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Neoadjuvant chemotherapy (NAC) is a common breast cancer treatment that involves administering chemotherapy for 3-6 months prior to surgery. This treatment enables more breast-conserving surgeries and even allows for the omission of surgery in some cases. However, about 31% of patients receiving NAC do not respond to the treatment. Therefore, there is a need for real-time methods to predict treatment response and improve patient outcomes. Over the last two decades, diffuse optical imaging has been investigated as a potential solution to this problem. This noninvasive and inexpensive technology uses near or shortwave infrared (NIR or SWIR) light to illuminate tissue, and detects multiply-scattered photons. However, bulky instrumentation and complicated imaging procedures have limited the clinical adoption of this technology. Furthermore, measured biomarkers including oxy- and deoxy-hemoglobin (HbO2 and HHb, respectively), water, and lipid, have had mixed results in terms of prognostic capability. To address these limitations, a new wearable optical probe technology was developed and validated in this project, including a high-optode density NIR probe for monitoring hemodynamics and a first-generation SWIR probe for quantifying water and lipid. Measurements on tissue-mimicking channel flow phantoms confirmed the ability of the NIR probe to quantify absorption contrast in vitro, and a cuff occlusion measurement demonstrated sensitivity to HbO2 and HHb in vivo. Hemodynamic oscillations at the respiratory rate were also explored in healthy volunteers and breast cancer patients as a potential new biomarker. It was demonstrated that traditional and novel breathing-related hemodynamic metrics provide tumor contrast and can potentially track treatment response. A deep-learning algorithm was developed to extract water and lipid concentrations from multi-distance SWIR measurements. The SWIR probe was validated by comparing measured water and lipid concentrations against ground truth values in emulsion phantoms. This work represents a significant step toward the development of technologies for frequent breast cancer treatment monitoring in the clinic and potentially at home.

In this study, the phenomenon of two-phase flow was investigated in a square channel. The experiment was performed with stagnant liquid conditions. The gas and liquid dynamics of the bubbly flow were observed in two regions far from the inlet. Air was inserted through a porous media at three superficial gas velocities: 4.6 mm/s, 2.5 mm/s, and 1.4 mm/s. Two techniques were applied in the experiment to measure the bubbly flow: an optical probe and an in-house developed tracking algorithm. Measurements of the bubble interface velocity, void fraction, bubble frequency, time of flight, and Sauter mean diameter were obtained by using the optical probe. The duration of the probe measurements for all three flow rates and both regions lasted approximately 33 hours. The tracking algorithm was used to analyze the experimental data for two visual methods: shadowgraphy and Particle Tracking Velocimetry (PTV). Shadowgraphy provided gas-phase measurements of the bubble centroid velocity and its fluctuations, void fraction, bubble size, and Reynolds stresses. Five data sets were acquired for each flow rate, resulting in a total of 327,540 shadowgraphy images. Liquid parameters such as the velocity, fluctuations in the velocity, and the Reynolds stresses were provided by PTV. Only one data set containing 10,918 images was obtained from liquid measurements for each flow rate. One data set was sufficient to provide reliable statistics since tracking two consecutive images lead to approximately 15,000 velocity vectors. The data obtained from this study was an effort to assist in the verification, validation, and improvement of two-phase flow simulations.

L’atomisation assistée est un procédé de formation d’un spray de gouttelettes issu d’une nappe liquide sous l’action d’un courant gazeux à forte vitesse dans un injecteur. Ce procédé est très utilisé dans de nombreuses applications industrielles. Nous étudions la succession d’instabilités hydrodynamiques qui génère les gouttes du spray à l’aide d’une méthode LIF pour mesurer la fréquence des vagues et d’une sonde optique pour la granulométrie des gouttes. Nous validons expérimentalement un nouveau modèle de stabilité linéaire inviscide pour l’instabilité de cisaillement, intégrant un profil de vitesse avec déficit à l’injection. Des simulations numériques et un modèle spatio-temporel de stabilité linéaire sont utilisés pour mettre en avant de nouveaux mécanismes de déstabilisation, de croissance des vagues et de création de gouttes. Les lois d’échelles connues prédictives du diamètre moyen des gouttes en fonction du Weber gaz sont testées pour de nouvelles variables d’étude. / Assisted atomization is a process used to form a spray of droplets. A slow liquid phase is strippedby the action of a strong gas current in order to generate the spray. This process is used in manyindustrial applications. We study the succession of hydrodynamic instabilities generating dropletsby means of a LIF method to measure the frequency and growthrate of waves, and with an opticalprobe to measure drop size and velocity. We validate experimentally a model including an interfacialvelocity deficit in the inviscid stability analysis. Experiments are compared to numerical simulationsand spatiotemporal stability analysis results : the confrontation of these three approaches is used tobring forward new mechanisms of destabilization, growth of waves and creation of drops. We assessthe influence of liquid thickness and dynamic pressure ratio on the dependency of the mean dropletdiameter with the Weber number.

