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Mature typhoon “cloud gyro” model and numerical simulation study

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Science China Earth Sciences 2020年第5期63卷 749-756页

作者： Xiaogang HUANG xiangcheng li Xiaoping CHENG Chenxi ZHANG Juli DING College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China PLA Troop 92664 Haiyang 265100China

Due to the coarse temporal resolution of the best track databases for typhoons,some small-scale characteristics of typhoon motion have been *** order to reveal the fine features of typhoon motion,the dense cloud within the radius of maximum wind(RMW)of mature typhoons,defined as a“cloud gyro”that simultaneously spins around its own rotational axis and precesses around the vertical axis,is approximated to a rigid *** on the principles of gyrodynamics,the derived mathematical model of a typhoon track indicates that typhoon movement is composed of translational motion governed by the steering flow and superimposed precessional motion that manifests as the inherent characteristics of typhoon tracks,especially with the external *** temporal resolution numerical simulation of a real case verifies the conclusion of this study,which is that the smaller the RMW,the larger the tangential wind speed or the larger the external torque,and the more obviously precessional motion manifests.

关键词： Mature typhoon Cloud gyro Precession angular velocity

Two-Stage Constructions for the Rate-Compatible Shortened Polar Codes

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Tsinghua Science and Technology 2023年第2期28卷 269-282页

作者： Chunjie li Haiqiang Chen Zelin Wang Youming Sun xiangcheng li Tuanfa Qin School of Computer Electronics and Information and Guangxi Colleges and Universities Key Laboratory of Multimedia Communications and Information ProcessingGuangxi UniversityNanning 530004China Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education Guangxi UniversityNanning 530004China

In this paper,we propose the two-stage constructions for the rate-compatible shortened polar(RCSP)*** the Stage-I construction,the shortening pattern and the frozen bit are jointly designed to make the shortened bits be completely known by the ***,a distance-greedy algorithm is presented to improve the minimum Hamming distance of the *** design the remaining Stage-II frozen bits,three different construction algorithms are further presented,called the Reed-Muller(RM)construction,the Gaussian Approximation(GA)construction,and the RM-GA *** we give the row weight distribution numerical results of the generator matrix after the Stage-I and Stage-II constructions,which shows that the proposed constructions can efficiently increase the minimum Hamming *** results show that the proposed RCSP codes have excellent frame error rate(FER)performances at different code lengths and code *** specifically,the RM-GA construction performs best and can achieve at most 0.8 dB gain compared to the Wang14 and the quasi-uniform puncturing(QUP)*** RM construction is designed completely by the distance-constraint without channel evaluation thus has the simplest ***,it still has better FER performance than the existing shortening/puncturing schemes,especially at high signal noise ratio(SNR)region.

关键词： polar codes rate-compatibility Reed-Muller codes Hamming distance shortening

Optical transparent metamaterial structure for microwave-infrared-compatible camouflage based on indium tin oxide

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中国科学:技术科学英文版 2023年第10期66卷 2850-2861页

作者： LUO Hui XIONG Yao CHENG YongZhi CHEN Fu li xiangcheng School of Information Science and Engineering Wuhan University of Science and TechnologyWuhan 430081China State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081China

A visible transparent metamaterial absorber was designed and fabricated with ultrabroadband microwave absorption and low infrared emissivity to meet the increasing demand for multispectral compatible camouflage. The absorber was fabricated with a low-infrared emissive layer at the top, a microwave-absorbing layer in the middle, and a reflective layer at the bottom, which were separated by polymethyl methacrylate plates. The absorber showed an average visible transmittance of 55%, infrared emissivity of ~0.37, and effective microwave absorption bandwidth of 32.1 GHz with a total thickness of 3.0 mm. Furthermore,microwave absorption exhibited wide-angle stability and polarization insensitivity characteristics. The mechanism of microwave attenuation was further explored through effective electromagnetic parameters as well as surface current, electric field, magnetic field, and energy loss density distributions. The experimental results were consistent with those of the simulations and calculations, indicating the potential of the designed metamaterial absorber for future applications in multispectral compatible camouflage.

