检索结果-南通市图书馆

A newly unraveled 13.6-year oscillation from GPS displacements and its potential implications for the dynamic reference frame

引用

Science China Earth Sciences 2024年第10期67卷 3204-3212页

作者： Hao ding Weiping JIANG School of Geodesy and Geomatics Hubei Luojia LaboratoryWuhan UniversityWuhan 430079China GNSS Research Center Wuhan UniversityWuhan 430079China

Numerous practical geodetic and geophysical applications necessitate precise measurements of GNSS displacements at the millimeter or sub-millimeter level. To attain such precision, it is imperative to identify and analyze the unidentified decadal signals inherent in the GPS displacements. In this research, we employ the optimal sequence estimation method to effectively detect an about 13.6-year oscillational signal with an excited amplitude of 3.6±1.2 mm in the U-components of the GPS displacements. It is noteworthy that this signal demonstrates a consistent spatial pattern characterized by the spherical harmonic Y_(2,-2). We conduct a comparative analysis with the 13.6-year oscillation observed in length-of-day variations(and geomagnetic records), finding that they are in reverse phase. After eliminating the Earth's external excitation sources through the utilization of two distinct in-situ hydrological records, we suggest that the 13.6-year GPS signal may come from the internal motions within the Earth. However, the specific excitation source and the detailed physical mechanism remain uncertain. Additionally, we develop a mathematical displacement model to explain the 13.6-year signal. Our findings indicate that this signal can result in displacements of up to 1.37 mm and velocity effects of 0.63 mm/yr(for U-component) at maximum. These results underscore the necessity of incorporating this 13.6-year signal into the construction and maintenance of a dynamic reference frame at the millimeter level.

关键词： GPS displacements Decadal changes 13.6-year oscillation Displacement model Dynamic reference frame

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

From London buses to activity trackers:A reflection of 70 years of physical activity research

引用

Journal of Sport and Health Science 2024年第6期13卷 736-738页

作者： ding ding Ulf Ekelund Prevention Research Collaboration Sydney School of Public HealthFaculty of Medicine and HealthThe University of SydneyCamperdownNSW 2006Australia Charles Perkins Centre The University of SydneyCamperdownNSW 2006Australia Department of Sports Medicine Norwegian School of Sports SciencesOslo 0806Norway Department of Chronic Diseases Norwegian Institute of Public HealthOslo 0213Norway

In 1953,Morris et al.^(1)published their ground-breaking findings among London bus drivers and conductors,linking physical activity to a major chronic disease for the first *** seminal paper marked the birth of a new field—physical activity epidemiology.^(1)Since then,the field has flourished,evidenced by mounting scientific publications.^(2)Our knowledge about the role of physical activity in disease prevention has expanded from coronary heart disease in Morris et al.’s^(1)initial study to dozens of additional diseases and conditions,such as diabetes,cancers,and dementia.^(3)More than 7 decades and thousands of publications later,we critically reflect on several aspects of the progress in physical activity epidemiology.

关键词： epidemiology prevention linking

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

New advances in the study of Tethyan Geodynamic System

引用

Science China Earth Sciences 2024年第3期67卷 874-878页

作者： Lin ding State Key Laboratory of Tibetan Plateau Earth System Science(LATPES) Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China

Tethyan Ocean was initially proposed by Austrian geologist Eduard Suess in 1893. The study of the Tethyan evolution by European geologists has led to the development of modern geology, but not to the establishment of plate tectonics theory(Trümpy, 2001). With the progress in various studies, the concept of Tethys has evolved from a Mesozoic ocean into three long-term evolving oceans:Proto-Tethys, Paleo-Tethys, and Neo-Tethys (Figure 1), and their life cycles cover the entire Phanerozoic era (Wu et al., 2020).

关键词： geology Mesozoic ocean

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

Equivalent linear model for seismic damage evaluation of single-degree-of-freedom systems representing reinforced concrete structures considering cyclic degradation behavior

引用

Earthquake Engineering and Engineering Vibration 2024年第3期23卷 637-648页

作者： Lulu Yan ding-Hao Yu Research Center for Geotechnical and Structural Engineering Technology of Liaoning Province Dalian UniversityDalian116622China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

In this study,a novel equivalent damping ratio model that is suitable for reinforced concrete(RC)structures considering cyclic degradation behavior is developed,and a new equivalent linearization analysis method for implementing the proposed equivalent damping ratio model for use in seismic damage evaluation is *** this end,Ibarra’s peak-oriented model,which incorporates an energy-based degradation rule,is selected for representing hysteretic behavior of RC structure,and the optimized equivalent damping for predicting the maximum displacement response is presented by using the empirical method,in which the effect of cyclic degradation is ***,the relationship between the hysteretic energy dissipation of the inelastic system and the elastic strain energy of the equivalent linear system is established so that the proposed equivalent linear system can be directly integrated with the Park-Ang seismic model to implement seismic damage *** to the simplicity of the equivalent linearization method,the proposed method provides an efficient and reliable way of obtaining comprehensive insight into the seismic performance of RC *** verification demonstrates the validity of the proposed method.

