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Study on Quantitative Precipitation Estimation by Polarimetric Radar Using Deep Learning

Advances in Atmospheric Sciences 2024年第6期41卷 1147-1160页

作者： Jiang huANGFU zhiqun hu Jiafeng ZHENG Lirong WANG Yongjie Zhu State Key Lab of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China Meteorological observatory of Jiangxi Province Nanchang 330096China Hebei Meteorological Disaster Prevention and Environmental Meteorological Center Shijiazhuang 050021China School of Atmospheric Sciences Chengdu University of Information TechnologyChengdu 610225China

Accurate radar quantitative precipitation estimation(QPE)plays an essential role in disaster prevention and *** this paper,two deep learning-based QPE networks including a single-parameter network and a multi-parameter network are ***,a self-defined loss function(SLF)is proposed during *** dataset includes Shijiazhuang S-band dual polarimetric radar(CINRAD/SAD)data and rain gauge data within the radar’s 100-km detection range during the flood season of 2021 in North *** that the specific propagation phase shift(KDP)has a roughly linear relationship with the precipitation intensity,KDP is set to 0.5°km^(-1 )as a threshold value to divide all the rain data(AR)into a heavy rain(HR)and light rain(LR)***,12 deep learning-based QPE models are trained according to the input radar parameters,the precipitation datasets,and whether an SLF was adopted,*** results suggest that the effects of QPE after distinguishing rainfall intensity are better than those without distinguishing,and the effects of using SLF are better than those that used MSE as a loss function.A Z-R relationship and a ZH-KDP-R synthesis method are compared with deep learning-based *** mean relative errors(MRE)of AR models using SLF are improved by 61.90%,51.21%,and 56.34%compared with the Z-R relational method,and by 38.63%,42.55%,and 47.49%compared with the synthesis ***,the models are further evaluated in three precipitation processes,which manifest that the deep learning-based models have significant advantages over the traditional empirical formula methods.

关键词： polarimetric radar quantitative precipitation estimation deep learning single-parameter network multi-parameter network

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萍乡古代寺产纠纷案初考——以显华寺碑刻所录案例为中心

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萍乡学院学报 2024年第2期41卷 46-53页

作者：邓里胡志群萍乡博物馆江西萍乡337000

古代,萍乡地区的寺庙因田产与村民发生纠纷的案件,地方文献不见有相关资料记载。近年,萍乡博物馆对全市庙宇文物进行调查时,在显华寺内发现数通碑刻,其中清同治二年(1863)重立的《永远遵守》碑和光绪四年(1878)刊立的《千秋永賴》碑涉... 详细信息

古代,萍乡地区的寺庙因田产与村民发生纠纷的案件,地方文献不见有相关资料记载。近年,萍乡博物馆对全市庙宇文物进行调查时,在显华寺内发现数通碑刻,其中清同治二年(1863)重立的《永远遵守》碑和光绪四年(1878)刊立的《千秋永賴》碑涉及有关寺产纠纷方面的内容,尤其是《千秋永賴》碑刻比较详细地记录了一件萍乡显华寺寺产纠纷案的整个发生过程和最终处理结果,为我们研究清代该时期寺产纠纷案的处理及其衍生问题,提供了一手资料。

关键词：显华寺清代碑刻寺产纠纷案

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基于ConvLSTM融合RMAPS-NOW数据的雷达回波外推研究

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气象学报 2024年第4期82卷 554-567页

作者：王善昊胡志群王福增陈杰鑫成都信息工程大学电子工程学院成都610225 中国气象科学研究院灾害天气国家重点实验室北京100081 中国气象局大气探测重点开放实验室成都610225 成都信息工程大学大气科学学院成都610225

雷达回波外推是临近预报、人工影响天气作业及效果评估的主要参考依据之一,快速准确的回波外推技术一直是雷达气象领域的研究热点。近年来,基于深度学习的时空序列预测模型在雷达回波外推中得到了广泛应用。然而,这些外推网络架构的输... 详细信息

