Дисертації з теми "Natural sources of sound"
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1
Bolin, Karl. "Wind Turbine Noise and Natural Sounds : Masking, Propagation and Modeling." Doctoral thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10434.
Повний текст джерелаАнотація:
Wind turbines are an environmentally friendly and sustainable power source. Unfortunately, the noise impact can cause deteriorated living conditions for nearby residents. The audibility of wind turbine sound is influenced by ambient sound. This thesis deals with some aspects of noise from wind turbines. Ambient sounds influence the audibility of wind turbine noise. Models for assessing two commonly occurring natural ambient sounds namely vegetation sound and sound from breaking waves are presented in paper A and B. A sound propagation algorithm has been compared to long range measurementsof sound propagation in paper C. Psycho-acoustic tests evaluating the threshold and partial loudness of wind turbine noise when mixed with natural ambient sounds have been performed. These are accounted for in paper D. The main scientific contributions are the following.Paper A: A semi-empiric prediction model for vegetation sound is proposed. This model uses up-to-date simulations of wind profiles and turbulent wind fields to estimate sound from vegetation. The fluctuations due to turbulence are satisfactory estimated by the model. Predictions of vegetation sound also show good agreement to measured spectra. Paper B: A set of measurements of air-borne sound from breaking waves are reported. From these measurements a prediction method of sound from breaking waves is proposed. Third octave spectra from breaking waves are shown to depend on breaker type. Satisfactory agreement between predictions and measurements has been achieved. Paper C: Long range sound propagation over a sea surface was investigated. Measurements of sound transmission were coordinated with local meteorological measurements. A sound propagation algorithm has been compared to the measured sound transmission. Satisfactory agreement between measurements and predictions were achieved when turbulence were taken into consideration in the computations. Paper D: The paper investigates the interaction between wind turbine noise and natural ambient noise. Two loudness models overestimate the masking from two psychoacoustic tests. The wind turbine noise is completely concealed when the ambient sound level (A-weighed) is around 10 dB higher than the wind turbine noise level. Wind turbine noise and ambient noise were presented simultaneously at the same A-weighed sound level. The subjects then perceived the loudness of the wind turbine noise as 5 dB lower than if heard alone. Keywords: Wind turbine noise, masking, ambient noise, long range sound propagationQC 20100705
2
Norris, Richard. "An exploration of cross-genre composition focusing on the combination of natural and synthetic sound sources." Thesis, Royal Holloway, University of London, 2012. http://repository.royalholloway.ac.uk/items/2837960b-20e0-9ec8-dd40-ec05067f86de/11/.
Повний текст джерелаАнотація:
This portfolio explores a combination of acoustic performance with technology in various guises, including the use of backing tracks alongside an ensemble, the manipulation of live instruments with effects and the use of synthesizers and samplers along with an instrumental ensemble. A key feature that runs through the portfolio is the use of specific non-musical subject themes as inspiration for the music. These include the murders of five prostitutes in Ipswich in 2006 by Steve Wright, a speech by David Davis on people trafficking from 2005, the Mumbai hostage situation and bombings of 2007, drug culture and the sounds of London. A large proportion of the pieces that make up this portfolio have contributed to a fusion album entitled Opposites React. This album explores how acoustic performance can be combined with electronics and includes performances and collaborations with performers, poets, producers and visual artists.
3
Комлєва, Поліна Максимівна. "Особливості запису окремих натуральних джерел звукових сигналів в залежності від жанру створюваної програми". Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/34885.
Повний текст джерелаАнотація:
Дипломна робота: 69 c., 2 табл., 19 рис., 31 джерел.
Об'єктом дослідження є натуральні, електромузичні інструменти та особливості їх запису.
Метою роботи є аналіз акустичних характеристик інструментів та процеси їх запису.
Метод дослідження – досліджено запис натуральних та електричних інструментів в залежності від стилю музики та акустичного обладнання.
Галузь застосування: студії звукозапису, концертні зали.69 pp., 2 tab., 19 figures, 31 sources. The object of research are natural, electromusical instruments and features of their recording. The aim of the work is to analyze the acoustic characteristics of instruments and their recording processes. Research method - the recording of natural and electric instruments depending on the style of music and acoustic equipment was studied. Field of application: recording studios, concert halls. As a result of the thesis, the recording of natural and electric instruments depending on the style of music and acoustic equipment was studied.
4
Di, Bona Elvira. "Sound and sound sources." Paris, EHESS, 2013. http://www.theses.fr/2013EHES0058.
Повний текст джерелаАнотація:
Dans cette thèse je vais proposer une théorie de la perception auditive selon laquelle les sons sont strictement attachés aux objets matériels qui sont leurs sources. Dans le Chapitre l, je propose une taxonomie des théories du son. Ma taxonomie range les théories du son dans quatre catégories : le groupe minimaliste, le groupe modéré, le groupe maximaliste et le groupe plus-que-maximaliste. Dans le Chapitre II, je fais deux choses: je traite des questions sur l'a-spatialité de la perception auditive, et ensuite, je caractérise la relation entre les sources sonores et les sons. Par ailleurs, mon intention est de justifier le point de vue maximaliste en défendant une nouvelle théorie du son comme événement vibratoire qui arrive aux sources sonores. Dans le Chapitre III e IV je m'occupe des qualités sonores du son qui sont la hauteur, l'intensité, le timbre, la durée et la location. En générale, je vais montrer que non seulement les qualités sonores peuvent être considérées comme des contreparties perceptibles des propriétés physiques des ondes sonores dans un milieu, mais qu'elles sont aussi en corrélation avec les propriétés physiques de la vibration de l'objet sonore. L'objectif du Chapitre V est d'aborder le problème de la perception directe du son et des sources sonores. En particulier, je vais prétendre que mon analyse des qualités sonores -qui prête une attention particulière au timbre -et la caractérisation du son comme événement source nous permet de conclure que nous pouvons entendre directement les sources sonores -et que nous pouvons, donc, justifier la vue maximaliste. Dans l'Excursus j'évalue la possibilité auditive de percevoir la causalitéLn this dissertation I defend two theses: the "identity view" and the "maximalist view". According to the first thesis, when we hear sounds, we hear also events and happenings which occur at the sources where sounds have been produced. According to the second thesis, our auditory landscape is constituted by sounds which not only are identical to the audible events occurring at sound sources, but they are also the tools which help us to recover information about the material objects which generate sound. This dissertation is composed by five chapters and an Excursus. In Chapter 1, I propose a taxonomy of sound theories. My taxonomy organises sound theories into four groups: the minimalist group, the moderate group, the maximalist group and the overmaximalist group. In Chapter Il, I deal with issues on the a-spatiality of auditory perception, in the attempt to demonstrate that we hear sound as co-Iocated with sound sources. Furthermore, I define the relation between sound sources and their sounds and justify the identity view by virtue of the distinction between two aspects of sound sources -the thing source (such as bells or violins) and the event source (such as collisions or vibratory events at the object). In Chapters III and IV, I tackle the problem of the audible qualities of sound (pitch, loudness, timbre, duration and location) in the light of the characterization of sound as event source. The objective of the last chapter is the problem of the direct perception of sound and sound sources in the light of the considerations made in the previous chapters. I add an Excursus in which I evaluate the possibility of perceiving causality by audition
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Dong, Bin. "Spatial Separation of Sound Sources." Phd thesis, INSA de Lyon, 2014. http://tel.archives-ouvertes.fr/tel-01059653.
