Measures Of System Effectiveness Research Articles

Analysis of a Single-Unit System with Weibull Failure and Repair densities Subject to Server Failure

The main concentration in the present paper is to analyze a single- unit system using the concepts of inspection, degradation, preventive maintenance, and server failure. A single repair facility inspect the original and degraded unit upon failure to check the feasibility of repair. The repair facility may fail during maintenance, repair and inspection and undergoes for treatment with Weibull probability density function. The unit after repair becomes degraded. Switch devices are perfect. All random variables like repair time, failure time, inspection time and treatment rate are independent and statistically independent. For the analysis of the system various measures of system effectiveness are obtained by using semi-Markov processes and regenerative point technique. With the help of numerical and graphical results for MTSF, availability and profit functions it is concluded that present system is more reliable, available and profitable, when random variables have less vale of shape parameters. Keywords: System, Availability, Inspection, Degradation and Preventive Maintenance

Reliability measure of an integrated H/W and S/W system with redundancy and preventive maintenance

The purpose of the study is to evaluate the reliability measures of an integrated $\mathrm{h} / \mathrm{w}$ and $\mathrm{s} / \mathrm{w}$ system with the concepts of redundancy and preventive maintenance. A stochastic model is developed considering two-identical units of the system- one unit is initially operative and other is in cold standby. In each unit $\mathrm{h} / \mathrm{w}$ and s/w work together and may fail independently from normal mode. There is a single server who visits the system immediately to $\mathrm{h} / \mathrm{w}$ repair and $\mathrm{s} / \mathrm{w}$ up-gradation. The preventive maintenance of the system (unit) is conducted by the server after a maximum operation time. The failure time of $\mathrm{h} / \mathrm{w}$ and $\mathrm{s} / \mathrm{w}$ follows negative exponential distribution while the distributions of preventive maintenance, $\mathrm{h} / \mathrm{w}$ repair and $\mathrm{s} / \mathrm{w}$ up-gradation times are taken as arbitrary. The semi-Markov process and regenerative point technique is adopted to derive expressions for various measures of system effectiveness. The behaviour of some important reliability measures has been observed graphically giving particular values to various costs and parameters.

Stochastic Analysis of a Redundant System with Maximum Repair Time and Priority for Operation over Preventive Maintenance

The main goal of the present study is to analyze a redundant system by using the concept of priority to operation over Preventive Maintenance (PM) and Maximum Repair Time (MRT). For this purpose, two stochastic models are developed. The concept of MRTis studied in the second model in addition to the assumptions of first model. There is a single server who visits the system immediately as and when required. The server takes the unit under preventive maintenance after a maximum operation time at normal mode if one standby unit is available for operation. If the repair of the failed unit is not possible up to an MRT, failed unit is replaced by new one. The failure time, maximum operation time and MRT distributions of the unit are considered as exponentially distributed while repair and maintenance time distributions are considered as arbitrary. Various measures of system effectiveness are obtained by using the technique of semi-Markov process and RPT. To compare the performance of stochastic models graphs for several reliability measures are drawn.

Reliability Measures of a Computer System with Priority for Repair and Hardware Redundancy

This paper concentrates on the evaluation of reliability measures of a computer system by introducing the concept of priority of hardware repair over software up-gradation. The system operates with one more hardware in cold standby. The failure times of hardware and software are independent random variables which follow negative exponential distribution. The repair facility (called server) attends the faults immediately which occur during operation of the system. Repair of the hardware is done at failure while software undergoes for up-gradation. The distributions of hardware repair and software up-gradation times are taken as arbitrary with different probability density functions. The system model has been analyzed using semi-Markov process and regenerative point technique. The trends of some important measures of system effectiveness have been observed for arbitrary values of the parameters. The profit of the present model has also been compared with that of the system model in which no priority is given to hardware repair.

Reliability Modeling of a Solar Photovoltaic System using Supplementary Variable Technique

present study, an attempt has been made to derive the reliability measures of a solar photovoltaic system consisting of four subsystems arranged in a series. There is a single server who visits the system immediately to do repair of the unit. Failure time distributions are negative exponential while the repair time distributions of the subsystems are arbitrary. After repair, subsystems are ''as good as new''. Moreover, the whole system fails immediately when any subsystem fail. Switch devices are perfect. All random variables are statistically independent. Under these assumptions, using Markov process theory and the Laplace transform, some important reliability indexes and some steady state system indexes are derived. Finally, graphs for various measures of system effectiveness are derived using MATLAB to highlight the importance of the study.

