International Journal of Simulation and Process Modelling (24 papers in press)
- An object-oriented approach to port activity simulation
by Mikhail Kondratyev
Abstract: This paper discusses a technique for modelling cargo port activity. It is designed for a comprehensive evaluation of port efficiency under a given input of cargo traffic. An object-oriented extension of the conventional block-based approach to process-oriented discrete-event simulation is proposed to specify a model structure. A port modelling framework is implemented using the proposed technique and AnyLogic 6 simulation software. The framework consists of the custom AnyLogic library backed by a Java-based package of classes and interfaces. The library contains blocks, representing a set of typical vehicle handling processes in a port. The framework provides tools that allow for the rapid development of a cargo port model. It not only provides non-modifiable standard solutions but also allows thorough detailing of certain elements of the port infrastructure, if necessary.
Keywords: seaport infrastructure, port logistics, cargo traffic, discrete-event simulation, object oriented
modelling framework, AnyLogic
- A parallel spatio-temporal model for emergency evacuation simulation
by Bo Yang
Abstract: The research provides a new way to simulate emergency evacuation in a large scale environment based on Multi-Resolution Modelling (MRM). The paper provides a parallel spatio-temporal model to synchronise and control two kinds of resolution models: the micro model based on Multi-Agent System (MAS) and Particle Swarm Optimization (PSO) algorithm, and the macro model based on a fluid dynamics model. With this approach, it is possible to apply distributed simulation to a large scale emergency evacuation, while the individual behaviours at specific locations can be also presented.
Keywords: parallel spatio-temporal model; evacuation simulation; multi-resolution modelling; synchronisation
- Environment exploration and map building of mobile robot in unknown environment
by Dongshu Wang, Yihai Duan, Jia Wang
Abstract: Simultaneous environment exploration and map building by a mobile robot in an unknown environment are studied. Based on real-time data acquired from a laser sensor, a suitable environment exploration strategy with obstacle avoidance ability is proposed. To handle the problems existing in producing and evaluating candidates, feasible approaches are proposed. They can maximise the expected information gain and keep the environment information integrated, and ensure the environment exploration's continuum and complete traversal. The new evaluation method overcomes the drawbacks of the traditional weighted average method, such as attending to one criterion but losing another. It can comprehensively evaluate the travelling cost, expected information gain and rotating angle to guarantee the quality of the optimal candidate. Furthermore, a topological map model is proposed that uses the nodes of the Growing Neural Gas (GNG) network as the topological network nodes. Through the growing characteristic of the GNG network, new topological nodes are added into the network to abstract and express the holistic knowledge of the surrounding environment and construct the environment map. Simulation results of two different indoor environments demonstrate the effectiveness and feasibility of the approach.
Keywords: mobile robot, environment exploration, map building, GNG network
- The Cell-DEVS formalism as a method for activity tracking in spatial modelling and simulation
by Gabriel Wainer
Abstract: The spreading of wildfires in forests is a complex natural phenomenon that depends on many different variables (such as the fuel, the geography of the area, the weather, etc.). We discuss different methods based on DEVS and Cell-DEVS, which can be used to speed up the simulation and simplify the modelling of this kind of spatial system. We propose using a combination of Quantized DEVS and dead reckoning to vary the length of the time steps taken by each cell. We also discuss different methods to adjust the computation method dynamically according to the level of activity, varying the length of the time taken by each cell. We show how these methods can be used to track the level of activity in the model automatically, without intervention by the modeller, and how this can improve the simulation performance for fire spreading and other environmental models. We show how the same models can be applied to a parallel simulation environment, allowing finding varied results faster than real-time.
Keywords: forest fires simulation; cellular models; Cell-DEVS
- Study of mapping relationship between surface micro-defect and haze of polycarbonate plate
by Yao Huang, Daming Wu, Qingyun Meng
Abstract: This paper investigates the mapping relationship between surface micro-defects and haze of a polycarbonate (PC) plate. Experiment studies showed that the PC plate with different degree of surface micro-defect can be produced by the process of injection and hot embossing, then the haze of the PC plate can be measured by a haze tester. Simulation studies were made through a ray tracing method to find the proper topography function of the surface of the plate and to calculate the haze of the plate, so as to study the relationship between surface micro-defects and haze. Finally, it was found that the experimental results validated the theoretical simulation well. The prediction and evaluation of the haze through the mapping relationship was available.