The research presented in this dissertation focuses on improvements made to lithium niobate leaky-mode modulators for both holographic video and optogenetic applications. The specific improvements found herein are: (1) characterization of leaky-mode modulators to decrease driver bandwidth to match that of commodity graphics processing units, (2) the implementation of surface relief gratings as input couplers to replace rutile prism coupling, (3) the addition of backside surface relief gratings to create an orthogonal output face for the leaky-mode modulator, and (4) the creation of superimposed surface relief gratings in lithium niobate to enable multiple wavelength coupling at a single input angle. These advancements for leaky-mode modulators open avenues in display technologies and optogenetics. As a display technology, the leaky-mode modulator can not only be used more effectively in holographic monitors, but can stand alone as a transparent near-eye display. In regards to optogenetics, these technologies allow for the creation of a highly advanced light delivery method, with multiple illumination angles through non-mechanical steering, a large output area to probe size ratio, and support for simultaneous multiple wavelength output in both common and disparate locations.

No / The development of kerosene–water up-flow in a vertical pipe of 77.8 mm inner diameter and 4500 mm, length downstream of a 90◦bend, hasbeen investigated using a Pitot tube and dual optical probe. The CFD ANSYS Fluent 12.0 is used to model the flow and the results are comparedwith experimental data. The CFD provides detailed information on flow structure which is difficult to obtain in experiments. The experimentalmeasurements of the local parameters demonstrate that the single phase and two-phase flows reached the fully developed axisymmetricalconditions at L/D = 54. These results also show the severe asymmetry distributions of the two-phase flow parameters at the entrance region(L/D = 1). The predictions from Fluent are found to be in close agreement with experimental data for L/D ≥ 16 but there is a significant discrepancyat L/D = 1.

Sur la table de sortie d’un laminoir à chaud, le refroidissement des bandes d’acier est principalement assuré par des rampes de jets d’eau gravitaires qui vont impacter directement la surface supérieure de la bande en défilement. La température de la bande est initialement entre 800 et 900 °C et on cherche à la refroidir à des températures nettement inférieures mais précises avant son bobinage, cette température allant de la température ambiante à 700 °C suivant les propriétés voulues pour l’acier. Ce refroidissement assuré par les rampes de jets est transitoire et la vitesse de refroidissement est variable suivant la nature du régime de refroidissement. Le point de remouillage est défini par la température à laquelle le régime d’ébullition en film stable se termine et s’accompagne généralement d’une hausse significative des flux de refroidissements. Dans ce travail de thèse, nous avons cherché à caractériser ce point par des mesures d’épaisseur de vapeur effectuées à l’aide de sondes optiques. Les sondes optiques permettent de savoir si leur zone sensible est majoritairement dans le gaz ou le liquide et sont généralement exploitées pour faire des mesures de taux de vide. L’utilisation qui en est faite ici, à savoir une mesure précise de position d’interface, a demandé une calibration expérimentale précise afin de connaitre la position exacte de l’interface sur la zone sensible. Afin de disposer d’un outil fonctionnel, nous avons également cherché à modéliser la réponse des sondes à l’aide d’une méthode de lancer de rayons et en prenant en compte la formation du ménisque sur la pointe. Enfin, cette calibration et ce modèle ont été confrontés à des mesures expérimentales dans le cas du refroidissement d’une zone hémisphérique porté à haute température et donnant lieu à un régime d’ébullition en film stable / On a run out table of a hot rolling mill, the cooling of steel strips is mainly provided by ramps of water jets falling down that will directly impact the upper surface of the strip. The temperature of the strip starts between 800 and 900 °C and it is intended to cool at temperatures much lower than the start but still accurate before its winding, the temperature ranges from ambient temperature to 700 °C depending on the required properties for the steel product. This water-based process ensures a transient cooling at an uneven rate depending on the nature of the boiling regime. The rewetting point is defined by the temperature at which the stable film boiling regime ends. In general, the cooling fluxes show a significant increase at this particular transition. In this thesis, we sought to characterize rewetting by vapor thickness measurements and analysis using optical probes. The optical sensors inform us whether their sensitive area is mainly in the gas or in the liquid and are generally used to make void fraction measurements. The use that is made here, namely a precise measurement of the position of the interface, required a precise experimental calibration in order to know the exact position of the interface on the sensitive area. In order to have a working tool, we also modeled the response of the probes by using a ray tracing method and taking into account the formation of the meniscus on the tipoff the probe. Finally, the calibration and model were compared with experimental measurements in the case of the cooling of a hemispherical area initially at high temperature that provides a stable film boiling regime when it is partially immersed

