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1
Chong, Yung Boon. "Sonic crystal noise barriers." Thesis, Open University, 2012. http://oro.open.ac.uk/44502/.
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An alternative road traffic noise barrier using an array of periodically arranged vertical cylinders known as a Sonic Crystal (SC) is investigated. As a result of multiple (Bragg) scattering, SCs exhibit a selective sound attenuation in frequency bands called band gaps or stop bands related to the spacing and size of the cylinders. Theoretical studies using Plane Wave Expansion (PWE), Multiple Scattering Theory (MST) and Finite Element Method (FEM) have enabled study of the performance of SC barriers. Strategies for improving the band gaps by employing the intrinsic acoustic properties of the scatterer are considered. The use of the tube cavity (Helmholtz type) resonances in Split Ring Resonator (SRR) or the breathing mode resonances observed in thin elastic shells is shown to increase Insertion loss (IL) in the low-frequency range below the first Bragg stop band. Subsequently, a novel design of composite scatterer uses these 2 types of cylindrical scatterer in a concentric configuration with multiple symmetrical slits on the outer rigid shell. An array of composite scatterers forms a system of coupled resonators and gives rise to multiple low-frequency resonances. Measurements have been made in an anechoic chamber and also on a full-scale prototypes outdoors under various meteorological conditions. The experimental results are found to confirm the existence of the Bragg band gaps for SC barriers and the predicted significant improvements when locally resonant scatterers are used. The resonant arrays are found to give rise to relatively angle-independent stop bands in a useful range of frequencies. Good agreement between computational modelling and experimental work is obtained. Studies have been made also of the acoustical performances of regular arrays of cylindrical elements, with their axes aligned and parallel to a ground plane including predictions and laboratory experiment.
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Williams, Warwick Hamilton Safety Science Faculty of Science UNSW. "Barriers to occupational noise management." Awarded by:University of New South Wales. Safety Science, 2007. http://handle.unsw.edu.au/1959.4/27368.
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This work undertook the examination of the perceived barriers that exist to the management of occupational noise exposure in the workplace. Exposure to excessive levels of noise results in cumulative damage to the hearing mechanism of the ear and a subsequent hearing loss. This hearing loss is permanent and does not recover over time. Initially the conventional method of addressing or controlling noise exposure was through Hearing Conservation Programs and more recently through Occupational Noise Management Programs that take more of a risk management approach. However, the numbers of new hearing loss claims submitted through the various ???workcover??? and ???worksafe??? authorities in Australia continue to remain very high. Hearing loss claims rank within the top two in number of new claims each year. The research conducted shows that there are four main barriers perceived by individuals that work against the institution of effective preventive action. These four main barriers in order of priority are hearing protectors, information, culture and management, and are themselves each composed of several lesser factors. Each of the barriers was examined more closely in an attempt to better understand how they operate and the potential to discover how they may be overcome. To briefly summarise the main barriers: 1) Hearing protectors are uncomfortable, impede communication and are unpleasant to wear; 2) Individuals would like more information on noise reduction and for this information to be supplied by management; 3) workplace and management culture needs to be supportive of occupational health and safety in general and with the implementation of supportive preventive measures in particular; and 3) management needs to be seen to place importance on occupational health and safety in the workplace in general and the reduction of excessive noise in particular. By being aware of the barriers and operation the design of future more effective intervention or better noise management programs should be possible.
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Engström, Nicklas. "Inclination angle of noise barriers : A study on the effect an inclination angle has on the reflected noise from noise barriers." Thesis, KTH, Farkost och flyg, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-39481.
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The aim of this thesis is to determine the effect an inclination of a noise barrier has on the reflected noise produced by road traffic. The height distribution of the reflected noise is expected to decrease with an increasing angle of inclination. A theoretical study based on mirror sources and trigonometry explains the relation between the barrier inclination and the height of the reflected noise. The theoretical model is complemented with a scale model measurement and a simulation performed in Odeon. Acoustic hard surfaces and totally absorbent surfaces are used during the theoretical model, scale model measurement and the simulation. The results of the scale model measurement and the simulation supports the behavior of the theoretical model and displays an angle of inclination where the behavior is reversed and at which the height of the pressure is increased with further the increase of the inclination angle.
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Chau, Pak-lam. "Evaluation on the effectiveness of noise barriers for road traffic noise mitigation /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20038173.
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Wu, Weixiong. "Impacts of noise barriers on metropolitan communities." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0005/NQ43128.pdf.
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Sohrabi, Shahin. "Active control of noise transmitted from barriers." Doctoral thesis, Universitat Politècnica de Catalunya, 2022. http://hdl.handle.net/10803/674002.
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Active noise cancellation is a unique approach that helps passive noise control in reducing sound levels at low frequencies; nevertheless, successful use of active noise cancellation necessitates performing numerous and tedious experiments together with defining several parameters properly. The locations and quantity of active control system transducers are among these parameters.
The present research provides a comprehensive framework for placing control sources and error microphones near a noise barrier in order to improve its efficiency in both narrowband and broadband noise spectra. To accomplish this, the appropriate locations for the control sources are first determined using a repetitive computation method, and then the optimizations are completed by determining the best position for the error microphone.
Several alternative transducer locations near the barrier are incorporated in the repetitive computation, and the optimal sites for the control sources and error microphones are found using two-step optimization methods as well as the genetic algorithms approach.
The findings reveal that the best places to put the control sources are on the incident side, below the barrier's edge, and the best locations to place the error microphones are on the shadow side, as close as possible to the target area. The effect of ground reflection on the efficiency of the active noise control system is also investigated, and it is discovered that while ground reflection has no significant effect on the performance of the active noise control system for broadband frequency ranges, it does reduce the control system's efficiency at tonal noises.
In order to optimize more parameters, further calculations are performed based on the genetic optimizer. The output of the GA calculations found new configurations for the control units that result in higher noise level reduction at the target area.
In addition to the active noise barrier, the application of active noise cancellation for open windows as a particular case of the barrier is explored as a particular case of the barrier. Different arrangements are studied for the control units close to the open windows, including linear, boundary, and planar control arrangements.
The effect of several parameters such as the incident angle of noise waves, the distance between error microphones and the opening, and the number of control units are investigated. The results demonstrate that the active noise control system with obliqued linear placements of transducers have higher performance than the other arrangements. Furthermore, when the frequency and incident angle increase, the effectiveness of active noise reduction decreases.La cancelación activa de ruido es un enfoque único que ayuda al control pasivo del ruido a reducir los niveles de sonido a bajas frecuencias; sin embargo, el uso exitoso de la cancelación activa de ruido requiere la realización de numerosos y tediosos experimentos junto con la definición adecuada de varios parámetros. La ubicación y la cantidad de transductores del sistema de control activo se encuentran entre estos parámetros. La presente investigación proporciona un marco completo para colocar fuentes de control y micrófonos de error cerca de una barrera de ruido con el fin de mejorar su eficiencia en espectros de ruido de banda estrecha y banda ancha. Para lograr esto, primero se determinan las ubicaciones apropiadas para las fuentes de control usando un método de cálculo repetitivo, y luego se completan las optimizaciones determinando la mejor posición para el micrófono de error. Varias ubicaciones de transductores alternativas cerca de la barrera se incorporan en el cálculo repetitivo, y los sitios óptimos para las fuentes de control y los micrófonos de error se encuentran utilizando métodos de optimización de dos pasos, así como el enfoque de algoritmos genéticos. Los hallazgos revelan que los mejores lugares para colocar las fuentes de control están en el lado del incidente, debajo del borde de la barrera, y los mejores lugares para colocar los micrófonos de error están en el lado de la sombra, lo más cerca posible del área objetivo. También se investiga el efecto de la reflexión del suelo sobre la eficiencia del sistema de control de ruido activo, y se descubre que si bien la reflexión del suelo no tiene un efecto significativo en el rendimiento del sistema de control de ruido activo para rangos de frecuencia de banda ancha, sí reduce el rendimiento del sistema de control. eficiencia en ruidos tonales. Para optimizar más parámetros, se realizan más cálculos basadosen el optimizador genético. El resultado de los cálculos de GA encontró nuevas configuraciones para las unidades de control que dan como resultado una mayor reducción del nivel de ruido en el área objetivo. Además de la barrera de ruido activa, se explora la aplicación de la cancelación de ruido activa para ventanas abiertas como un caso particular de la barrera. Se estudian cuatro disposiciones para las unidades de control cercanas a las ventanas abiertas. Las unidades de control en una configuración de límite se colocan en el borde de la abertura, mientras que en el control plano, se ubican en la superficie de la abertura. En una configuración de contorno, las unidades de control se colocan en el borde de la abertura, mientras que en un diseño plano, se colocan en la superficie de la abertura. Se investiga el efecto de varios parámetros como el ángulo de incidencia de las ondas de ruido, la distancia entre los micrófonos de error y la apertura, y el número de unidades de control. Los resultados demuestran que el sistema de control de ruido activo con configuración plana tiene un rendimiento más alto que el control de límites. Además, cuando la frecuencia y el ángulo de incidencia aumentan, la eficacia de la reducción activa del ruido disminuye.
Enginyeria mecànica, fluïds i aeronàutica
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Chau, Pak-lam, and 周栢林. "Evaluation on the effectiveness of noise barriers for road traffic noise mitigation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31253970.
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Menounou, Pinelopi. "Theoretical study of diffraction by straight and ragged edge noise barriers /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Liu, Yuen-mei, and 廖婉薇. "Feasibility study of green noise barriers in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48543299.
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Hong Kong is a crowded city where pavements, lanes, hawker areas, trunk roads and highway are closely built. With heavy traffic flow on complex road networks, the noise barriers located in the urban centre usually adjacent to commercial centres and residential buildings. The design of noise barriers is therefore needed to be in harmony with the landscape of the neighbourhood. Different kinds of green noise barrier systems combined with soil and vegetation had been developed across Europe and the USA in recent years. It is believed that an effective controller of noise shall be visually attractive especially for residents who are adjacent to the roads. A number of noise barriers with vegetation were successfully implemented in European Countries. Nevertheless, these engineering techniques cannot be fully applied to Hong Kong due to the over-crowded living environment.
A well-designed green noise barrier system is the critical reason for successful application to sustain the vegetation and to insulate and absorb noise. The objective of this study to investigate different kinds of green noise barriers and come up with some guidelines for design consideration in order to optimize the green noise barriers. The study provides a thorough analysis of the available green noise barrier systems across the world, including a look at all the potentials benefits from environmental and socio-economics perspectives.
The pilot field measurement was conducted at Yeung Uk Road where green noise barriers located between a heavily travelled main road and residential area in Tsuen Wan, to measure the SPL and Leq noise levels to assess the effectiveness of the green noise barriers. No significant attenuation effect is observed on the green noise barrier which has to be attributed to the median placement and over-crowded urban environment.
Online questionnaires and interviews are conducted to investigate the effects of vegetation on the perception of green noise barriers. Results show that 78% of the respondents preferred vegetation rather than concrete (0.1%) and other materials. 77% like the aesthetics appearance of vegetation and 86% are willing to bear the cost. In general, 95% of the respondents agreed green noise barriers should be promoted in Hong Kong. The results assured that (1) vegetation on green noise barrier is aesthetically pleasing and mostly preferred; (2) people are willing to pay for green noise barrier for aesthetics; (3) aesthetic or vegetated screen is important in determining human response to noise which improved public perception of traffic noise due to visual and psychological relief.
The outcome of the study indicated that it is feasible to promote green noise barriers in Hong Kong, with the evidence of the potential benefits, technical experience and public support. It is also suggested that the living wall modular system is the best system which is suitable for the application in Hong Kong.published_or_final_version
Environmental Management
Master
Master of Science in Environmental Management
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Kwon, Suk-Jae. "Noise externalities : a hybrid model to assess effects and management with application to transportation issues in Rhode Island /." View online ; access limited to URI, 2006. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3225318.
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Lo, Chun Sing. "Application of cementitious rubber chips as noise and vibration barriers /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202005%20LO.
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Daltrop, Shira Nicole Jones. "Investigation of factors affecting the performance of roadside noise barriers." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/37535.
