A dual, double-acting propulsion system is analyzed to determine how efficiently it can convert the potential energy available from liquid nitrogen into useful work. The two double-acting pistons (high- and low-pressure) were analyzed by using a Matlab-Simulink computer simulation to determine their respective mechanical efficiencies. The flow circuit for the entire system was analyzed by using flow circuit analysis software to determine pressure losses throughout the system at the required mass flow rates. The results of the piston simulation indicate that the two pistons analyzed are very efficient at transferring energy into useful work. The flow circuit analysis shows that the system can adequately maintain the mass flow rate requirements of the pistons but also identifies components that have a significant impact on the performance of the system. The results of the analysis indicate that the nitrogen propulsion system meets the intended goals of its designers.

The purpose of this work is to find optimal design for mounting cryogenic tank into ISO container frame. Solution is based on stress analyses of several designs and theirs interpretation. According to standards, set of tests, which all cryogenic containers have to pass before being put into operation, is created. Designs are tested by final element method using software ANSYS. At first, results of the stress analyses provide base for improvements targeted to better meeting with needs of the standards. In final stage, the results participate in optimum design selection.

Plusieurs molécules d’intérêt astrochimique appartenant à la famille du cyanoacétylène ont été caractérisées spectroscopiquement. Des études photochimiques ont également été menées sur ces molécules. La technique d’isolation en matrice cryogénique de gaz rare a été utilisée pour la préparation de la plupart des échantillons. Des molécules étudiées étaient : CH₃C₃N (et certains de ses isomères), CH₃C₅N, HC₅N – toutes disponibles via une synthèse organique, ainsi que celles obtenues comme produits de réactions photochimiques, principalement en matrice de Kr : HC₉N, à partir de C₄H₂ + HC₅N, et de C₁₀N₂, à partir soit de C₄H₂ + HC₅N soit de HC₅N + HC₅N. La méthode a pu être étendue à la synthèse de composés méthylés avec la formation de CH₃C₅N à partir de CH₃C₂H + HC₃N et de CH₃C₇N à partir de CH₃C₂H + HC₅N. De plus, les expériences photochimiques sur les matrices contenant HC₅N ont conduit à la détection de HC₇N et de l'anion C₅N⁻. Un mécanisme général décrivant les processus d'élongation des chaînes a été formulé. Les similarités ou différences présentes dans les règles de sélection, les écarts vibroniques, les énergies des transitions électroniques et les durées de vie de phosphorescence ont été examinées pour les séries homologues HC₂n+₁N, NC₂nN et CH₃C₂n+₁N. / Several astrochemically interesting molecules of the cyanoacetylene family have been characterized spectroscopically. Photochemical studies involving these molecules have also been performed. The cryogenic rare-gas matrix isolation technique was employed for the preparation of most of the samples. The tudied molecules were: CH₃C₃N (and some of its isomers), CH₃C₅N, HC₅N – all available via preparative organic chemical synthesis, as well as those that appeared as the products of photochemical reactions run mostly in solid Kr: HC₉N, starting from C₄H₂ + HC₅N, and C₁₀N₂, starting from either C₄H₂ + HC₅N or HC₅N + HC₅N. The method was further extended to the synthesis of methylated compounds with formation of CH₃C₅N from CH₃C₂H + HC₃N, and CH₃C₇N from CH₃C₂H + HC₅N. In addition, photochemical experiments using HC₅N containing matrices led to the detection of HC₇N and of the C₅N⁻ anion. A general scheme describing the chain elongation processes was formulated. Similarities or differences in selection rules, vibronic spacings, electronic transition energies, and phosphorescence decay times were examined for the homologous series HC₂n+₁N, NC₂nN and CH₃C₂n+₁N.

