International Journal of Simulation and Process Modelling (22 papers in press)
- Evaluating policies using agent-based simulations: investigating policies for continuity of care
by Gregory Ramsey
Abstract: Anticipating effects of proposed clinical policies is a difficult task. This study investigates the usefulness of agent-based simulations for evaluating clinical policies. Two policies for continuity of care for patients with type 2 diabetes are investigated using an agent-based simulation. Computational models of a dynamic decision environment were simulated to determine aggregated effects of individual care-providing agents acting to achieve clinical goals. The simulated policies were: (1) continuous care (CC), where each patient was randomly assigned a specific physician model for care across visits, and (2) opportunistic care (OC), where each patient on each visit was randomly assigned to a physician model for treatment. These policy scenarios are at the crux of a debate as to whether continuity of care needs to be administered by a single provider or by a single organisation (e.g., clinic). The study determines under which conditions CC and OC policies result in favorable patient outcomes.
Keywords: clinical policies, agent-based simulations, type 2 diabetes, continuity of care, policy simulations
Special Issue on: "
I3M 2012 "The Future of Modelling and Simulation Training, Experimentation and Decision Making,"
- Innovative models for supporting operational planning
by Simonluca Poggi
Abstract: Innovative simulation models are proposed for supporting operational planning related to CIMIC (CIvil MIlitary Cooperation) and PSYOPs (PSYchological OPerations) within complex scenarios. The paper describes these models as well as the experimentation in situations involving crisis and conflicts (i.e. Afghanistan); these models are based on the IA-CGF (Intelligent Agents Computer Generated Forces) developed by the simulation team and they have been extensively used in CAPRICORN Project (CIMIC and Planning Research In Complex Operational Realistic Network), an initiative led by the University of Genoa for EDA (European Defence Agency). The proposed models take care both of logistics and operational issues as well as of the effects on the people and interest groups; indeed, the paper proposes the simulator developed to demonstrate these capabilities, which include the communications among the stakeholders, the population models, and the effects of human factors including social and cultural aspects. The paper includes experimental results based on this simulator devoted to validate and test the models in strong cooperation with final users and SME (Subject Matter Experts); the proposed experimentation is based on design of experiment techniques, including MSpE (Mean Square pure Error) and sensitivity analysis.
Keywords: simulation for stabilisation and reconstruction; S&R; civil military cooperation; CIMIC; psychological operations; PSYOPS; human behaviour modifiers; HBM/
Special Issue on: "
I3M 2013 Cutting-edge Methodologies, Applications and Technologies in Modelling and Simulation,"
- Production function implementation in an agent-based simulation
by Roman Šperka, Marek Spišák
Abstract: The aim of the paper is to describe the seller-to-customer negotiation in the business processes (sales) of a virtual company. Based on it, we propose an innovative approach to simulate, investigate and predict some of the key performance indicators of a trading company. The methods used to implement the simulation framework in the form of a multi-agent system come out of the agent-based modelling and simulation techniques. The paper firstly presents some of the existing theories about consumer behaviour and the types of factor influencing it. Secondly,the paper characterises a multi-agent model of a virtual company, the agents participating in the seller-to-customer negotiation, and the production function. Finally, the simulation results and their validation are described. To conclude, the proposed approach with the use of seller-to-customer negotiation could properly contribute to better decision-making process of a company's management.
Keywords: system; simulation; virtual company; multi-agent system; negotiation; decision support
Special Issue on: "AMEE 2013 Advances in System Simulation"
- A comparison of machine learning techniques for medical data classification
by Lei Shi
Abstract: Research in medicine and molecular biology has accumulated enormous amounts of medical data. Such large amounts of data must be thoroughly analysed to gain useful information. Recently, many researchers have been attracted to study this problem. As an effective tool, machine learning methods are the best candidates for this challenging task. This paper aims to assess several machine learning techniques, including support vector machines, artificial neural networks, decision tree and random forest, and then to compare the performance of these methods for automated classification of medical data.
