The oscillating plasma torch is proposed as a potential device that will produce an oscillating shock and resulting control of the supersonic combustion process. This research will capitalize on previous results [Gallimore, 1998] which indicate that the plasma torch oscillations originate from the inherent oscillations of the voltage applied to the torch. The aim of this research is to thoroughly investigate the oscillation behavior of the plasma torch with the plan of ultimately controlling the oscillation at chosen frequencies. A modulating power system used for dynamic control of the plasma torch oscillation was designed and tested in quiescent conditions (no flow), Mach 2.4 cold supersonic flow, and Mach 2 heated supersonic flow conditions. The oscillating plasma torch used nitrogen feedstock and was operated over a frequency range of 2Hz- 4kHz. A dynamic torch model using the hybrid Mayr-Cassie electric arc model was developed to predict the plasma torch electric arc response at appropriate frequencies for interaction with supersonic combustion. In quiescent conditions, the dynamic response of the plasma torch power system and plasma jet were characterized using signal processing techniques and high speed video imaging. High speed Schlieren images were used to determine the behavior of the oscillating plasma jet in Mach 2.4 cross flow and its influence on the induced shock structure. The unsteady nitrogen-fed torch was integrated with the flush walled 4-hole aerodynamic ramp injector using hydrogen and hydrocarbon fuels at the University of Virginia Aerospace Research Lab (ARL) heated Mach 2 supersonic flow. Unsteady pressure variations from the oscillating shock produced by the plasma torch were recorded using recess-mounted Kulite pressure transducers. Also, measurements of the static pressure of the combustion produced by the oscillating plasma torch were obtained. The oscillating torch system performed well over a range of different flow conditions. It will enable active control input to the combustion process. The controllable unsteady blockage might provide a type shock interaction needed to increase turbulence and mixing augmentation [Kumar, et al. 1987]. / Master of Science

<p> Following the introduction to the field of lasers and the theories of laser oscillations in the light output, it is pointed out that calculations involving existing theories yield oscillation periods in excess of the period observed for our crystal. To account for this disagreement, the thesis proposes the inclusion of the additional loss terms of scatter and diffraction augmenting the transmission loss. The theory of Birnbaum Stocker and Welles (BSWl) is extended to include these additional loss mechan- isms and the oscillation period predicted, using the mea- sured values of these parameters is in good agreement with the. observed oscillation period. </p> / Thesis / Master of Science (MSc)

Anecdotal evidence suggests that increased numbers of waterfowl are remaining at northern latitudes throughout winter in the Mississippi Flyway. A calculated weather severity index (WSI), based on temperature and snow data, determined that local mallard abundance decreases when a WSI of 8 is reached. In mapping the WSI 8 line, mallard movement can be estimated. A fifty year trend analysis of the climatic factors driving duck migration for various locations within the Mississippi Flyway was used to determine whether climatic shifts have occurred, finding that although there are sinusoidal temperature trends throughout those years, the past decade has a longer and overall warmer trend. In examining the role of El Niño Southern Oscillation, it was found that in La Niña there is a more severe WSI, and El Niño correlates with a less severe WSI. A neutral Oceanic Niño Index caused a very high or very low WSI (was inconclusive).

