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Incompressible Limit of the Compressible Q-tensor System of Liquid Crystals

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Acta Mathematicae Applicatae Sinica 2023年第1期39卷 179-201页

作者： yi-xuan WANG University of Pittsburgh PA 15260USA

We study the connection between the compressible Navier-Stokes equations coupled by the Qtensor equation for liquid crystals with the incompressible system in the periodic case, when the Mach number is low. To be more specific, the convergence of the weak solutions of the compressible nematic liquid crystal model to the incompressible one is proved as the Mach number approaches zero, and we also obtain the similar results in the stochastic setting when the equations are driven by a stochastic force. Our approach is based on the uniform estimates of the weak solutions and the martingale solutions, then we justify the limits using various compactness criteria.

关键词： compressible liquid crystal system Q-tensor weak solutions martingale solution stochastic compactness Mach number incompressible limit

Rts: learning robustly from time series data with noisy label

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Frontiers of Computer Science 2024年第6期18卷 186332-186332页

作者： ZHOU Zhi JIN yi-xuan Li Yu-Feng National Key Laboratory for Novel Software Technology Nanjing University

Significant progress has been made in machine learning with large amounts of clean labels and static data. However, in many real-world applications, the data often changes with time and it is difficult to obtain massive clean annotations, that is, noisy labels and time series are faced simultaneously. For example, in product-buyer evaluation, each sample records the daily time behavior of users, but the long transaction period brings difficulties to analysis, and salespeople often erroneously annotate the user’s purchase behavior. Such a novel setting, to our best knowledge, has not been thoroughly studied yet, and there is still a lack of effective machine learning methods. In this paper, we present a systematic approach RTS both theoretically and empirically, consisting of two components, Noise-Tolerant Time Series Representation and Purified Oversampling Learning. Specifically, we propose reducing label noise’s destructive impact to obtain robust feature representations and potential clean samples. Then, a novel learning method based on the purified data and time series oversampling is adopted to train an unbiased model. Theoretical analysis proves that our proposal can improve the quality of the noisy data set. Empirical experiments on diverse tasks, such as the house-buyer evaluation task from real-world applications and various benchmark tasks, clearly demonstrate that our new algorithm robustly outperforms many competitive methods.

关键词： weakly-supervised learning time-series classification class-imbalanced learning

Response of fine particulate matter to reductions in anthropogenic emissions in Beijing during the 2014 Asia–Pacific Economic Cooperation summit

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Atmospheric and Oceanic Science Letters 2016年第6期9卷 411-419页

作者： GU yi-xuan LIAO Hong State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of Sciences College of Earth Science University of Chinese Academy of Sciences School of Environmental Science and Engineering Nanjing University of Information Science &Technology

The nested-grid capability of the global chemical transport model GEOS-Chem, with a horizontal resolution of 1/4°× 5/16° （latitude x longitude）, was used to identify the chemical species whose reductions made the largest contributions to decreases in PM2.s concentrations （fine particulate matter, diameter 〈 2.5μm, defined in this study as the sum of sulfate, nitrate, ammonium, black carbon, and organic carbon aerosols） in Beijing during the 2014 Asia-Pacific Economic Cooperation （APEC） summit. A number of numerical experiments were carried out for the period 15 October-29 November 2014. The model reproduced the observed daily variations of concentrations of PM2.s and gas-phase species （carbon monoxide, nitrogen dioxide, and sulfur dioxide）. Simulated PM2.s concentrations decreased by 55.9%-58.5% during the APEC period, compared to other periods in October and November 2014, which agreed closely with measurements. Sensitivity results showed that emissions control measures regarding nitrogen oxides and organic carbon over North China led to the largest reductions in PM2.s concentrations in Beijing during the APEC summit, which led to overall reductions in the PM2.5 concentration of Beijing by 5.7% and 4.6%, respectively. The control of ammonia emissions was found to be able to greatly reduce PM2.5 concentrations in the whole of North China during the APEC meeting.

关键词： Fine particulate matter emissions reduction Asia-Pacifc EconomicCooperation Beijing GEOS-Chem

Luminescence properties of nitrogen-rich Ca-SiAlON:Eu2+ phosphors prepared by freeze-drying assisted combustion synthesis

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International Journal of Minerals,Metallurgy and Materials 2020年第5期27卷 687-692页

作者： Zhang-lin Chen Kai Liu xuan-yi Yuan Ke-xin Chen Beijing Key Laboratory of Optoelectronic Functional Materials&Micro-nano Devices Department of PhysicsRenmin University of ChinaBeijing 100872China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100872China

Nitrogen-rich Eu2+-doped Ca-α-SiAlON phosphors(Cam/2-xSi12-m-nAlm+nOnN16-n:xEu) were synthesized by a freeze-drying assisted combustion synthesis(CS) route. Fast-synthesized products with high purity and uniform particle morphology were confirmed by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The analysis of lattice parameters by comparison with empirical equations showed that the as-prepared phosphors had low oxygen content. A series of samples were prepared according to the stoichiometry of Cam/2-0.08Si12-mAlmN16:0.08 Eu for further research. The influences of m value on the luminescence properties were investigated in detail. As m increased, a redshift phenomenon was observed in both the excitation and emission spectra. First-principle electronic structure calculations showed that the 3d energy level of Ca played an important role in the occurrence of the redshift phenomenon.

