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Flexural Behavior of RC Beams with NSM Prestressed Helical Rib Steel Wire
Meixiang Zhang,Xiaolin Yang,Yahong Ding,Ping Xu,Bo Sun,Xiaoyi Zhang,Xianggang Zhang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.9
The reinforcement technique of near-surface mounted?NSM?prestressed helical rib steel wire (PHRSW) with wide raw material sources, lower in price and high application value can significantly enhance the flexural behavior of reinforced-concrete (RC) structures. Based on 8 flexural RC beams reinforced with NSM PHRSW, performance of test beams under different groove widths (10 mm, 15 mm and 20 mm) and concrete strengths (C30 and C40) was analyzed, including load-deflection, ductility, flexural capacity, strain of longitudinal steel bar and HRSW, failure mode and crack propagation. The results show that the overall flexural behavior RC beams reinforced with NSM PHRSW was significantly improved. There is a good entirety bearing capacity between the longitudinal reinforcement and PHRSW of reinforced beam with suitable groove size. The comprehensive performance of reinforced beams increases first then decreases, with the increase of groove size. The higher the strength of concrete, the more significant the influence of groove size. There is an optimal match between groove width and concrete strength for RC beams reinforced with NSM PHRSW. Considering comprehensive property of reinforced beams, groove width with 15mmwas best in this research. The results can make the research of RC beams reinforced with NSM PHRSW more comprehensive and in-depth, and provide design basis for its engineering application.
Iterative MMSE-based soft MIMO detection with parallel interference cancellation
Zhang, Meixiang,Ahmed, Saleem,Kim, Sooyoung IET 2017 IET COMMUNICATIONS Vol.11 No.11
<P>Minimum mean square error (MMSE)-based techniques are often used for the joint iterative detection and decoding that is for coded multi-input-multi-output (MIMO) system due to a sound complexity and the performance trade-off. This study proposes an enhanced MMSE-based soft MIMO-detection scheme by using three main ideas. The first idea is an efficient complexity-reduced soft-bit estimation technique, the second one is a performance improvement method utilised inside the MMSE detection process, and the third one is a complexity-reduced soft-symbol estimation method for quadrature amplitude modulation. The proposed ideas enable the interference-cancellation processes to be activated in parallel on each symbol layer, thereby reducing the processing time. The simulation results show that the proposed method efficiently contributes to the improvement of the performance in addition to its reduction of the linear-order complexity.</P>
Formulation of Joint Iterative Decoding for Raptor Codes
Zhang, Meixiang,Kim, Sooyoung,Kim, Won-Yong,Cho, Yong-Hoon Korea Multimedia Society 2014 멀티미디어학회논문지 Vol.17 No.8
Raptor codes are a class of rateless codes originally designed for binary erasure channels. This paper presents a compact set of mathematical expressions for iterative soft decoding of raptor codes. In addition, an early termination scheme is employed, and it is embedded in a single algorithm with the formula. In the proposed algorithm, the performance is enhanced by adopting iterative decoding, both in each inner and outer code and in the concatenated code itself between the inner and outer codes. At the same time, the complexity is reduced by applying an efficient early termination scheme. Simulation results show that our proposed method can achieve better performance with reduced decoding complexity compared to the conventional schemes.
Meixiang Zhang,Sooyoung Kim IET 2014 IET COMMUNICATIONS Vol.8 No.1
<P>In this study, the authors propose a compact soft demodulation method for <I>M</I>-ary modulation schemes defined in the Digital Video Broadcasting via Satellite - Second Generation (DVB-S2) system. They first derive a conventional soft demodulation method for quadrature phase shift keying and 8-ary phase shift keying with a linear order of complexity, and apply this to the modulation schemes defined in DVB-S2. In particular, they propose a new constellation for 32-ary amplitude and phase shift keying (32-APSK), which provides better performance, regardless of the soft demodulation scheme. In addition, the proposed constellation enables us to apply a very simple and efficient soft demodulation method. The proposed soft demodulation method estimates the soft information by simple distance calculation, and greatly reduces the computational complexity, compared with maximum-log-likelihood detection. They demonstrate the bit error rate (BER) performance of various soft demodulation methods, combined with the low density parity check codes specified in DVB-S2. The BER simulation results reveal that the proposed constellation for 32-APSK can achieve better performance than the conventional one, regardless of the soft demodulation method. In addition, the proposed soft demodulation method can highly reduce the computational complexity, with reasonable performance degradation.</P>
Soft decoding method for systematic raptor codes
Meixiang Zhang,Sooyoung Kim,Jin Yeong Chang,Won-Yong Kim IET 2015 IET COMMUNICATIONS Vol.9 No.16
<P>Raptor codes are a class of rateless codes that were originally designed for binary erasure channels. To enhance their performance, multiple soft iterative loops can be employed in the decoder. In this study, the authors propose a method to construct modified Tanner graphs for systematic raptor codes in order to increase the efficiency of soft decoding. A modified Tanner graph is drawn in terms of bit and check nodes for each component code, instead of encoding and information nodes, as in conventional Tanner graphs, for its component Luby transform codes. This modified Tanner graph enables the use of a more simplified soft iterative decoding algorithm and provides improved decoding performance compared with the conventional method. In addition, they propose an efficient joint iterative soft decoding method with a parallel process to speed up the iterative decoding. The simulation results in this study reveal that the modified Tanner graph works better than the conventional Tanner graph for joint iterative decoding, and that the proposed parallel decoding method can contribute to further enhance the performance as well as the decoding speed by reducing the average number of iterations.</P>