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1
Vejendla, Balaji. "Acoustic source strength determination of turbocharger in an unfavourable acoustic environment". Thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-265645.
Abstract (sommario):
The aim of the M.Sc thesis work is to specify a measurement method suitable for deter-mining the sound power levels and especially to quantifying the levels at the compressor blade pass frequency of a turbocharger in the new turbo performance rig located at Scania CV AB, Södertälje.Intensity and pressure based methods are widely used to determine the sound power levels. The thesis work focuses on pressure based methods since intensity measurements has a limitation in high frequencies and the intensity scanning in the rig is not allowed when the test rig is being operated. Unlike the intensity based methods the major drawback of using the pressure based methods is the influence of test environment on the sound pressure measurements. Since the room is not completely anechoic and reflections from various objects in the room may lead to wrong estimation of sound power levels. In order to understand the influence of test environment at the four chosen microphone positions several measurements were performed both in compliance with international standards and also to test assumptions on the acoustics characteristics of the room.Other than the turbocharger itself the test environment also includes three main auxiliary equipments; a cooling fan, a burner and an oil conditioning system which may contribute to the background noise at the microphone locations. A detailed study has been conducted to understand the influence from these additional sound sources during the measurements. It was concluded that the background sound do not a˙ect the measured results in the frequency range of interest. Measures were taken to isolate radiation from connecting pipes by shielding them with sound absorbing material.Based on the results from the test environment measurements and the background noise analysis the international standard ISO 3744 (Determination of sound power levels in an essentially free field over a reflecting plane) is recommended to determine the sound power levels of the turbocharger.For a constant shaft speed it was found that the highest A-weighted sound power levels were observed when the turbocharger was running close to surge followed by peak eÿciency and choke conditions on the compressor map. There is one limitation associated with the calculated sound power level and that is, the estimated sound power level is uncertain since it is based on only 4 microphone positions and thereby is not capturing the details of the compressor directivity.As future work, a setup with a large number of microphones surrounding the test speci-men is recommended which would help to determine the directivity hence improving the accuracy of the measurements. Also further studies on the sensitivity of the microphone positions, the arrangement of the auxiliary equipment in the room and the influence by the inlet and outlet pipes used in the real installation is recommended.Keywords: Turbocharger, surge, choke, peak eÿciency, compressor map, compressor blade pass frequency, sound power levels.Syftet med M.Sc-avhandlingen är att specificera en mätmetod som är lämplig för att bestämma ljudeffektnivåerna och särskilt att kvantifiera nivåerna vid kompressorbladets passfrekvens för en turboladdare i den nya turbo-prestandariggen vid Scania CV AB, Södertälje .Intensitets- och tryckbaserade mätmetoder används ofta för att bestämma ljudeffektnivåerna. Avhandlingsarbetet fokuserar på tryckbaserade metoder eftersom intensitetsmät-ningar har en begränsning i höga frekvenser och intensitetsskanningen i riggen inte är tillåten när testriggen används. Till skillnad från de intensitetsbaserade metoderna är den största nackdelen med att använda de tryckbaserade metoderna påverkan från testmiljön på ljudtrycksmätningarna. Detta eftersom rummet inte är ekofritt och reflektioner från olika objekt i rummet kan leda till fel uppskattning av ljudeffektnivåerna. För att förstå testmiljöns inverkan vid de fyra valda mikrofonpositionerna utfördes flera mätningar både i överensstämmelse med internationella standarder och för att testa antaganden om rummets akustikegenskaper. Utöver själva turboladdaren innehåller testmiljön också tre hjälputrustningar; en kylfläkt, en brännare och ett oljekonditioneringssystem som kan bidra till bakgrundsljud i mikrofon-positionerna. En detaljerad studie har genomförts för att förstå påverkan från dessa ytterligare ljudkällor under mätningarna. Det konstaterades att bakgrundsljudet inte påverkar de uppmätta resultaten i frekvensområdet av intresse. Åtgärder vidtogs för att isolera strålning från anslutande rör genom att skydda dem med ljudabsorberande material. Baserat på resultaten från testmiljömätningarna och bakgrundsljudanalysen rekommenderas den internationella standarden ISO 3744 (Bestämning av ljudeffektnivåer i ett väsentligen fritt fält över ett reflekterande plan) för att bestämma ljudeffektnivåerna för turboladdaren. För en konstant axelhastighet konstaterades att de högsta ljudeffektnivåerna observerades när turboladdaren kördes nära pumplinjen, följt av området med högsta verkningsgrad och choke linjen i kompressor-mappen. De beräknade ljudeffektnivåerna har en begränsning eftersom turboladdare direktivitet är okänd på grund av det låga antalet mikrofoner i mikrofonarrangemang runt turboladdaren, men de erhållna resultaten är tillräckligt bra för att göra en jämförelse mellan olika turboladdare förutsatt att de har liknande direktivitet. Som framtida arbete rekommenderas en installation med ett större antal mikrofoner (säg c:a 10 stycken) som omger testobjektet vilket skulle hjälpa till att bestämma direktiviteten och därmed förbättra mätnoggrannheten. Vidare rekommenderas ytterligare studier om mikrofonpositionernas känslighet, arrangemanget av hjälputrustningen i rummet samt påverkan av ljudutstrålning från de anslutande rören mer lika de i den riktiga motorinstallationen.
2
Elwali, Wael. "Vehicle Vibro-Acoustic Response Computation and Control". University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1382373197.
3
Fulton, Thomas F. (Thomas Friedrich) 1970. "Acoustic navigation for the autonomous underwater vehicle REMUS". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/88342.
4
Gutiérrez, Carlos 1974. "Unidirectional active acoustic control for launch vehicle fairings". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/89259.
5
Sampan, Somkiat. "Neural Fuzzy Techniques in Vehicle Acoustic Signal Classification". Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30612.
Abstract (sommario):
Vehicle acoustic signals have long been considered as unwanted traffic noise. In this research acoustic signals generated by each vehicle will be used to detect its presence and classify its type. Circular arrays of microphones were designed and built to detect desired signals and suppress unwanted ones. Circular arrays with multiple rings have an interesting and important property that is constant sidelobe levels. A modified genetic algorithm that can work directly with real numbers is used in the circular array design. It offers more effective ways to solve numerical problems than a standard genetic algorithm.
In classifier design two main paradigms are considered: multilayer perceptrons and adaptive fuzzy logic systems. A multilayer perceptron is a network inspired by biological neural systems. Even though it is far from a biological system, it possesses the capability to solve many interesting problems in variety fields. Fuzzy logic systems, on the other hand, were inspired by human capabilities to deal with fuzzy terms. Its structures and operations are based on fuzzy set theory and its operations. Adaptive fuzzy logic systems are fuzzy logic systems equipped with training algorithms so that its rules can be extracted or modified from available numerical data similar to neural networks. Both fuzzy logic systems and multilayer perceptrons have been proved to be universal function approximators. Since there are approximations in almost every stage, both of these system types are good candidates for classification systems.
In classification problems unequal learning of each class is normally encountered. This unequal learning may come from different learning difficulties and/or unequal numbers of training data from each class. The classifier tends to classify better for a well-learned class while doing poorly for other classes. Classification costs that may be different from class to class can be used to train and test a classifier. An error backpropagation algorithm can be modified so that the classification costs along with unequal learning factors can be used to control classifier learning during its training phase.Ph. D.
6
Cameron, Christopher John. "Design of Multifunctional Body Panels in Automotive Applications : Reducing the Ecological and Economical footprint of the vehicle industry". Licentiate thesis, Stockholm : Skolan för teknikvetenskap, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10661.
7
Liu, Li. "Ground vehicle acoustic signal processing based on biological hearing models". College Park, Md. : University of Maryland, 1999. http://techreports.isr.umd.edu/reports/1999/MS%5F99-6.pdf.
Abstract (sommario):
Thesis (M.S.) -- University of Maryland, College Park, 1999.Thesis research directed by Institute for Systems Research. "M.S. 99-6." Includes bibliographical references (leaves 75-78). Available also online as a PDF file via the World Wide Web.
8
Evans, Naoko. "Automated vehicle detection and classification using acoustic and seismic signals". Thesis, University of York, 2010. http://etheses.whiterose.ac.uk/1151/.
Abstract (sommario):
Security threats to important infrastructure cause problems to not only those who live nearby but also in a much wider sense. It is therefore desirable to consider the use of automated systems capable of detection and identification of potential threats. This thesis describes an investigation into acoustic and seismic methods for achieving such a system specifically for commercial road vehicles. Accurate algorithms have been developed for recognition of moving vehicles using fusion of acoustic and seismic signals. It has been found that seismic signals are less susceptible to interfering signals, making them optimal for detection of vehicles. Their much narrower bandwidth also increases processing efficiency and speed. Thus, the algorithm developed utilises firstly only seismic signals to detect vehicle presence, and then employs both acoustic and seismic signals for classifying type of the vehicle. The detection algorithm is purely time domain and uses seismic Log Energy together with a modification of Time Domain Signal Coding. The best detection accuracy obtained was 97.71 % with Support Vector Machine and 99.02 % with Learning Vector Quantisation Neural Networks. The classification algorithm to distinguish between trucks and cars utilises three relatively simple time domain methods: Zero-Crossing Rate, Log Energy and Autocorrelation of seismic signals; combined with LPC coefficients collected from acoustic signals. Classification with either SVM or LVQ reached 93.30 % or 80.80 % respectively. This study therefore has demonstrated it is possible to detect an approaching vehicle and classify its type by using acoustic and seismic signal processing.
