Tesi: "Signal loss"

1

Palekar, Trishul Ajit. "Signal optimization at isolated intersections using pre-signals". Texas A&M University, 2006. http://hdl.handle.net/1969.1/4279.

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This research proposes a new signal operation strategy aimed at efficient utilization of green time by cutting down on the start up and response loss times. The idea is to have a "pre-signal" on each main approach a few hundred feet upstream of the intersection in addition to the main intersection signal, which is coordinated with the pre-signal. The offset between the main and pre-signal ensures that the majority of start up losses does not occur at the main signal. The benefits of the system under various traffic conditions were evaluated based on analysis of the queue discharge process and Corridor Simulation (CORSIM) study. The proposed measure should reduce the travel time and total control delay for the signalized network. To attain the objective the following two studies were undertaken: 1. Development of a queue discharge model to investigate the expected benefits of the system. 2. Simulation of the system: In the second part of the research, the proposed strategy was tested using CORSIM to evaluate its performance vis-ÃÂ -vis the baseline case. The queue discharge model (QDM) was found to be linear in nature in contrast to prior expectations. The model was used to quantify the benefits obtained from the pre-signal system. The result of this analysis indicated that the proposed strategy would yield significant travel time savings and reductions in total control delay. In addition to the QDM analysis, CORSIM simulations were used to code various hypothetical scenarios to test the concept under various constraints and limitations. As per expectations, it was found that the system was beneficial for high demand levels and longer offsets. The upper limit on offsets was determined by visual observation of platoon dispersion and therefore the maximum offset distance was restricted to 450 feet. For scenarios where split phasing was used, the break even point in terms of demand level was found to be 2500 vph on a three lane approach, whereas that for a lag-lag type of phasing strategy was found to be 1800 vph, also on a three lane approach.

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2

Kurtoglu, Levent. "Analysis of loss for inductive strips in finline". Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA239947.

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Thesis (M.S. in System Engineering)--Naval Postgraduate School, September 1990.
Thesis Advisor(s): Knorr, Jeffrey B. Second Reader: Janaswamy, R. "September 1990." Description based on title screen as viewed on March 18, 2010. DTIC Identifier(s): Finlines, Inductive Strips, Ohmic Losses. Author(s) subject terms: Finline, Inductive Strip, Finline Discontinuity, Ohmic Losses. Includes bibliographical references (p. 61). Also available in print.

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3

Dumenil, Arnaud. "Polarization dependent loss in next-generation optical networks : challenges and solutions". Electronic Thesis or Diss., Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAS006.

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La demande de débit en augmentation constante requiert des canaux de communication fiables et robustes. Les réseaux optiques terrestres ainsi que les liens sous-marins représentent le cœur de l'infrastructure des télécommunications au niveau mondial, et transportent des centaines de canaux fréquentiels modulés à haut débit. Ces liens se composent non seulement de kilomètres de fibre mais aussi de composants optiques comme les amplificateurs à fibre dopée à l'erbium (EDFA) pour relever régulièrement la puissance des signaux atténués, ou encore des commutateurs sélectifs en longueur d'onde (WSS) qui routent le signal vers leur destination. Dans cette thèse, nous nous intéressons à une pénalité spécifique qui survient dans ces systèmes et qui réduit le débit d'information dans une propagation optique. Les composants optiques discrets présentent typiquement une anisotropie en polarisation : un déséquilibre de perte (ou gain) apparaît entre les deux polarisations d'un signal optique multiplexé en polarisation. Cet effet non unitaire appelé pertes dépendant de la polarisation (abrégé PDL en anglais) dégrade la qualité de transmission dans les systèmes optiques actuels et futurs.Dans le cadre des transmissions multiplexés en polarisation, nous caractérisons la perte de capacité induite par la PDL. Pour commencer, des modèles de canal sont attentivement étudiés et deux approches sont présentées : un canal avec des éléments PDL distribués avec un bruit également distribué, ou alors un canal équivalent simplifié en un seul élément. Nous analysons les limites fondamentales de communication associées à ces modèles. Nous montrons en outre que la capacité d'un canal PDL dépend en pratique de l'orientation de l'état de polarisation du signal incident. Nous passons ensuite en revue l'état de l'art de schémas de modulation atténuant l'effet de PDL puis nous proposons deux nouveaux schémas de modulation multi-dimensionnels qui augmentent la performance minimum et moyenne du canal. Ces deux modulations sont des transformations unitaires de symboles M-QAM qui n'utilisent pas de degrés de liberté autres que les quatre déjà utilisés pour chaque longueur d'onde (encodage en phase et quadrature de phase sur les deux états de polarisation). Nous proposons succinctement une extension de ces premiers résultats à des communications optiques plus généralement multiplexés en dimension spatiale et impactées par des pertes dépendantes de mode, qui présentent un déséquilibre de gain identique. Au-delà de la construction de modulations au niveau du transmetteur, nous étudions la perte de performance en présence de PDL d'une chaîne de traitement de signal conventionnelle et séquentielle par comparaison avec une égalisation et décodage joint. Cette perte additionnelle de capacité résultant du traitement séquentiel non optimal est évaluée pour différents formats de modulations ainsi que différents points de fonctionnement. Enfin, nous exposons une validation expérimentale des deux schémas de modulation proposés, aussi bien sur un élément de PDL seul ou sur un canal PDL distribué, et montrons comme attendu une robustesse augmentée vis-à-vis de la PDL
Large amounts of ever-increasing global data traffic require sound and reliable communication channels. Optical terrestrial networks and submarine links are at the very heart of the global telecom infrastructure, and carry hundreds of frequency channels modulated at very high rates. These links include not only kilometers of fiber but also optical elements such as Erbium-Doped Fiber-Amplifiers (EDFA) to amplify periodically the attenuated signals and Wavelength Selective Switches (WSS) to route the signals to their assigned destinations. In this thesis, we explore a specific rate-degrading impairment of the optical propagation that raises in those systems. Discrete optical elements often exhibit a polarization anisotropy that emerges as a gain or loss imbalance between the two polarization tributaries of the polarization-multiplexed optical signals. This non-unitary effect called Polarization Dependent Loss (PDL) impairs the quality of transmission in current and next-generation optical systems.In the context of polarization-multiplexed signals, we assess the capacity loss induced by PDL. First, channel models are carefully studied and two approaches are described: a channel with distributed PDL elements and distributed noise or a simplified single-element equivalent channel. Making use of these models, we then analyze their fundamental limits of communications. We show that the PDL channel capacity depends in practice on the state-of-polarization orientation of the incident signal. We then review the state-of-the art of PDL-mitigating modulation schemes and propose two new multi-dimensional signaling schemes that enhance worst-case and average performance. These two modulations are unitary transforms of M-QAM symbols and do not make use of additional degrees of freedom apart from the four already-used dimensions per wavelength (in-phase and quadrature channels of two polarization states). We briefly extend these first results to space-division-multiplexed optical communications impaired by mode dependent loss (MDL) that present a similar gain imbalance. Beyond signal shaping at the transmitter side, we study the performance loss of a conventional, sequential signal processing chain at the receiver side in presence of PDL, in comparison with a joint equalization-decoding scheme. The additional capacity loss due to the mismatch sequential processing is evaluated for several modulation formats and at different operating points. Finally, we report an experimental validation of the two proposed signaling schemes, both on a single PDL element and on a distributed PDL channel, demonstrating the predicted enhanced robustness to PDL

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4

Pokorný, Rostislav. "Návrh programovatelného útlumového členu". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413091.

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This Master´s thesis focuses on design and implementation of programmable attenuator. The main aim of this thesis is to create an electronical device that provide continuous setting of attenuation value in the range between 0–150 dB. Setting a value from the range can be performed using buttons and set values are shown on display. For this thesis an attenuator with working frequency between 0–6 GHz was chosen and four–layer printed circuit board was designed. As a result the device is fitted with an 8bit microcontroller ATmega328P–PU using five 6bit digital attenuators connected in series with manual and program settings of attenuation from 0–157,5 dB with step of 0,5 dB. Data are shown on a build–in display. The application for remote settings and value reading over integrated USB (Universal Serial Bus) interface, was created in C#. In conclusion of this thesis there is a measurement evaluation of attenuation measurement performed on the device.

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5

Pidaparthi, Sahitya. "AN ASSESSMENT OF THE ACCURACY OF MAGENTIC RESONANCE PHASE VELOCITY MAPPING IN TURBULENT FLOW THROUGH ORIFICES". Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1297396841.

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6

Stephens, Richard Brian Leonard. "A study and modelling of the propagation effects of vegetation on radio waves at centimetre-wavelength frequencies". Thesis, University of South Wales, 1998. https://pure.southwales.ac.uk/en/studentthesis/a-study-and-modelling-of-the-propagation-effects-of-vegetation-on-radio-waves-at-centimetrewavelength-frequencies(48d8248f-a287-45e4-96e5-fe8d8e56efae).html.

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With the increase in and more diverse applications of microwave radio communications, the probability of a signal propagating through a medium of vegetation is increased. As a direct result of this demand for microwave communication systems, knowledge is required of the effects of vegetation media on the propagating microwave signal. This enables radio system planners to predict the signal loss more accurately, necessitating a detailed study of the propagation effects of vegetation. A vegetation depth attenuation model has been developed based on the International Telecommunications Union-Radio Sector model and validated against measurements conducted at two microwave frequencies of 11.2 GHz and 20 GHz. The measurements were conducted on a number of sites of differing geometries at different times of the year to obtain the two extreme states of foliage, in- and out-of-leaf. The trees found at the sites were of a number of indigenous species. A variety of species and environments were employed for the outdoor measurements as it was felt that any variation in the signal, occurring as a direct result of the species, climate, environment etc., would be reduced. A further study has been conducted in an anechoic chamber, the purpose being to investigate the depolarising effect of vegetation, to characterise and to ascertain how and to what extent the polarisation of the incident signal is changed as it passes through the vegetation without the effects of climate, location and environment affecting the resultant signal. To enable larger quantities of data to be obtained, collated and subsequently analysed and also to remove any scope for error during the collection of results, two data acquisition programs were written for the two main environments in which the measurements were to be undertaken, that is to say, outdoor and indoor (anechoic chamber) environments. In seeking to provide a model for the prediction of attenuation a radio wave will suffer as it is propagated through a body of vegetation, several models have been examined in turn and their relative merits discussed together with their applicability to the study. After examining the possible models available, the thesis provides a model which enables the prediction of additional attenuation a radiowave signal will suffer as a function of path length (depth) of the vegetation medium and frequency. The model can be recommended for use in the 10-30 GHz band. The study on the depolarisation of signals by vegetation has shown that the components of a vegetation medium e.g. tree trunks, branches and leaves, can cause considerable changes in the polarisation of the incident signal as it propagates through a volume of vegetation. The work presented in this thesis contains new measured results of the polarisation state of the radio wave as it emerges from a vegetation specimen. These results obtained in an anechoic chamber under controlled conditions have demonstrated that additional effects, other than attenuation by absorption and scatter need to be considered in order to characterise and subsequently model the overall effect of vegetation in the radio path of propagating signals.

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7

Curran, Brian [Verfasser], e Herbert [Akademischer Betreuer] Reichl. "Loss Modeling in Non-Ideal Transmission Lines for Optimal Signal Integrity / Brian Curran. Betreuer: Herbert Reichl". Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2012. http://d-nb.info/1024771911/34.

