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This paper aims to propose and formulate a complicated routing/scheduling problem for multiple automated guided vehicles (AGVs) in a manufacturing system.

Considering the due date of AGVs requiring for material handling among shops in a jobshop layout, their earliness and tardiness are significant in satisfying the expected cycle time and from an economic view point. Therefore, the authors propose a mathematical program to minimize the penalized earliness and tardiness for a conflict-free and just-in-time production.

The model considers a new concept of turning point for deadlock resolution. As the mathematical program is difficult to solve with a conventional method, an optimization method in two stages, namely, searching the solution space and finding optimal solutions are proposed. The performance of the proposed mathematical model is tested in a numerical example.

A case study in real industrial environment is conducted. The findings lead the decision-makers to develop a user interface decision support as a simulator to plan the AGVs’ movement through the manufacturing network and help AGVs to prevent deadlock trap or conflicts. The proposed decision support can easily be commercialized.

The benefits of such commercialization are increase in the quality of material handling, improve the delivery time and prevent delays, decrease the cost of traditional handling, capability of computerized planning and control, intelligent tracking and validation experiments in simulation environment.

Deadlock is a rather undesirable phenomenon and must be well solved in flexible manufacturing systems (FMS). This paper aims to propose a general iterative deadlock control method for a class of generalized Petri nets (GPN), namely, G-systems, which can model an FMS with assembly and disassembly operations of multiple resource acquisition. When given an uncontrolled G-system prone to deadlocks, the work focuses on the synthesis of a near-optimal, non-blocking supervisor based on reachability graph (RG) analysis.

The concept of a global idle place (GIP) for an original uncontrolled G-system is presented. To simplify the RG computation of an uncontrolled G-system, a GIP is added temporarily to the net model during monitor computation steps. Starting with one token and then by gradually increasing the number of tokens in the GIP at each iteration step, the related net system is obtained. The minimal-covered-set of all bad markings of the related net system suffering from deadlock can be identified and then removed by additional monitors through an established place-invariant control method. Consequently, all related systems are live, and the GIP is finally removed when the non-blockingness of the controlled system is achieved. Meanwhile, the redundancy of monitors is also checked.

A typical G-system example is provided to demonstrate the applicability and effectiveness of the proposed method. Experiments show that the proposed method is easy to use and provides very high behavioral permissiveness for G-system. Generally, it can achieve an optimal or a near-optimal solution of the non-blocking supervisor.

In this work, the concept of GIP for G-systems is presented for synthesis non-blocking supervisors based on RG analysis. By using GIP, an effective deadlock control method is proposed. Generally, the proposed method can achieve an optimal or a near-optimal, non-blocking supervisor for an uncontrolled G-system prone to deadlocks.

The purpose of this study is to investigate the benefits of the turning point layout; a simulation model being applicable for strategic level is designed that compares systems with and without turning points. Specifically, the avoidance of deadlocks and prevention of conflicts is substantial.

Optimization process for different layouts and configuration of autonomous guided vehicles (AGVs) are worked out using statistical methods for design parameters. Regression analysis is used to find effective design parameters and analysis of variance is applied for adjusting critical factors. Also, the optimal design is then implemented in a manufacturing system for an industrial automation and the results are reported.

The outputs imply the effectiveness of the proposed approach for real industrial cases. This research will combine both simulation-based method and optimization technique to improve the quality of solutions.

In AGV systems, the begin-end combinations are usually connected by using a fixed layout, which is not the optimal path. The capability of these configurations is limited and often the conflict of multiple AGVs and deadlock are inevitable. By appearing more flexible layouts and advanced technology, the positioning and dispatching of AGVs increased. A new concept would be to determine each path dynamically. This would use the free paths for AGVs leading to overcome the conflicts and deadlocks.

Siphon-based deadlock control in a flexible manufacturing system (FMS) suffers from the problems of computational and structural complexity since the number of siphons grows exponentially with respect to the size of its Petri net model. In order to reduce structural complexity of a supervisor, a set of elementary siphons derived from all strict minimal siphons (SMS) is explicitly controlled. The purpose of this paper is through fully investigating the structure of a class of generalized Petri nets, WS3PR, to compute all SMS and a compact set of elementary siphons.

