No description available.

A subsonic wind tunnel facility was designed and built to test and optimize various diffuser-collector box geometries at the one-twelfth scale.  The facility was designed to run continuously at an inlet Mach number of 0.42 and an inlet hydraulic diameter Reynolds number of 340,000. Different combinations of diffusers, hubs, and exhaust collector boxes were designed and evaluated for overall optimum performance. Both 3-hole and 5-hole probes were traversed into the flow to generate multiple diffuser inlet and collector exit performance profile plots. Surface oil flow visualization was performed to gain an understanding of the complex 3D flow structures inside the diffuser-collector subsystem. The cutback radial hardware was found to increase the subsystem pressure recovery by over 10% from baseline resulting in an approximate 1% increase in gas turbine power output. / Master of Science

Orientador: João Francisco Escobedo / Banca: Dinival Martins / Banca: Alexandre Dal Pai / Resumo: Este trabalho objetivou apresentar a evolução anual das irradiações global ( d ) G H b , direta ( d ) B H b e difusa de referência ( d ) DR H b média mensal com medidas diárias incidentes sobre superfícies inclinadas a 12,85º L − 10º , 22,85º L e 32,85º L + 10º com a face voltada para o Norte e as estimativas das três irradiações com base em medidas da irradiação global na horizontal e da razão de insolação. O periodo de dados considerado no estudo foi de 1998 a 2007, com medidas realizadas entre 04/1998 a 08/2001 para a inclinação de 22,85º; de 09/2001 a 02/2003 para 12,85º e de 01/2004 a 12/2007 para a inclinação de 32,85º. Em todos os períodos de medidas, os valores as tres irradiações foram comparadas com medidas realizadas em superfícies horizontais. Os níveis de ( d ) H Gb nos planos inclinados foram inferiores no período de verão e superiores entre os equinócios quando comparados com as superfícies horizontais. Houve uma tendência de aumento da diferença entre ( d ) H Gb e ( d ) H GH com o aumento da intensidade de inclinação. Os picos máximos médios mensais verificados nas inclinações foram de 22,04; 22,64 e 21,82 MJ m-2 dia-1, ocorridos em setembro, abril e agosto, enquanto que os picos mínimos foram de 16,08; 17,00 e 16,39 MJ m-2 dia-1 nos meses de maio, junho e janeiro, para as inclinações de L − 10º , L e L + 10º , respectivamente. Nas superfícies horizontais nesse período de medidas foram verificados máximos e minimos de 23,64 e 12,95 MJ m-2 dia-1, em novembro e junho. As radiações diretas na horizontal foram projetadas nas inclinações e foram obtidos pelo produto entre ( d ) bH H e o fator geométrico ( ) B R . Os valores de ( ) d H Bb foram inferiores aos de ( ) d H BH no verão e superiores no inverno, com diferenças crescentes com o aumento da inclinação. Os valores máximos... (resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work planned to present the annual evolution of the diffuse reference, beam, and global irradiations of monthly medium with daily measures incidents about surfaces inclined to 12,85º L − 10º , 22,85º L e 32,85º L + 10º with facing the Nort and the estimates of the three irradiations on the basis of measures of the global irradiation in the horizontal one and of the reason of sunshine. The period of facts considered in the study was of 1998 to 2007, with measures carried out between 04/1998 to 08/2001 for the inclination of 22,85º; of 09/2001 to 02/2003 for 12,85º and of 01/2004 to 12/2007 for the inclination of 32,85º. In all of the periods of measures, the values the three irradiations were compared with measures carried out in horizontal surfaces. The levels of ( d ) H Gb in the planes tilters were lower in the period of summer and superiors between the equinoxes when compared with the horizontal surfaces. Had a tendency of increase of the difference between ( d ) H Gb and ( d ) H GH increase with of the intensity of inclination. The monthly medium maximum peaks verified in the inclinations were of 22,04; 22,64 e 21,82 MJ m-2, they occurred in september, april and august, whereas the most minimum peaks were of 16,08; 17,00 e 16,39 MJ m-2 in the months of may, june and january, for the inclinations of L-10º, L and L+10º, respectively. In the horizontal surfaces in that period of measures were verified maximum and minimum of 23,64 e 12,95 MJ m-2, in november and june. The direct radiations in the horizontal one were projected in the inclinations and were obtained by the product between ( d ) bH H and the geometrical factor ( ) B R . The values of ( ) d H Bb were lower to ( ) d H BH of the in the summer... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:26:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-18Bitstream added on 2014-06-13T20:34:41Z : No. of bitstreams: 1 souza_ap_me_botfca.pdf: 2085223 bytes, checksum: 6f1e33f2d9020a877fb0c3f6857acac1 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / Este trabalho objetivou apresentar a evolução anual das irradiações global ( d ) G H b , direta ( d ) B H b e difusa de referência ( d ) DR H b média mensal com medidas diárias incidentes sobre superfícies inclinadas a 12,85º L − 10º , 22,85º L e 32,85º L + 10º com a face voltada para o Norte e as estimativas das três irradiações com base em medidas da irradiação global na horizontal e da razão de insolação. O periodo de dados considerado no estudo foi de 1998 a 2007, com medidas realizadas entre 04/1998 a 08/2001 para a inclinação de 22,85º; de 09/2001 a 02/2003 para 12,85º e de 01/2004 a 12/2007 para a inclinação de 32,85º. Em todos os períodos de medidas, os valores as tres irradiações foram comparadas com medidas realizadas em superfícies horizontais. Os níveis de ( d ) H Gb nos planos inclinados foram inferiores no período de verão e superiores entre os equinócios quando comparados com as superfícies horizontais. Houve uma tendência de aumento da diferença entre ( d ) H Gb e ( d ) H GH com o aumento da intensidade de inclinação. Os picos máximos médios mensais verificados nas inclinações foram de 22,04; 22,64 e 21,82 MJ m-2 dia-1, ocorridos em setembro, abril e agosto, enquanto que os picos mínimos foram de 16,08; 17,00 e 16,39 MJ m-2 dia-1 nos meses de maio, junho e janeiro, para as inclinações de L − 10º , L e L + 10º , respectivamente. Nas superfícies horizontais nesse período de medidas foram verificados máximos e minimos de 23,64 e 12,95 MJ m-2 dia-1, em novembro e junho. As radiações diretas na horizontal foram projetadas nas inclinações e foram obtidos pelo produto entre ( d ) bH H e o fator geométrico ( ) B R . Os valores de ( ) d H Bb foram inferiores aos de ( ) d H BH no verão e superiores no inverno, com diferenças crescentes com o aumento da inclinação. Os valores máximos... / This work planned to present the annual evolution of the diffuse reference, beam, and global irradiations of monthly medium with daily measures incidents about surfaces inclined to 12,85º L − 10º , 22,85º L e 32,85º L + 10º with facing the Nort and the estimates of the three irradiations on the basis of measures of the global irradiation in the horizontal one and of the reason of sunshine. The period of facts considered in the study was of 1998 to 2007, with measures carried out between 04/1998 to 08/2001 for the inclination of 22,85º; of 09/2001 to 02/2003 for 12,85º and of 01/2004 to 12/2007 for the inclination of 32,85º. In all of the periods of measures, the values the three irradiations were compared with measures carried out in horizontal surfaces. The levels of ( d ) H Gb in the planes tilters were lower in the period of summer and superiors between the equinoxes when compared with the horizontal surfaces. Had a tendency of increase of the difference between ( d ) H Gb and ( d ) H GH increase with of the intensity of inclination. The monthly medium maximum peaks verified in the inclinations were of 22,04; 22,64 e 21,82 MJ m-2, they occurred in september, april and august, whereas the most minimum peaks were of 16,08; 17,00 e 16,39 MJ m-2 in the months of may, june and january, for the inclinations of L-10º, L and L+10º, respectively. In the horizontal surfaces in that period of measures were verified maximum and minimum of 23,64 e 12,95 MJ m-2, in november and june. The direct radiations in the horizontal one were projected in the inclinations and were obtained by the product between ( d ) bH H and the geometrical factor ( ) B R . The values of ( ) d H Bb were lower to ( ) d H BH of the in the summer... (Complete abstract click electronic access below)

