This work is aimed at investigating out-of-plane displacement data on the top surface of a loaded composite laminate containing microcracking damage to explore the feasibility of using surface data to locate microcracks in laminates. In this study, finite element models are created for eleven different cross-ply IM7/977-2 laminates with ply numbers varying from four to ten. Here, each ply thickness is 0.127mm, which is the common laminate thickness commercially available for this material system. For each model a range of transverse loadings are applied and the surface displacement data are analyzed along the mid-plane perpendicular to the plane of the crack. The following outof- plane surface data parameters are obtained for each case: the minimal value above the crack tip, the peak value, and the far-field value. The difference in the peak and minimal values for a given loading is important in determining whether or not the optical technique is sensitive enough to resolve the data. The lateral distance to the peak values and the far-field values are also obtained. These distances are important in determining whether or not an optical system can spatially resolve the data. Results suggest that an optical technique such as digital holography could resolve, at a minimum, the data of [0/90/90/0], [0/90/90/90/90/0], and [0/0/90/90/90/90/0/0] laminates subjected to transverse loads of 1000 MPa.

The use of optical techniques in biomedical monitoring and diagnosis is becoming increasingly widespread, primarily because of the non-invasive nature of optically derived measurements. Physiological analysis is usually achieved by characterisation of the spectral or temporal properties of the interaction between light and the anatomy. Although some optical measurements require complex instrumentation and protocols, recent technological advances have resulted in robust and compact equipment that is now used routinely in a multitude of clinical contexts. Unfortunately, these measurements are inherently sensitive to corruption from dynamic physical conditions or external sources of light, inducing signal artefact. Artefact is the primary restriction in the applicability of many optical measurements, especially for ambulatory monitoring and tele-medicine. The most widely used optical measurement is photoplethysmography, a technique that registers dynamic changes in blood volume throughout the peripheral vasculature and can be used to screen for a number of venous disorders, as well as monitoring the cardio-vascular pulse wave. Although photoplethysmographic devices are now incorporated into many patient-monitoring systems, the prevalent application is a measurement known as pulse oximetry, which utilises spectral analysis of the peripheral blood to estimate the arterial haernoglobin oxygen saturation. Pulse oximetry is well established as an early warning for hypoxia and is now mandatory under anaesthesia in many countries. The problem of artefact is prominent in these continuous monitoring techniques, where it is often impossible to control the physical conditions during use. This thesis investigates the possibility of reducing artefact corruption of photoplethysmographic signals in real time, using an electronic processing methodology that is based upon inversion of a physical artefact model. The consequences of this non-linear artefact reduction technique for subsequent signal analysis are discussed, culminating in a modified formulation for pulse oximetry that not only has reduced sensitivity to artefact but also possesses increased generality. The design and construction of a practical electronic system is then used to explore both the implementation issues and the scope of this technique. The performance of artefact reduction obtained is then quantified under realistic experimental conditions, demonstrating that this methodology is successful in removing or reducing a large proportion of artefact encountered in clinically relevant situations. It is concluded that non-linear artefact reduction can be applied to any photoplethysmographic technology, reducing interpretation inaccuracies that would otherwise be induced by signal artefact. It is also speculated that this technology could enable the use of photoplethysmographic systems in applications that are currently precluded by the inherent severity of artefact.

Highly sensitive magneto-optical techniques have been used to investigate weak linear and nonlinear optical absorption mechanisms in p- and n-type InSb. As a result, new absorption processes involving both impurities and free carriers have been identified and studied in detail. For p-InSb, magneto-optical spectra has been obtained over a wide range of temperatures and photon energies. The spectra obtained at higher sample temperatures are seen to result from combined-resonance transitions of free holes between heavy-and light-hole Landau levels, while bound-hole transitions between ground heavy-hole-like and excited light-hole-like acceptor states are observed at lower temperatures. Analysis of the combined-resonance data along with extensive intra-conduction band and two-photon interband data using a modified Pidgeon and Brown 8X8 energy band model has allowed the determination of a single set of band parameters for InSb that quantitatively describes these different sets of data. In addition, a ground state binding energy of 8.1 meV for Cd acceptors and 42.5 meV for Au acceptors has been extracted from the analysis of the bound-hole spectra. For n-lnSb, photo-Hall techniques have been developed and used to study both resonant impurity and two-photon magneto-absorption (TPMA) processes in detail. As a result, LO-phonon-assisted impurity cyclotron resonance harmonic (LOICRH) transitions from the shallow Te donor level have been observed for the first time. In addition, transitions from deep levels are also observed in the photo-Hall signal obtained at sample temperatures greater than 20K. Both time-resolved and intensity-dependent measurements on impurity and TPMA processes are reported and the results compared directly with the predictions of rate equations describing the photoexcited carrier dynamics. These investigations have yielded important information about the optical properties of n-InSb; e.g. impurity and two-photon absorption coefficients, photo-excited carrier lifetimes, and recombination rates.