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8

LINARES, LUIS CARLOS BLANCO. "STUDY OF SIGNAL DISTORTION IN ANALOGICAL OPTICAL SYSTEMS: FOR COMBINED EFFECTS OF POLARIZATION MODE DISPERSION AND POLARIZATION DEPENDENT LOSS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7426@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
Neste trabalho é apresentado um estudo do formalismo matemático para a teoria da polarização da luz, da dispersão dos modos de polarização e das perdas dependentes da polarização e de seus efeitos combinados. Medidas experimentais para caracterização dos parâmetros dos dispositivos que compõe a montagem experimental são apresentados, sendo aqui abordadas as técnicas de medida utilizadas. Um novo modelamento teórico para os efeitos combinados da dispersão dos modos de polarização e das perdas dependentes da polarização em sistemas ópticos analógicos é apresentado. Curvas teóricas e experimentais de distorção harmônica em função dos vários parâmetros envolvidos no modelamento comprovam a natureza interferométrica dos fenômenos avaliados. Medidas experimentais comprovam o correto modelamento teórico e demonstram que o modelamento matemático apresentado em [6], não contempla corretamente os fenômenos envolvidos.
In this work is presented a study of mathematical formalism to polarization of light thory, of polarization mode dispersion and polarization dependent loss and of this effects combined. Experimental measurements to characterize the devices of experimental set-up are presented, and the measure technique are mentioned here. A new theorical model to combined effects of polarization mode dispersion and polarization dependent loss is presented. Theorical and experimental curves of hamonic distortion in function of many parameters involved in theorical model prove the interferometric nature of phenomenon. Experimental measurement demonstrate a perfect agreement with modeling developed and prove differences of 5 dB with modeling presented in [6].

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9

Chhabra, Manish. "Source Characterization using an Experimental Method and Prediction of Insertion of the Exhaust System". University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin154399673454236.

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10

Dybäck, Matilda, e Johanna Wallgren. "Pupil dilation as an indicator for auditory signal detection : Towards an objective hearing test based on eye tracking". Thesis, KTH, Skolan för teknik och hälsa (STH), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-192703.

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An early detection of hearing loss in children is important for the child's speech and language development. For children between 3-6 months, a reliable method to measure hearing and determine hearing thresholds is missing. A hearing test based on the pupillary response to auditory signal detection as measured by eye tracking is based on an automatic physiological response. This hearing test could be used instead of the objective hearing tests used today. The presence of pupillary response has been shown in response to speech, but it is unstudied in response to sinus tones. The objective of this thesis was to study whether there is a consistent pupillary response to different sinus tone frequencies commonly used in hearing tests and if yes, to determine reliably the time window of this response. Four different tests were done. The adult pupillary response in regard to sinus tone stimuli with four frequency levels (500 Hz, 1000 Hz, 2000 Hz and 4000 Hz), and four loudness levels (silence, 30 dB, 50 dB and 70 dB) was tested (N=20, 15 females, 5 males). Different brightness levels and distractions on the eye tracking screen were investigated in three substudies (N=5, 4 females, 1 male). Differences between silence and loudness levels within frequency levels were tested for statistical significance. A pupillary response in regard to sinus tones occurred consistently between 300 ms and 2000 ms with individual variation, i.e. earlier than for speech sounds. Differences between silence and loudness levels were only statistically significant for 4000 Hz. No statistical difference was shown between different brightness levels or if there were distractions present on the eye tracker screen. The conclusion is that pupillary response to pure sinus tones in adults is a possible measure of hearing threshold for at least 4000 Hz. Larger studies are needed to confirm this, and also to more thoroughly investigate the other frequencies.
En tidig upptäckt av hörselnedsättning hos barn är viktig för barnets tal- och språkutveckling. För barn mellan 3-6 månader saknas det en tillförlitlig metod för att mäta hörsel och bestämma hörtrösklar. Ett hörseltest baserad på pupillreaktion på ljud som mäts med en eye tracker bygger på en automatisk fysiologisk reaktion och skulle kunna användas istället för de objektiva test som används idag. Hitintills har pupillreaktion på tal påvisats, men det saknas studier som studerat eventuella reaktioner på sinustoner. Syftet med denna uppsats var att undersöka om det finns en enhetlig pupillreaktion på de olika frekvenserna av sinustoner som vanligen används i hörseltest. Vidare var studiens syfte att fastställa ett tillförlitligt tidsfönster för pupillreaktion. Fyra olika typer av tester utfördes. Pupillreaktionen mot sinustoner med fyra olika frekvensnivåer (500 Hz, 1000 Hz, 2000 Hz och 4000 Hz), och fyra olika ljudnivåer (tystnad, 30 dB, 50 dB och 70 dB) undersöktes i ett test på vuxna deltagare (N=20, 15 kvinnor, 5 män). Olika ljusnivåer och distraktioner på eye tracker-skärmen undersöktes i tre test (N=5, 4 kvinnor, 1 man). Skillnaderna mellan ljudnivåer och frekvensnivåer testades med statistiska tester. Resultaten visade att pupillreaktion på sinustoner inträffade konsekvent mellan 300 ms och 2000 ms med individuella variationer. Denna reaktionstid inträffar tidigare än för taljud. En statistisk signifikant skillnad mellan tystnad och olika ljudnivåer kunde endast ses för frekvensnivån 4000 Hz. Ingen statistisk skillnad uppmättes mellan olika ljudnivåer eller om det fanns distraktioner på eye tracker-skärmen. De i studien framkomna resultaten tyder på att pupillreaktioner mot rena sinustoner hos vuxna är en möjlig metod för att identifiera hörseltrösklar för åtminstone 4000 Hz. Större studier behöver göras för att fastställa detta och en noggrannare undersökning behöver genomföras för de andra frekvenserna.

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11

Bayram, Ahmet. "A Study of Indoor Ultra-wideband Propagation Measurement and Characterization". Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/32748.

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Ultra-wideband (UWB) communication is emerging as a new wireless technology, which promises high data rates with low interference and low power consumption. The development of such UWB systems requires a sufficiently large amount of data to characterize the propagation behavior of UWB signals in indoor environments and develop accurate channel models. This thesis focuses primarily on a frequency-domain approach for propagation measurements and characterization of indoor UWB channels. This approach is based on measurements of the amplitude using a scalar network analyzer and retrieval of the phase from the amplitude data using a Hilbert transform relationship.

Extensive propagation data are collected in a frequency range of 1 to 12 GHz in two buildings on Virginia Tech campus. Using the data, channel characterization results are obtained and compared to those based on time-domain measurements. Some statistical results for small-scale fading, path loss exponent, and signal quality are presented. This comparison validates the accuracy of measured results for the UWB measurement campaign. The measured data also reaffirms the immunity of UWB propagation to small-scale fading which is present in narrowband wireless communication systems.

In addition to channel propagation measurements, signal distortions in UWB links, due to bandwidth limitations of antenna characteristics as well as the dispersive behavior of building materials, are also examined. In particular, the distortion of radiated signals by TEM horn antennas along off-boresight directions are studied experimentally. Furthermore, pulse distortions resulting from propagation through dispersive walls are demonstrated by simulation. The roles of receive-transmit antennas in a UWB link are examined, and the requirements for gain, input impedance, polarization, and phase of the radiated signal necessary for minimization of signal distortions are pointed out.
Master of Science

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12

Rakk, Adrian. "Automatically measuring the resistive loss of a transformer : A project in cooperation with Alstom Power Sweden". Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-10791.

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In order to develop more economical and ecologically friendly transformers it is necessary to know the losses throughout the product development process. There are several losses related to transformers, but in this particular case the focus will be on the resistive loss of the transformer. In order to measure this loss first the resonant frequency of the transformer is determined. Since at resonance the secondary side of the transformer is considered to be purely resistive. The aim of this paper is to design and build a closed loop measurement system that is able to perform this task.

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13

Muzi, Lanfranco. "Advances in Autonomous-Underwater-Vehicle Based Passive Bottom-Loss Estimation by Processing of Marine Ambient Noise". PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2612.

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Accurate modeling of acoustic propagation in the ocean waveguide is important to SONAR-performance prediction, and requires, particularly in shallow water environments, characterizing the bottom reflection loss with a precision that databank-based modeling cannot achieve. Recent advances in the technology of autonomous underwater vehicles (AUV) make it possible to envision a survey system for seabed characterization composed of a short array mounted on a small AUV. The bottom power reflection coefficient (and the related reflection loss) can be estimated passively by beamforming the naturally occurring marine ambient-noise acoustic field recorded by a vertical line array of hydrophones. However, the reduced array lengths required by small AUV deployment can hinder the process, due to the inherently poor angular resolution. In this dissertation, original data-processing techniques are presented which, by introducing into the processing chain knowledge derived from physics, can improve the performance of short arrays in this particular task. Particularly, the analysis of a model of the ambient-noise spatial coherence function leads to the development of a new proof of the result at the basis of the bottom reflection-loss estimation technique. The proof highlights some shortcomings inherent in the beamforming operation so far used in this technique. A different algorithm is then proposed, which removes the problem achieving improved performance. Furthermore, another technique is presented that uses data from higher frequencies to estimate the noise spatial coherence function at a lower frequency, for sensor spacing values beyond the physical length of the array. By "synthesizing" a longer array, the angular resolution of the bottom-loss estimate can be improved, often making use of data at frequencies above the array design frequency, otherwise not utilized for beamforming. The proposed algorithms are demonstrated both in simulation and on real data acquired during several experimental campaigns.

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Baldassaro, Paige Marie. "RF and GIS: Field Strength Prediction for Frequencies between 900 MHz and 28 GHz". Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/34724.

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This thesis presents a model to predict signal strength for frequencies between 902 MHz and 28 GHz. The model approximates diffraction using the knife-edge concept and equations proposed by Lee (1985). LOS pathways are calculated using the Bresenham algorithm and the corresponding elevations are obtained from a 30m DEM base map. The base map was generated by the procedure outlined in Rose (2001) and includes building elevations. The effect of Fresnel zones on prediction accuracy is considered. The effect of interpolating elevations along the Bresenham line is also considered. An Inverse Distance Weighting algorithm was used to interpolate the elevations. The accuracy of the model was evaluated using received signal strength data compiled from studies conducted at 902 MHz, 24.12 GHz and 27.525 GHz. In addition to the compiled data, data was also collected for this study at 2.4 GHz. 257 receiver locations were evaluated; 70 samples were Line-of-Sight. The study area incorporates the Virginia Polytechnic Institute and State University campus. Incorporating Fresnel zones, Interpolating elevations and calculating double blockages do not have an effect on the program's overall ability to predict signal strength. However, for obstructed pathways, it is not adequate to simply use path loss as an estimate of signal strength. Accurate estimates of diffraction gain are crucial for obstructed pathways. In addition, examination of the standard deviation for the data sets indicates that the model is independent of frequency. The average error across the frequencies is positively correlated with frequency, indicating that the model predicts signal strength better for higher frequencies. The smaller wavelengths associated with the higher frequencies require a more directional antenna and are therefore less sensitive to multipath interference. In addition, the smaller wavelengths are less able to diffract around buildings and terrain features.
Master of Science

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15

Thorslund, Birgitta. "Effects of hearing loss on traffic safety and mobility". Doctoral thesis, Linköpings universitet, Institutionen för beteendevetenskap och lärande, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-111933.

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The aim of this PhD thesis was to investigate traffic safety and mobility for individuals with hearing loss (HL). Three studies were conducted: 1. a questionnaire survey aimed to evaluate differences in choice of transportation that might be related to HL, 2. a driving simulator study that looked into compensatory strategies and evaluated the efficiency of a tactile signal to alert the driver, and 3. a field study to evaluate these effects in real traffic and to evaluate a navigation system with a supportive tactile signal. The effects of HL discovered in this thesis add to the knowledge and understanding of the influence of HL on traffic safety and mobility. Differences found consistently point to a generally more cautious behavior. Compensatory and coping strategies associated with HL are bound to driving complexity and appear when complexity increases. These strategies include driving at lower speeds, using a more comprehensive visual search behavior and being less engaged in distracting activities. Evaluation of a tactile signal showed that by adding a tactile modality, some driver assistance systems can also be made accessible to drivers with HL. At the same time, the systems might be more effective for all users, since the driver can be more focused on the road. Based on the results in this thesis, drivers with HL cannot be considered an increased traffic safety risk, and there should be no need for adjustments of the requirements of hearing for a license to drive a car.
Syftet med den här doktorsavhandlingen var att undersöka trafiksäkerhet och mobilitet för individer med hörselnedsättning (HN). Tre studier har genomförts: 1. en enkätstudie för att undersöka skillnader i transportvanor relaterade till HN, 2. en körsimulatorstudie for att titta på kompensatoriska strategier och utvärdera effektiviteten i en taktil signal för att påkalla förarens uppmärksamhet och 3. en fältstudie för att undersöka effekterna i riktig trafik samt utvärdera ett navigationssystem med en taktil signal som stöd för navigering. Effekterna av HN som kom fram i denna avhandling bidrar till kunskapen och förståelsen för hur HN påverkar trafiksäkerhet och mobilitet. De funna skillnaderna pekar konsistent mot ett generelltmera försiktigt beteende. Kompensatoriska - och copingstrategier förknippade med HN beror på körkomplexitet och observeras när komplexiteten ökar. Dessa strategier innebär körning med lägre hastighet, mera heltäckande visuell avsökning och mindre engagemang i distraherande uppgifter. Utvärdering av en taktil signal visade att genom att lägga till en taktil modalitet kan vissa förarstödsystem bli tillgängliga även för förare med HN. Samtidigt kan systemen bli mera effektiva för alla användare eftersom föraren då kan fokusera mera på vägen. Baserat på resultaten i den här avhandlingen kan inte förare med HN betraktas som någon förhöjd risk och det bör därmed inte finnas något behov av att justera hörselkraven när det gäller körkortsinnehav.

