10,802 research outputs found

    Interaction of molecular nitrogen with Free-Electron-Laser radiation

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    We compute molecular continuum orbitals in the single center expansion scheme. We then employ these orbitals to obtain molecular Auger rates and single-photon ionization cross sections to study the interaction of N2 with Free-Electron-Laser (FEL) pulses. The nuclei are kept fixed. We formulate rate equations for the energetically allowed molecular and atomic transitions and we account for dissociation through additional terms in the rate equations. Solving these equations for different parameters of the FEL pulse, allows us to identify the most efficient parameters of the FEL pulse for obtaining the highest contribution of double core hole states (DCH) in the final atomic ion fragments. Finally we identify the contribution of DCH states in the electron spectra and show that the DCH state contribution is more easily identified in the photo-ionization rather than the Auger transitions

    Propfan test assessment testbed aircraft stability and control/performance 1/9-scale wind tunnel tests

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    One-ninth scale wind tunnel model tests of the Propfan Test Assessment (PTA) aircraft were performed in three different NASA facilities. Wing and propfan nacelle static pressures, model forces and moments, and flow field at the propfan plane were measured in these tests. Tests started in June 1985 and were completed in January 1987. These data were needed to assure PTA safety of flight, predict PTA performance, and validate analytical codes that will be used to predict flow fields in which the propfan will operate

    Propfan Test Assessment (PTA)

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    The objectives of the Propfan Test Assessment (PTA) Program were to validate in flight the structural integrity of large-scale propfan blades and to measure noise characteristics of the propfan in both near and far fields. All program objectives were met or exceeded, on schedule and under budget. A Gulfstream Aerospace Corporation GII aircraft was modified to provide a testbed for the 2.74m (9 ft) diameter Hamilton Standard SR-7 propfan which was driven by a 4475 kw (600 shp) turboshaft engine mounted on the left-hand wing of the aircraft. Flight research tests were performed for 20 combinations of speed and altitude within a flight envelope that extended to Mach numbers of 0.85 and altitudes of 12,192m (40,000 ft). Propfan blade stress, near-field noise on aircraft surfaces, and cabin noise were recorded. Primary variables were propfan power and tip speed, and the nacelle tilt angle. Extensive low altitude far-field noise tests were made to measure flyover and sideline noise and the lateral attenuation of noise. In coopertion with the FAA, tests were also made of flyover noise for the aircraft at 6100m (20,000 ft) and 10,668m (35,000 ft). A final series of tests were flown to evaluate an advanced cabin wall noise treatment that was produced under a separate program by NASA-Langley Research Center

    Linguistic modality affects the creation of structure and iconicity in signals

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    Different linguistic modalities (speech or sign) offer different levels at which signals can iconically represent the world. One hypothesis argues that this iconicity has an effect on how linguistic structure emerges. However, exactly how and why these effects might come about is in need of empirical investigation. In this contribution, we present a signal creation experiment in which both the signalling space and the meaning space are manipulated so that different levels and types of iconicity are available between the signals and meanings. Signals are produced using an infrared sensor that detects the hand position of participants to generate auditory feedback. We find evidence that iconicity may be maladaptive for the discrimination of created signals. Further, we implemented Hidden Markov Models to characterise the structure within signals, which was also used to inform a metric for iconicity

    A new artificial sign-space proxy for investigating the emergence of structure and categories in speech

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    En relación con las publicaciones presentadas en el Clabes I, donde se mencionan las nuevas estrategias implementadas para afrontar el desgranamiento, blended learning y tutorías; y Clabes II, en el que referimos a una ampliación y profundización tanto en las políticas como en las metodología a implementar desde dos niveles: Nacional desde el Rectorado de la Universidad y Local desde la Facultad Regional Resistencia; en esta oportunidad se presentan los resultados de la acción emprendida en el año 2012 en la línea de acceso e integración de alumnos a las carreras ofrecidas por la Facultad. En este sentido se puede decir que se ha reforzado la apuesta; la institución no conforme con las actividades desarrolladas al interior de la misma, organizó un ciclo de visitas a las escuelas de Nivel Medio de la Zona de influencia. La Facultad Regional Resistencia se viene desarrollando desde el año 2006 diferentes acciones tendientes a la disminución del desgranamiento de los alumnos en los primeros tramos de las carreras. Todas estas acciones, hacia adentro de la institución, es decir, saber cuáles son los motivos que llevan a los alumnos a desgranar en los primero años, realizar un seguimiento de los ingresantes a través del sistema de acción tutorial, utilizar en el seminario universitario metodologías que promuevan a la autorregulación. Todas iniciativas desarrolladas una vez que el alumno ha elegido la carrera y nuestra facultad. Si bien se han obtenido mejora en los resultados con las acciones antes mencionadas la Facultad inició un camino de articulación con el nivel medio en colaboración con las Direcciones de carrera y la Secretaría de Extensión Universitaria. Se organizaron y ejecutaron bajo el eslogan “la UTN va a las escuelas”, una serie de talleres informativos en los que participaron unos 3.000 alumnos de escuelas secundarias. Los talleres tienen como objetivos: generar un marco propicio para el ingreso y permanencia de los alumnos en la universidad, informar a los estudiantes acerca de las diferentes opciones de carrera que brinda la institución y proporcionar herramientas metodológicas que propicien una mejor inserción académica. Entendemos que estas acciones se enmarcan en la responsabilidad social que le compete a la Universidad, parafraseando a François Vallaeys (2007), la institución debe hacer una reflexión sobre sí misma de su accionar en su entorno social, un análisis de su responsabilidad y, sobre todo, de su parte de culpabilidad en los problemas crónicos de la sociedad. Los talleres se centraron en trabajar la autorregulación de los futuros estudiantes universitarios como una habilidad meta cognitiva que puede resultar clave para el éxito o el fracaso académico, según lo consideran algunos autores entre ellos Corral (2003). Si bien no se está en condiciones de afirmar cuánto influye esta habilidad en la definición de las estrategias utilizadas para la apropiación y retención de los contenidos y consecuentemente en el rendimiento academico, sin embargo los estudiantes que mayor comportamiento autorregulado demuestran obtienen un mejor rendimiento en las diferentes áreas académicas

    Emergence of signal structure: Effects of duration constraints

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    Recent work has investigated the emergence of structure in speech using experiments which use artificial continuous signals. Some experiments have had no limit on the duration which signals can have (e.g. Verhoef et al., 2014), and others have had time limitations (e.g. Verhoef et al., 2015). However, the effect of time constraints on the structure in signals has never been experimentally investigated

    Propfan Test Assessment (PTA): Flight test report

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    The Propfan Test Assessment (PTA) aircraft was flown to obtain glade stress and noise data for a 2.74m (9 ft.) diameter single rotation propfan. Tests were performed at Mach numbers to 0.85 and altitudes to 12,192m (40,000 ft.). The propfan was well-behaved structurally over the entire flight envelope, demonstrating that the blade design technology was completely adequate. Noise data were characterized by strong signals at blade passage frequency and up to 10 harmonics. Cabin noise was not so high as to preclude attainment of comfortable levels with suitable wall treatment. Community noise was not excessive
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