The thesis deals with integral and distributed optical fiber sensors of electric current. In the area of integral sensors the analysis is performed by Jones matrix calculus and the simultaneous influence of induced circular and undesired linear birefringence using an ortho-conjugation retroreflector. Furthermore, the proposed conjugation loop variant using half-wave phase retarders is analyzed. The theoretical conclusions are confirmed by simulation and experimental measurement. In the field of distributed fiber optic sensors, analysis and simulation for the detection of plasma currents in thermonuclear fusion reactors, based on the POTDR technique, is performed. An improvement procedure is proposed for circular-shaped vacuum vessel reactors. Plasma current detection procedure in divertor-type reactors have been newly designed and simulated to investigate the effect of the OTDR detector noise on plasma current detection accuracy.

Plasma pretreatments are environmentally benign and energy efficient processes for modifying the surface chemistry of materials. In an effort to improve the strength of the titanium alloy/FM-5 polyimide adhesive joint for aerospace applications, oxygen plasma pretreatments and novel thin plasma polymerized (PP) films were investigated as adhesion promoters. Plasma treatments were carried out using custom-built, low pressure, radio frequency, inductively coupled plasma reactors. Ti-6Al-4V coupons were plasma treated and used to prepare miniature single lap shear (SLS) joints. The effects of plasma pretreatments on surface chemistry were studied using x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), Fourier transform infrared analysis (FTIR), and contact angle measurements. Relationships between composition, mechanical properties, and adhesion of PP films on Ti-6Al-4V and silicon wafers were investigated. The nanomechanical properties (modulus, hardness and adhesion) were studied using atomic force microscopy (AFM) nanoindentation and nanoscratch testing. A design of experiments (DOE) three factorial model was used to optimize the parameters for oxygen plasma treatments. Oxygen plasma pretreatments enhanced joint strength by cleaning the titanium surface and creating an extended oxide layer. Nanoindentation of oxygen plasma treated substrates showed no change in the surface mechanical properties due to the oxygen plasma treatment. This suggested that the improved SLS strength of the oxygen plasma pretreated substrates was due to the cleaning of the substrate and the removal of carbonaceous contaminants, rather than any changes in the morphology of the oxide layer. PP acetylene films were predominantly carbon, with oxygen as the other main constituent (incorporated mostly as C-O and C=O). For all SLS specimens tested, the adhesion between PP acetylene and FM-5 adhesive was adequate. However, the strength of SLS joints was limited by the adhesion of the PP acetylene to the Ti-6Al-4V substrate. The effects of a large number of plasma parameters, such as substrate pretreatment, carrier gas, input power, flow rate and film thickness were investigated. All samples failed at the PP film/Ti-6Al-4V interface or within the PP acetylene film, and thicker PP films yielded lower SLS strengths. PP films deposited at lower power exhibited higher hardness and reduced modulus than films deposited at higher power. Overall, thinner films exhibited higher hardness and reduced Young's modulus than thicker films. PP films of higher hardness yielded higher critical loads at debond (thickness normalized) during the nanoscratch test. Thin films were developed via the vapor plasma polymerization of titanium(IV) isobutoxide (TiiB). XPS results suggested that titanium was incorporated into the film as TiO2 clusters dispersed in an organic matrix. No evidence for Ti-C was obtained from the XPS spectra. PP films of TiiB were much more compliant than PP acetylene films. This behavior was attributed to decreased fragmentation and lower crosslinking that occurred during PP TiiB film deposition. These PP films did not exhibit sol-gel-like qualities, and because of the way titanium was incorporated into the films, a more appropriate name for these films might be "titanium dioxide-doped plasma polymerized films." / Ph. D.

No description available.

In recent years, digital twins (DT) have gained traction in enhancing operation and maintenance procedures across various industrial sectors, such as manufacturing, energy, and aerospace. Yet their utilization remains more limited in the built environment. The aim of this paper is to investigate the current conceptualizations of DTs within the context of the Swedish built environment, shedding light on the maturity of DTs for built assets and the key value drivers influencing their adoption. The study reveals that DTs for built assets are in early developmental stages, lacking the maturity required to encompass the full spectrum of attributes inherent in a conventional DT. Despite stakeholders labeling these initiatives as DTs, our findings indicate a closer alignment with the concept of BIM-based digital models. This observation resonates with existing literature, highlighting the absence of a universally accepted definition for DTs. Within the Operations and Maintenance (O&M) phase, we have identified the following four primary value drivers shaping the adoption of BIM-based DTs: 1) commercial transparency and trusted transactions, 2) efficiency and cost reduction in routine operations, 3) operational continuity, and 4) added services. These findings contribute to the ongoing discourse surrounding the convergence of BIM and DTs, offering insights into the practical implications and value propositions that drive the integration of these technologies within the built environment. / Under de senaste åren har användningen av digitala tvillingar (DT:ar) blivit allt vanligare för drift- och underhållsförfaranden inom olika industrisektorer, såsom tillverkning, energi och flyg- och rymdindustrin. Användningen är dock fortfarande begränsad inom bygg- och fastighetsbranschen. Syftet med denna studie är att undersöka de nuvarande konceptualiseringarna av DT:ar inom ramen för den svenska fastighetsbranschen, belysa mognaden hos tekniken och undersöka de viktigaste värdedrivande faktorerna som påverkar utvecklingen och användningen i drift- och underhåll av fastigheter. Studien visar att användningen av DT:ar i fastighetsbranschen befinner sig i ett tidigt utvecklingsstadie och att begreppet inom industrin inte helt överensstämmer med visionen kring konceptet. Resultaten stämmer överens med befintlig litteratur, som belyser avsaknaden av en allmänt accepterad definition för DT:ar. I drift- och underhållsfasen har vi också identifierat följande fyra primära värdedrivande faktorer för användingen av BIM-baserade DT:ar: 1) kommersiell transparens och pålitliga transaktioner, 2) kostnadsbesparingar i rutinmässigt drift- och underhållsarbete, 3) kontinuerligt driftsarbete, samt 4) tilläggstjänster. Resultaten från denna studie bidrar till den pågående diskussionen om koncepten BIM och DT, och ger ytterligare insikt i de praktiska värdeskapande processerna och belyser användningsområden av DT:ar i fastighetsbranschen.

