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In this study, we combine two aspects of remanufacturing, namely product acquisition management and marketing (pricing) of the remanufactured products. We consider an original equipment manufacturer (OEM) who decides on the acquisition prices offered for returns from different quality types and on selling prices of new and remanufactured products, in a single period setting. We develop a procedure for determining the optimal prices and corresponding profit of the OEM, and conduct a sensitivity analysis to understand the effect of different model parameters on the optimal strategies and profit. An important managerial insight is that the optimal solution is not to have the same profit per remanufactured item for all return types, but to if the minimum cost for acquisition and remanufacturing of some core type is lower. [ABSTRACT FROM AUTHOR]

The performance of a wafer fabrication system is constrained by its bottlenecks, which are difficult to detect and improve due to the complexity within the system. To weaken the negative effects of bottlenecks, a work in process (WIP) strategy is proposed in this paper which focuses on offline target WIP level setting and online WIP control simultaneously. First, bottlenecks are detected and classified based on the constraint weights which are decided by the sensitivity of the system performance to the machine's fluctuant availability. Second, the target WIP level is allocated to the bottlenecks to avoid the process fluctuation caused by unpredictable events. Third, in real time scheduling, the upstream machine of the bottlenecks modifies its dispatching order to adjust the deviation of the WIP levels at the bottlenecks. Finally, a simulation platform is developed to validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper considers the problem of parallel machine scheduling with sequence-dependent setup times to minimise both makespan and total earliness/tardiness in the due window. To tackle the problem considered, a multi-phase algorithm is proposed. The goal of the initial phase is to obtain a good approximation of the Pareto-front. In the second phase, to improve the Pareto-front, non-dominated solutions are unified to constitute a big population. In this phase, based on the local search in the Pareto space concept, three multi-objective hybrid metaheuristics are proposed. Covering the whole set of Pareto-optimal solutions is a desired task of multi-objective optimisation methods. So in the third phase, a new method using an e-constraint hybrid metaheuristic is proposed to cover the gaps between the non-dominated solutions and improve the Pareto-front. Appropriate combinations of multi-objective methods in various phases are considered to improve the total performance. The multi-phase algorithm iterates over a genetic algorithm in the first phase and three hybrid metaheuristics in the second and third phases. Experiments on the test problems with different structures show that the multi-phase method is a better tool to approximate the efficient set than the global archive sub-population genetic algorithm presented previously. [ABSTRACT FROM AUTHOR]

In this paper, a simulated annealing approach is developed for the parallel mixed-model assembly line balancing and model sequencing (PMMAL/BS) problem which is an extension of the parallel assembly line balancing (PALB) problem introduced by Gokcen et al. (2006). In PALB, the aim is to balance more than one assembly line together. Balancing of the lines simultaneously with a common resource is very important in terms of resource minimisation. The proposed approach maximises the line efficiency and distributes the workloads smoothly across stations. The proposed approach is illustrated with two numerical examples and its performance is tested on a set of test problems. The computational results show that the proposed approach is very effective for PMMAL/BS. [ABSTRACT FROM AUTHOR]

Cell formation is a procedure that involves identification of product families and their associated machine cells. This paper proposes a new cell formation algorithm, called heuristics rules-based logic (HERBAL), which belongs to the class of array-based matrix formulation algorithms. The algorithm incorporates the machine-component incidence (MCI) matrix to identify the component or part families and their associated machine groups. The algorithm, to an extent, overcomes some of the known drawbacks, such as in manipulating ill-structure machine-part matrices, attaining rational sizes of cells and employing weighted machine-part matrices. The proposed cell formation algorithm has been tested on a number of well-known data sets obtained from the literature as well as on a number of randomly generated data sets. In both cases, it has demonstrated successful groupings, in terms of the grouping efficiency, grouping efficacy and quality index measures. [ABSTRACT FROM AUTHOR]

In today's competitive environment cellular manufacturing (CM) is a well-known strategy in improving manufacturing performance. To obtain the full benefits that CM has to offer successful implementation is a critical factor. Evidence indicates that firms converting to CM often struggle with implementation and achieve results that are less than anticipated. A comprehensive review of implementation literature was undertaken and a multi-phase model developed and evaluated through a case study. The framework recognizes the importance of both technical and human aspects of CM and provides practitioners with a better understanding of the various phases in the implementation process, including the many activities and issues which need to be considered for each step. In the case study company, implementation of CM not only provided many of the benefits associated with this form of manufacturing but also allowed operators to become a value-adding link in respect to process and product improvement and new product development. [ABSTRACT FROM AUTHOR]

