Discrete Event-driven Simulation Research Articles

Modeling of Energy Consumption and Reduction of Pollutant Emissions in a Walking Beam Furnace Using the Expert Method—Case Study

This paper presents an algorithm for modeling electricity and natural gas consumption in a walking furnace with the use of artificial intelligence and simulation methods, depending on the length of the rolling campaign and the established rolling program. This algorithm is the basis for the development of a proposal for a set of minimum requirements characterizing the Best Available Techniques (BAT) for beam furnaces intended for hot rolling, taking into account the requirements set out in national regulations and the recommendations described in the BREF reference documents. This information should be taken into account when drawing up an application for an integrated permit, as well as when setting emission limit values. Based on the constructed algorithm, it was shown that depending on their type and technical specification, the analyzed projects will offer measurable economic benefits in the form of reducing the amount of energy consumed by 1,076,400 kWh during the implementation of 50 rolling campaigns to reduce gas by 14,625 GJ and environmental benefits in the form of reduction of pollutant emissions into the atmosphere 80–360 g/Mg. The constructed algorithm was validated in the Dosimis-3 program, based on a discrete event-driven simulation. Thanks to this representation of the model, its user can interactively participate in changes that take place in the model and thus evaluate its behavior. The model, verified in real conditions, can be the basic source of information for making effective operational technological decisions related to the preparation of production at the rolling mill as part of planning and long-term activities.

KnightSim: A Fast Discrete Event-Driven Simulation Methodology for Computer Architectural Simulation

In this paper we introduce a fast discrete event-driven simulation methodology, called KnightSim, that is intended for use in the development of future computer architectural simulations. KnightSim extends an older event-driven simulation library by (1) incorporating corrections to functional issues that were introduced by the recent additions of stack protection, pointer mangling, and source fortification in the Linux software stack, (2) incorporating optimizations to the event engine, and (3) introducing a novel parallel implementation. KnightSim implements events as independently executable x86 “KnightSim Contexts”. KnightSim Contexts comprise a mechanism for fast context execution and automatically model occupancy and contention, which readily lends itself to use in computer architectural simulations. We present the implementation methodologies of KnightSim and Parallel KnightSim with a detailed performance analysis. Our performance analysis makes direct comparisons between KnightSim, Parallel KnightSim, and the discrete event-driven simulation engines found in three different mainstream computer architectural simulators. Our results show that on average KnightSim achieves speedups of 2.8 to 11.9 over the other discrete event-driven simulation engines. Our results also show that on average Parallel KnightSim can achieve speedups over KnightSim of 1.89, 3.33, 5.84, and 9.24 for 2, 4, 8, and 16 threaded executions respectively.

A Case Study on Productivity Improvement by a Discrete Event-Driven Simulation System

A Case Study on Productivity Improvement by a Discrete Event-Driven Simulation System

Scalable service discovery in ubiquitous and pervasive computing architectures: A percolation-driven approach

The diffusion of ubiquitous and pervasive computing applications, providing advanced services anytime and everywhere across heterogeneous mobile networks, is fostering the development of new architectures and models, based on the emerging peer-to-peer paradigm, to allow the effective use of multiple replicated resources and services without the scalability and adaptiveness limitations characterizing traditional client–server organizations. In this scenario, effective service discovery facilities are needed to minimize the administrative overhead and increase the overall usability and perceived service quality. However, most of the currently available implementations lack efficiency due to the highly dynamic and hierarchically flat nature of the underlying wireless mobile networking environment, that make any traditional solution based on centralized schemes and statically defined roles practically unfeasible. Accordingly we proposed a novel service discovery approach based on a fully distributed and parallel search model, that does not require any centralized intelligence, fixed roles and stable communication infrastructure. It exploits, in a dynamic scale-free scenario characterized by competition for links and balanced node insertion and removal rates, a widely known random walk-based search paradigm benefitting from bond percolation in power law organizations to automatically limit the search space (by shielding low connectivity nodes from search traffic) and drastically reduce the total control overhead. We analyzed the effectiveness and performance of the proposed solution by using discrete event-driven simulation, whose results were satisfactory also in highly mobile ad-hoc environments. This indicates that the proposed ideas are promising and deserve further exploitation by practical application solutions designers.

リエントラントフローショップにおける装置メンテナンス計画に関する研究 (第3報)

This research paper introduces a development of production management method for equipment maintenance scheduling and work-in-process (WIP) dispatching or scheduling in re-entrant flow manufacturing systems. The method utilizes and combines two published technologies: discrete event-driven simulation and critical ratio dispatching rule. The research established a method of what-if analysis based on actual WIP configuration. Impact of equipment maintenance on system performance is quantified by the simulation. Then, modified critical ratio parameters is applied to maximize bottleneck equipment utilization. The established method, Dynamic Critical Ratio (DCR), has been implemented to a semiconductor manufacturing system. The implementation has avoided WIP blocking in equipment maintenance and WIP starvation at a bottleneck equipment downstream. As a results, the improvement of bottleneck utilization and total system throughput was observed. In closing, possibility for applying the developed method to other production management activities such as equipment re-configuration for product mix and demand change, work shift management and supply chain planning is discussed.

Study of MANET routing protocols by GloMoSim simulator

This paper compares ad hoc on-demand distance vector (AODV), dynamic source routing (DSR) and wireless routing protocol (WRP) for MANETs to distance vector protocol to better understand the major characteristics of the three routing protocols, using a parallel discrete event-driven simulator, GloMoSim. MANET (mobile ad hoc network) is a multi-hop wireless network without a fixed infrastructure. Following are some of our key findings: (1) AODV is most sensitive to changes in traffic load in the messaging overhead for routing. The number of control packets generated by AODV became 36 times larger when the traffic load was increased. For distance vector, WRP and DSR, their increase was approximately 1.3 times, 1.1 times and 7.6 times, respectively. (2) Two advantages common in the three MANET routing protocols compared to classical distance vector protocol were identified to be scalability for node mobility in end-to-end delay and scalability for node density in messaging overhead. (3) WRP resulted in the shortest delay and highest packet delivery rate, implying that WRP will be the best for real-time applications in the four protocols compared. WRP demonstrated the best traffic scalability; control overhead will not increase much when traffic load increases.

An integrated dispatcher training simulator for use in a regional electricity distribution centre

At the end of 1993 the first dispatcher training simulator of the Hungarian electric power industry began operation in the regional dispatcher centre of the North Hungarian Electricity Distribution Company (EMASZ KDSZ). The simulator performs discrete event-driven simulation of the network, the protection arrangements and the telemetry system. Its main purpose is to help the dispatchers to cope with complicated, rarely occurring disturbances in the electrical network. During a training session the trainee uses the same type of workstation as in the online system. The instructor's man-machine interface is implemented in DECWindows using the colour graphics terminal of a VAXstation 3100.

Concurrent discrete event-driven simulation tools

Parallel processing techniques that may enhance the performance of simulation methods for telecommunications networks are reviewed. The assumption that each processor runs a single network component process is avoided, such a premise being unrealistic when simulating large networks. Performance issues arising from implementing distributed simulation strategies on message-passing processor architectures are discussed. Nontrivial network models are separated into domains, each sited on a distinct transputer. Problems arising from the limited connectivity of the transputer are also addressed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>