2018
Authors
Escada, J; Coelho, LCC; Dias, THVT; Lopes, JAM; dos Santos, JMF;
Publication
JOURNAL OF INSTRUMENTATION
Abstract
Experimental measurements of the extraction efficiency f of the photoelectrons emitted from a reflective CsI photocathode into Ar-CF4 and Xe-CF4 gaseous mixtures are presented, as a function of reduced electric field E/p in the range 0.1 to 3 V cm(-1) Torr(-1) and as a function of CF4 concentration. The experimental data is compared to Monte Carlo simulation results. The investigation confirms that backdiffusion of low-energy photoelectrons emitted from a photocathode into a gas medium depends strongly on the nature of the gas. The effect is especially significant in pure noble gases, but it can be considerably reduced by the admixture of certain molecular gases, like CF4.
2018
Authors
Barros Ribeiro, ECB; Moreira, AC; Ferreira, LMDF; Cesar, AD;
Publication
JOURNAL OF CLEANER PRODUCTION
Abstract
The objective of this study is to identify, through motivating, inhibiting and facilitating factors, responses to institutional pressures on the relationship between biodiesel plants and family farming cooperatives via the Social Fuel Seal (SFS) in the South region of Brazil. This region is characterized by well-endowed family farming cooperatives. This paper adopts as theoretical lens the institutional theory. It is based on case studies involving qualitative research drawing results from four biodiesel plants with SFS certification and eight family farming cooperatives. The results indicate that the institutional biodiesel framework influenced the SFS-based relationships. This coercion mechanism led the plants to comply with the promotion of family farming via cooperatives. The plants seek legal legitimacy and opt to accept institutional pressures, primarily due to the guaranteed sale of all biodiesel produced via government sponsored auctions. Cooperatives are attracted by the receipt of the social bonus, seen as a prime motivating factor, which can be interpreted as an informal coercive pressure. Considering the context in which the plants and cooperatives are inserted, the SFS promoted changes in the sale of raw materials. It was also found that cooperatives facilitating factors are inversely related with plants inhibiting factors.
2018
Authors
Carvalhais, M; Cardoso, P;
Publication
Estudos em Comunicacao
Abstract
Computational media allow the development of very particular relationships with readers. Their nature allows them to register static information but also complex and contingent behaviours that they are capable to operationalise, thus becoming interactive and immersive. These media exist in a dual state between a surface layer and a subface layer. These two are inextricably connected, with the subface often becoming a black box that can only be peered at through surface effusions that both mediate and isolate it. The procedural layer of the subface can be discovered through a process of virtuosic interpretation that allows readers to form a theory of system, breeding empathy with it, and ultimately, transferring some of its processes to their minds. This paper focuses on how virtuosic interpretation is developed, and how from it stems the development of a unique kind of aesthetic experience. It explores how computational media, through anamorphosis and a dialectics of aporia and epiphany, become narrative games. © 2018 Universidade da Beira Interior.All right reserved.
2018
Authors
Moutinho, V; Madaleno, M; Robaina, M; Villar, J;
Publication
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
Abstract
This paper analyzes a set of selected German and French cities' performance in terms of the relative behavior of their eco-efficiencies, computed as the ratio of their gross domestic product (GDP) over their CO2 emissions. For this analysis, eco-efficiency scores of the selected cities are computed using the data envelopment analysis (DEA) technique, taking the eco-efficiencies as outputs, and the inputs being the energy consumption, the population density, the labor productivity, the resource productivity, and the patents per inhabitant. Once DEA results are analyzed, the Malmquist productivity indexes (MPI) are used to assess the time evolution of the technical efficiency, technological efficiency, and productivity of the cities over the window periods 2000 to 2005 and 2005 to 2008. Some of the main conclusions are that (1) most of the analyzed cities seem to have suboptimal scales, being one of the causes of their inefficiency; (2) there is evidence that high GDP over CO2 emissions does not imply high eco-efficiency scores, meaning that DEA like approaches are useful to complement more simplistic ranking procedures, pointing out potential inefficiencies at the input levels; (3) efficiencies performed worse during the period 2000-2005 than during the period 2005-2008, suggesting the possibility of corrective actions taken during or at the end of the first period but impacting only on the second period, probably due to an increasing environmental awareness of policymakers and governors; and (4) MPI analysis shows a positive technological evolution of all cities, according to the general technological evolution of the reference cities, reflecting a generalized convergence of most cities to their technological frontier and therefore an evolution in the right direction.
2018
Authors
Neves, F; Machado, N; Pereira, J;
Publication
2018 48TH ANNUAL IEEE/IFIP INTERNATIONAL CONFERENCE ON DEPENDABLE SYSTEMS AND NETWORKS (DSN)
Abstract
Programmers and support engineers typically rely on log data to narrow down the root cause of unexpected behaviors in dependable distributed systems. Unfortunately, the inherently distributed nature and complexity of such distributed executions often leads to multiple independent logs, scattered across different physical machines, with thousands or millions entries poorly correlated in terms of event causality. This renders log-based debugging a tedious, time-consuming, and potentially inconclusive task. We present Falcon, a tool aimed at making log-based analysis of distributed systems practical and effective. Falcon's modular architecture, designed as an extensible pipeline, allows it to seamlessly combine several distinct logging sources and generate a coherent space-time diagram of distributed executions. To preserve event causality, even in the presence of logs collected from independent unsynchronized machines, Falcon introduces a novel happens-before symbolic formulation and relies on an off-the-shelf constraint solver to obtain a coherent event schedule. Our case study with the popular distributed coordination service Apache Zookeeper shows that Falcon eases the log-based analysis of complex distributed protocols and is helpful in bridging the gap between protocol design and implementation.
2018
Authors
Torres, MF; Sousa, AJ; Torres, RT;
Publication
INTERNATIONAL JOURNAL OF TECHNOLOGY AND DESIGN EDUCATION
Abstract
Replanning is often used to optimize results of an activity in an ever changing world. To address the challenge of preparing future engineers for success, a special course was created for all engineering freshmen of the Faculty of Engineering of the University of Porto, in Portugal. Presented as a case study, this special course underwent a careful replanning as a result of several years of experience in teaching practice alongside with a theoretical deepening in pedagogical and technological issues, under the aegis of the action-research methodology. Within the context of the case study course, the mentioned replanning was also based on a theoretical approach that clearly identifies teaching-learning-assessment methodologies that promote regulation from those that foster emancipation, using a specific instrument: a taxonomy of educational processes. The replanning was designed to globally boost results regarding the educational aims of the course such as furthering freshmen's integration into work environment and preparing them for success by fostering transversal skills (needed for study and work). Technology is seen as a mean of education enrichment as well as a productivity tool. The introduced innovations include fun-but-educational activities, several types of assessment over time and specific technological tools which were critical for the educational impact/achievement of this course. Success is demonstrated by encouraging feedback from the stakeholders, high students' classifications and a steady reduction in retention. It is advocated that large portions of the reasoning behind the replanning can be extrapolated to other courses.
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