Discrete Event Simulation Software Research Articles

Teaching system dynamics and discrete event simulation together: a case study

System dynamics (SD) and discrete event simulation (DES) follow two quite different modeling philosophies and can bring very different but, nevertheless, complimentary insights in understanding the same ‘real world’ problem. Thus, learning SD and DES approaches requires students to absorb different modeling philosophies usually through specific and distinct courses. We run a course where we teach model conceptualization for SD and DES in parallel and, then, the technical training on SD and DES software in sequential order. The ability of students to assimilate, and then put into practice both modeling approaches, was evaluated using simulation-based problems. While we found evidence that students can master both simulation techniques, we observed that they were better able to develop skills at representing the tangible characteristics of systems, the realm of DES, rather than conceptualizing the intangible properties of systems such as feedback processes, the realm of SD. Suggestions and reflections on teaching both simulation methods together are proposed.

Pilot To Full-Scale Production: A Battery Module Assembly Case Study

Electric vehicles are currently on the rise due to environmental and legal concerns. Furthermore, improvements made in battery assembly steadily boosts the efficiency of electric vehicles. A well-prevalent method to overcome the uncertainties that emerge from the ever-changing battery technology, is to assemble products using pilot production lines. However, literature pertaining to the scale-up of pilot production lines for full scale production is scarce. Therefore, in this paper, potential scale-up scenarios for battery module assembly line are proposed in a discrete event simulation software and results are compared. Furthermore, the benefits of the proposed method are discussed with a test case.

Effect of Buffers and Robot in a Converging and Diverging Conveyor System for a Production Operation through Simulation Approach

The rapid development in the computer technology and its applications in the production system have become flexible in product variety. The flexible production system may take time in setting up the machine to the change in the arrived job. It is often desirable to change the sequence of jobs to save setup cost and time. Conveyor system is the commonly used advanced material handling system that moves jobs from one station to other stations. The conveyor systems used may be of converging or diverging or combination of converging and diverging depending on the type of applications. Most of the assembly operations require converging and diverging type of conveyors. The performance of the conveyor system depends on the elements of the conveyor system and its operational parameters. The present work addresses the effect of dynamic job sequencing in a converging-diverging conveyor system with the objective to reduce the setup cost and its associated time. Discrete event simulation software has been used to model, simulate and investigate the effect of operational parameters associated with converging-diverging conveyor system. Three different models have been considered for studying the effect of different elements in the converging-diverging conveyor system along with dynamic job sequencing based on sequencing heuristics.

Utilization of Discrete Event Simulation in Business Processes Management Projects

Discrete event simulation (DES) software is often used in business process management (BPM) projects, in order to support modeling, change and automatization of process modeling. However, the current research lacks systematic overview of the benefits and pitfalls of using DES software for BPM. The goal of this paper is to provide a systematic analysis of research paper related to the operations research, computer science, business and management that report the usage of DES in BPM projects, in order to shed some light in this area. Results of this analysis could be useful to academics and business practitioners in their projects.

Ururau: a free and open-source discrete event simulation software

This paper has the purpose of describing the architecture and operation of Ururau, a software used to create discrete event simulation models based on the Java Simulation Library. Ururau is a free and open-source multiplatform software, which allows the user to develop models in the graphical interface or implement them directly in the source code. This characteristic allows the user to employ it as a tool for modeling and simulation of discrete event systems and also as a learning tool. Thus, an experienced modeler can add specific algorithms to simulation models or new features to the simulator. Also, with access to the source code, a beginner modeler can understand the internal structure of a discrete event simulation software. Initial results have demonstrated this new software’s ability in building small and simple models efficiently.

Modeling and simulation of mineral water filling process - an application with the Ururau Software

Este trabalho apresenta um modelo de simulação computacional para a análise da linha de produção de garrafões de água mineral. O modelo envolve o processo desde a higienização dos garrafões até a inspeção de saída. Nesse modelo, foi possível verificar diversos parâmetros que podem auxiliar um empresário desse setor a como dimensionar a linha de produção de acordo com o volume de produção e o mercado pretendidos. Para isso, este trabalho utiliza um software de simulação a eventos discretos, livre e de código fonte aberto chamado Ururau. Os resultados dos experimentos simulados demonstraram que a disponibilização de mais garrafões na entrada da linha impacta de forma positiva a produção, enquanto o acréscimo de operários e máquinas não demonstrou a mesma equivalência.