Supercritical CO2 (sCO2) has been proposed for many applications, such as power generation, air conditioning, and thermal management of electronic equipment. In proximity to critical conditions, the thermal and transport properties of the CO2 vary abruptly, promoting a significant heat transfer enhancement. Revealing the heat transfer processes associated with CO2 flows requires measuring fluid temperature, pressure, heat transfer coefficients, velocities, etc. However, fundamental knowledge about the heat transfer processes at near-critical conditions is not fully understood. Advanced optical techniques should be considered to measure these properties of sCO2. These techniques include Schlieren Imaging to capture the density gradient, LIF ( Laser Induced Fluorescence) for temperature measurement, and PIV ( Particle Image Velocimetry) for measurement of the velocity flow field. Different experimental setups have been built to apply the advanced optical technique. The Schlieren imaging has been used to capture the density gradient of the methane injection into the chamber filled with CO2 at supercritical thermodynamic conditions. The density gradient in the flow helped to define the jet cone angle. The micro-channel setup was implemented through which a mixture of CO2 and Rh6G dye was flowed. The dye particles will act as a thermal probe and measure the temperature of the CO2 flow at near supercritical conditions by applying the LIF ( Laser Induced Fluorescence). Initially, the feasibility of the backlight micro-PIV technique was demonstrated by performing experiments with the methanol and non-fluorescent tracers. Then the author applied the the same technique for the first time to measure the velocity of the liquid CO2 flow through a T-channel. Furthermore, the bottom of the channel was painted with fluorescence color to excite, which helps to observe the shadows of the non-fluorescent particles used to measure the velocity of the flow.

Made available in DSpace on 2015-05-08T14:59:34Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1933952 bytes, checksum: 631f48c47124341fd9bdddc854ca8722 (MD5) Previous issue date: 2011-12-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work presents a non contact measurement techniques study on the manufacturing process and the design and development of a non contact measurement system for inspection of diameters of parts during the machining process on the lathe. Amongst the techniques are showed technologies which are based on physical principles of optical, pneumatic, electric or ultrasound. The system developed to this work uses an optical sensor to take the scan on the part and an incremental rotary encoder to monitor the displacement of that one. At the end of the inspection operation, the diameter of the part is indicated on a display and transmitted to the computer to standard RS-232 serial communication. Test with the developed measurement system were realized such in the laboratory like a machine shop environment in order to determine the metrological characteristics of the prototype in different conditions of operation. Based on experiments with non contact measuring system, it presented good repeatability, reproducibility and long term stability. / Este trabalho apresenta um estudo das técnicas de medição sem contato em processo de fabricação e o projeto e desenvolvimento de um sistema de medição sem contato, para inspeção de diâmetros de peças durante o processo de usinagem em um torno mecânico. Dentre as técnicas são apresentadas tecnologias que se baseiam nos princípios físicos da óptica, pneumática, elétrica ou ultra-som. O sistema desenvolvido para esta dissertação utiliza um sensor óptico de presença para realizar a varredura na peça e um encoder rotativo incremental para monitorar o deslocamento do sensor óptico. Ao final da operação de inspeção, o diâmetro do mensurando é indicado em um display e transmitido ao computador pelo padrão de comunicação serial RS-232. Testes com o sistema de medição desenvolvido foram realizados tanto em laboratório quanto no ambiente de uma oficina mecânica, a fim de determinar as características metrológicas do protótipo em condições distintas de operação. Com base nos experimentos realizados com o sistema de medição sem contato, o mesmo apresentou boa repetitividade, reprodutibilidade e estabilidade a longo prazo.