CUORE est la plus grande expérience qui recherche la double désintégration bêta sans neutrino avec des bolomètres de TeO₂. La découverte de cette transition nucléaire aurait des conséquences décisives sur la scène actuelle de la physique. Les questions suivantes trouveraient une réponse : pourquoi la matière est-elle dominante dans l’Univers? Quelle est la masse du neutrino? Le neutrino est il un particule de Majorana ou de Dirac? Ce travail présente deux approches différentes pour l’amélioration de la sensibilité de CUORE en vue de sa prochaine phase : CUPID. Dans la première partie de ce travail, une étude du modèle thermique pour les bolomètres équipés avec des NTDs est présentée dans le but de mieux comprendre la réponse des détecteurs de CUORE. Les bolomètres sont des détecteurs extraordinaires utilisés pour un grand nombre d’applications en raison de leurs performances remarquables, mais leur modélisation et leur simulation sont loin d’être complètement comprises. Deux mesures ont été effectuées pour évaluer expérimentalement deux paramètres du modèle thermique : la conductance de la colle et celle entre les électrons et les phonons. Dans la deuxième partie de ce travail, la possibilité de détecter la faible lumière Cherenkov émise par le TeO₂ est étudiée à fin de rejeter des événements alpha, le fond principal de l’expérience CUORE. Le défi consiste dans la détection d’un signal de lumière de 100 eV à moyen d’un détecteur équipé avec un NTD qui a normalement un bruit de l’ordre de 100 eV. Cette question peut être résolue grâce à l’effet Neganov-Trofimov-Luke (NTL) qui a permis de baisser le seuil du détecteur de lumière et d'améliorer son rapport signal-sur-bruit. Cet effet exploite la présence d’un champ électrique pour amplifier les signaux thermiques des bolomètres. Le rejet complet du fond alpha a été prouvé avec un photo-bolomètre amélioré par l’effet NTL et couplé à un bolomètre de TeO₂ comme ceux utilisés par CUORE. Une solution convaincante pour le rejet de fond alpha a été démontrée en vue de l’expérience CUPID. / CUORE is the first tonne-scale experiment searching for the neutrinoless double beta decay with TeO₂ bolometers. The discovery of this nuclear transitionwould have decisive consequences on the present physics scene. The following questions would find an answer: why is matter dominant in the Universe? which is the neutrino mass? has the neutrino a Majorana or a Dirac nature? This work presents two different approaches for the enhancement of the CUORE sensitivity with a view to its upgrade: the CUPID experiment. In the first part, a study of the thermal model describing NTD-based bolometers is presented with the objective to achieve a better comprehension of the response of the CUORE detectors. Bolometers are amazing detectors used for a large number of applications because of their impressive high performance, but their modelisation and simulation is far to be completely understood. Two measurements have been performed for an experimental evaluation of two thermal-model parameters: the glue and the electron-phonon conductances. In the second part, the possibility to detect the tiny Cherenkov light emitted by TeO₂ to reject alpha events — the main background of the CUORE experiment — is studied. The challenge consists in the detection of a 100-eV light signal with a NTD-based light detector that usually is characterised by a baseline noise of the order of 100 eV. This issue is solved with the employment of the Neganov-Trofimov-Luke (NTL) effect to lower the energy threshold of the light detector and improve its signal-to-noise ratio. This effect exploits the presence of an electric field to amplify bolometric thermal signals. The full rejection of the alpha background has been proved with one NTL assisted photo-bolometer coupled to a CUORE-size TeO₂ bolometer. A convincing solution for the alpha background rejection has been demonstrated with a view to the CUPID experiment.

The general aim of this work was a development of methodology and instrumentation for speciation analysis based on the combination of the selective generation of substituted hydrides with atomic absorption or atomic fluorescence spectrometry detection. The first topic of this work was the development of methodology and instrumentation for arsenic speciation analysis based on selective generation of substituted arsines with trapping in the cryogenic trap (U-tube packed with chromosorb) with AAS detection (HG- CT-AAS). The conditions of the selective hydride generation approach as well as working procedure of the cryogenic trap were optimized (appropriate approach for hydride generation, set up of heating program of cryogenic trap, new dryer - cartidge with NaOH, elimination of unspecific absorption, decreasing of the detection limits). The second important part of the work lay in applying of the developed method for arsenic speciation analysis in a homogenized mouse liver tissue. The direct slurry sampling to hydride generator was develop. Moreover the information about oxidation state (iAsIII,V , MAsIII,V a DMAsIII,V ) was obtain. The effect of relevant experimental parameters such as tetrahydroborate concentration, TRIS buffer concentration and time of pre-reduction of the samples by L-cysteine...

