Pub Date : 1995-01-16DOI: 10.1109/RAMS.1995.513290
M. W. Hulet, C. W. Carroll
This paper provides discussion items identifying safety management errors which should be unacceptable to safety management, particularly in the next generation due to the fact that the costs of noncompliance are simply too high. Safety management failures can be the final basis of program termination if there is a failure to properly analyze subsystems. Without the protection of proper hazard controls, catastrophic system failures may be the outcome. Some hazards slip through the cracks despite significant efforts to prevent it. However, it is the failure to apply acknowledged techniques in a proper and professional manner that should be totally unacceptable to safety managers, and will certainly be unacceptable to senior corporate managers in the next generation. Following the recommendations included in the paper could provide a reasonable means of assuring that frequent failures by safety management do not occur.
{"title":"Avoiding safety-management errors in the next generation","authors":"M. W. Hulet, C. W. Carroll","doi":"10.1109/RAMS.1995.513290","DOIUrl":"https://doi.org/10.1109/RAMS.1995.513290","url":null,"abstract":"This paper provides discussion items identifying safety management errors which should be unacceptable to safety management, particularly in the next generation due to the fact that the costs of noncompliance are simply too high. Safety management failures can be the final basis of program termination if there is a failure to properly analyze subsystems. Without the protection of proper hazard controls, catastrophic system failures may be the outcome. Some hazards slip through the cracks despite significant efforts to prevent it. However, it is the failure to apply acknowledged techniques in a proper and professional manner that should be totally unacceptable to safety managers, and will certainly be unacceptable to senior corporate managers in the next generation. Following the recommendations included in the paper could provide a reasonable means of assuring that frequent failures by safety management do not occur.","PeriodicalId":143102,"journal":{"name":"Annual Reliability and Maintainability Symposium 1995 Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122574297","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 : 1995-01-16DOI: 10.1109/RAMS.1995.513222
H. Salehfar, B. Bubar
For the purposes of this study, a generic electrohydraulic steering system of standard components similar to those found on currently sailing commercial tankers and freighters is considered. A fault tree analysis methodology is used to evaluate the proposed design and then employed to identify components or subsystems that have the most potential for improving overall system reliability. Design modifications consisting of parallel components of higher reliability are added to show the improvements in system availability. The study results show that complete regard for reliability criteria during the design process result in optimal availability while staying within design restrictions. Furthermore, regulatory agencies and classification societies could be using these same criteria when reviewing proposed design and new regulations on critical shipboard systems to increase vessel safety with minimal economic impact to the operators.
{"title":"Reliability of electro-hydraulic steering systems aboard commercial ships","authors":"H. Salehfar, B. Bubar","doi":"10.1109/RAMS.1995.513222","DOIUrl":"https://doi.org/10.1109/RAMS.1995.513222","url":null,"abstract":"For the purposes of this study, a generic electrohydraulic steering system of standard components similar to those found on currently sailing commercial tankers and freighters is considered. A fault tree analysis methodology is used to evaluate the proposed design and then employed to identify components or subsystems that have the most potential for improving overall system reliability. Design modifications consisting of parallel components of higher reliability are added to show the improvements in system availability. The study results show that complete regard for reliability criteria during the design process result in optimal availability while staying within design restrictions. Furthermore, regulatory agencies and classification societies could be using these same criteria when reviewing proposed design and new regulations on critical shipboard systems to increase vessel safety with minimal economic impact to the operators.","PeriodicalId":143102,"journal":{"name":"Annual Reliability and Maintainability Symposium 1995 Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129218902","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 : 1995-01-16DOI: 10.1109/RAMS.1995.513250
E. Pohl, D. Dietrich
Environmental stress screening (ESS) is employed to reduce, if not eliminate, the occurrence of early field failures. In this paper, a general two-level ESS model is presented for a multi-component electronic system. Screening is performed at the component and unit level. Components and connections are assumed to come from good and substandard populations and their time-to-failure distributions are modeled with mixture distributions. ESS models currently found in the literature assume that time-to-failure distributions are mixtures of exponentials. This paper extends previous work by examining mixtures of Weibull distributions for all assembly levels. The mixed Weibull distribution is used to examine how screening strategies change when wear-out mechanisms are present, Also, this paper relaxes the assumption that all failures precipitated by the screening process are found before being used in subsequent assembly levels. Numerical examples are provided to illustrate the screening model. Significant changes in screening strategies are found when the assumptions of perfect failure detection and exponentiality are relaxed.
