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Vardakos, Sotirios. "Back-analysis methods for optimal tunnel design". Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/26124.
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A fundamental element of the observational method in geotechnical engineering practice is the utilization of a carefully laid out performance monitoring system which provides rapid insight of critical behavioral trends of the work. Especially in tunnels, this is of paramount importance when the contractual arrangements allow an adaptive tunnel support design during construction such as the NATM approach. Utilization of measurements can reveal important aspects of the ground-support interaction, warning of potential problems, and design optimization and forecasting of future behavior of the underground work.
The term back-analysis involves all the necessary procedures so that a predicted simulation yields results as close as possible to the observed behavior. This research aims in a better understanding of the back-analysis methodologies by examining both simplified approaches of tunnel response prediction but also more complex numerical methods. Today a wealth of monitoring techniques is available for tunnel monitoring. Progress has also been recorded in the area of back-analysis in geotechnical engineering by various researchers. One of the most frequently encountered questions in this reverse engineering type of work is the uniqueness of the final solution. When possible errors are incorporated during data acquisition, the back analysis problem becomes formidable. Up to the present, various researchers have presented back-analysis schemes, often coupled with numerical methods such as the Finite Element Method, and in some cases the more general approach of neural networks has been applied.
The present research focuses on the application of back-analysis techniques that are applicable to various conditions and are directly coupled with a widely available numerical program. Different methods are discussed and examples are given. The strength and importance of global optimization is introduced for geotechnical engineering applications along with the novel implementation of two global optimization algorithms in geotechnical parameter identification. The techniques developed are applied to the back-analysis of a modern NATM highway tunnel in China and the results are discussed.Ph. D.
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Kelceoglu, Bekir. "Preventing carpal tunnel syndrome : a product design study to assist carpal tunnel syndrome prevention techniques". Connect to resource, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1194647505.
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Adderley, Geoffrey. "The effect of tunnel blast design on vibration". Thesis, University of Essex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506087.
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Bjureland, William. "On reliability-based design of rock tunnel support". Licentiate thesis, KTH, Jord- och bergmekanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-204919.
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Tunneling involves large uncertainties. Since 2009, design of rock tunnels in European countries should be performed in accordance with the Eurocodes. The main principle in the Eurocodes is that it must be shown in all design situations that no relevant limit state is exceeded. This can be achieved with a number of different methods, where the most common one is design by calculation. To account for uncertainties in design, the Eurocode states that design by calculation should primarily be performed using limit state design methods, i.e. the partial factor method or reliability-based methods. The basic principle of the former is that it shall be assured that a structure’s resisting capacity is larger than the load acting on the structure, with high enough probability. Even if this might seem straightforward, the practical application of limit state design to rock tunnel support has only been studied to a limited extent. The aim of this licentiate thesis is to provide a review of the practical applicability of using reliability-based methods and the partial factor method in design of rock tunnel support. The review and the following discussion are based on findings from the cases studied in the appended papers. The discussion focuses on the challenges of applying fixed partial factors, as suggested by Eurocode, in design of rock tunnel support and some of the practical difficulties the engineer is faced with when applying reliability-based methods to design rock tunnel support. The main conclusions are that the partial factor method (as defined in Eurocode) is not suitable to use in design of rock tunnel support, but that reliability-based methods have the potential to account for uncertainties present in design, especially when used within the framework of the observational method. However, gathering of data for statistical quantification of input variables along with clarification of the necessary reliability levels and definition of “failure” are needed.QC 20170407
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BACCHINI, ALESSANDRO. "Electric VTOL preliminary design and wind tunnel tests". Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2847140.
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Cheong, Mun Kit. "Assessment of Vehicle Fire Development in Road Tunnels for Smoke Control Ventilation Design". Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2009. http://hdl.handle.net/10092/2863.
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A fire in road tunnel can be dangerous and lead to serious consequences if not addressed
appropriately. In a tunnel fire incident, creating a smoke free path for motorist evacuation
and facilitating fire fighters to access the fire is critical for fire and rescue operations. A
means of achieving this is to use ventilation fans to blow sufficient air down the tunnel
ensuring no back-layering of smoke occurs upstream of the fire. The airflow necessary for
such operation is known as the critical velocity which is a function of a number of factors
includes; heat release rate, tunnel geometry, tunnel gradient etc. Among these parameters,
the heat release rate is the most difficult to identify as this value is dependent on the types
of vehicles, number of vehicles involved, the type of cargo and the quantity of cargo
carried by these vehicles. There are also other factors such as the influence of ventilation
condition, tunnel geometry and the use of legislation (to restrict hazardous vehicles
entering in tunnel) that could affect the heat release rate in a tunnel fire. The number of
possible fire scenarios is numerous.
Based on current practise, fire size selection for most tunnel ventilation design often
references various guidelines such as NFPA 502, BD78/99 or the PIARC technical
committee report. The heat release rate, particularly for goods vehicle recommended by
the guidelines varies from 20 to 30 MW. However, recent fire tests conducted in the
Runehamar tunnel experiments indicate a higher heat release rate. These experiments
suggest that heat release rate guidelines for goods vehicles might be underestimated. An
ideal means to estimate the heat release rate in the tunnel is to use the oxygen consumption
calorimetry technique. However, this approach is generally expensive, logistically
complicated to perform and it is often not feasible to conduct such tests for a tunnel project
at the initial design stage simply because the structure and systems are not ready for such
activities.
This research thesis presents an approach to establish a design fire in a road tunnel
particularly the peak heat release rate for emergency tunnel ventilation system design. The
analysis consists of two stages; stage one involves the use of a probabilistic approach (risk
analysis) to identify the potential cause and type of vehicle which could result in a tunnel
fire. Findings from the risk analysis are used in stage two in which Computational Fluid
II
Dynamics (CDF) modelling is used to establish the heat release rate in the tunnel
considering factors such as fuel load, ventilation condition, tunnel geometry and ignition
location. The Fire Dynamics Simulator (FDS 4.0.7), a CFD model of fire-driven fluid flow
is used for the analysis and an urban road tunnel project in Singapore is used to illustrate
this methodology.
Other topic related to this research work includes the reconstruction for the Runehamar
tunnel fire test using numerical approach to calibrate the FDS simulation model. The used
of Probabilistic Bayesian approach and CFD approach using FDS to estimate the heat
release rate in the tunnel is also investigated in this thesis. The effect of vehicle fire spread
in road tunnel and numerical simulation of road tunnel fires using parallel processing is
presented. Preliminary work in using FDS5 for tunnel simulation work is discussed as part
of the research work in this project.
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Mattar, Joe. "An investigation of tunnel-soil-pile interaction in cohesive soils /". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112577.