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16

Costa, Julio C. "Analysis and optimization of empirical path loss models and shadowing effects for the Tampa Bay area in the 2.6 GHz band". [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002547.

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17

Dyverfeldt, Petter. "Estimation of Turbulence using Magnetic Resonance Imaging". Thesis, Linköping University, Department of Biomedical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7448.

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In the human body, turbulent flow is associated with many complications. Turbulence typically occurs downstream from stenoses and heart valve prostheses and at branch points of arteries. A proper way to study turbulence may enhance the understanding of the effects of stenoses and improve the functional assessment of damaged heart valves and heart valve prostheses.

The methods of today for studying turbulence in the human body lack in either precision or speed. This thesis exploits a magnetic resonance imaging (MRI) phenomenon referred to as signal loss in order to develop a method for estimating turbulence intensity in blood flow.

MRI measurements were carried out on an appropriate flow phantom. The turbulence intensity results obtained by means of the proposed method were compared with previously known turbulence intensity results. The comparison indicates that the proposed method has great potential for estimation of turbulence intensity.

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18

Wu, Qing. "Characterization of Impulse Noise and Hazard Analysis of Impulse Noise Induced Hearing Loss using AHAAH Modeling". OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1467.

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Millions of people across the world are suffering from noise induced hearing loss (NIHL), especially under working conditions of either continuous Gaussian or non-Gaussian noise that might affect human's hearing function. Impulse noise is a typical non-Gaussian noise exposure in military and industry, and generates severe hearing loss problem. This study mainly focuses on characterization of impulse noise using digital signal analysis method and prediction of the auditory hazard of impulse noise induced hearing loss by the Auditory Hazard Assessment Algorithm for Humans (AHAAH) modeling. A digital noise exposure system has been developed to produce impulse noises with peak sound pressure level (SPL) up to 160 dB. The characterization of impulse noise generated by the system has been investigated and analyzed in both time and frequency domains. Furthermore, the effects of key parameters of impulse noise on auditory risk unit (ARU) are investigated using both simulated and experimental measured impulse noise signals in the AHAAH model. The results showed that the ARUs increased monotonically with the peak pressure (both P+ and P-) increasing. With increasing of the time duration, the ARUs increased first and then decreased, and the peak of ARUs appeared at about t = 0.2 ms (for both t+ and t-). In addition, the auditory hazard of experimental measured impulse noises signals demonstrated a monotonically increasing relationship between ARUs and system voltages.

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Al, Issa Huthaifa A. "Position-adaptive Direction Finding for Multi-platform RF Emitter Localization using Extremum Seeking Control". University of Dayton / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1343755148.

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20

Mbairi, Felix D. "Some Aspects of Advanced Technologies and Signal Integrity Issues in High Frequency PCBs, with Emphasis on Planar Transmission Lines and RF/Microwave Filters". Doctoral thesis, KTH, Mikroelektronik och tillämpad fysik, MAP, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4324.

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The main focus of this thesis is placed on high frequency PCB signal Integrity Is-sues and RF/Microwave filters using EBG structures. From the signal Integrity aspect, two topics were mainly discussed. On one hand, the effect of increasing frequency on classical design rules for crosstalk reduction in PCBs was investigated experimentally and by full-wave simulations. An emphasis was placed on the 3×W spacing rule and the use of guard traces. Single-ended and differential transmission lines were considered. S-parameter measurements and simu-lations were carried out at high-frequency (up to 20 GHz). The results emphasize the necessity to reevaluate traditional design rules for their suitability in high frequency applications. Also, the impacts of using guard traces for high frequency crosstalk re-duction were clearly pointed out. On the other hand, the effect of high loss PCB ma-terials on the signal transmission characteristics of microstrip lines at high frequency (up to 20 GHz) was treated. Comparative studies were carried out on different micro-strip configurations using standard FR4 substrate and a high frequency dielectric ma-terial from Rogers, Corporation. The experimental results highlight the dramatic im-pact of high dielectric loss materials (FR4 and solder mask) and magnetic plating metal (nickel) on the high frequency signal attenuation and loss of microstrip trans-mission lines. Besides, the epoxy-based SU8 photoresist was characterized at high frequency (up to 50 GHz) using on-wafer conductor-backed coplanar waveguide transmission lines. A relative dielectric constant of 3.2 was obtained at 30 GHz. Some issues related to the processing of this material, such as cracks, hard-skin, etc, were also discussed. Regarding RF/Microwave filters, the concept of Electromagnetic Band Gap (EBG) was used to design and fabricate novel microstrip bandstop filters using periodically modified substrate. The proposed EBG structures, which don’t suffer conductor backing issues, exhibit interesting frequency response characteristics. The limitations of modeling and simulation tools in terms of speed and accuracy are also examined in this thesis. Experiments and simulations were carried out show-ing the inadequacies of the Spice diode model for the simulations in power electronics. Also, an Artificial Neural Network (ANN) model was proposed as an alternative and a complement to full-wave solvers, for a quick and sufficiently accurate simulation of interconnects. A software implementation of this model using Matlab’s ANN toolbox was shown to considerably reduce (by over 800 times) the simulation time of microstrip lines using full-wave solvers such as Ansoft’s HFSS and CST’s MWS. Finally, a novel cooling structure using a double heatsink for high performance electronics was presented. Methods for optimizing this structure were also discussed.
QC 20100809

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DiSalvo, Maribeth. "Effects of Cardiovascular Health on Hearing Levels Among Musicians". Miami University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=miami1051043965.

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Kritzinger, Mieke. "Cortical Auditory Evoked Potential (CAEP) and the chirp Auditory Steady State Response (ASSR) in predicting behavioural hearing thresholds in adults with sensorineural hearing loss". Diss., University of Pretoria, 2019. http://hdl.handle.net/2263/73231.

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Abstract Purpose: To compare the frequency specific Cortical Auditory Evoked Potential (CAEP) and the chirp-evoked 40 Hz Auditory Steady State Response (ASSR) with equivalent residual noise levels for behavioural threshold prediction in adults with normal hearing and with SNHL. Method: The study tested 23 adults with normal hearing and 20 adults with SNHL. The participants were aged between 18–65 years. A repeated measures within- participant descriptive design was used to collect the quantitative data. The participants underwent behavioural pure tone, CAEP and ASSR testing on the same day. Results: Similar CAEP difference scores across frequencies for the participants with normal hearing (mean=12.32-14.40 dB) and with SNHL (mean=10.00-16.47 dB) were measured. However, for the ASSR difference scores across frequencies slightly smaller difference scores were measured for the participants with SNHL (mean=10.17-17.30 dB) than for the participants with normal hearing (mean=11.74- 17.14 dB). CAEP thresholds were significantly closer to the behavioural pure tone thresholds at 500 (p=0.028; mean absolute difference 14.40 dB) and 2000 (p=0.016; mean absolute difference 12.56 dB) Hz for participants with normal hearing. In participants with sensorineural hearing loss, CAEP and ASSR thresholds were measured at similar sensation levels and were not statistically different (p>0.05). Conclusion: For the purpose of threshold estimation, representing the auditory function to the level of the auditory cortex the CAEP was closer to the behavioural hearing thresholds than the 40 Hz ASSR at all frequencies except at 4000 Hz, regardless of the hearing sensitivity. Keywords: Auditory steady state response (ASSR), Cortical auditory evoked potential (CAEP), Auditory evoked potential (AEP), Residual noise, Signal to noise ratio (SNR), objective threshold estimation, awake adults.
Dissertation (MA (Audiology))--University of Pretoria, 2019.
Speech-Language Pathology and Audiology
MA Audiology
Unrestricted

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Xu, Liang. "Computerised analysis of fetal heart rate". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:9ad2cf2f-45aa-48df-b33f-da27087bd5da.

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This thesis presents a comprehensive work on computerised analysis of fetal heart rate (FHR) features, including feature extraction, feature selection, analysis of influencing factors and setting up/validation of a computerised decision support system. Firstly, a novel feature – pattern readjustment – was extracted and tested. Clinical data were used to train a Support Vector Machine (SVM) to detect pattern readjustment. Then, the association of pattern readjustment and adverse labour outcome was investigated. The validation results with clinical experts show that the pattern readjustment can be accurately detected, while the study on labour outcome shows that the feature is related to fetal acidemia at birth. Secondly, Genetic Algorithms were employed as a feature selection method to select a best subset of FHR features and to use them to predict fetal acidemia with linear and nonlinear SVM. The diagnostic power of the classifier output using selected features was tested on the total set of 7,568 cases. As the classifier output increases, there is a consistent increase of the risk of fetal acidemia. Thirdly, an important influencing factor on FHR features - signal loss – was investigated. A bivariate model was built to estimate error based on signal loss. Validation results show that the bivariate model can accurately predict the error generated by signal loss. The influence of signal loss on labour outcome classification was also investigated. Finally, a computerised decision support system to estimate the risk of fetal acidemia was set up based on the above studies. The system was validated using new retrospective data. Validation results show that the system is capable of predicting adverse labour outcome and providing timely decision support. It is the first time an intrapartum computerised FHR decision support system has been built and validated on this size of dataset. With further improvements, such a system could be implemented clinically in the long term.

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Folio, David. "Stratégies de commande référencées multi-capteurs et gestion de la perte du signal visuel pour la navigation d’un robot mobile". Toulouse 3, 2007. http://www.theses.fr/2007TOU30253.

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L'amélioration des capteurs a permis l'émergence de la commande référencée capteurs qui permet la réalisation de diverses tâches de navigation de façon précises. L'intention de cette thèse est de contribuer à définir des stratégies de commande référencées multicapteurs pour un robot mobile réalisant une tâche référencée vision dans un environnement encombré d'obstacles susceptibles d'occulter le motif visuel. Nous avons ainsi proposé des lois de commandes permettant d'éviter à la fois les occultations et les collisions. Toutefois,les résultats obtenus ont montré que chercher à éviter simultanément ces deux phénomènes sur-contraignait le mouvement du robot,limitant la gamme des missions réalisables. Nous avons alors proposé une approche alternative consistant à tolérer la perte totale du signal visuel. Nous avons ainsi proposé dans un cadre général plusieurs méthodes (analytiques et numériques) de reconstruction du signal visuel lorsqu'il devient indisponible
The recent sensors improvement gave rise to the sensor-based control which allows to perform various and accurate navigation tasks. This thesis aims at developing sensorbased control laws allowing a mobile robot to perform vision-based tasks amidst possibly occluding obstacles. Indeed,it is necessary to preserve not only the robot safety (ie. Noncollision) but also the visual features visibility. Thus,we have first proposed techniques able to fulfill simultaneously the two previously mentioned objectives. However,avoiding both collisions and occlusions often over-strained the robotic navigation task,reducing the range of realizable missions. This is the reason why we have developed a second approach which lets the visual features loss occurs if it is necessary for the task realization. Using the link between vision and motion,we have proposed different methods (analytical and numerical) to compute the visual signal as soon it becomes totally unavailable

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Hasan, Md Al-Mahadi, e Mainul Islam. "Improving the System Performance of High Altitude Platforms Serving Suburban Areas". Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5071.

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High Altitude Platforms (HAP) has been evolving to make a new history in wireless communications infrastructure. A number of applications and services have been proposed for HAP based communications which advance HAP over terrestrial and satellite infrastructure for future communications. Providing high speed multimedia mobile communications through HAPs to the users of Third Generation (3G) holds strong position using one of the proposed band, 2GHz. In this study we investigated how to improve the performance of 3G serving from HAP over a territory having suburban characteristics. Two proposed channel models, free space loss and shadowing loss, has been used to analyze the performance of HAP systems at 2GHz frequency band for suburban regions. Three different parameters namely antenna bore point, HAP antenna roll off factor and user antenna roll off factor have proposed to improve the performance of HAP systems while considering suburban regions. A scenario has introduced consisting of an ideal suburban and rural region to serve 3G services while emphasizing on suburban region. The number of HAPs required to serve the defined suburban region is restricted to at least three due to elevation dependent losses in the scenario. The three proposed parameters have been used to improve the performance of 3G services over the selected suburban region. Application of the parameters over suburban region gives different performances which can be categorized in different ways. Some of the parameters are more elastic than others for a certain coverage area. We conclude with adaptive application of the parameters for 3G services over suburban area to have improved performance of HAP.
+46720459586

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Grobbelaar, Annerina. "Linear frequency transposition and word recognition abilities of children with moderate-to-severe sensorineural hearing loss". Diss., Pretoria : [s. n.], 2009. http://upetd.up.ac.za/thesis/available/etd-03112010-104801.

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Bsoul, Abed Al-Raoof. "PROCESSING AND CLASSIFICATION OF PHYSIOLOGICAL SIGNALS USING WAVELET TRANSFORM AND MACHINE LEARNING ALGORITHMS". VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/258.

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Over the last century, physiological signals have been broadly analyzed and processed not only to assess the function of the human physiology, but also to better diagnose illnesses or injuries and provide treatment options for patients. In particular, Electrocardiogram (ECG), blood pressure (BP) and impedance are among the most important biomedical signals processed and analyzed. The majority of studies that utilize these signals attempt to diagnose important irregularities such as arrhythmia or blood loss by processing one of these signals. However, the relationship between them is not yet fully studied using computational methods. Therefore, a system that extract and combine features from all physiological signals representative of states such as arrhythmia and loss of blood volume to predict the presence and the severity of such complications is of paramount importance for care givers. This will not only enhance diagnostic methods, but also enable physicians to make more accurate decisions; thereby the overall quality of care provided to patients will improve significantly. In the first part of the dissertation, analysis and processing of ECG signal to detect the most important waves i.e. P, QRS, and T, are described. A wavelet-based method is implemented to facilitate and enhance the detection process. The method not only provides high detection accuracy, but also efficient in regards to memory and execution time. In addition, the method is robust against noise and baseline drift, as supported by the results. The second part outlines a method that extract features from ECG signal in order to classify and predict the severity of arrhythmia. Arrhythmia can be life-threatening or benign. Several methods exist to detect abnormal heartbeats. However, a clear criterion to identify whether the detected arrhythmia is malignant or benign still an open problem. The method discussed in this dissertation will address a novel solution to this important issue. In the third part, a classification model that predicts the severity of loss of blood volume by incorporating multiple physiological signals is elaborated. The features are extracted in time and frequency domains after transforming the signals with Wavelet Transformation (WT). The results support the desirable reliability and accuracy of the system.

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Zattoni, Michelle Queiroz. "Benefício do sistema de frequência modulada em crianças usuárias de aparelhos de amplificação sonora individual e implante coclear". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/5/5160/tde-21012013-174615/.

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A criança com deficiência auditiva sensorioneural apresenta uma maior dificuldade para compreender a fala em meio ao ruído em comparação à criança normo-ouvinte. Portanto é importante considerar o uso de recursos, como o sistema de frequência modulada (FM), que auxiliam os usuários de aparelho de amplificação sonora individual (AASI) e implante coclear (IC) no reconhecimento de fala no ruído. OBJETIVO: verificar o benefício do sistema de FM em crianças com deficiência auditiva sensorioneural usuárias de AASI e/ou IC. METODOLOGIA: Participaram do estudo 30 crianças com idades entre 6 e 13 anos divididas em três grupos: grupo 1 (adaptação bimodal), grupo 2 (adaptação bilateral de AASI) e grupo controle (normo-ouvintes). Os sujeitos foram submetidos a uma avaliação do reconhecimento de fala no ruído, sendo que os sujeitos do grupo de estudo 1 e 2 foram submetidos a avaliação com e sem o sistema de FM. RESULTADOS: O sistema de FM apresentou benefícios estatisticamente significantes para os usuários de AASI e IC. A média de melhora com o sistema de FM foi de 9,7dB relação S/R para o grupo 1 e 17,2dB relação sinal/ruído para o grupo 2. A comparação com o grupo controle evidenciou que para uma criança usuária de AASI e/ou IC pode ser necessário uma melhora na relação S/R maior que 10dB a fim de alcançar o mesmo grau de reconhecimento de fala de crianças normo-ouvintes. CONCLUSÃO: O Sistema de FM beneficia crianças com deficiência auditiva usuárias de AASI e/ou IC no reconhecimento de fala no ruído.
The child with sensorineural hearing loss presents more difficulty to understand speech in noise compared with children with normal hearing. Therefore, it is important to consider the use of resources, such as the frequency modulation (FM) system, which help users of hearing aids (HA) and cochlear implants (CI) in speech recognition in noise. OBJECTIVE: verify the benefit of the FM system in children with sensorineural hearing loss users of hearing aid and/or CI. METHOD: We studied 30 children aged between 6 and 13 years divided into three groups: group 1 (bimodal fitting), group 2 (binaural fitting of hearing aids) and control group (normal hearing). The subjects were evaluated as to speech recognition in noise, and subjects of group 1 and 2 underwent evaluation with and without the FM system. RESULTS: The FM system showed statistically significant benefits for users of hearing aid and CI. The mean improvement in the FM system was 9.7 dB signal/noise ratio for group 1 and 17.2 dB signal/noise ratio for group 2. The comparison with the control group showed that for a child user of hearing aid and/or CI it may be necessary an improvement in S/N ratio greater than 10dB in order to achieve the same degree of speech recognition of normal hearing children. CONCLUSION: The FM system benefits children with hearing loss users of hearing aid and/or CI in speech.

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Arieta, Aline de Moraes 1981. "HINT Brasil : estudo em portadores de perdas auditivas". [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/309221.

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Orientadores: Everardo Andrade da Costa, Christiane Marques do Couto
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-22T10:10:32Z (GMT). No. of bitstreams: 1 Arieta_AlinedeMoraes_D.pdf: 1729442 bytes, checksum: 2887ecc98db30769bd998782cb6716d0 (MD5) Previous issue date: 2013
Resumo: A investigação do reconhecimento da fala na presença de ruído competidor, em situações de escuta assemelhadas às do dia a dia, torna-se cada vez mais necessária. Atualmente, na rotina audiológica nacional, esta avaliação ainda é realizada sem ruído, limitando as informações sobre o desempenho dos indivíduos em condições de vida real. Este problema se agrava nas perdas auditivas sensorioneurais, de alta ocorrência na sociedade. O objetivo desta pesquisa é avaliar o reconhecimento da fala sem e com ruído competidor, em diferentes grupos populacionais, com o teste - Hearing in Noise Test - HINT BRASIL - Um total de 268 sujeitos, 180 do gênero masculino e 78 do feminino, foram avaliados e divididos em: 66 normo-ouvintes; 70 normo-ouvintes com história de exposição a ruído ocupacional; 80 com perda auditiva sensorioneural, com história de exposição a ruído ocupacional e 52 usuários de próteses auditivas. O HINT Brasil foi aplicado com fones de ouvido e em campo livre nas condições: sem ruído (S); com ruído frontal (RF); ruído à direita (RD); ruído à esquerda (RE). Além disso, o programa fornece uma média ponderada das condições com ruído, a qual denomina Ruído Composto (RC). Os resultados foram computados em dB(A) na condição sem ruído e em dB Relação Sinal/Ruído nas condições com ruído. Nos testes com ruído, os valores obtidos em campo livre foram piores do que os obtidos com fones de ouvido. O grupo de normo-ouvintes exposto a ruído ocupacional apresentou pior desempenho ao HINT Brasil, na condição RC, em relação aos normo-ouvintes não expostos. O grupo de sujeitos com perda auditiva sensorioneural apresentou respostas piores em todas as condições de aplicação do HINT Brasil quando comparados aos normo-ouvintes com e sem exposição. No grupo de usuários de próteses auditivas, o desempenho para o HINT Brasil foi melhor com o uso das próteses em relação a não utilização delas
Abstract: The investigation to recognize speech in day-to-day conditions becomes increasingly necessary. Currently, on the national routine audiological, this evaluation is still performed without noise, limiting the information about the performance of individuals in real-life conditions. This problem is aggravated on sensorineural hearing loss, which has high prevalence in society. The purpose of this research is to evaluate speech recognition with and without noise in different population groups, using the HINT Brazil (Hearing in Noise Test - Portuguese version of Brazil). A total of 268 people, 180 males and 78 females were evaluated: 66 normal hearing, 70 normal hearing individuals with a history of occupational noise exposure, 80 with sensorineural hearing loss, with a history of occupational noise exposure and 52 users hearing aids. The HINT Brazil was applied, with headphones and soundfield on conditions: quiet (Q); Noise Front (NF) Noise Right (NR); Noise Left (NL). Additionally, the program provides an average of the noise conditions called Noise Composed (NC). The results were calculated on dB (A) with no noise conditions and dB Signal to Noise Ratio (S/R) in noisy conditions. On the tests with noise, the values obtained in soundfield were worse than the ones with headphones. The normal hearing group exposed to occupation noise presents worse performance with the HINT Brazil, in the condition RC, comparing to the ones not exposed. The sensoneural hearing loss group presented worse performance in all the conditions of the HINT Brazil comparing to the normal hearing with and without exposure. On the hearing aid users group, the HINT performance was better using the hearing aids
Doutorado
Epidemiologia
Doutora em Saúde Coletiva

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Saeed, Asad, Habib Ur Rehman e Muhammad Hassan Masood. "Performance Analysis and Comparison of Radio Propagation Models for Outdoor Environment in 4G LTE Network". Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3241.

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The dissertation concerns about the path loss calculation of Radio Frequency (RF) propagation models for 4G Long Term Evolution (LTE) Network to prefer the best Radio Frequency propagation model. The radio propagation models are very significant while planning of any wireless communication system. A comparative analysis between radio propagation models e.g. SUI model, Okumura model, Cost 231 Hata Model, Cost 231-Walfisch Ikegami and Ericsson 9999 model that would be used for outdoor propagation in LTE. The comparison and performance analysis has been made by using different geological environments e.g. urban, sub-urban and rural areas. The simulation scenario is made to calculate the lowest path loss in above defined environments by using selected frequency and height of base station antennas while keeping a constant distance between the transmitter and receiver antennas.
Asad Saeed C/O Muhammad Awais Hovslagargatan 47 LGH 1004 19431 Stockholm Sweden Mob: 0046723333734

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Obeidat, Huthaifa A. N. "Investigation of Indoor Propagation Algorithms for Localization Purposes: Simulation and Measurements of Indoor Propagation Algorithms for Localization Applications using Wall Correction Factors, Local Mean Power Estimation and Ray Tracing Validations". Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17385.

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The objective of this work is to enhance the awareness of the indoor propagation behaviour, by a set of investigations including simulations and measurements. These investigations include indoor propagation behaviour, local mean power estimation, proposing new indoor path loss model and introducing a case study on 60 GHz propagation in indoor environments using ray tracing and measurements. A summary of propagation mechanisms and manifestations in the indoor environment is presented. This comprises the indoor localization techniques using channel parameters in terms of angle of arrival (AOA), time of arrival (TOA) and received signal strength (RSS). Different models of path loss, shadowing and fast fading mechanisms are explored. The concept of MIMO channels is studied using many types of deterministic channel modelling such as Finite Difference Time Domain, Ray tracing and Dominant path model. A comprehensive study on estimating local average of the received signal strength (RSS) for indoor multipath propagation is conducted. The effect of the required number of the RSS data and their Euclidian distances between the neighbours samples are investigated over 1D, 2D and 3D configurations. It was found that the effect of fast fading was reduced sufficiently using 2D horizontal’s arrangement with larger spacing configuration. A modified indoor path loss prediction model is presented namely effective wall loss model (EWLM). The modified model with wall correction factors is compared to other indoor path loss prediction models using simulation data (for 2.4, 5, 28, 60 and 73.5 GHz) and real-time measurements (for 2.4 and 5 GHz). Different operating frequencies and antenna polarizations are considered to verify the observations. In the simulation part, EWLM shows the best performance among other models. Similar observations were recorded from the experimental results. Finally, a detailed study on indoor propagation environment at 60 GHz is conducted. The study is supported by Line of Sight (LoS) and Non-LoS measurements data. The results were compared to the simulated ones using Wireless-InSite ray tracing software. Several experiments have confirmed the reliability of the modelling process based on adjusted material properties values from measurements.

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Cruz, Aline Duarte da. "Esforço auditivo e fadiga em adolescentes com deficiência auditiva - uso do sistema FM". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/25/25143/tde-01102018-201135/.

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O esforço auditivo é definido como o esforço cognitivo e de atenção necessários para compreender a fala em ambiente ruidoso. Este estudo teve como objetivo analisar o esforço auditivo e fadiga em adolescentes com deficiência auditiva, usuários de aparelho de amplificação sonora individual (AASI), sem e com sistema de frequência modulada (FM), e comparar com adolescentes com audição normal, por meio do desenvolvimento de uma plataforma para execução da tarefa secundária em teste de dupla tarefa; analisar o impacto do ruído na aprendizagem pela perspectiva dos participantes; e investigar a opinião dos usuários sobre o impacto do uso do sistema FM na sala de aula. Participaram 18 adolescentes com audição normal e 13 adolescentes com deficiência auditiva sensorioneural, bilateralmente, de grau moderado e severo usuários de AASI e sistema FM, com média de idade de 14 anos. O esforço auditivo foi avaliado por meio do paradigma da dupla tarefa, a fadiga por meio de escala, o impacto do ruído na aprendizagem por meio de uma questão e foi aplicado um questionário sobre o uso do sistema FM em ambiente educacional. Foram utilizados para análise dos resultados o teste T (p< 0,01), Anova, qui-quadrado de Pearson (p<0,05) e análise descritiva. Foi elaborada uma plataforma para auxiliar a execução do teste de dupla tarefa, denominada PALETA, com um teste de memória de reconhecimento de cores. A diferença do esforço auditivo com base no número de respostas corretas foi estatisticamente significativa entre os participantes do grupo com audição normal e os participantes do grupo com deficiência auditiva na condição apenas com AASI, o que não ocorreu quando analisado o tempo de resposta. Os resultados sugerem que o desempenho do grupo com audição normal foi próximo ao do grupo com deficiência auditiva na condição com AASI e sistema FM, sendo que na condição de uso apenas do AASI apresentou um esforço auditivo maior. Os resultados obtidos na escala de avaliação da fadiga não revelaram diferenças estatisticamente significativas entre nenhum dos grupos. Sobre o impacto no ruído na sala de aula, os resultados revelaram que o grupo usuário de AASI e sistema FM relataram menor queixa quanto ao ruído interferir na aprendizagem do que seus pares ouvintes e na condição apenas com seus AASI. O questionário aplicado forneceu informações sobre as perspectivas do usuário de sistema FM, que em sua maioria encontravam-se satisfeitos e faziam o uso efetivo de seus dispositivos em sala de aula. Conclui-se que a PALETA é considerada uma ferramenta efetiva para auxiliar na cução de teste de dupla tarefa quando considerado o número de respostas corretas; o uso do sistema FM foi efetivo para reduzir o esforço auditivo; não foram encontradas diferenças significativas entre os grupos quanto à fadiga; a queixa dos adolescentes com deficiência auditiva quanto ao impacto do ruído na aprendizagem diminui significativamente com o uso do sistema FM, e a maioria dos adolescentes usuários de sistema FM encontravam-se satisfeitos e faziam o uso efetivo de seus dispositivos em sala de aula.
Listening effort is defined as the cognitive effort and the attention required to understand speech in a noisy environment. This study aims to analyze listening effort and fatigue in hearing impaired adolescents, users of HA, with and without a FM system, and to compare them with adolescents with normal hearing, through development of a platform for performing the secondary task in a dual-task test; analyze the impact of noise on learning from the participants perspective; and investigate users\' opinions on the impact of using the FM system in the classroom. A total of 31 adolescents participated in this study: 18 with normal hearing and 13 with moderate to severe bilateral sensorineural hearing loss, users of HA and FM system. The mean age of the adolescents was 14 years. Listening effort was evaluated using dual task paradigm; fatigue, using a scale; the impact of noise on learning, using a question; and the use of the FM system in an educational environment, using a questionnaire. The results were statistically analyzed using t-test (p<0.01), Anova, chisquare of Pearson (p<0.05) and descriptive analysis. A platform was developed to assist in the execution of the dual task test. The platform was named PALETA and consisted of color recognition memory test. Based on the number of correct responses, the difference in listening effort was statistically significant between the participants of the normal hearing group and the participants of the hearing-impaired group when these participants were using HA; but the difference was not statistically significant when comparing response times. The results suggest that the performance of the normal hearing group was similar to the hearing-impaired group when these participants were using a HA and a FM system. When the participants of the hearingimpaired group were using only the HA, the results showed a greater listening effort. The results obtained in the fatigue assessment scale did not reveal statistically significant differences in any of the groups. On the impact of noise in the classroom, the results revealed that the hearing-impaired group users of hearing aid and FM system reported less complaints about noise interfering in learning than their normal hearing peers and in the condition only with their HA. The questionnaire applied provided information on the user\'s perspectives of FM system, which showed that the users were mostly satisfied and made effective use of their devices in the classroom. It is concluded that PALETA is considered an effective tool to assist in the execution of dual task test when considering the number of correct answers; the use of the FM system was effective in reducing listening effort; no significant differences were found between the groups regarding fatigue; the complaint of adolescents with hearing loss about the impact of noise on learning diminishes significantly with the use of the FM system; and the majority of adolescents using FM systems were satisfied and made effective use of their devices in the classroom.

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33

Castro-Arvizu, Juan Manuel. "Robust indoor positioning in WLAN networks". Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/405889.

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Navigation and location technologies have been reaching in a major interest where Global Navigation Satellite System (GNSS) is mostly adopted. The limitation of this technology is that direct sky view is needed for reliable positioning. In indoor environments, however, it is difficult for GNSS technology to provide a reliable performance in positioning due to the signal attenuation and blocking caused by buildings and construction materials. For this reason, the growth in indoor applications has focused the research in new techniques for attempting mitigate the poor GNSS performance on this type of environments In the context of indoor positioning, multitude of emerging technologies for localization based on ultrasound, infrared, Ultra Wide Band (UWB), Zigbee, inertial navigation and other non-GNSS technologies have been proposed but special equipment is required and a large number of signal sources are needed. However, Wireless Local Area Network (WLAN) technology is widely used in indoor positioning. While the same requirements are also needed as the other technologies in order to improve the positioning accuracy, in terms of cost and ability, Wireless-based indoor location is widely used due to the already deployment of Anchor Points (AP) in urban and indoor areas. There are several methods for indoor positioning purposes e.g ToA (Time of Arrival), Received Signal Strength (RSS) measurements, AoA (Angle of Arrival), fingerprinting and so on. Most of the network-based location estimations use RSS measurements because almost all mobile devices are afforded to use this type of measurements. So, this thesis is centered in WLAN RSS-based positioning systems. The first step for indoor positioning is the distance estimation between the user and the AP. Theoretical and empirical propagation channel models are used to translate the difference between the transmitted and Received Signal Strength into an estimated range. A Propagation channel model built the radio map and also report changes in the environment. There are several models in the literature to characterize this channel. Indoor RSS-based localization has become a popular solution, but standard techniques still consider a time invariant simple single slope path loss channel model with a priori known constant channel parameters. While some contributions considered the RSS-based localization problem using a single path loss model with unknown parameters, the general solution that considersa generalized distance dependent measurement model is an important missing point. This thesis considers the two-slope channel model and proposes a robust indoor positioning solution based on a parallel architecture using a set of Interacting Multiple Models (IMM), each one involving two Extended Kalman filters (EKF) and dealing with the estimation of the distance to a given AP. Within each IMM, the two-slope path loss model parameters are sequentially estimated with Maximum Likelihood Estimate (MLE) to provide a robust solution. Finally, the set of distance estimates are fused into a standard EKF-based solution to mobile target tracking. In addition, the benchmarks derived in this thesis to evaluate the performance of our IMM-EKF algorithm are the Cramér Rao Lower Bound (CRLB) and the Posterior Cramér Rao Lower Bound (PCRLB) providing a guidance in the improvement of the experimental design. The CRLB is used to assess the estimation of model parameters and the PCRLB for tracking solution. This, combined with a path-loss exponent estimation, the channel calibration algorithm is validated with an online range estimation. The central theme throughout this thesis is to develop a completely online two-slope channel calibration and, simultaneously, a mobile target tracking algorithm. The performance of the method is assessed through realistic computer simulations and validated with real RSS measurements obtained from experimental tests in a typical office environment.
Las tecnologías en navegación y localización han estado obteniendo un gran interés en los últimos años donde el Sistema Global de Navegación por Satélite (GNSS) aparece como el más utilizado para estos fines. No obstante, una de las limitaciones del GNSS es la necesidad de tener una visión directa al cielo para así garantizar un posicionamiento bastante fiable. También, al utilizar solamente tecnología GNSS en espacios interiores (más conocidos en el mundo científico por entornos indoor), se es complicado conseguir un buen desempeño en términos de posicionamiento debido a la atenuación e interferencia de la señal causada por los edificios y materiales de construcción. Por esta razón, y debido al crecimiento en aplicaciones dentro de entornos indoor, la investigación de nuevas tecnologías para posicionamiento en interiores se ha centrado en intentar mitigar el mal desempeño de la tecnología GNSS en este tipo de ambientes. En el contexto de posicionamiento en interiores (indoor positioning), se han propuesto multitud de tecnologías emergentes para localización basadas en ultrasonido, infrarrojo, Banda Ultra Ancha (UWB), Zigbee,navegación inercial y otras tecnologías que no sean GNSS. Sin embargo, se requiere de equipo especial y un gran número de fuentes de señal. A pesar de ello, la tecnología en Redes de Área Local Inalámbricas (WLAN) es ampliamente utilizada en el posicionamiento en interiores. Aunque la tecnología WLAN tenga los mismos requerimentos que el resto de tecnologías, en términos de coste y practicidad, los sistemas de posicionamiento basados en redes inalámbricas se utilizan con mayor frecuencia debido al ya existente despliegue de estaciones base (AP) en áreas urbanas e interiores. Existen varias técnicas que sirven para fines de posicionamiento en interiores. Por ejemplo, utilizando el tiempo de llegada de la señal (TOA), las mediciones de la potencia de la señal recibida ( RSS), el ángulo de llegada (AoA), la técnica fingerprinting entre otras. Esta tesis está centrada en sistemas de posicionamiento basados en mediciones WLAN-RSS. Un modelo de canal de atenuación de interiores contruye un mapa de cobertura y también es capaz de reportar los cambios en el entorno indoor. El posicionamiento indoor basado en mediciones RSS se ha convertido en una solución bastante popular, pero las técnicas comunes consideran un modelo de pérdidas por trayectoria de una pendiente, invariante en el tiempo y con un conocimiento previo de los parámetros del canal que se consideran constantes. Esta tesis considera el modelo de pérdidas por trayectoria de pendiente dual y propone una solución robusta para posicionamiento en interiores basado en una arquitectura paralela conformada por un conjunto de algoritmos de Interacción de Múltiples Modelos (IMM) donde cada IMM involucra dos Filtros de Kalman Extendidos (EKF) para el proceso de estimación de la distancia entre el AP y el usuario. Dentro de cada IMM, los parametros del modelo de pérdidas por trayectoria de pendiente dual se estiman secuencialmente utilizando la estimación por máxima verosimilitud (MLE) y así proveer una solución robusta. Finalmente, el conjunto de distancias estimadas se fusionan en un EKF para tener una solución final de la posición del usuario. Además, las cotas de referencias que son derivadas en esta tesis y que sirven para evaluar el rendimiento del algoritmo IMM-EKF son la Cota Inferior de Cramér Rao (CRLB) y la Cota Inferior de Cramér Rao Posterior (PCRLB) que servirán de guía para el perfeccionamiento del diseño experimental. El tema central de esta tesis es desarrollar un algoritmo online para posicionamiento indoor que simultáneamente sea capaz de hacer la calibración del canal de propagación. El desempeño del método se evalúa mediante simulaciones por computadora que se validan con mediciones RSS reales obtenidas a partir de pruebas experimentales.

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Fidêncio, Vanessa Luisa Destro. "Avaliação digital do efeito do ruído sobre a fala: relação sinal/ruído". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/25/25143/tde-03122013-170001/.

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Abstract (sommario):

O ruído é um fator que contribui negativamente para a habilidade de compreensão da fala, o que pode prejudicar o desenvolvimento da criança com deficiência auditiva. Nas salas de aula, a fala raramente é transmitida a criança sem que haja interferência do ruído de fundo. Ao mesmo tempo, a efetiva transmissão da informação auditiva é imprescindível para um melhor desempenho acadêmico. Na maioria dos ambientes de aprendizagem, o que mais interfere para que haja uma boa percepção da fala é a relação sinal/ruído (S/R). O Sistema de Frequência Modulada (FM) funciona como o meio mais efetivo para melhorar a captação do sinal da fala e eliminar os efeitos da distância, ruído e reverberação em ambiente educacional. Objetivo: Avaliar a relação S/R a que crianças com deficiência auditiva estão expostas em ambiente escolar e comparar com o limiar de recepção da fala no ruído. Métodos: O trabalho foi realizado com crianças com deficiência auditiva e com linguagem oral estabelecida, usuárias de aparelho de amplificação sonora individual (AASI) e/ou implante coclear (IC) acoplados ao Sistema FM. A mensuração da relação sinal ruído foi realizada através da utilização de um gravador digital portátil e um programa de processamento de áudio para computador. Para avaliação da percepção da fala no ruído, foi aplicada a versão brasileira do teste Hearing in Noise Test (HINT), em campo livre em dois momentos: primeiramente com a criança utilizando apenas seus AASIs e/ou IC e em um segundo momento com o Sistema FM acoplado ao dispositivo individual. Resultados: Todas as crianças apresentaram melhor percepção da fala no ruído com o uso do Sistema FM. Apenas em uma sala de aula a relação sinal/ruído está adequada. Observou-se que a posição do aluno na sala de aula realmente influencia na qualidade da relação S/R a qual o mesmo está exposto. Também foi comprovado que, quanto maior o número de alunos, mais baixa é a relação S/R da sala de aula. Conclusão: A relação S/R da sala de aula em situação real de ensino mostrou-se com um valor mais próximo à relação S/R em que o paciente consegue compreender o discurso com o uso do Sistema FM, demonstrando que o uso do dispositivo é essencial para melhor compreensão da fala nesse ambiente.
Noise is a factor that contributes negatively to the ability to understand speech, which can harm the development of children with hearing impairment. In classrooms, speech is rarely transmitted to children without interference from background noise. At the same time, the effective transmission of auditory information is essential for better academic performance. In most learning environments, which further interferes so there is a good speech perception is the signal/noise ratio (S/N). The Personal Frequency Modulation (FM) Systems serves as the most effective way to improve the uptake of speech signal and eliminate the effects of distance, noise and reverberation in the educational environment. Objective: To evaluate the S/N ratio that hearing impaired children are exposed in a school environment and compare with the speech reception threshold in noise. Methods: The study was conducted with children with hearing impaired and spoken language established, users of a hearing aids and/or cochlear implant (CI) coupled to FM system. The measurement of signal to noise ratio was achieved by the use of a portable digital recorder and an audio processing program for computer. To assess speech perception in noise was applied the Brazilian version of the Hearing in Noise Test (HINT), in two stages: first with the child using only their hearing aid\'s and/or CI and a second time with FM system coupled to individual device. Results: All children had better speech perception in noise using the FM system. Only in a one classroom the S/N ratio is adequate. It was observed that the position of the student in the classroom really affect the quality of the S/N ratio to which it is exposed. It was also proven that the higher the number of students, the lower the S/N ratio of the classroom. The S/N ratio of the classroom in a real school showed up with a value closer to the S/N ratio in which the patient can understand speech using the FM system, demonstrating that the use of this device is essential to better understand speech in these environments.

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Gitijah, Parham. "Utveckling av mätmetod och prestandaanalys av LoRa". Thesis, KTH, Hälsoinformatik och logistik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-252818.

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Internet of Things(IoT) tillämpningar har ökat under de senaste åren och därför behövs nya kommunikationstekniker som uppfyller kriterierna låg strömförbrukning, lång räckvidd samt låg kostnad, som behövs för att distribuera tekniken i samhället. LoRa (Long Range) är en framstående trådlös kommunikationsteknik som utvecklades av LoRa Alliance för att uppfylla dessa kriterier. Syftet med arbetet är att utveckla en mätmetod för prestandaanalys av radiosystemet LoRa. Mätmetoden används sedan för att analysera hur olika parametrar som datahastighet, avstånd och olika miljöer påverkar LoRa-nätverksprestandaparametrar dvs. signalstyrka, paketförluster, fördröjningar (latency) och fördröjningsvariationer (jitter). För att uppnå syftet utvecklades först en mätningsmetod. Därefter genomfördes experiment i två olika miljöer (stadsmiljö och havsmiljö) för prestandaanalys av LoRa. I varje experiment positionerades en IoT-nod på olika avstånd och datapaket skickades med olika datahastigheter från IoT-noden till en gateway. Datahastigheten ändrades genom att ändra på spridningsfaktor (SF) och bandbredd. Passiv mätningsmetod användes för att samla in mätningsdata. Metoden som användes för att analysera resultaten var statistisk dataanalysmetod då de data som samlades in var kvantitativa. Resultatet visar att signalstyrkan påverkas av miljö, avstånd och bandbredd. Signalstyrkan är starkare i fri sikt jämfört med stadsmiljö. Signalstyrkan är starkare även vid kortare avstånd och större bandbredd. Däremot har datahastigheten (SF) minimal påverkan på signalstyrkan. Att signalstyrkan påverkas av bandbredden är intressant resultat som inte kunde förutses innan. Paketförlusten påverkas av miljö, datahastighet (SF och bandbredd) och avstånd. Fler datapaket förloras vid längre avstånd och i stadsmiljön. Lägre datahastighet leder till att färre datapaket förloras och på så sätt längre kommunikationsräckvidd uppnås. Enligt tidigare arbetens simuleringar förutsågs att högre datahastighet leder till längre kommunikationsräckvidd men i den här studien genomfördes experiment på riktig hårdvara för att undersöka resultaten. Miljö, avstånd och datahastighet påverkar fördröjningen. Fördröjningen är några millisekunder längre i stadsmiljö än havsmiljö vid samma avstånd. Fördröjningen är även några millisekunder längre vid längre avstånd i samma miljö. Däremot har datahastighet största påverkan på fördröjningen. Fördröjningen ändras med några hundra millisekunder när datahastigheten ändras genom SF och/eller bandbredd. Fördröjningsvariationen påverkas inte av miljö och avstånd. Datahastighet (bandbredd och SF) påverkar fördröjningsvariationen men denna påverkan är låg och man kan bortse från den.
The Internet of Things (IoT) use cases have increased significantly in recent years. Therefore, new wireless communication technologies are needed that meet the criteria such as low power consumption, long range and low cost. LoRa, which stands for "Long Range", is a wireless communication technology developed by the LoRa Alliance to meet these criteria. The purpose of this paper is to a develop measurement method for performance analysis of the LoRa radio system. The measurement method used to analyze how different parameters such as data rate, distance and different environments affect LoRa network performance parameters i.e. signal strength, packet loss, latency and jitter. To achieve the purpose, a measurement method and prototype were first developed. Then experiments were carried out in two different environments (urban and open space). In each experiment, an IoT node was positioned at different distances and data packets were sent from the IoT node to a gateway with different data rates. The data rate was changed by changing the spreading factor (SF) and bandwidth. Passive measurement method was used to collect measurement data. The method used to analyze the results was the statistical data analysis method since the data collected was quantitative. The result shows that the signal strength is affected by the environment, distance and bandwidth. The signal strength is stronger in free view compared to urban environment. The signal strength is stronger even at shorter distances and greater bandwidth. However, the data rate (SF) has minimal impact on signal strength. The fact that the signal strength is affected by the bandwidth is interesting results that could not be predicted before. The packet loss is affected by the environment, data rate and distance. More data packets go lost at longer distances and in the urban environment. Lower data rate cause to fewer data packets go lost and a longer communication range being achieved. According to earlier work's simulations, it was possible to predict that higher data rates lead to longer communication range, but in this study experiments were carried out on real hardware to investigate the results. Environment, distance and data rate affect the delay. The delay is a few milliseconds longer in urban environment than the free space environment at the same distance. The delay is also a few milliseconds longer at longer distances in the same environment. However, data rate has the greatest impact on the delay. The delay changes by a few hundred milliseconds when the data rate is changed by SF and/or bandwidth. The jitter is not affected by the environment and distance. Data rate (bandwidth and SF) affects the delay variation but this influence is low and can be ignored.

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36

Lessoway, Kamea. "Perception of quality of life for adults with hearing impairment in Aotearoa / New Zealand". Thesis, University of Canterbury. Department of Communication Disorders, 2014. http://hdl.handle.net/10092/9599.

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AIMS: This study investigated the perception of generic and disease-specific Health-Related Quality of Life (HRQoL) for adults living with hearing impairment (HI) in Aotearoa/New Zealand (NZ). This study aimed to answer three questions: (1) What is the perception of HRQoL amongst adults with hearing impairment in NZ? (2) How do these perceptions compare to adults with HI living in other countries for which we have data? (3) What are the demographic and audiometric variables related to device ownership? METHOD: HRQoL, demographic, and audiometric information was collected from 126 adults in NZ. The following demographic information was collected: age, relationship length, hours worked per week, income, ancestry, sex, level of education, city size, and sexual orientation. The following audiologic information was also collected: ownership of hearing aids (HA), ownership of hearing assistance technology (HAT), better-ear pure-tone average (BEPTA), worse-ear pure-tone average (WEPTA), and signal-to-noise ratio loss (SNR loss). HRQoL information was collected using the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36; Ware & Sherbourne, 1992), and the Hearing Handicap Inventory (HHI) for both elderly (HHIE) and adults (HHIA; Ventry & Weinstein, 1982; Newman, Weinstein, Jacobson, & Hug, 1991). Variables discriminating HA and HAT owners from non-owners were also analysed. RESULTS: The relationship between demographic variables and HRQoL scores revealed that only age and income were significant. Audiometric variables had significant relationships with disease-specific HRQoL scores, as well as HA and HAT ownership. Finally, disease-specific HRQoL scores and all audiometric variables differentiated HA owners from non- owners, but demographic variables did not. Generic HRQoL scores and all audiometric variables differentiated HAT owners from non-owners. CONCLUSIONS: These results suggest that the negative impacts of HI on HRQoL as reported overseas are also present in NZ, and that not only do audiometric variables including SNR loss are related to HRQoL, but HRQoL is a significant predictor for HA and HAT ownership. Further QoL research is warranted amongst the HI population in NZ to identify and understand any causal relationships present amongst these variables. Furthermore, HRQoL instruments and a test of speech understanding in noise have been shown to provide additional meaningful information, and therefore clinicians might consider including them during consultation.

