International Journal of Simulation and Process Modelling (18 papers in press)
- 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
- 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
- Android malware detection based on permission combinations
by Zenghui Liu, Yingxu Lai, Yinong Chen
Abstract: Considering the resource limitations of mobile terminals, such as memory capacity and battery power, it will take a large portion of resources if the complex malicious detection system is implemented in mobile terminals. We propose that the training part is implemented on the backend server and the detecting part is implemented on the mobile terminals. In addition, we apply permission information the applications installed on the terminals, because permission mechanism controls the applications accesses to sensitive information. In our method, we first employ Apriori algorithm to define the permission combinations to be the initial feature and calculate the threat level of permission based on the relative deviation distances. The distances are then used as weights to the classification algorithm. In the process, we apply an integrated feature selection approach based on the principle of self-learning to extract important features to form the feature set. Finally, the minimum-risk Bayes algorithm is introduced to classify unknown applications. The experimental results show that our method is effective on imbalanced datasets.
Keywords: Android, imbalanced datasets, integrated learning, permission-based mechanism
- Engineering-oriented simulation platform for laminar cooling process of hot-rolled strips
by Jinxiang Pian, Zhen Wang, Yunlong Zhu, Tianyou Chai
Abstract: Because the new approach cannot be applied directly in the hot-rolled strip laminar cooling process, a simulation is necessary to verify the new approach effectively, which can improve the strip quality and production yields. In order to make sure the simulation platform is as similar as possible to the practical industrial process, we propose an engineering-oriented distributed simulation platform for the laminar cooling process, integrating part of physical equipment (such as PLC controllers). Additionally, there is an exchange of physical signals among the controller and virtual sensors in the platform. The simulation platform consists of four parts, including virtual object, virtual instruments and actuators, loop controller and process monitoring computer, and setting controller. The virtual object reflects the actual input and output characteristics of laminar cooling process. Virtual instruments and actuators can simulate the field instruments and actuators. Loop controller and process monitoring show the device operating conditions, the control performance, and give alarm signals in time. The setting controller performs setting control procedures. The experimental results indicate that simulation platform has powerful ability to evaluate the new approach in the light of the engineering, which can reduce the live-fire testing cost and meet the requirements of repeat trials.
Keywords: simulation platform; engineering-oriented; laminar cooling process; physical signals exchange
- Customer order fulfilment in mass customization context: an agent based approach
by Khaled Medini
Abstract: The ever-increasing customer-specific needs require suitable strategies to accommodate these requirements and deliver exactly what the customer wants and on time. Mass customisation, as a successor of mass production, is one of these strategies, which aims at satisfying customer needs with near mass production efficiency. However, achieving efficiency is challenged by several issues, such as customer order fulfilment in a customisation environment. In fact, product variety induced by customer choices requires flexible production systems able to manage internal complexity caused by such external variety. This paper proposes a multi-agent based model to manage customer orders by i) defining production requirements of each order, and ii) simulating the execution of the production and delivery operations. It then illustrates the proposed model with a case study and investigates the impact of inventory management on the enterprise economic performance. The case study shows how the model supports the decision-making process with respect to customer order fulfilment.
Keywords: order fulfilment; mass customisation; multi-agent system; dynamic scheduling; performance evaluation; decision making;
- Construction resource scheduling with chaotic particle swarm optimisation
by Zenghui Huang, Hongbo Zhao
Abstract: The traditional methods, such as critical path method and linear programming, have difficulty solving more general scheduling problems, such as resource constrained scheduling problems. Emerging techniques, such as particle swarm optimisation (PSO), have shown advantages in addressing this problem. However, the performance of simple PSO is greatly dependent on its parameters, and bad selection of the parameters often leads to the problem of being trapped in local optima which causes premature convergence. By introducing chaos mapping into the PSO algorithm, we present an updated PSO method addressing the construction resource rescheduling problems. In the proposed approach, the parameters of chaotic PSO have little influence on the performance of the algorithm, and thus make the algorithm more robust. The new method has been examined and tested on a practical problem. The results indicate that the new approach solves the problem at a faster convergence rate and with a better precision, as well.
Keywords: construction management; project management; scheduling; artificial intelligence; particle swarm optimisation
- A virtualisation simulation environment for data centre
by Chia-Jung Chen, Rong-Guey Chang
Abstract: In view of resource efficiency, virtualization is a critical unit to construct a virtualisation data centre (VDC). Indeed, performances bottlenecks are related to low level event. The unpredictability and complexity of virtualisation need to be solved. Generally, using a profiling tool to analyse a layered VDC application remains difficult and error-prone. A possible solution, VDC Simulation Techniques (VST), has been proposed as an alternative tool for early validation and evaluation, instead of using traditional profiling approaches. Although many performance bottlenecks have been indicated, the VST remains elusive. It is because the too many design goal to put in VST. Programmers need a clear VST to have simple programming model, even to solve performance pathologies, including unknown layered in sequence, virtualisation overhead. To address these pathologies, we aim at addressing a missing potential by simulating system from unit simulation to native system implantation for thin simulation. Our proposed simulator is called Data Centre Simulator (DCSim). It first identifies all simulation requirement that can have the VDC behaviour and then preforms a simulation environment by system implantation. Compared with previous research, ours has the following advantages. First, it not only optimises VST and provides cross-layer analysis but also proposes newly adaptive approaches for simulating VDC. Second, unlike discrete event simulation, it has layered situations because it takes real system as simulated unit and then perform system execution. Finally, DCSim provides a simple programming model, because the infrastructure are related to Linux. The results show that ours is more efficient and the analysed results are similar with general VDC.
