2013 Proceedings Annual Reliability and Maintainability Symposium (RAMS)最新文献

{"title":"Reliability and Maintainability analysis of a high air pressure compressor facility","authors":"Ph.D.  Fayssal M. Safie, Nasa Marshall, Robert W. Ring, Ph.D Stuart K. Cole, P. E. . Nasa, Langley Research Center, VA  Hampton","doi":"10.1109/RAMS.2013.6517657","DOIUrl":"https://doi.org/10.1109/RAMS.2013.6517657","url":null,"abstract":"This paper discusses a Reliability, Availability, and Maintainability (RAM) independent assessment conducted to support the refurbishment of the Compressor Station at the NASA Langley Research Center (LaRC). The paper discusses the methodologies used by the assessment team to derive the repair by replacement (RR) strategies to improve the reliability and availability of the Compressor Station (Ref.1). This includes a RAPTOR simulation model that was used to generate the statistical data analysis needed to derive a 15-year investment plan to support the refurbishment of the facility. To summarize, study results clearly indicate that the air compressors are well past their design life. The major failures of Compressors indicate that significant latent failure causes are present. Given the occurrence of these high-cost failures following compressor overhauls, future major failures should be anticipated if compressors are not replaced. Given the results from the RR analysis, the study team recommended a compressor replacement strategy. Based on the data analysis, the RR strategy will lead to sustainable operations through significant improvements in reliability, availability, and the probability of meeting the air demand with acceptable investment cost that should translate, in the long run, into major cost savings. For example, the probability of meeting air demand improved from 79.7 percent for the Base Case to 97.3 percent. Expressed in terms of a reduction in the probability of failing to meet demand (1 in 5 days to 1 in 37 days), the improvement is about 700 percent. Similarly, compressor replacement improved the operational availability of the facility from 97.5 percent to 99.8 percent. Expressed in terms of a reduction in system unavailability (1 in 40 to 1 in 500), the improvement is better than 1000 percent (an order of magnitude improvement).","PeriodicalId":189714,"journal":{"name":"2013 Proceedings Annual Reliability and Maintainability Symposium (RAMS)","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123277016","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}

{"title":"Applications of Relative Risk Evaluations in the Spacecraft Development","authors":"Haisheng Li, Liming Ren, Heng Zheng","doi":"10.1109/RAMS.2013.6517653","DOIUrl":"https://doi.org/10.1109/RAMS.2013.6517653","url":null,"abstract":"In the development of complex spacecraft, new technologies or new processes are often introduced in the design. Therefore, the problems of lack of information and data are usually encountered in the decision-making of designs selection. Relative risk evaluations can be applied in the selection of designs to cope with these problems. Also, in many instances, evaluators are more comfortable making relative decisions versus assigning absolute values. In this paper, a framework based on relative risk evaluations is presented which assists in making the decision on the design or designs to select. The proposed approach starts with applying the Fussell-Vesely measure to obtain the importance rankings of different risk contributors of different end states. The analytical hierarchy process (AHP) method is then used to determine the criteria weights of different risk end states. Accordingly, the relative importance of the particular contributors to the total risk for the reference design is calculated. On the other hand, the relative difference ratios in the contribution for alternative designs compared to reference design are calculated. Combined with the relative importance and the relative difference ratios of contributors, the relative risk difference ratios between different designs are evaluated. Finally, the optimal alternative design is determined by ranking relative risk evaluations. The performances of the proposed approaches are illustrated and validated using an example of a spacecraft propellant distribution system development. The results show that the proposed approaches are capable of helping designers to systematically consider relevant information and effectively determine the optimal design alternatives in the spacecraft development.","PeriodicalId":189714,"journal":{"name":"2013 Proceedings Annual Reliability and Maintainability Symposium (RAMS)","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129014606","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}

