Linking hybrid systems to ACD models: a case study in the fibre-glass industry

This paper is aimed at formalising and testing a model for hybrid systems where the interactions between the continuous process parts and the manufacturing sub-systems are given by minor stoppages. The proposed approach consists in representing the effects of the continuous process dynamics on discrete manufacturing sub-systems by means of autoregressive conditional duration (ACD) models originally conceived to treat high-frequency and irregularly spaced financial transaction data. The model has been applied to a real-life furnace and spooling-bushing department system of a fibre-glass production plant. Results conclude that the ACD-based model proved useful for representing the occurrence of fibre-glass breakage on the spooling-bushing machines and, in more general terms, that the proposed methodology could be really suitable for the logical modelling of the hybrid production systems where the relationships between the continuous and the discrete parts are given by the occurrence of minor stoppages.     

The Impact of Imperfect Processes on Production Run Times

This paper investigates the interaction between the economics of production and imperfections in the production process. Specifically, this paper is the first to devise a model in an attempt to provide managers with guidelines to choose the appropriate production run times to buffer against both the production of defective items and stoppages occurring due to machine breakdowns. In addition to providing several structural properties of the model, we show that a manager will always incur a cost penalty when (s)he uses the results of two oft‐cited models‐the EMQ (Economic Order/Manufacturing Quantity) and the NR‐E (No‐Resumption, Exponential machine breakdown)‐to determine production run times.     

THE VALIDITY OF THE INDEPENDENT INCREMENTS ASSUMPTION FOR PRODUCTION: AN EMPIRICAL STUDY OF AN AUTOMOTIVE ASSEMBLY PLANT

In assembly plants, random line stoppages cause production variability. For analytic tractability and data availability, researchers commonly assume that the production process possesses the independent increments property (necessary for a process to be Poisson). If the production process has independent increments, then the production in any interval is independent of the production in any other nonoverlapping interval. This property means, for one thing, that the current period's production is never influenced by previous production periods. Intuition, however, suggests that current production could be correlated to past production-violating this assumption of independence. If production problems persist from one period to the next, then one would expect the production in adjacent time periods to be correlated. Although the independent increments property is oflen assumed, its validity has not been demonstrated in practice. We analyze data from an automotive assembly plant to assess the validity of the independent increments assumption for its production.     

A solution approach to a synchronisation problem in a JIT production system

Delivering of orders on time, increasing productivity and reducing costs are all challenges that companies have to cope with on a regular basis. Making production lines compatible solves these problems and means a reduction in line stoppages and cycle time. In continuous production systems in which production is carried out in lots, the main ways to ensure an uninterrupted and smooth flow and have a high production rate, are line balancing and synchronising work stations. In this paper, a line stoppage and productivity problem at an automotive factory (Toyota Turkey plant, Sakarya city) is solved by root-cause analysis. Cycle time and in-process inventory inconsistency causes the problem between paint and assembly lines. Different solutions are researched and the most appropriate one is selected and implemented.     

搞好精益生产 提高设备利用率

随着市场竞争的日趋激烈,如何提高设备利用率,增加生产产出,如何提高员工的劳动效率成了每个加工制造业必须研究的课题。本文把工业工程和精益生产的技术和方法运用到芯片封装测试上产线中,对其关键工序,工人动作,工序流程等进行研究,有效的减少设备的等待时间。对于影响生产效率的关键因素——人机比进行研究,有效的减少不必要的劳动力成本。     

The effects of state-dependent human behavior on the design of a serial line

Most research on line design assumes that human operators perform independently from the status of the line. Recent empirical evidence is contradictory. Humans are likely to change their working speed if they might otherwise cause idle time (Schultz et al., Manage Sci 44(12):1595–1607, 1998). This peculiarity of worker behavior is observed in a variety of settings but little is still known about optimal line design that accounts for this more realistic modeling of worker behavior. Therefore, we analyze work allocation in a serial line with limited buffer capacity and adaptive human behavior. An extensive simulation study reveals that optimal work allocation in state-dependent models is different from classical state-independent models. A bowl-shaped work allocation might be suboptimal and design guidelines are more complicated. Depending on the extent of human reactions, a bowl-shaped, balanced, or reversed-bowl work allocation can be preferable.     