Keywords: support vector machines, artificial neural networks, decision tree, random forest
Special Issue on: "I3M 2012 The Future of Modelling and Simulation Applications in Industrial Plants, Processes and Services"
- Analysis of the operations of an intermodal barge terminal
by Lotte Verdonck, An Caris, Katrien Ramaekers, Gerrit Janssens
Abstract: This paper studies the operations of intermodal barge terminals. The objective is to increase the terminals efficiency by supporting the operational planning of the terminal operator. For this purpose, a review on general and process-specific barge terminal planning problems, discussed in current scientific literature, is provided. This theoretical knowledge is validated in practice by means of a comparison with operational planning realities at Haven Genk, a Belgian trimodal terminal. Finally, a simulation study based on Haven Genk data is performed to investigate whether vessel size and number of vessels in use have an impact on barge terminal efficiency.
Keywords: barge terminal; operational planning; discrete event simulation
- Analysis and optimisation of inventory management policies for perishable food products: a simulation study
by Eleonora Bottani, Marta Rinaldi, Roberto Montanari, Gino Ferretti
Abstract: In this paper, we analyse three traditional reorder policies, namely Economic Order Interval (EOI), Economic Order Quantity (EOQ) and (S,s), applied to five food products with different shelf-life characteristics. Particular attention is paid to fresh products with limited shelf-life, which represent three of the five products examined, and to the suitability of applying the inventory management policies to those products. An ad hoc simulation model, reproducing a real two-echelon supply chain, was developed under Microsoft ExcelTM and used to simulate the flow of the different products along the supply chain, according to the three reorder policies. From the simulation, the minimum cost setting is first derived for all policies, taking into account the total cost generated by each policy. Then, additional performance parameters (e.g., the throughput time of items along the supply chain) are computed and compared to the products constraints (e.g., the shelf-life), to assess the real suitability of implementing each policy to the products considered.
Both the supply chain modeled and the products data are derived from a real scenario; thus, it is expected that our outcomes and guidelines are of practical usefulness to inventory managers, to optimize inventory management of perishable products.
Keywords: inventory management, inventory policies, perishable products, simulation model, optimisation, supply chain
- A parametrised model of multimodal freight transportation for maritime services optimisation
by Rosa Rios Prado, Diego Crespo Pereira, David del Rio Vilas, Nadia Rego Monteil, Alejandro García del Valle
Abstract: Multimodal transport has been promoted by several transport commissions initiatives as an alternative to road transport. A key factor for improving its competitiveness is to provide private and public investors with means for evaluating and selecting the best options in terms of profitability. This paper presents a parameterization schema of a freight transport model for the assessment of a multimodal transport service in terms of its internal rate of return (IRR). Parameterization enables the application of optimization algorithms for the maximization of profitability. Finally, a case study consisting of the evaluation of a new maritime service for the interregional freight transport in Spain is used in order to verify the proposed parameterization.
Keywords: logistics, freight transport, multimodal, simulation, supply chain, optimization, IRR, decision maker, transportation planning, route planning
- A modelling and simulation approach to assessment of a negative binomial approximation in a multi-echelon inventory system
by Adriano Solis, Letizia Nicoletti, Pietro Caruso, Elisa Fazzari
Abstract: Some studies in the multi-echelon inventory systems literature have used a negative binomial distribution to approximate a critical random variable arising in the model. Graves (1996) developed a multi-echelon inventory model with fixed replenishment intervals, where each site follows a base stock policy. He proposed in the one-warehouse, N-retailer case a negative binomial distribution to approximate a random variable he referred to as uncovered demand. Computational evidence was provided to demonstrate the effectiveness of the approximation. Graves then suggested search procedures for approximately optimal base stock levels at the warehouse and N identical retailers under two customer service criteria: (i) probability of no stockout and (ii) fill rate. A separate analytical evaluation of the negative binomial approximation has been preliminarily reported elsewhere. In the current study, we apply a modelling and simulation approach to assess whether the approximation-based search procedures, in fact, lead to optimal or near-optimal stock levels.
Keywords: multi-echelon inventory model; supply chain; one-warehouse, N-retailer inventory system; base stock policy; negative binomial approximation; modelling and simulation
- Layout and process optimisation: using computer-aided design and simulation through an integrated systems design tool
by Luis Dias, Guilherme Pereira, Pavel Vik, José Oliveira
Abstract: The design of production and logistic systems is a process of managing both technical and organisational variants in order to identify the best solution for a given system. This paper discusses design issues of production systems that are applied to an internal logistic system in the automotive industry. As far as the production systems design (PSD) is concerned, three basic classes of software tools usually pertain: computer-aided design (CAD), process simulation, and information systems. However, these software tools have been used with low levels of integration. Vik et al. (2010b, 2010c) proposed integrating these software resources in production systems and developed an advanced tool called Integrated Design of Systems (IDS). The proposed IDS tool involves a wide set of functions for the most common tasks of PSD, from conceptualisation to implementation, including systems analysis (P-Q, cluster, and material flow analysis), automatic generation of simulation models, generation of alternatives for the layout of facilities and factories, material flows display, transportation system design, and iterative buffer size specification. The IDS approach takes advantage of simulation, CAD systems, and their integration. This paper will demonstrate the concept and functionalities of the proposed tool in a real industrial case study.