9
Opinto, Alessandro <1991>. "Active Control of the Acoustic Field in a Vehicle Cabin". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10245/1/PhD_Thesis_AOpinto.pdf.
Abstract (sommario):
In this thesis, a thorough investigation on acoustic noise control systems for realistic automotive scenarios is presented. The thesis is organized in two parts dealing with the main topics treated: Active Noise Control (ANC) systems and Virtual Microphone Technique (VMT), respectively.
The technology of ANC allows to increase the driver's/passenger's comfort and safety exploiting the principle of mitigating the disturbing acoustic noise by the superposition of a secondary sound wave of equal amplitude but opposite phase. Performance analyses of both FeedForwrd (FF) and FeedBack (FB) ANC systems, in experimental scenarios, are presented. Since, environmental vibration noises within a car cabin are time-varying, most of the ANC solutions are adaptive. However, in this work, an effective fixed FB ANC system is proposed. Various ANC schemes are considered and compared with each other. In order to find the best possible ANC configuration which optimizes the performance in terms of disturbing noise attenuation, a thorough research of \gls{KPI}, system parameters and experimental setups design, is carried out.
In the second part of this thesis, VMT, based on the estimation of specific acoustic channels, is investigated with the aim of generating a quiet acoustic zone around a confined area, e.g., the driver's ears. Performance analysis and comparison of various estimation approaches is presented. Several measurement campaigns were performed in order to acquire a sufficient duration and number of microphone signals in a significant variety of driving scenarios and employed cars. To do this, different experimental setups were designed and their performance compared. Design guidelines are given to obtain good trade-off between accuracy performance and equipment costs. Finally, a preliminary analysis with an innovative approach based on Neural Networks (NNs) to improve the current state of the art in microphone virtualization is proposed.
10
Rallabhandi, Sriram Kishore. "Sonic Boom Minimization through Vehicle Shape Optimization and Probabilistic Acoustic Propagation". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6937.
Abstract (sommario):
Sonic boom annoyance is an important technical showstopper for commercial supersonic aircraft operations. It has been proposed that aircraft can be shaped to alleviate sonic boom. Choosing the right aircraft shape reflecting the design requirements is a fundamental and most important step that is usually over simplified in the conceptual stages of design by resorting to a qualitative selection of a baseline configuration based on historical designs and designers perspective. Final aircraft designs are attempted by minor shape modifications to this baseline configuration. This procedure may not yield large improvements in the objectives, especially when the baseline is chosen without a rigorous analysis procedure.
Traditional analyses and implementations tend to have a complex algorithmic flow, tight coupling between tools used and computational limitations. Some of these shortcomings are overcome in this study and a diverse mix of tools is seamlessly integrated to provide a simple, yet powerful and automatic procedure for sonic boom minimization. A shape optimization procedure for supersonic aircraft design using better geometry generation and improved analysis tools has been successfully demonstrated. The geometry engine provides dynamic reconfiguration and efficient manipulation of various components to yield unstructured watertight geometries. The architecture supports an assimilation of different components and allows configuration changes to be made quickly and efficiently because changes are localized to each component. It also enables an automatic way to combine linear and non-linear analyses tools. It has been shown in this study that varying atmospheric conditions could have a huge impact on the sonic boom annoyance metrics and a quick way of obtaining probability estimates of relevant metrics was demonstrated. The well-accepted theoretical sonic boom minimization equations are generalized to a new form and the relevant equations are derived to yield increased flexibility in aircraft design process. Optimum aircraft shapes are obtained in the conceptual design stages weighing in various conflicting objectives. The unique shape optimization procedure in conjunction with parallel genetic algorithms improves the computational time of the analysis and allows quick exploration of the vast design space. The salient features of the final designs are explained. Future research recommendations are made.
11
Wennhage, Per. "Structural-Acoustic Optimization of Sandwich Panels". Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3161.
12
Masmitjà, i. Rusinyol Ivan. "Acoustic underwater target tracking methods using autonomous vehicles". Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/668828.
Abstract (sommario):
Marine ecological research related to the increasing importance which the fisheries sector has reached so far, new methods and tools to study the biological components of our oceans are needed. The capacity to measure different population and environmental parameters of marine species allows a greater knowledge of the human impact, improving exploitation strategies of these resources. For example, the displacement capacity and mobility patterns are crucial to obtain the required knowledge for a sustainable management of fisheries.
However, underwater localisation is one of the main problems which must be addressed in subsea exploration, where no Global Positioning System (GPS) is available. In addition to the traditional underwater localisation systems, such as Long BaseLine (LBL) or Ultra-Short BaseLine (USBL), new methods have been developed to increase navigation performance, flexibility, and to reduce deployment costs. For example, the Range-Only and Single-Beacon (ROSB) is based on an autonomous vehicle which localises and tracks different underwater targets using slant range measurements conducted by acoustic modems. In a moving target tracking scenario, the ROSB target tracking method can be seen as a Hidden Markov Model (HMM) problem. Using Bayes' rule, the probability distribution function of the HMM states can be solved by using different filtering methods. Accordingly, this thesis presents different strategies to improve the ROSB localisation and tracking methods for static and moving targets. Determining the optimal parameters to minimize acoustic energy use and search time, and to maximize the localisation accuracy and precision, is therefore one of the discussed aspects of ROSB. Thus, we present and compare different methods under different scenarios, both evaluated in simulations and field tests. The main mathematical notation and performance of each algorithm are presented, where the best practice has been derived. From a methodology point of view, this work advances the understanding of accuracy that can be achieved by using ROSB target tracking methods with autonomous vehicles.
Moreover, whereas most of the work conducted during the last years has been focused on target tracking using acoustic modems, here we also present a novel method called the Area-Only Target Tracking (AOTT). This method works with commercially available acoustic tags, thereby reducing the costs and complexity over other tracking systems. These tags do not have bidirectional communication capabilities, and therefore, the ROSB techniques are not applicable. However, this method can be used to track small targets such as jellyfish due to the reduced tag's size. The methodology behind the area-only technique is shown, and results from the first field tests conducted in Monterey Bay area, California, are also presented.La biologia marina junt amb la importància que ha adquirit el sector pesquer, fa que es requereixin noves eines per a l’estudi dels nostres oceans. La capacitat de mesurar diferents poblacions i paràmetres ambientals d’espècies marines permet millorar el coneixement de l’impacte que l’ésser humà té sobre elles, millorant-ne els mètodes d’explotació. Per exemple, la capacitat de desplaçament i els patrons de moviment són crucials per obtenir el coneixement necessari per a una explotació sostenible de les pescaries involucrades. No obstant, la localització submarina és un dels principals problemes que s’ha de resoldre en l’explotació dels recursos submarins, on el sistema de posició global (GPS) no es pot utilitzar. A part dels mètodes tradicionals de posicionament submarí, com per exemple el Long Base-Line (LBL) o el Ultra-Short Base-Line (USBL), nous mètodes han estat desenvolupats per tal de millorar la navegació, la flexibilitat, i per reduir els costos de desplegament. Per exemple, el Range-Only and Single-Beacon (ROSB) utilitza un vehicle autònom per a localitzar i seguir diferents objectius submarins mitjançant mesures de rang realitzades a partir de mòdems acústics. En un escenari on l’objectiu a seguir és mòbil, el mètode ROSB de seguiment pot ser vist com a un problema de Hidden Markov Model (HMM). Aleshores, utilitzant la regla de Bayes, la funció de distribució de probabilitat dels estats del HMM pot ser solucionat utilitzant diferents mètodes de filtratge. Per tant, s’estudien diferents estratègies per millorar el sistema de localització i seguiment basat en ROSB, tant per objectius estàtics com mòbils. En aquesta tesis, presentem i comparem diferents mètodes utilitzant diferents escenaris, els quals s’han avaluat tant en simulacions com en proves de camp reals. A més, es presenten les principals notacions matemàtiques de cada algoritme i les millors pràctiques a utilitzar. Per tant, des d’un punt de vista metodològic, aquest treball fa un pas endavant en el coneixement de l’exactitud que es pot assolir utilitzant els mètodes de localització i seguiment d’espècies mitjançant algoritmes ROSB i vehicles autònoms. A més a més, mentre molts dels treballs realitzant durant els últims anys es centren en l’ús de mòdems acústics per al seguiment d’objectius submarins, en aquesta tesis es presenta un innovador mètode anomenat Area-Only Target Tracking (AOTT). Aquest sistema utilitza petites etiquetes acústiques comercials (tag), la qual cosa, redueix el cost i la complexitat en comparació amb els altres mètodes. Addicionalment, gràcies a l’ús d’aquests tags de dimensions reduïdes, aquest sistema permet seguir espècies marines com les meduses. La metodologia utilitzada per el mètode AOTT es mostra en aquesta tesis, on també es presenten els primers experiments realitzats a la badia de Monterey a Califòrnia.
