1,720,975 research outputs found
A proposed correction for the expected service level in the economic order quantity (EOQ) model under relaxed demand assumption
No full textThe economic order quantity (EOQ) and the economic production quantity (EPQ) are well-known and commonly used inventory control techniques. The standard results are easy to apply but are based on a number of unrealistic assumptions. One of the assumption is that the demand is normally distributed in any interval. In several practical cases the assumption about independence of successive demands, and consequently demand normal distribution in any interval, is not supported by real data. This paper investigates the effects on the expected service level (SL) after relaxing normal distribution assumption on the demand. The present work shows a possible strategy to use classic inventory model, such as EOQ/EPQ model, adopting simulation analysis to quantify model performances under relaxed assumptions
An improved step on evaluation of using a generic simulation package for processes to support SPR techniques as PERT and CPM
No full textThis paper represents an attempt to evaluate how a software tool to model and simulate process can support typical activities that any Project Manager commonly perform, and to enforce his work. In detail, It will be represented the whole work of programming activities, resources scheduling (man work especially), and their definition in team; moreover, we will see costs definition and planning, and the related control activity, and finally, periodical activities of progress control, and the following corrective actions. Structure, logics, any parameter and terminology in the model have been inspired to Network Programming Systems (NPS) like PERT, CPM, Man Scheduling, RAMPS, etc., of whom has been kept attitudes, conditioned just by specific most relevant needs in our contest and, stimulated, by opportunities offered by specific software simulating tool adoption. The case of project and process we referred to, is the activities flow deployed to reply to a commercial proposal and related price estimation for some equipment for tiles production in the ceramic field, and, under hypothesis of acceptance, the necessary following work flow to design, to produce and to supply and test at the customer plant. We adopted this hypothesis based on the big experience with this kind of equipment and of plants in this field, that made easier focus on the idea and on example we built, and to validate the hypothesis; on other hand, because in the case and contest we proposed, it should be more justified the burden to represent in a simulating model the entire flow of activities related to the project, in terms of time, cost, and effort, and should be easier replicate some part of the model structure, logics, and others, because of analogies that distinct project should present. Under these considerations, it’s possible obtain some structural repeatability, also if in light and apparent opposition with characteristics of uniqueness that each project has, under the most commons definitions about PM in literature. The use of a simulating “general purpose” SW should be achievable also to SME’s present in a so large amount in the Italian contest. Software tool is Arena of Rockwell
A proposed framework to introduce Lean Thinking in Healthcare Services
No full textHealthcare services need, in all industrialized countries, an important part of the economic resources and ensuring sustainable healthcare services is critical for governments. Lean Production and Lean Thinking practices and concepts proved to be useful to improve performances and reduce costs in many industrial sectors. Lean Thinking generates positive results in services too, with some experiences even in healthcare. The present paper provides a literature review about Lean Thinking in healthcare and describes a work in progress experience of Lean implementation in healthcare services in Italy. The Lean practices adopted, the intervention areas and the results are analyzed to point out positive and negative aspects of each case study. Starting from this analysis a framework to introduce Lean in Healthcare Services is proposed
Analysing the ceramic sector using processes and simulation models
No full textIndustrial simulation involves making a virtual representationof a complex entity such as a ceramic company.Without needing to interact physically with the plant, thistechnique allows technical and economic performanceindicators to be evaluated, plant engineering andorganisational alternatives to be tried out and the mostsuitable solutions found for reducing investment andoperating costs and limiting industrial risks. These analyses areperformed by means of dedicated software platforms thatcreate a model of the company and its processes
ANALYSIS OF INDUSTRIAL PROCESSES BASED ON INTEGRATION OF DIFFERENT SIMULATION TOOLS
No full textThe present paper provides an example of software tools integration in order to perform simulations incomplex industry models, such as a ceramic tile manufacture. The first part of the paper presents thefeatures of the two simulation tools adopted: AutoModTM and VirtES. AutoModTM is a commercial suiteof simulation tools witch provides an environment easy to develop highly accurate models for analysis.VirtES simulation tool was developed by the Industrial Plants Research Group of the Department ofIndustrial and Civil Engineering (DIMeC) of the University of Modena and Reggion Emilia. Modelsdeveloped in VirtES are useful to investigate macro Key Performances Indicators (KPI), such aseconomic indicators. The integrated used of VirtES and AutoModTM allows to perform accuratesimulation at line production level developed by AutoModTM in multiple virtual scenarios created byVirtES
A modular modelling approach to stochastic simulation of production – logistic systems
