Thematische Bibliographien / Tail surface test

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Auswahl der wissenschaftlichen Literatur zum Thema „Tail surface test“

Autor: Grafiati

Veröffentlicht am 28. Juni 2021

Zuletzt aktualisiert am 1. Februar 2022

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Zeitschriftenartikel zum Thema "Tail surface test"

Gao, Zong Jun, Jia Guo Ren, Jia Liang Li, Hong Cao, Qian Qian Wu, Zhao Xiang Zhang und Hai Hui Ma. „The Comprehensive Test for Geothermal Tail-Water Disposal“. Advanced Materials Research 403-408 (November 2011): 4522–27. http://dx.doi.org/10.4028/www.scientific.net/amr.403-408.4522.

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Geothermal reservoirs and groundwater resources in layered porous media in large sedimentary basins have enormous exploitation potential because of their extensive distribution, great quantity, and feasible temperatures and drilling depths. The discharge of geothermal wastewater (i.e. tail-water) on the surface is a serious environmental issue because of its high salinity content, so the Bureau of Geology Exploration and Mineral Resources Exploitation in Shandong Province, China called for the study of the disposal technique of the geothermal tail-water. The disposal test process is as follows: take the waste of geothermal water to make physics-chemistry preparative disposal; filtration with manganese-sand set and/or double-medium equipment; filtration with ion exchange resins; nanofiltration membrane separation; and reverse osmosis separation. After separation, the cheap, clean water can be used as a material for chemical plants. However, in the case of deeply embedded geothermal groundwater resources, connate water(buried water), or bad recharge conditions, must be dried up for a long time exploitation, causing ground depression. Therefore, it is concluded that systems utilizing reinjection, i.e. closed-circuit cycle mode injection, in sandstone reservoirs are ideal for the realization of sustainable exploitation of the geothermal groundwater resources with favorable environmental conditions on the surface.

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Nicassio, Francesco, und Gennaro Scarselli. „Simulation and Test of Discrete Mobile Surfaces for a RC-Aircraft“. Aerospace 6, Nr. 11 (05.11.2019): 122. http://dx.doi.org/10.3390/aerospace6110122.

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Morphing structures suitable for unmanned aerial vehicles (UAVs) have been investigated for several years. This paper presents a novel lightweight, morphing concept based on the exploitation of the “lever effect” of a bistable composite plate that can be integrated in an UAV horizontal tail. Flight dynamics equations are solved in Simulink environment, thus being able to simulate and compare different flight conditions with conventional and bistable command surfaces. Subsequently, bistable plates are built by using composite materials, paying particular attention to dimensions, asymmetric stacking sequence and total thickness needed to achieve bistability. NACA0011 airfoil is chosen for proving this concept. Wind tunnel tests demonstrate that the discrete surface is capable of withstanding the aerodynamic pressure. A remotely piloted vehicle is employed to test the discrete horizontal tail command during the take-off. The results show that, choosing a proper configuration of constraints, stacking sequence and aspect ratio for the bistable laminate, it is possible to tailor the snap-through mechanism. The proposed concept appears lighter and increases aerodynamic efficiency when compared to conventional UAV command surfaces.

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Fratto, Melanie A., und Andrew K. Davis. „Do black-furred animals compensate for high solar absorption with smaller hairs? A test with a polymorphic squirrel species“. Current Zoology 57, Nr. 6 (01.12.2011): 731–36. http://dx.doi.org/10.1093/czoolo/57.6.731.

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Abstract In polymorphic mammalian species that display multiple color forms, those with dark, or melanic pelage would be prone to overheating, especially if they live in warm climates, because their fur absorbs solar energy at a higher rate. However, experimental studies indicate that certain physical properties of fur of dark individuals appear to prevent, or minimize heat stress, although it is not clear what properties do so. Here, we tested the possibility that black-furred individuals simply have shorter or thinner hair fibers, which would create a lighter (in terms of weight) coat or one that allows greater air flow for evaporative cooling. We examined museum specimens of eastern fox squirrels Sciurus niger, a species native to the United States and one that displays brown, grey or all-black pelage color, and used image analysis procedures to quantify hairs from the dorsal surface and tail. From examination of 43 specimens (19 brown, 9 black and 15 grey), and 1,720 hairs, we found no significant difference in hair lengths across color morphs, but significant differences in hair fiber widths. Black squirrels had thinner body hairs than other forms (7% thinner), but thicker tail hairs (9% thicker) than the others. Given that the dorsal surface would be directly exposed to solar radiation, we interpret this to be an adaptation to prevent heat stress during the day. The thicker tail hairs may be an adaptation for nighttime thermoregulation, since squirrels sleep with their tails wrapped around their bodies. These results add to a growing literature body of the functional significance of mammalian pelage.

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Warguła, Łukasz, Bartosz Wieczorek und Mateusz Kukla. „The selection of the tail lift parameters“. AUTOBUSY – Technika, Eksploatacja, Systemy Transportowe 20, Nr. 1-2 (28.02.2019): 364–67. http://dx.doi.org/10.24136/atest.2019.067.

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People moving on wheelchairs overcome the forces of resistance such as: air resistance, resistance of the ascent, inertia force and rolling resistance force. Under certain conditions of use of the wheelchair, the only resistance that must overcome the driving force during the movement is the rolling resistance force. This situation occurs during uniformly rectilinear movement, on a flat level surface at speeds of up to 20 km/h, because at this speed the air resistance is negligible. Rolling resistance is mainly influenced by the mass of the rolling object and the rolling resistance coefficient of the running gear. The value of the rolling resistance coefficient can be influenced, among others, by the surface, type and level of pressure in the tire, and the measurement method. There are test methods that in the resistance of rolling beyond the resistance resulting from the contact of the tire with the surface take into account the resistance to connection of the wheel with the driven object. One of them is the innovative method of measuring the rolling resistance coefficient of objects equipped only with the running gear according to the patent application P.424484 and the developed device for these tests in accordance with the patent application P.424483. The article presents the results of wheelchair rolling resistance test with a classic drive system and wheel attachment. These results show differences in the aspect of rolling resistance of classic wheelchairs with wheelchairs equipped with innovative propulsion solutions, such as a lever drive system or a hybrid drive. The study was financed from the means of the National Centre for Research and Development under LIDER VII programme, re-search project no. LIDER/7/0025/L-7/15/NCBR/2016.

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Khan, Abid Ali, Muhammad Arif Ashraf, Asim Shehzad, Abroon Jamal Qazi und Imran Hayat. „Computational and experimental studies of horizontal tail flutter suppression“. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, Nr. 1 (14.08.2017): 34–43. http://dx.doi.org/10.1177/0954410017725363.

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Flutter is an extremely violent instability that may result in catastrophic failure. Thus, flutter clearance test is one of the critical phases in qualification of an aircraft’s airworthiness. During design and development process of an aircraft, flutter problems were experienced on an aerodynamic surface (horizontal tail). In order to tackle the observed problem, a number of approaches to optimize the design for flutter speed were computationally and experimentally studied and evaluated. This paper presents and discusses the outcomes of these studies. A hybrid approach based on evaluations and design change constraints has been proposed to suppress the flutter of the horizontal tail.

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Gao, Zhenxing, Debao Wang und Zhiwei Xiang. „A Method for Estimating Aircraft Vertical Acceleration and Eddy Dissipation Rate in Turbulent Flight“. Applied Sciences 10, Nr. 19 (28.09.2020): 6798. http://dx.doi.org/10.3390/app10196798.

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Atmospheric turbulence is a typical risk that threatens the flight safety of civil aviation aircraft. A method of estimating aircraft’s vertical acceleration in turbulence is proposed. Based on the combination of wing and horizontal tail, the continuous change of aerodynamic force in turbulent flight is obtained by unsteady vortex ring method. Vortex rings are assigned on the mean camber surface to further improve the computing accuracy. The incremental aerodynamic derivatives of lift and pitching moment are developed, which can describe the turbulence effects on aircraft. Furthermore, a new acceleration-based eddy dissipation rate (EDR) algorithm was developed to estimate the turbulence severity. Compared with wind tunnel test data, the aerodynamic performance of the lifting surface was computed accurately. A further test on wing–tail combination showed that the computed pitching moment change due to control-surface deflections approaches the aircraft-modeling data. The continuous change of vertical acceleration at any longitudinal locations of aircraft is obtained in turbulent flight. Compared with traditional transfer function-based EDR algorithms, the proposed algorithm shows higher accuracy and stability. Furthermore, the adverse influence of aircraft maneuvering on EDR estimation is eliminated.

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Kern, Martin, Perry Bartelt, Betty Sovilla und Othmar Buser. „Measured shear rates in large dry and wet snow avalanches“. Journal of Glaciology 55, Nr. 190 (2009): 327–38. http://dx.doi.org/10.3189/002214309788608714.

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AbstractWe present estimates of internal shear rates of real-scale avalanches that are based on velocity measurements. Optical velocity sensors installed on the instrument pylon at the Swiss Vallée de la Sionne test site are used to measure flow velocities at different flow heights of three large dry and wet snow avalanches. Possible sources of error in the correlation analysis of the time-lagged reflectivity signals measured by optical sensors are identified for real-size avalanches. These include spurious velocities due to noise and elongated peaks. An appropriate choice of the correlation length is essential for obtaining good velocity estimates. Placing restrictions on the maximum possible accelerations in the flow improves the analysis of the measured data. Coherent signals are found only in the dense flowing cores. We observe the evolution of shear rates at different depths between the front and tail of the flowing avalanche. At the front, large shear rates are found throughout the depth; at the tail, plug flows overriding highly sheared layers near the bottom of the flow are observed. The measured velocities change strongly with height above the ground and fluctuations around the measured mean velocity can be identified. We find that the dense flows are laminar, undergoing a transition from supercritical to subcritical flow behaviour from the head to the tail. Furthermore, we provide real-scale experimental evidence that the mean shear rate and the magnitude of velocity fluctuations increase with the mean discharge.

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Li, Gang, Kai Pang, Lan Chi, Chang Xiang Liu, Li Jiang und Li Qun Mo. „Experimental Study on Performance of Phase Change Thermal Storage Kang“. Applied Mechanics and Materials 525 (Februar 2014): 451–56. http://dx.doi.org/10.4028/www.scientific.net/amm.525.451.

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In this paper, the author build a new type of Kang with paraffin as its heating surface. Paraffin is a kind of phase change material ,which can stroage and release heat at a relatively constant temperature. It can make full use of the heat of the smoke in the Kang and extend the Kang heating period. We do comparison test of the the traditional Kang room and the phase change Kang room and related temperature was recorded. The tested result shows that the average temperature of the head, medium and tail of traditional Kang varies greatly,the maximum difference of the temperature is over 20°C. While the average temperatures of the head, middle and tail of the phase change thermal storage Kang are 32.59°C, 28.38°C and 26.12°C, Kang surface temperature distribution is more uniform, which improves the comfort of Kang surface. The indoor temperature with phase change thermal storage Kang shows an upward trend after the fuels burnt out until the wee hours. And the average indoor temperature is 1 °C higher than the comparision room. The phase change thermal storage Kang greatly improves the thermal comfort of its heating surface and indoor temperature.

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Tang, Yong, Liang Liang, You Xia Pang, Zong Ming Zhu und Yan Xu. „Research of Erosion, Cavitation and Their Interactive Wears of Fluid Machinery Three-Phase Flow“. Applied Mechanics and Materials 212-213 (Oktober 2012): 1261–66. http://dx.doi.org/10.4028/www.scientific.net/amm.212-213.1261.

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There are erosion and cavitation in the wear of flow passage components of fluid machinery at the same time. With simulating the working conditions of hydraulic turbine, this paper studies the flow field (pressure field and fluid concentration distribution) of vapor-liquid-solid three-phase on the surface of test rotary table when there are erosion, cavitation and interactive wear on the test rotary table under different environmental pressure with computational fluid dynamics i.e. CFD method, and erosion and cavitation interactive wear test is made on the rotary wear test-bed. The results show that during interaction, the pressure on test piece surface is higher than that in erosion and cavitation, and both high pressure area and bubble area appear near the cavitation hole which is shown as fish-tail shape; with the environmental pressure increased and the interaction, the pressures on test piece surface and bubble are increased, and wear is thereupon increased; Under the interaction, the numerically computational area with many bubbles and big pressure gradient is basically the same as test piece wearing area, so the numerical computational results are consistent with the test results well.

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Xiao, Kanyan, Jennifer Garner, Kathleen M. Buckley, Peter A. Vincent, Christine M. Chiasson, Elisabetta Dejana, Victor Faundez und Andrew P. Kowalczyk. „p120-Catenin Regulates Clathrin-dependent Endocytosis of VE-Cadherin“. Molecular Biology of the Cell 16, Nr. 11 (November 2005): 5141–51. http://dx.doi.org/10.1091/mbc.e05-05-0440.

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VE-cadherin is an adhesion molecule critical to vascular barrier function and angiogenesis. VE-cadherin expression levels are regulated by p120 catenin, which prevents lysosomal degradation of cadherins by unknown mechanisms. To test whether the VE-cadherin cytoplasmic domain mediates endocytosis, and to elucidate the nature of the endocytic machinery involved, the VE-cadherin tail was fused to the interleukin (IL)-2 receptor (IL-2R) extracellular domain. Internalization assays demonstrated that the VE-cadherin tail dramatically increased endocytosis of the IL-2R in a clathrin-dependent manner. Interestingly, p120 inhibited VE-cadherin endocytosis via a mechanism that required direct interactions between p120 and the VE-cadherin cytoplasmic tail. However, p120 did not inhibit transferrin internalization, demonstrating that p120 selectively regulates cadherin internalization rather than globally inhibiting clathrin-dependent endocytosis. Finally, cell surface labeling experiments in cells expressing green fluorescent protein-tagged p120 indicated that the VE-cadherin–p120 complex dissociates upon internalization. These results support a model in which the VE-cadherin tail mediates interactions with clathrin-dependent endocytic machinery, and this endocytic processing is inhibited by p120 binding to the cadherin tail. These findings suggest a novel mechanism by which a cytoplasmic binding partner for a transmembrane receptor can serve as a selective plasma membrane retention signal, thereby modulating the availability of the protein for endo-lysosomal processing.

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Dissertationen zum Thema "Tail surface test"

Serediuk, Vadym. „Návrh průkazných statických pevnostních zkoušek letounu v kategorii UL“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443247.

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The diploma thesis involves the design of certification static strength tests for the newly developed aircraft of the TL-Ultralight company. At the beginning of the work, the theory of aircraft testing is generally discussed with emphasis on static strength tests. Furthermore, an analysis of the requirements of the Czech regulation UL 2 and the German LTF-UL, which represent the certification basis for this aircraft, is performed. The requirements of regulations on the construction of the aircraft (or its individual parts) and the requirements for strength tests are discussed in detail. Based on the regulation and the provided calculation protocols, individual test cases and test plans of the wing, tail surfaces, engine bed, and chassis are calculated and prepared. In the end, the calculation of the rocker system and the basic design of jigs are performed.

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Winkler, Anderson M. „Widening the applicability of permutation inference“. Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:ce166876-0aa3-449e-8496-f28bf189960c.

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This thesis is divided into three main parts. In the first, we discuss that, although permutation tests can provide exact control of false positives under the reasonable assumption of exchangeability, there are common examples in which global exchangeability does not hold, such as in experiments with repeated measurements or tests in which subjects are related to each other. To allow permutation inference in such cases, we propose an extension of the well known concept of exchangeability blocks, allowing these to be nested in a hierarchical, multi-level definition. This definition allows permutations that retain the original joint distribution unaltered, thus preserving exchangeability. The null hypothesis is tested using only a subset of all otherwise possible permutations. We do not need to explicitly model the degree of dependence between observations; rather the use of such permutation scheme leaves any dependence intact. The strategy is compatible with heteroscedasticity and can be used with permutations, sign flippings, or both combined. In the second part, we exploit properties of test statistics to obtain accelerations irrespective of generic software or hardware improvements. We compare six different approaches using synthetic and real data, assessing the methods in terms of their error rates, power, agreement with a reference result, and the risk of taking a different decision regarding the rejection of the null hypotheses (known as the resampling risk). In the third part, we investigate and compare the different methods for assessment of cortical volume and area from magnetic resonance images using surface-based methods. Using data from young adults born with very low birth weight and coetaneous controls, we show that instead of volume, the permutation-based non-parametric combination (NPC) of thickness and area is a more sensitive option for studying joint effects on these two quantities, giving equal weight to variation in both, and allowing a better characterisation of biological processes that can affect brain morphology.

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Bücher zum Thema "Tail surface test"

Ratvasky, Thomas P. NASA/FAA Tailplane Icing Program overview. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 2000.

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Foss, Van Zante Judith, Sim Alex und NASA Glenn Research Center, Hrsg. NASA/FAA Tailplane Icing Program: Flight test report. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 2000.

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Foss, Van Zante Judith, Riley James T, Lewis Research Center und United States. National Aeronautics and Space Administration., Hrsg. NASA/FAA Tailplane Icing Program overview. [Cleveland, Ohio]: National Aeronautics and Space Administration, Lewis Research Center, 1999.

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Foss, Van Zante Judith, und Lewis Research Center, Hrsg. In-flight aerodynamic measurements of an iced horizontal tailplane. [Cleveland, Ohio]: National Aeronautics and Space Administration, Lewis Research Center, 1999.

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In-flight aerodynamic measurements of an iced horizontal tailplane. [Cleveland, Ohio]: National Aeronautics and Space Administration, Lewis Research Center, 1999.

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Investigation of dynamic flight maneuvers with an iced tailplane. [Cleveland, Ohio]: National Aeronautics and Space Administration, Lewis Research Center, 1999.

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Buchteile zum Thema "Tail surface test"

Dondero, Franco, Loredana Gandini, Francesco Lombardo und Andrea Lenzi. „Immunological infertility“. In Oxford Textbook of Endocrinology and Diabetes, 1429–32. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780199235292.003.9100.

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Immunological infertility is the presence, in one or both partners, of an antisperm immune reaction capable of interfering with fertility variables. In about 8–10% of these couples the immunological phenomenon is on the male side, causing ‘male immunological infertility’ (1). Since the first demonstration that a significant number of infertile men show an autoimmunity to sperm, experiments have suggested that antisperm antibodies (ASA) can interfere with the fertilizing ability of spermatozoa (2). ASA can act negatively on the motility of spermatozoa in semen, on their ability to pass through female genital secretions, or on the penetration of the oocyte. In particular, owing to in vitro fertilization techniques, it has been possible to demonstrate the effects of antibody-bound sperm directly, at the level of in vitro gamete interaction (3). ASA can reduce the motility and concentration of spermatozoa, and can induce sperm agglutination. However, normozoospermia can be accompanied by a high percentage of antibodies bound to the sperm surface, or a high ASA titre in serum or seminal plasma. In addition, ASA can affect sperm penetration of cervical mucus. When ASA are present in cervical mucus or bound to the sperm surface, impaired sperm penetration of cervical mucus, and abnormal swimming behaviour within cervical mucus—ranging from complete immobilization of sperm, to vibratory motion with limited progression (‘shaking reaction’), to restricted tail beat frequency and loss of rotatory motion—may be observed during the post-coital test (PCT). The shaking reaction in these cases is presumably due to cross-linking of motile, antibody-coated spermatozoa to the cervical mucus gel via the Fc part of the antibody (4). ASA may also inhibit fertilization by binding specifically to membrane antigens involved in sperm–oocyte interaction. They can additionally impair the fertilization process at the levels of the acrosome reaction, of zona pellucida recognition and penetration, and of sperm–vitellus interaction (5).

