This is a Master Thesis done at the Swedish Defence Research Agency with the purpose to design and investigate how different geometries of a compression surface integrated with an intake affects the performance such as distortion, boundary layer diversion, pressure recovery and deceleration of speed. The work was divided in two parts. In the first part, CFD calculations using the FOI developed Edge 4.1 code were made for the compression surfaces alone. In the second part the most promising design was integrated with an intake. Two more bumps with the intake were modelled and the three geometries were compared to the intake without bump. Surface flow, deceleration of Mach number, pressure recovery, mass flow, boundary layer diversion, lift and drag were the factors chosen to be examined, boundary layer diversion and pressure recovery being the two most vital.

Solder bump is used to connect organic substrate with chip to form Flip Chip package. Comparing to wire bond package, the path is reduced so the electrical performance is much better. Due to the environmental concern, eutectic bump is replaced by lead-free bump gradually. Meanwhile, since wafer technology is improved from 55 nm to 40 nm, the material for dielectric layers is also changed so the material for the package need to revised to meet the characteristic of wafer. Now the laser grooving is adopted before blade sawing to accommodate the brittleness of new 40nm wafer. Also, one extra polyimide is added in the wafer fabrication to reinforce the robustness of the circuit. The stress inside the lead-free bump can be reduced by optimizing the temperature of the reflow process and the speed of cooling. Different UBM structure is also reviewed to find out its affect on the strength of bump and low-K circuit so the failure mode of bump can be predicted. The selection of underfill need to be well considered so, the warpage of package can be reduced, the maximum protection of bump and low-K circuit can be achieved, and the process is easier to control. (The four underfills are reviewed) The reliability test is utilized to decide the best bump composition, the structure of UBM, the selection of underfills and the process parameter. By adding the laser grooving in the wafer sawing process, the chance of crack on die low-K layer is reduced during the reliability test. As for the UBM structure, the POU is better than RPI to reduce the crack of die low-K layer. The result is verified on the package with no underfill by Temperature cycle. Last, the matching of SnCu0.7 bump with SAC305 C4 pad has the best result. During the research, the variance of CTE for the core of substrate contributes less warpage of package, comparing to the difference of Tg for underfills. The adhesion of underfills varies and the underfill UA9 has the best result. The flip chip package with underfill UA9 can passes TCB1000. The optimization of UBM structure for lead-free bump is researched and discussed. Composition of the lead-free bump, process parameter, and cost, those factors are also studied.

<p>This is a Master Thesis done at the Swedish Defence Research Agency with the purpose to design and investigate how different geometries of a compression surface integrated with an intake affects the performance such as distortion, boundary layer diversion, pressure recovery and deceleration of speed.</p><p>The work was divided in two parts. In the first part, CFD calculations using the FOI developed Edge 4.1 code were made for the compression surfaces alone. In the second part the most promising design was integrated with an intake. Two more bumps with the intake were modelled and the three geometries were compared to the intake without bump. Surface flow, deceleration of Mach number, pressure recovery, mass flow, boundary layer diversion, lift and drag were the factors chosen to be examined, boundary layer diversion and pressure recovery being the two most vital.</p>