Thesis focuses on the principles and properties of the tilted Bragg fiber gratings. Two models of the principal cladding mode behaviour are proposed and ther respective results compared with experimental data. The experimental setup for the preparation of the tilted gratings is described. The thesis shows the evaluation of the gratings parameters for the set of prepared gratings. Application of the tilted gratings in the sensors is discussed

Silt fence is one of the most widely used perimeter control devices and is considered an industry standard for use in the control of sediment transport from construction sites. Numerous research studies have been conducted on the use of silt fence as a perimeter control, including a number of studies involving controlled laboratory flume tests and outdoor tests performed in the field on construction sites with actual monitored storm events. In field tests, due to the random and uncontrollable nature of real storm events and field conditions, studies have shown difficulty in evaluating silt fence performance. These field studies have shown the need for performance testing of silt fence in a more controlled environment, which can also simulate the actual use and performance in the field. This research, which is a continuation of ongoing research on silt fence fabrics at UCF Stormwater and Management Academy, was conducted in order to evaluate silt fence performance under simulated field conditions. Presented in this thesis are evaluation of two silt fence fabrics, a woven (ASR 1400) fabric and nonwoven (BSRF) fabric. Both fabrics were installed separately on a tilted test bed filled with a silty-sand soil and subjected to simulated rainfall. Previous field studies on the performance of silt fence fabrics have evaluated the turbidity and sediment removal efficiencies only after the rain event, with the assumption that the efficiency values represent the true overall performance of silt fence. The results of this study revealed that the turbidity and suspended sediment performance efficiencies of silt fence were significantly affected by the time of sampling. The performance efficiencies during rainfall remained less than 55 percent, however, after the rainfall event ended, the performance efficiencies increased over time, reaching performance efficiency upwards of 90 percent. The increase in efficiency after rainfall was due to the constant or decreasing ponding depth behind the silt fence, increased filtration due to fabric clogging, and sedimentation of suspended particles. The nonwoven fabric was found to achieve higher removal efficiencies and flow-through rates both during and after the rain event when compared with the woven fabric. However, over the entire test duration (during and after rainfall combined), the projected overall efficiencies of both fabrics were similar. The projected overall average turbidity performance efficiencies of the woven and nonwoven silt fence fabrics was 80 and 78 percent, respectively. Both fabric types also achieved comparable overall average suspended sediment concentration efficiencies of 79 percent. This result leads to the conclusion that silt fence performance in the field is dependent on three main processes: filtration efficiency occurring during the rain event, filtration and sedimentation efficiency occurring after the rainfall event, and flow-through rate of the silt fence fabrics. Decreases in the flow-through rate lead to increases in the overall efficiency. This thesis quantifies the different mechanisms by which these processes contribute to the overall efficiency of the silt fence system and shows how these processes are affected by different conditions such as the degree of embankment slope and rainfall intensity.

No description available.