雷达回波外推是临近预报、人工影响天气作业及效果评估的主要参考依据之一,快速准确的回波外推技术一直是雷达气象领域的研究热点。近年来,基于深度学习的时空序列预测模型在雷达回波外推中得到了广泛应用。然而,这些外推网络架构的输入大多用16级伪彩色雷达回波强度产品转化而来的灰度图,丢失了许多回波细节,并且随着外推时间延长,误差不可避免地增大。回波的生消、移动、演变与天气背景紧密相关,因此,将北京城市气象研究院研发的新一代快速更新多尺度资料分析和预报系统的临近数值预报子系统(RMAPS-NOW)初始零场的部分物理量产品融入华北雷达拼图原始数据,构建多个雷达单元(Radar cells),并将这些雷达单元作为输入,基于卷积长短期记忆网络(ConvLSTM),设计了一个多通道雷达回波外推网络架构(MR-ConvLSTM)。另外,考虑到卷积算法的平滑性,构建了自定义损失函数,增加回波强度的时空权重进行时空衰减订正。选取(40.65°—41.65°N,114°—115.4°E)内2018—2021年的6—9月共13000组华北雷达组合反射率因子拼图及RMAPS-NOW初始零场数据,其中的80%共10400组为训练集,20%共2600组为测试集。引入的物理量包括多个高度层的u、v风(1350 m),相对湿度(RH,150 m),水平散度(1350 m)等,基于ConvLSTM及MR-ConvLSTM加自定义损失函数,分别训练得到5个雷达回波外推模型。采用临界成功指数(CSI)、命中率(POD)、虚警率(FAR)作为评价指标,利用测试集对所有模型进行评估。基于引入物理量的MR-ConvLSTM训练得到的模型在20、30、35 dBz反射率阈值下,比未引入物理量的基于ConvLSTM的外推模型CSI值平均高4.67%、13.8%、5.98%,POD值平均高3.1%、7.68%、8.38%,FAR值平均低6.37%、8.54%、10.17%,同时引入3种物理量(RH、u、v)的外推模型在不同阈值的各项指标中综合表现最好,其CSI、 POD值在3种不同阈值下比未引入物理量模型平均高16.01%、13.38%,FAR值平均低14.88%。从模型应用的个例可视化也可以看出,引入物理量后有效提升了雷达回波外推的准确度,证明基于MR-ConvLSTM架构训练的雷达回波外推模型有较强的泛化能力。

关键词：雷达回波外推深度学习 RMAPS-NOW MR-ConvLSTM网络架构自定义损失函数

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Applications of Wavelet Analysis in Differential Propagation Phase Shift Data De-noising

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Advances in Atmospheric Sciences 2014年第4期31卷 825-835页

作者： hu zhiqun LIU Liping State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences

Using numerical simulation data of the forward differential propagation shift （ΦDP） of polarimetric radar,the principle and performing steps of noise reduction by wavelet analysis are introduced in *** from the multiscale analysis,various types of noises can be identified according to their characteristics in different scales,and suppressed in different resolutions by a penalty threshold strategy through which a fixed threshold value is applied,a default threshold strategy through which the threshold value is determined by the noise intensity,or a ΦDP penalty threshold strategy through which a special value is designed for ΦDP ***,a hard-or soft-threshold function,depending on the de-noising purpose,is selected to reconstruct the *** the three noise suppression strategies and the two signal reconstruction functions,and without loss of generality,two schemes are presented to verify the de-noising effect by dbN wavelets：（1） the penalty threshold strategy with the soft threshold function scheme （PSS）; （2） the ΦDP penalty threshold strategy with the soft threshold function scheme （PPSS）.Furthermore,the wavelet de-noising is compared with the mean,median,Kalman,and finite impulse response （FIR） methods with simulation data and two actual *** results suggest that both of the two schemes perform well,especially when ΦDP data are simultaneously polluted by various scales and types of noises.A slight difference is that the PSS method can retain more detail,and the PPSS can smooth the signal more successfully.

