Nabil Gindy

A simulated annealing algorithm for dynamic layout problem

Abstract Increased level of volatility in todays manufacturing world demanded new approaches for modelling and solving many of its well-known problems like the facility layout problem. Over a decade ago Rosenblatt published a key paper on modelling and solving dynamic version of the facility layout problems. Since then, various other researchers proposed new and improved models and algorithms to solve the problem. Balakrishnan and Cheng have recently published a comprehensive review of the literature about this subject. The problem was defined as a complex combinatorial optimisation problem. The efficiency of SA in solving combinatorial optimisation problems is very well known. However, it has recently not been applied to DLP based on the review of the available literature. In this research paper a SA-based procedure for DLP is developed and results for test problems are reported. Scope and purpose One of the characteristic of todays manufacturing environments is volatility. Under a volatile environment (or dynamic manufacturing environment) demand is not stable. To operate efficiently under such environments facilities must be adaptive to changing demand conditions. This requires solution of the dynamic layout problem (DLP). DLP is a complex combinatorial optimisation problem for which optimal solutions can be found for small size problems. This research paper makes use of a SA algorithm to solve the DLP. Simulated annealing (SA) is a well-established stochastic neighbourhood search technique. It has a potential to solve complex combinatorial optimisation problems. The paper presents in detail how to apply SA to solve DLP and an extensive computational study. The computational study shows that SA is quite effective in solving dynamic layout problems.

A TABOO SEARCH BASED APPROACH TO FIND THE PARETO OPTIMAL SET IN MULTIPLE OBJECTIVE OPTIMIZATION

Abstract Taboo search is a heuristic optimization technique which works with a neighbourhood of solutions to optimize a given objective function. It is generally applied to single objective optimization problems. Taboo search has the potential for solving multiple objective optimization (MOO) problems, because it works with more than one solution at a time, and this gives it the opportunity to evaluate multiple objective functions simultaneously. In this paper, a taboo search based algorithm is developed to find Pareto optimal solutions in multiple objective optimization problems. The developed algorithm has been tested with a number of problems and compared with other techniques. Results obtained from this work have proved that a taboo search based algorithm can find Pareto optimal solutions in MOO effectively.

A new approach for systematic design of condition monitoring systems for milling processes

Abstract This paper outlines an approach, termed ASPS (automated sensory and signal processing selection system), aimed at aiding the systematic design of condition monitoring systems for machine tools and machining operations. The work is based on utilising Taguchi’s orthogonal arrays to design an experimental programme for investigating the number and type of sensors and signal processing methods most appropriate for the detection of fault conditions for milling processes. Cutting tool condition is selected in this work as an application of the proposed approach. The goal is to reduce the number of sensors needed to detect cutter deterioration and reduce the cost and time required for developing and optimising the design of the condition monitoring system for machining operations.

MOCACEF 1.0: Multiple objective capability based approach to form part-machine groups for cellular manufacturing applications

A pre-emptive goal programming formulation is developed for concurrently forming independent part/machine cells. Machine independent capability units, which are known as Resource Elements (RE), are used to define processing requirements of parts and processing capabilities of machine tools. Representation of unique and shared capability boundaries of machine tools is possible via RE, which increases the opportunity to form independent manufacturing cells and efficient utilization of them. RE-based operation sequences, processing times, capacities, demand, cell sizes, cell flexibility, load balance between cells, cell interaction, copies of each machine type in the job shop are all considered in the problem formulation. The model is solved by a specially developed tabu search algorithm.

Component grouping for GT applications—a fuzzy clustering approach with validity measure

The variety of the currently available component grouping methodologies and algorithms provide a good theoretical basis for implementing GT principles in cellular manufacturing environments. However, the practical application of the grouping approaches can be further enhanced through extensions to the widely used grouping algorithms and the development of criteria for partitioning components into an ‘optimum’ number of groups. Extensions to the fuzzy clustering algorithm and a definition of a new validity measure are proposed in this paper. These are aimed at improving the practical applicability of the fuzzy clustering approach for family formation in cellular manufacturing environments. Component partitioning is based upon assessing the compactness of components within a group and overlapping between the component groups. The developed grouping methodology is experimentally demonstrated using an industrial case study and several well known component grouping examples from the published literature.

