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Similarity evaluation of stratum anti-drilling ability and a new method of drill bit selection
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作者 YAN Tie XU Rui +4 位作者 SUN Wenfeng LIU Weikai HOU Zhaokai YUAN Yuan SHAO Yang 《Petroleum Exploration and Development》 CSCD 2021年第2期450-459,共10页
Considering the stratum anti-drilling ability,drill bit working conditions,drill bit application effect and drill bit economic benefits,the similarity of stratum anti-drilling ability was evaluated by grey relational ... Considering the stratum anti-drilling ability,drill bit working conditions,drill bit application effect and drill bit economic benefits,the similarity of stratum anti-drilling ability was evaluated by grey relational analysis theory to screen out candidate drill bits with reference values.A new comprehensive performance evaluation model of drill bit was established by constructing the absolute ideal solution,changing the relative distance measurement method,and introducing entropy weight to work out the closeness between the candidate drill bits and ideal drill bits and select the reasonable drill bit.Through the construction of absolute ideal solution,improvement of relative distance measurement method and introduction of entropy weight,the inherent defects of TOPSIS decision analysis method,such as non-absolute order,reverse order and unreasonable weight setting,can be overcome.Simple in calculation and easy to understand,the new bit selection method has good adaptability to drill bit selection using dynamic change drill bit database.Field application has proved that the drill bits selected by the new drill bit selection method had significant increase in average rate of penetration,low wear rate,and good compatibility with the drilled formations in actual drilling.This new method of drill bit selection can be used as a technical means to select drill bits with high efficiency,long life and good economics in oilfields. 展开更多
关键词 drill bit selection stratum anti-drilling ability grey relational analysis absolutely ideal solution relative distance measurement method entropy weight comprehensive performance of drill bit
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Multiuser Pre-Coding Aided Quadrature Spatial Modulation for Large-Scale MIMO Channels 被引量:1
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作者 Fatang Chen Kang Yang +2 位作者 Pingping Xing Huan Zhang Yanan Jiang 《China Communications》 SCIE CSCD 2018年第11期62-69,共8页
Pre-coding aided quadrature spatial modulation(PQSM) is a promising multiple input multiple output(MIMO) transmission technology. The multiuser(MU) detection in PQSM system is investigated in this paper. Based on the ... Pre-coding aided quadrature spatial modulation(PQSM) is a promising multiple input multiple output(MIMO) transmission technology. The multiuser(MU) detection in PQSM system is investigated in this paper. Based on the known channel state information, pre-coding matrix is designed to pre-process the in-phase and quadrature signals of quadrature spatial modulation(QSM) to reduce the inter-channel interference. In order to lower the complexity at the receiver brought by the orthogonality of the PQSM system, an orthogonal matching pursuit(OMP) detection algorithm and a reconstructed model are proposed. The analysis and simulation results show that the proposed algorithm can obtain a similar bit error rate(BER) performance as the maximum likelihood(ML) detection algorithm with more than 80% reduction of complexity. 展开更多
关键词 pre-coding generalized quadra-ture spatial modulation bit error performance maximum likelihood
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Construction of protograph LDPC codes with circular generator matrices 被引量:5
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作者 Kaiyao Wang Yang Xiao Kiseon Kim 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2011年第5期840-847,共8页
The application of protograph low density parity check (LDPC) codes involves the encoding complexity problem. Since the generator matrices are dense, and if the positions of "1" s are irregularity, the encoder nee... The application of protograph low density parity check (LDPC) codes involves the encoding complexity problem. Since the generator matrices are dense, and if the positions of "1" s are irregularity, the encoder needs to store every "1" of the generator matrices by using huge chip area. In order to solve this problem, we need to design the protograph LDPC codes with circular generator matrices. A theorem concerning the circulating property of generator matrices of nonsingular protograph LDPC codes is proposed. The circulating property of generator matrix of nonsingular protograph LDPC codes can be obtained from the corresponding quasi-cyclic parity check matrix. This paper gives a scheme of constructing protograph LDPC codes with circulating generator matrices, and it reveals that the fast encoding algorithm of protograph LDPC codes has lower encoding complexity under the condition of the proposed theorem. Simulation results in ad- ditive white Gaussian noise (AWGN) channels show that the bit error rate (BER) performance of the designed codes based on the proposed theorem is much better than that of GB20600 LDPC codes and Tanner LDPC codes. 展开更多
关键词 protograph low density parity check (LDPC) codes cyclic matrices fast encoding algorithm bit error rate (BER) performance.
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Underwater Optical Wireless Communications (UOWC) Based on Visible Light
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作者 Mazin Ali A. Ali 《Journal of Physical Science and Application》 2016年第1期204-211,共8页
In this paper, we investigate the effect of water attenuation on an underwater optical wireless communication based on LOS model. We take into account parameters including the chlorophyll concentration and also discus... In this paper, we investigate the effect of water attenuation on an underwater optical wireless communication based on LOS model. We take into account parameters including the chlorophyll concentration and also discuss the choice of suitable wavelength for underwater optical wireless communication. Using analytical expressions and calculating the Jerlov water type attenuation, the received signal power is studied. The characteristics of bit error rate for four kinds of optical modulation techniques (OOK, 2FSK, 2DPSK, and L-PPM) are analyzed. The results show that the performance of OOK and 2DPSK are more suitable for underwater optical wireless communication. On the other hand, the wavelength 450 nm is better compared with the wavelength 600 nm. 展开更多
关键词 Underwater communications optical wireless communications bit error rate performance optical channel line-of-sight.
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