{"title":"Using human simulation in developing implantable medical device leads","authors":"J. Sipper, T. Marler, R. Bhatt","doi":"10.1109/RAMS.2013.6517630","DOIUrl":"https://doi.org/10.1109/RAMS.2013.6517630","url":null,"abstract":"Implantable medical device systems such as pacemakers and neuromodulators use leads, like those shown in Figure 1, to transmit signals from a source generator. The leads are routed within the body to a specific location such as the heart, epidural space, brain, or a specific nerve. Manufacturers must produce leads which are thin and flexible, for patient comfort, while being highly reliable as repair requires surgical intervention. Reliable leads contribute to a better quality of life, and reduce the trauma and expense of the surgeries required to replace failures, across the patient population.","PeriodicalId":189714,"journal":{"name":"2013 Proceedings Annual Reliability and Maintainability Symposium (RAMS)","volume":"135 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127669211","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}

{"title":"Optimal design configurations of fault-tolerant systems","authors":"S. Amari","doi":"10.1109/RAMS.2013.6517667","DOIUrl":"https://doi.org/10.1109/RAMS.2013.6517667","url":null,"abstract":"Fault tolerance is an essential architectural attribute for achieving high reliability in many critical applications of digital systems. Automatic recovery and reconfiguration mechanisms play a crucial role in implementing fault tolerance because an uncovered fault may lead to a system or subsystem failure even when adequate redundancy exists. An excessive level of redundancy may even reduce the system reliability in addition to consuming system resources. Therefore, an accurate reliability analysis must account for not only the system structure but also the system fault and error handling behavior. The models that capture the fault and error handling behavior are called coverage models. The appropriate coverage modeling approach depends on the type of fault-tolerant techniques used. This paper describes and demonstrates a solution methodology that determines optimal design configurations that maximize the reliability of fault-tolerant systems subject to imperfect fault coverage and resource constraints. It is assumed that the system consists of several subsystems in series where each subsystem contains multiple redundant components. The problem formulation considers the generic type of fault-tolerant mechanisms and associated coverage models for each subsystem. The objective of the optimal design is to select the design configuration, type of components, and fault-tolerant mechanism for each subsystem from the applicable/available choices. Optimal solutions are determined based on an equivalent problem formulation and integer programming. The methodology presented here is flexible and can accurately model a wide range of faulttolerant systems used in safety-critical applications. The methodology is successfully demonstrated on a large problem with 14 subsystems and 4 component choices for each subsystem.","PeriodicalId":189714,"journal":{"name":"2013 Proceedings Annual Reliability and Maintainability Symposium (RAMS)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124585837","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}

{"title":"An improved risk priority number method based on AHP","authors":"Youhu Zhao, Guicui Fu, B. Wan","doi":"10.1109/RAMS.2013.6517757","DOIUrl":"https://doi.org/10.1109/RAMS.2013.6517757","url":null,"abstract":"Process failure mode effect and critically analysis (PFMECA) is a widely used method to study the reliability of the manufacturing system. The method of Risk Priority Number (RPN) is the key part of PFMECA. It is used to determine the risk degree of each process failure mode. However, the traditional RPN method of PFMECA has some drawbacks. The paper analyzes the drawbacks of the traditional method and proposes a new method based on AHP (Analysis Hierarchy Process) and cost. The AHP method is able to determine the importance of each process. It is effective for solving complicated problems. The cost is useful to evaluate the risk of a failure mode. The improved RPN method makes the result of the RPN analysis more objective and accurate. Furthermore, the paper gives a fictitious instance using the new RPN method on PFMECA of a circuit board. The desired result has been achieved. This new method provides an effective and convenient tool for failure analysis and improves PFMECA implementation in failure and risk analysis for manufacturing production lines.","PeriodicalId":189714,"journal":{"name":"2013 Proceedings Annual Reliability and Maintainability Symposium (RAMS)","volume":"42 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120977811","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}

