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Brown, Ainsmar Xavier. "Inflatable wing UAV experimental and analytical flight mechanics." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39492.
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The field of man portable UASs (Unmanned Aerial Systems) is currently a key area in improving the fielded warrior's capabilities. Pressurized aerostructures that can perform with similar results of solid structures can potentially change how this objective may be accomplished now and in the future. Construction with high density polymers and other composites is currently part of active inflatable vehicle research. Many shape forming techniques have also been adapted from the airship and balloon manufacturing industry. Additional research includes modeling techniques so that these vehicles may be included in simulation packages.
A flight dynamics simulation with reduced-order aeroelastic effects derived with Lagrangian and Eulerian dynamics approaches were developed and optimized to predict the behavior of inflatable flexible structures in small UASs. The models are used to investigate the effects of significant structural deflections (warping) on aerodynamic surfaces. The model also includes compensation for large buoyancy ratios. Existing literature documents the similarity in structural dynamics of rigid beams and inflatable beams before wrinkling. Therefore, wing bending and torsional modes are approximated with the geometrically exact ntrinsic beam equations using NATASHA (Nonlinear Aeroelastic Trim And Stability for HALE Aircraft) code. An approach was also suggested for inclusion of unique phenomena such as wrinkling during flight. A simplified experimental setup will be designed to examine the most significant results observed from the simulation model. These methods may be suitable for specifying limits on flight maneuvers for inflatable UASs.
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Carvalho, Marco Aurélio. "IPCM Telemetry System: Experimental Results." International Foundation for Telemetering, 2015. http://hdl.handle.net/10150/596440.
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ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NVThe aeronautical industries have been suffering financial cutbacks and the market has to face new challenges associated with new companies. Telemetry community has been facing the increase of the electromagnetic spectrum usage for a variety of applications (e.g. 4G), after all telemetry is everywhere. In view of these issues and focused on the inherent requirements of the Flight Test application, the IPEV R&D group proposes the iPCM Telemetry architecture as solution for the existing reliability and bandwidth issues associated with the telemetry link. In this article, as a proof-of-concept of the iPCM architecture, it has been performed an experimental assembly. The results demonstrate the iPCM's ability to regenerate corrupted data providing the required data integrity and reliability, besides the capability to dynamically select the FTI transmitted parameter list to optimize the bandwidth link.
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Wilcox, Michael Schnebly. "Trajectory Generation and Optimization for Experimental Investigation of Flapping Flight." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3953.
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Though still in relative infancy, the field of flapping flight has potential to have a far-reaching impact on human life. Nature presents a myriad of examples of successful uses of this locomotion. Human efforts in flapping flight have seen substantial improvement in recent times. Wing kinematics are a key aspect of this study. This study summarizes previous wing trajectory generators and presents a new trajectory generation method built upon previous methods. This includes a novel means of commanding unequal half-stroke durations subject to robotic trajectory continuity requirements. Additionally, previous optimization methods are improved upon. Experimental optimization is performed using the new trajectory generation method and a more traditional means. Methods for quantifying and compensating for sensor time-dependence are also discussed. Results show that the Polar Fourier Series trajectory generator advanced rapidly through the optimization process, especially during the initial phase of experimentation. The Modified Berman and Wang trajectory generator moved through the design space more slowly due to the increased number of kinematic parameters. When optimizing lift only, the trajectory generators produced similar results and kinematic forms. The findings suggest that the objective statement should be modified to reward efficiency while maintaining a certain amount of lift. It is expected that the difference between the capabilities of the two trajectory generators will become more apparent under such conditions.
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Mullen, Gerald John. "Experimental evaluation of the performance and robustness of advanced rotor control schemes." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265323.
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Baek, Youn Hyeong. "An experimental review of some aircraft parameter identification techniques." Thesis, Cranfield University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285023.
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Gibbs, Jason. "Experimental Determination of Lift and Lift Distributions for Wings In Formation Flight." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/31301.
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Experimental methods for the investigation of trailing vortex strengths, total lift, and lift distributions for three-dimensional wings in close proximity flight were developed. With these experiments we model compound aircraft flight either docked tip-to-tip, or flying in formation. There is a distinct lack of experimental formation flight data using three-dimensional wing models for tests. The absence of fixed walls on either end of the wing permits the development of the asymmetric shedding of vortices, and the determination of the asymmetric circulation distribution induced by the proximity of the leading wing. The pair consisted of a swept NACA-0012 non-cambered wing simulating one half of a leading aircraft and a rectangular cambered NACA 63-420 wing simulating the trailing aircraft. Important aspects of the work included theoretical development, experimental setup, data acquisition and processing, and results validation. Experimentally determining the lift for formation flight, in addition to the local flow behavior for a pair of wings, can provide valuable insight for the proposition of flying actual aircraft in formation to increase mission efficiency. To eliminate the need for bulky mounting stings and direct load measurement devices that can potentially interfere with the local flowfield, a minimally invasive velocity probe method is developed. A series of experiments were performed to assist with the development of the method. Velocity and vorticity distributions obtained along a near-field plane were processed to calculate wingtip vortex strengths. Additionally, vortex position instabilities and the shedding of vorticity inboard of the wingtips were observed. To determine the circulation distributions for the trailing wing, the initial method is modified. By processing velocity information acquired in a near-field plane, both the lift and induced drag were calculated for the trailing airfoil. Comparisons are made to directly measured loads and to results reported earlier. Directly measured lift and drag coefficients were found to agree with existing literature.Master of Science
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Bradley, Roy. "A method for specifying complex real-time systems with application to an experimental variable stability helicopter." Thesis, University of Glasgow, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357497.
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Kostyleva, Daria [Verfasser]. "Experimental Studies of Proton-Unbound Nuclei via In-Flight Decay Spectroscopy / Daria Kostyleva." Gießen : Universitätsbibliothek, 2021. http://d-nb.info/1228828970/34.
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Sullivan, Robert Bryan. "The use of vestibular models in flight simulator motion washout systems : an experimental evaluation." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/80443.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1985.Microfiche copy available in Archives and Barker.
Bibliography: leaves 114-115.
by Robert Bryan Sullivan.
M.S.
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Brand, Albert G. "An experimental investigation of the interaction between a model rotor and airframe in forward flight." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/12433.
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Bellomo, Nicolas. "Analysis Of Variable Thrust Hybrid Propulsion For Formation Flight Satellites." Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422918.
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Hybrid motors are a promising brand of space propulsion. Many benefits have been demonstrated, like the fact that they can be "green", low cost safe. In this optics, with this thesis we want to characterize throttle-able hybrid motor for collision avoidance in formation flight.
The purpose is to enhance the performance of a "state of the art" motor, in particular mitigating the effect of some drawbacks like low regression rate and combustion efficiency. The propellant choice has been pressurized nitrous oxide as oxidizer and paraffin wax as fuel.
The work started with a preliminary design of the motor with a 0-D transient analytical code. Objective was to define the main dimensions like nozzle, grain, combustion chamber and oxidizer mass flow, and to help in the sensors choice for the full scale level.
A 3D steady state CFD analysis have been performed, to have a full comprehension of the phenomenon involving vortex flow field inside the combustion chamber. It has been discovered that the most important parameter is the temperature gradient produced by the combustion process, that increase the axial velocity straightening the fluid lines.
This numerical analysis has been used also to characterize the motor performance, simulating different chamber configurations: a) different grain port diameter, to study the combustion at different burning time, b) variation in oxidizer mass flow, involving throttling effects and c) different combustion chamber configuration, using mixer-like devices and pre/post-combustion chambers.
An analytical tool has been developed, using steady state Navier-Stokes in cylindrical coordinates: results showed a forced vortex behaviour of the velocity profile of the fluid field. Moreover, a pressure gradient in radial direction has been discovered. This knowledge helped in the selection of the correct pick-up point of the pressure in combustion chamber, in a position (near the nozzle) where this effect is negligible.
Throttling device selection has devised the use of a needle valve. The selected model, prior to its use in burning test, has been characterized with water (in a preliminary phase) and nitrous oxide in cold test.
The experimental campaign has taken the majority of this work: first cold test have been performed to evaluate the oxidizer mass flow with both axial and vortex injection, discovering that they have the same discharge coefficient; measured mass flow was 350g/s.
Burning test involved all previous investigated field: studying axial and vortex injection have been discovered that the second technique gives an increase in combustion efficiency from 73% to 91%, and an increase in regression rate of 41% with the a coefficient going from 0.19mm/s in the axial case to 0.31mm/s in the vortex case. Pressure oscillations in combustion chamber were reduced from 7.5% to 3.8%.
Throttling has been performed in two levels: 75% and 50%. In both cases pressure oscillations remained the same, while combustion efficiency dropped to a value of 85% for the first case and 82% for last. Regression rate has not changed appreciably.