Many operations in CNC milling tasks are performed using pocket milling which has two main types of tool path trajectories, contour parallel path and direction parallel path. Hence there have been a lot of works on geometrically efficient algorithms to generate tool paths. Although the conventional tool path obtained from geometric information has been successful to make a desirable shape, it seldom considers physical process concerns like cutting forces and chatters. In order to cope with these problems, an optimized tool path, which maintains as constant MRR as possible in order to achieve constant cutting forces and to avoid chatter vibrations at all time, is introduced and the result is verified. Additional tool path segments are appended to the basic tool path obtained by geometric shape by using a pixel-based simulation technique. The algorithm has been implemented for two-dimensional contiguous end milling operations, and cutting tests are conducted by measuring spindle current, which reflects machining situations, to verify the significance of the proposed method. [ABSTRACT FROM AUTHOR]

Monitoring the condition of cutting tools in any machining operation is very important to avoid unexpected machining trouble and improve machining accuracy. This paper presents the use of vibration analysis of the cutting process in milling to indicate the presence and progression of damage incurred by an end mill. The metal cutting experiments were performed on a mild steel workpiece without using any coolant to accelerate damage to cutter, and classical processing schemes in time and frequency domains were applied to the resulting vibrations of cutting process to obtain diagnostic information. Moreover, developing fault features were also illustrated using both scalogram and its mean frequency variation. It has been found that scalogram and its mean frequency are both capable of revealing the features of not only localized, but progressive fault more clearly in the presence of strong noise than conventional time and frequency domain analyses. Furthermore, the global average of the mean frequency variation provides a useful indicator signifying the progression of wear, whereas time domain statistics do not give any consistent trend. [ABSTRACT FROM AUTHOR]

Appropriately controlled cutting forces can contribute not only to the safety and efficiency of machining but also to the quality of machined surfaces. It is even more important when hardened material is cut. The correlation between the cutting force and the surface quality in ball-end milling operations has been investigated by machining P20 steel (HRC 30) work-pieces using solid carbide ball-end cutters. Plane surfaces with different depth of cut were machined using two different cutting strategies. The first strategy cut the test-piece using a cutting force model, whereas the other machined with a feed rate optimization product, which uses the removal rate as an analogue of cutting force to control the feed rate. The test results show that constant surface quality is possible when the cutting forces are controlled through feed rate adjustment. Conversely, a desired surface quality can also be maintained by controlling the cutting force in a predetermined manner. [ABSTRACT FROM AUTHOR]

This study considers push and pull strategies to control multistage production systems with random processing times. Such systems are important as they mirror the level of complexity often encountered in practice. We start with definitions of push and pull systems, and develop a framework to compare multistage production systems based upon work-in-process (WIP) and throughput (TP) tradeoff. Surprisingly, we find that often push out performs pull, i.e. push systems accumulate less WIP than pull systems, while maintaining higher PT Concerning pull systems we find that WIP linearly increases in the number of stages and that WIP is not affected by variation in processing time. Concerning push systems we find that the release of material into the system in deterministic time intervals greatly improves performance. [ABSTRACT FROM AUTHOR]

Shigeo Shingo's 'SMED' methodology has been at the forefront of retrospective changeover improvement activity since the mid-1980s. The 'SMED' methodology, which emphasizes that improvement should be sought primarily by rearranging changeover elements into external time, has been widely acclaimed and has been widely assimilated into academic texts and industrial training material. To date, no known critical evaluation of the methodology has been undertaken. This paper, in which a case study is also presented, argues that in the sequential application of stages, the 'SMED' methodology (including the sequential application of improvement techniques that are assigned to those stages) need not always represent an effective improvement route. The 'SMED' methodology's dominant objective of translating tasks into external time is also considered. The paper argues that the 'SMED' methodology does not sufficiently promote some important improvement options, particularly those that seek to reduce the duration of existing changeover tasks or eliminate them altogether. Opportunities for improvements of this type particularly arise when design changes to the existing manufacturing system are contemplated. The issue of design in the context of incremental kaizen improvement is also investigated. [ABSTRACT FROM AUTHOR]

This note introduces a measure of parallelism for activity networks, and we suggest its relevance to concurrent engineering efforts. The importance of the ability to judge the degree of parallelism in a concurrent engineering project is discussed. Then, a brief review of the existing measures of parallelism is provided. Due to the drawbacks of some of these measures, a new measure, Omega, is introduced and its performance is compared to the other measures. The results indicate that Omega is an excellent measure of parallelism, particularly for application in concurrent engineering. [ABSTRACT FROM AUTHOR]

With the given geometrical data of a model, this paper presents a technique: (1) to prepare a workpiece with minimal material required to fabricate the model; (2) to automatically determine the necessary manufacturing processes utilizing the concept of feature-based recognition; and (3) to optimally sequence these processes based on a tabulated optimization scheme. Four types of feature, face, hole, slot, and pocket, are considered. Computational results are provided to demonstrate the capability and advantage of the technique. Conclusions are given and recommendations for future research are discussed. [ABSTRACT FROM AUTHOR]