Acetylcholinesterase (AChE) terminates cholinergic neurotransmission by catalyzing the hydrolysis of the neurotransmitter acetylcholine (ACh). Inhibition of AChE has proven an effective treatment for the memory loss exhibited by early stage Alzheimer's disease (AD) patients; four AChE inhibitors (AChEI) have been approved by the FDA for this purpose. The first AChEI approved for the palliative treatment of AD-related memory loss was 9-amino-1,2,3,4-tetrahydroacridine (tacrine). Inhibition of AChE may present either therapeutic or toxic effects depending upon the dose administered. With the goal of discovering safe and effective pesticides to control the population of Anopheles gambiae, a malaria-transmitting mosquito indigenous to Sub-Saharan Africa, the reoptimization of the tacrine pharmacophore was undertaken. Because the optimized drug would necessarily be a poor inhibitor for human AChE (hAChE), initial ligand design focused on modification to tacrine known to negatively impact the inhibition potency for hAChE. Ultimately, an AChEI was discovered, which exhibited micromolar inhibition of Anopheles gambiae AChE (AgAChE) and essentially no potency for hAChE. Two units of this lead compound were tethered through an alkyl chain to yield a nanomolar inhibitor of AgAChE that was more than 1,100-fold selective for the mosquito enzyme over hAChE. Dimerization of an active inhibitor is an effective strategy to increase the potency and selectivity of AChEI, and many examples of tacrine hetero- and homodimers complexed to AChE can be found in the RCSB Protein Data Bank (PDB). The bond formed between the exocyclic amine moiety and the heterocyclic ring system of tacrine is analogous to an amide bond when tacrine is protonated. Therefore, the rotational profile of protonated N-alkyltacrine should exhibit a conformational profile in which dihedral angles significantly out of the plane formed by the ring system are associated with high energies relative to those when the dihedral angles are nearly coplanar with the ring system. The barrier of rotation (ΔG^‡) produced by this phenomenon in two tacrine derivatives and two quinoline derivatives was experimentally determined using dynamic 1H NMR. These values were compared to density functional theory (DFT) derived values for the same phenomenon. Furthermore, since the ΔG^‡ proved to be impossible to experimentally determine for the optimal model compound for the active site portion of tacrine dimers, N-methyltacrine, the DFT method employed for modeling the ΔG^‡ of the tacrine and quinoline analogs was used to computationally derive the entire rotational conformation diagram of N-methyltacrine. The calculated values were then used to comment on the relative energies of adopting certain conformations found in the X-ray crystal structures of dimer/AChE complexes. / Ph. D.

Speed bump energy harvester, which aims to harvest energy from the passing by vehicles by absorbing their kinetic and potential energy, is designed, fabricated, simulated, and tested in this research. The proposed design is analyzed with a theoretical modelling which has then been validated with a ground test. Result reveals that the prototype has been able to produce up to 600 watts of peak power and around 150 watts of RMS power which is significant number. Further analysis has been done which theoretically suggests that the numbers could be increased up to 1 KW by optimizing the speed bump design and varying the system parameters such as electrical damping, mechanical damping, velocity and weight of the vehicles. Overall, system is able to increase the overall energy density by using Mechanical Motion Rectification (MMR) technology which would allow the increase in the power generation almost by double. Furthermore, different vehicle models have been used to analyze the effectiveness and accuracy of the harvester and also, the effect of harvester on the dynamics of the vehicle has been studied and analyzed in detail. / Master of Science

