Pub Date : 2008-01-28DOI: 10.1109/RAMS.2008.4925845
S. Go
Pratt & Whitney's RL10 engine line has a long and rich history, beginning in 1958 and continuing today. This paper provides a historical summary of launch vehicles using RL10 engine derivatives dating from 1962 - 2005. The historical launch data is used to derive baseline launch success rates and growth curves for vehicles configured with RL10 engines in the upper stage.Because it was the first liquid hydrogen fueled rocket engine, the RL10 engine launch history provides a unique opportunity to investigate the maturity trends for revolutionary new complex systems. All of the data used in this survey was acquired through publicly-available sources. In all, 190 vehicles configured with RL10 upper stage engines were launched between 1962 and 2005. There were 12 upper stage failures that either failed to reach orbit, or reached a lower, unintended orbit. The early failures were dominated by knowledge gaps in system interactions and operational flight conditions. There is a clear trend of early development growth with an eventual plateau as system knowledge improved as a result of flight experience and more thorough test programs. Failures due to process-based issues (fabrication techniques, quality control, etc.), however, do not appear to exhibit maturity growth. Eventually, as the knowledge-based failures are removed, these process-based failures become the dominant risk driver. Vehicles that use mature, highly-reliable components are still vulnerable to process or functional changes, and failures of this type occur fairly uniformly with flight experience. In order to improve future reliability estimates for such systems, it is important to understand the trends and relationship between the knowledge-based and process-based issues, and determine which class of issues currently dominates. It should be noted that of the 12 upper stage failures, only one was caused by a defective part.
{"title":"A historical survey with success and maturity estimates of launch systems with RL10 upper stage engines","authors":"S. Go","doi":"10.1109/RAMS.2008.4925845","DOIUrl":"https://doi.org/10.1109/RAMS.2008.4925845","url":null,"abstract":"Pratt & Whitney's RL10 engine line has a long and rich history, beginning in 1958 and continuing today. This paper provides a historical summary of launch vehicles using RL10 engine derivatives dating from 1962 - 2005. The historical launch data is used to derive baseline launch success rates and growth curves for vehicles configured with RL10 engines in the upper stage.Because it was the first liquid hydrogen fueled rocket engine, the RL10 engine launch history provides a unique opportunity to investigate the maturity trends for revolutionary new complex systems. All of the data used in this survey was acquired through publicly-available sources. In all, 190 vehicles configured with RL10 upper stage engines were launched between 1962 and 2005. There were 12 upper stage failures that either failed to reach orbit, or reached a lower, unintended orbit. The early failures were dominated by knowledge gaps in system interactions and operational flight conditions. There is a clear trend of early development growth with an eventual plateau as system knowledge improved as a result of flight experience and more thorough test programs. Failures due to process-based issues (fabrication techniques, quality control, etc.), however, do not appear to exhibit maturity growth. Eventually, as the knowledge-based failures are removed, these process-based failures become the dominant risk driver. Vehicles that use mature, highly-reliable components are still vulnerable to process or functional changes, and failures of this type occur fairly uniformly with flight experience. In order to improve future reliability estimates for such systems, it is important to understand the trends and relationship between the knowledge-based and process-based issues, and determine which class of issues currently dominates. It should be noted that of the 12 upper stage failures, only one was caused by a defective part.","PeriodicalId":143940,"journal":{"name":"2008 Annual Reliability and Maintainability Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124279914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-01-28DOI: 10.1109/RAMS.2008.4925820
J. Akers, R. Bergman, S. Amari, L. Xing
A distinct characteristic of a multi-state system (MSS) is that the system and/or its components may exhibit multiple performance levels (or states) varying from perfect operation to complete failure. A MSS can model dependencies such as shared loads, performance degradation, imperfect fault coverage, standby redundancy, limited repair resources, and common-cause failures. The non-binary state property of a MSS and its components makes the analysis of such a system difficult. This paper proposes efficient algorithms for analyzing a MSS using multi-valued decision diagrams. Various reliability, availability, and performability measures are considered. The application and advantages of the proposed algorithms are demonstrated through an example.
