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Numerically stable method of signal subspace estimation based on multistage Wiener filter

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Science china(Information Sciences) 2010年第12期53卷 2620-2630页

作者： ZHUANG XueBin ,CUI XiaoWei,lu mingquan & feng zhenming department of electronic engineering,tsinghua university,beijing 100084.china 1. department of electronic engineering Tsinghua University Beijing 100084 China

In this paper,a numerically stable method of signal subspace estimation based on Householder multistage Wiener filter(HMSWF) is *** stability of the method lies on the fact that the Householder matrix in HMSWF ensures the unitary blocking operation and significantly strengthens the orthogonality of basis vectors,especially in the finite-precision *** the following,we analyze the numerical stability of HMSWF and MSWF based on the correlation subtractive structure(CSS-MSWF) by establishing the equivalence between the forward recursion of MSWF and the Arnoldi algorithm in numerical linear ***,the equivalence between HMSWF and the Householder QR decomposition(QRD) on the Krylov matrix underlying in MSWF is directly *** on the relationship,two theoretical upper bounds of the orthogonality error of basis vectors in signal subspace are obtained and it is demonstrated that the orthogonality of basis vectors based on HMSWF is perfectly preserved by the numerically well-behaved Householder matrix,and the corresponding signal subspace estimation is much more numerically stable than that based on *** show the numerical stability of the proposed method of signal subspace estimation by HMSWF.

关键词： multistage Wiener filter subspace estimation Householder transform numerical stability Arnoldi algorithm

Brain development in newborns and infants after ECMO

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World Journal of Pediatrics 2024年第6期20卷 556-568页

作者： Kai Yan lu-Kun Tang Fei-Fan Xiao Peng Zhang Guo-Qiang Cheng Lai-Shuan Wang Chun-Mei lu Meng-Meng Ge li-Yuan Hu Yuan-feng Zhou Tian-Tian Xiao Yan Xu Zhao-Qing Yin Gang-feng Yan Guo-Ping lu Qi li Wen-Hao Zhou department of Neonatology Children Hospital of Fudan UniversityShanghai 201102China Kunming Medical university Affiliated Dehong Hospital DehongYunnanChina Graduate School Kunming Medical UniversityKunmingYunnanChina department of Neurology Children's Hospital of Fudan UniversityShanghaiChina School of Medicine Chengdu Women's and Children's Central HospitalUniversity of Electronic Science and Technology of ChinaChengduSichuanChina department of Intensive Care Medicine Children's Hospital of Fudan UniversityShanghaiChina department of Intensive Care Medicine The Sixth Medical Center of PLA General HospitalBeijingChina Key Laboratory of Neonatology National Health Care CommissionShanghaiChina

Background Extracorporeal membrane oxygenation(ECMO)not only significantly improves survival rates in severely ill neonates but also is associated with long-term neurodevelopmental *** systematically review the available literature on the neurodevelopmental outcomes of neonates and infants who have undergone ECMO treatment,with a focus on motor deficits,cognitive impairments,sensory impairments,and developmental *** review aims to understand the incidence,prevalence,and risk factors for these problems and to explore current nursing care and management *** sources A comprehensive literature search was performed across PubMed,EMBASE,and Web of Science using a wide array of keywords and phrases pertaining to ECMO,neonates,infants,and various facets of *** initial screening involved reviewing titles and abstracts to exclude irrelevant articles,followed by a full-text assessment of potentially relevant *** quality of each study was evaluated based on its research methodology and statistical ***,citation searches were conducted to identify potentially overlooked *** the focus was primarily on neonatal ECMO,studies involving children and adults were also included due to the limited availability of neonate-specific *** About 50%of neonates post-ECMO treatment exhibit varying degrees of brain injury,particularly in the frontal and temporoparietal white matter regions,often accompanied by neurological *** occur in 18%–23%of neonates within the first 24 hours,and bleeding events occur in 27%–60%of ECMO procedures,with up to 33%potentially experiencing ischemic *** some studies suggest that ECMO may negatively impact hearing and visual development,other studies have found no significant differences;hence,the influence of ECMO remains *** terms of cognitive,language,and intellectual development,ECMO treatment may be associated with potential deve

关键词： Brain development Extracorporeal membrane oxygenation Infants Neonates Neurological outcomes

Intermediate Spoofing Strategies and Countermeasures

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tsinghua Science and Technology 2013年第6期18卷 599-605页

作者： Yang Gao hong li mingquan lu zhenming feng department of electronic engineering Tsinghua University

Intermediate spoofing can impact most off-the-shelf Global Navigation Satellite Systems （GNSS） receivers, therefore low cost detection of such spoofing is very important to protect the reliability of the GNSS receivers used in critical safety and financial applications. This paper presents two strategies to analyze attacks by intermediate spoofing attackers to identify the weaknesses of such attacks. The analyses lead to a code and carrier phase consistency detection method with simulation results showing that this method can indicate the receiver when spoofing has occurred. The method can be used by most receivers, is inexpensive, and requires only a small software upgrade.

