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Flow-Induced Vibration Fatigue Damage of A Pair of Flexible Cylinders in A Staggered Array

China Ocean Engineering 2021年第6期35卷 878-890页

作者： XU wan-hai LI Yu-han JIA Kun lai Jiang State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China Nuclear Power Institute of China Chengdu 610041China

Flow-induced vibration(FIV)of a group of long,flexible cylinders involves a complex interaction between fluid and *** a substantial number of studies have been devoted to assessing FIV response behaviours,fatigue damage features of staggered flexible cylinders are not fully ***,the wake-induced flutter constitutes an intricate hydrodynamic behaviour that frequently occurs when one cylinder is in the vicinity of another ***,existing studies on the fatigue damage caused by wake-induced flutter are incapable of achieving better *** paper,therefore,estimates the FIV fatigue damage of two staggered flexible cylinders with an aspect ratio of 350 and a mass ratio of 1.90 based on normal S−N curves according to Det Norske Veritas(DNV)*** staggered cases(cross-flow spacing ratios of 2.0,3.0,4.0,and 6.0 and in-line spacing ratios of 4.0,6.0,and 8.0)are discussed for comparison,and fatigue damage caused by wake-induced flutter is thoroughly *** damage results indicate that the variation of the cross-flow(CF)spacing ratio has a greater influence than that of the in-line(IL)spacing ratio on the CF fatigue damage of the upstream *** IL fatigue damages of the upstream cylinder are observed when reduced velocity V_(r)≥15.03 due to the wake flow patterns with different IL spacing ***,wake interference,especially wake-induced flutter,predominates the fatigue damage characteristics of the downstream *** V_(r)=8.77−11.27,wake-induced flutter enhances the IL fatigue damage of the downstream cylinder and slightly affects that of the upstream ***,wake-induced flutter causes considerable IL fatigue damage disparity between the two staggered cylinders by suppressing the IL fatigue damage of the upstream cylinder when V_(r)≥20.04.

关键词： flow-induced vibration fatigue damage flexible cylinder staggered arrangement wake-induced flutter

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中国共病加权指数与老年人卫生服务利用的关联性研究

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中国全科医学 2025年第1期28卷 65-70页

作者：李丽萍廖婧高鑫源王力赖颖斯中山大学公共卫生学院广东省广州市510000 广东省肇庆市疾病预防控制中心传染病预防控制科 526000

背景慢性病共病给老年人卫生服务带来挑战,探索老年人慢性病共病负担对卫生服务利用的影响具有重要意义。中国共病加权指数(CMWI)是衡量我国中老年人群共病负担的指标,目前尚缺乏CMWI与卫生服务利用关联性的队列研究。目的探索老年人慢... 详细信息

背景慢性病共病给老年人卫生服务带来挑战,探索老年人慢性病共病负担对卫生服务利用的影响具有重要意义。中国共病加权指数(CMWI)是衡量我国中老年人群共病负担的指标,目前尚缺乏CMWI与卫生服务利用关联性的队列研究。目的探索老年人慢性病共病负担与卫生服务利用的关联,为改善老年人慢性病共病干预与管理提供科学依据。方法于2021年12月—2024年1月,以广东省肇庆市四会市为例,收集该市全民健康信息平台中2017—2021年的居民电子健康档案信息,建立老年人健康体检自然人群队列。以该时间段内首次体检时间为基线,使用CMWI衡量老年人基线的慢性病共病负担,采用负二项回归分析个体基线的CMWI分别与其在随访时间内利用的总门诊次数、慢性病相关门诊次数、总住院次数以及慢性病相关住院次数的关联性。结果39989例老年人中,14991例(55.18%)患有慢性病共病,CMWI值为1.3(0,2.3);在平均1268 d随访时间内,26141例(65.37%)利用过门诊服务,总门诊次数为2(0,6)次,慢性病相关门诊次数为1(0,4)次;7332例(18.34%)利用过住院服务,总住院次数为0(0,0)次,慢性病相关住院次数为0(0,0)次。不同年龄、性别、文化程度及CMWI的老年人卫生服务利用比较,差异有统计学意义(P0.05)。在调整年龄、性别、居住地、文化程度后,负二项回归分析结果显示,CMWI是老年人卫生服务利用次数增加的危险因素(IRR>1),CMWI每增加1个单位,总门诊次数增加1.210次(95%CI=1.196~1.224次),慢性病相关门诊次数增加1.276次(95%CI=1.259~1.292次),总住院次数增加1.277次(95%CI=1.244~1.312次),慢性病相关住院次数增加1.286次(95%CI=1.252~1.321次)。结论CMWI是老年人卫生服务利用次数增加的危险因素,老年人卫生服务利用次数随CMWI值增大而增加,应重视老年人的慢性病共病负担,为改进我国老年人慢性病共病干预与管理提供科学依据。