{"title":"Analysis of Multi-State Systems using multi-valued decision diagrams","authors":"J. Akers, R. Bergman, S. Amari, L. Xing","doi":"10.1109/RAMS.2008.4925820","DOIUrl":"https://doi.org/10.1109/RAMS.2008.4925820","url":null,"abstract":"A distinct characteristic of a multi-state system (MSS) is that the system and/or its components may exhibit multiple performance levels (or states) varying from perfect operation to complete failure. A MSS can model dependencies such as shared loads, performance degradation, imperfect fault coverage, standby redundancy, limited repair resources, and common-cause failures. The non-binary state property of a MSS and its components makes the analysis of such a system difficult. This paper proposes efficient algorithms for analyzing a MSS using multi-valued decision diagrams. Various reliability, availability, and performability measures are considered. The application and advantages of the proposed algorithms are demonstrated through an example.","PeriodicalId":143940,"journal":{"name":"2008 Annual Reliability and Maintainability Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117009113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-01-28DOI: 10.1109/RAMS.2008.4925815
J. L. Cook
Few complex systems exhibit a binary set of states, that is only simple systems are limited to the basic states of operational and failed. Complex systems and Systems of Systems (SoS) take on multiple degraded states between the fully operational and fully failed extremes. However, reliability requirements often lack the necessary information to adequately allocate multi-state reliability to the sub-systems and components. Specifically, the criticality of functional failures is not defined in the requirements phase but rather, it is done just prior to test. A proposed requirements generation and allocation method is presented to enable more robust requirement sets specific to multi-state systems and SoS which in turn enables more effective and efficient design for reliability practices.
{"title":"Multi-state reliability requirements for complex systems","authors":"J. L. Cook","doi":"10.1109/RAMS.2008.4925815","DOIUrl":"https://doi.org/10.1109/RAMS.2008.4925815","url":null,"abstract":"Few complex systems exhibit a binary set of states, that is only simple systems are limited to the basic states of operational and failed. Complex systems and Systems of Systems (SoS) take on multiple degraded states between the fully operational and fully failed extremes. However, reliability requirements often lack the necessary information to adequately allocate multi-state reliability to the sub-systems and components. Specifically, the criticality of functional failures is not defined in the requirements phase but rather, it is done just prior to test. A proposed requirements generation and allocation method is presented to enable more robust requirement sets specific to multi-state systems and SoS which in turn enables more effective and efficient design for reliability practices.","PeriodicalId":143940,"journal":{"name":"2008 Annual Reliability and Maintainability Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122066122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-01-28DOI: 10.1109/RAMS.2008.4925792
S. Vittal, H. Neuman
This paper provides an open-source literature survey on the emerging science of early detection of warranty and reliability issues - a topic that is becoming critical to product life management for the automotive, aerospace and energy industries. The authors have conducted an open-source literature survey from a variety of disciplines like reliability engineering, operations research, prognostic-health management, systems engineering, biostatistics, public health and epidemiology. These are areas that have seen significant recent research activity in the development of early warning systems and algorithms. This paper provides an overview of current and promising techniques with a focus on their underlying statistical theory and related system architecture issues.
{"title":"Early detection of warranty issues: A multi-disciplinary literature survey","authors":"S. Vittal, H. Neuman","doi":"10.1109/RAMS.2008.4925792","DOIUrl":"https://doi.org/10.1109/RAMS.2008.4925792","url":null,"abstract":"This paper provides an open-source literature survey on the emerging science of early detection of warranty and reliability issues - a topic that is becoming critical to product life management for the automotive, aerospace and energy industries. The authors have conducted an open-source literature survey from a variety of disciplines like reliability engineering, operations research, prognostic-health management, systems engineering, biostatistics, public health and epidemiology. These are areas that have seen significant recent research activity in the development of early warning systems and algorithms. This paper provides an overview of current and promising techniques with a focus on their underlying statistical theory and related system architecture issues.","PeriodicalId":143940,"journal":{"name":"2008 Annual Reliability and Maintainability Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116791348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-01-28DOI: 10.1109/RAMS.2008.4925800
T. Lindquist, L. Bertling
Infrared thermography is the most common way to assess the condition of high-voltage electrical contacts in electric distribution and transmission systems. However, thermography has one major drawback as contacts carrying low or no load may not be assessed. This paper proposes a method to save and make use of thermography measurements to estimate statistical distribution parameters for the time to failure for a population of electrical contacts. The statistical distributions may then be used to support maintenance decisions for the sometimes large proportion of contacts that may not be assessed directly due to low load. As the measurement results accumulate over the years more accurate predictions can be made. The proposed method is illustrated using three test cases applied to a population of high-voltage disconnectors with randomly generated thermography measurements. The main conclusion of the paper is that using the proposed method will provide maintenance decision support for high-voltage apparatus that may not be assessed directly by thermography.