The potential of expert systems in manufacturing is now well documented, if not unanimously accepted. However, particularly in the welding domain, there is comparatively little evidence of their practical realisation or regular utilisation in industry. The main objective of this work was to evaluate recent computing advances in the context of planning for arc welding. Thus the objectives of this study were not so much concerned with simply producing another `expert system', but rather to extract more generic knowledge about the application of expert system techniques to advanced manufacturing problems. Furthermore it was intended to evaluate the claims made about expert systems regarding their ease of use, extendibility and modifiability. A prototype system is described which can generate welding procedures to the specification of BS4870. [ABSTRACT FROM AUTHOR]

Several observations regarding the normality of the total batch completion times in flexible manufacturing are presented. It is shown that normality holds under some but not all conditions. Other conditions, prevalent in flexible manufacturing and leading to multimodal batch completion times, are discussed. [ABSTRACT FROM AUTHOR]

Traditional methods of estimating the 'process average' detect rate of a manufacturing process involves selecting a fixed number of items from the process and using the sample defective proportion as its estimate. If the estimate is required to have a precision proportional to the true process average defect rate, the sample size required is dependent on that true process average. When prior knowledge about the process average is uncertain and its value is low, as in most modern production situations, this binomial sampling scheme often fails to meet the predetermined precision specifications or results in an unnecessarily large number of observations. A well-known sequential estimation method called inverse negative binomial sampling is considered as a potentially more efficient alternative to the traditional binomial fixed sample size approach. particularly under such circumstances. Several existing estimators for the method are presented and compared, from which derives a general estimator whose closed form expressions permit simple determination of moments for estimators fitting this general form. A new estimator is then derived from the general estimator and is shown to he more efficient than the existing ones The precision of the sequential estimation method using the new estimator is shown to be virtually insensitive to a. prior knowledge of the true process average, thereby avoiding the need to provide an initial estimate of it, and therefore making it potentially attractive in practical applications. [ABSTRACT FROM AUTHOR]

Knowledge of material properties, microstructure, underlying material composition, and manufacturing process parameters that the material has undergone is of significant interest to materials scientists and engineers. A large amount of information of this nature is available in publications in the form of experimental measurements, simulation results, etc. However, getting to the right information of this kind that is relevant for a given problem on hand is a non-trivial task. First, an engineer has to go through a large collection of documents to select the right ones. Then, the engineer has to scan through these selected documents to extract relevant pieces of information. Our goal is to help automate some of these steps. Traditional search engines are not of much help here, as they are keyword centric and weak on relation processing. In this paper, we present a domain-specific search engine that processes relations to significantly improve search accuracy. The engine preprocesses material publication repositories to extract entities such as material compositions, material properties, manufacturing processes, process parameters, and their values and builds an index using these entities and values. The engine then uses this index to process user queries to retrieve relevant publication fragments. It provides a domain-specific query language with relational and logical operators to compose complex queries. We have conducted an experiment on a small library of publications on steel on which searches such as “get the list of publications which have carbon composition between 0.2 and 0.3 and on which tempering is carried out for about 30 to 40 min” are performed. We compare the results of our search engine with the results of a keyword-based search engine. [ABSTRACT FROM AUTHOR]

Nowadays the lean philosophy's tool- and rule system has spread into the production- and service areas as well. This is because companies using the lean philosophy are able to reduce their wastes continuously, thus they can gain a significant competitive advantage. One of the most important tools of the lean philosophy is the SMED method that enables a reduction in the changeover time of manufacturing/production processes. The reduction of the changeover time has a role in changing numerous parameters of the manufacturing/production process, which can result in increased efficiency of the examined manufacturing/production processes. The algorithm of the SMED method has been determined but application of simulation investigational methods can be necessary in many cases for increased efficiency. The paper introduces the application possibilities of the simulation investigational methods in the SMED method, as well as the concept for an elaborated investigational method. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for the application of real-time optimization techniques to the problem of optimally scheduling and managing the interaction between electricity providers and users so that the grid and loads can come to an agreement to achieve optimal economic performance. The energy flows in typical industrial processes (e.g., chlor-alkali production) are simulated to illustrate day-ahead scheduling and contract following behaviors, as well as real-time demand response management. A communication and incentive scheme is first proposed for the complete energy scheduling process. Energy management strategies are then developed to realize the objectives of meeting production requirements while minimizing the overall operating and environmental costs through producing, purchasing and selling electricity. The energy contract following and demand response policies are also integrated into the proposed methodology, which appear to reduce uncertainties and help maintain the reliability of the grid. [ABSTRACT FROM AUTHOR]

