检索结果-南通市图书馆

Frontiers of Environmental Science & Engineering 2024年第4期18卷 91-102页

作者： Zhihao Xian Jun Yan Jingyi Dai Hao Wu Xin Zhang Wenbo Nie fucheng guo Yi Chen Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environment(Ministry of Education) Chongqing UniversityChongqing 400044China College of Environment and Ecology Chongqing UniversityChongqing 400044China

Constructed wetlands(CWs)are widely used to treat secondary ***,simultaneously removing ammonia(NH_(4)^(+)-N)and nitrate(NO_(3)^(–)–N)is challenging because of insufficient oxygen and carbon *** this study,a novel composite material(MPCM)comprising MnO_(2) and polycaprolactone was developed as a substrate for CWs to enhance the synchronous removal of NH_(4)^(+)–N and NO_(3)^(–)–*** CWs with a higher MPCM content(H-CW),lower MPCM content(LCW),and controlled CW(C-CW)exhibited average NH_(4)^(+)–N removal efficiencies of 75.69%,70.49%,and 52.40%,*** 15N isotope tracking technique showed that NH_(4)^(+)–N removal was attributed to anaerobic ammonia oxidation mediated by MnO2 reduction(Mnammox),which accounted for 17.16%–27.24%of the NH_(4)^(+)–N removal in the composite material layers(0–20 cm)of the H-CW and *** richness of ammonia oxidizers in the upper layers(40–50 cm)of the HCW and L-CW further facilitated NH_(4)^(+)–N ***,the average total nitrogen(TN)removal efficiencies of the H-CW and L-CW were 1.99 and 1.59 times that of C-CW,respectively,owing to enhanced denitrification by ***,N_(2)O emissions were reduced by 81.31%and 70.83%in the H-CW and L-CW,*** study provides an effective approach for improving nitrogen removal and reducing N2O emissions during the treatment of secondary effluent by CWs.

关键词： Constructed wetland Nitrogen removal Manganese redox Polycaprolactone Nitrous oxide

已知波形信号的时差频差估计方法研究与性能分析

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

信号处理 2024年第2期40卷 292-300页

作者：刘严朱毅张源郭福成国防科技大学电子科学学院湖南长沙410073

借助深入分析和长期积累,非合作定位系统可以获得关于电视、广播、导航等电磁信号波形的丰富先验信息,对这些信息加以利用有望大幅提高对信号参数的估计精度。该文针对导航、通信等欺骗干扰源及非法用户的无源定位需求,在观测站与辐射... 详细信息

借助深入分析和长期积累,非合作定位系统可以获得关于电视、广播、导航等电磁信号波形的丰富先验信息,对这些信息加以利用有望大幅提高对信号参数的估计精度。该文针对导航、通信等欺骗干扰源及非法用户的无源定位需求,在观测站与辐射源之间存在相对运动的场景下,围绕已知波形信号开展时差频差估计问题研究。首先,通过引入已知的信号波形信息对观测站接收数据进行建模,直观呈现了观测数据与不同观测站信号相对于原始信号时延、频移的关系。随后,充分利用入射信号波形已知这一有利条件,通过估计两个观测站各自的时延和频移,并对不同观测站上的估计结果进行差分,提出了一种针对已知波形信号的双站时差、频差估计方法。在此基础上,该文分析了已知波形信号时频差估计精度的理论下界,揭示了时频差估计精度受观测站接收信号幅度等因素的影响情况,并进一步分析了双站时频差估计精度与单通道时延、频移估计精度之间的关系。最后,借助仿真实验验证了论文所提出的时频差估计方法在不同环境中的参数估计性能,以及信号波形先验信息的利用给时频差参数估计精度带来的提升情况。仿真结果表明,在所设定的信号环境中,该文所提出的方法对低信噪比的适应能力比基于互模糊函数的传统方法增强了15 dB左右;当该方法的参数估计性能达到收敛之后,其时差频差估计精度与CRLB非常吻合。

关键词：时差频差估计已知信号波形运动观测站互模糊函数克拉美-罗界(CRLB)

在线全文

学校读者我要写书评

暂无评论

基于迭代二次优化算法的低截获波形序列设计

电子与信息学报 2024年第5期46卷 2048-2056页

作者：刘强张敏郭福成殷加鹏胡卫东国防科技大学电子科学学院长沙410073

对抗条件下,低截获雷达通过发射特殊波形防止非合作电子侦察系统截获和检测其发射信号,是现代雷达技术的重点研究方向。该文旨在降低电子侦察系统的功率截获概率,在保证目标的辐射能量基础上,针对短时傅里叶变换(STFT)宽带数字侦察接收... 详细信息

