Study on velocity attenuation of spherical tungsten fragments by comb target

Author(s):  
Jiajie ZHOU ◽  
Deren KONG
Keyword(s):  
2012 ◽  
Vol 531-532 ◽  
pp. 751-754
Author(s):  
Ying Xue Yao ◽  
Hong Bo Wang ◽  
Liang Zhou

A low-speed spindle running on air bearings is presented, it is used on rotary viscometer based on velocity attenuation of rotating cylinder. Principle of spindle is introduced, it is composed of a low speed motor and an air bearing. The low speed motor is a coupling of two motors. Design of the spindle shows the structure of it. Materials of the spindle are selected. The spindle is machined and operation process of it shows it is suitable for driving part of rotary viscometer based on velocity attenuation of rotating cylinder.


2000 ◽  
Vol 43 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Zhongjie Zhang ◽  
Jiwen Teng ◽  
Zhenhua He

Geophysics ◽  
2020 ◽  
Vol 85 (2) ◽  
pp. D65-D74 ◽  
Author(s):  
Andrew J. Carter ◽  
Veronica A. Torres Caceres ◽  
Kenneth Duffaut ◽  
Alexey Stovas

Seismic attenuation distorts phase and narrows bandwidth in seismic surveys. It is also an exploration attribute, as, for example, gas or overpressure, may create attenuation anomalies. Compensating attenuation in imaging requires accurate models. Detailed attenuation models may be obtained using full-waveform inversion (FWI) or attenuation tomography, but their accuracy benefits from reliable starting models and/or constraints. Seismic attenuation and velocity dispersion are necessarily linked for causal linear wave propagation such that higher frequencies travel faster than lower frequencies in an attenuative medium. In publicly released well data from the Norwegian North Sea, we have observed systematic positive linear trends in check-shot drift when comparing (lower frequency) time-depth curves with (higher frequency) integrated sonic transit times. We observe velocity dispersion consistent with layers having constant seismic attenuation. Adapting a previously published method, and assuming an attenuation-dispersion relationship, we use drift gradients, measured over thick stratigraphic units, to estimate interval P-wave attenuation and tentatively interpret its variation in terms of porosity and fluid mobility. Reflectivity modeling predicts a very low attenuation contribution from peg-leg multiples. We use the attenuation values to develop a simple regional relationship between P-wave velocity and attenuation. Observed low drift gradients in some shallower units lead to an arch-shaped model that predicts low attenuation at both low and high velocities. The attenuation estimates were broadly comparable with published effective attenuation values obtained independently nearby. This general methodology for quickly deriving a regional velocity-attenuation relationship could be used anywhere that coincident velocity models are available at seismic and sonic frequencies. Such relationships can be used for fast derivation (from velocities) of starting attenuation models for FWI or tomography, constraining or linking velocity and attenuation in inversion, deriving models for attenuation compensation in time processing, or deriving background trends in screening for attenuation anomalies in exploration.


2020 ◽  
Vol 44 (4) ◽  
pp. 212-219
Author(s):  
Ammar A. Oglat ◽  
Marwan Alshipli ◽  
Mohannad Adel Sayah ◽  
Muntaser S. Ahmad

In this review, the ultrasound (US) artifacts features such as propagation path, velocity, attenuation, multiple echoes, and resolution are explained. The main restrictions of an axial and lateral resolution are artifacts. However, failure to fix them lead to the lack of details, and adjacent neighboring objects may be observed as one image. This article describes an essential law to control wave movement, and the US artifacts are formed. Thus, it is substantial for the radiologist and sonographer to differentiate between the artifacts and abnormal signs during the diagnostic procedure. Furthermore, the use of enhancing and shadowing artifacts in determining the nature of masses was explained. The comet tail, attenuation, mirror image, refraction, speed displacement, side lobe, and beam width artifacts happened typically in clinical (in-vivo) practice were also discussed. Finally, an estimation and evaluation of these artifacts are necessary to increase the accuracy in diagnosis.


2015 ◽  
Vol 25 ◽  
pp. 206-213
Author(s):  
J.A. Peñaloza Giraldo ◽  
J.A. Escobar-Vargas ◽  
L.D. Donado

Author(s):  
HONG-PING GU ◽  
CHUN-LIN YI ◽  
YONG-ZHU LU ◽  
GUANG-JIA LI ◽  
BAO-HUA LI ◽  
...  

Ultrasonics ◽  
2011 ◽  
Vol 51 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Tomohisa Norisuye ◽  
Satoshi Sasa ◽  
Kohsuke Takeda ◽  
Mariko Kohyama ◽  
Qui Tran-Cong-Miyata

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