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This paper proposed lasso estimator in parametric frailty model. Comparison of lasso (least absolute shrinkage and selection operator) and maximum likelihood (ML) estimator is done in terms of scalar mean square error (MSE). Performance of lasso estimator is examined through simulation study. Furthermore, approach is applied to analyze infant mortality in India.

This paper concerns with a complex system that comprises two subsystems in series configuration. First subsystem has n identical units that are working under k-out-of-n: G policy. All the units are connected in parallel through a switching device, which may be unreliable as and when required. Second subsystem has four identical units that are working under 2-out-of-4: G policy. Failure rates of all the units in both the subsystems are assumed to be constant and follow exponential distribution, while the repair supports general distribution and Goumbel–Hougard copula family distribution. There may be an unpredictable catastrophic failure of the system at any time (t). Failed components are replaced by the available warm standbys and hence are restored as good as new components after repair. A novel efficient technique is used to investigate the system and evaluate availability and reliability of the system, mean time to failure and profit analysis using the supplementary variable technique, Laplace transforms and copula methodology. For such a system, the evaluation of the reliability characteristics is quite complex due to availability of n − k + 1 states for first subsystem as well as a finite series developed during solution unlike as done in the past. Numerical examples are illustrated with graphs for various values of n and k. It can provide a reference for the decision-makers when developing maintenance policies.

This paper deals with the study of reliability measures of a complex engineering system consisting three subsystems namely L, M, and N in series configuration. The subsystem-L has three units working under 1-out-of-3: G; policy, the subsystem-M has two units working under 1-out-of-2: G policy and the subsystem-N has one unit working under 1-out-of-1: G; policy. Moreover, the system may face catastrophic failure at any time t. The failure rates of units of all subsystems are constant and assumed to follow the exponential distribution however, their repair supports two types of distribution namely general distribution and Gumbel-Hougaard family copula distribution. The system is analyzed by using the supplementary variable technique, Laplace transformation and Gumbel-Hougaard family of copula to derive the differential equations and to obtain important reliability characteristics such as availability of the system, reliability of the system, MTTF, and profit analysis. The numerical results for reliability, availability, MTTF, and profit function are obtained by taking particular values of various parameters and repair cost using maple. Tables and figures demonstrate the computed results and conclude that copula repair is more effective repair policy for better performance of repairable systems. It gives a new aspect to scientific community to adopt multi-dimension repair in form of copula. Furthermore, the results of the model are beneficial for system engineers and designers, reliability and maintenance managers.

The Weibull distribution is used to describe various observed failures of phenomena and widely used in survival analysis and reliability theory. Sometimes it is very difficult to compute moments of such distributions due to various reasons for e.g. analytical issues, multi parameter cases etc. This study presents the computation of the moments and the expected value of the product of order statistics in the sample from the one-parameter Weibull distribution. An alternative approach in connection to survival function is used to obtain these moments and expected values. In addition the characteristic function of the above distribution is also obtained in the form of gamma functions. Further an illustration is shown to find the first two moments and expected value of the product of order statistics by using this approach.

Infant mortality is an important indicator of nation’s socio-economic welfare. There are many socio-economic, demographic and environmental determinants of infant mortality. As infant has an innate relationship with the mother, therefore the maternal health programmes have also very important repercussion on infant health. The above two dimensions of infant mortality have seldom been examined together in infants-based studies. Thus, the survival analysis for infants regarding its several determinants along with maternal health programmes and their impact is seen in the study. The paper applies Kaplan-Meier and Cox proportional hazard model using National Family Health Survey data 2005-06, in India, to demonstrate the risk of infant death with the above said factors. Poor households are more likely to experience infant deaths than rich and middle households. Maternal health programmes have a significant effect on infant mortality, but the inclusion of breastfeeding, mother education and wealth index make these results insignificant. This study indicates that there is a need to increase birth spacing, improve mother’s education level, encourage breastfeeding and discourage teenage pregnancy in order to achieve the desired outcome of reducing infant mortality. Many interesting facets of the successful implementation of government and non-government policies on the improvement of infant survival are also discussed.

paper presents the profit analysis of a two unit cold standby system with delayed repair of partially failed unit and better utilization of units. It is assumed that the system stops functioning only when both the units fail. The failure time distributions and delayed time distribution of each unit are assumed to be negative exponential with different parameters whereas the repair time distributions are taken to general. Formulas for various reliability indices of the system including availability, busy period analysis of the repairman, and profit function analysis by using the regenerative point technique are derived. General Terms Redundancy; Standby system; Stochastic; Failure and Repair times; Correlation.

This paper analyzes the effect of socioeconomic and demographic factors on infant mortality in India. The Paper also examines reasonable comparison of the three National Family Health Survey (NFHS), the largest sample survey of India from the 1993–1994, 1998–1999 and 2005–06 with respect to different determinants of infant mortality. Accelerated Failure Time (AFT) model is used to measure the direct effect of the above factors on the survival of infants. On the basis of Akaikes Information Criterion (AIC), the Weibull AFT model fits better to other selected models. In all the three NFHS, Weibull AFT model shows the significant effect of the factors on infant survival.