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1
Zhang, Shuting. "Angular effects of surface brightness temperature observed from Sentinel-3A/SLSTR data." Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAD055.
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Ce travail de thèse utilise les données TIR de SLSTR comme source principale pour extraire la température de brillance de la surface (SBT) en appliquant l’algorithme split-window, afin d’analyser l’effet angulaire sur la SBT. En se basant sur une base de données de simulation, une méthode d’extraction de la SBT a été développée et appliquée aux observations à double angle de SLSTR. L’étude a ensuite examiné l’amplitude et les caractéristiques des différences de SBT entre les vues nadir et obliques, en tenant compte de facteurs tels que l’occupation du sol /la couverture terrestre, la saison, la latitude et le climat. Enfin, l’outil GeoDetector a été utilisé pour effectuer une analyse d’attribution des effets angulaires sur la SBTThis study adopts SLSTR TIR data as the main data source and retrieves surface brightness temperature using split-window algorithm to analyze the angular effect of surface brightness temperature (SBT). Based on the simulation database, SBT retrieval method is developed and applied to SLSTR dual-angle SBT extraction. Then the magnitude and characteristics of SBT differences between nadir and oblique views were observed, considering factors such as land use/land cover, season, latitude and climate. Finally, GeoDetector tool was used to perform attribution analysis of SBT angular effects
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Monem, A. S. M. A. "Angular light scattering from phospholipid vesicles and the effect of magnetic fields." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373565.
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Le, Charles Tuan-Cong. "Angular memory effect and its interferometric applications in rough surface mean height profiling /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/6005.
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Shaw, Matthew D. "On the Measurement of Angular Dependent Sound Transmission through Airborne Supercritical Plates." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2835.
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A method of measuring angular dependence of acoustic transmission through supercritical plates in air is discussed. The coincidence effect occurs in a supercritical plate when the component of the acoustic wave number parallel to the plate matches the bending wave number in the plate. The transmission of sound is a maximum at the angle where this trace wave number matching occurs. The theory of the coincidence effect is well-defined for unbounded thin plates using plane-wave excitation. However, experimental results for finite plates are known to diverge from theory, especially near grazing angles. An experimental setup has been developed in order to observe the coincidence effect using continuous-wave excitation and phased-array methods. Experimental results through a 0.5 mm thick aluminum bar exhibit strong maxima at the predicted coincidence angles, showing that coincidence is observable using continuous waves. Also, transmission near grazing angles is seen to diverge from infinite plate theory. Further work is suggested to improve the measurement setup and explore the source of the divergence.
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N’Diaye, M., F. Martinache, N. Jovanovic, J. Lozi, O. Guyon, B. Norris, A. Ceau, and D. Mary. "Calibration of the island effect: Experimental validation of closed-loop focal plane wavefront control on Subaru/SCExAO." EDP SCIENCES S A, 2018. http://hdl.handle.net/10150/627093.
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Context. Island effect (IE) aberrations are induced by differential pistons, tips, and tilts between neighboring pupil segments on ground-based telescopes, which severely limit the observations of circumstellar environments on the recently deployed exoplanet imagers (e.g., VLT/SPHERE, Gemini/GPI, Subaru/SCExAO) during the best observing conditions. Caused by air temperature gradients at the level of the telescope spiders, these aberrations were recently diagnosed with success on VLT/SPHERE, but so far no complete calibration has been performed to overcome this issue. Aims. We propose closed-loop focal plane wavefront control based on the asymmetric Fourier pupil wavefront sensor (APF-WFS) to calibrate these aberrations and improve the image quality of exoplanet high-contrast instruments in the presence of the IE. Methods. Assuming the archetypal four-quadrant aperture geometry in 8 m class telescopes, we describe these aberrations as a sum of the independent modes of piston, tip, and tilt that are distributed in each quadrant of the telescope pupil. We calibrate these modes with the APF-WFS before introducing our wavefront control for closed-loop operation. We perform numerical simulations and then experimental tests on a real system using Subaru/SCExAO to validate our control loop in the laboratory and on-sky. Results. Closed-loop operation with the APF-WFS enables the compensation for the IE in simulations and in the laboratory for the small aberration regime. Based on a calibration in the near infrared, we observe an improvement of the image quality in the visible range on the SCExAO/VAMPIRES module with a relative increase in the image Strehl ratio of 37%. Conclusions. Our first IE calibration paves the way for maximizing the science operations of the current exoplanet imagers. Such an approach and its results prove also very promising in light of the Extremely Large Telescopes (ELTs) and the presence of similar artifacts with their complex aperture geometry.
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Östling, Johan. "High Accuracy Speed and Angular Position Detection by Dual Sensor." Thesis, Uppsala universitet, Fasta tillståndets fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-365726.
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For many decades there has been a need in many industries to measure speed and position of ferrous gears. This is commonly done by converting passing gear teeth from trigger wheels to electrical impulses to calculate speed and angular position. By using Hall effect sensors or Giant Magnetoresistance sensors (GMR), a zero speed detection of gear teeth is possible while at the same time be cheap to produce and durable for harsh environments. A specially designed trigger-wheel (cogwheel created for measurements) with gear teeth in a specific pattern, exact position can be detected by using a dual sensor, even when no earlier information is available. The new design of trigger-wheel also makes this new method more accurate and universal compared to previous solutions. This thesis demonstrates and argues for the advantages of using a dual sensor for speed and angular position detection on gear wheels. Were one sensor do quantitative measurements for pattern detection in the teeth arrangements and the other sensor do qualitative measurements for position detection.
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Jackson, Richard Aram Jr. "A Preliminary Study of Pump/Probe Angular Dependence of Zeeman Electromagnetically Induced Transparency." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1439372287.
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Aljazaeri, Bassim. "Effect of previous angular deformation on flexural fatigue resistance of controlled memory nickel-titanium endodontic instruments." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/48451.
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Objective: To evaluate the effect of torsional stress preloading angle on fatigue resistance of Typhoon (TYP) CM instruments. Methodology: TYP NiTi 25/.04, TYP NiTi 40/.04, TYP CM 25/.04 and TYP CM 40/.04 were rotated until fracture to obtain the mean angular deflection according to the +-ISO 3630-1 standard. Files were pre-torqued to 25, 50, and 75% of their elastic limit and then subjected to cyclic loading in a three-point binding device until fracture. The fatigue life was recorded for each file.The fracture surface of each fragment was examined with a scanning electron microscope. Results: The angle of rotation at fracture of TYP CM was significantly higher than that of TYP instruments (P < 0.05). However, there was no significant difference between size 40 and size 25 in all types of files. The fatigue resistance of TYP CM was significantly higher than that of TYP instruments (P < 0.05). Size 25/.04, TYP and TYP CM files in all three preloading groups had a significantly lower fatigue life than files with no preloading (P < 0.05). Size 40/.04 TYP CM files in the 50% and 75% preloading groups had a significantly lower fatigue life than files in the groups with no preloading (P < 0.05). The fractured files in the preloading groups showed the typical pattern of fatigue failure. Conclusions: TYP CM files have a higher fatigue resistance than conventional TYP NiTi files, irrespective of the amount of previous torsional stress. Fatigue resistance of TYP CM and TYP instruments was reduced after torsional stress preloading. Size 25/.04 file fatigue life was affected by preloading at lower distortion angles than was size 40/.04 fatigue life.Dentistry, Faculty of
Graduate
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Kennedy-Fisher, Sandra D. "The effect of copper sulphate and host variety on angular leaf spot, Xanthomonas fragariae, of strawberry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq24862.pdf.
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Wells, Jared Lawrence. "Effect of angular orientation on the hydrodynamic forces acting on a body in a restricted waterway." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/41572.
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A slender body theory method developed for a body moving parallel to a wall in shallow water is extended to include angular orientation of the body to the wall. The method satisfies only the zero normal velocity condition on the external boundaries but does not take into account the effect of induced flows on the body itself. A spheroid and a Series 60, block .80 hull were the bodies studied. The side force and yaw moment on each body were determined numerically for varying angular orientation with respect to either a single wall or canal bank. For both cases results for a range of depths and wall separation distances are presented. It is found that the method gives good qualitative side force predictions for a body moving parallel to a wall, but is unable to correctly predict the yaw moment or the side force due to angular orientation. This result dictates the need for a more complex mathematical model to properly represent the flow than the simple model and quasiâ steady method used here.
Master of Science
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El, Balaa Rayan. "Effect of Predator Diet on Predator-induced Changes in Life History and Performance of Anuran Larvae." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22790.
