The main aim of this thesis is to develop a library for integrating fully homomorphic encryption-based computations on a standard database. The fully homomorphic encryption is an encryption scheme that allows functions to be performed directly on encrypted data without the requirement of decrypting the data and yields the same results as if the functions were run on the plaintext. This implementation is a promising solution for preserving the privacy of the health care system, where millions of patients’ data are stored. The personal health care tools gather medical data and store it in a database. Upon importing this library into the database, the data that is being entered into the database is encrypted and the computations can be performed on the encrypted data without decrypting.

Dans ce travail, des méthodes d’analyses de spéciation exhaustive de lanthanides (Ln), en présence d'acides polyaminocarboxyliques (EDTA, DTPA) utilisés comme agents de desextraction dans les procédés de traitement de combustibles nucléaires usés, ont été développées par couplage simultané HILIC-ESIMS/ICPMS. Pour réduire les volumes d’effluents chromatographiques tout en maintenant des séparations efficaces et rapides, les performances de colonnes remplies de particules entièrement poreuses (FPP) et de particules superficiellement poreuses (SPP) ont été évaluées, aboutissant à la sélection de la technologie FPP de diamètre sub-2-µm. Selon la composition des échantillons, le couplage HILIC-ESIMS peut s'avérer suffisant pour des études de spéciation exhaustive, nécessitant l'évaluation du potentiel de l'ESIMS pour la mesure de composition isotopique d'éléments. Des méthodes de mesure de rapports isotopiques du natSm complexé à l'EDTA ont alors été développées avec deux types d’ESIMS, en introduisant directement l'échantillon. Une méthode de déconvolution a ensuite été développée pour déterminer les rapports isotopiques du natSm. L'approche a été validée avec un complexe de Sm enrichi en 147Sm et 149Sm. L'étape ultérieure a consisté à déterminer les rapports isotopiques du Sm avec le couplage simultané, en appliquant plusieurs méthodes de traitements de signaux transitoires. Des méthodes de quantification par étalonnage externe et par dilution isotopique spécifique ont été ensuite développées avec ce même complexe. Les développements réalisés avec le Sm pourront être étendus à d'autres lanthanides et aux actinides. / In this work, analysis methods of lanthanide (Ln) comprehensive speciation, in the presence of polyaminocarboxylic acids (EDTA, DTPA) used as back extraction agents in spent nuclear fuel treatment processes, were developed by simultaneous coupling HILIC-ESIMS/ICPMS. To reduce chromatographic effluent volumes while maintaining efficient and rapid separations, the performances of columns packed with fully porous particles (FPP) and superficially porous particles (SPP) were evaluated, resulting in the selection of the sub-2-µm FPP technology. Depending on the sample composition, HILIC-ESIMS coupling may be sufficient for comprehensive speciation studies, requiring assessment of the ESIMS potential for isotopic composition measurement of elements. The isotopic ratio measurement methods of natSm complexed with EDTA were then developed with two types of ESIMS, directly introducing the sample. A deconvolution method was then developed to determine the natSm isotope ratios. The approach was validated with Sm complex enriched in 147Sm and 149Sm. The next step was to determine the Sm isotopic ratios with the simultaneous coupling, by applying several methods of transient signal processing. Quantification methods by external calibration and specific isotopic dilution were then developed with this same complex. The developments carried out with Sm may be extended to other lanthanides and actinides.

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The heat transfer and friction augmentation in the fully developed portion of a 2:1 aspect ratio rectangular channel with orthogonal ribs at channel Reynolds numbers of 20,000, 30,000, and 40,000 is studied both experimentally and computationally. Ribs are applied to the two opposite wide walls. The rib aspect ratio is varied systematically at 1, 3, and 5, with a constant rib height and constant rib pitch (rib-pitch-to-rib-height ratio of 10). The purpose of the study is to extend the knowledge of the performance of rectangular channels with ribs to include high aspect ratio ribs. The experimental investigation is performed using transient Thermochromic Liquid Crystals technique to measure the distribution of the local Nusselt numbers on the ribbed walls. Overall channel pressure drop and friction factor augmentation is also obtained with the experimental setup. A numerical simulation is also performed by solving the 3-D Reynolds-averaged Navier-Stokes equations using the realizable-k-Greek lowercase letter episilon] turbulence model for closure. Flow visualization is obtained from the computational results as well as numerical predictions of local distributions of Nusselt numbers and overal channel pressure drop. Results indicate that with increasing rib width, the heat transfer augmentation of the ribbed walls decreases with a corresponding reduction in channel pressure drop.

