The scientific applications and engineering aspects of multispectral and hyperspectral imaging systems have been studied extensively. The traditional geometric spectral imaging system model is specifically developed aiming at spectral sensors with spectrally non-overlapping bands. Spectral imaging systems with overlapping bands also exist. For example, the quantum-dot infrared photodetectors (QDIPs) for midwave- and longwave-infrared (IR) imaging systems exhibit highly overlapping spectral responses tunable through the bias voltages applied. This makes it possible to build spectrally tunable imaging system in IR range based on single QDIP. Furthermore, the QDIP based system can be operated as being adaptive to scenes. Other optical imaging systems like the human eye and some polarimetric sensing systems also have overlapping bands. To analyze such sensors, a functional analysis-based framework is provided in this dissertation. The framework starts from the mathematical description of the interaction between sensor and the radiation from scene reaching it. A geometric model of the spectral imaging process is provided based on the framework. The spectral response functions and the scene spectra are considered as vectors inside an 1-dimensional spectral space. The spectral imaging process is abstracted to represent a projection of scene spectrum onto sensor. The projected spectrum, which is the least-square error reconstruction of the scene vectors, contains the useful information for image processing. Spectral sensors with arbitrary spectral response functions are can be analyzed with this model. The framework leads directly to an image pre-processing algorithm to remove the data correlation between bands. Further discussion shows that this model can also serve the purpose of sensor evaluation, and thus facilitates comparison between different sensors. The spectral shapes and the Signal-to-Noise Ratios (SNR) of different bands are seen to influence the sensor's imaging ability in different manners, which are discussed in detail. With the newly defined SNR in spectral space, we can quantitatively characterize the photodetector noise of a spectral sensor with overlapping bands. The idea of adaptive imaging with QDIP based sensor is proposed and illustrated.

High signal-to-noise ratio (SNR) is typically required for higher resolution and faster speed in magnetic resonance imaging (MRI). Planar microcoils as receiver probes in MRI systems offer the potential to be configured into array elements for fast imaging as well as to enable the imaging of extremely small objects. Microcoils, however, are thermal noise dominant and suffer limited SNR. Cryo-cooling for the microcoils can reduce the thermal noise, however conventional cryostats are not optimum for the microcoils because they typically use a thick vacuum gap to keep samples to be imaged to near room temperature during cryo-cooling. This vacuum gap is typically larger than the most sensitive region of the microcoils that defines the imaging depth, which is approximately the same as the diameters of the microcoils. Here microfluidic technology is utilized to locally cryo-cool the microcoils and minimize the thermal isolation gap so that the imaging surface is within the imaging depth of the microcoils. The first system consists of a planar microcoil with microfluidically cryo-cooling channels, a thin N2 gap and an imaging. The microcoil was locally cryo-cooled while maintaining the sample above 8°C. MR images using a 4.7 Tesla MRI system shows an average SNR enhancement of 1.47 fold. Second, the system has been further developed into a cryo-cooled microcoil system with inductive coupling to cryo-cool both the microcoil and the on-chip microfabricated resonating capacitor to further improve the Q improvement. Here inductive coupling was used to eliminate the physical connection between the microcoil and the tuning network so that a single cryocooling microfluidic channel could enclose both the microcoil and the capacitor with minimum loss in cooling capacity. Q improvement was 2.6 fold compared to a conventional microcoil with high-Q varactors and transmission line connection. Microfluidically tunable capacitors with the 653% tunability and Q of 1.3 fold higher compared to a conventional varactor have been developed and demonstrated as matching/tuning networks as a proof of concept. These developed microfluidically cryo-cooling system and tunable capacitors for improving SNR will potentially allow MR microcoils to have high-resolution images over small samples.

Three novel approaches that are based on a recent communication technique called time compression overlap-add (TC-OLA), are introduced into pulse compression (PC) radar systems to improve the radar waveform shaping and enhance radar performance. The first approach lays down a powerful framework for combining the TC-OLA technique into traditional PC radar system. The new TC-OLA-based radar obtained is compared with other radars, namely traditional linear frequency modulation (LFM), and wideband LFM which has the same processing gain under different background situations. The results show the superiority of the proposed radar over the others. The second approach combines a random phase noise signal with a selected radar signal to build a new radar system, SSLFM radar, that enjoys the low-probability of intercept property, and, therefore, has higher immunity against noise jamming techniques compared with other radar systems. The properly recovery of the transmitted signal, however, requires a synchronization system at the receiver side. In this dissertation, we propose three synchronization systems each having different pros and cons. The last approach takes the radar waveform design methodology in a different direction and proposes a novel framework to combine any number of radar signal and transmit them simultaneously. Instead of trying to achieve universality through waveform shaping optimization, we do so via pluralism. As a proof of concept, all the proposed radars have been implemented and tested on software-defined radar (SDR). The theoretical and the experimental results showed the superiority of all proposed radar systems. Since TC-OLA is fundamental to this work, we add a chapter to propose a new technique called downsample upsample shift add (DUSA) to address the limitations of the existing implementation of TC-OLA. / Graduate

Orientador: Plínio Almeida Barbosa / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Estudos da Linguagem / Made available in DSpace on 2018-08-25T03:48:52Z (GMT). No. of bitstreams: 1 Constantini_AnaCarolina_D.pdf: 2193643 bytes, checksum: c28fc92dc576ce19800b7b9ebea2f365 (MD5) Previous issue date: 2014 / Resumo: A prosódia é uma informação fônica que está além do nível do segmento, e é usualmente estudada a partir da análise de três parâmetros fonético-acústicos clássicos: frequência fundamental, intensidade e duração. Embora estudada para muitas finalidades, a prosódia geralmente não é a primeira opção de investigação quando se busca conhecer mais sobre diferenças entre variedades de uma mesma língua, por exemplo. Desta forma, o presente trabalho pretende preencher essa lacuna no que diz respeito aos estudos prosódicos para caracterizar e diferenciar variedades faladas no Brasil. O objetivo desta tese de Doutorado foi estudar parâmetros prosódicos que pudessem caracterizar e posteriormente diferenciar sujeitos de diferentes variedades faladas do português brasileiro. Em um segundo momento, ruído aditivo foi incluído nas mesmas amostras de fala utilizadas para caracterizar a prosódia de diferentes variedades do português brasileiro, com o objetivo de entender melhor como os parâmetros prosódicos se comportam quando há inclusão de ruído nas amostras de fala, situação muito comum na área da Fonética Forense. O objetivo secundário da pesquisa foi aplicar testes perceptivos a ouvintes do português brasileiro com a finalidade de saber se eles seriam capazes de reconhecer e categorizar a origem dos falantes de acordo com suas falas. Analisamos amostras de fala espontânea de 35 sujeitos, do sexo masculino, de sete regiões brasileiras: São Paulo, Minas Gerais, Rio de Janeiro, Paraná, Distrito Federal, Região Nordeste e Região Norte. Todas as amostras de fala foram segmentadas em unidades Vogal-Vogal (unidade VV), unidades do tamanho da sílaba que compreendem um segmento que vai do início de uma vogal até o início da vogal imediatamente seguinte, incluindo as consoantes entre elas. O script BeatExtractor foi utilizado para este fim. Posteriormente, outro script (ProsodicDescriptorExtractor) foi executado para extrair oito medidas prosódico-acústicas das amostras de fala: taxa de elocução (unidades VV/s), média de z-score suavizado de duração de unidade VV, desvio-padrão de z-score suavizado de duração de unidade VV, assimetria de z-score suavizado de duração de unidade VV, taxa de proeminência (picos de z-score/s), mediana de frequência fundamental, ênfase espectral e taxa de unidades VV não proeminentes por segundo. Após a análise estatística, os resultados mostraram que cinco dos oito parâmetros conseguiram identificar ao menos uma variedade estudada e assim, diferenciá-la de outras. A mediana de F0 e a ênfase espectral foram capazes de criar dois grandes grupos que separaram DF e Região Norte de todas as outras variedades (exceto pela não diferenciação de DF e Paraná), mostrando que DF e Norte possuem valores maiores de ênfase espectral, bem como têm valores de F0 maiores que os falantes de outras variedades. Assimetria de z-score suavizado e taxa de unidades VV não proeminentes/s foram os parâmetros que colocaram DF e Norte em grupos diferentes. O desvio-padrão de z-score apontou para uma diferença entre dialetos falados na região Norte do Brasil e da Região Sul: a região Norte se diferenciou de SP, DF e Nordeste e SP, que, por sua vez, se diferenciou do PR. Concluímos, portanto, que os parâmetros prosódicos podem revelar características próprias de variedades faladas no Brasil. A análise das amostras de fala em diferentes relações sinal-ruído mostrou que mediana de F0 e ênfase espectral são os parâmetros que sofrem maior perturbação quando a relação sinal-ruído é baixa, sendo que os valores de ênfase espectral chegaram a sofrer mudanças de 154% em relação a seus valores originais. O resultado mostrou que a análise da estrutura rítmica é a mais robusta quando há presença de ruído nas amostras de fala. Por fim, os testes perceptivos foram aplicados em 20 falantes do português brasileiro e a variedade mais reconhecida foi a variedade falada no Rio de Janeiro, que chegou a apresentar 90% de