Scheduling in an assembly-type production chain with batch transfer

This paper addresses a three-machine assembly-type flowshop scheduling problem, which frequently arises from manufacturing process management as well as from supply chain management. Machines one and two are arranged in parallel for producing component parts individually, and machine three is an assembly line arranged as the second stage of a flowshop for processing the component parts in batches. Whenever a batch is formed on the second-stage machine, a constant setup time is required. The objective is to minimize the makespan. In this study we establish the strong NP-hardness of the problem for the case where all the jobs have the same processing time on the second-stage machine. We then explore a useful property, based upon which a special case can be optimally solved in polynomial time. We also study several heuristic algorithms to generate quality approximate solutions for the general problem. Computational experiments are conducted to evaluate the effectiveness of the algorithms.     

Job route selection model for workload balancing between workstations in flexible flow line

A flexible flow line (FFL) consists of several groups of identical machines. All work-orders flow along the same path through successive machine groups. Thus, the balancing of workloads between machine groups in order to maximize total productivity is emphasized. On the other hand, many different types of work-orders, in varying batch or lot sizes, are produced simultaneously. The mix of work-orders, their lot sizes, and the sequence in which they are produced affect the workload. However, the work-orders and their lot sizes are pre-fixed and cannot be changed. Because of these reasons, an optimal route selection model has been developed using heuristic search and a min-max algorithm for balancing the workload between machine groups in the FFL.     

Speed in the Internationalization Process of the Firm

While firm internationalization processes have been understood as being dynamic, the dimension of speed has rarely been the main focus of research efforts, which, until a decade ago, focused principally on explaining sequences of entry modes and choices of markets. The emergence of the study of international entrepreneurship has enhanced the role of speed, although this has usually been measured in terms of the time lag between a firm's foundation and its initial international action, with little attempt at defining and explaining the speed of the process once it is under way. This study reviews the concept of speed from an internationalization perspective, describes the multidimensional nature of the concept and sets out the different aspects that link timescales with the types of changes – continuous and discontinuous – that take place during internationalizing processes. The paper concludes with a research agenda as a guide for future work on considering the role of speed in the internationalization process.     

Scheduling algorithms for computer-aided line balancing in printed circuit board assembly

Generalized flexible flow line (GFFL) is a scheduling environment comprising several machine banks which the products visit in the same order but can skip some machine banks. The type of machines in a bank can differ but they are suitable for performing the same manufacturing tasks. To change one product to another demands a set-up operation of the machine. This paper describes several scheduling algorithms for the GFFL problem. The overall structure of these algorithms is similar, consisting of machine allocation and sequencing phases. The algorithms have been integrated into an interactive production scheduling system for electronics assembly. Sample cases are used to illustrate the operation of the system in practice.     

“These Power Lines Make Me Ill”: A Typology of Residents’ Health Responses to a New High‐Voltage Power Line

Little attention has been devoted to the potential diversity in residents’ health responses when exposed to an uncertain environmental health risk. The present study explores whether subgroups of residents respond differently to a new high‐voltage power line (HVPL) being put into operation. We used a quasi‐experimental prospective field study design with two pretests during the construction of a new HVPL, and two posttests after it was put into operation. Residents living nearby (0–300 m, n = 229) filled out questionnaires about their health and their perception of the environment. We applied latent class growth models to investigate heterogeneity in the belief that health complaints were caused by a power line. Classes were compared on a wide range of variables relating to negative‐oriented personality traits, perceived physical and mental health, and perceptions of the environment. We identified five distinct classes of residents, of which the largest (49%) could be described as emotionally stable and healthy with weak responses to the introduction of a new power line. A considerable minority (9%) responded more strongly to the new line being activated. Residents in this class had heard more about the health effects of power lines beforehand, were more aware of the activation of the new line, and reported a decrease in perceived health afterwards. Based on our findings we can conclude that there is a considerable heterogeneity in health responses to a new HVPL. Health risk perceptions appear to play an important role in this typology, which has implications for risk management.     