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In the upcoming deep underground neutrino experiment (DUNE), Liquid Argon Time Projection Chambers (LArTPCs) will be used as the detector technology, and argon will be used as the nuclear target. In order to reduce the systematic uncertainties on the extracted oscillation parameters, a more precise description of the argon nuclear structure is needed. Electron scattering has been one of the most powerful methods of studying the nuclear structure of a target. Therefore we performed an electron scattering experiment E12-14- 012 in Hall A at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). In the E12-14-012 experiment, we collected data for the inclusive (e,e′) and exclusive (e,e′p) processes for a variety of targets (argon, titanium, aluminum, carbon) at a wide range of kinematics. This thesis presents the measurements of the double differential cross sections for carbon, titanium, aluminum and argon at beam energy E = 2.222 GeV and scattering angle θ = 15.541◦ / Doctor of Philosophy / In the upcoming deep underground neutrino experiment (DUNE), Liquid Argon Time Projection Chambers (LArTPCs) will be used as the detector technology, and argon will be used as the nuclear target. In order to reduce the systematic uncertainties on the extracted oscillation parameters, a more precise description of the argon nuclear structure is needed. Electron scattering has been one of the most powerful methods of studying the nuclear structure of a target. Therefore we performed an electron scattering experiment E12-14- 012 in Hall A at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). In the E12-14-012 experiment, we collected data for the inclusive (e,e′ ) and exclusive (e,e′p) processes for a variety of targets (argon, titanium, aluminum, carbon) at a wide range of kinematics. This thesis presents the measurements of the double differential cross sections for carbon, titanium, aluminum and argon at beam energy E = 2.222 GeV and scattering angle θ = 15.541◦ .

The Madden-Julian oscillation (MJO), also known as the 30-60day oscillation, is the strongest of the intraseasonal climate oscillations in the tropics and has significant derivative effects on extratropical circulation and intraseasonal climate. It has recently been shown that the stratospheric quasi-biennial oscillation (QBO) modulates the amplitude of the boreal winter MJO such that MJO amplitudes are larger on average during the easterly phase (QBOE) than during the westerly phase (QBOW). A major possible mechanism is the decrease in static stability in the lowermost stratosphere under QBOE conditions resulting from relative upwelling associated with the QBO-induced meridional circulation. Here evidence is presented that tropical upwelling changes related to the 11year solar cycle also modulate the boreal winter MJO. Based on 37.3years of MJO amplitude data, the largest amplitudes and occurrence rates, and the weakest static stabilities in the tropical lower stratosphere, occur during the QBOE phase under solar minimum (SMIN) conditions while the smallest amplitudes and strongest static stabilities occur during the QBOW phase under solar maximum (SMAX) conditions. Conversely, when the QBO and solar forcings are opposed (QBOW/SMIN and QBOE/SMAX), the difference in occurrence rates becomes statistically insignificant. During the coming solar minimum, at least one additional winter in the QBOE/SMIN category should occur (possibly as early as 2017/2018) during which especially large MJO amplitudes are expected and an initial test of these results will be possible. Plain Language Summary An ongoing issue in climate science is the extent to which upper atmospheric processes, including solar forcing, can influence tropospheric climate. It has recently been shown that an internal oscillation of the stratosphere, the quasi-biennial oscillation, can modulate the amplitude and occurrence rate of intraseasonal climate oscillations in the tropical Pacific during northern winter. These intraseasonal oscillations, the most important of which is the 30-60day Madden-Julian oscillation, have significant derivative effects on climate outside of the tropics, including impacts on rainfall events over the continental United States. Here evidence is presented that the amplitude of the Madden-Julian oscillation during northern winter is also modulated by the 11year solar cycle. The modulation is such that amplitudes and occurrence rates are largest under solar minimum conditions when the quasi-biennial oscillation is in its easterly phase and smallest under solar maximum conditions when the quasi-biennial oscillation is in its westerly phase. However, the available time record (37.3years of satellite measurements) is limited. During the coming solar minimum, at least one additional winter in the solar minimum/easterly category should occur (possibly as early as 2017/2018) during which larger-than-average amplitudes are expected and an initial test of the proposed relationship will be possible.