{"title":"Emerging trends in risk assessment and evaluation","authors":"K. Bowman, D. Huffman, J. Akers","doi":"10.1109/RAMS.2013.6517691","DOIUrl":"https://doi.org/10.1109/RAMS.2013.6517691","url":null,"abstract":"Risk assessment is one of the primary tools that management teams use to determine if a product should be taken to market. If the risk associated with the product concept is at an acceptable level, the product proceeds into the design phase. Throughout the product lifecycle, the risk assessment is updated and refined as product functions are built out into the design. Different industries use different tools for risk assessment, but their purpose is the same: to minimize product risk factors. In this paper, we discuss emerging trends in risk assessment for increasing both the value and efficiency of analyses. For example, by taking a systems engineering approach to FMEAs, companies are now rolling failure modes laterally to other subassemblies that can be affected by the same failure rather than merely rolling these modes up product tree structures. Additionally, systems engineers are using the top-down approach common to fault tree analysis and then breaking out only the highest risks into detailed FMEAs to save time. Yet another trend includes linking a FMEA directly to a FRACAS. This allows a direct comparison of what failure modes were predicted to occur (and at what rate) against what is actually seen in the field. This paper will give case studies demonstrating these emerging trends in risk assessment.","PeriodicalId":189714,"journal":{"name":"2013 Proceedings Annual Reliability and Maintainability Symposium (RAMS)","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115763922","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}

{"title":"Optimizing the non-destructive test program for a missile inventory","authors":"E. Hunt, J. A. Wester","doi":"10.1109/RAMS.2013.6517748","DOIUrl":"https://doi.org/10.1109/RAMS.2013.6517748","url":null,"abstract":"The quantity and frequency of non-destructive testing (NDT) across the life cycle of a missile inventory must be carefully considered. This paper provides a process for optimizing the quantity of missiles subject to NDT across the life of the missile inventory. This process ensures that the program does not exceed the minimum test quantity necessary to ensure that the inventory continues to meet the user's reliability requirement based on the predicted failure probability and annual test quantity. The methodology takes into account the age distribution of the inventory, tested/untested populations, removal of failing hardware, and items with multiple tests through the system life. The analysis also provides an estimate of the minimum and maximum test time that missiles will be exposed to across the projected life of the inventory. The paper provides an example of the process as applied to a representative Army missile system. This example demonstrates the practicality and simplicity of the process. The affect of varying levels of NDT on the inventory reliability is readily apparent in graphical form that facilitates the Reliability Engineer in presenting options to the Program Manager for making sustainment decisions. Overall, the U.S. Army Stockpile Reliability Program (SRP) has repeatedly demonstrated successes in identifying trends, ensuring readiness, and justifying missile shelf life extensions. However, under the current era of decreasing defense budgets, and expectations to push the life of existing missile systems out without replacement, NDT costs should be minimized while simultaneously minimizing the wear of those tests on the inventory. The approach outlined in this paper can be used to accomplish this on either the existing NDT program for a fielded system, or by the Program Manager developing a SRP program plan for a new missile system.","PeriodicalId":189714,"journal":{"name":"2013 Proceedings Annual Reliability and Maintainability Symposium (RAMS)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124130417","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}

{"title":"Effective management of functional safety for ISO 26262 standard","authors":"P. Stirgwolt","doi":"10.1109/RAMS.2013.6517758","DOIUrl":"https://doi.org/10.1109/RAMS.2013.6517758","url":null,"abstract":"The ISO 26262 standard is strongly affecting today's development behavior in the Automotive Industry. It defines the new development process requirements for the shift from the quality management system (QMS, ISO/TS 16949) to a safety oriented work culture. There are four key barriers to make this shift; 1) the existing business decision environment based only on cost, 2) the typical project work culture to directly jump to a solution without first defining the requirements (as defined by the “V” model), 3) the knowledge gap on how to shift from qualitative to quantitative product reliability assessment and 4) the time and awareness to manage the implementation of the additional safety confirmation measures. The challenge for the automotive industry is to overcome these barriers as established with the ISO/TS16949 quality management system processes. The ISO 26262 standard has covered the first three barriers by; 1) defining the requirements for a good safety culture, 2) deriving the safety requirements from the “Top Down”, 3) providing a quantitative product reliability or failure in Time (FIT) methodology. However, the standard only defined how a single developer needs to manage the functional safety but not how to address the development interfaces between the multiple organization during the safety lifecycle. With the learning from the Aerospace & Aviation industry it would be beneficial to the Automotive Industry to improve the interaction between the distributed developers. The Aerospace & Aviations “Flight Readiness Review” is a proven Safety Management Review network. To further improve the management of functional safety in the Automotive industry, this paper proposes to incorporate a “Safety Manager Review” network within the next revision of the ISO 26262 standard. The key benefits that would be achieved are: 1) Provide “closed loop” learning with common definitions throughout the multiple organisation. 2) Earlier resolution of the safety anomalies during the product lifecycle. 3) A more effective Management of Functional Safety by implementing the decisions based on field data. With this proposal in place the multiple organisation would have a better chance to confirm that the Safety Function complies adequately to the quantitative targets. Only when all three levels of the distributed developers have the same process language and quantitative units, the safety targets can be accomplished.","PeriodicalId":189714,"journal":{"name":"2013 Proceedings Annual Reliability and Maintainability Symposium (RAMS)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125925544","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}