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Jaimes, Isaac. "Contribution à la modélisation d’un turbocompresseur automobile et sa caractérisation acoustique". Thesis, Paris, ENSAM, 2017. http://www.theses.fr/2017ENAM0045/document.

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Dans cette thèse, des méthodes de caractérisation acoustique passive et active de systèmes acoustiques à deux ports sont présentées, basées sur une décomposition d’ondes planes en entrée et sortie. Cette décomposition est réalisée par la méthode du beamforming. Ces méthodes mises en place et validées sur des géométries simples, sont ensuite employées pour caractériser l’étage compresseur d’un turbocompresseur de suralimentation automobile. La caractérisation acoustique active se fait par la mesure de la puissance et de l’intensité acoustique dans les conduits du compresseur, ceci pour des points de fonctionnement spécifiques, des cartographies compresseur complètes sont également élaborées. Les essais ont été menés sur banc turbo, banc moteur et sur véhicule complet. La caractérisation acoustique passive est abordée par le calcul de matrices du compresseur (matrice de transfert, matrice d’impédance et matrice de diffusion). Le calcul de la perte par transmission acoustique est déduit de ces matrices. Des essais ont été réalisés et comparés à des simulations éléments finis 3D sur un turbocompresseur statique comme sur un turbocompresseur opérationnel
In this thesis, methodologies to perform the acoustic passive and active characterization of two port systems are presented. These methods are based on plane wave decomposition made at the inlet and at the outlet of the system. This decomposition is made according beamforming technique. Once these methods were validated on simple geometries, they were then applied to the compressor stage of an automotive turbocharger. The active acoustic characterization is made by the measurement of the acoustic power and acoustic intensity in the compressor ducts on given working points, but also on complete compressor maps. This was performed on turbocharger benches, engine benches and a complete vehicle. The passive acoustic characterization is made by the calculation of characteristic matrices (transfer matrix, impedance matrix and scattering matrix). These matrices are then used to compute the acoustic transmission loss. Experiments were performed on a static turbocharger and compared to 3D finite elements simulations, as well as experiments on an operating turbocharger

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Pizarro, Luzia Maria Pozzobom Ventura. "Maturação cortical e habilidades auditivas em usuários experientes de Vibrant Soundbridge: estudo eletrofisiológico e comportamental". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/5/5143/tde-27092018-084134/.

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Introdução: A atresia congênita de orelha constitui uma deformidade presente ao nascimento, de prevalência unilateral, decorrente da alteração no desenvolvimento das estruturas das orelhas externa e média. Geralmente, provoca perda auditiva condutiva, e pode ser acompanhada por componente sensorioneural. Dentre as formas de tratamento disponíveis, encontra-se o implante de orelha média Vibrant Soundbridge (VSB), que tem se mostrado eficaz no tratamento deste tipo de alteração. A literatura mostra melhora nos limiares tonais e nos resultados dos testes de percepção auditiva da fala, realizados com o uso do processador de fala após a cirurgia. Considerando que os indivíduos com este tipo de malformação podem passar por um período de privação sensorial auditiva anterior à reabilitação, torna-se interessante avaliar o estágio maturacional das estruturas auditivas corticais e o processamento das informações auditivas em nível central, bem como, verificar o benefício da indicação do VSB unilateral em situação de escuta difícil. Não foram encontrados estudos que abordam este aspecto e o emprego dos potenciais evocados auditivos corticais (PEAC) e do P300 em usuários de VSB. Objetivo: Analisar o impacto da perda auditiva condutiva e mista nos PEAC e P300 em usuários de VSB unilateral, com atresia de orelha bilateral, e verificar as habilidades auditivas, em situação de escuta difícil, considerando a indicação do VSB unilateral. Casuística e método: Vinte indivíduos, divididos em dois grupos, pareados em idade, sexo e grau de escolaridade. G1: dez indivíduos com perda auditiva condutiva ou mista bilateral, usuários de VSB unilateral, atendidos na Instituição de realização da pesquisa. Todos fizeram uso de aparelhos auditivos convencionais antes do VSB. G2: Dez indivíduos normo-ouvintes. Realização de audiometria em campo livre com o uso do VSB (apenas o G1), avaliação das habilidades auditivas pelo Hearing in Noise Test, pesquisa dos componentes P1, N1, P2, N2 e P300, em campo calibrado. Resultados: A média dos limiares tonais nas frequências de 500 a 3000 Hz, de 20 a 36 dB NA, mostrou que o VSB possibilitou o acesso aos sons da fala. Não foi observada diferença estatisticamente significante entre os valores de latência dos PEAC e P300 entre os grupos. Foi observada diferença estatisticamente significante entre o limiar de reconhecimento de sentenças e a relação sinal/ruído entre os grupos, sendo os melhores resultados apresentados pelo G2. Conclusão: Indivíduos com atresia de orelha e perda auditiva condutiva ou mista bilateral, quando adequadamente reabilitados, podem atingir a maturação das vias auditivas centrais e o processamento da informação auditiva em nível cortical. As habilidades de reconhecimento auditivo, sem e com ruído competitivo, mostraram-se defasadas quanto à normalidade, apontando para a indicação do VSB bilateral
Introduction: Congenital aural atresia is a congenital deformity. It is unilaterally prevalent due to alterations in the development of the external and middle ear structures. Congenital aural atresia causes conductive hearing loss and can be accompanied by sensorineural component. Among the available forms of treatment is the middle ear implant, Vibrant Soundbridge (VSB), which has been shown to be effective in treating this type of alteration. The literature shows improvement in tonal thresholds and in the results of tests of auditory perception of speech that were performed using the speech processor after surgery. Individuals with this type of malformation often experience a period of auditory sensory deprivation prior to rehabilitation. Hence, it is important to evaluate the maturation stage of the cortical auditory structures, the processing of auditory information at the central level, and to verify the benefit of unilateral VSB in difficult listening situations. There are no previous data on this aspect and with the use of cortical auditory evoked potentials (CAEP) and event-related potential (P300) in users of VSB. Aim: To analyze the impact of conductive and mixed hearing loss on CAEP and P300 in unilateral VSB users with bilateral ear atresia. To verify the auditory abilities in a difficult listening situation considering the indication for unilateral VSB. Materials and methods: Twenty individuals were divided into two groups matched for age, sex, and educational level. G1 comprised ten individuals with bilateral conductive or mixed hearing loss and users of unilateral VSB, who visited the research institution. All subjects used conventional hearing aids prior to VSB. G2 comprised ten normal hearing individuals. Audiometry in the free field was performed with the use of VSB (G1 only) and evaluation of hearing skills by the Hearing in Noise Test was conducted; components P1, N1, P2, N2, and P300 in a calibrated field were recorded. Results: Evaluation of the mean tonal thresholds in the frequencies between 500 and 3000 Hz, from 20 to 36 dB HL, demonstrated that VSB allowed access to speech sounds. There was no statistically significant difference in the CAEP and P300 latency values between the two groups. A statistically significant difference was observed in the sentence recognition threshold and the signal-to-noise ratio between the groups, with best results presented by G2. Conclusion: Individuals with congenital aural atresia and bilateral conductive or mixed hearing loss may reach maturation of the central auditory pathway and achieve adequate processing of auditory information at the cortical level, when rehabilitated. The auditory recognition skills, with and without competitive noise, were shown to be out of phase with normality, indicating the need for a bilateral VSB

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39

Pai, Ruby J. "Nonadaptive lossy encoding of sparse signals". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/41623.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.
Includes bibliographical references (p. 67-68).
At high rate, a sparse signal is optimally encoded through an adaptive strategy that finds and encodes the signal's representation in the sparsity-inducing basis. This thesis examines how much the distortion rate (D(R)) performance of a nonadaptive encoder, one that is not allowed to explicitly specify the sparsity pattern, can approach that of an adaptive encoder. Two methods are studied: first, optimizing the number of nonadaptive measurements that must be encoded and second, using a binned quantization strategy. Both methods are applicable to a setting in which the decoder knows the sparsity basis and the sparsity level. Through small problem size simulations, it is shown that a considerable performance gain can be achieved and that the number of measurements controls a tradeoff between decoding complexity and achievable D(R).
by Ruby J. Pai.
M.Eng.

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40

Kim, Hyunsu. "Transmission loss of silencers with flow from a flow-impedance tube using burst signals". The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1320338533.

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Afifi, Mohammed Ahmed Melegy Mohammed. "TCP FTAT (Fast Transmit Adaptive Transmission): A New End-To- End Congestion Control Algorithm". Cleveland State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=csu1414689425.

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42

Luo, Meiling. "Indoor radio propagation modeling for system performance prediction". Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00961244.

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This thesis aims at proposing all the possible enhancements for the Multi-Resolution Frequency-Domain ParFlow (MR-FDPF) model. As a deterministic radio propagation model, the MR-FDPF model possesses the property of a high level of accuracy, but it also suffers from some common limitations of deterministic models. For instance, realistic radio channels are not deterministic but a kind of random processes due to, e.g. moving people or moving objects, thus they can not be completely described by a purely deterministic model. In this thesis, a semi-deterministic model is proposed based on the deterministic MR-FDPF model which introduces a stochastic part to take into account the randomness of realistic radio channels. The deterministic part of the semi-deterministic model is the mean path loss, and the stochastic part comes from the shadow fading and the small scale fading. Besides, many radio propagation simulators provide only the mean power predictions. However, only mean power is not enough to fully describe the behavior of radio channels. It has been shown that fading has also an important impact on the radio system performance. Thus, a fine radio propagation simulator should also be able to provide the fading information, and then an accurate Bit Error Rate (BER) prediction can be achieved. In this thesis, the fading information is extracted based on the MR-FDPF model and then a realistic BER is predicted. Finally, the realistic prediction of the BER allows the implementation of the adaptive modulation scheme. This has been done in the thesis for three systems, the Single-Input Single-Output (SISO) systems, the Maximum Ratio Combining (MRC) diversity systems and the wideband Orthogonal Frequency-Division Multiplexing (OFDM) systems.

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43

Lu, Yilong. "The finite element solution of inhomogeneous anisotropic and lossy dielectric waveguides". Thesis, University College London (University of London), 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268886.

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44

Deghdegh, Khireddine. "Étude des paramètres du signal E. M. G. Associé à des exercices dynamiques : caractérisation de la fatigue lors de tests sur cycloergomètre". Lyon 1, 1998. http://www.theses.fr/1998LYO10107.

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Cette étude a pour objectif d'analyser les variations cinématiques et électromyographiques survenant lors de la répétition de sprints sur cycloergomètre. L'expérimentation porte sur l'analyse des prélèvements EMG de quatre muscles de la jambe (biceps femoris, gastrocnemius medialis, vastus lateralis, rectus femoris) combinés à l'électrogoniométrie du genou au cours d'un protocole de fatigue basé sur une série de quinze sprints. L'étude effectuée par le biais de diverses méthodes de traitement du signal a porté sur trois axes : la caractérisation de la fatigue musculaire, la corrélation des grandeurs caractéristiques du signal EMG aux données mécaniques et enfin l'analyse de la coordination intermusculaire au cours du mouvement poly-articulaire. Les évolutions des grandeurs temporelles et fréquentielles du signal EMG ainsi que les coefficients du modèle autorégressif sont analysées et discutées. Il ressort que ces paramètres constituent des arguments en faveur d'une caractérisation de la fatigue musculaire au cours du mouvement dynamique. Ainsi plusieurs aspects de la sensibilité des parmètres EMG liés à la fatigue musculaire lors de la répétition de sprints sont mis en évidence. L'examen des patterns d'activation des muscles et l'évolution des paramètres d'amplitude démontrent une sollicitation différente selon qu'il s'agit d'un muscle mono- ou biarticulaire. La séquence temporelle qui caractérise le recrutement des différents muscles fait apparaître son indépendance vis-à-vis de la fatigue musculaire. Si la diminution de la puissance mécanique est corrélée au pourcentage de fibres rapides ou (vastus lateralis) aucune relation ne semble lier cette typologie aux variations des paramètres du signal EMG. Nous nous sommes également intéressés aux représentations temps-fréquence du signal EMG. La qualité descriptive que nous offrent quelques-unes permet d'envisager leurs utilisations comme complément intéressant à l'étude de l'EMG au cours de l'exercice dynamique.

