1,721,045 research outputs found
On the selection of loads in the multiload method for measuring the acoustic source parameters of duct systems
No full textThe in-duct source can be characterized by two acoustical parameters such as the source strength and the source impedance, which permit the prediction of radiated sound pressure or insertion loss of the whole duct system. One-port acoustic characteristics of an in-duct source can be measured by the multiload method using an overdetermined set of open pipes or side-branch pipes with different lengths as applied loads. The input data, viz. load pressure and load impedance, are usually contaminated by measurement error in the actual measurements, which result in errors in the calculated source parameters. In this paper, the effects of the errors in the input data on the results have been studied numerically, varying the number of loads and their impedances in order to determine what combination of the loads will yield the best result. It is noted that, frequently, only a set of open pipes is used when applying the multiload method to the internal combustion engine sources. A set of pipe lengths, which cause the calculated results to be least sensitive to the input data error, can be found when using open pipe loads. The present work is intended to produce guidelines for preparing an appropriate load set in order to obtain accurate source properties of fluid machines. (C) 2002 Acoustical Society of America
BACKWARD PREDICTIVE BLOCK MATCHING ALGORITHM FOR LOW BIT RATE VIDEO CODING
No full textIn contrast to the conventional block matching algorithm (BMA) in video coding, a backward predictive BMA which does not need the transmission of the motion vector is investigated. The motion vector is estimated using the previously estimated motion vectors and reconstructed pixels adjacent to a block to be coded. For application to low bit rate video coding, backward/forward adaptive BMA is devised. At 59 kbit/s the proposed scheme provides 0.2-0.5 dB improvement in peak signal to noise ratio (PSNR) over the conventional BMA
Refined multiload method for measuring acoustical source characteristics of an intake or exhaust system
No full textThe one-port source characteristics in a duct system, viz., source impedance and strength, can be determined by using the four-load method. In this paper, to avoid the instability problem of the conventional four-load method, a new formulation for the multiload method has been proposed, which employs an error function based on the linear, time-invariant source model. It is shown that the method is less sensitive to input errors compared to the previous methods. For a 10% input error, the proposed method yields a relative error in the source resistance that is about 1/100 times smaller than for the conventional method. The effectiveness of the present method is demonstrated by two test examples, a loudspeaker and a blower, each operating in a duct. It is observed that the conventional and least-squares methods result in large errors, whereas the present method yields far better agreement with the actual source parameters, as measured by the direct method. The present method is then used to obtain the source parameters on the exhaust side of an operating internal combustion engine. The radiated sound spectrum from the exhaust opening is predicted by using the measured source parameters and the calculated result agrees very well with the measured one. (C) 2000 Acoustical Society of America. [S0001-4966(00)00906-1]
A measurement method for the nonlinear time-variant source characteristics of intake and exhaust systems in fluid machines
No full textModeling of Frame Difference Image Based on Ridge-signal and Application to Low-rate Video Data Compression
No full text
Development of CRISPRi based gene knock-down platform for Leuconostoc citreum and its application for riboflavin production
No full textEngineering of Klebsiella oxytoca for Improved xylose Utilization using Adaptive Laboratory Evolution
No full text- …