关键词： degrading system equivalent linear system equivalent damping seismic damage RC structures

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

Catalysis by subsurface metal atoms in Al(001) through electron transfer

引用

National Science Review 2024年第4期11卷 12-13页

作者： Bo Sun ding Ma Beijing National Laboratory for Molecular Science New Cornerstone Science Laboratory College of Chemistry and Molecular Engineering Peking University

Heterogeneous catalysis plays a crucial role in the chemical industry, which has evolved from the investigation of chemisorption to an electronic structure[1]. Diverse strategies, such as alloying,doping, and confining, have been applied to enhance the catalytic properties of active sites through electronic modulation. The electron transfer between active sites and substrates profoundly influences catalytic activity [2].

关键词：

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

Constraint on the focal mechanism of the 2011 Tohoku earthquake from the radial modes

引用

Geodesy and Geodynamics 2024年第1期15卷 27-32页

作者： Weikun Chen Hao ding School of Geodesy and Geomatics Hubei LuoJia LaboratoryWuhan UniversityWuhan 430079China

Different from other normal modes of the Earth’s free oscillation that depend on all the six components(M_(rr),M_(tt),M_(pp),M_(rt),M_(rp),and M_(tp))of the centroid moment tensor,the amplitudes of the radial modes depend on the M_(rr)component(e.g.,scalar moment(M_(0)),dip(δ),and slip(λ))and hypocenter depth of the focal mechanism,and hence can be easily used to constrain these parameters of the focal *** this study,we use the superconducting gravimeter(SG)records after the 2011 Tohoku earthquake to analyze the radial modes_(0)S_(0)and_(1)S_(0).Based on the solutions of the focal mechanism provided by the GCMT and USGS,we can obtain the theoretical amplitudes of these two radial *** the theoretical amplitudes with the observation amplitudes,it is found that there are obvious differences between the former and the latter,which means that the GCMT and USGS focal mechanisms cannot well represent the real focal mechanism of the 2011 *** the GCMT solution as a reference and changing the depth and the three parameters of the M_(rr)moment,the scalar moment(M_(0))and the dip(δ)have significant influences,but the effects of the slip(λ)and the depth are *** comparisons,we provide a new constraint(M_(0)=5.8±0.09×10^(22)N·m,δ=10.1±0.08°,λ=88°,and depth=20 km)for the focal mechanism of the 2011 *** addition,we further determine the center frequency(1.631567±2.6e^(-6)mHz)and quality factor(2046.4±50.1)of the_(1)S_(0)mode.

关键词： Focal mechanism Radial modes Gravity observation

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

Deep Reinforcement Learning Based Resource Allocation for Fault Detection with Cloud Edge Collaboration in Smart Grid

引用

CSEE Journal of Power and Energy Systems 2024年第3期10卷 1220-1230页

作者： Qiyue Li Yadong Zhu Jinjin ding Weitao Li Wei Sun Lijian ding Hefei University of Technology Engineering Technology Research Center of Industrial Automation Hefei 230009China Electric Power Research Institute of State Grid Anhui Electric Power Co. Ltd.Hefei 230000China Hefei University of Technology Hefei 230009China IEEE CSEE

Real-time fault detection is important for operation of smart *** has become a trend of future development to design an anomaly detection system based on deep learning by using the powerful computing power of the ***,delay of Internet transmission is large,which may make the delay time of detection and transmission go beyond the ***,the edge-based scheme may not be able to undertake all data detection tasks due to limited computing resources of edge ***,we propose a cloud-edge collaborative smart grid fault detection system,next to which edge devices are placed,and equipped with a lightweight neural network with different precision for fault *** addition,a sub-optimal and realtime communication and computing resource allocation method is proposed based on deep reinforcement *** method greatly speeds up solution time,which can meet the requirements of data transmission delay,maximize the system throughput,and improve communication *** results show the scheme is superior in transmission delay and improves real-time performance of the smart grid detection system.

