Universiẗat, Diss., 1999--Frankfurt (Main).

While many studies have been conducted in channels that are fully open or entirely covered with ice, little has been examined in channels with border ice. To begin filling in this gap in knowledge, experiments were conducted in the Hydraulics Research Testing Facility at the University of Manitoba in a 1.2m wide, 14m long flume to assess the impact of Froude number, coverage ratio and bed-to-ice roughness ratio on the hydraulic characteristics of channels with border ice cover. Acoustic Doppler velocimetry was used to collect detailed 3D velocity data over a cross section of the flume which facilitated the analysis of velocity and turbulence intensity fields as well as the shear stress distribution. The data collected thus far represents the most complete experimental dataset of measured water velocities in a channel with a border ice cover. / February 2016

abstract: Changes to the microenvironment of the endothelium can produce significant changes in the response of endothelial cells to stimuli. Human Aortic Endothelial Cells (HAECs) are tested in vitro for their fluid shear stress response when their substrates, and the solute concentrations of the fluids to which they are exposed, are modulated, and for their nitric oxide expression when they are exposed to hyperglycemic conditions. ImageJ is used to quantify either the degree of cellular alignment and elongation with the direction of flow, or the relative NO expression using the fluorochrome DAF-2. First, the results of Brower, et.al. are replicated: HAECs under normal glucose (4mM) conditions align and elongate with flow (p<<0.05), while high glucose (30.5mM) conditions negate this effect (p<<0.05) and is likely the result of Advanced Glycation End-products (AGEs). Then, in this study it is found that substitution of fibronectin for gelatin substrates does not impair flow (p<<0.05), indicating that fibronectin likely does not participate in the initiation of vascular lesions. High palmitic acid also does not prevent HAEC shear response (p<<0.05), which is consistent with Brower's predictions that AGEs are responsible for impaired elongation and alignment. NO production is significantly increased (p<<0.025) in HAECs cultured 24 hours under high glucose (30.5mM) conditions compared with normal glucose (4mM) conditions, indicating the presence of inducible nitric oxide as part of an inflammatory response. Aminoguanidine (5mM) added to high glucose concentrations reduces, but does not eliminate NO production (p<<0.05), likely due to insufficient concentration. Modulation of the endothelial microenvironment leads to pronounced changes in HAEC behavior with regards to NO production under hyperglycemic conditions. Diabetic model rat aortas are explanted and imaged for the purpose of detecting aortic endothelial cell alignment and elongation; improvements in this method are discussed. A microvessel chamber used with explanted human tissue is re-fit to reduce required volumes of solutions and allow more effective experimentation. / Dissertation/Thesis / M.S. Bioengineering 2013

Le contrôle de la sûreté des ouvrages hydrauliques est l’une des grandes priorité dans le domaine du génie civil et de l’ingénierie hydraulique. Durant sa vie, un ouvrage est soumis à des sollicitations variables hydromécaniques, physicochimiques et climatiques qui contribuent à son éventuelle détérioration. Parmi les phénomènes qui en résultent, l’érosion des sols sous toutes ses formes représente un enjeu majeur à comprendre, maîtriser et empêcher. L’objectif de ce travail est d’étudier l’érosion des sols par le Jet Erosion Test. La première partie est consacrée à la description des dispositifs expérimentaux, surtout le Jet Erosion Test (JET) développé à l’Ecole Centrale Paris permettant de mesurer directement quelques paramètres d’érosion. A partir des résultats du JET, à l’aide d’une loi d’érosion empirique, nous déduisons la contrainte de cisaillement critique, le coefficient d’érosion, la profondeur d’érosion d’équilibre. La deuxième partie du travail est consacrée à l’étude de l’influence des paramètres de compactage sur l’infiltration de l’eau et la résistance du sol, en utilisant le pénétromètre. Dans les troisième et quatrième parties, nous étudions l’influence des propriétés géotechniques du sol et celle des paramètres d’essai sur les paramètres d’érosion du sol. Les résultats obtenus montrent que les paramètres d’érosion sont influencés non seulement par les propriétés géotechniques du sol mais aussi par les paramètres d’essai. La dernière partie présente la synthèse entre les résultats des essais de pénétromètre et ceux des essai de JET, et tente de relier les paramètres d’érosion avec les propriétés géotechniques du sol. / Control of the safety of hydraulic structures is a major priority in the field of civil and hydraulic engineering. During its life, the hydraulic structure is submitted to variable hydromechanical, physicochemical and climatic loads that may contribute to its possible failure. Among the resulting phenomena, soil erosion under all its forms is a major challenge which it is important to understand, control and prevent. The objective of this work is to study soil erosion by the Jet Erosion Test. The first part is devoted to the description of the experimental devices, especially the Jet Erosion Test (JET) developed at the Ecole Centrale Paris to directly measure some erosion parameters. From the results of JET, using an empirical erosion law, we deduce the critical shear stress, the erosion coefficient, the equilibrium scour depth. The second part of this work is devoted to the study of the influence of compaction parameters on water infiltration and soil strength, using the penetrometer. In the third and fourth parts, we study the influence of the geotechnical properties of soil and of the test parameters on the erosion parameters of soil. The obtained results show that the erosion parameters are influenced not only by the geotechnical properties of soil but also by the test parameters. The final section presents a synthesis of the results of penetrometer tests and JET tests, and attempts to link the erosion parameters with the geotechnical properties of soil.

