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Sagers, Jason Derek. "Analog Feedback Control of an Active Sound Transmission Control Module." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2461.pdf.
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Goldstein, Andre L. "Control of Sound Transmission with Active-Passive Tiles." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27913.
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Nowadays, numerous applications of active sound transmission control require lightweight partitions with high transmission loss over a broad frequency range and simple control strategies. In this work an active-passive sound transmission control approach is investigated that potentially addresses these requirements. The approach involves the use of lightweight stiff panels, or tiles, attached to a radiating base structure through active-passive soft mounts and covering the structure surface. The resulting double-partition configuration was shown to have good high frequency passive isolation, but poor low frequency transmission loss due to the coupling of the tiles to the base vibration through the air gap. The low frequency transmission loss performance of the partition was increased by using the active mounts to cancel the local volume velocity of the tiles. The use of a decentralized control approach with independent single channel controllers for each tile facilitates the implementation of a multiple tile system in a large scale application.
A coupled structural-acoustic model based on an impedance mobility matrix approach was formulated to investigate the potential performance of active-passive tile approach in controlling sound transmission through plates. The model was initially applied to investigate the sound transmission characteristics of a double-panel partition consisting of a single tile-plate configuration and then extended to model a partition consisting of multiple-tiles mounted on a plate. The system was shown to have significant passive performance above the mass-spring-mass resonance of the double-panel system. Both feedback and feedforward control approaches were simulated and shown to significantly increase the transmission loss of the partition by applying control forces in parallel with the mounts to reduce the tile normal velocity. A correspondent reduction in sound radiated power was obtained over a broad frequency range limited by the tile stiffness.
The experimental implementation of the active-passive tile approach for the control of sound transmission through plates was also performed. Two main experimental setups were utilized in the investigations, the first consisting of a single tile mounted on a clamped plate and the other consisting of four active tiles mounted of a simply supported plate. Tile prototypes were implemented with lightweight stiff panels and integrated active-passive mounts were implemented with piezoelectric Thunder actuators. Both analog feedback and digital feedforward control schemes where designed and implemented with the objective of reducing the normal velocity of the tiles. Experimental results have demonstrated significant broad frequency range reductions in the sound transmission through the partition by active attenuation of the tile velocity. In addition, the experiments have shown that decentralized control can be successfully implemented for multiple tiles systems. The active-passive sound transmission control characteristics of the systems experimentally studied were observed to be in accordance with the analytical results.Ph. D.
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Bianchi, Emanuele. "Smart panel with an array of decentralised control systems for active structural acoustic control." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274667.
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Davis, Nathan A. "Sound Absorptivity of Various Designs of 3-D Printed Acoustic Paneling." Youngstown State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1619960590635589.
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Jones, C. Mair A. "Scattering of sound by a semi-infinite sandwich panel perforated on one side." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46846.
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Mu, Rui Lin. "Improvement of Sound Insulation Performance of Multi-layer Structures in Buildings." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174914.
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Alujević, Neven. "Smart double panel with decentralised active damping units for the control of sound transmission." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/64537/.
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This thesis presents a comprehensive study of a smart aircraft double panel for active vibroacoustic control. The control of the double panel vibration is implemented using Multi-Input-Multi-Output (MIMO) decentralised velocity feedback loops. The loops are applied via an array of electrodynamic force actuators and collocated velocity sensors. The actuators are located in an air cavity between the two panels such that they can react against the two panels. Two velocity sensors per actuator are used. Either sensor is located at the source and radiating panel footprint of an actuator. The error velocity is formed by subtracting weighted sensor outputs. In the introductory part of the thesis a survey of aircraft interior noise is given, and stateof- the-art passive and active noise control methods are presented. In Chapter two the mathematical model for the theoretical analysis of the smart double panel is formulated and a parametric study of passive sound transmission is performed using the mathematical model. In Chapter three the performance of decentralised feedback control systems using absolute and relative velocity is analysed theoretically. In Chapter four the stability and performance of decentralised feedback control systems using reactive actuators driven with weighted velocity error signals is analysed theoretically. In Chapter five the stability of decentralised feedback control systems using weighted velocity error signals and electrodynamic reactive actuators is analysed experimentally. In Chapter six the performance of decentralised feedback control systems using weighted velocity error signals and reactive actuators is analysed experimentally.
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McLeod, Sharynne, S. Verdon, C. Bowden, and A. Lynn Williams. "Aspirations of an International Expert Panel for Working with Multilingual Children with Speech Sound Disorders." Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/2057.
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Liu, Bilong. "Acoustical Characteristics of Aircraft Panels." Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4102.
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Meng, Han. "Acoustic properties of novel multifunctional sandwich structures and porous absorbing materials." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC008/document.
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La mise en oeuvre de matériaux acoustiques est une méthode efficace et très utilisée pour réduire le bruit le long de sa propagation. Les propriétés acoustiques de nouvelles structures sandwich multifonctionnelles et de matériaux absorbants poreux sont étudiées dans la thèse. Les principales contributions de la thèse sont les suivantes: Les panneaux sandwich ont généralement d'excellentes propriétés mécaniques et un bon indice de perte en transmission sonore (STL), mais aucune capacité d'absorption acoustique. De nouvelles structures sandwich multifonctionnelles sont développées en intégrant des microperforations et des matériaux absorbants poreux aux panneaux sandwich ondulés et en nid d’abeilles conventionnels, structurellement efficaces pour obtenir de bons STL et de bonnes absorptions en basses fréquences. Le coefficient d'absorption acoustique (SAC) et la perte en transmission (STL) des panneaux sandwich ondulés sont évalués numériquement et expérimentalement en basse fréquence pour différentes configurations de perforations. Les modèles éléments finis (EF) sont construits en tenant compte des interactions vibro-acoustiques sur les structures et des dissipations d'énergie, visqueuse et thermique, à l'intérieur des perforations. La validité des calculs FE est vérifiée par des mesures expérimentales avec les échantillons testés obtenus par fabrication additive. Par rapport aux panneaux sandwich ondulés classiques sans perforation, les panneaux sandwich perforés (PCSPs) avec des perforations dans leur plaque avant présentent non seulement un SAC plus élevé aux basses fréquences, mais aussi un meilleur STL, qui en est la conséquence directe. L'élargissement des courbes des indices d’absorption et de transmission doit être attribué à la résonance acoustique induite par les micro-perforations. Il est également constaté que les PCSPs avec des perforations dans les plaques avant et les parois internes onduleés ont les fréquences de résonance les plus basses de tous les PCSPs. En outre, les performances acoustiques des panneaux sandwich en nid d'abeilles avec une plaque avant microperforée sont également examinées. Un modèle analytique est présenté avec l'hypothèse que les déplacements des deux plaques sont identiques aux fréquences inférieures à la fréquence de résonance des plaques. Le modèle analytique est ensuite validé par des modèles d'éléments finis et des résultats expérimentaux existants. Contrairement aux panneaux sandwich en nid d'abeilles classiques qui sont de piètres absorbeurs de bruit, les sandwichs en nid d'abeilles perforés (PHSPs) conduisent à un SAC élevé aux basses fréquences, ce qui entraîne en conséquence un incrément dans le STL basse fréquence. Les influences de la configuration du noyau sont étudiées en comparant les PHSPs avec différentes configurations de noyaux en nids d'abeilles. […]Implementation of acoustic materials is an effective and popular noise reduction method during propagation. Acoustic properties of novel multifunctional sandwich structures and porous absorbing materials are studied in the dissertation. The main contributions of the dissertation are given as, Sandwich panels generally have excellent mechanical properties and good sound transmission loss (STL), but no sound absorption ability. Novel multifunctional sandwich structures are developed by integrating micro perforations and porous absorbing materials to the conventional structurally-efficient corrugated and honeycomb sandwich panels to achieve good SAC and STL at low frequencies. Low frequency sound absorption and sound transmission loss (STL) of corrugated sandwich panels with different perforation configurations are evaluated both numerically and experimentally. Finite element (FE) models are constructed with considerations of acousticstructure interactions and viscous and thermal energy dissipations inside the perforations. The validity of FE calculations is checked against experimental measurements with the tested samples provided by additive manufacturing. Compared with the classical corrugated sandwich panels without perforation, the perforated corrugated sandwich panels (PCSPs) with perforations in its face plate not only exhibits a higher SAC at low frequencies but also a better STL as a consequence of the enlarged SAC. The enlargement of SAC and STL should be attributed to the acoustical resonance induced by the micro perforations. It is also found that the PCSPs with perforations in both the face plates and corrugated cores have the lowest resonance frequencies of all the PCSPs. Besides, the acoustic properties of honeycomb sandwich panels with microperforated faceplate are also explored. An analytical model is presented with the assumption that displacements of the two faceplates are identical at frequencies below the faceplate resonance frequency. The analytical model is subsequently verified by finite element models and existing experimental results. Unlike classical honeycomb sandwich panels which are poor sound absorbers, perforated honeycomb sandwiches (PHSPs) lead to high SAC at low frequencies, which in turn brings about increment in the low frequency STL. Influences of core configuration are investigated by comparing PHSPs with different honeycomb core configurations. In order to enlarge the SAC bandwidth of perforated sandwich panels, porous absorbing materials are added to the cores of novel perforated sandwich panels. FE models are set up to estimate the SAC and STL of perforated sandwich panels with porous materials. Results show that perforated sandwich panels with porous material can provide SAC with broader bandwidth and lower resonance frequency than that without porous materials. Whereas the peak values in the SAC and STL curves are reduced due to the weakened acoustical resonance by the porous materials. […]
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Liu, Biong. "Sound transmission through aircraft panels /." Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-494.