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Goldschneider, Jill R. "Lossy compression of scientific data via wavelets and vector quantization /". Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/5881.

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EL, HARAOUI MOHAMED. "Etude du signal emg : confrontation avec les parametres cardio respiratoires lors d'une epreuve d'effort". Amiens, 1997. http://www.theses.fr/1997AMIE0117.

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Le but de cette etude est d'automatiser la recuperation et le traitement des signaux cardio-respiratoires et electromyographiques (emg) chez les enfants prepuberes durant une epreuve d'effort. Il s'agit en particulier de determiner les seuils ventilatoires et de rechercher les relations entre le signal emg et la reponse ventilatoire afin d'approcher la determination des seuils ventilatoires par des methodes moins invasives. Pour cela deux algorithmes ont ete developpes (pentes, em : erreur minimum) et deux autres ont ete adaptes (dmax : distance maximale, df : derivee filtree). Sept enfants sains de sexe masculin, ages de 9 a 11 ans, de taille 1489 cm, de poids 34. 57 kg, ont participe a cette etude. L'ensemble des sujets avait realise une epreuve d'effort incrementale sur ergocycle a frein electromagnetique. L'augmentation continue de la puissance etait realisee selon un protocole de 20 watts. Mn 1 avec une frequence de pedalage de 60 rpm. Au cours de chaque epreuve, la ventilation pulmonaire (ve, 1. Mn 1), la production en dioxyde de carbone (vco 2, 1. Mn 1), la consommation d'oxygene (vo 2, ml. Kg 1. Mn 1) et la frequence cardiaque (fc) ont ete mesurees. A partir de ces variables, les equivalents respiratoires en oxygene (eo 2 = ve. Vco 2 1) et en dioxyde de carbone (eco 2 = ve. Vco 2 1) ont ete calcules. Simultanement, le signal emg de surface du muscle vaste externe a ete detecte en bipolaire, amplifie et enregistre par l'intermediaire d'une carte d'acquisition. A l'issue de chaque epreuve, les seuils ventilatoires, transition aerobie-anaerobie, ont ete determines, selon les criteres de wassermann (sv1 et sv2) et de beaver (sb1 et sb2), a partir des cassures detectees par les algorithmes de pentes, de la df, de em et de dmax, dans les courbes d'evolution de ve, eo 2 et eco 2 en fonction de l'augmentation de la puissance (w, watt). De la meme maniere, des cassures sur la courbe d'augmentation de l'energie efficace (rms) du signal emg ont ete determinees (semg1 et semg2) a l'aide de ces memes algorithmes iteratifs. Les resultats ne montrent pas de difference significative entre les seuils anaerobie et de decompensation de l'acidose metabolique determines par les criteres de wassermann, de beaver et les seuils emg. L'analyse de la regression lineaire n'a pas montre de correlation significative entre sv1 et semg1. Par contre, une correlation significative a ete obtenue entre semg1 et sb1 (vo 2:r = 0. 75, p = 0. 05 par df et vo 2:r = 0. 9, p = 0. 001 par em). Des coefficients de correlation eleves ont ete, egalement, obtenus entre sv2 et semg2 (vo 2 : r = 0. 85, p = 0. 01 par em et fc = 0. 86, p = 0. 01 par df). En conclusion, les algorithmes utilises ont permis une objectivite satisfaisante pour la determination des seuils au cours d'un exercice incremental. De plus, les resultats concernant le signal emg apparaissent suffisamment discriminatoires pour approcher la zone de transition aerobie-anaerobie.

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47

Ibata, Ombetta Stella. "Signalisation et régulation des fonctions cellulaires induites lors de Candida albicans avec le macrophage". Lille 2, 2003. http://www.theses.fr/2003LIL2MT15.

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48

Rocha, Clayton Henrique. "Inteligibilidade de fala em trabalhadores expostos a ruído com protetores auditivos". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/5/5170/tde-09082017-123419/.

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Introdução: O ruído é um dos principais agentes de poluição ambiental, que em intensidades elevadas, poderá causar a perda auditiva induzida por níveis de pressão sonora elevadas (PAINPSE). A PAINPSE é o segundo tipo de perda auditiva neurossensorial mais frequente, e considerada uma das principais doenças ocupacionais. Para evitar os prejuízos da exposição ao ruído ocupacional, legislações determinam o monitoramento e o desenvolvimento de ações para reduzir os efeitos da exposição, sendo o uso de dispositivos de proteção auditiva (DPA) a mais empregada. Contudo é comum que o trabalhador relate dificuldades para se comunicar com o DPA, o que pode induzi-lo ao uso inadequado. Os estudos já realizados apresentam discordâncias sobre os efeitos do DPA para a inteligibilidade da fala, além de serem poucos os que compararam participantes com perdas auditivas com normo-ouvintes. Objetivos: Avaliar a inteligibilidade de fala em trabalhadores expostos a ruído durante o uso de DPA. Métodos: Trata-se de um estudo transversal, aprovado pelo Comitê de Ética em Pesquisa da instituição nº 130/14, com amostra de 36 participantes, todos do sexo masculino e expostos ao ruído. Foram divididos em grupo normo-ouvintes (G1), com 20 participantes e com perda auditiva (G2), com 16 participantes. Todos os participantes realizaram avaliação da inteligibilidade de fala em campo acústico, utilizando listas de monossílabas e sentenças, em situações de uso do DPA no silêncio e no ruído e sem o uso do DPA no ruído. Resultados: Na avaliação da inteligibilidade de fala com DPA utilizando as monossílabas, ambos os grupos apresentaram porcentagens de acertos superiores à 95% na situação de silêncio. Na presença do ruído com o DPA, não foi detectado efeito de interação envolvendo grupo (p>=0,106) e nem efeito de grupo (p=0,182), mas houve efeito de interação entre intensidade de fala e relação sinal/ruído (S/R) (p=0,006). Na avaliação da inteligibilidade de fala no ruído sem o DPA, foi detectado efeito de interação entre uso do DPA e relação S/R (p=0,010) sobre a média das porcentagens de acertos. Na avaliação com listas de sentenças, a porcentagem de acertos com DPA foram superiores a 98% no silêncio; contudo, no ruído houve piora, com efeito de interação entre intensidade de fala e relação S/R (p=0,010) e entre grupo e relação S/R (p=0,039). Na comparação do uso/não uso do DPA, houve efeito de interação entre uso do DPA e as relações S/R (p=0,009) sobre a média das porcentagens de acertos. Conclusões: Para ambos os grupos, houve piora da inteligibilidade de fala com o aumento da intensidade do ruído; contudo, a dificuldade foi maior para o G2. Na comparação das situações com/sem o uso do DPA, o uso dificultou a inteligibilidade de fala, mas não houve diferença significante entre as situações. Por fim, ressalta-se a importância de realizar mais estudos dos efeitos do DPA na comunicação, além de inserir nas avaliações ocupacionais testes que avaliam a fala no ruído, para determinar as dificuldades que podem surgir no ambiente ocupacional, e assim desenvolver medidas que beneficiem os trabalhadores que necessitam se comunicar durante as atividades laborais
Introduction: Noise is one of the main agents of environmental pollution, and at high intensities, it may provoke noise-induced hearing loss (NIHL). NIHL is the second most frequent type of sensorineural hearing loss and it is considered one of the main occupational diseases. In order to avoid the effects of the exposition to occupational noise, legislation determines the monitoring and development of actions to reduce the effects of such exposure and one of the most applied measure is the mandatory use of hearing protection devices (HPD). However, workers often report difficulties to communicate when using the HPD, what may induce them to use it improperly. Previous studies showed divergences between the effects of HPD on speech intelligibility; besides, few studies compared participants with hearing loss to those with normal hearing. Purpose: To assess speech intelligibility of workers exposed to noise during the use of HPD. Methods: This is a cross-sectional study, approved by the Institution\'s Ethics Committee (nº 130/14) and counted on a sample of 36 participants, all males and exposed to noise. They were distributed into a normal hearing group (G1), with 20 participants and hearing loss group (G2), with 16 participants. All participants were submitted to an assessment of speech intelligibility in free field, using monosyllable and sentence lists, when using the HPD in silence and noise situation, and also without the use of HPD in noise. Results: In the assessment of speech intelligibility with HPD using the monosyllables, both groups presented percentages of correct answers above 95%. In the presence of noise with HPD, there was no interaction effect involving group (p>=0.106) or group effect (p=0.182), but there was found an interaction effect between speech intensity and signal-to-noise ratio (SNR) (p=0.006). In the assessment of speech intelligibility in noise without HPD, an interaction effect between HPD use and SNR (p=0.010) was detected over the mean percentage of correct answers. In the evaluation with lists of sentences, the percentage of correct answers with HPD were superior to 98% in the silence; however, in noise, there was a decrease on the interaction effect between speech intensity and SNR (p = 0.010) and between group and SNR (p = 0.039). In the comparison with/without use of HPD, there was found an interaction effect between hearing protection use and SNR (p = 0.009) on the mean percentage of correct answers. Conclusions: For both groups, it was noticed that speech intelligibility decrease with the increasing of noise intensity; nevertheless, the difficulty was greater for the group with hearing loss. In the comparison of situations with and without the use of HPD, its use made speech intelligibility more challenging, but no significant difference between the situations was found. Finally, it is important to highlight the importance of further studies regarding the effects of HPD on communication and, besides, inserting speech-in-noise tests in occupational examination in order to determine the difficulties that may arise in the occupational environment and thus, develop measures that benefits the workers who need communicate during their labor activities

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Lohard, Steven. "Propagation d'un signal pro-apoptotique paracrine via la voie cGAS/STING lors des chimitothérapies antimitotiques". Thesis, Nantes, 2019. http://www.theses.fr/2019NANT1004/document.

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Une action fascinante mais non caractérisée de la chimiothérapie antimitotique consiste à induire une apoptose mitochondriale collective, bien que n’impactant que la sous-population cellulaire proliférante. Nous montrons ici que les réponses apoptotiques aiguës au paclitaxel de cultures organotypiques de tumeurs mammaires humaines et de xénogreffes dérivées de patientes s’associent à des signatures d’expression génique marquant une exposition au TNFα et aux IFN de type I. Ces cytokines sont sécrétées par les cellules cancéreuses présentant des micronoyaux induits par le traitement antimitotique et détectés par le senseur de l'ADN cytosolique cGAS et conservant une intégrité mitochondriale malgré la pression apoptotique intrinsèque au traitement antimitotique. Ces cytokines déclenchent dans les cellules tumorales voisines l’expression de NOXA, inhibiteur de MCL-1, responsable d’un effet pro-apoptotique paracrine révélé par une sensibilisation au BH3 mimétiques ciblant BCL-xL. Cet effet dépendant de la voie cGAS/STING est nécessaire pour la réponse au paclitaxel in vivo, qui est elle-même amplifiée par l'administration séquentielle, mais non synchrone, de BH3 mimétiques ciblant BCL-xL
A fascinating but uncharacterized action of anti-mitotic chemotherapy is to collectively prime cancer cells to apoptotic mitochondrial outer membrane permeabilization (MOMP), while impacting only on cycling cell subsets. Here, we show that acute apoptotic responses to paclitaxel of organotypic cultures of primary human breast tumors and of patient-derived xenografts associate with gene expression signatures marking exposure to type I IFN and TNFα. These cytokines are secreted by micronuclei-positive cGAS/STING-active cancer cells maintaining mitochondrial integrity despite intrinsic apoptotic pressure during anti-mitotic treatment. In turn, they trigger pro-apoptotic NOXA expression in neighboring cells. STING-dependent apoptotic effects are required for paclitaxel response in vivo, and they are amplified by sequential, but not synchronous, administration of BH3 mimetics

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Muto, Shunsuke, e Yusuke Sasano. "Energy-drift correction of electron energy-loss spectra from prolonged data accumulation of low SNR signals". Oxford University Press, 2008. http://hdl.handle.net/2237/20779.

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