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Iterative hybrid decoding algorithm for LDPC codes based on attenuation factor

Frontiers of Electrical and Electronic Engineering in China 2012年第3期7卷 279-285页

作者： Minghua LIU Lijun ZHANG School of Electronic and Information Engineering Beijing JiaotongUniversity Beijing 100044 China

An attenuated iterative reliability-based major- ity-logic （AIML） decoding algorithm for low-density parity-check （LDPC） codes is proposed, which pertains to hybrid decoding schemes. The algorithm is devised based on the orthogonal check-sums of one-step majority- logic （OSMLG） decoding algorithm in conjunction with certain of reliability measures of the received symbols. Computation of reliability measure of the syndrome sum is refined by introducing an attenuation factor. Simulation results show that, in binary-input additive white Gaussian noise （BI-AWGN） channel, the AIML decoding algorithm outperforms other popular iterative reliability-based major- ity-logic （IML） decoding algorithms with a slight increase in computational complexity. Within maximum iteration number of 5, the AIML algorithm can achieve almost identical error performance to sum-product algorithm （SPA）. No error floor effect can be observed for the AIML algorithm down to the bit error rate （BER） of 10- s, while error floor appears for SPA around the BER of 10 7 even with maximum iteration number of 100. Furthermore, the inherent feature of parallel procession for AIML algorithm enforces the decoding speed in contrast to those serial decoding schemes, such as weighted bit-flipping （WBF） algorithm.

关键词： attenuation factor reliability-based iterative,majority-logic low-density parity-check (LDPC) codes

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The Assessment of Groundwater Vulnerability Due to Leaching of Chemicals: The Review of attenuation factor

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Open Journal of Soil Science 2016年第1期6卷 9-20页

作者： Sivarajah Mylevaganam Chittaranjan Ray University of Nebraska-Lincoln Lincoln NE USA

To assess the groundwater vulnerability due to leaching of chemicals, the groundwater system in the unsaturated zone is characterized by conceptual models that are further extended and refined with more detailed mathematical models to understand the governing physical processes in detail. However, due to lack of data and uncertainty level, an intermediate transition through index based models is researched. The attenuation factor (AF) approach, which works under the assumption that the chemicals degrade following a first-order kinetics and determines the fraction of the chemicals that goes to groundwater table, is one of the index based models that has been widely used due to its simplicity. Therefore, the objective of this paper is to review the research works done using the AF approach, to outline the future research needs. Furthermore, the mathematical implementation of the AF approach and the associated uncertainty levels is explained through an example and MATLAB source code.

关键词： attenuation factor Index Based Models Groundwater Vulnerability Assessment Uncertainty Level Volatization MATLAB

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GNSS Precise Point Positioning Based on Dynamic Kalman Filter with attenuation factor

GNSS Precise Point Positioning Based on Dynamic Kalman Filte...

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第37届中国控制会议

作者： Yufu Guo Senchun Chai Lingguo Cui Beijing Institute of Technology School of Automation

This paper addresses the Kalman filter divergence problem for Global Navigation Satellite System（GNSS）in Precise Point Positioning（PPP）. Continuous improvement of precision of GNSS PPP makes it widely used in various fields, however the Kalman filter divergence resolutions for PPP signal attenuating and satellite missing condition are still insufficient. Kalman filter is a recursive, linear unbiased,minimum variance method. Compared with the standard Kalman filter, the dynamic Kalman filter with attenuation factor in this paper makes up for the Kalman filter divergence problem. The effectiveness of dynamic Kalman Filter is demonstrated via matlab simulation.

关键词： Precise Point Positioning Kalman divergence attenuation factor

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A nonparametric spectrum estimation method for dispersion and attenuation analysis of borehole acoustic measurements

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Petroleum Science 2023年第1期20卷 241-248页

作者： Bing Wang Wei Li Qing Ye Kun-Yu Ma State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China Beijing Research Center Aramco AsiaBeijing100102China

Dispersion and attenuation analysis can be used to determine formation anisotropy induced by fractures,or *** this paper,we propose a nonparametric spectrum estimation method to get phase dispersion characteristics and attenuation *** designing an appropriate vector filter,phase velocity,attenuation coefficient and amplitude can be inverted from the waveform recorded by the receiver *** analysis of this algorithm is compared with Extended Prony Method(EPM)and Forward and Backward Matrix Pencil(FBMP)*** on the analysis results,the proposed method is capable of achieving high resolution and precision as the parametric spectrum estimation *** the meantime,it also keeps high stability as the other nonparametric spectrum estimation *** last,applications to synthetic waveforms modeled using finite difference method and real data show its *** real data processing results show that the P-wave attenuation log is more sensitive to oil formation compared to S-wave;and the S-wave attenuation log is more sensitive to shale formation compared to P-wave.

关键词： Dispersion analysis attenuation factor Nonparametric spectrum estimation method Acoustic logging Fluid type evaluation

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Experimental study on wire breakage detection by acoustic emission

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Frontiers of Structural and Civil Engineering 2011年第4期5卷 503-509页

作者： Limin SUN Ji QIAN State Key Laboratory for Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China

This paper experimentally investigated wire breakage detection in a steel cable by acoustic emission(AE)*** the experiments,the attenuation laws of waveform amplitudes were discussed based on stress wave propagation in the wire,which was generated by kNocking and wire *** the wave velocity was calculated based on the reach time of the stress wave from each ***,based on the waveform attenuation laws and the linear position method,the amplitude and energy of the source were confirmed through the measured waveform to identify the source *** experimental results illustrated that the stress wave from different sources has a different frequency spectrum,and the amplitude attenuation factor varied with the stress wave frequency;high frequency waves had a greater attenuation *** with the other source,the wire breakage source contained a much higher energy,and thus,the wire breakage signal can be distinguished from the other source by comparing the non-attenuation energy at the source position.

关键词： acoustic emission(AE) waveform wire breakage attenuation factor wave velocity

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Forecasting of Target Air Route Based on Weighted Least Squares Method

Forecasting of Target Air Route Based on Weighted Least Squa...

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第二十九届中国控制会议

作者： CAO Jian-Zhong,HUANG Jin-Qiu,CHEN Zhi-Ming Electronic Science Department,Huizhou University,Guangdong 516007,P.R.China

The azimuth and elevation variation rules of a short-range,low-flying target is firstly analyzed in this paper,then the target air route is predicted using a weighted least squares parabolic regression parameter estimation method-firstly the input signal is filtered,then one step prediction is carried *** method has advantages of easier formula derivation and less intermediate *** results show that by selection of forgetting factor of the historical data,the prediction of the target air route can be faster,stabler and more accurate.

关键词： Target Air Route Least Squares Method attenuation factor Prediction

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