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Phillips, Timothy Jason Nirmal. "Sound Transmission Loss of Sandwich Panels." Thesis, University of Canterbury. Department of Mechanical Engineering, 2012. http://hdl.handle.net/10092/9210.
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The sound transmission loss characteristics of plywood based sandwich panels were investigated. Measurements were made of the sound transmission loss of a range of materials and used as a baseline for comparison while a sound transmission loss optimisation method was developed. A unique test rig was built and calibrated to determine selected mechanical properties of materials of interest. The results of sound transmission loss and material properties measurements were used to select an appropriate prediction model, which was then used in conjunction with a mathematical optimisation model to determine combinations of materials and panel parameters which result in improved sound transmission loss. An effort was made to reproduce these predictions in experimental testing by constructing several prototype panels.
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Cowan, Andre James. "Sound Transmission Loss of Composite Sandwich Panels." Thesis, University of Canterbury. Mechanical Engineering, 2013. http://hdl.handle.net/10092/7879.
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This thesis examines the sound transmission loss (STL) through composite sandwich panel systems commonly used in the marine industry. Experimental, predictive and optimisation methods are used to evaluate the acoustic performance of these systems and to improve their acoustic performance with noise treatment.
The complex nature of the material properties of composite sandwich panels was found to be dependent not only on the physical properties but also the frequency of incident noise. Young’s modulus was found to reduce with increasing frequency as has been predicted in the literature which is due to the shear stiffness dominating over the bending stiffness. Two methods for measuring these properties were investigated; ‘fixed-free’ and ‘free-free’ beam boundary condition modal analyses. The disagreement between these methods was identified as the clamping fixed nature that increased flexibility of the beam.
Composite sandwich panels can be modelled as homogeneous isotopic materials when predicting their acoustic performance provided the dilatational resonance is above the frequency range of interest. Two such panels were modelled using this simple sound insulation prediction method, but the agreement between theory and experimental results was poor. A variable Young’s modulus was included in the model but agreement remained relatively poor especially in the coincidence frequency region due to variation of Young’s modulus with frequency.
A statistical method of optimisation of the parameter settings by fractional factorial design proved successful at identifying the important parameters that affect the sound transmission class (STC) of a noise treatment material applied to a panel. The decouple foam layer and attachment method were the most significant factors. The same method, with higher resolution was then used to identify the important parameters that affected the noise reduction class (NRC) finding that the outer foam thickness without a face sheet were the most significant factors. The independent optimisation studies performed for each of the STC and NRC produced conflicting results meaning that both could not be achieved simultaneously.
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Rousounelos, Andreas. "Reduction of sound radiation from automotive-type panels." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6314.
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The problem of the effect of structural modifications on sound radiation from a structure is very important with many applications in the design of a variety of products. In practise, for the design of acoustically optimum structures simplified theoretical models are used which can lead to unexpected behaviour of the real structures. Alternatively, measurements or numerical simulation can be used. The disadvantage of these two methods is that the study of alternative structures (structures with different properties) is not easy since for every modification a new structure must be manufactured or a new numerical model must be created. Moreover, these two methods do not easily give an insight into the physical mechanisms of sound radiation from modified structures. In the first part of this thesis the problem of vibration and sound radiation from a plate with an attached beam stiffener is studied theoretically. This extends the current theories of vibroacoustic behaviour of infinite plates with an infinitely long beam discontinuity and infinite plates with an infinite number of equidistant beam discontinuities forming a periodic structure. Firstly, the propagation of flexural waves and the subsequent sound radiation from an infinitely long plate strip is considered. The scattering of plate flexural waves by a finite beam across its width is considered. Changes to the mean square velocity, sound power and radiation efficiency of the plate strip due to the introduction of the beam stiffener are identified. Simplified approximate analytical expressions for the low-frequency range, well below the critical frequency, are also presented. This model is extended for the case of a finite rectangular plate by incorporating wave reflection from the two additional boundaries of the plate. Expressions for the radiation efficiency and the mean squared velocity of the stiffened plate are derived. The results are compared with results derived using well established numerical methods. For structures with more complicated modifications the derivation of analytical expressions is not easy. For this reason numerical optimisation is often used. In this thesis numerical optimisation is used to optimise the modes of a structure in order to radiate acoustic energy weakly into the acoustic medium. The effectiveness of point mass and line stiffener modification to create acoustically optimum modeshapes in a flat simply supported plate is firstly studied. The results show significant reduction in the sound power radiated by the optimised structural modes. These results are also verified experimentally. This optimisation method has certain advantages when it is used on automotive panels. The main advantage is that the panel under consideration can be isolated from the rest of the automotive structure and it can be optimised alone. This drastically reduces the time required and makes the optimisation practically applicable. A simplified car model is used and the proposed optimisation is applied to one of its floor panels. Firstly, point masses and line stiffeners are used as structural modifications to create weakly radiating modeshapes. Then more commonly used geometrical modifications are used on the floor panel. Two such modifications are studied; swages and domes. The results show a significant reduction in the radiation effciency and sound power radiated by the optimised panel.
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Sy, Djibril. "Modélisation et optimisation des performances acoustiques d'un tablier d'automobile en alliage de magnésium." Mémoire, Université de Sherbrooke, 2010. http://savoirs.usherbrooke.ca/handle/11143/1589.
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Résumé : Ce projet fait partie du projet MFERD (Magnésium Front End Research and Development) qui vise à développer les technologies permettant de rendre les alliages de Magnésium (Mg) comme un principal matériau structural pour les voitures (aujourd'hui essentiellement constituées d'acier quatre fois plus lourd que le Mg) afin d'en réduire leur masse pour des raisons environnementales et sécuritaires. Dans ce travail de maîtrise nous avons regardé la partie acoustique dans le cas d'un tablier (structure métallique derrière le tableau de bord) en magnésium. En effet, le confort acoustique à l'intérieur des voitures est devenu un argument de marketing d'une grande importance. Le tablier en séparant le compartiment moteur, source de bruit, de l'habitacle, joue un rôle important dans l'isolation acoustique de l'intérieur de la voiture. Ainsi le passage d'un tablier en acier à un tablier en Mg ne doit pas entraîner une baisse de performance. Dans ce travail, nous avons d'abord effectué une revue de la littérature sur les types de traitements acoustiques utilisés dans l'industrie automobile ainsi que des différentes techniques de leur modélisation. Nous avons ensuite comparé les performances acoustiques du tablier en Mg sur lequel on a appliqué des traitements classiques (à une couche, deux couches et trois couches) à celles des tabliers en acier et en aluminium et ce, à masse surfacique, raideur et/ou fréquences de résonnances égales. Finalement nous avons optimisé différents concepts de traitements acoustiques innovants appliqués sur le tablier en Mg en vue d'avoir des performances acoustiques semblables ou supérieures à celles du tablier en acier classique. L'optimisation s'est faite à partir d'un modèle SEA (Statitical Energy Analysis) couplé à un code d'optimisation basé sur un algorithme génétique||Abstract : This work is part of the MFERD (Magnesium Front End Research and Development) project which goal is to develop enabling technologies for the use of magnesium alloys as a principal structural material for cars (mainly made in steel which is four time heavier than magnesium) in order to reduce their mass for both, environmental and security concerns. In this work we have focused on the acoustic part, in the case of a magnesium alloy dash panel. The dash board, by separating the engine compartment from the interior cabin, plays a critical role in the insulation of the car interior. Since the acoustic comfort inside the car has become a marketing argument of great importance, the passage from steel to magnesium dash panel should not deteriorate acoustic performances. In this work, we first conducted a literature review on the types of acoustic treatments used in the automotive industry as well as various techniques of their modeling. We then compared the acoustic performances of a Mg dash with attached traditional acoustic treatments (single-layer, two layers and three layers) to those of a steel and aluminum dash panels with the same mass density, stiffness and/or frequency of resonances. Finally, we optimized different concepts of innovative sound packages applied on the Mg dash panel to achieve a noise performance similar or superior to those of a conventional steel dash. The optimization was done using a SEA (Statitical Energy Analysis) model, coupled with an optimization code based on a genetic algorithm.
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Schiller, Noah Harrison. "Decentralized control of sound radiation from periodically stiffened panels." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/30148.
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Active structural acoustic control has previously been used to reduce low-frequency sound radiation from relatively simple laboratory structures. However, significant implementation issues have to be addressed before active control can be used on large, complex structures such as an aircraft fuselage. The purpose of this project is to extend decentralized structural control systems from individual bays to more realistic airframe structures. In addition, to make this investigation more applicable to industry, potential control strategies are evaluated using a realistic aft-cabin disturbance identified from flight test data.