关键词： Cloud-edge collaboration communication delay deep reinforcement learning fault detection smart grid

来源：

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

A brand new green coating technology for realizing the regulation of spherical propellant energy release process

引用

Defence Technology（防务技术） 2024年第6期36卷 78-94页

作者： Wenhao Fan Yajun ding Zhongliang Xiao School of Chemistry and Chemical Engineering Nanjing University of Science and TechnologyNanjing210094China Key Laboratory of Special Energy Materials Nanjing University of Science and TechnologyMinistry of EducationNanjing 210094China

To achieve the controllable release of energy of nitrocellulose-based propellants,this paper combines the cellulose-based nanocomposites aqueous coating(Surelease®-NC)with fluidized bed coating equipment to successfully prepare the coated spherical propellant for the first *** effects of fluidized bed coating temperature,air velocity,flow speed and atomization pressure on the adhesion rate,coating integrity and coating uniformity of the coated spherical propellant were investigated,and the preparation of coated spherical propellant with homogeneous size and structural integrity was achieved for the first *** microscopic morphology,chemical structure,water vapor adsorption behavior,combustion performance,and ageing resistance property of the coated spherical propellant were systematically investigated by,Fourier transforms infrared spectroscopy(FTIR),Micro confocal raman spectrometer,field scanning electron microscopy(SEM),dynamic vapor adsorption techniques,and closed bomb test,confirming the surface core-shell structure and the tightly bonded interfacial structure of coated spherical ***,the coated spherical propellant has good hygroscopic,excellent progressive burning and long storage stability.

关键词： Nanocomposites aqueous coating Fluidized bed coating equipment Coated spherical propellant Controllable release of energy Long storage stability

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

Optimization of resource allocation in FDD massive MIMO systems

引用

Digital Communications and Networks 2024年第1期10卷 117-125页

作者： Jun Cai Chuan Yin Youwei ding School of Artificial Intelligence and Information Technology Nanjing University of Chinese MedicineNanjing 210046China School of Electronic and Information Hangzhou Dianzi UniversityHangzhou 310018ZhejiangChina

The performance of massive MIMO systems relies heavily on the availability of Channel State Information at the Transmitter(CSIT).A large amount of work has been devoted to reducing the CSIT acquisition overhead at the pilot training and/or CsI feedback *** fact,the downlink communication generally includes three stages,i.e.,pilot training,CsI feedback,and data *** three stages are mutually related and jointly determine the overall system ***,there exist few studies on the reduction of csIT acquisition overhead from the global point of *** this paper,we integrate the Minimum Mean Square Error(MMSE)channel estimation,Random Vector Quantization(RVQ)based limited feedback and Maximal Ratio Combining(MRC)precoding into a unified framework for investigating the resource allocation *** particular,we first approximate the covariance matrix of the quantization error with a simple expression and derive an analytical expression of the received Signal-to-Noise Ratio(SNR)based on the deterministic equivalence *** the three performance metrics(the spectral efficiency,energy efficiency,and total energy consumption)oriented problems are formulated *** practical system requirements,these three metrics can be collaboratively ***,we propose an optimization solver to derive the optimal partition of channel coherence *** results verify the benefits of the proposed resource allocation schemes under three different scenarios and illustrate the tradeoff of resource allocation between three stages.

关键词： Massive MIMO FDD CSIT Resource allocation

来源：

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

Upconversion luminescence and temperature sensing performance of Er^(3+) ions doped self-activated KYb(MoO_(4))_(2) phosphors

引用

Journal of Rare Earths 2024年第8期42卷 1507-1513,I0004页

作者： Ye Tong Wenpeng Liu Shoujun ding School of Microelectronics and Data Science Anhui University of TechnologyMaanshan243002China Advanced Laser Technology Laboratory of Anhui Province Hefei230037China Anhui Institute of Optics and Fine Mechanics Chinese Academy of SciencesHefei230031China

In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction *** phase structure of the as-prepared samples was analyzed by X-ray diffraction(XRD),XRD Rietveld refinement and Fourier transform infrared(FT-IR) *** as-prepared samples retain the orthorhombic structure with space group of Pbcn even Er^(3+) doping concentration up to 15 at%.High-purity upconversion(UC) green emission with green to red intensity ratio of 55 is observed from the as-prepared samples upon the excitation of 980 nm semiconductor laser and the optimum doping concentration of Er^(3+) ions in the self-activated KYb(MoO_(4))_(2) host is revealed as 3 at%.The strong green UC emission is confirmed as a two-photon process based on the power-dependent UC *** addition,the fluorescence intensity ratios(FIRs) of the two thermally-coupled energy levels,namely ^(2)H_(11/2) and ^(4)S_(3/2).of Er^(3+) ions were investigated in the temperature region 300-570 K to evaluate the optical temperature sensor behavior of the *** maximum relative sensitivity(S_(R)) is determined to be 0.0069 K^(-1) at300 K and the absolute sensitivity(S_(A)) is determined to be 0.0126 K^(-1) at 300 *** S_(A) of self-activated KYb(MoO_(4))2:Er^(3+)is almost twice that of traditional KY(MoO_(4))2:Er^(3+)/Yb^(3+)codoping *** results demonstrate that Er^(3+) ions doped self-activated KYb(MoO_(4))2 phosphor has promising application in visible display,trademark security and optical temperature sensors.

关键词： Er^(3+)ions doped KYb(MoO_(4))_(2) Self-activated phosphors Upconversion luminescence Solid-state reaction method Optical temperature sensors Rare earths

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

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：