Keywords: integrated systems design; production systems planning and design; computer-aided design; CAD; simulation; layout optimisation
- CFD modelling of thermal distribution in industrial server centres for configuration optimisation and energy efficiency
by Pierre-Luc Paradis, Drishtysingh Ramdenee, Adrian Ilinca, Hussein Ibrahim
Abstract: The use of servers for computational and communication control tasks is becoming more and more frequent in industries and institutions. Ever increasing computational power and data storage combined with reduction in chipsets size resulted in the increased heat density and need for proper configurations of the server racks to enhance cooling and energy efficiency. While different methods can be used to model and design new server centres and optimise their configuration, there is no clear guideline in the literature on the best way to design them and how to increase energy efficiency of existing server centers. This paper presents a simplified yet reliable Computational Fluid Dynamics (CFD) model used to qualitatively evaluate different cooling solutions of a data centre and proposes guidelines to improve its energy efficiency. The influence of different parameters and configurations on the cooling load of the server room is then analysed.
Keywords: flow simulation, SolidWorks, data centres, cooling optimisation, energy efficiency, fluid mechanics, heat transfer.
- Integrated planning and scheduling built on cluster analysis and simulation optimisation
by Galina Merkuryeva, Vitaly Bolshakov
Abstract: This paper proposes integrated solutions for product delivery planning and scheduling in distribution centres. Cluster analysis, computer simulation and metaheuristic optimisation are applied to improve planning decisions at tactical and operational levels. An integrated approach to product delivery planning and scheduling built on integration of these technologies is described. A cluster analysis of product demand data of stores is used to identify typical dynamic demand patterns and associated product delivery tactical plans. Customer regional clusters are built through multi-objective optimisation. Metaheuristic optimisation techniques are applied to define optimal parameters of product transportation and delivery schedules. Here, vehicle scheduling is performed for the routed solution. Integrated solutions are illustrated and adjusted to a specific business case.
Keywords: tactical planning; cluster analysis; simulation; optimisation; metaheuristics; vehicle routing; vehicle scheduling
- Situation awareness in critical infrastructures
by Federica Pascucci, Vincenza Abate, Ludovica Adacher
Abstract: Critical infrastructure protection and situation awareness are relevant topics in the critical system domain. These issues go far beyond the academic world, involving very often the national security framework. In this contribution, a review of the most attractive approaches proposed for addressing the situation awareness problems is presented. Most of the proposed approaches are based on multi-sensor data fusion, since the awareness is achieved building a scenario using data provided by sensors spread into the systems. Humans are supposed to interact with the system, but only a few models are able to include their intervention. The review analysis is performed by considering models, architectures, and techniques adopted in each system and by highlighting their effectiveness and drawback. Finally, an example in the field of air traffic management is presented.
Keywords: situation awareness, critical infrastructure protection, distributed data fusion
- Simulation as enabling technologies for agile thinking: training and education aids for decision makers
by Agostino G. Bruzzone
Abstract: This paper describes on-going researches and preliminary results obtained about the potential of serious games for identification, development and education of specific soft skills related to agile thinking, such as what Napoleon called 'Coup dOeil'; these characteristics correspond to the capability to catch at a glance a solid understanding of the details in a scenario or the identification of missing elements in a set of information. This paper proposes an interdisciplinary research where expertise in modelling and simulation and serious gaming are mixed with skills in education and decision making development. The goal is to develop a general methodology and a set of games that could support decision makers in different sectors to develop intuition and the capability to think and understand out of personal contextual frameworks (Baisini et al., 2011 and 2010b). Preliminary experimentations are proposed by using an existing serious game, named Sibilla, to demonstrate the potential of this approach; the proposed results are also useful to direct the research towards where to focus the efforts for developing an ad hoc game designed for this very specific purpose.