Повний текст джерелаАнотація:
La séparation aveugle de sources est une technique prometteuse pour l'identification, la localisation, et la classification des sources sonores. L'objectif de cette thèse est de proposer des méthodes pour séparer des sources sonores incohérentes qui peuvent se chevaucher à la fois dans les domaines spatial et fréquentiel par l'exploitation de l'information spatiale. De telles méthodes sont d'intérêt dans les applications acoustiques nécessitant l'identification et la classification des sources sonores ayant des origines physiques différentes. Le principe fondamental de toutes les méthodes proposées se décrit en deux étapes, la première étant relative à la reconstruction du champ source (comme par exemple à l'aide de l'holographie acoustique de champ proche) et la seconde à la séparation aveugle de sources. Spécifiquement, l'ensemble complexe des sources est d'abord décomposé en une combinaison linéaire de fonctions de base spatiales dont les coefficients sont définis en rétropropageant les pressions mesurées par un réseau de microphones sur le domaine source. Cela conduit à une formulation similaire, mais pas identique, à la séparation aveugle de sources. Dans la seconde étape, ces coefficients sont séparés en variables latentes décorrélées, affectées à des "sources virtuelles" incohérentes. Il est montré que ces dernières sont définies par une rotation arbitraire. Un ensemble unique de sources sonores est finalement résolu par la recherche de la rotation (par gradient conjugué dans la variété Stiefel des matrices unitaires) qui minimise certains critères spatiaux, tels que la variance spatiale, l'entropie spatiale, ou l'orthogonalité spatiale. Il en résulte la proposition de trois critères de séparation à savoir la "moindre variance spatiale", la "moindre entropie spatiale", et la "décorrélation spatiale", respectivement. De plus, la condition sous laquelle la décorrélation classique (analyse en composantes principales) peut résoudre le problème est établit de une manière rigoureuse. Le même concept d'entropie spatiale, qui est au coeur de cette thèse, est également iv exploité dans la définition d'un nouveau critère, la courbe en L entropique, qui permet de déterminer le nombre de sources sonores actives sur le domaine source d'intérêt. L'idée consiste à considérer le nombre de sources qui réalise le meilleur compromis entre une faible entropie spatiale (comme prévu à partir de sources compactes) et une faible entropie statistique (comme prévu à partir d'une faible erreur résiduelle). La méthode proposée est validée à la fois sur des expériences de laboratoire et des données numériques et illustrée par un exemple industriel concernant la classification des sources sonores sur la face supérieure d'un moteur Diesel. La méthodologie peut également séparer, de façon très précise, des sources dont les amplitudes sont de 40 dB inférieur aux sources les plus fortes. Aussi, la robustesse vis-à-vis de l'estimation du nombre de sources actives, de la distance entre le domaine source d'intérêt et le réseau de microphones, ainsi que de la taille de la fonction d'ouverture est démontrée avec succès.
6
Lee, JungSuk. "Categorization and modeling of sound sources for sound analysis/synthesis." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116954.
Повний текст джерелаАнотація:
In this thesis, various sound analysis/re-synthesis schemes are investigated in a source/filter model framework, with emphasis on the source component. This research provides improved methods and tools for sound designers, composersand musicians to flexibly analyze and synthesize sounds used for gaming, film or computer music, ranging from abstract, complex sounds to those of real musical instruments. First, an analysis-synthesis scheme for the reproduction of a rolling ball sound is presented. The proposed scheme is based on the assumption that the rolling sound is generated by a concatenation of micro-contacts between a ball and a surface, each having associated resonances. Contact timing information is extracted from the rolling sound using an onset detection process, allowing for segmentation of a rolling sound. Segmented sound snippets are presumed to correspond to micro-contacts between a ball and a surface; thus, subband based linear predictions (LP) are performed to model time-varying resonances and anti-resonances. The segments are then resynthesized and overlap-added to form a complete rolling sound. A "granular" analysis/synthesis approach is also applied to various kinds of environmental sounds (rain, fireworks, walking, clapping) as an additional investigation into how the source type influences the strategic choices for the analysis/synthesis of sounds. The proposed granular analysis/synthesis system allows for flexible analysis of complex sounds and re-synthesis with temporal modification. Lastly, a novel approach to extract a pluck excitation from a recorded plucked string sound is proposed within a source / filter context using physical models. A time domain windowing method and an inverse filtering-based method are devised based on the behavior of wave propagation on the string. In addition, a parametric model of the pluck excitation as well as a method to estimate its parameters are addressed.Dans cette thèse, nous avons étudié plusieurs scéhmas d'analyse/synthèse dans le cadre des modèles source/filtre, avec un attention particulière portée sur la composante de source. Cette recherche améliore les méthodes ainsi que les outils fournis créateurs de sons, compositeurs et musiciens désirant analyser et synthétiser avec flexibilité des sons destinés aux jeux vidéos, au cinéma ou à la musique par ordinateur. Ces sons peuvent aller de sons abstraits et complexes à ceux provenant d'instruments de musique existants. En premier lieu, un schéma d'analyse-synthèse est introduit permettant la reproduction du son d'une balle en train de rouler. Ce schéma est fondé sur l'hypothèse que le son de ce roulement est généré par la concaténation de micro-contacts entre balle et surface, chacune d'elles possédant sa proper série de résonances. L'information relative aux temps de contact est extradite du son du roulement que l'on cherche à reproduire au moyen d'une procédure détectant le début du son afin de le segmenter. Les segments de son ainsi isolés sont supposés correspondre aux micro-contacts entre la balle et la surface. Ainsi un algorithme de prédiction linéaire est effectué par sous-bande, préalablement extraites afin de modéliser des résonances et des anti-résonances variants dans le temps. Les segments sont ensuite re-synthétisés, superposés et additionnés pour reproduire le son du roulement dans son entier. Cette approche d'analyse/synthèse "granulaire" est également appliquée à plusieurs sons de types environnementaux (pluie, feux d'artifice, marche, claquement) afin d'explorer plus avant l'influence du type de la source sur l'analyse/synthèse des sons. Le système proposé permet une analyse flexible de sons complexes et leur synthèse, avec la possibilité d'ajouter des modifications temporelles.Enfin, une approche novatrice pour extraire le signal d'excitation d'un son de corde pincée est présentée dans le contexte de schémas source/filtre sur une modèlisation physique. A cet effet, nous introduisons une méthode de type fenêtrage, et une méthode de filtrage inverse fondée sur le type de propagation selon laquelle l'onde se déplace le long de la corde. De plus, un modèle paramétrique de l'excitation par pincement ainsi qu'une méthode d'estimation de ces paramètres sont détaillés.
7
Boyle, M. V. "The characterisation of complex sound sources." Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546011.
Повний текст джерела
8
Ito, Masanori, Yoshinori Takeuchi, Tetsuya Matsumoto, Hiroaki Kudo, and Noboru Ohnishi. "Blind Signal Separation of Moving Sound Sources." INTELLIGENT MEDIA INTEGRATION NAGOYA UNIVERSITY / COE, 2004. http://hdl.handle.net/2237/10347.
Повний текст джерела
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Thite, Anand Narasinha. "Inverse determination of structure-borne sound sources." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273993.
Повний текст джерела
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Saussus, Patrick T. "Investigation into sound sources for anechoic chamber qualification and related sound issues." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/17910.
Повний текст джерела
11
Wei, Wei. "Underwater measurement of the sound-intensity vector : its use in locating sound sources, and in measuring the sound power of stationary and moving sources /." Full text available from ProQuest UM Digital Dissertations, 1994. http://0-proquest.umi.com.umiss.lib.olemiss.edu/pqdweb?index=0&did=1296083321&SrchMode=1&sid=4&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1268675088&clientId=22256.
Повний текст джерелаАнотація:
Thesis (Ph.D.)--University of Mississippi, 1994.Typescript. "May 1994 ." Dissertation director: Dr. Robert Hickling Committee chair: Dr. Richard Raspet Includes bibliographical references (leaves 115-118). Also available online via ProQuest to authorized users.
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Lievens, Matthias [Verfasser]. "Structure-borne sound sources in buildings / Matthias Lievens." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1048084930/34.
Повний текст джерела
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Späh, Moritz Michael. "Characterisation of structure-borne sound sources in buildings." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428229.
Повний текст джерела
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Elliott, Andrew S. "Characterisation of structure borne sound sources in-situ." Thesis, University of Salford, 2009. http://usir.salford.ac.uk/26661/.
Повний текст джерелаАнотація:
In theory it should be possible to characterise a vibration source's active and passive properties in an independent way which allows for structure borne sound to be predicted for a source in different installations. When put into practice however, the independent source characterisation approach often results in sur- prisingly poor predictions of source behaviour for the installed condition. The exact cause of the error is currently unknown but is often attributed to the practi- cal difficulties encountered when measuring source properties and hence numerical instabilities resulting from poor quality or unrepresentative data. Here we ad- dress the problem of obtaining independent descriptions of a source's active and passive properties using in-situ measurement approaches. In-situ measurements may be advantageous because the hypothetical quantities required for indepen- dent source characterisation are on the whole unmeasurable and hence elaborate measurements are often required to obtain an approximate source description. It will be shown that the independent blocked force, describing the activity of a vibration source under a blocked condition, can be measured in-situ and that the in-situ blocked force can be used to predict source behaviour in different environ- ments including a free condition. It will also be shown that the in-situ blocked force approach may allow for a transfer path analysis to be performed without dismantling the source-receiver assembly and thus allowing for a significant time saving. To address the characterisation of passive source properties two methods for the in-situ measurement of mobilities are described and investigated. Overall it is shown that active, and possibly passive, properties of vibration sources can be independently characterised whilst a source is installed and that there may be significant benefits in doing so. For example measurements may be faster or easier and the data obtained may be more representative.
