Scheduling with interjob communication on parallel processors

Consider a scheduling problem in which a set of tasks needs to be scheduled on m parallel processors. Each task \(T_i\) consists of a set of jobs with interjob communication demands, represented by a weighted, undirected graph \(G_i\). The processors are assumed to be interconnected by a shared communication channel, which can be used by jobs to communicate among each other while being processed in parallel. In each time step, the scheduler assigns jobs to the processors and allows any processed job to use a certain capacity of the channel in order to satisfy (parts of) its communication demands to adjacent jobs processed in the same step. The goal is to find a schedule with minimum length in which the communication demands of all jobs are satisfied. We show that this problem is NP-hard in the strong sense even if the number of processors is constant and the underlying graph is a single path or a forest with arbitrary constant maximum degree. Consequently, we design and analyze approximation algorithms with asymptotic approximation ratio \(\min \{1.8, 1.5 \frac{m}{m-1}\}+1\) if the underlying graph G, the union of the \(G_i\), is a forest. For general graphs it is \(\min \left\{ 1.8, \frac{1.5m}{m-1}\right\} \cdot \left( \text {arb}(G) + \frac{5}{3}\right) \), where \(\text {arb}(G)\) denotes the arboricity of G.     

The impact of attitudes and behavioral costs on environmental behavior: A natural experiment on household waste recycling

Numerous studies have shown the importance of incentives as well as of attitudes in explaining pro-environmental behavior. Reported attitude effects, however, are generally rather small and exhibit considerable variation among studies. Different theoretical perspectives can account for this finding: whereas theories of rational action suggest additive effects of costs and attitudes, the low-cost hypothesis and dual-process theories imply interaction effects - in different directions, resulting from different mechanisms. The present study tries to overcome the shortcomings of past research by using advanced statistical methods to test competitive hypotheses in the context of post-consumer waste recycling. We utilize data from a natural experiment on recycling participation in Cologne/Germany (n = 1882) in which the incentive structure for recycling changed due to the conversion of the recycling scheme from a drop-off system to curbside collection. In order to avoid self-selection bias, we conducted pre- and post-treatment surveys and applied conditional fixed-effects regression models. We found that curbside collection had a strong impact on recycling participation and attitudes had a moderate effect. The interaction is negative but statistically insignificant. Our findings contradict the low-cost hypothesis and provide some evidence that environmental concerns moderate the effect of the recycling scheme. We cannot, however, reject the rational choice proposition of mere additive effects.     

Agency and clientship in public encounters: co‐constructing ‘neediness’ and ‘worthiness’ in shelter placement meetings

This article seeks to develop our understanding of the agency of vulnerable groups who at first sight may not seem to have much agency in their lives. It explores the co‐constructed nature of agency in three Danish homeless shelters. Unlike earlier interview‐based studies, our research is based on naturalistic data drawn from 23 video‐recorded placement meetings. Using concepts from Goffman, we examine how versions of the neediness and worthiness of homeless people are negotiated verbally and bodily between staff and clients. We find that homeless people have to juggle two partly contradictory roles when they are given or take the roles of either a (active) citizen or a (passive) client. Clientship is actively negotiated by both parties and demonstrates the agency of homeless people: they can collaborate with (as clients) or challenge (as citizens) the staff’s attempts to formulate solutions to their troubles. We further examine how the professional ideology of client centredness affects the meeting between the two parties. However, we show that, like any discourse, client centredness has no intrinsic meaning and is played out by actors in very different ways. In work with the homeless, the discourse of client centredness is related to discourses of ‘neediness’, ‘worthiness’ and ‘value for money’ that define agency in different ways and make three different client positions available: the resolute client, the acquiescent client and the passive client.     

On the road toward the development of clothing size standards and safety devices for Chilean workers

The range of sizes used in Chile for clothing comes from criteria developed in continental Europe, mainly the EN 13402 standard. Any standard adopted by a country should consider the anthropometric dimensions of the user population, particularly to discern the ratio of garments for different size. Consequently, the purpose of this study was to propose standards for the size of clothing based on anthropometric characteristics of a sample of Chilean miners. The study was conducted in 447 male workers. The age and body weight were measured in each workers as well as their percentage of body fat. Anthropometric measurements for garments were made according to the criteria of the European Community (EN 13402-1) and ISO (8559- 1989). Body dimensions for the design of gloves, shoes, helmets and caps, clothes that cover the upper part of the body and clothes that cover the lower part were measured. The results obtained made it possible to establish the percentage of workers falling within the range of sizes that manufacturers consider as reference. One of the main conclusions of the study is the need to carefully consider a set of complementary anthropometric measures, which can help to improve the comfort of costumes, to the extent that the providers adapt their designs to the characteristics of Chilean workers.     

Radiological emergency response for community agencies with cognitive task analysis, risk analysis, and decision support framework

Radiological nuclear emergency responders must be able to coordinate evacuation and relief efforts following the release of radioactive material into populated areas. In order to respond quickly and effectively to a nuclear emergency, high-level coordination is needed between a number of large, independent organizations, including police, military, hazmat, and transportation authorities. Given the complexity, scale, time-pressure, and potential negative consequences inherent in radiological emergency responses, tracking and communicating information that will assist decision makers during a crisis is crucial. The emergency response team at the Angra dos Reis nuclear power facility, located outside of Rio de Janeiro, Brazil, presently conducts emergency response simulations once every two years to prepare organizational leaders for real-life emergency situations. However, current exercises are conducted without the aid of electronic or software tools, resulting in possible cognitive overload and delays in decision-making. This paper describes the development of a decision support system employing systems methodologies, including cognitive task analysis and human-machine interface design. The decision support system can aid the coordination team by automating cognitive functions and improving information sharing. A prototype of the design will be evaluated by plant officials in Brazil and incorporated to a future trial run of a response simulation.     

SCOR model application in developing countries: challenges & requirements

Due to the changes in the nature of business and competition from company versus company to supply chain versus supply chain, the importance of improving the entire supply chain holistically is becoming an increasingly important topic in recent studies. Industry practitioners and academics are focusing on developing a modelling tool for this purpose. However, such efforts were unsuccessful. The main reasons for failure are that the existing models are developed and tested based on the experiences of manufacturing firms in the developed world. The nature of the existing firms, their operating and business processes situation in developing countries vary greatly from the manufacturing processes and the surrounding environment in developed countries. However, the absence of an agreed upon, common language and standardised modelling tools for the entire supply chains hampers the global supply chain improvement initiatives. This paper focuses on addressing the issue of a how standardised and widely accepted model, like the SCOR, can be applied despite the different circumstances. The firms’ supply chain characteristics and new requirement for the model adaptation were collected based on the available literature and field analysis results. The research paper results focus on the make and delivery processes for illustration and evaluation.