Orientador: João Eduardo Gomes Filho / Resumo: Introdução: O objetivo deste estudo foi avaliar a eficácia de diferentes protocolos de Irrigação Ultrassônica Passiva (PUI) por meio de microscopia eletrônica de varredura (MEV). Métodos: Seis cavidades foram confeccionadas ao longo da seção vestibular de 20 canais radiculares de pré-molares inferiores humanos e preenchidas com detritos. 10 grupos foram criados de acordo com o protocolo final de irrigação: Grupo 1- controle positivo (sem detritos); Grupo 2- controle negativo (com detritos); Grupo 3 - irrigação convencional com hipoclorito de sódio a 2,5% (NaOCl); Grupo 4 - irrigação convencional com 17% de ácido etilenodiaminotetracético (EDTA) seguido de NaOCl; Grupo 5- PUI com 3 ciclos de 20 segundos (NaOCl-NaOCl-NaOCl); Grupo 6- PUI com 3 ciclos de 20 segundos (NaOCl-EDTA-NaOCl); Grupo 7- PUI com um ciclo de 60 segundos (NaOCl); Grupo 8 - PUI com ciclo de 180 segundos (NaOCl); Grupo 9 - PUI com 2 ciclos de 60 segundos (EDTA-NaOCl); Grupo 10 - PUI com 2 ciclos de 60 segundos (NaOCl-EDTA). Os espécimes foram observados em MEV para a análise da remoção dos detritos (scores 1 a 5) e exposição dos túbulos dentinários (score 1 ou 2) dentro das cavidades. O teste de Kruskal-Wallis foi realizado para a análise estatística, com significância de 5%. Resultados: Os grupos PUI apresentaram melhores resultados na limpeza de detritos do que os grupos de irrigação convencionais nas cavidades 1, 2 e 3. As cavidades 4, 5 e 6 foram limpas em todos os grupos experimentais. Em relação à expos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Abstract: Introduction: The aim of this study was to evaluate the effectiveness of different Passive Ultrasonic Irrigation (PUI) protocols by means of scanning electron microscopy. Methods: Six hemispherical cavities were made along the buccal section of 20 root canals of human lower premolars and filled with debris. 10 groups was created according to the final irrigation protocol: Group 1-positive control(no debris); Group 2-negative control(with debris); Group 3-conventional irrigation with 2.5% sodium hypochlorite (NaOCl); Group 4-conventional irrigation with 17% ethylenediamine tetracetic acid (EDTA) followed by NaOCl; Group 5-PUI with 3 cycles of 20 seconds (NaOCl-NaOCl-NaOCl); Group 6-PUI with 3 cycles of 20 seconds (NaOCl-EDTA-NaOCl); Group 7-PUI with a 60 seconds cycle (NaOCl); Group 8-PUI with a 180 seconds cycle (NaOCl); Group 9-PUI with 2 cycles of 60 seconds (EDTA-NaOCl); Group 10-PUI with 2 cycles of 60 seconds (NaOCl-EDTA).Scores were given for the analysis of debris removal in SEM, as well as for the exposure of dentinal tubules within the cavities. Kruskal-Wallis test was performed for statistical analysis.Results: The PUI groups presented better results in cleaning of debris than the conventional irrigation groups in cavities 1, 2 and 3. Cavities 4, 5 and 6 were well cleansed in all experimental groups. Regarding the exposure of the dentinal tubules, the PUI groups were able to achieve a better result than the conventional irrigation groups.Conclusions: Passi... (Complete abstract click electronic access below) / Mestre