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„axillary, on 5-10 mm long stems. Sepals 5-7 mm long, elliptical, narrow-scarious along margin. Petals 7-10 mm long, oblong-obovate or oval, narrowing into long cuneate claw, orange-colored at base, white in upper portion. Capsules 16-24 mm long, 6-10 (12) mm broad, oblong-oval or oval, pentagonal; wings 2-3 mm broad. In solonchaks and solonetzic steppes, sometimes on rocky steppe slopes. West. Sib.: AL—Go (Chuya river valley: facing Chegan river estuary—class, hab. and others in Chuya steppe).— Mid. Asia, West. China, Mongolia. Map 21. 5. Z. pterocarpum subsp. tuvinicum Peschkova, subsp. nova. A subspecie typica foliis plerumque trijugis (rarius bijugis), foliolis oblongo-linearibus, petiolis apice processu aculeoli-formi molli subindistincto albido recto vel subincurvato distinguitur. Typus. Tuva, dist. Tes-Chemensis, declive australe jugi Tannu-Ola Orientalis, 1200 m.s.m., vallis FI. Irbitei, silva salicoso-populosa variiherbosa, 3 VIII 1972, V. Chanminczun, L. Kupalova, L. Eremenko (NS, isotypus LE). Unlike type subspecies, leaves usually with 3 (rarely 2) pairs of oblong-lanceolate leaflets. Leaf petioles with faint whitish, erect or slightly curved soft spiniform shoot at tip. In arid solonetzic meadows, river valleys, nannophyte solonchak semideserts. Cen. Sib.: TU (Irbitei river valley in Tes-Khemsk region—class, hab.—Ak-Chyra settlement, bank of Amdaigyn-Khol’ lake).—Endemic. 2. Tribulus L. 1. T. terrestris L. 1753, Sp. Pl.: 387. Annual with slender weak root and (3)10-60 cm tall stems diffuse along ground and branched right from base; together with leaf petioles and pedicels, covered with long distant and short semiappressed hairs bent at tip. Leaves (1) 2-6 cm long, (0.5) 1-3 cm broad, more often opposite, paripinnate, with small lanceolate-deltoid stipules; leaflets 4-7 pairs, 3-13 mm long, 34 1-5 mm broad, oblong or oblong-elliptical, asymmetric, obtuse, on very short petiolules, more or less compactly (specially young) covered beneath with long slender appressed hairs, glabrescent with age, subglabrous on upper surface. Flowers single, axillary, on short (4-10 mm) stems. Sepals 3-5 mm long, lanceolate, hairy outside. Petals narrow-obovate, about 10 mm long“,. In Flora of Siberia, Vol. 10, 46–55. CRC Press, 2006. http://dx.doi.org/10.1201/9781482294248-3.

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Konferenzberichte zum Thema "Tail surface test"

Balu, Alexander, Miguel Castro, Geet Padhi, Todd Bandhauer, Bret Windom, Shane Garland, Daniel Olsen und Robert Braun. „Optimization and Simulation of a CFR Engine Fueled by Dilute Anode Tail-Gas“. In ASME 2020 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/icef2020-2971.

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Abstract Recent innovations in Metal Supported Solid Oxide Fuel Cells (MS-SOFC) have increased the longevity and reliability of fuel cells. These innovations drive the desire to create power generating systems that combine different ways of extracting power from a fuel to increase overall thermal efficiency. This investigation assesses the feasibility of operating an internal combustion engine with the anode tail-gas, which is a blend of H2, CO, CO2, H2O, and CH4, exhausted by a MS-SOFC. This engine would be used to support fuel cell balance of plant equipment and produce excess electrical power. Four variations of the expected anode tail-gas blends were determined by varying the dewpoint temperature of the fuel. Gas blends are tested by combining separate flows of each constituent, and combustion is tested using a Cooperative Fuel Research (CFR) engine. Compression ratio, spark timing, inlet manifold temperature, and boost pressure were used to obtain optimal operating conditions. Stable engine operation was obtained on all test blends. A combination of computational fluid dynamics (CFD) and analysis of chemical species and reaction mechanisms is used to develop an engine and combustion model. This model allows for further investigation into anode tail-gas combustion characteristics. Response Surface Method Optimization was used to experimentally optimize operating parameters and determine the maximum achievable efficiency utilizing the CFR engine. All test blends with H2O produced power in the engine although the blend with the most water content caused operational problems with the CFR engine test stand, including large amounts of water entering the oil system. Three chemical kinetic mechanisms were investigated that had the correct species for simulating the fuel with a low number of reactions to facilitate low computational time: San Diego (SD), GRI and Gallway 2017 (NUIG) mechanism. Out of these four mechanisms, the NUIG mechanism results fit the CFR engine experimental data best. Response Surface Method Optimization was performed on the most viable test blends, the steam injections blends at 40°C and 90°C fuel dewpoint temperature. During optimization the 40°C dewpoint temperature blend brake efficiency increased from 20% to 21.6%, and the 90°C dewpoint temperature blend brake efficiency increased from 17% to 22.3%.

