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An investigation of tunnel-soil-pile interaction in cohesive soils /Mattar, Joe. January 2007 (has links)
No description available.
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Toward decreasing the risk of carpal tunnel syndrome in video display terminal users through feedback.Blake, Kathleen E. 01 January 1991 (has links) (PDF)
No description available.
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Comparison of Magnetic Resonance Imaging & Sonography in an Animal Model in the Acute Stages of Carpal Tunnel SyndromeLarry, Fout Tyler 09 August 2013 (has links)
No description available.
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Grundvatteninläckage till Citybanan : En studie av prediktioner, tillstånd och verkligt utfallKourinnoi, Bogdan January 2017 (has links)
År 2008 inleddes bygget av den 6 kilometer långa tunneln Citybanan som sträcker sig genom stora delar av centrala Stockholm. Tunneln utgörs till största del av bergtunnlar men även av betongtunnlar på ett antal kortare sträckor. Syftet med tunneln är att avlasta spårtrafiken i Stockholm genom att fördubbla spårkapaciteten. Hela pendeltågstrafiken kommer omdirigeras till tunneln och de två nya pendeltågsstationerna Stockholm City och Odenplan kommer att byggas. Svårigheterna med tunnelbyggandet beror på det grundvatteninläckage som sker till bergtunneln genom bergets sprickor och svaghetszoner. Ett högt inläckage kan leda till att grundvattennivån sänks och jordlager ovanför tunneln krymper. Det kan leda till förändringar i den ovanliggande stadsmiljön och kostsamma sättningsskador. På grund av Stockholms geologiska heterogenitet och befintliga konstruktioner krävs försiktighet och korrekta åtgärder för att minimera de kostsamma konsekvenserna. För att minimera sättningarna har Trafikverket, som har huvudansvaret för Citybanan, utfört prediktioner av inläckaget till de olika delsträckorna i tunneln. Prediktionerna är baserade på undersökningar om den geologiska strukturen och antaganden om vilka tätningsåtgärder som ska utföras. Därefter har Miljödomstolen bestämt vilka värden som beviljats för de olika sträckorna som Trafikverket måste anpassa sig efter. För att sammanställa prediktionerna, de begränsande värdena och det verkliga inläckaget har data hämtats från utredningsdokument utförda på beställning av Trafikverket, miljödomar och Trafikverkets mätdatabas för omgivningspåverkan (TMO). Inläckaget har överskridit de tillåtna gränsvärdena till de två arbetstunnlarna Torsgatan och Norra station. Arbetstunnlarna ligger i närheten av sättningskänsliga områden, där framförallt området kring Stockholm City, till följd av inläckaget kan ha fått en förhöjd risk. Till de andra delsträckorna har inläckaget varit lägre än de högsta tillåtna värdena. Inläckaget har på fem sträckor överskridit de initiala prediktionerna. Miljödomarnas gränsvärden har, på alla delsträckor utom en, fastställts högre än prediktionerna. På grund av Stockholmsområdets geologiska komplexitet och de sättningskänsliga områdena bör det sättas ifråga om de tillåtna värdena bör sättas lägre för att stimulera Trafikverket att minimera inläckaget och således grundvattenpåverkan. / Construction of the 6 kilometres long tunnel Citybanan was initiated in 2008 by The Swedish Transport Administration. The majority of the tunnel consists of rock tunnels, but some shorter parts are concrete tunnels. The main purpose of the tunnel is to double the rail traffic capacity of central Stockholm and absorb commuter traffic. In addition to this, two new commuter train stations have been constructed. Cracks and weak zones within the rock is a challenge that can result in issues such as groundwater leakage. High groundwater leakage can cause the surrounding groundwater levels to sink which can lead to soil compaction around the tunnel. Soil compaction can cause land subsidence and further on damage buildings and existing infrastructure. Due to the heterogenic geology in Stockholm, and the vast amount of existing structures, specific actions have to be taken to minimize the risk of unwanted effects. Predictions has been done by The Swedish Transport Administration regarding the groundwater leakage in the different parts of the tunnel. The predictions are based on the geological structure and the planned amount of made grouting operations. Later, the Environmental court decided the allowed amount of groundwater leakage in the different sections. The predictions, permissions and actual inleakage presentet in this report have been retrieved from the Environmental Impact Assessment, the court verdicts and the Transports Administration database for environmental impact (TMO). The inleakage has exceeded the allowed amount into the two work tunnels Torsgatan and Norra station. These sections are located near sensitive areas, which can lead to an increased risk of subsidence damage. In total, the leakage has exceeded the predicted values in five different sections. The allowed inleakage is higher than the predicted inleakage at all sections except for one. Due to the complex geology and the risk of subsidence in central Stockholm, this report questions whether the allowed leakage should have been as high as they were. Lowering the level of accepted leakage could potentially stimulate the Transport Administration to minimize the leakage and thus the undesirable side effects.