关键词： intermediate spoofing dragging code phase strategy low cost countermeasures code and carrierphase consistency

The Evolution of Photospheric Current Density During an X9.3-Class Solar Flare

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Research in Astronomy and Astrophysics 2024年第10期24卷 189-200页

作者： Hai-li li hong-Fei liang Xin-Ping Zhou Yu liu Ni Meng Yu-Long feng department of Physics Yunnan Normal UniversityKunming 650500China State Key Laboratory of Space Weather Chinese Academy of SciencesBeijing 100190China College of Physics and electronic engineering Sichuan Normal UniversityChengdu 610068China School of Physical Science and Technology Southwest Jiaotong UniversityChengdu 610068China

This paper deduced the temporal evolution of the magnetic field through a series of high-resolution vector magnetograms and calculated the fine distribution map of current density during an X9.3-class flare eruptions using Ampère's *** results show that a pair of conjugate current ribbons exist on both sides of the magnetic neutral line in this active region,and these conjugate current ribbons persist before,during,and after the *** was observed that the X9.3-class flare brightened in the form of a bright core and evolved into a double-ribbon flare over ***,the position of the double-ribbon flare matches the position of the current ribbons with high accuracy,and their morphologies are very *** investigating the complexity of current density and flare morphology,we discovered a potential connection between the eruption of major flares and the characteristics of current density.

关键词： Sun:activity Sun:magnetic fields Sun:flares methods:data analysis

Low-complexity method for DOA estimation based on ESPRIT

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Journal of Systems engineering and electronics 2010年第5期21卷 729-733页

作者： Xuebin Zhuang Xiaowei Cui mingquan lu zhenming feng department of electronic engineering Tsinghua University Beijing 100084 R R. China

A low-complexity method for direction of arrival（DOA） estimation based on estimation signal parameters via rotational invariance technique（ESPRIT） is *** of using the cross-correlation vectors in multistage Wiener filter（MSWF）,the orthogonal residual vectors obtained in conjugate gradient（CG） method span the signal subspace used by *** computational complexity of the proposed method is significantly reduced,since the signal subspace estimation mainly needs two matrixvector complex multiplications at the iteration of data ***,the prior training data are not needed in the proposed *** overcome performance degradation at low signal to noise ratio（SNR）,the expanded signal subspace spanned by more basis vectors is used and simultaneously renders ESPRIT yield redundant DOAs,which can be excluded by performing ESPRIT once more using the unexpanded signal *** with the traditional ESPRIT methods by MSWF and eigenvalue decomposition（EVD）,numerical results demonstrate the satisfactory performance of the proposed method.

关键词： direction of arrival(DOA) multistage Wiener filter(MSWF) conjugate gradient(CG) estimation signal parameters via rotational invariance technique(ESPRIT) eigenvalue decomposition(EVD).

On the Performances of Estimating Stellar Atmospheric Parameters from CSST Broad-band Photometry

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Research in Astronomy and Astrophysics 2024年第4期24卷 161-173页

作者： Rui-feng Shi Yang Huang Xin-Yi li Hua-Wei Zhang School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China South-Western Institute for Astronomy Research Yunnan UniversityKunming 650500China CAS Key Lab of Optical Astronomy Key Laboratory of Space Astronomy and TechnologyNational Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China College of Physics and electronic engineering Qilu Normal UniversityJinan 250200China department of Astronomy School of PhysicsPeking UniversityBeijing 100871China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China

Deriving atmospheric parameters of a large sample of stars is of vital importance to understand the formation and evolution of the Milky *** surveys,especially those with near-ultraviolet filters,can offer accurate measurements of stellar parameters,with the precision comparable to that from low/medium resolution *** this study,we explore the capability of measuring stellar atmospheric parameters from Chinese Space Station Telescope(CSST)broad-band photometry(particularly in the near-ultraviolet bands),based on synthetic colors derived from model *** find that colors from the optical and near-ultraviolet filter systems adopted by CSST show significant sensitivities to the stellar atmospheric parameters,especially the *** to our mock data tests,the precision of the photometric metallicity is quite high,with typical values of0.17 and 0.20 dex for dwarf and giant stars,*** precision of the effective temperature estimated from broad-band colors are within 50 K.

