http://www.ifac-papersonline.net/ en Copyright 08:00 PM Wednesday 22, 2012 IFAC-PapersOnline http://www.ifacpapersonline.com 08:00 PM Wednesday 22, 2012 08:00 PM Wednesday 22, 2012 ET webmaster@ifac-papersonline.net webmaster@ifac-papersonline.net http://www.ifac-papersonline.net/Detailed/44533.html 04:00 PM Wednesday 31, 1969 In this paper we address a lot splitting and scheduling problem of a Textile factory that produces garment pieces. Each garment piece is made of a set of components that are produced on the knitting section of the company. The problem consists of finding a weekly production plan for the knitting section, establishing the quantities to produce of each component (organized in one or several lots), and where and when (starting/completion times) to produce them. The main contribution of this work is the development of a constructive heuristic that generates automated knitting scheduling plans. The heuristic produces solutions very fast for a set of randomly generated instances based on real world data. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44621.html 04:00 PM Wednesday 31, 1969 Wireless Sensor Networks (WSNs) offer a diversity of applications in most of the fields, including healthcare, environmental monitoring, military and smart homes. However, most of the important applications ofWSNs cannot operate in complete isolation and therefore it is necessary to have an infrastructure for integrating WSNs with external environments (e.g., IP networks and virtual worlds). In this paper, we survey the current approaches on interconnecting WSNs with the IP networks and analyze their advantages as well as their limitations. Based on the analysis, we propose a new approach for interoperability between WSNs and external environments. Our proposed framework takes the advantages of current approaches as well as it takes into account the idea of service-orientation and application-independence. Our aim is to create a generic framework that is able to adapt with the multitude of applications running on sensor nodes and exposes WSNs as a set of web services to external environments. This paper also presents an implemented use-case for integrating WSNs with Second Life virtual world. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44571.html 04:00 PM Wednesday 31, 1969 Total Productive Maintenance (TPM) is a relatively new concept implemented in Romanian enterprises. This paper presents a method to optimize the most important indicator of the TPM concept: Overall Equipment Effectiveness (OEE). A real case study of implementing the proposed method is presented at the end of the paper. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44539.html 04:00 PM Wednesday 31, 1969 A supply chain is an alliance of independent business players, such as supplier, manufacturing, and distribution processes that perform the critical functions in order reach a business objective delivering value to customer and companies. Strategic design decisions as number of supply chain levels, numbers of nodes at each level, distance between nodes and definition of operations for each node contribute for better performance of the production and delivery of a variety of products to the customers. This paper presents an auto-part automotive supply chain redesign case study that has as objective to delivery modules to the assemble plant at lowest cost, high quality, and short lead time. It starts with a review of the legal procedures as the fees and taxes of the concerned States and after an analysis of logistics costs, values of labor, agility of the entire system and competitiveness, essential for the automobile company in the current scenario, are considered. At the end indexes of performance of the actual and proposed supply chain are compared to show the advantages of a new design. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44557.html 04:00 PM Wednesday 31, 1969 This paper presents a multi-agents approach to solve job shop scheduling problem using meta-heuristics. The job shop scheduling problem (JSP) is a traditional problem largely exploited in the operational research area through the academic research but belonging also to the domain of practical situations, especially in industrial companies. Several approaches have been used to investigate this problem that is very complex when addressing real industrial cases. The JSP is a NP-hard problem and no exact solution can be obtained in polynomial time. Meta-heuristics approaches when solving scheduling problems have proven to be very effective and useful in practical situations. Among them, Tabu Search (TS) and Genetic Algorithms (GA) have been used to solve optimization problems with success. The main reason is that these algorithms have good performance in terms of solution quality and execution time, when compared with optimization or simple heuristics techniques respectively. In this sense, the multi-agent approach proposed in this paper combining these algorithms brings new perspective to solve this kind of problem. In this paper a multi-agent approach based on A-Team that combines TS and GA and other specific agents is presented to solve the JSP. Results for benchmark problems from the literature are presented aiming to demonstrate the applicability of the proposal. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44495.html 04:00 PM Wednesday 31, 1969 In this paper, we address the problem of allocating a set of tasks to a set of operators, in labor intensive work environments such as manufacturing of clothing, in order to maximize the performance of the underlying production system. First, we modelize the problem as a mixed integer problem by adopting the point of view of the company through a multi-criteria approach. Two objectives are considered: minimizing the total production time and maximizing the quality of products. A critical analysis of the results shows an imbalance in the workload distribution among operators. This analysis led us to propose an approach which takes into account the workload balancing among operators. We study two types of balancing: (1) balancing in terms of temporal loads and (2) balancing in terms of assigned tasks’ number. The result is an integrated model allowing decision makers to find the best compromise between the company’s total performance in terms of production time and quality, and the interest of operators in terms of workload. This integrated model was developed and implemented as a decision-making tool that helps companies to make decisions about training of operators. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44521.html 04:00 PM Wednesday 31, 1969 We present in this paper a new formulation of the Capacitated Lot sizing and Scheduling Problem with Sequence Dependent set up cost and times (CLSPSD) problem, well known as an NP-Hard problem. We formulate the problem as a non linear model and use it to modify a lot sizing problem described in literature and applied to a real-life problem of a Canadian paper maker where the paper machine represents the bottleneck resource and consequently requires an efficient production planning approach optimizing resource utilization and minimizing production, setup and inventory costs. In these previous works, the dependency of the costs and times with the production sequences isn’t thoroughly dealt with. We prove that by really treating the problem of determining the production sequences, we handle to considerably reduce the supply chain total cost. This cost includes production costs, inventory holding costs, start up and setup costs. The reduction in the total cost varies from 6 to 52% when setup costs vary from 20% to 200% of inventory holding costs. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44547.html 04:00 PM Wednesday 31, 1969 Abstract: It has long been accepted that fish and seafood contribute positively to human health and consumer well-being. However, supply of seafood from wild catches steadily decreases and aquaculture gradually fills the gap of an ever increasing seafood market. In fact, aquaculture has been recognized as one of the fastest growing industries worldwide raising concern regarding fishmeal stock sustainability. This paper presents a profit optimization decision support tool for the Eastern Mediterranean offshore aquaculture industry, enabling just-in-time production of fish stock with minimum slack of mature fish stock in breeding cages. In detail, (a) a simulation model of involved cost elements is introduced, enabling (b) model development. Finally, a case study application of the model is presented. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44519.html 04:00 PM Wednesday 31, 1969 Current economic crisis severely affected construction industry across the Globe. Major construction companies seek product differentiation through improved quality. However, Quality Assurance applied to the construction industry proves to be a challenging task since construction projects are highly customized constituting application of Statistical Process Control principles extremely difficult. Within this context, this paper presents the ongoing activities relating to the development of a real-time quality assurance tool for the Cyprus construction industry. The framework of this tool comprises of (a) a model of the construction process, (b) a list of construction processes, (c) a checklist and (d) an application methodology. Further work to the tool completion is also described http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44497.html 04:00 PM Wednesday 31, 1969 The understanding and applying of knowledge can be difficult if it is isolated from the context under which the knowledge is generated and managed. Despite the importance of contextual information, there has been limited support for utilizing context in existing knowledge management solutions. This paper presents a set of integrated services for context aware enhancing of knowledge and knowledge management: monitoring services monitor human computer interaction to implicitly capture their interactions with the explicit or implicit data; context extraction services extract activity centric knowledge context from the monitoring data, as well as support users to manage their knowledge-based activities; knowledge enhancing services enhance knowledge and knowledge management by taking into consideration the context and topic of the knowledge-based activity. The services are provided in a loosely coupled service oriented framework which can be easily integrated with existing information and knowledge management systems to maximize its usability and extendibility. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44619.html 04:00 PM Wednesday 31, 1969 Structural health monitoring has long been identified as a prominent application of Wireless Sensor Networks (WSNs), as traditional wired-based solutions present some inherent limitations such as installation/maintenance cost, scalability and visual impact. Nevertheless, there is a lack of ready-to-use and off-the-shelf WSN technologies that are able to fulfill some most demanding requirements of these applications, which can span from critical physical infrastructures (e.g. bridges, tunnels, mines, energy grid) to historical buildings or even industrial machinery and vehicles. Low-power and low-cost yet extremely sensitive and accurate accelerometer and signal acquisition hardware and stringent time synchronization of all sensors data are just examples of the requirements imposed by most of these applications. This paper presents a prototype system for health monitoring of civil engineering structures that has been jointly conceived by a team of civil, and electrical and computer engineers. It merges the benefits of standard and off-the-shelf (COTS) hardware and communication technologies with a minimum set of custom-designed signal acquisition hardware that is mandatory to fulfill all application requirements. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44585.html 04:00 PM Wednesday 31, 1969 A methodology for designing control systems for real time applications is presented. It is proposed to have a first stage of assisted design of nominal systems with simulation based verification of the achieved performances. The control algorithm will then be improved by robustification to reproduce as good as possible the performances obtained in simulation on the real time process. Finally, a supervisor is implemented to optimize the thermo-energetic process and to compute the best choice for the reference signals. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44523.html 04:00 PM Wednesday 31, 1969 Aggregate production planning problems are found in an intermediate level of a hierarchical decision process. They are used to anticipate managerial strategies related to the future use of resources of the company. Optimal plans and production scenarios can be provided by solving mathematical models, which are formulated to represent these problems. This paper introduces a managerial decision support system, based on Excel spreadsheet, to deal with aggregate production planning problem. Some computational features of this tool are presented. A case from literature is used as an example to illustrate other aspects of the tool. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44517.html 04:00 PM Wednesday 31, 1969 In this paper, we study two information shared simultaneously, the first one coming from the upstream and the second coming from the downstream of the supply chain. We treat the case of a multi-echelons multi-products serial supply chain. This chain is made up of one supplier, one warehouse, one retailer and several customers. Thus, we develop a model to study various scenarios of information sharing. We focus our approach on the decentralised decision, in which, the goal of each link is to minimise its own logistic cost. The difference between these costs shows the value of the studied information sharing and represents the contribution of a scenario compared to another. The proposed model is solved by ILOG CPLEX integrated in JAVA program. The output results are the optimal cost in each studied situation. The numerical experimentation proves to validate contribution of our approach. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44503.html 04:00 PM Wednesday 31, 1969 This contribution reports on an optimization framework for the formulation and the solution of batch scheduling problems. The problems are graphically modeled as extended resource task networks (eRTN). The extended resource task networks are automatically translated to timed automata (TA) and are composed by parallel composition to form a global automaton that represents the complete scheduling problem. An efficient cost-optimal reachability analysis is performed on the global automaton to derive the schedules. The schedules are presented graphically as Gantt-charts to the user and can be revised when required. The main advantage of this approach over standard mathematical programming techniques is the intuitive graphical and modular modeling and the ability to compute solutions within reasonable periods of time. The proposed framework is tested on a scheduling problem in a pipeless plant to demonstrate a successful application. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44611.html 04:00 PM Wednesday 31, 1969 The paper analyses some of the commercially available solutions for casting small-size metallic parts and outlines possible solutions that would reduce the cost of such systems while maintaining a high performance level. high performance level. One typical application area for small-size parts is human prosthetics, so the commercial casting machines analysed here are used mainly in this application domain. The paper shows how high-cost systems added to the machines for providing protective atmospheres can be replaced by low-cost solutions with the same results in terms of part quality. Moreover, a solution is described that avoids the typical drawbacks of the currently used casting machines and improves the casting performance, without significantly increasing the cost of the casting system. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44549.html 04:00 PM Wednesday 31, 1969 The paper presents a case study on simulation modelling and analysis of a real production line operating in an electronics company. Simulation technique is applied to analyse the existing manufacturing system and detect factors with significant impact on its capacity. The analysis aims to improve the allocation of available production resources to maximize the average capacity of the system. A full factorial design has been applied as a simulation analysis tool. Then, a new system design is proposed to enhance the overall performance and is verified using a simulation model. The simulation system WITNESS has been used to complete this study. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44525.html 04:00 PM Wednesday 31, 1969 The Vendor Management Inventory (VMI) is an integrated approach for customer-supplier coordination in which the supplier is responsible for the management of inventory at the retailer. In this paper, we consider the three periodic inventory policies applied within the framework of VMI approach. The aim is to determine the best policy that minimize the total cost composed by the production cost, the inventory cost at the customer and the supplier and the distribution cost http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44597.html 04:00 PM Wednesday 31, 1969 This paper compares the performances of genetic operators for the Capacitated Vehicle Routing Problem (CVRP). Two representations and some crossover and mutation operators are considered. Design of Experiment (DoE) is used to identify the best combination of the studied GA components. The goal is to determine the combination of features that maximizes the efficiency of the algorithm. Results provided from a computational experiment over common benchmarks showed which parameters and genetic operators affect the quality of provided solutions. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44509.html 04:00 PM Wednesday 31, 1969 Currently the focus of planning and designing intralogistic systems lies on the technical quality rating in the form of maximum fulfilment of the mechanical requirements. This compliancy is often achieved by oversizing the mechanical components. A re-orientation in designing such systems is especially necessary because of the multitude of electrically-driven components. The current guidelines for embodiment design for intralogistic systems are not sufficient to optimise such plants regarding their service conditions. That is why adapted statistical models have been developed with the help of DoE based on measurands. These models conduce to generate new guidelines for embodiment design for such plants. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44535.html 04:00 PM Wednesday 31, 1969 In this paper, the requirements of industrial solutions to plant-wide planning and scheduling problems are discussed. The state-of-the-art algorithms for the coordination of local schedulers are reviewed and a new heuristic method is presented that utilizes the existing distributed scheduling algorithms by considering the coupled due dates and release dates in the distributed schedulers and by penalizing the slacks between the individual optimized schedules and the linking variables iteratively. The performance of the proposed coordination algorithm is evaluated for a prototypical distributed production scheduling problem which consists of two MILP scheduling models. The numerical results show that the proposed coordination scheme is superior compared to fully decentralized and to centralized scheduling algorithms and to other cooperative scheduling methods with respect to solution quality and computational effort. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44531.html 04:00 PM Wednesday 31, 1969 The availability and reliability of intralogistic systems depends significantly on the maintenance of these systems which demands modern maintenance concepts. Hence condition-based maintenance concepts are a very important development. To determine the condition of intralogistic systems a holistic concept has been developed, which combines mobile and stationary sensor units. Mobile units travel along with the regular containers on the conveying system and gather several data. Additional data is collected by the stationary sensor units. Each sensor unit, either mobile or stationary, pre-evaluates the data and only necessary data is transmitted to a central evaluation unit. By using the concept it becomes possible to determine the condition of an intralogistic system. This paper introduces measurement techniques which can be used in this context. Furthermore the new developed monitoring concept will be explained by using a common intralogistic system as an example. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44559.html 04:00 PM Wednesday 31, 1969 The occurrence of failure in a safety critical engineering system can be reduced through the use of preventive maintenance (PM). Each time a component of the system is maintained its effective age is reduced; the extent of this age reduction depends on the effectiveness of the PM known as the improvement factor. While some components may need to be maintained every PM interval T, typically most components will possess a PM interval which is a multiple of T (αT), where α is the coefficient of maintenance interval (CoMI). Where PM completely rejuvenates the component being maintained, it is termed perfect preventive maintenance (PPM). This paper investigates the effect of PPM on system reliability, unavailability and cost. Firstly, a model of the effect of PPM actions on the reliability, unavailability, and cost of components, calculated using a Weibull distribution, is established. Secondly, HiP-HOPS, a semi-automatic method for analyzing system dependability (i.e. safety, reliability and availability analysis), is extended to consider PPM of components in a system. Finally, an evolutionary optimization algorithm, using HiP-HOPS, is applied to PM scheduling. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44603.html 04:00 PM Wednesday 31, 1969 This paper presents the findings of an evaluation of an innovative ICT tool (Melodie) for the generation of ideas in the early stages of innovation. An early prototype of Melodie was experimented with in two workshops. The results of this testing of Melodie are reported in the paper. The paper analyses the number, quality and improvements made to the ideas generated during the two workshops. It concludes with recommendations for ICT tools designed to support the idea generation process. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/44567.html 04:00 PM Wednesday 31, 1969 In this paper, we address the leather nesting problem that arise typically in the automotive companies. In this problem, irregular shapes (parts of car seats) have to be cut from another larger shape (natural leather hide). The problem is defined over two dimensions, and all the shapes are irregular and may contain different quality zones due to the natural origin of the leather hides and to particular quality requirements for the different parts of the seats. Our study is based on the real case of a large multinational company. We explore different approaches to solve this problem based on constructive procedures. The details of each of these procedures are discussed. We also briefly describe how to use the no-fit polygon in the context of these particular nesting problems. Some preliminary results on real instances are discussed at the end of the paper. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif