1,721,121 research outputs found
L'acqua non è mai la stessa. La Cina e l'acqua. Il Giappone e l'acqua
No full textSi presenta il rapporto che la cultura cinese e la cultura giapponese hanno nella tradizione con l'elemento acqua. La parte dell'introduzione del volume dedicata alla Cina (da p. 1 a p. 9) ne descrive il rapporto con l'elemento 'acqua' nella tradizione culturaleIn the introduction is described the relationship the Chinese culture and the Japanese culture have with water in the traditional culture. The part of the introduction to the volume related to China (namely from page 1 to page 9) depicts the value of 'water' in the Chinese cultural tradition
NUMERICAL ANALYSIS AND EXPERIMENTAL INVESTIGATION OF A COMMON RAIL TYPE DIESEL INJECTOR
No full textA production common rail-type injector has been investigated via numerical simulation and experimentation. The functioning principle of the injector has been carefully analyzed so as to obtain a mathematical model of the device. A zero-dimensional approach has been used for modeling the injector, thus considering the variables as function of time only. The analysis of the hydraulic part of the injector resulted in the definition of an equivalent hydraulic scheme, on which basis both the equations of continuity in chambers and flow through nozzles were written. The connecting pipe between common rail and injector, as well as the injector internal line, were modeled according to a onedimensional approach. The moving mechanical components of the injector, such as needle, pressure rod, and control valve have been modeled using the mass-spring-damper scheme, thus obtaining the equation governing their motion. An electromagnetic model of the control valve solenoid has also been realized, in order to work out the attraction force on the anchor, generated by the electric current when flowing into its coil. The model obtained has been implemented using the MATLAB® toolbox SIMULINK®; the ordinary differential equations were solved by means of an implicit scheme of the second-order accuracy, suitable for problems with high level of stiffness, while the partial differential equations were integrated using the finite-difference Lax-Friedrichs method. The experimental investigation on the common-rail injection system was performed on a test bench at some standard test conditions. Electric current flowing through the injector coil, oil pressure in the common rail and at the injector inlet, injection rate, needle lift, and control valve lift were gauged and recorded during several injection phases. The mean reflux-flow rate and the mean quantity of fuel injected per stroke were also measured. Temperature and pressure of the feeding oil as well as pressure in the rail were continuously controlled during the experimental test. The numerical and experimental results were compared. Afterwards, the model was used to investigate the effect of control volume feeding and discharge holes and of their inlet fillet, as well as the effect of the control volume capacity, on the injector performance
A Linear Optical Sensor for Measuring Needle Displacement in Common-rail Diesel Injectors
No full textAlinear optical displacement sensorwas designed to overcome the problems related to the sensitivity of traditional transducers to electromagnetic disturbance, when applied to the measurement of needle lift in electrically actuated Diesel fuel injectors. The sensor consisted of a laser light emitter, a receiver, and a device used for modulating the intensity of the light reaching the receiver in function of position of the moving element. Thus, two rectangular windows were mounted on the injector body, while a third window was rigidly connected to the needle control piston, and aligned with the fixed ones, to obtain a clearance area which varied linearly with needle position. An optical fibre cable was used to transfer the laser light from the source to one of the fixed window, while a similar cable was connected between the second window and the receiver. Hence, the intensity of the light reaching the receiver was proportional to the position of the injector needle. Light intensity was converted into an equivalent voltage, and this signal was fed to the data acquisition system. The injector needle lift curves were measured and compared with those obtained with a commercial eddy current sensor. The reliability of the sensor was further improved by designing a suitable gasket that prevented fuel oil from reaching the optical windows, thus avoiding the onset of fluid cavitation, which would have resulted in bubble formation and consequent random laser light scattering, hence measurement alteratio
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
A solvable model for a finite-capacity queueing system - A Reply to Iversen and Nielsen's Letter
No full textDispelling 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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