Differences in southern yellow pine (represented by Pinus taeda) and Douglas-fir (Pseudotsuga menziesii) mature and juvenile wood were examined in terms of density, chemical composition, surface energy, shear stress, % wood failure, and delamination. Density was measured using a QTRS density scanner. Loblolly pine contained a higher average density. Chemical composition was measured using the NREL standard for identifying the chemical composition of biomass. Southern yellow pine contained a higher % hemicellulose, lignin, and extractives. Douglas-fir had higher % cellulose than southern yellow pine. Surface energy was measured using the static sessile drop contact angle method and the acid/base approach. Southern yellow pine contained a lower average contact angle than Douglas-fir. Shear stress, % wood failure, and durability were measured using ASTM-D2559 with two adhesives, a one-part moisture cure polyurethane (PU), and a two-part ambient curing phenol-resorcinol-formaldehyde (PRF). Shear stress for southern yellow pine was affected the most by the type of growth regions at the bond (juvenile to mature wood) and the assembly times of the adhesives used. Douglas-fir shear stress was affected by the type of adhesive and the growth region at the bond. Delamination results demonstrated that when using PRF the southern yellow pine has less delamination statistically than Douglas-fir. Also, the growth region at the bond with both adhesives showed to impact delamination with juvenile to mature wood having less delamination than mature to mature wood. / Master of Science

This investigation concerns the design, build, and testing of a new class of skin friction sensor capable of performing favorably in high-speed, high-enthalpy flow conditions, such as that found in atmospheric re-entry vehicles, scramjets, jet engines, material testing, and industrial processes. Fully understanding and optimizing these complex flows requires an understanding of aerodynamic properties at high enthalpies, which, in turn, requires numerical and analytical modeling as well as reliable diagnostic instrumentation. Skin friction is a key quantity in assessing the overall flight and engine performance, and also plays an important role in identifying and correcting problem areas. The sensor design is founded on a direct-measuring, cantilever arrangement. The design incorporates two fundamental types of materials in regards to thermal conductivity and voltage resistivity properties. The non-conducting material distinction greatly deters the effect of heat soak and prevents EMI transmission throughout the sensor. Four custom fabricated metal-foil strain gauges are arranged in a Wheatstone bridge configuration to increase sensitivity and to provide further compensation for sensitivity effects. The sensor is actively cooled via a copper water channel to minimize the temperature gradient across the electronic systems. The design offers a unique immunity to many of the interfering influences found in complex, high-speed, high-enthalpy flows that would otherwise overshadow the desired wall shear measurement. The need to develop an encompassing design methodology was recognized and became a principal focus of this research effort. The sensor design was developed through a refined, multi-disciplinary approach. Concepts were matured through an extensive and iterative program of evolving key performance parameters. Extensive use of finite element analysis (FEA) was critical to the design and analysis of the sensor. A software package was developed to utilize the powerful advantage of FEA methods and optimization techniques over the traditional trial and error methods. Each sensor endured a thorough series of calibrations designed to systematically evaluate individual aspects of its functionality in static, dynamic, pressure, and thermal responses. Bench-test facilities at Virginia Tech (VT) and Air Force Research Laboratory (AFRL) further characterized the design vibrational effects and electromagnetic interference countermeasure effectiveness. Through iterations of past designs, sources of error have been identified, controlled, and minimized. The total uncertainty of the skin friction sensor measurement capability was determined to be ±8.7% at 95% confidence and remained fairly independent of each test facility. A rigorous, multi-step approach was developed to systematically test the skin friction sensor in various facilities, where flow enthalpy and run duration were progressively increased. Initial validation testing was conducted at the VT Hypersonic Tunnel. Testing at AFRL was first performed in the RC-19 facility under high-temperature, mixing flow conditions. Final testing was conducted under simulated scramjet flight conditions in the AFRL RC-18 facility. Performance of the skin friction sensors was thoroughly analyzed across all three facilities. The flow stagnation enthalpies upward of 1053 kJ/kg (453 Btu/lbm) were tested. A nominal Mach 2.0 to 3.0 flow speed range was studied and stagnation pressure ranged from 172 to 995 kPa (25 to 144 psia). Wall shear was measured between 94 and 750 Pa (1.96 and 15.7 psf). Multiple entries were conducted at each condition with good repeatability at ±5% variation. The sensor was also able to clearly indicate the transient flow conditions of a full scramjet combustion operability cycle to include shock train movement and backflow along the isolator wall. The measured experimental wall shear data demonstrated good agreement with simple, flat-plate analytical estimations and historic data (where available). Numerical CFD predictions of the scramjet flow path gave favorable results for steady cold and hot flow conditions, but had to be refined to handle the various fueling injection schemes with burning in the downstream combustor and surface roughness models. In comparing CFD wall shear predictions to the experimental measurements, in a few cases, the sensor measurement was adversely affected by shock and complex flow interaction. This made comparisons difficult for these cases. The sensor maintained full functionality under sustained high-enthalpy conditions. No degradation in performance was noted over the course of the tests. This dissertation research and development program has proven successful in advancing the development of a skin friction sensor for applications in high-speed, high-enthalpy flows. The sensor was systematically tested in relevant, high-fidelity laboratory environments to demonstrate its technology readiness and to successfully achieve a technology readiness level (TRL) 6 milestone. The instrumentation technology is currently being transitioned from laboratory development to the end users in the hypersonic test community. / Ph. D.