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Spatial Variability of shotcrete thicknessKlaube, Maximilian January 2018 (has links)
An important task during the construction process is to validate the dimensions and properties of a given structure. The dimensions like for instance the thickness of a construction element should be measured after finishing building it. The aim is to compare the measured value with the design value to avoid that elements do not correspond to the input requirements. Moreover, the measurements are helpful to analyse the statistical distribution of the investigated geometrical property by computing e.g. a histogram, which visualises the dispersion and enable the calculation of the probability of failure for a specific structure or element.In this work, a shotcrete layer has been analysed in order to provide information about the homogeneity of the shotcrete thickness in a pre-determined tunnel section. The calculation method is based on two laser scans, before and after applying the shotcrete. Due to the construction process, the shotcrete layer will not be totally equal, which might be a safety problem. Especially, when the shotcrete layer is thinner than required and hence, the actual variation of the shotcrete must be considered and verified.To determine the statistical distribution, correlograms and histograms have been computed for a wall area in a tunnel in Southern Sweden. The correlogram shows the distance where the values have a correlation to each other and usually this distance is called scale of fluctuation. For the wall section, this scale of fluctuation has been calculated for the length (0.8m) as well as the height (0.8m). Compared to the original sample distance, e.g. distance of the rock bolts, the variance for the calculation of the probability of failure might be reduced.
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Active Control of Separated Flow over a Circular-Arc AirfoilMiranda, Sergio 14 August 2000 (has links)
An experimental study of active control of fully separated flow over a symmetrical circular-arc airfoil at high angles of attack was performed. The experiments were carried out in a low-speed, open circuit wind tunnel. Angles of attack from 10 to 40 degrees were tested. Low-power input, unsteady excitation was applied to the leading or trailing edge shear layers. The actuation was provided by the periodic oscillation of a 4-percent-chord flap placed on the suction side of the airfoil and facing the sharp edge. Vortex-shedding frequencies were measured and harmonic combinations selected as the applied actuator frequencies.
Pressure measurements over the airfoil show that the control increased the normal force coefficient by up to 70%. This supports the idea of vortex capture in the time-averaged sense, enhancing the lift on the airfoil by managing the shear layer roll up.
The results indicate the viability of the control of large-scale flow fields by exploiting the natural amplification of disturbances triggered by small-scale actuators.