This thesis describes the unstable dynamics of a gas jet impinging on a falling liquid film. This flow configuration is encountered in the jet wiping process, used in continuous coating applications such as the hot-dip galvanizing to control the thickness of a liquid coat on a moving substrate. The interaction between these flows generates a non-uniform coating layer, of great concern for the quality of industrial products, and results from a complex coupling between the interface instabilities of the liquid film and the confinement-driven instabilities of the impinging jet.Combining experimental and numerical methods, this thesis studied the dynamics of these flows on three simplified flow configurations, designed to isolate the key features of their respective instabilities and to provide complementary information on their mutual interaction. These configurations include the gas jet impingement on a falling liquid film perturbed with controlled flow rate pulsation, the gas jet impingement on a solid interface reproducing stable and unstable liquid film interfaces and a laboratory scaled model of the jet wiping process. Each of these configurations was reproduced on dedicated experimental set-up, instrumented for non-intrusive measurement techniques such as High-Speed Flow Visualization (HSFV) and Time-resolved Particle Image Velocimetry (TR-PIV) for the gas jet flow analysis, Laser Induced Fluorescence (LIF) tracking of the liquid interface, and 3D Light Absorption (LAbs) measurement of the liquid film thickness. To optimize the performances of these measurement techniques, several advanced data processing routines were developed, including a novel image pre-processing method for background removal in PIV and a dynamic feature tracking for the automatic detection of the jet flow and the liquid film interface from HSFV, LIF, and PIV videos.To identify the flow structures driving the unstable response of the jet flow, a novel data-driven modal decomposition was developed. This decomposition, referred to as Multiscale Proper Orthogonal Decomposition (mPOD), was validated on synthetic, numerical and experimental test cases and allowed for better feature extraction than classical alternatives such as Proper Orthogonal Decomposition (POD) or Dynamic Mode Decomposition (DMD).The experimental work on these laboratory models was complemented with the analysis of several numerical simulations, including a classical 2D Unsteady Reynolds Averaged Navier Stokes (URANS) modeling of the gas jet impingement on a fixed interface, a 2D Variational Multiscale Simulation (VMS) with anisotropic mesh refinement of the gas jet impingement on a pulsing interface, and a 3D simulation of the jet wiping process combining Large Eddy Simulation (LES) on the gas side with Volume of Fluid (VOF) treatment of the liquid film flow. The experimental modal analysis on the dynamic response of the gas jet and the characterization of the pressure-velocity coupling in the numerical investigation allowed for a complete picture of the mechanism driving the jet oscillation and its possible impact on the liquid film.In parallel, several flow control strategies to prevent the jet oscillation were developed, tested numerically and experimentally in simplified conditions, and later implemented on the design of a new nozzle for the jet wiping process. This new nozzle was finally tested on a laboratory scale of the wiping process and its performances compared to single jet and multiple jet wiping configurations. In these three cases, the experimental work presents the modal analysis of the gas field using TR-PIV and mPOD, the liquid interface tracking via LIF, and the final coating thickness characterization via LAbs.The large spatiotemporally resolved experimental database allowed to give a detailed description of the jet wiping instability and to provide new insights on this fascinating fundamental and applied problem of fluid dynamics. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

No description available.

