Volume 2 Issue 5
Authors: Matthew Morris; Niranjan Humbad
Abstract: Automotive vehicles use aspirators to sense in-car temperature for controlling thermal comfort. The aspirator noise at the sensor end located on dash can be unacceptable and therefore an additional muffler is used between the sensor and the aspirator. An innovative aspirator design was developed to replace the aspirator and muffler by a one-piece design. This new concept was designed to meet the noise performance targets while making it easy to manufacture, while meeting the airflow targets of the current production two-part aspirator and muffler design. The new design incorporates the change in airflow direction to address the customer concern.
Keywords: Muffler; Noise; Airflow; Aspirator; Automotive
Authors: Matthias Behrendt; Gerhard Robens; Albert Albers
Abstract: The pass-by noise is a necessary validation step within the vehicle development process for the homologation of every vehicle. With respect to accuracy and reproducibility and to avoid for example weather conditions etc. there is an effort to transfer the pass-by noise measurement into an acoustic roller test bench. Therefore an acoustic chamber in the size of the ISO 362 track is obligatory. Those chambers are very expensive and often not possible because of the facility’s infrastructure. The anechoic chamber at IPEK – Institute of Product Engineering at KIT includes a four-wheel roller test bench but is not providing the ISO 362 track dimensions. In order to measure the complete length of the test track in small chambers it is necessary to develop a method for scaling the measurement setup. In this contribution the focus is the scaling from large to small chambers and not the transfer from road to rig itself. To quantify related influences the paper at hand deals with measurements by the use of generic sources, for example a full and a half dodecahedron and discusses the results. These results are transferred to the vehicle application in order to get valid and reproducible results.
Keywords: Acoustic; Indoor Pass-by; Anechoic Chamber; Dodecahedron
Authors: Arkadiy Prodeus
Abstract: Detailed description of speech intelligibility assessment by proposed formant-modulation method is presented in the paper. Analytical expressions for expectation and variance of estimators of a modulation coefficient and effective signal-to-noise ratio are obtained. Two situations which are most interesting in engineering applications are considered: a predominant noise disturbance and a predominant reverberant disturbance. Convenience in engineering applications equations, which permit finding efficient test signal duration for required measurement exactness, has been obtained. Computer modelling and experimental testing have confirmed efficiency of the formant-modulation method.
Keywords: Speech Intelligibility; Formant-Modulation Method; Assessment; Measuring Exactness
Authors: Tetsuya Yamamoto; Hiroshi Tsuda; Junji Takatsubo
Abstract: The center location of a defect (a drill hole, DH) in a solid material was estimated using the circular-shaped wavefront of scattering waves. Measurement data recorded by a pulsed laser scanning system were used in the calculation. For data preprocessing, two techniques were applied: with the waveform peaks being extracted from the original measurement signals, and then a suitable threshold level being applied to the peak-extracted data. The center location of the hole was detected using the scattering wavefront of the snapshot images obtained immediately after reflection from the hole. Efficient calculation can be achieved as a result of decreasing a great number of pixel points in the snapshot images. This imaging technique is a promising candidate for use in an automatic defect inspection system that employs ultrasonic waves excited by pulsed laser scanning.
Keywords: Defect Detection; Pulsed Laser Scanning; Scattering Wave; Non-Destructive Inspection; Drill Hole
Authors: Jan Jabben; Charlos Potma
Abstract: Since 2000, the Dutch National Institute for Public Health and Environment (RIVM) carries out a noise monitoring program, commissioned by the Dutch Ministry of Infrastructure and Environment. The program involves continuous measurements along several motorways in the Netherlands. At each monitoring site, LAeq values are registered hourly, together with traffic volumes and temperature. The extensive data series allow an evaluation of temperature effects on measured noise levels. This paper gives an overview of effects seen in previous years along the A2 and N256 motorways in the Netherlands. At the N256 a distinction of effects from passenger cars and trucks is made. In addition to previous results, latest results of 2010 and analyses will be discussed and compared with guidelines at use for temperature correction.
Keywords: Tire Road Noise; Traffic Speed; Measurement; Temperature
Authors: Woon Siong Gan
Abstract: In a previous paper, the author proposed turbulence as a second order phase transition with spontaneous broken symmetry. This has been experimentally confirmed by research groups from the University of Illinois and Weizemann Institute of Science. In this paper we propose turbulence as a classical analog of Bose Einstein condensate and the Gross-Pitaevskii equation is used to derive the condensation free energy. The critical value of the order parameter, the condensation wave function is determined. This is the value where turbulence occurs and spontaneous symmetry breaking in the ground state of the condensation free energy takes place. Being a condensate, there is molecular pairing in turbulence. We determine the numerical value of the condensation free energy with the use of the coupled oscillation model for the pair of molecules. Our expression for the condensation free energy also yields a power series in terms of the order parameter in agreement with the Landau phenomenology of second order phase transition. This confirms that turbulence is a condensate since Gross-Pitaevskii equation is the equation for condensate. We conclude that our understanding of turbulence is a second order phase transition and is a condensate with molecular pairing.
Keywords: Second Order Phase Transition; Spontaneous Symmetry Breaking; Condensate; Gross-Pitaesvkii Equation; Condensation Wave Function; Condensation Free Energy; Order Parameter; Molecular Pairing; Coupled Oscillation