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Carrier frequency disturbance distributions on GPS during equatorial ionospheric scintillation

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Journal of Systems Engineering and Electronics 2020年第6期31卷 1308-1317页

作者： ZHU Xuefen lin mengying CHEN Xin CHEN Xiyuan Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology of Ministry of Education School of Instrument Science and EngineeringSoutheast UniversityNanjing 210096China School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

In the equatorial region,deep amplitude fading in global positioning system(GPS)signals frequently occurs during the strong ionospheric scintillation,it can lead to the loss of lock in GPS carrier tracking loops,and result in increased positioning error and even navigation interruption.The relationships between amplitude scintillation indices and detrended carrier frequency are investigated,based on GPS L1 C/A signals during the last peak of the solar cycle at the low latitude site of São Josédos Campos,Brazil(23.2S,45.9W)from 2013 to 2015.Corresponding mathematic model of the probability distribution function is built for the first time to provide statistical analysis on the above relationships.The results show that the standard carrier frequencies reveal an almost linear relation with the amplitude scintillation indices.Moreover,the frequency widths of detrended frequency are proportional to levels of amplitude scintillation when the value of the peak probability is lower than the corresponding boundary.A conclusion can be drawn that different levels of amplitude scintillation will influence the fluctuation of the carrier frequency.The analysis will provide useful guidance to set the receiver’s bandwidth with respect to the different scintillation levels and design the advanced tracking algorithms to improve the robustness and precision of the GPS receiver.

关键词： ionospheric scintillation carrier frequency disturbance probability distribution bandwidth

MIMO-FSK non-coherent detection with spatial multiplexing in fast-fading environment

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The Journal of China Universities of Posts and Telecommunications 2020年第5期27卷 47-54页

作者： Zheng lin Wang Zhen Chen Jianmei lin mengying Deng Xiaofang Guangxi Key Lalxiralory of Wireless Wideband Communications and Signal Processing Guilin University of Electronic TechnologyGuilin 541004China Science and Technology on Communication Networks Laboratory Shijiazhuang 050081China

Accurate estimationand real-time compensation for phase offset and Doppler shift are essential for coherent multi-input multi-output(MIMO)systems.Here,a spatial multiplexing MIMO scheme with non-coherent frequency-shift keying(FSK)detection is proposed.It is immune to random phase interference and Doppler shift while increasing capacity.It is valuable that the proposed spatial multiplexing MIMO based on energy detection(ED)is equivalent to a linear system,and there is no mutual interference caused by the product of simultaneous signals in square-law processing.The equivalent MIMO channel model is derived as a real matrix,which remains maximal multiplexing capacity and reduces the channel estimation complexity.Simulation results show that the proposed scheme has outstanding performance over Rician flat fading channel,and experimental system obtains four times the capacity through 4 antennas on both transmitter and receiver.

关键词： non-coherent MIMO MIMO-FSK spatial multiplexing experimental system

Detection and Analysis of Strong Ionospheric Scintillation in Equatorial Region

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Instrumentation 2021年第4期8卷 1-8页

作者： ZHU Xuefen lin mengying LU Zhengpeng CHEN Xiyuan Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology of Ministry of Education School of Instrument Science and EngineeringSoutheast UniversityNanjing 210096China

To detect the occurrence of ionospheric scintillation in the equatorial region,a coherent/non-coherent integration method is adopted on the accumulation of intermediate frequency(IF)signal and local code,in the process of signal acquisition based on software receiver.The processes of polynomial fitting and sixth-order Butterworth filtering are introduced to detrend the tracking results.Combining with ionospheric scintillation detection algorithm and preset thresholds,signal acquisition and tracking,scintillation detection,positioning solution are realized under the influence of strong ionospheric scintillation.Under the condition that the preset threshold of amplitude and carrier phase scintillation indices are set to 0.5 and 0.15,and the percentage of scin-tillation occurrence is 50%,respectively,PRN 12 and 31 affected by strong amplitude scintillation are detected effectively.Results show that the positioning errors in the horizontal direction are below 5m approximately.The software receiver holds performances of accurate acquisition,tracking and positioning on the strong ionospheric scintillation conditions,which can provide important basis and helpful guidance for relevant research on ionospheric scintillation,space weather and receiver design with high performance.

关键词： Ionospheric Scintillation,Acquisition and Tracking Positioning Error,Coherent/Non-coherent Integration,Detrending

Ferrihydrite transformation impacted by coprecipitation of lignin:Inhibition or facilitation?