Keywords: micro-defect; haze; mapping; topography
- Using discrete event visual simulation to teach process modeling in MBA operations management courses
by Shahram Taj, Elham Mousavidin
Abstract: We discuss our experience using discrete event visual simulation to teach MBA students process modeling/analysis as part of a required operations management/supply chain class. We apply a hybrid approach by using a combination of simulation and such process mapping/analysis tools as flow-diagram, capacity/utilisation, and Littles law to real-world processes. We link improvements in operational performance indicators to financial performances. Our approach provides future managers with a deep understanding of the conceptual and practical aspects of process modeling/analysis, emphasising the complexities involved in real life dynamic and stochastic processes. We also developed a framework for assessing experiential learning using this teaching approach. The use of the discrete event visual simulation approach in operation management classes is novel and highly valuable. It is novel because we offer a four-week module in a fifteen-week class versus courses that exclusively teach simulation, and it is valuable in rendering simulation modeling accessible to a broader audience.
Keywords: discrete event simulation; process modeling; process planning; productivity improvement; performance measures; operations management; training.
- An extensible and configurable trace-driven Wweb server cluster simulation platform
by Zhi Xiong, Weijun Liu
Abstract: Scheduling algorithm and cache replacement algorithm are two important aspects in web server clusters, which affect, and even determine, the performance of the cluster system. However, their performance depends on client access pattern and some key system parameters to a large extent. In this paper, we design and implement a trace-driven web server cluster simulation platform based on JavaSim, called WSCSim, to evaluate the two kinds of algorithm. The algorithms are directly written in Java, so complicated algorithms can be simulated. In the platform, users are allowed to add new trace parsers to support different trace formats, and can use the timer and hook component to collect related information and then calculate the performance indexes they are interested in. Especially, the platform adopts a loosely coupled component architecture to facilitate extension, and all the extensible components are PnP (plug and play). All the components and their parameters can be configured in a configuration file of XML format. Two simulation application scenarios show the feasibility and validity of WSCSim.
Keywords: web server cluster; simulation platform; trace-driven; scheduling algorithm; cache replacement algorithm
- Structural optimisation and analysis of internally heat integrated reactive distillation column
by Shoushi Bo, Jian Wang, Lanyi Sun, Fei Bai, Kang He
Abstract: In this contribution, the model for hydrolysis of methyl acetate (MeAc) occurring in an internally heat integrated reactive distillation column (R-HIDiC) was built by using Aspen Plus software. Several configurations of R-HIDiC were proposed. The effects of the configuration on the energy saving were investigated on the premise of ensuring the purity of products and minimum approach temperature. The results reveal that the configuration has significant influence on the performance of R-HIDiC for the hydrolysis reaction of MeAc, and the optimal structure is determined. Sensitivity analysis has also been conducted to tune the design and operating variables of R-HIDiC.
Keywords: internally heat integrated reactive distillation column; configuration; methyl acetate; sensitivity
- Evolution of service innovation in e-commerce based on the NK model
by Zhe Yuan, Guoyin Jiang
Abstract: In this study, we employ an NK-based model to explore the evolution path of synergetic services in e-commerce. The proposed model can dynamically adjust to the changes in the synergetic services brands of e-commerce over time, including their technical and promotion capabilities. The simulation results show that enterprise innovation fitness increases with an increase in interaction between service capacities. The fitness of moderately interdependent enterprises is greater than that of enterprises that are completely dependent. In order to gain an optimal level of innovation fitness, an enterprise can make appropriate adjustments, depending on the interdependence of its service capabilities. The innovation evolutionary path of synergetic services in e-commerce is proportionately in line with an S-curve. The system can forecast the macro-level evolution of a synergic service under real scenarios, and support competition-oriented enterprises decision making. The synergy of internal service elements can also improve the enterprises performance in terms of innovation.
