Minimizing total weighted completion time in a proportionate flow shop

We study the special case of the m machine flow shop problem in which the processing time of each operation of job j is equal to pj; this variant of the flow shop problem is known as the proportionate flow shop problem. We show that for any number of machines and for any regular performance criterion we can restrict our search for an optimal schedule to permutation schedules. Moreover, we show that the problem of minimizing total weighted completion time is solvable in O(n2) time. © 1998 John Wiley & Sons, Ltd.

Proportionate flow shop with controllable processing times

This paper considers a special class of flow-shop problems, known as the proportionate flow shop. In such a shop, each job flows through the machines in the same order and has equal processing times on the machines. The processing times of different jobs may be different. It is assumed that all operations of a job may be compressed by the same amount which will incur an additional cost. The objective is to minimize the makespan of the schedule together with a compression cost function which is non-decreasing with respect to the amount of compression. For a bicriterion problem of minimizing the makespan and a linear cost function, an O(n log n) algorithm is developed to construct the Pareto optimal set. For a single criterion problem, an O(n2) algorithm is developed to minimize the sum of the makespan and compression cost. Copyright © 1999 John Wiley & Sons, Ltd.

Scheduling batches with sequential job processing for two-machine flow and open shops

In this paper, we study a problem of scheduling and batching on two machines in a flow-shop and open-shop environment. Each machine processes operations in batches, and the processing time of a batch is the sum of the processing times of the operations in that batch. A setup time, which depends only on the machine, is required before a batch is processed on a machine, and all jobs in a batch remain at the machine until the entire batch is processed. The aim is to make batching and sequencing decisions, which specify a partition of the jobs into batches on each machine, and a processing order of the batches on each machine, respectively, so that the makespan is minimized. The flow-shop problem is shown to be strongly NP-hard. We demonstrate that there is an optimal solution with the same batches on the two machines; we refer to these as consistent batches. A heuristic is developed that selects the best schedule among several with one, two, or three consistent batches, and is shown to have a worst-case performance ratio of 4/3. For the open-shop, we show that the problem is NP-hard in the ordinary sense. By proving the existence of an optimal solution with one, two or three consistent batches, a close relationship is established with the problem of scheduling two or three identical parallel machines to minimize the makespan. This allows a pseudo-polynomial algorithm to be derived, and various heuristic methods to be suggested.

Two-stage open shop scheduling with a bottleneck machine

It is known that for the open shop scheduling problem to minimize the makespan there exists no polynomial-time heuristic algorithm that guarantees a worst-case performance ratio better than 5/4, unless P6≠NP. However, this result holds only if the instance of the problem contains jobs consisting of at least three operations. This paper considers the open shop scheduling problem, provided that each job consists of at most two operations, one of which is to be processed on one of the m⩾2 machines, while the other operation must be performed on the bottleneck machine, the same for all jobs. For this NP-hard problem we present a heuristic algorithm and show that its worst-case performance ratio is 5/4.

Scheduling three-operation jobs in a two-machine flow shop to minimize makespan

This paper considers a variant of the classical problem of minimizing makespan in a two-machine flow shop. In this variant, each job has three operations, where the first operation must be performed on the first machine, the second operation can be performed on either machine but cannot be preempted, and the third operation must be performed on the second machine. The NP-hard nature of the problem motivates the design and analysis of approximation algorithms. It is shown that a schedule in which the operations are sequenced arbitrarily, but without inserted machine idle time, has a worst-case performance ratio of 2. Also, an algorithm that constructs four schedules and selects the best is shown to have a worst-case performance ratio of 3/2. A polynomial time approximation scheme (PTAS) is also presented.

An improved approximation algorithm for the two-machine open shop scheduling problem with family setup times

We consider the problem of scheduling families of jobs in a two-machine open shop so as to minimize the makespan. The jobs of each family can be partitioned into batches and a family setup time on each machine is required before the first job is processed, and when a machine switches from processing a job of some family to a job of another family. For this NP-hard problem the literature contains (5/4)-approximation algorithms that cannot be improved on using the class of group technology algorithms in which each family is kept as a single batch. We demonstrate that there is no advantage in splitting a family more than once. We present an algorithm that splits one family at most once on a machine and delivers a worst-case performance ratio of 6/5.

Approximation results for flow shop scheduling problems with machine availability constraints

This paper considers two-machine flow shop scheduling problems with machine availability constraints. When the processing of a job is interrupted by an unavailability period of a machine, we consider both the resumable scenario in which the processing can be resumed when the machine next becomes available, and the semi-resumable scenario in which some portion of the processing is repeated but the job is otherwise resumable. For the problem with several non-availability intervals on the first machine under the resumable scenario, we present a fast (3/2)-approximation algorithm. For the problem with one non-availability interval under the semi-resumable scenario, a polynomial-time approximation scheme is developed.