关键词：慢性病共病老年人卫生服务利用负二项回归中国共病加权指数

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Minimum Error Entropy Based EKF for GPS Code Tracking Loop

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Computers, Materials & Continua 2021年第6期67卷 2883-2898页

作者： Dah-jing Jwo Jen-Hsien lai Department of Communications Navigation and Control EngineeringTaiwan Ocean University202301TaiwanChina Chunghwa Precision Test Tech.Co. Ltd.Taoyuan City324TaiwanChina

This paper investigates the minimum error entropy based extended Kalman filter(MEEKF)for multipath parameter estimation of the Global Positioning System(GPS).The extended Kalman filter(EKF)is designed to give a preliminary estimation of the *** scheme is designed by introducing an additional term,which is tuned according to the higher order moment of the estimation *** minimum error entropy criterion is introduced for updating the entropy of the innovation at each time *** to the stochastic information gradient method,an optimal filer gain matrix is *** mean square error criterion is limited to the assumption of linearity and ***,non-Gaussian noise is often encountered in many practical environments and their performances degrade dramatically in non-Gaussian *** of the existing multipath estimation algorithms are usually designed for Gaussian *** I(in-phase)and Q(quadrature)accumulator outputs from the GPS correlators are used as the observational measurements of the EKF to estimate the multipath parameters such as amplitude,code delay,phase,and carrier *** reasonable way to obtain an optimal estimation is based on the minimum error entropy *** MEEKF algorithm provides better estimation accuracy since the error entropy involved can characterize all the randomness of the *** assessment is presented to evaluate the effectivity of the system designs for GPS code tracking loop with multipath parameter estimation using the minimum error entropy based extended Kalman filter.

关键词： Entropy extended Kalman filter multipath global positioning system tracking loop

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Construction of three-dimensional hierarchical porous nitrogen-doped re duce d graphene oxide/hollow cobalt ferrite composite aerogels toward highly efficient electromagnetic wave absorption

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Journal of Materials Science & Technology 2023年第1期132卷 193-200页

作者： jing Xu Ruiwen Shu Zongli wan Jianjun Shi State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and TechnologyHuainan 232001China School of Chemical Engineering Anhui University of Science and TechnologyHuainan 232001China Institute of Environment-Friendly Materials and Occupational Health Anhui University of Science and TechnologyWuhu 241003China

The development of graphene-based composites with low density,robust absorption,wide bandwidth and thin thickness remained a great challenge in the field of electromagnetic(EM)*** this work,nitrogen-doped reduced graphene oxide/hollow cobalt ferrite(NRGO/hollow CoFe_(2)O_(4))composite aerogels were constructed by a solvothermal and hydrothermal two-step *** demonstrated that the as-fabricated composite aerogels had the ultralow density and a unique three-dimensional(3D)network structure,and lots of hollow CoFe_(2)O_(4)microspheres were almost homogeneously distributed on the wrinkled surfaces of lamellar ***,superior EM absorbing capacity could be achieved by modulating the ferrite structure,addition amounts of hollow CoFe_(2)O_(4)and *** was noteworthy that the NRGO/hollow CoFe_(2)O_(4)composite aerogel with the addition amount of ferrite of 15.0 mg pos-sessed the minimum reflection loss of-44.7 dB and maximum absorption bandwidth of 5.2 GHz(from 12.6 to 17.8 GHz)at a very thin thickness of 1.8 mm and filling ratio of 15.0 wt.%.Furthermore,the possible EM attenuation mechanism had been *** results of this work would be helpful for developing RGO-based 3D composites as lightweight,thin and highly efficient EM wave absorbers.