15
Litwic, Lukasz. "Separation of sound sources : a machine audition perspective." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/808813/.
Повний текст джерелаАнотація:
Speech separation by machines has been extensively studied for many decades and several algorithms and systems have been proposed. Since the speech separation task for machines is often likened to the speech separation task performed (remarkably well) by the human auditory system several analogies can be found in the proposed systems. This thesis takes a localised view on a few of the aspects of the speech separation task and explores some of the analogies from a machine audition perspective. The first part of the thesis presents algorithms for binaural localisation and separation of speech sources based solely on analysis of the Interaural Phase Difference (IPD) cue. The IPD cue encodes time delay information between two microphones which can be used to establish spatial locations of the sources in the mixture. One well known problem with processing the IPD cue is its periodic nature. This means that a single IPD value can represent several spatial locations of the corresponding source. The phase ambiguity problem has been studied for human auditory processing as well for machines, however, mostly from source localisation perspective. Relatively little attention has been given to phase ambiguity which relates to interaction of the IPDs between the sources present in the mixture. Investigations presented in the thesis explore the use of the IPDs by machines for robust source localisation and separation. Firstly, an algorithm for source localisation is introduced. The algorithm combines the Maximum Likelihood Sample Consensus (MLESAC) based search of line patterns which correspond to speech sources. The search is performed using Cross-phasogram representation of IPDs. Next, the study on the impact of phase ambiguity on separation performance is presented. A source separation algorithm called Localisation based Mask for Source Separation (LOCUS) is introduced. The LOCUS algorithm models the IPDs using Gaussian Mixture Model (GMM). The analysis of the IPDs interaction between different sources is shown to improve initialisation of the GMM and in consequence provided performance gains over the state-of-the art binaural separation methods. The second part of this thesis focuses on using the harmonicity cue for speech separation. The harmonicity is a feature of voiced speech therefore intuitively seems a powerful cue that could enhance separation of speech sources. However, in a multi-speaker scenario segregation of harmonic components is not trivial as it relies heavily on the underlying multi-source pitch determination algorithm. The proposed system uses an approach where speech sources are firstly reconstructed using the LOCUS algorithm and fed into single-source pitch determination algorithm. This gives the opportunity to use well-established single-source pitch determination algorithms which have been known for good robustness and accuracy of provided pitch trajectories. Based on this approach the Pitch based Harmonicity Mask for Source Separation (PRIMUS) algorithm is introduced. The approach is analogous to other separation systems that can be found in the literature however there has been little formal validation of some of the algorithmic choices that need to be considered for such approach. Therefore a detailed review followed by experimental studies of all the stages of the algorithm, from reconstruction of speech sources to calculation of corresponding separation masks, are presented. The final evaluation is done for the PRIMUS and the JANUS (Joint Localisation and Harmonicity Mask for Source Separation) algorithms where the JANUS algorithm computes a set of joint separation masks combining outputs of the LOCUS and the PRIMUS algorithms. The experimental results showed improvements in separation performance that were achieved over the state-of-the art binaural separation methods.
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Eckerholm, Fredrik. "Physical models of sound sources: interaction models - the "PluckSynth"." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-95246.
Повний текст джерелаАнотація:
This thesis report describes a virtual musical instrument capable of time domain synthesis of guitar tones of acoustic and electrical character. Apart from the problem of the generation of guitar timbres, attention is paid to the interaction between the guitar and the player. A real time implementation with a graphical user interface has been developed, using modern software synthesis technology.
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Sovardi, Carlo [Verfasser]. "Identification of Sound Sources in Duct Singularities / Carlo Sovardi." München : Verlag Dr. Hut, 2016. http://d-nb.info/1117982009/34.
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Best, Virginia Ann. "Spatial Hearing with Simultaneous Sound Sources: A Psychophysical Investigation." University of Sydney. Medicine, 2004. http://hdl.handle.net/2123/576.
Повний текст джерелаАнотація:
This thesis provides an overview of work conducted to investigate human spatial hearing in situations involving multiple concurrent sound sources. Much is known about spatial hearing with single sound sources, including the acoustic cues to source location and the accuracy of localisation under different conditions. However, more recently interest has grown in the behaviour of listeners in more complex environments. Concurrent sound sources pose a particularly difficult problem for the auditory system, as their identities and locations must be extracted from a common set of sensory receptors and shared computational machinery. It is clear that humans have a rich perception of their auditory world, but just how concurrent sounds are processed, and how accurately, are issues that are poorly understood. This work attempts to fill a gap in our understanding by systematically examining spatial resolution with multiple sound sources. A series of psychophysical experiments was conducted on listeners with normal hearing to measure performance in spatial localisation and discrimination tasks involving more than one source. The general approach was to present sources that overlapped in both frequency and time in order to observe performance in the most challenging of situations. Furthermore, the role of two primary sets of location cues in concurrent source listening was probed by examining performance in different spatial dimensions. The binaural cues arise due to the separation of the two ears, and provide information about the lateral position of sound sources. The spectral cues result from location-dependent filtering by the head and pinnae, and allow vertical and front-rear auditory discrimination. Two sets of experiments are described that employed relatively simple broadband noise stimuli. In the first of these, two-point discrimination thresholds were measured using simultaneous noise bursts. It was found that the pair could be resolved only if a binaural difference was present; spectral cues did not appear to be sufficient. In the second set of experiments, the two stimuli were made distinguishable on the basis of their temporal envelopes, and the localisation of a designated target source was directly examined. Remarkably robust localisation was observed, despite the simultaneous masker, and both binaural and spectral cues appeared to be of use in this case. Small but persistent errors were observed, which in the lateral dimension represented a systematic shift away from the location of the masker. The errors can be explained by interference in the processing of the different location cues. Overall these experiments demonstrated that the spatial perception of concurrent sound sources is highly dependent on stimulus characteristics and configurations. This suggests that the underlying spatial representations are limited by the accuracy with which acoustic spatial cues can be extracted from a mixed signal. Three sets of experiments are then described that examined spatial performance with speech, a complex natural sound. The first measured how well speech is localised in isolation. This work demonstrated that speech contains high-frequency energy that is essential for accurate three-dimensional localisation. In the second set of experiments, spatial resolution for concurrent monosyllabic words was examined using similar approaches to those used for the concurrent noise experiments. It was found that resolution for concurrent speech stimuli was similar to resolution for concurrent noise stimuli. Importantly, listeners were limited in their ability to concurrently process the location-dependent spectral cues associated with two brief speech sources. In the final set of experiments, the role of spatial hearing was examined in a more relevant setting containing concurrent streams of sentence speech. It has long been known that binaural differences can aid segregation and enhance selective attention in such situations. The results presented here confirmed this finding and extended it to show that the spectral cues associated with different locations can also contribute. As a whole, this work provides an in-depth examination of spatial performance in concurrent source situations and delineates some of the limitations of this process. In general, spatial accuracy with concurrent sources is poorer than with single sound sources, as both binaural and spectral cues are subject to interference. Nonetheless, binaural cues are quite robust for representing concurrent source locations, and spectral cues can enhance spatial listening in many situations. The findings also highlight the intricate relationship that exists between spatial hearing, auditory object processing, and the allocation of attention in complex environments.
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Alber, Thomas Helmut. "Valves as sources of structure- and fluid-borne sound." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436258.
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Buret, Marc. "New analytical models for outdoor moving sources of sound." Thesis, n.p, 2002. http://library7.open.ac.uk/abstracts/page.php?thesisid=64.
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Mugagga, Pius Kavuma Basajjabaka. "A binaural sound sources localisation application for smart phones." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/24295.
