Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, September 1990. / Thesis Advisor(s): Healey, J. Val. Second Reader: Schmidt, L. V. "September 1990." Description based on title screen as viewed on December 18, 2009. DTIC Descriptor(s): Velocity, Air Flow, Flight Decks, Shear Properties, Measurement, Position(Location), Ships, Models, Layers, Edges, Boundary Layer, Flow Visualization, Tunnels, Curvature, Smoke, Stationary, Bubbles, Patterns, Helium, Flow, Ship Models, Video Signals, Anemometers, Earth Atmosphere, Deflectors, Photographic Equipment. DTIC Identifier(s): Wake, Naval Vessels(Support), Turbulence, Helicopters, Atmospheric Motion, Air Flow, Ship Models, Replenishment at sea, AOR Class Vessels, H-56 Aircraft, Wind Direction, Oilers(Naval Vessels), Rotor Blates(Rotary Wings), Impact, Vertical Replenishment, Blade Strike, Theses, Wind Tunnel Models. Author(s) subject terms: Flow Visualization, Simulated Atmospheric Boundary Layer, Helium Bubble Flow Visualization, Smoke Visualization, AOR Class ship. Includes bibliographical references (p. 84-85). Also available in print.

Thesis (M. Phil.)--University of Hong Kong, 1987.

L’objectif de cette thèse est de présenter des critères simples pour l’évaluation des performances d’une ventilation transversale. On définit l’efficacité et le rendement, calculés à partir du flux de déficit de densité créé par l’incendie. Après une étude préliminaire permettant de caler les modèles numériques, l’influence de différents paramètres sur ces valeurs a été évaluée. Dans un premier temps, l’étude a porté sur une seule trappe et a montré que le courant d’air dans le tunnel est le paramètre le plus important. A l’inverse, la forme de la trappe pour une surface donnée n’a que très peu d’importance, sauf dans des cas limites (fente sur toute la largeur du tunnel). L’étude d’un canton à huit trappes confirme l’importance du contrôle du courant d’air. Lorsqu’on diminue le nombre de trappes en conservant la même surface totale d’aspiration, cette sensibilité tend à disparaître, mais l’efficacité diminue. Enfin, l’étude de l’influence de l’encombrement montre une légère amélioration de l’efficacité, due à l’obstruction d’une partie de la section par des camions, qui bloquent les fumées au droit des trappes. / The aim of this study is to present simple criteria to evaluate the performances of a transverse ventilation system. Efficiency and yield have been defined, based on the flux of density deficit createdby the fire. After a preliminary study of numerical models, the influence of different parameters on those criteria has been investigated. First, the study focused on the simplified case of a single damper. We showed that the air flow speed in the tunnel is the more important parameter. On the contrary, the shape of the damper has little influence on the efficency, except in unusual cases (slit on the whole width of the tunnel). Then, the study of a longer portion of the tunnel confirmed the prominence of the limitation of air flow speed. Comparison with a case with fewer dampers but the same total extraction section showed that this sensibility to air flow speed tends to disappear for larger dampers, but that the efficiency is lowered. Finally the study of the influence of heavy-goods-vehicules obstructing the tunnel reports better results, due to the fact that big objects tend to confine smokes.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

No description available.