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Roadside noise barriers are used to prevent traffic noise from reaching nearby residences. Two factors that may affect the acoustical performance of highway noise barriers - surface absorption and nearby vegetation - were investigated. Three experimental techniques were used: full-scale laboratory tests, field tests, and scale-model tests. Tests with a 1.2m high barrier on a hard surface were performed in an anechoic chamber, using source and receiver positions corresponding to different diffraction angles. Absorption was added to the wall in various configurations and the change in insertion loss (IL) was measured. IL's of 12-18 dBA behind and -1 dBA in front of the reflective wall were found. Surface absorption increased IL by up to 2 dBA behind the barrier and 1 dBA in front. For the field tests, traffic noise was measured behind reflective noise walls without and with nearby foliage. Effects were small, less than 5 dB, but suggest that vegetation can either attenuate sound, increasing the IL, or scatter sound into the barrier shadow zone, decreasing the IL. A 1:31.5 scale-model highway configuration was created and tested in an anechoic chamber. Scale-model materials were chosen by performing excess attenuation measurements and doing a best fit using flow resistivity. Absorption was tested on single and parallel noise barriers of varying heights, allowing for a comparison between adding absorption and increasing the height. Foliage tests were performed on single and parallel barriers with various configurations of model trees. Barrier absorption prevented the amplification of sound between parallel barriers and adding absorption was equivalent to increasing the height by 0.33 m. The foliage test results were similar to the field tests; the effects were small and dependent on frequency and the size of the foliage. Predicting these results was attempted using ray tracing, the method of images (MOI), and finite element methods (FEM). An existing ray tracing model, PRAY, was modified and used; however the predicted IL’s were 10-30 dB greater than those measured. FEM gave IL's 2-8 dB lower and MOI gave IL's 5-20 dB lower than measurements.
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Chua, Chin Boon. "APPLICATION OF ABSORPTIVE TREATMENTS ON TRAFFIC NOISE BARRIERS IN FLORIDA." Master's thesis, University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4383.
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In this thesis, the parallel barrier analysis feature in the Federal Highway Administration Traffic Noise Model (FHWA TNM), which is based on RAYVERB was used to explore the effects of multiple reflections due to single and parallel barriers and the use of absorptive treatment. Database was developed from the data collected from previous research efforts was used to generate a best fit equation model that can be used as a predetermining tool to determine the magnitude of parallel barrier insertion loss. The best fit equation model was then used to test against measured/model result and TNM prediction results for its validity. Absorptive materials were also studied such that 3 top of them were selected and recommended for Florida highway barrier use. It was found that the top three absorptive treatments for use on Florida highway barriers have been determined to be cementitous material, metal wool and glass fiber. These materials can be used to reduce the sound reflections for single and parallel barriers. The developed best fit equation model from this research is Deg = -2.17NRC - CW[superscript 0.42] + 1.97eln(BH) + RH[superscript 0.29] + DBB[superscript 0.27]; the prediction results give moderately high R[superscript 2] value of 0.55 if compared to the results from database. Prediction results from best fit equation model was also found to be consistent with the results from the measure/modeled results, providing further proof of the validity of the model. However, if compared results from equation model, TNM and measured/model (measured and model compared results using ANSI method), TNM was shown to provide higher insertion loss degradation. It was found that the most effective placement of absorptive material was the pattern which covers the barrier from the bottom up; it was also found that only about 60% from the bottom of the barrier area requires covering with high NRC absorptive treatment (NRC greater than or equals to 0.8) without sacrificing insertion loss. Also, if the barrier area near the top includes an easily obtainable NRC value of 0.4, only 40% to 50% of the bottom barrier needs absorptive treatment with a higher, more expensive NRC rating. These findings can substantially reduce the cost of conventional absorptive barrier which have full coverage of high NRC absorptive treatment. This research has begun important improvements in noise barrier design, additional work can be continued to further verify all the findings in this thesis such that easier and better equation model can be developed to calculate insertion loss degradation and cheaper absorptive barrier with less absorptive material usage can be built.M.S.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil and Environmental Engineering
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Morgan, Philip Alan. "Boundary element modelling and full scale measurement of the acoustic performance of outdoor noise barriers." Thesis, Brunel University, 1999. http://bura.brunel.ac.uk/handle/2438/4921.
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The performance of various designs of outdoor noise barrier has been investigated using numerical modelling and full scale experiments. The numerical modelling has been performed using a two-dimensional boundary element method. The model has been extended to allow the efficient simulation of barrier arrangements on ground having two distinct impedance values and cross-sections incorporating cuttings. It has been reported previously that the performance of a plane screen can be enhanced by adding a device to the top of the barrier to induce destructive interference. Full scale modelling and boundary element simulations have been performed on one such commercially available device. It has been shown that, taking the height increase into account, the major contribution to the improved performance is the presence of two diffracting edges rather than any interference effects generated. It is known that the performance of a single barrier is degraded following the introduction of a barrier on the opposite side of a source. Boundary element simulations of such parallel arrangements have been performed. Modifications have been proposed to reduce the over-estimation of multiple reflections within the model, together with a method for converting predictions to the equivalent point source values. Sound absorptive, tilted and median barriers have been shown to be effective in reducing the degradation. A multiple-edge barrier configuration is known to offer improved screening performance over a plane screen. Reported in-situ measurements have suggested the behaviour to be influenced by site geometry. Boundary element calculations have been performed to identify a more efficient variant of the device. The results suggest the addition of an inclined base panel to be most effective. The boundary element model has been used to investigate the effect of shape and surface treatment upon railway noise barriers. The model has been adapted to allow the use of dipole sources characteristic of railway noise. The cross-section of the rolling stock has been shown to affect the performance of rigid barriers. If the upper edges are coincident, the results suggest that simple absorptive barriers provide better screening than tilted designs. The addition of multiple edges further enhances performance.
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Lin, Kai-Jui. "Influence of weather conditions on the propagation of highway noise at sites with barriers." Ohio : Ohio University, 2000. http://www.ohiolink.edu/etd/view.cgi?ohiou1172598982.
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Clum, Craig M. "Highway traffic noise barrier overlap gap model." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177442958.
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Strandquist, Karl, and Johannes Mattsson. "Luftspalters inverkan på bullerskärmars ljudreduktion." Thesis, Uppsala universitet, Byggteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-357003.
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Common practice in acoustic design does not consider air gaps. Thereare different opinions about air gaps and their affect on noise reduction.The report analyzes the credibility of the requirements used in a theoretical calculation model that addresses noise reduction in acoustic screens. Several measurement results from empirical attempts in a realistic environment for different screen models are compared.The result shows that a horizontal 50-millimeter gap has no noticeable impact on noise reduction. The result for horizontal air gaps against ground is of particular interest as it allows a simplified foundation to be used.Vertical air gaps have a greater negative influence on noise reduction but the results presented in the report can be used when lower demands are set on screens.An economic analysis shows that the result from the experiment when using a simplified foundation results in a cost reduction ofapproximately 300 SEK per meter acoustic screen.
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Bull, John Ivan. "Measurement of the airborne sound insulation of traffic noise barriers using impulse response techniques." Thesis, University of Canterbury. Mechanical Engineering, 2014. http://hdl.handle.net/10092/8962.
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This research thesis involves the measurement of the airborne sound insulation of road traffic noise barriers, with the goal of gaining a more in depth understanding of the factors that influence noise barrier performance. A measurement system is developed, based on EN 1793-6:2012, to quantify the airborne sound insulation of a noise barrier in situ. Validation testing is performed to ensure that the system meets the requirements of EN 1793-6:2012. MATLAB code is developed, incorporating all of the signal processing tasks into a single graphical user interface. The measurement system is then used to measure the airborne sound insulation of eight existing traffic noise barriers located around Auckland, New Zealand.
The results from the Auckland field tests show that consistent single number ratings of airborne sound insulation can be achieved on different samples of the same noise barrier. The presence of air gaps and hidden defects will degrade the acoustic performance of a noise barrier, most significantly at the high frequencies. The comparison of single number ratings calculated with differing measurement frequency ranges is discussed, and some comments are made on the measurement standard itself.
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Ghent, Jeremy E. "A digital signal processing approach to analyze the effects of multiple reflections between highway noise barriers." Ohio : Ohio University, 2003. http://www.ohiolink.edu/etd/view.cgi?ohiou1175090494.
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Arner, Wayne. "A DERIVATION OF AN EMPIRICAL EQUATION FOR ESTIMATING THE ACOUSTICAL SHADOW ZONE LENGTH OF ROADWAY NOISE BARRIERS." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2329.
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The objective of this research was to derive an empirical equation that estimates the acoustical shadow zone length (SZL) of roadway noise barriers. The acoustical shadow zone is the area behind a noise barrier of reduced sound levels, generally to some stated level at or near background. The ability to predict the SZL can be used as a method to evaluate the performance, and possibly the design, of roadway noise barriers. The current federally required roadway noise model is the Federal Highway Administration (FHWA) Traffic Noise Model (TNM). TNM uses insertion loss (IL) to evaluate the effectiveness of a barrier. Insertion loss is the difference in sound level between the "no barrier" and the "with barrier" case. One major limitation with TNM is that the reported IL does not take into account how background noise levels influence the mitigated sound levels. Background noise can be defined as the noise present at a barrier location in the absence of roadway noise. The shadow zone represents a region behind the noise barrier where the barrier is effective at reducing noise levels and takes into account how background noise affects the IL and thus the SZL. The inclusion of background noise becomes significant in evaluating barrier effectiveness because as the distance from the barrier increases, background noise begins to overtake roadway noise as the dominate noise source. The derivation of the empirical equation began by collecting in-situ noise measurements at 18 noise barrier locations across Florida. The measured noise data was supplemented by noise data obtained from computer modeling. After a sufficient quantity of measured and modeled IL data was obtained, a contour of equal IL (IL = 5 dB) was plotted for each barrier location. The area defined by the contour is called the shadow zone. All the SZLs were statistically compared to several variables that were expected to influence it. Regression modeling showed that the background noise level, noise barrier height, the distance from the roadway to the noise barrier, and percent of heavy truck traffic volume were statistically significant as useful predictors of SZL. Two empirical equations were derived, one from linear regression and one from polynomial regression, and are referred to as the Shadow Zone Equations.M.S.Env.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engineering
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Krezel, Zbigniew Adam, and n/a. "Recycled aggregate concrete acoustic barrier." Swinburne University of Technology, 2006. http://adt.lib.swin.edu.au./public/adt-VSWT20060821.154340.
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This document reports on a research project aimed at developing a concrete acoustic barrier
made from Recycled Aggregate (RA) Concrete. The research project was undertaken in
response to the needs expressed by the Victorian concrete recycling industry. The industry,
the scientific community conducting research into relevant disciplines, and the community
at large, represented by Victorian government agencies, are of the opinion that there is a
need to devise a higher value utilisation application for selected concrete recycling
products.
This document outlines the rationale and objectives of the research project which involves
the examination of Recycled Concrete (RC) Aggregate, the design and examination of RA
Concrete, and finally the development of an acoustic barrier made from RA Concrete.
The literature review presented in this report examines aspects of concrete recycling and
concrete technology pertaining to traditional and alternative constituent materials for
concrete production. Firstly, the importance and influence of fine and coarse aggregate on
basic properties of concrete is introduced. Secondly, an account on the use of alternative
materials in concrete technology, especially of coarse recycled aggregates and
supplementary cementitious materials (SCM) is described. Thirdly, some of the physical
and mechanical properties and how the use of RC Aggregate and SCM changes these
properties are discussed. Fourthly, a number of commonly used techniques and neutron
scattering techniques to investigate aggregate and concrete properties are introduced and
discussed. Fifthly, the porosity of aggregate and concrete including durability are
specifically discussed and testing methods are reasoned. The literature review also
discusses the use of no-fines concrete; its physical, mechanical and acoustic properties.
Finally it presents an account of the use of concrete in transportation traffic noise
attenuation devices.
This document continues with an outline of a methodology that was adopted in this
research project. It outlines experimental work aimed at examining the properties of RC Aggregate which amongst other properties includes porosity, particle size distribution,
water absorption, shape and density. It continues examining RA Concrete properties and
includes, among other properties, compressive strength, porosity and durability as well as
sound absorption of acoustic barrier. The methodology introduces standard and purposely
modified test procedures used in the examination of aggregates, concrete and acoustic
barrier. An account of various research techniques is presented, spanning from simple
visual observations to more sophisticated neutron scattering techniques. The summary of
test procedures follows a description of test specimen composition and their sizes, and a
suite of tested specimens. It also introduces statistical methods used to analyse test results.
