O presente estudo propõe investigar o método para estimar a força exercida pelo parafuso na junta aparafusada, propondo uma possível substituição a célula de carga convencional. Com base na técnica pulso-eco ultrassônico, verificando o tempo de propagação da onda em um parafuso retificado antes e após ser submetida a uma carga normal. A diferença de tempo correlacionada à força medida pela célula de carga foi realizada após a aplicação de um torque de aperto na região elástica da fixação. As amostras de parafuso foram retificados nas suas extremidades paralelas, o aparelho ultrassônico com transdutor de 5MHz de 6mm de diâmetro foi acoplado magneticamente sob o parafuso utilizando gel a base dágua como acoplante, para assim verificar o deslocamento, no tempo, do sinal do eco que é detectado por um limiar de amplitude desse sinal, o tempo de voo do pulso-eco longitudinal no meio isotrópico foi o objeto do estudo para correlacionar com a força medida em uma célula que mede força (kN). A diferença do tempo do pulso ultrassônico foi causado por um esforço longitudinal após um torque aplicado na região elástica de resistência mecânica do parafuso na junta simulada, utilizando um equipamento que basicamente é formado por célula de carga longitudinal e torcional com torquímetro eletrônico transdutorizado para efetuar o aperto gradativo. Este equipamento é atualmente usado para verificar o atrito de elementos roscados e as interações de inúmeras possibilidades de superfícies de contato, tais quais porcas e parafusos, conforme fórmulas da norma ISO16047. / The present study proposes to investigate the method to estimate the force exerted by the screw in the bolted joint, proposing a possible replacement to the conventional load cell. Based on the pulse-echo technique ultrasonic, checking the wave propagation time in a rectified screw before and after being subjected to a normal load. The time difference correlated to the force measured by the load cell was performed after the application of a tightening torque in the elastic region of the fixation. The screw samples were rectified at their parallel ends, the ultrasonic apparatus with a 5MHz of 6mm diameter was magnetically coupled under the screw using water-based gel as a coupling, to thereby verify the time shift of the echo signal that is detected by a threshold amplitude of that signal, the flight time of the pulse-echo in the isotropic medium was the object of the study to correlate with the force measured in a cell that measures force (kN). The difference of the time of the ultrasonic pulse was caused by a longitudinal effort after a tightening torque applied in the elastic region of mechanical resistance of the screw in the simulated joint, using equipment that basically is formed by cell of longitudinal and torsional load with electronic transduced torque wrench to define the gradual tightening. This equipment is currently used to check the friction of threaded elements and the numerous possibilities of contact surfaces, such as nuts and bolts, according to ISO16047 formulas.

The ability to numerically determine the received signal in an ultrasound pulse-echo system is very important for the development of new ultrasound applications, such as tissue characterization, complex object recognition, and identification of surface topology. The output signal from an ultrasound pulse-echo system depends on the transducer geometry, reflector shape, location and orientation, among others, therefore, only by numerical modeling can the output signal for a given measurement configuration be predicted. This thesis concerns about the numerical modeling and optimal design of annular array based ultrasound pulse-echo system for object recognition. Two numerical modeling methods have been implemented and evaluated for calculating received signal in a pulse-echo system. One is the simple, but computationally demanding Huygens Method and the other one is the computationally more efficient Diffraction Response for Extended Area Method (DREAM). The modeling concept is further extended for pulse-echo system with planar annular array. The optimal design of the ultrasound pulse-echo system is based on annular array transducer that gives us the flexibility to create a wide variety of insonifying fields and receiver characteristics. As the first step towards solving the optimization problem for general conditions, the problem of optimally identifying two specific reflectors is investigated. Two optimization methods, the straightforward, but computationally intensive Global Search Method and the efficient Waveform Alignment Method, have been investigated and compared.