Στην εργασία αυτή παρατίθενται τα τεχνικά - γεωλογικές συνθήκες για το άνοιγμα της σιδηροδρομικής σήραγγας της Τράπεζας, που έχει συνολικό μήκος 3.048,12 m. Η γεώτρηση πραγματοποιείται σε μεταλπικές ιζήματα των νεογενών και ιδιαίτερα σε πυκνή μάργες με τοπικές ενστρώσεις χαλαρά ομίλων . Λόγω της φύσης των υλικών ήταν αναγκαία η χρήση της κεφαλής - δοκών, το κεφάλι - άγκυρες και όλα τα προσωρινά μέσα συγκράτησης (πλαίσια), εκτοξευόμενο σκυρόδεμα, αγκύρια, mesh) και στα σημεία αυξημένης υδροφορέα έγινε χρήση μεμβρανών και συστηματικές οπές αποστράγγισης. Η έρευνα βρίσκεται στο σχηματισμό του κατώτερου ορίζοντα των νεογενών και ιδιαίτερα στους σχηματισμούς των marlstones - ιλυόλιθοι που παρουσιάζουν συμπεριφορά σκληρών εδαφών - μαλακών βράχων και φιλοξενούν το μεγαλύτερο τμήμα της σήραγγας . Πραγματοποιήθηκε μια συστηματική δειγματοληψία από τα μέτωπα εκσκαφής με τη μορφή δειγμάτων μεγάλων διαστάσεων ( δείγματα μπλοκ ), που μεταφέρθηκαν αμέσως στο εργαστήριο , όπου ο σχηματισμός τους πήραν θέση για τη δοκιμή χαλάρωσης , καθώς και τις δοκιμές του προσδιορισμού των οι φυσικές ιδιότητες . Στα δείγματα που σχηματίστηκαν , οι δοκιμές του προσδιορισμού των φυσικών παραμέτρων ελήφθησαν τόπο και ιδιαίτερα οι ακόλουθες δοκιμές πραγματοποιήθηκαν: δοκιμές της φυσικής υγρασίας, ο καθορισμός των ορίων συνέπειας (όρια Αtterberg), τον προσδιορισμό του ειδικού βάρους ενός υλικού λεπτότερο υλικό από 2mm, την ανάλυση των σωματιδίων με κόσκινα, καθώς και με ένα υδρόμετρο (μέθοδος Stokes του), ο προσδιορισμός της μονάδα βάρους συνεκτικών υλικών και, τέλος, τον προσδιορισμό του ποσοστού βράχου κρεμάει. / In this work they are listed the technical – geological conditions for the opening of the railway tunnel of the Trapeza that has a total length of 3048.12 m. The drilling takes place in post alpine sediments of the neogene and particularly in dense marls with local intercalations of loose conglomerates. Due to the nature of the materials it was necessary the use of head – beams, head – anchors and all temporary retaining means ( frames), sprayed concrete, anchors, mesh ) and in the points of increased aquifer it was made use of membranes and systematic drainage holes. The investigation is located in the formation of the lower horizon of the neogene and particularly in the formations of the marlstones – siltstones that present a behavior of hard soils – soft rocks and they host the biggest part of the tunnel. It took place a systematic sampling from the fronts of excavation with the form of samples of big dimensions ( block samples) that were transferred immediately to the laboratory, where their formation was taken place for the sag test as well as the tests of the determination of the physical properties. In the samples that were formed, tests of the determination of the physical parameters were taken place and particularly the following tests took place: tests of natural moisture, the determination of consistency limits ( Αtterberg limits ), the determination of the specific weight of a material of finer material than 2mm\, the particle analysis with sieves as well as with an hydrometer (Stokes’s method), the determination of unit weight of consistent materials and finally the determination of the rock sag rate.

Three dimensional laser scanning, also known as Light Detection and Ranging (LiDAR) has quickly been expanding in its applications in the field of geological engineering due to its ability to rapidly acquire highly accurate three dimensional positional data. Recently is has been shown that LiDAR scanning can be easily integrated into an excavation sequence in an underground environment for the purpose of collecting rockmass and discontinuity information. As scans are often taken multiple times of the same environment, the next logical application of LiDAR scanning is for monitoring for change and deformation. Traditionally, deformation and change in an underground environment is measured using a series of five or more permanent control points installed around the profile of an excavation. Using LiDAR for profile analysis provides many benefits as compared to traditional monitoring techniques. Due to the high density of the point cloud data, the change in profile is able to be fully characterized, and areas of anomalous movement can easily be separated from overall closure trends. Furthermore, monitoring with LiDAR does not require the permanent installation of control points, therefore monitoring can be completed more quickly after excavation, and scanning is non-invasive therefore no damage is done during the installation of temporary control points. The main drawback of using LiDAR scanning for deformation monitoring is that the raw point accuracy is generally the same magnitude as the smallest level of deformations that need to be measured. To overcome this, statistical techniques for profile analysis must be developed. This thesis outlines the development one such method, called the Elliptical Fit Analysis (EFA) and LiDAR Profile Analysis (EFA) for tunnel and shaft convergence analysis. Testing of the EFA and LPA has proved the robustness of this technique in its ability to deal with accuracy and precision issues associated with LiDAR scanning. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2012-05-15 13:24:28.398