A new Nawaz–Enscore–Ham-based heuristic for permutation flow-shop problem with bicriteria of makespan and machine idle-time

A new heuristic based on Nawaz–Enscore–Ham (NEH) algorithm is proposed for solving permutation flowshop scheduling problem in this paper. A new priority rule is proposed by accounting for the average, mean absolute deviation, skewness and kurtosis, in order to fully describe the distribution style of processing times. A new tie-breaking rule is also introduced for achieving effective job insertion for the objective of minimizing both makespan and machine idle-time. Statistical tests illustrate better solution quality of the proposed algorithm, comparing to existing benchmark heuristics.

Shop-floor narratives : how six workers and a researcher describe learning activities

I am a part-time graduate student who works in industry. This study is my narrative about how six workers and I describe shop-floor learning activities, that is learning activities that occur where work is done, outside a classroom. Because this study is narrative inquiry, you wilileam about me, the narrator, more than you would in a more conventional study. This is a common approach in narrative inquiry and it is important because my intentions shape the way that I tell these six workers' stories. I developed a typology of learning activities by synthesizing various theoretical frameworks. This typology categorizes shop-floor learning activities into five types: onthe- job training, participative learning, educational advertising, incidental learning, and self-directed learning. Although learning can occur in each of these activities in isolation, it is often comprised of a mixture of these activities. The literature review contains a number of cases that have been developed from situations described in the literature. These cases are here to make the similarities and differences between the types of learning activities that they represent more understandable to the reader and to ground the typology in practice as well as in theory. The findings are presented as reader's theatre, a dramatic presentation of these workers' narratives. The workers tell us that learning involves "being shown," and if this is not done properly they "learn the hard way." I found that many of their best case lean1ing activities involved on-the-job training, participative learning, incidentalleaming, and self-directed learning. Worst case examples were typically lacking in properly designed and delivered participative learning activities and to a lesser degree lacking carefully planned and delivered on-the-job training activities. Included are two reflective chapters that describe two cases: Learning "Engels" (English), and Learning to Write. In these chapters you will read about how I came to see that my own shop-floor learning-learning to write this thesis-could be enhanced through participative learning activities. I came to see my thesis supervisor as not only my instructor who directed and judged my learning activities, but also as a more experienced researcher who was there to participate in this process with me and to help me begin to enter the research community. Shop-floor learning involves learners and educators participating in multistranded learning activities, which require an organizational factor of careful planning and delivery. As with learning activities, which can be multi-stranded, so too, there can be multiple orientations to learning on the shop floor. In our stories, you will see that these six workers and I didn't exhibit just one orientation to learning in our stories. Our stories demonstrate that we could be behaviorist and cognitivist and humanist and social learners and constructivist in our orientation to learning. Our stories show that learning is complex and involves multiple strands, orientations, and factors. Our stories show that learning narratives capture the essence of learning-the learners, the educators, the learning activities, the organizational factors, and the learning orientations. Learning narratives can help learners and educators make sense of shop-floor learning.

Engaging environments: Tacit knowledge sharing on the shop floor

Purpose: The purpose of this paper is to identify factors that facilitate tacit knowledge sharing in unstructured work environments, such as those found in automated production lines. Design/methodology/approach: The study is based on a qualitative approach, and it draws data from a four-month field study at a blown-molded glass factory. Data collection techniques included interviews, informal conversations and on-site observations, and data were interpreted using content analysis. Findings: The results indicated that sharing of tacit knowledge is facilitated by an engaging environment. An engaging environment is supported by shared language and knowledge, which are developed through intense communication and a strong sense of collegiality and a social climate that is dominated by openness and trust. Other factors that contribute to the creation of an engaging environment include managerial efforts to provide appropriate work conditions and to communicate company goals, and HRM practices such as the provision of formal training, on-the-job training and incentives. Practical implications: This paper clarifies the scope of managerial actions that impact knowledge creation and sharing among blue-collar workers. Originality/value: Despite the acknowledgement of the importance of blue-collar workers' knowledge, both the knowledge management and operations management literatures have devoted limited attention to it. Studies related to knowledge management in unstructured working environments are also not abundant. © Emerald Group Publishing Limited.

A new evolutionary clustering search for a no-wait flow shop problem with set-up times

This paper addresses the m-machine no-wait flow shop problem where the set-up time of a job is separated from its processing time. The performance measure considered is the total flowtime. A new hybrid metaheuristic Genetic Algorithm-Cluster Search is proposed to solve the scheduling problem. The performance of the proposed method is evaluated and the results are compared with the best method reported in the literature. Experimental tests show superiority of the new method for the test problems set, regarding the solution quality. (c) 2012 Elsevier Ltd. All rights reserved.

Preliminary job descriptions for the domestic & personal service industry.

"Published by the Minnesota State Department of Education and the Division of Standards and Research of the United States Employment Service as a report on official projects 5196 ... 5201, [4155 and 4184] conducted under the auspices of the Works Progress Administration."