关键词： optical transparent microwave absorption metamaterial low infrared emissivity indium tin oxide

Al-SCM-25分子筛的合成及其催化性能研究

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化学反应工程与工艺 2024年第2期40卷 142-149页

作者：付文华李相呈陶伟川中石化(上海)石油化工研究院有限公司绿色化工与工业催化全国重点实验室上海201208

将Al引入硅锗分子筛骨架是提升其骨架稳定性、增强酸性的有效手段。本工作首次采用直接合成法将Al引入SCM-25分子筛骨架,制备了不同铝含量的Al-SCM-25分子筛。考察了水量、铝含量、晶种添加对合成的影响,发现与SCM-25分子筛的合成相比,A... 详细信息

将Al引入硅锗分子筛骨架是提升其骨架稳定性、增强酸性的有效手段。本工作首次采用直接合成法将Al引入SCM-25分子筛骨架,制备了不同铝含量的Al-SCM-25分子筛。考察了水量、铝含量、晶种添加对合成的影响,发现与SCM-25分子筛的合成相比,Al-SCM-25分子筛需要在更高的水量和晶种存在的条件下才可以完全结晶。采用N_(2)物理吸附、^(27)Al魔角旋转固体核磁(^(27)Al MAS NMR)、氨气程序升温脱附(NH_(3)-TPD) 等手段表征了Al-SCM-25分子筛的孔结构性质、铝配位状态及酸性。结果表明,Al-SCM-25具有与SCM-25相近的比表面积和微孔体积;大部分铝以四配位形式进入骨架中,从而产生了比SCM-25分子筛数量更多、强度更高的酸性位。在环己酮Baeyer-Villiger氧化制备 ε-己内酯反应中,Al-SCM-25分子筛相较SCM-25分子筛表现出更高的环己酮转化率和目标产物的收率,并且具有较好的循环稳定性。

关键词：硅锗铝分子筛 SCM-25 分子筛合成理化性质 Baeyer-Villiger氧化

动态扰动辅助的串行抵消双比特翻转Polar译码算法

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电讯技术 2024年第1期64卷 126-131页

作者：曾俏丽陈海强周泉刘远博孙友明黎相成广西大学计算机与电子信息学院南宁530004 广西多媒体通信与网络技术重点实验室南宁530004

针对串行抵消翻转译码算法(Successive Cancellation Flip,SCF)受限于单比特翻转而性能提升有限问题,提出了一种双比特翻转译码算法(Successive Cancellation Flip with 2 Bits,SCF2)。针对SCP算法扰动方差初始值固定的问题,设计了一种... 详细信息

针对串行抵消翻转译码算法(Successive Cancellation Flip,SCF)受限于单比特翻转而性能提升有限问题,提出了一种双比特翻转译码算法(Successive Cancellation Flip with 2 Bits,SCF2)。针对SCP算法扰动方差初始值固定的问题,设计了一种扰动方差可随码长和码率变化的改进SCP算法。在此基础上,结合翻转和扰动机制,提出了一种动态扰动辅助的串行抵消双比特翻转(Dynamic Perturbation-Aided SCF2,DPA-SCF2)译码算法,并对其译码复杂度和性能进行了分析。仿真结果显示,相比于列表长度为4的循环冗余校验辅助串行抵消列表(Cyclic Redundancy Check Aided Successive Cancellation list,CA-SCL)译码算法,所提算法最大可获得约0.5 dB的性能增益。

关键词： Polar码串行抵消翻转(SCF)译码串行抵消扰动(SCP)译码动态扰动

具有超低镍负载的Ni-C_(3)N_(4)高效催化5-羟甲基糠醛氢解制2,5-二甲基呋喃

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Chinese Journal of Catalysis 2024年第5期60卷 253-261页

作者：曲虹宇胡文德李相呈徐睿韩笑李俊杰陆怡卿叶迎春王传明王振东杨为民华东理工大学化工学院上海200237 中石化(上海)石油化工研究院有限公司绿色化工与工业催化全国重点实验室上海201208

生物质平台化合物的选择性氢解对生产可持续化学品和燃料具有重要意义.2,5-二甲基呋喃(DMF)是一种重要的生物基化学品,其不仅可作为汽油添加剂,还可与乙烯发生Diels-Alder环加成脱水反应直接合成生物基对二甲苯.DMF主要通过5-羟甲基糠醛... 详细信息

生物质平台化合物的选择性氢解对生产可持续化学品和燃料具有重要意义.2,5-二甲基呋喃(DMF)是一种重要的生物基化学品,其不仅可作为汽油添加剂,还可与乙烯发生Diels-Alder环加成脱水反应直接合成生物基对二甲苯.DMF主要通过5-羟甲基糠醛(HMF)氢解制备.当以氢气为氢源时,常用的催化剂体系包括贵金属(如Ru,Pt,Pd)及多种非贵金属(如Ni,Cu,Co)复合催化剂体系.虽然上述催化剂表现出良好的催化性能,但是贵金属的高成本以及非贵金属复合催化剂的回收难等问题阻碍了其工业应用.因此,利用单一非贵金属催化剂实现高效HMF氢化制DMF具有重要意义.本文采用简单的配位-浸渍-热解法制备了超低Ni负载的非贵金属Ni-C_(3)N_(4)/HC催化剂,Ni负载量低至0.86 wt%.在190℃及1.5 MPa氢气条件下,经过4 h反应,HMF完全转化,DMF产率达到94.2%,DMF生产能力可达12.8 mmolDMF mmolNi-1 h^(-1),在已报道的Ni,Co和Cu基催化剂中处于较高水平.此外,Ni-C_(3)N_(4)/HC催化剂表现出良好的稳定性,在固定床反应器中连续反应120 h未见明显失活.透射电镜结果表明,Ni物种高度分散在活性炭载体上,其平均粒径约为2.6 ***纳米颗粒被约1.3 nm厚的C_(3)N_(4)壳层紧密包裹,有效稳定了Ni纳米颗粒并抑制了其在反应过程中团聚.X射线能谱分析显示,Ni和N元素呈现均匀分布,表明可能形成了Ni_(3)N物种.X射线光电子能谱和电子能量损失谱结果进一步证实了Ni_(3)N物种的存在.密度泛函理论计算结果表明,Ni_(3)N是氢解反应的本征活性组分,它表现出良好的C-O键活化性能.推测反应主要遵循HMF先转化为MF(5-甲基糠醛),再转化为MFA(5-甲基-2-呋喃甲醇),最终生成DMF的路线进行.鉴于Ni-C_(3)N_(4)/HC催化剂中的Ni_(3)N物种表现出了较好的C-O键活化性能,进一步考察了该催化剂对木质素衍生单体和木质素模型化合物的催化性能.实验结果表明,Ni-C_(3)N_(4)/HC催化剂在C-O键活化断裂加氢反应中表现出广泛的适用性.另外,H_(2)处理的活性炭载体也发挥了重要作用:(1)降低了活性炭的含氧量,提高载体热稳定性,并减弱了载体的酸性,从而有效避免了底物的HMF聚合;(2)有助于Ni物种的均匀分散,减少了NiO物种的生成,增加了Ni_(3)N活性物种的含量,从而提升了催化剂的性能.综上,本文制备了超低Ni负载的非贵金属Ni-C_(3)N_(4)/HC催化剂,其表现出高效的HMF氢解制DMF性能及良好的稳定性.同时,该催化剂对木质素衍生单体和木质素模型化合物也有广泛的适用性.本研究为开发用于生物质加氢和氢解反应的单一非贵金属催化剂提供了新思路.

关键词：生物质 5-羟甲基糠醛 2,5-二甲基呋喃氢解 Ni_(3)N

融合路径度量值和行重特性的Polar码SCL译码算法

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电讯技术 2024年第2期64卷 295-301页

作者：周泉陈海强曾俏丽廖兰娟孙友明黎相成广西大学计算机与电子信息学院南宁530004 广西多媒体通信与网络技术重点实验室南宁530004

首先提出基于初始对数似然比(Log-likelihood Ratio,LR)与路径度量值(Path Metric,PM)的PM-LLR-SCL译码算法,在接收端初始LLR和PM值之间建立映射关系,并通过重排PM值完成翻转功能。其次,提出基于极化码生成矩阵的行重特性和PM值的PM-RW-... 详细信息