Comparison of Timed Automata with Discrete Event Simulation for Modeling of Biomarker-Based Treatment Decisions: An Illustration for Metastatic Castration-Resistant Prostate Cancer

BackgroundWith the advent of personalized medicine, the field of health economic modeling is being challenged and the use of patient-level dynamic modeling techniques might be required. ObjectivesTo illustrate the usability of two such techniques, timed automata (TA) and discrete event simulation (DES), for modeling personalized treatment decisions. MethodsAn early health technology assessment on the use of circulating tumor cells, compared with prostate-specific antigen and bone scintigraphy, to inform treatment decisions in metastatic castration-resistant prostate cancer was performed. Both modeling techniques were assessed quantitatively, in terms of intermediate outcomes (e.g., overtreatment) and health economic outcomes (e.g., net monetary benefit). Qualitatively, among others, model structure, agent interactions, data management (i.e., importing and exporting data), and model transparency were assessed. ResultsBoth models yielded realistic and similar intermediate and health economic outcomes. Overtreatment was reduced by 6.99 and 7.02 weeks by applying circulating tumor cell as a response marker at a net monetary benefit of −€1033 and −€1104 for the TA model and the DES model, respectively. Software-specific differences were observed regarding data management features and the support for statistical distributions, which were considered better for the DES software. Regarding method-specific differences, interactions were modeled more straightforward using TA, benefiting from its compositional model structure. ConclusionsBoth techniques prove suitable for modeling personalized treatment decisions, although DES would be preferred given the current software-specific limitations of TA. When these limitations are resolved, TA would be an interesting modeling alternative if interactions are key or its compositional structure is useful to manage multi-agent complex problems.

A review of open source discrete event simulation software for operations research

This article reviews the state of the art in Open Source (OS) Discrete Event Simulation (DES) software used for decision support in Operations Research (OR) focusing on the modelling of manufacturing, services, supply chain management and logistics. DES is arguably one of the most popular OR techniques. Commercial-Off-The-Shelf (COTS) DES software has been around for decades and it has considerably helped in the wider adoption and use of DES, providing the user with tools for modelling, debugging and experimentation. However, such tools often have limitations regarding their aspects such as cost, flexibility and reusability and OS DES seems to be a strong alternative in order to fill those gaps. The scope of our review is to present the state of the art in OS DES and identify future areas of research. The paper concludes with the desired features that an OS DES project should have in order to become a notable competitor against COTS equivalents in the OR domain.

ESTABLISHING AN OPTIMAL QUALITY PLANNING DECISION THROUGH DISCRETE EVENT SIMULATION: ANALYSIS CASE STUDY

Random in-process quality control (IPQC) is conducted in one of the departments in a circuit board manufacturing company, Company A, which produces high-mixed products, and results in complete failure of ensuring the quality of parts produced. Consequently, defects occur on the parts produced, leading to high rejection rate. This high rejection rate eventually results in high cost of non-value-added activities, which include rework of rejected parts. This paper introduces quality planning to ensure the quality of work-in-progress (WIP) parts in the production with discrete event simulation (DES) software. A series of experiments is conducted by using varying parameters, including flow patterns of parts in the shop floor and number of IPQC inspector, to assess the significance of these parameters on the performance measures relevant to quality perspective. Statistical analysis is conducted on the simulation results via ANOVA. Findings from this research prove that varying the parameters has a significant effect on the performance measures.

Model of the Adaptive Information System on a Navigational Bridge

Adaptive Information Systems (AdIS) are systems responsive to environmental changes or changes in a ship's systems. In this paper the potential of shipboard AdIS to decrease an officer's excessive workload are examined. The workload of the Officer Of the Watch (OOW) consists of tasks being initiated by the OOW and by external inputs. Sometimes the external inputs, particularly those requiring low priority actions, actually distract the OOW and increase the workload. Consequently an overload may be reduced by delaying low priority information, thus delaying the actions they could initiate. To estimate the applicability of AdIS, a model has been developed using a discrete event simulation software, consisting of three main modules: environment, AdIS and the OOW. The simulation has been run with a traffic environment comparable to those existing in the Dover Strait. A comparison between the OOW workload with and without AdIS has been estimated, indicating that during demanding navigation AdIS can significantly reduce the overload time. In areas similar to the Dover Strait the overload time can be reduced by a third.