Last part regarded combustion chamber configuration: we found out that the use of mixer-like devices enhances the regression rate of 6% and raise the combustion efficiency up to 96%. Use of a longer pre-combustion chamber (from 10mm to 17mm) has similar but lower effect: combustion efficiency has an increment of 3%. In both cases, pressure chamber oscillation drop to a level lower than 2%.I motori ibridi fanno parte di un promettente ramo della propulsione aerospaziale. Sono già stati dimostrati diversi benefici, quali il fatto che siano "green", a basso costo e con una elevata sicurezza nelle operazioni. In quest'ottica, con questa tesi si vuole caratterizzare un motore ibrido a spinta variabile da utilizzarsi per collision avoidance in formation flight. Lo scopo è di incrementare un motore già esistente con le tecnologie allo stato dell'arte, ed in particolare cercare di mitigare gli effetti negativi classici degli ibridi come il basso regression rate ed efficienza di combustione. La scelta dei propellenti è ricaduta su N2O pressurizzato come ossidante e paraffina come propellente. La prima fase del progetto ha visto la creazione di un modello transient 0-D analitico per il design preliminare del motore. In particolare, si sono ricavate le dimensioni di grano, ugello e camera di combustione e la portata di massa obiettivo. Successivamente, è stato analizzato il campo di moto fluido interno alla camera di combustione tramite un codice stazionario 3-D CFD. Il risultato emerso è che il parametro fondamentale per la fluidodinamica interna è il gradiente di temperatura prodotto dalla combustione, che accelera la componente assiale di velocità raddrizzando le linee fluide. Questo stesso strumento è stato impiegato anche per caratterizzare in via numerica le configurazioni di motore che sono state poi testate. Tre gruppi di analisi sono state effettuate: a) differente portata di ossidante, per studiare il fenomeno del throttling dal punto di vista fluidodinamico, b) diverso diametro di porta del grano, per studiare il comportamento del motore in diversi istanti temporali e c) differenti configurazioni di camera di combustione, con l'impiego di componenti tipo mixer o pre/post-camere. Un tool analitico che utilizza le equazioni di Navier-Stokes in coordinate cilindriche è stato sviluppato con lo scopo di aumentare la conoscenza del campo di moto. In particolare, è stato scoperto che il profilo di velocità del flusso segue un vortice forzato, ed è presente un gradiente di pressione in senso radiale. Questa informazione ha permesso un più accurato posizionamento dei sensori, in modo da avere un minore effetto gradiente nella misura del segnale di pressione. Il throttling ha richiesto una selezione di dispositivi regolatori di flusso: la scelta è caduta su una valvola a spillo. Questa è stata caratterizzata dal punto di vista sperimentale mediante test a freddo sia con acqua che con l'ossidante reale utilizzato nei successivi test a fuoco. La campagna sperimentale è iniziata con dei test a freddo per caratterizzare i due iniettori, assiale e vortex; il risultato è che hanno la stessa portata (350g/s) a parità di salto di pressione, e quindi lo stesso coefficiente di scarica. Successivamente sono state studiate le performance con dei burn test: con la metodologia di iniezione vortex si ottengono incrementi sia di regression rate(+41%) che di efficienza di combustione (si passa da 73% a 91%). Le oscillazioni di pressione in camera scendono da un valore sulla media di pressione di 7.5% al 3.8%. Il throttling è stato studiato in due livelli: 75% e 50% della portata di massa di ossidante. La riduzione di portata è stata accompagnata da una riduzione di efficienza di combustione (85% per il primo caso, 82% per il secondo), mentre le oscillazioni di pressione sono rimaste le stesse. L'ultima parte ha visto lo studio di diverse configurazioni della camera di combustione. In particolare, si è visto che dispositivi tipo mixer permettono un incremento di efficienza fino al 96%, ed un aumento del regression rate del 6%. Anche l'impiego di pre-camere più lunghe (da 10mm a 17mm) fornisce prestazioni simili ma con incrementi minori: l'efficienza è innalzata del 3%. In entrambi i casi vi è un effetto positivo nella riduzione delle oscillazioni di pressione, che si attestano ad un valore inferiore al 2%.
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Nastic, Aleksandra. "Cold Gas Dynamic Spray Impact: Metallic Bonding Pre-Requisites and Experimental Particle In-Flight Temperature Measurements." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42086.
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The impact phenomena of high velocity micron-size particles, although commonly considered and described as detrimental in numerous engineering applications, can be used in a beneficial way if properly understood and controlled. The Cold Gas Dynamic Spray (CGDS) process, known as a surface modification, repair and additive manufacturing process, relies on such high velocity impacts. In the process, solid particles are accelerated by a supersonic gas flow to velocities up to 1200 m/s and are simultaneously heated to temperatures lower than their melting point. When propelled under proper velocity and temperature, the particles can bond onto a target surface. This bonding is caused by the resulting interfacial deformation processes occurring at the contact interface. Hence, the process relies heavily on the gas/particle and particle/substrate interactions.
Although numerous experimental and/or numerical studies have been performed to describe the phenomena occurring during particle flight and impact in the CGDS process, numerous phenomena remain poorly understood. First, the effect of substrate surface topographical condition on the particle deformation and ability to successfully adhere, i.e. atomically and/or mechanically, has not been thoroughly investigated such that its influence is not well understood. Another aspect of the process that is generating the largest gap between experimental and numerical studies in the field is the lack of particle in-flight temperature measurements. Obtaining such data has proven to be technically difficult. The challenges stem from the short particle flight time, low particle temperature and small particle size preventing the use of established thermal spray pyrometry equipment. Relatedly, lack of such measurements precludes a proper experimental study of the impact related phenomena at the particle/substrate interface. As a result, the effect of particle size dependent temperature on overall coating properties and atomic bonding relies currently on estimates. Finally, the effect of particle impact characteristics on interfacial phenomena, i.e. grain size and geometry, velocity/temperature, and oxide scale thickness, on adhesion and deformation upon single particle collision has also been scarcely studied for soft particle depositions on hard substrate.
Hence, the current research work aims at studying fundamental aspects of particle/gas heat transfer and particle/substrate impact features in goals to improve the understanding of the CGDS process. Different surface preparation methods will be used to create various surface roughness and topographical features, to provide a clear understanding of the target surface state influence on coating formation and adhesion. Additionally, new equipment relying on novel technology, i.e. high-speed IR camera, will be utilized to obtain particle in-flight temperature readings with sequence recordings. Subsequently, the experimental particle in-flight temperature readings will be used to develop a computational fluid dynamics model in goals to validate currently used Nusselt number correlations and heat transfer equations. The particle size-dependent temperature effect on the particle’s elastic and plastic response to its impact with a targeted surface and its ability to successfully bond and form a coating will be studied experimentally. A thorough CFD numerical work, based on experimental findings, will be included to provide full impact characteristics (velocity, temperature, size and trajectory) of successfully deposited particles. Finally, the numerical results will be utilized in the ensuing study to correlate single particle deformation, adhesion and interfacial features to impact characteristics. A finite element model will be included to investigate the effect of particle size dependent temperature on single particle interfacial pressure, temperature and bonding ability.
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Miller, P. "An experimental study of sonic and supersonic nozzles and their application to high pressure ejectors for aircraft attitude control." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380891.
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A study has been conducted of reaction controls for VSTOL aircraft using thrust augmenting ejector techniques. Rapid mixing nozzles have been developed for high pressure ejectors. Mass flow increases for sonic nozzles of up to 50\ at x/D=8 were recorded, compared with plain circular nozzles. Their use was found to improve the thrust performance of a simple ejector by 9\, and larger increases are believed possible. Results from an ejector performance prediction model were successfully compared with experimental data. The use of rapid mixing nozzles in a practical ejector design has been assessed. It is predicted that a maximum thrust increment of 20\ ·could be achieved, compared with a simple fully expanded jet flow.
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Vignotto, Davide. "Analysis of the in-Flight Performance of a Critical Space Mechanism." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/323575.
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Gravitational waves detection is a challenging scientific objective, faced by scientist in the last 100 years, when Einstein theorized their existence. Despite multiple attempts, it was only in 2016 that the first observation of a gravitational wave was officially announced. The observation, worth a Nobel Prize, was made possible thanks to a worldwide collaboration of three large ground-based detectors. When detecting gravitational waves from ground, the noisy environment limits the frequency bandwidth of the measurement. Thus, the type of cosmic events that are observable is also limited. For this reason, scientists are developing the first gravitational waves detector based in space, which is a much quieter environment, especially in the sub-Hertz bandwidth. The space-based detector is named laser interferometer space antenna (LISA) and its launch is planned for 2034. Due to the extreme complexity of the mission, involving several new technologies, a demonstrator of LISA was launched and operated between 2015 and 2017. The demonstrator mission, called LISA Pathfinder (LPF), had the objective to show the feasibility of the gravitational waves observation directly from space, by characterizing the noise affecting the relative acceleration of two free falling bodies in the milli-Hertz bandwidth. The mission was a success, proving the expected noise level is well below the minimum requirement.
The free-falling bodies of LPF, called test masses (TMs), were hosted inside dedicated electrode housings (EH), located approximately 30 cm apart inside the spacecraft. When free falling, each TM stays approximately in the center of the EH, thus having milli-meter wide gaps within the housing walls. Due to the presence of such large gaps, the TMs were mechanically constrained by dedicated mechanisms (named CVM and GPRM) in order to avoid damaging the payload during the launch phase and were released into free fall once the spacecraft was in orbit. Prior to the start of the science phase, the injection procedure of the TMs into free-fall was started. Such a procedure brought each TM from being mechanically constrained to a state where it was electro-statically controlled in the center of the EH. Surprisingly, the mechanical separation of the release mechanism from the TM caused unexpected residual velocities, which were not controllable by the electrostatic control force responsible for capturing the TM once released. Therefore, both the TMs collided with either the surrounding housing walls or the release mechanism end effectors. It was possible to start the science phase by manually controlling the release mechanism adopting non-nominal injection strategies, which should not be applicable in LISA, due to the larger time lag. So, since any release mechanism malfunctioning may preclude the initialization of LISA science phase, the GPRM was extensively tested at the end of LPF, by means of a dedicated campaign of releases, involving several modifications to the nominal injection procedure. The data of the extended campaign are analyzed in this work and the main conclusion is that no optimal automated release strategy is found for the GPRM flight model as-built configuration that works reliably for both the TMs producing a nominal injection procedure. The analysis of the in-flight data is difficult since the gravitational referencesensor of LPF is not designed for such type of analysis. In particular, the low sampling frequency (i.e., 10 Hz) constitutes a limiting factor when detecting instantaneous events such as collisions of the TM. Despite the difficulties of extracting useful information on the TM residual velocity from the in-flight data, it is found that the main cause of the uncontrollable state of the released TM is the collision of the TM with the plunger, i.e., one of the end-effectors of the GPRM. It is shown that the impact is caused by the oscillation of the plunger or by the elastic relaxation of the initial preload force that holds the TM. At the end of the analysis, some improvements to the design of the release mechanism are brie y discussed, aimed at maximizing the probability of performing a successful injection procedure for the six TMs that will be used as sensing bodies in the LISA experiment.
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Stanger, Jonathan Jeffrey. "Experimental Assessment of Charge Flow in Electrospinning." Thesis, University of Canterbury. Mechanical Engineering, 2013. http://hdl.handle.net/10092/8447.