Based on graph theory, the concepts of initial resource weighted digraphs and restricted subgraphs are proposed. Moreover, the concept of augmented siphons is proposed to extend the application of elementary siphons theory for WS3PR. Consequently, the set of elementary siphons obtained by the proposed method is more compact and well suits for WS3PR.

In order to demonstrate the proposed method, an FMS example is presented. All SMS and elementary siphons can be derived from initial resource weighted digraphs. Compared with those obtained by the method in Li and Zhou, the presented method is more effective to design a structural simple liveness-enforcing supervisor for WS3PR.

This work presents an effective method of computing SMS and elementary siphons for WS3PR. Monitors are added for the elementary siphons only, and the controllability of every dependent siphon is ensured by properly supervising its elementary ones. A same set of elementary siphons can be admitted by different WS3PR with isomorphic structures.

To date, there has been little research about the degree of correspondence between partner equity ownership and partner representation on boards of joint ventures (JVs). It is generally assumed that partners’ share equals board representation in percentage. This paper aims to explore various instances of deviation from the above norm.

Using a unique database of 259 JV contracts extracted from the US Securities and Exchange Commission, and by drawing from resource dependency and transaction cost theories, this manuscript explores the factors that increase or decrease the deviation between equity share and board representation.

The results show that international JVs (IJVs) tend to deviate more, while JVs with a deadlock clause, a large board and based in a stable country deviate less from the degree of correspondence between equity share and board representation.

This study contributes to the alliance and governance literatures by identifying factors that influence the degree of correspondence between partner investment (equity share) and control through board of director representation.

Conflict resolution and peace building has acquired much significance in the last few years (Siddiqi, 2003).

The purpose of this article is to examine the proposal adopted by the Equal Opportunities Commission (EOC) that employers undertaking an equal pay review should be permitted a “protected period” during which its employees would be prohibited from taking equal pay claims to law. This proposal is considered against recent collective agreements in local government and National Health Service, and where equal pay claims have been made by employees either with the support of the unions that are party to the collective agreement or more critically with external legal support.

Information is drawn from the EOC, from employer and trade union sources, and decisions of the employment tribunals and courts.

The outcome of the unstructured mix of collective bargaining and litigation shows a pattern of delay, uncertainty, added conflict between involved parties and pressure, making resource adjustments that initially were to be avoided.

The research has been undertaken as the collective agreements are being implemented. As the initial hearings of claims are not complete and there are opportunities for appeals against initial judgments, the descriptions here are unlikely to provide a settled account.

The EOC proposal is given support but shown to need further institutional support. In that regard the opportunity is taken to consider a possible alternative form of adjudication of “collective” equal pay issues. It is proposed to facilitate an extended version of a former jurisdiction of the Central Arbitration Committee.

A survey of current work on database systems is presented. The area is divided into three main sectors: data models, data languages and support for database operations. Data models are presented as the link between the database and the real world. Languages range from formal algebraic languages to attempts to use a dialogue in English to formulate queries. The support includes hardware for content addressing, database machines and software techniques for optimizing and evaluating group expressions. Mathematical models are used to organize this support. Throughout there is a tutorial component and evaluation, which in both cases is related to the application of database ideas to documentation.

The purpose of this paper is to present research in the area of the applications of knowledge‐based and constraint programming (CP)‐driven methodology in production planning and development of decision‐making software supporting scheduling of multi‐robot in a multi‐product job shop, taking into account imprecise (fuzzy) activity specification, and resource sharing by some industrial processes that simultaneously produce different products.

Applications of the knowledge‐based, logic‐algebraic and CP‐driven approach for multi‐robot task allocation problem and generating of fuzzy plan/schedule of production activities for a given period of time.

This paper illustrates the useful information that can be obtained from fuzzy and crispy‐like schedule describing production activities in a multi‐product job shop.

The use of knowledge‐based and CP‐driven methodology for production planning in a multi‐product job shop was a very effective method dedicated to solve typical decision problems in the area of project‐driven production flow management applied in make‐to‐order manufacturing.

The methodology discussed in the paper can be used to design fuzzy Gantt diagrams, which define admissible schedule of production orders for a given period of time.

The paper's contribution covers various issues of decision making while employing the knowledge‐ and CP‐based framework. The proposed approach provides the framework allowing one to take into account distinct (pointed), and imprecise (fuzzy) data, in a unified way and treat it in a unified form of a discrete, constraint satisfaction problem.