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Ames, Eric C., und Raja V. Pulikollu. „Virtual Life and Performance Modeling of Aerospace Spiral Bevel Gears“. In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12351.

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Spiral bevel gears are widely used in the tail rotor drive trains of most rotorcraft. The loads associated with the tail rotor drive train are generally much more variable than those in the main rotor drive train primarily resulting from maneuvers. Over the life of any particular military rotorcraft it is not uncommon for the aircraft’s operating gross weight to steadily increase, causing the aircraft to fly at higher mean power levels and thus increasing the operating load spectrum associated with the tail rotor drive train. Special missions and equipment such as pulling a mine sweeping sled or very high altitude high gross weight assaults can put severe load demands on the tail drive train. This paper details an effort conducted to evaluate the effects of short to moderate duration overloads on the spiral bevel gears of the UH-60 helicopter tail rotor drive train. The focus of the effort was on the Tail Take-off gear mesh (TTO). An initial analytical assessment of the effect of loads above the endurance limit was conducted using an American Gear Manufacturers Association (AGMA) based approach. To confirm the validity of this approach, overload testing of the TTO gear mesh was conducted by the U.S. Army’s Aviation Applied Technology Directorate at the Navy’s test facility in Paxtuent River MD. Following the testing, the gear tooth bending and surface fatigue lives were analyzed using a microstructure based probabilistic tool developed by Sentient Corporation. The tool, known as Digital Clone was able to run hundreds of virtual tests that closely simulated the actual testing thus providing a low cost method for increasing the confidence associated with the effects of short to moderate high transient loads.

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G. Faal, Siamak, Fuchen Chen, Weijia Tao, Shadi T. Kalat, Payam Razavi, Vahideh Eshaghian und Cagdas D. Onal. „Design, Fabrication, Experimental Analysis, and Test Flight of an Origami-Based Fixed-Wing Aerial Vehicle: µPlane“. In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-60477.

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This article covers details the design, fabrication, experimental analysis, and first flight tests of μPlane, an origami-inspired aerial vehicle. μPlane is a monoplane with a straight wing planform that has a wingspan of 580 millimeters and can reach a maximum linear velocity of 6.12 meters-per-second. The body of the μPlane is fabricated by folding a single, unified crease pattern which includes all the sections required to construct the wing, tail, fuselage, and connection ports for external components, such as actuators and batteries. The wing of the plane utilizes a cambered profile to generate the required lift force. An optimization problem is formulated to find a solution to the set of constraints that provides the desired camber form. To validate the proposed design, a 3D scan of the top surface of the wing is accrued using a high-resolution fringe projection system. Finally, the flight performance and stability of μPlane are tested in both indoor and outdoor environments.

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Turan, Cabir, Ender Dur, Mevlu¨t Fatih Peker, O¨mer Necati Cora und Muammer Koc¸. „Corrosion, Contact Resistance, and Surface Characteristics of Stamped and Hydroformed Metallic Bipolar Plates for PEMFC“. In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33347.

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In a quest for achieving sustainable mobility, improved fuel efficiency, enhanced driving performance and drastically reduced the tail-pile emissions necessitate the replacement of conventional energy conversion systems with environmentally-friendly technologies as well as lightweighting in transportation vehicles. Fuel cell technology is believed to be a promising avenue to achieve such a long desired sustainable transportation goal. However, for its widespread commercial success, there are some issues that need to be addressed. This study aims to investigate two of these underlying issues: corrosion and contact resistance in bipolar plates, which arise during the use fuel cell stacks, and are direct effects of production, material, surface, and coating conditions. Repeatability and robustness of manufacturing method (stamping, and hydroforming), corrosion and contact resistance of stainless steel bipolar plates (BPP), and tribological issues of forming dies in which bipolar plates are formed were investigated in this study. First, the effects of manufacturing conditions on formed bipolar plate quality and process repeatability were investigated. Second, corrosion and contact resistance tests for manufactured bipolar plates as well as blank stainless steel sheets were performed. Based on the corrosion test results, a faster stamping speed is found to be preferable for higher corrosion resistance and shorter production time. On the contrary, higher pressure rates in hydroforming are found to lower the corrosion resistance. Thus, a compromise between corrosion performance and production rate is needed in hydroforming for mass production purposes. According to the preliminary contact resistance tests, hydroformed bipolar plates showed better interfacial electrical conductivity than stamped plates. Also, the test results confirmed that surface coating is necessary to improve corrosion and contact properties to meet the DOE goals. Finally, relatively larger surface topography changes were observed on the manufactured bipolar plates compared to the forming die surfaces after several hundreds of BPP production.

