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Article
Publication date: 1 August 2002

Edward T. Lee

Line‐oriented two‐dimensional grammars (LOTDGs), region‐oriented two‐dimensional grammars (ROTDGs) and parallel productions are introduced. The relationships between…

Abstract

Line‐oriented two‐dimensional grammars (LOTDGs), region‐oriented two‐dimensional grammars (ROTDGs) and parallel productions are introduced. The relationships between LOTDGs and ROTDGs are stated. Examples of LOTDGS for generating all possible 45° right‐angled triangles, all possible squares, all possible 45° isosceles trapezoids, and all possible 45° parallelograms using parallel productions are presented. A new concise representation of a derivation chain is also introduced and illustrated by examples. LOTDGs and ROTDGs are compared. Generally speaking, LOTDGs require less terminal variables and non‐terminal variables, require less storage space, and require less derivation steps. Seven challenging problems for future research are also included. In addition, parallel production is an effective tool to model parallel computers as well as parallel processing. The results have useful applications in robot vision interpretation, robot pictorial communication, artificial intelligence, visual languages, software engineering, medical expert systems, and fuzzy logic functions.

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Kybernetes, vol. 31 no. 6
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 1 June 1996

Edward T. Lee

Describes intuitively the fact that four types of formal languages can be generated by four types of grammars or can be recognized by four types of automata. Gives the…

Abstract

Describes intuitively the fact that four types of formal languages can be generated by four types of grammars or can be recognized by four types of automata. Gives the relationships between context‐sensitive languages and computer programming languages. Defines and investigates parallel productions, parallel grammars, and context‐free parallel grammars. Shows that context‐sensitive languages exist which can be generated by context‐free parallel grammars. In addition, states the advantages of context‐free parallel grammars. Also shows that context‐free languages (CFL) are a proper subset of context‐free parallel languages (CFPL). Furthermore, CFPL is a more effective tool for modelling computer programming languages than CFL, especially for parallel computer programming languages, for example, the ADA programming language. Also illustrates context‐sensitive property of recognizing hand‐written characters. The results may have useful applications in artificial intelligence, model parallel computer programming languages, software engineering, expert systems and robotics.

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Kybernetes, vol. 25 no. 4
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 14 May 2020

Nouhayla Hafidi, Abdellah El Barkany, Abderrahman EL Mhamedi and Morad Mahmoudi

The purpose of this paper is to consider various possible constraints of the problem of production and maintenance planning control for a multi-machine under…

Abstract

Purpose

The purpose of this paper is to consider various possible constraints of the problem of production and maintenance planning control for a multi-machine under subcontracting constraint, in order to bring the manufacturer industry closer to real mode. In this paper, we present an efficient and feasible optimal solution, by comparing optimization procedures.

Design/methodology/approach

Our manufacturing system is composed of parallel machines producing a single product, to satisfy a random demand under a given service level. In fact, the demand is greater than the total capacity of the set of machines; hence there rises a necessity of subcontracting to complete the missing demand. In addition, we consider that the unit cost of subcontracting is a variable depending on the quantity subcontracted. As a result, we have developed a stochastic optimal control model. Then, to solve the problem we compared three optimization methods: (exact/approximate), the genetic algorithm (GA), the Pattern Search (PS) and finally fmincon. Thus, we validate our approach via a numerical example and a sensitivity analysis.

Findings

This paper defines an internal production plan, a subcontracting plan and an optimal maintenance strategy. The optimal solution presented in this paper significantly improves the ability of the decision maker to consider larger instances of the integrated model. In addition, the decision maker can answer the following question: Which is the most optimal subcontractor to choose?

Practical implications

The approach developed deals with the case of the real-mode manufacturing industry, taking into consideration different constraints and determining decision variables which allow it to expand the profits of the manufacturing industry in different domains such as automotive, aeronautics, textile and pharmacies.

Originality/value

This paper is one of the few documents dealing with the integrated maintenance in subcontracting constraint production which considers the complex aspect of the multi-machine manufacturing industry. We also dealt with the stochastic aspect of demand and failures. Then, we covered the impact of the unit cost variation of subcontracting on the total cost. Finally, we shed light on a comparison between three optimization methods in order to arrive at the most optimal solution.