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Journal of Environmental Sciences 2024年第5期139卷 23-33页

作者： lin Liu Zhihui Yang Weichun Yang Wen Jiang Qi Liao mengying Si Feiping Zhao School of Metallurgy and Environment Central South UniversityChangsha 410083China Chinese National Engineering Research Center for Control&Treatment of Heavy Metal Pollution(CNERC-CTHMP) Changsha 410083China

Lignin is a common soil organic matter that is present in soils,but its effect on the transformation of ferrihydrite(Fh)remains unclear.Organic matter is generally assumed to inhibit Fh transformation.However,lignin can reduce Fh to Fe(Ⅱ),in which Fe(Ⅱ)-catalyzed Fh transformation occurs.Herein,the effects of lignin on Fh transformation were investigated at 75℃ as a function of the lignin/Fh mass ratio(0-0.2),pH(4-8)and aging time(0-96 hr).The results of Fh-lignin samples(mass ratios=0.1)aged at different pH values showed that for Fh-lignin the time of Fh transformation into secondary crystalline minerals was significantly shortened at pH 6 when compared with pure Fh,and the Fe(Ⅱ)-accelerated transformation of Fh was strongly dependent on pH.Under pH 6,at low lignin/Fh mass ratios(0.05-0.1),the time of secondary mineral formation decreased with increasing lignin content.For high lignosulfonate-content material(lignin:Fh=0.2),Fh did not transform into secondary minerals,indicating that lignin content plays a major role in Fh transformation.In addition,lignin affected the pathway of Fh transformation by inhibiting goethite formation and facilitating hematite formation.The effect of coprecipitation of lignin on Fh transformation should be useful in understanding the complex iron and carbon cycles in a soil environment.

关键词： Ferrihydrite transformation Lignin Hematite Goethite Fe(Ⅱ)-catalyzed Reactive Fe(Ⅲ)species

科教融合背景下新任导师培养研究生的策略——以非线性控制系统课程为载体

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化工高等教育 2024年第2期41卷 124-129页

作者：黄自鑫林梦颖卢俊杰周耀胜胡航武汉工程大学电气信息学院湖北武汉430205 武汉工程大学创新创业学院湖北武汉430205

非线性控制系统课程是一门理论与实践相结合的课程,是控制科学与工程专业新工科人才培养的基础。在科教融合背景下,新任导师针对课程教学中存在的问题,结合三维共建的科研能力指导体系和课程教学大纲,设计并举办研讨论坛,要求学生通过... 详细信息

非线性控制系统课程是一门理论与实践相结合的课程,是控制科学与工程专业新工科人才培养的基础。在科教融合背景下,新任导师针对课程教学中存在的问题,结合三维共建的科研能力指导体系和课程教学大纲,设计并举办研讨论坛,要求学生通过演讲汇报等形式进行模拟汇报。教学实践表明,学生的课程成绩显著提高,科研创新等综合能力得到充分锻炼与培养,新工科人才培养质量稳步提升。

关键词：科教融合新任导师非线性控制系统论坛模式

科教融合视域下研究生的数字化培养路径探索——以“非线性控制系统”课程为例

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湖北理工学院学报 2024年第2期40卷 71-75页

作者：黄自鑫卢俊杰林梦颖邹蝶谭浩然武汉工程大学电气信息学院湖北武汉430205 湖南大学电气与信息工程学院湖南长沙410082

当代信息技术的高速发展极大拓宽了学习路径和教学方式,数字化课程建设已经成为教育领域重要的发展趋势。为探索科教融合视域下研究生的数字化培养路径,以适应新时代需求,文章梳理了“非线性控制系统”课程的开设现状,明确了数字化时代... 详细信息

当代信息技术的高速发展极大拓宽了学习路径和教学方式,数字化课程建设已经成为教育领域重要的发展趋势。为探索科教融合视域下研究生的数字化培养路径,以适应新时代需求,文章梳理了“非线性控制系统”课程的开设现状,明确了数字化时代课程培养目标的新需求,同时以课程教学过程为载体,探索了一种全过程数字化教学路径。整合数字资源开展课前教学,利用仿真软件融入课中案例,分解科研项目纳为课后实践,并结合教学平台建立多元教学评价体系。教学实践表明,学生在整体成绩提升的同时,数字素养得到全面培养。

关键词：科教融合教育数字化 “非线性控制系统”课程研究生培养数字素养

基于改进的多因素SVM算法的太阳射电暴强度检测

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Journal of Southeast University(English Edition) 2022年第1期38卷 20-26页