After a detailed description of the aggregate, concrete and RA Concrete acoustic barrier,
the document outlines a summary of data generated through the experimental program of
this research project. The data on fine aggregate, on selected 14/10mm coarse RC
Aggregate, on concrete made from natural and recycled aggregate and on acoustic barrier
are presented and discussed. Test results of various physical, mechanical and acoustic
properties of aggregate, concrete and barrier are reported, analysed and discussed. The data
from observations, visual assessment and scientific experimentation of specific properties
are then crossed analysed in a search for relationships between properties of fine and coarse
aggregates and properties of concrete made from such aggregates. A cross analysis of data
on ?less-fines? RA Concrete and on the acoustic performance of barrier is examined, and
the relationship between the volume of interconnected voids in a porous part of ?less-fines?
concrete, and the sound absorption of acoustic barrier is discussed and reported.
The document then presents a synthesis of the literature review results, project aims
adopted within the experimental program and test results in the three main areas of this
research project. These areas include recycled concrete aggregate, recycled aggregate
concrete and acoustic barrier made from RA Concrete.
Finally, conclusions reached through the course of this investigation are summarised and
recommendations are proposed in relation to the RA Concrete acoustic barrier. The main
conclusion is that selected RC Aggregate can be used in the production of concrete of a compressive strength of 25MPa, if the moisture content and water absorption in the
aggregate are closely monitored, and the foreign material content is kept below 1.5%. The
author concludes that acoustic barrier made from selected RC Aggregate has unique sound
absorption characteristics that can easily be tunable by a selection of appropriate aggregate
and by specific concrete mix designs. Recommendations for further research are also
proposed.
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Krezel, Zbigniew Adam. "Recycled aggregate concrete acoustic barrier." Australasian Digital Theses Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20060821.154340.
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Thesis (PhD) - Swinburne University of Technology, 2006.Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Civil Engineering, Swinburne University of Technology - 2006. Typescript. Includes bibliographical references.
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Monazzam, Esmaeil Poor M. R. "Application of diffuser surfaces on single profile environmental noise barriers: evaluation, theory and optimization." Thesis, University of Salford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491800.
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Profile structures were previously introduced to improve the performance of noise barriers. Subsequent researches on reactive surfaces have shown that these surfaces improve the performance of the profile barriers at certain frequency ranges. This thesis details an investigation into prediction, measurement and the reduction mechanism of profile Schroeder diffuser barriers.
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DeBrunner, Victor Earl. "Sensitivity analysis of digital filter structures." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/104319.
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Uppenberg, Caroline, and Emma Jonsson. "Innovative noise protection solutions for Sweden's first high speed railway." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-27235.
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This thesis investigates and design innovative concepts of noise protection solutions (NPS) for the Swedish high-speed railway (HSR) that is planned to be built between Stockholm and Gothenburg in the near future. The planned traffic will start in 2035. The concepts have been developed through a design process, starting with a research phase of existing solutions for the problem, theory about noise and absorbing materials. Following by an analysis of all researched data to narrow down the project and the interviews with the Swedish transport administration, this in order to pinpoint the requirements for the NPS. To get opinions from people who are exposed to low frequency noise, two questionnaires were conducted with a total of 80 respondents. Because of the difficulty to find the exact target group of people who are only exposed to the noise from high speed trains, the first questionnaire was open for all people who are exposed to low frequency noise (traffic noise). The second questionnaire was published at Trafikverket Facebook page, and because of their high number of followers, people who are exposed to train noise could easily be reached. From the answers and the analyzed data, a requirement specification for the NPS was created with all the requirements that the NPS needed to have according to Trafikverkets standards and from the questionnaire. These requirements were the prerequisite used in the synthesis phase. Different brainstorming methods were used to develop a large amount of ideas. A workshop with people from the society was held to keep the creativity alive. From the first synthesis phase, six ideas out of 160 ideas were chosen by a dot evaluation, and in order to narrow down the ideas even more, a matrix evaluation was used. The matrix was built from the requirement specification to verify which ideas fit most of the requirements for a new NPS. From this evaluation, two concepts were chosen to be developed further. After a validation from Trafikverket, the two concepts were further developed, this by an open brainstorming session. Via discussions and sketching, new ideas for the concepts arose. We found solutions for the problems that arose with each concept and made final decisions about the design and material. Three concepts were 3D visualized in the CAD program Rhinoceros. Final touches of the concepts were made in Keyshot. Throughout this thesis, three concepts for noise protections for the HSR have been developed and the research question “How can innovation be created by using a design process?” have been discussed and answered.
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Zhang, Nan. "SCALE MODELS OF ACOUSTIC SCATTERING PROBLEMS INCLUDING BARRIERS AND SOUND ABSORPTION." UKnowledge, 2018. https://uknowledge.uky.edu/me_etds/119.
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Scale modeling has been commonly used for architectural acoustics but use in other noise control areas is nominal. Acoustic scale modeling theory is first reviewed and then feasibility for small-scale applications, such as is common in the electronics industry, is investigated. Three application cases are used to examine the viability. In the first example, a scale model is used to determine the insertion loss of a rectangular barrier. In the second example, the transmission loss through parallel tubes drilled through a cylinder is measured and results are compared to a 2.85 times scale model with good agreement. The third example is a rectangular cuboid with a smaller cylindrical well bored into it. A point source is placed above the cuboid. The transfer function was measured between positions on the top of the cylinder and inside of the cylindrical well. Treatments were then applied sequentially including a cylindrical barrier around the well, a membrane cover over the opening, and a layer of sound absorption over the well. Results are compared between the full scale and a 5.7 times scale model and correlation between the two is satisfactory.
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Jolibois, Alexandre, and Alexandre Jolibois. "A study on the acoustic performance of tramway low-height noise barriers : gradient-based numerical optimization and experimental approaches." Phd thesis, Université Paris-Est, 2013. http://pastel.archives-ouvertes.fr/pastel-00965168.
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Noise has become a main nuisance in urban areas to the point that according to the World Health Organization 40% of the European population is exposed to excessive noise levels, mainly due to ground transportation. There is therefore a need to find new ways to mitigate noise in urban areas. In this work, a possible device to achieve this goal is studied: a low-height noise barrier. It consists of a barrier typically less than one meter high placed close to a source, designed to decrease the noise level for nearby pedestrians and cyclists. This type of device is studied both numerically and experimentally. Tramway noise barriers are especially studied since the noise sources are in this case very close to the ground and can therefore be attenuated efficiently. The shape and the surface treatment of the barrier are optimized using a gradient-based method coupled to a 2D boundary element method (BEM). The optimization variables are the node coordinates of a control mesh and the parameters describing the surface impedance. Sensitivities are calculated efficiently using the adjoint state approach. Numerical results show that the shapes generated by the optimization algorithm tend to be quite irregular but provide a significant improvement of more than 5 dB (A) compared to simpler shapes. Utilizing an absorbing treatment on the source side of the barrier is shown to be efficient as well. This second point has been confirmed by scale model measurements. In addition, a full scale low height noise barrier prototype has been built and tested in situ close to a tramway track in Grenoble. Measurements show that the device provides more than 10 dB (A) of attenuation for a close receiver located at the typical height of human ears. These results therefore seem to confirm the applicability of such protections to efficiently decrease noise exposure in urban areas
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Cardenas, Pablo, and Peter Wall. "Jämförelse mellan bullerreducerande beläggning och bullerskärm. : Ur ett kostnads- och tekniskt perspektiv." Thesis, KTH, Byggteknik och design, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-141995.
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Den bullerreducerande beläggnigen har en porös struktur som förbättrar dräneringen och reducerar buller vid källan men egenskaperna orsakar ett snabbt slitage och portäppning. Detta medför att beläggningen måste omläggas och rengöras oftare än en konventionell beläggning som t.ex. ABS 16. Kritiken mot den bullerreducerande beläggningen riktar sig på de höga drift- och underhållskostnaderna, detta gör att många väghållaren satsar på bullerskärm som bulleråtgärd. Syftet med arbetet är att jämföra bullerreducerande beläggning med bullerskärm, för att reda på vilken bulleråtgärd är mer kostnadseffektivt under 20 år. Ett teoriavsnitt kommer att förklara och beskriva på ett tekniskt sätt: väg, ljud och buller, bullerskärm och bullerreducerande beläggningar. Kostnadsjämförelsen mellan bulleråtgärderna omfattar investering, drift och underhåll. Den fördjupar sig på en befintlig sträcka vid Gamla Enskede i Nynäsvägen, där det sedan 2012 finns bullerskärmar. De riktiga priserna av skärmarna ställs mot priserna för en eventuell bullerreducerande beläggning i sträckan. Priserna, antal omläggningar och bullerreducerande förlusten per år för den bullerreducerande beläggningen blev antagna genom beräkningar utifrån verkliga sträckor. Med hjälp av kalkyler och diagram kunde det noteras att bullerskärmarna är dyrare än bullerreducerande beläggningen. Förklaring av kostnadsresultat medföljs av rekommendationer som anses vara relevanta för att ha i åtanke för framtida val av bullerreducerande åtgärder.Noise reducing pavement has a porous structure that improves drainage and reduces traffic noise but these propitious qualities causes’ problems such as rapid wear and pore clogging. This means that the pavement must be repaved and cleaned more frequently than a conventional pavement such as ABS 16. Criticism of the noise reducing pavement has been raised and has to do with the high operating and maintenance costs, this result in more invests in noise barriers instead. The purpose with this review is to compare noise reducing pavement with noise barriers, in order to determine which noise provision is more cost effective during a period of 20 years. There will be a theory chapter were it will be explain and describe in a technical method: Road, sound and noise, noise barriers and noise-reducing pavement. Cost comparison of noise provisions includes investment-, operation- and maintenance cost. This review immerses on an existing road at Gamla Enskede in Nynäsvägen, which since 2012 has noise barriers. The actual prices of the noise barriers in Gamla Enskede will be compared to a possible noise reducing pavement. Prices, quantity of pavement replacement and noise loss per year for the noise reducing pavement was presumed by calculations based on actual distances with noise reducing pavement. Observation of our calculations and charts reveals that noise barriers are more expensive than noise reducing pavement. Explanations of cost results are accompanied by recommendations that are considered relevant to have in mind for future choices of noise reduction provisions.
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Roth, Emelie. "Undersökning av ny fältmätningsmetod för bullerskyddsskärmar med avseende på ljudabsorption." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355081.
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För att undersöka bullerskyddsskärmars akustiska prestanda med avseende på ljudabsorption mäts idag absorptionen inomhus i laboratorier. Detta är oftast inte lämpligt eftersom bullerskyddsskärmar används utomhus, där ett annat ljudfält råder. Således introducerades en ny mätstandard år 2016 för att kunna undersöka ljudabsorptionen i fält, med benämningen SS-EN 1793-5:2016. Metoden innebär att ljudreflektionen uppmäts, där ljudabsorptionen sedan kan erhållas eftersom de är varandras komplement. Mätmetoden tillämpades på tre bullerskyddsskärmar för att identifiera för- och nackdelar med metoden, analysera skillnader i ljudabsorption mellan olika typer av bullerskyddsskärmar samt för att jämföra ljudabsorptionen mellan fält- och laborationsmätningar. Det sistnämnda eftersom tidigare studier har visat att ljudabsorptionen generellt överskattas vid laborationsmätningar i jämförelse med fältmätningar (CEDR, 2017). Metoden var praktiskt genomförbar och fördelarna är att mätmetoden är mer representativ än laborationsmätningar för bullerskyddsskärmar där direkt ljudfält råder samt att metoden möjliggör undersökning av ljudabsorptionens förändring över tid. Nackdelar som påvisades var att metoden är tidskrävande, att skärmens ljudisolering även behöver mätas för att få reda på den fullständiga ljudabsorptionen, att det saknas tydliga specifikationer för hur mätdata för bullerskyddsskärmar som är < 4 m höga ska analyseras samt att låga frekvenser blir ogiltiga för skärmar som har en höjd < 4 m. De tre mätobjekten som undersöktes var en skärm i laminerat härdat glas i närheten av Fridhemsplan i Stockholm, en skärm i sträckmetall beklädd med vegetation intill Lidingövägen i Stockholm samt en skärm i Knivsta som består av sektioner i aluminium respektive akrylglas. Glasskärmen vid Fridhemsplan var generellt mest reflekterande, följt av akryglassektionen i Knivsta. Aluminiumsektionen i Knivsta och den vegetationsbeklädda metallskärmen vid Lidingövägen var mest absorberande. Skillnaderna mellan skärmarna berodde på att de består av olika material som var olika reflekterande respektive absorberande. För aluminiumsektionen i Knivsta utfördes en jämförelse mellan ljudabsorptionen som tidigare hade uppmätts i laboratorium och ljudabsorptionen som uppmättes i fält. Sektionen uppvisade mer ljudabsorption vid mätning i laboratorium än vid mätning i fält. Detta ansågs främst bero på att ljudfälten skiljer sig mellan laboratorium och fält.
