Recent research trend of economic-lot scheduling problems

Purpose - This research note aims to present a summary of research concerning economic-lot scheduling problem (ELSP). Design/methodology/approach - The paper's approach is to review over 100 selected studies published in the last 15 years (1997-2012), which are then grouped under different research themes. Findings - Five research themes are identified and insights for future studies are reported at the end of this paper. Research limitations/implications - The motivation of preparing this research note is to summarize key research studies in this field since 1997, when the ELSP problems have been verified as NP-hard. Originality/value - ELSP is an important scheduling problem that has been studied since the 1950s. Because of its complexity in delivering a feasible analytical closed form solution, many studies in the last two decades employed heuristic algorithms in order to come up with good and acceptable solutions. As a consequence, the solution approaches are quite diversified. The major contribution of this paper is to provide researchers who are interested in this area with a quick reference guide on the reviewed studies. © Emerald Group Publishing Limited.

Non-stationary stochastic inventory lot-sizing with emission and service level constraints in a carbon cap-and-trade system

Firms worldwide are taking major initiatives to reduce the carbon footprint of their supply chains in response to the growing governmental and consumer pressures. In real life, these supply chains face stochastic and non-stationary demand but most of the studies on inventory lot-sizing problem with emission concerns consider deterministic demand. In this paper, we study the inventory lot-sizing problem under non-stationary stochastic demand condition with emission and cycle service level constraints considering carbon cap-and-trade regulatory mechanism. Using a mixed integer linear programming model, this paper aims to investigate the effects of emission parameters, product- and system-related features on the supply chain performance through extensive computational experiments to cover general type business settings and not a specific scenario. Results show that cycle service level and demand coefficient of variation have significant impacts on total cost and emission irrespective of level of demand variability while the impact of product's demand pattern is significant only at lower level of demand variability. Finally, results also show that increasing value of carbon price reduces total cost, total emission and total inventory and the scope of emission reduction by increasing carbon price is greater at higher levels of cycle service level and demand coefficient of variation. The analysis of results helps supply chain managers to take right decision in different demand and service level situations.

Design of a genetic algorithm for bi-objective flow shop scheduling problems with re-entrant jobs

This paper presents a simulated genetic algorithm (GA) model of scheduling the flow shop problem with re-entrant jobs. The objective of this research is to minimize the weighted tardiness and makespan. The proposed model considers that the jobs with non-identical due dates are processed on the machines in the same order. Furthermore, the re-entrant jobs are stochastic as only some jobs are required to reenter to the flow shop. The tardiness weight is adjusted once the jobs reenter to the shop. The performance of the proposed GA model is verified by a number of numerical experiments where the data come from the case company. The results show the proposed method has a higher order satisfaction rate than the current industrial practices.

On plagiarism, patchwriting and the problems of overseas students in British universities

Although according to Angélil-Carter (2002: 2) ‘plagiarism is a modern Western concept which arose with the introduction of copyright laws in the Eighteenth century’, its avoidance is now a basic plank of respectable academic scholarship. Student plagiarism is currently a hot topic, at least for those who teach and study in British and American universities. There are companies selling both off-the-shelf and written-to-order term papers and others, like Turnitin.com, offering an electronic detection service. Recently an Australian Rector was dismissed for persistent plagiarism earlier in his career and most Anglo-American universities have warnings against and definitions of plagiarism on their websites – indeed Pennycook notes that in the mid-90s Stanford University's documents about plagiarism were reproduced by the University of Oregon apparently without attribution, and suggests, whimsically, that there is 'one set of standards for the guardians of truth and knowledge and another for those seeking entry' (1996: 213), (example and quote taken from Pecorari, 2002, p 29).

