| 1. |
- Amiryarahmadi, Nata, 1982, et al.
(författare)
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Time-domain model of a tapping machine
- 2011
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Ingår i: Proceedings - 6th Forum Acusticum 2011, Aalborg, 27 June - 1 July 2011. - 2221-3767. ; , s. 1713-1718
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Konferensbidrag (refereegranskat)abstract
- In the past few years the use of lightweight buildings made of prefabricated wooden elements has become more common. Ease of installation, high accuracy and lightness of such buildings has attracted builders and designers. Sweden, having a large coverage of renewable forests has an increasing interest in multi-storey wooden buildings. However noise and vibration in wooden buildings is an issue of concern especially low frequency impact sound due to footsteps. Impact sound insulation of floors can be measured based on ISO 140-7 using standardized tapping machine as excitation source. Experience has shown that in many cases the results obtained by this method do not correlate with annoyance experienced by inhabitants. On the other hand, the method presented in ISO 140-7 has usually shown to be relevant for the evaluation of impact sound transmission of concrete floors. Discovering the source of this contradiction requires deeper understanding of the impact process. A first step would be to find the difference between contact forces of the tapping machine on different floor materials. One could then correlate it with inhabitants’ perceived annoyance. This paper is the first step of this investigation which is a part of a Swedish research project called AkuLite. In this work a time-dependent model based on Hertz’s contact law is presented for the tapping machine. The model is validated by measurements on a homogeneous concrete floor. Also the contribution of parameters such as damping and stiffness of floor material on the resulting impact force and vibrations is studied.
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| 2. |
- Andersson, Patrik, 1974, et al.
(författare)
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Numerical Modelling of Tyre/Road Interaction
- 2012
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Ingår i: Scientific Bulletin, Automotive Series. - 1453-1100. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- From November 2012 all passenger car tyres, light truck tyres and heavy duty vehicle tyres sold on the aftermarket in the European Union must have a label classifying the external rolling noise, the fuel efficiency, and the wet grip. This regulation puts a focus on optimisation of the tyre design with respect to all these parameters at once. Up to today these three parameters have been treated rather independently. There is little to no detailed information available on the relationship between rolling noise generation, rolling resistance, and grip of car tyres besides empirical data based on measurements. Today, simulation models that can simulate all these effects at once have just started to emerge. This paper gives a brief presentation of the past and the most resent development of numerical tyre/road interaction models with focus on external noise, rolling resistance, and grip. Today, the simulation models can be used to gain fundamental knowledge about the tyre/road interaction process and the resulting noise, rolling resistance, and grip. Models for combined optimisation of rolling resistance and noise emissions exists, and are just about to be used in preliminary investigations. Models that in addition give results for grip are still under development.
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| 3. |
- Andersson, Patrik, 1974, et al.
(författare)
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Numerical Modelling of Tyre/Road Interaction
- 2011
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Ingår i: Exploratory Workshop: Modern Methods of Vibro-Acoustic Studies With Automotive Applications, University of Pitesti, Romania, November 24-25, 2011.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- From November 2012 all passenger car tyres, light truck tyres and heavy duty vehicle tyres sold on the aftermarket in the European Union must have a label classifying the external rolling noise, the fuel efficiency, and the wet grip. This regulation puts a focus on optimisation of the tyre de- sign with respect to all these parameters at once. Up to today these three parameters have been treated rather independently. There is little to no detailed information available on the relationship between rolling noise generation, rolling resistance, and grip of car tyres besides empirical data based on measurements. Today, simulation models that can simulate all these effects at once have just started to emerge. This paper gives a brief presentation of the past and the most resent develop- ment of numerical tyre/road interaction models with focus on external noise, rolling resistance, and grip. Today, the simulation models can be used to gain fundamental knowledge about the tyre/road interaction process and the resulting noise, rolling resistance, and grip. Models for combined opti- misation of rolling resistance and noise emissions exists, and are just about to be used in preliminary investigations. Models that in addition give results for grip are still under development.
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| 4. |
- Beckenbauer, Thomas, et al.
(författare)
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A mixed physical and statistical approach for the prediction of tyre/road noise
- 2013
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Ingår i: Proceedings of AIA-DAGA 2013 Conference on Acoustics, Meran, Italy, March 18-21, 2013.