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Phenotypic plasticity allows some animals to change their behavioural, morphological, performance, and life history traits in response to changes in environmental conditions such as the presence of predators. These changes can enhance survival, but come at a cost. Some of these phenotypic changes are predator and diet specific. I examined the effects of predator diet on the performance, life-history, and morphology of developing Northern Leopard Frog (Lithobates pipiens) tadpoles. Tadpoles were either exposed to cues from fish free water, cues from Brown Bullhead (Ameiurus nebulosus) fed a diet of trout pellets, or cues from A. nebulosus fed a L. pipiens tadpoles diet. Tadpoles exposed to predatory fish cues had smaller bodies, deeper tail fins, slower growth and development rates, and better rotational performance than tadpoles that were not exposed to predatory fish cues. Moreover, tadpoles appeared to differentiate between predatory fish diet and produced diet-specific responses in tail morphology and activity, although the latter effect was only marginally significant. Hatching, metamorphosis rates, and linear performance were not affected by the treatments. These results suggest that A. nebulosus can induce phenotypic changes in L. pipiens tadpoles, with some of these changes being diet specific.
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Cronin, Thomas Martin. "Effect Of Fiber Orientation Distribution Function Reconstruction On Probabilistic Tractography." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1327524558.
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Greig, Robert Ewan. "The effect of geometry variation and winding cross-coupling on the angular error of a high accuracy multipole resolver." Thesis, Heriot-Watt University, 1986. http://hdl.handle.net/10399/1958.
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Adam, R., I. Bartalucci, G. W. Pratt, P. Ade, P. André, M. Arnaud, A. Beelen, et al. "Mapping the kinetic Sunyaev-Zel’dovich effect toward MACS J0717.5+3745 with NIKA." EDP SCIENCES S A, 2017. http://hdl.handle.net/10150/623249.
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Measurement of the gas velocity distribution in galaxy clusters provides insight into the physics of mergers, through which large scale structures form in the Universe. Velocity estimates within the intracluster medium (ICM) can be obtained via the Sunyaev-Zel'dovich (SZ) effect, but its observation is challenging both in term of sensitivity requirement and control of systematic effects, including the removal of contaminants. In this paper we report resolved observations, at 150 and 260 GHz, of the SZ effect toward the triple merger MACS J0717.5 + 3745 (z = 0.55), using data obtained with the NIKA camera at the IRAM 30 m telescope. Assuming that the SZ signal is the sum of a thermal (tSZ) and a kinetic (kSZ) component and by combining the two NIKA bands, we extract for the first time a resolved map of the kSZ signal in a cluster. The kSZ signal is dominated by a dipolar structure that peaks at -5.1 and + 3.4 sigma, corresponding to two subclusters moving respectively away and toward us and coincident with the cold dense X-ray core and a hot region undergoing a major merging event. We model the gas electron density and line-of-sight velocity of MACS J0717.5 + 3745 as four subclusters. Combining NIKA data with X-ray observations from XMM-Newton and Chandra, we fit this model to constrain the gas line-of-sight velocity of each component, and we also derive, for the first time, a velocity map from kSZ data (i. e. that is model-dependent). Our results are consistent with previous constraints on the merger velocities, and thanks to the high angular resolution of our data, we are able to resolve the structure of the gas velocity. Finally, we investigate possible contamination and systematic effects with a special care given to radio and submillimeter galaxies. Among the sources that we detect with NIKA, we find one which is likely to be a high redshift lensed submillimeter galaxy.
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Qarni, Muhammad Jawad. "Effect of incremental equal channel angular pressing (I-ECAP) on the microstructural characteristics and mechanical behaviour of commercially pure titanium." Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28410.
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Owing to its high specific strength, low density, outstanding corrosion resistance and excellent bio-compatibility titanium and its alloys are a material of choice in many aerospace, military, chemical and biomedical applications. Ti-6Al-4V is the most widely used alloy for medical device applications such as in total replacement implants, where higher strength characteristics are generally a requirement. However, research has suggested that alloying elements such as aluminium and vanadium present in that alloy can be toxic in the long term and are therefore undesirable for full bio-integration. Commercially pure titanium (CP-Ti) has superior biocompatibility but it lacks the strength required for most load bearing implants. One viable solution is to abandon the use of alloying elements and to improve the mechanical strength and performance of CP-Ti by nano-structuring or grain refinement. Severe plastic deformation (SPD) is an established method for introducing extreme grain refinement in metals. The technique imparts high plastic strain to the material without significantly changing the sample dimensions and is capable of achieving ultrafine grain (UFG) structure in metals. UFG materials are characterized by an average grain size of < 1 μm and with mostly high angle grain boundaries. These materials exhibit exceptional improvements in strength, superplastic behaviour and in case for titanium, improved corrosion resistance and enhanced biocompatibility. Among the various available SPD methods, equal channel angular pressing (ECAP) is the most widely used method for obtaining bulk UFG materials. However, ECAP (in its classical form) suffers from low productivity and is not a practical option for commercialization. Therefore, lately the interest is in the development of continuous SPD techniques, capable of processing very long or continuous billets for use in commercial applications. Incremental ECAP (I-ECAP) developed at the University of Strathclyde, offers such possibility. This promising technique has a strong potential of obtaining the much-needed high strength CP-Ti for biomedical implants on an industrial scale. The aim of the present research work is to investigate the feasibility of the I-ECAP process in improving the mechanical performance of CP-Ti by refining its grain structure. However, before processing CP-Ti on the I-ECAP experimental rig, it was necessary to eliminate the some existing limitations of the rig and improve the overall process efficiency. Major upgrades and enhancements were implemented as part of the present work. These include: automation of material feeding system, elevated temperature capability, press controller upgrade, data acquisition and process control during experiments. Moreover, finite element analysis was performed to optimize the tooling geometry by studying the billet deformation behaviour and subsequently new I-ECAP dies were designed and manufactured suitable for processing CP-Ti billets. Using the considerably improved I-ECAP experimental facility, CP-Ti billets were subjected to multiple passes of the I-ECAP process at elevated temperatures. To investigate the effect of different levels of induced shear strain per pass, billets were processed using two separate dies with channel intersection angles of 120 and 90°. Microstructural evolution and textural development in the material was tracked and examined using high-resolution electron backscatter diffraction (EBSD) technique. Twinning and continuous dynamic recrystallization (CDRX) have been observed to act as a grain refinement mechanism during subsequent passes of I-ECAP. Analysis of the microstructure shows that UFG structure was successfully obtained with mostly high angle grain boundaries (HAGB) in the processed billets using the two dies. Room temperature tensile tests carried out before and after processing show significant increase in strength with some loss in ductility in the processed material. The yield strength and ultimate tensile strength (UTS) of the material after I-ECAP processing using the die angle of 120° was increased by 81% and 25%, respectively. The material processed using the die angle of 90° exhibits an even higher increase in yield strength and UTS i.e. 118% and 33%, respectively. Compression tests conducted at different strain rates at room temperature show increase in strength with a three stage hardening behaviour, though the severely deformed UFG material suffers a loss in its strain hardening ability. Detailed microhardness measurements also show the increase in hardness after processing with a reasonable level of homogeneity. Finally, workability characteristics of UFG titanium is determined by compression testing at room and warm temperature conditions (400 to 600 °C). The work has successfully demonstrated that I-ECAP process is effective in improving the mechanical performance of titanium and has a potential for commercialization.
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Li, Zehao. "Quantum Mechanics on the Möbius Ring." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/186.
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Recent advances in the chemical vapor deposition method of growing graphene sheets suggest that graphene rings can grow. We may anticipate that chemical methods can be developed to construct twisted nano-ribbons to form Möbius structures in the very near future. I investigated the quantum mechanics of an electron constrained to motion on a nanoscale Möbius ring by solving the Schrdinger equation on the curved surface. The close analogy between ordinary cylindrical rings and Möbius rings is displayed by the closeness of their energy spectra. The expectation values for the angular momentum component L_z are shown to be close, but not exactly equal, to integral or half-integral multiples of hbar. The half-integer angular momentum states are present only for the nontrivial topology of Möbius rings. The effect of the curvature of the Möbius rings manifests itself in the level splitting. This can be understood in terms of representations of the discrete rotational groups C_nv. The nonzero variance of L_z will allow weak transitions between integral and half-integral angular momentum states, while preserving the unit angular momentum for photons. Again, since the topology of the system is critical for the Aharonov-Bohm effect, I investigated the AB effect on Möbius rings and found a remarkable pattern in transmission through finite-width 2D ring structures with finite-width input and output contacts attached at the periphery. The periodicity in the magnetic flux, in units of h/e, is weakly broken on 2D rings of finite width. The unusual states with half-integer values of observed on Möbius rings, investigated earlier, display a different characteristic in transmission. In view of the fascinating properties displayed by the non-trivial topology in terms of its novel two-dimensional physics, we expect that the properties of carriers on the Möbius ring that we have presented here will be relevant for practical applications.