This work focuses on decentralized control, which implies that each control unit is designed and implemented independently. While decentralized control systems are relatively scalable, performance can be limited due to the destabilizing interaction between neighboring controllers. An in-depth study of this problem demonstrates that the modeling error introduced by neighboring controllers can be expressed as the product of the complementary sensitivity function of the neighboring control unit multiplied by a term that quantifies the diagonal dominance of the plant. This understanding can be used to improve existing control strategies. For instance, decentralized performance can often be improved by penalizing control effort at the zeros of the local control model. This stabilizes each control unit and reduces the modeling error induced on neighboring controllers. Additional analyses show that the performance of decentralized model-based control systems can be improved by augmenting the structural damping using robust, low-authority control strategies such as direct velocity feedback and positive position feedback. Increasing the structural damping can supplement the performance of the model-based control strategy and reduce the destabilizing interaction between neighboring control units. Instead of using low-authority controllers to stabilize the decentralized control system, another option is to modify the model-based design. Specifically, an iterative approach is developed and validated using real-time control experiments performed on a structural-acoustic system with poles close to the stability boundary, non-minimum phase zeros, and unmodeled dynamics. Experiments demonstrate that the iterative control strategy, which combines frequency-shaped linear quadratic Gaussian (LQG) control with loop transfer recovery (LTR), is capable of achieving 12dB peak reductions and a 3.6dB integrated reduction in radiated sound power from a rib-stiffened aluminum panel.Ph. D.
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Ramanathan, Sathish Kumar. "Sound transmission properties of honeycomb panels and double-walled structures." Doctoral thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96538.
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Sandwich panels with aluminium face sheets and honeycomb core material have certain advantages over panels made of wood. Some of the advantages of these constructions are low weight, good moisture properties, fire resistance and high stiffness to-weight ratio etc. As product development is carried out in a fast pace today, there is a strong need for validated prediction tools to assist during early design stages. In this thesis, tools are developed for predicting the sound transmission through honeycomb panels, typical for inner floors in trains and later through double-walled structures typical for rail-vehicles, aircrafts and ships. The sandwich theory for wave propagation and standard orthotropic plate theory is used to predict the sound transmission loss of honeycomb panels. Honeycomb is an anisotropic material which when used as a core in a sandwich panel, results in a panel with anisotropic properties. In this thesis, honeycomb panels are treated as being orthotropic and the wavenumbers are calculated for the two principal directions. The wavenumbers are then used to calculate the sound transmission using standard orthotropic theory. These predictions are validated with results from sound transmission measurements. The influence of constrained layer damping treatments on the sound transmission loss of these panels is investigated. Results show that, after the damping treatment, the sound transmission loss of an acoustically bad panel and a normal pane lare very similar. Further, sound transmission through a double-leaf partition based on a honeycomb panel with periodic stiffeners is investigated. The structural response of the periodic structure due to a harmonic excitation is expressed in terms of a series of space harmonics and virtual work theory is applied to calculate the sound transmission. The original model is refined to include sound absorption in the cavity and to account for the orthotropic property of the honeycomb panels. Since the solution of the space harmonic analysis is obtained in a series form, a sufficient number of terms has to be included in the calculation to ensure small errors. Computational accuracy needs to be balanced with computational cost as calculation times increases with the number of terms. A new criterion is introduced which reduces the computational time by up to a factor ten for the panels studied. For all the double-leaf systems analysed, the sound transmission loss predictions from the periodic model with the space harmonic expansion method are shown to compare well with laboratory measurements.QC 20120607
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WINTZELL, LOUISE. "Acoustic Textiles : the case of wall panels in home environment." Thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-17698.
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Abstract Noise has become an increasing public health problem and has become serious environment pollution in our daily life. This indicates that it is in time to control and reduce noise from traffic and installations in homes and houses. Today a plethora of products are available for business, but none for the private market. The project describes a start up of development of a sound absorbing wall panel for the private market. It will examine whether it is possible to make a wall panel that can lower the sound pressure level with 3 dB, or reach 0.3 s in reverberation time, in a normally furnished bedroom and still follow the demands of price and environmental awareness. To start the project a limitation was made to use the textiles available per meter within the range of IKEA. The test were made according to applicable standards and calculation of reverberation time and sound pressure level using Sabine’s formula and a formula for sound pressure equals sound effect. During the project, tests were made whether it was possible to achieve a sound classification C on a A-E grade scale according to ISO 11654, where A is the best, with only textiles or if a classic sound absorbing mineral wool had to be used. To reach a sound classification C, a weighted sound absorption coefficient (αw) of 0.6 as a minimum must be reached. The project resulted in that it is technical possible to achieve a sound classification C with only textiles even though for this project another combination was chosen for proceeding with the calculations, because of account to price and environmental awareness. The calculations showed that it is possible to lower the reverberation time to 0.3 s in a normally furnished bedroom with 7 wall panels, and to achieve a lowering of the sound pressure level with 3dB with 7 wall panels. This project showed promising results and leave openings for further research with only textiles and further calculations where more factors are taken under consideration to get more precise and reliable results.Program: Textilingenjörsutbildningen
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Moosavi, Mehr Ehsan. "Sound transmission characteristics of sandwich panels with a truss lattice core." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/56785.
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Sandwich panels are extensively used in constructional, naval and aerospace structures due to their high stiffness and strength-to-weight ratios. In contrast, sound transmission properties of sandwich panels are adversely influenced by their low effective mass. Phase velocity matching of structural waves propagating within the panel and the incident pressure waves from the surrounding fluid medium lead to coincidence effects (often within the audible range) resulting in reduced impedance and high sound transmission. Truss-like lattice cores with porous microarchitecture and \emph{reduced} inter panel connectivity relative to honeycomb cores promise the potential to satisfy the conflicting structural and vibroacoustic response requirements. This study combines Bloch-wave analysis and the Finite Element Method (FEM) to understand wave propagation and hence sound transmission in sandwich panels with a truss lattice core. Three dimensional coupled fluid-structure finite element simulations are conducted to compare the performance of a representative set of lattice core topologies. Potential advantages of sandwich structures with a lattice core over the traditional shear wall panel designs are identified. The significance of partial band gaps is evident in the sound transmission loss characteristics of the panels studied. This work demonstrates that, even without optimization, significant enhancements in STL performance can be achieved in truss lattice core sandwich panels compared to a traditional sandwich panel employing a honeycomb core under constant mass constraint.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Anders, William S. "Structural acoustic analysis of shape memory alloy hybrid composite panels." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-11012008-063243/.
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Ramanathan, Sathish Kumar. "The effects of damping treatment on the sound transmission loss of honeycomb panels." Licentiate thesis, KTH, MWL Structural and vibroacoustics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12514.
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In the industry, all passenger vehicles are treated with damping materials to reduce structure-borne sound. Though these damping materials are effective to attenuate structure-borne sound, they have little or no effect on the air-borne sound transmission.The lack of effective predictive methods for assessing the acoustic effects due to added damping on complex industrial structures leads to excessive use of damping materials.Examples are found in the railway industry where sometimes the damping material applied per carriage is more than one ton. The objective of this thesis is to provide a better understanding of the application of these damping materials in particular when applied to lightweight sandwich panels.
As product development is carried out in a fast pace today, there is a strong need for validated prediction tools to assist in the design process. Sound transmission loss of sandwich plates with isotropic core materials can be accurately predicted by calculating the wave propagation in the structure. A modified wave propagation approach is used to predict the sound transmission loss of sandwich panels with honeycomb cores. The honeycomb panels are treated as being orthotropic and the wave numbers are calculated for the two principle directions. The orthotropic panel theory is used to predict the sound transmission loss of panels. Visco-elastic damping with a constraining layer is applied to these structures and the effect of these damping treatment on the sound transmission loss is studied. Measurements are performed to validate these predictions.
Sound radiated from vibrating structures is of great practical importance.The radiation loss factor represents damping associated with the radiation of sound as a result of the vibrating structure and can be a significant contribution for structures around the critical frequency and for composite structures that are very lightly damped. The influence of the radiation loss factor on the sound reduction index of such structures is also studied.
QC 20100519
ECO2-Multifunctional body Panels
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Burgemeister, Kym A. "Novel methods of transduction for active control of harmonic sound radiated by vibrating surfaces." Title page, contents and abstract only, 1996. http://hdl.handle.net/2440/37932.
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Large electric transformers such as those used in high voltage substations radiate an annoying low frequency hum into nearby communities. Attempts have been made to actively control the noise by placing a large number of loudspeakers as control sources around noisy transformers to cancel the hum. These cancellation systems require a large number of loudspeakers to be successful due to the imposing size of the transformer structures. Thus such systems are very expensive if global noise reduction is to be achieved. The aim of this thesis is to investigate theoretically and experimentally the use of thin perforated panels closely placed to a heavy structure to reduce the radiation of unwanted harmonic noise. These panels can themselves be vibrated to form a control source radiating over a large surface surrounding the primary source. The problem of the equipment overheating inside the enclosure is alleviated because the holes in the panels still allow natural cooling. An initial study is carried out to determine the resonance frequencies of perforated panels. The use of previously determined effective elastic properties of the panels and Finite Element Analysis to theoretically calculate their resonance frequencies is examined. Secondly the attenuation provided by active noise control using perforated panels as control sources is explored by use of a coupled analysis, where the primary source is assumed to influence the radiation of the perforated control panel. This analysis was found to predict poorly the amount of attenuation that could be achieved, so an uncoupled analysis is undertaken, where both the primary and control sources are assumed to radiate independently of each other. Not only does this greatly simplify the theoretical analysis but it also enables prediction of attenuation levels which are comparable to those determined experimentally. The theoretical model is reformulated to enable comparison of the sound power attenuation provided by perforated panel control sources with that of traditional acoustic and structural control sources. Finally, the use of modal filtering of traditional acoustic error sensor signals to give transformed mode (or power mode) sensors is examined. The independently radiating acoustic transformed modes of the panel are determined by an eigenanalysis and a theoretical analysis is presented for a farfield acoustic power sensor system to provide a direct measurement of the total radiated acoustic power. The frequency dependence of the sensor system, and the amount of global sound power attenuation that can be achieved is examined. Experimental measurements are made to verify the theoretical model and show that a sound power sensor implemented with acoustic sensors can be used in a practical active noise control system to increase the amount of attenuation that can be achieved. Alternatively the sound power sensor can be used to reduce the number of error channels required by a control system to obtain a given level of attenuation when compared to traditional error criteria. The power mode sensor analysis is then applied to the perforated panel control system, with similar results.Thesis (Ph.D.)--Engineering (Department of Mechanical Engineering), 1996.
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Odabas, Erinc. "Predictions On Absorption And Scattering Characteristics Of Acoustic Scatterers Modified With Micro-perforated Panels." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614938/index.pdf.
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In this study, the basic absorption and scattering characteristics of acoustic scatterers, specifically Schroeder Diffusers, are investigated. Schroeder Diffusers are one of the most widely used acoustic scatterers in which the scattering phenomenon is predictable due to the geometry of the diffuser, based on a particular mathematical sequence. It is shown that it is possible to increase the amount of absorption by modifying the diffuser structure by means of adding perforated panels into the wells or narrowing diffuser wells. In room acoustics applications, diffusers are conventionally mounted to a wall or ceiling assumed to be rigid enough such that sound wave cannot penetrate through. This thesis proposes a new modification on these diffusers where the diffuser is not backed by a rigid surfaceit is hung over a space instead. To construct such a configuration, diffuser wells are terminated with micro-perforated panels (MPP). Inclusion of MPP introduces additional losses
hence, higher absorption can be achieved. However, the most significant absorption in this configuration is achieved below the first resonance frequency of the panel-air space system due to the existence of non-rigid backing. This thesis aims to model the absorption and scattering mechanisms enabled with the non-rigid backing by improving a previously introduced mathematical model.
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Wennhage, Per. "Structural-Acoustic Optimization of Sandwich Panels." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3161.
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Logawa, Banda. "Improving the sound absorption of cross-laminated timber panels using resonant absorbent layer." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61947.
Full textAbstract:
Developed in the mid-1990s in Austria and Germany, Cross Laminated Timber (CLT) is an innovative wood product known for its strength in both orthogonal directions, and its dimensional stability, making it a sustainable alternative to concrete slabs. CLT is created through the cross-lamination process, which glues together odd number of layers of wood planks placed in orthogonally alternating directions.
With the growing interest in the application of CLT in North America, numerous studies has been conducted to characterize the acoustical properties of CLT panels. However, most of them focused on the sound-transmission aspect of CLT, very few on the sound absorption. This thesis will explore the sound-absorption characteristics of CLT, the effect on overall room-acoustical conditions, the utilization of resonant sound-absorbing layers on CLT to make it more sound-absorptive, and proposed solutions to improve this performance aspect.
To demonstrate the low sound absorption and poor acoustical conditions in rooms with exposed and untreated CLT panels, several in-situ reverberation-time (RT) measurements were conducted in multiple buildings in British Columbia. Average sound-absorption coefficients and estimated Speech Intelligibility Indices (SII) were calculated as baseline performance measures for this study. Based on the results from five different buildings, involving 8 rooms configurations, average sound-absorption coefficients for exposed CLT panels are approximately between 0.02 to 0.13, resulting in barely acceptable conditions for verbal communication.
To optimize the sound-absorption characteristics of prototype CLT panels, a transfer-matrix model has been developed to predict the performance of multi-layered CLT panels. This theoretical model was then validated by using three different sound-absorption measurement methods (impedance tube, spherical decoupling, and reverberation chamber) for multiple HR array configurations.
After identifying the important parameters of an HR system and their effects on performance, a final prototype configuration with Helmholtz Resonator Array was then created with the goal of improving the room- acoustical performance of CLT, as well as responding to input from the CLT manufacturers and experts. Both the theoretical and experimental results confirmed that the proposed solution has the required sound-absorption performance and achieves all research objectives.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Kumar, Gaurav. "Structual-acoustic properties of automotive panels with shell elements." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/13950.
Full textAbstract:
The automotive industry has witnessed a trend in the recent years of reducing the bulk weight of the vehicle in order to achieve improved ride dynamics and economical fuel consumption. Unfortunately, reducing the bulk weight often compromises the noise, vibra- tion, and harshness (NVH) characteristics of the vehicle. In general, the automotive body panels are made out of thin sheet metals (steel and aluminium) that have a very low bend- ing stiffness. Hence, it becomes important to find countermeasures that will increase the structural stiffness of these thin body panels without affecting their bulk weight. One such countermeasure is to introduce the geometrical indentations on various body panels. The geometrical indentation explained in this thesis is in the shape of elliptical dome, which supports the increase of the structural stiffness whilst keeping the bulk weight constant. The primary reason to choose elliptical domes as the applied geometrical indentation is due to a significant amount of interest shown by Jaguar Land Rover. Moreover, the elliptical domes, because of the nature of its design, can cover a larger surface area with minimal depth, thereby, eliminating the possibility of sharp and pointy indentations. This thesis presents a comprehensive study of the structural-acoustic behaviour of the automotive-type panels with dome-shaped indentations. The ultimate aim of this research is to establish a set of design guidelines in order to produce automotive-type panels with optimised dome-shaped indentations. In order to do so, a new design optimisation strategy is proposed that results in the optimal placement of the required dome-shaped indenta- tions. The optimisation problem addressed in this thesis is unlike a general mathematical problem, and requires specific methodologies for its solution. Therefore, the use of genetic algorithm is observed as the most suitable method in order to tackle this type of design optimisation problem. During the development of the optimisation procedure, the preliminary results show a consistency in the design patterns. This led to the motivation to investigate a few intuitively designed panels, which are inspired by the initial, trial, optimisation results. Therefore, four intuitively designed panels are investigated for their structural-acoustic characteristics. The study of the intuitively designed panels provided essential physical insight into the design optimisation problem, which ultimately defined the guidelines in order to develop the proposed optimisation procedure. This type of optimisation procedure is completely new in the domain of structural-acoustic optimisation. The efficiency of the underlying work lies in the separate investigation of both the structural and the acoustic properties of the panels with various dome-shaped indentations, and then utilising the insights gained in order to develop a specific optimisation algorithm to stream-line the dome-shaped panel design procedure.
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Zhou, Jie. "Sound transmission through panels and shells filled with porous material in the presence of external flow." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/366536/.
Full textAbstract:
With increasingly tighter regulations on noise exposure during flight, aircraft designers have been compelled to innovate structures that minimise noise transmission into the cabin space. Porous material is widely used as a passive noise control medium because of their light weight, low cost, and broad band sound abatement effectiveness. The present work, inspired by the need to be able to predict noise transmission characteristics for commonly used constructions, incorporates the effect of flow into the calculations. Three types of sandwich configurations {bonded-bonded, bonded-unbonded and unbonded-unbonded{ are considered. Biot's theory is used to simulate the poroelastic material. The sound transmission though a double-walled panel lined with porous material in the presence of external mean flow is considered, first. The transmission loss is found to increase with increasing Mach number of the external mean flow. This is then explained on the basis that external mean flow increases the impedance of the panel. Mismatch in the characteristic acoustic impedances of the exterior and the interior results in the change of transmission loss. Transmission loss increases gradually when the pressure difference between air gap and that in the exterior decreases. A bi-objective optimization study is carried out to simultaneously minimize the sound transmission and the structural weight. The effect of laminated composite face plate in the structure is also brought out. Sound transmission through a system of double shells, lined with poroelastic material in the presence of external mean flow, is studied next. The transmission characteristics of the sandwich construction are presented for different incidence angles and Mach numbers over a wide frequency range. It is noted that the transmission loss exhibits three dips on the frequency axis as opposed to flat panels where there are only two such frequencies. Results are discussed in the light of these observations. Flow is shown to decrease the transmission loss below the ring frequency, but to increase this above the ring frequency due to the reduction of stiffness and the damping effect added by the flow. Finally, sound transmission through double-walled cylindrical shell lined with poroelastic material in the core excited by the exterior pressure fluctuation due to the turbulent boundary layer is investigated. The peaks of power spectral density of the inner shell kinetic energy due to shell resonance, hydrodynamic coincidence and acoustic coincidence are discussed. The results show that if the high frequency is interested, an air gap, even if very thin, between the two face shells provide superior sound insulation.
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Fiorentino, Pavel. "With everyone’s imagination atrophied, no one will ever be a threat to the world : Work in progress. An essay by Pavel Fiorentino." Thesis, Konstfack, Institutionen för Konst (K), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:konstfack:diva-3604.
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Kurtoglu, Ilker. "Acoustically Induced Stress Analysis Of Center Fuselage Skin Panels Of A Basic Training Aircraft Using Statistical Energy Analysis." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610698/index.pdf.