<p>The work presented here employs cryogenic ion spectroscopy for the study of protein structure, kinetics, and dynamics. The main technique used is IR-UV double resonance spectroscopy. Here peptide ions are generated through nano electrospray ionization, guided into a mass spectrometer, mass selected, and then guided into a cryogenically held octupole ion trap. Ions are subsequently cooled to their vibrational ground state through collisions with 5 K helium allowing for high resolution IR and UV spectra to be recorded. The IR spectra are highly sensitive to an ion’s conformation, and the well resolved UV spectra provides a means generate conformer specific IR spectra. With the use quantum mechanical calculations, it is possible to calculate the vibrational spectra of candidate structures for comparison with experimental spectra. Strong correlations between theory and experiment allow for unambiguous structural assignments to be made.</p> <p> Structural studies are performed on β-turn motifs and well as salt-bridge geometries. Beta-turns are a commonly occurring secondary structure in peptides and proteins. It is possible to artificially encourage the formation of this secondary structural element through the incorporation of the D-proline (^DP) stereoisomer followed by a gly or ala residue. Interestingly, the L-proline (^LP) stereoisomer is seen to discourage the formation of beta turn structure. Here were probe the inherent conformational preferences of the diastereomeric peptide sequences YA^LPAA and YA^DPAA. The findings agree with solution phase studies, the ^DP sequence is observed to adopt a beta turn however, the ^LP sequence is found to undergo a sterically driven <i>trans</i> à <i>cis</i> isomerization about the proline amide bond. We find the energetics associated with this unfavorable interaction and show the ability to reverse it by proper substitution of Ala₂ for a Gly.</p> <p>The studies directed towards gas phase salt bridges have been limited to single amino acids or dipeptides. Generally, these species are ionized using a metal ion or adducted with water or excess electrons in order to stabilize a zwitterionic motif. Here we take the first look at a salt bridge motif incorporated into polypeptide in order to understand how the solvation from the secondary structure can aid in stabilizing these motifs in non-polar environments. We find a unique salt bridge motif in the YGRAR sequence in which the tyrosine OH acts as a neutral bridge to form a network between the C-terminal arginine and the ion pair formed between the central arginine and C-terminal carboxylate group. This binding motif has not been discussed in literature and appears as an important structural element in non-polar environments as all salt bridge character is lost upon substituting Tyr for Phe. We are the process of mining the PDB for these types of interactions. </p> <p>To better understand how cryo-cooling impacts the resulting population distribution at 10 K we measured the distribution among the two major conformation of the YGPAA ion. This was carried out using population transfer spectroscopy. In this method conformational isomerization is induced vis single conformer infrared excitation. The change in population can be related to the final population distribution at 10 K. With this number, we were able to develop a cooling model to simulate the change in the distribution as a function of cooling. The cooling rates, were experimental established, and the isomerization rates and starting population were theoretically derived through RRKM and thermodynamic calculations. With these parameters and cooling model, we found that the room temperature population distribution is largely preserved. When isomerization events involve breaking a hydrogen bond, they become too slow to complete with the cooling time scale of the experiment, effectively freezing in the room temperature structures. These are important physical parameters to characterize when performing structural studies at 10 K.</p> <p>Finally, we demonstrate a 2-Color IRMPD technique that is able to generate linear spectra at varied temperatures. This is in sharp contrast to traditional IRMPD which results in non-linear and skewed spectra. The importance of generating linear spectra when making structural assignments is highlight by comparing the performance between both techniques. Furthermore, with this technique we show the ability to record the spectra of ion prepared with high internal energies. This provides spectroscopic snapshots of the unfolding events leading to dissociation. Overall, the versatility of this technique to record ground state spectra comparable to IR-UV DR, to record linear spectra at room temperature, and to probe dynamics proves this technique to be useful in the field of ion spectroscopy.</p>

Two-dimensional electron systems in GaAs/AlGaAs heterostructures have provided a platform for investigating numerous phenomena in condensed matter physics. The quantum Hall effect is a particularly remarkable phenomenon due to its topological properties, including chiral edge states with quantized conductance. This report describes progress made in interference measurements of these edge states in electronic Fabry-Perot interferometers. Previous interference experiments in the quantum Hall regime have been stymied by Coulomb charging effects and poor quantum coherence. These Coulomb charging effects have been dramatically suppressed by the implementation of a novel GaAs/AlGaAs heterostructure which utilizes auxiliary screening wells in addition to the primary GaAs quantum well. Using this heterostructure, Aharonov-Bohm interference is measured in very small devices which have greatly improved coherence. Robust Aharonov-Bohm interference is reported at fractional quantum Hall states nu = 1/3 and nu = 2/3. Discrete jumps in phase at nu = 1/3 consistent with anyonic braiding statistics are observed. The report concludes with proposed future experiments, including extending these results to possible non-Abelian quantum Hall states.

