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Novel modified min-sum decoding algorithm for low-density parity-check codes

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The Journal of China Universities of Posts and Telecommunications 2010年第4期17卷 1-5,46页

作者： liu hai-yang , QU wen-ze, liu Bin, LI Jiang-peng, LUO Shi-dong, CHEN Jie Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China Institute of Microelectronics Chinese Academy of Sciences Beijing 100029 China

The problem of improving the performance of min-sum decoding of low-density parity-check （LDPC） codes is considered in this paper. Based on min-sum algorithm, a novel modified min-sum decoding algorithm for LDPC codes is proposed. The proposed algorithm modifies the variable node message in the iteration process by averaging the new message and previous message if their signs are different. Compared with the standard min-sum algorithm, the modification is achieved with only a small increase in complexity, but significantly improves decoding performance for both regular and irregular LDPC codes. Simulation results show that the performance of our modified decoding algorithm is very close to that of the standard sum-product algorithm for moderate length LDPC codes.

关键词： LDPC codes sum-product algorithm min-sum algorithm modified min-sum algorithm

THE IMPACT OF MOUNTAIN TO BASIN WINDS ON THE DIURNAL VARIATION IN FOG OVER THE SICHUAN BASIN, CHINA

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Journal of Tropical Meteorology 2019年第2期25卷 257-268页

作者： ZHANG Fu-ying liu hai-wen ZHU Yu-xiang ZHAO Liang DUAN Bo-long FU Ning Nanjing University of Information Science & Technology Department of Aviation Meteorology Civil Aviation University of China CMA Training Center China Meteorological Administration LASG Institute of Atmospheric Physics Chinese Academy of Sciences Lanzhou Central Meteorological Observatory

There is an increased demand for the accurate prediction of fog events in the Sichuan Basin(SCB) using numerical methods. A dense fog event that occurred over the SCB on 22 December 2016 was investigated. The results show that this dense fog event was influenced by the southwest of a low pressure with a weak horizontal pressure gradient and high relative humidity. This fog event showed typical diurnal variations. The fog began to form at 1800 UTC on 21 December 2016(0200 local standard time on 22 December 2016) and dissipated at 0600 UTC on 22 December 2016(1400 local standard time on 22 December 2016). The Weather Research and Forecasting model was able to partially reproduce the main features of this fog event and the diurnal variation in the local mountain to basin winds. The simulated horizontal visibility and liquid water content were used to characterize the fog. The mountain to basin winds had an important role in the diurnal variation of the fog event. The positive feedback mechanism between the fog and mountain to basin winds was good for the formation and maintain of the fog during the night. During the day, the mountain to basin wind displayed a transition from downslope flows to upslope flows. Water vapor evaporated easily from the warm, strong upslope winds, which resulted in the dissipation of fog during the day. The topography surrounding the SCB favored the lifting and condensation of air parcels in the lower troposphere as a result of the low height of the lifting condensation level.

关键词： mountain to basin winds fog events weather research and forecasting simulations Tibetan Plateau

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糠醛废水处理工程的工艺改造

现代化工 2008年第1期28卷 65-68页

作者：刘研萍刘硕刘文海北京化工大学环境科学与工程系北京100029 哈尔滨工业大学市政与环境工程学院黑龙江哈尔滨150090

某糠醛生产厂排放的废水有机物浓度高、成分复杂、BOD5/COD低,难生物降解,该厂采用"厌氧-好氧-兼氧"为主体的处理工艺,但生产无法正常运行。主要原因是预处理不充分,工艺流程不够合理。提出了工程改造方案,包括采用微电解-絮凝强化预处... 详细信息

某糠醛生产厂排放的废水有机物浓度高、成分复杂、BOD5/COD低,难生物降解,该厂采用"厌氧-好氧-兼氧"为主体的处理工艺,但生产无法正常运行。主要原因是预处理不充分,工艺流程不够合理。提出了工程改造方案,包括采用微电解-絮凝强化预处理,增设中沉池,同时改造某些处理构筑物,强化系统调控等。改造后工程出水能达标排放,运行成本比原工艺增加了0.3元/t。

关键词：糠醛废水微电解絮凝

The anti-endotoxic effect of o-aminobenzoic acid from Radix Isatidis

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Acta Pharmacologica Sinica 2005年第5期26卷 593-597页

作者： Jian-guo FANG~2,Yun-hai liu,wen-qing WANG,Wei XIE,Shu-xian FANG,Hong-gang HANDepartment of Pharmacy,Tongji Hospital,Tongji Medical College,Huazhong University of Science and Technology,Wuhan 430030,China Department of Pharmacy Tongji Hospital Tongji Medical College Huazhong University of Science and Technology Wuhan China

Aim:To study the anti-endotoxic effect of o-aminobenzoic acid(OABA)isolatedfrom Banlangen(BLG).Methods:OABA was extracted and isolated from BLG anddiluted into 0.5% *** concentration of endotoxin(ET)pretreated withOABA was quantitatively detected using Limulus *** inhibition of ET-induced fever by OABA was measured in *** rates of lipopolysaccha-rides(LPS)-induced death in mice pretreated with or without OABA were *** influence of OABA on the release of TNF-α and NO from mac-rophages induced by LPS was examined in ***:After pretreatment withOABA,84.4% of ET was *** ET-induced fever in rabbits decreasedsignificantly and the rate of LPS-induced death in mice dropped from 70% to 20%.The release of TNF-α and NO induced by LPS in mice was inhibited dose-depen-dently when the concentration of OABA was between 0.125% and 0.5%.Conclusion:OABA isolated from BLG has an anti-endotoxic effect.