Full textAbstract:
Two sample statistical energy analysis (SEA) models are generated for a section of the fuselage panel of an aircraft, namely the uniform panel model which includes the frames and stringers, and the ribbed panel model in which the frames and stringers are smeared into the skin. Turbulent boundary layer (TBL) excitation is used as the primary acoustic excitation source. Stress levels are estimated from the average velocity data of the panels. The stress results are found comply with those obtained by the AGARD method. Effect of radiation from panels to exterior and interior of the sample skin panel as well as the pressurization of the skin panels are investigated separately to analyze their effects on the stress levels. The method is then used in the analysis of center fuselage skin panels on a basic training aircraft. Two models are generated for the aircraft analysis, namely the complete aircraft model and the simplified model which excludes the wings and the empennage. In addition to TBL, propeller noise is used as the primary acoustic excitation source. The effects of the wings and the empennage on the stress levels in the center fuselage skin panels are also investigated along with the radiation from panels to the exterior and interior of the aircraft and pressurization of the pilot cabin.
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Zergoune, Zakaria. "Meso-macro approach for modeling the acoustic transmission through sandwich panels." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC048/document.
Full textAbstract:
La modélisation du comportement vibroacoustique en flexion des structures sandwich est devenue aujourd’hui de plus en plus d’un grand intérêt dans les différents secteurs industriels. Cette tendance est principalement due aux propriétés mécaniques avantageuses des structures sandwich. L’un des principaux avantages de ce type de structures réside principalement dans le rapport rigidité-poids élevé. En revanche, acoustiquement la diminution de la masse du panneau avec une rigidité élevée conduit à un confort acoustique insatisfait. Pour cette raison, il y a une demande croissante pour des approches de modélisation du comportement vibroacoustique des structures sandwich avec une précision maximale. La présente thèse propose une approche méso-macro basée sur une méthode numérique pour la prédiction des caractéristiques dynamiques des structures sandwich. La méthode est principalement utilisée pour résoudre le problème de transparence acoustique considéré dans ce projet de thèse. Le travail présenté porte principalement sur la topologie du coeur du sandwich pour traiter le problème abordé. Le principal avantage du modèle proposé réside dans les effets du cœur prises en compte telle que l’effet du cisaillement et celle de l’orthotropie du panneau sandwich. L’approche de modélisation proposée est basée sur la méthode des éléments finis ondulatoire, qui combine la méthode des éléments finis classique et la théorie des structures périodiques. La structure sandwich a été modélisée comme un guide des ondes tridimensionnelles qui garde absolument les informations à l’échelle mésoscopique du panneau modélisé. La fréquence de transition définie la fréquence à laquelle le cisaillement du coeur devient important. Cette fréquence spéciale a été identifié via deux méthodes numériques. Une expression de transmission acoustique à travers un panneau sandwich a également été dérivée. Ensuite, une étude paramétrique a été menée dans le but de révéler l’effet des différents paramètres géométriques sur les indicateurs vibroacoustiquesPrediction of the flexural vibroacoustic behavior of honeycomb sandwich structures in the low-mid frequency is nowadays becoming of high interest in different industrial sectors. This trend is mainly owing to the advantageous mechanical properties of the sandwich structures. One of the main advantages of this kind of structures lies principally in the high stiffness-to-weight ratio. Even though, acoustically the decrease of the panel mass with a high stiffness leads to an unsuitable acoustic comfort. For this reason, there is an increasing demand for approaches modeling the vibroacoustic behavior of the sandwich structures with a maximum accuracy. The present thesis deals with a meso-macro approach based on a numerical method for modeling the vibroacoustic behavior of sandwich structures. The modeling description is mainly used to address the acoustic insulation problem considered in the thesis. The presented work focuses on the topology of the sandwich core to treat the addressed problem. The main advantage of the proposed model is that it takes into account the core shear and panel orthotropic effects. The modeling approach suggested here is based on the wave finite element method (WFE method), which combines the standard finite element method and the periodic structure theory. The sandwich structure has been modeled as a tridimensional waveguide which holds absolutely the meso-scale information of the modeled panel. The transition frequency, which indicates the frequency at which the core shear becomes important, was identified via two different numerical methods. An expression of the acoustic transmission for an equivalent isotropic sandwich panel was also derived. A parametric study was then conducted with a goal of revealing the effect of the geometric parameters of the sandwich core on the vibroacoustic indicators
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Trojáková, Michaela. "Penzion Pamferova Huť." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372261.
Full textAbstract:
This diploma thesis describes the design and processing of project documentation pension. The proposed facility is located in the village of Železná Ruda- Pamferova Hut. The site is widely used by tourists in winter and summer. This is partly basement building, which has 2 storeys and an attic. The roof is designed as a gabled dormer with a flat roof. The building is based on the footings of plain concrete and under the reinforced concrete pillars are designed shoe. Supporting, peripheral and partition walls are designed from sand-lime bricks SENDWIX. An exception is peripheral walls of the basement, which is in contact with soil, which is designed as a lost formwork. In the dining area, which has an open reinforced concrete columns. Ceiling structure will consist of prestressed ceiling panels SPIROLL. Perimeter walls are insulated using external thermal insulation composite system using insulation from stone wool. The building is functionally divided into three main parts with a common main entrance. The first part is a restaurant with a kitchen, storage and kitchen facilities. This section is designed restaurants with a total capacity of 26 persons, the capacity will be in the summer to expand the possible capacity of the terrace, which belongs to the dining room. It is also proposed sanitary facilities for visitors to the restaurant, kitchen with storage and facilities for staff. The second part is the wellness center, which consists of a gym and rooms with infrared sauna and whirlpool. This section is designed sanitary facilities for visitors separated for men and women. The last part of the pension, which used to accommodate 30 people and the background of the pension. Backgrounds pension means any technical equipment room, storage room for bikes and skis, and not least the individual room house, which also includes a room for personal hygiene. This thesis was created with an emphasis on a correct layout and architectural design, static requirements an
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Silva, Edison Delmiro. "O papel narrativo da canção nos filmes brasileiros a partir da Retomada." Pontifícia Universidade Católica de São Paulo, 2008. https://tede2.pucsp.br/handle/handle/5055.
Full textAbstract:
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Previous issue date: 2008-05-12From the analysis of sixty-two Brazilian movies released since 1995, the thesis presents a categorization of the narrative role of popular songs in these productions. The films of this period called "Retomada (National Cinema Resume) show the use of this specific musical form for the construction of meanings in scenes and, ultimately, for the making of allegories that form a contemporary cultural identity and renew the concept of nationality represented in cinema. The study applies the analytical paradigms of the audiovisual soundtrack to the context of the song, categorizes its functions narratives with examples taken from Brazilian movies and observes the historical periods where the song was highlighted in Brazilian films, from the silent movies to the latest musical films
A partir da análise de sessenta e dois filmes brasileiros lançados a partir de 1995, a tese apresenta uma categorização do papel narrativo das canções populares nestas produções. A filmografia deste período denominado Retomada do Cinema Nacional apresenta o uso desta forma musical específica para a construção dos significados nas cenas e, em última instância, para a constituição de alegorias que formam uma identidade cultural contemporânea e renovam a noção de nacionalidade representada no cinema. O estudo aplica os paradigmas analíticos da trilha sonora audiovisual no contexto da canção, categoriza as suas funções narrativas com exemplos extraídos de filmes nacionais e observa os períodos históricos onde a canção teve maior destaque nos filmes brasileiros, do cinema mudo até as produções musicais mais recentes
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Espinoza, Infantes Raphael Marcos, and Condor Juan Alonso Sotomayor. "Estudio y diseño para el reacondicionamiento de áreas hospitalarias de Lima para cumplir los estándares de calidad ambiental de ruido utilizando un software de modelamiento acústico." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2021. http://hdl.handle.net/10757/656497.
Full textAbstract:
El presente trabajo de investigación tuvo como objetivo principal el estudio de los niveles de ruido dentro de los hospitales, específicamente en las áreas de recuperación del Hospital del Niño, así como una propuesta para la reducción de los niveles de ruido. La medición de los niveles de ruido se efectuó en los corredores aledaños a los ambientes de recuperación, estas mediciones se realizaron con un sonómetro calibrado adecuadamente. De esta forma fue posible la determinación de los niveles de ruido máximo y su distribución en el horario diurno. La determinación de los niveles de ruido dentro de los ambientes de recuperación no fue posible, pues estos se encontraban en uso, durante el desarrollo del trabajo de investigación; sin embargo, se determinó la distribución espacial de los niveles de ruido mediante el modelamiento de la presión sonora, usando el software SoundPLAN. Finalmente, se propuso la colocación de paneles de corcho de e=20 mm, como una técnica que permita la reducción de los niveles de ruido dentro los ambientes de recuperación. Los resultados de las mediciones mostraron que los niveles de ruido pueden alcanzar los 79.4 dBA, en los corredores aledaños a las áreas de recuperación, mientras que los niveles de ruido alcanzaron los 55 dBA, dentro de los mismos, además, el uso de paneles de corcho permitió la reducción del ruido hasta en un 21%.El presente trabajo de investigación tuvo como objetivo principal el estudio de los niveles de ruido dentro de los hospitales, específicamente en las áreas de recuperación del Hospital del Niño, así como una propuesta para la reducción de los niveles de ruido. La medición de los niveles de ruido se efectuó en los corredores aledaños a los ambientes de recuperación, estas mediciones se realizaron con un sonómetro calibrado adecuadamente. De esta forma fue posible la determinación de los niveles de ruido máximo y su distribución en el horario diurno. La determinación de los niveles de ruido dentro de los ambientes de recuperación no fue posible, pues estos se encontraban en uso, durante el desarrollo del trabajo de investigación; sin embargo, se determinó la distribución espacial de los niveles de ruido mediante el modelamiento de la presión sonora, usando el software SoundPLAN. Finalmente, se propuso la colocación de paneles de corcho de e=20 mm, como una técnica que permita la reducción de los niveles de ruido dentro los ambientes de recuperación. Los resultados de las mediciones mostraron que los niveles de ruido pueden alcanzar los 79.4 dBA, en los corredores aledaños a las áreas de recuperación, mientras que los niveles de ruido alcanzaron los 55 dBA, dentro de los mismos, además, el uso de paneles de corcho permitió la reducción del ruido hasta en un 21%.