Ces travaux de thèse portent sur l'étude expérimentale approfondie d'un composite à base polyamide 66/6 renforcé par des fibres de verres tissés suivant un motif sergé 2/2. L’objectif est de proposer des solutions de Contrôle Non Destructif (CND) basées sur les ultrasons afin de détecter différents niveaux d’endommagement induis. Pour cela, une étude approfondis des mécanismes d’endommagement apparaissant lors de sollicitations en traction suivant l’axe des fibres et hors axes est réalisé. Le cas d’impact induis par poids tombant est également étudiés. En effet, ces différents cas de sollicitions entraînent l’apparition de différent mécanismes d’endommagement. Ces derniers, ainsi que leur ordre d’apparition, sont caractérisés par Microscopie Electronique à Balayage (MEB) et tomographie à rayons X principalement. L’évaluation de la réduction du module élastique pré et post chargement ainsi que la fraction volumique de vide montrent une évolution de l’endommagement plus importante lors de chargement en traction hors axes des fibres que lors de chargement suivant l’axe. Lors des essais d’impact par poids tombant différents niveaux d’énergie sont considérés en restant proche du domaine des BVID en vue d’éprouver la sensibilité des méthodes de CND. Deux méthodes de CND par ultrasons étudiées durant ce projet peuvent être mises en avant. Premièrement, par mesure de la vitesse de propagation des ondes dans plusieurs directions du composites, le tenseur de rigidité est estimé dans tous ces cas de sollicitation mécanique pour différents niveaux d’endommagement. Des indicateurs d’endommagement basés sur ces mesures montrent une évolution de l’état d’endommagement similaire à celle discutée précédemment. Deuxièmement, une étude de la détection de l’endommagement par ondes guidées est menée. Aucun changement des modes transmit n’est visible lors de l’augmentation de l’état d’endommagement. L’évolution de l’énergie du signal transmis est alors proposée et validée comme indicateur d’endommagement efficace pour des chargements en traction mais pas pour l’impact. La mesure du décalage temporel à en revanche permis une localisation et une quantification de l’endommagement induit par impact. / The present study is focused on the experimental study of a polyamide 66/6 based composite reinforced by a 2/2 twill weave glass fabric. The aim is to propose Non Destructive Evaluation (NDE) methods based on ultrasound that can efficiently distinguish different damage state. In order to do so, an investigation of the damage mechanisms induced by different type of mechanical solicitations. Tension along and off the axis of the fibers was considered as well as the case of drop weight impact. Those solicitations were shown to induce different damage mechanisms. The latter were characterized by means of Scanning Electronic Microscopy (SEM) and X-Ray tomography mostly. The decreasing of the elastic modulus and the void volume fraction evolution were shown to be more significant for the samples loaded in tension off-axis. During the drop weight impact tests, the energies were considered in order to remain close to the Barely Visible Impact Damage (BVID) regime in order to experience the capability of the ultrasound based NDE methods. Two NDE methods investigated during this study deserve to be highlighted. Firstly, the stiffness tensor was estimated by means of phase velocities measurements in different propagation direction. Damage indicators based on results from this method were proposed. They were found to give results similar with the one from the evaluation of damage discussed earlier on. Secondly, a study of the damage detection using guided waves was performed. No mode conversion effect was observed from this investigation. Consequently, the signal energy was proposed as damage indicator and was found to be suitable to detect damage induced by tension but not by impact. The measure of time shift allowed obtaining a localization and evaluation of the damage induced by impact.

Orientador: Maria Jaqueline Mamprim / Coorientador: Carlos Roberto Teixeira / Banca: Raquel Sartor Marcelino / Banca: Alessandra Melchert / Resumo: O atendimento de cães com sobrepeso e obesos na rotina clínica de animais de companhia tem sido cada vez mais frequente. O objetivo do presente estudo foi avaliar as alterações hepáticas parenquimatosas e hemodinâmicas, por meio da ultrassonografia bidimensional e Doppler, em três grupos de cães com diferentes escores de condição corporal - G1 (peso ideal/controle), G2 (sobrepeso) e G3 (obesos) -, sem doenças hepáticas por outras causas de base. Houve correlação positiva entre o G3 e os seguintes fatores: aumento da ecogenicidade do parênquima hepático, aumento das dimensões hepáticas, hiperlipidemia, e morfologia anormal da onda da veia hepática (VH). Diferença significativa na velocidade média do fluxo portal (Vméd.VP) foi observada entre G1 (17,23 ± 3,7cm/s) e G3 (13,66 ± 2,56cm/s), no volume do fluxo portal (VFVP) entre G1 (32,69 ± 11,86mL/min/kg) e G2 (19,58 ± 7,68mL/min/kg) e entre G1 e G3 (15,22 ± 8mL/min/kg), no índice hepatorrenal entre G2 (1,1 ± 0,29) e G3 (1,28 ± 0,22), nos níveis séricos de fosfatase alcalina (FA) entre G1 e G3, de gama glutamiltransferase (GGT) entre G1 e G2 e de colesterol entre G1 e os demais grupos. Não houve diferença significativa no índice de congestão portal (ICP), no índice de resistividade da artéria hepática (IRAH), no diâmetro e área da veia porta e nos níveis séricos de alanina aminotransferase (ALT) e triglicérides, entre os grupos. Concluiu-se que a obesidade pode levar ao desenvolvimento de alterações parenquimatosas e hemodinâmicas no fígado de cães / Abstract: Veterinary care of overweight and obese dogs in small animal clinical sciences has become increasingly common. The aim of the present study was to investigate, using two dimensional and Doppler sonography, parenchymal and hemodynamic changes in three groups of dogs, according to body score condition (G1, ideal body weight/control; G2, overweight; G3, obese), without hepatic diseases due to other causes. A positive correlation was found between G3 and the characteristics described below: increased liver echogenicity, hepatomegaly, hiperlipidemia and abnormal hepatic vein Doppler waveform pattern. There was statistical difference in the mean portal blood flow velocity between G1 (17,23 ± 3,7cm/s) and G3 (13,66 ± 2,56cm/s), in the portal blood flow between G1 (32,69 ± 11,86mL/min/kg) and G2 (19,58 ± 7,68mL/min/kg) and between G1 and G3 (15,22 ± 8mL/min/kg), in the hepatorenal index between G2 (1,1 ± 0,29) and G3 (1,28 ± 0,22), in serum levels of alkaline phosphatase (ALP) between G1 and G3, in levels of gamma glutamyltranspeptidase (GGT) between G1 and G2 and in levels of cholesterol between G1 and the other groups. There was no statistical difference in the portal vein congestion index, hepatic artery resistance index, portal vein diameter and area and on serum levels of alanine aminotransferase (ALT) and triglycerides between the groups. It was concluded that obesity may be responsible for the development of parenchymal and hemodynamic changes in dog's liver / Mestre