{"title":"Hazard rate estimation for high-voltage contacts using infrared thermography","authors":"T. Lindquist, L. Bertling","doi":"10.1109/RAMS.2008.4925800","DOIUrl":"https://doi.org/10.1109/RAMS.2008.4925800","url":null,"abstract":"Infrared thermography is the most common way to assess the condition of high-voltage electrical contacts in electric distribution and transmission systems. However, thermography has one major drawback as contacts carrying low or no load may not be assessed. This paper proposes a method to save and make use of thermography measurements to estimate statistical distribution parameters for the time to failure for a population of electrical contacts. The statistical distributions may then be used to support maintenance decisions for the sometimes large proportion of contacts that may not be assessed directly due to low load. As the measurement results accumulate over the years more accurate predictions can be made. The proposed method is illustrated using three test cases applied to a population of high-voltage disconnectors with randomly generated thermography measurements. The main conclusion of the paper is that using the proposed method will provide maintenance decision support for high-voltage apparatus that may not be assessed directly by thermography.","PeriodicalId":143940,"journal":{"name":"2008 Annual Reliability and Maintainability Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128584433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-01-28DOI: 10.1109/RAMS.2008.4925841
J. Hines, D. Garvey
Equipment, process, and system prognostic techniques can be classified as belonging to one of three major classes of methods: 1) conventional reliability-based using failure times (Weibull), 2) population based with environmental considerations (e.g. proportional hazards modeling), and 3) individual based (e.g. general path model). A new individual-based prognostic algorithm, termed the path classification and estimation (PACE) model, has been developed and is based entirely on failure data. This model recasts the general path model (GPM), which is the foundation of the majority of the modern individual based prognosis algorithms, as a classification problem, where a current device's degradation path is classified according to a series of exemplar paths and the results of the classification are used to estimate the remaining useful life (RUL) of the device. The requirement of the existence of a failure threshold is removed, thereby enabling the PACE to be applied to ldquoreal worldrdquo systems, where a single failure threshold is not likely to occur. If the failure threshold is known, simple formatting may be applied to the degradation paths such that they can be easily used with the PACE. The newly proposed method was applied to data collected from the hydraulic steering system of a drill used for deep oil exploration with the objective of detecting, diagnosing, and prognosing faults. The PACE was used to predict the RUL for several failure modes using actual data. For this work, a three tiered architecture was implemented, where conventional reliability methods were used to estimate the population-based RUL, PACE population-based prognosers were trained to map the cause of a failure mode to the RUL, and PACE individual prognosers were trained to map the effects of a failure mode to the RUL. It was found that the population based prognoser produced RUL estimates with large errors (75 hours) and uncertainties (261 hours). The individual prognosers were found to significantly outperform the population based prognoser, with errors ranging from 1.2 to 11.4 hours with 95% confidence intervals ranging from 0.67 to 32.02 hours.