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Soares, Fabiano Silva. "Avaliação do uso de barreira acústica para escolas municipais em Porto Alegre." Universidade do Vale do Rio dos Sinos, 2018. http://www.repositorio.jesuita.org.br/handle/UNISINOS/7329.
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O crescimento desordenado das cidades tem aumentado significativamente a poluição sonora, ao mesmo tempo que ocasionam desgaste nas relações entre vizinhos, prejudicando o bem-estar da comunidade. Uma das alternativas utilizadas para reduzir estes efeitos são as barreiras acústicas, visto que se configuram numa das soluções mais eficazes para a redução da propagação do som em área livre. Neste panorama, a escola sempre foi tratada como receptora sensível, sendo raramente considerada emissora do ruído, em virtude deste fato é que a dissertação se desenvolve. Desta forma, neste trabalho é proposta a utilização de barreiras acústicas como forma de solucionar a livre propagação do som emitido durante atividades de recreação em duas unidades educacionais do município de Porto Alegre. O principal problema consiste em se reduzir os níveis de pressão sonora incidente nas edificações vizinhas, afim de garantir o atendimento aos níveis estabelecidos pelas normas ABNT NBR 10151 e 10152. Por ser fundamentado em situações reais, o estudo de caso envolveu levantamentos de campo dos espaços físicos das escolas e das residências vizinhas, ensaios em laboratório para determinação do coeficiente de absorção sonora, ensaios em campo para a determinação dos níveis de pressão sonora emitidos pelas crianças nas escolas. As medições em campo indicaram que os níveis sonoros internos nas residências vizinhas e externos nos playgrounds estão acima dos indicados pelas normas. Para a sequência do trabalho, foi desenvolvido um protótipo de barreira sonora, utilizando conceitos de reflexão sonora e absorção, tal como um ressonador de Helmholtz e após, ensaiado em laboratório. Com os dados obtidos nos ensaios laboratoriais da amostra, se obteve um coeficiente de absorção sonora ponderado (αw) de 0,7. O software CadnaA® foi a ferramenta utilizada para a realização de simulação dos projetos das barreiras acústicas em ambas escolas, sendo demonstrada uma redução de 15 dB para a escola Jardim Camaquã e 5 dB para a escola Unidos da Paineira, sendo que a utilização do acabamento de topo com inclinação apresentou redução significativa apenas na escola Jardim Camaquã. A proposta da inserção das barreiras sonoras se mostrou relevante, mas ainda assim, não atingiu os valores determinados pelas normas.
The disorderly growth of cities has contributed to a significant increase of noise pollution, at the same time as it causes frictions between neighbors, jeopardizing the well-being of communities. One of the alternatives used to reduce these effects is the adoption of acoustic barriers, since it is one of the most effective solutions to reduce the propagation of sound in open space. In the scenario, the school has always been seen as a sensitive receptor, and hardly ever considered a sound emitter, and this is the research subject of the present dissertation. Therefore, this work proposes to discuss the use of acoustic barriers as a way to solve the free propagation of emitted sound during recreation activities in two educational facilities in the city of Porto Alegre. The main problem consists in reducing the levels of sound pressure that reach neighboring buildings, as a way to guarantee the observance of levels established by the Associação Brasileira de Normas Técnicas (ABNT – Brazilian Association of Technical Norms) in the norms NBR 10151 and 10152. As it was grounded in real situations, the case study involved field surveys to assess school and neighboring building physical spaces, laboratory tests to determine the sound absorption coefficient, and field tests to determine the levels of sound pressure emitted by children at the schools. The field tests showed that noise levels inside the neighboring buildings and outside on the playgrounds were above the ones established in the norms. For the continuity of the study, a sound barrier prototype was built, using concepts of noise reflection and absorption, as the Helmholtz resonator, and then tested in laboratory. According to the results obtained with the sample, a weighted sound absorption coefficient (αw) of 0.7 was obtained. The CadnaA® software was the tool used to conduct simulations of sound barrier projects in both schools. A reduction of 15 dB was demonstrated at Jardim Camaquã School, whilst a 5 dB reduction was demonstrated at Unidos da Paineira School, being that the use of inclined top finish only represented significant reduction at Jardim Camaquã School. The use of sound barriers was proved relevant, but even so the levels established by norm were not reached.
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Regnard, Jean-Philippe. "Développement d’un concept d’isolant éco-acoustique." Mémoire, Université de Sherbrooke, 2011. http://hdl.handle.net/11143/6737.
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Résumé : Le but de cette étude est de développer un concept d’isolant acoustique à base de matières recyclées. Ce projet, initié par le Ministère des Transports du Québec (MTQ), s’inscrit dans la conception d’écrans antibruit répondant aux exigences actuelles du développement durable et de la loi sur l’environnement. L’isolant acoustique devra donc être également recyclable. Un matériau de type coupe-son est caractérisé par son indice d’affaiblissement sonore. Plus un matériau est lourd, plus il est isolant. Cependant, un phénomène physique provoque une importante chute de son efficacité à une fréquence précise dépendant de la rigidité spécifique du matériau (i.e. rapport du module d’Young sur la masse volumique). Il devra donc avoir une masse importante tout en ayant un module d’Young adéquat pour éviter ce phénomène. Le polyéthylène basse densité linéaire (LLDPE), thermoplastique recyclable de grande consommation, est alors alourdi avec des billes d’acier de grande taille (3.175 mm) afin d’augmenter la rigidité spécifique du composite résultant. Le composite ainsi formé montre néanmoins une augmentation du module d’Young qui compense l’ajout de masse. Cette augmentation est causée par la liaison interfaciale entre le LLDPE et les billes de fer. Pour limiter cette cohésion, un effort de traction a été effectué sur les échantillons. Ceci a eu pour effet de briser le lien mécanique à l’interface des billes et du LLDPE. En conséquence, le module a suffisamment chuté pour atteindre des valeurs inférieures au matériau brut. De plus, l’augmentation de la fraction volumique va de pair avec la réduction du module d’Young. Un modèle analytique de prédiction du module d’Young en fonction de la fraction volumique de billes d’acier a été également établi. Il a été comparé aux modèles existants et a montré de bons résultats avec les mesures.
Des simulations acoustiques de la perte par transmission ont par la suite été effectuées sur les composites obtenus afin d’évaluer leurs performances par rapport aux matériaux usuels (e.g. béton, gypse, verre,…) et par rapport à des écrans antibruit existants. Les résultats ont démontrés que les composites peuvent parfaitement se substituer aux matériaux utilisés et présentent dans certains cas de meilleurs résultats. || Abstract : The aim of this study is to develop a concept of an acoustic reflective material using recycled materials. This project, initiated by the Ministre des Transports du Quebec (MTQ), fits with the current requirements of sustainable development and environmental law. So the acoustic material should be also recyclable.
An acoustic reflective material is characterized by its sound transmission loss. The heavier the material is, the better is its sound transmission loss. However, a physical phenomenon causes a significant drop in efficiency at a specific frequency depending on the specific stiffness of the material (i.e., the ratio of Young’s modulus and density) So the material must be heavy and should have a Young modulus adapted to avoid this phenomenon.
Linear low density polyethylene (LLDPE), a largely available recyclable thermoplastic material, is then weighed down with large steel balls (3.175 mm diameter) to increase the specific stiffness of the resulting composite. However, the composite thus formed shows an increase of its Young's modulus that compensates for the added mass. This increase is caused by the interfacial bonding between the LLDPE and steel balls. To limit this bonding, a tensile stress was applied on the samples. This had the effect of breaking the mechanical link at the interface. As a result, the modulus has dropped to a value below that of the raw material. In addition, the increase in volume fraction of steel balls goes hand in hand with the reduction of the Young's modulus. An analytical model for predicting Young's modulus as a function of volume fraction of steel balls was also established. It was compared to existing models and shown good agreement with measurements.
Simulations of the acoustic transmission loss are subsequently carried out on the obtained composites to evaluate their acoustical performance compared to conventional materials (e.g. , concrete, gypsum, glass, ...) and to existing noise barriers. The results show that the developed composites can fully replace conventional materials and show better results in some cases.
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Koussa, Faouzi. "Evaluation de la performance acoustique des protections antibruit innovantes utilisant des moyens naturels : application aux transports terrestres." Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00776758.
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Le bruit dû aux infrastructures de transports terrestres fait partie des premières préoccupations environnementales de ce début de 21e siècle. Un moyen utilisé pour réduire ce bruit est de placer des protections acoustiques le long des grands axes routiers et ferroviaires. Actuellement, les choix de ces protections antibruit se portent généralement sur des solutions traditionnelles : écran droit, merlon, écran incliné, écran avec un couronnement. Le but de ce travail est de proposer des protections acoustiques innovantes utilisant des moyens naturels et d'en étudier la performance acoustique en utilisant des approches numériques et expérimentales. L'approche numérique peut être couplée en outre à un outil d'optimisation, développé dans cette thèse, pour chercher des formes améliorées de tels dispositifs antibruit novateurs. Après une présentation des principaux phénomènes mis en jeu dans la propagation des ondes acoustiques en milieu extérieur complexe, un état de l'art des principaux écrans acoustiques dédiés aux transports terrestres a été établi, permettant de choisir trois protections antibruit innovantes pour en étudier la performance acoustique. Une analyse des principales méthodes de simulation numérique, de mesure et d'optimisation des protections antibruit a permis de choisir les méthodes adaptées à notre problématique des écrans acoustiques utilisant des moyens naturels. Les méthodes choisies ont été utilisées dans ce travail pour évaluer la performance acoustique de ces écrans innovants. Pour le premier écran choisi, dit écran en gabions, nous avons effectué des mesures in-situ et sur modèles réduits, ainsi que des simulations numériques montrant une efficacité satisfaisante. Pour le deuxième écran, utilisant des cristaux soniques, et pour le troisième écran, de type merlon acoustique de forme complexe, nous avons réalisé une étude numérique paramétrique suivie d'une étude d'optimisation. Les résultats des calculs ont montré l'intérêt de tels dispositifs antibruit pour réduire le bruit de circulation routière et ferroviaire en milieu urbain et ils ont abouti à des formes améliorées des protections acoustiques utilisant des moyens naturels.
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Sjöberg, Andrea. "Utvärdering av standard EN 1793–6:2012 för att undersöka bullerskyddsskärmars effektivitet in-situ." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-347175.