首先提出基于初始对数似然比(Log-likelihood Ratio,LR)与路径度量值(Path Metric,PM)的PM-LLR-SCL译码算法,在接收端初始LLR和PM值之间建立映射关系,并通过重排PM值完成翻转功能。其次,提出基于极化码生成矩阵的行重特性和PM值的PM-RW-SCL译码算法,不仅考虑了Polar码的最小码距和极化子信道可靠度,同时将路径分裂每一层的PM值引入到译码策略中,从而提高了译码性能。仿真结果显示,与串行抵消列表比特翻转(Successive Cancellation list Bit-flip,SCLF)相比,提出的PM-LLR-SCL算法最大可获得约0.23 dB的性能增益,而基于路径数量的复杂度降低了约62%;与基于行权重的串行抵消列表翻转译码算法相比,PM-RW-SCL算法最大可获得约1.5 dB的性能增益,而复杂度降低了约39%。

关键词： Polar码串行抵消列表比特翻转译码路径度量值行重特性

An Iterative Detection/Decoding Algorithm of Correlated Sources for the LDPC-Based Relay Systems

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China Communications 2017年第9期14卷 190-198页

作者： Haiqiang Chen Hang Cao xiangcheng li Youming Sun Haibin Wan Tuanfa Qin The School of Computer and Electronic Information Guangxi University Guangxi Key Laboratory of Multimedia Communications and Network Technology Guangxi University Guangxi Colleges and Universities Key Laboratory of Multimedia Communications and Information Processing Guangxi University

An iterative detection/decoding algorithm of correlated sources for the LDPC-based relay systems is presented. The signal from the source-destination(S-D) link is formulated as a highly correlated counterpart from the relay-destination(R-D) link. A special XOR vector is defined using the correlated hard decision information blocks from two decoders and the extrinsic information exchanged between the two decoders is derived by the log-likelihood ratio(LLR) associated with the XOR vector. Such the decoding scheme is different from the traditional turbo-like detection/decoding algorithm, where the extrinsic information is computed by the side information and the soft decoder outputs. Simulations show that the presented algorithm has a slightly better performance than the traditional turbo-like algorithm(Taking the(255,175) EG-LDPC code as an example, it achieves about 0.1 dB performance gains aroundBLER=10^(-4)). Furthermore, the presented algorithm requires fewer computing operations per iteration and has faster convergence rate. For example, the average iteration of the presented algorithm is 33 at SNR=1.8 dB, which is about twice faster than that of the turbo-like algorithm, when decoding the(961,721) QC-LDPC code. Therefore, the presented decoding algorithm of correlated sources provides an alternative decoding solution for the LDPC-based relay systems.

关键词： correlated sources iterative de-coding LDPC codes relay channel

基于可靠度差值特征的自适应判决多元LDPC译码算法

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电讯技术 2024年第6期64卷 945-951页

作者：孙友明韦礼乐黄奕俊莫莉歆黎相成孙洪民广西大学计算机与电子信息学院南宁530004 广西无线宽带通信与信号处理重点实验室(桂林电子科技大学) 桂林541004 广西工业职业技术学院南宁530001

利用变量节点符号可靠度在迭代过程中的分布特征,提出了一种基于可靠度差值特征的自适应判决多元低密度奇偶校验(Low Density Parity Check, LDPC)译码算法。整个迭代过程划分为两个阶段,针对不同阶段节点可靠度的差值特征分别采用不同... 详细信息

利用变量节点符号可靠度在迭代过程中的分布特征,提出了一种基于可靠度差值特征的自适应判决多元低密度奇偶校验(Low Density Parity Check, LDPC)译码算法。整个迭代过程划分为两个阶段,针对不同阶段节点可靠度的差值特征分别采用不同的判决策略:前期阶段,采用传统的基于最大可靠度的判决策略;后期阶段,根据最大、次大可靠度之间的差值特征,设计自适应的码元符号判决策略。仿真结果表明,所提算法在相当的译码复杂度前提下,能获得0.15~0.4 dB的性能增益。同时,对于列重较小的LDPC码,具有更低的译码错误平层。

关键词：多元LDPC码大数逻辑译码自适应判决差值特征