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2012, Organizacija
We discuss the concept of simulation and its application in the resolution of problems in complex industrial systems. Most problems of serious scale, be it an inventory problem, a production and distribution problem, a management of resources or process improvement, all real world problems require a mix of generic, data algorithmic and ad-hoc solutions making the best of available information. We describe two projects in which analytical solutions were applied or contemplated. the first case study uses linear programming in the optimal allocation of advertising resources by a major internet service provider. the second study, in a series of projects, analyses options for the expansion of the production and distribution network of mining products, as part of a sensitive strategic business review. using the examples, we make the case for the need of simulation in complex industrial problems where analytical solutions may be attempted but where the size and complexity of the problem forces a Monte carlo approach.
OR Spectrum, 2009
Discrete-event simulation and (mixed-integer) linear programming are widely used for supply chain planning. We present a general framework to support the operational decisions for supply chain networks using a combination of an optimization model and discrete-event simulation. The simulation model includes nonlinear and stochastic elements, whereas the optimization model represents a simplified version. Based on initial simulation runs cost parameters, production, and transportation times are estimated for the optimization model. The solution of the optimization model is translated into decision rules for the discrete-event simulation. This procedure is applied iteratively until the difference between subsequent solutions is small enough. This method is applied successfully to several test examples and is shown to deliver competitive results much faster compared to conventional mixed-integer models in a stochastic environment. It provides the possibility to model and solve more realistic problems (incorporating dynamism and uncertainty) in an acceptable way. The limitations of this approach are given as well.
International Journal of Simulation Modelling, 2018
JaamSim is a prominent, discrete-event simulator with an established and fast growing community of users. To the authors' knowledge, no simulation optimisation package was available for JaamSim up to now. For the purposes of this research, we developed the open-source software JSOptimizer that can be used to optimise simulation models of complex engineering systems built with JaamSim. The proposed tool utilises the jMetal framework, a well-known and validated library of meta-heuristic optimisation algorithms. The contribution of this article is twofold. First, we present the most important aspects of the proposed software JSOptimizer. Secondly, we examine a novel, multiobjective problem pertaining to a stochastic manufacturing system which involves production control and job routing decisions. Several instances of the optimisation problem are solved and the resulting local non-dominated sets are compared under various performance metrics by utilizing the functionalities of JSOptimizer. This investigation also serves as a proof of concept for the proposed software's applicability.
Computer Aided Chemical Engineering, 2005
Supply Chain Management (SCM) involves the decision-making related to resources management through the entire Supply Chain (SC), from the initial suppliers to the final customers . Many of present SCM approaches consider operations research optimisation models, which often assume centralised management and are inadequate to efficiently undertake SC dynamics and uncertainty. On the contrary, simulation-based approaches are able to deal with these two issues but they are not appropriate to optimise the SC operation. In this work, a combined framework, which offers the advantages of simulation and optimisation, is proposed and a methodology is presented in order to explicitly include not only the traditional economic criteria, but also the other concerns: environment, safety, flexibility, customer satisfaction, etc. In this way, the simultaneous consideration of multiple criteria provides a way to further explore the necessary trade-offs upon which decision-making should be based. The results so far obtained are very promising.
The integrated analysis and optimization of today's complex supply chains that combine production and distribution are highly challenging both for the academic/research community and the supply chain partners. The traditional operational research models have been proven incapable to describe the complexity of global supply chains. The development and adoption of simulation based techniques seems to be the only reliable solution for modelling and testing the efficiency of a business system, as they support decision-making by studying simultaneously the effect of various critical factors. This paper aims to develop a methodological framework that analyses, models and studies the operations of a supply chain using simulation. The proposed framework is based on Petri Nets theory; Petri Nets has been used successfully applied in the literature for a valid mathematical representation of systems with discrete time transitions. Moreover, the combination of Petri Nets with the Activity Cycle Diagrams provides a valid simulation modelling and a quite simple simulation program development. The framework is presented through its implementation on the supply chain of a Ready Mixed Concrete Unit, located in Northern Greece. Specifically, the probability distributions of the stochastic variables are estimated using historical production data and the simulation model is built using Petri Nets, Activity Cycle Diagrams and the Simul8 ® software. Then, the validity and verification of the model is tested. Statistical analysis of experiments ('what-if' scenarios) is conducted and optimal decisions are proposed accordingly, regarding technological and resource investment. Finally, the paper provides future research directions.
