6,856 research outputs found

    A digitally controlled system for effecting and presenting a selected electrical resistance

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    A digitally controlled resistance generator is described, in which resistors having values selected according to an expression 2(sup N-1)(R), where N is equal to the number of terms in the expression, and R is equal to the lowest value of resistance, are electrically inserted into a resistive circuit in accordance with a parallel binary signal provided by an analog-to-digital converter or a programmable computer. This binary signal is coupled via optical isolators which, when activated by a logical 1, provides a negative potential to some or all of the gate inputs of the normally on field effect transistors which, when on, shorts out the associated resistor. This applied negative potential turns the field effect transistors off and electrically inserts the resistor coupled between the source terminal and the drain terminal of that field effect transistor into the resistive circuit between the terminals

    Application of a panel method to wake-vortex/wing interaction and comparison with experimental data

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    The ability of the Vortex Separation AEROdynamics (VSAERO) program to calculate aerodynamic loads on wings due to interaction with free vortices was studied. The loads were calculated for various positions of a downstream following wing relative to an upstream vortex-generating wing. Calculated vortex-induced span loads, rolling-moment coefficients, and lift coefficients on the following wing were compared with experimental results of McMillan et al. and El-Ramly et al. Comparisons of calculated and experimental vortex tangential velocities were also made

    Control biom茅trico: el necesario debate p煤blico

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    Podr铆a decirse que los sistemas de identificaci贸n biom茅trica proporcionan a EEUU y a la Uni贸n Europea la f贸rmula m谩gica para solucionar algunos problemas de seguridad clave (como el terrorismo internacional, la delincuencia organizada y la migraci贸n ilegal) asociados con la usurpaci贸n de la identidad y la falsificaci贸n de documentos. Al ir pasando la utilizaci贸n de la tecnolog铆a biom茅trica de ser algo marginal a ser usual, han surgido importantes cuestiones de fondo en torno a la protecci贸n de datos, la privacidad de las personas y las libertades civiles. En respuesta a los ataques terroristas del 11 de septiembre de 2001, EEUU y la Uni贸n Europea han adoptado soluciones de identificaci贸n biom茅trica destinadas a mejorar la seguridad de los documentos y ampliar las capacidades de control sobre ciudadanos extranjeros. Los sistemas biom茅tricos se emplean para identificar, verificar y clasificar la identidad de una persona bas谩ndose en caracter铆sticas f铆sicas o del comportamiento almacenadas en redes inform谩ticas. Las razones que suelen aducirse a favor de la adopci贸n de sistemas biom茅tricos son el control de fronteras, la protecci贸n contra la falsificaci贸n de documentos y la usurpaci贸n de la identidad, el rastreo de inmigrantes ilegales y delincuentes sospechosos y la prevenci贸n del terrorismo. Dejando de lado cuestiones t茅cnicas sobre la fiabilidad de su funcionamiento en la pr谩ctica, las tecnolog铆as biom茅tricas ponen de manifiesto algunas cuestiones de fondo en torno a la protecci贸n de datos, la privacidad de las personas y las libertades civiles, que no han recibido el suficiente debate p煤blico en Espa帽a y otros pa铆ses de la Uni贸n Europea. La finalidad de este an谩lisis es servir de introducci贸n al origen y la funci贸n de los sistemas de vigilancia y autenticaci贸n biom茅trica, comparar los usos actuales y propuestos de la biometr铆a en EEUU y la UE derivadas, respectivamente, de la Patriot Act y del Sistema de Informaci贸n de Schengen, y comentar las cuestiones de fondo que surgen de la adopci贸n y la 鈥渁rmonizaci贸n鈥 generalizadas de los sistemas biom茅tricos. Se concluye aportando algunas recomendaciones pol铆ticas de car谩cter general

    Aerodynamic and Aeroacoustic Wind Tunnel Testing of the Orion Spacecraft

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    The Orion aerodynamic testing team has completed more than 40 tests as part of developing the aerodynamic and loads databases for the vehicle. These databases are key to achieving good mechanical design for the vehicle and to ensure controllable flight during all potential atmospheric phases of a mission, including launch aborts. A wide variety of wind tunnels have been used by the team to document not only the aerodynamics but the aeroacoustic environment that the Orion might experience both during nominal ascents and launch aborts. During potential abort scenarios the effects of the various rocket motor plumes on the vehicle must be accurately understood. The Abort Motor (AM) is a high-thrust, short duration motor that rapidly separates Orion from its launch vehicle. The Attitude Control Motor (ACM), located in the nose of the Orion Launch Abort Vehicle, is used for control during a potential abort. The 8 plumes from the ACM interact in a nonlinear manner with the four AM plumes which required a carefully controlled test to define the interactions and their effect on the control authority provided by the ACM. Techniques for measuring dynamic stability and for simulating rocket plume aerodynamics and acoustics were improved or developed in the course of building the aerodynamic and loads databases for Orion

    Securitizing Migration after 11 March

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    This analysis draws on the recent experience of the United States to address perceived immigration risks since 9/11, and weighs the prospect of adopting similar approaches in Spain and the European Union following the 11 March terrorist attacks in Madrid. Immigration can be a source of unease in the developed world today due, in part, to the supposed linkage between international migration and global terrorism. Recent trends point to an accelerated growth of migration worldwide, whose networks terrorists are known to exploit. Migration, however, has only in the last decade risen to be a high security issue as state struggles against terrorists and other criminals have been extended to new targets, most notably immigrants. This analysis appraises the 鈥榩roblem鈥 of immigration in the US shortly before and after 9/11, and assesses a range of possible responses to the Madrid attacks on 11 March that could affect how Spain and other EU states deal with immigration and associated risks. In the final analysis, immigration and border authorities are well positioned to contribute to risk prevention with measures that improve the ability to gather and share intelligence needed to detect and detain terrorists and obstruct their plans, but restrictive 鈥榝ortress鈥 responses and sweeping immigrant surveillance appear to hinder rather facilitate cooperation with key immigrant, especially Muslim, communities