Keywords: data centre; data sharing; virtualisation.
- Modelling the complexity of emergency department operations using hybrid simulation
by Norazura Ahmad, Noraida Abdul Ghani, Anton Abdulbasah Kamil, Razman Mat Tahar
Abstract: As a system, the emergency department of a hospital reveals detailed and dynamic complexity in its interaction between inter-departmental units and intra-departmental elements. Discrete-event simulation (DES) has the ability to comprehend operational problems with detailed complexity. Whilst using DES to model the complexities of the integrated emergency department system, we also use System Dynamics (SD) to capture the interdependency relationships between the emergency department and other subunits in a hospital. This paper presents the integration of DES and SD modelling approaches, hereby named as hybrid simulation, to better understand emergency department operations from a whole system perspective.
Keywords: emergency department, hybrid simulation, discrete-event simulation, system dynamics.
- Simulation and analysis of water concentration in the proton exchange membrane
by Shizhong Chen, Zhongxian Xia, Shiyu Xing, Xuyang Zhang, Yuhou Wu
Abstract: Water content in the PEM (Proton Exchange Membrane) has an important effect on PEM fuel cells. The water concentration gradient map was simulated by using COMSOL Multiphysics, and this figure was calculated and analysed to get the water concentration distribution in PEM. The results show that water concentration in the membrane shows inverse parabolic increase along the direction of gas flow. The trend of water concentration on the cathode surface is the same as on the anode surface, both of them increase along the direction of gas flow, but the value on the cathode side is higher than that on the anode side. The change rate of water concentration on the membrane increases along the direction of gas flow. The water concentration on the middle position of membrane is the lowest throughout the membrane, even lower than the inlet along the thickness direction, which can lead to water shortages.
Keywords: PEM; fuel cell; concentration gradient map; water concentration
- Simulation of autonomous systems in the extended marine domain
by Alberto Tremori, Angelo Ferrando, Matteo Agresta
Abstract: This paper is focused on the characteristics and goals of an integrated architecture that aims at reproducing joint interoperability among autonomous systems; the paper proposes an experimentation over a scenario developed for the maritime context that uses an innovative simulator. The authors' goal, during such research, consists of identifying requirements related to these simulators so that they accurately take into account the most important elements affecting real operative context. This analysis addresses training and engineering, and it could be further developed for supporting or operation supervision. The general architecture is devoted to integrating such simulators within a federation, together with the approach that has been used in order to carry out this operation, and represent the subjects of this paper. The mission environment has been created with the only goal to test the federation, and similarly simulation architecture and conceptual models are validated through proposed preliminary activities.
Keywords: autonomous systems, simulation, interoperability, intelligent agents
- Infrastructure protection based on heterogenous networks
by Marina Massei, Agostino Bruzzone, Simonluca Poggi
Abstract: This paper presents a modelling approach for mapping cyber defence issues with respect to heterogeneous networks; the research is devoted to develop an agent-driven simulation environment able to analyse this problem considering different layers, including CIS capabilities, operational issues, system architecture, management processes and human factors. The paper analyses a specific case study to validate and verify the proposed modelling approach; the scenario is focused on an heterogeneous network applied to extended maritime environment including Autonomous Underwater Vehicles (AUV), sensors, platforms, vessels, satellites and relevant military assets and threats. The present document uses this case study as example of System of Systems to be simulated including cyber warfare issues to evaluate their impact on operations.
Keywords: cyber defence, interoperable simulation, maritime simulation, heterogeneous networks, autonomous systems
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: "Recent Trends in Process Modelling, Simulation and Control,"
- Real-Time Simulation of DEVS Models in CD++
by Gabriel Wainer
Abstract: The CD++ toolkit was developed in order to implement the theoretical concepts specified by the DEVS formalism. The tool allows the execution of both DEVS and Cell-DEVS models. In this work, we present the definition and implementation of a real-time simulator. In such simulations, events must be handled timely and time constraints can be stated and validated accordingly. The new simulation technique allows the interaction between the model and its surrounding environment. Additionally, a non-hierarchical simulation approach is presented and introduced to CD++ in order to reduce the communication overhead.
Keywords: DEVS, real-time DEVS, real-time systems, CD++ toolkit.