Effect of ignoring input correlation on truck–shovel simulation

This paper presents an approach for handling correlated input variables in discrete event simulation (DES) modelling of truck–shovel systems using commercial DES software and uses a case study to investigate the effect of ignoring correlation between input variables. Multivariate random vectors, instead of independent probability distributions, are used for variables found to be correlated. The authors prove that correlations do exist in truck–shovel haulage systems. The model with multivariate random vectors performs better than the original model. The significance of modelling correlation in input variables depends on the strength of the correlation and the output’s sensitivity to the input variables.

A simple energy usage toolkit from manufacturing simulation data

A fundamental problem in the management of energy usage is the inability to clearly predict any possible energy saving opportunities. The cost of both under or overestimating potential returns on investment can be prohibitive to a decision maker. In recent years the simulation of energy usage using existing manufacturing simulation tools has increased in popularity among researchers, but it is decision makers who need to see the benefits of this discipline. This paper proposes an interactive manufacturing energy management toolkit which makes use of existing productivity simulation models for the prediction of energy usage. An interactive Microsoft® Excel® based toolkit is developed to control Lanner's WITNESS® discrete-event simulation software using Microsoft® Visual Basic® for Applications. The toolkit has the ability to predict potential areas where energy saving opportunities can be made within a complex manufacturing line, and is accessible from management presentations and proposals. The interactivity of the toolkit provides an environment which facilitates efficient hypothesis testing. The paper includes an industrial case study where the approach was used to quantify theoretical savings from certain energy usage reduction scenarios within a complex automotive engine manufacturing line.

Ship Block Logistics Simulation Based on Discrete Event Simulation

The load of resources in the block logistics process influences the mid-term planning and scheduling of shipyard management. Therefore, load analysis must be conducted before confirming the plans. However, conducting the analysis using the traditional mathematical model is difficult. This study suggests using the discrete event simulation (DES) method for load analysis in advance. The simulation model of actual shipyard block logistics is established by the DES software. Data on the structure of the product, process, resource, and schedule are clearly defined to match the DES model. Partial results through the simulation are discussed in terms of real production activities. The outputs prove that the proposed simulation model can help planners arrive at reasonable and rational decisions related to shipbuilding plans. This simulation method can contribute in strengthening the competitiveness of shipyards.

SIMULATION AND PERFORMANCE ANALYSIS EVALUATION FOR MULTIPATH EXTENSION OF AODV TO IMPROVE END TO END DELAY, ROUTE ERROR SENT, ROUTING LOAD AND PACKET DROP RATIO

This paper describes improvement in standard routing protocol AODV for mobile ad-hoc networks. Our mechanism setups multiple optimal paths based on bandwidth and delay. It allows to store multiple optimal paths based on Bandwidth and delay. At time of link failure, it will switch to next available path. To set up multiple paths, we have used the information that we get in the RREQ packet and also send RREP packet to more than one path. It reduces overhead of local route discovery at the time of link failure and because of this End to End Delay and Drop Ratio decreases. The main feature of our mechanism is that it is simple, efficient. We evaluate through simulations the performance of the AODV routing protocol including our scheme and we compare it with HLSMPRA (hot link split multi-path routing algorithm) Algorithm. Indeed, our scheme reduces routing load, End to End Delay, route error sent, and Packet drop ratio. The simulations have been performed using network simulator OPNET-14.0. The network simulator OPNET is discrete event simulation software for network simulations which means it simulates events such as sending, receiving, forwarding and dropping packets.

