An experimental study of wall-injected flows in a rectangular cylinder

An experimental investigation of the flow inside a rectangular cylinder with air injected continuously along the wall is performed. This kind of flow is a two-dimensional approximation of what happens inside a solid rocket motor, where the lateral grain burns expelling exhaust gas or in processes with air filtration or devices to attain uniform flows. We propose a brief derivation of some analytical solutions and a comparison between these solutions and experimental data, which are obtained using the Particle Image Velocimetry (PIV) technique, in order to provide a global reconstruction of the flowfield. The flow, which enters orthogonal to the injecting wall, turns suddenly its direction being pushed towards the exit of the chamber. Under the incompressible and inviscid flow hypothesis, two analytical solutions are reported and compared. The first one, known as Hart-McClure solution, is irrotational and the injection velocity is non-perpendicular to the injecting wall. The other one, due to Taylor and Culick, has non-zero vorticity and constant, vertical injection velocity. The comparison with laminar solutions is useful to assess whether transition to turbulence is reached and how the disturbance thrown in by the porous injection influences and modifies those solutions

Heavy particles in the near field of a turbulent jet

The behaviour of aluminium spherical particles of density ρp=2700 Kg/m3 dispersed in a turbulent round water jet, at Reynolds number Re≈15000 and exit Stokes number St0=0.013 is investigated via Particle Image Velocimetry up to x/D=16 from the nozzle exit. Average and fluctuating velocity fields are analysed and compared to the unladen jet condition. Generally, particles are reported not to behave like tracers, in particular outside the region of the jet potential core. Velocity fluctuations are reported to differ from the fluid fluctuations in particular at the jet centreline and shear layers. In particular, axial velocity fluctuations appear to be dominated by the fluid phase whereas a tendency towards an increase of radial fluctuations downstream of the jet exit is reported for particles. The complexity of this scenario suggests a selective particle response with respect to the flow dynamics

The active optics software for the VST telescope

The VST (VLT Survey Telescope) active optics software must basically provide the analysis of the image coming from the wavefront sensor (a 10x10 subpupils Shack Hartmann device) and the calculation of primary mirror forces and secondary mirror displacements to correct the aberrations of the optical system, instrinsic or originated for thermal and gravity reasons. After the telescope commissioning the VST will be operated by ESO. In this framework, INAF-OAC staff was committed to design and realize the software in a VLT-compliant way. This will smoothen the integration, operation and maintenance of the telescope in the Paranal observatory

Identificação de minerais do grupo das zeólitas por espectroscopia de reflectância, para aplicação como remineralizadores de solo.

A utilização de zeólitas para melhorar a qualidade do solo destinado à agricultura ganha espaço em todo o mundo. A elevada capacidade de troca catiônica das zeólitas favorece a conservação de nutrientes no solo e, a alta capacidade de retenção de água em seus retículos cristalinos faz destes minerais excelentes condicionadores de solo. A ausência de depósitos de zeólitas em exploração no Brasil torna os basaltos da Formação Serra Geral da Bacia do Paraná um alvo com grande potencial para a prospecção por zeólitas naturais. Pesquisas da CPRM destacam a significativa presença de zeólitas especialmente no contato entre os derrames inferiores da Formação Serra Geral e os arenitos eólicos da Formação Botucatu no Rio Grande do Sul. A espectroscopia de reflectância é uma ferramenta capaz de contribuir para a identificação de zeólitas em campo ou laboratório, utilizando-se de análises rápidas e de baixo custo. O conhecimento prévio do comportamento espectral das zeólitas é de grande utilidade na prospecção de alvos potenciais na Formação Serra Geral (pilhas de lobos e brechas de topo de derrames basálticos). Nestas ambiências foram reconhecidas macroscopicamente heulandita, escolecita, estilbita, laumontita e mordenita. O presente trabalho apresenta os resultados de leituras em amostras representativas das paragêneses que caracterizam os diferentes blocos determinados pelo Projeto Agrominerais Bacia do Paraná no Rio Grande do Sul-CPRM, com uso do espectrorradiômetro FieldSpec 3 Hi-Res© - ASD, de resolução espectral entre 0,35 e 2,5 μm. Foram identificadas curvas espectrais referentes à estilbita, heulandita, laumontita, mordenita e possivelmente analcima e clinoptilolita, localmente associadas à calcita. Por meio de assinaturas espectrais poderão ser construídos padrões para as zeólitas, para classificação de imagens de satélite, devendo-se considerar a relação entre a dimensão dos alvos e as resoluções espaciais e espectrais dos sensores orbitais e aeroportados disponíveis para o imageamento da área de pesquisa

ETHANOL PRODUCTION FROM A MEMBRANE PURIFIED HEMICELLULOSIC HYDROLYSATE DERIVED FROM SUGAR MAPLE BY PICHIA STIPITIS NRRL Y-7124

In an effort to devise inexpensive and sustainable production of ethanol fuel, experiments were conducted to establish conditions for Pichia stipitis NRRL Y-7124 to ferment a membrane treated wood hydrolysate derived from sugar maple to produce ethanol. The degree of aeration required to effectively utilize xylose, produce ethanol, and minimize xylitol formation as well as the optimal hydrolysate concentration were the conditions examined. P. stipitis produced the highest concentrations of ethanol in shake flasks at 150 rpm (14.3 g/L in 71 h), and 50% hydrolysate maximized ethanol yield (12.4 g/L in 51.5 h). In the 50% hydrolysate cultures, P. stipitis produced ethanol at a rate of 0.24 g/Lh with a yield of 0.41 g ethanol/g wood-derived carbohydrate