Tesis
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Svoboda, Jan. "Sportovní centrum Polička." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240241.
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This thesis deals with the design and elaboration process of a project documentation of a sports centre. The designed sports centre building is situated in the southern part of the town of Polička, in the area determined for sports and free time activities complexes and areas. It is a two-floor, non-cellar, flat-roof building. It is based on plain concrete strip foundations and reinforced concrete foundation footing. The bearing, peripheral and partition walls are designed from POROTHERM hollow clay blocks. Reinforced concrete columns are designated in open disposition areas. The ceiling construction is made from SPIROLL pre-stressed concrete floor slabs and point-supported reinforced concrete slabs. The peripheral walls of the first aboveground floor are insulated with external thermal insulation system with a protective gabion facade. The peripheral wall thermal insulation in a bowling restaurant and gym halls extension is designed from a ventilated facade with CEMBRIT METRO facade cladding panels. The building is functionally divided into two main parts with a shared entrance. The sports centre with gyms and other sports facilities form the first part. Three squash courts, a mini-football piste, a special room for spinning and alpinning, a room for group exercising and cloakrooms with sanitary facilities are designed within one part of the sports centre. A restaurant with a bowling area and a kitchen with storerooms and other facilities for employees form the second part. The designed complex is barrier-free. There is aimed to be a car park for fifty cars, four motorbikes and a bus in front of the building. Three parking places are for disabled people.
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Li, Yuan-Wei, and 李芫維. "Sound insulation performance of double-leaf panel." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/gh6hme.
Full textAbstract:
碩士國立臺灣大學
工程科學及海洋工程學研究所
107
The purpose of this research is to discuss the sound insulation of double-leaf panel. In the actual production of panels and experimental measurements, the middle part of the double-leaf panel needs to be connected by studs. Then the way of connection divided of points and line. The sound insulation quantity of different connection methods is not the same. In this thesis, we use the governing equation to simulate the sound insulation performance of double-leaf panel, while the middle structure is simulated by springs. With the difference of the incident frequency, the stiffness of the spring is also different. Based on the literature proposed to distribution of spring stiffness values, into the theoretical calculation to simulate the sound insulation performance of double-leaf panel. To order to verify the present method, citing data measured by NRCC. The comparison of the transmission loss between experimental data and numerical predictions is reliable. Using the present method, several cases are set up to investigate related parameters of double-leaf panel, such as thickness, density, stud spacing, distance between two panels and add some porous between two panels. The numerical results show that the coincident frequency will change with different thickness of the panel. Finally, theoretical analysis show that add porous to the structure can increase the sound insulation by about 5 dB.
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Chen, Yan-Bo, and 陳彥伯. "The Research on Suspended Sound Absorber Panel." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/58472606507336568963.
Full textAbstract:
碩士國立成功大學
建築學系碩博士班
93
This study discusses important factors affecting the sound absorption of suspended sound absorber panels; It is measured from the acoustics laboratory by different kind of materials , size , the width between absorber panels，and distance between absorbers and reflecting surface. The conclusions are as followed: 1. Sound absorber panels backing with complex sound absorptive materials have higher sound absorption coefficients than those backing without sound absorptive materials 2. For the same volume of material，To make it into big sound absorber panels will get better absorption coefficients at frequency of 1000Hz below，to make it into small sound absorber panels will get better absorption coefficients at frequency of 1000Hz over. 3. To increase the distance between absorber panels causes increasing result of sound absorption per absorber. When the distance between two absorber is equal or over 3 times of the depth of panel, the sound absorption of each absorber is getting constant. 4. When the frequency goes over 1000Hz，the sound absorption goes greater by increasing the distance between absorbers and reflecting surface. In addition, the more the distance becomes ,the lesser the effect of functional sound absorber goes, when the distance more than 30cm the effect is negligible。 5. The sound absorber panels absorption coefficients are concluded as following formula: log(NRC)= -1.6866+1.2743T+0.0196H+5.6325(W)-1–0.3175(H/W) + 0.1197C NRC: Noise Reduction Coefficient T: material parameter H: the depth of panel W: the distance between absorber panels C: structure parameter
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Su, Chen-Lung, and 蘇鎮隆. "SPL Spectrum Smoothing of Laminated Composite Panel Sound Radiator." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/d257c4.
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碩士國立交通大學
機械工程系所
92
This thesis is focused on the vibration characteristics and the performance of sound pressure level(SPL) of laminated composite panels. The main purpose is to smooth SPL curves using the different material compositions and boundary conditions. The finite element code ANSYS is used to determine the vibration responses of the plates. The sound pressure generated by the plate is computed using the first Rayleigh integral. Experiments are performed to measure the sound pressure generated by a number of plates. Comparing experiment results with theoretical preditions , we study how SPL curves vary. Then we can find out the influence of each design parameter on sound pressure responses of loudspeakers. By summarizing the results , we can improve the design of the radiating panel. PC plastics and carbon composites are used to construct the transparent radiating panels supported by elastic suspensions and composite beams. The radiating panels together with actuators , suspensions , composite beams and panels are used to make speakers which are then tested to study the sound pressure responses of the speakers. After verifying the theoretical analysis by comparing with experiment results , we further use the finite element method to simulate SPL curves of the speakers. Observing the vibrating shapes , we can find out which factor causes the SPL curves to have pits and peaks . Based on this , we can design the structures and improve the performance of their sound pressure responses.
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Wu, Ming-Han, and 吳明翰. "A Study of Sound Absorption Characteristics on Perforated Steel Panel." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/09988867945274176274.
Full textAbstract:
碩士國立成功大學
建築學系碩博士班
91
Perforated steel panels are widely used as sound absorption materials in architectural field. However, the setup always follows the overseas information and lacks experiments and tests on the sound absorption characteristics of perforated steel panels. It shows that in our country, not only the requests of sound absorption ability but also the related information of perforated steel panels are unavailable. This research discusses all factors affecting the sound absorption characteristics of perforated steel panels, including perforation, backing materials, and air space. This research aims to figure out the suitable prediction formula for resonant frequencies of perforated steel panels, and to collect the statistics and data as well. There are some conclusions as follow: 1.For the same thickness and perforation, the difference of sound absorption coefficients between perforated steel panels and perforated aluminum panels is below 0.04. With steel or aluminum panels, the changes of metal materials show no obvious effect to sound absorption coefficients. 2.With the same material, panels with perforation have different curves from those with no perforation. None-perforated panels present sound absorption characteristics of panel vibration, while perforated panels present resonant sound characteristics. 3.With fixed air space and backing materials, the more the perforation is (from 8.7% to 17.5%), the higher the resonant frequency goes. All the differences of sound absorption coefficients are below 0.15, which are not quite big. 4.The larger the air space is, the higher the sound absorption coefficients are, and the lower the resonant frequency would be. It shows that the air space would increase low frequency sound absorption. 5.The average sound absorption coefficients of perforated steel panels backing with sound absorptive material are greater than those backing with no sound absorptive materials by 0.12 at least, and 0.75 at most. It shows that in addition to setting air space, perforated steel panels would gain better sound absorption characteristics when backing with sound absorptive materials. 6.Perforated steel panels backing with complex sound absorptive materials have higher sound absorption coefficients than those backing with single sound absorptive materials.
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Pan, Zheng-Jia Ivan, and 潘政佳. "Active Structural Acoustic Control of Sound Transmission Through a Panel." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/94360895821951222625.
Full textAbstract:
碩士國立成功大學
造船及船舶機械工程學系
89
In this paper, the ASAC technique for controlling noise transmission into an anechoic room using piezoelectric actuator on an elastic plate is discussed. The adaptive LMS algorithm was implemented on a TMS320C32 digital signal processing board to achieve control experiments. In addition, experimental simulations were achieved by the adaptive LMS and the filtered-X version of the adaptive LMS algorithms. Experiments were conducted to measure farfield sound radiation from a 33.0cm*33.0cm*0.1cm baffled panel on the window of an anechoic room subjected to acoustic excitation, with and without active control conditions. The active control of the transmission loss of the panel was achieved by one piezoelectric actuator mounted on the panel. Sound pressure radiated from the panel was measured to estimate the reduction of transmission loss of the panel due to ASAC. Theoretical simulation and Experimental results showed that sound radiation from acoustical modes at low frequencies is reduced.
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Wen-ChingTai and 戴彣勍. "Sound-Absorbing Properties by Micro-Perforated Panel for Interior Ceiling." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/30215043317026848339.
