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Assessment of Atmospheric Reanalysis Data Based on Buoy Observations over the Tropical Western Indian Ocean in 2019

Journal of Ocean University of China 2023年第4期22卷 863-873页

作者： LUO Yulan LIU Lin PAUL Oloo PHILIP Sagero LI Kuiping YANG Yang SU Qinglei LI Qiuchi miao zichen First Institute of Oceanography Ministry of Natural Resources and Laboratory for Regional Oceanography and Numerical ModelingPilot National Laboratory for Marine Science and TechnologyQingdao 266061China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 510275China Kenya Meteorological Department Nairobi 30259Kenya Department of Geography Earth Science and EnvironmentThe University of the South PacificBag Suva 17257Fiji

Atmospheric reanalysis data are an important data source for studying weather and climate *** sea surface wind and sea level pressure observations measured from a real-time buoy system deployed in Kenya’s offshore area in 2019 conducted jointly by Chinese and Kenyan scientists were used to evaluate the performance of the major high-frequency atmospheric reanalysis products in the western Indian Ocean *** with observations,the sea level pressure field could be accurately simulated using the atmospheric reanalysis ***,significant discrepancies existed between the surface wind reanalysis data,especially between meridional wind and the observational *** of the data provide a complete understanding of sea level pressure,except for the Japanese 55-year Reanalysis data,which hold a significant system *** Modern-Era Reanalysis for Research and Applications,Version-2,provides an improved description of all *** the reanalysis datasets for zonal wind underestimate the strength during the study *** reanalysis data,NCEP-DOE Atmospheric Model Intercomparison Project reanalysis data presents an inaccurate description due to the worst correlation with the *** meridional wind,most reanalysis datasets underestimate the variance,while the European Centre for Medium-Range Weather Forecasts Atmospheric Composition Reanalysis 4 has a larger variance than the *** addition to the original data comparison,the diurnal variability of sea level pressure and surface wind are also assessed,and the result indicates that the diurnal variations have a significant gap between observation and reanalysis *** study indicates that the current high-frequency reanalysis data still have disadvantages when describing the atmospheric parameters in the Western Indian Ocean region.

关键词： Bailong buoy reanalysis Indian Ocean sea level pressure surface wind

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Multicontrast Pocket Colposcopy Cervical Cancer Diagnostic Algorithm for Referral Populations

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Biomedical Engineering Frontiers 2022年第1期3卷 381-393页

作者： Erica Skerrett zichen miao Mercy N.Asiedu Megan Richards Brian Crouch Guillermo Sapiro Qiang Qiu Nirmala Ramanujam Department of Biomedical Engineering Duke UniversityDurhamNCUSA Department of Electrical and Computer Engineering Purdue UniversityWest LafayetteINUSA Department of Computer Engineering Massachusetts Institute of TechnologyCambridgeMAUSA Department of Electrical and Computer Engineering Department of Biomedical EngineeringDepartment of Computer ScienceDepartment of MathematicsDuke UniversityDurhamNCUSA

Objective and Impact *** use deep learning models to classify cervix images—collected with a low-cost,portable Pocket colposcope—with biopsy-confirmed high-grade precancer and *** boost classification performance on a screened-positive population by using a class-balanced loss and incorporating green-light colposcopy image pairs,which come at no additional cost to the *** the majority of the 300,000 annual deaths due to cervical cancer occur in countries with low-or middle-Human Development Indices,an automated classification algorithm could overcome limitations caused by the low prevalence of trained professionals and diagnostic variability in provider visual *** dataset consists of cervical images(n=1,760)from 880 patient *** optimizing the network architecture and incorporating a weighted loss function,we explore two methods of incorporating green light image pairs into the network to boost the classification performance and sensitivity of our model on a test *** achieve an area under the receiver-operator characteristic curve,sensitivity,and specificity of 0.87,75%,and 88%,*** addition of the class-balanced loss and green light cervical contrast to a Resnet-18 backbone results in a 2.5 times improvement in *** methodology,which has already been tested on a prescreened population,can boost classification performance and,in the future,be coupled with Pap smear or HPV triaging,thereby broadening access to early detection of precursor lesions before they advance to cancer.

关键词： boost network backbone

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AED-Net:An Abnormal Event Detection Network

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Engineering 2019年第5期5卷 930-939页

作者： Tian Wang zichen miao Yuxin Chen Yi Zhou Guangcun Shan Hichem Snoussi School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Department of Electronic Engineering Dalian Maritime UniversityDalian 116026China School of Instrumentation Science and Opto-electronic Engineering&International Research Institute for Multidisciplinary Science Beihang UniversityBeijing 100191China Institute Charles Delaunay-LM2S-UMR STMR 6281 CNRS University of Technology of TroyesTroyes 10010France

It has long been a challenging task to detect an anomaly in a crowded *** this paper,a selfsupervised framework called the abnormal event detection network(AED-Net),which is composed of a principal component analysis network(PCAnet)and kernel principal component analysis(kPCA),is proposed to address this *** surveillance video sequences of different scenes as raw data,the PCAnet is trained to extract high-level semantics of the crowd’s ***,kPCA,a one-class classifier,is trained to identify anomalies within the *** contrast to some prevailing deep learning methods,this framework is completely self-supervised because it utilizes only video sequences of a normal *** in global and local abnormal event detection are carried out on Monitoring Human Activity dataset from University of Minnesota(UMN dataset)and Anomaly Detection dataset from University of California,San Diego(UCSD dataset),and competitive results that yield a better equal error rate(EER)and area under curve(AUC)than other state-of-the-art methods are ***,by adding a local response normalization(LRN)layer,we propose an improvement to the original *** results demonstrate that this proposed version performs better by promoting the framework’s generalization capacity.

