A Fiber-Optic-Based Protocol for Manufacturing System Networks: Part II—Statistical Analysis

1992 ◽  
Vol 114 (1) ◽  
pp. 121-131 ◽  
Author(s):  
A. Ayyagari ◽  
A. Ray
Keyword(s):  
Statistical Model ◽  
Real Time ◽  
Conceptual Development ◽  
Fiber Optic ◽  
Discrete Event ◽  
Simulation Models ◽  
Distribution Functions ◽  
Computer Integrated Manufacturing ◽  
Event Simulation ◽  
Arrival Processes

Conceptual development, architecture, statistical and simulation models, and the results of test and verification of a fiber-optic-based protocol have been reported in a sequence of two papers. The protocol uses the unidirectional bus topology and is specifically designed for computer integrated manufacturing (CIM) networks. The architecture of the protocol is formulated in Part I [1]. In this second part, a statistical model of the proposed protocol is formulated for analyzing the network-induced delays and pertinent results of analysis and simulation are presented for different scenarios of network traffic. The major assumptions in formulating the statistical model are: (1) message arrival processes for real-time (RT) and non-real-time (NRT) modes are independent and Markov; and (2) message lengths follow independent general distributions with known statistical properties. The Laplace-Stieltjes transforms of probability distribution functions of queueing delays for RT and NRT messages have been derived. The analytical results for the first two moments of both RT and NRT queueing delays have been compared with those obtained from discrete event simulation.

A Fiber-Optic-Based Protocol for Manufacturing System Networks: Part I—Conceptual Development and Architecture

1992 ◽  
Vol 114 (1) ◽  
pp. 113-120 ◽  
Author(s):  
A. Ayyagari ◽  
A. Ray
Keyword(s):  
Real Time ◽  
Computer Aided Design ◽  
Conceptual Development ◽  
Manufacturing System ◽  
Fiber Optic ◽  
Mac Protocol ◽  
Computer Integrated Manufacturing ◽  
Plant Management ◽  
Machine Model ◽  
Loop Control

The goal of Computer Integrated Manufacturing (CIM) is to put together the diverse areas of engineering, design and production processes, material inventory, sales and purchasing, and accounting and administration into a single interactive closed loop control system [1]. Essential to this distributed total manufacturing system is the integrated communications network over which the information leading to process interactions, and plant management and control will flow. Such a network must be capable of handling heterogeneous real-time (e.g., data packets for inter-machine communications at the factory floor) and non-real-time (e.g., Computer Aided Design (CAD) drawings, design specifications, and administrative information) traffic. This sequence of papers in two parts presents the development and analysis of a novel fiber-optic-based medium access control (MAC) protocol for integrated factory and office communications. Its adaptation as the common MAC layer protocol in the fiber-optic-based version of Manufacturing Automation Protocol (MAP) [2] and Technical and Office Protocols (TOP) [3], will make their specifications identical up to the presentation layer; only the application layer which is user-specific could be different. This first part provides the necessary background for the reported work and details of the protocol which is represented by a finite-state-machine model. Part II [4] presents the performance analysis of the protocol using a statistical model, and a comparison of the simulation and analytical results.

scholarly journals Simulation modeling and analysis of primary health center operations

SIMULATION ◽  
2021 ◽  
pp. 003754972110309
Author(s):  
Mohd Shoaib ◽  
Varun Ramamohan
Keyword(s):  
Resource Utilization ◽  
Waiting Times ◽  
Discrete Event ◽  
Simulation Models ◽  
Modeling And Analysis ◽  
Healthcare Facilities ◽  
Event Simulation ◽  
Analytical Approximations ◽  
Primary Health ◽  
Generic Modeling

We present discrete-event simulation models of the operations of primary health centers (PHCs) in the Indian context. Our PHC simulation models incorporate four types of patients seeking medical care: outpatients, inpatients, childbirth cases, and patients seeking antenatal care. A generic modeling approach was adopted to develop simulation models of PHC operations. This involved developing an archetype PHC simulation, which was then adapted to represent two other PHC configurations, differing in numbers of resources and types of services provided, encountered during PHC visits. A model representing a benchmark configuration conforming to government-mandated operational guidelines, with demand estimated from disease burden data and service times closer to international estimates (higher than observed), was also developed. Simulation outcomes for the three observed configurations indicate negligible patient waiting times and low resource utilization values at observed patient demand estimates. However, simulation outcomes for the benchmark configuration indicated significantly higher resource utilization. Simulation experiments to evaluate the effect of potential changes in operational patterns on reducing the utilization of stressed resources for the benchmark case were performed. Our analysis also motivated the development of simple analytical approximations of the average utilization of a server in a queueing system with characteristics similar to the PHC doctor/patient system. Our study represents the first step in an ongoing effort to establish the computational infrastructure required to analyze public health operations in India and can provide researchers in other settings with hierarchical health systems, a template for the development of simulation models of their primary healthcare facilities.

