Traditional shock models view system failure time as a first passage problem. Yeh Lam proposed a new class of models called δ-shock models in which failure was dependent on the frequency of shocks. The present work generalizes Yeh Lam's results for renewal shock arrivals and random threshold. Several special cases and an optimal replacement problem are also discussed.

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Availability function which forms an important part of reliability analysis is expressed in terms of an integral equation. The analytical solution of such an equation is possible only in very simple cases and hence approximations are the only tools available; very few such approximations are available in the literature. This paper proposes three useful approximations, two of which are based only on the first few moments of the underlying distributions and do not require their functional forms. The third approximation uses the Riemannian sum to approximate the integral equation. Numerical illustrations based on test cases are provided to show the efficacy of the approximations. As an application, the problem of an opportunistic channel access scheme in a communication network is used to test the approximations.

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For long decades, Nigeria has the highest population in Africa and has been struggling by slow economic growth, poor GDP per capita, high unemployment, and a host of other problems.These problems affect the country's energy sector which in turn leads to a negative crisis feedback loop. The Nigeria energy sector has been labeled by both its citizens and foreigners as a total failure in terms of economic perspective. Despite the continuous government investment over the years, there has been a slight growth in the sector with an ever-rising demand due to its population explosion, leading to a total breakdown across Nigeria economic and industrial development. This study aims to examine how the country can maximize its full energy potential by turning towards the vast quantities of solar resources at its disposal. A review of the nation’s solar energy policies was done with the aim to identify the barriers hindering the country’s solar development, the serviceability of solar energy to the country. Researchers attempt to demonstrate Nigeria's energy gains through the incorporation of solar energy into the country's energy resources.

In an attempt to enrich existing literature on online fashion brand communities in the digital era, this research aimed at exploring the relationship between peer influence and self-disclosure on sustaining consumer engagement in generating loyalty to social media fashion brand communities (SMFBCs). The survey included a sample of 365 members who follow local Nigerian SMFBCs and was analyzed using SmartPLS v3.2.9. Findings from the study show that peer influence and self-disclosure have a positive impact on sustaining consumer engagement in social media fashion brand communities. Furthermore, the findings show that self-disclosure mediated the relationship between peer influence and sustaining consumer engagement. Finally, consumer engagement fosters loyalty to social media brand communities.

Regression analysis refers to methods by which estimates are made for the model parameters from the knowledge of the values of a given input-output data set. The aim of this research this research is to find a suitable model and determine the ‘best’ values of the parameters of the model from the given data. In the statistical regression analysis, deviations between the observed output values and corresponding values predicted by the model are attributed to random errors. It is often assumed that the distribution of these random errors is Gaussian. On the other hand, in fuzzy regression analysis the deviations (errors) are attributed to the imprecision or the vagueness of the system structure or data. The research proposed a new fuzzy linear programming model. The new proposed model is compared with the models used in the literature which are Tanaka, Hojati and Tansu regression models. The results are presented and comparison has been done for each model. Eleven different applications have been mentioned. Then the comparison of results of all the application regarding each similarity measure of goodness of fit is stated in the paper.