Evaluation of the DESI interface for discrete event simulation input data management automation

Discrete event simulation (DES) is a powerful tool of modelling and analysis used in different disciplines. DES projects rely heavily on data in order to compute different parameters that drive the simulations. DES is usually performed on specialized DES software, which performs the simulations but does not prepare the data to set up the simulations. Professionals and practitioners who use DES agree that the preparation of data for DES projects is a highly manual process and is extremely time-consuming in relationship to the entire duration of DES projects. On average, 31% of DES projects time is devoted to input data management. This article presents an innovative user interface, called DESI, which collects and processes data for DES projects in an automated manner, producing results in real time, in response to intuitive user inputs. This article demonstrates that the DESI interface reduces the time devoted to input data management, addresses current gaps in DES input data management and because it does not rely on the previous existence of data, it can be used in different disciplines where DES modelling is appropriate.

Simulation of forest harvesting alternative processes and concept design ofan innovative skidding winch focused on productivity improvement

In contexts in which mechanized harvesting is limited, such as in the northwestern Black Sea region of Turkey, it is important to improve timber harvesting productivity while preserving operators' safety and reducing environmental damage. This study aims to introduce a methodology in which the harvesting process is simulated with discrete-event simulation (DES) software in order to identify bottlenecks. An alternative process is compared to the original within the DES software, carrying out further steps oriented to the generation of new innovative product concepts. As a case study, the design of an innovative skidding winch is proposed. The development of the product was focused towards customer satisfaction by collecting customer requirements and identifying quality characteristics with a quality function deployment approach. Contradictions identified in the design phase were solved using the TRIZ contradiction toolkit, generating different product concepts. Inventive solutions provided by TRIZ were designed within parametric CAD software. The concepts were compared in a virtual environment, eventually selecting an optimal solution. The results showed that, with the concept adopted, it is possible to achieve a substantial increase in productivity, from 121% to 133%, in terms of kilograms of logs per hour deposited on the landing.

SIMULATION OF LIBRARY SYSTEM SERVICE

The paper describes the development of a simulation model of the Services system of Research Library of Library and Publishing Complex of Siberian Federal University. Discrete-event simulation and simulation software ExtendSim are used. The focus is on performance indicators of library services.

Integrating Optimisation and Simulation to Solve Manufacturing Scheduling Problems

In this research paper, a novel approach to solve manufacturing scheduling problems based on the integration of optimisation and simulation tools is proposed. The advantages of this approach are illustrated with reference to a manufacturing scheduling case study. The initial optimisation model is formulated as an adaptation of the Capacitated Lot-Sizing Problem (CLSP). Then, a Discrete Event Simulation (DES) software is employed to verify the optimised solution and analyse its robustness taking into account uncertainties in the processing times and arrival rates, and a heuristic method is applied to improve the initial solution. Video abstract [Display omitted]

An extension of the OpenModelica compiler for using Modelica models in a discrete event simulation

This article describes a new back-end and run-time system for the OpenModelica compiler. This new back-end transforms a Modelica model into a module for the adevs discrete event simulation package, thereby extending adevs to encompass complex, hybrid dynamical systems. The new run-time system that has been built within the adevs simulation package supports models with state-events and time-events and that comprise differential-algebraic systems with high index. Although the procedure for effecting this transformation is based on adevs and the Discrete Event System Specification, it can be adapted to any discrete event simulation package.

Optimal Route Based Advanced Algorithm using Hot Link Split Multi-Path Routing Algorithm

Abstract —Present research work describes advancement in standard routing protocol AODV for mobile ad-hoc networks. Our mechanism sets up multiple optimal paths with the criteria of bandwidth and delay to store multiple optimal paths in the network. At time of link failure, it will switch to next available path. We have used the information that we get in the RREQ packet and also send RREP packet to more than one path, to set up multiple paths, It reduces overhead of local route discovery at the time of link failure and because of this End to End Delay and Drop Ratio decreases. The main feature of our mechanism is its simplicity and improved efficiency. This evaluates through simulations the performance of the AODV routing protocol including our scheme and we compare it with HLSMPRA (Hot Link Split Multi-Path Routing Algorithm) Algorithm. Indeed, our scheme reduces routing load of network, end to end delay, packet drop ratio, and route error sent. The simulations have been performed using network simulator OPNET. The network simulator OPNET is discrete event simulation software for network simulations which means it simulates events not only sending and receiving packets but also forwarding and dropping packets. This modified algorithm has improved efficiency, with more reliability than Previous Algorithm.