{"title":"Environmental stress screening strategies for multi-component systems with Weibull failure-times and imperfect failure detection","authors":"E. Pohl, D. Dietrich","doi":"10.1109/RAMS.1995.513250","DOIUrl":"https://doi.org/10.1109/RAMS.1995.513250","url":null,"abstract":"Environmental stress screening (ESS) is employed to reduce, if not eliminate, the occurrence of early field failures. In this paper, a general two-level ESS model is presented for a multi-component electronic system. Screening is performed at the component and unit level. Components and connections are assumed to come from good and substandard populations and their time-to-failure distributions are modeled with mixture distributions. ESS models currently found in the literature assume that time-to-failure distributions are mixtures of exponentials. This paper extends previous work by examining mixtures of Weibull distributions for all assembly levels. The mixed Weibull distribution is used to examine how screening strategies change when wear-out mechanisms are present, Also, this paper relaxes the assumption that all failures precipitated by the screening process are found before being used in subsequent assembly levels. Numerical examples are provided to illustrate the screening model. Significant changes in screening strategies are found when the assumptions of perfect failure detection and exponentiality are relaxed.","PeriodicalId":143102,"journal":{"name":"Annual Reliability and Maintainability Symposium 1995 Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126970882","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 : 1995-01-16DOI: 10.1109/RAMS.1995.513229
J.J. Hadel, P. Lakey
A systems engineering approach to weapon system requirements allocation demands that all system level performance requirements, including reliability, be flowed down and allocated to lower-level sub functions using a logical, structured methodology. Normally it is not in the customer's best interest to contractually specify MTBF design parameters developed from system requirements because such action borders on dictating hardware design solutions instead of focusing on communicating customer overall needs and desires to the development agency. Because of this, the requirements flowdown process appears to offer opportunities for multiple feasible solutions, all of which are capable of meeting the customer's top level requirements.
{"title":"A customer-oriented approach to optimizing reliability-allocation within a set of weapon-system requirements","authors":"J.J. Hadel, P. Lakey","doi":"10.1109/RAMS.1995.513229","DOIUrl":"https://doi.org/10.1109/RAMS.1995.513229","url":null,"abstract":"A systems engineering approach to weapon system requirements allocation demands that all system level performance requirements, including reliability, be flowed down and allocated to lower-level sub functions using a logical, structured methodology. Normally it is not in the customer's best interest to contractually specify MTBF design parameters developed from system requirements because such action borders on dictating hardware design solutions instead of focusing on communicating customer overall needs and desires to the development agency. Because of this, the requirements flowdown process appears to offer opportunities for multiple feasible solutions, all of which are capable of meeting the customer's top level requirements.","PeriodicalId":143102,"journal":{"name":"Annual Reliability and Maintainability Symposium 1995 Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121293254","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 : 1995-01-16DOI: 10.1109/RAMS.1995.513270
E. Hakim, C. Rust, W. Olsson
The Microcircuit Application Handbook, MIL-HDBK-179(ER), dated 25 October 1993 is becoming the Army guide for the determination of suitability of a microcircuit packaging approach and the selection criteria for microcircuit suppliers and part types. This document is based on recommendations provided by the DoD Defense Science Board. A multiple entry matrix lists all possible DoD equipment environments, which ranges from temperature humidity controlled to space. Parts for these application environments include commercial and industrial grade plastic encapsulated microcircuits (PEMs), industrial qualification of PEM approaches, and QML. By implementation of the microelectronic selection criteria spreadsheet, the equipment developer provides the rational for selection of the PEM supplier and the part selected. The data required is mainly available through the supplier and should determine if he is implementing best commercial practices (BCP). This data will assure the parts surpass the equipment quality and reliability requirements. This approach to the use of nonmilitary approved microcircuits is already being implemented on several Army programs which are discussed. The vision is to make the handbook a requirement for all equipment developed at the US Army Communications-Electronics Command (CECOM).
