Analysis of the acoustic characteristics and optimization potential of road surfaces - One focus within the project "Quiet Road Traffic 3"

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

On the sound radiation of a rolling tyre

The sound radiation from rolling tyres is still not very well understood. Although details such as horn effect or directivity during rolling have been investigated, it is not clear which vibrational modes of the tyre structure are responsible for the radiated sound power. In this work an advanced tyre model based on Wave Guide Finite Elements is used in connection with a contact model validated in previous work. With these tools the tyre vibrations during rolling on an ISO surface are simulated. Starting from the calculated contact forces in time the amplitudes of the modes excited during rolling are determined as function of frequency. A boundary element model also validated in previous work is applied to predict the sound pressure level on a reference surface around a tyre placed on rigid ground as function of the modal composition of the tyre vibrations. Taking into account different modes when calculating the vibrational field as input into the boundary element calculations, it is possible to identify individual modes or groups of modes of special relevance for the radiated sound power. The results show that mainly low-order modes with relative low amplitudes but high radiation efficiency in the frequency range around 1 kHz are responsible for the radiated sound power at these frequencies, while those modes which are most strongly excited in that frequency range during rolling are irrelevant for the radiated sound power. This fact is very essential when focusing on the design of quieter tyres

Analysis of the acoustic characteristics and optimization potential of road surfaces - One focus within the project "Quiet Road Traffic 3"

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

Investigating generation mechanisms of tyre/road noise by speed exponent analysis

The purpose of this study is to clarify the influence of air-pumping related noise sources on typical tyre/road noise. The aim is to increase the understanding of noise generation mechanisms and catalyse the development of existing tyre/road noise simulation tools. The speed dependency of measured and simulated tyre/road noise is analysed and the results show that a large part of the noise can be explained by a high speed exponent traditionally connected with air-pumping mechanisms. Surprisingly, this is also the case for rough road surfaces which are expected to mainly generate noise by tyre vibrations. It is also found that vehicle wind noise may have a strong influence on the pass-by noise and care must be taken when analysing measurement data of quiet tyre/road combinations. Even simulated tyre/road noise shows higher speed exponents than what is anticipated without the inclusion of any type of air-pumping mechanism in the model. It is concluded that it is unfeasible to separate noise created by tyre vibrations from noise created by air-pumping with a speed exponent analysis due to the overlap in the speed exponents connected with the different generation mechanisms

Generation of a human induced pluripotent stem cell line (HMGUi002-A) from a healthy male individual.

Induced pluripotent stem cells (iPSCs) can be used to generate different somatic cell types in vitro, including insulin-producing pancreatic beta-cells. Here, we have generated iPSCs from a healthy male individual using an episomal reprogramming method. The resulting iPSCs are integration-free, have a normal karyotype and are pluripotent in vitro and in vivo. Furthermore, we show that this iPSC line can be differentiated into pancreatic lineage cells. Taken together, this iPSC line will be useful to test differentiation protocols towards beta-cell as well as other cell types and will also serve as a control for drug development and disease modelling studies

Einfluss der Fahrbahntextur auf das Reifen-Fahrbahn-Geraeusch

SIGLEAvailable from TIB Hannover: ZA 4681(847)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman