Computationally Improved Optimal Control Methodology for Linear Programming Problems of Flexible Manufacturing Systems

Deadlock prevention policies are used to solve the deadlock problems of FMSs. It is well known that the theory of regions is the efficient method for obtaining optimal (i.e., maximally permissive) controllers. All legal and live maximal behaviors of Petri net models can be preserved by using marking/transition-separation instances (MTSIs) or event-state-separation-problem (ESSP) methods. However, they encountered great difficulties in solving all sets of inequalities that is an extremely time consuming problem. Moreover, the number of linear programming problems (LPPs) of legal markings is also exponential with net size when a plant net grows exponentially. This paper proposes a novel methodology to reduce the number of MTSIs/ESSPs and LPPs. In this paper, we used the well-known reduction approach Murata (1989) to simply the construct of system such that the problem of LPPs can then be reduced. Additionally, critical ones of crucial marking/transition-separation instances (COCMTSI) are developed and used in our deadlock prevention policy that allows designers to employ few MTSIs to deal with deadlocks. Experimental results indicate that the computational cost can be reduced. To our knowledge, this deadlock prevention policy is the most efficient policy to obtain maximal permissive behavior of Petri net models than past approaches

Petri Nets at Modelling and Control of Discrete-Event Systems with Nondeterminism - Part 2

Discrete-Event Systems (DES) are discrete in nature. Petri Nets (PN) are one of the most widespread tools for DES modelling, analyzing and control. Different kinds of PN can be used for such purposes. Some of them were described in [3], being the first part of this paper. Here, the applicability of Labelled PN (LbPN) and Interpreted PN (IPN) for modelling and control of nondeterministic DES, especially with uncontrollable and/or unobservable transitions in the models, will be pointed out. Moreover, another kinds of nondeterminism in DES (errors, failures) will be modelled, and the possibilities of the error recovery of failed system will be presented

Design and Management of Manufacturing Systems

Although the design and management of manufacturing systems have been explored in the literature for many years now, they still remain topical problems in the current scientific research. The changing market trends, globalization, the constant pressure to reduce production costs, and technical and technological progress make it necessary to search for new manufacturing methods and ways of organizing them, and to modify manufacturing system design paradigms. This book presents current research in different areas connected with the design and management of manufacturing systems and covers such subject areas as: methods supporting the design of manufacturing systems, methods of improving maintenance processes in companies, the design and improvement of manufacturing processes, the control of production processes in modern manufacturing systems production methods and techniques used in modern manufacturing systems and environmental aspects of production and their impact on the design and management of manufacturing systems. The wide range of research findings reported in this book confirms that the design of manufacturing systems is a complex problem and that the achievement of goals set for modern manufacturing systems requires interdisciplinary knowledge and the simultaneous design of the product, process and system, as well as the knowledge of modern manufacturing and organizational methods and techniques

The Stability/Sustainability Dynamics: The Case of Marine Environmental Management in Somalia

Since January 1991, Somalia has been a war-torn society without law and order machinery. After a decade of chaos, in January 2001, an interim government formed in Djibouti was brought to Mogadishu, albeit it failed to function. Two similar others followed; one in 2004 and the other in 2007. In 2012, a federal government was elected by 275 members of parliament, but it is yet to govern most of the countrys regions. Consequently, over 25 years, there has been sociopolitical and economic instability which jeopardised Somalias environment and security (land and marine). Now, who are the actors of socio-political and economic instability, and can marine sustainability be achieved in the absence of stability? This doctoral study identifies, defines, examines and analyzes each of the state and non-state actors/networks operating in Somalia, at the international, regional, national, provincial, and local levels. I investigated who are they and what are their backgrounds/origins? What are their objectives and strategies? What are their capacities and economic status? What are their motives and manoeuvres? and what are their internal and external relationships? I categorised each one of them based on these scales: instability, potential stability or stability. I adopted a multi-dimensional approach which aims at tackling both marine environmental degradation and insecurity in the Somali basin, while establishing a community-based policy as a milestone for the formulation of a national/provincial policy. The study finds out that the competing multifaceted and multipurpose (economic, political or social gains) networks deliberately or inadvertently destroy the countrys environment and contribute to instability. Yet, in the countrys post-conflict situation, environmental traditional-based policy and socio-legal systems can be practiced at the grassroots level. I then proposed the roles to be played by individuals, local communities, provincials, and national, as well as regional, and international communities in the implementation of this bottom-up approach policy. While showing the relationship between environmental sustainability and sociopolitical stability, I argue that marine problems are borderless and as such, need global attention. I shed light on how war-torn states and post-conflict countries can establish vital means of environmental sustainability by applying community-based policy, implemented through self-help programs

Factories of the Future

Engineering; Industrial engineering; Production engineerin