13
BAKKAL, Ahmet Tansu. "Acoustic Detection of Rear Approaching Vehicles for Cyclists". Thesis, Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-25182.
Abstract (sommario):
The project aims to detect rear approaching vehicles for cycslist with a low power consumption. Study focuses on acoustic features of the sound of rear approaching vehicles and examines the useful indicators to detect the vehicles. The project includes more then one correlation and reveals their success rates for as many as samples possible.
14
Beach, Joseph N. "Integration of an Acoustic Modem onto a Wave Glider Unmanned Surface Vehicle". Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/7308.
Abstract (sommario):
This thesis examines the possibility of integrating an acoustic modem onto a Wave Glider with the goal of providing a bidirectional communications gateway for submerged sensors, platforms, and networks. The Wave Glider unmanned surface vehicle continuously harvests energy from the environment and is able to hold station without needing to refuel. A unique two-body architecture and wing system directly converts wave motion into thrust, and solar panels provide electricity for sensor payloads. Data messages are transmitted to shore via satellite, and the continuous surface presence means that data can be delivered in real time as it is collected. The objective of this thesis is to identify the best location for an acoustic modem on the Wave Glider, considering the factors of hydrodynamic drag on the vehicle and acoustic performance of the modem.
15
Kreamer, William Ryan 1976. "Supervisory control of an autonomous underwater vehicle using an acoustic communication link". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/8969.
Abstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2000.Includes bibliographical references (leaves 84-86).
In this thesis, I designed and tested a supervisory control scheme for the Odyssey II-class Autonomous Underwater Vehicles that relies on a very-low-data-rate acoustic communication link. A human supervisor communicates with the AUV over a combination radio/acoustic network. The supervisor radios commands from shore to data repeater nodes moored at strategic locations on the ocean surface. Utility Acoustic Modems mounted on the moorings rebroadcast the binary data into the sea in the 12-17 kHz frequency band. The moving AUV detects the transmission, decodes the message, and carries out the command contained within. The operator's commands are implemented in the context of a behavior-based layered control software architecture. The supervisory control scheme was tested and verified during the Synaptic Internal Tide Experiment, which took place in Monterey Bay during August and September, 1999.
by William Ryan Kreamer.
S.M.
16
Van, der Kelen Christophe. "Characterisation of anisotropic acoustic properties of porous materials - inverse estimation of static flow resistivity". Licentiate thesis, KTH, MWL Strukturakustik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31183.
Abstract (sommario):
The production processes of porous materials introduce an inherent geometric anisotropy in the material at micro scale, which influences the material properties at macro scale. In this thesis, the focus is turned to one of these macroscopic properties, the flow resistivity, which is a measure of the resistance felt by the sound pressure waves as they propagate through a porous space. In the current work, two different porous materials have been studied, a fibrous glass wool and a Melamine foam. The two materials are expected to show different degrees of anisotropy with respect to flow resistivity. Glass wool is assumed to be transversely isotropic, as a result of the stacking of layers of fibres. The level of anisotropy in Melamine foam is not as obvious, and might be related to production specific aspects, such as the rise-direction, and the position of the injection nozzles. The thesis begins by giving an introduction to porous materials in general, and to glass wool and Melamine foam in particular, followed by an introduction to flow resistivity, together with two methods to measure the flow resistivity. The full anisotropic flow resistivity of glass wool and Melamine foam samples is determined by means of measurements and inverse estimation. An eigenvalue and eigenvector decomposition of the flow resistivity tensor provides an insight into the connection between the directionality of the flow resistivity in each material, and its production process. A study of the homogeneity in density and flow resistivity for the two materials shows that these properties vary within the block of material. However, for each material, there seems to be no connection between the variation in the two properties, investigated at the macroscopic scale.QC 20110311
17
Aghaei, Shayan. "Acoustic Radiation Of An Automotive Component Using Multi-Body Dynamics". Thesis, KTH, Fordonsdynamik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-288710.
Abstract (sommario):
An important facet of creating high-quality vehicles is to create components that are quiet and smooth under operation. In reality, however, it is challenging to measure the sound that some automotive components make under load because it requires specialist facilities and equipment which are expensive to acquire. Furthermore, the motors used in testbeds drown out the noise emitted from much quieter components, such as a Power Transfer Unit (PTU). This thesis aims to solve these issues by outlining the steps required to virtually estimate the acoustic radiation of a PTU using the Transmission Error (TE) as the input excitation via multi-body dynamics (MBD). MBD is used to estimate the housing vibrations, which can then be coupled with an acoustic tool to create a radiation analysis. Thus, creating a viable method to measure the acoustic performance without incurring significant expenses. Furthermore, it enables noise and vibration analyses to be incorporated more easily into the design stage. This thesis analysed the sound radiated due to gear whine which arises due to the TE and occurs at the gear mesh frequency and its multiples. The simulations highlighted that the TE can be accurately predicted using the methods outlined in this thesis. Similarly, the method can reliably obtain the vibrations of the housing. The results from this analysis show that at 2000 rpm the PTU was sensitive to vibrations at 500, 1000 and 1500 Hz, the largest amplitude being at 1000 Hz. Furthermore, the Sound Power Level (SWL) was proportional to the vibration amplitudes in the system. Analytical calculations were conducted to verify the methods and showed a strong correlation. However, it was concluded that experiments are required to further verify the findings in this thesis.En viktig aspekt i att skapa fordon av hög kvalitet är att skapa komponenter som är tysta och smidiga under drift. I verkligheten är det dock svårt att mäta ljudet som vissa fordonskompo- nenter ger under belastning eftersom det kräver specialanläggningar och utrustning, vilket är dyrt att skaffa. Dessutom maskerar motorerna som används i testbäddar ut bullret från mycket tystare komponenter, till exempel en kraftöverföringsenhet (PTU). Detta examensar- bete syftar till att lösa dessa problem genom att beskriva de steg som krävs för att virtuellt uppskatta den akustiska strålningen av en PTU med hjälp av transmissionsfelet (TE) som ingångsexcitation via flerkroppsdynamik (multi-body dynamics, MBD). MBD används för att uppskatta kåpans vibrationer, som sedan kan kopplas till ett akustiskt verktyg för att skapa en ljudutstrålningsanalys. Således skapas en genomförbar metod för att mäta den akustiska pre- standan utan att medföra betydande kostnader. Dessutom möjliggör det att lättare integrera ljud- och vibrationsanalyser i designfasen. Detta examensarbete analyserade ljudet som utstrålats på grund av kugghjulsljud, som uppstår på grund av TE och uppträder vid kuggingreppsfrekvensen och dess multiplar. Simuleringarna belyste att TE kan förutsägas exakt med de metoder som beskrivs i detta examensarbete. På samma sätt kan metoden på ett tillförlitligt sätt uppnå kåpans vibrationer. Resultaten från denna analys visar att vid 2000 rpm var PTU känslig för vibrationer vid 500, 1000 och 1500 Hz, den största amplituden var vid 1000 Hz. Dessutom var ljudeffektsnivån (SWL) proportionell mot vibrationsamplituderna i systemet. Analytiska beräkningar genomfördes för att verifiera metoderna och visade en stark korrelation. Dock drogs slutsatsen att experiment krävs för att ytterligare verifiera resultaten i detta arbete.
18
Scrivener, Arthur W. "Acoustic underwater navigation of the Phoenix Autonomous Underwater Vehicle using the DiveTracker system". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA307914.
19
Torsiello, Kevin A. "Acoustic positioning of the NPS Autonomous Underwater Vehicle (AUV II) during hover conditions". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA279934.
Abstract (sommario):
Thesis (M.S. in Mechanical Engineering and Mechanical Engineer)--Naval Postgraduate School, March 1994.Thesis advisor(s): Healey, Anthony J. "March 1994." DTIC Descriptors: Underwater Vehicles, Acoustics, Control, Yaw, Environments, Dynamics, Motion, Motors, Sonar, Transponders, Directional, Nets, Hovering, Bottom, Thrusters, Mine Hunting, Theses, Tunnels, Internal, Stationary, Missions. DTIC Indicators: Autonomous Underwater Vehicles. Authors subject terms: Autonomous Underwater Vehicle, Acoustic Dynaminc Positioning, Marine Vehicle Dynamics, Proportional Derivative Control. Bibliography: p. 116. Also available online.
20
Lindberg, Eskil. "A Vibro-Acoustic Study of Vehicle Suspension Systems : Experimental and Mathematical Component Approaches". Doctoral thesis, KTH, MWL Strukturakustik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121575.