Повний текст джерелаАнотація:
The ability to estimate positions of sound sources is one that gives animals a 360° awareness of their acoustic environment. This helps compliment the visual scene which is restricted to 180° in humans. Unfortunately, deaf people are left out on this ability. Smart phones are rapidly becoming a common tool amongst mobile users in developed and emerging markets. Their processing ability has more than doubled since their introduction to mass consumer markets by Apple in 2007. Top-end smart phones such as the Samsung Galaxy Series; 3, 4, and 5 models, have two microphones with which one can acquire stereo recordings. The purpose of this research project was to establish a feasible Sound source localization algorithm for current top-end smart phones, and to recommend hardware improvements for future smart phones, to pave way for the use of smart phones as advanced auditory sensory devices capable of acting as avatars for intelligent remote systems to learn about different acoustic scenes with help of human users. The GCC-PHAT algorithm was chosen as the underlying core DOA algorithm due to its suitability for pair-wise localization as highlighted in literature. A stochastic power accumulation algorithm was designed and implemented to improve estimation outcomes by GCC-PHAT. This algorithm was based on inspiration from W-disjoint orthogonality assumption in literature and was extended to perform sound source counting and time domain source separation. The system yielded satisfactory azimuth estimates of sound source directions in real time with pin-point DOA estimation accuracy rates of 64%, and 90.67% accuracy rate when a tolerance of ± 1 correlation sample is considered. An effort to resolve front back ambiguity using phone orientation data from the MEMs sensors yielded un-satisfactory results prompting a recommendation that an extra microphone would be needed to achieve 360° localization in a more user friendly way. The dissertation concludes with plans for further work on the topic and provision of a further refined API and optimised libraries to facilitate development of customised solutions using this system.
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Scheck, Jochen. "Characterisation of lightweight stairs as structure-borne sound sources." Thesis, University of Liverpool, 2011. http://livrepository.liverpool.ac.uk/3653/.
Повний текст джерелаАнотація:
The work reported in this thesis addresses the problem of structure-borne sound transmission from impacts on lightweight stairs. The primary aim was to provide a laboratory method for characterisation of lightweight stairs as structure-borne sound sources, which will give input data for prediction of the sound transmission in heavyweight building situations. By treating the stair system, combined with impact source(s), as an active component, available methods for active sources could be adapted. The component powers of a timber staircase attached to a solid wall in a staircase test facility have been determined in-situ by use of a reciprocal method. It was shown that the force perpendicular to the wall surface is dominant, moments can be neglected. The force induced power can be predicted from contact free velocity and mobility or by the blocked force as stairs constitute high mobility sources in heavyweight buildings. A practical characterisation is proposed that is based on the reception plate method. It is demonstrated that real walls and floors can be used as reception plates along with a power calibration that circumvents problems in estimating the plate mass, mean squared velocity and total loss factor for non-isolated reception plates. The sound transmission is predicted using EN 12354 and it is confirmed that the prediction gives values within acceptable engineering accuracy. A deterministic model that accounts for the modal coupling of structure and room is used to predict the sound transmission at low frequencies. For the case considered, a major difficulty was found in the modelling of the wall vibration field, mainly due to the boundary conditions that do not correspond to idealised conditions, such as pinned or free edges.
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Huang, Lixi. "Wave drag and power in moving sources." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239640.
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Rowley, David Chapman. "Antiviral natural products from marine sources /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2001. http://wwwlib.umi.com/cr/ucsd/fullcit?p3035894.
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Du, Liangfen. "Characterisation of air-borne sound sources using surface coupling techniques." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI028/document.
Повний текст джерелаАнотація:
La thèse se base sur la recherche des possibilités de caractérisation du son aérien de sources sonores arbitraires. A cette fin, une approche particulière est étudiée à l’endroit où la caractérisation de la source est faite via une surface d’interface qui enveloppe totalement ou partiellement la source physique. Deux descripteurs qui dépendent de la fréquence sont definis au travers d’une telle surface: la pression sonore bloquée et l’impédance de la source. Le précédent représente la pression sonore créée par le système d’exploitation source qui agit sur la surface enveloppante quand elle est rendue immobile. Cette dernière représente le rapport des amplitudes de réponse de pression et les amplitudes de vitesse d’excitation normales au travers de la surface. La surface enveloppante définit un volume d’air qui contient la source physique appelée l’espace source. Les deux descripteurs définis sur l’espace source, la pression bloquée et l’impédance de la source sont montrés comme étant intrinsèques à la source, c’est-à-dire indépendants de l’espace acoustique environnant. Une fois définis, ces descripteurs permettent de trouver la pression sonore et la vitesse particulaire normale à la surface de l’interface quand l’espace source est couplé à un espace récepteur arbitraire, c’est-à-dire une pièce. Cela permet alors la prédiction du son dans l’espace récepteur. Les conditions de couplage nécessitent que l’espace récepteur soit caractérisé en utilisant la même surface enveloppante telle que l’espace source. En acceptant de garder à l’esprit la simplicité de la mesure, la surface enveloppante a été conçue vu qu’elle comporte une ou plusieurs surfaces rectangulaires planes. Le défi de la recherche était alors d’obtenir une impédance significative de la surface au travers de la surface plane rectangulaire (continue) ainsi que celle de la pression bloquée compatible avec la formulation de l’impédance. Cela a conduit à une décomposition dans l’espace de la pression sonore et de la vitesse des particules au sein du nombre fini des composants, chacun défini par une amplitude complexe et une distribution dans l’espace particulière. De cette façon, la pression bloquée se réduit à un vecteur d’amplitude de pression complexe, tandis que l’impédance devient une matrice de pression et des rapports d’amplitudes complexes de la vitesse de défauts de de décompositions ont été recherchés dans le détail: la méthode harmonique de surface et la méthode du patch. Le premier se rapproche de la pression de surface et de la vitesse normale par des combinaisons de fonctions de surface trigonométriques en 2D tandis que ce dernier partage la surface en petites parcelles et intervient sur chaque parcelle de façon discrète en utilisant les valeurs moyennes du patchThe thesis investigates possibilities of air-borne sound characterisation of arbitrary sound sources. To this end a particular approach is studied where the source characterisation is done via an interface surface which fully or partially envelopes the physical source. Two frequency dependent descriptors are defined across such a surface: the blocked sound pressure and the source impedance. The former represents the sound pressure created by the operating source which acts on the enveloping surface when this is made immobile. The latter represents the ratio of pressure response amplitudes and normal velocity excitation amplitudes across the surface. The enveloping surface defines an air volume containing the physical source, called the source space. The two source descriptors defined on the source space, the blocked pressure and the source impedance, are shown to be intrinsic to the source, i.e. independent of the surrounding acoustical space. Once defined, these descriptors allow one to find the sound pressure and normal particle velocity at the interface surface when the source space is coupled to an arbitrary receiver space, i.e. a room. This in turn allows for sound prediction in the receiver space. The coupling conditions require that the receiver space is characterised using the same enveloping surface as the source space. Bearing the measurement simplicity in mind, the enveloping surface has been conceived as consisting of one or several rectangular plane surfaces. The research challenge was then to obtain meaningful surface impedance across a (continuous) rectangular plane surface as well as the blocked pressure compatible with impedance formulation. This has led to a spatial decomposition of sound pressure and particle velocity into finite number of components, each defined by a complex amplitude and a particular spatial distribution. In this way the blocked pressure reduces to a vector of complex pressure amplitudes while the impedance becomes a matrix of pressure and velocity complex amplitude ratios. Two decomposition methods have been investigated in detail: the surface harmonic method and the patch method. The former approximates the surface pressure and normal velocity by combinations of 2D trigonometric surface functions while the latter splits the surface into small patches and treats each patch in a discrete way, using patch-averaged values
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Camargo, Hugo Elias. "A Frequency Domain Beamforming Method to Locate Moving Sound Sources." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/27765.
Повний текст джерелаАнотація:
A new technique to de-Dopplerize microphone signals from moving sources of sound is derived. Currently available time domain de-Dopplerization techniques require oversampling and interpolation of the microphone time data. In contrast, the technique presented in this dissertation performs the de-Dopplerization entirely in the frequency domain eliminating the need for oversampling and interpolation of the microphone data. As a consequence, the new de-Dopplerization technique is computationally more efficient.
The new de-Dopplerization technique is then implemented into a frequency domain beamforming algorithm to locate moving sources of sound. The mathematical formulation for the implementation of the new de-Dopplerization technique is presented for sources moving along a linear trajectory and for sources moving along a circular trajectory, i.e. rotating sources.
The resulting frequency domain beamforming method to locate moving sound sources is then validated using numerical simulations for various source configurations (e.g. emission angle, emission frequency, and source velocity), and different processing parameters (e.g. time window length). Numerical datasets for sources with linear motion as well as for rotating sources were simulated. For comparison purposes, selected datasets were also processed using traditional time domain beamforming. The results from the numerical simulations show that the frequency domain beamforming method is at least 10 times faster than the traditional time domain beamforming method with the same performance. Furthermore, the results show that as the number of microphones and/or grid points increase, the processing time for the traditional time domain beamforming method increases at a rate 20 times larger than the rate of increase in processing time of the new frequency domain beamforming method.Ph. D.
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Lombard, Anthony [Verfasser]. "Localization of Multiple Independent Sound Sources in Adverse Environments / Anthony Lombard." München : Verlag Dr. Hut, 2012. http://d-nb.info/1029400148/34.
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Xin, Su Jian. "Simplified characterisation of structure-borne sound sources with multi-point connections." Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400130.
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Baker, Jonathan M. "Natural and anthropogenic sources of methyl bromide." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266714.
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Partridge, Jamie Lee. "Natural ventilation : competing sources and background turbulence." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709122.
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Pignier, Nicolas. "Sound propagation from sustainable ground vehicles : from aeroacoustic sources to urban noise." Licentiate thesis, KTH, Farkost och flyg, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174182.
Повний текст джерелаАнотація:
Transportation is the main source of environmental noise in Europe, with an estimated 125 million people affected by excessive noise levels from road traffic, causing a burden of noise related diseases and having a substantial economic impact on society. In order to reduce exposure to high levels of traffic noise, two approaches are the topic of extensive research: preventing sound from propagating from roads and railways using for example noise barriers, and reducing the sources of noise themselves. The second solution, which addresses directly the cause of the problem, requires improved design methods, with a more systematic resort to multi-functional design. Addressing cross-functions simultaneously reduces the number of design iterations and the high cost of prototyping. The work presented in this thesis aims at developing methods that can be used to design quieter vehicle concepts within a multi-functional approach, and is articulated around two main axis of research, aerodynamic sound generation and sound propagation. The first axis aims at performing an aeroacoustic analysis to predict aerodynamic sound sources. A hybrid method is used on the example of a type of submerged air inlet called a NACA duct, where the near-field flow is solved through detached eddy simulation (DES) and where the far-field acoustics is computed using the Ffowcs Williams and Hawkings integral. Results for the flow for various operating conditions are presented and validated against experimental data from the literature, with very good agreement. Far-field acoustic results are shown, exhibiting levels and components that are strongly dependent on the operating conditions. This analysis gives a framework for future aeroacoustic analysis in the project, and sets the path for the development of air inlets with improved aerodynamic and aeroacoustic characteristics. The second axis focuses on the propagation of sound from a given source, moving in an urban environment. An approximate boundary method is presented, which relies on the Kirchhoff approximation applied to the Kirchhoff-Helmholtz integral equation. Using this approximation speeds up the computational time compared to using a regular boundary element method. The resulting expression is extended to account for multiple scattering through consecutive updates of the surface pressures, and for moving sources through the introduction of a retarded time and of a Doppler shift. Validation tests for this method are presented, from simple scatterers to a more realistic configuration, showing good agreement with analytical, experimental and simulated work.Fordon är den främsta källan till bullerexponering i Europa med uppskattningsvis 125 miljoner människor som är utsatta för höga ljudnivåer från vägtrafik, vilket kan orsaka bullerrelaterade häsloproblem samt har en betydande ekonomisk effekt på samhället. För att minska exponeringen för höga ljudnivåer från fordon, finns det två angreppssätt som båda idag är ämne för omfattande forskning: att förhindra ljudutbredning från vägar och järnvägar (till exempel med hjälp av bullerskydd), samt att minska ljudnivån från olika bullerkällor. Den sistnämnda, som direkt riktar sig till problemets orsak, kräver förbättrade designmetoder med mer systematisk användning av multifunktionell design. Att hantera flera funktioner hos fordonet samtidigt minskar antalet designiterationer och den höga kostnaden för prototyper. Arbetet som presenteras i denna avhandling syftar till att utveckla metoder som kan användas för att utforma tystare fordonskoncept inom ramen för en multifunktionell strategi och fokuserar på två spår i forskningen: aerodynamisk ljudalstring och ljudutbredning från rörliga källor. Det första spåret i forskningen syftar till att utföra en aeroakustisk undersökning för att modellera aerodynamiska ljudkällor. En hybridmetod tillämpas på ett typ av nedsänkt luftintag, kallat NACA-intag, där källområdet i strömningen löses genom detached eddy simulation (DES) och akustiken i fjärrfältet beräknas enligt Ffowcs Williams och Hawkings integral. Resultat för strömningen för olika driftförhållanden presenteras och valideras mot experimentella data från litteraturen, med mycket god överensstämmelse. Resultat för det akustika fjärrfältet visas, vilket uppvisar nivåer och komponenter som är starkt beroende av driftförhållandena. Denna analys ger en ram för kommande analyser av aeroakustik inom projektet och visar vägen för utvecklingen av luftintag med förbättrade aerodynamiska och aeroakustika egenskaper. Det andra spåret i forskningsprojektet är inriktat på ljudets utbredning från en given källa som rör sig i en urban miljö. En approximativ randvärdesmetod presenteras som bygger på Kirchhoff approximation tillämpad på Kirchhoff-Helmholtz integralekvation. Med hjälp av denna approximation minskas beräkningstiden jämfort med vanlig boundary element method (BEM). Modellen utvecklas sedan för att kunna hantera flera reflektioner genom att det akustiska trycket på ytorna uppdateras för varje reflektion samt för att kunna hantera rörliga källor genom att introducera tidsfördröjningar och Dopplerförskjutning. Validering för denna modell presenteras, från enkla spridare till en mer realistisk urban konfiguration, som visar god överensstämmelse med analytiskt, experimentellt och simulerat data.
QC 20151002
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Ning, Qi. "Towards a characterisation of circulation pumps as sources of structure-borne sound." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399100.
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Matzumoto, Andres Esteban Perez. "A study of microphone arrays for the location of vibrational sound sources." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305576.
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Hirakawa, Susumu. "Prediction of impact sound transmission with heavy impact sources in heavyweight buildings." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3028540/.
Повний текст джерелаАнотація:
In heavyweight buildings, impact sound insulation from heavy impacts such as footsteps in bare feet, or children running and jumping can be a significant problem. Hence it is useful to be able to predict the Fast time-weighted maximum sound pressure level (Lp,Fmax) in a room due a transient impact on the floor above. This thesis extends an existing prediction model using Transient Statistical Energy Analysis (TSEA) to include the effect of a floating floor on top of the concrete base floor, and through comparison with measurements. Time-domain Finite Element Methods (FEM) have been used to incorporate the rubber ball (a heavy impact source) within the model and to investigate the accuracy of TSEA and measurement procedures in the low-frequency range. Experimental and lump parameter models have been used to investigate the structural dynamics of the rubber ball, and the blocked force on impact. Experimental determination of modal parameters identified the fundamental frequency in order to estimate the Young's modulus of the rubber for FEM models. A single degree-of-freedom (dof) model for the ball gave reasonable estimates of the blocked force but for modelling purposes more accurate data was needed from force plate measurements. An idealised floating floor was investigated using small mass-spring systems that would fit on top of a force plate for which experiments and two dof models indicated a single peak or a double peak in the time domain blocked force depending on whether the resilient material was soft or stiff respectively. To incorporate the effect of a floating floor on a heavyweight base floor in a TSEA model, an inverse approach to TSEA (ITSEA) has been developed. Using laboratory measurements this gives the normalised transient power input into the base floor for a heavy impact source impacting the floating floor. Experimental assessment of ITSEA was carried out in test laboratories using small mass-spring systems and a full-size floating floor which validated the approach to experimentally quantify transient power with ITSEA and incorporate this in TSEA to predict Lp,Fmax in a receiving room. FEM models were validated against measurements from which comparisons of TSEA and FEM at low-frequencies show sufficiently close agreement (i.e. < 2.5dB) to recommend that TSEA be used in design work due to its fast computation time. FEM was also used to investigate and suggest improvements to measurement procedures by using corner measurement positions of Lp,Fmax.