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Konferensbidrag (refereegranskat)abstract
- The hybrid approach is intended to make a tool available for both analysis of tyre/road noise depending on road surface characteristics and synthesis of low noise road surfaces. However, the model does not claim applicability for the development of low noise tyres. Basic physical models for the calculation of non linear contact forces and tyre vibrations as well as an empirical model for the aerodynamic tyre/road noise generation have been implemented in order to feed a multiple regression model with problem specific input quantities. The model is able to predict absolute coast-by noise levels in terms of third octave bands between 315 Hz and 2 kHz within a wide speed range from 50 km/h up to 120 km/h separately for different noise generation mechanisms. Despite the fact that the model does not perform better than +/- 1 dB concerning the difference between calculated and measured overall noise levels and +/- 5 dB for spectral level differences it provides relevant information on the distribution of sound energy due to mechanical and aerodynamic processes within the tyre/road contact. This affords opportunity to characterize and develop road surfaces yielding reduced excitation of rolling noise which is presented by means of practically relevant examples.
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| 5. |
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| 6. |
- Bein, Thilo, et al.
(författare)
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Integrated Solutions for Noise & Vibration Control in Vehicles
- 2012
-
Ingår i: Procedia - Social and Behavioral Sciences. - : Elsevier BV. - 1877-0428. ; 48, s. 919-931
-
Tidskriftsartikel (refereegranskat)abstract
- A strong issue on the development of new vehicles is the weight reduction, required for the reduction of the fuel consumption and the CO2 emissions. The current vehicles have already a structure optimised to have low weight without reducing the required performances. However, there are some components of the structure that can be further reduced in weight still matching the resistance, crash and fatigue performances, but giving a poor performance in terms of noise and vibrations and increasing both the structure-borne and air-borne sound transmission.In the European FP7 project Green City Car, flexible, integrated passive and active solutions are developed permitting noise and vibration attenuation in vehicles equipped with the next generation of highly fuel-efficient two- or three cylinder internal combustion engines (ICE). Among others, shunted piezoelectric patches and electro-magnetic actuation as well as smart Helmholtz resonators are considered. Additionally, dedicated active noise control systems for the control of broadband rolling noise are developed. Besides, Green City Car addresses and implements novel damping materials and acoustic treatments as well as design approaches for tyres which are an important acoustic source for exterior and interior noise. This holistic approach should lead to a reduction in noise and vibrations levels in the order of 10 dB(A) and more measurable in the city car provided (not on component level). Currently, Green City Car finished its second year and first results are presented and discussed in this paper.
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| 7. |
- Buckers, C., et al.
(författare)
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Analysis of the acoustic characteristics and optimization potential of road surfaces - One focus within the project "Quiet Road Traffic 3"
- 2012
-
Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012; New York, NY; United States; 19 August 2012 through 22 August 2012. - 9781627485609
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Konferensbidrag (refereegranskat)abstract
- The development of silent road surfaces demands a detailed analysis of the tire/road interaction mechanisms basically determining the noise radiation of flowing traffic. Such an analysis is of significant importance to identify and characterize the relevant effects which affect the acoustic properties of the pavements. This paper reviews the approaches pursued within the interdisciplinary research project "Quiet Road Traffic 3" including an adequate expansion of the SPERoN model for the quantitative prediction of the tire/road noise. A variety of novel materials and road constructions is investigated to validate the model, to design optimized pavements, and to explore their application potential. The practical use of the results will be finally checked by implementing and monitoring test tracks. The research activities cover asphalt as well as concrete construction techniques and focus in particular on measures to reduce the noise nuisance in agglomerations. In total, the approaches within the project "Quiet Road Traffic 3" are intended to lower the road traffic noise level by 4 to 6 dB(A) as compared to the current state of the art.
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| 8. |
- Estévez Mauriz, Laura, 1982, et al.
(författare)
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Incorporation of the quiet side in noise maps
- 2014
-
Ingår i: TECNIACUSTICA 2014. 45st SPANISH CONGRESS ON ACOUSTICS. 8 th IBERIAN CONGRESS ON ACOUSTICS. EUROPEAN SYMPOSIUM ON SMART CITIES AND ENVIRONMENTAL ACOUSTICS. - 2340-7441. - 9788487985256 ; , s. 123-130
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Konferensbidrag (refereegranskat)abstract
- Nowadays noise maps are focused on the noise level at the most exposed façade, leading to underestimations on the shielded areas. Previous research showed that quiet areas have positive effects for the inhabitants' quality of life. To solve this problem, an engineering method was developed within the QSIDE project. This method aims to improve noise maps in terms of multiple reflections in an efficient way. Two different terms, attenuation due to the barrier and the canyon will be incorporated. In this paper, the suggested model from QSIDE has been further developed for its inclusion in noise map calculations.