关键词： Abnormal events detection Abnormal event detection network Principal component analysis network Kernel principal component analysis

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Optimized Mask-RCNN model for particle chain segmentation based on improved online ferrograph sensor

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Friction 2024年第6期12卷 1194-1213页

作者： Shuo WANG miao WAN Tonghai WU zichen BAI Kunpeng WANG Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System Xi’an Jiaotong UniversityXi’an 710049China

Ferrograph-based wear debris analysis(WDA)provides significant information for wear fault analysis of mechanical *** decades of offline application,this conventional technology is being driven by the online ferrograph sensor for real-time wear state ***,online ferrography has been greatly limited by the low imaging quality and segmentation accuracy of particle chains when analyzing degraded lubricant oils in practical *** address this issue,an integrated optimization method is developed that focuses on two aspects:the structural re-design of the online ferrograph sensor and the intelligent segmentation of particle *** enhancing the imaging quality of wear particles,the magnetic pole of the online ferrograph sensor is optimized to enable the imaging system directly observe wear particles without penetrating ***,a light source simulation model is established based on the light intensity distribution theory,and the LED installation parameters are determined for particle illumination uniformity in the online ferrograph *** this basis,a Mask-RCNN-based segmentation model of particle chains is constructed by specifically establishing the region of interest(ROI)generation layer and the ROI align layer for the irregular particle *** these measures,a new online ferrograph sensor is designed to enhance the image acquisition and information extraction of wear *** verification,the developed sensor is tested to collect particle images from different degraded oils,and the images are further handled with the Mask-RCNN-based model for particle feature *** results reveal that the optimized online ferrography can capture clear particle images even in highly-degraded lubricant oils,and the illumination uniformity reaches 90%in its imaging *** importantly,the statistical accuracy of wear particles has been improved from 67.2%to 94.1%.

关键词： wear particle analysis online ferrography particle image acquisition particle chain segmentation

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Interaction effects of DNA, RNA-polymerase, and cellular fluid on the local dynamic behaviors of DNA

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Applied Mathematics and Mechanics(English Edition) 2020年第4期41卷 623-636页

作者： Weipeng HU zichen DENG School of Civil Engineering and Architecture Xi’an University of TechnologyXi’an 710048China State Key Laboratory of Eco-Hydraulics in Northwest Arid Region of China Xi’an University of TechnologyXi’an 710048China School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China

In view of the complex structure and environment,the dynamic analysis on deoxyribonucleic acid(DNA)is a challenge in the biophysics *** the local interaction with ribonucleic acid(RNA)-polymerase as well as the dissipative effect of cellular fluid,a coupling sine-Gordon-type dynamic model is used to describe the rotational motions of the bases in ***,the approximate symmetric form is ***,the wave form and the wave velocity of the kink solution to the proposed dynamic model are investigated by a Runge-Kutta structure-preserving scheme based on the generalized multi-symplectic *** numerical results indicate that,the strengthening of the local interaction between DNA and RNA-polymerase described by the coupling potential makes the form of the kink solution steep,while the appearance of the friction between DNA and cellular fluid makes the form of the kink solution *** addition,the appearance of the friction decreases the velocities of both the symplectic configuration and the anti-symplectic configuration with different *** above findings are beneficial to comprehend the DNA transcription mechanism.

关键词： deoxyribonucleic acid (DNA) dynamics local interaction generalized multisymplectic idea kink solution Runge-Kutta scheme

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Wave Propagation Characteristics in Thick Conventional and Auxetic Cellular Plates

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Acta Mechanica Solida Sinica 2016年第2期29卷 159-166页

作者： Xiaojian Xu zichen Deng Key Laboratory for Special Area Highway Engineering of Ministry of Education School of HighwayChang'an University Department of Engineering Mechanics Northwestern Polytechnical University

Based on Mindlin plate models and Kirchhoff plate models,this study was concerned with the wave propagation characteristics in thick conventional and auxetic cellular structures,with the objective to clarify the effects of negative Poisson＇s ratio,shear factor and orthotropic mechanical properties on the dynamic behaviors of thick *** results revealed that the predictions using variable shear factor in Mindlin plate models resulted in high wave frequencies,which were more significant for plates with negative values of Poisson＇s *** present study can be useful for the design of critical applications by varying the values of Poisson＇s ratio.

关键词： auxetic cellular structure plate frequency shear factor negative Poisson's ratio

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A review of dynamic analysis on space solar power station

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Astrodynamics 2023年第2期7卷 115-130页

作者： Weipeng Hu zichen Deng School of Civil Engineering and Architecture Xi'an University of TechnologyXi'an 710048China State Key Laboratory of Eco-Hydraulics in Northwest Arid Region of China Xi'an University of TechnologyXi'an 710048China School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710072China

The concept of a space solar power station(SSPS)was proposed in 1968 as a potential approach for solving the energy *** the past 50 years,several structural concepts have been proposed,but none have been sent into *** of the main challenges of the SSPS is dynamic behavior prediction,which can supply the necessary information for control strategy *** ultra-large size of the SSPS causes difficulties in its dynamic analysis,such as the ultra-low vibration frequency and large *** this paper,four approaches for the numerical analysis of the dynamic problems associated with the SSPS are reviewed:the finite element,absolute nodal coordinate,foating frame formulation,and structure-preserving *** the merits and shortcomings of the above four approaches are introduced when they are employed in dynamic problems associated with the *** the merits of the aforementioned four approaches,we believe that embedding the structure-preserving method into finite element software may be an effective way to perform a numerical analysis of the dynamic problems associated with the SSPS.

关键词： space solar power station(SSPS) finite element method absolute nodal coordinate method floating frame formulation method structure-preserving method

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Elastic Wave Propagation in Lattice Metamaterials with Koch Fractal

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Acta Mechanica Solida Sinica 2020年第5期33卷 600-611页

作者： Pengcheng Zhao Kai Zhang zichen Deng School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical UniversityXi’an710072China

In this study,the wave propagation properties of lattice metamaterials with Koch fractal structures are investigated in terms of band structures and directional wave *** analytical models of lattice metamaterials are established using the finite element method,and the dispersion relation is solved using the Bloch’s *** band structures of the lattice metamaterials with different numbers of iterations are studied,and the group velocities at a selected frequency are calculated to analyze the directional wave propagation ***,dynamic responses of the finite structures are calculated using commercial finite element software to verify the band gaps and directional wave propagation behaviors in the lattice *** results show that multiple and low band gaps are present in the lattice materials with various geometric parameters of the Koch fractal,and the position of the lowest band gap decreases as the number of iterations *** results indicate the potential applications of lattice metamaterials with Koch fractals for vibration isolation and multi-functional design.

关键词： Elastic wave propagation Lattice metamaterial Koch fractal Band gap Group velocity

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Synthesis and fluorescence behavior of 2,5-diphenyl-l,3,4- oxadiazole-containing bismaleimides and bissuccinimides

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Frontiers of Chemical Science and Engineering 2013年第4期7卷 381-387页

作者： Xin ZHANG zichen LI University of Wuerzburg Institute of Organic Chemistry Am Hubland 97074 Wuerzburg Germany Key Laboratory of Polymer Chemistry & Physics of Ministry of Education College of Chemistry & Molecular Engineering Peking University Beijing 100871 China

Bismaleimides bearing 2,5-diphenyl-l,3,4- oxadiazole chromophores at para, meta, ortho position and corresponding saturated bissuccinimides were synthe- sized. Several synthetic strategies for these bismaleimides were discussed in detail. Almost no or very weak fluorescence was observed for these bismaleimides, however, the bissuccinimides show a strong fluorescence. The effect of molecular geometry on optical behavior and fluorescence quenching mechanism were investigated by UV-vis absorption and fluorescence emission spectro- scopy. The electron coupling of ground state of p- bismaleimide is stronger than those of m- and o- bismaleimides.p-Bissuccinimide displays increasing fluor- escence quantum yields with red shifts of 22-24 nm, compared to m-bissuccinimide. Polymerizable C=C bonds play a key role in the intramolecular fluorescence quenching.

关键词： fluorescence bismaleimide oxadiazole suc-cinimide

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Aero-optical effects simulation technique for starlight transmission in boundary layer under high-speed conditions

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Chinese Journal of Aeronautics 2020年第7期33卷 1929-1941页

作者： Bo YANG zichen FAN He YU School of Astronautics Beihang UniversityBeijing 100083China

Aero-optical effects for starlight transmission in the high-speed flow field will reduce the accuracy of the star sensor on an *** simulations for aero-optical effects usually require plenty of calculations,which cause difficulties when designing a celestial navigation system for a high-speed *** this study,an Aero-Optical Simulator For Starlight Transmission(AOSST)in the boundary layer is *** effectively reduces the computational burden compared to that of the widely used CFD simulation,and it achieves satisfactory *** this simulator,gas ellipsoids satisfying certain design rules are used to simulate coherent density structures in boundary *** rules for the gas ellipsoids are found from published experimental and high-fidelity CFD simulation *** generated wavefront distortion by AOSST is anchored with the scale law for aero-optical distortion in the boundary layer by determining some control parameters,which enables the simulator to output reliable results over a wide range of flight *** numerical examples are provided to verify the performance of *** results demonstrate that AOSST is able to simulate the directional dependence of aero-optical distortions in boundary layers,the variation trend of distorted wavefront shapes with Reynolds number,and the grayscale distribution on the disturbed star map.

关键词： Aero-optical effect Boundary layer Celestial navigation for high-speed aircraft Coherent structure Starlight transmission

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