Reconfigurable manufacturing system has been deemed as a new frontier of manufacturing system. Reconfigurability in manufacturing system attempts to impel flexibility in the system not only in producing a variety of parts but also in changing the system capacity, though the amount of reconfigurability in a manufacturing system depends on the demand and product mix of a manufacturing scenario. In the present work, a fuzzy based quantitative approach is developed for need assessment of a reconfiguration of a manufacturing system based on the existing capacity and future needs. To determine the required reconfigurability in the system, a reconfigurability need index (RNI) is proposed considering both scale up and scale down reconfiguration in terms of operational requirements. The approach employs fuzzy sets and fuzzy rule base are formulated to counter the uncertainty and vagueness in demands. The developed model is computationally tested in C++ and illustrated through a case study. [ABSTRACT FROM AUTHOR]

This paper concerns the issues of measurement techniques, analysis and assessment of the machined surface geometric structure. The aim of this work was to show the application of surface analysis in diagnosing the causes of discrepancies occurring in the manufacturing process, which may result from ill-matched (poorly fitting) process parameters. An appropriate system of control and interpretation of results may allow early reaction to unfavorable trends (for example blunting of the tool) and prevention of undesirable defects. The subject of research was a waste basket used in the construction of retaining sewer systems. In this paper, the quality of the waste basket as well as its manufacturing process were analyzed and assessed. The research was carried out with the use of three measurement stands, i.e. optical microscopy (OM), scanning electron microscopy (SEM) and white light interferometer (WLI). The surface analysis proved to be important from the viewpoint of outlining the production process as well as improving the product quality. The software used for topographical analysis appeared to be significant for the success of the analysis, providing notable economic effects, namely the lack of defects. [ABSTRACT FROM AUTHOR]

In the industry, only rotary dynamometers can be used for monitoring when multiple spindles are used in machining operations. The current commercial rotary dynamometers are bulky and expensive for most machining centers. The basic hardware and computational tools proposed are for a smaller, more cost effective Torque-based Machining Monitor (TbMM). The objective of the TbMM concept is to estimate the remaining tool life, detect chatter from the torque signal inside the proposed device, and communicate with the central computer only when problems arise. The remaining tool life estimation and chatter detection algorithms of the TbMM were developed by analyzing the experimental data collected by a commercial rotary dynamometer. The mechanical hardware of the TbMM was designed to generate voltage proportional to the cutting torque using a piezoelectric composite element. The remaining tool life was estimated from the standard deviation (or variance) of the torque signal. Teager-Kaiser algorithm (TKA) based procedure detected the chatter based on the frequency estimations only from four samples at a time. The accuracy and characteristics of the signal of the mechanical component of the TbMM were found satisfactory in the estimation of machining problems such as wear and chatter. The TbMM is a good choice particularly when multiple spindles work simultaneously on the same workpiece. [ABSTRACT FROM AUTHOR]

To obtain various underlying data from machining processes, measuring and sensing devices are required to be distributed at different machining process nodes. Considering the characteristics of multistage machining processes (MMPs), a measuring and sensing network (MSN) for analyzing product-quality and equipment-fault is proposed and its complexity is discussed. In order to establish this MSN, first, product machining form features, machining components, measuring and sensing elements are abstracted as different network nodes. The coupling relationships (such as evolving, locating, machining, inspecting and monitoring) between different nodes are mapped into network edges. Next, a level-by-level evolution model is presented to illustrate the formation procedure of establishing MSN. Then, combined with complex network theory, the related topological and physical properties are defined to analyze the MSN. Finally, a case study is put forward to demonstrate the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

In the article some features of multivariate statistical process control were introduced. Advantages and disadvantages of multivariate control charts (Hotelling charts) -- counterpart of traditional Shewhart control charts in multivariate space -- were also shown. The author pointed out the advantage of Hotelling charts over traditional ones in some situations. The main part of the paper is a multivariate surveillance procedure based on the division on two stages: Phase I (phase of stabilization) and Phase II (phase of monitoring). After describing some elements of multivariate statistical process control implementation (considered from the methodological point of view) author introduced two most popular control charts used in industrial practice: control charts for individual observations and for means. The article is summarized by some author's conclusions concerning popularity of multivariate surveillance and future directions of his work. [ABSTRACT FROM AUTHOR]

Traceability is normally difficult to achieve in continuous processes, since there are no natural batch structures. In this article, we demonstrate flow-based simulation using process data to improve traceability in a continuous pelletising process. Using the simulation model, the engineers could test the impacts of process disturbances, identify cause and effect relations and aid control in case of process disturbances. In a field trial where the chemistry of an additive was varied during production of a special product, the simulation forecasts predicted the level of the chemical content after the plant within the errors that the engineers found acceptable. [ABSTRACT FROM PUBLISHER]

