A generalization of the multivariate slash distribution

In this paper, we propose a generalization of the multivariate slash distribution and investigate some of its properties. We show that the new distribution belongs to the elliptically contoured distributions family, and can have heavier tails than the multivariate slash distribution. Therefore, this generalization of the multivariate slash distribution can be considered as an alternative heavy-tailed distribution for modeling data sets in a variety of settings. We apply the generalized multivariate slash distribution to two real data sets to provide some illustrative examples.     

An alternative approach to minimize model inadequacy

In this article Bock's (1975) approach is used to fit a class of lower order polynomials to a higher order response function. For a wide class of conditions our fitted models offer greater protection, in some sense, against model inadequacies than the one fitted by Karson, Manson and Hader (1969). However, our approach is applicable to the situations where the assumption of normality about the distribution of the response variable is appropriate.     

Building resilience in SMEs of perishable product supply chains: enablers,barriers and risks

SMEs of perishable product supply chains (PPSCs) are critical to sustaining fresh food supply and global economy. However, they face immense challenges given the nature of their operations. Surprisingly, the literature lacks research on the distinct intra- and inter-organisational factors intertwined to build resilience in these firms. From the semi-structured interviews conducted with 30 managers of a PPSC in Australia, we developed a holistic framework to build resilience in SMEs of PPSCs. The findings offer novel insights into research and practice including an optimal portfolio of enablers, barriers and risks towards building resilience. The analysis reveals that most risks stem from the factors that are internal to the supply chain, thus necessitating a strong supply chain collaboration. The level of resilience, barriers and risks varies considerably within SMEs depending on their size (small vs. medium) and location of nodes in the supply chain. Interestingly, the SMEs with consortium support demonstrate better resilience and performance.     

Lebanon's economic reconstruction after the war: A bridge too far?

Since the onset of the Civil War in 1975 Lebanon has experienced burgeoning fiscal deficits and an unsustainable public debt overhang. Much of this arose from the loss of revenues during the period of the Civil War 1975–1990 and attempts to maintain basic public expenditure, while from 1990 to 2006 this reflected post-Taif rebuilding and reconstruction of key infrastructure with limited revenue capacity. Considerable progress from the 1990s had been achieved in rebuilding the shattered economy from both public and private international and domestic sources, but its legacy is a huge public debt and a servicing requirement that currently absorbs alone almost 30 per cent of total government revenue and is the highest in the world on a per capita basis. While the need to reduce this debt to a sustainable level would be daunting enough in itself, Lebanon's fiscal predicament was further compounded by the outbreak of war with Israel during July–August 2006. The consequence of this 34-day war was the devastation of residential property, vital infrastructure, loss of agricultural production, industrial production, exports, environmental damage, the collapse of tourism and a further erosion of the influence and power of the central government. Estimates of the direct and indirect costs for Lebanon of this relatively brief but devastating war conservatively vary from US$ 10–15 billion. The implications of such reconstruction and rebuilding costs for the budget and public debt are potentially calamitous for Lebanon which is already struggling under the weight of debt overhang and its servicing. A key question is whether Lebanon can tackle this enormous task in insolation.This paper explores the background to the fiscal crisis, identifies from available literature the extent, nature and cost of the war damage, analyses the options available to the authorities in rebuilding the economy and highlights key policy issues and measures that will be required if a sustainable economic recovery is to be achieved. Despite its demonstrated and remarkable resilience to past trauma the paper concludes that the fiscal crisis makes it impossible for Lebanon to tackle the reconstruction and rebuilding task on its own and particularly in the wake of the events of summer 2006. The country will require substantial and ongoing financial support from international lenders and donors. The success of these efforts in the case of Lebanon is of particular interest as it could well be a microcosm of possible future outcomes for the region more generally.     

An alternative proof of order statistics moment problem

A necessary and sufficient condition that two distributions having finite means are identical is that for any fixed integer r > 0, the expected values of their rth (n ? r) order statistics are equal [or the expected values of their (n-r)th (n > r ? 0) order statistics are equal] for all n where n is the sample size.     

NERJIT: Using Net Requirement Data in Kanban‐Controlled Jumbled‐Flow Shops

The bold lines that have separated the application of specific production planning and control techniques to specific production systems are being blurred by continuous advances in production technologies and innovative operational procedures. Oral communication among dispatchers and production units has given way to electronic communication between production planners and these units by continuous progress in information technologies. Current production literature alludes to the idea that, collectively, these advances have paved the way for application of Just‐In‐Time (JIT) production concepts, which were originally developed for mass production systems, in intermittent production systems. But this literature does not actually consider the possibility. This article presents a modification to JIT procedures to make them more suitable for jumbled‐flow shops. This article suggests providing real‐time information about net‐requirements for each product to each work center operator for setting production priorities at each work center. Simulation experiments conducted for this study show that using Net‐Requirements in JIT (NERJIT) reduces customer wait time by 45–60% while reducing inventory slightly. The analysis of work centers’ input and output stock‐point inventories shows that using the information about net‐requirements results in production of items that are in current demand. NERJIT results in smaller input stock‐point inventory and availability of products with higher priority in the output stock‐points of work centers.     

Selection of suitable prior for the Bayesian mixture of a class of lifetime distributions under type-I censored datasets

This paper explores the study on mixture of a class of probability density functions under type-I censoring scheme. In this paper, we mold a heterogeneous population by means of a two-component mixture of the class of probability density functions. The parameters of the class of mixture density functions are estimated and compared using the Bayes estimates under the squared-error and precautionary loss functions. A censored mixture dataset is simulated by probabilistic mixing for the computational purpose considering particular case of the Maxwell distribution. Closed-form expressions for the Bayes estimators along with their posterior risks are derived for censored as well as complete samples. Some stimulating comparisons and properties of the estimates are presented here. A factual dataset has also been for illustration.     

TR Multivariate Conditional Median Estimation

An affine equivariant version of the nonparametric spatial conditional median (SCM) is constructed, using an adaptive transformation–retransformation (TR) procedure. The relative performance of SCM estimates, computed with and without applying the TR-procedure, are compared through simulations. Also included is the vector of coordinate conditional, kernel-based medians (VCCMs). The methodology is illustrated via an empirical data set. The simulations indicate that the TR-SCM estimator is more efficient than the SCM estimator for data generated from asymmetric contaminated trivariate normals. However, when the dimension of the covariates increases the efficiency of the TR-SCM estimator decreases. The TR-VCCM- and VCCM estimators lack efficiency, and consequently should not be used in practice.     

Parametric inference in a perturbed gamma degradation process

Abstract

We consider a degradation model which is the sum of two independent processes: an homogeneous gamma process and a Brownian motion. This model is called perturbed gamma process. Based on independent copies of the perturbed gamma process observed at irregular instants we propose to estimate the unknown parameters of the model using the moment method. Some general conditions allow to derive the asymptotic behavior of the estimators. We also show that these general conditions are fulfilled for some specific observation schemes. Finally, we illustrate our method by a numerical study and an application to a real data set.