作者：罗铱镅祝雪芬林梦颖杨帆涂刚毅东南大学仪器科学与工程学院南京210096 南京信息工程大学电子与信息工程学院南京210044

为实现对太阳射电暴(SRBs)强度的自动检测,提出了一种基于改进的多因素支持向量机(SVM)的SRBs强度检测方法.首先,分析SRBs对全球导航卫星系统(GNSS)信号的影响,提取能够反映接收站点SRBs强度的特征向量.根据太阳射电流量对SRBs强度进行... 详细信息

为实现对太阳射电暴(SRBs)强度的自动检测,提出了一种基于改进的多因素支持向量机(SVM)的SRBs强度检测方法.首先,分析SRBs对全球导航卫星系统(GNSS)信号的影响,提取能够反映接收站点SRBs强度的特征向量.根据太阳射电流量对SRBs强度进行分类标签,不同标签对应不同SRBs强度类型,训练样本由特征向量及其标签组成.其次,将具有不同标签的训练样本输入SVM分类器,进行一对一训练,得到最优分类模型.最后,将最优分类模型合成为改进的多因素SVM分类器,用于自动识别更新后的SRBs样本.实验结果表明,对于历史SRBs事件,当太阳入射角大于20°时,SRBs强度检测的平均准确率在90%以上.该算法综合考虑了多种因素,可进行SRBs强度的自动检测,与其他方法相比,该方法不依赖射电望远镜,节约了成本且检测精度更高.

关键词：全球导航卫星系统太阳射电爆发改进的多因素支持向量机检测精度

阳-非离子型表面活性剂醇醚季铵盐的合成及性能

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石油化工 2023年第7期52卷 938-945页

作者：蔺孟莹李方旭陈钊蒋建中崔正刚江南大学化学与材料工程学院合成与生物胶体教育部重点实验室江苏无锡214122

以Guerbet醇醚(C_(24)PO_(10)EO_(10)OH)非离子型表面活性剂为原料经氯代和季铵化反应合成了一种含支链烷基的醇醚季铵盐(C_(24)PO_(10)EO_(10)-TAC)。实验结果表明,这种新型的阳-非离子型表面活性剂具有优良的耐温耐盐性,当含量为0.3%... 详细信息

以Guerbet醇醚(C_(24)PO_(10)EO_(10)OH)非离子型表面活性剂为原料经氯代和季铵化反应合成了一种含支链烷基的醇醚季铵盐(C_(24)PO_(10)EO_(10)-TAC)。实验结果表明,这种新型的阳-非离子型表面活性剂具有优良的耐温耐盐性,当含量为0.3%(w)时,对水溶液中NaCl,CaCl_(2),Na_(2)SO_(4)三种无机盐的容忍度分别可达186000,170000,155000 mg/L,且在80℃下密封保存30 d后,有效物浓度保持率高达98.5%。这种表面活性剂在碳酸盐岩/水界面的吸附量仅为3.08×10^(-7)mol/g(0.45 mg/g),显著低于传统的阳离子型表面活性剂,同时可有效提高碳酸盐岩表面的亲水性。将C_(24)PO_(10)EO_(10)-TAC与亲水性非离子表面活性剂烷基糖苷APG-1214以及另一种阳-非离子型表面活性剂C_(18)PO_(25)EO_(20)-TAC复配,得到的二元或三元表面活性剂混合物可在总含量为0.06%~1.00%(w)的范围内将相关原油/模拟盐水(矿化度75346 mg/L)的界面张力降至超低。

关键词：阳-非离子型表面活性剂碳酸盐岩吸附润湿性界面张力

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移动网络中多用户下行非相干MIMO通信

无线电工程 2021年第8期51卷 773-778页

作者：林梦莹郑霖杨超桂林电子科技大学信息与通信学院广西桂林541004 广西无线宽带通信与信号处理重点实验室广西桂林541004

非相干多输入多输出(Multiple Inputs Multiple Outputs,MIMO)检测不仅具有抗随机相位干扰,对多普勒频偏不敏感的特点,还可以获得空分复用增益。针对多用户下行非相干MIMO系统中的共信道干扰问题,通过理论推导及仿真验证了预编码算法能... 详细信息

非相干多输入多输出(Multiple Inputs Multiple Outputs,MIMO)检测不仅具有抗随机相位干扰,对多普勒频偏不敏感的特点,还可以获得空分复用增益。针对多用户下行非相干MIMO系统中的共信道干扰问题,通过理论推导及仿真验证了预编码算法能够有效解决移动网络中多用户下行随相处理系统的干扰问题。通过仿真给出了莱斯信道下多用户非相干MIMO系统与多用户相干MIMO系统的性能比较,验证了非相干MIMO在多用户环境下的可行性,以及其抗随机相位干扰、抗频偏的特性。

关键词：多用户多输入多输出非相干检测预编码空分复用