Double Chooz est une expérience dédiée à la mesure de l'angle de mélange θ₁₃ caractérisant le phénomène d’oscillation des neutrinos. Elle consiste en l’installation de deux détecteurs identiques respectivement installés à 400 m et 1050 m des deux réacteurs à eau pressurisée de la centrale nucléaire de Chooz dans les Ardennes. Les réacteurs nucléaires sont en effet à l’origine d’un flux intense d’antineutrinos électroniques (de l’ordre de 10²¹ ⊽ₑ/s pour un réacteur de 1GWe)qui peut être détecté par réaction bêta inverse dans le liquide scintillant des détecteurs : ⊽ₑ + p −> e⁺ + n. Le paramètre θ₁₃ peut ensuite être déterminé en cherchant une réduction du nombre d’antineutrinos et une distorsion du flux mesuré dans le détecteur lointain par rapport au détecteur proche. La première phase de l’expérience pour laquelle uniquement le détecteur lointain prend des données a débuté en avril 2011. En l’absence du détecteur proche dont l’installation sera terminée en 2014, une prédiction du flux d’antineutrinos non oscillé attendu dans le détecteur lointain est nécessaire à la prédiction de θ₁₃ . Dans ce manuscrit, nous présentons le travail de simulation réalisé en vue de prédire les taux de fission des deux cœurs de Chooz à l’origine des antineutrinos émis par les réacteurs. Pour cela des simulations de cœur complet des réacteurs ont été développées à l’aide du code de simulation MCNP Utility for Reactor Evolution (MURE). Les résultats de ces simulations ont permis de déterminer les taux de fission et les erreurs systématiques associées durant les périodes de prise de données et d’aboutir à la première indication d’un angle θ₁₃ non-nul en novembre 2011. / The Double Chooz experiment is designed to search for a non-vanishing mixing angle θ₁₃ characterizing the ability of neutrinos to oscillate. It consists in two identical detectors located respectively at 400 m and 1050 m of the two pressurized water reactors of the Chooz nuclear plant in the French Ardennes. Indeed, nuclear reactor are huge electron antineutrino emitters (about 10²¹ ⊽ₑ/s for a 1GWe reactor). In Double Chooz, antineutrino sare detected by the inverse beta decay process in the liquid scintillator of the detectors : ⊽ₑ + p −> e⁺ + n. The θ₁₃ parameter can be investigated searching for ⊽ₑ disappearance and ⊽ₑ energy distortion in the far detector with respect to the near detector. The first phase of the experiment during which only the far detector is taking data has started in April 2011. In absence of far detector whose installation will be completed in 2014, a prediction of the non-oscillated antineutrino flux and spectrum shape expected in the far detector is mandatory to measure θ₁₃ . In this manuscript, we present the simulation work performed to predict the fission rates of both Chooz cores responsible for the reactor antineutrino flux. In this view, a complete core model has been developed with the MCNP Utility for Reactor Evolution (MURE) simulation code. The results of these simulations were used to determine the fission rates and associated systematic errors since the beginning of data taking and led to the first indication for a non-zero θ₁₃ mixing angle in November 2011.