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Underground tunnels are considered to be a vital infrastructure component in most cities around the world. Careful planning is always necessary to ensure minimum impact on nearby surface and subsurface structures. This thesis describes the experimental and numerical investigations carried out at McGill University to examine the effect of existing pile foundation on the stresses developing in a newly constructed tunnel supported by a flexible lining system. A small scale testing facility was designed and built to simulate the process of tunnel excavation and lining installation in the close vicinity of pre-installed piles. Lining stresses were measured for different separation distances between the tunnel and the existing piles. Significant decrease in circumferential stresses was observed when the lining was installed at a distance that ranges between one to three times the tunnel diameter from the piles. Two-dimensional finite element analyses were also conducted to investigate the different aspects of the pile-soil-lining interaction including lining deformation, axial forces and bending moments. The measured lining stresses agreed with those obtained using finite element analysis. The results presented in this study provided an insight into understanding an important aspect of this soil-structure interaction problem.
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Chatawut, Chanvanichskul. "Fundamental Study on Design and Stability of Tunnel Structures". 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/123480.
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Du, Dianchun. "Design of tunnels using the hyperstatic reaction method". Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI063/document.
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Ce travail de recherche a pour objectif de présenter la conception de tunnels au moyen de la méthode hyperstatique aux coefficients de réaction (HRM). Les modèles développés par la méthode HRM sont tout d'abord proposés pour étudier le comportement de tunnels en forme de fer à cheval inversée dans différentes conditions, par exemple en considérant deux cas de charge, deux géométries différentes de revêtement de tunnel, deux cas de coefficients de réaction différents, changement de la rigidité des coefficients de réaction, conditions de sol multicouches, surcharges en surface et sol saturés. Les modèles présentés permettent d’aboutir à des prévisions qualitatives avec une efficacité de calcul élevée par rapport à la modélisation numérique en différences finies. Une analyse paramétrique est ensuite réalisée pour estimer le comportement du revêtement de tunnel en forme de fer à cheval dans un grand nombre de cas couvrant les conditions généralement rencontrées dans la pratique. Ensuite, en prenant comme exemple un tunnel métropolitain à deux voies, une série de fonctions mathématiques est déduite et utilisée dans le processus d'optimisation d’un tunnel de forme complexe, ce qui offre aux concepteurs de tunnels un support théorique leur permettant de choisir la forme optimale du tunnel à mettre en oeuvre. L’effet de différents paramètres, tels que le coefficient des terres au repos, le module d’Young du sol, la profondeur du tunnel, les surcharges en surface, sur les efforts internes et la forme du tunnel. Dans la dernière partie du manuscrit, l’influence d’un changement de température sur les efforts dans le revêtement d’un tunnel circulaire au moyen de la méthode HRM est étudiée en tenant compte de différents facteurs, tels que l’épaisseur du revêtement de tunnel, le module d’élasticité du revêtement et le coefficient de dilatation thermique du solThis research work aims to present the design of tunnel by means of the Hyperstatic Reaction Method (HRM). The models developed by the HRM method are firstly proposed for investigating the behaviour of U-shaped tunnels under different conditions, considering two load cases, two different geometries of U-shaped tunnel lining, two different cases of springs, change of the spring stiffness, multi-layered soil conditions, surcharge loading, and saturated soil masses. The presented models permit to obtain good predictions with a high computational efficiency in comparison to finite difference numerical modelling. Then a parametric analysis has permitted to estimate the U-shaped tunnel lining behaviour in a large number of cases which cover the conditions that are generally encountered in practice. Thereafter, taking a twin-lane metro tunnel as an example, a series of mathematical functions used in the optimization progress of sub-rectangular tunnel shape is deduced, which gives to tunnel designers a theoretical support to choose the optimal sub-rectangular tunnel shape. The effect of different parameters, like the lateral earth pressure factor, soil Young’s modulus, tunnel depth, surface loads, on the internal forces and shape of sub-rectangular tunnel is then given. In the last part of the manuscript, the influence of a temperature change on the lining forces of circular tunnel by means of the HRM method is investigated, considering different factors, such as the tunnel lining thickness, lining elastic modulus and ground coefficient of thermal expansion
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Hamilton, Christianne Rhea. "Design of Test Sections for a High Enthalpy Wind Tunnel". MSSTATE, 2003. http://sun.library.msstate.edu/ETD-db/theses/available/etd-04082003-114126/.
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This document describes the design of a supersonic and a subsonic test section for a high enthalpy wind tunnel. A streamline is tracked through a supersonic test section using the method of characteristics. The specifics of the design program and the design techniques are illustrated for the supersonic section. The section of the paper dealing with the subsonic nozzle has a greatly diverse nature. This section details the inlet and exhaust restrictions and construction elements for the entire low speed system. The system is currently being set up for testing with the subsonic section, and the supersonic will eventually follow.
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Carey, P. S. "Direct wind tunnel modelling of natural ventilation for design purposes". Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422325.
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Gustafson, Eric Andrew. "Design, Simulation, and Wind Tunnel Verication of a Morphing Airfoil". Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/33663.
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The application of smart materials to control the flight dynamics of a Micro Air Vehicle
(MAV) has numerous benefits over traditional servomechanisms. Under study is wing morphing achieved through the use of piezoelectric Macro Fiber Composites (MFCs). These devices exhibit low power draw but excellent bandwidth characteristics. This thesis provides a background in the 2D analytical and computer modeling tools and methods needed to design and characterize an MFC-actuated airfoil.
A composite airfoil is designed with embedded MFCs in a bimorph configuration. The deflection capabilities under actuation are predicted with the commercial finite element package NX Nastran. Placement of the piezoelectric actuator is studied for optimal effectiveness. A thermal analogy is used to represent piezoelectric strain. Lift and drag coefficients in low Reynolds number flow are explored with XFOIL. Predictions are made on static aeroelastic effects. The thin, cambered Generic Micro Aerial Vehicle (GenMAV) airfoil is fabricated with a bimorph actuator. Experimental data are taken with and without aerodynamic loading to validate the computer model. This is accomplished with in-house 2D wind tunnel testing.Master of Science
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Mathew, Jose. "Design, fabrication, and characterization of an anechoic wind tunnel facility". [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0013083.
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KAUSHIK, ABHISHEK. "DESIGN OF A TUNNEL BY NEW AUSTRIAN TUNNELING METHOD (NATM)". Thesis, DELHI TECHNOLOGICAL UNIVERSITY, 2021. http://dspace.dtu.ac.in:8080/jspui/handle/repository/18804.
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There are several methods for designing rock supports in tunnels. The Q-system is one of such
methods, which is based on the rock mass classification. The Q-system was developed at
Norwegian GeotechnicalInstitute (NGI) between 1971 and 1974 (Barton et al. (1974)). The
rock supports recommendations fromQ-system are based on the Q-value of the rock mass,
which is calculated from 6 rock parameters. The rock parameters for calculating Q-values are
based on the orientation and number of discontinuity sets present in the rock mass, surface
condition of discontinuities, groundwater conditions and insitu stress state in the rock mass.