关键词： Radix Isatidis(Banlangen) o-aminobenzoic acid endotoxin lipopolysaccharides Tachypleus Amebocyte Lysale tumor necrosis factor-α nitric oxide

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经验模态分解在直升机谱特征提取中的应用

哈尔滨工程大学学报 2010年第6期31卷 714-719页

作者：刘文海李关防哈尔滨工程大学水声工程学院黑龙江哈尔滨150001 海军装备部沈阳地区军事代表局辽宁沈阳110003 江苏自动化研究所江苏连云港222006

为了更有效地提取直升机辐射噪声的频谱特征,提出了一种基于经验模态分解(EMD)的特征提取算法.仿真研究表明EMD具有突出信号局部特征且余量可表征信号变化趋势的特性,该算法将目标辐射噪声的频谱构成和EMD的特性相结合,将EMD应用于变换... 详细信息

为了更有效地提取直升机辐射噪声的频谱特征,提出了一种基于经验模态分解(EMD)的特征提取算法.仿真研究表明EMD具有突出信号局部特征且余量可表征信号变化趋势的特性,该算法将目标辐射噪声的频谱构成和EMD的特性相结合,将EMD应用于变换域(信号频谱序列)信号分析,有效的实现了信号连续谱的提取.相比于平滑滤波器法须人为选择最优的α值,且提取的连续谱有滞后性的不足,文中所示方法可自适应的提取信号的连续谱,且在准确无滞后地估计连续谱的同时,对线谱有一定的"增益",为后续的目标识别提供更全面的信息.

关键词：经验模态分解(EMD) 特征提取直升机噪声线谱提取

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活性炭烟气脱硫催化反应速率实验研究

北京科技大学学报 2014年第2期36卷 235-240页

作者：刘应书王海鸿张辉范菲刘文海北京科技大学机械工程学院北京100083

针对活性炭烟气脱硫过程,以吸附质浓度沿床层分布曲线实验为基础,对活性炭脱除SO2的催化反应速率的影响因素进行了探讨.研究发现SO2质量浓度和CO2体积分数对活性炭催化反应速率有显著影响.SO2质量浓度对活性炭催化反应速率影响最大,随着... 详细信息

针对活性炭烟气脱硫过程,以吸附质浓度沿床层分布曲线实验为基础,对活性炭脱除SO2的催化反应速率的影响因素进行了探讨.研究发现SO2质量浓度和CO2体积分数对活性炭催化反应速率有显著影响.SO2质量浓度对活性炭催化反应速率影响最大,随着SO2质量浓度升高催化反应速率将显著增加,但高SO2质量浓度下催化反应速率将不再增加;体积分数在15%以内的CO2对催化反应速率呈线性抑制,使得活性炭催化反应速率降低约30%;烟气线速度在0.14～0.3 m·s-1之间变化时对催化反应速率的影响效果不大.

关键词：烟气脱硫活性炭催化作用反应速率二氧化硫

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射电天文用太赫兹三通带频率选择表面设计

物理学报 2015年第17期64卷 103-109页

作者：刘海文占昕任宝平华东交通大学信息工程学院射频通信与传感器网络江西省重点实验室中国人民解放军73681部队

本文设计一种基于单屏改进型开口谐振环(SRR)的太赫兹频率选择表面(FSS).改进型SRR谐振单元由具有开口缝的金属贴片组成,开口缝的物理尺寸会影响其阶跃特征阻抗特性.本文通过对改进型SRR单元结构建立LC等效电路模型,提取等效电路模型参... 详细信息

本文设计一种基于单屏改进型开口谐振环(SRR)的太赫兹频率选择表面(FSS).改进型SRR谐振单元由具有开口缝的金属贴片组成,开口缝的物理尺寸会影响其阶跃特征阻抗特性.本文通过对改进型SRR单元结构建立LC等效电路模型,提取等效电路模型参数,并结合传输线理论,得到FSS的基频计算公式和谐波关系式.相比于传统均匀SRR,本文所提出的改进型SRR多频带传输的控制更为灵活.基于此特点,设计了一款中心频率依次为0.46 THz,0.86 THz和1.03 THz,可应用于射电天文的三通带太赫兹FSS.采用电磁仿真软件对影响该FSS传输特性的关键参数、周期间隔、小型化程度以及入射角敏感性等重要指标进行分析研究.结果表明,改进型SRR三通带FSS在三个通带内的反射系数分别为-37.6 dB,-13 dB和-19.6 dB,在0°-60°范围内均具有稳定的频率响应特性,且具有小型化程度高、损耗低等特点.这种三通带FSS在太赫兹频段射电天文方面有潜在的应用价值.

关键词：频率选择表面太赫兹三通带开口谐振环