International Journal of Simulation and Process Modelling (18 papers in press)
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.
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
Special Issue on: "ICLS-2012 Simulation and Processing of Large Scale Systems"
- ComplexSim: a flexible simulation platform for complex systems
by Fabrizio Messina, Giuseppe Pappalardo, Corrado Santoro
Abstract: This paper describes ComplexSim, a C-based simulation platform to support the study of P2P systems and complex networks. Its architecture is based on two layers: the Parallel Simulation Kernel manages the execution of simulations on SMP systems, by supporting the definition and the scheduling of tasks and events with a clean API; the Complex Network Data & Runtime manages the definition of a complex network as a graph of entities with user-defined attributes and runtime behaviour. The paper describes ComplexSim architecture as well as the provided API. Moreover, some experimental results are reported, showing that, also in the case of huge complex networks having hundred million nodes, ComplexSim features better performances, in terms of memory consumption and processing times, with respect to similar solutions.
Keywords: complex networks; complex systems; peer to peer; overlay networks; simulations; pthreads; threads; symmetric multiprocessor systems; SMP; parallel programming; application programming interface; API; dynamic graphs; memory consumption; processing time.
- Concurrent simulation in the cloud with the mJADES framework
by Antonio Cuomo, Massimiliano Rak, Umberto Villano
Abstract: In this paper we discuss the design and implementation of mJADES, a new simulation engine that runs on top of an ad-hoc federation of cloud providers and is designed to perform multiple concurrent simulations. These features make mJADES an attractive environment for the simulation of complex systems, in which it is often desirable to perform many simulation runs, either for statistical validation or to compare the system behaviour in several different conditions. Given a set of simulation tasks, mJADES is able automatically to acquire the computing resources needed from the cloud and to distribute the simulation runs to be executed.
Keywords: discrete-event simulation; cloud computing; concurrency; platform-as-a-service; process-oriented simulation
- Multiple project portfolio scheduling using recurrent neural networks
by Dimitrios Tselios, Ilias Savvas, M-Tahar Kechadi
Abstract: This work is devoted to the portfolio project management problem and more precisely it is focused on IT portfolios' management. The problem is modelled as a multi-purpose job shop problem. Contemporary organisations such as IT companies define a careful planning to perform a set of projects that share common resources. These projects must, therefore, be handled concurrently. In this study, we review the literature and develop a system based on multi-objective problem modelling. We use a recurrent neural network (RNN) technique to look for optimal or near-optimal solutions to the derived optimisation problem. We first apply a greedy algorithm to find an initial feasible solution. This solution is then fed to the RNN. We implemented our approach and evaluated it on some well known benchmarks. The experimental results obtained were very promising.
Keywords: project portfolio; job shop scheduling; neural network; multi-objective; greedy algorithm
- Energy and distance adaptive clustering algorithm for 3D wireless sensor networks
by Nan Jiang, Yan Guo, Yueshun He
Abstract: How to use the limited energy of sensor nodes efficiently and evenly is a significant issue which needs great consideration in the research on Wireless Sensor Networks (WSNs). After researching, we find that some factors, such as the residual energy of node, the distance from node to Base Station (BS), are critical for the network lifetime. Further, combining with the practical application of WSN in three-dimensional space, this paper proposes a three-dimensional network, based on the energy and distance adaptive clustering (3D-EDAC) algorithm. In the following simulation experiments, we compare the network lifetime of 3D-EDAC with the reconstructive LEACH protocols from different aspects, and calculate the optimum cluster number of 3D space. These experiment results demonstrate that the 3D-EDAC algorithm has higher energy efficiency in different network conditions, and is more competent to prolong the networks lifetime.
Keywords: wireless sensor networks; three-dimensional space; 3D-EDAC; LEACH
- Research of data fusion methods of compressed sensing-based orchard monitoring system by wireless sensor networks
by Chuanyun Wang
Abstract: A novel data fusion method for monitoring the fruit growth environment is proposed, combining the model based on parameter evaluation method with the compressed sensing technique and taking Gannan navel orange as an example in this paper. The model based on parameter evaluation is used to extract the space-time characteristic information of the fruit growth environment. The distributed compressed sensing (CS) technique is used to significantly reduce the amount of data transmission, improve the accuracy of information, and prolong the lifecycle of the network. Accordingly, an experiment platform of wireless sensor networks (WSN) is built for sampling accurately the parameters of the fruit growth environment in real-time. A scientific management programme is developed to optimise the fruit growth environment, according to the proposed parameter model. It is helpful for spreading the practical application of WSN in the modern management of orchards.
Keywords: orchard; wireless sensor networks; compressed sensing; data fusion
- A social similarity-aware multicast routing protocol in delay tolerant networks
by Xia Deng
Abstract: In Delay Tolerant Networks (DTNs), multicast is widely adopted for emergency notifications in crisis environment and data scattering under military rescue situations, as it has better robustness and resource usage. Although the topology of DTNs usually changes quickly, they also demonstrate relatively stable social characteristics, e.g. the social similarity. In this paper, a Social Similarity-aware Multicast routing protocol (SSM) is proposed, in which the social similarity is quantified as the probability of the encounter of two nodes in the future based on the number of common neighbours in the history. We propose and evaluate four measuring metrics (i.e., max, min, average and median) on such probability in multicast scenarios, and nodes with higher such similarity metrics are selected in priority to construct the forwarding group during the data replication process. Simulation results show that SSM can effectively improve the data delivery ratio and reduce the overhead at the same time.
Keywords: delay tolerant networks; DTNs; multicast; social characteristics; similarity
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