1,721,322 research outputs found
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
45th AIAA/ASME/SAE/ASEE joint propulsion conference & exhibit
No full textLarge-eddy simulations (LES) have been performed for kerosene spray combustion with methane pilot flame in a model dual mode ramjet chamber with a cavity flame holder under the condition of incoming Mach number of 2 and inlet static temperature of 520K. Three cases are compared with a constant equivalence ratio of methane pilot flame of 0.08 but different equivalence ratios of kerosene of 0.10, 0.25 and 0.6 respectively. It is found that the kerosene spray interacts strongly with the pilot flame in the near wall region and the depth of the spray penetration plays an important part in deciding the characteristics of the combustion process, its efficiency and the overall heat addition. When kerosene injection mass is small, spray droplets are close to the wall and are surrounded with the hot air generated by the pilot flame, the kerosene spray combustion can achieve higher efficiency due to nearly complete combustion in the separated boundary layer. However the resulting flame flashback in the boundary layer could induce engine inlet unstarting. When spray droplets penetrate further into the freestream but still interact intermittently with the pilot flame, the spray evaporation is enhanced by the pilot flame front. The heat consumption during this process results in rich fuel mixtures accumulating near the wall. Thus the combustion processes of both kerosene vapor and pilot gas have been suppressed, resulting the lowest heat releasing. As for the case of droplets fully penetrating into the freestream core, small amount of evaporated kerosene gradually diffuses and burns further downstream of the pilot flame, accompanied with the lowest combustion efficiency due to low evaporation rate but the relative higher additional heat releasing.Considering inlet unstarting is undesirable for ramjet engine under a relative low flight Mach number, unless the boundary layer separation can be controlled, the deep spray penetration is to be used to achieve a better overall kerosene combustion performance. However the spray combustion efficiency still needs to be improved
Large-eddy simulation of kerosene spray combustion in a model scramjet chamber
No full textLarge-eddy simulation (LES) of kerosene spray combustion in a model supersonic combustor with cavity flame holder is carried out. Kerosene is injected through the ceiling of the cavity. The subgrid-scale (SGS) turbulence stress ensor is closed via the Smagorinsky’s eddyviscosity model, chemical source terms are modelled by a finite rate chemistry (FRC) model, and a four-step reduced kerosene combustion kinetic mechanism is adopted. The chamber wallpressure predicted from the LES is validated by experimental data reported in literature. The test case has a cavity length of 77mm and a depth of 8mm. After liquid kerosene is injected through the orifice, most of the droplets are loaded with recirculation fluid momentum inside the cavity. Due to lower velocity of the carrier fluid inside the cavity, sufficient atomization and evaporation take place during the process of droplet transportation, resulting in a rich fuel mixture of kerosene vapour accumulating inside the cavity. These rich fuel mixtures are mixed with fresh air by the approachmixing layer at the front of the cavity and are thus involved in burning accompanied with the approach boundary layer separation extending towards upstream. The combustion flame in the downstream impinges onto the rear wall of the cavity and is then reflected back to the front of the cavity. During the recirculation of hot flow, heat is compensated for evaporation of droplets. The circulation processes mentioned above provide an efficient flame-holdingmechanism to stabilize the flame.Comparisons with results froma shorter length of cavity (cavity length of 45mm) show that, due to insufficient atomization and evaporation of the droplets in the short distance inside the cavity, parts of the droplets are carried out of the cavity through theboundary layer fluctuation and evaporated in the hot flame layer, thus resulting in incomplete air fuel mixing and worse combustion performance. The flow structures inside the cavity play an important role in the spray istribution, thus determining the combustion performance
LES of kerosene spray combustion in RBCC ramjet/scramjet mode
No full textLarge-eddy simulation (LES) of kerosene spray combustion in a model supersonic combustor with cavity flame holder is carried out. Kerosene is injected through the ceiling of the cavity. Chamber wall pressure predicted from the LES is validated by experimental data reported in literature. The test case has a cavity length of 77 mm and the depth of 8mm. After liquid kerosene is injected through the orifice, most of the droplets are loaded with recirculation fluid momentum inside the cavity. Due to lower velocity of the carrier fluid inside the cavity, sufficient atomization and evaporation take place during the processes of droplets transportation, resulting in rich fuel mixture of kerosene vapor accumulating inside the cavity. These rich fuel mixtures are mixed with fresh air by the approach mixing layer at the front of the cavity, thus are involved in burning accompanied with the approach boundary layer separation extending towards upstream. The combustion flame in the downstream impinges onto the rear wall of cavity, and then is reflected back to the front of the cavity. During the recirculation of hot flow, heat is compensated for droplets evaporation. The circulation processesmentioned above provide an efficient flame holding mechanism to stabilize the flame. Comparisons with results from a shorter length of cavity (cavity length of 45mm) shows that, due to insufficient atomization and evaporation of droplets in the short distance inside the cavity, parts of droplets are carried out of the cavity through the boundary layer fluctuation, and evaporated in the hot flame layer, thus results incomplete air fuel mixing and worse combustion performance. The flow structures inside the cavity play an important role in the spray distribution, thus determine the combustion performance
Pleural biomarkers in diagnostics of malignant pleural effusion: a narrative review
No full textAlthough cytology and pleural biopsy of pleural effusion (PE) are the gold standards for diagnosing malignant pleural effusion (MPE), these tools' diagnostic accuracy is plagued by some limitations such as low sensitivity, considerable inter-observer variation and invasiveness. The assessment of PE biomarkers may hence be seen as an objective and non-invasive diagnostic alternative in MPE diagnostics. In this review, we summarize the characteristics and diagnostic accuracy of available PE biomarkers, including carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), carbohydrate antigens 125 (CA125), carbohydrate antigen 19-9 (CA19-9), carbohydrate antigen 15-3 (CA15-3), a fragment of cytokeratin 19 (CYFRA 21-1), chitinase-like proteins (CLPs), vascular endothelial growth factor (VEGF) and its soluble receptor, endostatin, calprotectin, cancer ratio, homocysteine, apolipoprotein E (Apo-E), B7 family members, matrix metalloproteinase (MMPs) and tissue-specific inhibitors of metalloproteinases (TIMPs), reactive oxygen species modulator 1 (Romo1), tumor-associated macrophages (TAMs) and monocytes, epigenetic markers (e.g., cell-free microRNA and mRNA). We summarized the evidence from systematic review and meta-analysis for traditional tumor markers' diagnostic accuracy. According to the currently available evidence, we conclude that the traditional tumor markers have high specificity (around 0.90) but low sensitivity (around 0.50). The diagnostic accuracy of novel tumor markers needs to be validated by further studies. None of these tumor biomarkers would have sufficient diagnostic accuracy to confirm or exclude MPE when used alone. A multi-biomarker strategy, also encompassing the use of artificial intelligence algorithms, may be a valuable perspective for improving the diagnostic accuracy of MPE
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