For a known Q-value and span/height of the tunnel, the Q-system recommends rock support in
terms of thickness of fibre reinforced sprayed concrete layer, rock bolts, reinforced ribs of
sprayed concrete (RRS) and in some cases cast concrete lining (CCA). There are several types
of fibres available to reinforce the sprayed concrete, however it is chosen to use steel fibres for
the present work. The reinforced ribs of sprayed concrete (RRS) are similar to a reinforced
concrete beam and generally recommended for a very poor quality of rock mass. Based on the
quality of rock mass, the Q-system recommends thickness and the reinforcement in the RRS.
The installation of rock supports is a risky task, especially when the rock mass quality is very
poor as the rock blocks may fall during installation. Moreover, the reinforcement for RRS need
be placed duringinstallation, which makes the construction of tunnel difficult, time consuming
and expensive.
Several research papers are published to assess the validity of Q-system’s supports
recommendations, one such study was conducted by Palmstrom and Broch (2006). The authors
concluded that the Q-systemis a optimum method to design the supports for fair to very good
rock masses, but it may provide impractical, unrealistic and conservative outcome for poor
rock masses.
The rock supports from Q-system are compared with the outcome from numerical analysis in
this thesisaiming to obtain the optimized rock supports and subsequently improving the safety
and pace of construction. The main objective set for this study is to check the possibility of
reducing the requirement of reinforcement in the RRS focusing mainly on the poor quality of
rock masses in general, having Q- values less than 1.
The results from numerical analysis show that the rock supports recommended by Qsystem for
the verypoor rock mass (Q <1) are conservative and can be optimised in terms of reducing the
reinforcement inRRS, given that the detailed rock-lining interaction analysis is carried out.
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Åberg, Anton. "Aldrig ensam : Ett ljudsystem för unga kvinnors trygghet". Thesis, Högskolan i Gävle, Industridesign, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-34009.
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This project began with me joining in on a safety tour. This safety tour spanned across a neighborhood called Andersberg, in my hometown of Gävle. By talking to the participants of the safety tour, I started to realize the scope of the problem that presented itself there. These individuals, mostly consisting of residents of the area and neighboring areas, disclosed that they felt a constant insecurity while they were out and about in Gävle, especially during late nights. This piqued my interest. I wanted to enable these individuals to feel safe in their own hometown. I carried out interviews with residents of Gävle to fully understand their feelings of insecurity. The interviews and analysis of research that had been done within the subject, also gave me a more specific target group. A target group that experienced insecurity to further extents than other groups; women between the ages of 20 to 24. A survey was created for me to get a better understanding of what causes and elements there was for the experiences. The survey was sent to several young women, who shared the survey link with other members of the target group. The respondents’ answers painted a picture of the true scale of the problem and made me realize that the problem was too immense for me to solve completely. Thereby I found, amongst the survey answers, a part of the problem where I could do the most good. Which turned out to be loneliness and the thought of not being able to get out of a dangerous situation. Further exploration of the locations where the insecurity was experienced made it apparent that the tunnel was the structure where change was needed the most. The design that contributes to solving the problem is as follows; a system of speakers that play the sound of women talking and walking. These systems are used in tunnels to give the impression that the individual that passes through is surrounded by other women. This explains the name given to the concept; “Aldrig ensam” (Never alone).Projektet tog sin början i att jag deltog i en trygghetsvandring i området Andersberg i min hemstad Gävle. Efter att ha pratat med de andra deltagarna, började jag förstå storleken av det problem som fanns där. Dessa individer, som mestadels bestod av områdets och närliggande områdens invånare, hävdade att de kände en konstant känsla av otrygghet då de befann sig i staden, speciellt under nattetid. Detta fångade mitt intresse. Jag ville hjälpa dessa individer att känna sig trygga i sin egen hemstad. Jag utförde intervjuer med några av Gävles invånare för att tydligare förstå deras känslor av otrygghet. Intervjuerna, tillsammans med analyser av forskning i ämnet gav mig även en mer specifik målgrupp. En målgrupp som upplevde otrygghet i större utsträckning än andra grupper; kvinnor i åldrarna 20 till 24. En enkät skapades för att ge mig en bättre förståelse för orsakerna till den upplevda otryggheten. Enkäten skickades ut till flera unga kvinnor, som i sin tur delade med sig av enkätens länk till andra individer inom målgruppen. Respondenternas svar målade upp en bild av problemets sanna storlek, och fick mig att inse att det var för stort för att jag skulle kunna lösa det helt och hållet. Därför hittade jag, bland enkätens svar, en del av problemet där jag kunde göra mest nytta. Detta visade sig vara känslan av ensamhet och tron om att man inte kan ta sig ifrån en farlig situation. Vidare utforskning av de platser där otrygghet upplevdes tydliggjorde att gångtunneln var platsen där förändring behövdes som mest. Designen som bidrar till lösningen av problemet är som följande; ett högtalarsystem som spelar upp ljudet av kvinnor som pratar och går. Systemet används i tunnlar för att ge intrycket av att individen som passerar genom tunneln är omgiven av andra kvinnor. Därav namnet givet till designen, ”Aldrig ensam”
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Chen, Ran 1977. "Time dependent analysis of tunnel in creeping rock". Phd thesis, School of Civil Engineering, 2009. http://hdl.handle.net/2123/6432.
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Foschi, Edoardo. "Design of a return circuit for an open loop wind tunnel". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21536/.
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This work is about the design of two different solutions of a return circuit for the subsonic open loop wind tunnel of the University of Bologna placed in the laboratory of aerodynamics. The possibility of realizing a return circuit was born from the idea of moving the current wind tunnel to a different place. Realizing a closed-type wind tunnel could permit a better installation with reduced costs since the starting point of the project is an existing tunnel. Two different design solutions are shown in order to satisfy different conditions of allocation: one model has vertical development, the other has horizontal development. The conceptual phase is followed by a study of the pressure losses in order to evaluate which design solution could be the best.
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Ascioglu, Gokhan. "Analysis Of Support Design Practice At Elmalik Portals Of Bolu Tunnel". Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12609031/index.pdf.
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A completed part of the Bolu Tunnel at Elmalik side collapsed during the 1999 Düzce earthquake. In order to by-pass the collapsed section, a new tunnel route was determined. 474 meters of the new route, including two portals and double tubing, crossed through the weak to very weak rock units with intersecting fault gouge, excavated from Elmalik side. In this study, the characteristics of the rock masses and support classes are determined for new route of the Elmalik Side. Then, during the tunnel excavation, the deformations of temporary and permanent support systems were precisely measured and recorded. The support system properties as determined from NATM were analyzed by two dimensional convergence confinement method using the numerical RocSupport software. As a result of this study, for weak ground tunneling, duration of primary support installation should be kept at minimum. Besides that, temporary support measures such as forepoling, face sealing and temporary invert have an important role in controlling deformations before the primary support installation. With the application of temporary supports, loading on the permanent support, and hence the final deformation of the excavation, was found to be reduced significantly. Application of rigid lining was found to be necessary in order to prevent long-term deformations in weak ground tunnels, even though it is contradictory to the NATM philosophy.