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Kibar, Alp Aykut. "Investigation Of The Effect Of Dissimilar Channel Angular Pressing Method To The Mechanical And Microstuctural Properties Of 6061 Aluminum Alloy Sheets." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612140/index.pdf.
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Dissimilar Channel Angular Pressing (DCAP) method is an effective Severe Plastic Deformation (SPD) technique to improve the mechanical properties of sheets or strips by producing ultrafine grains. The aim of this study is to investigate the evolution of the microstructure and the improvement in mechanical properties of 6061 Al-alloy strips deformed by DCAP up to 5 passes. Mechanical properties such as hardness and strength have been observed to increase up to a certain strain level depending on the microstructural evolution. These microstructural changes were investigated by the characterization studies of XRD, SEM and TEM analysis of the DCAPed samples indicating the subgrain formation, changes in the dislocation density and dislocation behaviors.
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Montgomery, Patrick D. "MAGNETO-OPTICAL PROPERTIES OF THIN PERMALLOY FILMS: A STUDY OF THE MAGNETO-OPTICAL GENERATION OF LIGHT CARRYING ANGULAR MOMENTUM." UKnowledge, 2018. https://uknowledge.uky.edu/ece_etds/126.
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Magneto-optical materials such as permalloy can be used to create artificial spin- ice (ASI) lattices with antiferromagnetic ordering. Magneto-optical materials used to create diffraction lattices are known to exhibit magnetic scattering at the half- order Bragg peak while in the ground state. The significant drawbacks of studying the magneto-optical generation of OAM using x-rays are cost, time, and access to proper equipment. In this work, it is shown that the possibility of studying OAM and magneto-optical materials in the spectrum of visible light at or around 2 eV is viable. Using spectroscopic ellipsometry it is possible to detect a change in the magnetization of thin permalloy films with thicknesses between 5 and 20 nm. Patterns consistent with OAM were found at 1.95 eV using a square lattice with a 4𝜋 radial phase shift in the antiferromagnetic ground state. Evidence of magnetic scattering at the half-order Bragg peak using 1.95 eV was also found.
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Edmundson, Christopher James. "Effect of workload, upper body posture, and saddle set-back on full body angular joint kinematics, muscle activity, and lower limb haemodynamics." Thesis, University of Central Lancashire, 2008. http://clok.uclan.ac.uk/21823/.
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'Cycling is one of the toughest sports and one of the most complex to analyse in scientific terms.' - Mr Hein Verbruggen,P residentU nion Cycliste International 1991-2005. Despite extensive research into sagittal plane lower limb cycling kinematics there is little scientific literature available investigating the three-dimensional joint kinematics of the cyclist, and especially so regarding the kinematics of the pelvis, trunk, and arms, and how these are affected by workload, upper body posture, and saddle setback. This Thesis developed a comprehensive full-body three dimensional kinematic model and then determined the effects of workload, Upper Body Posture, and Saddle Setback on the leg, trunk, and arm kinematics of the cyclist. Competitive cycling has an extremely high aerobic component, and yet ironically there have been few studies investigating how workload or riding position affect lower limb blood flow haemodynamics. By using Near-Infrared Spectroscopy a cycling specific technique was developed to enable tissue oxygenation status of the lower limbs to be determined during cycling, which was then used to assess the effects of workload, trunk and hip angle, and saddle set-back on lower limb blood flow haemodynamics. It is unclear to what extent saddle setback affects lower limb and trunk muscle activity and cycling performance, and yet the sub-disciplines of cycling use markedly different bicycle set-ups. By using a custom cycle ergometer developed by the author this Thesis systematically assessed the effects of saddle setback on muscle recruitment and activation magnitude. When investigating the effects of bicycle set-up on cycling performance it is important to consider all the physiological and biomechanical determinants of success in unison, and how they inter-relate. To date there are no studies that have comprehensively studied the kinematic, haemodynamic, electromyographic, and associated crank kinetics simultaneously. As such this Thesis developed a methodology to evaluate the effects of changing workload, upper body posture, and saddle setback on fullbody three-dimensionalk inematics, lower limb blood flow haemodynamicsl,e g and trunk electromyography, and crank torque profiles, in order to arrive at the optimum riding position and highlight the compromises required when aiming to maximise cycling performance. The effects of workload were assessed by undertaking a 25W. min" graded maximal exercise test to exhaustion. In order to assess the kinematic, haemodynamic, and electromyographic effects of altering riding position a custom independently adjustable cycle ergometer was developed to permit precise accurate adjustment of the four main macro settings (saddle height and setback, and saddle to handlebar reach and drop) while maintaining the spatial coordinates of the other parameters. Three Upper Body Postures (Hoods,D rops and a Time Trial position), and six SaddleS etbacksw ere used (100,50, and Omm behind the bottom bracket, and 50,100, and 150mm in front of the bottom bracket). For all three studies three-dimensional full body kinematics were recorded using a stereophotogrammetricin fra-red motion capture system. Leg and trunk muscle activity were recorded using an 8-lead surface electromyographic system, and tissue oxygenation levels were recorded using Near Infrared Spectroscopy on the Vastus Lateralis. Corresponding crank torque profiles were measured simultaneously using a crank dynamometer. Increasesi n workload produced progressived ecreasesin Oxyhaemoglobina nd pedalling smoothnessin dex, and continual increasesin total haemoglobinc ontenta nd muscle activity in the majority of muscle groups, but produced little change in full-body kinematics until 80% maximal aerobic power was surpassedC. hanging from the Hoods to the Drops and into a Time Trial position had little effect on lower and upper limb kinematics, but produced significant increases in all lower limb muscle activity except the gluteus maximus, as well as considerable reductions in tissue oxygenation status, and resulted in cyclists pedalling with greater peak torque values. Moving the saddle forwards significantly affected joint kinematics, muscle activity, tissue oxygenation status, and the crank torques profiles. A saddle positioned with the nose directly over the bottom bracket minimised angular rotations of the ankle, knee, hip, and trunk as well as global muscle activation. Tissue oxygenation status was also significantly higher using this setting, suggesting that although an aerodynamic cycling position must take priority, setting the saddle with the nose directly over the bottom bracket and maintaining the operating range of motion at the hip and knee appears to maximise cycling performance, and that the spinal kinematics appear to act as a torque-induced engine by means of increases in axial rotation magnitude in the lumbar, mid-thoracic and thoracic spinal segments.
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Chai, Yue. "Nonlinear propagation of unconventional beams in a photorefractive crystal." Electronic Thesis or Diss., CentraleSupélec, 2024. http://www.theses.fr/2024CSUP0005.
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La thèse explore l'étude de la propagation et de l'interaction des faisceaux de Bessel non conventionnels dans un cristal photoréfractif (PR), en se penchant sur les technologies clés des communications optiques avancées. Cette thèse se divise en deux parties : la photo-inscription des guides d'ondes et la modulation des modes OAM. Premièrement, notre étude démontre qu'un seul faisceau de Bessel diffractant peut inscrire plusieurs guides d'ondes couplés dans le cristal PR en raison de ses profils en anneaux. En manipulant les paramètres optiques de notre plateforme optique, il est possible d'obtenir un contrôle flexible. Ces configurations permettent la réalisation de fonctions de routage complexe en optique. De plus, l'introduction d'un deuxième faisceau contra- propageant permet d'induire des guides d'ondes dynamiques, démontrant ainsi la possibilité de contrôle dans différents régimes. Deuxièmement, il est démontré que l'OAM d'un faisceau de Bessel polarisé de manière arbitraire peut être continuellement modulé par un champ électrique appliqué au matériau PR pour activer sa non-linéarité. Ensuite, des paramètres optimaux sont confirmés pour une plage de modulation en régime stable. Nous montrons également que l'OAM peut être modulé dans des conditions de non-linéarité très élevées, permettant ainsi d'étendre l'intervalle de modulation. Ces résultats offrent des perspectives prometteuses pour le développement de nouvelles technologies dans les domaines des composants passifs et dynamiques pour les communications tout-optiques ou quantiquesThe thesis focuses on the propagation of Bessel beams in a photorefractive crystal, involving technologies used in advanced optical communications, such as the all-optical router, switcher, mode multiplexing and demultiplexing using orbital angular momentum (OAM). The work is in two parts: the photo-inscription of waveguides and the modulation of OAM modes. In the first part, we demonstrate numerically and experimentally that a single diffracting Bessel beam can induce complex waveguides under the PR effect. In addition, by manipulating the parameters of our optical platform, we achieve flexible control of the induced waveguides’ characteristics. By testing these photo-induced waveguides using Gaussian probe beams, we confirm their complex routing functions. Furthermore, by introducing the second counter-propagating beam, we induce dynamic waveguides and demonstrate the control in any regime. In the second part, we demonstrated in simulations and experiments that the OAM of an arbitrarily polarized Bessel beam can be continuously modulated in the PR crystal by the applied electric field. By discussing parameter, we confirm optimal parameters to obtain the broadest modulation range in the steady state. We propose temporal plateaux long enough on which the OAM exceeds its initial value, thus enabling the extension of the OAM modulation range, even in the unstable regime. All the results in this thesis open up promising prospects for developing new technologies in all-optical or quantum communications
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Dixon, Mark. "Studies of spin and charge momentum densities using Compton scattering." Thesis, University of Warwick, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340475.