Abstract (sommario):
The objective of the present work is to study the vehicle suspension as a vibro-acoustic system of high complexity, consisting of many sub-systems with fundamentally different acoustical properties. In a parallel numerical and experimental modelling effort, important contributions to the understanding of its behaviour have been achieved. These findings are based on a balance between component investigations and global modelling of the complete system; they have been formulated for the transmission of both tyre-road excitation and friction-induced vibrations in the brake system. Initially an experimental study was conducted on a full vehicle test rig studying the broadband interior brake noise problem of, here named, roughness noise. The purpose of the study was twofold: first, to determine if the transmission from the source to the interior of the vehicle was structure-borne; second, to study the complexity of the suspension as a vibro-acoustic system. Parameters a_ecting the vibro-acoustic source were varied to gain understanding of the source mechanisms. This experimental study laid the foundation of the first part of this thesis (paper A) and provided the directions for the second part, the development of a mathematical modelling approach (paper B and C). In these two papers, methods for analysing the complex vibro-acoustic transfer of structure-borne sound in a vehicle suspension system were developed. The last part was then focussed on the wheel rim influence on the vibro-acoustic behaviour (paper D) of the suspension system. As a whole, the work clearly demonstrates that it is possible to conduct component studies of subsystems in the vehicle suspension system; and from these component studies it is possible draw conclusions that very well may avoid severe degradations in the interior noise of future vehicle generations.QC 20130503
21
Cameron, Christopher John. "Design of Multifunctional Body Panels for Conflicting Structural and Acoustic Requirements in Automotive Applications". Doctoral thesis, KTH, Lättkonstruktioner, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31112.
Abstract (sommario):
Over the past century, the automobile has become an integral part of society, with vastincreases in safety, refinement, and complexity, but most unfortunately in mass. Thetrend of increasing mass cannot be maintained in the face of increasingly stringentregulations on fuel consumption and emissions.The body of work within this thesis exists to help the vehicle industry to take a stepforward in producing vehicles for the future in a sustainable manner in terms of botheconomic and ecological costs. In particular, the fundamentally conflicting requirementsof low weight and high stiffness in a structure which should have good acousticperformance is addressed.An iterative five step design method based on the concepts of multifunctionality andmultidisciplinary engineering is proposed to address the problem, and explained witha case study.In the first step of the process, the necessary functional requirements of the systemare evaluated. Focus is placed on the overall system behavior and diverted from subproblems.For the case study presented, the functional requirements included: structuralstiffness for various loading scenarios, mass efficiency, acoustic absorption, vibrationaldamping, protecting from the elements, durability of the external surfaces,and elements of styling.In the second step of the process, the performance requirements of the system wereestablished. This involved a thorough literature survey to establish the state of theart, a rigorous testing program, and an assessment of numerical models and tools toevaluate the performance metrics.In the third step of the process, a concept to fulfil requirements is proposed. Here, amulti-layered, multi-functional panel using composite materials, and polymer foamswith varying structural and acoustic properties was proposed.In the fourth step of the process, a method of refinement of the concept is proposed.Numerical tools and parameterized models were used to optimize the three dimensionaltopology of the panel,material properties, and dimensions of the layers in a stepwisemanner to simultaneously address the structural and acoustic performance.In the fifth and final step of the process, the final result and effectiveness of the methodused to achieve it is examined. Both the tools used and the final result in itself shouldbe examined. In the case study the process is repeated several times with increasingdegrees of complexity and success in achieving the overall design objectives.In addition to the design method, the concept of a multifunctional body panel is definedand developed and a considerable body of knowledge and understanding is presented.Variations in core topology, materials used, stacking sequence of layers, effects ofperforations, and air gaps within the structure are examined and their effects on performanceare explored and discussed. The concept shows promise in reducing vehicleweight while maintaining the structural and acoustic performance necessary in the contextof sustainable vehicle development.QC 20110311
22
Basu, Somayan. "Acoustic Source Characterization of a Road". Thesis, KTH, Skolan för teknikvetenskap (SCI), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-290036.
Abstract (sommario):
A road can be considered as a noise source based on its traffic density. Intuition says, a road, with closely spaced vehicles, can be classified as a line source and for sparsely spaced vehicles, a collection of point sources. This study deals with the classification of a stretch of highway into either a line source or a collection of point sources based on the sound pressure measured by 7 microphones placed at certain distances from the highway and on the law of attenuation applicable. The results indicate a strong dependence of source classification with the traffic density.En väg kan betraktas som en bullerkälla baserat på dess trafikintensitet. Intuitivt bör en väg med hög trafikintensitet klassificeras som en linjekälla och för få fordon en samling punktkällor. Denna studie handlar om klassificeringen av en motorvägssträcka till antingen en linjekälla eller en samling punktkällor baserat på ljudtrycket uppmätt med sju mikrofoner placerade på varierande avstånd från motorvägen. Resultaten visar att källklassificeringen är beroende av trafiktätheten och av avståndet till vägen.
23
Lind, Nordgren Eleonora. "A study of tailoring acoustic porous material properties when designing lightweight multilayered vehicle panels". Doctoral thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-100701.
Abstract (sommario):
The present work explores the possibilities of adapting poro-elastic lightweight acoustic materials to specific applications. More explicitly, a design approach is presented where finite element based numerical simulations are combined with optimization techniques to improve the dynamic and acoustic properties of lightweight multilayered panels containing poro-elastic acoustic materials. The numerical models are based on Biot theory which uses equivalent fluid/solid models with macroscopic space averaged material properties to describe the physical behaviour of poro-elastic materials. To systematically identify and compare specific beneficial or unfavourable material properties, the numerical model is connected to a gradient based optimizer. As the macroscopic material parameters used in Biot theory are interrelated, they are not suitable to be used as independent design variables. Instead scaling laws are applied to connect macroscopic material properties to the underlying microscopic geometrical properties that may be altered independently. The design approach is also combined with a structural sandwich panel mass optimization, to examine possible ways to handle the, sometimes contradicting, structural and acoustic demands. By carefully balancing structural and acoustic components, synergetic rather than contradictive effects could be achieved, resulting in multifunctional panels; hopefully making additional acoustic treatment, which may otherwise undo major parts of the weight reduction, redundant. The results indicate a significant potential to improve the dynamic and acoustic properties of multilayered panels with a minimum of added weight and volume. The developed modelling techniques could also be implemented in future computer based design tools for lightweight vehicle panels. This would possibly enable efficient mass reduction while limiting or, perhaps, totally avoiding the negative impact on sound and vibration properties that is, otherwise, a common side effect of reducing weight, thus helping to achieve lighter and more energy efficient vehicles in the future.QC 20120815
24
Nordgren, Eleonora. "A study of tailoring acoustic porous material properties when designing lightweight multilayered vehicle panels". Phd thesis, Conservatoire national des arts et metiers - CNAM, 2012. http://tel.archives-ouvertes.fr/tel-00780756.
Abstract (sommario):
The present work explores the possibilities of adapting poro-elastic lightweight acoustic materials to specific applications. More explicitly, a design approach is presented where finite element based numerical simulations are combined with optimization techniques to improve the dynamic and acoustic properties of lightweight multilayered panels containing poro-elastic acoustic materials.The numerical models are based on Biot theory which uses equivalent fluid/solid models with macroscopic space averaged material properties to describe the physical behaviour of poro-elastic materials. To systematically identify and compare specific beneficial or unfavourable material properties, the numerical model is connected to a gradient based optimizer. As the macroscopic material parameters used in Biot theory are interrelated, they are not suitable to be used as independent design variables. Instead scaling laws are applied to connect macroscopic material properties to the underlying microscopic geometrical properties that may be altered independently.The design approach is also combined with a structural sandwich panel mass optimization, to examine possible ways to handle the, sometimes contradicting, structural and acoustic demands. By carefully balancing structural and acoustic components, synergetic rather than contradictive effects could be achieved, resulting in multifunctional panels; hopefully making additional acoustic treatment, which may otherwise undo major parts of the weight reduction, redundant.The results indicate a significant potential to improve the dynamic and acoustic properties of multilayered panels with a minimum of added weight and volume. The developed modelling techniques could also be implemented in future computer based design tools for lightweight vehicle panels. This would possibly enable efficient mass reduction while limiting or, perhaps, totally avoiding the negative impact on sound and vibration properties that is, otherwise, a common side effect of reducing weight, thus helping to achieve lighter and more energy efficient vehicles in the future.
25
Evans, Benjamin Kerbin. "The effect of coded signals on the precision of autonomous underwater vehicle acoustic navigation". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/29044.
Abstract (sommario):
Thesis (Ocean E.)--Joint program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering and Woods Hole Oceanographic Institution), 1999.Includes bibliographical references (p. 127-128).
Acoustic coded signaling offers potentially significant improvements over traditional "toneburst" methods in many underwater applications where error due to noise and multipath interference is a problem. In this thesis, the use of these spread spectrum techniques is analyzed for navigation of the REMUS autonomous underwater vehicle. The accuracy of the current system using Turyn and Barker sequences, as well as toneburst, is quantified, and the sources of the remaining error are examined.
by Benjamin Kerbin Evans.
Ocean E.
26
Bouilloux-Lafont, Antoine, e Pozo Rubén Noya. "Development of Acoustic Simulations using Parametric CAD Models in COMSOL". Thesis, Linköpings universitet, Maskinkonstruktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157612.
Abstract (sommario):
With constantly changing regulations on emissions, heavy commercial vehicles manufacturershave to adapt for their products to preserve their quality while meetingthese new requirements. Over the past decades, noise emissions have become a greatconcern and new stricter laws demand companies to decrease their vehicle pass-bynoise target values.To address the requirements from different disciplines, Scania follows a simulationdriven design process to develop new concept models EATS. The collaboration amongengineers from different fields is thereby necessary in order to obtain higher performancesilencers. However, the pre-processing step in terms of acoustic simulationsis time-consuming, which can slow the concept development process.In this thesis, a new method was introduced to automate the pre-processing of silenceracoustic models and allow for design optimisation based on acoustic performanceresults. A common Scania product study case was provided to several theseswithin the NXD organisation. The collaboration among the master thesis workersaimed to demonstrate the benefits of KBE and MDO and how they can be integratedwithin Scania’s current concept development and product introduction processes.The performed work was divided in the following steps: data collection, methoddevelopment and concluding work. The first step consisted in gathering sufficientknowledge by conducting a thorough literature review and interviews. Then, an initialmethod was formulated and tested on a simplified silencer model. Once approvedand verified, the method was applied to the study case EATS.The study case showed that a complex product can have its acoustic pre-processingstep automated by ensuring a good connectivity among the required software anda correct denomination of the geometrical objects involved in the simulations. Themethod investigated how morphological optimisations can be performed at bothglobal and local levels to enhance the transmission loss of a silencer. Besides optimisingthe acoustic performance of the models, the method allowed the identificationof correlations and inter-dependencies among their design variables and ouput parameters.
27
Fischell, Erin Marie. "Characterization of underwater target geometry from autonomous underwater vehicle sampling of bistatic acoustic scattered fields". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100161.
Abstract (sommario):
Thesis: Ph. D., Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 153-156).
One of the long term goals of Autonomous Underwater Vehicle (AUV) minehunting is to have multiple inexpensive AUVs in a harbor autonomously classify hazards. Existing acoustic methods for target classification using AUV-based sensing, such as sidescan and synthetic aperture sonar, require an expensive payload on each outfitted vehicle and expert image interpretation. This thesis proposes a vehicle payload and machine learning classification methodology using bistatic angle dependence of target scattering amplitudes between a fixed acoustic source and target for lower cost-per-vehicle sensing and onboard, fully autonomous classification. The contributions of this thesis include the collection of novel high-quality bistatic data sets around spherical and cylindrical targets in situ during the BayEx'14 and Massachusetts Bay 2014 scattering experiments and the development of a machine learning methodology for classifying target shape and estimating orientation using bistatic amplitude data collected by an AUV. To achieve the high quality, densely sampled 3D bistatic scattering data required by this research, vehicle broadside sampling behaviors and an acoustic payload with precision timed data acquisition were developed. Classification was successfully demonstrated for spherical versus cylindrical targets using bistatic scattered field data collected by the AUV Unicorn as a part of the BayEx'14 scattering experiment and compared to simulated scattering models. The same machine learning methodology was applied to the estimation of orientation of aspect-dependent targets, and was demonstrated by training a model on data from simulation then successfully estimating the orientations of a steel pipe in the Massachusetts Bay 2014 experiment. The final models produced from real and simulated data sets were used for classification and parameter estimation of simulated targets in real time in the LAMSS MOOS-IvP simulation environment.
by Erin Marie Fischell.
Ph. D.
28
Jonsson, Jonas. "Microsystems Technology for Underwater Vehicle Applications". Doctoral thesis, Uppsala universitet, Ångström Space Technology Centre (ÅSTC), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-171742.
Abstract (sommario):
The aim of this thesis work has been to investigate how miniaturization, such as microsystems technology, can potentially increase the scientific throughput in exploration of hard-to-reach underwater environments, such as the subglacial lakes of Antarctica, or other challenging environments, including cave systems and wrecks. A number of instruments and subsystems applicable to miniature submersibles have been developed and studied, and their potential to provide a high functionality density for size-restricted exploration platforms has been assessed. To provide an onboard camera system with measurement capabilities, simulation and design tools for diffractive optics were developed, and microoptics realized to project reference patterns onto objects to reveal their topography. The influence of murky water on the measurement accuracy was also studied. For longer-range mapping of the surroundings, and under conditions with even less visibility, the performance of a very small, high-frequency side-scanning sonar was investigated using extensive modeling and physical testing. In particular, the interference on the acoustic beam from tight mounting in a hull was investigated. A range in excess of 30 m and centimeter resolution were obtained. Besides these systems, which can be used to navigate and map environments, a two-dimensional, thermal sensor for minute flows was developed. Measuring speed and direction of water flows, this sensor can aid in the general classification of the environment and also monitor the submersible’s movement. As the flow of waters in subglacial lakes is estimated to be minute, the detection limit and sensitivity were investigated. Measurements of water properties are facilitated by the chip-based conductivity, temperature, and depth sensor system developed. Macroscopically, this is an essential oceanographic instrument with which salinity is determined. Contrary to what was expected, MHz frequencies proved to be advantageous for conductivity measurements. Finally, sampling of water using an acoustically enriching microdevice, and even enabling return of pristine samples via the use of integrated latchable, high-pressure valves, was realized and evaluated. Particularly, investigations of the device’s ability to capture and hold on to microorganisms, were conducted. Further developed and studied, these devices – as subsystems to miniature submersibles, or as stand-alone instruments – should enable exploration of previously unreachable submerged environments.Deeper Access, Deeper Understanding (DADU)
29
Fuller, Ryan Michael. "Adaptive Noise Reduction Techniques for Airborne Acoustic Sensors". Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1355361066.
30
Morrison, Archie Todd. "System identification and state reconstruction for autonomous navigation of an underwater vehicle in an acoustic net". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37999.
Abstract (sommario):
Thesis (Ocean. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994.GRSN 683373
Includes bibliographical references (leaves 202-205).
by Archie Todd Morrison, III
Ocean.E.
31
Mahmud, Sakib. "Comparing the Performance of Bottom-Moored and Unmanned Surface Vehicle Towed Passive Acoustic Monitoring Platforms for Marine Mammal Detections". Thesis, University of Louisiana at Lafayette, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10636502.
Abstract (sommario):
Passive acoustic monitoring (PAM) is a more effective method of monitoring cetaceans’ distribution and abundance than conventional visual surveys. Cetaceans are highly vocally active and produce identifiable acoustic signals during echolocation and communication. Three different PAM platforms recorded data in overlapping time periods in the vicinity of the 2010 Deepwater Horizon oil spill site: bottom-moored buoys (EARS), Unmanned Surface Vehicle towed arrays (USV), and subsurface glider-mounted hydrophones. Detection rates of the EARS and USV were compared to investigate their efficiency in detecting marine mammals. Detection events were obtained using independent detectors for each platform and then compared by feeding data through a common detector. Results from both detectors and platforms were compared, and a comparable trend of detection rates was found. The purpose of this study is to aid in the development of cost-efficient PAM methodology for mitigation and environmental impact assessment purposes.
32
Lindberg, Eskil. "Vehicle Disc Brake Roughness Noise : Experimental Study of the Interior Noise andVibro-Acoustic Modelling of Suspension Systems". Licentiate thesis, KTH, MWL Strukturakustik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-39554.
Abstract (sommario):
Prediction of vehicle disc brake roughness noise is a non-trivial challenge. In fact, neither the source mechanisms, nor the transfer paths are so far well understood. Traditionally, disc brake noise problems are studied as part of the friction-induced noise field, where the source is considered to be a more or less local phenomenon related to the brake disc and brake pad. However, for the roughness noise of interest here this viewpoint is not adequate when attempting to solve the interior noise problem since the transfer of vibro-energy from the brake into the vehicle body is a crucial aspect and plays an important role in the understanding and solution to the problem. The vibroacoustic energy transfer associated with the brake roughness noise is a problem where geometrical complexity and material combinations, including rubber bushings, pose an intricate modelling problem. Additionally, system altering effects from moving parts and loadings are important, e.g. due to the steering or brake systems. In addition, the source mechanisms themselves must also be understood to be able to solve the problem. The current work constitutes a combined experimental and theoretical investigation, aiming at an increased understanding of the source, the transfer paths and how they are a affected by change in the operational state. The experimental study of the vehicle disc brake roughness noise, is based on measurements conducted in a laboratory using a complete passenger car. It is found that the interior noise is a structural-borne broadband noise event well correlated to vehicle speed and brake pressure. The results suggest that the friction source may be divided into vibrations created in the sliding direction and vibrations created normal to the contact plane, where the sliding direction levels appear to be proportional to brake pressure according to Coulomb’s friction law; the vibration level in the normal direction of the contact plane on the other hand has behaviour proportional to Hertz contact theory. The measurements also indicate that the brake force created carried by the suspension system when braking will also alter the vibro-acoustic response of the system. To facilitate the theoretical simulations, an approach for modelling of the suspension system is developed. The vibro-acoustic transfer path model developed is using a modal based on the Craig-Bampton method where a restriction on the coupling modes is suggested. The approach suggested uses undeformed coupling interfaces, to couple structures of fundamentally different stiffness such as may be the case in a vehicle suspension system where for instance rubber bushings are combined with steel linking arms. The approach show great potential inreducing computational cost compared to the classical Craig-Bampton method.QC 20110913
33
Yapanel, Umit. "Acoustic modeling and speaker normalization strategies with application to robust in-vehicle speech recognition and dialect classification". Diss., Connect to online resource, 2005. http://wwwlib.umi.com/cr/colorado/fullcit?p3190395.
34
Parra, Martinez Juan Pablo. "On the ECO2 multifunctional design paradigm and tools for acoustic tailoring". Licentiate thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161209.
