656 research outputs found

    Advanced flight control system study

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    A fly by wire flight control system architecture designed for high reliability includes spare sensor and computer elements to permit safe dispatch with failed elements, thereby reducing unscheduled maintenance. A methodology capable of demonstrating that the architecture does achieve the predicted performance characteristics consists of a hierarchy of activities ranging from analytical calculations of system reliability and formal methods of software verification to iron bird testing followed by flight evaluation. Interfacing this architecture to the Lockheed S-3A aircraft for flight test is discussed. This testbed vehicle can be expanded to support flight experiments in advanced aerodynamics, electromechanical actuators, secondary power systems, flight management, new displays, and air traffic control concepts

    Newton in Grönland

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    Newtons experimentum crucis hat ein komplementäres Gegenstück, d.h. ein Experiment, in dem die Rollen von Licht und Schatten genau ausgetauscht sind. Statt wie Newton in der Dunkelkammer zu experimentieren, müssen wir das Komplement des experimentum crucis in einer Streulichtkammer aufbauen (deren Wände sog. Lambertstrahler sind). Wenn es dieses umgestülpte Experiment wirklich gibt, dann liefert es für jeden newtonischen Beweis einen umgestülpten Gegenbeweis, dessen Konklusion die Heterogenität der Schatten wäre (also die Behauptung, dass nicht weißes Licht, sondern schwarze Schatten eine heterogene Mischung verschiedenfarbiger Strahlen mit unterschiedlichen Brechungseigenschaften seien). Dass Newtons experimentum crucis in diesem Sinne umgestülpt werden kann, wird von Newtons eigener Theorie impliziert. Mehr noch, inzwischen ist der empirische Nachweis der Umstülpung gelungen.Newton's experimentum crucis has a complementary counterpart, i.e., an experiment in which the roles of light and shadow are switched. Instead of experimenting in the dark room, à la Newton, we propose to perform the complement of the experimentum crucis in a bright room (whose walls consist of Lambertian radiators). If Newton's experiment can be turned upside-down, then for each Newtonian conclusion (derived from the original experiment) there is a counterconclusion (derived from the new experiment). Thus, we arrive at the heterogeneity of darkness, which is an unorthodox hypothesis: Darkness and shadows (rather than white light) consist of rays that differ with respect to colour and refrangibility. Newton's own theory implies that in his experimentum crucis the roles of light and darkness can be interchanged; moreover, their very interchangeability can be demonstrated empirically.Peer Reviewe

    Hourly rainfall distribution in east Malaysia during the southwest monsoon season

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    The hourly rainfall pattern during the southwest (SW) monsoon season is addressed. For this purpose, hourly rainfall data of nine selectedstations are analyzed. The study period was thirtyone years. The results of this investigation show that four main mechanisms are responsible for the daily rainfall distribution in East Malaysia. . These mechanisms are: (a) convergence of land breezes, (b) increase of the atmospheric lapse rate during the night, (c) convection and (d) sea breeze. For example, these four mechanisms may be important in a particular station in a given month and not in the following one or the precedent one. Or it may just be that one mechanism is important for a different station in a given month.Se presenta la distribución horaria de precipitación en nueve estaciones localizadas en el Este de Malasia durante el Monsoon del Sudeste. El período de estudios consta de 31 años. Los resultados de la investigación muestran cuatro factores que afectan la precipitación en esa zona, pero estos no afectan en la misma estación del año ni simultáneamente en las mismas estaciones. Estos factores son: a) convergencia ocasionada por la brisa de tierra, b) incremento de del gradiente vertical de temperatura.Asociación Argentina de Geofísicos y Geodesta

    Sinteza i anthelmintičko djelovanje novih 2-supstituiranih-4,5-difenil imidazola

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    A series of 2-substituted-4,5-diphenyl imidazoles 1a-j were synthesized by refluxing benzil with different substituted aldehydes in the presence of ammonium acetate and glacial acetic acid. Structures of the synthesized compounds were confirmed on the basis of IR, 1H NMR and mass spectral data. Compounds 1a-j were screened for anthelmintic activity. Test results revealed that compounds showed paralysis time of 0.24 to 1.54 s and death time of 0.39 to 4.40 s while the standard drugs albendazole and piperazine citrate showed paralysis time of 0.54 and 0.58 s and death time of 2.16 and 2.47 s, respectively, at the same concentration of 1 % (m/V). Five compounds, 2-[2-hydroxyphenyl]-4,5-diphenyl imidazole (1b), 2-[3-methoxyphenyl]-4,5-diphenyl imidazole (1c), 2-[2-phenylethenyl]-4,5-diphenyl imidazole (1e), 2-[4-fluorophenyl]-4,5-diphenyl imidazole (1g) and 2-[3-nitrophenyl]-4,5-diphenyl imidazole (1h) showed significant anthelmintic activity compared to the standard drugs.Refluksiranjem benzila s različitim supstituiranim aldehidima u prisutnosti amonijeva acetata i ledene octene kiseline sintetizirana je serija 2-supstituiranih-4,5-difenil imidazola (1a-j). Strukture sintetiziranih spojeva potvrđene su IR, 1H NMR i masenom spektroskopijom. U testovima na anthelmintičko djelovanje određeno je vrijeme paralize 0,24 do 1,54 min i vrijeme smrti 0,39 do 4,40 min, dok standarni lijekovi albendazol i piperazin citrat imaju vrijeme paralize 0,54 i 0,58 min, a vrijeme smrti 2,16, odnosno 2,47 min pri istim koncentracijama (1 % m/V). Pet spojeva, 2-[2-hidroksifenil]-4,5-difenil imidazol (1b), 2-[3-metoksifenil]-4,5-difenil imidazol (1c), 2-[2-feniletenil]-4,5-difenil imidazol (1e), 2-[4-fluorofenil]-4,5-difenil imidazol (1g) i 2-[3-nitrofenil]-4,5-difenil imidazol (1h) pokazuju značajno anthelmintičko djelovanje u odnosnu na standardne lijekove