Simple, cheap and reliable echo-based ultrasonic ranging systems such as the Polaroid ranging unit are easily applied to indoor applications. However, to measure the range between an unmanned helicopter and a moving ship deck at sea using ultrasound requires a more robust ranging system, because rushing air and breaking water are known ultrasound noise sources. The work of designing, constructing and testing such a system is described in this dissertation. The compact, UAV ready ultrasound transmitter module provides high power, broadband arbitrary signal generation. The separate field-ready receiver is based on a modern embedded Digital Signal Processor (DSP), providing high speed matched-filter correlation processing. Large time-bandwidth signalling is employed to maximise the signal to noise ratio of the ranging system. Synthesised experiments demonstrate the ability of the correlation processing to reliably recover timing from signals buried in noise. Real world experiments demonstrate decimetre accuracy with two centimetre resolution, ten metre range and 32Hz refresh rate. A maximum boresight range of up to 38m is supported.

This thesis documents a PhD research program undertaken at Swinburne University of Technology between the years 2000 and 2004. The research was funded by the Cooperative Research Centre for Cast Metals Manufacturing and was undertaken in collaboration with Nissan Casting Plant Australia Pty Ltd and the Ford Motor Company Australia Limited. This thesis reports on the investigation of the possibility of using an ultrasonic sensing-based, non-destructive testing system to detect gas porosity defects in aluminium die casting parts with rough surfaces. The initial intention was to develop a procedure to obtain ultrasonic signals with the maximum possible amplitude from defects within the rough surface areas of the castings. A further intention was to identify defects with the application of a suitable signal processing technique to the raw ultrasonic signal. The literature review has indicated that ultrasonic techniques have the potential to be used to detect subsurface defects in castings. The possibility of classifying very weak ultrasonic signals obtained from rough surface sections of castings through a neural network approach was also mentioned in the literature. An extensive search of the literature has indicated that ultrasonic sensing techniques have not been successfully used to detect sub-surface defects in aluminium die castings with rough surfaces. Ultrasonic inspection of castings is difficult due to the influence of microstructural variations, surface roughness and the complex shape of castings. The design of the experimental set-up used is also critical in developing a proper inspection procedure. The experimental set-up of an A-scan ultrasonic inspection rig used in the research is described in this thesis. Calibration of the apparatus used in the inspection rig was carried out to ensure the reliability and repeatability of the results. This thesis describes the procedure used to determine a suitable frequency range for the inspection of CA313 aluminium alloy castings and detecting porosity defects while accommodating material variations within the part. The results obtained from ultrasonic immersion testing indicated that focused probes operating at frequencies between 5 MHz and 10 MHz are best suited for the inspection of castings with surface roughness Ra values varying between 50 [micro milli] and 100 [micro milli]. For the purpose of validating the proposed inspection methodology, gas porosity defects were simulated through side-drilled holes in the in-gate section of selected sample castings. Castings with actual porosity defects were also used in this research. One of the conclusions of this research was that it was extremely difficult to detect defects in castings with surface roughness above 125 [micro milli]. Once the ultrasonic signal data was obtained from the sample aluminium die castings with different surface roughness values ranging from 5 [micro milli] to 150 [micro milli] signal analysis was carried out. Signal feature extraction was achieved using Fast Fourier Transforms (FFT), Principal Component Analysis (PCA) and Wavelet Transforms (WT) prior to passing the ultrasonic signals into a neural network for defect classification. MATLAB tools were used for neural network and signal pre-processing analysis. The results indicated that poor classification (less than 75%) was achieved with the WT, PCA and combination of FFT/PCA and WT/PCA pre-processing techniques for rough surface signals. However, the classification of the signals pre-processed with the combination of WT/FFT, FFT/WT and FFT/WT/PCA classifiers provided much better classification of more than 90% for smooth surface signals and 78% to 84% for rough surface signals. The results obtained from ultrasonic testing of castings with both real and simulated defects were validated with X-ray analysis of the sample castings. The results obtained from this research encourage deeper investigation of the detection and characterisation of sub-surface defects in castings at the as-cast stage. Implications for the industrial application of these findings are discussed and directions for further research presented in this thesis.