Dans l'objectif de maîtriser le démarrage des moteurs fusées en vol balistique, il est proposé de caractériser le transitoire de remplissage des cavités d'injection des organes de combustion. L'étude s'effectue principalement sur la cavité tampon, appelée dôme. Le comburant est maintenu sous pression en amont d'une vanne dont l'ouverture contrôle son passage vers une chambre tampon qui est liée à la chambre de combustion à travers un réseau d'injecteurs. Afin d'empêcher la remontée du carburant vers la chambre tampon, un gaz balaye la chambre de l'entrée vers les injecteurs. Cette étude expérimentale consiste à décrire la structure spatio-temporelle de l'écoulement diphasique dans la cavité tampon suite à l'ouverture de la vanne en présence de l'écoulement du gaz de balayage. Il s'agit de suivre l'évolution de l'écoulement sur des temps courts (quelques centaine ms) par un ensemble de mesures (débits, pressions, distribution spatiale des phases, suivi de l'interface) sans ou avec transfert thermique aux parois de la cavité. Des fluides de substitutions sont utilisés. Pour la partie expérimentale sans transfert thermique, de l'eau et de l'air sont utilisés à la place du comburant et du gaz inerte et pour la partie non isotherme du "x" (fluorocarbone) et un gaz "y" ont été choisis. Dans le premier cas, les expériences isothermes ont mis en évidence le comportement typique des grandeurs comme la pression dans la cavité et le débit de liquide entrant ainsi que la distribution des phases en sortie d'injection, tandis qu'une analyse des résultats a montré l'importance des différentes échelles de temps qui interviennent pendant le remplissage: temps d'ouverture de la vanne, temps de recouvrement des injecteurs par le liquide et les temps de remplissage et de vidange de la cavité tampon. Dans le deuxième cas, les parois sont chauffées au-dessus de la valeur d'ébullition du liquide, pour la gamme de pression envisagée dans le dôme. Le but est de quantifier les effets d'un possible changement de phase aux parois et d'évaluer leur importance sur l'écoulement. De plus, les conséquences dues à l'échauffement du gaz de balayage constituent une partie significative du programme expérimental. Le gaz est chauffé indépendamment des parois. Un modèle théorique traitant des différents régimes d'écoulements pendant le transitoire de remplissage permet de reproduire le comportement des pressions, débit liquide et fraction volumique de gaz dans la cavité. L'ensemble de ces mesures permettent de comprendre le transitoire de remplissage de la cavité d'injection dôme et l'analyse théorique qui accompagne ces expériences doit permettre l'extrapolation des résultats obtenus en laboratoire aux conditions réelles (fluides cryogéniques sous microgravité). Elle doit aussi fournir les conditions aux limites requises pour les approches numériques développées par ailleurs ainsi que les bases de données permettant de tester ces simulations. / In order to control the ignition of rocket motors during ballistic flight, the transient flow of comburant into a reservoir or buffer cavity (dôme) and then through a grid of injectors must be carefully characterised. The liquid oxygen is held under pressure upstream of a valve which opens into the dome. The valve opening is a control parameter. To avoid any possible flow of carburant from combustion chamber back into reservoir, the latter is swept with an inert gas, thus ensuring that the pressure in the reservoir remains higher than in the combustion chamber. This experimental study has the aim of characterising the spatio-temporal structure of two-phase flow into the dome following opening of principal liquid valve. Filling the dome and forcing the liquid through the injectors has an overall time scale of some hundred milliseconds. High resolution measurements of liquid and gas flow rates, pressure, phase distribution, interface velocity and temperatures are recorded for different values of the key parameters as well as visualisations. For the experimental program with heat transfer, the comburant was replaced with "x". Much work was carried out on the effects of heat transfer from either the gas or the walls or both to the liquid entering the dome once these were above the liquid boiling point. Previous studies in the LEGI using water and air, and without heat transfer brought to light the important variations in dome pressure and liquid flow rate during the transient, while analysis of results indicated the importance of a number of time scales : value opening time, time for the liquid to cover the injectors, time to fill the dome, time to empty it. For the heat transfer experiments, the walls are heated for the pressure range chosen. The sweep gas is heated too. The aim of these experiments is to seek evidence of a phase-change at the walls or during interaction with the gas and to evaluate its importance. To carry out these experiments, specific instrumentation was used. The whole of these mesures enable us to understand the transient filling of the injection cavity. Thus, theoretical analysis have to allow extrapolations of results obteined in laboratory to real cases (cryogenic liquid under microgravity). Then, we have to give a data base to developp and validate numerical simulation.