This paper describes the design of a one dimensionalleaky-wave antenna, with an operating frequency at 30 GHz.The antenna consists a waveguide with one of the wallsreplaced by a semi-open row of pins, allowing power to leakout. The waveguide width and the height of the pins are taperedalong the waveguide length, in order to control the antenna’sradiation parameters.The antenna has been modeled and tested, using CST MicrowaveStudio and MathWorks Matlab. The final antenna designoperates at 30 GHz with an efficiency of 90%, side lobe levels of-26.3dB and a beamwidth 6.4°. For other frequencies in the Kaband the angle of maximum radiation varies, giving the antennascanning capabilities in one dimension. / Detta dokument beskriver utformningen aven endimensionell läckvågsantenn med en centerfrekvens på30 GHz.Antennen består av en vågledare där en av väggarna ersattsmed tappar som gör att effekt kan stråla ut. Vågledarens breddoch tapparnas höjd ändras längs vågledarens längd för attkontrollera antennens strålningsparametrar.Antennen har modellerats och testats med CST MicrowaveStudio och MathWorks Matlab. Den slutgiltiga antenndesignenfungerar vid 30 GHz med en effektivitet på 90%, sidlobsnivåerpå -26.3dB och en strålbredd på 6.4°. För andra frekvenser inomKa-bandet varierar vinkeln för maximal strålning, vilket tillåterantennen att scanna i en dimension. / Kandidatexjobb i elektroteknik 2021, KTH, Stockholm