The work reported in this thesis has been carried out in the following two areas of Optical metrology: 1. Measurement and correction of prism angles 2. Measurement of refractive indices using a spectrograph. The prism angles are conventionally tested by mechanical bevel protractors, autocol-limators (angle dekkors), simple interference techniques and interferometers. All these methods have their own limitations either in accuracy or in terms of cost. Mechanical methods are usually employed to measure the angles of prisms. Interference techniques and interferometers are also used but they need optically polished components. For both mechanical and simple interference methods of testing, it is essential to fabricate more than a single component in number. The process of building interferometers or purchasing interferometers, angle dekkors and standard angle gauges is not cost effective for many research laboratories, and medium scale industries. To overcome these difficulties simple and inexpensive methods without sacrificing the accuracy in the bargain are suggested for the measurement of prism angles, based on the principles of reflection of light. The refractive indices of prism materials for invisible and weaker spectral lines are usually determined from spectrograms using dispersion formulae and numerical interpolation techniques. In these methods, the accuracy of the results depends on the accuracy of determining the constants of the dispersion formulae. A simple experimental technique, using a spectrograph, is devised for the measurement of refractive indices of solids and liquids both for visible and invisible spectral lines (wavelengths). The thesis has been divided into six chapters. The first chapter starts with the general introduction. The second chapter presents the literature review of the existing methods for angle and refractive index measurements. The third chapter describes the proposed new techniques for prism angle measurements. The fourth chapter presents the experimental results of angle measurements, and the discussion of the accuracy of the results. This chapter also gives the scope for further research. The fifth chapter describes a newly proposed technique for measuring refractive indices and the experimental results. This chapter also gives the scope for further research. The summary of the results, conclusions, and suggestions for further work are presented in chapter six.

<p>This thesis explores the ablation and texturing of synthetic single crystal diamond under ultrashort laser pulse irradiation in rough vacuum ambient conditions. Experiments were performed with a 1 kHz repetition rate titanium sapphire laser system producing pulses at 800 nm central wavelength and 150 fs pulse duration. First, the production of ordered periodic nanostructures (ripples) on the diamond surface was characterized and the periodicity of these structures was analyzed against irradiation parameters. Ripples were usually found to fall into one of two categories: one with a spatial period near the irradiation wavelength and one with a spatial period near λ/2n, where λ is the central laser wavelength in air and n is the refractive index of diamond at λ. The spatial periods were plotted against irradiation conditions including the peak fluence, number of incident pulses, and the angle of incidence. Unique outcomes arising out of complex irradiation conditions were also explored. Second, the ablation thresholds for single pulse up to 1000 pulse irradiation were determined using the <em>D</em>² method at both the fundamental central wavelength (800 nm) and the second harmonic (400 nm). The single 800 nm pulse ablation threshold for synthetic single crystal diamond was determined to be 2.3 J/cm² with an incubation coefficient of 0.54. The single 400 nm pulse ablation threshold was determined to be 1.5 J/cm² with an incubation coefficient of 0.73.</p> / Master of Applied Science (MASc)

[ES] En los últimos años, la investigación en motores se ha centrado principalmente en la reducción de emisiones contaminantes y en el aumento de la eficiencia. Muchos de los esfuerzos de investigación actuales en este campo están dirigidos a mejorar y desarrollar nuevas estrategias activas para la reducción de emisiones, en particular centradas en los nuevos conceptos de combustión y en la obtención de un mejor control sobre ella. Su desarrollo requiere la aplicación de nuevas herramientas experimentales y teóricas. Estas herramientas deberían permitir tanto la aplicación de nuevas estrategias activas de control de contaminantes como ampliar el conocimiento básico de los fundamentos de los procesos involucrados. En este contexto es donde se encuadra el objetivo de esta Tesis: el desarrollo y optimización de un nuevo sistema de encendido no intrusivo y modulable, que permitirá el control sobre el tiempo y la ubicación del punto de encendido. Dicho sistema se aplicará para el encendido de chorros Diesel de inyección directa. En particular, se pretende evidenciar cómo las condiciones locales al encendido pueden afectar al desarrollo de la combustión posterior. Para lograr este objetivo, el trabajo de investigación se ha dividido en dos bloques principales. El primero se centra en el desarrollo y la