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Bullerskyddsskärmar används för att reducera buller från väg- och spårtrafik. Syftet med examensarbetet var att utvärdera standard EN 1793–6:2012, en mätmetod för att undersöka bullerskyddsskärmars effektivitet in-situ med avseende på ljudisoleringen. I nuläget bestäms bullerskyddsskärmars effektivitet med laborationsmätningar i ett diffust ljudfält, som inte överensstämmer med det direkta ljudfält och den komplexitet som är in-situ. Till följd av det blir ofta laborationsmätningarna missvisande. Det finns även en okunskap kring håligheter/ läckage och hur det påverkar den akustiska prestandan, vilket gör att det emellanåt leder till brister i installationen av bullerskyddsskärmar och att enhetens ljudreducering inte stämmer överens med förväntningarna. Det finns således ett behov av att bestämma en bullerskyddsskärms befintliga prestanda in-situ för att säkerställa de krav som ställs i specifikationerna. EN 1793–6:2012 ansågs vara lämplig för ändamålet men fler mätningar behövs utföras för att kunna säkerställa resultaten och för att verifiera mätsystemet. Ljudisoleringen bestämdes som en funktion av frekvenser i tersband och var giltiga i frekvensområdet mellan 200 Hz till 5 kHz respektive 400 Hz till 5 kHz. De undersökta bullerskyddsskärmar var: en i laminerat och härdat glas med aluminiumpelare, en icke-homogen vegetationsskärm i stålram och en kombinerad bullerskyddsskärm i akrylglas med aluminiumprofiler. Resultaten jämfördes med laborationsmätningar och/eller simuleringar i Insul. Bullerskyddsskärmarna i glas gav högre värden på ljudisoleringen än i laborationsmätning, ett resultat som kan bero på skillnaderna mellan diffust ljudfält och direkt ljudfält. Komplexiteten i vegetationsskärmen gjorde resultaten svåra att analysera, men läckage förekom i de högre frekvenserna. Adrienne-fönstren behövde bli specifikt beräknade för samtliga impulssvar eftersom dimensionerna för bullerskyddsskärmarna inte överensstämde med vad som definieras i EN 1793–6:2012 för certifieringsändamål. I EN 1793–6:2012 omnämns inte heller markreflektion, som påverkar den filtrerade signalen. Vidare studier behövs för att filtrera bort dessa oönskade komponenter.Road traffic noise devices, for example noise barriers, are used to reduce the noise from road traffic and trams. The purpose of this master thesis is to evaluate the standard EN 1793-6:2012, a test method for determining noise barriers efficiency in-situ. Currently, noise barriers efficiency is determined with laboratory measurements in a diffuse sound field, which does not reflect the direct sound field and the complexity that are in-situ. As a result, laboratory measurements are often misleading. Due to a lack of knowledge about leakage, there are sometimes defects caused in the installation of the noise barriers that adversely affect the acoustic properties. There is thus a need to determine the intrinsic parameters of a noise barrier in-situ to ensure the requirements set in the specifications. The new method described in EN 1793-6:2012 was considered useful for the purpose but it was found that more measurements need to be performed to ensure results and to verify the measurement system. The sound insulation was determined for three noise barriers where results are expressed as a function of frequency in one third octave band and were valid in the frequency range between 200 Hz to 5 kHz respective 400 Hz to 5 kHz. The noise barriers tested were: a barrier in laminated glass with metal posts, a non-homogeneous vegetation barrier in a steel frame and a combined barrier with acrylic glass and metal. The results were compared with laboratory measurements and/or simulations in Insul. The glass barriers showed higher values of the sound insulation index than the laboratory measurements, perhaps due to the different sound fields. The complexity of the vegetation barrier made the results difficult to analyze, but leakage occurred in the higher frequencies. The Adrienne temporal windows were specifically calculated for all impulse responses, since the dimensions of the noise barriers differed from the one defined in EN 1793-6: 2012 for certification purposes. Also, in EN 1793-6: 2012, ground reflection, which affects the filtered signal, is not mentioned. Further studies are needed to filter out these unwanted components.
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Jolibois, Alexandre. "A study on the acoustic performance of tramway low height noise barriers: gradient-based numerical optimization and experimental approaches ( Étude de la performance acoustique des écrans antibruit de faible hauteur pour le tramway : optimisation numérique par méthode de gradient et approches expérimentales)." Thesis, Paris Est, 2013. http://www.theses.fr/2013PEST1116/document.
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Le bruit est devenu une nuisance importante en zone urbaine au point que selon l'Organisation Mondiale de la Santé, 40% de la population européenne est exposée à des niveaux de bruit excessifs, principalement dû aux transports terrestres. Il devient donc nécessaire de trouver de nouveaux moyens de lutter contre le bruit en zone urbaine. Dans ce travail, on étudie une solution possible à ce problème: un écran bas antibruit. Il s'agit d'un écran de hauteur inférieure à un mètre placé près d'une source, conçu pour réduire le niveau de bruit pour les piétons et les cyclistes à proximité. Ce type de protection est étudié numériquement et expérimentalement. Nous nous intéressons particulièrement aux écrans adaptés au bruit du tramway puisque dans ce cas les sources sont proches du sol et peuvent être atténuées efficacement. La forme ainsi que le traitement de surface de l'écran sont optimisés par une méthode de gradient couplée à une méthode 2D d'éléments finis de frontière. Les variables à optimiser sont les coordonnées de nœuds de contrôle et les paramètres servant à décrire l'impédance de surface. Les sensibilités sont calculées efficacement par la méthode de l'état adjoint. Les formes générées par l'algorithme d'optimisation sont assez irrégulières mais induisent une nette amélioration par rapport à des formes simples, d'au moins 5 dB (A). Il est également montré que l'utilisation de traitement absorbant du côté source de l'écran peut améliorer la performance sensiblement. Ce dernier point est confirmé par des mesures effectuées sur modèle réduit. De plus, un prototype à l'échelle 1 d'écran bas antibruit a été construit et testé en conditions réelles, le long d'une voie de tramway à Grenoble. Les mesures montrent que la protection réduit le niveau de 10 dB (A) pour un récepteur proche situé à hauteur d'oreilles. Ces résultats semblent confirmer l'applicabilité de ces protections pour réduire efficacement le bruit en zone urbaineNoise has become a main nuisance in urban areas to the point that according to the World Health Organization 40% of the European population is exposed to excessive noise levels, mainly due to ground transportation. There is therefore a need to find new ways to mitigate noise in urban areas. In this work, a possible device to achieve this goal is studied: a low-height noise barrier. It consists of a barrier typically less than one meter high placed close to a source, designed to decrease the noise level for nearby pedestrians and cyclists. This type of device is studied both numerically and experimentally. Tramway noise barriers are especially studied since the noise sources are in this case very close to the ground and can therefore be attenuated efficiently. The shape and the surface treatment of the barrier are optimized using a gradient-based method coupled to a 2D boundary element method (BEM). The optimization variables are the node coordinates of a control mesh and the parameters describing the surface impedance. Sensitivities are calculated efficiently using the adjoint state approach. Numerical results show that the shapes generated by the optimization algorithm tend to be quite irregular but provide a significant improvement of more than 5 dB (A) compared to simpler shapes. Utilizing an absorbing treatment on the source side of the barrier is shown to be efficient as well. This second point has been confirmed by scale model measurements. In addition, a full scale low height noise barrier prototype has been built and tested in situ close to a tramway track in Grenoble. Measurements show that the device provides more than 10 dB (A) of attenuation for a close receiver located at the typical height of human ears. These results therefore seem to confirm the applicability of such protections to efficiently decrease noise exposure in urban areas
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Brolin, Nils. "Product Development of Curved Noise & NOx Barrier." Thesis, KTH, Maskinkonstruktion (Avd.), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-41524.
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Sammanfattning Genom att använda olika produktframtagningsprocesser och metoder tas en ny typ av buller och NOx-skydd fram. Från idé och konceptgenerering till färdig skalmodell. Bullerskyddet är paraboliskt utformat och hänger över vägbanan vilket ger den unika ljudreducerande egenskaper utan att tumma på vägsäkerheten. Genom att utnyttja geometrin, kan en extra ljudreducering om ca 3 [dB] tillämpas. Det motsvarar en halvering av ljudeffekten och kan jämföras med att höja trafikhastigheten från en 70-väg till 90 [km/h] utan att bullernivån höjs. Enligt SS-EN 1794-1/2 får bullerskyddet en klassifikation B3 eller beräknat 24 [dB] ljudreducering. Genom tillbehöret ”Absorbing Arm” ges en möjlighet att även absorbera en del av oljudet på ett effektivt sätt tack vare den paraboliska geometrin. Ytterligare värde får produkten genom sin NOx-reducerande förmåga. Betongytor i NOx-reducerande betong samverkar med självrengörande glas genom titaniumdioxid (TiO2) samt UV-ljus (solen eller UV-lampor i tunnlar) och bryter ned farliga NOx-utsläpp (från trafiken) till ofarliga nitrater. Detta reducerar omgivande utsläpp och förbättrar luftkvaliteten. Bullerskyddet är gjort av flera olika komponenter som ingår i ett stort system av fabriksgjorda moduler som monteras på plats. Detta för att effektivisera planering och konstruktion, samt spara pengar vid nybyggnation av bullerskydd. Modulanpassningen ger också upphov till flexibla system som lätt kan anpassas och ändras efter behov, vilket ger en stor flexibilitet i utformandet.Abstract By using different product development processes and methods a new type of noise and NOx barrier is developed, from idea to scale model. The barrier is parabolic shaped and overlays the road, giving it unique attributes that aids the noise reduction ability without intruding on road safety. By using this geometry, an additional 3 [dB] of noise reduction can be estimated. This difference is equal to increasing the speed limit of a 70 [km/h] road to 90 [km/h] without increasing the noise levels. The overall classification according to SS-EN 1794-1/2 of the barrier is B3, giving a noise reduction of an estimated 24 [dB]. With the additional add-on “Absorbing Arm”, the product has the possibility to absorb the noise in an effective way due to its parabolic geometry. Additional value to the product is a NOx-reducing ability, made possible by utilizing NOx-reducing concrete and glass. NOx-particles emitted from the traffic are bound on the surface of the material reacting together with titanium dioxide (TiO2) and UV-light transforming them into harmless nitrates, lowering the surrounding pollution levels. The product is made out of several different components, combined together through a system, which give rise to a pre-manufactured module that are assembled on location. By doing so a more flexible and economical system for planning and constructing efficient noise barriers is presented.
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Joynt, Jennifer L. R. "A sustainable approach to environmental noise barrier design." Thesis, University of Sheffield, 2005. http://etheses.whiterose.ac.uk/12880/.
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This thesis recognises the implicit shortfalls in the current methods of noise barrier development. An holistic and integrative methodology was devised, which can be potentially incorporated into general practise, without the unnecessary burdens of excessive cost and environmental impacts. In essence the thesis defines, 'a sustainable approach to environmental noise barrier design'. The importance of sustainability as a key determinant of a noise barrier's success is demonstrated through the impacts of public participation on the acceptance of a noise barrier. This was achieved through the triangulation of a grounded theory, formulated through the qualitative analysis of a real case study and then tested quantitatively on a larger representative sample. The theory explored the impact of ineffective public participation on the perceived success of a noise barrier. Noise maps were developed for the comparison of subjective opinions with objective facts. This also illustrated how this technology can be manipulated to focus public participation, and increase success. Demonstrating the utility of this growing resource beyond its current scope. A methodology for assessing the embodied impacts of noise barrier structures was also devised. By addressing the current lack of availability of a specific model, the means of choosing a noise barrier based on sustainable assets was revealed. Finally, the thesis concluded with a laboratory experiment, which utilised a RAVE facility and revealed the extent to which preconceptions play a role in the perception of a noise barriers' effectiveness. Revealing that regardless of which noise barrier is presented, that preconceptions of a materials' ability to attenuate noise are imbedded. The thesis contributed to several areas through the illustration of a sustainable approach to environmental noise barrier design. The methods highlighted, demonstrate how those responsible for building noise barriers, can improve the acceptance by the public and decrease the environmental impacts associated with the construction of these structures.
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Funke, Henrik L., Sandra Gelbrich, and Lothar Kroll. "Development of Effective Textile-Reinforced Concrete Noise Barrier." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-175299.
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Thin-walled, high-strength concrete elements exhibiting low system weight and great slenderness can be created with a large degree of lightweight structure using the textile-reinforced, load-bearing concrete (TRC) slab and a shell with a very high level of sound absorption. This was developed with the objective of lowering system weight, and then implemented operationally in construction.
Arising from the specifications placed on the load-bearing concrete slab, the following took place: an adapted fine-grain concrete matrix was assembled, a carbon warp-knit fabric was modified and integrated into the fine concrete matrix, a formwork system at prototype scale was designed enabling noise barriers to be produced with an application-oriented approach and examined in practically investigations within the context of the project. This meant that a substantial lowering of the load-bearing concrete slab’s system weight was possible, which led to a decrease in transport and assembly costs.
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Burrows, G. W. "The effect of wind turbulence on noise barrier performance." Thesis, Liverpool John Moores University, 1985. http://researchonline.ljmu.ac.uk/5587/.