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Electrospinning is a method of using high voltage electric fields to transform polymer solutions into nano-scale fibres. The field has seen significant work on processing different polymers and their resulting fibres but less work has focused the electrospinning process itself. The aim of this thesis is to present experimental observations of charge behaviour in the electrospinning process in the context of the underlying physics typically used to describe electrospinning. This thesis presents a review of existing methods of measuring aspects of the electrospinning process, and reviews published mathematical models of the process as representative examples of the current understanding of the underlying physics that drive the electrospinning phenomena. A novel measurement technique is introduced - high frequency data capture of the electric current flow simultaneously at the high voltage and collector electrode. This is used in three ways: to examine bulk charge density, to measure fibre flight time, and to quantify charge lost from the fibre in flight. Charge density is studied by comparing current and mass flow at the Taylor cone under a wide range of conditions. For 8% PVOH in water a constant bulk charge density was found of 7.7 C/kg. Flight time is studied by determining the time from the application of high voltage to the charged fibre first arriving at the collector electrode. It was found that for 8% PVOH the flight time depended strongly on applied voltage while electrode distance had a negligible effect. Charge loss was studied by comparing the magnitude of the simultaneous current flows in the quasi-steady state to determine if the charge flowing into the Taylor cone arrives with the fibre at the collector. For 8% PVOH, 8% PVOH with ionic salt, 9% PVOH in water and 18% PVB in ethanol, it was found that charge is always lost.
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Heijkenskjöld, Filip. "Experimental Techniques for Studies in Atomic & Molecular Physics." Doctoral thesis, Uppsala University, Department of Physics and Materials Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9295.
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This thesis is based on a selection of six different experimental techniques used for studies in atomic and molecular physics. The techniques analysed in the thesis are compared to find similarities in strategies and ways to avoid sources of error.
Paper 1 deals with collision based spectroscopy with 60 keV Xe6+ ions on sodium and argon gas targets. Information on energy of Rydberg states in Xe5+ is unveiled by optical spectroscopy in the wavelength range from vacuum ultraviolet (VUV) to visible. In paper 2, the fast ion-beam laser spectroscopy (FIBLAS) is adapted for measuring hyperfine structure of barium isotopes in an isotopically pure ion-beam. This techniques involves changing the isotope during the measurement to minimize sources of error in measurement and enhance the signal from lesser abundant isotopes. The FIBLAS technique is used in paper 3 to study samarium ions. The ions are optically pumped and the recorded optical nutation is used to measure transition probabilities. This technique eludes the difficulties inherent in relative intensity measurements of all the radiative transitions from an excited state. In Paper 4, optical emission spectroscopy is used in the VUV region to study noble gas mixture discharges. The source of the emission bands near the resonance lines of krypton and xenon are found to be heteronuclear dimers. In paper 5, radiation from a pulsed argon plasma with admixture of nitrogen is studied with time resolved spectroscopy in the VUV and ultraviolet wavelength ranges to investigate the mechanism of energy transport. A metastable state of atomic argon is found to be an important source of energy to many radiative processes. In Paper 6, photoelectron spectroscopy (PES) on thiophene, on 3-bromothiophene and on 3,4-dibromothiophene using time-of-flight photoelectron-photoelectron coincidence technique and conventional PES to investigate the onset of double ionisation compared to the onset of single ionisation in molecules.
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Sahoo, Dipankar. "Experimental analysis of the vorticity and turbulent flow dynamics of a pitching airfoil at realistic flight (helicopter) conditions." Diss., Texas A&M University, 2008. http://hdl.handle.net/1969.1/85893.
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Improved basic understanding, predictability, and controllability of vortex-dominated and unsteady aerodynamic flows are important in enhancement of the performance of next generation helicopters. The primary objective of this research project was improved understanding of the fundamental vorticity and turbulent flow physics for a dynamically stalling airfoil at realistic helicopter flight conditions. An experimental program was performed on a large-scale (C = 0.45 m) dynamically pitching NACA 0012 wing operating in the Texas A&M University large-scale wind tunnel. High-resolution particle image velocimetry data were acquired on the first 10-15% of the wing. Six test cases were examined including the unsteady (k>0) and steady (k=0) conditions. The relevant mechanical, shear and turbulent time-scales were all of comparable magnitude, which indicated that the flow was in a state of mechanical non-equilibrium, and the expected flow separation and reattachment hystersis was observed. Analyses of the databases provided new insights into the leading-edge Reynolds stress structure and the turbulent transport processes. Both of which were previously uncharacterized. During the upstroke motion of the wing, a bubble structure formed in the leading-edge Reynolds shear stress. The size of the bubble increased with increasing angle-of-attack before being diffused into a shear layer at full separation. The turbulent transport analyses indicated that the axial stress production was positive, where the transverse production was negative. This implied that axial turbulent stresses were being produced from the axial component of the mean flow. A significant portion of the energy was transferred to the transverse stress through the pressure-strain redistribution, and then back to the transverse mean flow through the negative transverse production. An opposite trend was observed further downstream of this region.
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Radhakrishnan, Anand M. "An experimental investigation of ground effect on a quad tilt rotor in hover and low speed forward flight." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/4094.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: 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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Rezende, M. A. "The aerobic power output of the chief flight muscle of birds (M. pectoralis) : A theoretical and experimental investigation." Thesis, University of Bristol, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373848.
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Bennett, April M. "Active Regulation of Speed During a Simulated Low-altitude Flight Task: Altitude Matters!" Wright State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=wright1167238078.
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Majdi, Saman. "Experimental Studies of Charge Transport in Single Crystal Diamond Devices." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-173599.
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Diamond is a promising material for high-power, high-frequency and high- temperature electronics applications, where its outstanding physical properties can be fully exploited. It exhibits an extremely high bandgap, very high carrier mobilities, high breakdown field strength, and the highest thermal conductivity of any wide bandgap material. It is therefore an outstanding candidate for the fastest switching, the highest power density, and the most efficient electronic devices obtainable, with applications in the RF power, automotive and aerospace industries. Lightweight diamond devices, capable of high temperature operation in harsh environments, could also be used in radiation detectors and particle physics applications where no other semiconductor devices would survive. The high defect and impurity concentration in natural diamond or high-pressure-high-temperature (HPHT) diamond substrates has made it difficult to obtain reliable results when studying the electronic properties of diamond. However, progress in the growth of high purity Single Crystal Chemical Vapor Deposited (SC-CVD) diamond has opened the perspective of applications under such extreme conditions based on this type of synthetic diamond. Despite the improvements, there are still many open questions. This work will focus on the electrical characterization of SC-CVD diamond by different measurement techniques such as internal photo-emission, I-V, C-V, Hall measurements and in particular, Time-of-Flight (ToF) carrier drift velocity measurements. With these mentioned techniques, some important properties of diamond such as drift mobilities, lateral carrier transit velocities, compensation ratio and Schottky barrier heights have been investigated. Low compensation ratios (ND/NA) < 10-4 have been achieved in boron-doped diamond and a drift mobility of about 860 cm2/Vs for the hole transit near the surface in a lateral ToF configuration could be measured. The carrier drift velocity was studied for electrons and holes at the temperature interval of 80-460 K. The study is performed in the low-injection regime and includes low-field drift mobilities. The hole mobility was further investigated at low temperatures (10-80 K) and as expected a very high mobility was observed. In the case of electrons, a negative differential mobility was seen in the temperature interval of 100-150K. An explanation for this phenomenon is given by the intervally scattering and the relation between hot and cold conduction band valleys. This was observed in direct bandgap semiconductors with non-equivalent valleys such as GaAs but has not been seen in diamond before. Furthermore, first steps have been taken to utilize diamond for infrared (IR) radiation detection. To understand the fundamentals of the thermal response of diamond, Temperature Coefficient of Resistance (TCR) measurements were performed on diamond Schottky diodes which are a candidate for high temperature sensors. As a result, very high TCR values in combination with a low noise constant (K1/f) was observed.
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Paul, Sanjoy. "CHARGE TRANSPORT IN LIQUID CRYSTALLINE SMECTIC AND DISCOTIC ORGANIC SEMICONDUCTORS: NEW RESULTS AND EXPERIMENTAL METHODOLOGIES." Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1469836810.
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Fassmann, Wesley N. "An Experimental Study of Bio-Inspired Force Generation by Unsteady Flow Features." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5316.
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As the understanding of the workings of the biological world expands, biomimetic designs increasingly move into the focus of engineering research studies. For this thesis, two studiesinvolving leading edge vortex generation for lift production as observed in nature were explored intheir respective flow regimes. The first study focused on the steady state analysis of streamwise vortices generated byleading edge tubercles of an adult humpback whale flipper. A realistic scaled model of a humpbackflipper was fabricated based on the 3D reconstruction from a sequence of 18 images taken whilecircumscribing an excised flipper of a beached humpback whale. Two complementary modelswith smooth leading edges were transformed from this original digitized model and fabricatedfor testing to further understand the effect of the leading edge tubercles. Experimentally-obtainedforce and qualitative flow measurements were used to study the influence of the leading edgetubercles. The presence of leading edge tubercles are shown to decrease maximum lift coefficient(Cl ), but increase Cl production in the post-stall region. By evaluating a measure of hydrodynamicefficiency, humpback whale flipper geometry is shown to be more efficient in the pre-stall regionand less efficient in the post-stall region as compared to a comparable model with a smooth leadingedge. With respect to a humpback whale, if the decrease in efficiency during post-stall angles ofattack was only required during short periods of time (turning), then this decrease in efficiencymay not have a significant impact on the lift production and energy needs. For the pursuit ofbiomimetic designs, this decrease in efficiency could have potential significance and should beinvestigated further. Qualitative flow measurements further demonstrate that these force results aredue to a delay of separation resulting from the presence of tubercles.The second study investigated explored the effects of flapping frequency on the passive flowcontrol of a flapping wing with a sinusoidal leading edge profile. At a flapping frequency of f =0.05 Hz, an alternating streamwise vortical formation was observed for the sinusoidal leading edge,while a single pair of vortices were present for the straight leading edge. A sinusoidal leading edgecan be used to minimize spanwise flow by the generation of the observed alternating streamwisevortices. An increase in flapping frequency results in these streamwise vortices becoming stretchedin the path of the wing. The streamwise vortices are shown to minimize spanwise flow even afterbeing stretched. Once instabilities are formed at f ≥ 0:1 Hz due to velocity shearing generatedby the increase in cross-radial velocity, the alternating streamwise vortices begin to break downresulting in a increase of spanwise flow.