关键词： polarimetric radar wavelet analysis differential propagation phase shift de-noising

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低精度ADC下无小区大规模MIMO系统的频谱效率研究

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信号处理 2024年第8期40卷 1520-1530页

作者：肖海林何怡玲谢湘伟胡智群张中山湖北大学计算机与信息工程学院湖北武汉430062 北京邮电大学信息与通信工程学院北京100876 北京理工大学信息与电子学院北京100081

无小区大规模多输入多输出(cell-free massive multiple-input multiple-output,CF-mMIMO)系统的覆盖区域内随机部署了大量分布式接入点(access points,APs)在同一时间频率资源中服务所有的用户,可显著提升系统通信容量,是6G网络中最具... 详细信息

无小区大规模多输入多输出(cell-free massive multiple-input multiple-output,CF-mMIMO)系统的覆盖区域内随机部署了大量分布式接入点(access points,APs)在同一时间频率资源中服务所有的用户,可显著提升系统通信容量,是6G网络中最具潜力的使能技术之一。然而,大量AP处配备高精度模数转换器(analog-to-digital converters,ADCs)导致的高功耗与硬件成本,限制了CF-mMIMO系统的实际部署。为了有效地降低硬件成本,本文研究了低精度ADCs下CF-mMIMO系统的上行链路频谱效率(spectral efficiency,SE)。在不完美的信道估计下,利用加性量化噪声(additive quantization noise model,AQNM)模型和最大比合并(maximal ratio combining,MRC)接收机滤波器,推导了CF-mMIMO系统中用户上行可达速率的闭式表达式,并基于该表达式分析了AP数量、用户传输功率以及ADCs精度等系统参数对SE的影响。为了最大化CF-mMIMO系统的SE,提出了一种低精度ADCs下贪婪导频分配算法抑制导频污染。将导频分配建模为最大-最小导频优化问题,通过迭代更新速率最小用户的导频序列,使其所受导频污染的影响最小,从而最大化该用户的可达速率。最后,将配备低精度ADC的CFmMIMO系统与传统完美精度ADC系统进行性能比较。数值仿真结果表明,系统配备5位低精度ADCs时的SE逼近完美精度ADCs,增加AP端天线数可以弥补低精度ADCs导致的性能退化。此外,所提算法不仅有效抑制了导频污染,还缩小了用户之间的速率差距,提升了系统的95%用户SE。

关键词：无小区大规模MIMO系统低精度模数转换器加性量化噪声模型导频分配

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Improvement of X-Band Polarization Radar Melting Layer Recognition by the Bayesian Method and ITS Impact on Hydrometeor Classification

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Advances in Atmospheric Sciences 2020年第1期37卷 105-116页

作者： Jianli MA zhiqun hu Meilin YANG Siteng LI Institute of Urban Meteorology China Meteorological AdministrationBeijing 100089China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China

Using melting layer(ML)and non-melting layer(NML)data observed with the X-band dual linear polarization Doppler weather radar(X-POL)in Shunyi,Beijing,the reflectivity(ZH),differential reflectivity(ZDR),and correlation coefficient(CC)in the ML and NML are obtained in several stable precipitation *** prior probability density distributions(PDDs)of the ZH,ZDR and CC are calculated first,and then the probabilities of ZH,ZDR and CC at each radar gate are determined(PBB in the ML and PNB in the NML)by the Bayesian *** PBB>PNB the gate belongs to the ML,and when PBBhunyi,Beijing,the reflectivity(ZH),differential reflectivity(ZDR),and correlation coefficient(CC)in the ML and NML are obtained in several stable precipitation *** prior probability density distributions(PDDs)of the ZH,ZDR and CC are calculated first,and then the probabilities of ZH,ZDR and CC at each radar gate are determined(PBB in the ML and PNB in the NML)by the Bayesian *** PBB>PNB the gate belongs to the ML,and when PBB

关键词： X-band polarimetric radar Bayesian method melting layer identification hydrometeor classification

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Improving throughput through dynamically tuning contention window size in dense wireless network

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The Journal of China Universities of Posts and Telecommunications 2017年第4期24卷 27-33页

作者： Lin Shangjuan Wen Xiangming hu zhiqun Lu Zhaoming School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing 100876 China Beijing Laboratory of Advanced Information Networks Beijing University of Posts and Telecommunications Beijing 100876 China

With the boom of wireless devices, the number of wireless users under wireless local area networks （WLANs） has increased dramatically. However, the standard baekoff mechanism in IEEE 802.11 adopts fixed initial contention window （CW） size without considering changes of network load, which leads to a high collision probability and low channel utilization in bursty arrivals. In this paper, a novel CW dynamic adjustment scheme is proposed to achieve high throughput performance in dense user environment. In the proposed scheme, the initial CW size is dynamically adjusted to optimum according to the measured packet collision probability. Simulation results show that the proposed scheme can significantly improve the throughput performance.