对抗条件下,低截获雷达通过发射特殊波形防止非合作电子侦察系统截获和检测其发射信号,是现代雷达技术的重点研究方向。该文旨在降低电子侦察系统的功率截获概率,在保证目标的辐射能量基础上,针对短时傅里叶变换(STFT)宽带数字侦察接收机特点,从能量的时频分布的角度将波形设计技术应用到无源对抗领域。首先,建立STFT宽带数字侦察接收机检测低截获模型,利用2次优化模型,将低截获问题转变为恒包络序列迭代优化问题;然后,为了获得较好的自相关性能,利用辅助标量,将优化模型转化为2次和形式,结合迭代算法得到了所提低截获波形序列;最后,讨论了计算复杂度。从仿真结果上看,所提序列比常见相位编码信号在相同的接收信噪比下具有更优的低截获能力,另外,引入Pareto权对所提序列的自相关特性进行控制,有效地提高了设计灵活性。

关键词：低截获雷达波形设计迭代2次优化

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

基于高维重频特征的雷达辐射源识别方法

现代雷达 2024年第4期46卷 1-7页

作者：徐涛刘章孟郭福成国防科技大学电子科学学院湖南长沙410073

通过提取和利用雷达脉冲间隔高维特征,提出了一种基于决策树的雷达辐射源识别方法。将相邻脉冲间隔所构成的向量作为脉冲的高维特征,以增强不同雷达信号之间的可分性,再利用聚类方法提取脉冲列中的这种特征;然后将该特征构成特征向量,... 详细信息

通过提取和利用雷达脉冲间隔高维特征,提出了一种基于决策树的雷达辐射源识别方法。将相邻脉冲间隔所构成的向量作为脉冲的高维特征,以增强不同雷达信号之间的可分性,再利用聚类方法提取脉冲列中的这种特征;然后将该特征构成特征向量,以表现特征的整体性;随后基于该特征向量构建决策树分类模型;最后将学习到的模型用于未知雷达脉冲列的识别。仿真实验验证了新方法在不同数据量和数据噪声场景下相对于传统方法的显著优势。

关键词：脉冲重复间隔高维特征决策树雷达辐射源识别

基于波形域的匹配滤波前抗间歇采样转发干扰方法

在线全文

学校读者我要写书评

暂无评论

雷达学报（中英文） 2024年第1期13卷 240-252页

作者：苏汉宁潘嘉蒙鲍庆龙郭福成胡卫东国防科技大学自动目标识别国家重点实验室长沙410073 国防科技大学电子信息系统复杂电磁环境效应国家重点实验室长沙410073

间歇采样转发干扰属于一类脉内相干欺骗干扰,其运用欠采样原理,在距离维上产生多个虚假的目标峰,从而干扰真实目标的检测与跟踪。为了解决这一问题,该文提出了一种基于波形域的匹配滤波前抗间歇采样转发干扰方法。首先,考虑到间歇采样... 详细信息

间歇采样转发干扰属于一类脉内相干欺骗干扰,其运用欠采样原理,在距离维上产生多个虚假的目标峰,从而干扰真实目标的检测与跟踪。为了解决这一问题,该文提出了一种基于波形域的匹配滤波前抗间歇采样转发干扰方法。首先,考虑到间歇采样转发干扰的部分匹配特性,该文在匹配滤波过程中引入了扩展域,即波形域,以研究干扰信号与真实目标回波信号元素的局部特征,并在每个波形域上定义了自适应的阈值函数。其次,引入卡尔曼滤波对波形域信号进行状态估计,通过自适应阈值检测筛选出波形域信号中的有效积分元素与无效积分元素,并建立关于有效积分元素的估计状态空间。最后,在抑制波形域信号中的无效积分元素的同时,从有效积分元素的估计状态空间中补充相应长度的积分元素,保留剩余的有效积分元素,通过积分得到不含虚假目标的距离像结果。该文所提方法不倚赖于任何干扰机参数等先验信息,即可有效抑制间歇采样转发干扰。仿真实验表明,与传统方法相比,该文方法实现的抗间歇采样转发干扰性能更优。

关键词：波形域抗间歇采样转发干扰匹配滤波自适应

石墨烯基聚合物复合涂层及湿法涂覆在金属双极板领域的应用进展

在线全文

学校读者我要写书评

暂无评论

广州化学 2024年第3期49卷 25-30,I0002页

作者：郭福成李静上海理工大学材料与化学学院上海200093

简单介绍真空气相沉积制备双极板涂层的优缺点;提出石墨烯作为理想防腐填料应用于双极板涂层的可能性;指出石墨烯基聚合物复合涂层的分散性难题及解决方案;详细综述了几种湿法涂覆石墨烯衍生物或二维纳米材料聚合物复合涂层的制备方法,... 详细信息

简单介绍真空气相沉积制备双极板涂层的优缺点;提出石墨烯作为理想防腐填料应用于双极板涂层的可能性;指出石墨烯基聚合物复合涂层的分散性难题及解决方案;详细综述了几种湿法涂覆石墨烯衍生物或二维纳米材料聚合物复合涂层的制备方法,以及各自涂层形貌、导电性、耐蚀性上的特点;最后展望了现阶段的石墨烯基聚合物复合涂层的缺陷以及改进方向。

关键词：金属双极板石墨烯基聚合物复合材料腐蚀与防护

A closed-form solution for moving source localization using LBI changing rate of phase difference only

