检索结果-内蒙古大学图书馆

Progress in Electromagnetic Research Symposium (PIERS)

作者： Zhanling Wang Chen Pang Yongzhen Li Xuesong Wang Dou Sun State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science National University of Defense Technology China

ISBN: (数字)9781728134031

ISBN: (纸本)9781728134048

There exhibit some challenges for the wideband fully polarimetric phased array radar (PPAR) in order to meet the requirement for highly accurate polarimetric measurements. Specifically, the electric field radiated from the horizontal (H) port is not necessarily orthogonal to that from the vertical (V ) port when the beam is directed away from the normal of the antenna plane. The cross-polar components are produced, and this is where the polarization biases yield from. Meanwhile, the parameters of electronic equipment, such as transmitter and receiver, are frequency-dependent. The polarimetric characteristics of the practical wideband PPAR antenna vary with frequency, and the polarization non-orthogonality are also frequency-dependent. Therefore, the wideband characteristics and the frequency-dependent polarimetric properties are mutually coupled. All the above factors will cause the polarization measurement bias, and they can also be considered as the frequency response (FR). In this paper, a bias correction method for the wideband PPAR is proposed. Firstly, the fully polarization measurement bias model based on the transmitting and receiving process of the electromagnetic wave is built, and the effects of frequency response on the polarization scattering matrix (PSM) are analyzed. Then, the proposed frequency band division method for measurement parameter bias is detailedly derived to eliminate the effect of the bandwidth. A wideband microstrip patch array element is conducted to demonstrate the effectiveness of the proposed method. The effects of bandwidth and beam direction for the polarimetric variables, such as differential reflectivity (Z DR ) and linear depolarization ratio (L DR ), are analyzed. The simulation results show that the biases of Z DR and L DR can be decreased to less than 0.1dB and -40dB, respectively. The proposed method can maintain a favorable measurement accuracy with widening the frequency band.

关键词： Wideband Frequency measurement Springs Antenna measurements Radar Scattering Frequency response

来源：评论

学校读者我要写书评

暂无评论

Characteristic Analysis of Monobit Signal

引用

Journal of Physics: Conference Series 2021年第1期1738卷

作者： Pengfei Ji Xiao Yang Chenglong Xia Huan Lv State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System Technology National University of Defense Technology Changsha Hunan 410073 China. School of Electronic Science National University of Defense Technology Changsha Hunan 410073 China. Military Representative Office of Rocket Force in Changsha Changsha Hunan 4100205 China.

This paper analyzes the characters of monobit signals and gives the reason why the spurious free dynamic ranges (SFDR) of monobit signals is much lower than those of multi-bit signals. According to our analysis and simulation, if the third harmonic of a monobit signal can be filtered, the SFDR of it can be improved well. Therefore, we give the way to obtain the desired band, which do not contain any third harmonics, and the simulation results are in agreement with our design. Such way can be used to improve the performance of monobit digital receivers in engineering.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Efficient Direct Measurement of Arbitrary Quantum systems via Weak Measurement

引用

Physical Review Applied 2019年第1期12卷 014045-014045页

作者： Changliang Ren Ya Wang Jiangfeng Du Center for Nanofabrication and System Integration Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing 400714 People’s Republic of China CAS Key Laboratory of Microscale Magnetic Resonance University of Science and Technology of China CAS Key Laboratory of Quantum Information University of Science and Technology of China Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics University of Science and Technology of China Hefei 230026 China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China

Obtaining the density matrix that fully describes a quantum system is central to quantum science. Recently, the technique of “direct measurement” has been proposed to characterize a quantum state in situ; however, all the existing schemes require sequential weak and strong measurements, which strongly limits their practical application. Here, we present an efficient scheme for directly measuring arbitrary quantum matrix elements with only one strong measurement or weak measurement on each qudit. Our scheme is experimentally feasible for the direct measurement of arbitrary quantum states; in particular, multiparticle quantum entangled states. This scheme has applications in the characterization of large-scale quantum systems.

