1,720,955 research outputs found
High altitude operations with piston engines powerplant design optimization part IV: Radiators optimum design
No full textIn high altitude operations, the cooling system takes part to the vehicle design optimization process. An integrated design of the cooling ducts is strictly necessary. At high altitudes, the cooling air is taken from high-pressure areas into an alternate, extremely optimized, path. A diffuser reduces the airspeed and increases pressure of the cooling air. Then a group of high performance finned radiators rejects the heat from coolant, air charge and oil. The high altitude, after diffuser radiator performance is discussed in this paper. At first high performance Formula 1 radiators are introduced and discussed. Experimental data are also exposed and summarized. The pressure drop and heat rejection are expressed in function or Re and Pr numbers of cooling air. Then the radiator performance at high altitude is extrapolated from the ground test data. Finally a few suggestions on radiator and cooling ducts arrangement are introduced
TBO evaluation of naval and aircraft diesel engines
No full textThis paper demonstrates that the experience from Formula 1 and watercraft racing can be applied directly to assess and improve the aircraft/maritime conversion of automotive commercial engines. A direct comparison of the main parameters that characterizes modern CRDID (Common Rail Direct Injection Diesel) and Formula 1 racing engine demonstrates that the similarities are hidden inside the design criteria. In fact, CRDIDs should output high torque at low rpm (1000-3000rpm) while racing engine should have top torque at 9000-11000 rpm. This fact introduces much shorter strokes in racing engines that reduce inertia loads. Since pressures are higher for CRDIDs the combustion loads are similar. The techniques used to improve the TBO of Formula 1 spark ignition engine and racing watercraft diesel can then be directly applied to naval and aircraft engines where the low-cost requirements are not so stringent as in mass-produced automotive CRDIDs (millions of items). The same technology that prolongs the Formula 1 TBO from a single race to the whole season can then be successfully used in aircraft/naval CRDIDs. A quantitative assessment of the TBO increase is included in this paper for the various systems that compose a CRDID
High altitude operations with piston engines powerplant design optimization
No full textDiesel and spark-ignition piston engines are an ideal choice for long endurance, high altitude operations (10, 000m/33, 000ft) and extremely high altitude operations (20,000m-65,000ft). These systems are more complex than traditional applications that are normally limited to 5, 000-7, 000m (16, 000-23, 000ft). In fact, the air propulsion system (propeller or fan), the air intake, the fuel system, the turbo charging, the exhaust and the cooling system take part to the design optimization process. An integrated design is strictly necessary. Since prop-fan is currently under development, the design should start from the choice between propeller and fan. This choice will influence optimum cruise speed, critical altitude and aircraft design as a whole. The air induction system is extremely important to improve efficiency, endurance and critical altitude. At low altitude, a filtered induction system is used for takeoff. At high altitudes, the intake air is taken from high-pressure areas into an alternate, extremely optimized, path. This induction system recovers as much pressure as possible, air kinetic energy at cruise speed. In propeller systems, the intake is usually positioned in the lower part of the aircraft. On fan systems, a little amount of "high pressure" air is taken from the high-pressure area of the fan. The exhaust system is also critical with the choice between pressure recovery and thrust. Exhaust-pressure-recovery reduces backpressure and temperature at exhaust. However, the improvement in critical altitude is marginal. In more common, thrust driven exhaust systems, the exhaust energy is converted into speed and thrust. At the relatively high speed of high altitude cruise, also the cooling system adds a small amount of thrust through the Meredith's effect. The piston engine power plant design is then extremely critical. Many different components should find the correct position for maximum performance. The power-plants of WWII water-cooled fighters and bombers are good examples, even if their design cruise altitude is below 10, 000m (33, 000ft). Modern turbofan and turbojet air intakes are also of help. However, the requirements of low weight, high reliability and long endurance HALE (High Altitude Long Endurance) UAVs (Unmanned Aerial Vehicle) requires further work on this specific subject
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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