{"title":"Beyond the qualified manufacturer list (QML)","authors":"E. Hakim, C. Rust, W. Olsson","doi":"10.1109/RAMS.1995.513270","DOIUrl":"https://doi.org/10.1109/RAMS.1995.513270","url":null,"abstract":"The Microcircuit Application Handbook, MIL-HDBK-179(ER), dated 25 October 1993 is becoming the Army guide for the determination of suitability of a microcircuit packaging approach and the selection criteria for microcircuit suppliers and part types. This document is based on recommendations provided by the DoD Defense Science Board. A multiple entry matrix lists all possible DoD equipment environments, which ranges from temperature humidity controlled to space. Parts for these application environments include commercial and industrial grade plastic encapsulated microcircuits (PEMs), industrial qualification of PEM approaches, and QML. By implementation of the microelectronic selection criteria spreadsheet, the equipment developer provides the rational for selection of the PEM supplier and the part selected. The data required is mainly available through the supplier and should determine if he is implementing best commercial practices (BCP). This data will assure the parts surpass the equipment quality and reliability requirements. This approach to the use of nonmilitary approved microcircuits is already being implemented on several Army programs which are discussed. The vision is to make the handbook a requirement for all equipment developed at the US Army Communications-Electronics Command (CECOM).","PeriodicalId":143102,"journal":{"name":"Annual Reliability and Maintainability Symposium 1995 Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124389456","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 : 1995-01-16DOI: 10.1109/RAMS.1995.513217
L.J. Hollick, G. Nelson
Failure modes and effects analysis (FMEA) and reliability centered maintenance (RCM)/maintenance steering group (MSG) decision logic have been successfully used by military and commercial aviation manufacturers for over three decades to develop preventive maintenance programs for new aircraft fleets. However, once a fleet is in place, there is a requirement to periodically validate or rationalize the applicability and effectiveness of individual tasks in the program, and to adjust task frequencies. Experience has shown that it is inefficient to re-apply FMEA/RCM decision logic to every aircraft item on a fixed frequency basis. This paper identifies how the Canadian Air Force (CAF) proposes to make more efficient and effective use of the in-service data it collects to identify those items for which the preventive maintenance requirement is ineffective or inapplicable. Moreover, it discusses how the same data source can be used in follow-up investigation to determine the actual failure mode history of an item as a basis for comparison with the FMEA-the basis upon which the requirement for the existing tasks is developed.
{"title":"Rationalizing scheduled-maintenance requirements using reliability centered maintenance-a Canadian Air Force perspective","authors":"L.J. Hollick, G. Nelson","doi":"10.1109/RAMS.1995.513217","DOIUrl":"https://doi.org/10.1109/RAMS.1995.513217","url":null,"abstract":"Failure modes and effects analysis (FMEA) and reliability centered maintenance (RCM)/maintenance steering group (MSG) decision logic have been successfully used by military and commercial aviation manufacturers for over three decades to develop preventive maintenance programs for new aircraft fleets. However, once a fleet is in place, there is a requirement to periodically validate or rationalize the applicability and effectiveness of individual tasks in the program, and to adjust task frequencies. Experience has shown that it is inefficient to re-apply FMEA/RCM decision logic to every aircraft item on a fixed frequency basis. This paper identifies how the Canadian Air Force (CAF) proposes to make more efficient and effective use of the in-service data it collects to identify those items for which the preventive maintenance requirement is ineffective or inapplicable. Moreover, it discusses how the same data source can be used in follow-up investigation to determine the actual failure mode history of an item as a basis for comparison with the FMEA-the basis upon which the requirement for the existing tasks is developed.","PeriodicalId":143102,"journal":{"name":"Annual Reliability and Maintainability Symposium 1995 Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127832900","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 : 1995-01-16DOI: 10.1109/RAMS.1995.513224
D. Mortin, J. Krolewski, M. Cushing
The assumption of the constant failure rate can lead to excessive costs and nonoptimum design decisions. As this paper shows, simply summing constant failure rates can produce results which are highly inaccurate. Highly inaccurate results can introduce significant error in decisions made in everything from product design to logistics support requirements such as spares and maintainers. The authors argue that if a shift is made from reliability accounting tasks to reliability engineering analysis, the ability to address hazard rates versus time based on root-cause failure mechanisms will become cost-effective and can become an integral part of the concurrent engineering approach to product development. The notion of the constant failure rate should no longer be accepted as a rule. Instead, statistical distributions and assumptions must be shown to be appropriate every time they are used. Simplicity alone is not a sufficient reason to use any given methodology or approach.