关键词： Entanglement measures Quantum tomography Weak values & weak measurements

来源：评论

学校读者我要写书评

暂无评论

Understand dynamic regret with switching cost for online decision making

arXiv

引用

arXiv 2019年

作者： Zhao, Yawei Zhao, Qian Zhang, Xingxing Zhu, En Liu, Xinwang Yin, Jianping School of Computer National University of Defense Technology College of Mathematics and System Science Xinjiang University Institute of Information Science Beijing Key Laboratory of Advanced Information Science and Network Technology Beijing Jiaotong University School of Computer Dongguan University of Technology

As a metric to measure the performance of an online method, dynamic regret with switching cost has drawn much attention for online decision making problems. Although the sublinear regret has been provided in many previous researches, we still have little knowledge about the relation between the dynamic regret and the switching cost. In the paper, we investigate the relation for two classic online settings: Online Algorithms (OA) and Online Convex Optimization (OCO). We provide a new theoretical analysis framework, which shows an interesting observation, that is, the relation between the switching cost and the dynamic regret is different for settings of OA and OCO. Specifically, the switching cost has significant impact on the dynamic regret in the setting of OA. But, it does not have an impact on the dynamic regret in the setting of OCO. Furthermore, we provide a lower bound of regret for the setting of OCO, which is same with the lower bound in the case of no switching cost. It shows that the switching cost does not change the difficulty of online decision making problems in the setting of OCO. Copyright © 2019, The Authors. All rights reserved.

关键词： Decision making

来源：评论

学校读者我要写书评

暂无评论

MRPB 1.0: A unified benchmark for the evaluation of mobile robot local planning approaches

arXiv

引用

arXiv 2020年

作者： Wen, Jian Zhang, Xuebo Bi, Qingchen Pan, Zhangchao Feng, Yanghe Yuan, Jing Fang, Yongchun The Institute of Robotics and Automatic Information System College of Artificial Intelligence Nankai University Tianjin300350 China The Tianjin Key Laboratory of Intelligent Robotics Nankai University Tianjin300350 China The School of Marine Science and Technology Northwestern Polytechnical University Xi'an710072 China The Faculty of Robot Science and Engineering Northeastern University Shenyang110000 China The College of Systems Engineering National University of Defense Technology Changsha410073 China

Local planning is one of the key technologies for mobile robots to achieve full autonomy and has been widely investigated. To evaluate mobile robot local planning approaches in a unified and comprehensive way, a mobile robot local planning benchmark called MRPB 1.0 is newly proposed in this paper. The benchmark facilitates both motion planning researchers who want to compare the performance of a new local planner relative to many other state-of-the-art approaches as well as end users in the mobile robotics industry who want to select a local planner that performs best on some problems of interest. We elaborately design various simulation scenarios to challenge the applicability of local planners, including large-scale, partially unknown, and dynamic complex environments. Furthermore, three types of principled evaluation metrics are carefully designed to quantitatively evaluate the performance of local planners, wherein the safety, efficiency, and smoothness of motions are comprehensively considered. We present the application of the proposed benchmark in two popular open-source local planners to show the practicality of the benchmark. In addition, some insights and guidelines about the design and selection of local planners are also provided. The benchmark website [1] contains all data of the designed simulation scenarios, detailed descriptions of these scenarios, and example code. Copyright © 2020, The Authors. All rights reserved.

关键词： Mobile robots

来源：评论

学校读者我要写书评

暂无评论

Review of Chinese atmospheric science research over the past 70 years: Atmospheric physics and atmospheric environment