Approaches to issues of job regulation. A study at branch level in a white collar, public sector trade union. Available in 2 volumes.

This study examines the internal dynamics of white collar trade union branches in the public sector. The effects of a number of internal and external factors on branch patterns of action are evaluated. For the purposes of the study branch action is taken to be the approach to issues of job regulation, as expressed along the five dimensions of dependence on the outside trade union, focus in issues adopted, initiation of issues, intensity of action in issue pursuit and representativeness. The setting chosen for the study is four branches drawn from the same geographical area of the National and Local Government Officers Association. Branches were selected to give a variety in industry settings while controlling for the potentially influential variables of branch size, density of trade union membership and possession of exclusive representational rights in the employing organisation. Identical methods of data collection were used for each branch. The principal findings of the study are that the framework of national agreements and industry collective bargaining structures are strongly related to the industrial relations climate in the employing organisation and the structures of representation within the branch. Where agreements and collective bargaining structures formally restrict branch job regulation roles, there is a degree of devolution of bargaining authority from branch level negotiators to autonomous shop stewards at workplace level. In these circumstances industrial relations climate is characterised by a degree of informality in relationships between management and trade union activists. In turn, industrial relations climate and representative structures together with actor attitudes, have strong effects on all dimensions of approach to issues of job regulation.

New measures of job control, cognitive demand and production responsibility

Recent research has highlighted several job characteristics salient to employee well-being and behavior for which there are no adequate generally applicable measures. These include timing and method control, monitoring and problem-solving demand, and production responsibility. In this article, an attempt to develop measures of these constructs provided encouraging results. Confirmatory factor analyses applied to data from 2 samples of shop-floor employees showed a consistent fit to a common 5-factor measurement model. Scales corresponding to each of the dimensions showed satisfactory internal and test–retest reliabilities. As expected, the scales also discriminated between employees in different jobs and employees working with contrasting technologies.

Professional standards research:job satisfaction and innovation

Job satisfaction is a significant predictor of organisational innovation – especially where employees (including shop-floor workers) experience variety in their jobs and work in a single-status environment. The relationship between job satisfaction and performance has long intrigued work psychologists. The idea that "happy workers are productive workers" underpins many theories of performance, leadership, reward and job design. But contrary to popular belief, the relationship between job satisfaction and performance at individual level has been shown to be relatively weak. Research investigating the link between job satisfaction and creativity (the antecedent to innovation) shows that job dissatisfaction promotes creative outcomes. The logic is that those who are dissatisfied (and have decided to stay with the organisation) are determined to change things and have little to lose in doing so (see JM George & J Zhou, 2002). We were therefore surprised to find in the course of our own research into managerial practices and employee attitudes in manufacturing organisations that job satisfaction was a highly significant predictor of product and technological innovation. These results held even though the research was conducted longitudinally, over two years, while controlling for prior innovation. In other words, job satisfaction was a stronger predictor of innovation than any pre-existing orientation organisations had towards working innovatively. Using prior innovation as a control variable, as well as a longitudinal research design, strengthened our case against the argument that people are satisfied because they belong to a highly innovative organisation. We found that the relationship between job satisfaction and innovation was stronger still where organisations showed that they were committed to promoting job variety, especially at shop-floor level. We developed precise instruments to measure innovation, taking into account the magnitude of the innovation both in terms of the number of people involved in its implementation, and how new and different it was. Using this instrument, we are able to give each organisation in our sample a "score" from one to seven for innovation in areas ranging from administration to production technology. We found that much innovation is incremental, involving relatively minor improvements, rather than major change. To achieve sustained innovation, organisations have to draw on the skills and knowledge of employees at all levels. We also measured job satisfaction at organisational level, constructing a mean "job satisfaction" score for all organisations in our sample, and drawing only on those companies whose employees tended to respond in a similar manner to the questions they were asked. We argue that where most of the workforce experience job satisfaction, employees are more likely to collaborate, to share ideas and aim for high standards because people are keen to sustain their positive feelings. Job variety and single-status arrangements further strengthen the relationship between satisfaction and performance. This makes sense; where employees experience variety, they are exposed to new and different ideas and, provided they feel positive about their jobs, are likely to be willing to try to apply these ideas to improve their jobs. Similarly, staff working in single-status environments where hierarchical barriers are reduced are likely to feel trusted and valued by management and there is evidence (see G Jones & J George, 1998) that people work collaboratively and constructively with those they trust. Our study suggests that there is a strong business case for promoting employee job satisfaction. Managers and HR practitioners need to ensure their strategies and practices support and sustain job satisfaction among their workforces to encourage constructive, collaborative and creative working. It is more important than ever for organisations to respond rapidly to demands of the external environment. This study shows the positive association between organisational-level job satisfaction and innovation. So if a happy workforce is the key to unlocking innovation and organisations want to thrive in the global economy, it is vital that managers and HR practitioners pay close attention to employee perceptions of the work environment. In a world where the most innovative survive it could make all the difference.