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Noise Behavior (noise + behavior)

Distribution by Scientific Domains
Engineering75%

Selected Abstracts

Two-point water-fat imaging with partially-opposed-phase (POP) acquisition: An asymmetric Dixon method,

MAGNETIC RESONANCE IN MEDICINE, Issue 3 2006
Qing-San Xiang
Abstract A novel two-point water-fat imaging method is introduced. In addition to the in-phase acquisition, water and fat magnetization vectors are sampled at partially-opposed-phase (POP) rather than exactly antiparallel as in the original Dixon method. This asymmetric sampling encodes more valuable phase information for identifying water and fat. From the magnitudes of the two complex images, a big and a small chemical component are first robustly obtained pixel by pixel and then used to form two possible error phasor candidates. The true error phasor is extracted from the two error phasor candidates through a simple procedure of regional iterative phasor extraction (RIPE). Finally, least-squares solutions of water and fat are obtained after the extracted error phasor is smoothed and removed from the complex images. For noise behavior, the effective number of signal averages NSA* is typically in the range of 1.87,1.96, very close to the maximum possible value of 2. Compared to earlier approaches, the proposed method is more efficient in data acquisition and straightforward in processing, and the final results are more robust. At both 1.5T and 0.3T, well separated and identified in vivo water and fat images covering a broad range of anatomical regions have been obtained, supporting the clinical utility of the method. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source]

Characterization of disk brake noise behavior via measurement of friction forces

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009
Stefan Schlagner
Squealing of disk brakes is a major problem in the field of vehicle design. It is commonly acknowledged, that this squeal is initiated by instability due to friction forces between the pads and the disk, leading to self excited vibrations. This work addresses the mechanical work of these friction forces in order to draw conclusions for the investigation of the noise behavior of disk brakes. Therefore a multi degree of freedom model is used to compare its stability behavior with the frictional work at the pads. The results obtained are applied to experiments in which, on the one hand brake pads with integrated piezoceramic actuators cause a broad band excitation and, on the other hand, dynamic pad velocities/accelerations and friction forces are measured. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Signal-noise support vector model of a microwave transistor

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 4 2007
Filiz Güne
Abstract In this work, a support vector machines (SVM) model for the small-signal and noise behaviors of a microwave transistor is presented and compared with its artificial neural network (ANN) model. Convex optimization and generalization properties of SVM are applied to the black-box modeling of a microwave transistor. It has been shown that SVM has a high potential of accurate and efficient device modeling. This is verified by giving a worked example as compared with ANN which is another commonly used modeling technique. It can be concluded that hereafter SVM modeling is a strongly competitive approach against ANN modeling. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007. [source]