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Sansou, Florian. "Contrôle actif d'un micro-drone convertible face à la turbulence." Electronic Thesis or Diss., Toulouse, École nationale de l’aviation civile, 2024. https://enac.hal.science.
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L'objectif du projet CATMAV est d'étudier le contrôle d'un micro-drone de type « tilt-wing » en environnement turbulent. La configuration générale est basée sur le principe d'un drone avion avec un fuselage classique dont l'aile est capable de basculer au cours du vol. Ce type de configuration convertible a de nombreux atouts dont une capacité de décollage et atterrissage vertical tout en gardant de bonnes performances en vol de croisière. Une importante limitation est la robustesse en présence de turbulences, notamment en milieu urbain, montagneux ou maritime. Une des innovations de ce projet est l'utilisation d'une sonde capable de mesurer le vecteur vent local ainsi que les turbulences. Ce capteur est en cours de développement au sein du programme drone de l'EnacThis PhD thesis aims at studying the control of a tilt-wing mini-UAV in turbulent environments. This type of configuration has many benefits with the capability to takeoff and land vertically while keeping good flight performances and the main body of the plane stays horizontal. However, it may be highly sensitive to wind gust and turbulences, especially in urban, mountain or maritime areas. The main objective is to contribute to the safety and flight performances of this type of flying platform. The UAV Program at Enac is currently developing a 5-hole probe to be used as a local wind and turbulence sensor. The work will concentrate on the integration of these aerological data into the control laws to achieve a faster and better dynamic response to gusts
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Bykov, A. (Alexander). "Experimental investigation and numerical simulation of laser light propagation in strongly scattering media with structural and dynamic inhomogeneities." Doctoral thesis, University of Oulu, 2010. http://urn.fi/urn:isbn:9789514261558.
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Abstract
Light scattering diagnostics of turbid media containing both structural and dynamic inhomogeneities is currently of significant importance. One of the important directions in modern light scattering diagnostics is the development of methods for probing biological media with visible- and near-infrared radiation allowing for visualization of the biotissue structure. Optical methods for studying the biotissue structure and characterization of its optical properties are very promising and have been rapidly developing during the past decade.
The present work is aimed at improving and discovering new potentials of currently existing methods of laser diagnostics of biological tissues containing both structural and dynamic inhomogeneities. In particular, the feasibilities of spatially resolved reflectometry and time-of-flight techniques for the problem of noninvasive determination of glucose level in human blood and tissues were examined both numerically and experimentally. The relative sensitivities of these methods to changes in glucose level were estimated. Time-of-flight technique was found to be more sensitive.
The possibilities of Doppler optical coherence tomography for imaging of dynamic inhomogeneities with high resolution were considered. This technique was applied for the first time for the imaging of complex autowave cellular motility and cytoplasm shuttle flow in the slime mold Physarum polycephalum. The effect of multiple scattering on the accuracy of the measured flow velocity profiles for the case of single flow and for the case of the flow embedded into the static medium with strong scattering was studied. It was shown that this effect causes significant distortion to the measured flow velocity profiles and it is necessary to take this into account while making quantitative measurements of flow velocities.
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Ozsoy, Serhan. "Vibration Induced Stress And Accelerated Life Analyses Of An Aerospace Structure." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12606966/index.pdf.
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Fatigue failure of metallic structures operating under dynamic loading is a
common occurrence in engineering applications. It is difficult to estimate the
response of complicated systems analytically, due to structure’
s dynamic characteristics and varying loadings. Therefore, experimental, numerical or a combination of both methods are used for fatigue evaluations. Fatigue failure can occur on systems and platforms as well as components to be mounted on the platform. In this thesis, a helicopter&
#8217
s Missile Warning Sensor - Cowling assembly is analyzed. Analytical, numerical and experimental approaches are used wherever necessary to perform stress and fatigue analyses. Operational flight tests are used for obtaining the loading history at the analyzed location by using sensors. Operational vibration profiles are created by synthesizing the data (LMS Mission Synthesis). Numerical fatigue analysis of the assembly is done for determining the natural modes and the critical locations on the assembly by using a finite element model (MSC Fatigue). In addition, numerical multiaxial PSD analysis is performed for relating the experimental results (Ansys). Residual stresses due to riveting are determined (MSC Marc) and included in experimental analysis as mean stresses. Bolt analysis is performed analytically (Hexagon) for keeping the v assembly stresses in safe levels while mounting the experimental prototype to the test fixture. Fatigue tests for determining the accelerated life parameters are done by an electromagnetic shaker and stress data is collected. Afterwards, fatigue test is performed for determining whether the assembly satisfies the required operational life. Resonance test is performed at the frequency in which the critical location is at resonance, since there was no failure observed after fatigue testing. A failure is obtained during resonance test. At the end of the study, an analytical equation is brought up which relates accelerated life test durations with equivalent alternating stresses. Therefore, optimization of the accelerated life test duration can be done, especially in military applications, by avoiding the maximum stress level to reach or exceed the yield limit.
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Boke, Cem. "Combining and analyzing the tanker and aircrew scheduling heuristics." View thesis, 2003. http://handle.dtic.mil/100.2/ADA412689.
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Thesis (M.S.)--Air Force Institute of Technology, 2003.Title from title screen (viewed Oct. 28, 2003). "March 2003." Vita. "AFIT/GOR/ENS/03-04." Includes bibliographical references (leaves 69-70). Also issued in paper format.
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Giles, Roger. "Design and development of a time of flight fast scattering spectrometer : a quantitative surface analysis technique and a new approach towards the experimental investigation of the surface particle interactions." Thesis, Aston University, 1995. http://publications.aston.ac.uk/8061/.
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A new surface analysis technique has been developed which has a number of benefits compared to conventional Low Energy Ion Scattering Spectrometry (LEISS). A major potential advantage arising from the absence of charge exchange complications is the possibility of quantification. The instrumentation that has been developed also offers the possibility of unique studies concerning the interaction between low energy ions and atoms and solid surfaces. From these studies it may also be possible, in principle, to generate sensitivity factors to quantify LEISS data. The instrumentation, which is referred to as a Time-of-Flight Fast Atom Scattering Spectrometer has been developed to investigate these conjecture in practice. The development, involved a number of modifications to an existing instrument, and allowed samples to be bombarded with a monoenergetic pulsed beam of either atoms or ions, and provided the capability to analyse the spectra of scattered atoms and ions separately. Further to this a system was designed and constructed to allow incident, exit and azimuthal angles of the particle beam to be varied independently. The key development was that of a pulsed, and mass filtered atom source; which was developed by a cyclic process of design, modelling and experimentation. Although it was possible to demonstrate the unique capabilities of the instrument, problems relating to surface contamination prevented the measurement of the neutralisation probabilities. However, these problems appear to be technical rather than scientific in nature, and could be readily resolved given the appropriate resources. Experimental spectra obtained from a number of samples demonstrate some fundamental differences between the scattered ion and neutral spectra. For practical non-ordered surfaces the ToF spectra are more complex than their LEISS counterparts. This is particularly true for helium scattering where it appears, in the absence of detailed computer simulation, that quantitative analysis is limited to ordered surfaces. Despite this limitation the ToFFASS instrument opens the way for quantitative analysis of the 'true' surface region to a wider range of surface materials.
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Chen, Xianlong. "Development of a low-cost in-situ material characterization method and experimental studies of smart composite structures." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCA002/document.