acerto, seguida pela variedade falada no Nordeste do Brasil. Constatamos que a proximidade da região de origem dos ouvintes com a região da variedade presente no teste facilita a identificação correta da variedade / Abstract: Prosody is usually studied by means of three classic parameters: fundamental frequency, intensity and duration. As for as dialectology is concerned, prosody has not been the main focus of the research on different dialects. Our goal is to characterize and differentiate Brazilian Portuguese varieties using prosodic parameters. In order to do that, we analyzed the recordings of spontaneous speech from 35 male subjects from seven different Brazilian regions: São Paulo (SP), Minas Gerais (MG), Rio de Janeiro (RJ), Paraná (PR), Distrito Federal (DF), Northeast (NE) and North (N). The speech samples were segmented in Vowel-to-Vowel units (VV units) using the BeatExtractor script. Later, the ProsodicDescriptorExtractor script was used to extract eight prosodic measures which are: speech rate (VV units/s), mean, standard deviation and skewness of the normalized z-score, prominence rate (peaks of z-score/s), median of fundamental frequency, spectral emphasis and rate of non prominent VV units/s. The statistical analysis revealed that five prosodic parameters were able to identify at least one variety and then differentiate it from the others. Fundamental frequency median and spectral emphasis created two groups which separated N and DF (DF is located at West-Central region, near North region) from all the other varieties, considering that N and DF were characterized by high values of these two parameters. On the other hand, skewness of z-score and rate of non prominent VV units/s set DF and N in different groups. Standard deviation of z-score pointed to differences between North varieties and South varieties. We concluded that prosodic parameters can be useful to differentiate Brazilian Portuguese varieties. Another goal of the current study was to analyze the spontaneous speech 'recordings in distinct signal-to-noise ratios. The analysis has shown that Gaussian, additive noise modifies the values for median of F0 and spectral emphasis (the least has changed 154% related to the original values). The results revealed that the rhythmic organization of the speech chain is more indicated to the analysis of acoustic parameters in the presence of noise. Finally, 20 listeners were recruited to answer a perceptual test (free classification test) about the different varieties spoken in Brazil (we used the same spontaneous speech recordings to run the perceptual test). Rio de Janeiro was the most recognized variety, which presented 90% of correct answers, followed by the NE variety. The closeness of the listeners¿ own origin to the regions of the spoken varieties contributed to correct identifications / Doutorado / Linguistica / Doutora em Linguística

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The main objective of this work was evaluating the possibility of using the Acoustic Doppler Velocimeter (ADV) to quantify the suspended sediment concentration (SSC). For this purpose, a laboratory experiment was developed, where a controlled environment was sought to test the ADV response for tests conducted in samples with known characteristics. Eight concentrations and five particles sizes of five types from soil types of three cities were used in the test. An experimental apparatus was built in order to obtain data in homogeneous water and soil samples utilizing the Sontek Horizon ADV software. Samples were collected in six different positions, 6cm, 12cm and 18cm from the bottom of the vessel, totalizing more than 600 sampling. The software Win ADV was utilized to visualize the data and the post processing, applying the PSTM filter to eliminate data that were affected by noise effects, maintaining a large percentage of data. The collected data showed an increase of SNR compared to the increase of SSC for the different soil types for the five particle sizes, wherein the best correlations between echo and SSC occurred for the tests with soils 2,3 and 4. By the measurements with ADV in laboratory, was possible to investigate the relation signal/noise for different particle sizes and SSC of soil when soil is suspended in water. It was noted that the found SNR values did not follow a pattern in relation to soil particle size. In other words, it cannot be concluded that the increase of particle size results in increase of SNR, whereas the SNR values found were larger for some particle sizes in some concentrations and smaller in others. In relation to SSC, it is easy to note that, in general, the higher the concentration of sediments, higher is the found SNR value. This result meets with what have been seen in the literature. / Este trabalho teve como objetivo principal avaliar a possibilidade do uso do Velocímetro Acústico Doppler (ADV) para quantificar a concentração de sedimento em suspensão (CSS). Para isso foi desenvolvido um experimento em laboratório, onde se buscou em um ambiente controlado, testar a resposta do ADV para testes conduzidos em amostras de características conhecidas. Foram utilizadas oito concentrações e cinco faixas granulométricas de cinco tipos de solo de três cidades nos ensaios. Foi construído um aparato experimental, a fim de obter dados em amostras homogêneas de água e solo utilizando o programa Sontek Horizon ADV. Coletou-se as amostras em diferentes posições a 6 cm, 12 cm e a 18 cm do fundo do recipiente, totalizando mais de 600 ensaios. Para visualização dos dados e pós processamento utilizou-se o programa Win ADV aplicando o filtro (PSTM) a fim de eliminar os dados que foram afetados por algum efeito de ruído, mantendo um grande percentual de dados. Os dados coletados mostraram o aumento do SNR em relação ao aumento da CSS para os diferentes tipos de solos para as cinco granulometrias, sendo que as melhores correlações entre o eco e a CSS ocorreram para os ensaios com os solos 2, 3 e 4. Através das medições com o ADV em laboratório, foi possível investigar a relação sinal/ruído para diferentes faixas granulométricas e CSS de solo quando em suspensão em água. Notou-se que os valores encontrados para o SNR não seguiram uma regra determinada em relação à faixa granulométrica do solo. Ou seja, não se pode concluir que o aumento da faixa granulométrica indica o aumento do SNR, já que os valores de SNR encontrados foram maiores para algumas granulometrias em algumas concentrações e menores em outras concentrações. Já no que diz respeito às diferentes CSS, em geral, quanto maior a concentração de sedimentos, maior é o valor de SNR encontrado. Esse resultado vem ao encontro com o que tem sido visto na literatura.