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Giannoulis, Dimitrios. "Recognition of sound sources and acoustic events in music and environmental audio." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/9130.
Повний текст джерелаАнотація:
Hearing, together with other senses, enables us to perceive the surrounding world through sensory data we constantly receive. The information carried in this data allow us to classify the environment and the objects in it. In modern society the loud and noisy acoustic environment that surrounds us makes the task of "listening" quite challenging, probably more so than ever before. There is a lot of information that has to be filtered to separate the sounds we want to hear at from unwanted noise and interference. And yet, humans, as other living organisms, have a remarkable ability to identify and track the sounds they want, irrespectively of the number of them, the degree of overlap and the interference that surrounds them. To this day, the task of building systems that try to "listen" to the surrounding environment and identify sounds in it the same way humans do is a challenging one, and even though we have made steps towards reaching human performance we are still a long way from building systems able to identify and track most if not all the different sounds within an acoustic scene. In this thesis, we deal with the tasks of recognising sound sources or acoustic events in two distinct cases of audio – music and more generic environmental sounds. We reformulate the problem and redefine the task associated with each case. Music can also be regarded as a multisound source environment where the different sound sources (musical instruments) activate at different times, and the task of recognising the musical instruments is then a central part of the more generic process of automatic music transcription. The principal question we address is whether we could develop a system able to recognise musical instruments in a multi-instrument scenario where many different instruments are active at the same time, and for that we draw influence from human performance. The proposed system is based on missing feature theory and we find that the method is able to retain high performance even under the most adverse of listening conditions (i.e. low signal-to-noise ratio). Finally, we propose a technique to fuse this system with another that deals with automatic music transcription in an attempt to inform and improve the overall performance. For a more generic environmental audio scene, things are less clear and the amount of research conducted in the area is still scarce. The central issue here, is to formulate the problem of sound recognition, define the subtasks and associated difficulties. We have set up and run a worldwide challenge and created datasets that is intended to enable researchers to perform better quality research in the field. We have also developed proposed systems that could serve as baseline techniques for future research and also compared existing state-of-the-art algorithms to one another, and also against human performance, in an effort to highlight strengths and weaknesses of existing methodologies.
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Gundlach, Catherine P. "Reflections of a fool a modern ballet derived from electronic sound sources." Thesis, Kansas State University, 1985. http://hdl.handle.net/2097/9844.
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Höller, Christoph. "Indirect methods of obtaining activity and mobility of structure-borne sound sources." Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/14233/.
Повний текст джерелаАнотація:
The work reported in this thesis focuses on the development of indirect methods for the experimental determination of important source parameters for structure-borne sound source characterization. In the first part of the thesis, matrix inversion methods for the determination of blocked forces are investigated. A simplified measurement procedure is proposed which offers a solution to the two major challenges to these methods, namely the acquisition of the FRF matrix and the problems associated with matrix inversion. The proposed procedure involves a free, low-mobility receiver plate which is modelled numerically. Calculated FRFs are used together with measured velocity responses to inversely determine the blocked forces. It is found that while the method has great potential in principle, in practice the accurate modelling of the receiver plate is of critical importance. In the second part of the thesis, three formulations are considered for the indirect determination of source mobility. Instead of performing measurements on the source in the free state, the source mobility is obtained from measurements made in-situ. This approach is beneficial if the source is difficult to suspend, or if it contains non-linear structural elements. The three formulations are validated numerically and experimentally. It is found that the methods can quantify source mobilities of single-contact and multi-contact sources from in-situ measurements. However, typical measurement errors, such as background noise or inaccuracies in sensor positioning, can significantly reduce the accuracy and reliability of the methods. In the final part of the thesis, the reception plate method for the determination of the power injected by a high-mobility source into a low-mobility receiver is reviewed, and a source substitution method proposed as a development. The substitution method circumvents problems that may arise when the reception plate method is applied to coupled walls and floors. A special focus of investigation is on the calibration of the receiver structure. It is found that the calibration can be performed with shaker or hammer, and that an average calibration factor may be used. The source substitution method thus offers a potential alternative to the reception plate method, for application with coupled plates.
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Kemp, Ronald Jeffrey. "Measurement of gaseous mercury emissions from natural sources." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ61978.pdf.
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Sturm, M. "Identification and quantification of transient structure-borne sound sources in electrical steering systems." Thesis, University of Salford, 2014. http://usir.salford.ac.uk/30761/.
Повний текст джерелаАнотація:
During driving on rough roads, rattle noise may emanate from (electric power) rack-and-pinion steering gears as a result of reverse feedback from the road. This project is in collaboration with a German steering system manufacturer and aims to develop a methodology facilitating identification and quantification of transient structure-borne sound sources within electrical steering systems. To achieve this aim, a conceptual source-path-receiver model has been developed that discloses the theoretical locations and associated mechanisms of all possible transient sound sources inside the steering gear. This information forms the basis for a subsequent measurement step which is required to experimentally quantify the strength of each individual source. The measurement approach is based on a time domain equivalent of the in-situ blocked force method; thus facilitating independent source characterisation on the fully assembled structure. The time domain (TD) approach relies on a robust inversion routine that uses an adaptive algorithm to simultaneously reconstruct multi-channel (blocked) force signatures from operational responses and the corresponding impulse response functions both measured (in-situ) on the (assembled) structure. The TD inversion routine is derived from the least mean square (LMS) algorithm which is widely used in adaptive filter design. The accuracy and sensitivity of the TD inversion routine is elaborated and compared to the standard frequency domain inverse method using simple numerical examples. Its general applicability for sophisticated technical structures is evaluated by example of an electric powered steering system being subjected to artificial excitation. The use of the TD approach for characterisation of transient structure-borne sound sources based on the blocked force method is discussed and different procedures to improve the force estimation accuracy are proposed. These procedures can be classified into methods that (i) help to evaluate the quality of pre-measured frequency response functions (FRFs) which are required to set up the (inverse) system model, (ii) measurement routines that may help to improve future FRF measurements conducted in-situ, i.e. whilst the steering gear is connected to a special rattling test bench, (iii) correction strategies to separate contributions from known (external) structure-borne sound sources different from the desired (internal) rattling sources and (iv) criteria that in theory allow for monitoring the performance of the iterative TD inversion routine precisely. Finally, the developed methodology is used to identify and quantify rattle sources within a steering system under realistic testing conditions.
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Laturnus, Frank. "Natural sources of volatile organohalogens : impact on the biosphere /." [Copenhagen] : University of Copenhagen, 2003. http://catalogue.bnf.fr/ark:/12148/cb399303687.
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Maynard, Diana Gabrielle. "Term recognition using combined knowledge sources." Thesis, Manchester Metropolitan University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311203.
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Bosenko, V. S. "Alternative energy sources." Thesis, Sumy State University, 2014. http://essuir.sumdu.edu.ua/handle/123456789/45174.
Повний текст джерелаАнотація:
Energy sources are very important for all of us. We all need different types of energy in our daily life to perform different tasks. We get energy from different natural resources like coal, petroleum, and electricity. Again, electricity comes from different sources hydro-electricity, thermal electricity and some alternate sources of energy like electricity from solar energy. Alarming Situation of Natural energy sources Stock Natural sources of energy are limited because of their limited stock. It takes several years in formation of natural energy sources but if the consumption of energy sources will be too more (like in current situation) than the rate of their formation, they will not last longer. Even the stocks of energy sources like petroleum are limited to certain areas and they have monopoly on petroleum market, resulting drastic increase in rates of petroleum during last decade.
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Sanalatii, Maryna. "Synthèse d'un champ acoustique avec contraste spatial élevé." Thesis, Le Mans, 2018. http://www.theses.fr/2018LEMA1005/document.
