检索结果-南通市图书馆

A novel method for extracting and optimizing the complex permittivity of paper-based composites based on an artificial neural network model

引用

Science China Technological Sciences 2024年第10期67卷 3190-3204页

作者： XIA ChenBin SHEN JunYi LIAO ShaoWei WANG Yi HUANG ZhengSheng XUE Quan TANG Min LONG Jin HU Jian school of Light Industry and Engineering South China University of Technology school of electronic and information Engineering South China University of Technology

Measuring the complex permittivity of ultrathin, flexible materials with a high loss tangent poses a substantial challenge with precision using conventional methods, and verifying the accuracy of test results remains difficult. In this study, we introduce a methodology based on a back-propagation artificial neural network(ANN) to extract the complex permittivity of paper-based composites(PBCs). PBCs are ultrathin and flexible materials exhibiting considerable complex permittivity and dielectric loss tangent. Given the absence of mature measurement methods for PBCs and a lack of sufficient data for ANN training, a mapping relationship is initially established between the complex permittivity of honeycomb-structured microwave-absorbing materials(HMAMs, composed of PBCs) and that of PBCs using simulated data. Leveraging the ANN model, the complex permittivity of PBCs can be extracted from that of HMAMs obtained using standard measurement. Subsequently, two published methods are cited to illustrate the accuracy and advancement of the results obtained using the proposed approach. Additionally, specific error analysis is conducted, attributing discrepancies to the conductivity of PBCs, the homogenization of HMAMs, and differences between the simulation model and actual objects. Finally, the proposed method is applied to optimize the cell length parameters of HMAMs for enhanced absorption performance. The conclusion discusses further improvements and areas for extended research.

关键词： paper-based composite honeycomb complex permittivity artificial neural networks inverse modeling

来源：

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Long-term variation of Arctic Sudden Stratospheric Warmings(SSW) and potential causes

引用

Earth and Planetary Physics 2024年第5期8卷 742-752页

作者： QingRan Li ShaoDong Zhang KaiMing Huang ChunMing Huang Yun Gong WenTao Tang Zheng Ma school of electronic information Wuhan University Guizhou Normal University Key Laboratory of Geospace Environment and Geodesy Ministry of Education State Key Laboratory of information Engineering in Surveying Mapping and Remote Sensing school of electronic information Engineering Jingchu University of Technology

Utilizing the European Centre for Medium-Range Weather Forecast(ECMWF) Reanalysis v5(ERA5), for the first time, we have confirmed close links among Sudden Stratospheric Warmings(SSWs) in the Northern Hemisphere(NH), the polar vortices, and stratospheric Planetary Waves(PWs) by analyzing and comparing their trends. Interestingly, within overall increasing trends, the duration and strength of SSWs exhibit increasing and decreasing trends before and after the winter of 2002, respectively. To reveal possible physical mechanisms driving these trends, we analyzed the long-term trends of the winter(from December to February) polar vortices and of stratospheric PWs with zonal wave number 1. Notably, our results show that in all three time periods(the entire period of 41winters, 1980 to 2020, and the two subperiods — 1980-2002 and 2002-2020) enhancing SSWs were always accompanied by weakening winter polar vortices and strengthening polar PWs like Stationary Planetary Waves(SPWs) and 16-day waves, and vice versa. This is the first proof, based on ERA5 long-term trend data, that weakening polar vortices and enhancing stratospheric PWs(especially SPWs) could cause an increase in SSWs.

关键词： sudden stratospheric warmings stationary planetary waves 16-day waves polar vortrices long-term trend correlation coefficient

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

A lightweight false alarm suppression method in heterogeneous change detection

引用

Journal of Systems Engineering and electronics 2024年第4期35卷 899-905页

作者： XU Cong HE Zishu LIU Haicheng school of electronic and information Engineering Heilongjiang Institute of EngineeringHarbin 150026China school of information and Communication Engineering University of Electronic Science and Technology of ChinaChengdu 611731China

Overlooking the issue of false alarm suppression in heterogeneous change detection leads to inferior detection *** paper proposes a method to handle false alarms in heterogeneous change detection.A lightweight network of two channels is bulit based on the combination of convolutional neural network(CNN)and graph convolutional network(GCN).CNNs learn feature difference maps of multitemporal images,and attention modules adaptively fuse CNN-based and graph-based features for different *** with a new kernel filter adaptively distinguish between nodes with the same and those with different labels,generating change *** evaluation on two datasets validates the efficacy of the pro-posed method in addressing false alarms.