Stochastic behavior of a cold standby system with maximum repair time

Article history: Received January 29, 2015 Received in revised format: April 28, 2015 Accepted May 7, 2015 Available online May 8 2015 The main aim of the present paper is to analyze the stochastic behavior of a cold standby system with concept of preventive maintenance, priority and maximum repair time. For this purpose, a stochastic model is developed in which initially one unit is operative and other is kept as cold standby. There is a single server who visits the system immediately as and when required. The server takes the unit under preventive maintenance after a maximum operation time at normal mode if one standby unit is available for operation. If the repair of the failed unit is not possible up to a maximum repair time, failed unit is replaced by new one. The failure time, maximum operation time and maximum repair time distributions of the unit are considered as exponentially distributed while repair and maintenance time distributions are considered as arbitrary. All random variables are statistically independent and repairs are perfect. Various measures of system effectiveness are obtained by using the technique of semi-Markov process and RPT. To highlight the importance of the study numerical results are also obtained for MTSF, availability and profit function. Growing Science Ltd. All rights reserved. 5 © 201

Discrete Time Semi-Markov Model of a Two Non-Identical Unit Cold Standby System with Preventive Maintenance with Three Modes

This paper presents the reliability and availability measures of a two non-identical unit cold standby redundant system (unit-1 is operating, and unit-2 is cold standby) using semi-Markov process under discrete parametric Markov-Chain i.e. failure and repair times of a unit and time to PM and PM time are taken as discrete random variables assuming three different modes (normal (N) mode, partial failure (P) mode and total failure (F) mode) of each unit. The unit-1 is sent for preventive maintenance (PM) after its working for a random period of time assuming that the failure and repair times of a unit and time to PM and PM time are taken as discrete random variables having geometric distributions with different parameters. A single repairman is available with the system for PM of unit-1 and repair of both units. The system is considered in up-state if only one or two units are operative or in partial failure (P) mode. After some basic definitions and notations, we obtain various measures of system effectiveness; reliability, availability, mean time to failure, busy period of repairman due to PM of unit-1, busy period of repairman due to repair of unit-1 and unit-2 from total failure, and the expected profit function using regenerative point technique. The mathematical problem thus developed has next been solved numerically and graphically represented by the aid of Maple program.

Reliability measures of a computer system with priority to PM over the H/W repair activities subject to MOT and MRT

Article history: Received September 18, 2014 Accepted 15 December 2014 Available online December 16 2014 This paper concentrates on the evaluation of reliability measures of a computer system of twoidentical units having independent failure of h/w and s/w components. Initially one unit is operative and the other is kept as spare in cold standby. There is a single server visiting the system immediately whenever needed. The server conducts preventive maintenance of the unit after a maximum operation time. If server is unable to repair the h/w components in maximum repair time, then components in the unit are replaced immediately by new one. However, only replacement of the s/w components has been made at their failure. The priority is given to the preventive maintenance over repair activities of the h/w. The time to failure of the components follows negative exponential distribution whereas the distribution of preventive maintenance, repair and replacement time are taken as arbitrary. The expressions for some important reliability measures of system effectiveness have been derived using semi-Markov process and regenerative point technique. The graphical behavior of the results has also been shown for a particular case. Growing Science Ltd. All rights reserved. 5 © 201

Cost -Benefit Analysis of a Single-Unit System with Preventive Maintenance and Weibull Distribution for Failure and Repair Activities

Abstract This paper deals with a reliability model developed for a single-unit system which goes for preventive maintenance after a pre-specific time ‘t’ up to which no failure occurs. There is a single server who takes some time to arrive at the system for doing repair activities. The unit does not work as new after repair at complete failure and so called the degraded unit. The degraded unit is replaced by new one after its failure with some replacement time. The failure time, preventive maintenance time, replacement time and repair time of the unit are taken as Weibull distributed with common shape parameter and different scale parameters. The switching devices are perfect. The system is observed at suitable regenerative epochs to obtain various measures of system effectiveness of interest to system designers and operation managers.

Cardiac Arrest and Cardiopulmonary Resuscitation Outcome Reports: Update of the Utstein Resuscitation Registry Templates for Out-of-Hospital Cardiac Arrest: A Statement for Healthcare Professionals From a Task Force of the International Liaison Committee on Resuscitation (American Heart Association, European Resuscitation Council, Australian and New Zealand Council on Resuscitation, Heart and Stroke Foundation of Canada, InterAmerican Heart Foundation, Resuscitation Council of Southern