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Fanis, Alberto De. "Double photoionization of alkaline earth atoms and photoelectron spectroscopy of reactive intermediates." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327255.
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Di, Mascolo Luca [Verfasser], and Rashid [Akademischer Betreuer] Sunyaev. "Probing the intracluster medium at high angular resolution via radio-interferometric measurements of the Sunyaev-Zeldovich effect / Luca Di Mascolo ; Betreuer: Rashid Sunyaev." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1214593356/34.
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Nordblad, Erik. "Opening New Radio Windows and Bending Twisted Beams." Doctoral thesis, Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-158797.
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In ground based high frequency (HF) radio pumping experiments, absorption of ordinary (O) mode pump waves energises the ionospheric plasma, producing optical emissions and other effects. Pump-induced or natural kilometre-scale field-aligned density depletions are believed to play a role in self-focussing phenomena such as the magnetic zenith (MZ) effect, i.e., the increased plasma response observed in the direction of Earth's magnetic field. Using ray tracing, we study the propagation of ordinary (O) mode HF radio waves in an ionosphere modified by density depletions, with special attention to transmission through the radio window (RW), where O mode waves convert into the extraordinary (X, or Z) mode. The depletions are shown to shift the position of the RW, or to introduce RWs at new locations. In a simplified model neglecting absorption, we estimate the wave electric field strength perpendicular to the magnetic field at altitudes normally inaccessible. This field could excite upper hybrid waves on small scale density perturbations. We also show how transmission and focussing combine to give stronger fields in some directions, notably at angles close to the MZ, with possible implications for the MZ effect. In a separate study, we consider electromagnetic (e-m) beams with helical wavefronts (i.e., twisted beams), which are associated with orbital angular momentum (OAM). By applying geometrical optics to each plane wave component of a twisted nonparaxial e-m Bessel beam, we calculate analytically the shift of the beam's centre of gravity during propagation perpendicularly and obliquely to a weak refractive index gradient in an isotropic medium. In addition to the so-called Hall shifts expected from paraxial theory, the nonparaxial treatment reveals new shifts in both the transverse and lateral directions. In some situations, the new shifts should be significant also for nearly paraxial beams.
25
Sutter, Steven George. "The effect of strain and path change on the mechanical properties and microstructural evolution of ultrafine grained interstitial free steel during equal channel angular extrusion (ECAE)." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4738.
Full textAbstract:
The objectives of this study were to examine the effect of strain and path change on
the microstructural evolution of ultrafine grained interstitial free (IF) steel during equal
channel angular extrusion (ECAE); to determine the mechanical properties; to observe
the resulting texture; and to perform optical and electron microscopy of the resulting
material. The effects of different routes of extrusion (A, B, C, C' and E), heat treatment
and plastic strains from 1.15 to 18.4 were examined. Monotonous tensile testing was
used to determine mechanical behavior of processed materials. X-ray diffraction and
TEM analyses were performed to evaluate the effect of processing on texture and grain
morphology. Hardness measurements were performed to determine recrystallization
behavior of the processed material. Optical microscopy was conducted on heat treated
samples to determine their grain size and refinement.
Monotonous tensile testing of processed materials showed that there was significant
strengthening after the first extrusion. Further processing resulted in increasing values of yield strength and ultimate tensile strength, with ductility at failure varying depending
upon which processing route was used. The best tensile strength results were obtained
after processing Routes 8C' and 16E, due to the significant grain refinement these routes
produced.
X-ray diffraction revealed increases in strength of preferred texture along the
directions [111] and [001], perpendicular to the transverse plane, for all specimens that
were processed using ECAE. TEM observations showed a consistent refinement of
grain size as the amount of processing increased, especially within Routes C' and E.
Hardness measurements of heat treated specimens showed that the onset of
recrystallization occurred at approximately the same temperature of recrystallization as
that of pure iron, 450ðC. The recrystallization curves for all samples showed that grain
growth begins at a temperature of around 700ðC.
The low carbon content of IF steel made optical microscopy challenging. The grain
size of annealed materials becomes finer and more uniform, ranging between 60 and 90
üm2, at high strain levels under Routes C' and E, due to the many potential nucleation
sites developed in highly worked material.
26
Maisonobe, Romain. "Mesure du coefficient de corrélation angulaire a entre l'électron et l'antineutrino dans la désintégration ß du neutron avec le spectromètre aSPECT." Phd thesis, Université de Grenoble, 2014. http://tel.archives-ouvertes.fr/tel-01060163.
Full textAbstract:
La désintégration beta du neutron est définie par divers coefficients de corrélation mesurables qui sont utilisés pour déterminer des paramètres du Modèle Standard et rechercher de nouvelle physique. L'objectif du spectromètre aSPECT est de mesurer le coefficient a de corrélation angulaire entre l'électron et l'antineutrino avec une précision sans précédent de 1%. Ce coefficient est extrait à partir d'une mesure de haute précision du spectre d'énergie des protons. Un point central de cette thèse est l'analyse du bruit de fond, motivée par les observations de décharges durant le temps de faisceau de 2011, et par une précédente indication d'une dépendance sur le potentiel de sélection des protons. Au cours de cette thèse, plusieurs mesures ont été réalisées hors ligne, en absence de particules ionisantes issues de la désintégration du neutron. Un bruit de fond "interne" (rayons-X et ions) a été identifié. Son influence sur da/a est de l'ordre de 10^-5 à 10^-4 suivant le niveau du vide (~10^-9 mbar) et la configuration du spectromètre. L'analyse des données du temps de faisceau en 2013 permet de construire un modèle de correction des différents bruits de fond présents dans l'expérience de désintégration du neutron, en considérant sa dépendance dans le temps. La correction est d'environ 3% sur le coefficient pour une configuration et un vide standard, mais elle peut atteindre 7% dans une configuration défavorable. Pour réduire ce bruit de fond, un champ électrique de dérive est appliqué au-dessus du maximum du potentiel de sélection. Des mesures supplémentaires réalisées durant ce temps de faisceau incluaient des tests systématiques comme les effets de bord (profil du faisceau) et différentes configurations des électrodes. Afin d'obtenir le résultat final, l'analyse doit être complétée en incluant les différentes corrections et en la comparant avec des simulations des effets systématiques.
27
Nam, Moon-Sun. "Magnetotransport in BEDT-TTF salts." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342589.
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28
Sanchez, Padilla Benjamin. "Rotational mechanical effects driven by the transfer of the acoustic orbital angular momentum." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0452.
Full textAbstract:
Ce travail de thèse traite des effets mécaniques rotationnels résultant de l'interaction son-matière en présence de transfert de moment angulaire de nature orbitale. Deux approches expérimentales sont mis en œuvre, toutes deux utilisant des ondes ultrasonores se propageant dans l'air et des objets de taille centimètrique obtenus par impression 3D imprimés et se comportant comme des miroirs structurés imprimant un profil de phase hélicoïdal au champ réfléchi. Le résultat principal consiste en la mesure directe quantitative du moment angulaire orbital porté par un faisceau vortex via deux approches indépendantes. La première est basée sur l’utilisation d’un miroir hélicoïdal placé à l’interface air-eau, et la seconde repose sur le développement d'un oscillateur mécanique de torsion forcé par le transfert de moment angulaireWe study the rotational mechanical effects resulting from sound-matter interaction in the presence of orbital angular momentum transfer. A set of experimental realizations are implemented by using ultrasonic waves propagating in the air and 3D printed centimeter-sized objects acting as structured mirrors imparting a helical phase profile to the reflected wave. The main result consists of the quantitative direct measurement of the orbital angular momentum carried by acoustic vortex beams via two independent approaches. The first one is based on the use of a freely rotating helical mirror placed at air-water interface, and the second one relies on the development of a torsional mechanical oscillator driven by acoustic orbital angular momentum
29
STELLA, UGO. "Light manipulation in multilayered photonic structures." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2842499.