{"title":"Consideration of component failure mechanisms in the reliability assessment of electronic equipment-addressing the constant failure rate assumption","authors":"D. Mortin, J. Krolewski, M. Cushing","doi":"10.1109/RAMS.1995.513224","DOIUrl":"https://doi.org/10.1109/RAMS.1995.513224","url":null,"abstract":"The assumption of the constant failure rate can lead to excessive costs and nonoptimum design decisions. As this paper shows, simply summing constant failure rates can produce results which are highly inaccurate. Highly inaccurate results can introduce significant error in decisions made in everything from product design to logistics support requirements such as spares and maintainers. The authors argue that if a shift is made from reliability accounting tasks to reliability engineering analysis, the ability to address hazard rates versus time based on root-cause failure mechanisms will become cost-effective and can become an integral part of the concurrent engineering approach to product development. The notion of the constant failure rate should no longer be accepted as a rule. Instead, statistical distributions and assumptions must be shown to be appropriate every time they are used. Simplicity alone is not a sufficient reason to use any given methodology or approach.","PeriodicalId":143102,"journal":{"name":"Annual Reliability and Maintainability Symposium 1995 Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127939155","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 : 1995-01-16DOI: 10.1109/RAMS.1995.513275
S.L. Dreyer, G. Smith
The US Defense Secretary hopes to reap savings in the order of $30 billion with procurement reform. He admits that one of his toughest challenges will be to nurture and sustain America's technological edge, which he sees as a necessity in a period of declining force levels, during a time of declining budgets. With these thoughts in mind Science Applications International Corporation (SAIC) took the initiative to pursue alternative cost effective methods to raise spare parts utilization. SAIC's approach is to include repaired printed wiring assemblies (PWAs) in lieu of purchasing additional spare PWAs in the spares analysis calculation. This also negates the additional costs of inventory and storage of the logistically required spare PWAs.
{"title":"Innovations in military spares analysis","authors":"S.L. Dreyer, G. Smith","doi":"10.1109/RAMS.1995.513275","DOIUrl":"https://doi.org/10.1109/RAMS.1995.513275","url":null,"abstract":"The US Defense Secretary hopes to reap savings in the order of $30 billion with procurement reform. He admits that one of his toughest challenges will be to nurture and sustain America's technological edge, which he sees as a necessity in a period of declining force levels, during a time of declining budgets. With these thoughts in mind Science Applications International Corporation (SAIC) took the initiative to pursue alternative cost effective methods to raise spare parts utilization. SAIC's approach is to include repaired printed wiring assemblies (PWAs) in lieu of purchasing additional spare PWAs in the spares analysis calculation. This also negates the additional costs of inventory and storage of the logistically required spare PWAs.","PeriodicalId":143102,"journal":{"name":"Annual Reliability and Maintainability Symposium 1995 Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129157515","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 : 1995-01-16DOI: 10.1109/RAMS.1995.513286
Arun Kumar Somani, U. R. Sandadi, D. Twigg, T. Sharma
A current trend in system design is to emphasize integration of various functionalities. This results in a complex environment to be handled by a fault tolerant system. The fault tolerance in the system is achieved by means of redundancy in the components, built in fault diagnosis, and sophisticated recovery/reconfiguration techniques. Reliability analysis of such systems is usually done using a Markov representation of the system. However, Markov chains tend to grow exponentially with the number of components, and beyond a certain size they become intractable. We propose techniques to manage the modeling of a class of systems by means of decomposing the system Markov chain into smaller Markov chains of manageable size. Our decomposition techniques facilitate modeling both repairable and nonrepairable systems with reduced complexity. These decomposition techniques are proved to be accurate analytically. The applicability of these schemes is shown through an example.
