Results 251 to 260 of about 131,967 (276)
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Carrier drift velocity in semiconducting strings
Physica E: Low-dimensional Systems and Nanostructures, 2003Abstract The carrier drift velocity in a 1D semiconducting sample attached to electrodes is derived from the Luttinger model, where the electric field generated by image charges within the electrodes is explicitly taken into account. If the length of the electrode is small enough compared to the sample length, the drift velocity vd can be estimated ...
S Kuwata, Y Koyama, K Fukeda
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Analysis of critical whirling velocity of drill string
Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021During the drilling process, the whirling motion often occurs, which will cause the drill string to vibrate violently, accelerate the fatigue damage of the drill string, and eventually cause the bo...
Jialin Tian +3 more
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Plunger Lift Versus Velocity Strings
Journal of Energy Resources Technology, 1999Plunger lift and velocity strings are two common methods of attacking liquid loading problems in gas wells. This paper shows how to compare the calculated performance of both methods at downhole producing conditions on one plot.
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Coiled Tubing Velocity Strings - Expanding the Cases
SPE/ICoTA Coiled Tubing Roundtable, 1998Abstract Coiled tubing is a preferred remedial method of extending the flowing life for gas wells. but selection of a size that will accomplish the task of removing bottomhole liquids is not simple. The difficult, in predicting results that guide coiled tubing selectivity is partly caused by the changing gas to ...
Alec Martinez, John Martinez
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Method for determining drill string velocity
The Journal of the Acoustical Society of America, 1989The invention is a method of determining the acoustic velocity of a drill string (28) in a borehole (10). An acoustic signal is generated at a first location(34) along the drill string, and detected at a second location (7). The detected signal is autocorrelated and the time of occurrence of multipath reflections on the autocorrelation record is ...
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Completion Leak Repair with Corrosion Resistant CT Velocity String
SPE/ICoTA Well Intervention Conference and Exhibition, 2023Abstract An operator company in Bolivia needed a solution to a corrosion and pressure integrity problem caused by the presence of CO2 gas in the production fluids, resulting in deep tubing corrosion over certain sections of completion components with measured penetrations up to 96% of tubing's wall thickness.
Erick Aguirre, Martin Nebiolo
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Modeling Coiled-Tubing Velocity Strings for Gas Wells
SPE Production & Facilities, 1998Summary Because of its ability to prolong well life, its relatively low expense, and the relative ease with which it is installed, coiled tubing has become a preferred remedial method of tubular completion for gas wells. Of course, the difficulty in procuring wireline-test data is a drawback to verifying the accuracy of the assumptions ...
John Martinez, Alec Martinez
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On the group velocity of guided waves in drill strings
The Journal of the Acoustical Society of America, 2001A key element to verify the drill-bit signal processing is the estimation of the time delay of the guided waves transmitted through the drill string from the bit to the surface. This delay can be measured from drill-bit vibrations or calculated using the mechanical properties of the drill string.
F, Poletto, J M, Carcione
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Decentralized Networked Control for Vehicle-String Velocity and Spacing
IFAC Proceedings Volumes, 2014Abstract Decentralized overlapping feedback control laws are designed for a vehicle-string bias system which controlled over networks in this paper. The dynamic model of vehicle-string bias system is treated as an interconnected system with overlapping states.
Distance Bias System +3 more
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Cosmic strings: Large-scale mass fluctuations and velocity fields
Chinese Astronomy and Astrophysics, 1988Abstract In this paper we calculate the large scale mass fluctuations and peculiar velocity fields in the cosmic string scenario in different dark matter-dominated universes. By using Turok et al.'s string density fluctuation spectra before gravitational growth and the usual linear perturbation theory, we get the mean square root mass fluctuation 〈
null Jing Yi-peng, null Zhang Jia-lü
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