Indiana University-Purdue University Indianapolis (IUPUI) / Atherosclerosis is a chronic disease that happens mostly in aged people, and recently studies have showed many similarities between Hutchinson Gilford Progeria Syndrome (HGPS) cells and aging cells, implicating dysfunctions of lamin A/C in aging process and atherosclerosis, as HGPS is caused by a mutated form of lamin A/C. Blood flow in arteries is generating shear stress that is mostly applied on endothelial cells that align along inner blood vessel wall. At the same time, endothelial cells are also under stretch by periodic arterial pulses. Considering the fact that atherosclerosis is prone to developing at arterial branches with disturbed shear and increased stretch, it is highly possible that laminar flow and proper stretch force are regulating endothelium to function appropriately. In this thesis, the investigation of what effects laminar flow or cyclic stretch can bring to endothelial cells was conducted, and examination of lamin A/C expression under mechanical forces were elaborated and incorporated with cell senescence. Results showed that laminar shear stress and stretch force can regulate lamin A/C expression in different patterns, which were impaired in senescent cells.

Elevated eosinophil counts in the circulation and/or tissues is considered a clinical feature and biomarker of several chronic airway diseases including asthma. As such, many therapeutic biologics for asthma developed within the past decade target eosinophil recruitment to and accumulation in the airways to mixed success. Although the nature of adhesive interactions and directional migration of eosinophils has been well studied, there remains a lack of comprehensive understanding regarding the components which modulate eosinophil movement from the blood into respiratory tissues that impacts the efficacy of these clinical studies; therefore, continued research in this area may reveal novel therapeutic targets and ultimately improve clinical outcomes of patients with eosinophilia-mediated diseases. The Janssen lab serendipitously discovered that the mere perfusion of standard media without pharmacological additives over human eosinophils in vitro induced the release of intracellular calcium (Ca2+) reminiscent of chemokine-induced Ca2+ release well documented in the literature. The central focus of my doctoral research was to characterize this novel phenomenon of the perfusion-induced calcium response (PICR), and to determine its physiological role in the eosinophil extravasation process to inflamed tissue sites. In our first research objective, we optimized a protocol of eosinophil isolation directly from whole blood with emphases on maximizing population purity and yield efficiency while minimizing cell activation that could potentially interfere with secondary functional assays. For our latter two studies, we utilized real-time fluorescent confocal microscopy and immunofluorescence staining to investigate the PICR. We observed that the latency to the PICR post-perfusion was significantly shorter in eosinophils subjected to physiological rates of shear stress, suggesting a temporal-regulatory function of eosinophil mechanosensitivity. Furthermore, the disruption of the PICR via pharmacological inhibitors significantly reduced eosinophil motility by increasing the latency to cytoskeletal rearrangements (flattening onto substrate-coated surfaces, formation of membrane protrusions that explore the environment) necessary for cell migration out of the vasculature. Detailing the role of eosinophil sensitivity to the mechanical trigger of fluid shear stress expands upon the current paradigm of eosinophil recruitment and will contribute to the development of clinical strategies. / Dissertation / Candidate in Philosophy

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23573号 / 医博第4787号 / 新制||医||1054(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 中本 裕士, 教授 花川 隆, 教授 湊谷 謙司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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