{"title":"An efficient decomposition technique for Markov-chain analysis","authors":"Arun Kumar Somani, U. R. Sandadi, D. Twigg, T. Sharma","doi":"10.1109/RAMS.1995.513286","DOIUrl":"https://doi.org/10.1109/RAMS.1995.513286","url":null,"abstract":"A current trend in system design is to emphasize integration of various functionalities. This results in a complex environment to be handled by a fault tolerant system. The fault tolerance in the system is achieved by means of redundancy in the components, built in fault diagnosis, and sophisticated recovery/reconfiguration techniques. Reliability analysis of such systems is usually done using a Markov representation of the system. However, Markov chains tend to grow exponentially with the number of components, and beyond a certain size they become intractable. We propose techniques to manage the modeling of a class of systems by means of decomposing the system Markov chain into smaller Markov chains of manageable size. Our decomposition techniques facilitate modeling both repairable and nonrepairable systems with reduced complexity. These decomposition techniques are proved to be accurate analytically. The applicability of these schemes is shown through an example.","PeriodicalId":143102,"journal":{"name":"Annual Reliability and Maintainability Symposium 1995 Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131513418","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 : 1995-01-16DOI: 10.1109/RAMS.1995.513259
M. A. Hinzmann
Dependency modeling (DM) can be used to provide an accurate measure of the testability attributes of items ranging in complexity from individual circuit-cards to complete weapon systems. This paper presents a method for performing testability analysis on an avionics power supply (PS) using DM. The level of indenture used in the DM process is assessed, and limitations of the model are described. The testability analysis tool used to compute the testability figure of merit (TFOM) is the weapon system testability analyzer (WSTA). The results of the modeling effort provide a measure of the fault detection capabilities of the power supply. In addition to PS assessment, the DM process as defined herein provides the benefits of: (1) a structured approach to diagnostic predictions; (2) the ability to adapt the model to the level of detail desired; (3) integration of reliability, maintainability and supportability considerations in the analysis; and (4) a framework for both go-nogo and diagnostic test development.
{"title":"Dependency modeling of an avionics power-supply for testability analysis","authors":"M. A. Hinzmann","doi":"10.1109/RAMS.1995.513259","DOIUrl":"https://doi.org/10.1109/RAMS.1995.513259","url":null,"abstract":"Dependency modeling (DM) can be used to provide an accurate measure of the testability attributes of items ranging in complexity from individual circuit-cards to complete weapon systems. This paper presents a method for performing testability analysis on an avionics power supply (PS) using DM. The level of indenture used in the DM process is assessed, and limitations of the model are described. The testability analysis tool used to compute the testability figure of merit (TFOM) is the weapon system testability analyzer (WSTA). The results of the modeling effort provide a measure of the fault detection capabilities of the power supply. In addition to PS assessment, the DM process as defined herein provides the benefits of: (1) a structured approach to diagnostic predictions; (2) the ability to adapt the model to the level of detail desired; (3) integration of reliability, maintainability and supportability considerations in the analysis; and (4) a framework for both go-nogo and diagnostic test development.","PeriodicalId":143102,"journal":{"name":"Annual Reliability and Maintainability Symposium 1995 Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132532964","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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