Determining Petrophysical Parameters of Rock during Phase Displacement with CT Technique

2000 ◽  
Author(s):  
Zhongyuan Tian ◽  
Lianhai Lu
Keyword(s):  
Petrophysical Parameters ◽  
Phase Displacement ◽  
Ct Technique

scholarly journals Common-Mode Voltage Harmonic Reduction in Variable Speed Drives Applying a Variable-Angle Carrier Phase-Displacement PWM Method

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2929
Author(s):  
Abraham Marquez Alcaide ◽  
Vito Giuseppe Monopoli ◽  
Xuchen Wang ◽  
Jose I. Leon ◽  
Giampaolo Buticchi ◽  
...  
Keyword(s):  
Carrier Phase ◽  
Harmonic Distortion ◽  
Harmonic Spectrum ◽  
Hydraulic Systems ◽  
Variable Speed ◽  
Common Mode ◽  
Variable Speed Drives ◽  
Phase Displacement ◽  
Common Mode Voltage ◽  
External Component

Electric variable speed drives (VSD) have been replacing mechanic and hydraulic systems in many sectors of industry and transportation because of their better performance and reduced cost. However, the electric systems still face the issue of being considered less reliable than the mechanical ones. For this reason, researchers have been actively investigating effective ways to increase the reliability of such systems. This paper is focused on the analysis of the common-mode voltage (CMV) generated by the operation of the VSDs which directly affects to the lifetime and reliability of the complete system. The method is based on the mathematical description of the harmonic spectrum of the CMV depending on the PWM method implementation. A generalized PWM method where the carriers present a variable phase-displacement is developed. As a result of the presented analysis, the CMV reduction is achieved by applying the PWM method with optimal carrier phase-displacement angles without any external component and/or passive filtering technique. The optimal values of the carrier phase-displacement angles are obtained considering the minimization of the CMV total harmonic distortion. The resulting method is easily implementable on mostly off-the-shelf mid-range micro-controller control platforms. The strategy has been evaluated in a scaled-down experimental setup proving its good performance.

scholarly journals Optimised calibration programmes for comparators for instrument transformers

2021 ◽  
Vol 88 (2) ◽  
pp. 122-131
Author(s):  
Christian Mester
Keyword(s):  
Experimental Study ◽  
Operating Principle ◽  
Device Under Test ◽  
Operating Range ◽  
Ratio Error ◽  
Phase Displacement ◽  
Instrument Transformers ◽  
Instrument Transformer ◽  
Method Of Measurement

Abstract Traditionally, instrument transformers are calibrated using bridges. By definition, bridges use the null method of measurement. The traditional calibration programme for instrument transformer bridges characterise namely this null measurement. Many new commercial comparators for instrument transformer use a very different method. They sample the secondary signals of reference and device under test (dut) transformer independently. Based on the samples, magnitude and phase of both signals are determined. Ratio error and phase displacement are calculated. Consequently, the significance of their calibration using the traditional calibration programme is limited. Moreover, the operating range of modern comparators is much larger than that of bridges. The additional versatility cannot be used without an adapted calibration programme. This article analyses the calibration programmes for both technologies. An experimental study confirms both the suitability of the new calibration programme and the need to chose the calibration programme depending on the technology of the device to be calibrated. The conclusion is very general and applies to all measurement problems where an operating principle is replaced by another – when changing the operating principle, it is important to check the calibration programme and adapt it if necessary.

Applications and Modulation Methods for Modular Converters Enabling Unequal Cell Power Sharing: Carrier Variable-Angle Phase-displacement Modulation Methods

2021 ◽  
pp. 2-13
Author(s):  
Vito Giuseppe Monopoli ◽  
Abraham Marquez Alcaide ◽  
JOSE I. LEON ◽  
Marco Liserre ◽  
Giampaolo Buticchi ◽  
...  
Keyword(s):  
Power Sharing ◽  
Phase Displacement ◽  
Variable Angle ◽  
Modular Converters ◽  
Modulation Methods

Cerebral Perfusion CT: Technique and Clinical Applications

Radiology ◽  
2004 ◽  
Vol 231 (3) ◽  
pp. 632-644 ◽  
Author(s):  
Ellen G. Hoeffner ◽  
Ian Case ◽  
Rajan Jain ◽  
Sachin K. Gujar ◽  
Gaurang V. Shah ◽  
...  
Keyword(s):  
Cerebral Perfusion ◽  
Clinical Applications ◽  
Perfusion Ct ◽  
Ct Technique

scholarly journals Phase Displacement Acceleration of High Intensity Stacks in the CERN ISR

1977 ◽  
Vol 24 (3) ◽  
pp. 1431-1433 ◽  
Author(s):  
E. Ciapala ◽  
S. Myers ◽  
C. Wyss
Keyword(s):  
High Intensity ◽  
Phase Displacement

CT colonography: determination of optimal CT technique using a novel colon phantom

2004 ◽  
Vol 29 (2) ◽  
pp. 173-176 ◽  
Author(s):  
K. T. Johnson ◽  
C. D. Johnson ◽  
S. M. Anderson ◽  
M. R. Bruesewitz ◽  
C. H. McCollough
Keyword(s):  
Ct Colonography ◽  
Ct Technique
Sign in / Sign up

Export Citation Format

Share Document