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Les structures composites intégrant des transducteurs piézoélectriques au cœur de la matière sont utilisées pour leur capacité à modifier leurs propriétés mécaniques en fonction de l’environnement, à contrôler leur intégrité structurale et à interagir avec l’homme ou avec d’autres structures.Ce travail se concentre sur les phases de conception préliminaire des structures composites intelligentes. Ces phases ne représentent que 5% du coût total d’un projet, mais conditionnent 80% du coût final du produit. Les principaux problèmes rencontrés lors de ces phases de conception préliminaire portent sur la détermination des propriétés matériau des transducteurs piézoélectriques et des matériaux composites utilisés, de l'influence de l'emplacement des transducteurs dans la structure ainsi que de l’influence du processus de fabrication, de la température et des endommagements sur le comportement final des structures composites intelligentes.Dans le processus de fabrication développé à l’Université de Technologies Belfort-Montbéliard (UTBM), l’élément-clé est un produit semi-fini appelé “soft layer”. Cette couche permet d’intégrer le réseau de transducteurs piézoélectriques au cœur de la structure composite. Le processus de fabrication de la “soft layer” ainsi que celui des structures intelligentes sont abordés dans cette thèse.Afin de trouver des solutions aux problèmes décrits ci-dessus, deux méthodes de caractérisation de composites intelligents ou adaptatifs sont présentées et utilisées : la méthode dite Resonalyser et la méthode du temps de vol. Après des études expérimentales et une comparaison des résultats obtenus, la méthode du temps de vol a été choisie comme méthode principale en raison de son faible coût de mise en œuvre et du fait qu’il s’agit d’une méthode de caractérisation in-situ. De plus, une nouvelle méthode appelée méthode CMB, basée sur la méthode du temps de vol a été développée afin de pouvoir facilement et rapidement extraire les constantes élastiques, en particulier le coefficient de Poisson.Des analyses expérimentales de sensibilité appliquées aux composites adaptatifs ont été effectuées.Premièrement, l’étude de l’influence de l’emplacement des transducteurs démontre qu’il est nécessaire de tenir compte de la position de la “soft layer” dans la modélisation du comportement de produit final. La position de cette couche dans l’épaisseur du produit a une influence notable sur les fréquences propres ainsi que les amplitudes modales de la structure. Cependant, l’ajout de la “soft layer” n’accroît pas le taux d’amortissement de la structure finale; et sa position dans l’épaisseur n’a aucune influence sur ce taux d’amortissement. La propagation des ondes de Lamb à l’intérieur du composite n’est pas impactée par le “soft layer”.Deuxièmement, l’étude de l’impact du processus de la fabrication nous renseigne sur l’influence notable des divers paramètres de réglage du processus de fabrication sur le comportement final de la structure composite intelligente.Troisièmement, l’étude de l’influence de la température sur des structures constituées de différents matériaux composites montre que le module de Young du produit final décroît quand la température augmente. Mais la diminution du module de Young en fonction de la température est différente selon les et les types de matériaux et les directions des fibres, en particulier pour les structures composites unidirectionnelles. De plus, cette étude montre également la sensibilité de la méthode du temps de vol vis-à-vis de la température. Ce dernier point est par ailleurs consolidé par la comparaison avec des résultats obtenus par une méthode de caractérisation ex-situ standard : l'analyse dynamique de la mécanique (DMA).Enfin, l'étude de l'impact des dommages mécaniques fournit une assez bonne référence pour les recherches futures. De cette façon, il est clair qu’une méthode de temps de vol peut être utilisée dans la surveillance de la santé structuraleThe composite structures embedding piezoelectric implants are developed due to their abilities of modifying mechanical properties according to the environment, of keeping their integrity, of interacting with human beings or with other structures.This study is focused on the preliminary design stages of smart composite structures, which represent only 5% of the total costs of a project, whereas 80% of the life cycle cost are set during the preliminary study phases. The top few problems during the preliminary design of smart composite structures are addressed in this work such as the determination of the material properties of the piezoelectric transducers and composite material used, the influence of transducers location, manufacturing process, temperature and damage on the behavior of the smart composite structures.Due to the manufacturing process developed at the Université de Technologie de Belfort-Montbéliard (UTBM), the most important element is a semi-finished product called “soft layer”. This special layer is used to embed the transducers system into the composite structures. The manufacturing process of “soft layer” as well as the smart composite structures are compiled in this report.In order to solve the problems described above, two characterization methods of composite material (Resonalyser method and Time-of-Flight method (T-o-F method)), are introduced and discussed. After experimental studies and comparing the results of these two methods, the T-o-F method is chosen as the main method for the following studies due to the fact that it is a low-cost and in-situ characterization method. Furthermore, a new method based on the T-o-F method is developed to easily and quickly extract the elastic constants, in particular the Poisson’s ratio.Experimental sensitivity analyses applied to the smart composite structures are performed with respect to the problems describes above. First of all, the study of the influence of transducers location demonstrates that the "soft layer” cannot be neglected to model the behavior of the final product. In particular, the through-the-thickness position has an influence on the eigenfrequencies and the modal amplitudes. However, the "soft layer” does not increase the overall damping ratio of the final structures and the through-the-thickness position of the "soft layer” has no influence on the damping ratios. The Lamb wave propagation inside the composite material is not impacted by the "soft layer”. Secondly, the study of the impact of manufacturing process demonstrates that the impact of variability of parameters due to the manufacturing process is very important on the final response of the structure. Thirdly, the study of the influence of temperature on different kinds of smart composite structures proves that when temperature increases, the Young’s modulus of the smart composites decreases. But the attenuation of Young’s modulus according to temperature is different along different fiber directions, especially for the unidirectional composite structures. Furthermore, in this study, the sensitivity of Time-of-Flight method with respect to temperature is well proved by comparing the results with a traditional method like Dynamic-Mechanical Analysis (DMA). Last but not least, the study of the impact of the mechanical damage gives a quite good reference for the future investigations. Along this way, it is possible to use a Time-of-Flight method in Structural Health Monitoring. In addition, some smart composite structures manufactured by the research team are given and their potential applications are discussed
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Mirus, Matthew M., Sergey V. Tokalov, Gerald Wolf, Jerilyn Heinold, V. Prochnow, and Nasreddin Abolmaali. "Noninvasive assessment and quantification of tumour vascularisation using MRI and CT in a tumour model with modifiable angiogenesis – An animal experimental prospective cohort study." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232305.
Full textAbstract:
Background
To investigate vascular-related pathophysiological characteristics of two human lung cancers with modifiable vascularisation using MRI and CT.
Methods
Tumour xenografts with modifiable vascularisation were established in 71 rats (approval by the Animal Care Committee was obtained) by subcutaneous transplantation of two human non-small-cell lung cancer (NSCLC) cells (A549, H1299) either alone or co-transplanted with vascular growth promoters. The vascularity of the tumours was assessed noninvasively by MRI diffusion-weighted-imaging (DWI), T2-weighted, and time-of-flight (TOF) sequences) as well as contrast-enhanced CT (CE-CT), using clinical scanners. As a reference standard, histological examinations (CD-31, fluorescent beads) were done after explantation.
Results
Microvessel density (MVD) was higher in co-transplanted tumours (171 ± 19 number/mm2) than in non-co-transplanted tumours (111 ± 11 number/mm2; p = 0.002). Co-transplanted tumours showed higher growth rates and larger tumour vessels at TOF-MRI as well as larger necrotic areas at CE-CT. In co-transplanted tumours, DWI revealed higher cellularity (lower minimal ADCdiff 166 ± 15 versus 346 ± 27 mm2/s × 10−6; p < 0.001), highly necrotic areas (higher maximal ADCdiff 1695 ± 65 versus 1320 ± 59 mm2/s × 10−6; p < 0.001), and better-perfused tumour stroma (higher ADCperf 723 ± 36 versus 636 ± 51 mm2/s × 10−6; p = 0.005). Significant correlations were found using qualitative and quantitative parameters: maximal ADCperf and MVD (r = 0.326); maximal ADCdiff and relative necrotic volume on CE-CT (r = 0.551); minimal ADCdiff and MVD (r = −0.395).
Conclusions
Pathophysiological differences related to vascular supply in two human lung cancer cell lines with modifiable vascularity are quantifiable with clinical imaging techniques. Imaging parameters of vascularisation correlated with the results of histology. DWI was able to characterise both the extent of necrosis and the level of perfusion.
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Campos, Lucélia de Almeida. "Isolamento e caracterização da delta toxina do veneno de Crotalus durissus terrificus." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-14052012-135435/.
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O veneno de C. d. terrificus tem sido descrito como sendo de pouca complexidade, tendo 4 frações caracterizadas, convulxina, giroxina. crotoxina e crotamina. O presente trabalho visou o isolamento e caracterização da Delta toxina cuja existência havia sido aventada em trabalhos anteriores. Após a realização de uma varredura de tampões em uma coluna de exclusão molecular Superdex-75 acoplada a um sistema FPLC, na presença de três diferentes tampões, chegou-se a uma condição ideal de fracionamento do veneno crotálico. Em seqüência realizou-se a segunda etapa de purificação em sistema HPLC em uma coluna C4, onde foi possível identificar o pico de interesse. O pico puro passou por análises em MALDI-ToF sendo sua massa estimada em 14.074,92 Da, Quando analisado por eletroforese em gel de poiiacrilamida, a delta toxina apresentou massa molecular de cerca de 14 kDa e uma migração anômala, Por eletroforese 2D, a proteína apresentou caráter ácido, com pl entre 4 e 5 e massa molecular de aproximadamente 42 kDa, revelando \"spots\" muito semelhantes podendo ser isoformas com características de uma proteína glicosiiada. Após digestão dos spots com tripsina, os fragmentos foram confrontados com o banco de dados do \"swissprot\", mostrando alto grau de homologia \"até 43% de cobertura\" com a troca ri na, um ativador de protrombina do veneno de Tropidechis carinatus, esses dados foram confirmados com a análise de aminoácidos. De posse desses resultados, optou-se por testar a capacidade da fração purificada de ativar fator X e II, usando substratos sintéticos. Os resultados apontaram para uma ativação direta do fator X, uma vez que não houve ativação do fator II, atividade que também não foi detectada no veneno total. A mesma se mostrou um potente ativador da agregação de forma direta, uma vez que os ensaios de agregação plaquetária foram realizados com plaquetas lavadas, logo na ausência de fatores séricos. Quando os ensaios de agregação foram realizados na presença de alguns inibidores observou-se que nem a atividade metalo proteinase, nem a serino proteinase, tampouco um domínio lectina estavam envolvidos no processo, uma vez que EDTA, benzamidina e D-galactose não inibiram a atividade da proteína. No presente trabalho isolamos a Delta toxina do veneno de C. d. terrificus. A mesma se comportou como previsto por Vital Brazil em 1980, eluindo na posição por ele aventada, sendo uma proteína ativadora de Fator X que ativa agregação plaquetária mesmo em concentrações muito baixas e de massa molecular de 40 kDa levando nos a crer se tratar de um homotrímero cujos componentes são unidos por ligações fracas.The Crotalus durissus terrificus venom has been so far described as being of low complexity, with four major components described: convulxin, gyroxin, crotoxin and crotamine. In recent studies, other components of this venom were characterized as, for example, an analgesic factor. In 1980, Vital Brazil predicted the existence of a toxin which could be involved in platelet aggregation, and named it delta toxin. However, this toxin has never been isolated or characterized. The aim of the present work was to purify and characterize this toxin. After FPLC size exclusion chromatography followed by reverse phase HPLC, an homogeneous fraction was obtained, with a molecular weight of 14,074.92 Da. When analyzed by SOS-PAGE, this toxin presented an anomalous behavior, with a molecular weight of 14 kDa, while in 2D gels, spots around 40 kDa and with an isoelectrical point between 4 and 5 were observed suggesting isoforms with glicosilation microheterogeneity. After trypsin digestion, the fragments were submitted to the swissprot databank showing high homology (43% coverage, 15 matching peptides) with trocarin, a prothrombin activator from Tropidechis carinatus. These data were further confirmed by aminoacid analysis. The toxin was tested for its ability to activate factor II and X using synthetic substrates. Our data indicate a direct activation of factor X. The same toxin also behaved as a potent direct platelet aggregation activator on washed platelets. Assays with specific inhibitors indicate that neither metalloproteinase, nor serinoproteinase or t lectin domains are involved in the aggregating activity, since EDTA, benzamidin and D-galactose did not inhibit the toxin. In the present work, we were able to identify, purify and characterize a new toxin from the brazilian rattlesnake. It behaved as predicted by Vital-Brazil and displayed direct factor X activating properties, also inducing platelet aggregation, even at low concentrations. Our data also indicate that it is probably a homotrimer with the subunities linked by hydrophobic and/or electrostatic interactions.