The Atmospheric Dispersion Corrector Software for the VST

The effects of atmospheric differential refraction on astrophysical measurements are well known. In particular, as a ray of light passes through the atmosphere, its direction is altered by the effects of atmospheric refraction. The amount of this effect depends basically on the variation of the refractive index along the path of the ray. The real accuracy needed in the atmosphere model and in the calculation of the correction to be applied is of course, considerably worse, especially at large zenith angles. On the VLT Survey Telescope (VST) the use of an Atmospheric Dispersion Corrector (ADC) is foreseen at a wide zenith distance range. This paper describes the software design and implementation aspects regarding the analytical correction law discovered to correct the refraction effect during observations with VST

Design of a Highly Portable Data Logging Embedded System for Naturalistic Motorcycle Study

According to Motorcycle Industrial Council (MIC), in USA the number of owned motorcycle increased during last few years and most likely will keep increasing. However, the number of the deadly crash accidents associated with motorcycles is on the rise. Although MIC doesn\u27t explain why the accident rate has increased, the unprotected motorcyclist gear can be one of the reasons. The most recent National Highway Traffic Safety Administration (NHTSA) annual report stated that its data analyses are based on their experiences and the best judgment is not based on solid scientific experiment [3]. Thus, building a framework for the data acquisition about the motorcyclist environment is a first step towards decreasing motorcyclist crashes. There are a few naturalistic motorcycle studies reported in the literature. The naturalistic motorcycle study also identifies the behaviors and environmental crash hazards. The primary objective of this thesis work is to design a highly portable data logging embedded system for naturalistic motorcycle study with capability of collecting many types of data such as images, speed, acceleration, time, location, distance approximation, etc. This thesis work is the first phase (of three phases) of a naturalistic motorcycle study project. The second phase is to optimize system area, form factor, and power consumption. The third phase will be concerned with aggressive low power design and energy harvesting. The proposed embedded system design is based on an Arduino microcontroller. A whole suite of Arduino based prototype boards, sensor boards, support software, and user forum is available. The system is high portable with capability to store up to eight (8) hours of text/image data during a one month study period. We have successfully designed and implemented the system and performed three trial runs. The data acquired has been validated and found to be accurate

The Fluid-dynamics of endo vascular aneurysm sealing (EVAS) system failure

Purpose The main objective of this work is to investigate hemodynamics phenomena occurring in EVAS (Endo Vascular Aneurysm Sealing), to understand if and how they could lead to type 1a endoleaks and following re-intervention. To this aim, methods based on computational fluid mechanics are implemented as a tool for checking the behavior of a specific EVAS configuration, starting from the post-operative conditions. Pressure and velocity fields are detailed and compared, for two configurations of the Nellix, one as attained after correct implantation and the other in pathological conditions, as a consequence of migration or dislocation of endobags. Methods The computational fluid dynamics (CFD) approach is used to simulate the behavior of blood within a segment of the aorta, before and after the abdominal bifurcation. The adopted procedure allows reconstructing the detailed vascular geometry from high-resolution computerized tomography (CT scan) and generating the mesh on which the equations of fluid mechanics are discretized and solved, in order to derive pressure and velocity field during heartbeats. Results The main results are obtained in terms of local velocity fields and wall pressures. Within the endobags, velocities are usually quite regular during the whole cardiac cycle for the post-implanted condition, whereas they are more irregular for the migrated case. The largest differences among the two cases are observed in the shape and location of the recirculation region in the rear part of the aorta and the region between the endobags, with the formation of a gap due to the migration of one or both of the two. In this gap, the pressure fields are highly different among the two conditions, showing pressure peaks and pressure gradients at least four times larger for the migrated case in comparison to the post-implanted condition. Conclusions In this paper, the migration of one or both endobags is supposed to be related to the existing differential pressures acting in the gap formed between the two, which could go on pushing the two branches one away from the other, thus causing aneurysm re-activation and endoleaks. Regions of flow recirculation and low-pressure drops are revealed only in case of endobag migration and in presence of an aneurysm. These regions are supposed to lead to possible plaque formation and atherosclerosis

Cosmological observations in scalar-tensor quintessence

The framework for considering the astronomical and cosmological observations in the context of scalar-tensor quintessence in which the quintessence field also accounts for a time dependence of the gravitational constant is developed. The constraints arising from nucleosynthesis, the variation of the constant, and the post-Newtonian measurements are taken into account. A simple model of supernovae is presented in order to extract the dependence of their light curves with the gravitational constant; this implies a correction when fitting the luminosity distance. The properties of perturbations as well as CMB anisotropies are also investigated.Comment: 26 pages, 22 figures, to appear in PR

Imaging the first light: experimental challenges and future perspectives in the observation of the Cosmic Microwave Background Anisotropy

Measurements of the cosmic microwave background (CMB) allow high precision observation of the Last Scattering Surface at redshift $z\sim$1100. After the success of the NASA satellite COBE, that in 1992 provided the first detection of the CMB anisotropy, results from many ground-based and balloon-borne experiments have showed a remarkable consistency between different results and provided quantitative estimates of fundamental cosmological properties. During 2003 the team of the NASA WMAP satellite has released the first improved full-sky maps of the CMB since COBE, leading to a deeper insight into the origin and evolution of the Universe. The ESA satellite Planck, scheduled for launch in 2007, is designed to provide the ultimate measurement of the CMB temperature anisotropy over the full sky, with an accuracy that will be limited only by astrophysical foregrounds, and robust detection of polarisation anisotropy. In this paper we review the experimental challenges in high precision CMB experiments and discuss the future perspectives opened by second and third generation space missions like WMAP and Planck.Comment: To be published in "Recent Research Developments in Astronomy & Astrophysics Astrophysiscs" - Vol I