Tool condition monitoring in broaching

Abstract The paper reports on research which attempts to correlate the condition of broaching tools to the output signals obtained from multiple sensors, namely, acoustic emission (AE), vibration, cutting forces and hydraulic pressure, connected to a hydraulic broaching machine. Broaching tools in a variety of conditions, namely, freshly ground teeth, one or more chipped teeth, one or more weakened teeth, one or more broken teeth and tools showing uniform wear, were investigated. Single tooth and multiple teeth broaching tools were employed during the broaching trials and the sensory signals were analysed both in the time and frequency domains. The results show that AE, vibration and cutting force signals are all sensitive to tool condition and a correlation can be made between the broaching tool condition and sensory signals using a variety of signal analysis techniques. A brief review of the advantages and the disadvantages of each sensor/signal and its associated analysis technique is presented. It is concluded that the most sensitive sensors to changes in tool condition are not necessarily those that are easy to mount or incorporate in a broaching machine. This can impose restrictions on the types of sensors that can be retrofitted to current machines. The condition monitoring system is currently being extended to incorporate sensor fusion techniques to increase the flexibility of the monitoring system and improve confidence in decision-making.

Technology roadmapping for the next generation manufacturing enterprise

Purpose – For high technology companies, the successful acquisition and management of technology to enable the development and manufacture of innovative products is a key factor in their competitiveness. Seeks to present an integrated technology road‐mapping methodology that enables management to define its technology requirements, taking account of financial and other issues, to assess proposed technology projects against these requirements and to create a balanced technology project portfolio.Design/methodology/approach – The methodology consists of six steps or phases; the first three steps produce a set of technology requirements based on a companys business drivers, products and competitive position; the last three steps enable the creation and assessment of a portfolio of research and development projects.Findings – Applications of the methodology in industry have demonstrated that the integrated nature of the process, from a derivation of technology requirements to investment decision making, impr...

An automated GD&T inspection system based on non-contact 3D digitization

Rapid developments and improvements in advanced manufacturing technology mean that the inspection process plays an important role in the quality control of manufactured products. The Geometric Dimension and Tolerance (GD&T) inspection process is used in industries to examine the conformity of manufactured parts with the part specification defined at the design stage. However, as the modern manufacturing trend is towards producing low-volume, high-variety, high-complexity, and large products, current inspection techniques show difficulties in coping with this. This is especially true in automatically inspecting the geometric tolerance items of a manufactured part, such as parallelism and perpendicularity. This paper proposes a non-contact digitization-based automated GD&T inspection system. In this study, we defined a Nominal Inspection Frame (NIF) for a nominal CAD model or a digitized model, in which every GD&T item required may be defined and specified. Using the NIF, an algorithm for automatically extracting the GD&T information on a measured model was developed and implemented in a Reverse Engineering (RE) environment with software. We examine this proposed approach with several applications on dimension tolerance, geometric tolerance, and free-form surface inspection, and discuss the inspection results in the paper.

Nano- and micro-sized honeycomb patterns through hierarchical self-assembly of metal-loaded diblock copolymer vesicles

Herein we present a novel approach for fabricating metallic micro- and nano-structures in thin films viaspin-coating solutions of diblock copolymer vesicles. A simple concept was developed, which is based on the metallization and self-assembly diblock copolymers. Firstly, vesicles incorporating the inorganic components are generated in solution by adjusting the solvent ratio in water–toluene mixtures. Subsequently, thin films are deposited onto a solid substrate viaspin-coating. As a result micro- and nano-sized honeycomb structures are obtained; the pore diameter is dependent on the size and size distribution of the vesicles. Hence, control over the pattern dimensions and the degree of order can be achieved by tuning the vesicle diameter prior to film deposition. Finally, the block copolymer is extracted by means of oxygen plasma etching, leaving behind inorganic Au-nanostructures that mimic the original film morphology. The surface properties of these honeycomb patterns, in terms of hydrophobicity, can be adjusted by controlling the film thickness and the characteristic dimension of the pattern.

Handling internal and external disturbances in responsive manufacturing environments

The major aim of the research presented in this paper is to report on an extensive investigation of one of the important problems that is frequently encountered during the operation of manufacturin...