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Terschlüsen, Joachim A. "Constructing and Commissioning HELIOS – A High Harmonic Generation Source for Pump-Probe Measurements with sub 50 fs Temporal Resolution : The Development of Experimental Equipment for Extreme Ultraviolet Spectroscopy." Doctoral thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-281298.
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This thesis presents HELIOS, an in-house laboratory for time-resolved pump-probe spectroscopy with extreme-ultraviolet (XUV) probe radiation. A wide span of pump wavelengths can be generated using commercial laser equipment while XUV probe radiation is generated via a high harmonic generation process in a noble gas delivering probe photons with energies between 20 eV and 72 eV. The XUV beam path features a time-preserving monochromator and was constructed and built in-house. HELIOS features an overall time resolution of about 50 fs when using 800 nm pump and 41 eV probe photons. An energy resolution of 110 meV at 41 eV photon energy can be achieved. HELIOS features two beamlines. One µ-focus beamline with an XUV focal size of about 20 µm can be used with experiments that require such a small XUV focal size as well as with different end stations. The other beamline features a semi-permanently mounted end station for angle-resolved photoelectron spectroscopy under ultra-high vacuum conditions. Experiments demonstrating the usability of HELIOS and the two beamlines are presented. A pump-probe measurement on graphene demonstrates the capability of determining a large part of the k-space in only one measurement due to the use of an ARTOF angle-resolved time-of-flight electron spectrometer. A non-angle-resolved pump-probe measurement on the conducting polymer PCPDTBT demonstrates the high signal-to-noise ratio achievable at this beamline in non-angle-resolved photoelectron-spectroscopy pump-probe measurements. The usability of the µ-focus beamline is demonstrated with time-resolved measurements on magnetic samples employing an in-house-designed spectrometer. These experiments allow the retrieval of element-specific information on the magnetization within a sample employing the transversal magneto-optical Kerr effect (T-MOKE). Additionally, a Fourier transform spectrometer for the XUV is presented, the concept was tested at a synchrotron and it was used to determine the longitudinal coherence of the XUV radiation at HELIOS.
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López, Zaragoza Juan Pedro. "Magnetically induced forces during LISA Pathfinder in-flight operations." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/671180.
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Les ones gravitatòries van ser predites per Albert Einstein l’any 1915 dintre del marc de la teoria de la Relativitat General. Segons aquesta teoria, la qual representa la vigent comprensió de la interacció gravitatòria, moviments violents en sistemes de grans quantitats de massa generen pertorbacions que es propaguen en l’espai i el temps, transportant amb elles energia del sistema originari. L’any 2015, La col·laboració LIGO va revolucionar el món de la física amb el seu anunci de la detecció de les ones gravitacionals produïdes per la violenta col·lisió de dos forats negrets.
Els detectors terrestres com LIGO veuen limitada la seva capacitat de detecció a freqüències per sota dels Hertz degut al soroll sísmic i d’origen humà. Per aquesta raó l’Agència Espacial Europea (ESA) ha decidit posar en òrbita un observatori d’aquestes característiques a la dècada del 2030. Prèviament, i per tal de provar la tecnologia necessària, el Desembre de 2015 es llençà el satèl·lit LISA Pathfinder (LPF), una missió que tenia com a objectiu posar a prova les tecnologies necessàries per a la detecció d’ones gravitatòries a l’espai. Amb aquesta finalitat el satèl·lit ha dut a terme una mesura pionera a l’espai. Es tracta de situar dues masses de prova separades 38 cm en una caiguda lliure nominalment perfecta, és a dir, que aquestes dues masses només es vegin afectades per la força de la gravetat. Un interferòmetre làser mesura la distància entre les dues masses, essent aquesta la principal mesura científica.
Nombroses forces i diferents efectes poden pertorbar el moviment geodèsic de les masses de prova. La tesi doctoral del candidat s’ha centrat en l’anàlisi de les dades del subsistema de diagnòstic magnètic de LISA Pathfinder. L’objectiu final d’aquest subsistema és el de poder predir amb precisió la contribució del soroll magnètic a la principal mesura científica del satèl·lit. Les masses de prova estan fabricades amb un aliatge d’or i platí per tal de minimitzar el seu moment magnètic. Tot i això, la precisió de l’instrument és suficient per ser sensible a l’acoblament del camp magnètic ambiental amb el moment magnètic de les masses de prova, lo qual produeix forces sobre les masses de prova que l’interferòmetre pot mesurar.
En aquesta tesi s’ha donat una visió de quins són els diferents mecanismes que produeixen aquestes forces magnètiques, s’ha estudiat l’evolució del camp magnètic que afecta les masses de prova i s’han analitzat els experiments magnètics que es van dur a terme durant les operacions científiques del satèl·lit. Tot això ha permès quantificar quina és la contribució deguda als efectes magnètics a les fluctuacions en l’acceleració relativa entre les dos masses de prova.Las ondas gravitacionales fueron predichas por Albert Einstein el año 1915 dentro del marco de la teoría de la Relatividad General. Según esta teoría, la cual representa la vigente comprensión de la interacción gravitatoria, movimientos violentos en sistemas muy masivos generan perturbaciones que se propagan a través del espacio-tiempo, transportando con ellas energía del sistema original. En el año 2015, la colaboración LIGO revolucionó el mundo de la física con su anuncio de la detección de las ondas gravitacionales producidas por la violenta colisión de dos agujeros negros. Los detectores terrestres como LIGO ven limitada su capacidad de detección a frecuencias por debajo del Hertz debido al ruido sísmico i de origen humano. Por esta razón la Agencia Espacial Europea (ESA) ha decidido poner en órbita un observatorio de estas características en la década del 2030. Previamente, i con tal de probar la tecnología necesaria, en Diciembre de 2015 se lanzó el satélite LISA Pathfinder (LPF), una misión que tenía como objetivo poner a prueba las tecnologías necesarias para la detección de ondas gravitacionales en el espacio. Con esta finalidad, el satélite realizó una medida pionera en el espacio. Se trata de situar dos masas de prueba separadas 38 cm en una caída libre nominalmente perfecta, es decir, que estas dos masas solo se vean afectadas por la fuerza de la gravedad. Un interferómetro láser mide la distancia entre las dos masas, siendo esta la principal medida científica. Numerosas fuerzas y diferentes efectos pueden perturbar el movimiento geodésico de las masas de prueba. La tesis doctoral del candidato se ha centrado en el análisis de los datos del subsistema de diagnóstico magnético de LISA Pathfinder. El objetivo final de este subsistema es el de poder predecir con precisión la contribución del ruido magnético a la principal medida científica del satélite. Las masas de prueba están fabricadas con una aleación de oro y platino con tal de minimizar su momento magnético. No obstante, la precisión de la medida del instrumento es tal que nos permite ver el acoplamiento del campo magnético ambiental con el momento magnético de las masas de prueba, lo cual produce fuerzas sobre las masas de prueba que el interferómetro puede medir. En esta tesis se ha dado una visión de cuales son los mecanismos que producen estas fuerzas magnéticas, se ha estudiado la evolución del campo magnético que afecta a las masas de prueba y se han analizado los experimentos magnéticos que se llevaron a cabo durante las operaciones científicas del satélite. Todo esto ha permitido cuantificar cual es la contribución debida a los efectos magnéticos a las fluctuaciones en la aceleración relativa entre las dos masas de prueba.
Gravitational waves were predicted by Albert Einstein in 1915 within the General Relativity theory. According to this theory, which represents the present understanding of the gravitational interaction, violent movements in very massive systems generate perturbations which propagate across the space-time, carrying with them the energy of the original system. In 2015, the LIGO collaboration shocked the world with their announcement of a gravitational wave detection coming from the collision of two black holes. Terrestrial detectors like LIGO have limitations to their detection capacity below the Hertz due to the seismic and human-originated noise. Due to this reason, the European Space Agency (ESA) have decided to put into orbit an observatory of this characteristics in the decade of 2030. Previously, and in order to prove the necessary technology, in December 2015 ESA launched the satellite LISA Pathfinder (LPF), a space mission which had the goal of proving the necessary technologies for the detection of gravitational waves in space. To this end, the satellite performed a pioneer measurement in space. It placed two test masses separated by 38 cm in a nominally perfect free-fall, which means that these two test masses were affected by the force of gravity. A laser interferometer constantly monitored the distance between the two test masses, being this the main scientific measurement of the mission. Several forces and different effects may perturb the geodesic motion of the test masses. The candidate's thesis focused in the analysis of the data from the magnetic diagnostics subsystem of LISA Pathfinder. The final goal of this subsystem is to be able to predict with great accuracy the contribution coming from magnetic effects to the main scientific measurement of the satellite. The test masses were designed with gold-platinum alloy with the objective of minimising their magnetic moment. Nevertheless, the instrument measurement accuracy is so high that we can see the coupling of the environmental magnetic field with the test masses magnetic moment. This produces forces on the test masses that the interferometer can measure. In this thesis we have given a review of which are the mechanisms producing these magnetic forces, we have studied the evolution of the magnetic field affecting the test masses and we have analysed the magnetic experiments performed on-board the satellite during the scientific mission operations. All this allowed us to quantify which is the contribution coming from the magnetic effects to the fluctuations of the relative acceleration between the two test masses.
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Potter, James Jackson. "Input-shaped manual control of helicopters with suspended loads." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50342.