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| 9. |
- Forssén, Jens, 1968, et al.
(författare)
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Introduction to traffic noise abatement
- 2014
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Ingår i: Environmental Methods for Transport Noise Reduction. - : CRC Press. ; , s. 1-18
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Presents Evidence-Based Guidance on Noise Abatement Methods Solutions for reducing the noise impact of road and rail traffic can be found in the use of natural elements in combination with artificial elements in urban and rural environments. Ground and road surface treatments; trees, forests, and tall vegetation; and the greening of buildings and other surfaces can contribute to powerful and cost-effective noise reduction. Environmental Methods for Transport Noise Reduction presents the main findings of the Holistic and Sustainable Abatement of Noise by optimized combinations of Natural and Artificial means (HOSANNA) research project. This project involved experts from seven countries, and assessed noise reduction in terms of sound level reductions, perceptual effects, and cost–benefit analysis. It considered a number of green abatement strategies, and aimed to develop a toolbox for reducing road and rail traffic noise in outdoor environments. Combines Theory with Practice Broad in both theory and application and based on leading-edge research, the book brings together the findings and their practical use. It details assessment methods for perceived noise, and outlines noise prediction methods that can be integrated with noise mapping software. It also explores the economic benefits and positive effects on urban air quality and CO2 levels. The material is this book: Includes up-to-date results on noise mitigation using vegetation and ground treatments Contains relevant results on innovative noise barrier designs Presents data on acoustic performance of vegetation and soil substratum Provides perceptual and cost–benefit analyses of noise mitigation methods Environmental Methods for Transport Noise Reduction is a helpful guide for noise consultants, city planners, architects, landscape architects, and researchers.
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| 10. |
- Forssén, Jens, 1968, et al.
(författare)
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Modelling the interior sound field of a railway vehicle using statistical energy analysis
- 2012
-
Ingår i: Applied Acoustics. - : Elsevier BV. - 0003-682X .- 1872-910X. ; 73:4, s. 307-311
-
Tidskriftsartikel (refereegranskat)abstract
- The sound field in train compartments, treated as a series of connected air cavities, is modelled using statistical energy analysis, SEA. For the case under study, with five cavities in series and the source in the second cavity, a closed-form solution is obtained. An adjusted SEA model is used to predict the rate of spatial decay within a cavity. The SEA model is validated using results from a ray tracing method and from scale model measurements. For the octave bands 500-4000 Hz, good agreement is shown between the results from measurements, the ray tracing and the SEA model, for the two saloons closest to the source cavity (a vestibule). The SEA model was shown to slightly underestimate the rate of spatial decay within a cavity. It is concluded that a reasonable cause is the additional diffusion due to the seating.
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| 11. |
- Hoever, Carsten, 1979, et al.
(författare)
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A comparison between Finite Element and Waveguide Finite Element Methods for the simulation of tire/road interaction
- 2013
-
Ingår i: Chalmers Library Link Resolver(opens in a new window) 42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013: Noise Control for Quality of Life. ; 1, s. 127-136
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Konferensbidrag (refereegranskat)abstract
- Due to increasing road utilization and tightening regulations, an increasing effort is made by the tire and automotive industries for accurate modeling of tire/road noise. It is well known that finite element (FE) based methods describing the vibration response of a rolling tire are computationally expensive while analytical models do not offer the necessary accuracy in the structural description of the tire. The recently proposed waveguide finite element (WFE) method combines the detailed description of a discretized tire cross section with a computationally efficient wave approach in the circumferential direction. The method has been successfully applied for tire dynamics and rolling noise simulations. An important aspect for the modeling of rolling noise is an accurate description of the road induced excitation. Both the high frequency vibration field and the lower frequency or quasi-static contact area need to be accurately captured. In this work we compare FE and WFE models of a tire in terms of traditional NVH properties such as mobility and modal frequencies, and in term of contact behavior such as footprint shape and structural stiffness. This way the potential of the WFE method for the modeling of both the excitation and the response of a rolling tire is critically examined.