Details

Journal of Quality in Maintenance Engineering, vol. 27 no. 1
Type: Research Article
ISSN: 1355-2511

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Article
Publication date: 29 July 2014

Daniel Nordigården, Jakob Rehme, Staffan Brege, Daniel Chicksand and Helen Walker

The purpose of this paper is to investigate an underexplored aspect of outsourcing involving a mixed strategy in which parallel production is continued in-house at the…

Abstract

Purpose

The purpose of this paper is to investigate an underexplored aspect of outsourcing involving a mixed strategy in which parallel production is continued in-house at the same time as outsourcing occurs.

Design/methodology/approach

The study applied a multiple case study approach and drew on qualitative data collected through in-depth interviews with wood product manufacturing companies.

Findings

The paper posits that there should be a variety of mixed strategies between the two governance forms of “make” or “buy.” In order to address how companies should consider the extent to which they outsource, the analysis was structured around two ends of a continuum: in-house dominance or outsourcing dominance. With an in-house-dominant strategy, outsourcing complements an organization's own production to optimize capacity utilization and outsource less cost-efficient production, or is used as a tool to learn how to outsource. With an outsourcing-dominant strategy, in-house production helps maintain complementary competencies and avoids lock-in risk.

Research limitations/implications

This paper takes initial steps toward an exploration of different mixed strategies. Additional research is required to understand the costs of different mixed strategies compared with insourcing and outsourcing, and to study parallel production from a supplier viewpoint.

Practical implications

This paper suggests that managers should think twice before rushing to a “me too” outsourcing strategy in which in-house capacities are completely closed. It is important to take a dynamic view of outsourcing that maintains a mixed strategy as an option, particularly in situations that involve an underdeveloped supplier market and/or as a way to develop resources over the long term.

Originality/value

The concept of combining both “make” and “buy” is not new. However, little if any research has focussed explicitly on exploring the variety of different types of mixed strategies that exist on the continuum between insourcing and outsourcing.

Details

International Journal of Operations & Production Management, vol. 34 no. 8
Type: Research Article
ISSN: 0144-3577

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Article
Publication date: 1 July 1992

Kajsa Ellegärd, Dan Jonsson, Tomas Engström, Mats I. Johansson, Lars Medbo and Bertil Johansson

Presents some theoretical principles and empirical evidencerelating to the new Swedish production systems for final assembly ofmotor vehicles. Contends that in these…

Abstract

Presents some theoretical principles and empirical evidence relating to the new Swedish production systems for final assembly of motor vehicles. Contends that in these production systems it is possible simultaneously to enhance efficiency and quality of working life. Briefly sketches three production forms as they apply to the final assembly of automobiles and discusses the societal environments in which these different forms of production have evolved. Focuses on Volvo′s Swedish Uddevalla plant as one of the main examples so far of a reflective production system for final assembly of automobiles. Amplifies the analysis of different production flow patterns for final assembly and in particular addresses the issue of semi‐parallel mechanistic production flow and parallel organic production flow as alternatives to serial flow on a conventional line assembly.

Details

International Journal of Operations & Production Management, vol. 12 no. 7/8
Type: Research Article
ISSN: 0144-3577

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Article
Publication date: 1 February 2006

S. Rajakumar, V.P. Arunachalam and V. Selladurai

To propose a methodology based on genetic algorithm (GA) to solve the parallel machine scheduling problems with precedence constraints.

Abstract

Purpose

To propose a methodology based on genetic algorithm (GA) to solve the parallel machine scheduling problems with precedence constraints.

Design/methodology/approach

Workflow balancing helps to remove bottlenecks present in a shop floor yielding faster movements of components or jobs. Multiple machines are used in parallel for processing the jobs to meet the demand. In parallel machine scheduling with precedence constraints, there are m machines to which n jobs are assigned using suitable scheduling algorithms. Workflow of a machine is the sum of processing time of all jobs assigned. All the preceding jobs are allocated first to satisfy the constraints. GA is developed to solve parallel machine scheduling problems with precedence constraints based on the objective of workflow balancing. The GA was coded on IBM/PC compatible system in the C++ language for simulation to a standard manufacturing environment.

Findings

The relative percentage of imbalance (RPI) in workloads among the parallel machines is used to evaluate the performance of the GA developed. The proposed GA produces lesser RPI values against the RANDOM heuristic algorithm for a wider range of jobs and machines.

Research limitations/implications

The performance of GA can be compared with the performance of other meta‐heuristic algorithms to find out the robustness of the results obtained by this research.

Practical implications

The proposed GA also gives better solution for a case study of assembly scheduling.