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Birknes, Jørn, Øistein Hagen, Thomas B. Johannessen, Øystein Lande und Arne Nestegård. „Second-Order Kinematics Underneath Irregular Waves“. In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11629.

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The present paper is concerned with the prediction of horizontal velocities underneath measured irregular wave surface elevations. The simple case of unidirectional waves in deep water is considered. The main challenge in calculating accurately the kinematics in the crest region is related to the treatment of the contribution from wave components with frequencies much higher than the frequencies near the spectral peak. When using linear or weakly nonlinear perturbation methods, the wave components are superimposed at the still water level and it is necessary to truncate the tail of the spectrum in order to calculate accurately the velocity in the crest region. In the present paper, results from three methods of calculating the crest kinematics are compared with the model test results of Skjelbreia et al. [1]: • The second-order model of Stansberg et al. [5] which truncates consistently the high frequency part of the spectrum. • The second-order model of Johannessen [13] which calculates the velocity directly at the instantaneous free surface. • The Wheeler [3] stretching method which stretches the linear velocity profile from the still water level to the instantaneous free surface. In addition to comparing the horizontal velocity profiles underneath the crest, time traces of horizontal velocity is compared at the free surface in the vicinity of a large crest. The latter comparison highlights the differences between the models and the challenge of accurate predictions close to top of crest. All three models show a reasonable agreement with model test results although it is clear that the first two methods are superior to the Wheeler method.

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Loghin, Adrian, Al Cerrone, Anjali Singhal und Ying Zhou. „Connecting Computed-Tomography-Assisted Discontinuity Detection in Ni-Base Superalloys to Engineering Simulation“. In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-65087.

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The impact of non-metallic inclusions on fatigue life of various materials (steel alloys, Ni-base) has been studied extensively for more than fifty years. Specimen test procedures at various conditions (temperature, air or vacuum, LCF, HCF, VHCF) have been used to quantify the impact of inherent manufacturing induced discontinuities (ceramic inclusions, pores, carbides) on the fatigue capability of the material. Frequently, the fatigue data shows large scatter, leading to a large set of test specimens that has to be considered to quantify the lower tail of the fatigue life distribution. To understand the specimen recorded fatigue lives, assessment of the discontinuity population is usually conducted post-mortem by fractography wherein the origin of crack nucleation, size of the eventual inclusion on fracture surface, and distance from the free surface are identified. 3D characterization techniques can be leveraged to extract previously unobtainable information out of the testing specimens non-destructively. In this study, samples of different Powder Metallurgy (PM) Ni-base superalloys with different inclusion content and size were scanned to identify the Computed Tomography (CT) test setup that would provide adequate contrast to discriminate between matrix and eventual discontinuities (inclusions, pores). To further validate the capability to identify discontinuities within the matrix (Ni base alloy) using the CT technique, a set of LCF specimens were scanned prior to the test procedure. Post-failure fractography analysis showed that one of the CT indications is correlated with the failure-inducing inclusion. Volume reconstruction and finite element meshing conclude this study to: a) further provide a size distribution of inclusions in the scanned volume as well as location of these inclusions relative to the surface of the specimen and b) connect direct measurement with engineering simulation.

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Fu, Thomas C., Eric Terrill, Anne M. Fullerton und Genevieve Lada Taylor. „A Comparison of the Model and Full Scale Transom Wave of the R/V Athena“. In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20595.

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Over the past few years the U.S. Office of Naval Research has sponsored a series of measurements of the transom wave of the R/V Athena and of a 1/8.25-scale model (NSWCCD Model 5365) of the ship. The objectives of the testing were to characterize the free surface wave behind the ship’s transom at both model and full scale for use in identifying hydrodynamic features and for developing and validating numerical simulation tools. The focus of this paper is the comparison of these full scale and model scale measurements, specifically a comparison of the time-averaged free-surface stern wave profiles and the dominant hydrodynamic features, the rooster tail for example. Both the field measurements and the model scale tow tank measurements were made in as calm as possible ambient conditions. Full scale data was collected in the relatively protected waters of St. Andrews Bay, Florida. The winds, which typically build as the day progresses, were minimal, and it was a new moon during the test period, so tidal excursions were also minimized. While measurements were obtained for ship speeds ranging from 3.1 to 6.2 m/s (6 to 12 knots), equivalent to Froude number range based on length (47 m) of 0.14 to 0.29, respectively, the focus of the comparison is for the 0.24 Froude number (10.5 knots full scale) case. Measurements of the full scale stern wave were made by a scanning laser altimeter, while measurements at model scale were made using a traversing set of conductivity finger probes.