A method is described for preset-count irradiations between 1 and 100 ions singling-out individual ions from an ion beam with more than a billion ions arriving per second. The ion tracks are etched in a conductometric system with real-time evaluation of the acquired data. The etch process can be interrupted when reaching a preset channel diameter. Cylindrical channels are obtained by adding surfactants to the etch solution forming a self-assembled barrier between etching medium and polymer. Asymmetric etching of single ion tracks leads to pH sensitive conical pores with diode-like properties. Using etched channels as template, homogeneous and multilayer magnetic single-wires are electrodeposited. The magnetoresistivity of the wires is studied. Single-track applications comprise critical apertures (cylindric, conic, necked), asymmetric pores (pH sensitive, biospecific), Giant Magneto Resistance sensors, and spintronic devices. On the basis of studies with individual ion tracks we tackled tilted multiporous systems such as ion beam lithography with a masked ion beam leading to micro-structures with inclined walls and anisotropic superhydrophobic ion track textures, analogous to biological shingle structures on butterfly wings. We demonstrated qualitatively, that the asymmetry of the texture translates into motion under ultrasonic agitation. This could lead to the development of rotary drives.

The requirements of the consumer market on high frequency devices have been more and more demanding over the last decades. Thus, a continuing enhancement of the devices’ performance is required in order to meet these demands. In a macro view, changing the design of the device can result in an improvement of its performance. In a micro view, the physical properties of the device materials have a strong influence on its final performance. In the case of high frequency devices based on piezoelectric materials, a natural way to improve their performance is through the improvement of the properties of the piezoelectric layer. The piezoelectric material studied in this work is AlN, which is an outstanding material among other piezoelectric materials due to its unique combination of material properties. This thesis presents results from experimental studies on the synthesis of AlN thin films in view of telecom, microelectronic and sensor applications. The main objective of the thesis is to custom design the functional properties of AlN to best suit these for the specific application in mind. This is achieved through careful control of the crystallographic structure and texture as well as film composition. The piezoelectric properties of AlN films were enhanced by doping with Sc. Films with different Sc concentrations were fabricated and analyzed, and the coupling coefficient (kt2) was enhanced a factor of two by adding 15% of Sc to the AlN films. The enhancement of kt2 is of interest since it can contribute to a more relaxed design of high frequency devices. Further, in order to obtain better deposition control of c-axis tilted AlN films, a new experimental setup were proposed. When this novel setup was used, films with well-defined thicknesses and tilt uniformity were achieved. Films with such characteristics are very favorable to use in sensors based on electroacoustic devices operating in viscous media. Studies were also performed in order to obtain c-axis oriented AlN films deposited directly on Si substrates at reduced temperatures. The deposition technique used was HiPIMS, and the results indicated significant improvements in the film texture when comparing to the conventional Pulsed DC deposition process.

La bonne ténacité des aciers pour gazoducs aux basses températures est nécessaire pour éviter la propagation de fissures de manière catastrophique. Cette étude vise à améliorer la compréhension physique et l'évaluation quantitative du comportement à rupture des aciers pour gazoducs laminés à chaud, en nous intéressant plus particulièrement aux températures au pied de la transition ductile-fragile .La résilience de ces aciers est généralement validée à l'aide d'essais dits drop weight tear tests (DWTT), après lesquels le faciès de rupture doit contenir moins de 15% de zone fragile. Pour les aciers mis en forme par laminage thermomécanique (TMCP), des ruptures fragiles hors plan, comme le délaminage (qui se propage dans le plan de laminage de la tôle), et la rupture fragile en biseau le long des plans dits thêta (inclinés de 40° autour de la direction de laminage par rapport au plan de laminage) apparaissent dans la transition ductile-fragile. Ces modes de rupture, observés lors des essais de résilience (DWTT, Charpy) et de ténacité (CT), affectent la résistance à la rupture de ces aciers.L'anisotropie de l'écoulement plastique, puis celle de la sensibilité à la rupture par clivage ont été caractérisées en fonction de la température, à l'aide d'essais de traction sur