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| 12. |
- Hoever, Carsten, 1979, et al.
(författare)
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A Simulation-Based Parameter Study of Car Tyre Rolling Losses and Sound Generation
- 2012
-
Ingår i: Proceedings - 9th European Conference on Noise Control, EURONOISE 2012, Prague, 10-13 June 2012. - 2226-5147. - 9788001050132 ; , s. 926-931
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Konferensbidrag (refereegranskat)abstract
- Due to legislative changes within the EU there is an increased demand for improvements in car tyre rolling resistance and noise generation. Apart from measurement data, however, information about the relationship between rolling resistance and rolling noise generation is scarce. It is the goal of this study to investigate the fundamental physical processes connecting both areas. Additionally, it is evaluated whether a simultaneous reduction of both rolling resistance and rolling noise is possible or if this is contradicting requirement. A previously presented model for simulating the structural dynamics and rolling resistance of a rolling car tyre is extended to allow rolling noise calculation. The approach is based on a waveguide finite element model of the tyre. Tyre/road contact forces are obtained using a non-linear 3D contact model. The velocity field on the tyre surface is used to determine the radiated sound pressure based on a boundary element method. In a parameter study it is evaluated how much dissipation and sound radiation are affected by material properties, tyre construction and road surfaces. Due to the characteristics of the modelling approach, detailed information about dissipation and sound generation in different frequency regions, wave orders or parts of the tyre is available. The results show that rolling resistance and radiation are mainly low wave order, low frequency phenomena which are, at least partly, controlled by the same set of modes. This suggests that by modifying specific tyre properties reductions in both sound radiation and rolling resistance can be achieved.
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| 13. |
- Hoever, Carsten, 1979, et al.
(författare)
-
Investigation of stress-distribution in a car tyre with regards to rolling resistance
- 2010
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Ingår i: Proceedings of ISMA2010 International Conference on Noise and Vibration Engineering including USD2010, Leuven, 20-22 September 2010. - 9789073802872 ; , s. 3977-3990
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Konferensbidrag (refereegranskat)abstract
- In recent years the method of waveguide finite element modelling has emerged as a suitable tool for the simulation of the structural behaviour of tyres. It combines cross-sectional finite element modelling with classical wave propagation methods along the waveguide. Compared to traditional finite element methods it is numerically much more efficient and provides greater physical insights into the vibrational behaviour. In an ongoing project an existing waveguide finite element model for the calculation of stationary (non-rolling) tyre vibrations is extended to allow for calculation of the stress distributions inside a rolling tyre being in contact with the ground. The results are used to identify local areas of high stress, which are not only important from a structural point of view but which can also be associated with high energy losses due to dissipation, hence affecting the overall rolling resistance of the tyre. The procedure and preliminary results will be presented.
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| 14. |
- Hoever, Carsten, 1979, et al.
(författare)
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Numerische Simulation von Rollgeräusch und Rollwiderstand von LKW-Antriebsachsenreifen
- 2014
-
Ingår i: DAGA 2014, Fortschritte der Akustik, 40. Deutsche Jahrestagung für Akustik, 10.--13. März 2014, Oldenburg. - 9783939296065 ; , s. 108--109-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Bei LKWs wird im Allgemeinen zwischen Lenk-, Antrieb- und Zusatzachsen unterschieden. Die eingesetzten Reifen sind dabei im Gegensatz zu PKWs für die spezifischen Bedingungen an der jeweiligen Achse z.B. hinsichtlich Traktion, Abrieb, Sicherheit oder Wirtschaftlichkeit optimiert. Speziell im Regionalverkehr werden dabei aufgrund häufiger Beschleunigungs-/Bremsvorgänge und Kurvenfahrten an den Antriebsachsen Reifen mit ausgeprägtem Blockprofil verwendet. Die resultierende starke Schwingungsanregung führt selbst auf eigentlich geräuscharmen Straßenoberflächen unmittelbar zu einer erhöhten Geräuschemission.Aus diesem Grund ist die Entwicklung eines geräuscharmen Antriebsachsenreifens für den LKW-Regionalverkehr eines der Ziele des Verbundsprojektes "Leiser Stranßenverkehr 3" (LeiStra3). Zur Unterstützung dieses Vorhabens wurde ein existierendes numerisches Modell zur Berechnung von Reifen-/Fahrbahninteraktion, Rollgeräusch und Rollwiderstand für PKW-Reifen an die speziellen Erfordernisse der Simulation von LKW-Antriebsachsenreifen angepasst. Besonderer Augenmerk wurde dabei auf eine effiziente Abbildung des Querprofils und der resultierenden Reifenanregung gelegt. Neben der Geräuschemission wird als eine wichtige Kenngröße der Wirtschaftlichkeit auch der Rollwiderstand betrachtet um einen möglichen Zielkonflikt frühzeitig zu erkennen.
