4,221 research outputs found
MPD work at MIT
MPD work at MIT is presented in the form of the view-graphs. The following subject areas are covered: the MIT program, its goals, achievements, and roadblocks; quasi one-dimensional modeling; two-dimensional modeling - transport effects and Hall effect; microscopic instabilities in MPD flows and modified two stream instability; electrothermal stability theory; separation of onset and anode depletion; exit plane spectroscopic measurements; phenomena of onset as performance limiter; explanations of onset; geometry effects on onset; onset at full ionization and its consequences; relationship to anode depletion; summary on self-field MPD; applied field MPD - the logical growth path; the case for AF; the challenges of AF MPD; and recommendations
Gobierno local abierto: diagnóstico en México y Oaxaca
Con un enfoque centrado en el ciudadano y el uso de las tecnologías de la información y la comunicación, la expresión gobierno abierto ha revolucionado la administración pública. Esto ha implicado una alta deliberación, colaboración, participación y publicidad. El objetivo del presente artículo es diagnosticar los estados cuyos municipios siguen el proyecto de gobierno abierto, para lo cual se tomó como muestra a los estados de México y Oaxaca, donde se compararon los estratos de desarrollo humano muy alto y bajo. A partir de ello se formuló la hipótesis de que los gobiernos locales en México responden de forma diferente a la expresión gobierno abierto cuando este tiene que ver de manera directa y proporcional con el desarrollo humano. Es decir, los municipios con mayor desarrollo humano tuvieron también mayor nivel de gobierno abierto, mientras que los gobiernos con menor desarrollo humano alcanzaron niveles inferiores de gobierno abierto. Se estudiaron 30 municipios de ambas entidades, con diez variables a analizar mediante contraste estadístico de chi cuadrada y coeficiente de correlación r de Pearson. Los resultados demostraron que sí existe una relación entre desarrollo humano y gobierno abierto
Blade scale effects of tip leakage
October 1990Includes bibliographical references (leaves 43-44)The effects of blade-tip leakage in a turbine are investigated by modeling the stage as an incomplete actuator disk. It is found that the spanwise flow redistribution due to the gap is such as to produce a uniform unloading of the blades, despite the very concentrated leakage. Partial lift retention at the blade tip is accounted for based on a leakage jet-free stream collision model which successfully predicts the roll-up of the leakage flow. The predicted efficiency loss due to the gap correlates well with experimental data
Rotordynamic forces in labyrinth seals: Theory and experiment
A theoretical and experimental investigation of the aerodynamic forces generated by a single gland labyrinth seal executing a simultaneous spinning/whirling motion has been conducted. A lumped parameter model for a single gland seal with coupling to an upstream cavity with leakage is developed along with an appropriate solution technique. From this theory, it is shown that the presence of the upstream cavity can, in some cases, augment the cross-stiffness and direct damping by a factor of four. The parameters that govern the coupling are presented along with predictions on their influence. A simple uncoupled model is used to identify the mechanisms responsible for cross force generation. This reduced system is nondimensionalized and the physical significance of the reduced parameters is discussed. Closed form algebraic formulas are given for some simple limiting cases. It is also shown that the total cross-force predicted by the uncoupled model can be represented as the sum of an ideal component due to an inviscid flow with entry swirl and a viscous part due to the change in swirl created by friction inside the gland. The frequency dependent ideal part is solely responsible for the rotordynamic direct damping. The facility designed and built to measure these frequency dependent forces is described. Experimental data confirm the validity and usefulness of this ideal/viscous decomposition. A method for calculating the damping coefficients based on the force decomposition using only the static measurements is presented. Experimental results supporting the predicted cross force augmentation due to the effect of upstream coupling are presented
Proyecto Básico de acondicionamiento de la N-332 entre el PK 192 y el PK 195 en el término municipal de Pedreguer (Alicante)
[EN] This basic refurbishment project is located on the national road N-332 at the level of the Municipality of Pedreguer in Alicante.
The objective of this basic project is to carry out a refurbishment of the national road N-332, where it has been seen the need to improve the access of this road with the construction of two new service roads and a roundabout.
The purpose of this conditioning is to improve the current consistency of the N-332 , since after a detailed analysis it has been discovered that it presents a very unstable traffic, In addition to this it is added the dangerous accesses that are in it, not guaranteeing the safety of the road users.
For the implementation of these service routes it was necessary to carry out new drainage works for the national N-332, since those currently available could not accommodate the estimated project flows, In this way an improvement is made.