optimización del sistema de encendido. Aprovechando las posibilidades que ofrece el proceso de inducción de plasma con láser y, una vez seleccionado el mejor método de inducción para su aplicación en un entorno especifico como el de un motor, se ha llevado a cabo un proceso de optimización y validación del sistema. Tal proceso resulta de importancia básica en el desarrollo de esta investigación, ya que la aplicación de un sistema de encendido totalmente fiable resulta ser fundamental, tanto en términos de su posible aplicación para control de combustión como en términos de las posibilidades de estudios que pueda ofrecer. Al principio, a partir de un extenso estudio de la literatura sobre el proceso de inducción de plasma con láser, se han obtenido los parámetros fundamentales a tener en cuenta para la aplicación del sistema al encendido de chorros de combustible de inyección directa. A partir de estos parámetros, se ha diseñado un primer sistema de encendido. Luego su fiabilidad en la inducción de plasma ha sido estudiada experimentalmente en condiciones ambientales y de motor, aplicando una metodología de optimización desarrollada en este mismo trabajo experimental. Como resultado principal de este primer bloque de trabajo, se ha podido obtener un sistema de encendido por plasma inducido con láser completamente optimizado y fiable, así como un método novedoso para su validación y optimización. El segundo bloque de trabajo corresponde a la aplicación del sistema al encendido de un chorro Diesel de inyección directa en condiciones reales del motor. El objetivo de este bloque era lograr dos hitos principales: la determinación de las capacidades y los límites del sistema en su aplicación, y el desarrollo de un primer estudio experimental sobre la influencia de las condiciones locales de la zona de encendido sobre una combustión Diesel. Para lograrlo, primero se ha validado la capacidad de encendido del sistema bajo un conjunto adecuado de condiciones termodinámicas, previamente seleccionadas para mantener la máxima efectividad. Los resultados de este estudio, en comparación con los típicos parámetros de autoencendido en las mismas condiciones, han permitido demostrar la capacidad de encendido del sistema. Posteriormente, se ha llevado a cabo una variación paramétrica de tiempos y posiciones en las que inducir el plasma, con el fin de determinar el efecto de las condiciones locales sobre el desarrollo de la combustión Diesel. En este caso, al comparar los resultados obtenidos con los parámetros estándar de autoencendido, se han podido obtener tendencias interesantes, que subra / [CA] En els últims anys, la investigació en motors s'ha centrat principalment en la reducció d'emissions contaminants i en l'augment de l'eficiència. Molts dels esforços d'investigació actuals en aquest camp estan dirigits a millorar i desenvolupar noves estratègies actives per a la reducció d'emissions, en particular centrades en els nous conceptes de combustió i en l'obtenció d'un millor control sobre ella. El seu desenvolupament requereix l'aplicació de noves eines experimentals i teòriques. Aquestes eines haurien de permetre tant el desenvolupament i aplicació de noves estratègies actives de control de contaminants com ampliar el coneixement bàsic dels fonaments dels principals processos involucrats. En aquest context és on s'enquadra l'objectiu principal d'aquesta Tesi: el desenvolupament i l'optimització d'un nou sistema d'encés no intrusiu i modulable, que permetrà el control sobre el temps i la ubicació del punt d'encés. Aquest sistema s'aplicarà per a l'encesa de dolls Diesel d'injecció directa. En particular, es pretén evidenciar com les condicions locals a l'encesa poden afectar el desenvolupament de la combustió posterior. Per a aconseguir aquest objectiu, el treball de recerca s'ha dividit en dos blocs principals. El primer se centra en el desenvolupament i l'optimització del sistema d'encesa. Aprofitant les possibilitats que ofereix el procés d'inducció de plasma amb làser i, una vegada seleccionat el millor mètode d'inducció per a la seua aplicació en un entorn especifique com el d'un motor, s'ha dut a terme un procés d'optimització i validació del sistema. Tal procés resulta d'importància bàsica en el desenvolupament d'aquesta investigació, ja que l'aplicació d'un sistema d'encesa totalment fiable resulta ser fonamental, tant en termes de la seua possible aplicació per a control de combustió com en termes de les possibilitats d'estudis que puga oferir. Al principi, a partir d'un extens estudi de la literatura sobre el procés d'inducció de plasma amb làser, s'han obtingut els paràmetres fonamentals a tindre en compte per a l'aplicació del sistema a l'encesa de dolls de combustible d'injecció directa. A partir d'aquests paràmetres, s'ha dissenyat un primer sistema d'encesa. Després la seua fiabilitat en la inducció de plasma ha sigut estudiada experimentalment en condicions ambientals i de motor, aplicant una metodologia d'optimització desenvolupada en aquest mateix treball experimental. Com a resultat principal d'aquest primer bloc de treball, s'ha pogut obtindre un sistema d'encés per plasma induït amb làser completament optimitzat i fiable, així com un mètode nou per a la seua validació i