Abstract (sommario):
Nowadays vehicle design paradigm influences not only the effectiveness of the different means of transport, but also the environment and economy in a critical way. The assessment of the consequences that design choices have on society at large are necessary to understand the limits of the methods and techniques currently employed. One of the mechanisms set in motion is the planned obsolescence of products and services. This has affected vehicle design paradigm in such a way that the variety in the market has shadowed the primary function of vehicle systems: the transport of persons and goods. Amongst the consequences of the expansion of such market is the exponential rise on combustion emissions to the atmosphere, which has become a great hindrance for humans health and survival of ecosystems. The development of evaluation tools for such consequences and their piloting mechanisms is needed so as to implement an ECO2 (Ecological and Economical) vehicle design paradigm. Moreover, the multifunctional design paradigm that drives aeronautical and vehicle engineering is an ever-growing demand of smart materials and structures, able to fulfil multiple requirements in an effective way. The understanding of certain phenomena intrinsic to the introduction of novel materials has found certain limits due to the complexity of the models needed. This work presents as a first step an assessment of the causes and consequences of the vehicle exponential market growth based on the analysis of the planned obsolescence within. Furthermore, a method for the acoustic response analysis of multilayered structures including anisotropic poroelastic materials is introduced. The methodology consists in a plane wave approach as a base for introducing the complex mechanic and acoustic equations governing anisotropic homogeneous media, e.g. open-celled foams, into an alternative mathematical tool manipulating physical wave amplitudes propagation within the studied media. In addition, this method is coupled to a power partitioning and energetic assessment tool so as to understand the phenomena present in complex multilayered designs.QC 20150323
35
Lundblad, Ohan. "The prospects of using acoustic particle separation techniques to separate heavy metals from lake- and seabed sediments". Thesis, KTH, Marcus Wallenberg Laboratoriet MWL, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299414.
Abstract (sommario):
This work aims to investigate if it is realistic to use acoustic particle separation techniques for separating heavy-metals from pump-dredged seabed sediments on a large scale. A premise for the project has been that the material should undergo hydrothermal carbonization (HTC) before acoustic treatment. A number of scientific articles have been studied to understand where the frontier is regarding manipulating small particles in fluids using high frequency sound (ultrasound). Discussion has been held with experts on ultrasound, HTC and chemical analyses. In Conclusion, the feasibility of removal of heavy-metals from HTC-treated material using ultrasound have been evaluated based on theoretical possibilities, comparisons to a selection of similar studies, and on some measured properties of the material. Prerequisites for practical experiments, that would prove or disprove this feasibility, have been explored. The possibility to scale up the process has been discussed.Detta arbete söker svar på om det är realistiskt att använda akustiska metoder för att i stor skala sortera ut tungmetaller från pump-muddrat sjöbottensediment. Utgångspunkten har varit att materialet ska genomgå hydrotermisk karbonisering (HTC) innan akustisk behandling. Ett antal vetenskapliga rapporter har studerats för att kunna förstå var forskningsfronten är, gällande att manipulera små partiklar i vätska med hjälp av högfrekvent ljud (ultraljud). Diskussion har hållits med experter på ultraljud, HTC och kemisk analys. Avslutningsvis har möjligheten att avlägsna tungmetaller ifrån HTC-behandlat material med hjälp av ultraljud evaluerats, baserat på teoretiska möjligheter, jämförelser med ett urval av liknande studier, och begränsade mätningar av egenskaper hos materialet. Förutsättningarna för praktiska experiment, som skulle kunna bevisa eller motbevisa denna möjlighet, har utforskats. Möjligheten att skala upp processen har diskuterats.
36
Grialou, Matthieu. "Vibro-acoustics substructuring : Combining simulations and experimental identification of subdomains for low frequency vehicle acoustics". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI109/document.
Abstract (sommario):
La sonorité de l’échappement joue un rôle significatif sur le confort acoustique des occupants, ainsi que sur le caractère du véhicule. L’étude proposée porte sur la problématique industrielle suivante : « Description et quantification de la transmission du son entre la bouche d’échappement et l’intérieur du véhicule ». Physiquement la transmission sonore entre l’échappement et l’intérieur du véhicule s’effectue en trois étapes : Propagation des ondes sonores de la canule à la surface extérieure du véhicule et conversion en énergie vibratoire (1) ; Le bruit structurel se propage de la peau extérieure du véhicule à l’habillage intérieur (2) ; La surface intérieure du véhicule rayonne de l’énergie dans l’air à l’intérieur (3). Dans l’état de l’art proposé, la méthode de sous-structuration vibro-acoustique Patch Transfer Functions (PTF) est considérée comme une alternative viable à la problématique proposée. Cependant, avant d’appliquer la méthode sur un véhicule complet, la problématique suivante devait être résolue : « Caractérisation expérimentale d’un sous-système par des mesures sur un système couplé ». Ce manuscrit propose une méthode originale pour mesurer des fonctions de transfert d’un système découplé, sur la base de la réponse d’un système couplé. En raison de la nature mal posée du problème inverse, une méthode originale de régularisation a été proposée. La méthode a été validée pas des essais numériques, puis par un test physiqueExhaust noise has a significant impact on acoustic comfort and the sound identity of a vehicle brand. The present study focuses on the: “Description and quantification of the sound transmission from the exhaust outlet into the interior of a vehicle”. Physically the noise propagation from the exhaust pipe to the cabin consists of three steps: The sound waves propagate through the air from the exhaust outlet to the external skin of the vehicle (1); the external skin vibrates and transmits its vibration to the internal skin (2); the internal skin radiates sound in the passengers’ cabin (3). The Patch Transfer Functions method, which is based on the framework of dynamic substructuring, allows for the consideration of this complex problem as simpler subproblems that consist of subsystem interactions. Yet the application of the method to a full vehicle requires addressing the problem: “Characterization of Patch Transfer Functions of a subsystem by means of measurement on a coupled system”. This dissertation presents an original inverse method for the measurement of Patch Transfer Functions. In industrial structures, this in-situ characterization is generally the only possible measurement method. Yet, due to the ill posed nature of the problem, the inversion process is difficult. An original regularization method is proposed. The method is tested through numerical simulations, and is validated with an experimental setup
37
Hwang, Isabel. "An initial study on external warning signals for Quiet Road Transport Vehicles". Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Produktutveckling, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-31111.
Abstract (sommario):
The increasing number of electric and hybrid vehicles in urban areas has shown to be beneficial in reducing both air and noise pollution. However, the lack of sound when driving at low speed has negatively affected the pedestrian safety since many rely on the vehicle sound for orientation. Regulatory bodies have therefore introduced minimum sound requirements for all silent vehicles, which has resulted in a key challenge for car manufacturers to develop external warning signature sounds. The objective of this project has been to study how these signals should sound in order to fit the image of electric and hybrid vehicles and minimize noise and annoyance. To complete the study, five sound concepts with different characteristics and rhythms were developed using the concept generation process. In order to gain subjective impressions of the sounds, three measurement methods were utilized. The first listening test was performed to eliminate the possibility that the sound samples would be perceived variously loud in the upcoming tests. The second listening test was performed to gain information on how suitable the signals are for electric and hybrid vehicles, and the third listening test was conducted to obtain information on how much annoyance the signals contributed with. A reference signal representing an internal combustion engine was included in the tests as well. The results of the measurement methods showed that the sound samples with long tone sequences were more preferred than those with short tone sequences, and that the artificial approach was more popular than the sound of an internal combustion engine vehicle. It was also established that additional tests need to be performed in order to confirm that these results are valid. It was suggested that field tests should be conducted and that new sound concepts should be developed based on the results of these tests.
38
Wang, Yawen. "Vibration and Sound Radiation Analysis of Vehicle Powertrain Systems with Right-Angle Geared Drive". University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491318542819425.
39
Haven, Scott. "Measuring surface ocean wave height and directional spectra using an Acoustic Doppler Current Profiler from an autonomous underwater vehicle". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78181.
Abstract (sommario):
Thesis (S.M.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 117-119).
The Acoustic Doppler Current Profiler (ADCP) is a proven technology which is capable of measuring surface wave height and directional information, however it is generally limited to rigid, bottom mounted applications which limit its capabilities for measuring deep water waves. By employing an upward looking ADCP on a moving platform, such as an autonomous underwater vehicle or submerged float, we show that it is possible to remove the wave induced motion of the platform and accurately measure surface ocean wave information. The platform selected for testing was a REMUS-100 vehicle equipped with an upward and downward looking ADCP and high accuracy Kearfott inertial navigation unit. Additionally, a Microstrain 3DM-GX3-25 Attitude Heading Reference System was tested as a low cost alternative to the Kearfott system. An experiment consisting of multiple REMUS deployments was conducted near the Martha's Vineyard Coastal Observatory (MVCO). The wave induced motion was measured by various inertial and acoustic sensors and removed from the ADCP data record. The surface wave height and mean directional estimates were compared against a Datawell MKIII directional Waverider buoy and bottom mounted 1200 kHz upward looking ADCP at the MVCO. Results demonstrate that the non-directional spectrum of wave height and the mean wave direction as a function of frequency can be accurately measured from an underway autonomous underwater vehicle in coastal depth waters using an ADCP.
by Scott Haven.
S.M.