引用

science China Earth sciences 2019年第12期62卷 1903-1945页

作者： Tijian WANG Taichang GAO Hongsheng ZHANG Maofa GE Hengchi LEI Peichang ZHANG Peng ZHANG Chunsong LU Chao LIU Hua ZHANG Qiang ZHANG Hong LIAO Haidong KAN Zhaozhong FENG Yijun ZHANG Xiushu QIE Xuhui CAI Mengmeng LI Lei LIU Shengrui TONG School of Atmospheric Sciences Nanjing UniversityNanjing 210023China College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China Department of Atmospheric and Oceanic Sciences School of PhysicsPeking UniversityBeijing 100871China Institute of Chemistry Chinese Academy of SciencesBeijing 100190China Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China School of Atmospheric Physics Nanjing University of Information Science and TechnologyNanjing 210044China National Satellite Meteorological Center China Meteorological AdministrationBeijing 100081China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China Department of Earth System Science Tsinghua UniversityBeijing 100084China School of Environmental Science and Engineering Nanjing University of Information Science and TechnologyNanjing 210044China Department of Environmental Health School of Public HealthFudan UniversityShanghai 200032China Department of Atmospheric and Oceanic Sciences Fudan UniversityShanghai 200032China Department of Environmental Science College of Environmental Science and EngineeringPeking UniversityBeijing 100871China

Since the founding of the People’s Republic of China 70 years ago,the subject of atmospheric physics and atmospheric environment has developed rapidly in China,providing important support for the development of atmospheric science and guarantee for the development of national *** this paper,the general advancement of atmospheric physics and atmospheric environment in last 70 years was *** main research progress of atmospheric physics and atmospheric environment in the past 40 years of reform and opening-up was reviewed,the outstanding research achievements since the 21 st century were summarized,the major problems and challenges are pointed out,and the key directions and suggestions for future development are put forward.

关键词： Atmospheric physics Atmospheric environment Atmospheric sounding Atmospheric chemistry Atmospheric remote sensing

来源：评论

学校读者我要写书评

暂无评论

Building an efficient intrusion detection system based on feature selection and ensemble classifier

arXiv

引用

arXiv 2019年

作者： Zhou, Yuyang Cheng, Guang Jiang, Shanqing Dai, Mian School of Cyber Science and Engineering Southeast University Nanjing China Key Laboratory of Computer Network and Information Integration Ministry of Education Nanjing China Jiangsu Provincial Key Laboratory of Computer Network Technology Southeast University Nanjing China National Key Laboratory of Science and Technology on Information System Security Beijing China

Intrusion detection system (IDS) is one of extensively used techniques in a network topology to safeguard the integrity and availability of sensitive assets in the protected systems. Although many supervised and unsupervised learning approaches from the field of machine learning have been used to increase the efficacy of IDSs, it is still a problem for existing intrusion detection algorithms to achieve good performance. First, lots of redundant and irrelevant data in high-dimensional datasets interfere with the classification process of an IDS. Second, an individual classifier may not perform well in the detection of each type of attacks. Third, many models are built for stale datasets, making them less adaptable for novel attacks. Thus, we propose a new intrusion detection framework in this paper, and this framework is based on the feature selection and ensemble learning techniques. In the first step, a heuristic algorithm called CFS-BA is proposed for dimensionality reduction, which selects the optimal subset based on the correlation between features. Then, we introduce an ensemble approach that combines C4.5, Random Forest (RF), and Forest by Penalizing Attributes (Forest PA) algorithms. Finally, voting technique is used to combine the probability distributions of the base learners for attack recognition. The experimental results, using NSL-KDD, AWID, and CIC-IDS2017 datasets, reveal that the proposed CFS-BA-Ensemble method is able to exhibit better performance than other related and state of the art approaches under several metrics. Copyright © 2019, The Authors. All rights reserved.

关键词： Data mining

来源：评论

学校读者我要写书评

暂无评论

A survey on edge computing systems and tools

arXiv

引用

arXiv 2019年

作者： Liu, Fang Tang, Guoming Li, Youhuizi Cai, Zhiping Zhang, Xingzhou Zhou, Tongqing School of Data and Computer Science Sun Yat-sen University GuangzhouGuangdong China Key Laboratory of Science and Technology on Information System Engineering National University of Defense Technology ChangshaHunan China School of Compute Science and Technology Hangzhou Dianzi University China College of Computer National University of Defense Technology ChangshaHunan China State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences China

—Driven by the visions of Internet of Things and 5G communications, the edge computing systems integrate computing, storage and network resources at the edge of the network to provide computing infrastructure, enabling developers to quickly develop and deploy edge applications. Nowadays the edge computing systems have received widespread attention in both industry and academia. To explore new research opportunities and assist users in selecting suitable edge computing systems for specific applications, this survey paper provides a comprehensive overview of the existing edge computing systems and introduces representative projects. A comparison of open source tools is presented according to their applicability. Finally, we highlight energy efficiency and deep learning optimization of edge computing systems. Open issues for analyzing and designing an edge computing system are also studied in this survey. Copyright © 2019, The Authors. All rights reserved.

