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101 results on '"He, Yu-Cheng"'

4. A Unilateral Nuclear Magnetic Resonance Sensor for Nondestructive Wood Moisture Measurements

Author

YU Deng-jie, GUO Pan, WU Jia-min, HE Yu-cheng, and XU Zheng

Subjects
unilateral nuclear magnetic resonance (UMR), sensor, wood, moisture, non-destructive detection, Electricity and magnetism, QC501-766
Abstract

An unilateral nuclear magnetic resonance (UMR) sensor was designed to measure wood moisture nondestructively. The sensor consisted of a unilateral magnet, an anti-eddy current module, a radiofrequency (RF) coil and an impedance matching and tuning circuit. The sensor produced a static magnetic field of 71.1 mT (resonant frequency:3.027 MHz) in a 50 mm×50 mm plane locating 75 mm above the sensor's surface. Preliminary nondestructive measurement of wood moisture was carried out with the sensor. The moisture distribution in the radical direction of a cylindrical wood sample was scanned. Variations in transverse relaxation time (T2) from the bark to core were obtained. Evaporation of moisture during wood drying was also measured with the UMR sensor. Experimental results showed that:the peak of long T2 component in the T2 spectrum moved to left and the peak integral area decreased gradually during drying. The integral area was proportional to the moisture content of the sample. The work presents a portable UMR device for wood research which may potentially be used for nondestructive moisture measurement on living trees in situ.

Published
2017
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6. High n-type and p-type conductivities and power factors achieved in a single conjugated polymer

Author

Yu, Zi-Di, primary, Lu, Yang, additional, Wang, Zi-Yuan, additional, Un, Hio-Ieng, additional, Zelewski, Szymon J., additional, Cui, Ying, additional, You, Hao-Yang, additional, Liu, Yi, additional, Xie, Ke-Feng, additional, Yao, Ze-Fan, additional, He, Yu-Cheng, additional, Wang, Jie-Yu, additional, Hu, Wen-Bing, additional, Sirringhaus, Henning, additional, and Pei, Jian, additional

Published
2023
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14. Adaptive Decoding Algorithm With Variable Sliding Window for Double SC-LDPC Coding System

Author

Lian, Qiu-Fang, Chen, Qiwang, Zhou, Lin, He, Yu-Cheng, and Xie, Xianzhong

Abstract

In this letter, an adaptive decoding algorithm with a variable sliding window for joint source-channel coding (JSCC) scheme based on double spatially coupled low-density parity-check (DSC-LDPC) codes is investigated. For the traditional sliding window decoding (SWD) algorithm, one or more errors occurring in a decoding window may affect the decoding of the next window, which will trigger error propagation. To mitigate the effects, a window extension algorithm based on average log-likelihood ratios (LLRs) will be proposed, but the implement of extension implies higher decoding complexity. In order to trade-off the error rate performance and complexity, the source and channel threshold that determines the window extension are analyzed. In the simulation, the proposed SWD algorithm with acceptable complexity has better error rate performance in the water fall region and the error floor region.

Published
2023
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18. An analysis of the orthogonality structures of convolutional codes for iterative decoding

Author

He, Yu-Cheng and Haccoun, David

Subjects
Algorithm, Technology application, Information theory -- Research, Algorithms -- Research, Algorithms -- Technology application
Abstract

The structures of convolutional self-orthogonal codes and convolutional self-doubly-orthogonal codes for both belief propagation and threshold iterative decoding algorithms are analyzed on the basis of difference sets and computation tree. It is shown that the double orthogonality property of convolutional self-doubly-orthogonal codes improves the code structure by maximizing the number of independent observations over two successive decoding iterations while minimizing the number of cycles of lengths 6 and 8 on the code graphs. Thus, the double orthogonality may improve the iterative decoding in both convergence speed and error performance. In addition, the double orthogonality makes the computation tree rigorously balanced. This allows the determination of the best weighing technique, so that the error performance of the iterative threshold decoding algorithm approaches that of the iterative belief propagation decoding algorithm, but at a substantial reduction of the implementation complexity. Index Terms--Belief propagation, convolutional self-doubly-orthogonal codes, convolutional self-orthogonal codes, iterative decoding, threshold decoding.

Published
2005

25. l2-Box ADMM Decoding for LDPC Codes Over ISI Channels.

Author

Jiao, Xiaopeng, Liu, Haiyang, Mu, Jianjun, and He, Yu-Cheng

Subjects
INTERSYMBOL interference, ERROR rates, TANNER graphs, SIGNAL-to-noise ratio, LOW density parity check codes
Abstract

The alternating direction method of multipliers (ADMM) has been adapted for decoding low-density parity-check (LDPC) codes over intersymbol interference (ISI) channels in order to reduce the complexity of the traditional Turbo equalization (TE) method. However, the error rate performance of ADMM decoding may be degraded in certain ISI channels when compared with the TE at high signal-to-noise ratio regions. In order to address the problem, we derive a novel ADMM-based decoding method, called l2-box ADMM decoding, for LDPC codes over ISI channels. By introducing suitable penalty functions to l2-box ADMM decoding, we present an enhanced method, called l2-box ADMM penalized decoding, to further improve the performance. Simulation results on several ISI channels indicate that the proposed l2-box ADMM penalized decoding can achieve better error rate performances compared with the TE and the existing ADMM penalized decoding methods, especially for ISI channels with long memory, while maintaining the low-complexity advantage of the ADMM penalized decoding. [ABSTRACT FROM AUTHOR]

Published
2021
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41. Analysis and proof of the stability condition for low-density erasure codes

Author

Mu Jian-Jun, He Yu-Cheng, and Wang Xin-Mei

Subjects
Discrete mathematics, symbols.namesake, Theoretical computer science, Computer science, Convergence (routing), Stability (learning theory), symbols, Bipartite graph, Graph theory, Fixed point, Erasure code, Poisson distribution, Numerical stability
Abstract

Based on the known principle of fixed points in mathematical analysis, a sufficient convergence condition for erasure codes is shown. Moreover, it is pointed out that this general convergence condition is weaker than the convergence condition available. Finally, for erasure codes constructed from bipartite graphs with heavy-tail/Poisson sequences we show a necessary and sufficient condition for the algorithm to finish successfully.

Published
2002
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50. Muskingum Model for Furrow Irrigation

Author

Singh, Vijay P. and He, Yu‐Cheng

Abstract

A mathematical model, based on volume balance and Muskingum type storage‐discharge relation, is presented for design and evaluation of furrow irrigation systems. Three field data sets from Colorado farms are used to test the model. The Muskingum model is simple and found to effectively simulate the hydraulics of every phase of furrow irrigation. The relative error of simulated results is less than 7&percent; for predicted advance, less than 4.7&percent; for outflow during storage phase, less than 5&percent; for recession, and less than 7&percent; for opportunity time. More testing is, however, necessary to define limitations and strengths of the model, and to enable regionalization of the model parameters.

Published
1988

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