Inducer performance is investigated for a variety of inducer geometries operating at multiple flow conditions using computational fluid dynamics. Inducers are used as a first stage in turbopumps to minimize cavitation and allow the pump to operate at lower inlet head conditions. The formation of inlet flow recirculation or backflow in the inducer occurs at low flow conditions and can lead to instabilities and cavitation-induced head breakdown. Backflow formation is often attributed to tip leakage flow. The performance of an inducer with and without tip clearance is examined. Removing the tip clearance eliminates tip leakage flow; however, backflow is still observed. Analysis suggests that blade inlet diffusion, not tip leakage flow, is the fundamental mechanism leading to the formation of backflow. Performance improvements in turbopump systems pumping cold water have been obtained through implementation of a recirculation channel called a stability control device (SCD). However, many inducers actually pump cryogenic fluids, such as liquid hydrogen. To determine the real world effects of SCD implementation, inducer performance at on and off design flow coefficients with and without an SCD were modeled with liquid hydrogen as the working fluid. Relevant thermodynamic effects present in liquid hydrogen at cryogenic temperatures are considered. The results reveal that the SCD yields marginal changes in the head coefficient. However, a stabilizing effect occurs at all considered flow coefficients, where a reduction in backflow occurs over much of the pump operational range. This occurs due to the SCD maintaining consistent, low incidence angles at the inducer leading edge.The final consideration of this work is the acceleration of an inducer from rest to the operating rotational rate. Rapid acceleration of rocket engine turbopumps during start-up imparts significant transient effects to the resulting flow field, causing pump performance to vary widely when compared to quasi-steady operation. A method to simulate turbopump start-up using CFD is developed and presented. The defined outlet pressure is modified based on the difference between simulation inlet pressure and target inlet pressure of a previous simulation. This process is repeated until simulation inlet pressure is essentially constant during start-up. Using this novel simulation method, the performance of a centrifugal turbopump during start-up is simulated. Analysis suggests this simulation method provides a reasonable prediction of cavitation formation and inducer performance.

Soil is the most widely used material in the construction of various civil infrastructure. Various types of soils are extensively used in its natural or compacted form in the construction of dams, canals, road and railway subgrades, and waste containment structures such as soil covers and liners. These infrastructure and foundation soils are exposed to the influence of environmental factors. In the permafrost and seasonally frozen regions, soils can be in different states (e.g., saturated or unsaturated, frozen or thawed, or combinations of them) due to the variations in moisture content and temperature. The soil-water characteristic curve (SWCC), which is the relationship between soil water content and suction, is used in the interpretation and prediction of unsaturated soils behavior. Similarly, the soil-freezing characteristic curve (SFCC), which is the relationship between unfrozen water content and subzero temperature, is used in the prediction and interpretation of frozen soils behavior. In this thesis, the SWCC and SFCC of two Canadian soils (i.e. Toronto silty clay (TSC) and Toronto lean clay (TLC)) were extensively investigated for better understanding the fundamental relationship between SWCC and SFCC. The soil resilient modulus (MR) is a key material property used in the rational design of pavements. Experimental investigations were undertaken to determine the MR of five Canadian soils (i.e., TSC, TLC, Kincardine lean clay (KLC), Ottawa Leda clay (OLC), and Indian Head till (IHT)), considering the influence of moisture and temperature, with the aid of an advanced triaxial testing equipment. Two simple models were proposed for estimating the MR of frozen soils, in this thesis. In addition, an artificial neural network (ANN) model was developed for estimating the MR of the five Canadian soils considering various influencing factors. The conclusions from the various studies in this thesis are succinctly summarized below. (1) Four expressions (i.e. power relationship, exponential relationship, van Genuchten equation, and Fredlund and Xing equation) that are widely used for representing the SFCC were selected for providing comparisons between the measured and fitted SFCCs for different soils. The results suggest that the exponential relationship and van Genuchten equation are suitable for sandy soils. The power relationship reasonably fits the SFCC for soils with different particle sizes, but not for saline silts. The Fredlund and Xing equation is flexible and provides good fits for all the soils. (2) The SFCC and SWCC of TSC and TLC were experimentally determined, analyzed, and compared. Many factors influence the reliable measurement of SFCC, which include sensors’ resolution and stability, sensor calibration for each soil, and thermodynamic equilibrium condition. The hysteresis of SFCC for the two soils is mainly attributed to the supercooling of pore water. The quantitative dissimilarity in the measured SFCC and SWCC may be attributed to specimen structure variations during compaction and saturation, and during freezing / thawing processes, and cracks formation due to sensors insertion. In addition, some fundamental differences may exist between the drying / wetting and freezing / thawing processes, resulting in dissimilarity. (3) Two novel models were proposed for the estimation of MR of frozen soils. The semi-empirical model extends the mechanics of unsaturated soils and employs SFCC for prediction. Several coarse- and fine-grained saturated soils were used to validate this model. The empirical hyperbolic model was proposed considering that the frozen MR versus subzero temperature relationship resembles hyperbola. This model was validated on coarse- and fine-grained soils under saturated / unsaturated conditions. The hyperbolic model has wider application since it can be used for both saturated and unsaturated frozen soils. Both the models are simple and promising. (4) The MR of five Canadian soils subjected to wetting and freezing was determined by using the GDS ELDyn triaxial testing system. A freezing system was established for controlling the desired testing temperatures within the soil specimens. The results suggest: (i) The effect of subzero temperature on the MR is significant. (ii) For TLC, KLC, OLC, and IHT, the frozen MR versus subzero temperature relationship of the saturated specimen typically has steeper slope than specimen at the optimum water content, for the temperature range from 0 to -5 °C. (iii) The effect of stress levels on the frozen MR depends on soil type, water content, and subzero temperature. Lastly, (iv) Loading frequency does not show a significant influence on the frozen MR. (5) The MR of the five Canadian soils was determined considering wetting and freeze-thaw (F-T) conditions. The results suggest: (i) The F-T cycles result in weak soil structure due to reduction in suction, particles movement, loss of cohesion, and formation of cracks / channels. (ii) The critical numbers of F-T cycles were determined as 1, 1, 2, and 1 for TLC, KLC, OLC, and IHT at the optimum water content, respectively. (iii) The percentage of reduction in MR after the critical number of F-T cycles was strongly related to the plasticity index for specimens tested at the optimum water content. (iv) The wetting process results in the decrease in suction and enlargement of soil pores. Consequently, relatively low MR values were measured at high water contents, and the effect of F-T cycles becomes insignificant. Finally, (v) The effect of stress levels on the MR was dependent on the initial water content of the specimen and soil type.