A Lagoa dos Patos, por sua importância e magnitude, é alvo de inúmeras pesquisas relacionadas ao seu contexto evolutivo geológico e paleogeográfico. Para a investigação das características de seu fundo e subfundo, foram executados, nos anos de 2002 e 2006, levantamentos de cerca de 700 Km de dados sísmicos de 3,5 kHz. O presente trabalho considerou aproximadamente 153 Km de registros sísmicos levantados na célula sul da Lagoa dos Patos, objetivando a identificação e mapeamento dos eco-caracteres da área. Para integração dos dados e visualização dos resultados finais, métodos de geoprocessamento foram aplicados. Os perfis sísmicos analisados permitiram a identificação de três principais eco-caracteres, que foram agrupados de acordo com o aspecto do refletor primário (fundo), ocorrência de refletores subsuperfície e geometria dos refletores de subsuperfície. O eco-caráter A se foi definido por refletor primário (fundo) plano e forte, seguido por refletores fortes e bem definidos; o eco-caráter B foi caracterizado a partir de refletor primário difuso e reflexões de subsuperfície pouco definidas, difusas ou com aspecto de manchas; o eco-caráter C consistiu em refletor primário plano e muito forte, seguido por sucessivas reflexões múltiplas de baixa perda. Estes eco-caracteres foram relacionados à batimetria da área e aos sedimentos de fundo do local, de forma observar a relação entre estes e a resposta acústica associada ao eco. Os eco-caracteres identificados foram correlacionáveis às características sedimentológicas da área e aos processos hidrodinâmicos atuantes na célula sul do sistema lagunar. Anomalias acústicas identificadas nos registros sonográficos evidenciaram a ocorrência de grande quantidade de gás raso, disseminado nos pacotes sedimentares intralagunares. Este trabalho confirma a importância de um melhor entendimento dos efeitos da hidrodinâmica nos processos de sedimentação e apresenta informações relevantes para o auxílio de estudos geomorfológicos e hidrodinâmicos a serem realizados na Lagoa dos Patos. / The Patos Lagoon, for its importance and magnitude, is the subject of numerous researches related to its geological and paleogeographic evolutionary context. For the investigation of its bottom and subbottom characteristics, about 700 km of seismic data of 3.5 kHz were surveyed in 2002 and 2006. This study considered nearly 153 Km of seismic records collected in the south of the Patos Lagoon cell, aiming to the identification and mapping of echo-character. For data integration and visualization of the results, geoprocessing methods were applied. The seismic profiles analyzed allowed the identification of three major echo-characters, which were grouped according to the aspect of the primary reflector (bottom), the occurrence of subbottom reflections, the geometry of the subbottom reflections. The echo-character A presented distinct and continuous surface (bottom) with well-defined subbottom reflections, generally parallel and continuous, which follow the topography of the surface; echo-character B was characterized by a diffuse primary reflector and poorly defined subbottom reflections, diffuse or blurry; echo-character C consisted of a plane and very strong well-defined first reflector and presents a series of low loss multiple reflections. These echo-characters were related to the bathymetry and the bottom sediments of the area, in order to observe the relationship between them and the acoustic response associated with the echo. The echo-characters identified presented good correlation to the sedimentological characteristics of the area and the hydrodynamic processes acting in the south cell of the lagoon system. Acoustic anomalies identified in ecograms indicate the occurrence of large amounts of shallow gas spread in intra-lagoon sedimentary packages. This study confirms the importance of a better understanding of the effects of hydrodynamics in sedimentation processes and presents relevant information to support geomorphological and hydrodynamics studies to be conducted in the Patos Lagoon.

Contexte : L'echodoppler carotidien (EDC) est un outil pour définir le risque cardio-vasculaire (RCV) mais peut progresser dans ses indications et dans les paramètres mesurés. Les travaux 1-2-3 étudient les correlations échographiques de l'index de volume de plaque (IVP). Les études 4-5 étudient l’apport de l’EDC dans l'évaluation du RCV des patients avec syndromes coronaires aigus (SCA). Matériels: les études N°1-2-3 ont été réalisées sur 93 patients avec EDC. Les études 4-5 ont été réalisées sur 152 patients avec SCA et EDC systématique. Les analyses sont transversales et longitudinales. Résultats : L'IVP n’est pas corrélé aux paramètres usuels de quantification de l’athérome carotidien. Il est plus sensible que le degré de sténose pour mesurer les changements de la plaque d’athérome. L'EDC chez tous les patients atteints de SCA est peu rentable. Ciblé aux patients âgés et diabétiques, il améliore ses performances. Les plaques carotidiennes 50-70 % ont une valeur pronostique significative. Conclusion : L’EDC est un outil intéressant pour aborder le RCV. Sa meilleure utilisation (quantitative et qualitative) permet de mieux appréhender le RCV. / Background: Carotid echo Doppler (EDC) is an interesting tool to define the cardio vascular risk (RCV) of patients. However its performances could be increased with creation of new parameters The studies n°1, 2 and 3 studied the correlations between the plaque volume index (IVP) and the currently used echographic parameters. Studies n° 4 and 5 studied the contribution of EDC for evaluating the RCV in patients with an acute coronary syndrome (ACS). Materials: Studies n°1,2 and 3 were performed on 93 patients with EDC. Studies n° 4 and 5 were performed on 152 patients with an SCA and EDC systematically achieved. Results: IVP was not correlated with the parameters currently used to quantify carotid atheroma. IVP was more sensible than the stenosis degree to detect the changes in carotid atheroma. EDC performed in all patients with an SCA could not be justified. Performed in elderly and diabetic patients, this tool was very useful to detect severe stenosis with an impact on patients’s management. Asymptomatic Carotid narrowing between was found to have a prognostic value. Conclusion: EDC is an interesting tool to understand the RCV. Its better use (quantitative and qualitative) should allow to reduce the CV morbid mortality.