Keywords: e-commerce; synergetic services; innovation evolution; NK model; multi-agent
- A comprehensive method for solving finite-state semi-Markov processes
by Richard Warr, David Collins
Abstract: Semi-Markov processes (SMPs) provide a rich framework for many real-world problems. However, owing to difficulty in implementing practical solutions they are rarely used with their full capability. The theory of SMPs is quite mature but was mainly developed at a time when computational resources were not widely available. With the exception of some of the simplest cases, solutions to SMPs are inherently numerical, and SMPs have been underused by practitioners because of difficulty in implementing the theory in applications. This paper demonstrates the theory and computational methods needed to implement SMP models in practical settings. Methods are illustrated with an application modelling the movement of coronary patients in a hospital. Our aim is to allow practitioners to use richer SMP models without being burdened with the rigorous mathematical theory.
Keywords: first passage distribution; inverse Laplace transform; Markov renewal process; queuing theory; statistical flowgraph model; Weibull.
Special Issue on: "I3M 2013 "Cutting-edge Methodologies, Applications and Technologies in Modelling and Simulation,"
- Military serious game federation development and execution process based on interoperation between game application and constructive simulators
by Changbeom Choi, Moon-Gi Seok, Seon Han Choi, Tag Gon Kim, Soohan Kim
Abstract: This paper proposes a development and execution process for military serious game federation, the Military Serious Game Federation Development and Execution Process (MSGFDEP). The MSGFDEP uses interoperation between an existing game application and constructive simulators to extend the serious game. In order to achieve the interoperation between the game application and constructive simulators, we use a High-Level Architecture (HLA). By interoperating a constructive simulator with an existing game application, a serious game developer can save effort by extending a serious game application, rather than building a serious game from scratch. The proposed methodology comprises two specified processes: federation development and federation execution. When the developer wants to build a serious game from scratch, the proposed methodology supports three specified processes: game loop analysis, game agent design, and development. On the other hand, when the developer wants to organise the federation with existing HLA-compliant serious game and constructive simulators, the methodology provides federation synthesis. Finally, the methodology defines the federation execution process to help trainees to obtain more experiences that are realistic.
Keywords: interoperation; system of systems; constructive simulator; serious game; virtual military training;
- Using the RetSim simulator for fraud detection research
by Edgar Alonso Lopez-Rojas, Dan Gorton, Stefan Axelsson
Abstract: Managing fraud is important for business, retail and financial alike. One method to manage fraud is by detection, where transactions etc. are monitored and suspicious behaviour is flagged for further investigation. There is currently a lack of public research in this area. The main reason is the sensitive nature of the data. Publishing real financial transaction data would seriously compromise the privacy of customers and companies alike. We propose to address this problem by building RetSim, a multi-agentrnbased simulator (MABS) calibrated with real transaction data from one of the largest shoe retailers in Scandinavia. RetSim allows us to generate synthetic transactional data that can be publicly shared and studied without leaking business-sensitive information, and still preserve the important characteristics of the data. We then use RetSim to model two common retail fraud scenarios to ascertain exactly how effective the simplest form of statistical threshold detection could be. The preliminary results of our tested fraud detection method show that the threshold detection is effective enough at keeping fraud losses at a set level, and that there is little economic room for improved techniques.