This thesis presents a comprehensive study of the ice particle production process through experimentation and numerical methods using computational fluid dynamics (CFD) that can be used to produce ice particles with controlled temperature and hardness for use in ice jet (IJ) process for industrial applications. The analytical and numerical modeling for the heat exchanger system are developed that could predict the heat, mass and momentum exchange between the cold gas and water droplets. Further, the feasibility study of the deployment of ice particles produced from the ice jet system for possible cleaning and blasting applications are analyzed numerically. Although the use of Abrasive Water Jet (AWJ) technology in cutting, cleaning, machining and surface processing is a very successful industrial process, a considerable amount of secondary particle waste and contamination impingement by abrasive materials has been an important issue in AWJ process. Some alternate cryogenic jet methods involving vanishing abrasive materials, such as plain liquid nitrogen or carbon dioxide have been tried for these applications, but they also suffer from certain drawbacks relating to the quality, safety, process control and materials handling. The use of ice jet process involving minute ice particles has received relatively little attention in industrial applications. Some researches have concentrated on the studies of effects of Ice Jet outlet parameters of the nozzle and focus tube for machining soft and brittle materials. Most of the work in this area is qualitative and researchers have paid a cursory attention to the ice particles temperature and the efficiency of production of these particles. An extensive investigation to gain insight knowledge into the formulation of ice formation process parameters is required in arriving at a deeper understanding of the entire ice jet process for production application. Experimental investigations were focussed on the measurement of ice particle temperature, phase transitions, ice particle diameter, coalescence and hardness test. The change in ice particle diameter from the inlet conditions to the exit point of the heat exchanger wasinvestigated using the experimental results. These observations were extended to numerical analysis of temperature variations of ice particles at different planes inside the custom built heat exchanger. The numerical predictions were carried out with the aid of visualization studies and temperature measurement results from experiments. The numerical models were further analysed to find out the behaviour of ice particles in the transportation stage, the mixing chamber of the nozzle and focus tube. This was done to find out whether the methodology used in this research is feasible and if it can be used in applications such as cleaning, blasting, drilling and perhaps cutting. The results of the empirical studies show that ice particles of desired temperature and hardness could be produced successfully with the current novel design of the heat exchanger. At the optimum parameters, ice particles could be produced below -60�C, with hardness of particles comparable to gypsum (Moh�s hardness of 1.5 to 3). The visualization studies of the process assisted in observation of the phases of ice at various points along the heat exchanger. The results of numerical analysis were found to agree well with the experiments and were supported by the statistical model assessments. Numerical analyses also show the survival of ice particles at the nozzle exit even with high-pressure, high-velocity water/air mixture.