Three-dimensional (3D) turbulent boundary layers (TBLs) are ubiquitous in most engineering applications, but most turbulence models used to simulate these flows are built on two-dimensional turbulence theory, limiting the accuracy of simulation results. To improve the accuracy of turbulence modeling capabilities, a better understanding of 3DTBL physics is required. This dissertation outlines the experimental investigation of the attached 3D TBL flow over the Benchmark Validation Experiments for RANS/LES Investigations (BeVERLI) Hill using laser Doppler velocimetry in the Virginia Tech Stability Wind Tunnel. The mean flow and turbulence behavior of the boundary layer are studied and compared with turbulence theories to identify the validity of these assumptions in the BeVERLI Hill flow. It is shown that the pressure gradients and curvature of the hill have a significant effect on the turbulence behavior, including significant history effects at all stations due to the changing pressure gradient impact through the height of the boundary layer. Supplementing the experimental results with analysis from rapid distortion theory and simulations, it is shown that the stations lower on the hill are significantly affected by the non-linear history effects due to the varying upstream origins of the flow passing through those stations. Stations closer to the hill apex pass through a region of extremely strong favorable pressure gradient and hill constriction, resulting in behavior that matches qualitatively with the results from rapid distortion theory and provides insights into the physical mechanisms taking place in these regions of the flow. Despite the misalignment of the mean flow angle (γ_FGA) and turbulent shear stress angle (γ_SSA) throughout all of the profiles, the proposed 3D law of the wall of van den Berg (1975), which incorporates pressure gradient and inertial effects and relies on the assumption that γ_FGA=γ_SSA, is able to predict the flow behavior at more mildly non-equilibrium stations. This suggests that models that currently rely on assumptions founded on the two-dimensional law of the wall could be improved by incorporating van den Berg's model instead. The total shear stress distribution at selected stations on the BeVERLI Hill are all significantly reduced below equilibrium two-dimensional (2D) levels, indicating that turbulence models built on this assumptions will not be able to accurately simulate the 3D turbulence behavior. / Doctor of Philosophy / As an object moves through a fluid or a fluid moves past an obstacle, fluid sticks to the solid boundary of the object because of the fluid's viscosity, resulting in zero velocity on the surface (known as the "no-slip" condition). There then exists a region where the flow velocity increases from zero to the freestream velocity - this region is known as the boundary layer. The nature of the boundary layer developing around a body significantly influences how the body and fluid interact and is critical to practical items of engineering interest, such as estimating how much drag a vehicle will experience. Most bodies of engineering interest are three-dimensional (3D), like an aircraft or a car, and thus induce a three-dimensional boundary layer, but many turbulence theories used in computational fluid dynamics simulations are based on simplified two-dimensional (2D) flow behavior studied in laboratories. To further improve the accuracy of simulations, a better understanding of three-dimensional turbulent boundary layer flows is required. This dissertation outlines a study of three-dimensional turbulent flows by analyzing the three-dimensional turbulent boundary layer over the Benchmark Validation Experiments for RANS/LES Investigations (BeVERLI) Hill using laser Doppler velocimetry (LDV) in the Virginia Tech Stability Wind Tunnel. LDV uses the Doppler shift principle to measure the fluid velocity and turbulence at different points in the flow. Through analysis of the fluid velocity and turbulence in the flow, it is shown that the turbulence and flow behavior at certain stations are heavily influenced on the upstream flow history. Stations closer to the bottom of the hill are more influenced by the upstream flow history, while stations closer to the top of the hill experience such strong acceleration due to the local favorable pressure gradient and hill curvature that the upstream history has a more linear influence. In general, the turbulence on the hill is reduced due to the acceleration over the surface below 2D levels and does not match with the 2D fundamental relationships often used in turbulence theories for simulations. Thus, simulations that rely on these assumptions will not be able to accurately predict the details of the 3D flow. A proposed 3D model for the mean velocity behavior by van den Berg (1975) will perform better in simulations than the typical 2D law used in some turbulence model assumptions.

Computational fluid dynamics (CFD) methods and schemes have been evolving at a rate that significantly outpaces the equipment needed to readily utilize them at scale. This lack of computational resources has resulted in an increased reliance on turbulence models and the need to know where turbulence models do well, where they do poorly, and where/how they can be improved upon. The BeVERLI Hill experiments aim to address this issue by providing experimental data that achieves a completeness level of three, which has never been done for this type of project. The experimental data collected is studied along side computational results from CFD solvers in order to help address and answer these questions. This paper provides an overview of the current computational status of the BeVERLI Hill project at Virginia Tech. The computational grids used for the analyses are presented such that the reader can gain an appreciation for the modeling techniques and methods being implemented. An analysis of the numerical error associated with the computational results is presented to provide confidence in the results obtained. An in-depth analysis will be presented that shows the results for the various grid levels that are being utilized to determine any grid based effects that are occurring within the solutions. Then, an analysis of the influence of the Reynolds numbers being run is shown. An investigation into the differences between the two different solvers being utilized, SENSEI and Fluent, is shown. An analysis of the effects on the solutions due to numerical limiters is presented to assist in increasing the computational efficiency of the workflow while not adversely affecting the results. Finally, an analysis of the differences between the two turbulence models being utilized is presented. Computational results are compared to available experimentally obtained data to further motivate and identify flow features. / Master of Science / An analysis has been done with high-fidelity computational fluid dynamic solvers that are utilized in order to solve for the flow over a three-dimensional bump called BeVERLI. An analysis is provided that discusses the use of different computational meshes, solvers, turbulence models, and numerical limiters within the computational tools to characterize the flow over the bump. An analysis of the estimated amount of numerical error within the solutions is provided along with a comparison to experimentally obtained data.