Les magnétomètres à induction sont utilisés dans de nombreux domaines d'exploration scientifique de la géophysique à l'astrophysique. Dans ces deux domaines l'étude des composantes magnétiques des ondes électromagnétiques naturelles requiert des instruments particulièrement performants: sensibles et présentant de faibles bruits intrinsèques pour accéder à des champs magnétiques de quelques fT/ . Dans le cas d'instruments scientifiques embarqués à bord de satellites, des contraintes en température, consommation, encombrement et de tenue en radiation s'ajoutent aux autres contraintes. Les technologies de circuits intégrés permettent une rupture technologique qui se traduit par une réduction de la taille des circuits électroniques embarqués d'un facteur supérieur à 1000 tout en améliorant les performances électriques et instrumentales (réduction de la consommation, des sources de bruit, augmentation de la bande passante et durcissement de l'électronique). Une première thèse au L2E (A. Rhouni) a montré la pertinence d'une technologie CMOS pour ce type d'instrumentation. Dans la présente thèse est décrite l'étude menée sur les circuits intégrés soumis à des environnements contraignants liés aux futures missions dans lesquelles ce type d'instrument doit être embarqué (Mission JUICE de l'ESA). Ces contraintes devenant de plus en plus sévères (dose de radiations supérieure à 300krad, température inférieure à 100 Kelvin ...), leur prise en compte dans tout le processus de conception est nécessaire. Une modélisation des effets de ces contraintes sur les composants de la technologie cible de circuits intégrés a été réalisée afin de pouvoir prendre en compte ces effets dès la conception. Enfin, ces modèles ont servi à la conception d'un circuit de lecture d'un magnétomètre à induction pour l'astrophysique. / Induction magnetometers are used in many fields of scientific exploration from geophysics to astrophysics. In these two fields, the study of the magnetic components of natural electromagnetic waves requires particularly powerful instruments: sensitive and with low intrinsic noises to access magnetic fields of some fT/ . In the case of scientific instruments carried on satellites, constraints on temperature, consumption, congestion and radiation resistance are added to the other constraints. Integrated circuit technologies allow technological breakthrough, which results in a reduction in the size of embedded electronic circuits by a factor greater than 1000, while improving electrical and instrumental performances (reduction in consumption, noise sources, bandwidth and hardening of the electronics). A first thesis at the L2E (A. Rhouni) showed the relevance of a CMOS technology for this type of instrumentation. In this thesis, we describe the study conducted on integrated circuits subject to environmental constraints related to the future missions in which this type of instrument must be embarked (Mission JUICE of ESA). These constraints are becoming more and more severe (radiation dose > 300krad, temperature less than 100 Kelvin ...), taking into account throughout the design process is necessary. A modeling of the effects of these constraints on the components of the integrated circuits technology has been carried out in order to be able to take these effects into account from the design stage. Finally, these models were used to design an induction magnetometer readout circuit for space instrumentation.