Повний текст джерелаАнотація:
L'objectif de ce travail de thèse est la conception d'un système de haut-parleurs transportable, capable de générer un champ sonore prédéfini et focalisé avec un contraste spatial élevé. Ce système doit permettre à terme d'effectuer différents types d'études, par exemple des essais de transparence acoustique ou encore des essais vibratoires en conditions non-anéchoïques. La minimisation du nombre de canaux à piloter ainsi que du nombre des transducteurs est l'un des enjeux principaux du travail. Le choix du nombre de sources et la sélection de leurs positions optimales afin de générer un champ acoustique cible n'a pas de solution triviale. Pour répondre à cette question, la méthode proposée se base sur la décomposition du rayonnement d’une source en série de fonctions orthogonales indépendantes (les"modes de rayonnement"), construits numériquement via une décomposition en valeurs singulières de la matrice d'impédance. En filtrant les termes évanescents, le champ lointain peut être reconstruit à l'aide d'un faible nombre de termes. De plus, la méthode permet d'estimer une distribution de débit efficace pour générer le champ cible. La méthode proposée étant relativement peu étudiée dans la littérature, la première partie de la thèse a été consacrée au problème de la validation expérimentale de la méthode directe et à l'étude des principaux paramètres en influençant le résultat. La problématique du positionnement des sources permettant de synthétiser un champ sonore prédéfini et focalisé est abordée dans la deuxième partie du travailThe goal of this thesis is the design of a transportable speaker system, able to generate a predefined and focused sound field with a high spatial contrast. This system has eventually to allow carrying out different types of studies, for example acoustic transmission loss tests or vibration tests in non-anechoic conditions. The minimization of the number of driven channels and the number of transducers is one of the main goals of the work. The choice of the number of sources and the selection of their optimal positions in order to generate a target acoustic field has no trivial solution. To answer this question, the proposed method is based on the decomposition of the source radiation into a series of independent orthogonal functions (the "radiation modes"), constructed numerically via a singular value decomposition of the impedance matrix. By filtering the evanescent terms, the far field can be reconstructed using a small number of terms. In addition, the method allows the estimation of an efficient flow distribution to generate the target field. With the proposed method having been scarcely studied in the literature, the first part of the thesis is devoted to the problem of the experimental validation of the direct method and the study of the main parameters that are influencing the result. The problem of sources positioning in order to synthesize a predefined and focused sound field is discussed in the second part of the thesis
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McCaffrey, Carol Anne. "Analytical studies of organic emissions from anthropogenic and natural sources." Thesis, Glasgow Caledonian University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306893.
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Williams, Steffan Richard. "Recovery of small organics from natural sources using membrane technology." Thesis, Swansea University, 2015. https://cronfa.swan.ac.uk/Record/cronfa43185.
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Rodrigues, Mário Jorge Ferreira. "Model of access to natural language sources in electronic government." Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12268.
Повний текст джерелаАнотація:
Doutoramento em Engenharia InformáticaFor the actual existence of e-government it is necessary and crucial to provide public information and documentation, making its access simple to citizens. A portion, not necessarily small, of these documents is in an unstructured form and in natural language, and consequently outside of which the current search systems are generally able to cope and effectively handle. Thus, in thesis, it is possible to improve access to these contents using systems that process natural language and create structured information, particularly if supported in semantics. In order to put this thesis to test, this work was developed in three major phases: (1) design of a conceptual model integrating the creation of structured information and making it available to various actors, in line with the vision of e-government 2.0; (2) definition and development of a prototype instantiating the key modules of this conceptual model, including ontology based information extraction supported by examples of relevant information, knowledge management and access based on natural language; (3) assessment of the usability and acceptability of querying information as made possible by the prototype - and in consequence of the conceptual model - by users in a realistic scenario, that included comparison with existing forms of access. In addition to this evaluation, at another level more related to technology assessment and not to the model, evaluations were made on the performance of the subsystem responsible for information extraction. The evaluation results show that the proposed model was perceived as more effective and useful than the alternatives. Associated with the performance of the prototype to extract information from documents, comparable to the state of the art, results demonstrate the feasibility and advantages, with current technology, of using natural language processing and integration of semantic information to improve access to unstructured contents in natural language. The conceptual model and the prototype demonstrator intend to contribute to the future existence of more sophisticated search systems that are also more suitable for e-government. To have transparency in governance, active citizenship, greater agility in the interaction with the public administration, among others, it is necessary that citizens and businesses have quick and easy access to official information, even if it was originally created in natural language.
Para a efectiva existência de governo electrónico é necessário e crucial a disponibilização de informação e documentação pública e tornar simples o acesso a esta pelos cidadãos. Uma parte, não necessariamente pequena, destes documentos encontra-se sob uma forma não estruturada e em linguagem natural e, consequentemente, fora do que os sistemas de pesquisa actuais conseguem em geral suportar e disponibilizar eficazmente. Assim, em tese, é possível melhorar o acesso a estes conteúdos com recurso a sistemas que processem linguagem natural e que sejam capazes de criar informação estruturada, em especial se suportados numa semântica. Com o objectivo de colocar esta tese à prova, o desenvolvimento deste trabalho integrou três grandes fases ou vertentes: (1) Criação de um modelo conceptual integrando a criação de informação estruturada e a sua disponibilização para vários actores, alinhado com a visão do governo electrónico 2.0; (2) Definição e desenvolvimento de um protótipo instanciando os módulos essenciais deste modelo conceptual, nomeadamente a extracção de informação suportada em ontologias e exemplos de informação relevante, gestão de conhecimento e acesso baseado em linguagem natural; (3) Uma avaliação de usabilidade e aceitabilidade da consulta à informação tornada possível pelo protótipo – e em consequência do modelo conceptual - por utilizadores num cenário realista e que incluiu comparação com formas de acesso existentes. Além desta avaliação, a outro nível, mais relacionado com avaliação de tecnologias e não do modelo, foram efectuadas avaliações do desempenho do subsistema responsável pela extracção de informação. Os resultados da avaliação mostram que o modelo proposto foi percepcionado como mais eficaz e mais útil que as alternativas. Associado ao desempenho do protótipo a extrair informação dos documentos, comparável com o estado da arte, os resultados obtidos mostram a viabilidade e as vantagens, com a tecnologia actual, de utilizar processamento de linguagem natural e integração de informação semântica para melhorar acesso a conteúdos em linguagem natural e não estruturados. O modelo conceptual e o protótipo demonstrador pretendem contribuir para a existência futura de sistemas de pesquisa mais sofisticados e adequados ao governo electrónico. Para existir transparência na governação, cidadania activa, maior agilidade na interacção com a administração pública, entre outros, é necessário que cidadãos e empresas tenham acesso rápido e fácil a informação oficial, mesmo que ela tenha sido originalmente criada em linguagem natural.
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Dischler, Nicole Marie. "Investigations of targeted natural sources in search of bioactive metabolites." Diss., University of Iowa, 2019. https://ir.uiowa.edu/etd/6725.
Повний текст джерелаАнотація:
The past several decades have seen a rise in the numbers of fungal infections due to an increase in the population of immune-compromised individuals. Some of the most common types of invasive fungal infections are caused by Candida, Aspergillus, and Cryptococcus species. The current treatments for systemic fungal infections remain unsatisfactory because of resistance and toxicity problems. Because of this, there is a growing need for classes of antifungal agents effective against these pathogens.
Fungi have proven to be an excellent source of novel secondary metabolites possessing a range of bioactivities, including antifungal effects. Most of the research described in this thesis stems from an ecology-based approach for selecting types of fungi for investigation in search of novel bioactive metabolites. Members of three ecological niche groups are discussed: mycoparasitic/fungicolous, endophytic, and coprophilous fungi.
Mycoparasitic or fungicolous fungi are those that colonize other fungi and often cause some level of damage to the host. If damage occurs, it may be caused in part by antifungal natural products. Chemical investigations of nine isolates of fungicolous or mycoparasitic fungi (eight of which displayed antifungal activity) described in this thesis afforded five new compounds and 12 known compounds. Three of these known compounds have been reported to display antifungal properties, however, several others have not been tested in bioactivity assays. Due to this and unexpected loss of access to several of the antifungal assays explored in the initial prioritization process, the source of the original extract activity was not identified.
Endophytic fungi are those that inhabit plant tissue and may or may not cause damage to the host. In some cases, colonization of a plant by fungi may be beneficial to the plant by providing protection against unwanted insect or microbial pests, which may be the result of bioactive compounds being produced by the colonizing fungus. Chemical investigation of 10 isolates of endophytic fungi described herein (five of which produced antifungal extracts) afforded 21 known compounds and four new metabolites. Of these, three extracts contained known antifungal compounds as major components, indicating that they were responsible for the original observed extract activity. In other cases, loss of access to the antifungal assays employed in the initial selection resulted in the source of the extract activity remaining undetermined.