关键词： Graphene Composite aerogels Hollow ferrite Three-dimensional network Nitrogen doping

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Experiment on impedance adaptation of under-actuated gripper using tactile array under unknown environment

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Science China(Information Sciences) 2018年第12期61卷 127-140页

作者： jing CUI Mi lai Zhongyi CHU Fuchun SUN School of Mechanical Engineering and Applied Electronics Beijing University of Technology Department of Computer Science and Technology Tsinghua University School of Instrument Science and Opto-electronics Beihang University

The experiment on impedance adaptation to achieve stable grasp for an under-actuated gripper grasping different unknown objects with tactile array is conducted. Under-actuated gripper has a wildly application in the field of space robot and industrial robot because of its better shape-adaptation. However it is difficult to achieve stable grasp owning to the uncertain properties of environment. A control strategy of adaptive matching the impedance parameters is proposed to achieve stable grasp. Firstly, the unknown objects are described as linear systems with unknown dynamics, and the parameters of the object are identified with the recursive least-squares(RLS) method through tactile sensor array. Then a desired impedance model is obtained by defining a cost function that includes the contact force, velocity and displacement errors, and the critical impedance parameters are found to minimize it. Finally, an experiment is presented and shows that the proposed impedance model can guarantee the stable grasp for various unknown objects.

关键词： impedance adaptation under-actuated gripper tactile array stable grasp unknown environment

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Defocus Hyperspectral Image Deblurring with Adaptive Reference Image and Scale Map

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Journal of Computer Science & Technology 2019年第3期34卷 569-580页

作者： De-wang Li Lin-jing lai Hua Huang School of Computer Science and Technology Beijing Institute of TechnologyBeijing 100081China

Defocus blur is one of the primary problems among hyperspectral imaging systems equipped with simple lenses. Most of the previous deblurring methods focus on how to utilize structure information of a single channel, while ignoring the characteristics of hyperspectral images. In this work, we analyze the correlations and differences among spectral channels, and propose a deblurring framework for defocus hyperspectral images. First, we divide the hyperspectral image channels into two sets, and the set with less blur is treated as a group of spectral bases. Then, according to the inherent correlations of spectral channels, a reference image can be derived from the spectral bases to guide the restoration of blurry channels. Finally, considering the disagreement between the reference image and the ground truth, a scale map based on gradient similarity is introduced as a prior in the deblurring framework. The experimental results on public dataset demonstrate that the proposed method outperforms several image deblurring methods in both visual effect and quality metrics.

关键词： hyperspectral image defocus blur deblurring reference image scale map

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Effect of Degree-of-Symmetry on Kinetostatic Characteristics of Flexure Mechanisms:A Comparative Case Study

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Chinese Journal of Mechanical Engineering 2018年第2期31卷 54-65页

作者： Xiao-Bing He jing-Jun Yu wan-wan Zhang Guang-Bo Hao School of Mechanical Engineering and Automation Beihang University School of Engineering-Electrical and Electronic Engineering University College Cork

The current research of kinetostatic characteristics in flexure mechanisms mainly focus on the improvement of accuracy. To reduce or eliminate the parasitic motion is considered as an approach by using the common knowledge of symmetry. However, there is no study on designing the flexure mechanisms with symmetrical features as many as possible for better kinetostatic performance, when considering the resulting cost by the symmetry. In this paper, the concept of degree of symmetry(DoS) is proposed for the first time, which is committed to symmetry design in the phase of conceptual design. A class of flexure mechanisms with 0?DoS, 1?DoS, 2?DoS and 3?DoS are synthesized respectively based on the Freedom and Constraint Topology method. Their overall compliance matrices in an analytical form formulated within the framework of the screw theory are used to analyze and compare the effect of different number of DoS on the kinetostatic characteristics for flexure mechanisms. The finite element analysis(FEA) simulations are implemented to verify the analytical results. These results show that the higher the DoS is, the smaller the parasitic motion error will be. The flexure model with 3?DoS is optimized according to the overall compliance matrix and then tested by using the FEA simulation. The testing result shows that with the best combination parameters, the parasitic motion error for 3?DoS mechanism is almost eliminated. This research introduces a design principle which can alleviate the unwanted parasitic motion for better accuracy.