关键词： Energy efficiency

来源：评论

学校读者我要写书评

暂无评论

Effects and mechanisms of innate immune molecules on inhibiting nasopharyngeal carcinoma

引用

Chinese Medical Journal 2019年第6期132卷 749-752页

作者： Fang Xiong Su Deng Hong-Bin Huang Xia-Yu Li Wen-Ling Zhang Qian-Jin Liao Jian Ma Xiao-Ling Li Wei Xiong Gui-Yuan Li Zhao-Yang Zeng Can Guo Science and Technology on Information System Engineering Laboratory National University of Defense Technology Changsha Hunan 410000 China Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education Xiangya Hospital Central South University Changsha. Hunan 410078 China NHC Key Laboratory of Carcinogenesis Cancer Research Institute Central South University Changsha Hunan 410078 China

To the Editor: The nasopharyngeal ep让helium is frequently exposed to various harmful carcinogens. When the nasopharvngeal mucosa is damaged, local inflammation is induced.[1] Chronic inflammation of the nasopharyngeal epithelium may eventually evolve into nasopharyngeal carcinoma (NPC). While the mucus secreted by the nasopharyngeal epithelium forms the body's primitive immune protection barrier as it contains a series of proteins and peptides that can sense, bind, degrade and remove various harmful substances. Lactotransferrin (LTF)[2] and bactericidal/permeability-increasing (BPI) protein family members[3] are an important component of the innate immune protection barrier.

关键词： Effects and mechanisms innate immune molecules inhibiting nasopharyngeal carcinoma

来源：评论

学校读者我要写书评

暂无评论

Estimating the Predictability Limit of Tropical Cyclone Tracks over the Western North Pacific Using Observational Data

引用

Advances in Atmospheric sciences 2018年第12期35卷 1491-1504页

作者： Quanjia ZHONG Lifeng ZHANG Jianping LI Ruiqiang DING Jie FENG State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences College of Meteorology and Oceanography National University of Defense Technology College of Earth Science University of Chinese Academy of Sciences Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and Technology College of Global Change and Earth System Sciences Beijing Normal University School of Meteorology University of Oklahoma

In this study,the nonlinear local Lyapunov exponent(NLLE)approach was used to quantitatively determine the predictability limit of tropical cyclone(TC)tracks based on observed TC track data obtained from the Joint Typhoon Warning *** results show that the predictability limit of all TC tracks over the whole western North Pacific(WNP)basin is about 102 h,and the average lifetime of all TC tracks is about 174 *** predictability limits of the TC tracks for short-,medium-,and long-lived TCs are approximately 72 h,120 h,and 132 h,*** predictability limit of the TC tracks depends on the TC genesis location,lifetime,and intensity,and further analysis indicated that these three metrics are closely *** more intense and longer-lived TCs tend to be generated on the eastern side of the WNP(EWNP),whereas the weaker and shorter-lived TCs tend to form in the west of the WNP(WWNP)and the South China Sea(SCS).The relatively stronger and longer-lived TCs,which are generated mainly in the EWNP,have a longer travel time before they curve northeastwards and hence tend to be more predictable than the relatively weaker and shorter-lived TCs that form in the WWNP region and ***,the results show that the predictability limit of the TC tracks obtained from the best-track data may be underestimated due to the relatively short observational records currently *** work is needed,employing a numerical model to assess the predictability of TC tracks.

关键词： predictability tropical cyclone tracks nonlinear local Lyapunov exponent

来源：评论

学校读者我要写书评

暂无评论

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

请选择保存的检索档案：

请选择收藏分类：

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

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

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：