This study examines the efficacy of presenting footnotes information in alternative display formats on investors’ judgments and decisions. Non-professional investors play a significant role in the capital markets yet they do not always attend to information contained in footnote disclosures. As a result, nonprofessional investors systematically misprice firms and misallocate resources. Recognizing that increased mandatory and voluntary disclosures create additional challenges for non-professional investors, both the FASB and SEC have actively sought ways to increase the effectiveness of disclosures. I hypothesize that high display proximity, low signal-to-noise presentation formats can increase investors’ attention to and processing of footnote disclosures and hence performance on an investing task. Further I hypothesize that low display proximity, low signal-to-noise presentation formats can improve investor performance on a recognition task. Lastly, I hypothesize that non-professional investors viewing high display proximity, low signal-to-noise footnote disclosures will rate usability higher than nonprofessional investors viewing footnote disclosures in the other three display formats. Amazon Mechanical Turk workers are used as participants in a 2 x 2 between-participants experiment using two task types: an integrative (investing) task and a non-integrative (recognition) task. I manipulate display proximity (inline or side-by-side) and signal-to-noise ratio (footnotes presented simultaneously or individually). Contrary to my hypotheses, I find that low signal-to-noise ratio increases non-professional investors’ performance on both the integrative (investing) and non-integrative (recognition) tasks. Further, although task performance increased under the low signal-to-noise presentation format, participants did not evaluate either signal-to-noise presentation format easier to use or more useful. Instead, participants found the high display proximity (side-by-side) presentation format easier to use, although it did not yield performance increases.

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Background: Since the 1940s, measures of pure-tone sensitivity and speech recognition in quiet have been vital components of the audiologic evaluation. Although early investigators urged that speech recognition in noise also should be a component of the audiologic evaluation, only recently has this suggestion started to become a reality. This report focuses on the Words-in-Noise (WIN) Test, which evaluates word recognition in multitalker babble at seven signal-to-noise ratios and uses the 50% correct point (in dB SNR) calculated with the Spearman-Kärber equation as the primary metric. The WIN was developed and validated in a series of 12 laboratory studies. The current study examined the effectiveness of the WIN materials for measuring the word-recognition performance of patients in a typical clinical setting. Purpose: To examine the relations among three audiometric measures including pure-tone thresholds, word-recognition performances in quiet, and word-recognition performances in multitalker babble for veterans seeking remediation for their hearing loss. Research Design: Retrospective, descriptive. Study Sample: The participants were 3430 veterans who for the most part were evaluated consecutively in the Audiology Clinic at the VA Medical Center, Mountain Home, Tennessee. The mean age was 62.3 yr (SD = 12.8 yr). Data Collection and Analysis: The data were collected in the course of a 60 min routine audiologic evaluation. A history, otoscopy, and aural-acoustic immittance measures also were included in the clinic protocol but were not evaluated in this report. Results: Overall, the 1000-8000 Hz thresholds were significantly lower (better) in the right ear (RE) than in the left ear (LE). There was a direct relation between age and the pure-tone thresholds, with greater change across age in the high frequencies than in the low frequencies. Notched audiograms at 4000 Hz were observed in at least one ear in 41% of the participants with more unilateral than bilateral notches. Normal pure-tone thresholds (≤20 dB HL) were obtained from 6% of the participants. Maximum performance on the Northwestern University Auditory Test No. 6 (NU-6) in quiet was ≥90% correct by 50% of the participants, with an additional 20% performing at ≥80% correct; the RE performed 1-3% better than the LE. Of the 3291 who completed the WIN on both ears, only 7% exhibited normal performance (50% correct point of ≤6 dB SNR). Overall, WIN performance was significantly better in the RE (mean = 13.3 dB SNR) than in the LE (mean = 13.8 dB SNR). Recognition performance on both the NU-6 and the WIN decreased as a function of both pure-tone hearing loss and age. There was a stronger relation between the high-frequency pure-tone average (1000, 2000, and 4000 Hz) and the WIN than between the pure-tone average (500, 1000, and 2000 Hz) and the WIN. Conclusions: The results on the WIN from both the previous laboratory studies and the current clinical study indicate that the WIN is an appropriate clinic instrument to assess word-recognition performance in background noise. Recognition performance on a speech-in-quiet task does not predict performance on a speech-in-noise task, as the two tasks reflect different domains of auditory function. Experience with the WIN indicates that word-in-noise tasks should be considered the "stress test" for auditory function.