关键词： Flexure mechanism Symmetry Kinetostatic characteristics FEA simulation

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Density Functional Theory Study on Interaction between Catechin and Thymine

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Chinese Journal of Chemical Physics 2012年第6期25卷 642-648,I0003页

作者： wan-fei Cai Yan Zheng lai-cai Li An-min Tian Departement of Chemistry and Material Science Sichuan Normal University Chengdu 510065China Departement of Chemistry Sichuan University Chengdu 510054 China

The interacting patterns and mechanism of the catechin and thymine have been investigated with the density functional theory Becke＇s three-parameter nonlocal exchange functional and the Lee, Yang, and Parr nonlocal correlation functional （B3LYP） method by 6-31＋G＊ basis set. Thirteen stable structures for the catechin-thymine complexes have been found which form two hydrogen bonds at least. The vibrational frequencies are also studied at the same level to analyze these complexes. The results indicated that catechin interacted with thynfine by three different hydrogen bonds as N-H…O, C-H…O, O-H…O and the complexes are mainly stabilized by the hydrogen bonding interactions. Theories of atoms in molecules and natural bond orbital have been adopted to investigate the hydrogen bonds involved in all systems. The interaction energies of all complexes have been corrected for basis set superposition error, which are from -18.15 k J/mol to -32.99 kJ/mol. The results showed that the hydrogen bonding contribute to the interaction energies dominantly. The corresponding bonds stretching motions in all complexes are red-shifted relative to that of the inonomer, which is in agreement with experimental results.

关键词： Density functional theory Thymine Hydrogen bond Catechin

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Vortical structures and wakes of a sphere in homogeneous and density stratified fluid

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Journal of Hydrodynamics 2021年第2期33卷 207-215页

作者： Liu-shuai Cao Feng-lai Huang Cheng Liu De-cheng wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil Engi-neeringShanghai Jiao Tong UniversityShanghai 200240China Ocean College Zhejiang UniversityZhoushan 316021China

Vortical structures and wakes of bluff bodies in homogenous and stratified environment are common and important in ocean *** on the Boussinesq approximation,a thermocline model is proposed to deal with the variable density stratified fluid,and implemented in the commercial software Simcenter STAR-CCM+*** improved delayed detached eddy simulation(IDDES)modeling method is adopted to resolve the coherent vortical structures and turbulent wakes precisely and *** conditions consisting of one homogenous and three stratified fluid cases with different density gradient past a sphere at Reynolds number 3700 are *** show that density stratification has a great impact on the vortical structures,the vertical motion is suppressed and internal waves will be induced and propagated,which is very different with that of homogenous *** the stratification strength increases,the vortical structures are gradually flattened,the asymmetry and anisotropy between vertical and horizontal motions are enhanced.

关键词： Vortical structures wakes sphere homogenous stratified fluid

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Compressed Sensing of IR-UWB Wireless Sensor Network Data Based on Two-Dimensional Measurements

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Chinese Journal of Electronics 2015年第3期24卷 627-632页

作者： wanG Kai LIU Yulin wan Qun jing Xiaojun Chongqing Communication Institute China Electronic System Engineering Company University of Electronic Science and Technology of China Beijing University of Posts and Telecommunications

A novel Compressed sensing(CS) method based on two-dimensional measurements is proposed that can be effectively utilized in Impulse radio ultra-wideband wireless sensor networks(IR-UWB WSNs) to significantly reduce the energy consumption and sampling rate in sensor data transferring. We start by establishing the CS measurement model by taking both spatial and temporal correlations of Wireless sensor network(WSN) data into account. Since our model incorporates a new type of measurement matrix: the block quasi-Toeplitz structured matrix, we derive the Restricted isometry property(RIP)of the block quasi-Toeplitz structured matrix to ensure the performance of the two-dimensional recovery of WSNs data. We substantiate our mathematical analysis by numerical examples in the context of ideal spares vector and real WSN data, and results demonstrate that the approach achieves significantly saving of energy and sampling rate with small reconstruction error.

关键词： Compressed sensing Wireless sensor net-works IR-UWB Measurement Restricted isometry property

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