关键词： convolutional neural network(CNN) graph convolu-tional network(GCN) heterogeneous change detection lightweight false alarm suppression

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Probing Model of Secret Key Generation Based on Channel Autocorrelation Function

引用

China Communications 2024年第6期21卷 163-175页

作者： Xia Enjun Hu Binjie Shen Qiaoqiao school of electronic and information Engineering South China University of TechnologyGuangzhou 510641China

Secret key generation(SKG)is a promising solution to the problem of wireless communications *** the first step of SKG,channel probing affects it *** there have been some probing schemes,there is a lack of research on the optimization of the probing *** study investigates how to optimize correlated parameters to maximize the SKG rate(SKGR)in the time-division duplex(TDD)***,we build a probing model which includes the effects of transmitting power,the probing period,and the dimension of sample *** on the model,the analytical expression of the SKGR is ***,we formulate an optimization problem for maximizing the SKGR and give an algorithm to solve *** conclude the SKGR monotonically increases as the transmitting power *** mathematical proofs are given in this *** the simulation results,increasing appropriately the probing period and the dimension of the sample vector could increase the SKGR dramatically compared to a yardstick,which indicates the importance of optimizing the parameters related to the channel probing phase.

关键词： channel autocorrelation function channel probing optimization problem physical layer security secret key generation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Bridge Bidding via Deep Reinforcement Learning and Belief Monte Carlo Search

引用

IEEE/CAA Journal of Automatica Sinica 2024年第10期11卷 2111-2122页

作者： Zizhang Qiu Shouguang Wang Dan You MengChu Zhou school of information and electronic Engineering Zhejiang Gongshang UniversityHangzhou 310018China IEEE

Contract Bridge,a four-player imperfect information game,comprises two phases:bidding and *** computer programs excel at playing,bidding presents a challenging aspect due to the need for information exchange with partners and interference with communication of *** this work,we introduce a Bridge bidding agent that combines supervised learning,deep reinforcement learning via self-play,and a test-time search *** experiments demonstrate that our agent outperforms WBridge5,a highly regarded computer Bridge software that has won multiple world championships,by a performance of 0.98 IMPs(international match points)per deal over 10000 deals,with a much cost-effective *** performance significantly surpasses previous state-of-the-art(0.85 IMPs per deal).Note 0.1 IMPs per deal is a significant improvement in Bridge bidding.

关键词： Contract Bridge reinforcement learning search

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A statistical analysis of the Kappa-type energy spectrum distribution of radiation belt electrons observed by Van Allen Probes

引用

Earth and Planetary Physics 2024年第2期8卷 368-374页

作者： LuHuai Jiao Xin Ma YuanNong Zhang TaiFeng Jin Song Fu BinBin Ni Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China

The energy spectrum of energetic electrons is a key factor representing the dynamic variations of Earth’s Van Allen radiation *** measurements have indicated that the commonly used Maxwellian and Kappa distributions are inadequate for capturing the realistic spectral distributions of radiation belt *** we adopt the Kappa-type(KT)distribution as the fitting function and perform a statistical analysis to investigate the radiation belt electron flux spectra observed by the Van Allen *** calculating the optimal values of the key KT distribution parameters(i.e.,κandθ2)from the observed spectral shapes,we fit the radiation belt electron fluxes at different L-shells under different geomagnetic *** this manner,we obtain typical values of the KT distribution parameters,which are statistically feasible for modeling the radiation belt electron flux profiles during either geomagnetically quiet or active periods.A comparison of the KT distribution model results with those using the Maxwellian or Kappa distribution reveals the advantage of the KT distribution for studying the overall properties of the radiation belt electron spectral distribution,which has important implications for deepening the current understanding of the radiation belt electron dynamics under evolving geomagnetic conditions.

