An experimental investigation of a flush-wall, diamond-shaped injector was conducted in the Virginia Tech supersonic wind tunnel. The diamond injector was elongated in the streamwise direction and is aimed downstream angled up at 60° from the wall. Test conditions involved sonic injection of helium heated to approximately 313 K into a nominal Mach 4.0 crossstream airflow. These conditions are typical of a scramjet engine for a Mach 10 flight, and heated helium was used to safely simulate hydrogen fuel. The injector was tested at two different injectant conditions. First, it was investigated at a baseline mass flow rate of 3.4 g/s corresponding to an effective radius of 3.54 mm and a jet-to-freestream momentum flux ratio of 1.04. Second, a lower mass flow rate of 1.5 g/s corresponding to an effective ratio of 2.35 mm and a jet-to-freestream momentum flux ratio of 0.49 was studied. The diamond injector was tested both aligned with the freestream and at a 15° yaw angle for the baseline mass flow rate and aligned with the freestream at the lower mass flow rate. For comparison, round injectors angled up at 30° from the wall were also examined at both flow rates. A smaller round injector was used at the lower mass flow rate such that the jet-to-freestream momentum flux ratio was 1.75 for both cases. A concentration sampling probe and gas analyzer were used to determine the local helium concentration, while Pitot, cone-static and total temperature probes were used to determine the flow properties. The results of the investigation can be summarized as follows. For the baseline case, the aligned diamond injector penetrated 44% higher into the crossflow than did the round injector. The addition of yaw angle increased the crossflow penetration to 53% higher than the round injector. The aligned diamond injector produced a 34% wider jet than the round injector, while the addition of yaw angle somewhat reduced this widening effect to 26% wider than the round injector. The aligned and yawed diamond injectors exhibited 10% and 15% lower mixing efficiency than the round injector, respectively. The total pressure loss parameter of the aligned diamond was 22% lower than the round injector, while the addition of yaw angle improved the total pressure loss parameter to 34% lower than the round injector. For the lower mass flow (and momentum flux ratio) case, the diamond injector demonstrated 52% higher penetration and a 39% wider plume than the round injector. The mixing efficiency was nearly identical between the two injectors with just a 4% lower mixing efficiency for the diamond injector. The total pressure loss parameter of the diamond injector was 32% lower than round injector. These results confirm the conclusions of earlier, lower free stream Mach number and higher molecular weight injectant, studies that a slender diamond injector provides significant benefits for crossflow penetration and lower total pressure losses. / Master of Science

The goal of this project was improve the fundamental understanding of the wood-resin interaction, by looking at the relationship between the resin wetting onto wood and the resulting penetration into wood lumens. Wetting was analyzed with the sessile drop method, which observed the initial contact angle and change in contact angle over 35s. Penetration was measured within each individual tracheid. The Lucas-Washburn equation analyzed the wetting and penetration by calculating the penetration and comparing it to the measured penetration. Wetting of four resins was compared on 3 species, to improve the understanding of adhesive wetting behavior. This study agreed with previous research, that the non-aqueous resin exhibited favorable wetting and presumably better penetration than aqueous resins, with exception of urea-formaldehyde. Wetting and penetration of pMDI was studied on 5 wood species using the Lucas-Washburn equation. The wetting behaviors exhibited grain and species effects, which had implications on the resin availability for flake/strand-based composite products. The greater surface energy of loblolly pine most likely accounted for the significantly greater penetration of loblolly pine compared to Douglas-fir. The calculated penetration, via the Lucas-Washburn equation, exceeded the measured penetration, but it was concluded that the Lucas-Washburn equation predicted penetration reasonably well. Wetting and penetration of phenol-formaldehyde and subsequent adhesives was compared on 3 wood species using the Lucas-Washburn equation. All contact angles were unfavorable due to a skin formation. The Lucas-Washburn equation did not predict any penetration; however, penetration was observed with all systems. The findings suggest that the system was too complex for the Lucas-Washburn equation to be able to predict accurately. / Master of Science / Although the wood-based composites industry has been in operation for over a century, fundamental aspects of the wood/resin interaction- what happens when the liquid resin touches wood- remain poorly understood. An important aspect of this wood/resin interaction is penetration, which is critical to the strength and durability of wood-based composites. The two types of resins used, oil-based and water-based, were observed on a variety of wood species, Douglas-fir, loblolly pine, spotted gum, European beech and yellow-poplar. When using the oil-based resin, penetration measurements were in reasonable agreement with theoretical predictions. However, when using the water-based resins, the theory predicted no penetration which contradicted measurements- a shallow penetration was clearly observed. This means that parameters modeled by theory were in error, and this is sensible because we expect water to transfer from resin into the dry wood. Consequently, controlling parameters such as resin viscosity, resin surface tension, and wood surface energy were changing. This contributes fundamental knowledge, providing a better understanding of a critical step in the manufacture of wood-based composites, the materials most North Americans use to build their homes.

Daylight penetration into a deep interior space can be achieved by using a light tube strategy. This research investigates how effective a room's ceiling cavity can be as a daylight transporting system. The design, therefore, tries to answer the question "What is the optimal geometry for a ceiling cavity and inlet aperture to bring deeper daylight penetration and achieve a higher illumination level, measured at the back of a room, than that achieved by a typical high window opening?" Corporate affiliate 3M assisted this project by providing a prismatic and highly specular surface to cover the underlying geometry of the ceiling cavity. A 16' deep room section with a high window opening on one side was constructed as a test cell. Inside, sensors were set up to allow light measurement at task level along the depth of the room. Light rays were deflected by the geometry of the ceiling cavity, through a number of internal reflections on the highly reflective film surface, to a diffuser at the back. The three most promising geometric designs from scaled model tests were selected, installed and tested for efficiency in the full-scale test cell. / Master of Science

Due to lack of soil sampling during a conventional cone penetration testing (CPT), it is necessary to classify soils based on recorded tip and sleeve friction and pore pressure (if available) values. However, currently available soil classification models are based on deterministic and judgemental determination of soil classification boundaries which do not address the uncertainties intristic to the problem. Moreover, size and quality of databases used in the development of these soil classification models are undocumented and thus questionable. Similar limitations do also exist in the development of SPT-CPT correlations which are widely used in SPT dominated design such as soil liquefaction triggering. To eliminate these discussed limitations, within the confines of this study it is attempted to present (1) a new probabilistic CPT- based soil classification methodology, and (2) new SPT-CPT correlations which address the uncertainties intrinsic to the problems. For these purposes, a database composed of 400 CPT/SPT boring data pairs was compiled. It is intended to develop probabilistic models, which will correlate CPT tip and sleeve friction values to actual soil classification and CPT tip resistance to SPT blow count N. The new set of correlations, model parameters of which estimated by implementing maximum likelihood methodology, presented herein are judged to represent a robust and defensible basis for (1) prediction of soil type based on CPT data and, (2) estimation of SPT-N value for given CPT data.

In recent impact and penetration mechanical tests, steel projectiles (AISI4340) were impacted into targets like concrete with striking velocities (1200 m/s to 1500 m/s). Results indicated a material removal from the nose of the projectile, phase changes of the projectile materials, a reduction in the length of the projectile, and a blunting of the nose shape. These observations cannot be explained by current theories and numerical integration code that are used to study impact and penetration mechanics. Thus, the objectives of the thesis research are to (a) formulate and characterize the mechanisms responsible for the material erosion of the impacting projectile and the mass loss from the nose region; and (b) to determine the physical properties of alloy steels that are important to penetration mechanics from ab initio methods. The results can be used to design new projectile materials that can provide the desired penetration characteristics. These objectives are accomplished by investigating two related problems. The first problem is to formulate simplified models that can explain the penetration mechanics. The new models include the varying cross-section nose, changes of yield stress behind the shock wave and high strain rate phase transitions. Nose erosion effects, and time-dependent penetration path can be determined by integrating ODEs. A cavity expansion theory model is used to obtain the target resistance that is responsible slowing and deforming the penetrating projectile. The second problem concerns the determination of the constitutive relations from ab initio methods. The equation of state (EOS) and magnetic moments for alloy steels are investigated by using a special quasirandom structure technique and ab initio methods. Specifically, EOS for an interstitial disordered alloy Fe1-x-yNixCy is developed. First, the EOS of iron and phase transition of iron are studied and validated. Second, Nickel is considered to investigate the substitutional disordered alloy Fe1-x-yNixCy. Third, Carbon is placed at an interstitial position in the substitutional disordered alloy. These investigations will form foundation for future work involving new projectile with steel nose and shank made of multifunctional structural energetic materials.

