of injuries and MSDs.     

Ergonomic mismatch between students anthropometry and university classroom furniture

University students spend most of their time in classrooms, mostly in a sitting position. Prolonged sitting on ill-fitted furniture and the resulting bad posture is making students suffer from different musculoskeletal disorders (MSDs). This study evaluates the potential mismatch between furniture dimensions and anthropometric measurements. To determine potential mismatch, 13 anthropometric measurements of 550 students and 11 dimensions of two types of classroom furniture (mounted-desktop and chair-with-table) were measured and then compared. Additionally, chi-square test was performed to compare the relation between anthropometry and relevant furniture dimensions. Results showed that a significant number of mismatches emerged between anthropometric measurements and furniture dimensions. For both types of furniture, seat height was too high and seat depth was too deep. Moreover, for mounted desktop, desk height is almost appropriate for all students whereas for chair and table, it was too high for the males. These circumstances may lead to increase discomfort and increase MSDs problems among all students. It can be concluded that the dimensions of both types of classroom furniture were not appropriate for users according to anthropometric measurements. This analysis recommends the measurements of furniture dimensions based on participants’ anthropometric measurements to avoid or minimise discomfort and MSDs problems.     

The use of discretion on the shop floor

An analysis hag been made of the amount of discretion available to the employees on the shop floor of a medium batch production factory. Four different levels of discretion wore identified. The amount of discretion which employees possess was shown to be closely related to the satisfaction of the employees' personal economic objectives.     

A comparison of sequencing rules in static and dynamic hybrid flow systems

It is well known that efficient scheduling of jobs is essential for improving the economics of production in manufacturing organizations. As a result, extensive research has been conducted on scheduling, especially in job shop and flow shop settings. In contrast, little research has been done on hybrid flow systems, even though they are found in many industries, including beer processing, glass container production, pertroleum refining, plastic-coated cable production, and fertilizer production. Furthermore, the few studies that have dealt with hybrid systems have been limited by the assumptions made about their operating environments. Therefore, we conducted a study that extends the previous work on hybrid systems in two significant ways: (1) it included financially oriented scheduling rules and a new, related performance measure; and (2) the new rules were compared with the existing ones in a large simulation experiment under both static and dynamic (generally encountered in practice) hybrid flow shop environments. To date such comparisons have been made only under static environments. The results show that the relative performances of the scheduling rules differ as the assumptions regarding the operating environment are changed.     

On the who-rule in Dual Resource Constrained (DRC) manufacturing systems

The who-rule is a labour allocation rule used in labour and machine-limited dual resource constrained (DRC) systems. A who-rule selects one worker out of several workers to be transferred to a work centre. By means of a practical instance, the paper shows that the who-rule plays a role in the daily practice of worker assignment. Previous simulation studies, however, either have not mentioned the who-rule or have treated it as a fixed factor. The present study will explore the need of including the who-rule in simulation studies. It will describe in detail at what decision moments the who-rule needs to be applied in simulation. Further, it will explore the flow time effects of applying different who-rules in several DRC systems where labour flexibility is limited and workers differ with respect to task proficiencies, the number of skills they possess and the loads of work centres for which they are responsible. As with other labour allocation rules, the impact of the who-rule depends on the specific DRC shop modelled. The paper will show that the average labour utilization, and the types and extent of worker differences, determine the impact of the who-rule on shop performance.     

A lever concept integrated with simple rules for flow shop scheduling

The development of more efficient and better performing priority dispatching rules (PDRs) for production scheduling is relevant to modern flow shop scheduling practice because they are simple, easy to apply and have low computational complexity, especially for large-scale problems. While the current research trend in scheduling is towards finding superior solutions through meta-heuristics, they are computationally expensive and many meta-heuristics also use PDRs to generate starting points. In this paper, we analyse the properties of flow shop scheduling problems to minimise maximum completion time, and generate a new dominance rule that is complementary to Szwarc’s rule. These dominance rules indicate that a weighting factor should be included in sequencing to account for the possibility that a single job’s processing time can generate idle time repeatedly within a flow line. Two new PDRs with a leveraged weighting factor are proposed to minimise makespan and average completion time. Computational results on Taillard’s benchmark problems and on historical operating room data show that the proposed PDRs perform much better than established PDRs without an increase in computational complexity.     

A model to examine the effect of loading conditions on scheduling rules in a job shop environment

Although a great deal of research has been carried out in the field of job scheduling this has generally been directed towards examining the benefits of particular rules and presenting improved algorithms. This paper examines how real job shop problems can be modelled and available scheduling rules examined for particular capacity loading conditions. A model of a medium-size production job shop is developed and it is shown that, for their particular shop layout and job mix, the performance and ranking of particular rules with respect to certain criteria, change with shop conditions. The model developed can easily be applied to a wide range of job shop situations and once performance charts have been produced for those scheduling rules available, they can be used to aid the existing scheduling system whether manual or computer based.     

Reducing feedback requirements of workload control

The workload control concept is known as a robust shop floor control concept. It is especially suited for the dynamic environment of small- and medium-sized enterprises (SMEs) within the make-to-order sector. Before orders are released to the shop floor, they are collected in an ‘order pool’. To make the release decision, information regarding the actual situation on the shop floor is required. Within SMEs, this information is often incomplete, incorrect or delayed. However, the workload control approaches discussed in the literature assume precise feedback information. The paper discusses the opportunities for information feedback from the shop floor for centralized order release within SMEs and analyses the information requirements of workload control approaches. These approaches are adapted based on more realistic assumptions regarding information supply within SMEs. The different approaches are compared and assessed by a simulation study. Results show that additional investments in more accurate information supply lead to decreasing marginal improvements in overall shop performance. Additionally, they indicate that the choice of the right workload control approach might have important effects on performance.     

A simulation based approach to analyse the effects of job release on the performance of a multi-stage job-shop with processing flexibility

Workload control concepts are advocated as one of the new production planning and control methods. In its elaborated form, workload control includes three major decision levels: job entry, job release and priority dispatching. In each decision level, several decision points which have significant impact on the effectiveness of the production planning and control are defined (i.e., acceptance/rejection, due date assignment, etc.). Workload control systems should consider all of these decision points simultaneously in order to improve the effectiveness of production planning and control. In addition to these decision levels, flexibility of the shop can also be included as the fourth decision level which allows the shop capacity to be adjusted as new orders enter the system and as they are released to the shop floor. In this study, simulation models which enable the effect of each decision level within a workload control concept to be explored are developed and tested. The results reveal that simultaneous consideration of decision levels is critical and can improve the effectiveness of production planning and control.