Microelectronics integration continuously follows the trend of miniaturisation for which the technologies enabling fine pitch interconnection are in high demand. The recent advancement in the assembly of Hybrid Pixel Detectors, a high resolution detecting and imaging device, is an example of where novel materials and processes can be applied for ultra-fine pitch interconnections. For this application, indium is often used for the fine pitch bump bonding process due to its unique properties that make it especially suitable, in particular in a cryogenic environment where some types of detector have to serve. Indium bumps are typically fabricated through vacuum evaporation at the wafer level; however, this thesis investigates an alternative low cost manufacturing process at the wafer scale for the deposition of indium micro-bumps through electroplating. The work has placed its emphasis on the requirements of future technologies which will enable a low temperature (<150oC), high density interconnection (> 40,000 IOs/cm2) with a high throughput and high production yield. This research is a systematic investigation of the wafer-scale indium bumping process through electrodeposition using indium sulphamate solution. An intensive experimental study of micro-bump formation has been carried out to elaborate the effects of two of the main electroplating factors that can significantly influence the quality of bumps in the course of electrodeposition, namely the current distribution and mass transport. To adjust the current density distribution, various waveforms of current input, including direct current (DC), unipolar pulse current and bipolar pulse reverse current, were employed in the experiments. To assist mass transportation prior to or during electroplating, acoustic agitation including ultrasonic agitation at 30 kHz frequency as well as megasonic agitation at 1 MHz, were utilised. The electrochemical properties of the indium sulphamate solution were first investigated using non-patterned plain substrates prior to indium bumping trials. This provided understanding of the microstructural characteristics of indium deposits produced by electroplating and, through cathodic polarisation measurements, the highest current density suitable for electrodeposition was achieved as approximately 30 mA/cm2 when electroplating was carried out at room temperature and with no agitation applied. The typical surface morphology of DC electroplated indium contained a granular structure with a surface feature size as large as 10 µm. Pulse and pulse reverse electroplating significantly altered the surface morphology of the deposits and the surface became much smoother. By introducing acoustic agitation, the current density range suitable for electrodeposition could be significantly expanded due to the greater mass transfer, which led to a higher speed of deposition with high current efficiency. Wafer-scale indium bumping (15 µm to 25 µm diameter) at a minimum pitch size of 25 µm was successfully developed through electroplating trials with 3 inch test wafers and subsequently applied onto the standard 4 inch wafers. The results demonstrate the capability of electroplating to generate high quality indium bumps with ultrafine pitch at a high consistency and yield. To maximise the yield, pre-wetting of the ultrafine pitch photoresist patterns by both ultrasonic or megasonic agitation is essential leading to a bumping yield up to 99.9% on the wafer scale. The bump profiles and their uniformity at both the wafer and pattern scale were measured and the effects of electrodeposition regimes on the bump formation evaluated. The bump uniformity and microstructure at the feature scale were also investigated by cross-sectioning the electroplated bumps from different locations on the wafers. The growth mechanism of indium bumps were proposed on the basis of experimental observation. It was found that the use of a conductive current thief ring can homogenise the directional bump uniformity when the electrical contact is made asymmetrically, and improve the overall uniformity when the electrical contact is made symmetrically around the periphery of the wafer. Both unipolar pulse electroplating and bipolar pulse reverse electroplating improved the uniformity of the bump height at the wafer scale and pattern scale, and the feature scale uniformity could be significantly improved by pulse reverse electroplating. The best uniformity of 13.6% for a 4 inch wafer was achieved by using pulse reverse electroplating. The effect of ultrasonic agitation on the process was examined, but found to cause damage to the photoresist patterns if used for extended periods and therefore not suitable for use throughout indium bumping. Megasonic agitation enabled high speed bumping without sacrifice of current efficiency and with little damage to the photoresist patterns. However, megasonic agitation tended to degrade some aspects of wafer scale uniformity and should therefore be properly coupled with other electroplating parameters to assist the electroplating process.