关键词： radiation belt electron Kappa-type distribution fitting geomagnetic storm

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effect of interplanetary magnetic field B_(x)on the polar electrojets as observed by CHAMP and Swarm satellites

引用

Earth and Planetary Physics 2024年第2期8卷 382-390页

作者： Hui Wang ChengZhi Wang YunFang Zhong Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China

Based on 16 years of magnetic field observations from CHAMP and Swarm satellites,this study investigates the influence of the Interplanetary Magnetic Field(IMF)Bx component on the location and peak current density of the polar electrojets(PEJs).We find that the IMF Bx displays obvious local time,seasonal,and hemispherical effects on the PEJs,as follows:(1)Compared to other local times,its influence is weakest at dawn and dusk.(2)In the midnight sectors of both hemispheres,the IMF Bx tends to amplify the westward PEJ when it is0 in the Southern Hemisphere;this effect is relatively stronger in the local winter hemisphere.(3)At noontime,the IMF Bx intensifies the eastward current when it is0,it reduces the westward current;this effect is notably more prominent in the local summer hemisphere.(4)Moreover,the noontime eastward current shifts towards higher latitudes,while the midnight westward current migrates towards lower latitudes when IMF Bx is0 in the Southern Hemisphere.

关键词： polar electrojet interplanetary magnetic field Bx local time asymmetry hemispheric difference

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

HetNets Under Decoupled Uplink and Downlink Access with UE Random Discontinuous Transmission: Local Delay and Energy Efficiency

引用

China Communications 2024年第3期21卷 205-216页

作者： Zhang Yue Zheng Fuchun Luo Jingjing school of electronic and information Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

Due to the limited uplink capability in heterogeneousnetworks (HetNets), the decoupled uplinkand downlink access (DUDA) mode has recently beenproposed to improve the uplink performance. In thispaper, the random discontinuous transmission (DTX)at user equipment (UE) is adopted to reduce the interferencecorrelation across different time slots. By utilizingstochastic geometry, we analytically derive themean local delay and energy efficiency (EE) of an uplinkHetNet with UE random DTX scheme under theDUDA mode. These expressions are further approximatedas closed forms under reasonable *** results reveal that under the DUDA mode, there isan optimal EE with respect to mute probability underthe finite local delay constraint. In addition, with thesame finite mean local delay as under the coupled uplinkand downlink access (CUDA) mode, the HetNetsunder the DUDA mode can achieve a higher EE witha lower mute probability.

关键词： decoupled uplink and downlink access(DUDA) heterogeneous networks(HetNets) random discontinuous transmission(DTX) stochastic geometry

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Overshoot phenomena:Observation and simulation

引用

Earth and Planetary Physics 2024年第2期8卷 391-399页

作者： Ting Feng MoRan Liu ShiMin He Xiang Wang Chen Zhou Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China

High-power O-mode radio waves can excite artificial instabilities in the F region,according to experiments conducted at the European Incoherent Scatter Science Association(EISCAT)heating *** main instabilities include the parametric decay instability(PDI),oscillating two-stream instability(OTSI),and thermal parametric instability(TPI).The PDI and OTSI not only compete with each other,but also compete with the TPI,leading to a two-stage overshoot phenomenon:a miniovershoot occurs on a millisecond time scale after pump-on,followed by the main *** gain insight into the miniovershoot via a generalized Zakharov model,whereas the main overshoot can be observed as an enhanced plasma line overshoot phenomenon in incoherent scatter radar *** can also observe that the zero-frequency ion line exists only in the initial heating period after a cold start and that the upshifted and downshifted ion lines behave irregularly in the *** simulation results show that competition between the PDI and OTSI leads to an initial peak,which we named the *** following processes,namely ion density caviton generation,and collapse and cascade in the development of the PDI,contribute to the miniovershoot phenomenon.

关键词： overshoot parametric decay instability oscillating two-stream instability competition

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Linear shallow neural network to accelerate transmitter dispersion eye closure quaternary(TDECQ) assessment

引用

Science China(information Sciences) 2024年第4期67卷 337-338页

作者： Junjiang XIANG Zejun CHEN Yijun CHENG Hailin YANG Xuancheng HUO Meng XIANG Gai ZHOU Yuwen QIN Songnian FU Institute of Advanced Photonics Technology School of Information EngineeringGuangdong University of Technology school of optical and electronic information Huazhong University of Science and Technology Key Laboratory of Photonic Technology for Integrated Sensing and Communication Ministry of Education of ChinaGuangdong University of Technology Guangdong Provincial Key Laboratory of information Photonics Technology Guangdong University of Technology

To support the ever-emerging capacity requirement of datacenter interconnection(DCI) applications, transmitter dispersion eye closure quaternary(TDECQ) has been proposed by IEEE802.3 standard [1], which is specifically employed for the four-level pulse amplitude modulation(PAM-4) signals. However, the traditional scheme of TDECQ assessment needs several iterative operations,

关键词： IEEE Standards

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：