40
Cellier, Antony Hermann Guy. "Detection and Identification of Instability and Blow-off/Flashback Precursors in Aeronautical Engines using Deep Learning techniques". Thesis, KTH, Kraft- och värmeteknologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-272079.
Abstract (sommario):
The evolution of injection processes toward more fuel efficient and less polluting combustion systems tend to make them more prone to critical events such as Thermo-Acoustic Instabilities, Blow-Off and Flash-Back. Moreover, the addition of Di-Hydrogen as a secondary or as the main fuel is in discussion by aeronautical engines manufacturers. It drastically modifies the stability of the system and thus raise several interrogations concerning the multiplicity of its use. Being able to predict critical phenomena becomes a necessity in order to efficiently operate a system without having to pre-test every configuration and without sacrificing the safety of the user. Based on Deep Learning techniques and more specifically Speech Recognition, the following study presents the steps to develop a tool able to successfully detect and translate precursors of instability of an aeronautical grade swirled injector confined in a tubular combustion chamber. The promising results obtained lead to proposals for future transpositions to real-size systems.Utvecklingen av injektionsprocesser mot mer bränsleeffektiva och mindre förorenande förbränningssystem, tenderar att göra dem mer benägna att utsättas för kritiska händelser som Thermo-Acoustic Instabilities, Blow-Off och Flash-Back. Dessutom diskuterar flygmotorkonstruktörer möjligheten att använda Dihydrogen som sekundärt eller som huvudbränsle. Det modifierar drastiskt systemets stabilitet och det väcker frågan hur man kan använda det effektivt. Att kunna förutsäga kritiska fenomen blir en nödvändighet för att använda ett system utan att behöva att på förhand testa varje konfiguration och utan att reducera användarens säkerhet. Baserat på Deep-Learning-tekniker och Speech-Recognition-tekniker, presenterar följande studie stegen för att utveckla ett verktyg som kan upptäcka och översätta föregångare till instabilitet hos en swirled flygmotorerinsprutningspump som är innesluten i en förbränningskammare. De lovande resultaten leder till idéer om hur man kan anpassa det här verktyg till ett system i verklig storlek.
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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.
Abstract (sommario):
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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Pegoretti, Thaís dos Santos 1986. "Environmental and sound analysis of the acoustic treatment of vehicle compartments = Análise ambiental e sonora do tratamento acústico de habitáculos de veículos". [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265853.
Abstract (sommario):
Orientadores: José Roberto de França Arruda, Pierre LamaryTese (doutorado) ¿ Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Este trabalho tem como objetivo desenvolver uma metodologia capaz de adicionar critérios ambientais à fase de pré-projeto de um tratamento acústico veicular. Essa integração foi realizada através de uma otimização multiobjetivo baseada em um algoritmo genético. Um caso real foi analisado com a metodologia proposta. Ele consiste em um painel acústico multicamadas aplicado em um automóvel de passeio. O método da matriz de transferência é usado para o cálculo do comportamento acústico do painel. Neste método é feita a hipótese simplificadora de painel de área infinita, o que permite um custo computacional muito menor do que modelos de elementos finitos. Para a modelagem de materiais poroelásticos, utiliza-se o modelo de Johnson-Champoux-Allard, que inclui os fenômenos de dispersão de energia resultante da interação térmica e viscosa entre as fases sólida e fluida. O custo computacional menor do modelo é essencial para a otimização. Foram estabelecidos como objetivos da otimização a curva de perda de transmissão desejada e os resultados da análise do ciclo de vida do painel. Uma curva de perda de transmissão em função de bandas de oitava foi estabelecida como um critério de desempenho acústico mínimo. Para os critérios ambientais, o impacto de um painel existente foi estabelecido como máximo. A análise do ciclo de vida quantifica o impacto do produto em relação a diversos aspectos. Na metodologia proposta três critérios foram selecionados inicialmente: aquecimento global, destruição de recursos abióticos e toxicidade da água doce. Finalmente, apenas um deles foi utilizado na otimização, o aquecimento global, pois os critérios máximos estabelecidos para os demais eram facilmente atingidos ao longo da otimização. A otimização multiobjetivos gera como resultado uma frente de Pareto com um conjunto de soluções, e cabe ao projetista escolher a melhor opção, analisando-a em relação ao impacto ambiental e a outros aspectos, tais como disponibilidade e custo
Abstract: This work aims at developing a methodology capable of adding environmental criteria to the pre-design of a vehicular acoustic treatment. This integration was accomplished through a multi-objective optimization based on a genetic algorithm. A real case study was analyzed with the proposed methodology. It consists of a multilayered acoustic panel applied in passenger vehicles. The transfer matrix method is used to calculate the acoustic behavior of the panel. In this method the panel area is infinite. It provides a lower computational cost than finite element models, which can take into account the real dimensions of the panel. The Johnson-Champoux-Allard model was used for poroelastic material modeling. It includes the energy loss generated by the viscous and the thermal interactions between the solid and the fluid media. The lower computational cost of the model is essential for the optimization. The desired acoustic transmission and results of the life cycle analysis of the panel were established as the optimization objectives. A transmission loss curve in octave bands was defined as a minimum noise performance criterion. For the environmental criteria, an existing panel behavior was established as the maximum. The life cycle assessment quantifies the product impact with respect to many aspects. In the proposed methodology, three criteria were initially selected: global warming, abiotic depletion, and fresh water aquatic ecotoxicity. Finally, only one of them was used in the optimization, the global warming, because the maximum values established for the other criteria were easily achieved during the optimization. The multi-objective optimization provides a Pareto front solutions set, and it is up to the designer to choose the best option, analyzing the solution set with relation to environmental impact and other aspects, such as availability and cost
Doutorado
Mecanica dos Sólidos e Projeto Mecanico
Doutora em Engenharia Mecânica
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Mak, Lin Chi Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Non-Line-of-Sight localisation of a sound source". Awarded by:University of New South Wales. Mechanical & Manufacturing Engineering, 2009. http://handle.unsw.edu.au/1959.4/44702.
Abstract (sommario):
This thesis proposes two acoustic localisation techniques that are accurate in Non-Line-of-Sight (NLoS) conditions and system implementation of the proposed techniques. Such conditions can cause positive bias errors, namely NLoS errors, in the measured Time-of-Arrivals (ToAs) of first-arrival signals received by microphones and thus reduce the positioning accuracy. The primary issue of the thesis is to precisely estimate and correct the NLoS errors by modelling the received first-arrival signals. The first proposed technique uses multiple on-ground microphones to locate a sound source. The proposed technique approximately estimates and corrects the NLoS errors based on an initial guess of the sound source position and a map. The localisation is then achieved by iteratively correcting the ToAs and updating the sound source location. The strength of the proposed technique is that its accuracy is not notably affected by small or known obstacles. The proposed technique is implemented into two localisation systems of controlled and uncontrolled sound sources. The performance of the proposed technique is investigated by its comparison with three other time-based localisation techniques in series of experiments and simulations, showing at least 10% improvement by the proposed technique under various background noise levels. The second proposed technique localises a sound source using a single on-ground microphone subject to an assumption of a single diffraction in the first-arrival signal. To predict the angular and radial coordinates of the sound source relative to the diffraction point, a new magnitude delay frequency profile is proposed. The profile can be estimated by applying the uniform geometrical theory of diffraction and be extracted from measured signals using a derived formulation. Similar to the first technique, the second proposed technique estimates the measured delay of the first-arrival signal for computing the radial coordinate. The angular coordinate is then obtained by matching the estimated and measured profiles at the measured delay. A key achievement of the second proposed technique is enabling NLoS localisation using only one microphone without any time-consuming pre-measurement. This technique is implemented into a localisation system of a controlled sound source and validated experimentally with three different sound sources and under two background noise levels.
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Edwards, Matthew Ryan. "Development of an automotive steering-wheel mounted audio user Interface". Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53529.
Abstract (sommario):
A tier 1 automotive components supplier has developed a virtual user interface system for the purpose of replacing currently existing physical buttons mounted on automotive steering wheels. The system is capable of generating acoustic and vibratory feedback to the user for the purpose of mimicking the sound and feel of mechanical buttons. The work performed in this thesis served to investigate what the input waveform should be to the system in order to generate a desired audio output signal. Additionally, subjective testing in the form of a sound jury was conducted in order to identify which types of sounds should be associated with which command functions in order to indicate successful initiation of the intended function. A model for grouping command functions into banks, where each bank is assigned a single sound, was then developed for the purpose of reducing the total number of button sounds used in an automotive environment.
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Bagley, Phil. "Investigations of the behaviour of demersal grenadier fish, Coryphaenoides (Nematonurus) armatus in the abyssal Pacific and Atlantic oceans using an autonomous acoustic tracking vehicle". Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU049186.