No description available.

This thesis presents the work undertaken to assess potential improvements in high performance bicycles. There are several wheel options available for elite riders to use in competition and this research has investigated the aerodynamic properties of different wheel type. The research has also developed CFD and FEA models of carbon fibre bicycle wheels to assist in the wheel improvements process. An accurate and repeatable experimental test rig was developed to measure the aerodynamic properties of bicycle wheels in the wind tunnel, namely translational drag, rotational drag and side force. Both disk wheels and spoked wheels were tested. It was found that disk wheels of different hub widths have different aerodynamic properties with the 53mm wide Zen disk wheel requiring the lowest total power of the wheels tested. There was little difference between the translational power requirements of the wheels but there was greater variation in the rotational power requirements. Compression spoked wheels of 3 and 5 spokes were found to require less power than wire spoked wheels. There was little difference between the total power requirements of the compression spoked wheels tested, with the differences at 50km/hr being less than the experimental uncertainty. The Zipp 808 wheel demonstrated considerably lower axial force than all other wheels at 10° yaw angle, confirming Zipp design intention to have optimum wheel performance between 0-20°. The Zen 3-spoke wheel showed the lowest axial drag and side force at yaw of the compression spoked wheels tested and had similar side force results to the Zipp 808. CFD models of the disk and 3-spoke wheel achieved good agreement with the experimental results in terms of translational drag. Rotational drag did not agree so well, most likely due to the turbulence model being designed for higher Reynolds number flows. A FE model of the disk wheel was validated with experimental testing. In order to simplify modelling, the FE model of the 3-spoke wheel did not include the hub, which led to a large discrepancy with experimental results for the particular loading scenario. The experimental rig and CFD models were used to develop aerodynamic improvements to the wheel and the FE models were used to identify the implication of geometric changes to the wheel structural integrity. These improvements are not reported in this thesis due to the results being commercially sensitive.

Expertise is undoubtedly a feature of policy areas in contemporary societies; inputs of formal knowledge are important components of the policy process. The post- 1945 period, in Britain, has witnessed a proliferation and diversification in both the number and type of expert, and expert group used in policy areas. This situation poses both theoretical and empirical difficulties for any analysis of the role and influence of expert groups. The thesis focuses upon expert groups in the policy process, the nature and reasons for their influence, and the subsequent democratic and normative implications raised by such an analysis. The thesis makes an assessment of the various definitions of the expert, as well as a thorough examination of technocracy. Moreover, the nature of expertise is examined to demonstrate how expert influence may alter at different levels in the policy-making process. It is contended that complexity, and a corresponding requirement of legitimacy, are the primary reasons for the use of experts in policy areas. This analysis is placed in historical context since 1945, a period that has witnessed alterations in both the nature and type of expert and expert group, the level of demand for expertise, and the reasons for that demand, made by policy- makers for expert input. This theoretical and historical overview is utilised in the analysis of two diverse case studies of policy sub-sectors: the case of air pollution and asthma, and the siting of the route of the Channel Tunnel Rail Link. Although distinct in nature, it is shown that within both of these policy areas expert groups operate on a formal mandate, as a result of complexity and a requirement of legitimacy. And furthermore, that the primary effect of the complex nature of the policy-making process, and the corresponding use of expert knowledge to legitimate policy, is on the level and type of political participation.