scholarly journals Assessing asset monitoring levels for maintenance operations

2015 ◽  
Vol 26 (5) ◽  
pp. 632-659 ◽  
Author(s):  
Abdullah A Alabdulkarim ◽  
Peter Ball ◽  
Ashutosh Tiwari
Keyword(s):  
Asset Management ◽  
Business Models ◽  
Discrete Event ◽  
Dynamic Modelling ◽  
Simulation Models ◽  
Content Type ◽  
Event Simulation ◽  
Product Service ◽  
Asset Monitoring ◽  
The Impact

Purpose – Asset management has recently gained significance due to emerging business models such as Product Service Systems where the sale of asset use, rather than the sale of the asset itself, is applied. This leaves the responsibility of the maintenance tasks to fall on the shoulders of the manufacturer/supplier to provide high asset availability. The use of asset monitoring assists in providing high availability but the level of monitoring and maintenance needs to be assessed for cost effectiveness. There is a lack of available tools and understanding of their value in assessing monitoring levels. The paper aims to discuss these issues. Design/methodology/approach – This research aims to develop a dynamic modelling approach using Discrete Event Simulation (DES) to assess such maintenance systems in order to provide a better understanding of the behaviour of complex maintenance operations. Interviews were conducted and literature was analysed to gather modelling requirements. Generic models were created, followed by simulation models, to examine how maintenance operation systems behave regarding different levels of asset monitoring. Findings – This research indicates that DES discerns varying levels of complexity of maintenance operations but that more sophisticated asset monitoring levels will not necessarily result in a higher asset performance. The paper shows that it is possible to assess the impact of monitoring levels as well as make other changes to system operation that may be more or less effective. Practical implications – The proposed tool supports the maintenance operations decision makers to select the appropriate asset monitoring level that suits their operational needs. Originality/value – A novel DES approach was developed to assess asset monitoring levels for maintenance operations. In applying this quantitative approach, it was demonstrated that higher asset monitoring levels do not necessarily result in higher asset availability. The work provides a means of evaluating the constraints in the system that an asset is part of rather than focusing on the asset in isolation.

scholarly journals Evaluation of a proposed optimization method for discrete-event simulation models

2012 ◽  
Vol 32 (3) ◽  
pp. 543-560 ◽  
Author(s):  
Alexandre Ferreira de Pinho ◽  
José Arnaldo Barra Montevechi ◽  
Fernando Augusto Silva Marins ◽  
Rafael Florêncio da Silva Costa ◽  
Rafael de Carvalho Miranda ◽  
...  
Keyword(s):  
Discrete Event Simulation ◽  
Discrete Event ◽  
Simulation Models ◽  
Optimization Method ◽  
Event Simulation

Using Object-Oriented Frame Language for Realizing Discrete Event Simulation

1996 ◽  
Author(s):  
Ming Dong ◽  
Jianzhong Cha ◽  
Mingcheng E
Keyword(s):  
Knowledge Base ◽  
Discrete Event Simulation ◽  
Discrete Event ◽  
Object Oriented ◽  
Simulation Models ◽  
Activity Cycle ◽  
Event Simulation ◽  
Knowledge Based ◽  
Inference Engines ◽  
Reasoning About Knowledge

Abstract In this paper, we realize knowledge-based discrete event simulation model’s representation, reasoning and implementation by means of object-oriented(OO) frame language. Firstly, a classes library of simulation models is built by using the OO frame language. And then, behaviours of simulation models can be generated by inference engines reasoning about knowledge base. Lastly, activity cycle diagrams can be used to construct simulation network logic models by connecting the components classes of simulation models. This kind of knowledge-based simulation models can effectively solve the modeling problems of complex and ill-structure systems.

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