{"title":"Nonparametric model-based prognostics","authors":"J. Hines, D. Garvey","doi":"10.1109/RAMS.2008.4925841","DOIUrl":"https://doi.org/10.1109/RAMS.2008.4925841","url":null,"abstract":"Equipment, process, and system prognostic techniques can be classified as belonging to one of three major classes of methods: 1) conventional reliability-based using failure times (Weibull), 2) population based with environmental considerations (e.g. proportional hazards modeling), and 3) individual based (e.g. general path model). A new individual-based prognostic algorithm, termed the path classification and estimation (PACE) model, has been developed and is based entirely on failure data. This model recasts the general path model (GPM), which is the foundation of the majority of the modern individual based prognosis algorithms, as a classification problem, where a current device's degradation path is classified according to a series of exemplar paths and the results of the classification are used to estimate the remaining useful life (RUL) of the device. The requirement of the existence of a failure threshold is removed, thereby enabling the PACE to be applied to ldquoreal worldrdquo systems, where a single failure threshold is not likely to occur. If the failure threshold is known, simple formatting may be applied to the degradation paths such that they can be easily used with the PACE. The newly proposed method was applied to data collected from the hydraulic steering system of a drill used for deep oil exploration with the objective of detecting, diagnosing, and prognosing faults. The PACE was used to predict the RUL for several failure modes using actual data. For this work, a three tiered architecture was implemented, where conventional reliability methods were used to estimate the population-based RUL, PACE population-based prognosers were trained to map the cause of a failure mode to the RUL, and PACE individual prognosers were trained to map the effects of a failure mode to the RUL. It was found that the population based prognoser produced RUL estimates with large errors (75 hours) and uncertainties (261 hours). The individual prognosers were found to significantly outperform the population based prognoser, with errors ranging from 1.2 to 11.4 hours with 95% confidence intervals ranging from 0.67 to 32.02 hours.","PeriodicalId":143940,"journal":{"name":"2008 Annual Reliability and Maintainability Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123057889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-01-28DOI: 10.1109/RAMS.2008.4925811
Meng-Lai Yin, J. Angus
The complexity of modern systems often precludes the development of exact models for reliability measures. Thus, a common issue is the achievement of fidelity in reliability models in light of system complexity. This issue grows with the stringency of reliability requirements imposed on the system. How to conduct a reliability analysis so that adequate fidelity is provided while maintaining manageable complexity is the topic addressed here. The performability approach, which takes performance effects into consideration in handling the complexity in reliability analysis, is proposed as an important element of the process. A case study on network reliability analysis is presented to demonstrate the approach. The example shows that the performability approach leads to cost-effective designs, while low-fidelity, overly conservative approaches lead to over-design of the system or overlooked effects of system operations. This approach has been applied to a real-life satellite navigation system, where it proved to be a useful technique in conducting reliability analysis for complex systems.
{"title":"On the cost of low-fidelity modeling: The case for a performability approach","authors":"Meng-Lai Yin, J. Angus","doi":"10.1109/RAMS.2008.4925811","DOIUrl":"https://doi.org/10.1109/RAMS.2008.4925811","url":null,"abstract":"The complexity of modern systems often precludes the development of exact models for reliability measures. Thus, a common issue is the achievement of fidelity in reliability models in light of system complexity. This issue grows with the stringency of reliability requirements imposed on the system. How to conduct a reliability analysis so that adequate fidelity is provided while maintaining manageable complexity is the topic addressed here. The performability approach, which takes performance effects into consideration in handling the complexity in reliability analysis, is proposed as an important element of the process. A case study on network reliability analysis is presented to demonstrate the approach. The example shows that the performability approach leads to cost-effective designs, while low-fidelity, overly conservative approaches lead to over-design of the system or overlooked effects of system operations. This approach has been applied to a real-life satellite navigation system, where it proved to be a useful technique in conducting reliability analysis for complex systems.","PeriodicalId":143940,"journal":{"name":"2008 Annual Reliability and Maintainability Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116582867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-01-28DOI: 10.1109/RAMS.2008.4925783
P. Sonnemans, A. Balasubramanian, K. Kevrekedis, M. Newby
This paper addresses the problem how to represent diverse field usage of professional systems in an efficient way, so that field usage can be incorporated in reliability tests. With diverse we mean the variability in system use in the field. Operational profiles are constructed from system field data to represent system field use. A clustering technique is introduced and applied in a strategic way to reduce the diversity in describing diverse system use in the field. In this way testing effort could be reduced by a factor 87 while maintaining 70% similarity with the original system field data.
