نتایج جستجو برای: stoneley wave velocity
تعداد نتایج: 341781 فیلتر نتایج به سال:
1872-9312/$e seefrontmattera2008A doi:10.1016/j.artres.2008.11.002 Summary Measurement of pulse wave velocity is of increasing importance for assessment of arterial stiffness and risk evaluation. Different techniques are available, based either on pressure, distension or Doppler waveforms. Techniques not only differ by the algorithm used to identify specific part of the pulse signal, but also i...
We apply 2-D wave-equation prestack depth migration to a North Sea basalt dataset. High velocity and impedance contrasts across a basalt layer causes low P-wave reflection signal-to-noise ratio under the basalt. We first migrate the P-wave data with a provided depth velocity model, and then replace sub-basalt P-wave velocity with a simple estimate of shear wave velocity and migrate locally-conv...
Sand improvements using organic agents have shown promising results. Polyacrylamide is one possible organic agent, which has been shown to influence the shear strength, stiffness, soil remediation, and erosion resistance of geomaterials. In this study, we explored the shear wave velocity (S-wave) and water retention curves of unsaturated sands containing polyacrylamide solutions. The shear wave...
In this report, we introduce a new wave-equation method of migration velocity analysis (MVA). The method is based on the linear relation that can be established between a perturbation in the migrated image and the generating perturbation in the slowness function. Our method consists of two steps: we first improve the focusing of the migrated image and then iteratively update the velocity model ...
Carotid-femoral pulse wave velocity is an established method for characterizing aortic stiffness, an individual predictor of cardiovascular mortality in adults. Normal pulse wave velocity values for the pediatric population derived from a large data collection have yet to be available. The aim of this study was to create a reference database and to characterize the factors determining pulse wav...
OBJECTIVES Mitral regurgitation (MR) is a common echocardiographic finding; however, there is no simple accurate method for quantification. The aim of this study was to develop an easily measured screening variable for hemodynamically significant MR. BACKGROUND The added regurgitant volume in MR increases the left atrial to left ventricular gradient, which then increases the peak mitral inflo...
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