Utstein-style guidelines contribute to improved public health internationally by providing a structured framework with which to compare emergency medical services systems. Advances in resuscitation science, new insights into important predictors of outcome from out-of-hospital cardiac arrest, and lessons learned from methodological research prompted this review and update of the 2004 Utstein guidelines. Representatives of the International Liaison Committee on Resuscitation developed an updated Utstein reporting framework iteratively by meeting face to face, by teleconference, and by Web survey during 2012 through 2014. Herein are recommendations for reporting out-of-hospital cardiac arrest. Data elements were grouped by system factors, dispatch/recognition, patient variables, resuscitation/postresuscitation processes, and outcomes. Elements were classified as core or supplemental using a modified Delphi process primarily based on respondents’ assessment of the evidence-based importance of capturing those elements, tempered by the challenges to collect them. New or modified elements reflected consensus on the need to account for emergency medical services system factors, increasing availability of automated external defibrillators, data collection processes, epidemiology trends, increasing use of dispatcher-assisted cardiopulmonary resuscitation, emerging field treatments, postresuscitation care, prognostication tools, and trends in organ recovery. A standard reporting template is recommended to promote standardized reporting. This template facilitates reporting of the bystander-witnessed, shockable rhythm as a measure of emergency medical services system efficacy and all emergency medical services system-treated arrests as a measure of system effectiveness. Several additional important subgroups are identified that enable an estimate of the specific contribution of rhythm and bystander actions that are key determinants of outcome.

A single unit system with preventive maintenance and repair subject to maximum operation and repair times

The purpose of the present study is to determine reliability measures of a single-unit system considering arbitrary distributions for the random variables associated with failure time, preventive maintenance and repair times, maximum operation time, maximum repair time and replacement time. The system fails completely either directly from normal mode or via partial failure. There is a single server who visits the system immediately to do repair activities. The partially failed operating unit is shutdown after pre-specific time (called maximum operation time) for preventive maintenance. However, repair of the unit is done after its complete failure. The completely failed unit is replaced by new one if server is unable to do its repair within a maximum repair time. The unit works as new after preventive maintenance and repair. The expressions for some important measures of system effectiveness are derived using semi-Markov process and regenerative point technique. The numerical results for a particular case are obtained to depict the behavior of MTSF, availability and profit function with respect to maximum operation time for fixed values of other parameters and costs.

English

In this paper a two unit standby system with single repair facility has been considered. When a working unit fails, it is immediately taken over by standby unit and repair on the failed unit is started immediately. Taking two types of distribution, namely, Weibull and Erlangian, various system effectiveness measures such as MTSF, Availability and Busy Periods are compared and results are interpreted numerically. Regenerative Point Technique and Semi-Markov process have been employed in this paper to find the results. Results are supported with numerical data also. Failure time distributions are taken to be exponential whereas the repair times are particular. The result obtained from this can be applied to study complex system where small change in the value of one variable affects the system measures to a great extent.   Key words: MTSF, availability, busy period, regenerative point technique, Semi-Markov process.

Stochastic Analysis of a Parallel System under Maintenance and Repair Subject to Random Shocks

This study presents the stochastic analysis of a two unit parallel system subject to random shocks. There is a single server who visits immediately to do maintenance and repair of the system. The operative units in the system undergo for maintenance if they are affected by the impact of shocks with some probabilities. However, repair of the units is done when they fail due to some other reasons. The unit works as new after maintenance and repair. The distributions of random shocks and failure times of the unit follow negative exponential while that of maintenance and repair times are taken as arbitrary with different probability density functions. Using regenerative point technique and semi-Markov process, several measures of system effectiveness are obtained in steady state. The graphical behavior of MTSF, availability and profit function has been analyzed for particular values of various parameters and costs. Profit of the present model has also been made with the profit of the system model proposed by Malik and Chhillar (2012).

MEASUREMENT OF HEALTH CARE SYSTEM EFFICIENCY

The aim of the paper is presentation of construction of 2 measures (indicators) of health care system effectiveness and, also, the results of studies in this area conducted in OECD countries. We’ve also elaborated the matrix of correlation coefficients for specific socio-economic factors. Basing on this, we’ve evaluated the relations between the health care expenditure and selected indicators of health status. We’ve used data coming from the WHO, Bloomberg and Eurostat. We’ve hypothesized that expenditure on health correlate negatively with PYLL. Potential Years of Life Lost (PYLL) estimate of the average years a person would have lived if he or she had not died prematurely. Existing of this correlation should result in incorporation of this factor into the health care system’s efficiency measure to assure the proper diagnosis of the efficiency. Results, obtained during research, especially Pearson correlation coefficient seem to proof the validity of assumption, that the diagnosis of the health system’s overall effectiveness should contain a component of Potential Years of Life Lost (PYLL). JEL codes: I14, I15, P46, R51.

Reliability Analysis of a Single-Unit System with Inspection Subject to Different Weather Conditions

The purpose of this paper is to develop and analyze a reliability model of a single-unit system considering two weather conditions-normal and abnormal. The unit may fail completely either directly from normal mode or via partial failure. A single repair facility is available who plays the dual role of inspection and repair. The server first inspects the totally failed unit to see the feasibility of its repair. If repair of the unit is not feasible, it is replaced by new one. Server conducts the repair only on totally failed unit. The operation, inspection and repair of the unit are stopped in abnormal weather as a precautionary measure to avoid excessive damage to the system. Failure rates and rate of change of weather conditions are constant whereas the inspection and repair rates are general. By using semi-Markov process and regenerative point technique some reliability measures of system effectiveness are obtained. Graphs of MTSF, availability and profit for a particular case are drawn to highlight the importance of the study.

