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31.
Seyeong Choi Mazen O. Hasna Hong‐Chuan Yang Mohamed‐Slim Alouini 《Wireless Communications and Mobile Computing》2013,13(10):897-907
In this paper, we proposed several antenna selection schemes for cooperative diversity systems with adaptive transmission. The proposed schemes were based on dual‐hop relaying where a relay with multiple‐antenna capabilities at reception and transmission is deployed between the source and the destination nodes. We analyzed the performance of the proposed schemes by quantifying the average spectral efficiency and the outage probability. We also investigated the trade‐off of performance and complexity by comparing the average number of active antennas, path estimations, and signal‐to‐noise ratio comparisons of the different proposed schemes. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
32.
Two-dimensional (2-D) formulae for estimating discharge capacity of straight compound channels are reviewed and applied to
overbank flows in straight fixed and mobile bed compound channels. The predictive capabilities of these formulae were evaluated
using experimental data obtained from the small-scale University of Birmingham channel. Full details of these data and key
references may be found at the following www.flowdata.bham.ac.uk (university website). 2-D formulae generally account for
bed shear, lateral shear, and secondary flow effects via 3 coefficients f, λ and Γ In this paper, the secondary flow term (Γ) used within the 2-D methods analysed here is ignored in all applications. Two different 2-D formulae almost give practically
the same results for the same data when the secondary flow term is ignored. For overall test cases, the value of dimensionless
eddy viscosity λ used in 2-D formulae was kept at 0·13 as recommended for open channels. 2-D formulae gave good predictions for most of the
data sets studied in comparison with the traditional 1-D methods, namely the Single Channel Method (SCM) and the Divided Channel
Method (DCM). The accuracy of predictions of 2-D formulae was increased by calibrating of λ value where the calibration was needed. For overall data, the average errors for each method were Lateral Division Methods
(LDMs), with λ value of 0·13, 2·8%, DCM 14·3% and SCM −26·8%. The average error was 0·5% for LDMs with the calibrated values of λ 相似文献
33.
An extended state observer(ESO)-based loop filter is designed for the phase-locked loop(PLL)involved in a disturbed grid-connected converter(GcC).This ESO-based... 相似文献
34.
Wireless Personal Communications - Object detection is one of the most important computer vision tasks that is used synonymous to object recognition which comprises the mission of identifying the... 相似文献
35.
The Journal of Supercomputing - Software-defined networks (SDNs) are designed to cover the dynamic operations of network factors and the complex role of controlling components to achieve... 相似文献
36.
Ismail Abdulazeez Othman Charles S. Al-Hamouz Mazen Khaled Abdulaziz A. Al-Saadi 《工业材料与腐蚀》2020,71(4):646-662
Oil well acidizing is a common practice used to boost oil well productivity in the industry. This practice, however, exposes the mild steel components of the wells to extremely harsh corrosive environments. Under such conditions, highly efficient inhibitors are used to minimize corrosion attack. In the present study, corrosion inhibition of mild steel in simulated acidic medium saturated with CO2 and H2S gases by a newly synthesized polyurea-based material (PUCorr-1) was investigated. Electrochemical studies supported with quantum chemical density-functional theory calculations and surface characterization revealed that PUCorr-1 adsorbs onto mild steel through a chemisorption mechanism yielding a stable protective film. The polyurea exhibited an excellent efficiency of 99.9% at a temperature of 50°C and a low concentration of 100 ppm, yielding a corrosion current density of 0.3 µA/cm2. In the presence of CO2 and H2S gases, PuCorr-1 exhibited a remarkable performance (>93% efficiency) making it a potential corrosion inhibitor in industrial processes that involve the use of acid solutions in the presence of CO2 and H2S gases. 相似文献
37.
Abdel-Salam Mazen Fattah A. Abdel Saied Mohamed M. Tharwat-El-Mohandes M. 《Industry Applications, IEEE Transactions on》1985,(4):912-918
A set of oscillograms has been obtained to investigate the development of pulse mode in the positive discharge from a single and twin interacting thin needles. The transition from burst pulses to continuous glow in laboratory air is discussed. When the needles are brought close together, the onset voltage increases with a subsequent decrease of the corona current for the same applied voltage. Not only the onset voltage but also the offset voltage (i.e., voltage at which the burst pulses disappear) increases as the needle-to-needle spacing decreases. The pulse repetition rate increases with the applied voltage reaching maximum and then showed a decrease with further increase of voltage. When the needles are brought very close to each other, the rate of increase of pulse repetition rate with voltage increases by about 15 percent more than the corresponding rate for single needle. Not only the rate of increase of pulse repetition rate but also the repetition rate itself reaches almost double the value for a single needle. The randomness of the pulse repetition rate was found maximum at voltages close to the onset value and decreases with increase of the voltage. On the contrary, the pulses had almost the same amplitude at voltages very close to the onset value. 相似文献
38.
39.
Mazen Farhood 《国际强度与非线性控制杂志
》2018,28(4):1281-1302
》2018,28(4):1281-1302
This paper focuses on spatially distributed control systems where the controller sensing and actuation topology is inherited from that of the plant. Specifically, this paper considers distributed systems composed of discrete‐time linear parameter‐varying subsystems interconnected over general graph structures. These distributed systems are subject to a communication latency of one sampling period, where the information sent by a subsystem at the current time step is received by the target subsystem at the next time step. Analysis and synthesis conditions are derived for control design in this setting using a parameter‐dependent Lyapunov approach with the ?2‐induced norm as the performance measure. Fast and easy‐to‐implement algorithms are also provided for constructing the controller in real time. The techniques developed are finally applied to a leader‐follower formation problem with intermittent communications. 相似文献
40.
Polycrystalline samples of mixed ferrite Mnl –x
Cd
x
Fe2O4, wherex = 0, 0.2, 0.4, 0.6 and 0.8, were studied by X-ray analysis and d.c. electrical conductivity. lt was found that the calculated lattice parameter (a
0) increases from 0155 to 0.861 nm according to increases inx from 0 to 0.8. The apparent density and theoretical density exhibit the same behaviour. lt was also found that the activation energy of the conduction mechanism and log 27° C increase with increasing cadmium content, which affect the exchange interaction mechanism in tetrahedral (A) sites and octahedral (B) sites. 相似文献