This thesis is a study of the production of human speech sounds by acoustic modelling and signal analysis. It concentrates on sounds that are not produced by voicing (although that may be present), namely plosives, fricatives and aspiration, which all contain noise generated by flow turbulence. It combines the application of advanced speech analysis techniques with acoustic flow-duct modelling of the vocal tract, and draws on dynamic magnetic resonance image (dMRI) data of the pharyngeal and oral cavities, to relate the sounds to physical shapes. Having superimposed vocal-tract outlines on three sagittal dMRI slices of an adult male subject, a simple description of the vocal tract suitable for acoustic modelling was derived through a sequence of transformations. The vocal-tract acoustics program VOAC, which relaxes many of the assumptions of conventional plane-wave models, incorporates the effects of net flow into a one-dimensional model (viz., flow separation, increase of entropy, and changes to resonances), as well as wall vibration and cylindrical wavefronts. It was used for synthesis by computing transfer functions from sound sources specified within the tract to the far field. Being generated by a variety of aero-acoustic mechanisms, unvoiced sounds are somewhat varied in nature. Through analysis that was informed by acoustic modelling, resonance and anti-resonance frequencies of ensemble-averaged plosive spectra were examined for the same subject, and their trajectories observed during release. The anti-resonance frequencies were used to compute the place of occlusion. In vowels and voiced fricatives, voicing obscures the aspiration and frication components. So, a method was devised to separate the voiced and unvoiced parts of a speech signal, the pitch-scaled harmonic filter (PSHF), which was tested extensively on synthetic signals. Based on a harmonic model of voicing, it outputs harmonic and anharmonic signals appropriate for subsequent analysis as time series or as power spectra. By applying the PSHF to sustained voiced fricatives, we found that, not only does voicing modulate the production of frication noise, but that the timing of pulsation cannot be explained by acoustic propagation alone. In addition to classical investigation of voiceless speech sounds, VOAC and the PSHF demonstrated their practical value in helping further to characterise plosion, frication and aspiration noise. For the future, we discuss developing VOAC within an articulatory synthesiser, investigating the observed flow-acoustic mechanism in a dynamic physical model of voiced frication, and applying the PSHF more widely in the field of speech research.

Resumo: Pesquisas epidemiológicas sobre disfonias na infância são escassas e apontam índices bastante variados entre 4,4 a 30,3%, estando relacionados às diferentes metodologias utilizadas. Determinar a prevalência de disfonia em crianças de quatro a doze anos, baseando-se nos julgamentos dos pais e nas avaliações perceptivo-auditiva, caracterizar a população estudada, os sintomas vocais, fatores de risco e sintomas associados; analisar os resultados dos exames de videolaringoscopias. Foram incluídas 2.000 crianças sorteadas em escolas públicas e subdividas em faixas etárias: quatro a seis anos, sete a nove anos e de dez a doze anos. Os pais preencheram um questionário sobre as qualidades vocais de seus filhos e as crianças foram submetidas às avaliações perceptivo-auditiva, tempo máximo de fonação (TMF), acústicas e aos exames de videolaringoscopias. Foram incluídas 2.000 crianças (1.007 meninos, 993 meninas). Sintomas vocais esporádicos foram reportados pelos pais de 206 delas e sintomas permanentes por 123, sendo estes últimos utilizados no cálculo do índice de disfonia. A avaliação perceptivo-auditiva registrou no parâmetro G da escala GRBASI, 694 vozes com escore 0, 1065 com escore 1 e 228 com escore 2. Os valores de TMF aumentaram com a idade e mantiveram-se menores nas crianças com escore 2 de G. O cálculo da relação s/z não se alterou com os escores da avaliação perceptivo-auditiva. As medidas acústicas indicaram diminuição da f0 com aumento da idade em ambos os sexos, e valores mais elevados de % de jitter, PPQ, % de shimmer, APQ, NHR E SPI. Nos exames de videolaringoscopias, os nódulos vocais, espessamento mucosos e processos inflamatórios foram as lesões mais encontradas, especialmente nas crianças com escore 1 e 2 de G. O julgamento dos pais indicou índice de prevalência de disfonia de 6,15%, elevando-se para 11,4% após as análises... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Epidemiological studies on dysphonia during childhood are scarce, and indicate rates ranging from 4.4 to 30.3% that are related to the different methods used. To determine the prevalence of dysphonia in children aged 4-12 years based on parental judgement and auditory-perceptual evaluation, as well as to characterize the study population, vocal symptoms, risk factors and associated symptoms, and videolaryngoscopic findings. Two thousand children attending public school were randomly selected and allocated into age groups: 4-6 years, 7-9 years, and 10-12 years. Parents were asked to answer a questionnaire about their children's vocal features. The participating children underwent auditory-perceptual evaluation, maximum phonation time (MPT) and acoustic assessment, and videolaryngoscopy. Of the 2000 children enrolled, 1007 were males and 993 were females. According to parental reporting, 206 children had sporadic vocal symptoms, and 123 showed permanent symptoms being, therefore, included in the calculation of the dysphonia index. Auditory-perceptual evaluation using the GRBASI scale revealed the following scores on the G parameter: 0 in 694, 1 in 1065, and 2 in 228 voice samples. MPT values increased with age, and remained lower among children with a G score of 2. The s/z ratio calculation did not change with auditoryperceptual scores. Acoustic measurements indicated f0 decreased as age increased in both genders, and higher jitter %, PPQ, shimmer %, APQ, NHR and SPI values. Vocal nodules, mucous thickening and inflammatory processes were the most frequent videolaryngoscopic findings, particularly in children with 1 and 2 G scores. Parental judgement indicated a dysphonia prevalence index of 6.15%, which rose to 11.4% after auditoryperceptual analysis was performed in a population of 2000 (993-F, 1.007-M). Most frequently reported vocal symptoms were related with vocal overload... (Complete abstract click electronic access below) / Orientador: Regina Helena Garcia Martins / Coorientador: Alcione Ghedni Brasolotto / Banca: Onivaldo Bretan / Banca: Vera Lucia Garcia / Banca: Kelly Silverio / Banca: Cristiano Melo / Doutor

Invasive bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix), hereafter, bigheaded carp, pose a major threat to the Great Lakes ecosystem as they advance toward Lake Michigan via the Illinois River. However, a series of navigation dams may deter their upstream movement. Starved Rock Lock and Dam (SRLD) is the most downstream gated dam on the Illinois River, therefore presenting the first navigation challenge for upstream migrating bigheaded carp. Before 2015, five acoustic receivers near SRLD detected successful upstream passage of only two of 900 tagged bigheaded carp. I further investigated the permeability of SRLD to bigheaded carp migration as a function of temperature, gage height, and dam operation. In 2015, I added 12 receivers around SRLD and acoustically tagged an additional 118 bigheaded carp downstream of SRLD. I also investigated the timing of bigheaded carp arriving downstream of SRLD using a generalized linear model. The explanatory variables influencing bigheaded carp arrival were average water temperature, average tailwater elevation, and the change in average water temperature. During 2015-2016, acoustic receivers recorded a total of 11 upstream passage events through SRLD, with nine through the dam gates, one through the lock chamber, and one undetermined. Passage through the dam gates occurred most frequently at high water levels when the dam gates were completely out of the water. The probability of upstream migrating bigheaded carp approaching SRLD was positively correlated with rising temperature and high gage. No upstream migrants approached SRLD between mid-September and late March. Overall, dam gates were more susceptible to upstream passage than the lock chamber, and environmental factors accurately predicted the arrival of bigheaded carp at SRLD. Modifying gate use during times of bigheaded carp arrival will likely prevent upstream passage through SRLD and other lock and dam structures.