Airport pavements and longitudinal elevation profiles, in conjunction with the aircraft, form a system where vertical displacements are produced that can compromise their performance. Rough pavements are generally responsible for the occurrence of dynamic responses such as vertical accelerations and pavement loads that affect the aircraft, increase stopping distance and difficult to read the cockpit instrumentation. To approach this problem, the International Roughness Index (IRI) and the Boeing Bump Index (BBI) are currently used to quantify airport pavement roughness and to identify sections that need maintenance and rehabilitation (M&R) activities. However, such indices were developed only based on the dynamic responses of an automobile at 80 km/h to the irregularities of road pavements, and from the physical characteristics of the irregularities, respectively, without considering the effect of the aircraft dynamic response. In addition, current critical limits for IRI and BBI can misjudge the real condition of the pavement. This research aims to evaluate the effect of airport pavement roughness on aircraft dynamic response in terms of vertical accelerations at the aircraft cockpit (VACP) and at the center of gravity (VACG), as well of dynamic loads at the nose, main and rear landing gear (NGPL, MGPL, and RGPL), which may compromise the aircraft safety and the pavement performance. The ProFAA software was used to compute both indices and to simulate the responses of 4 representative aircraft traversing 20 runway profiles at 10 operational speeds varying from 20 to 200 knots (37 to 370 km/h). Statistical comparisons and regression analyses between roughness indices and dynamic responses were carried out. Principal results indicated that VACP was 50% higher than VACG and that NGPL was approximately 80% higher than MGPL. In addition, it was observed that VACP exceeds 0.40 g when the IRI is higher than 3.7 m/km and that NGPL doubles the static load when the IRI is higher than 3.3 m/km. A case study presented to compare these limits shown that decision-making based on the dynamic response of the aircraft can bring significant differences in the number and quality of M&R activities. / Os pavimentos aeroportuários e os perfis de elevação longitudinal, em conjunto com as aeronaves, formam um sistema onde são produzidos deslocamentos verticais que podem comprometer seu desempenho. Pavimentos irregulares são geralmente responsáveis pela ocorrência de respostas dinâmicas como acelerações verticais e carregamentos no pavimento que podem danificar a aeronave, aumentar a distância de parada e dificultar a leitura dos instrumentos de navegação na cabine dos pilotos. Para abordar esse problema, os índices International Roughness Index (IRI) e Boeing Bump Index (BBI) são utilizados atualmente para quantificar a irregularidade longitudinal dos pavimentos aeroportuários e identificar seções que demandem atividades de manutenção e reabilitação (M&R). No entanto, tais índices foram desenvolvidos apenas com base nas respostas dinâmicas de um automóvel a 80 km/h às irregularidades dos pavimentos rodoviários e a partir das características físicas das irregularidades, respectivamente, sem considerar o efeito da resposta dinâmica das aeronaves. Ainda, os limites críticos atuais para IRI e BBI podem subestimar a condição real do pavimento. Esta pesquisa objetiva avaliar o efeito da irregularidade longitudinal na resposta dinâmica das aeronaves em termos de acelerações verticais na cabine dos pilotos (VACP) e no centro de gravidade (VACG) assim como os carregamentos no trem de pouso de nariz, principal e traseiro (NGPL, MGPL e RGPL, respectivamente), que podem comprometer a segurança das aeronaves e o desempenho do pavimento. O software ProFAA foi utilizado para calcular os dois índices e para simular as respostas de 4 aeronaves representativas operando 20 pistas de pouso e decolagem em 10 velocidades de operação variando de 20 a 200 nós (37 a 370 km/h). Comparações estatísticas e análises de regressão entre índices e respostas dinâmicas foram realizadas. Os principais resultados indicaram que VACP foi 50% maior do que VACG e que NGPL foi aproximadamente 80% maior do que MGPL. Além disso, observou-se que VACP ultrapassa 0,40 g quando o IRI está acima de 3,7 m/km e que NGPL dobra a carga estática quando o IRI está acima de 3,3 m/km. Um estudo de caso apresentado para comparar esses limites indicou que a tomada de decisão baseada na resposta dinâmica das aeronaves pode trazer diferenças significativas na quantidade e qualidade das atividades de M&R.

Submitted by ANA KARLA PEREIRA RODRIGUES (anakarla_@hotmail.com) on 2017-08-14T11:52:04Z No. of bitstreams: 1 arquivototal.pdf: 1035035 bytes, checksum: 24db9b859fa0c32ac6b5b442ef6e12fa (MD5) / Made available in DSpace on 2017-08-14T11:52:04Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1035035 bytes, checksum: 24db9b859fa0c32ac6b5b442ef6e12fa (MD5) Previous issue date: 2016-11-28 / In this work we study the existence of multi-bump solutions to a certain class of elliptic problems involving biharmonic problems. Moreover, we apply the method developed to biharmonic for study the existence of multi-bump solutions to Choquard Equation. / Neste trabalho estudamos a existência de soluções multi-bump para uma determinada classe de problemas elípticos que envolvem o operador Biharmônico. Além disso, aplicamos o método desenvolvido para o biharmônico no estudo da existência de solução multi-bump para equação de Choquard.