Purpose – The purpose of this paper is to address the capture and documentation of essential design for manufacture (DFM) pieces of information to make design decisions. Essential manufacturing information is that which can affect the fulfilment of functional requirements and product constraints. The hierarchical structure of the main components for the open architecture-process planning model (PPM), manufacturing activity model (MAM) and manufacturing resource model (MRM) are discussed The aim of the approach is to define manufacturing knowledge structures and develop a knowledge-based application for DFM. Design/methodology/approach – This work addresses the capture and documentation of essential DFM pieces of information to make design decisions. Essential manufacturing information is that which can affect the fulfilment of functional requirements and product constraints. The hierarchical structure of the main components for the open architecture-PPM, MAM and MRM are discussed. The aim of the approach is to define manufacturing knowledge structures and develop a knowledge-based application for DFM. Findings – This paper gives details of the application framework development by integrating object-oriented technology and component-based development. This will help to achieve large-scale software reuse for manufacturing application development projects. This paper also gives an overview of a computer system for automated concurrent engineering, and more particularly, to a method for the concurrent design of parts, tools and processes. Originality/value – The workability of this approach was tested in a machine-tool manufacturing firm and the same has been presented as a case. [ABSTRACT FROM AUTHOR]

This is not an article! With this evident contradiction inspired by Rene Magritte's painting of a pipe, I will underline the special conditions I was given by the editor. The intention is that I shall review my own work and career, to articulate key ideas and to tell what I see as future challenges in my area. Therefore the use of 'I' is in a non-traditional form. The object of this article is the author's Weltanschaung concerning design and designing as it has developed over a 45 years period as teacher and researcher. Three dimensions are treated in an attempt to answer the following questions: how can we establish rigour and strong foundation for researching design? How to explain to industry what they are doing, and how to create industrial support? And what to tell the students about designing? I will focus upon the dislocations which have led to the development of the current state and what we see as a comprehensive school of designing. Details about established results can be found in the literature; I will focus upon the questions, thoughts, problems and beliefs behind the answers, and unsolved or non-clarified aspects. The article follows three lines of development, labelled Theory of Technical Systems, Engineering Design and Product Development, and our attempts to create a totality out of design philosophy, Domain Theory, Theory of Properties and our understanding of product development. Together they are the main part of 'our school', namely the foundation of the group 'Engineering Design and Product Development' at the Technical University of Denmark; the 'Copenhagen School' as our friends often refer to us. The conclusion attempts to balance in a joint model what I see as the role of design research in the worlds of teaching and practice, and where I see the challenges for the future. [ABSTRACT FROM AUTHOR]

Various types of phenomena contribute to the variability of process results. Their common feature is randomness. Some of them can be described by continuous probability distributions, for example, the performance of machines or the properties of processed material. There are also discretely distributed contributions, such as human errors or machine failures. Six sigma methodology encompasses both continuous and discrete phenomena by expressing measures of variability by the so-called 'sigma measure'. However, this methodology cannot be used directly to assess the individual impact of a specific class of factors, such as human errors in a continuously distributed production process. This paper describes the development of a probabilistic model of human error. The model makes use of classical reliability concepts, such as a failure rate function, to represent substantial phenomena of various types (continuous and discrete) that play a significant role in the creation of errors in human work. The model includes a mechanism that is inherently associated with human work (i.e. the 'bathtub curve' that represents the processes of learning and fatiguing) and mechanisms introduced by the work environment (accumulation of tasks). The hypothesis is formulated that, in industrial processes, special causes of errors are closely related to the assignment of inadequate amounts of time for properly performing the operations. Graphs of error rate functions enable intuitive graphical interpretation of the causes of problems, and they can be used to support some considerations regarding the organization and measurement of workflow during a work shift. Thus, an intuitive graph can be useful for figuring out the potential impact on the risk of errors that will result from certain system events. Such graphs can be applied in a general capability study of a process to assess the variability measures associated with the individual impacts of particular classes of factors, for example, the sigma measure used in the six sigma methodology. It can be used to identify mechanisms of potential failures associated with human error in risk analysis, such as FMEA (Failure Mode and Effect Analysis). Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The characteristic of layered manufacturing is the incremental build-up which inevitably leads to the staircase effect. One method to reduce this effect is to optimise part orientation and to apply adaptive slicing procedures. Although layer thickness will be decreased in some regions, process efficiency can be kept to a reasonable level. This paper presents different approaches of adaptive slicing for laser-based applications in consideration of limited range of thickness variation to ensure the mechanical part properties. In contradiction to previous work, the number of applied layer thicknesses is limited due to the associated process parameters. In order to optimise the slicing process and to obtain the best results, this paper presents a practicable approach based on existing work to simulate adaptive slicing. To underline the potential of non-uniform slicing, illustrative examples will show possible improvements in the case of replacing the uniform slicing procedure. [ABSTRACT FROM AUTHOR]