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Karahan, Ercument. "Design Of Excavation An Support Syaytems Of Cubukbeli Tunnel In Antalya". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611569/index.pdf.
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In this thesis, suggestion of appropriate excavation and support systems and selection of rock mass strength parameters for the determination of these systems were carried out for the Çubukbeli Tunnel in Antalya. Ç
ubukbeli Tunnel is a twin tube flute shaped tunnel with 1985 m length, 12 m width, 10 m height and maximum overburden thickness of 130 m. The tunnel area consists of limestone, clayey limestone, claystone, marl and siltsone. Rock mass classification systems are used for evaluation of rock mass characteristics and estimation of strength parameters. Selection of appropriate numerical method and software tool, namely Phase2, is accomplished after an extensive literature survey. The rock mass was divided into sections according to the RMR, Q, NATM and GSI classification systems along the tunnel and excavation and support systems were determined empirically along these sections. Thereafter, geomechanical parameters (i.e. modulus of deformation Em, Hoek-Brown material constants m and s etc.) were selected based on these classification systems. Finite element analysis was carried out as the final step of the design in order to investigate deformations and stress concentrations around the tunnel, analyze interaction of support systems with excavated rock masses and verify and check the validity of empirically determined excavation and support systems. As the result of design studies accomplished along tunnel route, B1, B2, B3 and C2 type rock classes are assumed to be faced during construction of Ç
ubukbeli Tunnel and appropriate excavation and support systems are proposed for these rock classes.
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Gupta, Ajay. "Performance prediction and conceptual design of a continuous tunnel boring machine". Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12154.
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Ramesh, Anisha. "TUNNELING BASED QUANTUM FUNCTIONAL DEVICES AND CIRCUITS FOR LOW POWER VLSI DESIGN". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338315073.
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Le, Good G. M. "Aerodynamic characteristics of passenger cars : comparison between wind tunnel and track derived data". Thesis, Cranfield University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260296.
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Wang, Liquan. "Reliable design of tunnel diode and resonant tunnelling diode based microwave sources". Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3423/.
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This thesis describes the reliable design of tunnel diode and resonant tunneling diode (RTD) oscillator circuits. The challenges of designing with tunnel diodes and RTDs are explained and new design approaches discussed. The challenges include eliminating DC instability, which often manifests itself as low frequency parasitic oscillations, and increasing the low output power of the oscillator circuits. To stabilise tunnelling devices, a common but sometimes ineffective approach is the use of a resistor of suitable value connected across the device. It is shown in this thesis that this resistor tunnel diode circuit can be described by the Van der Pol model. Based on this model, design equations have been derived which enable the design of current-voltage (I-V) measurement circuits that are free from both low frequency bias oscillations and high frequency parasitic oscillations. In the conventional setup, the I-V characteristic of the tunnelling device is extracted from the measurement by subtracting from the measured current the current through the stabilising resistance at each bias voltage. In this thesis, also using the Van der Pol model, a circuit for the direct measurement of I-V characteristics is proposed. This circuit utilises a series resistor-capacitor combination in parallel with the tunnelling device for stabilisation. Experimental results show that IV characterisation of tunnel diodes in the negative differential resistance (NDR) region free from oscillations can be made. A new test set-up suitable for radio frequency (RF) characterisation of tunnel diodes over the entire NDR region was also developed. Initial measurement results on a packaged tunnel diode indicate that accurate characterisation and subsequent small-signal equivalent circuit model extraction for the NDR region can be done. To address the limitations of low output power of tunnel diode or RTD oscillators, a new multiple device circuit topology, incorporating a novel design methodology for the DC bias decoupling circuit, has been developed. It is based on designing the oscillator specifically for sinusoidal oscillations, and not relaxation oscillations which are also possible in tunnel diode oscillators. The oscillator circuit can also be described by the Van der Pol model which provides theoretical predictions of the maximum inductance, in terms of the tunnel diode device parameters, that is required to resonate with the device capacitance for sinusoidal oscillations. Each of the tunnel diodes in the multiple device oscillator circuit is decoupled from the others at DC and so can be stabilised independently. The oscillator topology uses parallel resonance but with each tunnel diode individually biased and DC decoupled making it possible to employ several tunnel diodes for higher output power. This approach is expected to eliminate parasitic bias oscillations in tunnel diode oscillators whilst increasing the output power of a single oscillator. Simulation and experimental oscillator results were in good agreement, with a two-tunnel diode oscillator exhibiting approximately double the output power as compared to that of a single tunnel diode oscillator, i.e. 3 dB higher. Another method considered for the realisation of higher output power tunnel diode or RTD oscillators was series integration of the NDR devices. A new method to suppress DC instability of the NDR devices connected in series with all the devices biased in their NDR regions was investigated. It was successfully employed for DC characterisation with integrations of 2 and 5 tunnel diodes. Even though no suitable oscillator circuit topology and/or methodology with series-connected NDR devices could be established for single frequency oscillation, the achieved results indicated that this approach may be worthy of further investigation. The final aspect of this project focussed on the monolithic realisation of RTD oscillators. Monolithic oscillators in coplanar waveguide (CPW) technology were successfully fabricated and worked at a fundamental frequency of 17.5 GHz with -21.83 dBm output power. Finally, to assess the potential of RTD oscillators for high frequency signal generation, a theoretical analysis of output power of stabilised RTD oscillators was undertaken. This analysis suggests that it may be possible to realise RTD oscillators with high output power (0 dBm) at millimetre-wave and low terahertz (up to 1 THz) frequencies.
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Johl, G. "The design and performance of a 1.9m x 1.3m indraft wind tunnel". Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/7194.