Made available in DSpace on 2014-06-11T19:25:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-24Bitstream added on 2014-06-13T20:33:24Z : No. of bitstreams: 1 silva_af_me_arafcl.pdf: 940072 bytes, checksum: 3baa98e628ee79a59290c8f585f1d473 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo desta dissertação de mestrado é descrever do ponto de vista acústico as fricativas labiodentais, alveolares e palatoalveolares surdas e sonoras do Português Brasileiro em posição de onset e coda silábica. Para este estudo, foi montado um corpus composto por palavras dissílabas (reais e logatomas - palavras que não existem, mas que estão de acordo com a fonotaxe da língua). As palavras do corpus possuíam as seguintes estruturas silábicas: CV.CV; CVC.CV; CV.CVC. Assim, a posição de onset foi ocupada pelas fricativas labiodentais, alveolares e palatoalveolares e pela oclusiva bilabial surda. A posição de coda silábica foi ocupada sempre pelas fricativas alveolares. O núcleo silábico, por sua vez, foi ocupado pelas vogais /a/, /i/ e /u/ com o objetivo de verificar se o contexto vocálico interfere nas características das fricativas. As palavras do corpus foram inseridas na frase veículo “Digo palavra-alvo baixinho”, com o objetivo de homogeneizar o ambiente fonético. O corpus deste estudo foi gravado por cinco informantes (três homens e duas mulheres) naturais de Vitória da Conquista – BA, universitários com idade entre 18 e 27 anos. Cada informante repetiu as frases três vezes. Os parâmetros acústicos adotados para caracterizar as fricativas foram a duração segmental e a frequência do espectro. Como se sabe, a duração segmental pode variar de acordo com vários fatores, por isso, optamos por analisar a duração relativa das fricativas, e não a duração absoluta. Para a análise da taxa de frequência em que são realizadas as fricativas, utilizamos a análise dos quatro momentos espectrais (FORREST ET AL., 1988). Nossos resultados evidenciam que a duração relativa foi eficaz para distinguir as fricativas com relação ao ponto de articulação, à sonoridade, ao contexto vocálico e à posição silábica. No que refere-se à frequência... / The purpose of this master’s degree thesis is to describe from the acoustic point of view the labiodental, alveolar and postalveolar fricatives, voiced and voiceless, of Brazilian Portuguese in onset and coda position in syllables. For this study , a corpus was organized, composed by two-syllable words (real and logatome - words that do not exist, but they are in accordance with the language phonotactics). The words of the corpus had the following syllable structures: CV.CV; CVC.CV; CV.CV. Thus, the onset position was occupied by labiodental, alveolar and postalveolar fricatives and voiceless bilabial plosive. The coda position was always occupied by alveolar fricatives. The syllable nucleus, in turn, was occupied by the vowels /a/, /i/ and /u/ in order to check if the vowel context affects the characteristics of fricatives. The words from the corpus were inserted in the support sentence I say target word softly, in order to homogenize the phonetic environment. The corpus of this study was recorded by five participants (three men and two women) from Vitória da Conquista - BA, students aged between 18 and 27 years. Each participant repeated a sentence three times. The acoustic parameters used to define the fricatives were segmental duration and frequency spectrum. As we know, the segmental length can vary depending on several factors. Therefore, we chose to analyze the relative duration of fricatives and not the absolute duration. For the frequency rate analysis in which fricatives are produced, we employed an analysis of four spectral moments (FORREST ET AL., 1988). Our results proved that the relative length was effective to distinguish fricatives in relation to places of articulation, voicing, vowel context and syllable position. As regards the frequency of fricatives, the results show that the values of the first spectral moment were the most effective to distinguish fricatives... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:32:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-23Bitstream added on 2014-06-13T19:02:22Z : No. of bitstreams: 1 tavares_elm_dr_botfm.pdf: 915790 bytes, checksum: 8c4918b38a3d740c6bba7fada8665e65 (MD5) / Universidade Estadual Paulista (UNESP) / Pesquisas epidemiológicas sobre disfonias na infância são escassas e apontam índices bastante variados entre 4,4 a 30,3%, estando relacionados às diferentes metodologias utilizadas. Determinar a prevalência de disfonia em crianças de quatro a doze anos, baseando-se nos julgamentos dos pais e nas avaliações perceptivo-auditiva, caracterizar a população estudada, os sintomas vocais, fatores de risco e sintomas associados; analisar os resultados dos exames de videolaringoscopias. Foram incluídas 2.000 crianças sorteadas em escolas públicas e