In order to increase the efficiency of wheeled mobile manipulators (WMM), it is preferred to carry the maximum payload, but in the case of a small-sized platform, which is desirable in applications, it may cause dangerous tip over, especially in the presence of obstacles. So, it is necessary to consider stability constraint in the determination of robot motion planning. This paper presents a novel approach for the determination of the maximum payload -carrying capacity of a coordinated mobile manipulator in an environment with presence of obstacle, based on stability. The proposed method considers the tip over stability on zero moment point criterion, which must be considered when the path of the end-effector is predefined but the position of the mobile platform is free, because tipping over in this condition is probable. Hence, the full dynamic model of WMM (including the coordinating vehicle and manipulator) is used, the obstacle avoidance scheme is implied based on potential functions, and the maximum payload path for a specified payload is generated using the optimal control approach. Then, an iterative method based on the stability criterion and motor restriction, including torque and jerk, was implied to calculate the maximum payload capacity. To the best of our knowledge, this is the first paper reporting on some simulation results as well as successful experiments of implementing the algorithm. The proposed approach has been implemented and tested on a nonholonomic WMM consisting of a differential-drive mobile base and a robotic arm to demonstrate the efficiency and effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

This paper considers the problem of scheduling part families (groups) and jobs within each part family in a hybrid flow shop manufacturing cell with sequence-dependent family setups times where jobs should be completed at times as close as possible to their respective due dates, and hence both earliness and tardiness should be penalized while processing parts (jobs) in each family together. It is assumed that earliness and tardiness penalties will not occur if a job is completed within the due window. The objective is to determine a schedule that minimizes sum of the earliness and tardiness of jobs. To this problem, the hybrid metaheuristic algorithm combined elements from particle swarm optimization; simulated annealing and variable neighborhood search are developed. The aim of using a hybrid metaheuristic is to raise the level of generality so as to be able to apply the same solution method to several problems. Problem sizes ranging in size from small, medium, to large are considered along with three levels of flexibility. The higher the number of stages and the number of parallel machines in each stage, the higher is the flexibility introduced into the problem. A design of experiments approach is employed to calibrate the parameters and operators of the algorithm. We present computational experiments on 126 problems and compare the results with the simulated annealing and genetic algorithms that presented recently. The computational results show that our proposed algorithm is more efficient than the other methods. [ABSTRACT FROM AUTHOR]

An octree-based (numerical control) NC simulation (Oct-OAC) system developed for end milling has two major applications: (1) NC verification and (2) optimization of the cutting parameters, viz., spindle speed, N (s−1), and feed rate, f (ms−1). Oct-OAC has a geometric modeling module to simulate the geometry of material removal process. Every object in the machining environment such as cutter, instantaneous workpiece, swept volume, etc. is stored as octree, an inexact representation of solid. Using this module, one can predict the geometry of the material removed at any instant of time and update the geometry of the blank subsequently. Optimization of cutting parameters using Oct-OAC is achieved through optimization module using a mechanistic model for computation and prediction of the cutting forces at any instant. The basic input for this module is the geometry of the contact surface between the cutter and workpiece which comes from the geometric modeling module using an octree-based solid modeler. It is through this contact surface that the cutting forces are passed from the workpiece onto the cutter and vice versa. The mechanistic modeling module can predict the instantaneous cutting forces from the instantaneous contact geometry and other process parameters like material combination of cutter–workpiece, parameters defining cutter geometry, and current cutting parameters such as N and f. Using this prediction, it will modify the cutting parameters for maximizing the material removal rate. This way, the mechanistic modeling module does what an adaptive controller will do with the help of force sensing. Therefore, the NC program optimization done using the Oct-OAC system is actually off-line adaptive control. [ABSTRACT FROM AUTHOR]

A better understanding of heat partition between the tool and the chip is required in order to produce more realistic finite element (FE) models of machining processes. The objectives are to use these FE models to optimise the cutting process for longer tool life and better surface integrity. In this work, orthogonal cutting of AISI/SAE 4140 steel was performed with tungsten-based cemented carbide cutting inserts at cutting speeds ranging between 100 and 628 m/min with a feed rate of 0.1 mm/rev and a constant depth of cut of 2.5 mm. Cutting temperatures were measured experimentally using an infrared thermal imaging camera. Chip formation was simulated using a fully coupled thermo-mechanical finite element model. The results from cutting tests were used to validate the model in terms of deformed chip thickness and cutting forces. The coupled thermo-mechanical model was then utilised to evaluate the sensitivity of the model output to the specified value of heat partition. The results clearly show that over a wide range of cutting speeds, the accuracy of finite element model output such as chip morphology, tool–chip interface temperature, von Mises stresses and the tool–chip contact length are significantly dependent on the specified value of heat partition. [ABSTRACT FROM AUTHOR]