O presente estudo propõe investigar o método para estimar a força exercida pelo parafuso na junta aparafusada, propondo uma possível substituição a célula de carga convencional. Com base na técnica pulso-eco ultrassônico, verificando o tempo de propagação da onda em um parafuso retificado antes e após ser submetida a uma carga normal. A diferença de tempo correlacionada à força medida pela célula de carga foi realizada após a aplicação de um torque de aperto na região elástica da fixação. As amostras de parafuso foram retificados nas suas extremidades paralelas, o aparelho ultrassônico com transdutor de 5MHz de 6mm de diâmetro foi acoplado magneticamente sob o parafuso utilizando gel a base dágua como acoplante, para assim verificar o deslocamento, no tempo, do sinal do eco que é detectado por um limiar de amplitude desse sinal, o tempo de voo do pulso-eco longitudinal no meio isotrópico foi o objeto do estudo para correlacionar com a força medida em uma célula que mede força (kN). A diferença do tempo do pulso ultrassônico foi causado por um esforço longitudinal após um torque aplicado na região elástica de resistência mecânica do parafuso na junta simulada, utilizando um equipamento que basicamente é formado por célula de carga longitudinal e torcional com torquímetro eletrônico transdutorizado para efetuar o aperto gradativo. Este equipamento é atualmente usado para verificar o atrito de elementos roscados e as interações de inúmeras possibilidades de superfícies de contato, tais quais porcas e parafusos, conforme fórmulas da norma ISO16047. / The present study proposes to investigate the method to estimate the force exerted by the screw in the bolted joint, proposing a possible replacement to the conventional load cell. Based on the pulse-echo technique ultrasonic, checking the wave propagation time in a rectified screw before and after being subjected to a normal load. The time difference correlated to the force measured by the load cell was performed after the application of a tightening torque in the elastic region of the fixation. The screw samples were rectified at their parallel ends, the ultrasonic apparatus with a 5MHz of 6mm diameter was magnetically coupled under the screw using water-based gel as a coupling, to thereby verify the time shift of the echo signal that is detected by a threshold amplitude of that signal, the flight time of the pulse-echo in the isotropic medium was the object of the study to correlate with the force measured in a cell that measures force (kN). The difference of the time of the ultrasonic pulse was caused by a longitudinal effort after a tightening torque applied in the elastic region of mechanical resistance of the screw in the simulated joint, using equipment that basically is formed by cell of longitudinal and torsional load with electronic transduced torque wrench to define the gradual tightening. This equipment is currently used to check the friction of threaded elements and the numerous possibilities of contact surfaces, such as nuts and bolts, according to ISO16047 formulas.

Infrastructure deterioration is an international problem requiring significant attention. One particular manifestation of this deterioration is the occurrence of sub-surface cracking (delaminations) in reinforced concrete bridge decks. Of many techniques available for inspection, air-coupled impact-echo testing, or sounding, is a non-destructive evaluation technique to determine the presence and location of delaminations based upon the acoustic response of a bridge deck when struck by an impactor. In this work, two automated air-coupled impact echo sounding devices were designed and constructed. Each device included fast and repeatable impactors, moving platforms for traveling across a bridge deck, microphones for air-coupled sensing, distance measurement instruments for keeping track of impact locations, and signal processing modules. First, a single-channel automated sounding device was constructed, followed by a multi channel system that was designed and built from the findings of the single-channel apparatus. The multi channel device performed a delamination inspection in the same manner as the single-channel device but could complete an inspection of an entire traffic lane in one pass. Each device was tested on at least one concrete bridge deck and the delamination maps produced by the devices were compared with maps generated from a traditional chain-drag sounding inspection. The comparison between the two inspection approaches yielded high correlations for bridge deck delamination percentages. Testing with the two devices was more than seven and thirty times faster, respectively, than typical manual sounding procedures. This work demonstrates a technological advance in which sounding can be performed in a manner that makes complete bridge deck scanning for delaminations rapid, safe, and practical.