    Mapping localized surface plasmons within silver nanocubes using cathodoluminescence hyperspectral imaging

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    Localized surface plasmons within silver nanocubes less than 50 nm in size are investigated using high resolution cathodoluminescence hyperspectral imaging. Multivariate statistical analysis of the multidimensional luminescence dataset allows both the identification of distinct spectral features in the emission and the mapping of their spatial distribution. These results show a 490 nm peak emitted from the cube faces, with shorter wavelength luminescence coming from the vertices and edges; this provides direct experimental confirmation of theoretical predictions

    Spasticity of the gastrosoleus muscle is related to the development of reduced passive dorsiflexion of the ankle in children with cerebral palsy: A registry analysis of 2,796 examinations in 355 children

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    Background and purpose Spasticity and muscle contracture are two common manifestations of cerebral palsy (CP). A spastic muscle may inhibit growth in length of the muscle, but the importance of this relationship is not known. In 1994, a register and a healthcare program for children with CP in southern Sweden were initiated. The child's muscle tone according to the Ashworth scale and the ankle range of motion (ROM) is measured annually during the entire growth period. We have used these data to analyze the relationship between spasticity and ROM of the gastrosoleus muscle. Patients and methods All measurements in the total population of children with CP aged 0-18 years during the period January 1995 through June 2008 were analyzed. The study was based on 2,796 examinations in 355 children. In the statistical analysis, the effect of muscle tone on ROM was estimated using a random effects model. Results The range of dorsiflexion of the ankle joint decreased in the total material by mean 19 (95% CI: 14-24) degrees during the first 18 years of life. There was a statistically significant association between the ROM and the child's level of spasticity during the year preceding the ROM measurement. Interpretation Spasticity is related to the development of muscle contracture. In the treatment of children with CP, the spasticity, contracture, and strength of the gastrosoleus muscle must be considered together

    Vascular responses of the extremities to transdermal application of vasoactive agents in Caucasian and African descent individuals

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    This is an accepted manuscript of an article published by Springer in European Journal of Applied Physiology on 04/04/2015, available online: https://doi.org/10.1007/s00421-015-3164-2 The accepted version of the publication may differ from the final published version.© 2015, Springer-Verlag Berlin Heidelberg. Purpose: Individuals of African descent (AFD) are more susceptible to non-freezing cold injury than Caucasians (CAU) which may be due, in part, to differences in the control of skin blood flow. We investigated the skin blood flow responses to transdermal application of vasoactive agents. Methods: Twenty-four young males (12 CAU and 12 AFD) undertook three tests in which iontophoresis was used to apply acetylcholine (ACh 1 w/v %), sodium nitroprusside (SNP 0.01 w/v %) and noradrenaline (NA 0.5 mM) to the skin. The skin sites tested were: volar forearm, non-glabrous finger and toe, and glabrous finger (pad) and toe (pad). Results: In response to SNP on the forearm, AFD had less vasodilatation for a given current application than CAU (P = 0.027–0.004). ACh evoked less vasodilatation in AFD for a given application current in the non-glabrous finger and toe compared with CAU (P = 0.043–0.014) with a lower maximum vasodilatation in the non-glabrous finger (median [interquartile], AFD n = 11, 41[234] %, CAU n = 12, 351[451] %, P = 0.011) and non-glabrous toe (median [interquartile], AFD n = 9, 116[318] %, CAU n = 12, 484[720] %, P = 0.018). ACh and SNP did not elicit vasodilatation in the glabrous skin sites of either group. There were no ethnic differences in response to NA. Conclusion: AFD have an attenuated endothelium-dependent vasodilatation in non-glabrous sites of the fingers and toes compared with CAU. This may contribute to lower skin temperature following cold exposure and the increased risk of cold injuries experienced by AFD.Published versio
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