Analysis of a Repairable System Operating Under Different Weather Conditions

Ashish K. Barak Department of Mathematics Manipal University Jaipur, Jaipur-303007, India M.S. Barak Department of Mathematics, IGPGRC, Rewari, M.D. University, Rohtak-124001, India ABSTRACT The purpose of this paper is to develop and analyze a reliability model of a repairable system of single–unit considering two weather conditionsnormal and abnormal. In this model a unit may fail totally either directly from normal mode or via partial failure. There is a single server who visits the system immediately to do repair of the failed unit. The operation and repair of the unit are stopped in abnormal weather as a precautionary measure to avoid excessive damage to the system. Failure rates, repair rates and rate of change of weather conditions follow general distribution. By using semi-Markov process and regenerative point technique some reliability and economic measures of system effectiveness are obtained. The graphical of MTSF, availability and profit with respect to abnormal weather rate has also been shown for a particular case.

A two dissimilar unit parallel system with two phase repair by skilled and ordinary repairmen

The paper deals with the cost-benefit and reliability analysis of a two non-identical unit parallel system with two independent repairmen—skilled and ordinary. A failed unit is first attended by skilled repairman to perform first phase repair and then it goes for second phase repair by ordinary repairman. Both types of repair discipline are FCFS. All the failure and first phase repair time distributions are exponentials with different parameters whereas second phase repair time distributions are taken general. Various important measures of system effectiveness are obtained by regenerative point technique.

Modeling for a System Operating Characteristic for Wide Area Mines

Traditional landmines are limited in their attack range and information providing ability. There are currently several wide area search mines in the research and development phase to overcome these disadvantages. Progress on the individual technologies is promising, but there are insufficient analytical tools for evaluating the effectiveness of these concept mines. This paper examines some of the modeling aspects of wide area search mines with Autonomous Target Recognition (ATR) capability. The optimal employment of autonomous wide area search mines is addressed. The specific scenarios considered involve several mines searching a battle fields for targets in the presence of false targets. All relevant parameters are extracted from intelligence information, the sensor performance specification, and the vehicle performance specification. Analytic system effectiveness measures are derived using applied probability theory. Optimal schedules for controlling sensor threshold during a mission are derived. These schedules establish a system operating characteristic. An increase in system effectiveness is demonstrated when parameters are dynamically controlled during a mission.

Reliability modeling of a single-unit system with arbitrary distributions subject to different weather conditions

The main concentration of the present study is on the evaluation of some important reliability measures of a single-unit system considering arbitrary distributions for the random variables associated with failure and repair times, time to change of weather conditions, inspection time and arrival time of the server. The system operates under two weather conditions-normal and abnormal. The unit fails completely via partial failure. There is a single server who takes some time to arrive at the system. Server inspects the unit at its complete failure to see the feasibility of its repair while repair of the unit at partial failure is done without inspection. The unit works as new after repair at partial failure whereas unit is assumed as degraded after repair at complete failure. Inspection of the degraded unit is also conducted at its failure to examine the feasibility of repair. The degraded unit is replaced by new one if inspection reveals that its repair is not feasible to the system. Some measures of system effectiveness are obtained using semi-Markov and regenerative point technique. Giving particular values to various parameters and costs, the numerical results for mean time to system failure, availability and profit function are obtained considering exponential and Rayleigh distributions for all random variables.

What Makes the Implementation of Clinical Information Systems Difficult in Nursing Homes?

Attention has been given to the implementation failure of clinical information systems (CIS); however, the majority of previous investigations have been conducted in hospitals and clinics, rather than with a systems engineering perspective in long-term care and nursing home environments. In this present study, we examined the reasons behind a nursing home’s abandonment of a CIS. Data were collected through field observations (n=12) and individual interviews (n=18) of CIS stakeholders in a nursing home in Hong Kong. Data were analyzed using the immersion/crystallization approach. A sociotechnical model (Sittig and Singh, 2010) was used to guide data extraction and analysis. Our findings showed that the observed implementation challenges were related to the eight dimensions of the sociotechnical model. Specific implementation challenges identified included system speed, accessibility, and stability; technical support; clinical content adequacy and availability; system usefulness and user interface design; computer literacy; familiarity with the system; experience in the health care profession; fit between the system, workflow and communication; inconsistency between workflow, work policy, and procedures; lack of financial support; conflict between government regulations and the functional needs of users; and lack of measurement and monitoring of system effectiveness.. The knowledge gained regarding these challenges improves prior understanding of CIS failure in nursing home settings. The results offer a knowledge base for possible solutions and strategies for further initiatives in CIS implementation.