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| 15. |
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| 16. |
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| 17. |
- Hoever, Carsten, 1979, et al.
(författare)
-
The influence of lateral road surface resolution on the simulation of car tyre rolling losses and rolling noise
- 2013
-
Ingår i: Chalmers Library Link Resolver(opens in a new window) 42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013: Noise Control for Quality of Life.
-
Konferensbidrag (refereegranskat)abstract
- CO2 emissions and traffic noise are two major environmental issues associated with road traffic. Increased efforts are made to develop suitable simulation tools for the prediction of tyre rolling losses and rolling noise. The accurate description of the tyre/road interaction under rolling conditions is crucial for these simulations. Besides an accurate contact model, input data of sufficiently high quality is required. Ac- cordingly, the measurement effort for the road roughness profiles is high: in the rolling direction distances of several meters need to be scanned at positions less than a millimetre apart. While in the lateral direction a lower resolution can be accepted, still between ten and twenty parallel profile tracks are required under perfect conditions. Yet, in reality road surface scans are typically restricted to very few lateral tracks due to limited resources. This study evaluates how rolling resistance and rolling noise simulations are affected if the number of independent lateral road scans is less than the number of lateral tracks in the contact model. Different schemes for extrapolating the missing lateral information from the available data are tested for several tyre/road combinations. It is shown that a certain number of parallel road surface scans is necessary for accurate prediction of rolling noise and rolling resistance.
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| 18. |
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| 19. |
- Hoever, Carsten, 1979, et al.
(författare)
-
Waveguide-Finite-Element based parameter study of car tyre rolling losses
- 2011
-
Ingår i: Proceedings - 6th Forum Acusticum 2011, Aalborg, 27 June - 1 July 2011. - 2221-3767. - 9788469415207 ; , s. 789-794
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Konferensbidrag (refereegranskat)abstract
- Low rolling resistance and a low noise level are two characteristics of a car tyre which are often seen as conflicting with each other. Simultaneously, there is an increased demand for improvement in both fields due to legislative changes. Due to the fact that there is little to no detailed information available on the relation between rolling resistance and acoustical behaviour of car tyres, an in-depth investigation of this subject seems to be desirable. In a first step, a Waveguide-Finite-Element-Model (WFEM) of a car tyre is combined with a non-linear 3D contact model to calculate the resulting contact forces between tyre and road surface. This can be used to make a detailed prediction of the tyre vibrations. For steady state rolling the input power into the tyre at the tyre-road interface gives the rolling resistance in terms of dissipated power. This includes detailed information on frequency and wave order distribution of dissipation. Using a parameter study, it is evaluated how the rolling resistance is affected by material properties or the tyre design.
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| 20. |
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| 21. |
- Hoffmann, Alice, 1983, et al.
(författare)
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Auralization of tyre/road noise based on the SPERoN prediction tool
- 2013
-
Ingår i: Proceedings of AIA-DAGA 2013 Conference on Acoustics, Meran, Italy, March 18-21, 2013. - 9783939296058 ; , s. 114-117
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Konferensbidrag (refereegranskat)abstract
- The SPERoN prediction tool allows to simulate pass-by spectra for different tyre/road combinations. The goal of this work is to use such a prediction for auralising pass-by sounds, which later on can be used in listening tests. For this a previously developed methodology is applied where recorded sounds of pass-by situations have been recorded monaurally. The recoded signals are then converted to a source signal for the engine and the tyre/road interaction. By this it is possible to shape the tyre/road source term by calculated spectra and synthesize the signal again to a pass-by signal. With the help of psychoacoustic judgments, the modelled signals were compared with recorded signals on a test field with the same tires, roads and distances in order to see how well the auralised signal matches the real signals in perception.
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| 22. |
- Hoffmann, Alice, 1983, et al.