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30
Gauthier, Graham A. "Angular effects in the STACEE photon detectors." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=78366.
Full textAbstract:
The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a ground based gamma-ray telescope located in Albuquerque, NM. This thesis describes the development of an instrument, at McGill University, to study the angular response of the STACEE photon detectors to specific lighting conditions. The STACEE photon detectors consist of a photomultiplier tube (PMT) which is optically coupled to a Dielectric Totally Internally Reflecting Concentrator (DTIRC). A deeper understanding and parameterization of each constituent of the STACEE detector is integral to optimizing of the performance of the detector itself.
31
Chadwick, Helen J. "Angular momentum polarisation effects in inelastic scattering." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:474b04fa-4f50-4618-88ab-c85878723f2a.
Full textAbstract:
In this thesis, a joint experimental and theoretical investigation of the vector properties that describe the inelastic scattering of a diatomic radical with an atomic collision partner is presented. A particular emphasis is placed on those correlations that include the final rotational angular momentum, j', of the radical. The depolarisation of both NO(A) and OH(A) brought about through collisions with krypton has been studied, providing a measure of the j-j' correlation, where j is the initial rotational angular momentum associated with the diatom. The total depolarisation cross- sections for both collisional disorientation and disalignment have been measured using quantum beat spectroscopy, and modelled theoretically using quasi-classical trajectory (QCT) calculations. The agreement between experiment and theory for NO(A)-Kr is excellent, but is not observed for OH(A)-Kr under thermal conditions. This has been attributed to the importance of electronic quenching in OH(A)-Kr. The depolarisation cross-sections have also been determined at a higher collision energy for OH(A)-Kr where electronic quenching is less significant, and the experimental results are in better agreement with those obtained theoretically. The NO(A)-Kr depolarisation cross-sections fall with increasing rotational quantum number, N, whereas for OH(A)-Kr, they exhibit less of an N dependence. This trend is mirrored in the elastic depolarisation cross-sections, which have also been determined experimentally for OH(A)-Kr. The significantly attractive and anisotropic nature of the OH(A)-Kr potential energy surface (PES) accounts for these observations. The j-j' correlation is extended to include the initial (relative) velocity (k) in a new theoretical treatment of the k-j-j' correlation. The formalism developed is used with the results from the QCT calculations for NO(A)-Kr and OH(A)-Kr to provide further insight into the mechanism of depolarisation in the two systems. Collisions of NO(A) with krypton do not cause significant depolarisation due to their impulsive nature, and the projection of j onto the kinematic apse is conserved. In contrast, collisions of OH(A) with krypton effectively randomise the direction of j, again showing the influence of the anisotropic and attractive nature of the PES. However, the projection of j onto the kinematic apse is still conserved. The inelastic scattering of NO(X) with argon and krypton has also been investigated, using a crossed molecular beam apparatus. The initial Λ-doublet state of the NO(X) was selected using hexapole focussing, and the products of the collision detected using velocity mapped ion imaging. The state to state differential cross-sections (equivalent to the k-k' correlation, where k' is the final relative velocity) have been measured for collisions which conserve the initial spin-orbit level of the NO(X) with krypton. The same parity dependent effects were seen as have been observed previously for NO(X)-Ar. The collision induced alignment (equivalent to the k-k'-j' correlation) of NO(X) as a result of scattering with argon has also been determined experimentally. The results can be explained classically by considering the conservation of the projection of j onto the kinematic apse.
32
Steele, T. A. "Chlorine atom reactive scattering : angular momentum effects." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356420.
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33
Ayieta, Elijah Omolo. "effects Of Absorbers on Perturbed Angular Correlation Spectrum." Miami University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=miami1103051277.
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34
Magallanes, González Hernando. "Mechanical effects of light in presence of optical spin-orbit interaction." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0437.
Full textAbstract:
Des interactions entre la matière et la lumière sont à l'origine de phénomènes opto-mécaniques. L'une des caractéristiques distinctives de l'interaction lumière-matière est l'interaction spin-orbite de la lumière. Cette dernière s'étudie au sein d'un domaine de recherche émergent consacré à l'étude des effets opto-mécaniques en présence de l'interaction entre la polarisation et des degrés de liberté spatiaux de la lumière. En particulier, ce travail vise à observer directement la manifestation (i) des forces latérales et (ii) des couples optiques gauches qui sont des effets opto-mécaniques contre-intuitifs. On utilise pour cela des milieux non homogènes et anisotropes comme ingrédients essentiels à la fabrication d’éléments optiques spin-orbite. Nous rapportons tout d'abord, les tentatives d’observations expérimentales directes, à partir des résultats préliminaires obtenus préalablement dans notre groupe de recherche. Nous présentons ensuite de nouvelles propositions d'expérimentations ainsi qu'une généralisation adaptée au cas des forces latérales. Par conséquent, nous rapportons d’une observation directe à l’échelle du millimètre des forces latérales optiques et des couples optiques gauches dépendantes du spin en effectuant une étude complète. Il ressort de l'analyse des deux phénomènes que leurs vitesses peuvent être augmentées en réduisant l'inertie ou la taille des éléments optiques spin-orbite au point de rendre les phénomènes significatifs à l'échelle microscopique et intéressants pour les applications technologiques. Nous faisons un rapport chronologique de notre travail expérimental consistant à observer le moment de force orienté à gauche à l'échelle du micromètre en utilisant des versions miniaturisées des échantillons précédents. Comme la dernière tentative n’était pas concluante, nous finissons par proposer de nouvelles stratégies prometteuses pour manipuler de tels micro-objetsInteractions between light and matter cause optomechanical phenomena, where a distinctive feature of light-matter interaction, namely, the spin-orbit interaction of light, takes place within an emerging research area dedicated to the study of optomechanical effects in the presence of the interplay between polarization and spatial degrees of freedom of light. In particular, this work aims to directly observe the manifestation of (i) lateral forces and (ii) left-handed torques, which are counterintuitive optomechanical effects, by using inhomogeneous and anisotropic media as a critical ingredient for the manufacture of spin-orbit optical elements. Hence, we report on their direct experimental observations attempts, starting from the preliminary results obtained in our group before this work, and then present our new proposals and further generalization to the case of lateral forces. Consequently, we report on a millimeter-scale direct observation of optical spin-dependent lateral forces and left-handed torques with a full study. From the analysis of both phenomena, it turns out that their speed can be increased by reducing the spin-orbit optical elements inertia or size, making the phenomena relevant at microscopic-scale and interesting for technological applications. Thus, we account for our experimental journey chronologically, to observe the left-handed torque at micrometer-scale with samples that correspond to miniaturized versions of previous ones. Since the last results were inconclusive, we finish by proposing new strategies of manipulation of such micro-elements with promising implementation
35
Tramontano, Rogerio. "Metodologia de redução dos espectros de correlação angular perturbada." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-20022014-144207/.
Full textAbstract:
Medidas de correlação angular perturbada diferencial no tempo - TDPAC - foram efetuadas com um sistema de detetores de HPGe com o objetivo de ampliar o conjunto de nuclídeos utilizáveis como sondas de prova de campo magnético e de gradiente de campo elétrico na matéria. A análise dos espectros obtidos considera a convolução angular de ordem superior a dois, o que está fora do escopo do procedimento convencional quando se utiliza o arranjo experimental padrão. O algoritmo é baseado no método dos mínimos quadrados e considera rigorosamente as incertezas estatísticas dos dados. O programa de cálculo implementado é orientado a objetos, que representam as estruturas matemáticas envolvidas na redução dos dados pelo método dos mínimos quadrados e os sistemas físicos característicos do experimento. Os detetores semicondutores mostraram-se inadequados ao estudo de materiais por TDPAC nas condições experimentais disponíveis. O método de análise proposto aqui foi aplicado à redução dos espectros obtidos em outros laboratórios, que utilizam cintiladores rápidos, resultando na determinação de parâmetros associados à estrutura cristalina para os quais a análise convencional não é sensível, em particulas dos coeficientes de atenuação temporal da correlação para cada uma das freqüências de oscilação. Esta metodologia permite calcular corretamente as incertezas nos parâmetros, notadamente nas frações de ocupação de diferentes sítios pela sonda de prova.Time dependent perturbed angular correlation TDPAC measurements were performed with a HPGe detector array aiming to increase the set of nuclides usable as magnetic field and electric field gradient probes in matter. The analysis of the obtained spectra takes into account the convolution of the perturbation function with the detector time response and angular correlation coefficients of order greater than two, which is not in scope of the conventional procedure. The algorithm is based on the least-squares method and considers rigorously the data statistical uncertainties. The implanted computer code is built on objects representing the mathematical entities used in data reduction by the least-squares method and the physical components of the experiment. The semiconductor detectors were found unsuitable for material study through TDPAC in the available experimental conditions. The analysis method proposed here was applied to the reduction of spectra obtained by other Laboratories that use fast scintillators, giving crystalline structure related parameters which cannot be determined in the conventional analysis, particularly correlation time attenuation parameters for each oscillation frequency. The uncertainties in the fitted parameters are correctly calculated by this method notably in the site probe occupation fractions.
36
Kaassamani, Shatha. "Polarization Spectroscopy of High Order Harmonic Generation in Semiconductors Orbital angular momentum from semiconductor high-order harmonics All semiconductor enhanced highharmonic generation from a single nanostructured cone." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP091.
Full textAbstract:
Depuis sa première observation, la génération d'harmonique d'ordre élevé (HHG) dans les cristaux s'est avérée d'être une source efficace, contrôlable et compacte de rayonnement XUV cohérent. Dans cette thèse, nous étudions la génération d'harmonique d'ordre élevé (HHG) dans le graphène, et dans différents semi-conducteurs principalement oxyde de zinc, silicium, arséniure de gallium et oxyde de magnésium. Nous observons que les propriétés du laser, notamment l'intensité, polarisation et ellipticité ainsi que les propriétés du cristal impactent de manière corrélée au processus de génération d'harmonique. De plus, nous surlignons le rôle important des effets de propagation linéaire et non linéaire, surtout l'effet Kerr, qui peut modifier l'efficacité de génération d'harmonique. Bien que ceux-ci induisent des limitations, dans certaines conditions ils présentent un avantage. Finalement, nous démontrons la possibilité d'augmenter localement l'intensité du laser par confinement dans un cône nanostructuré et ainsi d’accroître le flux harmonique généré. Enfin, nous démontrons une application en imagerie par diffraction cohérente de la source harmonique nanostructuréeSince its first observation, a decade ago, high harmonic generation (HHG) in crystals has proved to be an efficient, controllable and compact source of coherent XUV radiation. In this thesis, we investigate HHG in 2D materials, particularly graphene, and in different semiconductor crystals mainly zinc oxide, silicon, gallium arsenide and magnesium oxide. We find that the laser properties, such as its intensity, polarization and ellipticity, and the crystal properties are interrelated. Moreover, we shed the light on the role of the linear and nonlinear propagation effects mainly the Kerr effect, upon laser interaction with the crystal, which can significantly influence the high harmonic generation efficiency. Although this presents major limitations, we show that in some cases it turns out to be an advantage. Finally, we demonstrate the manipulation of the harmonic radiation at the source of the emission by patterning nanostructures to confine and enhance nanojoule laser pulses, and generate harmonic beams carrying orbital angular momentum. Lastly, we successfully image a micrometer-sized sample by the coherent diffractive imaging (CDI) technique based on solid-state harmonics
37
Johnston, Alan. "The effects of the asymmetrical curvature of light on angular observations." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309548.
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Juricevic, Igor. "The effects of angular separation and binocular viewing on apparent visual angles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0002/MQ45496.pdf.
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Padmabandu, Gamaralalage Gunasiri 1956. "Angular momentum of light and its mechanical effects on a birefringent medium." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276914.
Full textAbstract:
The torque exerted by a beam of polarized light on a half-wave plate which alters its state of polarization is calculated for several laser wavelengths and intensities using electromagnetic theory. The second-order torque that arises through the nonlinear interaction is formulated and the numerical values are calculated for the 42m crystal class. The experiment used to detect the existence of the torque is reviewed and a demonstration experiment is suggested.
40
Al, Husna Husyira. "Characterisation of spectral and angular effects on photovoltaic modules for energy rating." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/33553.
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This thesis presents work aimed at the development of practical and simplified methods for advanced characterisation of PV modules while reducing energy yield estimation uncertainties, focusing on the spectral and angular effects. In this work, practical characterisation method to measure the spectral response (SR) curve of PV modules have been developed based on the polychromatic method. Improvement of the method have been achieved through the development of new measurement setup and detail evaluation of the polychromatic fitting algorithm. Set of coloured plate with unique transmission profiles supplemented with a smaller number of optical bandwidth filters used in the measurement setup resulted in high throughput irradiance (the lowest is measured at 150 W/m2). High uniformity of the throughput irradiance over the measurement plane contribute to low uncertainty in the measurement of short-circuit current where the highest estimated uncertainty lays within the uncertainty margin for the STC measurement, at 2.5%. Measurement of optical/electrical of device under test with associated uncertainty are combined with the fitting algorithm through the Monte-carlo simulation method. The uncertainty in the final determination of SR characteristic gave the value of 7%, with about ±10% agreement between the SR curves obtained through the polychromatic method to the conventional monochromatic method. The measurement of angular response developed in this method employed the indoor measurement setup with the additional turn table attachment. The evaluation of divergent light of the non-ideal light source and the accuracy in angle adjustment of the turn table have been quantified and incorporated into the angular response measurement as uncertainties. Partial illumination method are applied for a reliable extraction of operating current in the measurement of PV modules with the uncertainty estimated at 1%. 4% variation in the measurement of angular dependency of various PV devices at high tilt angle have been realised which translate to about 1.5% difference in the simulated annual energy performance. The application of the same simulator in the development of spectral and angular response measurement in this work creates the potential for the angle-dependent spectral response characterisation on module scale. This have been realised through a simulation. Low uncertainty in energy yield is important as this indicate the risk in the investment of PV project. Detail evaluation with accuracy and uncertainty analysis of the works to be described will further improve the uncertainty in the measurement of spectral and angular response of PV modules, hence better accuracy in the assessment of energy yield can be achieved.
41
Karpuz, Pinar. "Investigation Of The Effects Of Equal Channel Angular Extrusion On Light Weight Alloys." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614036/index.pdf.
Full textAbstract:
Severe plastic deformation methods are of great interest in industrial forming applications, as they give rise to significant refinement in microstructures and improvements in mechanical and physical properties. In the &ldquoEqual Channel Angular Extrusion (ECAE)&rdquo
, which is the most common method for production of ultrafine grained bulk samples, very high plastic strains are introduced into the bulk material without any change in cross section. This study is composed of two main parts. Part I focuses on the plastic deformation behavior of Al alloys by modeling ECAE with Msc. Marc finite element software. A series of numerical experiments were carried out for the die angles of 90°
, 120°
, and 150°
, different friction conditions, and different round corners. Besides, the effects of strain hardening characteristics of the material, strain hardening coefficient (K) and exponent (n) of Hollomon&rsquo
s law, on corner gap formation and strain homogeneity in equal channel angular pressing process were investigated quantitatively. The results were compared and verified with those of the upper bound analysis. The numerical results showed that the process performance can be improved by modifying the die corner curvature accordingly, without running time consuming simulations. On the other hand, the aim of Part 3 is to investigate the texture evolution, mechanical response and the corresponding mechanisms, in terms of the flow stress anisotropy and tension-compression asymmetry in the ZK60 Mg alloy. The alloy was processed using ECAE, with different processing routes and temperatures, in order to produce samples with a wider variety of microstructures and crystallographic textures. Several mechanical tests and microstructure examinations were carried out
and the flow stress anisotropy and tension-compression asymmetry of the as-received and processed samples were measured. It was found that the initial texture has a strong effect on the resulting textures
and the textures, combined with the microstructure effect, define the mechanical properties of processed samples. Thus, the tension-compression asymmetry and the flow stress anisotropy variations in the processed samples are attributed to the generated textures and it is possible to control these properties by controlling the processing route and temperature.
42
Bistoni, Oliviero. "Intrinsic vibrational angular momentum driven by non-adiabatic effects in non-collinear magnetic systems." Doctoral thesis, Università degli studi di Trento, 2022. https://hdl.handle.net/11572/328688.
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In absence of external fields, vibrational modes of periodic systems are usually considered as linearly polarized and, as such, they do not carry angular momentum. Our work proves that non-adiabatic effects due to the electron-phonon coupling are time-reversal symmetry breaking interactions for the vibrational field in systems with non-collinear magnetism and large spin-orbit coupling. Since in these systems the deformation potential matrix elements are necessarily complex, a nonzero synthetic gauge field (Berry curvature) arises in the dynamic equations of the ionic motion. As a result, phonon modes are elliptically polarized in the non-adiabatic framework and intrinsic vibrational angular momenta occur even for non-degenerate modes and without external probes. These results are validated by performing fully relativistic ab-initio calculations on two insulating platinum clusters and a metallic manganese compound, with non-collinear magnetism. In both cases, non-adiabatic vibrational modes carry sizeable angular momenta comparable to the orbital electronic ones in itinerant ferromagnets.