印刷电路板组装生产线调度优化问题建模

印刷电路板(printed circuit board,PCB)组装是电子制造的基础,其核心生产过程包括电子元器件的表面贴装。分别基于典型的表面贴装机(CM402)、以及由高速贴片机(CM402)与多功能贴片机(DT401)组成的流水线的机械特征与生产特性,对上述组装机及组装流水线的调度问题建立优化模型,为进一步的算法开发以及电子制造生产调度的智能化提供理论支持。     

An Optimal Model for Cell Formation Decisions

This study develops an approach to cell formation decisions for cellular manufacturing layouts in group technology settings. An optimal 0–1 integer programming model is used to provide an analysis for determining which machines and parts should be assigned to cells in cellular manufacturing layouts. This approach minimizes the cost of manufacturing exceptional parts outside the cellular system, subject to machine capacity constraints. Part–machine matrices are partitioned into disconnected cells and use far fewer 0–1 variables than earlier approaches. Formulation of the model is described with a numerical example and computer solutions to realistic problems are obtained. The characteristics of computer run times, model performance, and applications of the model are discussed.     

Communication in Nuclear Emergency Preparedness: A Closer Look at Information Reception

Preparedness of the general population plays a key role in the effective implementation of protective actions in case of a nuclear emergency (e.g., evacuation or intake of iodine tablets). In this context, a good communication of emergency management actors with the public along the entire cycle of preparedness–response–recovery is of paramount importance. This article aims at providing a better understanding of the way people process communicated messages and the factors that may influence how they do this. In particular, it investigates information reception as part of the information processing in precrisis communication. As a case study, the precrisis communication context was chosen, as it has been tackled to a lesser extent in the literature. The empirical data used for this study originated from a large‐scale opinion survey in Belgium. One topic in this survey addressed the information campaign for the distribution of iodine tablets, in the context of preparedness for nuclear emergencies. The findings of this study demonstrate that systematic predictors have a stronger influence on information reception, as compared to heuristic predictors. The latter are only to a minor extent involved in the reception of emergency preparedness information. The hypothesized pattern—that more specific knowledge about the field relates to a higher reception of information—was confirmed for precrisis communication. Contrary to expectations, results showed that people with a high perception of radiation risks were less attentive to information about protective actions. People with little confidence in authorities were also more likely to have a low reception of information.     

In search of optimal management of the purchasing–marketing interface for new product development

Abstract

Growing dependence on suppliers for production and innovation, together with increasing consumer demands, has prompted recent discussions of the importance of purchasing–marketing functional integration. However, empirical studies are needed to understand how to manage this interface within a new product development (NPD) context. This study, grounded in information processing theory, proposes a new model to classify integrating mechanisms as either information-sharing forums or optimizers. This model further postulates the greater capacity of optimizer mechanisms for improving NPD commercial and financial performance, as well as speed. The empirical results, obtained from a sample of 141 firms, show that forums only improve NPD speed, whereas optimizer mechanisms evoke better commercial and financial performance. This study therefore highlights the potential of different integrating mechanisms and contributes to the on-going debate about the very concept of functional integration itself.     

Reliability: Its implications in production systems design

Research on production systems design has in recent years tended to concentrate on ‘software’ factors such as organisational aspects, work design, and the planning of the production operations. In contrast, relatively little attention has been paid to maximising the contributions made by fixed assets, particularly machines and equipment. However, as the cost of unproductive machine time has increased, reliability, particularly of machine tools, has become ever more important. Reliability theory and research has traditionally been based in the main on electrical and electronic equipment whereas mechanical devices, especially machine tools, have not received sufficiently objective treatment. A recently completed research project has considered the reliability of machine tools by taking sample surveys of purchasers, maintainers and manufacturers. Breakdown data were also collected from a number of engineering companies and analysed using both manual and computer techniques. Results obtained have provided an indication of those factors most likely to influence reliability and which in turn could lead to improved design and selection of machine tool systems. Statistical analysis of long-term field data has revealed patterns of trends of failure which could help in the design of more meaningful maintenance schemes.     