<p>Technologies for position sensing and identification are important to have in ubiquitous computing environments. These technologies can be used to track users, devices, and artefacts in the physical milieu, for example, locating the position of a cellular phone in av physical environment. The aim of this thesis was to survey and classify available technologies for location sensing and identification. </p><p>We have made a literature study on both commercial and research-oriented systems and technologies for use in indoor and outdoor environments. We compared the characteristics of the underlying sensing technologies with respect to physical size, sensing method, cost, and accuracy. We conclude the thesis with a set of recommendations to developers and discuss the requirements on future sensing technologies and their use in mobile devices and environments.</p>

<p>I detta examensarbete har ett system för navigering och styrning av ett autonomt fordon implementerats. Syftet med detta arbete är att vidareutveckla fordonet som ska användas vid utvärdering av banplaneringsalgoritmer och studier av andra autonomifunktioner. Med hjälp av olika sensormodeller och sensorkonfigurationer går det även att utvärdera olika strategier för navigering. Arbetet har utförts utgående från en given plattform där fordonet endast använder sig av enkla ultraljudssensorer samt pulsgivare på hjulen för att mäta förflyttningar. Fordonet kan även autonomt navigera samt följa en enklare given bana i en känd omgivning. Systemet använder ett partikelfilter för att skatta fordonets tillstånd med hjälp av modeller för fordon och sensorer.</p><p>Arbetet är en fortsättning på projektet Collision Avoidance för autonomt fordon som genomfördes vid Linköpings universitet våren 2005.</p> / <p>In this thesis a system for navigation and control of an autonomous ground vehicle has been implemented. The purpose of this thesis is to further develop the vehicle that is to be used in studies and evaluations of path planning algorithms as well as studies of other autonomy functions. With different sensor configurations and sensor models it is also possible to evaluate different strategies for navigation. The work has been performed using a given platform which measures the vehicle’s movement using only simple ultrasonic sensors and pulse encoders. The vehicle is able to navigate autonomously and follow a simple path in a known environment. The state estimation is performed using a particle filter.</p><p>The work is a continuation of a previous project, Collision Avoidance för autonomt fordon, at Linköpings University in the spring of 2005.</p>

<p>Many engineering components reach a finite fatigue life well above 10⁹load cycles. Some examples of such components are found in airplanes, automobiles or high speed trains. For some materials the fatigue failures have lately been found to occur well after 10⁷ load cycles, namely in the Very High Cycle Fatigue (VHCF) range. This finding contradicted the established concept of fatigue limit for these materials, which postulates that having sustained 10⁷ load cycles the material is capable of enduring an infinite number of cycles provided that the service conditions are unchanged. With the development of modern ultrasonic fatigue testing equipment it became possible to experimentally establish VHCF behaviour of various materials. For most of them the existence of the fatigue limit at 10⁷ load cycles has been proved wrong and their fatigue strength continues to decrease with increasing number of load cycles.</p><p> </p><p>One important group of materials used for the production of high performance components subjected to the VHCF is tool steels. This study explores the VHCF phenomenon using experimental data of ultrasonic fatigue testing of some tool steel grades. The causes and mechanisms of VHCF failures are investigated by means of high resolution scanning electron microscopy, and in relation to the existing theories of fatigue crack initiation and growth. The main type of VHCF origins in steels are slag inclusions.</p><p>However, other microstructural defects may also initiate fatigue failure. A particular attention is paid to the fatigue crack initiation, as it has been shown that in the VHCF range crack formation consumes the majority of the total fatigue life. Understanding the driving forces for the fatigue crack initiation is a key to improve properties of components used for very long service lives. Finite element modelling of VHCF testing was added as an additional perspective to the study by enabling calculation of local stresses at the fatigue initiating defects.</p><p> </p><p> </p>

<p>The aim of this master's thesis is to develop a method that fully automates a trimming step in the production of a fiber-optical power spectrometer, based on a unique Acusto-Optical Scanning Filter.</p><p>The filter is created by letting an ultrasonic mechanical pulse pass through a chirped Fiber Bragg Grating. The pulse introduces a disturbance in the grating, creating a thin optical transmission window in the otherwise reflective bandwidth. The high demands on the window requires a precise, unit dependent pulse form with unknown properties. Thus each unit needs to be trimmed to reach required performance.</p><p>The manual trimming is largely a trial and error process, that contains two performance tests. We redefine one, eliminating the need to reroute the optical path and reducing the number of fiber weldings. The tests are then quantified, allowing a figure of merit to be based on weighted performance values.</p><p>A brute force method, testing a large set of pulses, is implemented. The set is defined by the parameter space spanned by previously produced units. Due to the large space, the method is too time consuming. Instead it is used to measure the performance spaces of three units. An attempt to largely reduce the parameter space using PCA failed.</p><p>An alternating variables method that finds local performance optima in the parameter space is developed. By using a set of several starting points, the method tends to find several qualified pulses. The method is implemented and successfully verified by trimming new units.</p><p>Finally we propose where to focus improvements of the method in a production ramp up.</p>