Coprophilous fungi, those that colonize the dung of herbivores, inhabit a nutrient-rich environment populated by many other organisms including other fungi, bacteria, insects, and protists. The production of bioactive compounds by coprophilous fungi might help provide them with a competitive advantage in this environment. Studies of 14 coprophilous fungal isolates (many of which displayed antifungal activity) are described in this thesis, leading to identification of twenty-five known compounds and nine new compounds. The majority of extracts yielded at least one metabolite known to have antifungal activity or one or more new compounds displaying these properties.
In addition to the fungal isolates described in this thesis, six new stilbene-type phytoalexins were isolated from peanut seeds (Arachis hypogaea). These compounds are produced by peanut seeds that had been challenged by a mycotoxin-producing fungal invader and may serve to some degree as chemical defenses.
A variety of separation techniques were utilized to isolate compounds from a range of classes, including terpenoids, polyketides, and peptides. Structures were established mainly based on analysis of various 1D and 2D NMR data aided by mass spectrometry. Relative stereochemical configurations were determined, where feasible, based on coupling constants and NOE experiments, whereas absolute configurations were determined using Mosher’s or chemical degradation methods.
Several new secondary metabolites with distinctive chemical features were isolated, as well as many known compounds, some of which displayed bioactivity in medically or agriculturally relevant assays. The work described here illustrates that these targeted groups of fungi are capable of producing a structurally diverse array of bioactive natural products and supports their selection as targeted sources of potentially useful compounds.
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Stevenson, Robert Mark. "Multiple knowledge sources for word sense disambiguation." Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310763.
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Pignier, Nicolas. "Predicting the sound field from aeroacoustic sources on moving vehicles : Towards an improved urban environment." Doctoral thesis, KTH, Farkost och flyg, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205791.
Повний текст джерелаАнотація:
In a society where environmental noise is becoming a major health and economical concern, sound emissions are an increasingly critical design factor for vehicle manufacturers. With about a quarter of the European population living close to roads with heavy traffic, traffic noise in urban landscapes has to be addressed first. The current introduction of electric vehicles on the market and the need for sound systems to alert their presence is causing a shift in mentalities requiring engineering methods that will have to treat noise management problems from a broader perspective. That in which noise emissions need not only be considered as a by-product of the design but as an integrated part of it. Developing more sustainable ground transportation will require a better understanding of the sound field emitted in various realistic operating conditions, beyond the current requirements set by the standard pass-by test, which is performed in a free-field. A key aspect to improve this understanding is the development of efficient numerical tools to predict the generation and propagation of sound from moving vehicles. In the present thesis, a methodology is proposed aimed at evaluating the pass-by sound field generated by vehicle acoustic sources in a simplified urban environment, with a focus on flow sound sources. Although it can be argued that the aerodynamic noise is still a minor component of the total emitted noise in urban driving conditions, this share will certainly increase in the near future with the introduction of quiet electric engines and more noise-efficient tyres on the market. This work presents a complete modelling of the problem from sound generation to sound propagation and pass-by analysis in three steps. Firstly, computation of the flow around the geometry of interest; secondly, extraction of the sound sources generated by the flow, and thirdly, propagation of the sound generated by the moving sources to observers including reflections and scattering by nearby surfaces. In the first step, the flow is solved using compressible detached-eddy simulations. The identification of the sound sources in the second step is performed using direct numerical beamforming with linear programming deconvolution, with the phased array pressure data being extracted from the flow simulations. The outcome of this step is a set of uncorrelated monopole sources. Step three uses this set as input to a propagation method based on a point-to-point moving source Green's function and a modified Kirchhoff integral under the Kirchhoff approximation to compute reflections on built surfaces. The methodology is demonstrated on the example of the aeroacoustic noise generated by a NACA air inlet moving in a simplified urban setting. Using this methodology gives insights on the sound generating mechanisms, on the source characteristics and on the sound field generated by the sources when moving in a simplified urban environment.I ett samhälle där buller håller på att bli ett stort hälsoproblem och en ekonomisk belastning, är ljudutsläpp en allt viktigare aspekt för fordonstillverkare. Då ungefär en fjärdedel av den europeiska befolkningen bor nära vägar med tung trafik, är åtgärder för minskat trafikbuller i stadsmiljö en hög prioritet. Introduktionen av elfordon på marknaden och behovet av ljudsystem för att varna omgivningen kräver också ett nytt synsätt och tekniska angreppssätt som behandlar bullerproblemen ur ett bredare perspektiv. Buller bör inte längre betraktas som en biprodukt av konstruktionen, utan som en integrerad del av den. Att utveckla mer hållbara marktransporter kommer att kräva en bättre förståelse av det utstrålade ljudfältet vid olika realistiska driftsförhållanden, utöver de nuvarande standardiserade kraven för förbifartstest som utförs i ett fritt fält. En viktig aspekt för att förbättra denna förståelse är utvecklingen av effektiva numeriska verktyg för att beräkna ljudalstring och ljudutbredning från fordon i rörelse. I denna avhandling föreslås en metodik som syftar till att utvärdera förbifartsljud som alstras av fordons akustiska källor i en förenklad stadsmiljö, här med fokus på strömningsgenererat ljud. Även om det aerodynamiska bullret är fortfarande en liten del av de totala bullret från vägfordon i urbana miljöer, kommer denna andel säkerligen att öka inom en snar framtid med införandet av tysta elektriska motorer och de bullerreducerande däck som introduceras på marknaden. I detta arbete presenteras en komplett modellering av problemet från ljudalstring till ljudutbredning och förbifartsanalys i tre steg. Utgångspunkten är beräkningar av strömningen kring geometrin av intresse; det andra steget är identifiering av ljudkällorna som genereras av strömningen, och det tredje steget rör ljudutbredning från rörliga källor till observatörer, inklusive effekten av reflektioner och spridning från närliggande ytor. I det första steget löses flödet genom detached-eddy simulation (DES) för kompressibel strömning. Identifiering av ljudkällor i det andra steget görs med direkt numerisk lobformning med avfaltning med hjälp av linjärprogrammering, där källdata extraheras från flödessimuleringarna. Resultatet av detta steg är en uppsättning av okorrelerade akustiska monopolkällor. Steg tre utnyttjar dessa källor som indata till en ljudutbredningsmodel baserad på beräkningar punkt-till-punkt med Greensfunktioner för rörliga källor, och med en modifierad Kirchhoff-integral under Kirchhoffapproximationen för att beräkna reflektioner mot byggda ytor. Metodiken demonstreras med exemplet med det aeroakustiska ljud som genereras av ett NACA-luftintag som rör sig i en förenklad urban miljö. Med hjälp av denna metod kan man få insikter om ljudalstringsmekanismer, om källegenskaper och om ljudfältet som genereras av källor när de rör sig i en förenklad stadsmiljö.
QC 20170425
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Rudd, Alexis B. "Investigating the movement and seasonal occurrence of cetaceans in Hawai'i using sound." Thesis, University of Hawai'i at Manoa, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10085639.
Повний текст джерелаАнотація:
This dissertation tests two methods to obtain information of the distribution and movement of cetaceans. The first method uses vessels of opportunity as platforms to conduct acoustic surveys between the main Hawaiian Islands, with the ultimate goal of providing a method that can be used in future studies to contribute to mapping distribution and habitat modeling of data-poor cetacean species in the areas of the ocean which are infrequently surveyed. The distribution of a well-studied species, the humpback whale Megaptera novaeangliae was mapped and analyzed in relation to remotely sensed data on ocean depth, sea surface temperature, sea surface height, wind speed, chlorophyll-A, and surface currents. The results agreed with previous research on humpback whales, indicating that acoustic surveys from vessels of opportunity are a viable method for collecting distribution data on cetaceans. The predicted species of odontocete whistles collected during vessel of opportunity surveys was determined using the Real-time Odontocete Call Classification Algorithm, and analyzed in respect to remotely sensed data. The sighting rate for odontocete surveys in this study is comparable to that of previous survey methods, and cryptic species are identified at a higher relative rate than when using visual sighting methods. The biases inherent in concentrating survey effort primarily in the calm waters on the leeward sides the Hawaiian Islands are discussed, as well as the drawbacks of relying on visual sighting methods for detecting species with low visual detection probability. In addition, the potential impacts of anthropogenic noise and ship strikes from commercial vessels are discussed during the case study of a high-speed craft. This dissertation also discusses a second methodology involving the use of DIFAR sonobuoys to track multiple singing humpback whales, with the end goal of learning more about the function about humpback song. This method is also applicable to other cetacean species.