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An investigation has been carried out into the effect of wind turbulence on the propagation of sound over open grassland both with, and without, a 2.4m high barrier present. Sound bursts, derived from a variety of original signals, were generated using a horn loudspeaker and the resulting levels were measured using two variably positioned microphones, the further of which was placed at distances of up to 24m from the source. Simultaneous measurements were made of a variety of meteorological parameters. A microcomputer-based system was developed to control the experiments-and store the measured data for subsequent retrieval and analysis. As one of the approaches adopted in a search for visible evidence of correlation between various acoustical and meteorological parameters, the measured level difference for each sound burst was displayed graphically against the corresponding value of a particular measure of wind turbulence. For many combinations of measurement geometry and acoustic signal type, the data points fell, with a noticeable degree of consistency, within an envelope of characteristic shape. The shape implied that when the instant of transmission of a sound burst coincided with a low value of the measure of local turbulence, the apparent level difference was subject to considerable statistical fluctuation. This was the case both with and without the barrier present. As the turbulence increased, however, the propagating medium appeared to behave as a progressively more uniform and stable one and the observed scatter correspondingly reduced. The origin of this behaviour remains unclear; however the presence of the barrier, it was concluded, did not appear to modify this effect. 1 to 16 laboratory scale model experiments have been carried out to investigate the replication of the above effects and the results are reported.
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Kviman, Oskar, and Linus Nilsson. "Applicability of a Translucent Barrier Based Model of Noise." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-239378.
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The aim of this project was to create our own data set consisting of images of fruits and vegetables. A subset of the data set was composed of images where the fruits and vegetables were obscured by a plastic bag. We then evaluated the difficulty of this data set using a simple kernel machine algorithm. The performance drops considerably when introducing the above mentioned subset to the data set. The algorithm was to classify the different types of fruits and vegetables present in the data set. We also created the data set in different pixel dimensions, sufficiently reducing the computation time of the algorithm while not suffering a large drop in classification performance. This enables algorithms which complexity are highly dependent on input dimension size to use the data set. From our different experimental setups we were able to conclude that the machine outperforms humans on small input dimensions, given that the humans had no prior knowledge of the data set.
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Stegemann, Grischa. "Noise induced spatiotemporal dynamics in the double barrier resonant tunneling diode." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=98060169X.
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Karlin, Carl, and Desiré Åhström. "Ursäkta, vad sa du? : En studie om buller, dess påverkan på tredje man och möjliga åtgärder." Thesis, KTH, Byggteknik och design, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147250.
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Vid både ny- till- och ombyggnation sker ofta arbete tätt inpå redan befintlig bebyggelse. Då dessa innehåller både kontor, bostäder samt övriga verksamheter är risken stor att dessa påverkas negativt av buller från närliggande byggarbetsplatser. I dagsläget finns allmänna råd som Naturvårdsverket har tagit fram. I dessa går det att utläsa vilka ljudnivåer buller från byggarbetsplatser inte bör överstiga samt under vilka tider på dygnet dessa gäller. Det är viktigt att komma ihåg att allmänna råd inte är bindande utan endast riktvärden som i möjligaste mån bör följas. Tillsynsmyndigheten på Länsstyrelsen ansvarar för att dessa följs och tar beslut i samband med byggnation vilka bullernivåer som är lämpliga. Trots förekomsten av de allmänna råden uppkommer det i stor utsträckning tvister mellan den byggande parten och tredje man. Det behöver inte enbart handla om att råden inte efterföljs utan kan i fler fall bero på andra faktorer, till exempel att informationen om kommande störningar varit otydlig. Klagomål kan även förekomma då riktvärdena följs. Genom att diskutera bullerproblematiken med byggföretaget STRABAG Projektutveckling AB har kunskap om deras syn och erfarenhet av ämnet inhämtats. Företaget lägger stort fokus på att informera tredje man genom att skylta om kommande störningar. Enligt oss bör företaget dock arbeta mer med bland annat planering av avskärmningar mot omgivande bebyggelse. Hur bullerskärmar bör placeras i förhållande till omgivningen, hur de ska utformas och vilka områden som ska skyddas är viktiga frågor att ta upp redan under planering av projekt. Ytterligare information har inhämtats genom en enkätundersökning och intervjuer med Naturvårdsverket, kommuner och Tillsynsmyndigheten.Construction work is often performed in close contact to existing buildings such as offices, homes and stores. The people working and living in these buildings may thereby be affected negatively by the noise occurring from the construction site. There are guidelines compiled by Environmental Protection Agency regarding the level of noise that should not be exceeded. It’s important to remember that these guidelines are only guidelines and not binding values. “Tillsynsmyndigheten” at “Länsstyrelsen” is responsible for the adherence of the guidelines and make decisions related to which noise levels are appropriate at the construction site. Even though the existence of the guidelines there are times when the construction company can disturb the third party. This does not always have to do with the fact that the noise levels have been exceeded. It could also occur if the information about upcoming disturbances has been unclear. Complaints may also occur when the guidelines are followed. By interviewing representatives at STRABAG Projektutveckling AB about disturbance caused by noise we have received their opinions and experience in the matter. The company puts great effort to distribute the information about upcoming noise and posting it on billboards. By our opinion more effort should be added to planning upcoming projects and deciding what kind of protection should be used and the most efficient way of placing it due to its surroundings. These are questions that are to be decided in an early stage of the planning process. Additional information has been obtained through a questionnaire survey and interviews with Environmental Protection Agency, municipality and “Tillsynsmyndigheten”.
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Kantová, Radka. "SNIŽOVÁNÍ HODNOTY STAVENIŠTNÍHO HLUKU POMOCÍ MODELOVÁNÍ VÝROBNÍHO PROSTORU STAVBY A ÚPRAV TECHNOLOGICKÝCH POSTUPŮ PŘI VÝSTAVBĚ." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-392280.
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This doctoral thesis focuses on noise generated during construction. It defines the legislative and physical aspects of this topic. It determines heavy machinery as noise source and categorizes them by their usage in construction technologies. It collects source data of the machinery noises which can be further used in prognostic models. It analyses the level of construction noise which can impact the nearby residential areas and offers methodology for modelling and designing the possible arrangements for the noise reduction. It defines partial effects of the construction site which are significant for the noise spreading. It establishes their role in the value of acoustic pressure level of the noise affecting the façade of the considered building. With the data collection and with case study verification it offers a prepared work tool which can be easily used to predict noise levels on construction sites and can be applied in the early constructions preparations. The structure of this thesis is planned for possible usage as university textbook or study support.
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Lei, Lei. "Étude des matériaux poreux thermo compressés pour la modélisation des écrans acoustiques automobiles." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2428/document.
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Ce travail a été réalisé dans le cadre du projet EcOBEx, qui consiste à réduire le bruit du groupe motopropulseur rayonné à l'extérieur par l'ajout d'écrans acoustiques dans le compartiment moteur du véhicule. Les écrans acoustiques sont fabriqués par thermocompression de matériaux poreux uniformes. Les propriétés et l'épaisseur du matériau évoluent en fonction du degré de compression subit par le matériau. L'objectif de ce travail est de proposer des lois pour prédire l'évolution des propriétés des matériaux à partir du taux de compression et de leurs valeurs initiales avant compression. Dans un premier temps, on s'intéresse aux paramètres du modèle de fluide équivalent de Johnson-Champoux-Allard-Lafarge (JCAL) : porosité, résistivité au passage d'air, tortuosité, longueurs caractéristiques visqueuse et thermique, perméabilité thermique statique. Des expressions analytiques sont proposées pour prédire la variation de ces paramètres en fonction de la compression. Elles sont développées à partir d'un modèle de matériaux fibreux à fibres cylindriques où les variations d'orientation des fibres induites par la thermocompression peuvent être prises en compte. Les résultats sont en bon accord avec les mesures effectuées sur deux types de matériaux (mousse à cellules ouvertes et fibreux). Un modèle empirique généralisé est finalement proposé pour la résistivité au passage d'air. Dans un deuxième temps, on s'attache aux paramètres élastiques dont la connaissance est essentielle pour prendre en compte la vibration du squelette. La méthode expérimentale quasistatique est d'abord appliquée pour étudier l'évolution du module de Young par rapport au taux de compression pour les fibres et les mousses. Une loi de puissance est alors proposée pour prédire ces variations. Enfin, une méthode inverse pour estimer les propriétés élastiques d'un matériau poroélastique orthotrope à partir d'une mesure vibratoire d'un écran tricouche thermo comprimé est proposée. Cette méthode permet de caractériser les propriétés élastiques du matériau poreux dans une situation proche de son application réelleThis work was carried out in the framework of the project EcOBEx, whose main objective was to reduce the passby noise by mean of acoustic shields in the engine compartment of the vehicle. The acoustic shields are manufactured by thermocompression of uniform porous materials. The material’s properties and thickness evolve according to the degree of compression experienced by the material. The objective of this work is to propose some laws to predict the evolution of the materials properties from their initial non compressed values and the compression rate. Firstly, we focus on the parameters of the Johnson-Champoux-Allard-Lafarge (JCAL) equivalent fluid model : porosity, air-flow resistivity, tortuosity, viscous characteristic lengths, thermal characteristic length, static thermal permeability. Some analytical expressions are proposed to predict the variation of these parameters as a function of compression. They are derived from a physical model of cylindrical fibres where the fibre orientation variations induced by the thermocompression can be taken into account. The results are in good agreement with the measurements made two types of materials (open cell foam and fibrous). A generalized empirical model is finally proposed for the air-flow resistivity.In a second part, we focus on the elastic parameters, which are necessary to take into account the vibration of the skeleton. The quasi-static experimental method is first applied to study the evolution of the Young’s modulus along the compression rate for fibrous and open cell foams. A power law is then proposed to predict these variations. Finally, an inverse method for estimating the elastic properties of an orthotropic poro-elastic material from a vibratory measurement of a thermocompressed three layer sandwich structure is proposed. This method allows us to characterize the elastic properties of a porous material in a situation close to its actual application
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Djulstedt, Fredrik, and Diego Gronowski. "Standardisering av bullerskärm för järnväg : En undersökning för Peab och Trafikverket." Thesis, KTH, Byggteknik och design, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147184.
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I dagsläget dimensioneras bullerskärmar efter varje projekt med den enda gemensamma nämnaren att de skall uppfylla utformade riktlinjer och bullerkrav. De kan skilja sig enormt vad gäller estetisk utformning och konstruktion. Denna arbetsgång är både tids - och kostnadsineffektiv med konsekvenser som följd, framförallt då externa arkitekter anställs för att sätta sin egen prägel. Uppgiften har utdelats gemensamt utav Trafikverket och Peab som ser ett behov utav standardiserade bullerskärmar. Slutsatsen har dragits utav tidigare projekt och då framförallt projekt Mälarbanan. Denna rapport syftar till att, med utgångspunkt Mälarbanan, ta fram ett förslag till ett standardiserat system som skall kunna användas runt om i Sverige. Detta system, skall motverka dagens problematik med nuvarande bullerskärmar. Systemet kommer i texten att benämnas som Bsk 14F som står för Bullerskärm 14 Försök. Resultatet utav Bsk 14F kommer att redovisas med ljudmodelleringar i dataprogrammet INSUL som används i dagens utformningar. Ritningar i CAD kommer att påvisa Bsk 14Fs konstruktion och kalkylräkning för kostnaderna. Vi har även jämfört olika bullerskärmar som finns att tillgå på marknaden idag för att undersöka möjligheten att välja ett befintligt system. Med hjälp av en yrkesverksam akustiker, konstruktörer, platschefer och arbetsledare har vi kunnat erhålla underlag för att producera ett slutligt resultat. Här påvisas att med ett standardiserat system går det att uppnå ljudkraven som erfordras till ett lägre pris utan att behöva kompromissa utrymme för arkitektoniskt prägel.Ideally, the basic standard forms of how and why noise barriers are created are to fulfill the purpose of reducing sound. They vary greatly regarding their esthetics and design. Particular mechanics are both time and cost ineffective consequentially when external architects are contracted to put their trademark on them. Trafikverket and Peab, whom identify the need of standardizing noise barriers, have collaboratively delegated the assignment. The conclusion has been drawn from earlier projects and Project Mälarbanan. The premise of the report (having Mälarbanan as an example) is to offer a standardized system which would be used throughout Sweden. This system would, thus, counter the current problems with noise barriers that exist today. The system will be noted in the text as Bsk 14F, which stands for Bullerskärm 14 Försök (Noise Barrier 14 experimental). A computer sound-model program using today’s configurations will present the results of Bsk 14F, whereas drawings in CAD will show Bsk 14F’s design and calculation costs. A comparison has also been made to examine the possibility of choosing a noise barrier currently existing on the market today. With the help of effectively using a professional acoustician, engineers, site managers, and project leaders was it possible to obtain the core material to produce an ultimate and final result. The following demonstrates that establishing a standardized system, which fulfills the sound requirements and be constructed at a lower cost, is attainable without having to comprise the architectural trademark.