subdividas em faixas etárias: quatro a seis anos, sete a nove anos e de dez a doze anos. Os pais preencheram um questionário sobre as qualidades vocais de seus filhos e as crianças foram submetidas às avaliações perceptivo-auditiva, tempo máximo de fonação (TMF), acústicas e aos exames de videolaringoscopias. Foram incluídas 2.000 crianças (1.007 meninos, 993 meninas). Sintomas vocais esporádicos foram reportados pelos pais de 206 delas e sintomas permanentes por 123, sendo estes últimos utilizados no cálculo do índice de disfonia. A avaliação perceptivo-auditiva registrou no parâmetro G da escala GRBASI, 694 vozes com escore 0, 1065 com escore 1 e 228 com escore 2. Os valores de TMF aumentaram com a idade e mantiveram-se menores nas crianças com escore 2 de G. O cálculo da relação s/z não se alterou com os escores da avaliação perceptivo-auditiva. As medidas acústicas indicaram diminuição da f0 com aumento da idade em ambos os sexos, e valores mais elevados de % de jitter, PPQ, % de shimmer, APQ, NHR E SPI. Nos exames de videolaringoscopias, os nódulos vocais, espessamento mucosos e processos inflamatórios foram as lesões mais encontradas, especialmente nas crianças com escore 1 e 2 de G. O julgamento dos pais indicou índice de prevalência de disfonia de 6,15%, elevando-se para 11,4% após as análises... / Epidemiological studies on dysphonia during childhood are scarce, and indicate rates ranging from 4.4 to 30.3% that are related to the different methods used. To determine the prevalence of dysphonia in children aged 4-12 years based on parental judgement and auditory-perceptual evaluation, as well as to characterize the study population, vocal symptoms, risk factors and associated symptoms, and videolaryngoscopic findings. Two thousand children attending public school were randomly selected and allocated into age groups: 4-6 years, 7-9 years, and 10-12 years. Parents were asked to answer a questionnaire about their children’s vocal features. The participating children underwent auditory-perceptual evaluation, maximum phonation time (MPT) and acoustic assessment, and videolaryngoscopy. Of the 2000 children enrolled, 1007 were males and 993 were females. According to parental reporting, 206 children had sporadic vocal symptoms, and 123 showed permanent symptoms being, therefore, included in the calculation of the dysphonia index. Auditory-perceptual evaluation using the GRBASI scale revealed the following scores on the G parameter: 0 in 694, 1 in 1065, and 2 in 228 voice samples. MPT values increased with age, and remained lower among children with a G score of 2. The s/z ratio calculation did not change with auditoryperceptual scores. Acoustic measurements indicated f0 decreased as age increased in both genders, and higher jitter %, PPQ, shimmer %, APQ, NHR and SPI values. Vocal nodules, mucous thickening and inflammatory processes were the most frequent videolaryngoscopic findings, particularly in children with 1 and 2 G scores. Parental judgement indicated a dysphonia prevalence index of 6.15%, which rose to 11.4% after auditoryperceptual analysis was performed in a population of 2000 (993-F, 1.007-M). Most frequently reported vocal symptoms were related with vocal overload... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:34:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-11-30Bitstream added on 2014-06-13T20:05:58Z : No. of bitstreams: 1 cunha_mgs_dr_guara.pdf: 2456684 bytes, checksum: 35c3e64f73a4469232f7849a6e313dfa (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os músculos estriados esqueléticos, através de suas propriedades de contratilidade, extensibilidade e elasticidade, formam o principal motor das articulações nos seres humanos, através da tração exercida no tendão ou na aponeurose. Os músculos controlam, coordenam e realizam os movimentos articulares. A força produzida pelos músculos pode ser estimada através das alavancas realizadas pelo membro, considerando-se o torque de cada força, quando o músculo se contrai, parte da energia desta contração será dissipada na forma de som. A presente pesquisa tem como objetivo principal desenvolver um sistema para avaliar o sinal acústico muscular e comparar com a força produzida em uma célula de carga pela alavanca do membro superior. Os músculos selecionados para esta pesquisa foram os flexores do cotovelo, pela facilidade de acesso e de posicionamento. Foram coletados os sinais acústicos e do esforço realizado de 16 indivíduos de ambos os sexos, sendo 9 do sexo masculino e 7 do sexo feminino, saudáveis, com idade entre 18 e 35 anos, sem histórico de doenças neurológicas, cardiovasculares, não praticantes de atividade física que produzisse a hipertrofia dos músculos flexores do cotovelo. Foi desenvolvido um sistema para avaliação do sinal acústico muscular utilizando como sensor um estetoscópio adaptado com um microfone, simultaneamente à aquisição do