Full textAbstract:
碩士國立成功大學
建築學系
103
SUMMARY This study confirms the best specification of hole length, hole width first, hole distance of geometry micro-perforated panel(GMP), and discusses the application of geometry micro-perforated panel in the ceiling type of continuous, discontinuous and acoustic baffle with different factors, such as the form of air layer, air-back cavity style, the layer number of air layer, the arrangement form, and the height. CNS-9056 Acoustics-Measurement of Sound Absorption Coefficients in a Reverberation Room is referred and the methodology of measurement in this study. The results show the geometry micro-perforated panel(GMP) performs the best in hole length of 0.4mm, hole width of 0.04mm and hole distance of 3mm. The NRC and αw are both 0.75 in air-back cavity of 30 cm. The highest peak value of sound absorption coefficient is 0.97 with 200Hz of low frequency. The geometry micro perforated panel(GMP) under the air-back cavity performs best with the single layer of geometry micro-perforated panel(GMP) of 30cm. However, the single layer of geometry micro-perforated panel(GMP) is suggested putting in the indoor ceiling without air-back cavity. Keywords: geometry micro perforated panels, continuous type, discontinuous type, Sound absorber panels; sound absorption coefficient INTRODUCTION The micro perforated panel was developed from the research of general theory and design of micro perforated panel absorbers by Maa, Dah-You in 1996. It generates resonance of sound-absorbing by the structure of stiletto. In practice, it does not need to be added the materials with multiple holes, and is suitable to be using in places with high temperature and humidity because of water-repellent and high temperature resistant characters, such as glass wool, rock wool, etc. (Jiang, Zhon-Gjie, 2007) In the research of geometry micro perforated panel which was published in 2007 by Jiang, Zhon-Gjie. In the process of manufacturing, he punched holes instead of abandoning the vertical piercing way, observing the shape of holes from the side of dissecting and discovered these holes were like geometric shapes which were different from general micro perforated panels with straight shape. Hence, it was named as geometric micro-perforated panel (GMP). Through experimental result, he found that the performance of sound absorption was significantly impacted by changes of piercing rate. Therefore, the piercing rate can be controlled by the hole length, the hole width, and the hole distance indirectly. (Jiang, Zhon-Gjie, 2007). The changes of piercing rate has significant impact to elevate the sound absorption performance of GMP and makes bandwidth of sound absorption wide by comparing with straight micro perforated panels. The overall performance of sound absorption is elevated apparently. When adding geometry GMP to general indoor ceiling, GMPs need close air layers in order to elevate the performance of sound absorption, the ceiling are covered with micro-perforated panels with continuous type. Nevertheless, if the type of air layer is changed from close to open, the sound absorption performance of the GMP may be changed. Materials and Methods This study discusses three types of ceilings which are flat roof (60cm×60cm×2.5cm with basic unit and single layer GMP), discontinuous (60cm×60cm×5cm with basic unit and double layer GMP) and baffle (180cm×20cm×5cm with basic unit and double layer GMP) by using hole length of 0.4 mm, hole width of 0.04mm, and hole distance of 3mm as a standard specification. CNS-9056 acoustics measurement of sound absorption rate in the reverberant chamber is referred to and stereo laboratory of the department of Architecture from National Cheng Kung University is the testing place with floor area of 32.8 m2, volume of 171.6 m³, the testing capacity is 10.8 m2. Results and Discussion 1.Comparison of structure of GMP: Through the comparison of the experimental results, two sound absorption performance of GMP the same which are 0.3-2P and 0.4-3P respectively. P 0.4-3P is chosen to be the standardized specification in the future due to consideration of standardized specification and the yield rate of producing. 2.Continuous type ceiling: A.Thickness of back air layer: The experimental result shows that the bandwidth of sound absorption of 0.4-3p GMP increases and the trend of sound absorption moves from high frequency to low frequency when the thickness of back air layer increases. B.Type of back air layer: The experimental results show that the situation is obvious between low frequency of 100 Hz and high frequency of 630 Hz. The biggest value of difference is over 0.3. There is no significant difference above high frequency of 1000 Hz. C.Comparison of the numbers of layers: When the structure of layer transforms single into double, and the coefficient of sound absorption maintains over 0.8 with the low frequency between 200 Hz and 2000 Hz, those make up the part of declining with high frequency of 1000 Hz of the single layer. The sound absorption performance apparently elevates only when the geometry micro-perforated panel is added to aluminum board, the high frequency is from 200Hz to 2000Hz, and the low frequency is 80 Hz. 3.Discontinuous type ceiling: A.Content of the structure: Double side of GMP is better than single side’s. There is no difference under the low frequency of 200 Hz and significant difference over the low frequency of 200 Hz. The biggest difference of sound absorption coefficient is over 0.25. B.Comparison of Height change: GMP of double side is taking to do change of height. With the change trend of height and the move of low frequency, there is apparently significant difference in the mid-low frequency with the height of 5cm. However, there is no big difference in the high frequency. Moreover, the sound absorption performance is the best with the height of 40 cm. C. Form of arrangement: When the numbers of GMPs is arranged to be unmovable, the result shows there is no significant difference with overall sound absorption performance. The sound absorption performance of arrangement of dot form is different only in mid frequency of 630 Hz and the biggest difference is over 0,05. 4.Sound absorber panels: A.Sound-absorber the structure: Double - sided GMP on each frequency was significantly superior to the one-sided GMP, the most significant differences at high frequencies, sound absorption coefficient difference of 0.3 or more. B.reflecting surface between the distance: GMP done using double-sided reflective surface 0cm snapping back wall and back wall from the highly reflective surface 20cm, found snapping back wall there is a significant difference when 0cm in the low to intermediate frequency 630Hz 200Hz reflective surface, the difference between the highest absorbing coefficient of 0.3 or more. C.Spacing between the sound-absorber panels: Discussion on distance should be controlled when the same amount, when the distance between the absorbing body and absorbing body in 30cm, at intermediate frequency 315Hz to 5000Hz with the distance of 10cm, the most significant difference, the maximum difference of 0.1 or more. Conclusion When decorating ceiling, there is no limit to add GMP. The best performance of GMP is continuous single layer. Performances or material cost are all the most effective. However, if there is limitation with other demands of models or ceiling decoration and no complete air back layers, the GMP of double layer is the best to be the unit of decorating, and then we can do different decoration type of ceiling according to different demand.
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Hu, Wen-Hsin, and 胡文信. "Study on Sound Absorption Characteristics of Multi-Cavity Micro-Perforated Panel." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/fkc88f.
Full textAbstract:
碩士國立臺灣海洋大學
系統工程暨造船學系
106
The theory of Maa’s is based on a perforated plate less than 1 mm. The sound absorption and characteristics of micro-perforated panel are calculated by using the hole diameter, panel thickness, perforation ratio, and thickness of the back cavity. This paper uses finite element method to simulate the micro-perforated panel, In order to improve the application of micro-perforated panel, a single cavity thickness simulation was carried out through establish models with cavity thicknesses of 10 mm, 29 mm, 71 mm, and 154 mm, which were verified with Maa’s theory, and then discussed the sound absorption performance with different cavity angles. And the four cavity thickness of the two-cavity and four-cavity simulation and compare with the Iman Falsafi and Abdolreza Ohadi theory, and then in the end use no partition of the double, four cavity to explore its sound absorption performance. Model establishment is reference ASTM E1050-98 set specifications, after meshing, and then simulated by the finite element software. The micro-perforated panel setup is based on the Maa’s theory to import parameters to calculate the acoustic impedance. For ordinary perforated panel, Lee and Zhan used Mechel function to calculate the acoustic impedance and used the transfer admittance method to calculate the transmission loss of the muffler. This paper used this method to set the acoustic impedance of the micro-perforated panel by the transfer admittance method. Solve the problem of meshing caused by holes in the micro-perforated panel. Finally, use the transfer function to calculate the sound absorption coefficient and compare them. The simulation results show that the use of this method for micro-perforated panel simulation is in good agreement with Maa’s theory, confirming the feasibility of this simulation method. In the cavity simulation with varying angles, the cavity volume is also positively correlated with the sound absorption coefficient, multi-cavity. The simulation is in good agreement with the theory of Iman Falsafi and Abdolreza Ohadi.
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Chiang, Chung-chiech, and 江仲傑. "The study on sound-absorbing properties of oblique micro-perforated panel." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/86120903533513437360.
Full textAbstract:
碩士國立成功大學
建築學系專班
96
According to Dr. Maa’s theory, the sound absorption coefficient of ordinary micro-perforated panel (address as MP)absorber can be predicted with diameter of opening, percentage of perforated area, back air space depth. The oblique micro-perforated panel (address as OMP) is distinct to MP in terms of structure, such as oblique appearance, and open holes are not orthogonal to the panel’s surface. The study explored the differences of sound absorption’s character between MP and OMP, and the effect of structure factors on the sound absorption coefficient of OMP. The conclusion of the study including： 1.OMP structures could be absorbers with good sound absorption’s characters ( the averaging sound absorption coefficients reach 0.5 ) . 2.The averaging sound absorption coefficient of MP structure possessing the same hole area（take small-hole side area for OMP）, percentage of perforated area, depth of back opening and air space as OMP structures , is greater than MP structures taking large-hole side area and hole area situated at the center of depth for OMP, and the difference between that and OMP structure is little than differences as MP structures taking the other two hole areas. 3.The sound absorption coefficients of OMP structure at 3150Hz and 4000Hz are greater than that of MP structures possessing the same structures. 4.In the range of sample structures the research adopted, reducing percentage of perforated area, or increasing any of hole depth, hole section slope, small-hole side area, back air space depth, will observably raise the averaging sound absorption coefficients of OMP. Reducing large-hole side area or hole appearance-index, small-hole side surface uneven grade, will raise the averaging sound absorption coefficients too, but the inference is not notable. 5.Using sound absorption coefficients of MP as norm of comparison could make the inference of changing small-hole side area or small-hole side appearance-index obvious.
