Some nonparametric precedence-type tests based on progressively censored samples and evaluation of power

In this paper, we consider the problem of testing the equality of two distributions when both samples are progressively Type-II censored. We discuss the following two statistics: one based on the Wilcoxon-type rank-sum precedence test, and the second based on the Kaplan–Meier estimator of the cumulative distribution function. The exact null distributions of these test statistics are derived and are then used to generate critical values and the corresponding exact levels of significance for different combinations of sample sizes and progressive censoring schemes. We also discuss their non-null distributions under Lehmann alternatives. A power study of the proposed tests is carried out under Lehmann alternatives as well as under location-shift alternatives through Monte Carlo simulations. Through this power study, it is shown that the Wilcoxon-type rank-sum precedence test performs the best.     

Flexible reasoning using sensible agent-based systems: A case study in job flow scheduling

Planning and control systems for highly dynamic and uncertain manufacturing environments require adaptive flexibility and decision-making capabilities. Modern distributed manufacturing systems assess the utility of planning and executing solutions for both system goals (e.g. minimize manufacturing production time for all parts or minimize WIP) and local goals (e.g. expedite part A production schedule or maximize machine X utilization). Sensible Agents have the ability to alter their autonomy levels to choose among a set of decision models in order to handle the differences between local and system goals. In this paper, Sensible Agents are applied to a production planning and control problem in the context of job shop scheduling and decision model theory. Sensible Agents provide for trade-off reasoning mechanisms among system and local utilities that are flexible and responsive to an agent's abilities, situational context and position in the organizational structure of the system.     

Physiologically-Based Pharmacokinetic Modeling of a Mixture of Toluene and Xylene in Humans

A physiologically-based pharmacokinetic (PBPK) model for a mixture of toluene (TOL) and xylene (XYL), developed and validated in the rat, was used to predict the uptake and disposition kinetics of TOL/XYL mixture in humans. This was accomplished by substituting the rat physiological parameters and the blood:air partition coefficient with those of humans, scaling the maximal velocity for hepatic metabolism on the basis of body weight^0.75, and keeping all other model parameters species-invariant. The human TOL/XYL mixture PBPK model, developed based on the quantitative biochemical mechanism of interaction elucidated in the rat (i.e., competitive metabolic inhibition), simulated adequately the kinetics of TOL and XYL during combined exposures in humans. The simulations with this PBPK model indicate that an eight hour co-exposure to concentrations that remain within the current threshold limit values of TOL (50 ppm) and XYL (100 ppm) would not result in significant pharmacokinetic interferences, thus implying that data on biological monitoring of worker exposure to these solvents would be unaffected during co-exposures.     

Risk and resilience factors for substance use among street adolescents: Assessment and development of an integrative model

In this study, risk and protective factors for substance use were explored to develop an intervention program and test its efficacy among male street‐based adolescents. Twenty expert interviews and key informant interviews were conducted. In addition, 30 street adolescents (15 substance‐users and 15 non‐users) participated in four focus group discussions for needs assessment, wherein risk and protective factors were discussed. Based on the identified needs, an intervention package was developed and validated by experts. The package was implemented in a natural environment of 50 street adolescents. After the intervention, about 60% of the respondents quit or cut down on their substance use substantially, and approximately 40% of the respondents agreed to reunite with their respective families, while 20% did not change their substance use habits. The results showed that if several protective factors were present, there was a lower risk of substance use. Many factors contribute to substance use and protective factors need to be strengthened in order to make interventions effective.     

Prioritising indicators in improving supply chain performance using fuzzy AHP: insights from the case example of four Indian manufacturing companies

Abstract

In this contribution, we aim to prioritise the indicators to enhance the organisational supply chain’s (SC) effectiveness from an industrial perspective. It will help industries to develop strategies for managing the SC effectively and ensuring improvement in performance continuously. To achieve this, this work proposes to use a two-phase research methodology. First, 36 SC performance improvement indicators are recognised from a literature survey and from field and industrial expert’s inputs. Secondly, a structural model is proposed using the fuzzy analytical hierarchy process (AHP) to prioritise the indicators strategically to improve the SC performance. The fuzzy AHP method helps determine the priority of concerns of the identified indicators under fuzzy surroundings. Inputs in this research are taken from four ancillary Indian plastic manufacturing firms. Research findings indicate that collaborations and information exchange dimension indicators obtained the highest priority in improving SC performance. The model proposed is considered very useful for the SC managers/practitioners/decision-makers to understand better and distinguish the essential SC performance improvement indicators and to take systematic decisions specifically to improve the performance of business in a SC context. Sensitivity analysis was conducted to examine the priority ranking of the indicators.     

Composite sampling: effectiveness under a two stage scheme

This article describes a two stage composite sampling scheme for the detection of defectives in a sample. The costs under these schemes are compared with the costs under exhaustive testing for the binomial and hypergeometric models.     

A Virtual Cellular Manufacturing Approach to Batch Production*

In this paper, Virtual Cellular Manufacturing (VCM), an alternative approach to implementing cellular manufacturing, is investigated. VCM combines the setup efficiency typically obtained by Group Technology (GT) cellular manufacturing (CM) systems with the routing flexibility of a job shop. Unlike traditional CM systems in which the shop is physically designed as a series of cells, family-based scheduling criteria are used to form logical cells within a shop using a process layout. The result is the formation of temporary, virtual cells as opposed to the more traditional, permanent, physical cells present in GT systems. Virtual cells allow the shop to be more responsive to changes in demand and workload patterns. Production using VCM is compared to production using traditional cellular and job shop approaches. Results indicate that VCM yields significantly better flow time and due date performance over a wide range of common operating conditions, as well as being more robust to demand variability.     

Rural homelessness: its effect on healthcare access,healthcare outcomes,mobility, and perspectives of novel technologies

Rural homelessness is an undeniable public health issue that is understudied in the research literature. The purpose of this study was to determine the sociodemographics, physical and mental health status, barriers to access to care, and perspectives on potential technological advances of homeless individuals. A structured 45–90?min interview was utilized to gather demographic, physical health, mental health, mobility, and technology use data from a sample of 75 homeless individuals within three shelters in three micropolitan Nebraska cities. Individuals in this region were more likely to be white, unmarried, and mobile who have various physical and mental health disorders. Adherence to treatment of mental health disorders ranged from 43–60 percent. This population had increased employment, access to healthcare services, and use of technology than predicted. Leaders from all over the country can use these data to help improve state and local efforts to better cater to this vulnerable population's needs.     

The Role of Neighborhood Experiences in Psychological Distress Among African American and White Smokers

Race and Social Problems - Residential area characteristics and discrimination have been associated with psychological distress. Differences in these relationships across racial groups are not well...