This thesis aims to improve the understanding of El Niño Southern Oscillation (ENSO) diversity, in its future change, modeling and predictability. How might ENSO change in the warming climate? To reach a comprehensive understanding, a set of empirical probabilistic diagnoses (EPD) is introduced to measure the ENSO behaviors as to tropical Pacific sea surface temperature (SST) climatology, annual cycle, ENSO amplitude, seasonal phase locking, diversity in peak location and propagation direction, as well as the El Niño-La Niña asymmetry in amplitude, duration and transition. This diagnosis is applied to the observations, and consistency with previous studies indicates it is valid. Analysis of 37 CMIP5 model simulations for the 20th century and the 21st century shows that, other than the projected increase in SST climatology, changes in other aspects are largely model dependent and generally within the range of natural variation. The change favoring eastward propagating El Niños is the most robust seen in the SST anomaly field. To what extent can we trust the future projection? CMIP5 models show large spreads in terms of 20th century ENSO performance. So a data-driven approach called Empirical Model Reduction (EMR) is carried out, by fitting a low-dimensional nonlinear model from the observation with a representation of memory effect and seasonality. The stochastic simulation of EMR is able to reproduce a realistic ENSO diversity statistics and a reasonable range of natural variation, thus provides an additional benchmark to evaluate the CMIP5 model biases. What are the key model components leading to a good performance to simulate and predict ENSO? Using a suite of models under the aforementioned framework of EMR, control experiments are conducted to advance the understanding of ENSO diversity, nonlinearity, seasonality and the memory effects. Nonlinearity is found necessary to reproduce the ENSO diversity features by simulating the extreme El Niños. Nonlinear models reconstruct the skewed distribution of SST anomalies and improve the prediction of the El Niño-La Niña transition. Models with periodic terms reproduce the SST seasonal phase locking but do not improve the prediction appreciably. Models representing the ENSO memory effect, based on either the recharge oscillator (multivariate model with tropical Pacific subsurface information) or the time-delayed oscillator (multilevel model with SST history information), both improve the prediction skill dramatically. Models with multiple ingredients capture several ENSO characteristics simultaneously and exhibit overall better prediction skill. In particular, models with a memory effect show an alleviated skill drop during the spring barrier and a reduced prediction timing delay. One new ENSO prediction target is to predict not only the occurrence and amplitude of El Niño (EN) but also the peak location is at the central Pacific (CP) or the eastern Pacific (EP). Many prediction models have difficulty with it, which motivates the investigation on whether such ENSO diversity has intrinsically limited predictability. Here three aspects are addressed including the source/limit of predictability, time range and uncertainty. Approaches are combined including linear inverse modeling, singular vector analysis and probabilistic measure. The results show that two similar initial conditions with western Pacific SST warming anomalies may finally develop to either CPEN or EPEN. The equatorial Pacific subsurface evolution is important to tell the final outcome. Restricted by the chaotic property, the prediction horizon appears to be ~4 months before CPEN and ~7 months before EPEN. A flavor prediction model using data's transition probabilities is introduced as a new benchmark for probabilistic prediction.

L’expérience T2K étudie les propriétés des neutrinos, en particulier le phénomène d’oscillation des neutrinos. Se déroulant au Japon, elle utilise un faisceau de neutrinos muoniques produit par le complexe d’accélérateur J-PARC, un détecteur proche, ND280 sur le site même de J-PARC pour caractériser le faisceau, et un détecteur lointain, Super-Kamiokande situé à 295 km pour mesurer les oscillations de neutrinos. Le détecteur proche permet également d’étudier les interactions des neutrinos et cette thèse porte sur la mesure des sections efficaces de diffusion profondément inélastique des neutrinos muoniques.Le manuscrit introduit d’abord la physique des neutrinos, puis l’expérience T2K et en particulier les chambres à projection temporelles du détecteur proche, en insistant sur la vérification de la qualité des données, dont j’avais la charge. L’analyse porte sur les données de T2K enregistrées jusqu’en 2013. La sélection d’interactions de neutrinos muoniques par courant chargé est ensuite présentée, ainsi qu’une étude préliminaire de la sélection d’interactions de neutrinos muoniques par courant chargé avec production d’un pion neutre. Un critère portant sur la multiplicité des traces permet d’enrichir le premier lot en interactions correspondant à une diffusion profondément inélastique de neutrinos. Finalement un ajustement, validé d’abord sur des données simulées, permet d’extraire les sections efficaces de diffusion profondément inélastique des neutrinos muoniques. / The T2K experiment studies the properties of neutrinos, particularly neutrino oscillations. It takes place in Japan and uses a muonic neutrino beam produced by the J-PARC accelerator complex, a near detector, ND280 on the J-PARC site in order to characterise the beam, and a far detector, Super-Kamiokande 295 km away in order to measure the neutrino oscillations. The near detector is also used to study the neutrino interactions and the goal of this thesis is the measurement of muonic neutrino deep inelastic scattering cross sections.The thesis first introduces neutrino physics, then the T2K experiment and more particularly the time projection chambers of the near detector, and its data quality checking that I was in charge of. The analysis is based on the T2K data recorded until 2013. The selection of charged current muonic neutrino interactions is then presented, as well as a preliminary study of the selection of charged current muonic neutrino interactions with the production of a neutral pion. A criterion on track multiplicity allows enriching the former sample in interactions corresponding to a neutrino deep inelastic scattering. Finally a fit, first validated on simulated data, allows the extraction of the muonic neutrino deep inelastic scattering cross sections.