1,720,968 research outputs found
Energy-Efficient Control in Multi-Stage Production Lines with Parallel Machine Workstations and Production Constraints
Get PDFNowadays, the growing interest in industry for enhancing manufacturing processes sustainability is a major trend. One of the most supported strategies to increase the energy-efficiency of manufacturing activities is the control of machine state towards the optimum trade-off between production rate and energy demand. This method is referred to as energy-efficient control and it triggers machines in a standby state with low power request. In this paper, multi-stage production lines composed of identical parallel machine workstations are the systems of interest, and the energy-efficient control policies make use of buffer level information. Each machine can be switched off instantaneously and switched on with a stochastic startup time. Problem objective is to minimize the energy demand while assuring production constraints. The paper proposes a novel approach to solve the problem at hand. An exact model for two-stage system is formulated using a Markov Decision Process to be solved with a linear programming methodology. A novel technique, namely the Backward-Recursive approach, is used to address systems with more than two stages. Numerical experiments confirm the effectiveness of the proposed approach
Reinforcement learning for sustainability enhancement of production lines
No full textThe importance of sustainability in industry is dramatically rising in recent years. Controlling machine states to achieve the best trade-off between production rate and energy demand is an effective method for improving the energy efficiency of production systems. This technique is referred to as energy-efficient control (EEC) and it triggers machines in a standby state with low power requests. Reinforcement Learning (RL) algorithms can be used to successfully control production systems without the requirement of prior knowledge about system parameters. Due to the difficulty in acquiring comprehensive information about system dynamics in real-world scenarios, this is considered an important factor. The goal of this work is to create a novel RL-based model to apply EEC to multi-stage production lines with parallel machine workstations without relying on full knowledge of the system dynamics. Numerical results confirm model benefits when applied to a real line from the automotive sector. Further experiments confirm the effectiveness and generality of the approach
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Analysis of the near flatness phenomenon for multi-loop closed manufacturing systems
Get PDFWith the recent development of the electrical vehicle (EV) industry, the study of manufacturing systems producing key components in this sector is becoming increasingly important. Multi-loop closed manufacturing systems (MCMS), whose operation and control are rarely studied in the literature, are widely used in the EV industry. This work provides innovative guidelines for MCMS operation also valid in a general context and not necessarily limited to the EV field. The main focus is on a specific topic of MCMS operation, namely the near flatness phenomenon. The near flatness indicates how system throughput is influenced by its population, i.e. the number of items circulating in the MCMS, especially in high-throughput conditions. The study of near flatness aims at enhancing MCMS flexibility in terms of population control and handling while guaranteeing high system throughput. In this work, a new indicator quantitatively describing the near flatness is provided. Numerical studies are conducted to analyze the effect of machine efficiency in isolation, mean times to repair and buffer capacities on the near flatness. Experiments are also carried out on a real case of MCMS in the EV field. Based on the experimental results, practical specifications to improve MCMS design and management are provided
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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