optimització. El segon bloc de treball correspon a l'aplicació del sistema a l'encesa d'un doll Dièsel d'injecció directa en condicions reals del motor. L'objectiu d'aquest bloc era aconseguir dues fites principals: la determinació de les capacitats i els límits del sistema en la seua aplicació a l'encesa de dolls d'injecció directa, i el desenvolupament d'un primer estudi experimental sobre la influència de les condicions locals de la zona d'encesa sobre el desenvolupament posterior d'una combustió Diesel. Per a aconseguir-ho, primer s'ha validat la capacitat d'encesa del sistema sota un conjunt adequat de condicions termodinàmiques, prèviament determinades per a mantindre la màxima efectivitat. Els resultats d'aquest estudi, en comparació amb els típics paràmetres d'autoencesa en les mateixes condicions, han permés demostrar la capacitat d'encesa del sistema. Posteriorment, s'ha dut a terme una variació paramètrica de temps i posicions en les quals induir el plasma per a forçar l'encesa, amb la finalitat de determinar l'efecte de les condicions locals sobre el desenvolupament de la combustió Diesel. En aquest cas, en comparar els resultats obtinguts amb els paràmetres estàndard d'autoencesa, s'han pogut obtindre tendències interessants, que subratl / [EN] In the recent years the engine research has been mainly focused on the pollutant emissions reduction and on increasing the efficiency. Many of the actual research efforts in the field of the Internal Combustion Engines are aimed to improve and develop new active strategies for emission reduction, particularly centered on new combustion concepts and a general improved combustion control. Their development requires the application of new experimental and theoretical tools, allowing both to be directly applied as an active pollutant control strategy and to permit to expand the basic knowledge of the governing processes' fundamentals. This is the concept where the main objective of this Thesis is framed: the development and optimization of a new, non-intrusive and modulable ignition system that will allow the control on the position and timing of the ignition spot. Such system will be applied to the ignition of direct injection diesel sprays in order to expand the knowledge of the ignition process, particularly considering how the local conditions at the ignition are affecting the subsequent combustion development. In order to accomplish the proposed objective, the research work has been divided in two main blocks. The first one is focused on the development and optimization of the ignition system. Taking advantage of the possibilities granted by the laser plasma induction process and, once selected the best induction method for its application in an internal combustion engine environment, a process of optimization of the ignition system has been carried out. Such optimization process results to be of basic importance for this research development. In fact, the application of fully reliable ignition system is fundamental both in terms of its possible direct application for combustion modulation purposes and in terms of the new study possibilities that is able to deliver. At first, from an extensive literature survey upon the plasma laser induction process, the fundamental parameters to focus on for the application of the system to the ignition of direct injection fuel sprays have been obtained. Starting from these parameters, a first ignition system has been designed, and then its reliability in the plasma induction has been experimentally tested under ambient and engine-like conditions, applying an original optimization methodology. As a main result of this first work block, a fully optimized and completely reliable laser induced plasma ignition system has been obtained, and an original system validation and optimization method has been developed. The second work block corresponds to the application of the ignition system to a direct injection diesel spray under real engine conditions. This block aimed to accomplish two main goals: the determination of the system capabilities and limits for the spray ignition application and the development of a first experimental study regarding the influence of the local conditions at the ignition location on the subsequent development of diesel combustion. In order to do so, first the system ignition capability has been tested on a diesel spray, under an adequate set of thermodynamic conditions determined to maintain the maximum possible system feasibility. The results of this study, compared with the standard combustion diagnostics parameters for the autoignition event at the same conditions, proved its ignition capabilities. Then a parametric variation of the local timing and position of the induced plasma generation region has been carried out, in order to determine the effect of the local condition on the combustion development. By comparing the obtained results with standard autoignition parameters at the same conditions, interesting trends have been obtained, that underline the system ability to control and modulate the combustion event / Pinotti, M. (2019). COMBUSTION CONTROL OF DIESEL SPRAYS BY MEANS OF LASER INDUCED PLASMA IGNITION [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/130205