During assembly modeling, standard parts and some existing components with a typical assembly feature (TAF) are often directly inserted into the assembly model of a product and the design time could be reduced if these components are managed effectively. In this paper, the concept of the TAF is given from the function view. To reduce the complexity of the assembly modeling process, the types of constraints are summarized through an assembly process research and a parameterization method on component level is introduced. After that, a convenient and powerful assembly mechanism for components is proposed on the basis of the features and the constraints among them. Furthermore, a component database and a system for supporting rapid assembly modeling are developed based on a flexible coding system and a method to retrieve the components is given. [ABSTRACT FROM AUTHOR]

Stereolithography was introduced into the net-shape SiC components fabrication process to produce the molds for the preparation of porous carbon preforms. The mixed resin was cast into the molds and then pyrolyzed to produce the porous carbon preforms which had a high porosity of 40.93% and were infiltrated and reacted with molten silicon to get reaction-formed silicon carbide (RFSC) components. To realize the complete infiltration of the thick wall parts, pipelines as the channels for the molten silicon were added into the components. The hierarchical structures of the porous carbon had been attained to realize the controllability of the microstructure and properties of RFSC. The samples had a high linear and volume shrinkage, 24.7% and 57.3%, respectively, during the pyrolysis process. Phase composition had been investigated by optical microscopy and X-ray diffraction analysis. The results indicate that no residual carbon was available in the final RFSC. The net-shape fabrication process for the RFSC components could promote the industry applications where SiC components with complex surface and inner structure were needed. [ABSTRACT FROM AUTHOR]

In this paper, we consider two single-machine scheduling problems with the effect of deterioration and learning. In this model, the processing times of jobs are defined as functions of their starting times and positions in a sequence. For the following two objective functions, the weighted sum of completion times and the maximum lateness, this paper gives two heuristics according to the corresponding problems without learning effect. This paper also gives the worst-case error bound for the heuristics and provides computational results to evaluate the performance of the heuristics. [ABSTRACT FROM AUTHOR]

The formability of AA-2024 sheets, an aerospace grade material, in the annealed and pre-aged conditions has been investigated in the single-point incremental forming (SPIF) process. The major operating parameters, namely step size, tool radius, and forming speed, of SPIF process were varied over wide ranges, and their effect on the formability was quantified through a response surface method called as central composite rotational design. It was found that the interaction of step size and tool radius is very significant on the formability. Moreover, a variation in the forming speed does not affect the formability of annealed AA-2024 sheet. However, the formability of pre-aged AA-2024 sheet decreases with the increase in the forming speed. Furthermore, the annealed sheet shows higher formability than the pre-aged sheet. [ABSTRACT FROM AUTHOR]

During the plastic injection molding process, one of the biggest challenges is shrinkage which deteriorates the quality of produced parts. To control and reduce this defect, the essential way is to perfectly determine the variables like molding parameters. In this study, the effects of molding parameters including packing pressure, melt temperature, and cooling time on shrinkage and roundness have been investigated experimentally. Also, the relationship among initial molding parameters, the cavity pressure, and mold temperature was investigated. The results of this experimental study and analysis fulfill various requirements of plastic injection molding and clarify the relationship between molding conditions and the overall quality of produced parts. This study illustrated that packing pressure and melt temperature are dominant factors which determine the quality of parts. [ABSTRACT FROM AUTHOR]

During a manufacturing operation, exceptions may occur dynamically and unpredictably. Their occurrence may lead to the degradation of system performance or, in the worst case scenario, may interrupt the production process. The research proposes a multi-agent architecture for the capacity reconfiguration problem in a reconfigurable manufacturing system (RMS). A policy to manage capacity exchange among manufacturing lines based on due date performance is proposed. The Multi-Agent architecture was built in a simulation environment developed in ARENA® package and it is compared with a dedicated manufacturing and flexible manufacturing systems. The simulations are conducted in several demand scenarios to test the approach in a static and dynamic context. The simulation environment developed can support the planner to decide among the different manufacturing systems by the evaluation of the manufacturing performance. The simulation results, in dynamic environment, showed that the proposed approach leads to similar performance to flexible manufacturing system. [ABSTRACT FROM AUTHOR]

Friction stir welding (FSW) is a relatively new joining process and is being used commercially in several industry sectors. In small and medium enterprises, however, this novel technology has not been applied despite its remarkable advantages because of the drawbacks of FSW. A database has been assembled and drawbacks have been analyzed then solved appropriately in the Industry-Government-Academia Collaboration Project. As an outgrowth, the optimum and individual know-how of practical FSW technology could be transferred to medium and small enterprises. [ABSTRACT FROM AUTHOR]