The thesis focuses on the issue of signal processing. Using practical examples, it tries to show the use of individual signal processing operations from a practical point of view. For each of the selected signal processing operations, an application is created in MATLAB, including a graphical interface for easier operation. The division of the thesis is such that each chapter is first analyzed from a theoretical point of view, then it is shown using a practical demonstration of what the operation is used in practice. Individual applications are described here, mainly in terms of how they are handled and their possible results. The results of the practical part are presented in the attachment of the thesis.

La spectroscopie électronique basée sur l'effet tunnel donne accès à la densité d'états des électrons (DoS) dans les matériaux conducteurs, et renseigne ainsi en détail sur leurs propriétés électroniques. <br />Au cours de cette thèse, nous avons développé un microscope permettant d'effectuer la spectroscopie tunnel résolue spatialement (10 nm) de nanocircuits individuels, avec une résolution en énergie inégalée (10 µeV). Cet appareil combine les fonctions de Microscopie par Force Atomique (mode AFM) et de spectroscopie Tunnel locale (mode STM), et fonctionne à 30 mK. Dans le mode AFM, la topographie de l'échantillon est imagée grâce à un diapason en quartz piézoélectrique, ce qui permet de repérer les circuits. La spectroscopie tunnel peut ensuite être faite sur les zones conductrices. <br />Avec ce microscope, nous avons mesuré la DoS locale dans une structure hybride Supraconducteur-métal Normal-Supraconducteur (S-N-S). Dans un tel circuit, les propriétés électroniques de N et de S sont modifiées par l'effet de proximité supraconducteur. Notamment, pour des fils N courts, nous avons pu observer -comme prédit- la présence d'un gap dans sa DoS, indépendant de la position dans la structure : le “minigap”. De plus, en modulant la phase supraconductrice entre les deux S, nous avons mesuré la modification de ce gap, et sa disparition lorsque la différence de phase vaut π. <br />Nos résultats expérimentaux pour la DoS, ainsi que ses dépendances en phase, en position, et en longueur de N sont en accord quantitatif avec les prédictions de la théorie quasiclassique de la supraconductivité. Certaines de ces prédictions sont observées pour la première fois.

La Décomposition Modale Empirique (EMD) est un outil de traitement de signal piloté par les données et dédié aux signaux non-stationnaires issus ou non de systèmes linéaires. L'idée de base de l'EMD est l'interpolation des extrema par des splines pour extraire de composantes oscillantes appelées modes empiriques intrinsèques (IMFs) et un résidu. Dans cette thèse, un nouvel algorithme de l'EMD est introduit où au lieu d'une interpolation rigide, un lissage est utilisé pour la construction des enveloppes supérieures et inférieures du signal à décomposer. Ce nouvel algorithme est plus robuste au bruit que l'EMD conventionnelle et réduit le nombre d'IMFs "artificielles" (sur-décomposition). En combinant le nouvel algorithme et la méthode de séparation d'énergie (ESA) basée sur l'Opérateur d'Energie de Teager-Kaiser (OETK), un nouveau schéma de démodulation des signaux AM-FM multi-composante appelé EMD-ESA est introduit. Différentes versions de l'EMD-ESA sont analysées en terme de performance. Pour l'analyse Temps-Fréquence (TF), une nouvelle formulation de la carte TF de l'EMD-ESA appelée Transformation de Teager-Huang (THT) est présentée. Cette nouvelle Représentation TF (RTF) ne présentant pas de termes d'interférences est comparée aux RTF classiques telles que le spectrogramme, le scalogramme, la distribution de Wigner-Ville Distribution (WVD), la Pseudo-WVD et la réallocation de la Pseudo-WVD. En combinant la nouvelle formulation de la THT et la transformée de Hough, une nouvelle méthode de détection des signaux multi-composante à modulation linéaire de fréquence dans le plan TF est présentée. Cette méthode de détection est appelée transformation de Teager-Huang-Hough (THHT). Les résultats de la THHT sont comparés à ceux de la transformée WVD-Hough. Finalement, l'analyse TF par THT et par des RTF classiques (WVD, spectrogramme, etc.) de signaux réels de rétrodiffusion par des coques cylindriques de dimensions et de caractéristiques physiques différentes est présentée. Les résultats obtenus montrent l'apport de la THT comme un outil TF.