43
Kadri, Shabibahmed Jehangir. "Microstructural breakdown and scale-up effects in equal channel angular extrusion of cast copper." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4341.
Full textAbstract:
The primary objectives of this study were: (1) to verify the effectiveness of ECAE
to induce equal amounts of strain and grain refinement in bars of different cross-sectional
areas, (2) to determine the effectiveness of ECAE in breaking down the as-cast
macrostructure in CDA 101 Cu and in producing a homogeneous material containing
micron-scale grains upon recrystallization, and (3) to determine a thermomechanical
processing (TMP) schedule (from the ones examined) that produces the best
microstructure in terms of grain size and uniformity. The effects of extrus ion route, levels
of strain and intermediate heat treatment were investigated.
To achieve the first objective, bars having square cross-sections of three different
sizes, 19 mm, 25 mm and 50 mm, were processed up to eight ECAE passes through
routes A, B, C and E. To achieve the second and third objectives, bars were processed up
to eight ECAE passes with and without intermediate heat treatments through routes Bc,
C, E and F. ECAE processing was carried out in a 90o extrusion die with sliding walls at
an extrusion speed of 2.5 mm/s. Recrystallization studies were carried out on the
processed material to evaluate the recrystallization behavior and thermal stability of the
material. The as-worked and recrystallized materials were characterized by Vickers
microhardness, optical microscopy (OM) and transmission electron microscopy (TEM).
Results indicate that similar hardness values, sub-grain morphology and
recrystallized grain size are generated in the three bars having different cross-sectional
sizes processed through ECAE. ECAE is shown to induce uniform strain in all three billet
sizes. ECAE is therefore shown to be effective in scale-up to a size of at least 50 mm,
with larger billets giving better load efficiency. Results from the later parts of this study indicate that eight extrusion passes via
route Bc produces the best microstructure in terms of grain size and microstructural
uniformity. The routes can be arranged in the sequence Bc> E, F> C for their ability to
produce a uniform recrystallized microstructure with small average grain size.
Macroscopic shear bands are sometimes generated during extrusion depending upon the
initial grain morphology and texture of the material.
44
Ailes-Sengers, Lynn H. "Pulse broadening, polarimetric and angular memory effects of wave scattering from very rough surfaces /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5856.
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Herö, Johan. "The effects on knee angular velocity after a 6-weeks training period with the new training device ProPrioPlate- a pilot study." Thesis, Högskolan i Halmstad, Biomekanik och biomedicin, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-25040.
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AbstractBackground: ACL injuries is common and can result in long term disability or even have a career ending outcome for the athlete. Women are more exposed to ACL injuries than men are and several factors increase the risk of ACL injuries for women where one is the knee angle velocity. It seems that prevention programs involving plyometric- and strength training has been most effective on altering these risk factors for knee injuries. But many programs involve several exercises which makes it very time consuming. Since the gluteus muscles is our main hip abductor and hip stabilizer it is of great importance for controlling the knee. The ProPrioPlate (PPP) is a device that has been validated and shown to activate the gluteus medius 40% more in a squat compared to a regular bodyweight squat.Purpose: To investigate if a 6 week long training period, 3 sessions/ week, 5minutes/session with the PPP could decrease the mean abduction angular velocity (°/sec) of the knee joint in a Drop jump (DJ) in women with poor knee stabilityMethod: An experimental study design was used. Twelve female athletes with poor knee stability and signs of knee valgus in a drop jump conducted a 6 weeks training program to investigate any changes in abduction angular velocity in a DJ. 3D motion analyzes were performed before and after the training period. Wilcoxon signed ranked test was used to investigate if there were any changes in results between the different test occasions.Results: Median abduction angular velocity of the test performed before the intervention was -34. 34 (min -70. 65 max -11. 53) deg/sec and after the intervention median -34. 22 deg/sec (min -51. 97 max -3. 28). The P value was 0.24 which indicate that there were no statistical significant differences between the three testing occasions. Compliance to the intervention was low, 15%.Conclusion: A 6 weeks training period with the PPP did not decrease the abduction angular velocity. Due to low compliance rate amongst of subjects no conclusion regarding the effect of the device can be made.Abstrakt:Bakgrund: Svenska ligament registret rapporterar ungefär 5000 främre korsbandsskador (ACL) årligen i Sverige. ACL skador kan resultera i långvarig frånvaro från sporten eller till och med att idrottaren inte längre kan fortsätta sin karriär. Kvinnor är mer utsatta för ACL skador än män och det är flera faktorer som ökar risken för ACL skador hos kvinnor. Forskningen pekar mot att träningsprogram som syftar till att minska risken för knäskador innefattar styrketräning och plyometrisk träning. Många träningsprogram för att minska risken för knäskador innefattar många övningar vilket gör det tidskrävande. ProPrioPlate (PPP) är ett träningsredskap som är validerat och har visats aktivera gluteus medius 40% mer i en knäböj på PPP jämfört med vanliga knäböj.Syftet med denna studie var att undersöka knätabduktionshastighet i ett dropp vertikalhopp innan och efter ett 6 veckors träningsprogram med PPP för kvinnor med bristande knästabilitet.Metod: En exprementell studiedesign har använts. Tjugo frivilliga kvinnliga idrottar med bristande knästabilitet och teckan på valgus vid dropjump genomförde ett 6 veckors träningsprogram för att undersöka om knäabduktionshastighet i ett dropp vertikalhopp förändrades efter träningsperioden. 3D analyser på testpersonerna genomfördes innan och efter träningsperioden. Wilcoxons signed ranked test användes för att undersöka skillnader mellan de olika test tillfällena.Resultat: Medianen av abduktionshastigheten före interventionen var -47,88 grader/sek (min -74,76 max -30.16), -34.34 (min -70.65 max -11.53) och efter interventionen -34.22 (min -51.97 max -3.28) grader/sek. P värdet var 0.24 vilket indikerar att det inte fanns någon signifikant skillnad mellan före- och eftertesterna. Följsamheten till träningen hos deltagarna var låg (15%).Slutsats: En 6 veckors träningsperiod med PPP minskade inte abduktionshastigheten i ett DJ. Låg åtföljnad av våra testpersoner till träningsperioden innebar att inga slutsatser gällande PPP kan utgöras.
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Ishii, Toshiki, Ken-ichi Shimada, Taku Hoshizawa, and Yuzuru Takashima. "Modeling and analysis of vibration effects on signal quality for angular multiplexed holographic data storage." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621553.
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A practical optical system design that takes into account environmental factors is highly desirable. However, it is in general a time-consuming process, which requires a massive iterations of simulations. This is also one of the bottlenecks of the optical design of angular multiplexed holographic data storage systems. To develop a practical method to evaluate the effect of vibrations, a three-dimensional vibration model is developed. The model describes the vibration effect on normalized intensity on the basis of a single statistical figure of merit. Such a single figure of merits is adopted for designing a robust and efficient write strategy, which is applicable to a wide range of vibration waveforms to increase write data transfer rate. Also, optimum optical system parameters are identified. We propose a numerical aperture of 0.572 and a pixel pitch of 6.9 mu m which can improve capacity and data transfer rate without sacrificing the vibration margin. (C) 2016 The Japan Society of Applied Physics
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Jesus, Junior Waldir Cintra de. "Effects of angular leaf spot and rust on plant growth and yield of Phaseolus vulgaris." Universidade Federal de Viçosa, 2001. http://www.locus.ufv.br/handle/123456789/11523.