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García, Chocano Víctor Manuel. "New devices for noise control and acoustic cloaking." Doctoral thesis, Editorial Universitat Politècnica de València, 2015. http://hdl.handle.net/10251/53026.
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[EN] The aim of this work is to design new acoustic devices based on arrangements of scattering units. First, the use of sonic crystals as noise barriers for traffic noise control is comprehensively analyzed. Due to the limitations of the conventional structures based on rigid scatterers, the inclusion of absorbing elements is proposed. Two different types of absorbers are here considered: porous materials and microperforated plates. In the first case, the attenuation characteristics of barriers made with cylinders containing rubber crumb is analyzed. The second proposal is based on the construction of cylindrical microperforated shells. Analytical approaches modelling the behavior of the barriers have been developed in both cases. These models show a satisfactory agreement with the corresponding experimental realizations. Finally, it is performed an optimization process in order to obtain efficient sound barriers intended to attenuate traffic noise.
Another application considered in this work is the construction of cloaks to render objects acoustically invisible. In particular, cloaks made with rigid inclusions are designed to operate with airborne sound. The first proposal consists of a cloak that utilizes the temperature of the background to control the properties of the effective medium. In addition, two and three-dimensional cloaks have been developed through the scattering cancellation technique. These devices have been designed by means of an optimization procedure and their performance has been experimentally demonstrated.[ES] El objetivo de este trabajo es el diseño de nuevos dispositivos acústicos basados en disposiciones de centros de dispersión. En primer lugar, el uso de cristales sónicos como barreras acústicas para el control de ruido de tráfico es analizado en detalle. Debido a las limitaciones que presentan las estructuras convencionales basadas en centros de dispersión rígidos, se propone la inclusión de elementos absorbentes en los mismos. Se han considerado dos tipos distintos de absorbente: materiales porosos y placas microperforadas. En el primer caso se analizan las propiedades atenuadoras de barreras formadas por cilindros que contienen granza de caucho. La segunda solución se basa en la construcción de coronas microperforadas. En ambos casos se han desarrollado modelos analíticos que permiten determinar el comportamiento de las barreras. Dichos modelos muestran un acuerdo satisfactorio con las correspondientes realizaciones experimentales. Finalmente se ha realizado un proceso de optimización con objeto de obtener barreras eficientes para la atenuación de ruido de tráfico. Otra aplicación considerada en este trabajo es el desarrollo de dispositivos de invisibilidad acústica. Concretamente se pretenden diseñar mantos constituidos con elementos rígidos para ondas acústicas en aire. La primera propuesta consiste en un manto que utiliza la temperatura del medio externo para controlar sus propiedades efectivas. Además se han desarrollado mantos en dos y tres dimensiones a través de la técnica de cancelación de la dispersión. Los diseños han sido realizados por medio de un proceso de optimización y su funcionamiento ha sido demostrado experimentalmente.
[CAT] L'objectiu d'aquest treball és el disseny de nous dispositius acústics basats en disposicions de centres de dispersió. En primer lloc, l'ús de vidres sònics com barreres acústiques per al control de soroll de trànsit és analitzat en detall. A causa de les limitacions que presenten les estructures convencionals basades en centres de dispersió rígids, es proposa la inclusió d'elements absorbents en els mateixos. S'han considerat dos tipus diferents de absorbent: materials porosos i plaques microperforades. En el primer cas s'analitzen les propietats atenuadores de barreres formades per cilindres que contenen gransa de cautxú. La segona solució es basa en la construcció de corones microperforades. En tots dos casos s'han desenvolupat models analítics que permeten determinar el comportament de les barreres. Aquests models mostren un acord satisfactori amb les corresponents realitzacions experimentals. Finalment s'ha realitzat un procés d'optimització per tal d'obtenir barreres eficients per l'atenuació de soroll de trànsit. Una altra aplicació considerada en aquest treball és el desenvolupament de dispositius d'invisibilitat acústica. Concretament es pretenen dissenyar mantells constituïts amb elements rígids per ones acústiques en aire. La primera proposta consisteix en un mantell que utilitza la temperatura del medi extern per controlar les seves propietats efectives. A més s'han desenvolupat mantells en dues i tres dimensions a través de la tècnica de cancel·lació de la dispersió. Els dissenys han estat realitzats per mitjà d'un procés d'optimització i el seu funcionament ha estat demostrat experimentalment.
García Chocano, VM. (2015). New devices for noise control and acoustic cloaking [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/53026
TESIS
Premiado
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Ekici, Inan. "Road traffic noise barrier design : measurements and models concerning multiple-walls and augmented earth mounds." Thesis, Sheffield Hallam University, 2004. http://shura.shu.ac.uk/3189/.
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This research programme is concerned with the design of road traffic noise barriers, in particular, the use of multiple-walls on the ground and on top of earth mound type barriers. As part of this research, a comprehensive up-to-date review of the research carried out on noise barriers was undertaken. A number of areas requiring further research were identified. The discussion of these resulted in the proposal of a simplified noise barrier selection method which would be of use particularly to non-acousticians. This method indicated that acoustic information available for the design of earth mounds was limited, although this barrier type is commonly used in practice and is known to have a number of non-acoustic benefits. Initial investigations showed that the performance of an earth mound could be enhanced by the use of multiple-walls on its top. A detailed investigation was undertaken into the acoustic performance of multiple-walls both on the ground and on top of earth mounds. Both physical and numerical modelling techniques were used for this purpose. The physical scale modelling experiments were carried out both under uniform field conditions and in two different semi-anechoic chambers in the presence of a continuous noise source, using a model scale of 1: 10. The numerical modelling was applied using indirect boundary element method formulation. The commercial software named SYSNOISE was employed for the computations. It was found that numerical modelling results and the semi-anechoic chamber experiments generally agreed very well. The level of accuracy of the uniform field experiments depended on the choice of source and receiver locations as well as the size of the model geometry. This investigation resulted in acoustic advice on the use of multiple walls both on their own and on top of earth mounds. Under favourable conditions, the multiple-wall configurations were shown to provide substantial attenuations of up to 26dB. The physical parameters involved in their design and their noise attenuation mechanisms were identified. In addition to long-wave scattering and diffraction effects, it was identified that surface wave generation mechanisms and interference effects played a role in attenuating noise. The acoustic advice for the design of earth mounds was extended to the applications of single, double and multiple-walls on their top. This work also showed that uniform field conditions in conjunction with a continuous noise source could be used for physical modelling. It was found that for small-sized geometries good agreements were observed between physical modelling (both types) and numerical simulations. There were lesser agreements between the sets of data for larger geometries. The multiple-wall configurations investigated as part of this research programme could be used as noise mitigating measures in central reservations of dual carriageways. However, further research would be required into their acoustic performance and engineering design. The results obtained from this investigation have led to the identification of a number of research areas which could be undertaken in the future.
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Barbosa, Andre Luiz Souza. "Estudo de barreiras acústicas para a atenuação do ruído aeronáutico no Aeroporto de Congonhas em São Paulo." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/16/16134/tde-07032016-202246/.
Full textAbstract:
O aumento expressivo nos níveis de ruído, principalmente nas áreas urbanas próximas aos aeroportos, tem contribuído de forma preocupante para os já elevados e atuais níveis de poluição sonora registrados nos grandes centros urbanos. Além do fato dos incômodos e desconfortos no cotidiano das pessoas provocados por esse fato, as autoridades que tratam desse assunto alertam para os danos causados a saúde humana e dos seres vivos em geral. Alguns países europeus que estudam este assunto se dizem preocupados com os impactos negativos em suas economias na questão do desequilíbrio orçamentário no setor da saúde. A tese motivada pela utilização ampla de barreiras acústicas no setor de transporte rodoviário, ferroviário convencional e de alta velocidade, e, prioritariamente aéreo, pôde construir por intermédio desses contextos o conhecimento necessário e um cenário de expectativas promissoras com o objetivo de colaborar com a atenuação do ruído aeronáutico com uma proposta acadêmica de implantação de barreiras acústicas articuladas posicionadas nas cabeceiras da pista principal do Aeroporto de Congonhas em São Paulo no momento da decolagem, tendo como paradigma conceitual e operacional o uso similar dos defletores de energia que são utilizados nos conveses dos porta-aviões no momento das suas decolagens.The significant increase in noise levels, especially in urban areas close to airports, has contributed to the alarmingly high already and current noise pollution levels recorded in major urban centers. Besides the fact of annoyances and discomforts in the everyday life of people caused by this fact, the authorities dealing with this subject warn of the damage to human health and living creatures in general. Some European countries who study this issue claim to be concerned about negative impacts on their economies on the question of the budget imbalance in the health sector. Some European countries who study this issue claim to be concerned about negative impacts on their economies on the question of the budget imbalance in the health sector. The thesis motivated by wide use of noise barriers in the road transport sector, conventional and high-speed rail, and, as a matter of priority air could build through these contexts the knowledge necessary and a promising expectations scenario with the objective of collaborating with the aeronautical noise attenuation with an academic proposal to implement noise barriers at the headwaters of the track positioned hinged main from Congonhas Airport in Sao Paulo at the time of takeoff with the conceptual and operational paradigm using similar energy deflectors that are used on the decks of the carrier at the time of their landings.
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Bakar, Asra, and Georgi Mousi. "Solceller integrerade i anläggningskonstruktioner : En studie av hur solceller kan integreras i transportsektorns nyproduktion." Thesis, KTH, Byggteknik och design, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232126.
Full textAbstract:
Med ett alltmer miljömedvetet samhälle finner vi idag ett ökande intresse för tillämpningen av effektiva energiförsörjningssystem. Ett av tillvägagångssätten för detta är att utnyttja solenergi, vilket möjliggörs med solceller. Solceller kan kortfattat beskrivas som en komponent vilket syftar i att omvandla solenergi till elektricitet. Denna teknik har på senare år blivit ett incitament för byggherrar att uppnå kraven för diverse miljöcertifieringar, där solceller används som byggnadsmaterial vid nyproduktion och renoveringar. De konstruktioner där solceller har använts brukar gemensamt kallas för solcellsanläggningar, beroende på solcellstyp kan dessa delas in i byggnadsapplicerade (BAPV) och byggnadsintegrerade (BIPV). Med hjälp av litteraturstudier, fallstudier, intervjuer samt workshop och observationer har det utförts en undersökning med fokus på byggnadsintegrerade solceller (BIPV). Undersökningen verkställdes med avsikten att granska den potentiella utsträckningen som byggnadsintegrerade solceller kan implementeras inom transportsektorns nyproduktion. Avhandlingens huvudsakliga mål är att förse uppdragsgivaren med förslag på tillämpningsområden för byggnadsintegrerade solceller till nyproduktion, där eventuella hänsyn har tagits till byggteknik och arkitektur. Dessutom menar rapporten att bidra till bildningen av en uppfattning kring solceller som byggnadsmaterial. Resultatet som påvisades från undersökningen är att det finns möjligheter för BIPV att implementeras i anläggningskonstruktioner inom transportsektorn. Bland dessa konstruktioner är bullerskärmar och teknikhus för järnvägar. Dessutom konstateras att de byggtekniska faktorer som bör beaktas vid nyproduktion med BIPV är orientering och lutning, likaså skuggning och ventilation. För arkitektoniska faktorer gäller att konstruktionen är estetiskt tilltalande, har en god komposition med färg och material, passar det synliga rutnätets motiv, den är kontextualiserad och väl projekterad samt att den har en innovativ design. I avhandlingen framkommer även möjligheter och hinder vid projektering med solceller. Resultaten visar att möjligheterna för BIPV är förutom att den utgör ett byggnadsskal, så har den även en energiavkastning till skillnad från traditionella byggnadsmaterial. Dessutom är BIPV ett ekonomiskt och ekologiskt hållbart alternativ. De identifierade hindren relaterar till aktörers brist på kunskap i solcellstekniken, vilket försvårar deras arbeten. Studiens slutsats är att det finns en potential att implementera solcellstekniken i Sverige, dock är den mer lönsam för större anläggningskonstruktioner. Då bullerskärmar och teknikhus förekommer kontinuerligt längs svenska motor-och järnvägar ses detta som ett incitament till att integrera dessa med solceller. Slutsatsen är även att vissa hinder som uppstår vid produktion och underhåll kan undvikas redan vid projekteringsskedet.With a society that is becoming more environmentally conscious, we now find a growing interest in the application of efficient energy supply systems. One of the approaches for this is to utilize solar energy, which is possible with photovoltaics (PV) also known as solar cells. PV can briefly be described as a component which aims to convert solar energy into electricity. This technology has in recent years been an incentive for constructions companies and project owners to achieve the requirements for various environmental certifications. Photovoltaic technology can be used in building materials for new productions or renovations. Building structures where PV has been utilized are commonly referred to as solar systems. Depending on the solar cell type, these can be divided into building applied photovoltaics (BAPV) and building integrated photovoltaics (BIPV). With the help of literature research, interviews, case studies as well as workshop and observations, a study has been carried out which focuses on building integrated photovoltaic. The study was conducted with the intention to examine the potential extent that building integrated photovoltaics can be implemented in the transport sectors new production. The main aim of the dissertation is to provide with proposals for areas of application for BIPV, where construction technology and architecture is specifically taken into consideration. This dissertation also intends to contribute to the formation of an idea of photovoltaics as a building material. The result shown by the study is that there are opportunities for BIPV to be implemented in the transport sectors production of new constructions. Among these constructions are noise barriers and service houses for railways. In addition, it is noted that factors which regard PV building technology are orientation and tilt as well as shading and ventilation. The architectural factor that are considered when designing with BIPV is that the design of the construction needs to be aesthetically appealing, have a good composition with color and material, suitable with the visible grid's theme, it also needs to be contextualized and carefully planned. It is also required for BIPV constructions to have an innovative design. The dissertation also reveals possibilities and obstacles when designing with solar cells. The results show that the promises for BIPV come in the form of economic and ecological sustainability. The identified barriers relate to lack of knowledge in solar technology, which complicates the work of the involved operatives. The study's conclusion is that there is a potential for implementing PV technology in Sweden, but it is more profitable for larger constructions. However noise barriers and service houses for railways, occur continuously along Swedish roads and railways, therefore they are large in quantity. The large quantity of these constructions should be an incentive to implement BIPV in these constructions. In addition, it is stated that certain obstacles arising from production and maintenance can be avoided as early as in the design stage.