des éprouvettes lisses et entaillées conçues pour cette étude. L'analyse mécanique de ces essais à l'aide de calculs par éléments finis a permis de déterminer des contraintes critiques de clivage dans les directions perpendiculaires au plan de laminage et aux plans thêta. Les valeurs obtenues dans ces directions sont de 25% inférieures à celles correspondant aux directions de laminage et travers long.L'anisotropie de la contrainte critique de clivage a été quantitativement corrélée à l'anisotropie de microtexture du matériau. Des entités appelées « facettes de clivage potentielles » ont été définies et mesurées dans cette étude, comme des régions contenant un plan {100} défavorablement orienté et dans lesquelles les fissures de clivage se propagent sans être arrêtées. Par exemple, un plan contenant 20% de facettes de clivage potentielles aurait une contrainte critique de clivage de 20% moins élevée qu'un plan présentant seulement 10% de facettes de clivage potentielles.La taille et la forme de ces facettes de clivage potentielles évoluent avec la déformation plastique. Par conséquent, la contrainte critique de clivage est affectée par l'historique de déformation. Dans le cas du délaminage, les facettes de clivage potentielles s'allongent au cours d'un chargement dans la direction travers long, conduisant à une augmentation de leur taille effective et par conséquent à une diminution (qui peut atteindre 30%) de la contrainte critique de clivage dans le plan de la tôle. Cette diminution facilite in fine l'apparition du délaminage. De plus, la présence de micro-fissures ductiles facilite la rupture par délaminage en modifiant l'état de contrainte local. Un critère a ainsi été proposé pour prédire numériquement l'amorçage du délaminage dans des éprouvettes de traction et/ou de résilience Charpy.L'application de cette approche à des échantillons traités thermiquement et à des échantillons pré-déformés a montré que la sensibilité au délaminage pouvait être contrôlée en modifiant la texture locale initiale du matériau. / High toughness of pipeline steels at low temperature is required to avoid catastrophic propagation of brittle crack. The aim of the study is to improve physical understanding and quantitative assessment of the toughness behavior of hot-rolled pipeline steels, focusing on the lower part of the ductile to brittle transition temperature range.The impact toughness of these steels is commonly validated using drop weight tear tests (DWTT), on the basis of fracture surfaces that must exhibit less than 15% of brittle fracture appearance. In thermomechanical control processed steels, brittle out-of-plane cracks such as delamination (which propagates along the rolling plane), and brittle tilted fracture (BTF) along theta-planes (tilted around RD by 40° with respect to rolling plane), have been characterized in the ductile to brittle transition temperature range, for both industrial (DWTT) and laboratory Charpy impact tests. In both cases, as well as in fracture toughness tests, such brittle out-of-plane cracking has been shown to impair the impact toughness.The anisotropy in plastic flow and sensitivity to cleavage fracture has been characterized as a function of temperature, by using tensile tests on specifically designed smooth and notched specimens. From finite element mechanical analysis of these tests, critical cleavage stresses normal to the rolling plane and the theta-plane are considerably lower (around 25%) than for planes normal to the rolling and transverse directions.The anisotropy in critical cleavage stress has been quantitatively correlated to microtexture anisotropy. So-called “potential cleavage facets” have been defined and measured in this study, as regions with unfavorably oriented {100} planes, which are taken as unit crack paths for cleavage propagation. A sample containing 20% of potential cleavage facets had a critical cleavage stress 20% lower than a sample with only 10% of potential cleavage facets.The size and shape of these potential cleavage facets evolve during plastic deformation. Therefore, the critical cleavage stress was found to be affected by plastic strain history. In the case of delamination, potential cleavage facets along the rolling plane were elongated during loading, their area was increased and the corresponding critical cleavage stress decreased by around 30% with respect to the undeformed case. This made delamination cracking easier. Moreover, the presence of a ductile crack at the initiation site of delamination locally modified the stress state and also facilitated delamination occurrence. A criterion has been developed to numerically predict the onset of delamination in tensile and Charpy specimens.Application of this approach to heat-treated and to prestrained specimens eventually showed that it was possible to modify the sensitivity to delamination by strongly modifying the initial microtexture anisotropy.