{"title":"Software reliability modeling based on SVM and virtual sample","authors":"Yumei Wu, Risheng Yang","doi":"10.1109/RAMS.2013.6517763","DOIUrl":"https://doi.org/10.1109/RAMS.2013.6517763","url":null,"abstract":"Software reliability prediction models, which receive the most attention in software reliability engineering, use the failure data collected in testing phases to predict the failure occurrence in the operational environment. Currently, as the requirement for reliable software is increasing, ways to predict and estimate the reliability of software systems which require high reliability with small size test data is more problematic. What's more, there exists a difficult problem in software reliability modeling that the prediction capability of a model varies with failure data change. This inconsistency problem limits the promotion and application of software reliability techniques; mainly because the assumptions the models are based on may not be suitable for most cases. In addition, there exists a contradiction in traditional software reliability prediction methods. Prediction accuracy is low due to a lack of comprehensive consideration of factors affecting reliability. However, when more factors are taken into account, it is difficult to establish a statistical model and solve multivariate likelihood equations. For these reasons, software reliability prediction modeling method based on machine leaning techniques for small sample size is studied in this paper. Firstly, gene expression programming algorithm is used to analyze the small size sample by symbolic regression. The symbolic regression function acquired can then be viewed as the priori information of the data and used to generate a virtual sample. Then, with the virtual sample a regression model based on a Support Vector Machine (SVM) can be established, with which the software reliability can be predicted. Finally, a case study based on real failure data-sets is presented verifying the effectiveness of the method.","PeriodicalId":189714,"journal":{"name":"2013 Proceedings Annual Reliability and Maintainability Symposium (RAMS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130840968","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}

{"title":"Optimizing test confidence based on life cycle cost","authors":"S. Bindel","doi":"10.1109/RAMS.2013.6517768","DOIUrl":"https://doi.org/10.1109/RAMS.2013.6517768","url":null,"abstract":"Current Army acquisition policy states that systems shall demonstrate reliability requirements with high confidence, but the policy fails to state what `high' confidence means. Despite this, for every system there is an optimal confidence level with which to demonstrate the reliability requirement. The optimal confidence level may be driven by many competing factors including cost, schedule, Soldier safety, and mission criticality. Most of these factors are difficult to quantify, and leave the community to make a judgment call on the appropriate confidence level. In the absence of other driving or quantifiable metrics, one way to choose an optimal confidence level is to balance test cost against the risk to life cycle cost. This method deals in a natural metric: money. It is easily understood by the layman, and is straightforward to compare to most other programmatic risks. Conveniently it provides objective support for the common sense solution that inexpensive systems (to buy and test) that will be purchased in large quantities should be tested at higher confidence, while expensive systems (to buy and test) bought in low quantities possibly should be tested at lower confidence. If the other factors are not overwhelming, or do not suggest a particular confidence level, confidence can be optimized by balancing test cost against life cycle cost.","PeriodicalId":189714,"journal":{"name":"2013 Proceedings Annual Reliability and Maintainability Symposium (RAMS)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125650389","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}