Optimizing Operations, 2021
The Department of Defense (DoD) operates a world-wide supply chain, which in 2017 contained nearly 5 million items collectively valued at over $90 billion. Since at least 1990, designing and operating this supply chain, and adapting it to ever-changing military requirements, are highly complex and tightly coupled problems, which the highest levels of DoD recognize as weaknesses. Military supply chains face a wide range of challenges. Decisions made at the operational and tactical levels of logistics can alter the effectiveness of decisions made at the strategic level. Decisions must be made with incomplete information. As a result, practical solutions must simultaneously incorporate decisions made at all levels as well as take into account the uncertainty faced by the logistician. The design of modern military supply chains, particularly for large networks where many values are not known precisely, is recognized as too complex for many techniques found in the academic literature. Mu...
International Journal of Services Operations and Informatics, 2011
Existing simulation tools are able to map large size supply chains and can accommodate complex random phenomena. Nevertheless, they have significant weakness in the power of decision-making. Indeed, most of the problems of decision-making are typically determined by simplified rules. For this reason, involving optimisation tools in decision-making will allow the simulation to explore the real performance of a supply chain. Motivated by the limitations of existing supply chains simulation and optimisation tools, the aim of this study is to combine them in a single tool. More specifically, we aim to develop an 'intelligent' simulation tool with an embedded optimisation tool to solve various decision-making problems encountered during the simulation of a complex supply chain. Including an optimisation tool in a simulation tool allows accurate assessment of supply chains performances and overcome the lack of powers of decision-making in traditional simulation tools.
The Romanian Statistical Review, 2017
The present study is concerned with the concept of simulation and the development of simulation models, transposed into mathematical formalism from engineering sciences into economic context, as a powerful and effective tool for managerial decision making. The applications under consideration involve deterministic systems with continuous time and states, as well as with discrete ones. There presented simulations are of type G/G/1 activity, considered to be representative for models of modern business-type of problems, as well as paradigms, concepts and the mathematical formalism from engineering sciences, which have been successfully applied to economic organization-type problems, such as the Pollaczek – Khinchin formula, Lindley’s equation, the Wiener-Hopf equation.Finally, two classical, representative methods for simulations are briefly and synthetically discussed, the Monte-Carlo method and the Metropolis method, together with the methodology of implementation via the specialize...
Journal of the Franklin Institute, 2007
This study is based on an actual simulation application project carried out for a parcel transportation company. In its current system, the company has a wide network of branches throughout the country. Although, it is good to have a large network in terms of accessibility and increasing the business volume, performing the same operations in almost every branch is costly ineffective. Consequently, the company managers considered merging several branches in the same neighborhood and carrying out most of the tasks in these central branches. As they consulted us to see if this idea is feasible or not, we decided to use simulation modeling. After carefully investigating the details of the system we developed a comprehensive model of this dynamic and complicated system and looked at the feasibility and also the limitations of their approach. After getting the results, we noticed that what they planned would not work out and developed another central branch design that could work out. Using design of experiments we obtained the behavior of the suggested system under different business scenarios. In this study, we describe the details of this interesting application of simulation modeling.
SNE Simulation Notes Europe, 2011
The paper presents simulation-based methodology to solving multi-echelon supply chain planning and optimisation problems. It is aimed to analyse an efficiency of a specific planning policy over the product life cycle within the entire supply chain and to optimise the cyclic planning policy at the product maturity phase. Software prototypes and applications are described in the paper.
Production Planning & Control, 2011
2012
The paper presents a simulation on automotive inventory and stock issue, followed by evaluated performance of automotif Sector Company, focused on getting optimum profit from supply and demand balancing. Starting by evaluating and verification of customer's document until car delivered to customer. Simulation method of performance is used to evaluate company activity. excess demand of car by customer, not eligible customer to rented a car, number of customer who served and number of customer who served including the driver, the last result is number of optimum demand that match with the stock or supply of car by the company. Finally, board of management should be making decision; the first decision is buy the new car for meet with the demand or second decision is recruit new staff for increasing customer service or customer care.
2009
The production costs reduction in a highly competitive environment is a critical success factor. In particular, in fields where outsourcing is used frequently and the impact of the material costs is high, a significant cost reduction can be achieved making more efficient value chain. Moreover, the use of outsourcing is a way to adjust production capacity depending on demand. Therefore the coordination and planning of the various rings of the chain and the estimate of the productive capability of the various production units become fundamental for a coherent evaluation of promised delivery times. More and more frequently and in greater detail the Companies at the "end of the network" require, through capacity assessment a verification of the available productive capacity of the manufacturing units, both from a quality and quantity point of view, that each single firm can dedicate to a certain type of production. In this paper it is presented a simulation model that allows the elaboration of an operative plan of production through the verification of finite capacity scheduling of resources. The model tends to minimize costs of stocking and setup , considering other production costs as constant. The simulation is a technique that allows the checking with better precision of the use of the resources with variation of the ties. This approach lead to a high performing instrument in the field of the advanced planning and scheduling through analysis of the various possible views. The auxiliary use of the optimizing tool available in the ARENA software allows an optimal solution, confirming the validity of the study of new applications of the simulative instrument for the verification of productive capacity in the short term.