Originality/value

The allocation of assembly operations to the operators is modeled into a parallel machine scheduling problem with precedence constraints using the objective of minimizing the workflow among the operators.

Details

Journal of Manufacturing Technology Management, vol. 17 no. 2
Type: Research Article
ISSN: 1741-038X

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Article
Publication date: 17 February 2012

Tina Barnes, Stephen Raynor and John Bacchus

The purpose of this paper is to analyse the inconsistent use of terminology in international collaboration, and develop a clearer typology that reflects the commercial and…

Abstract

Purpose

The purpose of this paper is to analyse the inconsistent use of terminology in international collaboration, and develop a clearer typology that reflects the commercial and practical realities of modern business.

Design/methodology/approach

A critique of existing typologies provided the basis for the development of a more practical framework. The new typology was populated with the most prominent collaborative forms to emerge from the analysis of academic research and commercial practice.

Findings

“Structure” and “purpose” emerged as the most logical determinants in differentiating and classifying collaborative forms. Actual commercial ventures mapped on to the new typology demonstrate a good fit between these two considerations and the collaboration strategies adopted.

Originality/value

This work contributes much needed clarity in differentiating and classifying forms of collaboration. The key determinants of structure and purpose reflect more accurately the commercial and practical realities of modern business, and offer practitioners and researchers a logical means of mapping and analyzing collaboration strategy.

Details

Journal of Strategy and Management, vol. 5 no. 1
Type: Research Article
ISSN: 1755-425X

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Article
Publication date: 1 March 1964

MAIDEN FLIGHT OF FIRST PRODUCTION BEAGLE 5.206. On February 28, the first production Beagle B.206 from the assembly line at Rearsby, Leicester, plant of Beagle Aircraft…

Abstract

MAIDEN FLIGHT OF FIRST PRODUCTION BEAGLE 5.206. On February 28, the first production Beagle B.206 from the assembly line at Rearsby, Leicester, plant of Beagle Aircraft Ltd., made its maiden flight. This aircraft is the first of a batch of 22 to be delivered to the Ministry of Aviation and the Royal Air Force for whom it will replace the veteran Anson as a communications aircraft.

Details

Aircraft Engineering and Aerospace Technology, vol. 36 no. 3
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 April 1988

Sam C. Okoroafo

The increased use of government imposed countertrade (mandated countertrade) by developing nations (LDCs) to meet their economic goals has been of particular concern to…

Abstract

The increased use of government imposed countertrade (mandated countertrade) by developing nations (LDCs) to meet their economic goals has been of particular concern to international executives. Frequently, countertrade can be mandated by LDCs on transactions even with their long‐time trading partners. Firms therefore need to anticipate actions of their LDC trading partners to be competitive in the global market place. Inadequate preparation can result in repercussions such as exclusion from specific deals, to exclusion from a particular country‐market.

Details

International Marketing Review, vol. 5 no. 4
Type: Research Article
ISSN: 0265-1335

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Article
Publication date: 22 October 2020

Yongseung Han, Thomas Littlefield and Myeong Hwan Kim

This paper proposes the use of a gauge function as a measure of technical efficiency. The measure of technical inefficiency from a gauge function is desirable as the…

Abstract

Purpose

This paper proposes the use of a gauge function as a measure of technical efficiency. The measure of technical inefficiency from a gauge function is desirable as the estimation of a gauge function is not subject to the endogeneity problem under the behavioral assumption of profit maximization in the competitive market.

Design/methodology/approach

The authors address three important properties of a gauge function, i.e. linear homogeneity, monotonicity and convexity in inputs and outputs, and show how such properties are utilized in its estimation. Then, the authors apply the estimation of a gauge function to US Blacksmiths in 1850 and 1880 to show that a failure to satisfy such properties may lead to an incorrect inference on the technical efficiency.

Findings

The authors find that the Blacksmiths in the 1850s were technically more efficient than the ones in the 1880s, indicating technical regress in Blacksmithing when the properties are satisfied.

Originality/value

This paper introduces a measure of technical inefficiency from a gauge function and shows how to estimate the gauge function parametrically for the measure. The authors show McFadden's gauge function and its properties, which differ from the properties of other distance functions. The authors emphasize linear homogeneity as well as monotonicity and convexity in inputs and outputs, which must be satisfied in the estimation of a gauge function.

Details

Journal of Economic Studies, vol. 48 no. 6
Type: Research Article
ISSN: 0144-3585

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