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This Thesis has endorsed employing a novel indraft configuration for a severely spatially and financially constrained wind tunnel aimed at undergraduate and postgraduate aeronautical and automotive instruction. The novel horseshoe indraft configuration employed may be considered to either bend a traditional open circuit or remove corners 3 and 4 from a traditional closed circuit. By connecting the inlet and exit to atmosphere the new configuration prevents pressure loading of the surrounding building; eliminates the problem of exhausting a jet within a laboratory; and eliminates costs associated with a heat exchanger. The modest budget (£350,000) is commensurate with the financial means of a University or small enterprise. Aerodynamic performance data suggests future designers should not shy away from an indraft tunnel by default: Velocity uniformity in the working area of jet has been shown to vary by less than 0.3% of the mean in the presence of ambient gusts up to 11.5% of the test velocity. Lift and drag coefficients derived from a 27% scale Davis automotive model (5.9% frontal area blockage) repeated to 6 units (0.6%) and 2 units (0.2%) respectively in the presence of ambient gusts up to 13% of the test velocity. Axial turbulence intensity was measured to be in the region of 0.15% (negligible ambient gusts) and 0.35% (ambient gusts up to 16% of the test velocity). This data compares favourably to that for the significantly larger NASA Ames 80ft x 120ft open circuit wind tunnel. Maximum test section velocity has been shown to be in excess of the desired 40m/s. The test section boundary layer closely follows the profile for a 1/7th power law turbulent boundary layer, which suggests the contraction is free from separation. This Thesis contributes to the body of knowledge by publishing performance data for a new type of wind tunnel configuration. It also augments existing design guidelines and rules of thumb by providing a complete reference point (including design flowcharts) for the design of comparable low speed wind tunnels. The Thesis offers the following specific conclusions and implications: Screens: Whilst the inlet filer mesh is effective at damping ambient gusts it suffers the worst correlation to the governing equations (significant under prediction of loss), likely due to wire-wake coalescence. This highlights the importance of performing pipe rig tests for screens with open areas significantly less than 57%. Safety screen loss was under-predicted (assumed drag coefficient, CD of 1.0 due to treatment as isolated wires). Whilst measurements suggest a CD of ~1.25 designers are advised to conduct pipe rig tests. Contraction: To allow pressure gradients to decay prior to the working section, it is advised that the parallel duct at end of the contraction be 1 hydraulic diameter rather than the 1 hydraulic radius proposed by the major texts. Working section: To allow for model wake recovery (and hence reduce the effect of non-uniformity on the downstream diffuser), a working section length-to-diameter ratio of 2.5 is suggested rather than 2 proposed by the established texts. Additionally, the static ports of tunnel pitot-static should be at least 0.55 hydraulic diameters upstream of the model leading edge to position them away from the static pressure signature of the model. Diffusers: Whilst the safety screen would ideally have to be removed to prove the hypothesis - it is suggested that turbulent mixing aft of the safety screen (located at the end of the working section) appears to offer a ~10% Cpr improvement to the first diffuser. Corner cascades: Whilst the established texts focus on corner loss coefficient (KL) this Thesis has shown that KL should not be the sole metric used to select the space-to-chord ratio (s/c) of corner cascades. Uniformity far downstream of a test cascade has been shown to improve with more closely spaced vanes (s/c of 0.190 rather than 0.237) despite KL being similar. Improvements to inlet boundary layer quality have also been shown to reduce KL. Fan: The fan static pressure rise was measured to be less than predicted due to smaller than expected leakage losses. A leakage loss of 2.5% is therefore proposed rather than the 10% suggested by the major texts.
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Asef, Mohammad Reza. "Rock-support interaction analysis for tunnel design : a numerical modelling based approach". Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367354.
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Terezopoulos, N. G. "Rock mechanics design principles applied to tunnel stability in deep mining conditions". Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373790.
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Wilkins, James R. IV. "Propeller design optimization for tunnel bow thrusters in the bollard pull condition". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74896.
Pełny tekst źródłaStreszczenie:
Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 50-51).
Tunnel bow thrusters are often used by large ships to provide low-speed lateral maneuverability when docking. Required to provide high thrust while essentially at a standstill, the design point for these thrusters is the bollard pull condition. Traditionally, the term bollard pull refers to the amount of force a tug can apply to a bollard when secured to a pier. Here, the bollard pull condition is used to describe a propeller with no flow over it except for that induced by its own rotation. Conventional propeller design is primarily performed for an optimal vessel speed or range of speeds. OpenProp, a propeller design code based on lifting line theory, is a numerical model capable of design and analysis of such propellers. It has been experimentally validated for standard design conditions in an external flow, but until now has been incapable of design with no external fluid velocity component applied. Recent updates to the model now allow for bollard pull design work. This project is the first application of the OpenProp model update. Propellers are designed for both open water and ducted (tunnel) applications in OpenProp. Propeller geometry design refinement by coupling MTFLOW, an Euler Equation viscous flow solver, with PBD-14, a lifting surface design program for marine propulsors is examined. An experimental apparatus is constructed to test the propeller designs and validate the OpenProp model. A range of off-design operating conditions are analyzed and results are presented.
by James R. Wilkins, IV.
Nav.E.and S.M.
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Garcia, Jason S. "Design, Construction, and Characterization of the University of South Florida Wind Tunnel". Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7294.
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Much of the aerosol research completed at the University of South Florida has revolved around evaluating industrial hygiene equipment and instrumentation in environmental chambers. Data collected during these studies has provided valuable baseline data on equipment and instrument performance under calm air conditions. A newly constructed wind tunnel now allows researchers to evaluate industrial hygiene instruments under moving air conditions. Because the wind tunnel is capable of producing wind velocities that a worker could encounter in the occupational setting, researchers may gain insight into instrument performance under simulated field conditions. Because aerosols can be introduced into the new wind tunnel testing section, researchers can also challenge industrial hygiene equipment and instrumentation with aerosols in sizes ranges that are of interest in public health.
The purpose of this dissertation research was to develop a new wind tunnel to be used for aerosol research at the University of South Florida. Three specific aims had to be met for this study to be successful. They included: (1) designing a wind tunnel based on best practice information outlined in scientific literature, (2) constructing an operable wind tunnel to be used for aerosol research, and (3) characterizing wind tunnel performance by examining the wind tunnel velocity profile, turbulence intensity, and aerosol introduction/collection. The actual wind tunnel was constructed to a length of approximately 20 feet, a height of approximately 2 feet at its tallest point, and includes an entrance filter housing, a settling chamber, a contraction, a testing section, a diffuser, an exit filter housing, a fan, and exhaust duct. All components were designed and constructed using guidelines and best practices reported in the scientific literature.
Velocity profile measurements were the first way that this wind tunnel was characterized. In order to successfully obtain measurements, the wind tunnel cross section was divided into 16 equal quadrants. Five measurements were taken for each quadrant at each wind velocity. Target wind velocities for this research were 0.5 m/s, 1.0 m/s, and 2.0 m/s. Actual average wind velocities of 0.48 m/s, 1.00 m/s, and 2.04 m/s. All were within established limits reported in the scientific literature.
Turbulence intensity measurements were the second way that this wind tunnel was characterized. In order to successfully obtain measurements, the wind tunnel cross section was divided into 16 equal quadrants. Five measurements were taken for each quadrant at each wind velocity. Wind tunnels are typically designed to have the lowest turbulence intensity possible, generally below 10%. The overall average turbulence intensities for this wind tunnel at wind velocities of 0.5 m/s, 1.0 m/s, and 2.0 m/s were 9%, 10%, and 8% respectively. Overall turbulence intensity measurements were at or below 10%.