The unhappy marriage of religion and politics:problems and pitfalls for gender equality

This article explores how religion as a political force shapes and deflects the struggle for gender equality in contexts marked by different histories of nation building and challenges of ethnic diversity, different state–society relations (from the more authoritarian to the more democratic), and different relations between state power and religion (especially in the domain of marriage, family and personal laws). It shows how ‘private’ issues, related to the family, sexuality and reproduction, have become sites of intense public contestation between conservative religious actors wishing to regulate them based on some transcendent moral principle, and feminist and other human rights advocates basing their claims on pluralist and time- and context-specific solutions. Not only are claims of ‘divine truth’ justifying discriminatory practices against women hard to challenge, but the struggle for gender equality is further complicated by the manner in which it is closely tied up with, and inseparable from, struggles for social and economic justice, ethnic/racial recognition, and national self-determination vis-à-vis imperial/global domination.

Teaching about terrorism in the United Kingdom: How it is done and what problems it causes

This article presents some of the findings of research on issues surrounding teaching terrorism and political violence at UK higher education institutions. It reports the results of a survey of UK institutions of higher education on their responses to government and other pressures in relation to terrorism. The data show a minority of universities have developed systems, policies or procedures for ‘preventing violent extremism’, while a significant number have developed close cooperation and collaboration with state counterterrorism policies raising potential issues of academic freedom. This article then examines three high-profile cases – incidents where universities, lecturers and students have come under political and legal pressures over the content of terrorism courses or accusations of ‘radicalisation’ on campus. It suggests that these pressures can be and sometimes are resisted, but that they have on occasion effectively narrowed the scope of academic freedom in practise with the danger that a further chilling effect follows in their wake.

Computer-assisted production scheduling, planning and control in foundries

The present study describes a pragmatic approach to the implementation of production planning and scheduling techniques in foundries of all types and looks at the use of `state-of-the-art' management control and information systems. Following a review of systems for the classification of manufacturing companies, a definitive statement is made which highlights the important differences between foundries (i.e. `component makers') and other manufacturing companies (i.e. `component buyers'). An investigation of the manual procedures which are used to plan and control the manufacture of components reveals the inherent problems facing foundry production management staff, which suggests the unsuitability of many manufacturing techniques which have been applied to general engineering companies. From the literature it was discovered that computer-assisted systems are required which are primarily `information-based' rather than `decision based', whilst the availability of low-cost computers and `packaged-software' has enabled foundries to `get their feet wet' without the financial penalties which characterized many of the early attempts at computer-assistance (i.e. pre-1980). Moreover, no evidence of a single methodology for foundry scheduling emerged from the review. A philosophy for the development of a CAPM system is presented, which details the essential information requirements and puts forward proposals for the subsequent interactions between types of information and the sub-system of CAPM which they support. The work developed was oriented specifically at the functions of production planning and scheduling and introduces the concept of `manual interaction' for effective scheduling. The techniques developed were designed to use the information which is readily available in foundries and were found to be practically successful following the implementation of the techniques into a wide variety of foundries. The limitations of the techniques developed are subsequently discussed within the wider issues which form a CAPM system, prior to a presentation of the conclusions which can be drawn from the study.

An approach to the development of expert systems within production planning and control

The thesis presents an account of an attempt to utilize expert systems within the domain of production planning and control. The use of expert systems was proposed due to the problematical nature of a particular function within British Steel Strip Products' Operations Department: the function of Order Allocation, allocating customer orders to a production week and site. Approaches to tackling problems within production planning and control are reviewed, as are the general capabilities of expert systems. The conclusions drawn are that the domain of production planning and control contains both `soft' and `hard' problems, and that while expert systems appear to be a useful technology for this domain, this usefulness has by no means yet been demonstrated. Also, it is argued that the main stream methodology for developing expert systems is unsuited for the domain. A problem-driven approach is developed and used to tackle the Order Allocation function. The resulting system, UAAMS, contained two expert components. One of these, the scheduling procedure was not fully implemented due to inadequate software. The second expert component, the product routing procedure, was untroubled by such difficulties, though it was unusable on its own; thus a second system was developed. This system, MICRO-X10, duplicated the function of X10, a complex database query routine used daily by Order Allocation. A prototype version of MICRO-X10 proved too slow to be useful but allowed implementation and maintenance issues to be analysed. In conclusion, the usefulness of the problem-driven approach to expert systems development within production planning and control is demonstrated but restrictions imposed by current expert system software are highlighted in that the abilities of such software to cope with `hard' scheduling constructs and also the slow processing speeds of such software can restrict the current usefulness of expert systems within production planning and control.