This upgrading has improved the consistency and safety of road users by providing adequate accessibility to neighbouring municipalities and infrastructure.[CA] Aquest projecte bàsic de condicionament se situa en la carretera nacional N-332 a l'altura del Municipi de Pedreguer a Alacant.
L'objectiu d'aquest projecte bàsic és realitzar un condicionament de la carretera nacional N-332, on s'ha vist la necessitat de millorar els accessos d'aquesta via amb la construcció de dues noves vies de servei i una glorieta.
La fi d'aquest condicionament és la millora de la consistència actual de la N-332 , ja que després de realitzar una anàlisi detallada s'ha descobert que presenta un trànsit molt inestable, a més a això se li suma els perillós accessos que es troben en ella, no garantint la seguretat dels usuaris de la carretera.
Per a la implantació d'aquestes vies de servei s'ha vist necessari realitzar unes noves obres de drenatge per a la nacional N-332, ja que les que hi ha en l'actualitat no podien albergar els cabals de projecte calculats, d'aquesta manera es realitza una millora d'aquesta.
Amb aquest condicionament s'ha millorat la consistència i la seguretat dels usuaris de la carretera donant una accessibilitat adequada als municipis i infraestructures confrontants confrontants.[ES] Este proyecto básico de acondicionamiento se sitúa en la carretera nacional N-332 a la altura del Municipio de Pedreguer en Alicante.
El objetivo de este proyecto básico es realizar un acondicionamiento de la carretera nacional N-332, donde se ha visto la necesidad de mejorar los accesos de dicha vía con la construcción de dos nuevas vías de servicio y una glorieta.
El fin de este acondicionamiento es la mejora de la consistencia actual de la N-332 , ya que tras realizar un análisis detallado se ha descubierto que presenta un tráfico muy inestable, además a esto se le suma los peligroso accesos que se encuentran en ella, no garantizando la seguridad de los usuarios de la carretera.
Para la implantación de estas vías de servicio se ha visto necesario realizar unas nuevas obras de drenaje para la nacional N-332, ya que las que hay en la actualidad no podían albergar los caudales de proyecto calculados, de esta manera se realiza una mejora de la misma.
Con este acondicionamiento se ha mejorado la consistencia y la seguridad de los usuarios de la carretera dando una accesibilidad adecuada a los municipios e infraestructuras colindantes colindantes.Martinez Sanchez, M. (2019). Proyecto Básico de acondicionamiento de la N-332 entre el PK 192 y el PK 195 en el término municipal de Pedreguer (Alicante). http://hdl.handle.net/10251/126464Archivo delegad
Regulación, Supervisión y Conservadurismo Contable: La Interacción de los Tres Pilares de Basilea II con la Calidad de los Resultados Reportados en la Banca Mundial
Accounting conservatism is a quality of earnings positively associated with the strength of banking regu-
lation and supervision and also high market discipline, but there still remains the unresolved question of
the way these three pillars of Basel II interact with each other. We analyse how regulatory and supervisory
regimes in the banking industry clearly interact with market discipline measures, such as listing status, own-
ership, market concentration and disclosure requirements between ten years before Basel II fails, drawing
upon data from 14,651 bank year observations from 54 different countries.
According to our findings, there is a clear correlation between the strength of the enforcement of regulation
and supervision and accounting conservatism success in countries where market discipline fails. That is
to say, the supervisory power reinforces the effect of listing status, ownership and concentration on con-
servatism whereas the capital regulatory system mitigates the effect of market discipline on conservatism.
We also evidence that in a powerful regulatory system, more disclosure requirements are associated in less
conservatism policies in financial entities.
Strong increases in regulation, its enforcement and supervisory power introduced in the Basel III mechanism
is subject to the debate posed in this paper. The quality of accounting earnings can be improved to prevent
bank failures through the application of strong Pillars I and II, i.e., regulation and supervision. Having said
that, market discipline still remains a key factor in achieving financial stability.El conservadurismo contable es una cualidad de las ganancias asociada positivamente con la solidez de la
regulación y supervisión bancaria y también con la alta disciplina del mercado, pero aún queda la cuestión
sin resolver de la forma en que estos tres pilares de Basilea II interactúan entre sí. Analizamos cómo los
regímenes regulatorios y de supervisión en la industria bancaria interactúan claramente con las medidas
de disciplina del mercado, como si cotizan o no, la distinta estructura de propiedad, la concentración del
mercado y los requisitos de divulgación en una muestra de 14.651 observaciones de 54 países diferentes
durante los diez años anteriores al fallo de Basilea II.
