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Analysis of the Inner Fluid-Dynamics of Scroll Compressors and Comparison between CFD Numerical and Modelling Approaches
Full text linkScroll compressors are widely adopted machines in both refrigeration systems and heat
pumps. However, their efficiency is basically poor and constitutes the main bottleneck for improving
the overall system performance. In fact, due to the complex machine fluid dynamics, scroll design
is mainly based on theoretical and/or semi-empirical approaches. Designs strategies that do not
guarantee an in-depth analysis of the machine behavior can be supplemented with a Computation
Fluid Dynamics (CFD) approach. To this purpose, in the present work, the scroll compressor inner
fluid dynamics is numerically analyzed in detail using two CFD software and two different modelling
strategies for the axial gap. The analysis of the fluid evolution within the scroll wraps reveals unsteady
phenomena developing during the suction and discharge phases, amplified by the axial clearance
with negative impact on the main fluid flow (e.g., −13% of average mass flow rate for an axial gap
of 30 μ) and on the scroll performance (e.g., +26% of average absorbed power for an axial gap of
30 μ). In terms of accuracy, the k-" offers good performance on the estimation of average quantities
but proves to be inadequate for capturing the complexity of the unsteady phenomena caused by the
axial gap (e.g., −19% of the absorbed power in case of perfect tip seal). The need for considering
specific geometric details in design procedures is highlighted, and guidelines on the choice of the
most suitable numerical model are provided depending on the analysis need
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
Evaluation with contrast enhanced US of perfusion changes in untreatable hepatocellular carcinoma after thalidomide administration: preliminary results
No full textHCV-associated autoimmune haemolityc anaemia due to warm-reacting antibodies: evidence of B-cell monoconality
No full textRotavirus infection in newborn: a rare case of necrotizing enterocolitis
Full text linkRotavirus infections in neonates are often asymptomatic, but they can become complicated, up to Necrotizing Enterocolitis. Aim of the study is to resume the history of a rare case of NEC due to Rotavirus infection comparing clinical features, lab tests and development of Rotavirus-NEC to bacterial-NEC in order to identify the correct management and the best therapeutical strategy for this group of patients. Our case report described the complicated story of a preterm female affected by RotavirusNEC who underwent surgery three times, but at least with good outcome. Different risks factors predispose to NEC due to Rotavirus such as prematurity, seasonality and formula feeding. Associated symptoms are abdominal distention, tenderness, bloody stools and fever. Development of NEC in newborns affected by Rotavirus is pathognomonic: only a very small percentage of newborns affected by Rotavirus infections develop NEC, but all of them need surgery which is resolutive most of time. The average hospital stay of surgical newborns affected by Rotavirus infection was longer than that of newborns surgically treated for bacterial gastrointestinal infections. Prevention of Rotavirus infections may be important to decrease the incidence of NEC, the morbidity and the mortality rate in neonatal period
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
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