Abstract (sommario):
The deep-sea has long been perceived as a food limited environment. The recent discovery of seasonal inputs of organic matter into the deep, in areas of the North Pacific and North Atlantic Oceans, has led to questions about the behaviour of deep-sea demersal animals. This thesis describes an autonomous acoustic tracking system (AUDOS: Aberdeen University Deep Ocean Submersible) developed to address the behaviour question; primarily of the demersal grenadier fish, Coryphaenoides (Nematonurus) armatus, but also other shallower living species. Deep-sea acoustic pinger and Code Activated Transponder (CAT) ingestible fish tags, capable of operating at depths of 600m, are described. Deep-sea pingers operated with an early version of AUDOS, returning directional information on fish which ingested tags. The CAT, which is acoustically interrogated by a scanning sonar mounted on AUDOS, returns precise direction and range of individually tagged fish. AUDOS is an autonomous free-fall vehicle incorporating a microprocessor based logging unit which also controls a camera, current meter and compass, enabling several tagged fish to be individually located within a 500m radius. On-board environmental monitoring allows relationships between fish movements and the localised current to be addressed. Three locations were visited during 5 research cruises, Station M (32o50'N, 122o50'W) in the North Pacific Ocean, station MAP (29o30'N, 21o16'W) in the North Atlantic Ocean and the Porcupine Seabight area (51o20'N, 14o0'W) also in the North Atlantic Ocean. Tracking results indicate that C. (N.) armatus adopt an active foraging strategy at each of these stations. Evidence was found for a faster mean swimming speed, for the grenadier, in October (0.0692 m.s-1) compared to February (0.0262 m.s-1) at station M. Fish activity is elevated in October following a seasonal enrichment of the benthos by downward flux of particulate organic matter from the surface. At the Continental slope region of the Porcupine Seabight, the grenadier was found to be moving up the slope rather than directly using the current to forage for food (Station MAP).
46
Holmberg, Andreas. "Experimental Determination of Aeracoustic Sources in Low Mach Number Internal Flows". Licentiate thesis, KTH, MWL Strömningsakustik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-26133.
Abstract (sommario):
In this thesis, the in-duct experimental methods for determining aeroacoustic N-ports of in-duct elements are discussed and improved. The scattering matrix determination methods and the related wave decomposition methods are evaluated from measurements in an empty duct carrying a mean flow. The improvements of a new over-determination method for the source part of the N-port is studied using simulations and measurements; in quiescent air as well as measurements of the flow associated noise of a mixer plate, here a triangular plate inserted at an angle in a duct. The new method is shown to improve suppression of random errors while no improvement is achieved for bias errors. Further, the methods are applied in the study of two different aeroacoustic phenomena; one is the effect on the flow associated noise of the triangular plate achieved by varying the bending stiffness. For the most resilient plate tested, it is observed that when the Strouhal number of the flow noise coalesce with the Helmholtz number of a specific eigen-mode of the plate, the noise is drastically dampened. There is also a weaker broad band effect. The other phenomena studied is the amplification and attenuation obtained for sound waves propagating in a T-junction of rectangular ducts. It is found that by adding only 10% of inflow in the side branch relative to that in the main branch, the amplification is heavily increased. By adding another 10% the amplification is again similar to that of no side branch flow. Adding further flow lessens the effects still.QC 20101118
Experimental characterization of aero-acoustic sources
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Cousson, Rémi. "Identification de sources acoustiques au passage d'un véhicule routier par imagerie acoustique parcimonieuse dans le domaine temporel". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI106/document.
Abstract (sommario):
Le présent travail de recherche s'inscrit dans le cadre de la caractérisation de l'émission de bruit des véhicules routiers. On désire identifier les sources de bruit d'un véhicule en mouvement, lors de son passage sur une voie de circulation en conditions réelles, à partir de mesures acoustiques effectuées à poste fixe en bord de voie. Les méthodes d'imagerie acoustique utilisées actuellement présentent des performances insuffisantes sur véhicules routiers. Un état de l'art a permis d’identifier une méthode existante, MSA-PSF, consistant à effectuer sous certaines hypothèses une déconvolution sur sources mobiles dans le domaine fréquentiel, et originellement utilisée en aéronautique. Cette méthode est ici adaptée au contexte des véhicules routiers. Dans un deuxième temps, une approche originale est introduite pour répondre spécifiquement aux contraintes de ce contexte : CLEANT. Il s’agit d’une méthode itérative, dans le domaine temporel avec une approche large bande, qui prend en compte les effets du déplacement des sources et qui comporte deux paramètres permettant d’affiner les résultats : le facteur de boucle et le critère d’arrêt. Une version filtrée en fréquence est également proposée et montre une amélioration de l’identification de sources secondaires dans certains cas. CLEANT présente l’avantage d’obtenir des signaux-sources temporels reconstruits, ouvrant la voie à d’autres analyses, en particulier l’utilisation de la cohérence avec des signaux issus de mesures embarquées pour la séparation des contributions de sources décorrélées. MSA-PSF et CLEANT sont évaluées sur des simulations numériques à l'aide d'indicateurs mesurant leurs performances sur les aspects localisation et quantification de sources. Elles sont par la suite testées expérimentalement en conditions contrôlées de laboratoire, par l'utilisation d'une source mobile. Cette expérience permet une première application à un cas pratique, impliquant un mouvement linéaire, la présence de deux sources simultanées et des signaux de différentes natures (tonale et large bande). Enfin, elles sont comparées à l’approche classique de formation de voies sur source mobile, dans le cadre d’une expérience avec véhicule en conditions réelles. L'approche originale CLEANT fournit des résultats très encourageants, représentant une amélioration de la formation de voies classique, notamment en basse fréquence sur les cas testés. L'application à un véhicule en conditions réelles illustre certains comportements potentiellement problématiques de CLEANT et les solutions apportées par sa version filtrée en fréquence ou par l'ajustement de ses différents paramètres. Un premier test des approches par référencement avec des signaux issus de mesures embarquées est également présenté pour discriminer l'origine physique des sources, et souligne l'incidence de la brièveté des signaux inhérente au contexte de sources au passageThe study detailed in this manuscript is part of the effort to characterize the noise emission from road vehicles. We wish to identify the noise sources of a moving vehicle, when driven on a roadway in real-world conditions, with roadside acoustic measurements. The current acoustic imaging methods do not provide sufficient performance on road vehicles. A state of the art led to the selection of an existing method, MSA-PSF, which consists in deconvolving signals from mobile sources in the frequency domain under certain assumptions, and was originally developed for aeroacoustics. This method is adapted here to the context of road vehicles. Then, an original approach is proposed in order to tackle the specific constraints of this context: CLEANT. This is an iterative method, performed in time domain with a wideband approach, which takes into account the effect of sources motion and includes two parameters designed to refine the result: the loop factor and the stopping criterium. A further version of the algorithm, including a frequency filter, is also proposed and shows significant improvement in identifying secondary sources in some particular cases. An interesting point of CLEANT is the availability of the sources reconstructed time signals, which enables other types of analysis, especially the use of the coherence with signals from on-board measurements in order to separate the contributions of uncorrelated sources. MSA-PSF and CLEANT are evaluated with numerical simulations and a set of indicators to measure their source localization and quantification performance. They are then tested in a controlled laboratory conditions experiment, using a moving source. This experiment represents a first application of the methods to a practical case, involving a linear motion, two simultaneous sources and different kinds of signals (tone and wideband). They are finally compared to the classical approach of moving source beamforming, within the frame of an experiment on a road vehicle, in real-world conditions. The original approach CLEANT yields very encouraging results, and is a clear improvement from the conventional beamforming, especially at low frequency for the tested cases. Applying it to a road vehicle in real-world conditions highlights a potentially troublesome behavior of the method, and the solution brought by CLEANT's frequency filtered version, or by adapting its various parameters. The coherence with reference signals to discriminate the physical origins of the sources is also tested and underlines the role of the short duration of the signals related to the sources passing-by context
48
Cai, Rui [Verfasser]. "Methode zur objektivierten Komfortbeurteilung antriebsstranginduzierter Fahrzeugschwingungen am Fahrzeug-Rollenprüfstand = Method for evaluating the subjective perception of powertrain induced vehicle vibration using objective characteristic parameters on the acoustic roller test bench / Rui Cai". Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1225401135/34.
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Букар, Григорій Миколайович. "Акустична система виявлення і локалізації малих літальних апаратів". Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/34775.
Abstract (sommario):
Дипломна робота містить основну частину на 30 аркушах, 17 ілюстрацій та 1 таблицю. Метою роботи є розробка акустичної системи пеленгування безпілотних літальних апаратів. В роботі проведено аналітичний огляд літератури, встановлені акустичні характеристики випромінювання, вибрано тріангуляційний спосіб локалізації безпілотних літальних апаратів. Для визначення пеленгів запропоновано використати кореляційний метод. Комп’ютерне моделювання кореляційного пеленгатора дало змогу визначити відношення сигнал/завада для забезпечення достовірного виявлення.Thesis contains the bulk of the 30 pages, 17 illustrations and 1 table. The aim of the work is to develop an acoustic guidance system for unmanned aerial vehicles. The analytical review of the literature is carried out, the acoustic characteristics of radiation are established, the triangulation method of localization of unmanned aerial vehicles is chosen. It is proposed to use the correlation method to determine the bearings. Computer simulation of the correlation direction finder made it possible to determine the signal-to-noise ratio to ensure reliable detection.
50
Marr, William J. "Acoustic based tactical control of underwater vehicles". Diss., Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FMarr%5FPhD.pdf.
Abstract (sommario):
Thesis (Ph. D. in Mechanical Engineering)--Naval Postgraduate School, June 2003.Dissertation supervisor: Anthony J. Healey. Includes bibliographical references (p. 169-173). Also available online.