International Journal of Simulation and Process Modelling (19 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
- Using simulation in verification of a mathematical model for predicting the performance of manual assembly line occupied with flexible workforce
by Atiya Al-Zuheri, Lee Luong, Ke Xing
Abstract: Designing a dynamic system with inherent randomness requires a predictable and dependable mathematical model accurately representing the essential aspects of real systems. So it is necessary to establish a confidence level in the mathematical model of this system by carrying out a verification process for this model to collect evidence. This paper deals with verification of the mathematical model designed for the predication of performance of manual assembly-lines occupied by a flexible workforce referred to as walking worker(s) assembly line (WWAL). To verify the mathematical model, the model was applied to an illustrative industrial example. Also experiments carried out on this example were simulated using a software package. Then, the predicted results of the mathematical model were compared with simulation results. Comparison leads to the verification of both the accuracy and the serviceability of the mathematical model developed.
Keywords: manual assembly line, WWAL, mathematical model, simulation, verification, randomness
- Modelling methodology for the simulation of manufacturing systems
by Reda Tajini, Saâd Lissane Elhaq, Ahmed Rachid
Abstract: Facing an increasingly competitive environment, companies must continually improve the performance of their production systems to respond to consumer demand that is increasingly unpredictable, unstable, and with competitive prices. This article is intended as a contribution to finding a solution to an emerging problem in the management of manufacturing flows in recent years, where product diversity, shortened lead times, and strong competition make the aspect of the 'flow' of goods from supplier to end customer a central one. In this perspective, the aim of this paper is to develop a flexible modelling environment for the simulation and analysis of production systems. This environment enables the decomposition of the production system, by offering generic and modular concepts for modelling the physical processes as well as the control processes to simulate the manufacturing processes as a whole. These concepts are specified and modelled using an object-oriented approach, such as the UML.
Keywords: manufacturing systems, manufacturing modelling, model reusability, model replication, simulation, optimisation, control systems, decision making, performance evaluation, UML, industrial case study.
Special Issue on: "Simulation and Process Modelling in Safety and Emergencies,"
- Managerial equity incentive, corporate risk-taking and corporate performance
by Jianghong Zeng, Linping Tan, Xiaohong Chen
Abstract: Based on data from the equity incentive plans of Chinese firms listed on the stock market between 2006 and 2011, this study empirically investigates the relationship between managerial equity incentive, corporate risk-taking and corporate performance. The paper first uses the volatility of corporate earnings in order to measure the degree of corporate risk-taking, and the findings suggest that there is a significantly positive association between managerial equity incentive and corporate risk-taking. Moreover, compared with lower level staff, the risk-taking effect on managers is stronger. Additionally, the degree of corporate risk-taking of the sample in China is low. Therefore, an increase in the level of corporate risk-taking can considerably increase the firms value. This paper also uses the volatility of stock returns as a proxy variable of the degree of corporate risk-taking, and the findings do not change substantially.
Keywords: executive stock options; risk-taking incentives; firm value
- Research on probability of default prediction based on loan companys credit fund trading behaviours
by Bo Hong, XingSheng Xie, HaoMing Guo
Abstract: The probability of default (PD) is an important parameter to quantify credit risk, which is the foundation in construction of the internal rating-based (IRB) systems of commercial banks, and is usually impacted by some less frequent accidents, such as market factors or the macroeconomic climate changes. The traditional approaches to estimate PD, such as expert method or statistical pattern classification, are heavily dependent on annual financial reports, which are usually provided by the borrow-customer themselves, and can lead to unreliability and long time lags in forecast. In the light of the business schema of credit fund expenditure surveillance in some commercial banks in China, this paper proposes a Support Vector Machine (SVM) classifier model to predict PD based on a set of loan fund expenditure behaviour features. Quite different from the traditional PD classifier models, which are based on financial indicators of factors, our SVM classifier is constructed based on a set of loan fund expenditure behaviour features, which can be directly collected from the fund trading databases of commercial banks in time. For the sake of modelling effect comparison, both the Logistic model and the SVM are used in this paper to classify and predict PD. The Logistic regression classification accuracy is near 84.6%, whereas the SVM classification accuracy rate can be up to 89.4%.
Keywords: climate changes; probability of default; credit risk; classifying and predicting; credit fund trading behaviours
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 "Modelling and Applied Simulation Multi-Perspective and Multidisciplinary Approaches,"
- An integrated approach for demand forecasting and inventory management optimisation of spare parts
by Mattia Armenzoni, Gino Ferretti, Roberto Montanari, Eleonora Bottani, Giuseppe Vignali, Federico Solari, Marta Rinaldi
Abstract: In this paper, we develop and test an advanced model, based on discrete-event simulation, whose purpose is to forecast the demand for spare parts during the whole lifetime of a complex product, such as an industrial machine. To run the model, the relevant data of the product (i.e., the industrial machine) manufactured by a targeted company should be collected. With those data, the model provides an estimate of the spare parts the company will have to supply during the machine lifetime, and therefore of the optimal level of spare parts inventory the company should keep available. The data provided by the model are subsequently applied to a case example, referring to a hypothetical company, manufacturing industrial plants. The application is carried out considering two scenarios, i.e. a traditional and an advanced approach for demand forecasting, this latter reflecting the circumstance where the company makes use of the proposed forecasting method to estimate the spare parts demand. The comparison of the outcomes obtained in the two scenarios highlights the efficiency and resolution capacity of the model developed. Moreover, from the application, some important considerations are drawn as regards the potential savings that can be achieved by means of an advanced demand forecasting method, such as that enabled by the model developed in this paper.
Keywords: spare parts, simulation, demand forecasting, stock management.
- An agent-based electronic market simulator enhanced with ontology matching services and emergent social networks
by Virgínia Nascimento, Maria João Viamonte, Alda Canito, Nuno Silva
Abstract: AEMOS is a simulator that aims to support the development of agent-based electronic markets capable of dealing with the natural semantic heterogeneity present in this kind of environment. AEMOS simulates a marketplace that provides ontology matching services, enhanced with the exploitation of emergent social networks, enabling an efficient and transparent communication between agents, even when they use different ontologies. The system recommends possible alignments between the agents ontologies, and lets them negotiate and decide which alignment should be used to translate the exchanged messages. In this paper, we propose a new ontology alignment negotiation process, which promotes the reuse and combination of already existing alignments, as well as the involvement of business agents in the alignment composition process. With this new model, we aim to achieve a higher adequacy of the used alignments, as well as a more accurate and trustful evaluation of the alignments.
Keywords: agent mediated e-commerce, agent-based simulation, semantic interoperability, ontology alignment negotiation, ontology alignment evaluation, emergent social networks, social network based recommendations
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"
- 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
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