This dissertation demonstrates the first of its kind distributed magnetic field sensor based on a fiber optic distributed acoustic sensing (DAS) scheme. Ferromagnetic nickel and Metglas® were dispersed internally within a fiber optic preform and then drawn on an in-house fiber optic draw tower to lengths in the kilometers. Due to the close proximity of the ferromagnetic metals and fiber optic core, the magnetostrictive strain response of the ferromagnetic materials when exposed to a magnetic field would perturbate within the fiber cladding and transfer that strain, internally, to the fiber optic core. Strain resulting from the magnetostrictive effect allows the DAS based sensor to accurately translate strain into readable magnetic field data. Due to the high sensitivity seen in this sensor design, multiparameter sources, acoustic and magnetic fields, were tested and validated and a three dimensional magnetic-field vector sensor was proposed. Numerical analysis of the novel sensor design was first implemented using COMSOL Multiphysics, where inputs such as magnetostrictive element shape, size, distance, and number were first investigated. Upon optimizing system constraints, the sensor design was further modified such that single mode operation was consistent across multiple fiber draws while retaining high strain transfer from the ferromagnetic elements to the fiber optic core. Ferromagnetic material selection was evaluated as a function of the saturation magnetostriction constants and a total of 4 modules were used to fully characterize the complex physics involved in this sensor design. All fabrication and testing were performed in-house using a full scale 3-story fiber draw tower and custom environmental testing stations to imitate naturally occurring events such as magnetic or acoustic point sources. A unique stacking method was used to embed ferromagnetic nickel and Metglas® into a fiber optic preform which when combined with a custom fiber draw process resulted in consistent multi-material fibers drawn to lengths of 1-km. In-house testing facilities included different types of electromagnetic generators, in addition to a soil test bed, and an outdoor test bed which allowed 100 meters of fiber to be tested simultaneously. All tested sensors demonstrated high strain transfer capabilities on the order of 0.01-10 μϵ depending on the materials used, ferromagnetic rod number, and core to metal spacing. Due to the sensitivity of the system the difference between AC and DC was distinct, and directional magnetostriction was studied. Transverse and longitudinal magnetic wave propagation was controlled through a solenoid and rectangular Helmholtz coil, both built in-house. A three-dimensional magnetic field vector sensor was proposed due to the success of the magnetic field sensor, and a design was proposed and initially tested to validate direction as a function of field strength and distance. To summarize, this dissertation explores the first fully distributed magnetic field sensor using DAS based techniques and one of the first multi-material fiber draw processes which can produce consistent single mode fiber up to 1-km. Due to extensive FEA modeling, multiple iterations of the magnetic sensor were fully characterized and an equation describing the relationship between sensor design and strain transfer has been created and validated experimentally. Multi-parameter tests including acoustic and magnetic fields were implemented and an algorithm was developed to separate the mixed signals. Finally, a test was performed to demonstrate the feasibility of sensing magnetic fields directionally. Cumulative results demonstrate a high-quality sensor alternative to current designs which may surpass other magnetic sensors due to innate multi-parameter capabilities, in addition to the inexpensive production cost and extremely long operating lengths. / Doctor of Philosophy / This dissertation demonstrates the first of its kind distributed magnetic field sensor based on a fiber optic distributed acoustic sensing (DAS) scheme. Ferromagnetic nickel and Metglas® were dispersed internally within a fiber optic preform and then drawn on an in-house fiber optic draw tower to lengths in the kilometers. Due to the close proximity of the ferromagnetic metals and fiber optic core, the magnetostrictive strain response of the ferromagnetic materials when exposed to a magnetic field would perturbate within the fiber cladding and transfer that strain, internally, to the fiber optic core. Strain resulting from the magnetostrictive effect allows the DAS based sensor to accurately translate strain into readable magnetic field data. Due to the high sensitivity seen in this sensor design, multiparameter sources, acoustic and magnetic fields, were tested and validated and a three dimensional magnetic-field vector sensor was proposed. Numerical evaluation of the sensing structure was perused before experimental testing using COMSOL Multiphysics. Experimental and numerical evaluations were compared and showed a high degree of certainty which allowed expedited design modifications. Sensor characterization included scanning electron microscopy, and electron diffraction spectroscopy, which provided insight into material composition and fiber polishing quality. Due to the high-quality results attained in the combined acoustic and magnetic field tests, a final design was proposed to gather magnetic field data as a vector, showing both magnitude and direction. The 3D magnetic field vector sensor was partially validated based on a test which compared intensity with distance and a design and methodology was proposed to fully test and characterize this design. To summarize, a novel magnetic field sensor, capable of multi-parameter sensing, was proposed and tested experimentally and numerically resulting in a robust and highly sensitive design. The work presented here provides some of the first insights into multi-material fiber fabrication, an equation which provides an estimated relationship between magnetostrictive strain transfer onto a fiber optic core and the perceived DAS based sensor results, as well as a first of its kind multi-parameter distributed acoustic and magnetic field sensor.

In this dissertation, a fully scalable video coding system is proposed. This system achieves full temporal, resolution, and fidelity scalability by combining mesh-based motion-compensated temporal filtering, multihypothesis motion compensation, and an embedded 3D wavelet-coefficient coder. The first major contribution of this work is the introduction of the redundant-wavelet multihypothesis paradigm into motion-compensated temporal filtering, which is achieved by deploying temporal filtering in the domain of a spatially redundant wavelet transform. A regular triangle mesh is used to track motion between frames, and an affine transform between mesh triangles implements motion compensation within a lifting-based temporal transform. Experimental results reveal that the incorporation of redundant-wavelet multihypothesis into mesh-based motion-compensated temporal filtering significantly improves the rate-distortion performance of the scalable coder. The second major contribution is the introduction of a sliding-window implementation of motion-compensated temporal filtering such that video sequences of arbitrarily length may be temporally filtered using a finite-length frame buffer without suffering from severe degradation at buffer boundaries. Finally, as a third major contribution, a novel 3D coder is designed for the coding of the 3D volume of coefficients resulting from the redundant-wavelet based temporal filtering. This coder employs an explicit estimate of the probability of coefficient significance to drive a nonadaptive arithmetic coder, resulting in a simple software implementation. Additionally, the coder offers the possibility of a high degree of vectorization particularly well suited to the data-parallel capabilities of modern general-purpose processors or customized hardware. Results show that the proposed coder yields nearly the same rate-distortion performance as a more complicated coefficient coder considered to be state of the art.

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