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Este trabalho teve por objetivo estudar o efeito da mancha angular (Phaeoisariopsis griseola) e da ferrugem (Uromyces appendiculatus) sobre o crescimento e produção do feijoeiro (Phaseolus vulgaris).A tese foi organizada em cinco capítulos. Os dois primeiros capítulos foram escritos utilizando-se dados coletados a partir de 3 experimentos de campo, em que foram efetuadas diferentes análises. Os demais capítulos referem-se a resultados obtidos em experimentos independentes. Capítulo 1. No presente capítulo foram estudados os efeitos da mancha angular e da ferrugem, isoladas e conjuntas, sobre o crescimento (área abaixo da curva de progresso da área foliar, duração da área foliar sadia e absorção da área foliar sadia) e produção do feijoeiro. Em todos os experimentos não houve diferença estatística entre os tratamentos no tocante às variáveis área abaixo da curva de progresso da área foliar (AULAPC), duração da área foliar sadia (HAD) e absorção da área foliar sadia (HAA), entretanto todos os tratamentos inoculados diferiram do controle em severidade de doença e produção. Em geral, não obteve-se relação entre produção e doença, ao passo que a produção relacionou-se linearmente com as variáveis HAD e HAA. Concluiu-se que a mancha angular causa desfolha, enquanto que a ferrugem não afeta a área foliar. A ferrugem causou maior redução na produção se comparado à mancha angular, porém o decréscimo na fotossíntese causado pela mancha angular foi duas vezes maior. Capítulo 2. Neste capítulo foram investigados os efeitos da mancha angular e da ferrugem, isoladas e conjuntas, sobre a troca gasosa (taxa fotossintética líquida, condutância estomática e transpiração) do feijoeiro. A inoculação das plantas com P. griseola (tratamento P), U. appendiculatus (tratamento U) e com ambos patógenos (tratamento P+U) causou significante redução na taxa fotossintética líquida e na produção. Os tratamentos P e P+U resultaram em redução significativa da condutância estomática. A partir da análise dos dados foi observado que os efeitos das doenças sobre a produção podem ser explicados por decréscimos na condutância estomática e na taxa fotossintética líquida. Capítulo 3. No referido capítulo foram analisadas as relações entre mancha angular, área foliar sadia, área foliar efetiva e produção do feijoeiro. Não foi observada relação entre severidade visual ou virtual e produção, entretanto relação linear positiva foi obtida entre as variáveis duração da área foliar sadia (HAD), absorção da área foliar sadia (HAA), duração da área foliar efetiva (ELAD), absorção da área foliar efetiva (ELAA) e produção. Foi observado constância nos valores de inclinação (coeficiente angular), obtidos a partir da regressão linear entre produção e índice de área foliar sadio (HLAI), independentemente da data de plantio e estádio de crescimento do feijoeiro (de R6 a R8). HLAI é proposta como variável explanatória para um sistema transportável de manejo da doença, possibilitando recomendações precisas em nível de produtor. Capítulo 4. Neste capítulo foram avaliadas estraté gias de manejo da mancha angular do feijoeiro baseadas em aplicação de molibdênio e controle químico. Foi observado que a aplicação de molibdênio causou decréscimo na intensidade da doença, bem como promoveu incrementos na área foliar, na taxa fotossintética líquida e na produção do feijoeiro. O controle químico da mancha angular deve ser realizado durante a fase de florescimento, através de uma ou duas aplicações fungicidas. Capítulo 5. No presente capítulo foi testado a aplicabilidade do equipamento LAI-2000 (Li-Cor) para estimar o índice de área foliar (LAI) do feijoeiro. Foi concluído que o equipamento pode ser empregado sem restrições na cultura do feijoeiro.
The main purpose of the thesis was to understand the effects of angular leaf spot (Phaeoisariopsis griseola) and rust (Uromyces appendiculatus) on the variables related to plant growth and yield of common bean (Phaseolus vulgaris). This thesis was organized in to five chapters. In the first two chapters data from three field experiments were analyzed using different approaches. The last three chapters referred to independent experiments. Chapter 1. The effects of angular leaf spot and rust, separately or combined, on host growth (expressed as area under leaf area progress curve - AULAPC, healthy leaf area duration - HAD, and healthy leaf area absorption - HAA) and yield of individual bean plants were investigated. All inoculated treatments had significantly more severe disease and less yield than the control treatment. In general, yield was not related to disease severity or area under disease progress curve. In contrast, the highest yields were always related to the highest values of HAD, and HAA. The relationship between yield and HAD, and HAA was linear. It was concluded that angular leaf spot reduced the leaf area because of defoliation while rust did not affect the leaf area. Rust reduced yield more than four times that of angular leaf spot, although the decrease in photosynthesis to angular leaf spot was twice that of rust. Chapter 2. The effect of angular leaf spot and rust, separately or combined, on leaf gas exchange (net photosynthetc rate, stomatal conductance, and transpiration) of common bean was reported. The inoculation of plants with P. griseola (P), U. appendiculatus (U), and a combination of the two pathogens (P+U) caused a significant reduction in the net photosynthetic rate and yield. Treatments P and P+U resulted in a significant reduction of stomatal conductance. The interactive effects of the pathogens on yield could be explained in part by the decreases in stomatal conductance and in the net photosynthetic rate of diseased bean leaves. Chapter 3. The relationships among angular leaf spot, healthy leaf area, effective leaf area, and pod yield of common bean were evaluated. Visual and virtual severity, and area under disease progress curve (AUDPC) showed no correlation with pod yield. However, healthy leaf area duration (HAD), healthy leaf area absorption (HAA), effective leaf area duration (ELAD), and effective leaf area absorption (ELAA) were significantly correlated with pod yield. The relationships between yield and HAD, HAA, ELAD, and ELAA were linear in each of the three trials. The slope of the yield-healthy leaf area index (HLAI) relationship proved to be stable, regardless of planting date and bean growth stage (from R6 to R8). HLAI is proposed as a key explanatory variable for a transportable system of disease management; it may be useful in producing precise recommendations at the farm level. Chapter 4. The strategies to manage angular leaf spot on common bean based in molybdenum application and chemical control were studied. It was observed that the molybdenum treatments showed smaller severity of angular leaf spot, and higher leaf area, net photosynthetic rate and yield, than the treatments that had no Mo. To control angular leaf spot, it was important to spray fungicide once or twice during the flowering period, which takes place ca. 25 to 45 days after planting. Chapter 5. The applicability of the equipment LAI-2000 (Li-Cor) to estimate leaf area index (LAI) was tested. It was concluded that the equipment could be used to estimate LAI on common bean.
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Houston, Katrina M. "Effects of strain path on the microstructure of aluminum alloys during Equal Channel Angular Pressing (ECAP)." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Dec%5FHouston.pdf.
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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 2007.Thesis Advisor(s): McNelley, Terry. "December 2007." Description based on title screen as viewed on January 18, 2008. Includes bibliographical references (p. 53-55). Also available in print.
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Worcester, Katherine Sara. "EFFECTS OF INERTIAL LOAD ON SAGITTAL PLANE KINEMATICS DURING FLYWHEEL-BASED RESISTANCE TRAINING SQUATS." UKnowledge, 2018. https://uknowledge.uky.edu/khp_etds/57.
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Background: Training to increase muscular power is essential for improving athletic performance in most sports. Weight training (WT) is a common means for training muscular power. Another modality, flywheel resistance training (FRT), may be superior for improving muscular power. However, few studies have examined if FRT is kinematically similar to WT, or if FRT kinematics change with increasing inertial load. The purposes of this study were to determine how sagittal plane joint kinematics are affected by increasing inertial load during FRT squats, and to determine how FRT squat joint kinematics compare to WT squat joint kinematics.
Methods: Subjects (n=9) completed three visits for this study. On the first visit subjects completed squat 1 repetition maximum (1RM) testing. The second visit served as a full FRT familiarization session in which subjects performed one set of 5 maximal effort FRT squats at each inertial load (0.050, 0.075, and 0.100 kgm2). On the third visit, subjects were videoed in the sagittal plane while performing the FRT squat protocol. Subjects then completed 5 maximal velocity repetitions of WT squats with the barbell loaded according to the Kansas Squat Test (KST) protocol. Kinematic differences between inertial loads were determined via 1-way repeated measures ANOVAS while differences between FRT and WT were determined with paired T-tests.
Results: There were no differences in peak sagittal plane knee, trunk-hip, trunk (absolute) or ankle angles between inertial loads. Peak and mean joint angular velocities decreased with increasing inertial loads at the knee and trunk-hip. Mean joint angular velocities decreased at the ankle with increasing inertial loads, while peak and mean trunk (absolute) angular velocities were unaffected. No statistical analyses were conducted for FRT and WT comparison as not enough subjects met the criteria (n=3).
Conclusions: Sagittal plane joint kinematics are largely maintained despite increasing inertial load during FRT squats. Lower extremity joint angular velocities decreased with increasing inertial load. If training for muscular power and knee extensor velocity is the goal, then the inertia of 0.050 kgm2 is most suitable.
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Bouhier, Marie Edith. "Amélioration des performances en portée et en précision de localisation angulaire des systèmes de navigation sous-marine." Grenoble INPG, 1986. http://www.theses.fr/1986INPG0122.
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L'amelioration de la precision de localisation angulaire des systemes de navigation base-courte et ultra-courte necessite de considerer des bruits correles ou non sur les deux capteurs de reception selon la taille de la base acoustique par rapport au rayon de correlation spatiale du bruit