The application of flow control on sharp-edged aircraft wings could lead to improved maneuverability, innovative flight control and weight reduction. These can be achieved by inexpensive, low-power, rugged actuators. / Master of Science
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EXTERNAL COMPRESSION AND PARTIAL ISCHEMIA ALTER FLEXOR TENDON AND SUBSYNOVIAL CONNECTIVE TISSUE MOTIONTse, Calvin TF 18 November 2016 (has links)
Carpal tunnel syndrome (CTS) is a peripheral median neuropathy that is commonly characterized by thickening and fibrosis of the subsynovial connective tissue (SSCT) surrounding finger flexor tendons. The degenerative process affecting SSCT can be initiated with excessive relative motion between the tendon and SSCT that ruptures interconnecting collagen. We used colour Doppler ultrasound to evaluate flexor digitorum superficialis tendon motion at two movement speeds with palmar compression, forearm compression, and partial ischemia (via brachial blood pressure cuff). Partial ischemia decreased SSCT displacement (22.9 ± 3.3 mm vs. 22.0 ± 3.3 mm; p = 0.015) while tendon displacement did not change. There was also a trend for increased relative tendon-SSCT displacement and shear strain index (SSI – relative displacement normalized to tendon displacement), which suggested partial ischemia might increase the strain in collagen that connects tendon and SSCT. Forearm compression decreased tendon displacement (28.5 ± 4.1 mm vs. 27.0 ± 4.6 mm; p = 0.043) while SSCT displacement also trended to decrease (24.0 ± mm vs. 22.5 mm; p = 0.059). With a lack of change in relative tendon-SSCT displacement and SSI, maintaining flexion-extension range of motion may have meant that forearm compression strained the musculotendinous unit at a location where SSCT was uncompromised. Palmar compression did not significantly affect any dependent motion variables, which suggested palmar compressive forces likely do not affect tendon-SSCT shear injury risk. The fast movement speed increased relative tendon-SSCT displacement and SSI while decreasing mean velocity ratio (MVR), which suggested greater tendon-SSCT shear strain in all baseline and compression conditions. Previously, increased relative tendon-SSCT displacement with fast movement speed was only shown in cadaveric investigations, but we confirmed this effect is transferable in an in vivo model. We induced ischemia proximally and found a reduction in SSCT displacement at the distal carpal tunnel. This finding suggests that the vascular network integrated within SSCT may play a role in altering tendon-SSCT excursion, independent of other external mechanical factors previously shown to increase relative motion and potential shear injury risk. Overall, this thesis showed that external mechanical compression at the palm or forearm likely do not negatively affect relative tendon-SSCT motion and that local ischemia and carpal tunnel blood flow should be considered when evaluating tendon and SSCT motion in relation to CTS development and progression. / Thesis / Master of Science (MSc)
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Scaling techniques using CFD and wind tunnel measurements for use in aircraft designPettersson, Karl January 2006 (has links)
This thesis deals with the problems of scaling aerodynamic data from wind tunnel conditions to free flight. The main challenges when this scaling should be performed is how the model support, wall interference and the potentially lower Reynolds number in the wind tunnel should be corrected. Computational Fluid Dynamics (CFD) simulations have been performed on a modern transonic transport aircraft in order to reveal Reynolds number effects and how these should be scaled accurately. This investigation also examined how the European Transonic Wind tunnel (ETW) twin sting model support influences the flow over the aircraft. In order to further examine Reynolds number effects a MATLAB based code capable of extracting local boundary layer properties from structured and unstructured CFD calculations have been developed and validated against wind tunnel measurements. A general scaling methodology is presented. / QC 20101123
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Upgrading and Qualification of a Turbulent Heat Transfer Test FacilityOdetola, Olumide Folorunso 13 December 2002 (has links)
The Turbulent Heat Transfer Test Facility (THTTF) has been refurbished and the data acquisition system upgraded. The THTTF is now controlled by a LabView 4.1 program which replaces the old program in BASIC. Heat transfer data acquired using this new program is presented as Stanton number distributions. The new data set is compared to previously reported data obtained with this facility and other wellepted published data. This project has successfully qualified the THTTF for zero-pressure gradient, isothermal wall temperature, incompressible boundary-layer flow over smooth flat plates without transpiration. The THTTF is now set to accommodate modifications which will facilitate heat transfer investigations with high freestream turbulence.
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AMBIENT AND HIGH TEMPERATURE EROSION INVESTIGATION OF MATERIALS AND COATINGS USED IN TURBOMACHINERYDRENSKY, GEORGE KERILOV 11 June 2002 (has links)
No description available.
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