The topic of the research is related to the domain of computer-aided manufacturing process planning. This paper deals with the problem of setup and fixture planning for the machining of box-shaped parts on the horizontal machining centres. The setup and fixture planning involves the definition of setups, the setup sequence and conceptual design of fixtures for each setup. The central topic of this research is the automation of the conceptual design of fixtures. This topic is interconnected with the setup planning, and accordingly, the aim of the author has been the integrated handling of tasks of setup and fixture planning and the finding of solution in an integrated system. Based on the workpiece model, the developed system automatically determines the setup sequence, the content of setups and the conceptual solution of fixture for each setup. The paper presents the problems of fixture solutions and the partial tasks of workpiece holding, the typical solution of partial tasks and the conditions of their application and finally offers a new method, which makes the integrated handling of tasks of setup and fixture planning and finding solution in an integrated system possible. [ABSTRACT FROM AUTHOR]

With the technology entering the nanodimension, manufacturing processes are less and less reliable, thus drastically impacting the yield. A possible solution to alleviate this problem in the future could consist in using fault-tolerant architectures to tolerate manufacturing defects. In this paper, we consider the classical triple modular redundancy (TMR) as fault-tolerant architecture for yield improvement purposes. Firstly, we compute a set of conditions to be satisfied in order to make use of TMR architectures interesting for yield improvement. Then, we prove that these conditions depend on the testability of the TMR architecture. Thus, we investigate test requirements for TMR architectures and we propose a solution for generating test patterns for this type of architecture. Finally, we propose a new way of implementing the TMR architecture in order to achieve more benefits for yield improvement purpose. This is done by partitioning the logic part and then adding voters between sub-modules. Experimental results are provided on ISCAS'85 and ITC'99 benchmark circuits to demonstrate the efficiency of the proposed approach in terms of yield improvement. [ABSTRACT FROM AUTHOR]

The classifiers with supervised learning have proved to be efficient for the distinguishing of faces on the images, speakers' identities and characters recognition. The idea of the present work is to extend their application field to failures diagnosis liable to arise during the work of complex industrial processes. For this reason, we propose to use the support vector machines classifier "SVM" This method will be applied to two systems, including a hybrid one. We will also focus on detecting the liable oncoming failures. [ABSTRACT FROM AUTHOR]

Abstract: Experimental measurements of cutting and thrust forces and chip shear plane angles have been carried out for six steels turned at a feed of 0.25mm/rev at speeds from 50 to 250m/min. The results have been successfully reproduced by finite element simulations. For this it has been necessary to include an initial yield drop from an upper to a lower yield stress in the description of the steels’ plastic strain hardening. It has also been necessary to assume flow stress to reduce non-linearly with increasing temperature in the manner proposed by Zerilli and Armstrong, up to a temperature ≈900°C above which rapid softening takes place. A comparison is made between the present work and the earlier work of Oxley and his group. [Copyright &y& Elsevier]

Abstract: A new methodology based on pulsed lasers has been developed in order to estimate wheat outer layer mechanical properties without sample preparation. Laser experiments were carried out with an Argon Fluoride (λ =193nm) excimer laser source delivering pulses of 15ns duration. Wheat grains from two cultivars were irradiated by single laser pulses with a quasi-uniform irradiation and two fluences (2.5 and 5Jcm−2). The ablation flux was characterized by environmental scanning electron microscopy before measuring the removed material on cross-sections observed by confocal scanning laser microscopy. Specific image treatment was carried out to obtain the ablation flux (amount of removed matter per pulse). Pericarp, seed coat and aleurone layer were gradually ablated under the laser conditions used in this work. Their ablation thresholds were different and could be related to tissue cohesion. Specific behaviour of seed coat layer (8μm) could be emphasised with this technique. Pulsed laser ablation could be a potential methodology to reveal indirectly wheat grain layer cohesion. [Copyright &y& Elsevier]

In complex manufacturing processes, control structure selection poses a serious challenge for the control engineer. Such systems are typically interacting, large scale and may comprise many loops. Choosing a correct control structure is not often a straightforward process, especially, if as it often is the case, one is faced with the challenge of having to integrate additional proposed control systems into an already existing plant-wide control system. Current approaches to the control structure selection problem rely either on the control engineer's experience and intuition or on solutions of difficult and non-convex combinatorial optimisation problems. A set of new computationally inexpensive graphical analysis tools based on basis pursuit regularisation methods are presented that provide significant insight into the control structure selection problem. The tools presented build a centralised controller by incrementally adding one loop at a time to the structure of a baseline decentralised controller. There are no constraints as to where new loops can be added which results in a rich class of sparse controllers. With the aid of an example, it is shown that how these tools are used directly to assess the local structural sensitivity of the problem and to identify key and important connections within the controller. [ABSTRACT FROM AUTHOR]