Isokinetic sampling was the final method used to characterize this wind tunnel by collecting and detecting aerosols traveling through the wind tunnel testing section. The wind tunnel was operated at wind velocities of 0.5 m/s, 1.0 m/s, and 2.0 m/s with isokinetic sampling flow rates of 15.4 L/min, 30.9 L/min, and 61.7 L/min respectively. Monodisperse fluorescent polystyrene latex spheres were used as the test aerosol because they are uniform in size and shape and can be detected by fluorometry. The Blaustein Multi-Jet Atomizer (BLAM) was used to generate monodisperse fluorescent polystyrene latex aerosol 0.5 µm and 2.0 µm particles from liquid suspensions. The Vilnius Aerosol Generator (VAG) was used to generate monodisperse fluorescent polystyrene latex aerosol of 6.0 µm and 12.0 µm particles from dry powders. Nitrogen gas was used for delivering test aerosols into the wind tunnel. Five experimental runs were completed for each particle size and wind velocity for a total of 60 experimental runs. Fluorescence was detected in all 60 samples with average mass concentrations ranging from 0.000050 ng/ml to 0.002703 ng/ml.
Based on velocity profile measurements, turbulence intensity measurements, and isokinetic sampling, the performance of University of South Florida wind tunnel was found to be excellent, indicating that it was designed and constructed appropriately. The wind tunnel can now successfully be used by researchers interested in evaluating industrial hygiene sampling equipment with aerosols ranging from 0.5 µm to 12.0 µm in moving air with velocities ranging from 0.5 m/s to 2.0 m/s.
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Al-Qahtani, Turki Haif. "An improved design of wind towers for wind induced natural ventilation". Thesis, University of Bath, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323566.
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Baxter, N. G. "Design and stability of steel support systems with special reference to gate roadways in the Warwickshire coalfield". Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378773.
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Blanco, Mark Richard. "Design and Qualification of a Boundary-Layer Wind Tunnel for Modern CFD Validation Experiments". Youngstown State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1559237473563483.
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Cevik, Fatih. "Design Of An Axial Flow Fan For A Vertical Wind Tunnel For Paratroopers". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612790/index.pdf.
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Free fall is one of the important phases of the operation performed by the Special Forces paratroopers. Also civilian parachutists are performing free fall as a sport by doing aerobatic maneuvers when they reach the terminal
velocity during falling before opening their parachutes. Vertical wind tunnels are used for training the parachutists and paratroopers. It is safe, cheap and more convenient when compared to jumping out of an airplane.
This thesis consists of aerodynamic design of closed circuit, double return vertical wind tunnel with a flight section that can accommodate four paratroopers, aerodynamic design of a rotor straightener configuration axial flow fan and running CFD analysis of the axial flow fan for different operating conditions by FLUENT software.
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Pettersson, Karl. "Scaling techniques using CFD and wind tunnel measurements for use in aircraft design". Licentiate thesis, Stockholm : Department of Aeronautical and Vehicle Engineering, Royal Institute of Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4122.
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Neal, David Anthony III. "Design, Development, and Analysis of a Morphing Aircraft Model for Wind Tunnel Experimentation". Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/32104.
Pełny tekst źródłaStreszczenie:
Morphing aircraft combine both radical and subtle wing shape changes to improve vehicle performance relative to a rigid airframe. An aircraft wind tunnel model with considerable wing-shape freedom can serve as a tool in learning to model, control, and fully exploit the potential of such vehicles. This work describes the design, development, and initial analysis of a wind tunnel model that combines large and small wing shape variations for fundamental research in modeling and control of morphing air vehicles. The vehicle is designed for five primary purposes: quasi-steady aerodynamic modeling of an aircraft with large planform changes, optimization studies in achieving efficient flight configurations, transient aerodynamic modeling of high-rate planform changes, evaluating planform maneuvering as an control effector, and gimbaled flight control simulation of a morphing aircraft. The knowledge gained from the wind tunnel evaluations will be used to develop general stabilization and optimal control strategies that can be applied to other vehicles with large scale planform changes and morphing flight models.
After a brief background on the development of the Morphing Aircraft Program, and previous research ventures, the first phase vehicle development is described. The vehicle function, subsystems, and control are all presented in addition to the results of first phase wind tunnel testing. Deficiencies in the phase one design motivated the phase two development which has led to the current vehicle model: MORPHEUS. The evolution towards the MORPHEUS configuration is presented in detail along with an elementary strength analysis. The new embedded control implementation to permit a rate controllable planform is included. A preliminary aerodynamic analysis is presented to contrast MORPHEUS against the phase one design and an industry morphing concept. In particular, it is shown how the redesigned model has enhanced performance characteristics and the additional degrees of freedom enable greater flexibility in optimizing a configuration, especially with respect to trim characteristics. An expansion of traditional analysis techniques is applied to derive a new optimal twist algorithm for the MORPHEUS model at each planform configuration. The analysis concludes with a hybrid continuous modeling method that combines first-order computational aerodynamic modeling with classic stability expressions and DATCOM enhancements. The elementary aerodynamic coefficients are computed over the range of possible planform configurations and combined with the optimal twist results for preliminary trim analysis. This work precedes phase two wind tunnel testing and transient modeling. Future work involves expansion into the five purposes detailed for the MORPHEUS model.Master of Science
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Zucchini, Davide. "Design and realization of an instantaneous concentration measurement system for wind tunnel applications". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23540/.
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The aim of this project work is the design and realization of an instantaneous concentration measurement system to be used with binary gas mixtures. The design is focused on the simplicity of the set up and on its compactness, and it is specifically intended to be used in wind tunnel applications. The outcome of the design process for the specified system is an aspirating hot-wire probe based on a polypropylene 3D printed body and a simple single wire sensor. Specifically, a 3D printing machine based on the Material Jetting (MJ) technology was used for the probe manufacturing. One of the most important design features is the possibility to get access to the wire through the removal of a single probe component, which is a nearly effortless operation. This feature allows to repair the broken wire sensor without the need of substitute the whole probe. From these design specifications it could be understood that due also to its dimensions, the probe must be handled with care, and it cannot operate inside hot flows or uncontrolled flow temperature and pressure conditions. It was not possible to test the probe behaviour in presence of flows with composition variations due to the lack of the necessary instrumentation to perform this kind of experiments. Nonetheless, the design effectiveness could be confirmed by verifying that the hot-wire signal remained constant when the probe was exposed to a variable speed constant composition flow. This proved the probe insensitivity to external flow speed, and it opened the possibility to further testing sessions involving gases.
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Stjepan, Galamboš. "Uticaj oblika i vrste aerodinamičke opreme privrednih motornih vozila na otpor vazduha". Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2020. https://www.cris.uns.ac.rs/record.jsf?recordId=114836&source=NDLTD&language=en.