Keywords: privacy; anonymisation; multi-agent-based simulation; MABS; ABS;
retail store; fraud detection; synthetic data
- An intuitive and efficient approach to integrated modelling and control of three-dimensional vibration in long shafts
by Geoff Rideout, Ahmad Ghasemloonia, Farid Arvani, Stephen Butt
Abstract: Long, slender rotating shafts are susceptible to potentially destructive vibration, the severity of which depends on boundary conditions, geometry, and excitation. Examples of such shafts are truck driveshafts and mine or oilwell drillstrings. A nonlinear three-dimensional bond graph-based shaft model is presented, in which axial, torsional, and lateral vibrations can be predicted. Rigid lumped segments with six degrees of freedom are connected by axial, torsional, shear, and bending springs to approximate continuous system response. Parasitic springs and dampers are used to enforce boundary conditions. Additionally, the shaft can come into contact with surrounding objects. Normal contact forces are generated with a stiff spring, and sliding friction forces during contact are incorporated using coordinate transformations and dynamic Coulomb friction. The model is easily reconfigurable for different boundary conditions, and the bond graph formalism facilitates the inclusion of (semi-)active control submodels such as electromechanical actuators or dampers. The model is applied to an unbalanced rotating 80-metre oilwell drillstring collar section. Thirty segments are sufficient to predict the lowest natural frequencies and static deflection accurately. Simulations show realistic axial, torsional and lateral vibration, with lateral vibration comparable to a finite element model against which preliminary validation is done. Active lateral vibration control is implemented, in which actuators and strain gauges are placed 90-degrees apart around the pipe walls at multiple locations. A proportional controller acting on the strain gauge output significantly attenuates vibration and reduces wellbore contact.
Keywords: multibody dynamics; bond graph; lumped segment; drillstring; shaft vibration
- Bondgraphs model on cavitating pump system
by Kazuhiro Tanaka
Abstract: Cavitation phenomena in a pump unit, as well as internal flows, can be analysed by CFD codes with meaningful precision. However, it is difficult to analyse the dynamic characteristics of cavitating pump systems, such as cavitation compliance and mass flow gain factor. In this paper, the characteristic parameters on pump cavitation are studied through CFD calculations on cavity volume, and the results are related the system Bondgraphs in a lumped parameter system. The cavitation compliance can be represented by 1-port C element and mass flow gain factor can be represented not only by 1-port R element as flow resistance but also by 1-port I element as fluid inertia.
Keywords: Bondgraphs; pump cavitation; dynamic behaviour of pump system; CFD; turbulence model; Rayleigh-Plesset model; cavity volume; one dimensional model; cavitation compliance; mass flow gain factor
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
- Multi-domain modelling and simulation of an automated manual transmission system based on Modelica
by Hua Huang, Sebastian Nowoisky, Rene Knoblich, Clemens Guhmann
Abstract: With the continuous growth in demand for lower emissions and higher riding comfort, the shift quality takes a more and more important role in automated transmission control algorithms. In order to effectively optimise the corresponding control parameters and functions in the transmission control units (TCU), the model-based calibration is a suitable method. For this purpose, a detailed dynamic model, which provides a virtual platform for the shift quality optimisation, is imperative and necessary. In this paper a 5-speed automated manual transmission (AMT) is used as a research object, and a detailed Modelica
Keywords: automated transmission, hydraulic, multi-domain modelling, model-based calibration
- An ontologic agent-based model of recreational polydrug use: SimUse
by Francois Lamy, Terry Bossomaier, Pascal Perez
Abstract: SimUse is an ontology-based social simulation model aiming at reproducing trajectories of recreational poly-drug users. To describe and capture the complexity of this phenomenon, we bring together empirical evidence from ethnography with theoretical constructs from sociology and neuroscience into an agent-based model. After reviewing the context of recreational poly-substance use and justifying our approach, this paper describes the multi-layered structure of the simulation and details some of the key aspects of SimUse. We illustrate the capacity of SimUse to reproduce neurophysiological reactions to substance use and to explore what-if? scenarios related to drug use.
Keywords: polydrug use; agent-based model; social simulation; sociology of deviance
- Dynamic optimal power flow control with simulation-based evolutionary policy-function approximation
by Stephan Hutterer, Michael Affenzeller
Abstract: In current operations research, dynamic optimisation problems are a central and challenging research topic. Especially in complex real-world systems, such as electric power grids, dynamic problems occur where robust solutions need to be found that enable (near-)optimal control over time in volatile as well as uncertain power grid operation. This paper identifies the application of policy-function approximation for such problems. Here, an analytic function is aimed to be found, which takes a state of the dynamic system as input and directly derives control actions that lead to approximate optimal operation at runtime, without the need for embedded optimisation. Applying this approach to two popular and scientifically challenging problem classes in power grids research, this work aims at providing a general view on this optimisation concept. Therefore, a dynamic generation unit control task will be experimentally treated on the one hand, while dynamic load control under uncertainty with electric vehicles represents the second use case. Both applications are related to dynamic stochastic optimal power flow problems, hence, show the successful application of policy-function approximation to this problem domain.