    A 2022 review of sodium fluoroacetate for conservation and protecting endangered species

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    Sodium fluoroacetate (1080) is a vertebrate pesticide principally used to control unwanted introduced mammals in New Zealand and Australia. There have been over 260 publications during the last ten years on 1080 which supplement a body of scientific information regarding mode of action, natural occurrence, toxicology, antidotes, metabolism and fate in the environment. Multi-year studies have explored long-term outcomes, for multiple native bird species. Numerous reviews on community attitudes stimulated, in part by the Predator Free New Zealand (PFNZ) 2050 campaign, conclude that 1080 use for conservation remains controversial. Further effort is needed to increase target specificity avoiding game species and employ approaches with the highest public acceptance, including hunting, trapping and eradication strategies that obviate the need for repeated use of toxic baits. Greater acceptance of large-scale use of any pest control is likely when long-term goals and strategies for ecosystem recovery employ toxins as one-off treatments for eradicating pests versus continued applications

    Theoretical and experimental study of flow-control devices for inlets of indraft wind tunnels

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    The design of closed circuit wind tunnels has historically been performed using rule of thumb which have evolved over the years into a body of useful guidelines. The development of indraft wind tunnels, however, has not been as well documented. The design of indraft wind tunnels is therefore generally performed using a more intuitive approach, often resulting in a facility with disappointing flow quality. The primary problem is a lack of understanding of the flow in the inlet as it passes through the required antiturbulence treatment. For wind tunnels which employ large contraction ratio inlets, this lack of understanding is not serious since the relatively low velocity of the flow through the inlet treatment reduces the sensitivity to improper inlet design. When designing a small contraction ratio inlet, much more careful design is needed in order to reduce the flow distortions generated by the inlet treatment. As part of the National Full Scale Aerodynamics Complex Modification Project, 2-D computational methods were developed which account for the effect of both inlet screens and guide vanes on the test section velocity distribution. Comparisons with experimental data are presented which indicate that the methods accurately compute the flow distortions generated by a screen in a nonuniform velocity field. The use of inlet guide vanes to eliminate the screen induced distortion is also demonstrated both computationally and experimentally. Extensions of the results to 3-D is demonstrated and a successful wind tunnel design is presented

    Summer home range size and population density of great spotted kiwi (Apteryx Haastii) in the North Branch of the Hurunui River, New Zealand

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    Home range size, travel distances, and population density of the great spotted kiwi (Apteryx haastii) were investigated in the North Branch of the Hurunui River. Radio tracking was conducted on 10 great spotted kiwi between Dec 2007 and Apr 2008. The estimated minimum home-range sizes were determined using the concave polygon method and ranged between 19.6 ha and 35.4 ha, with a mean of 29.3 ha (卤 1.6 SEM). The observed nightly distances travelled per hour varied from 7 to 433 m (n = 569). Most estimates of travel distances (73%) were clustered in the classes from 0 - 150 m/hour, and distances over 200 m/hour were seldom achieved (only c. 7% of distances). The kiwi population in the Mainland Island site on the western North Branch of the Hurunui River was estimated to hold around 290 birds in total. Population density for the entire North Branch area was estimated to be 2 pairs/km虏 and when including subadults, 5 birds/km虏. Our estimate of home range size is larger but with more variation than found in other studies. Differences in population density estimates between our study and those in the Hurunui and Arthurs Pass district may be due to different objectives and method

    Freeze branding cattle (1993)

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    Freeze branding as a method of livestock identification has been received with enthusiasm. When super-cold or chilled branding irons are applied to the hide of the animal, the pigment-producing cells are destroyed or altered. When the hair grows back, it is white. The method is not foolproof, and those using it should be aware that the results may be variable

    Altered intrinsic functional coupling between core neurocognitive networks in Parkinson\u27s disease

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    Parkinson3s disease (PD) is largely attributed to disruptions in the nigrostriatal dopamine system. These neurodegenerative changes may also have a more global effect on intrinsic brain organization at the cortical level. Functional brain connectivity between neurocognitive systems related to cognitive processing is critical for effective neural communication, and is disrupted across neurological disorders. Three core neurocognitive networks have been established as playing a critical role in the pathophysiology of many neurological disorders: the default-mode network (DMN), the salience network (SN), and the central executive network (CEN). In healthy adults, DMN鈥揅EN interactions are anti-correlated while SN鈥揅EN interactions are strongly positively correlated even at rest, when individuals are not engaging in any task. These intrinsic between-network interactions at rest are necessary for efficient suppression of the DMN and activation of the CEN during a range of cognitive tasks. To identify whether these network interactions are disrupted in individuals with PD, we used resting state functional magnetic resonance imaging (rsfMRI) to compare between-network connectivity between 24 PD participants and 20 age-matched controls (MC). In comparison to the MC, individuals with PD showed significantly less SN鈥揅EN coupling and greater DMN鈥揅EN coupling during rest. Disease severity, an index of striatal dysfunction, was related to reduced functional coupling between the striatum and SN. These results demonstrate that individuals with PD have a dysfunctional pattern of interaction between core neurocognitive networks compared to what is found in healthy individuals, and that interaction between the SN and the striatum is even more profoundly disrupted in those with greater disease severity
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