Keywords: serious games, decision making, agile thinking, contextual learning
- Hybrid approach for container terminals' performance evaluation and analysis
by Letizia Nicoletti, Alessandro Chiurco, Carlos Arango, Rafael Diaz
Abstract: Turn-around time, defined as the total time spent by a vessel within the port area, is one of the most important key performance measures for a container terminal. In this article, the authors propose a hybrid approach based on simulation and genetic algorithms to investigate vessels' turn-around time in a real container terminal under different scenarios characterised by increases in container traffic and vessel traffic. The authors show how a modular simulation model integrated with optimisation algorithms can be used as an advanced support tool to identify resources, capacities, and constraints, and to identify how such constraints affect the turn-around time.
Keywords: container terminals, modelling and simulation, decision-making, performance evaluation
Special Issue on: "I3M 2012 The Future of Modelling and Simulation Training, Experimentation and Decision Making"
- A prototype for project management game development using high level architecture
by Simaan AbouRizk, Ronald Ekyalimpa, Yasser Mohamed, Farzaneh Saba
Abstract: Construction games teach students various concepts of managing project risks, making critical resource allocation and utilisation decisions, activity sequencing and other related construction issues. Past game development environments range from programs running monolithically on standalone computers to synthetic environments that support distributed modules (programs) running concurrently on different computers. This paper discusses one such environment, the Construction Synthetic Environment (COSYE) based on High Level Architecture (HLA), which has potential as a game development environment. Then a framework for developing project management games within COSYE is proposed, based on experiences from previous game developments. Examples of games discussed include the bidding game, a tunnelling game and a crane lift planning game. This framework is meant to simplify game development. The paper highlights specifications for an administrator, a player and a simulator module.
Keywords: project management games, game development prototype, COSYE, HLA, construction education
- Specification of CPN models into MAS platform for the modelling of social policy issues: FUPOL project
by Miquel Angel Piera, Roman Buil, Miguel Mújica
Abstract: Simulation transparency is becoming more crucial in the decision making process when quantitative computer tools are used to justify some strategies. E-governance is one of these areas in which the use of a Multi Agent System (MAS) to represent citizens' behaviours in a certain urban issue could foster e-participation in the design of urban policies that affect their habitat environment. The Coloured Petri Net (CPN) formalism is a promising modelling approach to foster simulation transparency by means of state space traceability tools, which has been proven to be useful for modelling system dynamics with conflict patterns. We propose a modelling methodology to represent and analyse a context-aware multi agent-based system, which tends to be highly complex. We introduce CPNs as a method of capturing citizens' preferences and affinities in front of a urban contextual change. In this paper, a way to translate the CPN semantic rules into the rules used by the agents called Turtles, links or patches in NetLogo is presented.
Keywords: transparency, coloured Petri nets, state space, MAS simulation, e-participation.
- Testing the behaviour of different inventory control policies in case of extended reverse logistics by using simulation
by Francesco Longo
Abstract: Nowadays, sustainability issues are stressing the importance of the inventory management problem in case of reverse logistics. The aim of this article is twofold: first it provides the reader with an updated and exhaustive review of the most important inventory control policies to be used when dealing with product return (reverse logistics). Second, the article aims at comparing (by proposing an advanced simulation framework called IMPRES) the behaviour of different inventory control policies (in terms of supply chain costs) extending some of the models proposed in the literature in different directions (i.e. disposal option available at any stage of the supply chain, stochastic manufacturing and remanufacturing lead times, multiple return options, multi-echelon inventory systems).
Keywords: reverse logistics, inventory management, modelling and simulation
- Proposal of a structured methodology for the measure of intangible criteria and for decision making
by Antonella Petrillo, Fabio De Felice
Abstract: Making decisions requires judgement. Judgement depends on feelings and thoughts and on the ability to interpret the information from the feelings and thoughts that arise from things happening that are inherently tacit, into attributes with different levels of intensity of preference, of importance, or of likelihood. This paper places special emphasis on the measurement of intangible criteria and on their incorporation into the resource allocation process through a proper decision making approach. In this paper, a well-known decision-making method, the Analytic Hierarchy Process (AHP) is applied to identify a quality model to evaluate the performance of Italian racecourses. The aim of the work is to provide a contribution to better understand the decision process of Italian racecourses because it is characterised by a decision process that is not well structured.
