Reliability analysis of prototypes based on small and heterogeneous test data volumes. Case study: Organic fibre prototype analysis

Author(s):  
V Murugesan ◽  
Sreejith Plappillimadam ◽  
VJ Saji ◽  
SS Maruthi ◽  
AK Anilkumar

Reliability is one of the critical design parameters for the launch vehicles and its systems. When the systems are ready to fly the first time, only limited test data are available and accordingly reliability assessed will be very low. However, in most cases, the new systems are derived and developed using the knowledge and experience gained from the heritage systems to meet the fresh challenges. Hence, the reliability assessed with the minimum number of tests done on the new system does not truly reflect the inherent reliability of the system. In this paper, an approach and a new analytical model are developed for the reliability assessment of systems with limited test data, giving an accurate weighting for the tests and flight experiences with similar systems. The method gives a systematic procedure for arriving at the weighting factor for test data of the pedigree system, with due consideration of the similarities between the systems and various factors influencing system reliability. The method is illustrated with a case study of a newly developed liquid propellant rocket system. The model is validated using the available test and flight data of two propulsion systems with adequate flight experience. The analytical model is generic in nature and can be applied to reliability analysis of any system, which has considerable similarities with a pedigree system.


Author(s):  
Jun-Xian Fu ◽  
Shukri Souri ◽  
James S. Harris

Abstract Temperature and humidity dependent reliability analysis was performed based on a case study involving an indicator printed-circuit board with surface-mounted multiple-die red, green and blue light-emitting diode chips. Reported intermittent failures were investigated and the root cause was attributed to a non-optimized reflow process that resulted in micro-cracks and delaminations within the molding resin of the chips.


2003 ◽  
Vol 42 (05) ◽  
pp. 564-571 ◽  
Author(s):  
M. Schumacher ◽  
E. Graf ◽  
T. Gerds

Summary Objectives: A lack of generally applicable tools for the assessment of predictions for survival data has to be recognized. Prediction error curves based on the Brier score that have been suggested as a sensible approach are illustrated by means of a case study. Methods: The concept of predictions made in terms of conditional survival probabilities given the patient’s covariates is introduced. Such predictions are derived from various statistical models for survival data including artificial neural networks. The idea of how the prediction error of a prognostic classification scheme can be followed over time is illustrated with the data of two studies on the prognosis of node positive breast cancer patients, one of them serving as an independent test data set. Results and Conclusions: The Brier score as a function of time is shown to be a valuable tool for assessing the predictive performance of prognostic classification schemes for survival data incorporating censored observations. Comparison with the prediction based on the pooled Kaplan Meier estimator yields a benchmark value for any classification scheme incorporating patient’s covariate measurements. The problem of an overoptimistic assessment of prediction error caused by data-driven modelling as it is, for example, done with artificial neural nets can be circumvented by an assessment in an independent test data set.


Author(s):  
Oladimeji Joseph Ayamolowo ◽  
Chukwunonso Anthony Mmonyi ◽  
Samson Olasunkanmi Adigun ◽  
Olabisi Abdullahi Onifade ◽  
Kehinde Adetunji Adeniji ◽  
...  

1980 ◽  
Vol 51 (3) ◽  
pp. 853-854
Author(s):  
Arthur Mac Neill Horton ◽  
Carl H. Johnson

Rational-emotive group and bibliotherapy were used to treat a depressed patient in a clinical setting. Psychological test data document a dramatic improvement. It is suggested that rational-emotive therapy may prove efficacious for the treatment of some depressed patients in clinical settings.


2015 ◽  
Vol 55 (2) ◽  
pp. 393-403 ◽  
Author(s):  
Yoshihisa Miyata ◽  
Richard J. Bathurst

Silva Fennica ◽  
2002 ◽  
Vol 36 (2) ◽  
Author(s):  
Martti Venäläinen ◽  
Seppo Ruotsalainen

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