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Usavršavanje aerodinamike privrednim motornih vozila putem optimizacije aerodinamičkih dodataka u svrhu postizanja boljih aerodinamičkih performansi u vidu umanjenja sile otpora vazduha. Prostiranje vazdušne struje oko modela je unapređeno optimizacionim dodacima što se sve ogleda u smanjenoj potrošnji goriva privrednog motornog vozila. Osim virtuelnih simulacija računarske dinamike fluida, u radu je prikazana validacija rezultata putem eksperimentalnog merenja u vazdušnom tunelu.The improvement of commercial motor vehicle's aerodynamics through optimization process of aerodynamic equpments in order to achieve better aerodynamic performance in the form of drag force reduction. The expansion of the air flow around the model is enhanced by optimization accessories, which is all reflected in the reduced of fuel consumption of the commercial motor vehicle. In addition to virtual simulations of computational fluid dynamics, the paper presents the validation of results by experimental measurement in the wind tunnel.
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Fornero, Agustin Matias. "Design, calculation and simulation of a wind tunnel for calibration of hot wire probes". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16225/.
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Desing, simulation and calculation of a wind tunnel used for calibration of hot wire probes. Involves the selection and calculation of the components of the wind tunnel, with special look in the convergent, where a few options where simulated and tested to find the best one.
Then, a model is proposed along with options for the fan of the wind tunnel.
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Ulusal, Nejat. "Conceptual Design Of A Model Support System And Its Controller For Ankara Wind Tunnel". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606951/index.pdf.
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Ankara Wind Tunnel (AWT) operated by TÜBiTAK-SAGE is the only big sized wind tunnel in Turkey. The AWT was constructed in late 1940&rsquo
s but was not operated until 1993 when the tunnel was turned over TÜ
BiTAK-SAGE. Since 1993, a series of modernization work has been undergoing in order to match the demands of the 21st century. In wind tunnels, models are positioned by special mechanisms that are instrumented to get the test data specific to the test performed. Models are assembled from their rear sides on these mechanisms called model support systems in order not to influence the flow around them. In this thesis, a conceptual design of a 6 degrees-of-freedom model support system for AWT is accomplished. A detailed system model is developed for the controller design. A force controller to perform store separation tests in real time is designed, tuned, and validated with computer simulations.
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Munro, Cameron. "Water tunnel validation and experiments at high angles of attack for aircraft conceptual design /". Linköping : Univ, 2003. http://www.bibl.liu.se/liupubl/disp/disp2002/tek847s.pdf.
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Guo, Wei. "Compact modeling of magnetic tunnel junctions and design of hybrid CMOS-magnetic integrated circuits". Grenoble INPG, 2010. http://www.theses.fr/2010INPG0126.
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Le but de cette thèse était d’évaluer les performances de circuits logiques combinant des composants CMOS classiques et des composants magnétiques. Les jonctions tunnel magnétiques sont bien connues comme éléments de base des mémoires magnétiques. Mais l’utilisation de ces composants non-volatiles peut également permettre de repousser certaines limites de la microélectronique actuelle, notamment en contribuant à diminuer la consommation, les problèmes de dissipation thermique, en améliorant la fiabilité des circuits et en apportant de nouvelles fonctionnalités. Cette thèse a consisté en deux principaux aspects. Tout d’abord, un modèle électrique équivalent de la jonction tunnel magnétique a été développé afin de pouvoir les utiliser dans les outils standards de la microélectronique. Ensuite, ces modèles ont été utilisés pour concevoir et évaluer différents circuits hybrides CMOS/magnétiques, reprogrammables ou de type ASICs, qui ont été implémentés dans des démonstrateurs
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Pereira, Jason L. "Hover and wind-tunnel testing of shrouded rotors for improved micro air vehicle design". College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8752.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Aerospace Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Catallini, Louis Ernest 1957. "ARIZONA SUPERCONDUCTING SUPER COLLIDER: ROCK MASS CLASSIFICATION FOR PRELIMINARY TUNNEL DESIGN--SIERRITA SITE (PIMA COUNTY, ARIZONA)". Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/291368.
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Franceschelli, Luca. "Cooling Performance Analysis and Design of an Instrumented Radiator in a MotoGP Wind Tunnel Model". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Znajdź pełny tekst źródłaStreszczenie:
The present thesis work was developed in collaboration with the Ducati Corse Aerodynamic Department. It is focused on the measurement system employed on the MotoGP Wind Tunnel model in order to evaluate the cooling performances at the radiators.
As first, an analysis of the current methodology is conducted. Based on the arrangement of hybrid-Kiel probes behind the radiators, it was observed that an improvement in the calibration procedure is required in order to account for inter-probe and support frame interference. Furthermore, a correlation process with the CFD simulation was carried out. A good agreement in trend with CFD results was displayed, despite a low accuracy. The need for higher spatial resolution was stated.
In order to update the CFD implementation of the actual water radiator, the latter has been characterized in terms of pressure drop on a dedicate radiator test bench, provided by Dallara Automobili. A suitable convergent frame has been designed for the purpose.
Finally, a new methodology for cooling performance evaluation was developed and calibrated. The method exploits a set of static and Kiel probes in a dummy radiator core. An honeycomb structure and a perforated plate are implemented to reproduce the real radiator behaviour.
Experiments have been performed with half-radiator equipped with the new set up and the other half instrumented with Pitot tubes, showing good agreement between the two probe-types.
A set of plates have been characterized. It allowed also to highlight the relevance of the solid part distribution - and related holes' diameter - on the pressure drop and the effect on the measured pressures from the probes.
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Yalcin, Levent. "Design And Performance Analysis Of A Variable Pitch Axial Flow Fan For Ankara Wind Tunnel". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607091/index.pdf.
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In this study, a variable pitch axial flow fan is designed and analysed for Ankara Wind Tunnel (AWT). In order to determine the loss caharacteristics of AWT, an algorithm is developed and the results are validated. Also some pressure and velocity measurements are made at the fan section to find the losses experimentally. After completion of the fan design, analyses are made at different volumetric flowrates and blade angles including the design point and the performance characteristics of the fan are obtained and thereafter the operating range of the tunnel is deterimened.
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Murray, Kenneth Douglas. "Automation and extension of LDV measurements of off-design flow in a cascade wind tunnel". Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/25708.
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Murphy, Michael M. "Defining Stress Changes Ahead of a Tunnel Face and Design of a Data Acquisition System". Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/36298.