This paper describes importance of simulation as a handy tool in today’s techno-commercial business environment. To strive in global market, organisations are trying to improve their performance using various optimisation tools and techniques available. Instead of evaluating every alternative in real world, simulation helps to mimic various alternatives available for optimisation and on the basis of these results decision making becomes very easy. Under the cost reduction objective, company has decided to localise i.e. manufacture sub-assemblies inhouse which were been imported previously. Localisation project will add new workstations in the existing assembly line. To ensure that the modified assembly line is optimized, various alternatives for newly added workplace as well as different worker allocation patterns were evaluated using simulation software. These results strengthen the proposal in decision making process.
2012
In this work, we propose a hybrid simulation optimization approach that addresses the problem of supply chain management. We formulated the problem as a mathematical model which minimizes the summation of production cost, transportation cost, inventory holding and shortage costs, subject to capacity and inventory balance constraints and propose a hybrid approach combining mathematical programming and simulation model to solve this problem. The main objective of this approach is to overcome the computational complexity associated with solving the underlying large-scale mixed integer linear problem and to provide a better representation of supply chain reality. The simulation-based optimization strategy uses an agent-based system to model the supply chain network. Each entity in the supply chain is represented as an agent whose activity is described by a collection of behavioral rules. The overall system is coupled with an optimization algorithm that is designed to address planning and scheduling level decisions.
2010
T he competitiveness and dynamic nature of today's marketplace is due to rapid advances in information technology, short product life cycles and the continuing trend in global outsourcing. Managing the resulting supply chain networks effectively is challenged by high levels of uncertainty in supply and demand, confl ict objectives, vagueness of information, numerous decision variables and constraints. With such levels of complexity, supply chain optimisation has the potential to make a signifi cant contribution in resolving these challenges. In this paper, a literature review -based on more than 100 peer-reviewed articles -of state-of-the-art simulation-based optimisation techniques in the context of supply chain management is presented. A classifi cation of supply chain problems that apply simulation-optimisation techniques is proposed. The main criteria for selecting supply chain optimisers are also identifi ed, which are then used to develop a map of optimisation techniques. Such a map provides guidance for researchers and practitioners for a proper selection of optimisation techniques.
This presentation covers different phases of the manufacturing system life cycle. Starting from conceptual system design to planning of operations. Material handling and logistic are the key factors in modern networking manufacturing. The author proposes use of discrete event simulation as a system design and operation-planning tool. Traditionally simulation tools have been used in the system planning and design; today the simulation models are used in all the different phases of manufacturing system life cycle. This paper presents two case studies. First case shows a modular semiautomatic assembly system planning using simulation. Second case presents a simulation tool developed for operations planning, management of production capacity and decision helping for planning of operations.
Proceeding of the 2001 Winter Simulation Conference (Cat. No.01CH37304)
Industrial & Engineering Chemistry Research, 2006
This work presents a novel approach that addresses the management of chemical supply chains (SCs) under demand uncertainty. One of the main objectives is to overcome the numerical difficulties associated with solving the underlying large-scale mixed integer nonlinear problem (MINLP). The approach that is proposed relies on a simulation-based optimization strategy that uses a discrete-event system to model the SC. Within this framework, each SC entity is represented as an agent whose activity is described by a collection of states and transitions. The overall system is coupled with an optimization algorithm that is designed to improve its operation. This strategy is a very attractive alternative in the field of decision-making processes under uncertainty, the advantages of which are highlighted with some cases of SC networks that are composed of several plants, warehouses, distribution centers, and retailers.
1998 Winter Simulation Conference. Proceedings (Cat. No.98CH36274)
In business today, re-engineering has taken a great deal of the cost out of internal corporate processes. Our factories and internal support organizations have become much more efficient, but there is still a great deal of unnecessary cost in the overall delivery system, or the supply chain. Although your corporation does not own all of the supply chain, the entire chain is responsible for product delivery and customer satisfaction. As one of several methodologies available for supply chain analysis, simulation has distinct advantages and disadvantages when compared to other analysis methodologies. This paper discusses the reasons why one would want to use simulation as the analysis methodology to evaluate supply chains, its advantages and disadvantages against other analysis methodologies such as optimization, and business scenarios where simulation can find cost reductions that other methodologies would miss.
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