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No. of bitstreams: 2 Dissertação - Francielle Diemer - 2014.pdf: 13400647 bytes, checksum: f1a5d38d2e6c6298ee648ff2cf652ac3 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-08-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Get soil resistance is critical to making any geotechnical design with confidence, thus, laboratory tests are used to determine the strength and deformability of the ground in discrete points involved in the volume of soil mass. Due to heterogeneity of soil formation is that field trials are needed to supplement this determination and enrich the bank information. Field trials were able to identify and estimate the mechanical parameters of the soil, an adequate prediction of the behavior of retaining structures, excavation, foundation, floor sizing, etc., and determine the characteristics of the soil profile, and have was used to estimate the mass of strength parameters involved ground. In this sense a new tool for the characterization of the soil profile from dynamic penetration of a metal cone with variable energy (PANDA) has been studied to find a relationship with the strength parameters of a tropical soil obtained in a vertical slope of about 4, 0 m high, located in Alexânia - GO with sandy visual tactile characteristics. Therefore, we performed PANDA tests up to 4.0 meters and determining the moisture profile through a survey to auger up to 3.70 meters and laboratory characterization tests were performed, determining the strength parameters in natural moisture condition and flooded , deformation parameters and determination of soil water characteristic curve (CCSA). PANDA the results were compared with the laboratory tests for this ground and found a range of variation between them always considering the trials of natural moisture condition. With the results it was possible to see the influence of suction in the PANDA test. In terms of resistance parameters was possible to find a friction angle of the relationship with the penetration of energy (qd) for this soil. Overall the strength parameters showed the same trend as the qd values obtained by PANDA compared with respect to depth. Finally, with the results it is recommended to carry out further testing on different soil types in different humidity conditions to improve relations found and increase the database. / Obter a resistência do solo é fundamental para elaborar qualquer projeto geotécnico com confiança, sendo assim, ensaios de laboratório são usados para determinar a resistência e deformabilidade do solo, em pontos discretos no volume da massa de solo envolvido. Devido a heterogeneidade da formação do solo é que são necessários ensaios de campo para complementar essa determinação e enriquecer o banco de informações. Os ensaios de campo são capazes de identificar e estimar os parâmetros mecânicos do solo, para uma adequada previsão do comportamento de estruturas de contenção, escavações, fundações, dimensionamento de pavimentos, entre outros, além de determinar as características do perfil do solo, e têm sido utilizados para estimar parâmetros de resistência do maciço de solo envolvido. Nesse sentido uma nova ferramenta para caracterização do perfil do solo a partir de penetração dinâmica de um cone metálico com energia varíavel (PANDA) foi estudado para encontrar uma relação com os parâmetros de resistência de um solo tropical obtido em um talude vertical de aproximadamente 4,0 m de altura, localizado em Alexânia – GO, com características tatil visuais arenosas. Para tanto foram realizados ensaios de PANDA até 4,0 metros e determinação do perfil de umidade através de uma sondagem à trado até 3,70 metros e em laboratório foram realizados ensaios de caracterização, determinação dos parâmetros de resistência na condição de umidade natural e inundado, parâmetros de deformação e determinação da curva característica solo água (CCSA). Foram comparados os resultados do PANDA com os ensaios de laboratório para este solo e encontrou-se uma faixa de variação entre eles sempre considerando os ensaios da condição de umidade natural. Com os resultados encontrados foi possível ver a influência da sucção no ensaio PANDA. Em relação aos parâmetros de resistência foi possível encontrar uma relação do ângulo de atrito com a energia de penetração (qd) para este solo. No geral os parâmetros de resistência apresentaram a mesma tendência que os valores de qd obtidos pelo PANDA quando comparados em relação a profundidade. Por fim, com os resultados encontrados recomenda-se realizar mais ensaios com diferentes tipos de solo em diferentes condições de umidade para melhorar as relações encontradas e aumentar o banco de dados.

No description available.