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With increasing world population, demand for underground construction is expected to accelerate in the future. Design of tunnels in rock is still largely empirical, while rock failure in underground mines and tunnel construction continues to claim lives. A seismic method to aid in increasing safety during excavation is tomography. Seismic tomography is a non-invasive technique to map the stress changes induced by mining ahead of the active face. Seismic tomography maps the velocity distributions of elastic waves traveling through a rock mass. The velocity distributions mapped in the tomograms can relate to anomalies in the rock such as fracture zones and highly concentrated stresses. In order to develop a relationship between stress and elastic wave velocity, laboratory tests in a controlled environment are required. In the current study tomographic tests were conducted on Berea sandstone and Five Oaks limestone samples. The stress redistribution in the sandstone samples could be imaged by mapping velocity distributions. On an unconfined test the sandstone sample acted much like a coal mine pillar where the stress redistributes to the least confined area. On a sandstone test where the sample was indented by a steel platen the velocity contrast was seen directly under the load and the velocity remained almost unchanged over the rest of the sample. For the limestone tests, the stress redistribution could not be mapped in the tomograms. The ability to map the stress distribution in the tomograms were attributed to the elastic and non-elastic characteristics of the stress-strain curve. For sandstone, a porous rock, the stress redistribution could be mapped and for limestone, a stiff rock, the stress redistribution could not be mapped. A field data acquisition system to apply tomography to ground control problems in a mine was designed and calibrated. Data acquisition hardware were assembled and programmed in LabVIEW to collect seismic data in a mine. The design of a geophone array that will fit into a miniature 5.08 cm (2 in) diameter borehole is presented.Master of Science
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Murphy, Michael Martin. "Defining Stress Changes Ahead of a Tunnel Face and Design of a Data Acquisition System". Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/36298.
Pełny tekst źródłaStreszczenie:
With increasing world population, demand for underground construction is expected to accelerate in the future. Design of tunnels in rock is still largely empirical, while rock failure in underground mines and tunnel construction continues to claim lives. A seismic method to aid in increasing safety during excavation is tomography. Seismic tomography is a non-invasive technique to map the stress changes induced by mining ahead of the active face. Seismic tomography maps the velocity distributions of elastic waves traveling through a rock mass. The velocity distributions mapped in the tomograms can relate to anomalies in the rock such as fracture zones and highly concentrated stresses. In order to develop a relationship between stress and elastic wave velocity, laboratory tests in a controlled environment are required. In the current study tomographic tests were conducted on Berea sandstone and Five Oaks limestone samples. The stress redistribution in the sandstone samples could be imaged by mapping velocity distributions. On an unconfined test the sandstone sample acted much like a coal mine pillar where the stress redistributes to the least confined area. On a sandstone test where the sample was indented by a steel platen the velocity contrast was seen directly under the load and the velocity remained almost unchanged over the rest of the sample. For the limestone tests, the stress redistribution could not be mapped in the tomograms. The ability to map the stress distribution in the tomograms were attributed to the elastic and non-elastic characteristics of the stress-strain curve. For sandstone, a porous rock, the stress redistribution could be mapped and for limestone, a stiff rock, the stress redistribution could not be mapped. A field data acquisition system to apply tomography to ground control problems in a mine was designed and calibrated. Data acquisition hardware were assembled and programmed in LabVIEW to collect seismic data in a mine. The design of a geophone array that will fit into a miniature 5.08 cm (2 in) diameter borehole is presented.Master of Science
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Chui, Kwok-Lun. "Integrated wind tunnel based response analysis and structural optimization for serviceability design of tall buildings /". View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20CHUI.
Pełny tekst źródłaStreszczenie:
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 187-194). Also available in electronic version. Access restricted to campus users.
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Carlsson, Martin. "Design and Testing of Flexible Aircraft Structures". Doctoral thesis, KTH, Aeronautical and Vehicle Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3761.
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Methods for structural design, control, and testing offlexible aircraft structures are considered. Focus is onnonconventional aircraft con- figurations and control concepts.The interaction between analysis and testing is a central topicand all studies include validation testing and comparisonbetween computational and experimental results.
The first part of the thesis is concerned with the designand testing of an aeroelastic wind-tunnel model representing aBlended Wing Body (BWB) aircraft. The investigations show thata somewhat simplified wind-tunnel model design concept isuseful and efficient for the type of investigations considered.Also, the studies indicate that well established numericaltools are capable of predicting the aeroelastic behavior of theBWB aircraft with reasonable accuracy. Accurate prediction ofthe control surface aerodynamics is however found to bedifficult.
A new aerodynamic boundary element method for aeroelastictimedomain simulations and its experimental validation arepresented. The properties of the method are compared totraditional methods as well as to experimental results. Thestudy indicates that the method is capable of efficient andaccurate aeroelastic simulations.
Next, a method for tailoring a structure with respect to itsaeroelastic behavior is presented. The method is based onnumerical optimization techniques and developed for efficientdesign of aeroelastic wind-tunnel models with prescribed staticand dynamic aeroelastic properties. Experimental validationshows that the design method is useful in practice and that itprovides a more efficient handling of the dynamic aeroelasticproperties compared to previous methods.
Finally, the use of multiple control surfaces andaeroelastic effects for efficient roll maneuvering isconsidered. The idea is to design a controller that takesadvantage of the elasticity of the structure for performancebenefits. By use of optimization methods in combination with afairly simple control system, good maneuvering performance isobtained with minimal control effort. Validation testing usinga flexible wind-tunnel model and a real-time control systemshows that the control strategy is successful in practice.Keywords: aeroelasticity, active aeroelastic structures,aeroelastic tailoring, control, structural optimization,wind-tunnel testing.
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KaiYang, Chih, i 楊植凱. "Reflected Shock Tunnel Design". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/77145025015374996396.
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碩士國立成功大學
航空太空工程學系碩博士班
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This work aims to report the design of a reflected shock tunnel which will be built and tested at National Cheng Kung University, Taiwan, in year 2010. Notably, this tunnel will be the first ground test facility for hypersonic flow in universities in Taiwan. The design objective of reflected shock tunnel is to produce two free-stream conditions for a preliminary study of scramjet: (1) Mach 2 flow with temperature up to 1300 K and pressure up to 0.5 atm for the design conditions of supersonic Hydrogen combustion and (2) Mach 5 flow for the design condition of external flow. Test time is longer than 1 ms.. This shock tunnel is composed by a 13-meter-long shock tube, of which the diameter is 18 cm. The length of driver section is 3 m and the driven section is 10 m. The preliminary design is based on the numerical simulation results by using two different codes, UNIC-UNS, and a compressible multiphase flow solver (CMFS). In this work, the compressible multiphase flow solver is used to investigate the near-tailored condition and stagnation properties under different initial conditions in helium-air shock tube. The numerical simulations of nozzle flow are implemented by UNIC-UNS. Chemical Equilibrium Application (CEA) code is used to validate the shock tube reservoir conditions simulated by CMFS and calculate the chemical composition of test gas, air, in the reservoir region. According to our simulation results, the present design is satisfactory to meet the required operation conditions. Besides, the schematic diagram and the relevant instrumentation of the reflected shock tunnel are presented in this thesis.