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Energy outputs and emissions analysis of various biodiesels as a function of coolant temperature and esters composition
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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
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
Interface-driven human brain injury mechanisms in blast exposure:A fluid–structure interaction model
Get PDFBlast-induced traumatic brain injury (bTBI) presents a significant challenge for military personnel and civilians exposed to explosions. Beyond combat, bTBI can arise from civilian incidents like industrial accidents (chemical-plant or mining blasts), accidental demolition blasts, fireworks factory explosions, and residential gas-leak detonations. The precise mechanisms by which blast waves damage the brain are still developing. Studies suggest that bTBI is primarily an interface-driven injury, where mechanical forces concentrate at anatomical boundaries including gray–white matter junctions, cortical sulci, cerebrospinal fluid (CSF) spaces, and perivascular structures. Recent research has shown that fluid structure interaction (FSI) simulations are instrumental in capturing shock wave transmission through the skull, CSF, and brain tissue, directly informing the design of protective gear. Here, we developed a high-resolution FSI model of the human head with approximately five million elements and detailed anatomical features (sulci, gyri, CSF compartments, vascular structures) to examine these biomechanical interactions. We employed Friedlander waveform to simulate the blast wave, with adjustments for attenuation through the skull and pressure transmission into the CSF and brain, with peak overpressures ranging from 100 to 1000 kPa and durations up to 6 ms. Our findings indicate that local CSF pressures dropping below its vapor pressure (around –90 kPa) can initiate cavitation, particularly within sulcal and ventricular spaces. This cavitation is accompanied by elevated shear stresses at adjacent gray–white matter interfaces, with strain rates exceeding 250 s−1, co-localizing with diffuse axonal injury (DAI) thresholds. Higher overpressures (500 kPa) also induced intraventricular cavitation and elevated periventricular strain rates. Blast orientation significantly influenced injury distribution, lateral blasts resulted in more diffuse stress fields, while frontal blasts localized damage to anterior cortical regions.</p
Performance evaluation of air breathing PEMFC under Saudi Arabia’s ambient conditions using three-dimensional FEM model
Get PDFIn 2016, Saudi Arabia has announced a new vision for year 2030, and set an initial target of 9.5GW to be generated from renewable energy sources [1]. Air-breathing proton exchange membrane fuel cell (PEMFC) stack is seen as a promising candidate as an alternative source of energy to conventional combustion engines in stationary and automotive applications. This type of PEMFC uses ambient air as the oxidant and hydrogen as the fuel generating electricity. The performance of air-breathing PEMFC is highly affected by the operating ambient conditions, such as temperature and humidity. In this paper, the performance of an air breathing PEMFC is evaluated under Riyadh’s city ambient conditions throughout the year, to help policy-makers in considering deploying this technology in the new public transportation project in the city, which is due to complete in 2019. Thermal and water management is obtained though validated 3-dimensional model. Furthermore, the effect of anode humidification on the dynamics of the PEMFC is analysed
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
State-of-the-art manufacturing technologies of PEMFC components
Get PDFDescription and analysis of membrane electrode assembly and different manufacturing processes of Proton Electron Membrane has been made. Efforts were made to explain the types of assembly and manufacturing methods. Finding innovative ways to fabricate PEM fuel cell components, which affords mass production at lower operating cost, is one of the major threats to its commercialisation. Additive manufacturing techniques are seen as efficient and fast manufacturing methods that builds up components layer-by-layer in three dimensions, rather than conventional subtractive manufacturing techniques. This helps to reducing the overall cost, manufacturing time and wastage. The major aim of this work is to help people working with PEM fuel cells make informed decision regarding the selection of material and the choice of process. Choosing the right type of assembly and manufacturing method can go a long way to reduce the cost of production and durability
FSI modeling and simulation of blood viscosity impacts on cavitation in mechanical heart valves
Get PDFHeart valve replacements are critical for patients with valve malfunctions, and the tri-leaflet mechanical heart valve (tMHV) is one of the most durable options available. The tMHV is used to replace malfunctioning heart valves, restoring normal blood flow with exceptional durability, often lasting up to 20 years without needing replacement. This durability makes tMHVs particularly suitable for patients under 60. However, mechanical issues like cavitation can undermine the valve's functionality, posing risks to both its longevity and the overall efficacy of cardiovascular treatments. While previous studies have investigated some aspects of cavitation in these valves, the combined effects of blood viscosity and fluid-structure interaction (FSI) on cavitation dynamics remain insufficiently explored.This work models and numerically simulate the influence of blood viscosity on cavitation within tMHVs, using FSI principles. A detailed geometric model of the tMHV was developed, incorporating experimental data and non-Newtonian fluid behaviour to accurately replicate blood flow. Simulations were conducted in ANSYS Fluent R1® using a transient solver to capture the dynamic FSI, with the Carreau-Yasuda model representing blood's shear-dependent viscosity. Cavitation was observed at pressures as low as 4.5 Pa—well below the 15-20 Pa range typically reported—indicating a higher vulnerability than previously recognized. The simulations further showed significant vapour bubble formation, with the maximum vapour volume fraction reaching 0.953. High-speed leakage flows, peaking at 11 m/s during valve closure, were also noted, considerably exceeding velocities observed in earlier studies.These findings demonstrate that cavitation occurs when blood pressure drops below vapour pressure, causing vapour bubbles to form. These bubbles generate shock waves that can damage the valve surfaces and surrounding tissue. Insights from this study will aid in the design of next-generation tMHVs with optimised flow dynamics, potentially reducing cavitation risks and enhancing patient outcomes by minimising valve-associated complications.<p/
Performance evaluation of air breathing PEMFC under Saudi Arabia’s ambient conditions using three-dimensional FEM model
Get PDFIn 2016, Saudi Arabia has announced a new vision for year 2030, and set an initial target of 9.5GW to be generated from renewable energy sources [1]. Air-breathing proton exchange membrane fuel cell (PEMFC) stack is seen as a promising candidate as an alternative source of energy to conventional combustion engines in stationary and automotive applications. This type of PEMFC uses ambient air as the oxidant and hydrogen as the fuel generating electricity. The performance of air-breathing PEMFC is highly affected by the operating ambient conditions, such as temperature and humidity. In this paper, the performance of an air breathing PEMFC is evaluated under Riyadh’s city ambient conditions throughout the year, to help policy-makers in considering deploying this technology in the new public transportation project in the city, which is due to complete in 2019. Thermal and water management is obtained though validated 3-dimensional model. Furthermore, the effect of anode humidification on the dynamics of the PEMFC is analysed
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