关键词： wireless local area network (WLAN) dense user environment contention window (CW) dynamic optimization

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QoE based power control scheme for interference mitigation in high-density WLANs

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The Journal of China Universities of Posts and Telecommunications 2016年第2期23卷 24-30页

作者： Wang Yiqing Wen Xiangming hu zhiqun Lu Zhaoming School of Telecommunication Engineering Beijing University of Posts and Telecommunications

Mobile data traffic is going through an explosive growth recently as mobile smart devices become more and more ubiquitous, causing huge pressure on cellular network. Taking advantage of its low cost and easy-to-deploy feature, wireless local-area networks（WLAN） becomes increasingly popular to offload data streams from cellular network, followed by higher and higher density of its deployment. However, the high density of WLAN will cause more interference, which results in degradation of its performance. Therefore, in order to enhance the performance of the network, we aim to minimize the interference caused by high density of WLAN. In this paper, we propose a novel power control scheme to achieve the above aim. We use the quality of experience（QoE） evaluation to coordinate the power of each access point（AP） and finally realize the optimization of the entire network. According to the simulation results, our scheme improves the performance of the network significantly in many aspects, including throughput and QoE.

关键词： power control high-density WLAN interference mitigation QoE

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Performance analysis of LTE-U coexistence network with WiFi using queueing model

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The Journal of China Universities of Posts and Telecommunications 2017年第5期24卷 1-7页

作者： hu zhiqun Lu Zhaoming Lin Shangjuan Wen Xiangming Xu Hen School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

The unforeseen mobile data explosion as well as the scarce of spectrum resource pose a major challenge to the performance of today＇s cellular networks which are in urgent need of novel solutions to handle such voluminous mobile data. Long term evolution-unlicensed （LTE-U）, which extends the LTE standard operating on the unlicensed band, has been proposed to improve system throughput. In LTE-U system, arriving users will contend the unlicensed spectrum resource with wireless fidelity （WiFi） users to transmit data information. Nevertheless, there is no clear consensus as to the benefits of transmission using unlicensed bands for LTE users. To this end, in this paper an analytical model is presented based on a queue system to understand the performance achieved by unlicensed based LTE system taking quality of services （QoS） and LTE-U users＇ behaviors into account. To obtain the stead-state solutions of the queue system, a matrix geometric method is used to solve it. Then, the average delay and utilization of unlicensed band for the LTE-U users is derived by using the queuing model. The performance of LTE-U coexistence is evaluated with WiFi using the proposed model and provide some initial insights as to the advantage of LTE-U in practice.

关键词： LTE-U WiFi queueing model matrix geometric method

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Spectrum efficiency maximization with trajectory design in UAV-enabled mobile relaying

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The Journal of China Universities of Posts and Telecommunications 2019年第4期26卷 17-24页

作者： Sun Chuanzhi hu zhiqun Wen Xiangming Lu Zhaoming Qi Hang Beijing Laboratory of Advanced Information Networks Beijing University of Posts and TelecommunicationsBeijing 100876China Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and TelecommunicationsBeijing 100876China School of Computer and Information Engineering Hubei UniversityWuhan 430062China

With the advantages of low cost and high mobility,unmanned aerial vehicles(UAVs)have played an important role in wireless *** investigate a UAV-enabled mobile relaying system,where a UAV is used as a mobile relay to assist in the communication from a ground source to a ground destination since their direct link is *** the conventional mobile relay in which the UAV adopts straight line or circular trajectory,we consider a more general elliptical trajectory and use realistic channel *** assuming that the UAV employs time-division duplexing(TDD)based decode-and-forward(DF)relaying,we jointly optimize the time allocations and the UAV trajectory to formulate the maximization of spectrum efficiency(SE).The simulation results show that the trajectory we designed achieves a higher SE than the optimal circular trajectory and static relaying.

关键词： UAV mobile relay time allocations elliptical trajectory

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