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Li, Wei-Peng, and 黎瑋鵬. "Research of Acoustical Properties for the Suspended Sound Absorber Panel and the Seat Variation Used in Sound Field." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/c6tx9t.
Full textAbstract:
碩士國立臺灣海洋大學
系統工程暨造船學系
102
In nowadays, a variety of different types of room space are more and more with our quality of life enhance, however, there are different room space requiring at different acoustic design. The initial research of this paper is used a room space that before and after acoustic improvement to measure it’s acoustical properties : Reverberation Time (RT), Clarity index (C50&;C80), Articulation Loss of Consonants(Alcons), Rapid Speech Transmission Index(RaSTI). The improvement using absorber material include the suspended sound absorber panel and others, then compare the simulated result using acoustical simulation software EASE with the measured result. In the second part, we used the Kath&;Kuhl method to measure the seat absorption coefficient with different cushion and the other absorber material, and find the suspended sound absorber panel which has the best absorption coefficient used in the room space. Finally, we took the different seat absorption coefficient used in the room space to simulate the acoustical properties, and discuss the accurate of the simulation. The results can be provided to the relate field.
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Jang, Jr-Jie, and 張志傑. "The Study On Sound Radiation Of Composite Flat-panel In Different Enclosures." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/42477778115058904991.
Full textAbstract:
碩士國立交通大學
機械工程系所
96
Two parts are discussed in this thesis. The first part is about the fabrication and analysis of flat-panel loudspeaker. The speaker fabrication includes the design and fabrication of the composite flat-panel, the determination of geometrical shapes of the elastic supports, and the assembling of the parts. In the theoretical study, we discussed the choice of the finite element types, the determination of system parameters, and analysis of the loudspeaker’s sound pressure level (SPL) curve. The second part is to study the sound radiation characteristics of the loudspeaker when it is installed in a closed or semi-hermetic box. There are different designs of the box. We will discuss three kinds of boxes which are commonly used. They are closed-box, the bass reflex box and the passive-radiators box. And then we will investigate experimentally if the box design methods for cone-loudspeaker can be used to design the flat-panel loudspeaker box. We have found the values between the theory and the experiment may be so different that the design methods of cone-loudspeaker box can only be used as a reference. In addition, we also do several different designs to observe the changes of sounds and SPL curve, and try to find the best way to improve them. From our experiment we find that among the different box designs the back oblique passive-radiator box is the most effective one in enhancing bass.
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Huang, Kuo-Fung, and 黃國峯. "The Effects of Different System Parameters on Sound Pressure Curves of Panel-speakers." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/44405539734516694043.
Full textAbstract:
碩士國立交通大學
機械工程學系
101
In this thesis, the effects of several system parameters on the sound pressure level (SPL) curves of panel-speakers made of different materials are studied via both theoretical and experimental approaches. For the panel-speakers, it is not uncommon to have SPL drops termed as sound valleys on the SPL curves, which can affect the sound quality of the speakers. This research offers a way to eliminate the sound valleys by adjusting the system parameters using the finite element model established on the basis of the simulation software “ANSYS”. In the first place, the experimental results are used to prove the correctness of the ANSYS model which can be used for the following investigation. Then we make changes in the system parameters such as plate material, diameter of coil, lamination arrangement of plate, and properties of elastic support to study the effects of the parameters on the SPL curves of the speakers. Finally, the appropriate system parameters are used to fabricate a panel-speaker to demonstrate the practicability of the design.
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Chen, Yin-Ju, and 陳音茹. "Manufacture and Optimal Design of Flat-panel Sound Radiator Subjected to Line Loads." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/34743522034438034120.
Full textAbstract:
碩士國立交通大學
機械工程系所
103
In this thesis, the effects of different material constants on sound pressure level (SPL) are studied. According to the results of the theoretical SPL, the exciter location is the most influential parameter regarding sound pressure level. Consequently, different flat-panel exciter locations are designed to eliminate the SPL dips and enhance high frequency performance via an optimization approach. Both the finite element method and the Rayleigh-Ritz method are used to simulate the frequency responses of flat-panel speakers. The first Rayleigh integral is used to construct the SPL curve of the speaker. The optimal excitation locations of several composite diaphragms with different aspect ratios are determined using a global optimization technique. The results of the optimal designs have shown that diaphragms with similar characteristics have similar excitation locations. The feasibility of the optimal design method has been validated by the experimental results.
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Zhang, Wen-Hao, and 張文豪. "A Study on Sound Absorption Characteristics of Perforated Mong-Zong Bamboo Composite Panel." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/89413887395080151864.
Full textAbstract:
碩士國立中興大學
農村規劃研究所
96
Eco-awareness is growing up in these years around the world, and the perforated bamboo composite panel is a kind of the building materials that green. Because it is beautiful and natural, firm but portable, the prospect of the perforated bamboo composite panel is potentially. This study discusses all factors that can affect the sound absorption characteristics of perforated bamboo composite panel, including the perforation, backing materials, and air space. Besides, in order to upgrading the sense of beauty, and discusses the cover rate of faceplate which on the perforated panel, too. Afterward this study will try to figure out a suitable prediction formula for resonant frequencies of perforated bamboo composite panel to make the designer surveyed the resonant frequencies quickly and simply. There are some conclusions as follow: 1.In the same perforation, backing materials, and air space, the more faceplate covered rate(from 0% to 66%), the lower the resonant frequencies goes, and the vibrat absorption effect of faceplate make the sound absorption coefficient a little promotion. 2.In the same cover rate, backing materials, and air space,the more perforation is(form 7.9% to 14.8%),the higher the resonant frequency goes, and the high frequencies goes up, too. 3.When the perforated bamboo composite panel backing with Malamine foams, the sound absorption coefficient of whole frequencies is greater than the without one, and the resonant frequency goes lower slightly,too. 4.In the same cover rate, perforation, and backing materials, the larger the air space is(from 5cm to 10cm), the lower the resonant frequency goes,but there is no variation in high frequency(over 2000Hz).It showed that make the air space get larger would not weaken the sound absorption coefficient in high frequency, and also make the sound absorption coefficient in low frequency increasingly. This study have also found out a suitable prediction formula for resonant frequencies of perforated bamboo composite panel by multiple regression analysis, too.
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Tewes, Stephan [Verfasser]. "Active trim panel attachments for control of sound transmission through aircraft structures / Stephan Tewes." 2006. http://d-nb.info/985295147/34.
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Fan, Kai-Han, and 范凱涵. "Optimal Design and Manufacturing of Flat - Panel Speakers and Sound Box for LCD TV." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/56106202975217517675.
Full textAbstract:
碩士大葉大學
工業工程與科技管理學系
100
The main purpose of this study is developed new composite materials flat-panel speaker on the mainstream of LCD TV speakers market, the main specifications for the L58×W25×H15 mm and L116×W25×H15 mm of flat-panel speaker. By designing flat-panel of speaker of stiffening composite pattern and transforming coefficient of the spring edge material, made the sound pressure curve to achieve the best smooth, can reproduce the frequency of the signal integrity and get the best sound quality flat-panel speakers, extend high frequency in sound pressure to increase the frequency range, enhance high frequency clarity. The two flat-panel speakers are to combine to form one double flat-panel speaker. This application could be make vocal range more broad. At the same time, closed enclosure and bass-reflex enclosure developed flat-panel speaker sound box enhances sound in the flat-panel speaker of the low frequency, sound pressure curve variance reduced by 14%. This study is used ANSYS finite element analysis software to create speaker models and frequency response analysis with the experimental measurements of sound pressure curves for comparison, verify the accuracy of the model predictions and effective characteristics of flat-panel speaker. Finally, the use the PSO in Fortran software calculate the best LCD TV manufacturing parameters, the L116×W25×H15 mm of the best flat-panel speaker diaphragm manufacturing parameters is pattern 1 and single carbon fiber stiffening, edge material used PU synthetic leather；the L58×W25×H15 mm of the best flat-panel speaker diaphragm manufacturing parameters is pattern 1 and single carbon fiber stiffening, edge material used PET, double flat-panel spacing of 35mm, expect to provide a new LCD TV speaker in the majority consumer market.
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Spiro, Holly Nicole. "An implementation analysis of the Clayoquot Sound scientific panel recommendations on First Nations perspectives." Thesis, 2003. http://hdl.handle.net/2429/14660.
Full textAbstract:
In 1995, the government of British Columbia adopted a set of groundbreaking recommendations for addressing First Nations perspectives in forestry in Clayoquot Sound. The recommendations focus on three themes: First Nations participation in forest management and decision-making, protection of cultural values, and incorporation of traditional ecological knowledge in management. Key informants from implementing agencies and target groups including government, the forest industry, First Nations, and multisectoral planning and co-management bodies were interviewed to determine how effectively these recommendations have been implemented. Outputs of implementing agencies and their perceived impacts by target groups were assessed. Factors that act as challenges or facilitators to implementation are determined, to explain the reasons for the observed degree of implementation success in each theme. Applying a broad, adaptive approach in defining implementation success, it was found that substantial impacts have been realized. Foremost among them are relationship building between previously disparate parties, and cross-cultural learning and exchange. However, it was also found that the observed impacts cannot be attributed solely to the recommendations being studied, as there are many interacting factors.