Wind power generation influences on the quality of the power grid. Because wind velocity is consistently changing this change causes unstable wind power generation. Since more wind power is expected to be used in the future, it is crucial to study the influence of the wind penetration level on normalized-damping ratio and damped-resonant frequency. In this thesis three types of calculated data were used to analyze the effect of wind penetration level on the Texas power grid: the percentage of wind power generation in Texas, generator-unit trip damping coefficient, and damped-resonant frequency. The percentage of wind energy was calculated from wind data provided by the Electric Reliability Council of Texas. The damping coefficient and damped-resonant frequency values are the indicators of power system stability and were calculated from synchronized phase data from the Texas power grid. The synchronized phase measurements were collected from the University of Texas at Austin and the wind farm near the Mc-Donald observatory. The data analyzed in this paper were from September 2009 to February 2010. The wind data were correlated to the grid-stability indicators which allowed us to interpret the status of the power grid according to the wind penetration level. When the wind penetration level increased over 11 %, five generator trip events occurred with damping coefficient values ten times higher than those of the regular unit trips. Moreover, during those events, damped-resonant frequency values rose nearly four times higher than the frequency values of other events. The results of this study may lead us to the conclusion that simply increasing the capacity of wind power generation will cause the power system to become unstable, and this will result in low quality of electricity. Therefore, further study is needed to determine the optimum amount of wind power generation without causing instability in the power grid. / text

Hafnium and Zirconium based gate dielectrics are considered potential candidates to replace SiO2 or SiON as the gate dielectric in CMOS processing. Furthermore, the addition of nitrogen into this pseudo-binary alloy has been shown to improve their thermal stability, electrical properties, and reduce dopant penetration. Because CMOS processing requires high temperature anneals (up to 1050 °C), it is important to understand the diffusion properties of any metal associated with the gate dielectric in silicon at these temperatures. In addition, dopant penetration from the doped polysilicon gate into the Si channel at these temperatures must also be studied. Impurity outdiffusion (Hf, Zr) from the dielectric, or dopant (B, As, P) penetration through the dielectric into the channel region would likely result in deleterious effects upon the carrier mobility. In this dissertation extensive thermal stability studies of alternate gate dielectric candidates ZrSixOy and HfSixOy are presented. Dopant penetration studies from doped-polysilicon through HfSixOy and HfSixOyNz are also presented. Rutherford backscattering spectroscopy (RBS), heavy ion RBS (HI-RBS), x-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), and time of flight and dynamic secondary ion mass spectroscopy (ToF-SIMS, D-SIMS) methods were used to characterize these materials. The dopant diffusivity is calculated by modeling of the dopant profiles in the Si substrate. In this disseration is reported that Hf silicate films are more stable than Zr silicate films, from the metal interdiffusion point of view. On the other hand, dopant (B, As, and P) penetration is observed for HfSixOy films. However, the addition of nitrogen to the Hf - Si - O systems improves the dopant penetration properties of the resulting HfSixOyNz films.

The purpose of this study was to evaluate the effect of a final rinse of ethanol on depth of sealer penetration in teeth obturated with Gutta Percha (GP)/AH-Plus® (Dentsply, De Trey GmbH, Konstanz, Germany) or Resilon/Epiphany® SE™ (Pentron Clinical Technologies, LLC, Wallingford, CT). Extracted human anterior teeth (n= 32) were shaped to size 30, 0.06 taper using nickel-titanium rotary files and subjected to an identical irrigation protocol. Specimens were randomly divided into eight groups according to final irrigating solution (saline, 70%, 95%, or 100% ethanol) and obturation material (GP/AH-Plus® or Resilon/EpiphanyÒ SE™). A 2mm thick slice was obtained by sectioning each obturated root at 3mm and 5mm from the anatomic apex. Specimens were cleared and assessed using scanning electron microscopy (SEM). Sealer penetration was observed at different magnifications when using GP/AH Plus® across all final rinse concentrations. Among Resilon/Epiphany® SE™ groups, no sealer penetration was evident under SEM. Conclusions: 1) GP/AH-Plus® showed evidence of sealer penetration, however, Resilon/Epiphany® SE™ did not show evidence of sealer penetration at both the dentin and sealer interface. 2) A final rinse with any concentration of ethanol prior to obturation does not improve sealer penetration with GP/AH-Plus® groups. 3). Resilon/Epiphany® SE™ bond can be dislodged at either the interface of sealer and Resilon or dentin and Resilon.