Strategizing and organizing in pluralistic contexts

In this article, the concept of pluralism is used to expose variations in the relationship between organizing and strategizing and the consequences of these variations for managerial practice. Pluralistic contexts are those that are shaped by the divergent goals and interests of different groups inside and outside the organization. Internally, these divergent interests result in multiple organizing processes, while the interests of external stakeholders lead to multiple strategic goals and objectives. Despite the Fact that innate pluralism and the consequent complexity of strategizing and organizing processes are experienced by many organizations in the 21st century, pluralism has been inadequately examined in organisation studies and virtually ignored in the strategy literature. Having defined pluralism and explained its implications for strategizing and organizing practices and processes within organizations, three relevant questions are posed for investigating the nature of organizing and strategizing in pluralistic contexts. Case examples from the public sector, professional services and regulated industries are utilized to provide insights into these questions, and derive a framework that enables the drivers and potential problems of the interdependence between strategizing and organizing to be better understood. Practical implications for managing this interdependence are drawn.

Lexical learning and dysgraphia in a group of adults with developmental dyslexia

We investigated the ability to learn new words in a group of 22 adults with developmental dyslexia/dysgraphia and the relationship between their learning and spelling problems. We identified a deficit that affected the ability to learn both spoken and written new words (lexical learning deficit). There were no comparable problems in learning other kinds of representations (lexical/semantic and visual) and the deficit could not be explained in terms of more traditional phonological deficits associated with dyslexia (phonological awareness, phonological STM). Written new word learning accounted for further variance in the severity of the dysgraphia after phonological abilities had been partialled out. We suggest that lexical learning may be an independent ability needed to create lexical/formal representations from a series of independent units. Theoretical and clinical implications are discussed. © 2005 Psychology Press Ltd.

Minimum description length, regularisation and multi-modal data

Conventional feed forward Neural Networks have used the sum-of-squares cost function for training. A new cost function is presented here with a description length interpretation based on Rissanen's Minimum Description Length principle. It is a heuristic that has a rough interpretation as the number of data points fit by the model. Not concerned with finding optimal descriptions, the cost function prefers to form minimum descriptions in a naive way for computational convenience. The cost function is called the Naive Description Length cost function. Finding minimum description models will be shown to be closely related to the identification of clusters in the data. As a consequence the minimum of this cost function approximates the most probable mode of the data rather than the sum-of-squares cost function that approximates the mean. The new cost function is shown to provide information about the structure of the data. This is done by inspecting the dependence of the error to the amount of regularisation. This structure provides a method of selecting regularisation parameters as an alternative or supplement to Bayesian methods. The new cost function is tested on a number of multi-valued problems such as a simple inverse kinematics problem. It is also tested on a number of classification and regression problems. The mode-seeking property of this cost function is shown to improve prediction in time series problems. Description length principles are used in a similar fashion to derive a regulariser to control network complexity.

Modelling and control of a hybrid stepping motor

The integration of a microprocessor and a medium power stepper motor in one control system brings together two quite different disciplines. Various methods of interfacing are examined and the problems involved in both hardware and software manipulation are investigated. Microprocessor open-loop control of the stepper motor is considered. The possible advantages of microprocessor closed-loop control are examined and the development of a system is detailed. The system uses position feedback to initiate each motor step. Results of the dynamic response of the system are presented and its performance discussed. Applications of the static torque characteristic of the stepper motor are considered followed by a review of methods of predicting the characteristic. This shows that accurate results are possible only when the effects of magnetic saturation are avoided or when the machine is available for magnetic circuit tests to be carried out. A new method of predicting the static torque characteristic is explained in detail. The method described uses the machine geometry and the magnetic characteristics of the iron types used in the machine. From this information the permeance of each iron component of the machine is calculated and by using the equivalent magnetic circuit of the machine, the total torque produced is predicted. It is shown how this new method is implemented on a digital computer and how the model may be used to investigate further aspects of the stepper motor in addition to the static torque.