torque produzido pelos flexores do cotovelo e avaliado por uma célula de carga. A presente pesquisa permitiu identificar que as principais freqüências acústicas da contração dos flexores do cotovelo estão na faixa de 10 a 15 Hz quando a contração equivale de 75 a 100% da força máxima para o sexo feminino e de 50 a 100 % da força máxima para o sexo masculino e na faixa de 5 a 10 Hz quando a contração equivale de 25 a 50 % da força máxima para o sexo feminino e 25 % da força máxima para o sexo masculino... / Striated skeletal muscles, through their properties of contractility, extensibility and elasticity, are the main driver of the joints in humans, through the traction exerted on the tendon or aponeurosis, muscle control, coordinate and carry out joint movements. The force produced by muscles can be estimated using from the levers held by the member, considering the torque of each force when the muscle contracts, this contraction of the energy is dissipated in the form of sound. The main objective of this research is to develop a system to evaluate the acustic signal and compare it with the muscular force produced in a load cell by the lever of the upper limb. The muscles selected for this research were elbow flexors, because of the easy access and positioning. Acoustic signals were collected and the effort made to 16 individuals of both sexes. We analyzed 9 male and 7 female, healthy and aged between 18 and 35 years old with no history of neurological and cardiovascular disease and not engaged in physical activity that could develop hypertrophy of the elbow flexor muscles. A system was developed for evaluation of the acoustic signal using muscle as a sensor adapted stethoscope with a microphone, simultaneously with the aquisition of the torque produced by the elbow flexor and evaluated by a load cell. This research has identified that the main acoustic frequencies of contraction of the elbow flexors are in the range of 10 to 15 Hz when the contraction equals 75 to 100% of maximum force for females and 50 to 100% of maximum force to males and in the range 50 to 10 Hz when the contraction equals 25 to 50% of maximum force for females and 25% of maximum force for males, as well as the correlation of the acoustic signals of males female with a coefficient less than 4. It was concluded that the acoustic signal muscle has specific characteristics for different levels of intensity of muscle... (Complete abstract click electronic access below)

Directional acoustic beams are used in diverse sonar systems. For efficient transmission of a sonar signal, the sound energy is projected in a narrow beam . For reduced interference in reception, the sound signal is received from a narrow spatial sector. Typically, such beams have associated sidelobes which adversely affect sonar performance. The goal of this thesis is to propose several novel acoustic arrays which are capable of generating desired search-light-type and fan-type beams with greatly reduced sidelobes. These novel acoustic arrays have fewer elements than conventional arrays of similar performance. The design of such novel arrays is inherently more difficult, however, since it involves nonlinear optimization. Such an optimization is normally computationally intensive and may not be globally convergent. This difficulty has been overcome by newly developed concepts and associated array pattern synthesis methods. A new concept called the equivalent linear array is introduced; a design method based on this concept benefits from existing design techniques developed for linear arrays. The equivalent linear array concept is further developed to lead to a new and effective method for array radiation pattern synthesis. A second new concept called the scale-invariance radiation pattern is introduced, and the subsequent relation between two novel arrays is discovered. Using this concept an angle mapping approach is developed which transforms a radiation pattern generated by a circular ring array to that of an elliptic ring array. This approach takes advantage of methodologies developed for the design of circular ring arrays. A third concept, constraint directions, is introduced; a subsequent new iterative method for array pattern synthesis is developed to meet the need in compact receiving/transmitting array design. With the help of these new concepts, the proposed synthesis methods avoid the use of nonlinear optimization techniques and merely require simple matrix operations. The methods can be applied to the problems of synthesizing radiation patterns of arrays with arbitrary sidelobe envelopes, with nonisotropic elements, and with nonuniform spacing between elements. The usefulness of the developed methodologies is demonstrated in various design examples. The methods developed provide powerfuI tools not only to design novel acoustic arrays but also to design antenna arrays. / Graduate

