Paul Young

This article interweaves the widely published empirical frameworks with a new paradigm proposing stochastic dynamic decision-making tools that could be employed for capturing the trade-offs among multiple and conflicting-in-nature criteria so as to provide a design of a resilient shock absorber (RSA) for disrupted supply chain network (SCN). Modern SCNs encounter ‘excursion events’ of different kinds mainly due to uncertain and turbulent markets, catastrophes, accidents, industrial disputes/strikes in organisations, terrorism and asymmetric information. An ‘excursion event’ is an unpredictable event that effectively shuts down or has a relatively large negative impact on the performance of at least one member of a system for a relatively long amount of time. In this article, design of an analytical framework has been conceptualised that allows an SCN to avoid propagating the ill effects of the ‘excursion events’ further and maintains the network at a desired equilibrium level. A broad analytical view of econophysics has been conceptualised using the definition of a ‘system’ from physics. An example derived from the 9/11 case has been delineated in order to illustrate the efficacy of the proposed design. The devised RSA facilitates the assessment of resiliency strategies for SCNs prone to excursion events that are characterised by low probability of occurrence and high impact. The shock-dampening fortification framework also enables practitioners to identify and assess quantitatively the islands of the excursion events in SCN.

Semiconductor manufacturing facilities are migrating to 300mm technology, necessitating the implementation of automated material handling systems (AMHS) for a variety of ergonomic and safety considerations. A predictive tool, such as software simulation, is needed at the planning stage to estimate the performance of these relatively new systems. Two forms of AMHS are in general use in industry one which handles

First published in September 2007, the Systems Modeling Language (SysML) is a recent language for systems modeling that has a growing community of users and advocates in the field of systems engineering. This chapter gives an overview of SysML, identifies why it is ...

ABSTRACT This paper describes a test implementation of the Core Manufacturing Simulation Data (CMSD) information model and the integration and initialisation of a simulation model in a newly developed Simulation Engine. The cost of developing, implementing and using simulation technology is high. The costs of integrating simulation models with other manufacturing applications are even higher. There is always a need to enable data exchange and sharing between simulation applications and other software applications. The idea of the CMSD effort is to facilitate the above using neutral, reusable data structures for managing actual production operations and for simulating the performance of the manufacturing system. To address the problem of time consuming pre-coding for DES projects, a knowledge extraction tool is currently being developed. The knowledge extraction tool will read data from several resources of an organisation and output it in a format that is applicable for simulation purposes. The format that we adopted follows the CMSD standard in order to describe simulation related data. In this paper we present the modelling of a complex production line of our industrial partner with the CMSD standard and the development of the translator in ManPy so that it can read the CMSD information model and run the simulation.

The Job-shop scheduling is one of the most important industrial activities, especially in manufacturing planning. The problem complexity has increased along with the increase in the complexity of operations and product-mix. To solve this problem, numerous approaches have been developed incorporating discrete event simulation methodology. The scope and the purpose of this paper is to present a survey which covers

A computational study has been developed to obtain optimal / near optimal solution for the flow shop scheduling problem with make-span minimization as the primary criterion and the minimization of either the mean completion time, total waiting time or total idle time as the secondary criterion. The objective is to determine a sequence of operations in which to process ‘n’

The current trend in semiconductor manufacturing is characterized by expanding product variety, decreasing lead times from order to delivery, exacting standards of quality, and competitive prices. One possible means of achieving this is in the form of increased flexibility. Providing flexibility is typically an expensive proposition so, industrial engineers aim to provide more economic approaches to enable flexible manufacturing cells

This article interweaves the widely published empirical frameworks with a new paradigm proposing stochastic dynamic decision-making tools that could be employed for capturing the trade-offs among multiple and conflicting-in-nature criteria so as to provide a design of a resilient shock absorber (RSA) for disrupted supply chain network (SCN). Modern SCNs encounter ‘excursion events’ of different kinds mainly due to uncertain

Exergy analysis has been applied to desalination membrane processes in an effort to characterise energy consumption and to optimise energy efficiency. Several models have been used to this end in the literature. One assumption that is common in these analyses is that of ideal solution behavior. However, seawater and other aqueous solutions of interest do not behave ideally. Indeed, even when ideal behavior is not assumed, there are several approaches to calculate these activity values, which are typically a function of the molality and ionic strength of the electrolytic solution. What is not clear from the published literature is the impact that the choice of activity calculation model has on the exergy analysis results. The objective of this research was to undertake the exergy analysis of a seawater membrane desalination plant using the Szargut chemical exergy approach and to compare the activity calculation approaches. The chemical exergy of the seawater was calculated using seve...

ABSTRACT In the literature, several exergy analysis approaches have been proposed to investigate desalination processes. It is not clear, however, which approach is the most appropriate or indeed whether all approaches are valid. The objective of this paper is to review the various methods and to critically assess their assumptions, limitations, advantages and disadvantages. The main focus of this work is the chemical exergy term. Several exergy calculation models were examined and compared using a dataset from the literature. In addition, an accurate approach to calculate the chemical exergy of electrolyte solutions, based on the Pitzer equations, was proposed. The models assessed were: (1) the ideal mixture model (NaCl and water), (2) the ideal mixture model (seawater salt and water), (3) the Sharqawy seawater functions, and (4) the electrolyte solution model (Pitzer equations, NaCl and water), (5) the model used by Drioli et al. and (6) the dissociated ion approach (NaCl and water). Four of the six approaches produced very similar results. Moreover, one other exergy calculation method was found to have serious limitations. The findings presented here show that the choice of exergy model can have a significant impact on the results obtained and that considerable care must be taken to select the most suitable approach.

Exergy, the quality of energy, is not conserved but is destroyed due to process irreversibilities. This exergy destruction can be quantified using an exergy balance which “may be looked upon as a statement of the law of degradation of energy [1]”. Exergy analyses have been applied to the desalination industry, however, based on an extensive review of the desalination exergy literature, it is evident that several desalination exergy models exist, presenting a challenge to those wishing to undertake an exergy analysis. How does one know which model to use and whether these models give similar results? This paper investigates two exergy calculation models (Model A and Model B) in depth, and considers both models in light of the specific physical and chemical exergy definitions described in key exergy texts (Model C). Results showed that the maximum percentage difference in specific physical exergy at each process stage was 2.07% for Model A and Model B. However, the specific chemical e...