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Amromin, Eduard, und Svetlana Kovinskaya. „Selection of Gas-Based Drag Reduction Technology“. In ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98354.

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Drag reduction in water has been a goal of numerous efforts based on different technologies. The gas-based drag reduction technologies include supercavitation, partial cavitation and microbubble ejection. The objective of this study is to clarify the vehicle speed and size ranges for the technology effective application. The provided analysis is based on both our results and publications by other authors. Cavitation can reduce drag because a surface under the cavity is practically free of friction. Usually, there is also a significant drag penalty to create a cavity. For supercavitation, this drag becomes smaller than friction reduction only for extremely low cavitation numbers (less than 0.06). Ventilation would be necessary to maintain such cavitation numbers at speed around 100 knots, but there is no confident basis for any forecast: Model test data on air supply to supercavities are affected by flow blockage and a reasonable scaling law for air flux was not found yet. For partial cavitation, there are the possibilities to have no drag penalty and to achieve a total drag reduction in moderate ranges of cavitation number. The penalty-free partially cavitating flow can exist with suppression of cavity pulsation by a pressure gradient downstream of cavity tail. A 25%–30% drag reduction by partial cavitation was measured in model tests with our specially designed hydrofoil (in a water tunnel at the University of Minnesota) and in sea with a 100-ton boat. The friction reduction is proportional to areas covered by cavities. The attainable cavity lengths and covered areas depend on the vehicle speed. Requesting moderate air supply rates at design conditions, partial cavitation looks as the most promising and widely applicable drag reduction technology. Oppositely to supercavitation, microbubble drag reduction decreases with flow speed (the best results were obtained at 4.7m/s) and its effect critically depends on the surface orientation. An opportunity to apply this technology may exist for slow flat-bottom ships.

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Prince, Joseph F., Daniel Maynes und Julie Crockett. „Pressure Drop Measurements in Turbulent Channel Flow Over Superhydrophobic Surfaces With Riblets“. In ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icnmm2014-21690.

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In this paper we consider the combined drag reducing mechanisms of superhydrophobicity with riblets. Pressure drop measurements were acquired for turbulent flow in a channel with superhydrophobic walls, riblet walls, and walls with both drag reducing mechanisms. The superhydrophobic structuring was composed of alternating microribs (15 microns tall and 8 microns wide) and cavities (32 microns wide), aligned parallel to the flow. Superhydrophobic surfaces function to reduce drag by minimizing the effective liquid-solid contact area as water will not penetrate the cavities between microribs due to surface tension. The riblets were nominally 80 microns tall, 18 microns wide, spaced with a period of 160 microns and were also aligned parallel to the flow. Riblets function by damping out spanwise turbulent motions. Since turbulence is a three-dimensional phenomenon, this destruction of turbulent motions acts to reduce the average friction at the surface. Fabrication of the drag reducing surfaces was completed with photolithographic techniques on silicon wafers. The wafers were inserted into a channel consisting of a control section with smooth wafers and a test section with patterned wafers. In all cases, the test section walls were structured on top and bottom while the side walls were left smooth. The channel had a hydraulic diameter of 7.3 mm and an aspect ratio of 10:1. Tests were obtained over a Reynolds number range of 5 × 103 to 1.5 × 104. The superhydrophobic surfaces with riblets showed a maximum drag reduction of 7.0% which was a higher reduction than either the surfaces patterned with riblets or the superhydrophobic surfaces.

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Ganapathy Subramani, Balasubramanian, und Ponnambalam Selvaganapathy. „Surface Micromachined PDMS Microchannels“. In ASME 2007 5th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2007. http://dx.doi.org/10.1115/icnmm2007-30169.

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A new surface micromachining technique for Poly dimethylsiloxane (PDMS) microchannels has been developed to address the leakage problem affecting traditional PDMS microchannel process with embedded tall structures or sudden topographical transitions. Bulk micromachined PDMS cannot be conformally bonded with the surfaces having tall topological features such as thick film electrodes, porous reactor beds and other structural features. Surface micromachining technique with PDMS as structural material and photoresist as a sacrificial material allows the creation of PDMS microchannels on substrates with significant topography. Adhesion of the structural layer with the substrate was characterized for different prepolymer ratios using standard tensile test and 1:3 (Curing agent: base) combination was found to be the best with maximum adhesion strength of 7.5 MPa. The effectiveness of this technique is demonstrated by the fabrication of microchannels with embedded 6μm thick Silver electrodes. The microchannels were leak proof and conformal contact between the PDMS and electrode was confirmed through SEM. The release time for microchannels was reduced to 1 min irrespective of the length of the microchannel. The extension of this technique for fabrication of multi layered microchannel structure was demonstrated through a microfluidic valve. The valve closure occurred at 6.37 kPa.

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