Accurate characterisation of fluid flow at tidal energy sites is critical for cost effective Tidal Energy Converter (TEC) design in terms of efficiency and survivability. The standard instrumentation in tidal site characterisation has been Diverging acoustic-Beam Doppler Profilers (DBDPs) which remotely measure the flow over a range of scales, resolving up to three velocity vectors. However, they are understood to have several drawbacks particularly in terms of characterising turbulent aspects of the flow. This characterisation is generally based upon a small number of key transient metrics, the accuracy of which directly impacts TEC designs. This work presents an optimisation and performance assessment of newly available Single Beam Doppler Profilers (SBDPs) mounted on a commercial-scale tidal turbine at mid-channel depth in a real operating environment. It was hypothesised that SBDPs would have advantages over DBDPs for site characterisation, in terms of reduced random error, reduced uncertainty in turbulence intensities and the ability to quantify the structure of the turbulent flow. The relationship between random error, sensor orientation and flow speed is quantified for both single and diverging beam sensor types. Random error was found to increase with increasing flow velocity as a power law, the slope of which varies for different sensor orientations. Quantification of noise offers a practical method to correct turbulence metrics. To enable the use of multiple acoustic sensors mounted in close proximity, interference was quantified and mitigation techniques examined. Cross-talk between sensors of the same type were generally shown to bias measurements towards zero. In the presence of alternate types of acoustic sensors, interference caused an increase in standard deviation of velocity results. Implementing a timing offset control mechanism was able to mitigate this effect. This work has achieved a greater understanding of the drivers (spatial separation, inclination angle, pulse power) and effects on measurements of interference along with ambient-noise for users of acoustic instruments. Lessons learned of value to the industry, as site characterisation work intensifies ahead of next generation commercial scale devices, are presented. Mid-channel depth mounted SBDPs were found to have advantages over seabed mounted DBDPs in resolving the key turbulent flow metrics. SBDPs were able to resolve integral length-scales of turbulence that show an anisotropic ratio of scales as predicted from theory and in work at similar sites, while the DBDPs results were similar for all directions. Turbulence intensity measurements were found to be similar after noise correction, with the SBDPs more able to accurately capture the turbulence dissipation rate. This evidence suggests that SBDP arrays present a significant improvement over bottom mounted DBDPs in discerning information about the nature of the turbulent flow, and thus future site characterisation work should consider the use of SBDPs alongside bottom mounted DBDPs for this purpose.

Orientador: Ricardo Tokio Higuti / Banca: Francisco Villarreal Alvarado / Banca: Washington Luiz de Barros Melo / Resumo: Um dos setores de grande importância na indústria frigorífica é o responsável pelo esquarte- jamento de aves, no qual peças inteiras são separadas em partes menores para comercialização. O processo de esquartejamento pode ser feito de forma automática, através de máquinas de corte, ou por trabalhadores, que cortam as aves utilizando uma serra circular. Por ser um tra- balho manual e envolver uma lâmina de corte, a periculosidade desse tipo de trabalho é alta, de maneira que mesmo com o uso de uma luva de aço inox como equipamento de proteção, costumam ocorrer acidentes que podem variar desde pequenos cortes até amputação de parte da mão do trabalhador atingido. Neste trabalho, é apresentado um método de análise de sinais para evitar que esse tipo de acidente ocorra. Esse sistema baseia-se na análise dos sinais acústicos envolvidos gerados durante esse processo e são utilizados para desligar o motor que impulsiona a serra e acionar um sistema de frenagem em casos quando houver a ocorrência de acidentes. O problema é abordado utilizando inicialmente um filtro digital e, posteriormente, com as técni- cas de análise multirresolução apresentadas pelas wavelets. Além disso, empregou-se também a decomposição de modo empírico, que também realiza uma análise multirresolução dos sinais decompondo os mesmos em funções de modo intrínseco. Visando detectar o maior número possível de toques suaves de luva na serra sem que cortes de ossos de frango fossem confundi- dos com toques de luva, o sistema apresentou um índice de acertos de aproximadamente 70%, havendo a ocorrência de apenas 2% de falsos positivos. Além desse problema, abordou-se o caso de detecção de trinca em ovos, no qual o objetivo era separar ovos trincados de ovos in- teiros utilizando um sistema barato e eficiente... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: One of the most important sectors in the meatpacking industry is chicken quartering, where whole pieces are cut into smaller ones. The quartering process can be done by automatic ma- chines or by manually cutting the chickens using a circular saw. The manual technique imposes physical risks for the workers, which wear protective stainless steel gloves. Small injuries or, in the worst case, amputation of part of the hand can occur in the event of an accident. In this work, we propose a methodology to prevent this type of accident, which is based on the anal- ysis of the acoustic signals generated during this process. In the event of an accident, the saw touches the metal glove, the acoustic signals are processed and used to turn off the engine that drives the saw and trigger a braking system. The problem is firstly analyzed using a digital filter and then with multiresolution techniques by wavelet analysis. In addition, the empirical mode decomposition technique is also employed, which also performs multiresolution analysis of sig- nals. These three techniques are implemented and compared. The method presented a 70% of successful detection of light touches of saw/glove and 2% of false positives, when a normal cut operation is detected as a saw/glove touch, in general occurring when cutting specific parts of bone. Besides this problem, the case of eggshell crack detection is studied, where the goal was to separate cracked eggs from intact eggs using an inexpensive and efficient system. A solenoid was used as a source of mechanical excitation and the resulting acoustic signals were acquired and processed. The same signal processing techniques were employed and compared, with small changes in parameters. As a result, it was possible to detect 80% of cracked eggs and 100% of intact eggs. The multiresolution technique... (Complete abstract click electronic access below) / Mestre

Acoustic levitation is a method which uses sound radiation to suspend matter in a medium. The main use of this phenomenon is for the contactless processing of matter, allowing to manipulate small objects without any solid contact. Contactless processing of matter presents many advantages in, for example, the fabrication of MEMS (microelectromechanical systems) where handling the components is challenging because of their fragile and surface-sensitive characteristics or in the chemical/biological industry when handling high-purity or hazardous materials. Thus, a new device for noncontact linear transportation of small solid objects is presented here. In this device, ultrasonic flexural vibrations are generated along the ring shaped vibrator using two Langevin transducers and by using a reflector parallel to the vibrator, small particles are trapped at the nodal points of the resulting acoustic standing wave. The particles are then moved by generating a traveling wave along the vibrator, which can be done by modulating the vibration amplitude of the transducers. The working principle of the traveling wave along the vibrator has been modeled by the superposition of two orthogonal standing waves, and the position of the particles can be predicted by using finite element analysis of the vibrator and the resulting acoustic field. A prototype consisting of a 3 mm thick, 220 mm long, 50 mm wide and 52 mm radius aluminum ring-type vibrator and a reflector of the same length and width was built and small polystyrene spheres have been successfully transported along the straight parts of the vibrator. / Levitação acústica é um método para suspender matéria em um meio através de pressão de radiação acústica gerada por intensas ondas de som. O principal uso desse fenômeno é na manipulação de partículas sem contato solido. Esse fenômeno tem várias aplicações para pesquisas onde deve ser evitado todo o contato como, por exemplo, na área de biologia, química, e na fabricação de MEMS. Assim, um novo sistema de transporte linear de partículas por levitação acústica está apresentado aqui. Nesse sistema, vibrações flexurais estão geradas em uma placa tipo anel com dois transdutores tipo Langevin, e colocando um refletor paralelo ao oscilador, partículas estão presas no pontos nodais da onda acústica gerada. As partículas estão deslocadas modulando a amplitude dos transdutores. Assim, este trabalho tem como objetivos a modelagem do fenômeno de levitação acústica, o dimensionamento de um protótipo de sistema de transporte linear de partículas por levitação acústica, bem como a fabricação e o controle desse protótipo. Um protótipo consistindo de uma estrutura tipo anel de alumínio de 3 mm de espessura, 220 mm de comprimento e um raio de 52 mm foi fabricado e o transporte de pequenas esferas de isopor foi realizado com êxito nas parte retas do vibrador.