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A helicopter can be used to transport a load hanging from a suspension cable. This technique is frequently used in construction, firefighting, and disaster relief operations, among other applications. Unfortunately, the suspended load swings, which makes load positioning difficult and can degrade control of the helicopter. This dissertation investigates the use of input shaping (a command-filtering technique for reducing vibration) to mitigate the load swing problem. The investigation is conducted using two different, but complementary, approaches. One approach studies manual tracking tasks, where a human attempts to make a cursor follow an unpredictably moving target. The second approach studies horizontal repositioning maneuvers on small-scale helicopter systems, including a novel testbed that limits the helicopter and suspended load to move in a vertical plane. Both approaches are used to study how input shaping affects control of a flexible element (the suspended load) and a driven base (the helicopter). In manual tracking experiments, conventional input shapers somewhat degraded control of the driven base but greatly improved control of the flexible element. New input shapers were designed to improve load control without negatively affecting base control. A method for adjusting the vibration-limiting aggressiveness of any input shaper between unshaped and fully shaped was also developed. Next, horizontal repositioning maneuvers were performed on the helicopter testbed using a human-pilot-like feedback controller from the literature, with parameter values scaled to match the fast dynamics of the model helicopter. It was found that some input shapers reduced settling time and peak load swing when applied to Attitude Command or Translational Rate Command response types. When the load was used as a position reference instead of the helicopter, the system was unstable without input shaping, and adding input shaping to a Translational Rate Command was able to stabilize the load-positioning system. These results show the potential to improve the safety and efficiency of helicopter suspended load operations.
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Chandezon, Frédéric. "Étude expérimentale de la stabilité d'agrégats de sodium multichargés produits par collision d'agrégats neutres avec des ions." Université Joseph Fourier (Grenoble ; 1971-2015), 1994. http://www.theses.fr/1994GRE10201.
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Le but de cette these est d'etudier la stabilite d'un agregat de sodium vis-a-vis d'un exces de charge positive. Dans un premier temps, nous avons procede a la construction de l'experience. La source utilisee pour la formation des agregats est du type thermalisation gazeuse. Avec cette source, nous avons obtenu des agregats froids de quelques atomes jusqu'a environ un millier. Le spectrometre de masse a temps de vol construit pour l'experience utilise un systeme d'acceleration a deux etages type wiley-mclaren, mais avec une focalisation amelioree. Une resolution en masse superieure a 2000 est obtenue vers la masse 1100 uma, et les agregats de sodium monocharges ayant jusqu'a 700 atomes peuvent etre separes. Dans un deuxieme temps, nous avons etudie la production et la stabilite d'agregats de sodium multicharges. L'ionisation sequentielle d'agregats neutres par une impulsion laser permet d'obtenir des agregats multicharges chauds, c'est-a-dire evaporant des atomes. La charge maximale des agregats est limitee par l'energie des photons. L'interaction d'agregats neutres avec des ions montre la coexistence de deux processus d'ionisation: la capture a distance d'electrons par le champ coulombien de l'ion et l'emission statistique d'electrons suite a l'excitation electronique de l'agregat quand un ion le traverse. Lorsque la charge de l'ion augmente, le premier processus devient predominant. Ceci implique une diminution de la temperature des agregats multicharges obtenus qui se traduit experimentalement par une diminution de la taille critique. En conclusion, l'interaction d'agregats neutres avec des ions permet de produire des agregats multicharges, de charge, de taille et de temperature variables. Elle apparait comme une methode de choix pour l'etude de la fragmentation lorsque ces edifices sont instables
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Tirtey, Sandy C. "Characterization of a transitional hypersonic boundary layer in wind tunnel and flight conditions." Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210367.
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Laminar turbulent transition is known for a long time as a critical phenomenon influencing the thermal load encountered by hypersonic vehicle during their planetary re-entry trajectory. Despite the efforts made by several research laboratories all over the world, the prediction of transition remains inaccurate, leading to oversized thermal protection system and dramatic limitations of hypersonic vehicles performances. One of the reasons explaining the difficulties encountered in predicting transition is the wide variety of parameters playing a role in the phenomenon. Among these parameters, surface roughness is known to play a major role and has been investigated in the present thesis.A wide bibliographic review describing the main parameters affecting transition and their coupling is proposed. The most popular roughness-induced transition predictions correlations are presented, insisting on the lack of physics included in these methods and the difficulties encountered in performing ground hypersonic transition experiments representative of real flight characteristics. This bibliographic review shows the importance of a better understanding of the physical phenomenon and of a wider experimental database, including real flight data, for the development of accurate prediction methods.
Based on the above conclusions, a hypersonic experimental test campaign is realized for the characterization of the flow field structure in the vicinity and in the wake of 3D roughness elements. This fundamental flat plate study is associated with numerical simulations for supporting the interpretation of experimental results and thus a better understanding of transition physics. Finally, a model is proposed in agreement with the wind tunnel observations and the bibliographic survey.
The second principal axis of the present study is the development of a hypersonic in-flight roughness-induced transition experiment in the frame of the European EXPERT program. These flight data, together with various wind tunnel measurements are very important for the development of a wide experimental database supporting the elaboration of future transition prediction methods.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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Bongo, Njeng Alex Stéphane. "Experimental study and modeling of hydrodynamic and heating characteristics of flighted rotary kilns." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2015. http://www.theses.fr/2015EMAC0009/document.
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Ce travail porte sur l'étude de fours tournants équipés de releveurs. Ce sont des contacteurs gaz/solide largement répandus dans de nombreux secteurs industriels mettant en oeuvre des solides divisés. Cependant en raison d'une faible connaissance du fonctionnement de ces équipements notamment en matière d'écoulement ou de transfert thermique, leur utilisation repose encore beaucoup sur le savoir faire des opérateurs acquis avec le temps. Ainsi ce travail vise à fournir aux ingénieurs des outils de connaissance et d'extrapolation pour les accompagner dans les phases de dimensionnement, mais aussi d'optimisation de procédés existants, en particulier pour des fours tournants en chauffage indirect et équipés de releveurs. La première partie de cette étude porte sur l'influence des conditions opératoires sur l'hydrodynamique des solides divisés de forme et taille différentes. Pour ce faire, des procédures expérimentales pour la mesure de distribution des temps de séjours des particules solides ont été mises en oeuvres. Deux pilotes de four tournant ont été utilisés. Ces derniers ont un ratio longueur sur diamètre équivalent mais un ratio de taille de 2. L'hydrodynamique des fours a été caractérisée quantitativement à partir des résultats expérimentaux en terme de temps de séjour des solides, taux de remplissage du four ainsi que de la dispersion axiale des particules. Ces derniers ont été modélisés par analyse dimensionnelle dans un souci de généralité en prenant en compte la présence d'éléments internes (releveurs, grille) ou diaphragmes en sortie, mais aussi des paramètres opératoires tels que la vitesse de rotation du tube, son inclinaison ou le débit des particules solides. La seconde partie de cette étude s'intéresse aux processus de transfert thermique dans les fours tournants en chauffage indirect et équipés de releveurs. Cette étude repose sur la mesure des profils de température à la paroi, dans la phase gazeuse et le lit de particules solides. L'analyse de ces profils de température se focalise sur la détermination des coefficients de transfert de chaleur entre la paroi et le lit de solides d'une part, et entre la paroi et le gaz d'autre part. Une méthode d'analyse globale de système mince et un bilan global intégrant la puissance fournie pour la chauffe sont utilisés pour la détermination de ces coefficients de transfert. Les résultats obtenus permettent d'une part de mettre en évidence l'effet des releveurs ainsi que l'influence des paramètres opératoires sur ces coefficients de transfert de chaleur et d'autre part d'établir par analyse dimensionnelle des modèles pour ces derniers. Enfin, ce travail se termine par la mise en place d'un modèle dynamique simplifié de four tournant en chauffage indirect permettant la détermination des profils de température le long du four et pouvant être facilement adapté à divers procédésThe present work addresses a fundamental study on flighted rotary kilns. They are gas-solid reactors, used in a variety of industries to process heterogeneous media. However, operating these kilns mainly relies on the know-how of operators due to insufficient fundamental understanding. The aim of this work is to provide engineers with relevant tools and models to assist in the design stage and the performance improvement of existing operating process units, in particular indirectly heated rotary kilns, inclined and equipped with lifters. In the first part, we studied the effects of operating parameters on the flow of materials of differing properties and shape. For this purpose, residence time distribution measurements were performed through experimental stimulus response tests. Two pilot-scale rotary kilns with similar length-to-diameter ratios, but a dimension ratio of about two were used in this study. We focused on the effects of lifter shape and configurations. The effects of the rotational speed, the kiln slope, the mass flow rate and the exit dam height were also analyzed. The flow of solids was quantitatively characterized primarily by the experimental mean residence time, hold-up, and axial dispersion coefficient. Using a dimensional analysis, models were established to predict the mean residence time, the filling degree and the axial dispersion coefficient, providing basic information on the kiln design, solid particle properties and operating conditions. In the second part, we studied the heat transfer mechanisms occurring in the flighted rotary kiln by measuring temperature profiles at the wall, the freeboard gas and the bulk of solids. Analysis of the temperature profiles focused on two main issues: assessment of the heat transfer coefficient between wall and gas, and assessment of the heat transfer coefficient between wall and solid particles. The lumped system analysis and a heat balance using the power supplied for the heating were applied to determine the experimental heat transfer coefficients. The effects of operating conditions and lifting flights were analyzed. Both heat transfer coefficients were then correlated through dimensional considerations. Lastly a global dynamic model mainly based on the models developed in this study can be used to determine wall, gas and bulk solids axial temperature profiles in an indirectly heated flighted rotary kiln. This global model needs to be completed with specific models related to a reaction so as to be used as a framework for the simulation of specific industrial rotary kilns
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Dupont, Emmeric. "Mesures à haute résolution et étude de la réaction de diffusion inélastique de neutrons sur le 56Fe." Aix-Marseille 1, 1998. https://tel.archives-ouvertes.fr/tel-01145543.
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Des mesures à haute résolution de la section efficace de diffusion inélastique de neutrons sur un échantillon enrichi en 56Fe ont été effectuées du seuil (862 keV) jusqu'à environ 3 MeV. Les expériences ont été réalisées en utilisant la technique du temps de vol sur la piste de 200 mètres du dispositif GELINA (Geel, Belgique) avec une bouffée de neutrons de durée inférieure à 2 ns, permettant d'atteindre une excellente résolution en énergie. Quatre scintillateurs au fluorure de baryum, placés autour des échantillons, ont enregistré les émissions de rayons gamma en provenance du fer et du bore. La réaction 10B(n,alpha-gamma)7Li a été utilisée pour la mesure du flux et pour normaliser la section efficace. Finalement, une étude des corrélations entre les largeurs partielles élastique et inélastique a été menée en prenant aussi en compte les informations obtenues lors de précédentes mesures de transmission réalisées à Geel.