Según nuestros hallazgos, existe una clara correlación entre la fortaleza de la regulación y la supervisión
bancaria y el nivel del conservadurismo contable en países donde la disciplina de mercado es débil. Es decir,
el poder de supervisión refuerza el efecto del estatus de cotización, la propiedad y la concentración sobre
el conservadurismo, mientras que el sistema de regulación de capital mitiga el efecto de la disciplina de
mercado sobre el conservadurismo. También evidenciamos que, en un sistema regulatorio poderoso, más
requisitos de divulgación están asociados con políticas menos conservadoras en las entidades financieras.
Los resultados obtenidos contribuyen al debate sobre si los fuertes incrementos en la regulación bancaria,
y el mayor poder de supervisión introducidos en el mecanismo de Basilea III están justificados ante fallos
en la disciplina de mercado introducida por Basilea II. La calidad del resultado contable se puede mejorar
para prevenir quiebras bancarias mediante la aplicación de fuertes Pilares I y II, es decir, regulación y
supervisión. Dicho esto, la disciplina del mercado sigue siendo un factor clave para lograr la estabilidad
financiera, pero sigue sin ser el más relevante
Use of emission spectroscopy for real-time assessment of relative wall erosion rate of BHT-200 hall thruster for various regimes of operation
Radiation emission due to Boron atoms sputtered from the Boron-Nitride ceramic walls of a BHT-200 Hall thruster was measured as
a diagnostic for real time assessment of thruster wall erosion and to determine the e ects of various operation conditions on thruster
lifetime. Boron neutral 249.677 and 249.773nm lines were measured using a high resolution spectrometer. Spectral measurement
results and the accompanying analysis and discussion are presented in this study. From the spectral measurements it was observed
that the Boron emission intensity significantly increases for increased discharge voltage pointing to a large increase in the thruster
wall erosion rate. Additionally, the measurements show that for the nominal discharge voltage and the applied magnetic field
intensity, there is an optimum propellant flow rate for minimum Boron emission, thus minimum wall erosion rate. The variation
in the current to the magnet coils showed that the Boron emission intensity increases for increased magnetic field and the Boron
emission intensity shows similar behavior to that of the Xenon single ion emission line intensity at 248.911nm. The findings of the
study show that emission spectroscopy can be used in determining the optimum operational parameters for minimum wall erosion
for SPT type Hall thrusters
Variation of the ultraviolet extinction law across the Taurus-Auriga star forming complex. A GALEX based study
The Taurus-Auriga molecular complex (TMC) is the main laboratory for the
study of low mass star formation. The density and properties of interstellar
dust are expected to vary across the TMC. These variations trace important
processes such as dust nucleation or the magnetic field coupling with the
cloud. In this article, we show how the combination of near ultraviolet (NUV)
and infrared (IR) photometry can be used to derive the strength of the 2175
\AA\ bump and thus any enhancement in the abundance of small dust grains and
PAHs in the dust grains size distribution. This technique is applied to the
envelope of the TMC, mapped by the GALEX All Sky Survey (AIS). UV and IR
photometric data have been retrieved from the GALEX-AIS and the 2MASS
catalogues. NUV and K-band star counts have been used to identify the areas in
the cloud envelope where the 2175 \AA\ bump is weaker than in the diffuse ISM
namely, the low column density extensions of L1495, L1498 and L1524 in Taurus,
L1545, L1548, L1519, L1513 in Auriga and L1482-83 in the California region.
This finding agrees with previous results on dust evolution derived from
Spitzer data and suggests that dust grains begin to decouple from the
environmental galactic magnetic field already in the envelope.Comment: Accepted in Monthly Notices of the Royal Astronomical Societ
Localized pulsed nanosecond discharges in a counterflow nonpremixed flame environment
A flame is a very unusual environment for the development of a gas discharge, since it presents strong gradients in temperature, composition, and pre-ionization. In this paper we examine how such an environment impacts the development of the plasma when using repetitive pulsed nanosecond discharges, one of the main strategies used in the field of plasma assisted combustion. Experiments were performed in a counterflow nonpremixed burner with parallel electrodes at the nozzle exits and nanosecond-resolved photography of the plasma emission is presented. It was shown that the discharge development in stratified media may take place in the form of a dielectric barrier discharge with a localized energy deposition. In the experiments presented the discharge energy was coupled to the flame front because of the high rate of chemi-ionization and the gas density decrease in the flame
- …