29,683 research outputs found
Joseph Y. S. Cheng (éd.), Guangdong. Preparing for the WTO Challenge
No full textArvanitis Rigas. Joseph Y. S. Cheng (éd.), Guangdong. Preparing for the WTO Challenge. In: Perspectives chinoises, n°91, 2005. pp. 64-65
Joseph Y. S. Cheng (éd.), Guangdong. Preparing for the WTO Challenge
No full textArvanitis Rigas. Joseph Y. S. Cheng (éd.), Guangdong. Preparing for the WTO Challenge. In: Perspectives chinoises, n°91, 2005. pp. 64-65
Isolation of therapeutically functional mouse bone marrow Mesenchymal stem cells within 3 hours by an effective single-step plastic-adherent method
No full text
Estimation Of Formation Parameters Using Full Waveform Acoustic and Shear Wave Logs
Get PDFA combination of borehole Stoneley waves from full waveform acoustic logs and direct
shear wave logs was used to estimate formation permeability and shear wave velocity.
Data sets used here were collected by Area's array full waveform acoustic logging tool
and shear wave logging tool. The P- and S-wave velocities of the formation are determined
by threshold detection with cross-correlation correction from the full waveform
and the shear wave log, respectively. The full waveform acoustic logging data are also
processed using the Extended Prony's method to estimate the borehole Stoneley wave
phase velocity and attenuation as a function of frequency. Two different borehole models
are considered for the inversion of Stoneley wave velocity and attenuation data. They
are the isotropic elastic and the porous isotropic borehole models. Inversion parameters
include shear wave velocity and formation permeability. Inverted shear wave velocities
and permeabilities are compared with the shear wave log and the core permeability
measurements, respectively, for an integrated interpretation and possible identification
of shear wave anisotropy.Massachusetts Institute of Technology. Borehole Acoustics and Logging ConsortiumUnited States. Dept. of Energy (Grant DE-FG02-86ER13636
HASTATUS FAVIAE N. GEN., N. SP., A XARIFIID COPEPOD PARASITIC IN THE HONEYCOMB CORAL OF TAIWAN
No full textSingaporean mothers' perception of their three-year-old child's weight status: A cross-sectional study
Get PDFSingapore National Research Foundation; National Medical Research Council (NMRC), SingaporeFull Author List: Cheng T.S.; Cheng T.; Loy S.; Cheung Y.; Chan J.; Tint M.; Godfrey K.; Gluckman P.; Kwek K.; Saw S.; Chong Y.; Lee Y.; Yap F.; Lek N.; Sheppard A.; Chinnadurai A.; Goh A.; Rifkin-Graboi A.; Qiu A.; Biswas A.; Lee B.; Broekman B.; Quah B.; Shuter B.; Chng C.; Ngo C.; Hsu S.; Bong C.; Henry C.; Chee C.; Fok D.; Yeo G.; Inskip H.; Chen H.; Van Bever H.; Magiati I.; Wong I.; Lau I.; Kapur J.; Richmond J.; Holbrook J.; Gooley J.; Tan K.; Niduvaje K.; Singh L.; Su L.; Daniel L.; Shek L.; Fortier M.; Hanson M.; Chong M.; Rauff M.; Chua M.; Meaney M.; Teoh O.; Wong P.; Agarwal P.; Van Dam R.; Rebello S.; Chong S.; Cai S.; Soh S.; Lim S.; Rajadurai V.; Stunkel W.; Han W.; Pang W.; Goh Y.; Chan Y.</p
Experimental And Finite Difference Modelling Of Borehole Mach Waves
Get PDFA series of model experiments are done in the ultrasonic laboratory to study the radiation of downhole sources in a variety of formations. Three models are used in the
experiments. They are a lucite model, a lucite model with free glass pipe in the center,
and a glass cased soil model. In addition, the finite difference modelling technique is
used to simulate the wave propagation in these models and the results of the laboratory
and numerical experiments are compared. In the lucite borehole model the waveforms
recorded in the experiment agree very well with the finite difference synthetics. The
snapshots of the wavefield from finite difference simulation show the radiation pattern
of the P and S wave in the lucite formation. These patterns are consistent with the
theoretical calculations. In the lucite model with the free glass pipe, the finite difference synthetics are also in good agreement with the experimental observations, especially for the conical P-wave arrival. The angle between the wavefront of the conical P wave and the borehole axis observed from the snapshot agrees with the theory. In the cased soil model the arrival time of the finite difference synthetics is in good agreement with the lab measurements. The relative amplitudes of the P wave and Mach wave are not correctly modelled because of no intrinsic attenuation in the finite difference calculation. The Mach cone angle from the snapshot agrees with the theoretical prediction. Finally the finite difference method is used to simulate the Mach wave propagation in the formation with two horizontal layers. In the two slow formation layers case, Mach wave generated in the first layer reflected back from and transmitted through the boundary and another Mach wave is generated at the second layer when the Stoneley wave travels into the second layer. In the one slow and the one fast formation layer case, the Mach wave generated in the slow formation is reflected back at the boundary and leaked into the fast formation layer. There is no Mach wave in the fast formation layer.Massachusetts Institute of Technology. Borehole Acoustics and Logging Consortiu
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