Keywords: analytic hierarchy process; DSS; performances; racecourses; absolute model
Special Issue on: "Simulation and Process Modelling in Safety and Emergencies"
- Dynamics of software systems projects during the requirements process improvement
by Aminah Zawedde, Ddembe Williams
Abstract: Requirements Process Improvement (RPI) in software systems projects has received much attention from both researchers and practitioners. RPI is aimed at systematically controlling changes in the requirements process, and making improvements that result in good quality requirements specifications at reduced costs and delivered within the specified schedule. RPI activities are dynamic and complex processes managing all changes to the requirements process. Therefore, in order to meet customer, business and regular industrial needs, organizations need to have an effective RPI that will result in quality requirements, and work within the stipulated budget and schedule. This paper explores the dynamics that exists among the factors that influence a successful RPI in order to provide the understanding required to explain how the underpinning process attributes affect the quality and associated costs of the RE specification delivered to the customer. A systematic approach for RPI has been used to provide the understanding required by process improvement teams in order to effectively undertake process improvement. The authors contend that the developed system dynamics-based quality-cost RPI model is a generic framework for an effective approach to RPI. The model allows a systematic inquiry that yields explanations and provides RPI stakeholders with a common decision-making framework. The model was validated by practising process improvement consultants and managers, and makes a contribution towards understanding the quality-cost dynamics of requirements process improvement.
Keywords: software systems; cost; quality; schedule; RPI; system dynamics modelling
- Sample average approximation method for the chance-constrained stochastic programming in the transportation model of emergency management
by Deng Chunlin, Yang Liu
Abstract: This study proposes a stochastic programming model for the transportation of emergency resources during the emergency response. Since it is difficult to predict the timing and magnitude of any disaster and its impact on the urban system, resource mobilisation is treated in a random manner, and the resource requirements are represented as random variables. Randomness is represented by the chance constraints in this paper. To deal with the difficulty in calculating the chance constraint function, we use Conditional Value at Risk (CVaR) to approximate the chance constraint, and solve the approximation problem of the chance-constrained stochastic programming by using the sample average approximation (SAA) method. For a given sample, the SAA problem is a deterministic non-linear programming (NLP) and any appropriate NLP code can be applied to solve the problem. The model and method provide a new way for the emergency logistics management engineering.
Keywords: emergency management engineering; chance constraint; conditional value-at-risk; sample average approximation; transportation model.
- Quantitative method on miners emergency response capacity
by Jiangshi Zhang, Pan-pan He, Shu-shan Gao, Jia Tao
Abstract: In order to realise optimal selection of key posts and reduce human-initiated accidents in coal mines, a fuzzy comprehensive evaluation model is established for miners emergency response capacity, together with an index system. Firstly, a hierarchical structure that has four first-level indexes and 14 second-level indexes is constructed taking account of literature dependence and safety engineering practices. Secondly, all indexes weights are determined by means of the Analytic Hierarchy Process (AHP), which is widely used to identify indexes relative importance. Thirdly, the fuzzy comprehensive evaluation method based on fuzzy mathematics is used to study each indexs weight distribution, and a total score is calculated in fuzzy evaluation. Finally, we take some coalmines as examples to illustrate the validity of the proposed evaluation model, and countermeasures can be put forward to improve miners emergency capability in accordance with evaluation results.
Keywords: miners; emergency capability; quantitative method; analytic hierarchy process; AHP; fuzzy comprehensive evaluation
- Electric vehicle industry development environment evaluation in China based on BP neural network
by Chuansheng Xie, Chenchen Zhao, Dapeng Dong, Pengyuan Zhong
Abstract: As an emerging industry of energy conservation and environment protection, the electric vehicle industry has broad prospects for development. However, it is currently in the initial stage and the development environment is complex, so it is very necessary to study the development environment. This paper combines an electric vehicle industry development environment evaluation index system with the BP neural network to establish an electric vehicle industry evaluation model. Then the indicator score values as training samples obtained from the use of expert scoring method are imported to the BP neural network evaluation model. After training and testing the neural network, this paper compares the testing results with the results based on AHP and fuzzy comprehensive evaluation method, to test the validity of the evaluation model. The result shows that evaluation model based on BP neural network can effectively improve the reliability and accuracy of evaluation results.
Keywords: electric vehicle industry; BP neural network; environment evaluation