1,720,980 research outputs found
Energy recovery of blast-furnace gas coke: the importance of a correct regulation system
No full textThe present work deals with the regulation system of a plant recovering the energy of blast-furnace gas coke residual pressure. Such a plant is equipped with a turbogenerator, which produces electric energy, expanding the gas coke up to the mill pipe network pressure value. Before revamping, the regulation system consisted of an automatic nozzle control of a turbine stator and a throttle valve. Once the system became operative, the regulation system seemed to be inadequate because it caused a significant reduction in energy recovery due to the variation of the gas coke characteristics, compared to the original engineering specifications. A mathematical model for the plant simulation has been developed through the regulation system static and dynamic responses. This simulation, together with a series of experimental tests, identified the causes of the operational problems in the original regulation system. On the basis of the response times of the old regulation system, a valve with reduced intervention inertia has been suggested. The regulation logic was also modified: The valve interventions were directly linked to the presence variations recorded at the blast furnace top, and no longer to the opening variation of the turbine automatic system. A more rational use of the plant components and its control system, together with an increased of the electric energy production, have been demonstrated
Energy recovery of blast-furnace gas coke. The importance of a correct regulation system
No full textThe present work deals with the regulation system of a plant recovering the energy of blast-furnace gas coke residual pressure. Such plant is provided by a turbogenerator which produces electric energy expanding the gas coke up to the mill pipe network pressure vallue. Before intervention the regulation apparatus consisted of an automatic vane orientation system of a turbine stator and a throttle valve. Once the system has become operative, the regulation set seemed to be inadequate showing a significant reduction in energy recovery due to the variation of the gas coke characteristics, compared to the original engineering specifications. A mathematical model for the plant simulation has been developed throughly the regulation system static and dynamic responses. This simulation together with a series of experimental tests indicated the causes of the operation problems in the original regulation system. On the base of the response times of the old regulation system, a valve with reduced intervention inertia has been introduced. The regulation logic was also modified: the valve interventions were directly linked to the pressure variations recorded at the blast furnace top, and no longer to the opening variation of the turbine automatic system. A more rational use of the plant components and its control system, together with and increase of the electric energy production have been the final results
Numerical Investigations on the Working Cycle of a Hydraulic Breaker: Off-Design Performance and Influence of Design Parameters
No full textThermal mapping analysis of a 48V prismatic lithium-ion battery pack with active and passive cooling
Full text linkThis experimental study investigates the thermal behavior of a 48V lithium-ion battery (LIB) pack comprising three identical modules, each containing 12 prismatic LIB cells, during five charge-discharge cycles. A homogeneous liquid cooling system is applied at the bottom of the modules to control the pack temperature when it reaches 40°C (active cooling phase). The initial two cycles represent passive cooling, where the cooling liquid remains stationary. Temperature distribution is measured and analyzed using 27 thermocouples, providing insights into temperature changes in the cells, modules, pack, and cooling system inlet/outlet. Results show that in passive cooling cycles, minimum temperature occurs at pack surfaces due to better convective heat transfer, while maximum temperature is observed in the central LIB cells. The active cooling phase alters the temperature distribution within the pack. One module is found to be more sensitive to high currents, generating more heat and releasing it faster. Additionally, the positive tab temperature is higher than the negative tab temperature within a single cell. The liquid cooling system decreases the temperature rise from 5.8°C to 3.5°C in the discharge cycles with a constant current of -237A. This study emphasizes the significance of evaluating the thermal behavior of individual modules and highlights the complexity of the LIB pack system, as well as the impact of an indirect liquid cooling system on enhancing its thermal performance
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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
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