The Structure of Wages in the Netherlands, 1986–98

Abstract. For many OECD countries an increase in wage inequality has been documented since the early 1980s. This is often attributed to a general rise in the demand for skilled workers resulting from recent technological change. Using the Organization for Strategic Labour Market Research (OSA) Labour Supply data, this paper studies the wage structure in the Netherlands over the period 1986–98 and demonstrates that wage inequality did not increase to any significant extent in the Netherlands. Using the accounting framework proposed by Juhn et al. (Journal of Political Economy 101: 410–442, 1993), it is shown that the relatively stable wage structure until at least the late 1990s can be attributed mainly to returns to observable components, such as education and experience, while residual wage inequality is found to be of minor importance in explaining the Dutch wage structure. These estimates suggest that the demand for skill in the Netherlands is likely not to have been rising to the extent it did in many other countries over this period.     

IMES: A System for Identifying and Evaluating Computer Models for Exposure Assessment2

Although IMES is apparently a marriage of independently developed modules, the blend is nearly seamless-there are only minor differences in “feel” between the three modules. IMES is well organized and easy to use. There are help screens at every stage in each module. Selection is efficient-queries rarely take more than a few seconds on a 386 machine before a report can be generated. There are a few pitfalls in model selection which are difficult to avoid. Improper classification is one of them. For example, IMES lists MINTEQ as a multimedia model. It would be more appropriate from this reviewer's perspective to classify MINTEQ as a geo-chemical model (for which this version of IMES has no classification category.)One minor concern is that in two modules (Selection and Validation)IMES queries the operator “Do you really want to exit?” or “Exit?” when one simply wants to go back one level in the screening process. It would be less disconcerting to be consistently presented (as is done in the Uncertainty module)with a pop-up menu selection like “Do you want to return to the previous screen?” IMES was an ambitious undertaking that resulted in a useful and important contribution to Exposure Assessment Model community.     

An approachto the machine layout problem in a cellular manufacturing environment

The model of the machine layout problem MLP in a cellular manufacturing environment attains additional dimensions as it should satisfy the qualitative interconnections between the machines and the location restrictions of an existing factory environment. A new MLP model based on merging pre-emptive goal programming and simulated annealing has been developed for machine layout in cells. This model seeks to find feasible solutions by addressing practical issues of implementation as well as reducing the total travel distances for parts between machines. The new model can also be applied to facility layout problems FLP . The computational work is demonstrated by applying the model to problems of both quantitative and qualitative types, and has produced encouraging results. This model is particularly attractive for layout problems with realistic goals and constraints. To show the performance of the model in handling real-world problems, a practical example has been introduced and solved using the proposed model.     

Multi-stage scheduling for banks by mathematical programming

Despite moves toward electronic funds transfer systems, the United States banking industry must continue to cope with the paper processing requirements associated with a payments system still heavily reliant upon checks. Through the development of MICR (magnetic ink character recognition), computers have been utilized to sort documents and post customer accounts. However, a labor intensive key encoding function is required to prepare documents for processing. An attempt to eliminate the labor intensity is the recent development of optical scanning capture equipment which ‘reads’ printed or hand-written documents and inscribes them with MICR characters. However, the utilization of optical scanning technology requires the scheduling and coordination of five processing activities. A mathematical programming model has been developed which minimizes the combination of payroll and float costs while recognizing machine capacity constraints in the scheduling of optical capture systems. The formulation was specifically designed to respond to the bank check processing scheduling problem. However, with minor modifications, the model is directly transferable to any multi-echelon processing system where penalties are incurred when the units of output fail to meet prespecified deadlines.