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Jones, Jared. "Winging It: Human Flight in the Long Eighteenth Century." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1565963832584991.
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Положевець, Ганна Андріївна, and Карина Олександрівна Сахно. "DEVELOPMENT AND EXPERIMENTAL RESEARCHES OF ESTIMATION OF THE FIRST SIGNS OF FACTOR RESONANCE AT THE PRODUCTION OF FLIGHTS." Thesis, Національний авіаційний університет, 2013. http://er.nau.edu.ua/handle/NAU/11524.
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Chen, Ping. "Applications of Chemometric Algorithms to Ion Mobility Spectrometry and Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1206019463.
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Bacher, Patrice. "Etude du profil des raies de diffraction neutronique en temps de vol utilisant un obturateur statistique : application à l'étude d'oxynitrures de structure tétraèdrique ou de type pérovskite." Grenoble 1, 1987. http://www.theses.fr/1987GRE10035.
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Application de l'etude du titre a deux grandes famille structurales: (1) les structures tetraedriques derivant de cele de la wuertzite (li::(1,33)ge::(1,67)on::(2); zn::(1,231)ge::(0,689)o::(0,782)n::(1,218); kgeon), (2) les structures de type perovskite (batao::(2)n, banbo::(2)n, lawo::(0,6)n::(2,4))
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Endo, Makoto. "Numerical modeling of flame spread over spherical solid fuel under low speed flow in microgravity:Model development and comparison to space flight experiments." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1461022358.
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Zhang, Lanyue [Verfasser], and Evangelos [Gutachter] Tsotsas. "Experimental investigation and numerical simulation of the particle motion in flighted rotating drums / Lanyue Zhang ; Gutachter: Evangelos Tsotsas." Magdeburg : Universitätsbibliothek Otto-von-Guericke-Universität, 2020. http://d-nb.info/123199200X/34.
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Monart, Brigitte. "Etude experimentale del'emission secondaire (ions atomiques et moleculaires, agregats, electrons) induite par bombardement de surface par des ions lourds energetiques ( equiv. A mev/u) : effets de l'etat de charge des projectiles." Paris 7, 1988. http://www.theses.fr/1988PA077121.
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Etude de l'emission secondaire en fonction de la vitesse en projectile, de l'angle d'incidence du faisceau par rapport a la cible (minerale ou organique) et surtout de l'etat de charge au projectile, par spectrometrie de masse a temps de vol principalement: cette emission depend fortement de la charge du projectile et aussi du changement d'etat de charge a l'interieur du materiau. Interpretation des resultats a l'aide du modele de maynard et al. , en supposant l'existence d'une profondeur d'interaction ion primaire-materiau qui depend du type d'ions secondaires et de la charge de l'ion incident
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Wyrwas, Richard Ben Jr. "Vanadium Oxide Anions Clusters: Their Abundances, Structures and Reactions with SO₂." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4908.
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Early transition metal oxide clusters have been a focus of study for several years. The production of vanadium oxide cluster anions in a pulsed helium flow reactor provides a relatively precise way of introducing defect sites and controlling the oxidation state of the vanadium atoms. The composition of the clusters can be changed from the V2O5 stoichiometry, where the vanadium atom is in a +5 oxidation state, to more reduced stoichiometries yielding a mixture of oxidation states containing atoms in the +2 oxidation state. The subsequent addition of reactant gases such as H2O and SO2 yields very intense adsorption reactions as well as a demonstration of the robustness of particular defect free clusters. For example, the cluster has been identified as a defect free cluster where all vanadium atoms are in the +5 oxidation state and all oxygen atoms are predicted to be in the 2- state. The cluster has been shown to not adsorb SO2- while clusters in a reduced oxidation state, such as and readily adsorb one or more SO2 molecules. The adsorption process has been shown to be size dependent, with the smallest monovanadium oxide anions being the most reactive.
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Bessot, Denis. "Conception de deux points mémoire statiques CMOS durcis contre l'effet des aléas logiques provoqués par l'environnement radiatif spatial." Grenoble INPG, 1993. http://www.theses.fr/1993INPG0161.
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Avec l'accroissement des traitements de l'information à bord des véhicules spatiaux et l'utilisation de technologies de plus en plus intégrées, le phénomène d'upset (modification non destructive du contenu d'un point mémoire suite à la collision d'un ion lourd) devient critique. L'objectif de cette thèse est d'étudier la possibilité de durcir face aux upsets un circuit VLSI, tel un processeur, à partir d'une technologie standard. Pour cela, deux points mémoire statiques CMOS (appelés HIT), capables de restituer l'information modifiée par l'impact d'une particule, ont été conçus. Une étude comparative portant sur les cellules HIT, deux cellules mémoire durcies proposées par la NASA et IBM, et le point mémoire statique non durci, a été entreprise. Un premier volet de cette étude, réalisée par simulation Spice, montre que les performances électriques statiques et dynamiques (consommation de puissance statique, temps de propagation et de lecture) sont comparables ou meilleures que celles des cellules mémoire durcies proposées dans la littérature. Un aspect important du durcissement à la conception est la surface silicium additionnelle. L'implantation des cellules à l'aide d'un process HS13 de THOMSON-TCS (épitaxial 1,2 micron) a permis de mettre en évidence que les cellules HIT consomment moins de surface silicium. Le deuxième volet d'étude a concerné la sensibilité aux upsets des cellules : - les charges collectées ont été évaluées à l'aide des simulations Spice, montrant qu'elles sont suffisamment élevées pour tolérer les upsets simples induits par les ions lourds couvrant un large spectre d'énergie, - la sensibilité aux upsets multiples a été évaluée à l'aide d'un modèle Markovien, montrant que les cellules HIT présentent une meilleure tolérance. Pour obtenir ce résultat, l'introduction des chaînes de Markov a conduit à calculer le facteur de défaillance à partir de tous les états critiques susceptibles d'engendrer un aléa logique. Un prototype implémentant cinq bancs de registres constitués de deux solutions proposées dans cette thèse, de deux cellules durcies proposées dans la littérature et de la cellule non durcie, a été conçu et réalisé. Les tests aux ions lourds de ce prototype, à l'aide d'équipements adéquats pour simuler l'environnement radiatif (accélérateurs de particules) permettra de corréler les résultats théoriques avec les données expérimentales
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Lundström, Fredrik. "Secrets of the Spearhead : Developing Continuum Mechanical Simulations and Organic Residue Analysis for the Study of Scandinavian Flint Spearhead Functionality." Thesis, Stockholms universitet, Arkeologiska forskningslaboratoriet, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-174757.
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This thesis is a pilot study, designed to test and develop methods suitable for the study of Scandinavian flint spearhead functionality. The functionality of projectile and lithic point armament has not been studied for almost 30 years in Scandinavia. Meanwhile, methods used to analyse lithic projectiles have developed considerably. However, few of these methods are precise enough to be used in conjunction with Scandinavian stone technological analyses that emphasize the societal aspect of lithic points. Consequently, two methods were chosen that could provide data for Scandinavian research issues: 3D-scanning/continuum mechanical simulations and organic residue analysis. The methods were tested on 6 experimental spearheads. The continuum mechanical simulation generated both visual and numerical data that could be used to create precise functional-morphological descriptions. The data could also potentially be used for projectile point classification. The organic residue analysis revealed promising results for the use of an artefact and activity specific analysis, with a sequential extraction protocol. In unison, the results from both analyses could be used to reveal how spearheads were functionally designed and used in Stone Age Scandinavia, even though there are methodological and technological issues that need solving.
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DeBoy, Christopher C., Paul D. Schwartz, and Richard K. Huebschman. "Midcourse Space Experiment Spacecraft and Ground Segment Telemetry Design and Implementation." International Foundation for Telemetering, 1996. http://hdl.handle.net/10150/608390.
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International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, CaliforniaThis paper reviews the performance requirements that provided the baseline for development of the onboard data system, RF transmission system, and ground segment receiving system of the Midcourse Space Experiment (MSX) spacecraft. The onboard Command and Data Handling (C&DH) System was designed to support the high data outputs of the three imaging sensor systems onboard the spacecraft and the requirement for large volumes of data storage. Because of the high data rates, it was necessary to construct a dedicated X-band ground receiver system at The Johns Hopkins University Applied Physics Laboratory (APL) and implement a tape recorder system for recording and downlinking sensor and spacecraft data. The system uses two onboard tape recorders to provide redundancy and backup capabilities. The storage capability of each tape recorder is 54 gigabits. The MSX C&DH System can record data at 25 Mbps or 5 Mbps. To meet the redundancy requirements of the high-priority experiments, the data can also be recorded in parallel on both tape recorders. To provide longer onboard recording, the data can also be recorded serially on the two recorders. The reproduce (playback) mode is at 25 Mbps. A unique requirement of the C&DH System is to multiplex and commutate the different output rates of the sensors and housekeeping signals into a common data stream for recording. The system also supports 1-Mbps real-time sensor data and 16-kbps real-time housekeeping data transmission to the dedicated ground site and through the U.S. Air Force Satellite Control Network ground stations. The primary ground receiving site for the telemetry is the MSX Tracking System (MTS) at APL. A dedicated 10-m X-band antenna is used to track the satellite during overhead passes and acquire the 25-Mbps telemetry downlinks, along with the 1-Mbps and 16-kbps real-time transmissions. This paper discusses some of the key technology trade-offs that were made in the design of the system to meet requirements for reliability, performance, and development schedule. It also presents some of the lessons learned during development and the impact these lessons will have on development of future systems.
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Kintz, Andrew Lane. "Nullspace MUSIC and Improved Radio Frequency Emitter Geolocation from a Mobile Antenna Array." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1479896813925084.
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