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2014年第2期27卷 365-374页

作者： Zhang Min guo fucheng Zhou Yiyu College of Electronic Science and Engineering National University of Defense Technology

Due to the deficiencies in the conventional multiple-receiver localization syste,.ns based on direction of arrival （DOA） such as system complexity of interferometer or array and ampli- tude/phase unbalance between multiple receiving channels and constraint on antenna configuration, a new radiated source localization method using the changing rate of phase difference （CRPD） measured by a long baseline interferometer （LBI） only is studied. To solve the strictly nonlinear problem, a two-stage closed-form solution is proposed. In the first stage, the DOA and its changing rate are estimated from the CRPD of each observer by the pseudolinear least square （PLS） method, and then in the second stage, the source position and velocity are found by another PLS minimiza- tion. The bias of the algorithm caused by the correlation between the measurement matrix and the noise in the second stage is analyzed. To reduce this bias, an instrumental variable （IV） method is derived. A weighted IV estimator is given in order to reduce the estimation variance. The proposed method does not need any initial guess and the computation is small. The Cramer-Rao lower bound （CRLB） and mean square error （MSE） are also analyzed. Simulation results show that the proposed method can be close to the CRLB with moderate Gaussian measurement noise.

关键词： Changing rate of phase dif-ference Cramer-Rao lower bound Estimation bias Instrumental variable Least square Long baseline interferome-ter Radiated source localization

Moving scanning emitter tracking by a single observer using time of interception:Observability analysis and algorithm

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2017年第3期30卷 1174-1183页

作者： Yifei ZHANG Min ZHANG fucheng guo Information Engineering Department Rocket Force University of Engineering College of Electronic Science and Engineering National University of Defense Technology

The target motion analysis（TMA） for a moving scanning emitter with known fixed scan rate by a single observer using the time of interception（TOI） measurements only is investigated in this *** transforming the TOI of multiple scan cycles into the direction difference of arrival（DDOA） model,the observability analysis for the TMA problem is *** necessary conditions for uniquely identifying the scanning emitter trajectory are *** paper also proposes a weighted instrumental variable（WIV） estimator for the scanning emitter TMA,which does not require any initial solution guess and is closed-form and computationally *** importantly,simulations show that the proposed algorithm can provide estimation mean square error close to the Cramer-Rao lower bound（CRLB） at moderate noise levels with significantly lower estimation bias than the conventional pseudo-linear least square（PLS） estimator.

关键词： Cramer-Rao lower bound Least squares Observability Scanning emitter Target motion analysis Time of interception

A Linear-correction Least-squares Approach for Geolocation Using FDOA Measurements Only

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2012年第5期25卷 709-714页

作者： LI Jinzhou guo fucheng JIANG Wenli School of Electronic Science and Engineering National University of Defense TechnologyChangsha 410073China

A linear-correction least-squares（LCLS） estimation procedure is proposed for geolocation using frequency difference of arrival （FDOA） measurements only. We first analyze the measurements of FDOA, and further derive the Cramer-Rao lower bound （CRLB） of geoloeation using FDOA measurements. For the localization model is a nonlinear least squares（LS） estimator with a nonlinear constrained, a linearizing method is used to convert the model to a linear least squares estimator with a nonlinear con- strained. The Gauss-Newton iteration method is developed to conquer the source localization problem. From the analysis of solving Lagrange multiplier, the algorithm is a generalization of linear-correction least squares estimation procedure under the condition of geolocation using FDOA measurements only. The algorithm is compared with common least squares estimation. Comparisons of their estimation accuracy and the CRLB are made, and the proposed method attains the CRLB. Simulation re- sults are included to corroborate the theoretical development.

关键词： signal processing frequency difference of arrival Cramer-Rao lower bound linear-correction least-squares Gauss-Newton iteration method Lagrange multiplier

Passive localization by a single moving observer using TOA only with unknown SRI:Observability analysis and algorithm

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2023年第6期36卷 318-331页

作者： Min ZHANG Yuhao PEI Xi LI fucheng guo College of Electronic Science and Technology National University of Defense TechnologyChangsha 410073China

Passive localization by a single moving observer using Time of Arrival(TOA)only with an unknown Signal Repetition Interval(SRI)is investigated in this *** analysis is performed *** observability condition for uniquely determining the emitter position and SRI is *** conditional Cramer-Rao Lower Bound(CRLB)is also *** is found that the ambiguity of the SRI integer of the first TOA does not affect the theoretical estimation precision of the emitter position and SRI.A Reference-Fixed Differential TOA(RFDTOA)-based Iterative Maximum Likelihood Estimator(IMLE)is proposed,which only needs O(M)computational *** analysis and simulation results show that the Mean Square Error(MSE)of the proposed algorithm could attain the CRLB with moderate Gaussian measurement noise.

关键词： Cramer-Rao lower bound Maximum likelihood estimation Observability analysis Passive localization Signal Repetition Interval(SRI) Time of Arrival(TOA)