(författare)
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Optimierung der Auralisierung von Reifengeraeuschen basierend auf dem Modellierungs-Tool SPERoN
- 2014
-
Ingår i: Akustik und Audiologie - "Hören für alle"; DAGA 2014, 40. Jahrestagung für Akustik "Fortschritte der Akustik", 10. - 13. März 2014, Oldenburg, Germany. - 9783939296065 ; 40, s. 178-179
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Konferensbidrag (refereegranskat)abstract
- Die Auralisierung von in SPERoN modellierten Reifengeräuschen wurde in vorhergehenden Beiträgen diskutiert. Die auralisierten Reifengeräusche wurden in der psychoakustischen Untersuchung ähnlich den entsprechenden Aufnahmen bewertet. Bei einer Frequenzanalyse der Reifengeräusche wurde festgestellt, dass die größten Unterschiede bei Frequenzen unter 315 Hz liegen, welche im SPERoN Modell nicht berücksichtigt sind. In dieser Arbeit wird die Hypothese aufgestellt, dass ein Teil der Unterschiede in der Wahrnehmung in der Diskrepanz der Signale für tiefe Frequenzen liegt.Um diese Hypothese zu untersuchen werden die Signale aus der SPERoN-Datenbank für Frequenzbänder unter 315 Hz vor der Auralisierung korrigiert. Die Anpassungswerte wurden im Vergleich zwischen auralisierten Signalen und entsprechenden aufgenommenen Signalen ermittelt.Die so erzeugten auralisierten Vorbeifahrten wurden im Hörversuch zusammmen mit entsprechenden aufgenommenen Vorbeifahrten bewertet.Dabei wurden sowohl die simulierten als auch die aufgenommenen Signale den Probanden vorgespielt. Die Probanden sollten die Geräusche auf einer Skala von 1 bis 7 für Angenehmheit, Lautheit, Rauhigkeit und Schärfe bewerten.Für die Attribute ''Angenehmheit'', ''Lautheit'' und ''Rauhigkeit'' konnte eine Verbesserung der Bewertung durch Berücksichtigung der Frequenzen unter 315 Hz erreicht werden. Für die ''Schärfe'' konnte keine Verbesserung erreicht werden.
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| 23. |
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| 24. |
- Kihlman, Tor, 1934, et al.
(författare)
-
Quieter cities of the future
- 2014
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The health effects of road traffic noise in cities are severe and constitute a threat to public health. Immission goals in the form of guideline values were formulated in many countries in the 1960s. The guidelines have remained rather unchanged but often been much exceeded in practice. Now, the scientific basis for health-based targets has become strong. A one-day forum was held in Innsbruck in September 2013. Its purpose was to clarify the effectiveness of present methods and policies. The forum was unique in bringing together noise control experts covering the whole chain from source to receiver including the health effects of the resulting immissions. There is no single technological fix available to decrease the adverse health effects. The road traffic noise problems cannot get reasonable solutions only through emission reductions even with foreseeable best technology. Present methods to measure and describe the emissions are neither sufficient nor adequate. Conclusions were drawn on what is needed and what can and should be done in terms of policy to substantially reduce the adverse health effects of traffic noise. A concerted action by several involved bodies is needed.
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| 25. |
- Kleiven, Stig, 1979, et al.
(författare)
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Improving efficiency of thermoacoustic refrigerators by a secondary source
- 2010
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Ingår i: 17th International Congress on Sound and Vibration 2010, ICSV 2010, Cairo, 18 - 22 July 2010. - 9781617822551 ; 3, s. 2348-2355
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Konferensbidrag (refereegranskat)abstract
- Improving efficiency and/or power are of key interest for heating and cooling devices, in particular thermoacoustic devices. Usually, thermoacoustic devices have a primary source attached opposite to the hard end termination of the resonator. The primary aim of this paper has been to investigate the potential of improving thermoacoustic devices by adding a secondary source replacing the hard end of the resonator. Using the secondary source the boundary conditions can be tuned arbitrarily. One specific case using a secondary source was studied closer: adapting the virtual length of the resonator together with the driving frequency. This case was investigated using simulations and parameter studies. The simulations were carried out using the time-domain model presented in a previous paper by the authors. Improvement in both efficiency and power were achieved by tuning the virtual length together with driving frequency. Moreover, these parameters may be tuned in real-time in an active control system using a secondary source.
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