In gas-solid fluidized beds, the generation of electrostatic charges due to continuous contacts between fluidizing particles, and the particles and the fluidization vessel wall, is unavoidable. Industrial operations, such as the production of polyethylene, are susceptible to significant operational challenges caused by electrostatics including reactor wall fouling, a problem known as “sheeting”. The formation of particle sheets can require shutdown periods for clean-up which results in significant economic losses. To gain a better understanding of the underlying mechanisms of electrostatic charging in gas-solid fluidized beds, in an attempt to eliminate or minimize this problem, a pilot-scale pressurized gas-solid fluidization system was designed and built, housing an online electrostatic charge measurement technique consisting of two Faraday cups. The system permits the study of the degree of particle wall fouling at pressures and temperatures up to 2600 kPa and 100°C, respectively, and gas velocities up to 1 m/s (covering a range including turbulent flow regime). The system also allowed, for the first time, the measurement of the fluidizing particles’ mass, net charge and size distribution in various regions of the bed, especially those related to the wall coating under the industrially relevant operating conditions of high pressures and gas velocities. Experimental trials were carried out using polyethylene resin received from commercial reactors to investigate the influence of pressure and gas velocity on the bed hydrodynamics and in turn, the degree of bed electrification. Mechanisms for particle charging, migration and adherence to the column wall were proposed. The size distribution of the gas bubbles shifted towards smaller bubbles as the operating pressure was raised. Thus, higher pressures lead to greater mixing within the bulk of the bed and resulted in a higher degree of particle wall fouling. Moreover, the extent of wall fouling increased linearly with the increase in gas velocity and as the bed transitioned to turbulent regime, due to the increase in particle-wall contacts. Bipolar charging was observed especially within the wall coating with smaller particles being negatively charged. Overall, particle-wall contacts generated negatively charged particles resulting in a net negative charge in the bed, whereas particle-particle contacts generated positively and negatively charged particles resulting in no net charge when entrainment was negligible. The formation of the wall layer and its extent was influenced by the gravitational and drag forces balancing the image force and Coulomb forces (created by the net charge of the bed and the metallic column wall as the attraction between oppositely charged particles).

L’objectif a été d’étudier le procédé de cristallisation en émulsion d’un ingrédient cosmétique hydrophobe (EGDS) dispersé en phase aqueuse. La première étape consiste à émulsifier à chaud l’EGDS en présence d’un émulsifiant afin d’obtenir une émulsion stable huile dans eau. La cristallisation par refroidissement de l’émulsion est la seconde étape. Deux sondes optiques ont été mises au point pour permettre le suivi vidéo in situ en temps réel du procédé. A partir des séquences vidéo, la mesure de la distribution en taille des gouttes (DTG) a été faite automatiquement, celles des particules par un opérateur. La croissance des cristaux dans les gouttes a été observée au moyen d’une platine thermostatée sous microscope. Par son action sur le mécanisme de brisure la puissance spécifique d’agitation est le paramètre de premier ordre sur la DTG. La concentration en émulsifiant a un impact de second ordre sur la DTG (coalescence et stabilisation). L’emploi d’une hélice à pales minces au lieu d’une turbine Rushton est préférable (DTG étroite et polyvalence du mobile). La mesure in situ a permis de déterminer que le temps d’obtention d’une DTG stable est 3 à 4 fois supérieur aux données de la littérature. La cristallisation des gouttes est progressive, des plus grosses aux plus petites. Une goutte donne naissance à une particule dans les conditions expérimentales choisies. La fréquence de nucléation primaire a été calculée à partir de l’évolution temporelle des DTG, en supposant un mécanisme mononucléaire dans chaque goutte. Le mécanisme est hétérogène. La localisation de la nucléation primaire dans le volume de la goutte ou à sa surface interne n’a pas été possible / The aim was to study the crystallization in emulsion process of a hydrophobic cosmetic ingredient (EGDS). The emulsification of the molten EGDS in a continuous phase with the use of an emulsifier in order to obtain a stable droplet size distribution (DSD) is the first stage. The crystallization upon cooling is the second stage. Two optical probes were developed to allow the in situ video monitoring of each stage of the process in real time. From the video sequences recorded the measurement of the DSD was carried out automatically, and by an operator for the PSD. The growth of crystals in motionless droplets was observed under microscope thanks to a thermostated well. The specific power input of stirring was the main parameter acting on the reduction of DSD owing to its action on the droplet break-up mechanism. The surfactant concentration was a parameter of secondary relevance on the DSD (coalescence and stability). The use of a flat blade propeller instead of a Rushton turbine was preferable for the production of a narrower DSD. Finally the time required to reach equilibrium was found higher by a factor of 3-4 than predicted in the literature. It was shown that the droplets crystallized very progressively during cooling, from the biggest to the smallest droplets. With the experimental conditions, one drop gave birth to one particle. The primary nucleation rate was obtained from the analysis of the temporal evolution of the DSD with the hypothesis of a mononuclear mechanism in each droplet. The nature of the mechanism seems to be heterogeneous. Nevertheless its localization in the droplet volume or at the inner interfacial surface was not possible