Search

Coriandrum sativum and Allium sativumare belong to family alliaceae which is famous for its culinary and medicinal properties. These two sativum species’ seeds and cloves extracts are chosen to synthesize the cobalt oxide nanoparticles because it is eco- benign, secure as well as cost – effective method. The reducing sugar such as glucose which is present naturally in the extract used as reducing agent instead a harmful chemicals as reducing agent. The synthesized cobalt oxide nanoparticles using sativum species were characterization using UV–Visible spectroscopy, FT-IR spectroscopy, EDAX and SEM. The optical absorption spectrum for Co3O4 nanoparticles are studied using UV–Visible spectroscopy. The FT-IR spectrum confirms the presence of functional group in cobalt oxide nanoparticles. Scanning Electron Microscopy was employed to analyze the morphology, it shows that synthesized cobalt oxide nanoparticles show different morphology, which depends on the nature of the extract and of the compound present the extract. The EDAX studies show that the presence of cobalt and oxygen elements in the synthesized nanoparticles. Photo - catalytic activity of the synthesized nanoparticles was evaluated by degradation of Rhodamine B dye.

The class of transmuted distributions has received a lot of attention in the recent statistical literature. In this paper, we propose a rich family of bivariate distribution whose condition...

Quantile-based reliability analysis has received much attention recently. We propose new quantile-based tests for exponentiality against decreasing mean residual quantile function (DMRQ) and new better than used in expectation (NBUE) classes of alternatives. The exact null distribution of the test statistic is derived when the alternative class is DMRQ. The asymptotic properties of both the test statistics are studied. The performance of the proposed tests with other existing tests in the literature is evaluated through simulation study. Finally, we illustrate our test procedure using real data sets.

The stochastic behaviour of lifetimes of a two component system is often primarily influenced by the system structure and by the covariates shared by the components. Any meaningful attempt to model the lifetimes must take into consideration the factors affecting their stochastic behaviour. In particular, for a load share system, we describe a reliability model incorporating both the load share dependence and the effect of observed and unobserved covariates. The model includes a bivariate Weibull to characterize load share, a positive stable distribution to describe frailty, and also incorporates effects of observed covariates. We investigate various interesting reliability properties of this model using cross ratio functions and conditional survivor functions. We implement maximum likelihood estimation of the model parameters and discuss model adequacy and selection. We illustrate our approach using a simulation study. For a real data situation, we demonstrate the superiority of the proposed model that incorporates both load share and frailty effects over competing models that incorporate just one of these effects. An attractive and computationally simple cross-validation technique is introduced to reconfirm the claim. We conclude with a summary and discussion.

The notion of cascading failures is a common phenomenon we observe around us. Here the initial failure alters the structure function of the system, which leads to subsequent failures within a short period of time referred to as threshold time. [17] introduced the concept of cascading failures within the framework of reliability theory. Swift [24] extended the Freund bivariate exponential distribution to model cascading failures. The Freund bivariate exponential distribution [10] allows to model a parallel redundant system with two components. In this system the lifetimes of the two components behave as if they are independent, until one of the components fail, after which the remaining component suffers an increased/decreased stress. In this paper we further study the model of Swift [24]. Various properties of the model are investigated and statistical inference procedures are developed using L-moments and method of moments. A practical application of this model is illustrated using data from www....

SYNOPTIC ABSTRACTSeveral authors have considered the analysis of load-sharing parallel systems. The main characteoristics of such a two-component system is that after the failure of one component, the surviving component has to shoulder extra load, and hence, it is more likely to fail earlier than would be expected under the original model. In other cases, the failure of one component may release extra resources to the other component, thus delaying the system failure. Freund introduced a bivariate extension of the exponential distribution, which is applicable to two-component load-sharing systems. It is based on the assumption that the lifetime distributions of the components are exponential random variables before and after the change. In this article, we introduce a new class of bivariate distribution using the proportional hazard model. It is observed that the bivariate model proposed by Freund is a particular case of our model. We study different properties of the proposed model. Different statistica...

The present paper aims at studying the mean past lifetime of a discrete random variable. The notion of discrete mean past lifetime is studied in relation to the concepts of reversed hazard rate, reversed lack of memory property, and cumulative past entropy. New classes of distributions characterized by particular forms of discrete mean past life are also investigated. Implications of an increasing mean past lifetime on other reliability notions are studied and finally some bivariate generalizations are discussed.

International audience; AbstractLeafcutter bees collect leaf discs to encase brood cells. However, our understanding of their use of plants as nesting resources, which is critical for their conservation, is poor. We followed plants and observed bees cutting leaves to understand the leaf and plant traits of the leaf forage plants of Megachile spp. We studied whether the leaf size explains the cut size and the number of cuts in the leaves. The bees collected leaves from 59 species, 49 genera and 25 families of plants of various habits. Plant habit, leaf morphotype and leaf size did not influence leaf choice by the bees. Of the plants surveyed, 45.22% had the distinguishable cutting marks. About 63% and 98% of the plants the bees used are native to the region and to the tropical southern hemisphere, respectively. Bees selected leaves over an extreme size range, and the leaf size predicted the number of cuts on a leaf. Comparing our results with other studies, we conclude that the leafcutter bees’ selection of plants is adapted to the local environment.