Gyroscopes are inertial sensors that measure the rate or angle of rotation. One of the most promising technologies for reaching a high-performance MEMS gyroscope has been development of the micro-hemispherical shell resonator. (μHSR) This thesis presents the electronic control and read-out interface that has been developed to turn the μHSR into a fully functional micro-hemispherical resonating gyroscope (μHRG) capable of measuring the rate of rotation. First, the μHSR was characterized, which both enabled the design of the interface and led to new insights into the linearity and feed-through characteristics of the μHSR. Then a detailed analysis of the rate mode interface including calculations and simulations was performed. This interface was then implemented on custom printed circuit boards for both the analog front-end and analog back-end, along with a custom on-board vacuum chamber and chassis to house the μHSR and interface electronics. Finally the performance of the rate mode gyroscope interface was characterized, showing a linear scale factor of 8.57 mv/deg/s, an angle random walk (ARW) of 34 deg/sqrt(hr) and a bias instability of 330 deg/hr.

<p>In this thesis, we present novel computational methods and frameworks to address the challenges associated with the determination of free energy profiles for condensed-phase chemical reactions using combined quantum mechanical and molecular mechanical (QM/MM) approaches. We focus on overcoming issues related to force matching, molecular polarizability, and convergence of free energy profiles. First, we introduce a method called Reaction Path-Force Matching in Collective Variables (RP-FM-CV) that efficiently carries out ab initio QM/MM free energy simulations through mean force fitting. This method provides accurate and robust simulations of solution-phase chemical reactions by significantly reducing deviations on the collective variables forces, thereby bringing simulated free energy profiles closer to experimental and benchmark AI/MM results. Second, we explore the role of pairwise repulsive correcting potentials in generating converged free energy profiles for chemical reactions using QM/MM simulations. We develop a free energy correcting model that sheds light on the behavior of repulsive pairwise potentials with large force deviations in collective variables. Our findings contribute to a deeper understanding of force matching models, paving the way for more accurate predictions of free energy profiles in chemical reactions. Next, we address the underpolarization problem in semiempirical (SE) molecular orbital methods by introducing a hybrid framework called doubly polarized QM/MM (dp-QM/MM). This framework improves the response property of SE/MM methods through high-level molecular polarizability fitting using machine learning (ML)-derived corrective polarizabilities, referred to as chaperone polarizabilities. We demonstrate the effectiveness of the dp-QM/MM method in simulating the Menshutkin reaction in water, showing that ML chaperones significantly reduce the error in solute molecular polarizability, bringing simulated free energy profiles closer to experimental results. In summary, this thesis presents a series of novel methods and frameworks that improve the accuracy and reliability of free energy profile estimations in condensed-phase chemical reactions using QM/MM simulations. By addressing the challenges of force matching, molecular polarizability, and convergence, these advancements have the potential to impact various fields, including computational chemistry, materials science, and drug design.</p>

Indiana University-Purdue University Indianapolis (IUPUI) / In this thesis, we present novel computational methods and frameworks to address the challenges associated with the determination of free energy profiles for condensed-phase chemical reactions using combined quantum mechanical and molecular mechanical (QM/MM) approaches. We focus on overcoming issues related to force matching, molecular polarizability, and convergence of free energy profiles. First, we introduce a method called Reaction Path-Force Matching in Collective Variables (RP-FM-CV) that efficiently carries out ab initio QM/MM free energy simulations through mean force fitting. This method provides accurate and robust simulations of solution-phase chemical reactions by significantly reducing deviations on the collective variables forces, thereby bringing simulated free energy profiles closer to experimental and benchmark AI/MM results. Second, we explore the role of pairwise repulsive correcting potentials in generating converged free energy profiles for chemical reactions using QM/MM simulations. We develop a free energy correcting model that sheds light on the behavior of repulsive pairwise potentials with large force deviations in collective variables. Our findings contribute to a deeper understanding of force matching models, paving the way for more accurate predictions of free energy profiles in chemical reactions. Next, we address the underpolarization problem in semiempirical (SE) molecular orbital methods by introducing a hybrid framework called doubly polarized QM/MM (dp-QM/MM). This framework improves the response property of SE/MM methods through high-level molecular polarizability fitting using machine learning (ML)-derived corrective polarizabilities, referred to as chaperone polarizabilities. We demonstrate the effectiveness of the dp-QM/MM method in simulating the Menshutkin reaction in water, showing that ML chaperones significantly reduce the error in solute molecular polarizability, bringing simulated free energy profiles closer to experimental results. In summary, this thesis presents a series of novel methods and frameworks that improve the accuracy and reliability of free energy profile estimations in condensed-phase chemical reactions using QM/MM simulations. By addressing the challenges of force matching, molecular polarizability, and convergence, these advancements have the potential to impact various fields, including computational chemistry, materials science, and drug design.