{"title":"Efficiently represent diverse system field usage in reliability testing","authors":"P. Sonnemans, A. Balasubramanian, K. Kevrekedis, M. Newby","doi":"10.1109/RAMS.2008.4925783","DOIUrl":"https://doi.org/10.1109/RAMS.2008.4925783","url":null,"abstract":"This paper addresses the problem how to represent diverse field usage of professional systems in an efficient way, so that field usage can be incorporated in reliability tests. With diverse we mean the variability in system use in the field. Operational profiles are constructed from system field data to represent system field use. A clustering technique is introduced and applied in a strategic way to reduce the diversity in describing diverse system use in the field. In this way testing effort could be reduced by a factor 87 while maintaining 70% similarity with the original system field data.","PeriodicalId":143940,"journal":{"name":"2008 Annual Reliability and Maintainability Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130188105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-01-28DOI: 10.1109/RAMS.2008.4925764
B. Castanier, T. Yeung
We develop an inspection and maintenance policy to minimize the cost of maintaining a given section of road or highway when there is a great deal of uncertainty in the degradation process. We propose to model the degradation of a section of road based on the proliferation and growth of cracks. We utilize a combination of a Poisson and gamma process to account for the tremendous amount of uncertainty and difficulty in predicting the proliferation of cracks. Our policy defines the optimal inspection interval as well as the minimum threshold at which to perform crack repairs. Furthermore, our policy contains a safety constraint to prevent the probability of a ldquocatastrophicrdquo failure from exceeding a pre-determined reliability value. Numerical calculations have shown that our model will extend the lifecycle of the road by performing preventive, conditioned-based maintenance to slow down the growth of cracks. Classical preventive maintenance policies usually shorten the lifecycle by forcing earlier renewals.
{"title":"Optimal highway maintenance policies under uncertainty","authors":"B. Castanier, T. Yeung","doi":"10.1109/RAMS.2008.4925764","DOIUrl":"https://doi.org/10.1109/RAMS.2008.4925764","url":null,"abstract":"We develop an inspection and maintenance policy to minimize the cost of maintaining a given section of road or highway when there is a great deal of uncertainty in the degradation process. We propose to model the degradation of a section of road based on the proliferation and growth of cracks. We utilize a combination of a Poisson and gamma process to account for the tremendous amount of uncertainty and difficulty in predicting the proliferation of cracks. Our policy defines the optimal inspection interval as well as the minimum threshold at which to perform crack repairs. Furthermore, our policy contains a safety constraint to prevent the probability of a ldquocatastrophicrdquo failure from exceeding a pre-determined reliability value. Numerical calculations have shown that our model will extend the lifecycle of the road by performing preventive, conditioned-based maintenance to slow down the growth of cracks. Classical preventive maintenance policies usually shorten the lifecycle by forcing earlier renewals.","PeriodicalId":143940,"journal":{"name":"2008 Annual Reliability and Maintainability Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114529867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-01-28DOI: 10.1109/RAMS.2008.4925828
Bo Yang, Huajun Hu, Jun Zhou
For a software development project, when to stop testing the software and release it for operation is of great importance as it impacts both the software reliability and the total cost of the project. Software release time determination, therefore, has attracted a lot of research in the past two decades and several new cost models have been developed in the literature recently. In most research on this topic, the approach taken is to minimize the expected total cost (ETC) of the software project, or further consider the software reliability requirement. However, because the actual total cost (ATC) of the software project is a random variable, minimization of the ETC does not guarantee that the ATC will be near this minimum. In fact, there exists certain risk that the ATC may exceed the ETC to an intolerable extent, which, despite its importance, has not been addressed in most related research. In this paper, we study the above mentioned risk problem for software release time determination and propose a new approach which could be helpful for management to control the risk of the project being over-budget. A numerical example is given to illustrate the solution procedures of the proposed approach.
{"title":"Optimal software release time determination with risk constraint","authors":"Bo Yang, Huajun Hu, Jun Zhou","doi":"10.1109/RAMS.2008.4925828","DOIUrl":"https://doi.org/10.1109/RAMS.2008.4925828","url":null,"abstract":"For a software development project, when to stop testing the software and release it for operation is of great importance as it impacts both the software reliability and the total cost of the project. Software release time determination, therefore, has attracted a lot of research in the past two decades and several new cost models have been developed in the literature recently. In most research on this topic, the approach taken is to minimize the expected total cost (ETC) of the software project, or further consider the software reliability requirement. However, because the actual total cost (ATC) of the software project is a random variable, minimization of the ETC does not guarantee that the ATC will be near this minimum. In fact, there exists certain risk that the ATC may exceed the ETC to an intolerable extent, which, despite its importance, has not been addressed in most related research. In this paper, we study the above mentioned risk problem for software release time determination and propose a new approach which could be helpful for management to control the risk of the project being over-budget. A numerical example is given to illustrate the solution procedures of the proposed approach.","PeriodicalId":143940,"journal":{"name":"2008 Annual Reliability and Maintainability Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123486688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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