Delaminations in concrete bridge decks result primarily from corrosion of the reinforcing bars (or rebar). This corrosion leads to volumetric expansion of the rebar. When the rebar expands, concrete cracks, and there is a localized separation of the concrete cover from the underlying concrete. Impact-echo testing is an effective technique to map delaminations on concrete bridge decks. However, mapping speed is limited by necessary retrieval of the impactor for traditional tests. To achieve higher scanning speeds, it is advantageous to use both a non-contact measurement (air-coupled impact-echo) and disposable-impactor excitation. Disposable impactors have the potential advantage of achieving greater deck scanning speeds because they do not need to be retrieved, and they can also be used with air-coupled measurement systems. This thesis reports impact excitation of concrete using disposable impactors such as water droplets and ice balls. The impact characteristics of these impactors are compared with those of steel balls and chain links. Comparing the acoustic recordings on intact and delaminated concrete surface shows that water droplets and ice balls are able to excite flexural resonant modes associated with delamination defects. The use of water droplets and ice balls for shallow delamination detection in concrete is thus demonstrated.

The aim of this study was to investigate the perception of personalization on news applications and to examine to what extent it is seen as an optimal solution for users to receive information. Due to the growth of online news and digital journalism the amount of information that is being published online is significantly higher nowadays than it has previously been. Therefore, a recommendation system called personalization has been introduced to choose content for the reader. Many concerns of personalization have already been brought to light, these concerns are believed to be contributing to filter bubbles and echo chambers. This study will investigate these concerns further in order to understand the users. The methodology used in the study were semi-structured interviews and an analysis based on the concerns brought forward by Borgesius et al. Six interviews were conducted with users and two were conducted with major news organizations in Sweden. The results of the study indicate that users fear personalization will cause filter bubbles and polarization due to them only being subjected to one perspective. The users are unaware as to how personalization works and therefore question why it is being introduced into news applications. Due to personalization being a new phenomenon news applications it is not yet seen as an optimal solution by users or news organizations. There are, however, many factors that can assist in its development such as transparency and awareness of the phenomenon.

The need for assessment of benthic habitat characteristics may arise for many reasons. Such reasons may include but are not limited to, habitat mapping, environmental concerns and identification of submerged aquatic vegetation. Oftentimes, such endeavors employ the use of aerial photography, satellite imagery, diving transects and extensive sampling. Aerial photography and remote sensing techniques can be severely limited by water clarity and depth, whereas diver transects and extensive sampling can be time consuming and limited in spatial extent. Acoustic methods of seabed mapping, such as the acoustic sediment classification system QTC are not hampered by water clarity issues. The acoustic sediment classification system QTC is capable of providing greater spatial coverage in fractions of the time required by divers or point sampling. The acoustic classification system QTC VIEW VTM was used to map benthic habitats within Tampa Bay. The QTC system connected in parallel to an echo-sounder is capable of digitally extracting and recording echoes returning from the seabed. Recorded echoes were processed using QTC IMPACTTM software. This software partitions echo waveforms into groups or classes based on their similarity to one another using multivariate statistics, namely Principal Component Analysis and K-Means clustering. Data was collected at two frequencies, 50 kHz and 200 kHz. Side-scan sonar data was collected coincident with the QTC data and used to produce mosaics of the various habitats in Tampa Bay. Side-scan sonar data was classified using QTC SideviewTM in an attempt to identify changes in benthic habitats. Sediment samples used for ground-truth were subjected to grain size analysis. Also, the percentage of organic matter and carbonate within samples was determined. Results of acoustic classification appear to accurately reflect changes in the sediment type and structure of the seabed. Grain size, particularly percent mud, appears to have a strong influence on classification. Carbonate hard bottom habitats were found to be acoustically complex, a characteristic useful for their identification. The QTC system was able to detect seagrass, although some misclassification occurred between vegetated and non-vegetated seabeds.

There is an ever-growing and increasing amount of technology options that use speech recognition software. Currently, the market includes smartphones, computers, and individual smart home personal assistants that allow for hands-free access to this technology. Research studies have explored the utility of these assistive devices for the completion of activities of daily living; however, there is limited research looking at the accuracy of voice recognition software within smart home personal assistants in populations with disordered speech. In persons with amyotrophic lateral sclerosis (ALS), symptoms include changes to motor functions, speech in particular, and it is unknown how some of these devices may respond to their disordered speech. The present study aimed to examine the accuracy of the Amazon Echo to respond appropriately to commands given by dysarthric patients with ALS. Participants were asked to read a variety of commands to an Amazon Echo. The sentences and responses by the Amazon Echo were audio-recorded for transcription and intelligibility ratings, which were then analyzed to look for relationships between intelligibility, auditory-perceptual features of speech, and sentence type. Results revealed there was no significant relationship between command intelligibility and accuracy of response by the Amazon Echo, nor was there a significant relationship between any of the auditory-perceptual ratings and accuracy of response. There was, however, a significant and positive association between conversational intelligibility and accuracy of responses by the Amazon Echo. This study provides support for use of hands-free assistive technology in patients with ALS to aid in the maintenance of quality of life and activities of daily living.