关键词： methods:data analysis stars:abundances surveys

A Vector Tracking Loop Based on ML Estimation in Dynamic Weak Signal Environments

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A Vector Tracking Loop Based on ML Estimation in Dynamic Wea...

The Analysis and Simulation of Multipath Error Fading Characterization in Different Satellite Orbits

第三届中国卫星导航学术年会

作者： Jing liu, Xiaowei Cui, mingquan lu and zhenming feng department of electronic engineering, tsinghua university, beijing, china

Vehicle positioning with GNSS in urban environments faces two problems which are attenuation and dynamic. In the tracking loops of traditional GNSS receivers, using non-coherent discriminators, thermal noise error and dynamic stress threshold are contradictory. Thus, it is difficult for the traditional tracking loops using non-coherent discriminators to track weak signals in dynamic environments. In order to improve the tracking sensitivity of GNSS receiver in dynamic weak signal environments, a Joint Vector Position Tracking Loop （JVPTL） is proposed in the paper, in which the design of discriminator is based on Maximum likelihood Estimation （MLE） according to the linear model of received baseband signal. Thus, the discriminator in the JVPTL is a coherent discriminator, which has relatively small discriminating errors and is able to ease the contradiction between thermal noise error and dynamic stress threshold. Moreover, the JVPTL tracks user position and velocity directly and takes full advantage of the coupling between codes and carriers of all visible satellite signals to reduce thermal noise error. Therefore, the proposed JVPTL is able to track dynamic weak signal. Simulation results show that in dynamic weak signal environments, the JVPTL performs better than the VDFLL with non-coherent discriminators.

关键词： Weak Signal·Dynamic·ML Estimation·Vector Tracking Loop·Coherent Discriminator

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The Analysis and Simulation of Multipath Error Fading Charac...

Pd/N-doped carbon dots@dendritic mesoporous silica nanospheres:A highly efficient catalyst for the hydrogenation of 4-nitrophenol

第三届中国卫星导航学术年会

作者： Gao Yang*1, Cui Xiaowei, lu mingquan, li hong, feng zhenming GNSS Lab, department of electronic engineering, tsinghua university, beijing, china

The "Standing multipath" was discovered when ranging to the GEO satellite in WAAS, the fading characterization of the range multipath error of the GEO satellites is quite different from that of the MEO satellite in GPS, which causes problems for the use of WAAS. This phenomenon shows that the orbit type affects the multipath fading. In this paper, the influences of the satellite orbit on the multipath fading will be focused: by using mathematical models, the fading frequency in different models will be unified into a general form, base on which, environment factor, the signal factor and the satellite moving factor on the fading frequency will be shown clearly. The fading frequency and fading characteristic in different orbits will be discussed qualitatively. Then simulations will be made to show the fading characteristic intuitively. Special fading characteristic in GEO orbit will be discovered and explained. Furthermore, the "stainding multipath" in WAAS will be recovered in computer simulation. The research in this article gives an analysis about multipath error fading characteristic in different orbits, shows the typical fading characteristic.

关键词： fading frequency fading characterization satellite orbit type

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Nano Research 2024年第9期17卷 7967-7974页

作者： Weiruo liu Yanbin Zhu Jiwei Wang Haisong feng Yunpu Zhai Wei li Dongyuan Zhao College of Chemistry Zhengzhou University100 Kexue AvenueZhengzhou 450001China department of Chemistry Laboratory of Advanced MaterialsShanghai Key Laboratory of Molecular Catalysis and Innovative Materialsand State Key Laboratory of Molecular Engineering of PolymersFudan UniversityShanghai 200433China State Key Laboratory of Chemical Resource engineering Beijing Advanced Innovation Center for Soft Matter Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China

Highly dispersed Pd/N-doped carbon dots(Pd/NCDs)were successfully immobilized in the mesoporous channels of amino-functionalized dendritic mesoporous silica nanospheres(NMS).The synthesized Pd/NCDs@NMS catalyst exhibits outstanding performance in the catalytic reduction of 4-nitrophenol(4-NP),achieving a turnover frequency of 1461.8 mol·molPd^(-1)·h^(-1),with the conversion rate remaining above 80%after 11 *** and density functional theory calculations reveal that the NCDs significantly affect the electronic structure of Pd nanoparticles,leading to changes in the energy barriers for the adsorption of 4-NP at the Pd sites and the conversion of 4-NP reaction intermediates,which is a key factor contributing to the catalytic *** study offers a new strategy for synthesizing carbon-dot-modified metal-based catalysts.

关键词： palladium nanoparticles nitrogen-doped carbon dots dendritic mesoporous silica catalytic hydrogenation 4-nitrophenol reduction