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Pregl, Sebastian. "Fabrication and characterization of a silicon nanowire based Schottky-barrier field effect transistor platform for functional electronics and biosensor applications." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-171112.
Full textAbstract:
This work focuses on the evaluation of the feasibility to employ silicon (Si) nanowire based parallel arrays of Schottky-barrier field effect transistors (SB-FETs) as transducers for potentiometric biosensors and their overall performance as building blocks for novel functional electronics. Nanowire parallel arrays of SB-FETs were produced and electrically characterized during this work. Nominally undoped Si nanowires with mean diameter of 20nm were synthesized by chemical vapor deposition (CVD) driven bottom-up growth and subsequently transferred via a printing process to Si/SiO2 chip substrates. Thereby, dense parallel aligned nanowire arrays are created. After dry oxidation of the nanowires, standard photolithography and deposition methods are employed to contact several hundred nanowires with interdigitated Ni electrodes in parallel. A silicidation step is used to produce axially intruded Ni-silicide (metallic) phases with a very abrupt interface to the Si (semiconducting) segment. Acting as front gate dielectric, the chip surface is entirely covered by an Al2O3 layer. For sensor applications, this layer further serves as electrical isolation of the electrodes and protects them from corrosion in electrolytes. Fabricated devices are part of the SOI (Si on insulator) transistor family with top (front) and back gate and exhibit ambipolar rectifying behavior. The top gate exhibits omega geometry with a 20nm thin Al2O3 dielectric, the back gate planar geometry with a 400nm thick SiO2 dielectric. The influence of both gates on the charge transport is summarized in the statistical analysis of transfer and output characteristic for 7 different lengths (for each 20 devices) of the Si conduction channel. A nonlinear scaling of on-currents and transconductance with channel length is revealed. Off-currents are influenced from both p- and n-type conduction at the same time. Increasing lateral electric fields (LEF) lead to a decline of suppression capability of both p- and n-currents by a single gate. This is reflected in a deteriorated swing and higher off-current towards decreasing channel lengths (increasing LEF). However, by individual gating of Schottky junction and channel, p- and n-type currents can be controlled individually. Both charge carrier types, p and n, can be suppressed efficiently at the same time leading to low off-currents and high on/off current ratio for all investigated channel lengths. This is achieved by a combined top and back double gate architecture, for which the back gate controls the Schottky junction resistance. It is demonstrated that a fixed high Schottky junction serial resistance, severely impairs the transconductance. However, the transconductance can be significantly increased by lowering this resistance via the back gate, enhancing the transducer performance significantly. Al2O3 covered SB-FETs were employed as pH sensors to evaluate their performance and signal to noise ratio (SNR). Current modulation per pH was observed to be directly proportional to the transconductance. The transistor related signal to noise ratio (SNR) is thus proportional to the transconductance to current noise ratio. Device noise was characterized and found to limit the SNR already below the peak transconductance regime. Statistical analysis showed that the nanowire SB-FET transconductance and noise both scale proportional with the current. Therefore, the SNR was found to be independent on the nanowire channel lengths under investigation. The high process yield of nanowire SB-FET parallel array fabrication close to hundred percent enables this platform to be used for simple logic and biosensor elements. Because of the low fabrication temperatures needed, the foundation is laid to produce complementary logic with undoped Si on flexible substrates. For previously reported results, the presence of Schottky junctions severely impaired the transconductance, restricting the applicability of SB-FETs as transducers. This work shows, that an electric decoupling of the Schottky junction can reduce these restrictions, making SB-FETs feasible for sensor applicationsDiese Dissertation ist der Bewertung von Silizium (Si) Nanodraht basierten Parallelschaltungen von Schottky-Barrieren-Feld-Effekt-Transistoren (SB-FETs) als Wandler für potentiometrische Biosensoren und deren generelle Leistungsfähigkeit als Bauelement neuartiger funktioneller Elektronik gewidmet. In dieser Arbeit wurden Parallelschaltungen von Nanodraht SB-FETs hergestellt und elektrisch charakterisiert. Nominell undotierte Si Nanodrähte mit durchschnittlichem Durchmesser von 20nm wurden mittels chemischer Dampfphasenabscheidung (CVD) synthetisiert und anschließend durch einen Druckprozess auf ein Si/SiO2 Chip-Substrat transferiert. Damit wurden dicht gepackte, parallel ausgerichtete Nanodraht Schichten erzeugt. Nach Trockenoxidation der Nanodrähte wurden diese mit Standard Lithographie und Abscheidungsmethoden mit interdigitalen Nickel (Ni) Elektroden als Parallelschaltung kontaktiert. Durch einen Temperprozess bilden sich axial eindiffundierte metallische Ni-Silizid-Phasen, mit einer sehr abrupten Grenzfläche zum halbleitenden Si Segments des Nanodrahts. Die Chipoberfläche wird vollständig mit einer Al2O3-Schicht bedeckt, welche als Frontgate-Dielektrikum oder als elektrische Isolation und Korrosionsschutzschicht für Elektroden in Elektrolytlösungen im Falle der Sensoranwendungen dient. Die hier gezeigten Bauelemente sind Teil der SOI (Si on insulator) Transistoren-Familie mit Top- (Front) und Backgate und zeigen ein ambipolares Schaltverhalten. Die Topgates besitzen eine Omega-Geometrie mit 20nm dickem Al2O3 Dielektrikum, das Backgate eine planare Geometrie mit 400nm dickem SiO2 Dielektrikum. Der Einfluss beider Gates auf den Ladungstransport ist in einer statistischen Analyse der Transfer- und Output-Charaktersitiken für 7 unterschiedliche Si-Leitungskanallängen zusammengefasst. Eine nichtlineare Skalierung von Strom und Transkonduktanz mit Leitungskanallänge wurde aufgedeckt. Die Ströme im Aus-Zustand des Transistors sind durch das Vorhandensein gleichzeitiger p- als auch n-Typ Leitung bestimmt. Die Zunahme lateraler elektrischer Felder (LEF) führt zu einem Verlust des gleichzeitigen Ausschaltvermögens von p- und n-Strömen bei Ansteuerung mit einem einzelnen Gate. Dies äußert sich durch einen graduell verschlechterten Swing und höheren Strom im Aus-Zustand bei verringerter Leitungskanallänge (gleichbedeutend mit erhöhten LEF). Durch eine getrennte Ansteuerung von Schottky-Kontakt und Leitungskanal lassen sich p- and n-Leitung jedoch unabhängig voneinander kontrollieren. Beide Ladungsträgertypen können so simultan effizient unterdrückt werden, was zu einem geringen Strom im Aus-Zustand und einem hohen An/Aus- Stromverhältnis für alle untersuchten Kanallängen führt. Dies wird durch eine Gatearchitektur mit kombiniertem Top- und Backgate erreicht, bei der das Backgate den Ladungstransport durch den Schottky-Kontakt und dessen Serienwiderstand kontrolliert. Es wird gezeigt, dass ein konstant hoher Schottky-Kontakt bedingter Serienwiderstand die Transkonduktanz erheblich vermindert. Jedoch kann die Transkonduktanz im höchsten Maße durch eine Herabsetzung des Serienwiderstandes durch das Backgate gesteigert werden. Dies erhöht die Leistungsfähigkeit des SB-FET als Wandler deutlich. Al2O3 oberflächenbeschichtete SB-FETs wurden als pH-Sensoren erprobt, um deren Tauglichkeit und Signal-zu-Rausch-Verhältnis (SNR) zu evaluieren. Die Strommodulation pro pH-Wert konnte als direkt proportional zur Transkonduktanz bestätigt werden. Das Transistor bedingte SNR ist daher proportional zum Verhältnis von Transkonduktanz und Stromrauschen. Bei der Analyse des Transistorrauschens wurde festgestellt, dass dieses das SNR bereits bei einer niedrigeren Transkonduktanz als der maximal Möglichen limitiert. Eine statistische Auswertung zeigte, dass sowohl SB-FET Transkonduktanz als auch Stromrauschen proportional zu dem Transistorstrom skalieren. Somit ist deren Verhältnis unabhängig von der Nanodraht-Leitungskanallänge, im hier untersuchten Rahmen. Die geringe Ausschuss bei der Fabrikation der Nanodraht SB-FET-Parallelschaltungen ermöglicht eine Nutzung dieser Plattform für simple Logik und Biosensorelemente. Durch die geringen Prozesstemperaturen wurde die Grundlage geschaffen, komplementäre Logik mit undotiertem Si auf flexiblen Substraten zu fertigen. Vorangegangene Resultate zeigte eine verminderte Transkonduktanz durch die Präsenz von Schottky-Barrieren, was die Anwendbarkeit von SB-FETs als Wandler einschränkt. Diese Arbeit zeigt, dass eine elekrtische Entkopplung der Schottky-Kontakte zu einer Aufhebung dieser Beschränkung führen kann und somit den Einsatz von SB-FETs als praktikable Wandler für Sensoranwendungen zulässt
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Gonçalves, Vanessa Santos Silva. "Overcoming Central Nervous System-barriers by the development of hybrid structured systems for nose-to-brain drug delivery using clean technologies." Doctoral thesis, Universidade Nova de Lisboa, Instituto de Tecnologia Química e Biológica António Xavier, 2016. http://hdl.handle.net/10362/56395.
Full textAbstract:
The effective delivery of therapeutics into the brain is challenging since drugs or drug delivery systems (DDS) candidates are not able to cross the blood-brain barrier (BBB), making the development of new drugs alone not enough to ensure progresses in Central Nervous System (CNS) drug therapy. Due to several problems related with other routes of brain drug administration, the interest has increased towards exploring the possibility of intranasal administration. The nose-to-brain transport and the therapeutic viability of this route have been investigated for rapid and effective transport of drugs to CNS, but the development of nasal drug products for brain targeting is still faced with many challenges.(...)info:eu-repo/semantics/publishedVersion