Keywords: simulation optimisation, power flow control, dynamic stochastic optimisation problems, policy-function approximation
- Comparison of optimisation methods tested on testing functions and discrete event simulation models
by Pavel Raska, Zdenek Ulrych
Abstract: The paper deals with the comparison of selected optimisation methods (Random Search, Hill Climbing, Tabu Search, Local Search, Downhill Simplex, Simulated Annealing, Differential Evolution and Evolution Strategy) using various evaluation criteria proposed by us which express the success of the optimisation method in different ways (the success of the method in finding the global optimum, the difference between optimum and local extremes, the distances of quartiles of possible solutions, the number of simulation experiments until the optimum was found). Some of the selected optimisation methods (Downhill Simplex, Simulated Annealing, Differential Evolution and Evolution Strategy) were modified to improve their behaviour to find the global optimum. Optimisation methods were tested on selected testing functions (De Jong
Keywords: simulation optimisation, evaluation criteria, optimisation methods, discrete event simulation models, testing function, ARENA, Plant Simulation, Random Search, Hill Climbing, Tabu Search, Local Search, Downhill Simplex, Simulated Annealing, Differential Evolution, Evolution Strategy
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
- Bond graph-based controller design for the quadruple-tank process
by Matías Nacusse, Sergio Junco
Abstract: The quadruple-tank process has been proposed as a benchmark for multivariable control system design. This paper addresses the design in the bond graph domain of a robust controller having the volumetric flows of two pumps as manipulated variables and the level of the two lower tanks as the regulated outputs. The basic control objectives are expressed in terms of desired closed-loop energy and power-dissipation functions and captured in the bond graph domain by means of a so-called Target Bond Graph. A basic controller design performed via Bond-Graph prototyping yields a primary control law, which is further robustified against parameter uncertainties, measurement deviations and faults using the diagnostic bond graph concept. This results in an additional closed loop consisting of a PI-law, which is represented by a physically meaningful bond graph subsystem. The design methodology is first developed on a simpler two-tank SISO-control problem and then straightforwardly extended to the multivariable problem with the help of some causal manipulations on the four-tank bond graph model.
Keywords: quadruple-tank system, bond graph prototyping, non-linear energy-based control, robust fault-tolerant control
- An advanced training environment for vessels' last mile navigation
by Francesco Longo, Letizia Nicoletti
Abstract: This article presents the results of a research project carried out at Modeling & Simulation Center Laboratory of Enterprise Solutions of the University of Calabria. The project aim was the design, development and prototyping of an advanced training environment for vessel operations in the last mile of navigation. The main idea behind the project is to recreate the typical conditions in which operators are usually involved in a vessel's last mile of navigation: manoeuvres of large ships within the harbour area (executed by ship pilots), tugboat operations to support ship manoeuvres (executed by tugboat pilots), and traffic control executed by officers on the ground (port traffic controllers). The system architecture includes three interoperable simulators, and this article focuses on one of the simulators, the tugboat simulator, presenting the system's general architecture, the software design and development phase, and the hardware integration. In particular, the 3D geometric models and the virtual environments (based on the port of Livorno, Italy) are introduced and described, the tugboat motion equations at sea (based on a six degree of freedom model) and the equations ruling the ship-tugboat interactions are presented and discussed; finally, specific information about the hardware integration (recreation of a tugboat bridge replica) is given. For the sake of completeness, a brief description of the other two simulators (the ship simulator and control tower simulator) and the way such simulators can be used jointly with the tugboat simulator (to provide cooperative training to operators involved in the last mile of navigation) is also given.
Keywords: marine ports, operator training, tugboat pilots, ship pilots, simulation
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