No full textThe economic scenario today is highly competitive in terms of costs and number of competitors, so it isnecessary to adopt strategies that allow the constant improvement of manufacturing processes withinthe spending constrains. Simulation models are useful to support and drive company management inimproving the performances of production and logistic systems. The costs of simulation modeldevelopment could be reduced by the reuse of some of its parts. This work presents a case studyconcerning stochastic modeling of a small manufacture operating into the wood products field. Amodular simulation model composed of reusable sub-models has been developed using AutoModTMsoftware package. The aim of the modular architecture is to allow the use of sub-models in differentproduction systems with little changes, decreasing the costs of development in order to became moreaffordable in a SME (small medium enterprise) contest
Simulation for safety engineering: A comparison between experimental data and fire models
No full textA comparison analysis has been conducted between experimental data of a concrete structure and three different models developed with CFAST, by NIST. This work concentrates on the possibility of modeling simplified fire objects. Full-scale experiments are simulated by two-layers zone models. Through a reverse approach on heat release rate estimation, a comparison between different models is reported analyzing time to flash over, maximum temperature, shape of the time-temperature curve. The possible use of these models as an engineering design tool is carried out. Results show that different ventilations lead to an uncertain time-temperature response. The benefits that should come from decomposition of fire load into many fire objects is counterbalanced by reduced accuracy due to increased model complexity and interactions between fire plumes. © 2013 DIME UNIVERSITÀ DI GENOVA
A stochastic simulation approach for production scheduling and investment planning in the tile industry
No full textThe present paper aims to develop a simulation tool for tile manufacturing companies. The paper shows how simulationapproach can be useful to support management decisions related to production scheduling and investment planning. Particularlythe aim is to demonstrate the importance of an information system in tile firms. The Factory Data Model (FDM) parameter isused to describe the activities in ceramic tile industries operating in different European countries. A process- based analysis oftile manufacturers is undertaken and individual company performance is quantified by Key Performance Indicators (KPI). Theoverall model is composed of different processes, which are coded into Scilab environment and matched together to arrange astochastic simulator. The simulations results are used to show how management decisions can significantly effect the KPIs. Thesimulations highlight the effects on KPIs of three specific parameters: the length of scheduling period, the quantity of stockneeded and the reliability of the information system supporting orders. The results clearly show that the effect of allowing thepresence of unattended orders within the outstanding orders list always has a remarkable negative influence on KPIs. Resultsalso suggest that the presence of sub-groups of homogeneous tiles, based on colour variation, is one of the most importantfactors affecting a tile manufacturer’s performance. The results of the simulations have two different practical implications.Firstly, they demonstrate the importance of information systems in tile companies, suggest to evaluate investment ininformation technology and indicate the value of promoting an information culture in the entire work forces. Secondly, theyshow the potential of simulation tools development to support decision making in a BPR (Business Processes Re-engineering)scenario
Lean Production in the ceramic industry: growth opportunities
No full textI profondi cambiamenti imposti dalla globalizzazione a cui si sommano, oggi, gli effetti della crisi economico-finanziaria impongo alle aziende manifatturiere una ristrutturazione sia dei modelli organizzativi sia dei processi produttivi alla ricerca di una ritrovata competitività.Anche il settore ceramico viene sollecitato al cambiamento da una duplice e, per certi versi, contrastante esigenza. Da un lato la frammentazione del mercato impone lo sviluppo di un numero crescente di prodotti con cicli di vita che di anno in anno diventano più brevi. Dall’altra la presenza di una agguerrita concorrenza e le crescenti difficoltà nel reperimento di risorse impongono una modernizzazione dei processi produttivi tesa al contenimento dei costi tramite l’adozione di sistemi di produzione snella. La situazione odierna nel settore ceramico, per quanto riguarda la Lean Production (LP), vede ancora una scarsa diffusione delle pratiche tipiche della produzione snella. Il termine produzione snella (dall'inglese lean manufacturing o lean production) identifica una filosofia industriale che mira a minimizzare gli sprechi fino ad annullarli. Il processo produttivo, quindi, viene trattato in modo globale al fine di ridurre al massimo la complessità della produzione puntando sulla sua flessibilità e coinvolgendo fin dall'inizio tutte le funzioni aziendali
Simulation models to support galb heuristic optimization algorithms based on resource balancing based on multi objective performance index
No full textThe following paper face with an approach to analyse a multi model manual assembly line, and the following heuristic algorithm to optimize the scheduling of tasks to the available stations, respecting of a set of restrictions, as task/station obligation, and aiming to optimize a multi objective function, based on time, balancing utilization rates, and line balancing costs elements. This problem can be considered as belonging to the wide area of GALB Problems. Some strategy about resource scheduling opportunities has been considered. The original referable configuration of the considered system is an assembly line with six stations, and with six operators. In the present step, the solution we experimented, shows a redundant (doubled) number of stations, to be a more flexible solution compared to previous solutions, with a layout too much specific and referred to the particular tasks and constrains profile, based on real data. © 2013 DIME UNIVERSITÀ DI GENOVA
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