A mathematical model and genetic algorithm-based approach for parallel two-sided assembly line balancing problem

Assembly lines are usually constructed as the last stage of the entire production system and efficiency of an assembly line is one of the most important factors which affect the performance of a complex production system. The main purpose of this paper is to mathematically formulate and to provide an insight for modelling the parallel two-sided assembly line balancing problem, where two or more two-sided assembly lines are constructed in parallel to each other. We also propose a new genetic algorithm (GA)-based approach in alternatively to the existing only solution approach in the literature, which is a tabu search algorithm. To the best of our knowledge, this is the first formal presentation of the problem as well as the proposed algorithm is the first attempt to solve the problem with a GA-based approach in the literature. The proposed approach is illustrated with an example to explain the procedures of the algorithm. Test problems are solved and promising results are obtained. Statistical tests are designed to analyse the advantage of line parallelisation in two-sided assembly lines through obtained test results. The response of the overall system to the changes in the cycle times of the parallel lines is also analysed through test problems for the first time in the literature.     

Effect of COVID-19 on Household Food Insecurity and Poverty: Evidence from Ghana

Social Indicators Research - Following the outbreak of COVID-19 and its heavy toll on the global community and humanity, a fierce debate on the pandemic and Sustainable Development Goals (SDGs)...     

FDA: strong consistency of the kNN local linear estimation of the functional conditional density and mode

In this paper we present a new estimator of the conditional density and mode when the co-variables are of functional kind. This estimator is a combination of both, the k-Nearest Neighbours procedure and the functional local linear estimation. Then, for each statistical parameter (conditional density or mode), results concerning the strong consistency and rate of convergence of the estimators are presented. Finally, their performances, for finite sample sizes, are illustrated by using simulated data.     

Technical and vocational education and training in Uganda: A critical analysis

This article undertakes a diagnostic study of the Technical and Vocational Education and Training (TVET) sub‐sector in Uganda, with a view to characterizing the sub‐sector and identifying its potential strengths and weakness. We undertook a cross‐sectional pre‐survey of purposively selected key stakeholders in the TVET sub‐sector. We selected performance indicators following their importance in influencing the TVET reform process. Both qualitative and quantitative data was solicited from the stakeholders. Quantitative data was collected through stakeholder‐specific structured questionnaires, whilst qualitative data was collected through desk review and field visits, individual focused interviews and focus group discussions. Our findings indicate that financing and planning constraints have resulted in poor quality equipment, under‐ and ill‐trained staff, limited adoption of a competence‐based education and training (CBET) curriculum, not to mention the supervision inadequacies of TVET institutions. Besides, the limited TVET sub‐sector interaction with the private sector has incapacitated TVET curriculum development to nurture skills demanded by the private sector. Furthermore, backward technology use in the private sector has equally inhibited the success of student attachment programmes. Finally, legal ambiguities have perpetuated a qualification jungle and overlapping curricula.     

Reversed preservation of stochastic orders for random minima and maxima with applications

In this paper, reversed preservation properties of right spread order, total time on test order and increasing convex (concave) order when taking random minima and maxima are developed. In this context, reversed preservation properties of some ageing concepts are investigated under parallel (series) systems which are composed of a random number of i.i.d. components. Some applications in reliability and economics are given.     

Bayesian methods for generalized linear models with covariates missing at random

The authors propose methods for Bayesian inference for generalized linear models with missing covariate data. They specify a parametric distribution for the covariates that is written as a sequence of one‐dimensional conditional distributions. They propose an informative class of joint prior distributions for the regression coefficients and the parameters arising from the covariate distributions. They examine the properties of the proposed prior and resulting posterior distributions. They also present a Bayesian criterion for comparing various models, and a calibration is derived for it. A detailed simulation is conducted and two real data sets are examined to demonstrate the methodology.     

Using the EM-algorithm for survival data with incomplete categorical covariates

Incomplete covariate data is a common occurrence in many studies in which the outcome is survival time. With generalized linear models, when the missing covariates are categorical, a useful technique for obtaining parameter estimates is the EM by the method of weights proposed in Ibrahim (1990). In this article, we extend the EM by the method of weights to survival outcomes whose distributions may not fall in the class of generalized linear models. This method requires the estimation of the parameters of the distribution of the covariates. We present a clinical trials example with five covariates, four of which have some missing values.     

War in Iraq: Environment of Insecurity and International Migration

LA GUERRE EN IRAK : CONTEXTE D'INSÉCURITÉ ET MIGRATION INTERNATIONALE
Cet article porte sur les éventuels rapports entre conflit et migration internationale, tout particulièrement dans le contexte de la plus récente guerre en Irak. Les tendances de la migration internationale irakienne sont analysées afin d'établir une éventuelle influence de la guerre sur la migration. Les situations de conflit sont répandues en Irak depuis plus de deux décennies, les racines de ces conflits remontant à 1979, année où Saddam Hussein est devenu le président de ce pays. Pendant le dernier quart de siècle, l'histoire irakienne a été marquée par des guerres et des crises d'aprèsguerre qui ont déclenché des tensions entre ethnies. D'après nous, ce sont ces tensions ethniques qui ont contribuéà la migration internationale à partir de l'Irak. C'est l'instabilité générale associée aux conflits qui engendre souvent des tensions plus vives entre différents groupes ethniques, à savoir les Kurdes, les Turkmènes, les chiites et les sunnites. Les situations de conflit ethnique peuvent mener à un contexte général d'insécurité, lequel sera une « occasion >> pour les personnes qui ont déjà des « projets >> individuels de migration. Les pays d'Europe occidentale seront particulièrement concernés par ces mouvement migratoires potentiels. Pendant les périodes de conflit, les Irakiens ont établi des réseaux de migration et formé en Occident des communautés d'immigrants assez vastes. Ces réseaux serviront également de facteurs facilitants pour la migration ethnique potentielle de certains Irakiens.