Wireless communications have become an essential part of our daily life. Despite the fact that wireless networks are simple to set up and deploy, the channel conditionsin wireless networks are susceptible to fading and attenuation, thereby reducing the transmission efficiency and reliability. The influence of unstable wireless channels, fading and attenuation is a significant limitation of wireless networks. The persistent and exponential increase in the usage of wireless communication services demands for enhanced reliability, transmission range and efficiency. This can be achieved byexploring and proposing different propagation techniques and models. This thesis evaluates a network model which makes use of an adaptive modulation coding scheme in the presence of an Amplify-and-Forward relaying environment. We deploy adaptive modulation technique in combination with Amplify-and-Forward relaying transmission mechanism to select the best suitable transmission path and obtain better transmission efficiency for a wireless communication system. The network model thus designed comprises of two links, one considering the relay transmission path that travels from the source-to-relay-to-destination, and the other link considering the direct transmission path traveling from the source to the destination, while both the links undergo Nakagami-m fading. In addition, the system ensures better performance in different conditions by making use of adaptive modulation and coding scheme and deploying distinct modulation and coding schemes based on the condition of the communication channel. The performance of this system model is analysed through mathematical analysis and the results are validated and depicted through simulation in MATLAB under different conditions. We have thereby derived the closed-form expressions for the Signal to Noise Ratio (SNR), Outage Probability, and the Packet Error Rate (PER) for the considered network model in the Nakagami-m fading environment. Different fading parameters that affect the system performance are considered and varied while obtaining the required results through MATLAB simulations. The system model proposed significantly reduces the outage probability and packet error rate and aids in achieving better system performance and reliability.

This dissertation presents research on the fabrication of optofluidic sensor platforms, which consist of integrated hollow waveguides and solid waveguides. Antiresonant reflecting optical waveguides (ARROWs) filled with liquids or gases, can be used for high-sensitivity sensing in applications of biotechnology, chemical synthesis, and analytical chemistry. The fabrication method developed for integrated ARROW sensing platforms utilizes standard microfabrication processes and materials. Dielectric cladding layers are deposited on a silicon wafer using plasma-enhanced chemical vapor deposition (PECVD) or sputtering. A sacrificial material is then patterned over the bottom cladding layers by photolithography. Additional dielectric layers are deposited around the core, forming the structure of the waveguides. Integrated solid-core waveguides can be easily created by etching a ridge into the topmost dielectric cladding layer. The hollow core waveguides are then formed by wet etching the sacrificial core material. The coupling efficiency between solid core and hollow core waveguides is extremely important for the platform's overall sensitivity. Efficiencies can be enhanced from 18% to 67% by adjusting the thickness of the thick top oxide. Experimental results prove that optical throughput was improved by 17.1× with this improved interface transmission. Sputtered films were investigated as an alternative to for producing cladding layers. The experimental results reveal that sputtered layers show poor adhesion and mechanical strength which make them unreliable for hollow waveguides with small dimension. High-sensitivity ARROW platforms were obtained by employing hybrid layers (PECVD SiO2 and sputtered Ta2O5) as claddings and building waveguides on self-aligned pedestals. The photolumiscence background was only 1/10 that of previous devices made with SiO2/SiN and the average signal-to-noise ratio was improved by 12×.