关键词： freeze-drying combustion synthesis phosphors powder fluorescence spectra first-principle calculation

Optimization Study on Expansion Energy Used Air-Powered Vehicle with Pneumatic-Hydraulic Transmission

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Chinese Journal of Mechanical Engineering 2018年第1期31卷 220-229页

作者： Xiang-Heng Fu Mao-Lin Cai yi-xuan Wang Yan Shi School of Automation Science and Electrical Engineering Beihang University The State Key Laboratory of Fluid Power & Mechatronic Systems Zhejiang University

Pneumatic-hydraulic transmission has been developed for years. However, its dynamic properties are not good enough for application. In this paper, in order to increase the output characteristics, a late-model air-powered vehicle using expansion energy is proposed which can boost energy through a pneumatic-hydraulic transmission. The dynamic characteristics of the air-powered vehicle is modeled and verified by conducting experiment. In addition,the influence of the key parameters of the air-powered vehicle is researched for the optimization of the system performance. Through the results, the author got the conclusion that, firstly, comparison of the results of model and experiment proves the built model to be effective; secondly, input air pressure should be set according to the request of the practical loads, and range of 0.65 to 0.75 MPa can be chosen; thirdly, as a key structure parameter of the airpowered vehicle, ratio of the areas is considered to be set to approximate 8; what’s more, a bigger orifice with a limit will promote the system dynamic characteristic property, and the limit is about 3.5 mm; last but not the least, not too farther position of the rings will increase the quality of output dynamic characteristics. This paper can be a reference for system design of air-powered vehicle and dynamic improvement.

关键词： Air-powered vehicle Expansion energy Pneumatic-hydraulic transmission Output dynamic characteristics

Reynolds number effect on compressible cylindrical cavity flow

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Chinese Journal of Aeronautics 2020年第2期33卷 456-464页

作者： Kung-Ming CHUNG yi-xuan HUANG Kuan-Huang LEE Keh-Chin CHANG Aerospace Science and Technology Research Center National Cheng Kung UniversityTainan 711China Department of Aeronautics and Astronautics National Cheng Kung UniversityTainan 701China

Presence of a cavity changes the mean and fluctuating pressure distributions inside and near the *** cylindrical cavity flow,the diameter-to-depth ratio is the dominant *** this study,flow is naturally developed along a flat plate with two different lengths,resulting in different incoming boundary layer thicknesses ahead of the *** effect of Reynolds number based on incoming boundary layer thickness on characteristics of mean and fluctuating pressure distributions is *** sensitive paint was also used to visualize the mean surface pressure *** effect of Reynolds number on the classification of compressible cylindrical cavity flow and self-sustained oscillating frequency is not *** increase in Reynolds number results in a reduction in the value of differential pressure or momentum flux near the rear edge.

关键词： Cavity flow Compressible flow Convection velocity Open cavity Oscillation

Exosomes:Promising biomarkers and targets for cancer

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World Journal of Gastrointestinal Oncology 2022年第8期14卷 1594-1596页

作者： Zhen Fang yi-xuan Ding Fei Li Department of General Surgery Xuanwu Hospital of Capital Medical UniversityBeijing 100053China

The review article entitled"Exosomes as potential diagnosis and treatment for liver cancer"recently published in World Journal of Gastrointestinal Oncology 2022;14:334-347 concluded that exosomes can be used as effective biomarkers or therapeutic biotargets in liver *** are a hot spot in the field of tumor diagnosis and treatment *** had also previously published a review on exosomes and *** this letter to the editor,we summarize the clinical application prospects and current challenges of exosomes.

关键词： Exosomes Cancer Biomarkers Diagnosis Therapy

Exact Radial Solution of the Non-relativistic Schrdinger Equation for the Helium Atom with the Potential Harmonic Method

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Chemical Research in Chinese Universities 2000年第3期16卷 213-217页

作者： WANG yi-xuan BU Yu-xiang LIU Cheng-bu Faculty of Chemistry Shandong UniversityJinan 250100P.R.China

We proposed a simple potential harmonic(PH) scheme for calculating the non\|relativistic radial correlation energies of atomic systems. The scheme was applied to the low\|lying \%n\%\+1\%S\%(\%n\%=1,2) and \%n\%\+3\%S\%(\%n\%=2,3) states of the helium atom. The results exhibit a very stable convergence characterization in both the angular and radial directions with PH and generalized Laguerre functions(GLF) respectively, even though the method is non\|variational one. The ninth significant figure of the non\|relativistic radial energy(NRE) calculated for the ground state exactly agrees with that of the most accurate literature data from the modified configuration interaction method. The convergent NRE′s for the excited states 2\+1\%S\%, 2\+3\%S\% and 3\+3\%S\% with the similar accuracy were also obtained.

关键词： Potential harmonic Radial limit Schrdinger equation Helium atom

Synthesis and Crystal Structure of a Mononuclear Zn(II) Complex with Tridentate Schiff Base,Zn(C_(12)H_(18)N_2O)(NCS)_2

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Chinese Journal of Structural Chemistry 2006年第9期25卷 1031-1034页

作者： CAI Wen-xuan WEN yi-Hang SU Hong FENG Yun-Long Institute of Physical Chemistry Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces Zhejiang Normal University Jinhua 321004 China

The title complex Zn（HL）（NCS）2 （C14H18N4OS2Zn, Mr = 387.81, HL = N-（3-dimethyl-aminopropyl）-salicylaldimine） has been synthesized by the reaction of ZnSO4·7H2O with the Schiff base N-（3-dimethylaminopropyl）-salicylaldimine derived from the condensation reaction of 3-dimethylamino- 1-propylamine with salicyladehyde. It crystallizes in the monoclinic system, space group P21/n with a = 9.8360（8）, b = 14.930（1）, c = 12.277（1） A, β= 101.455（2）°, V= 1767.0（3） A 3, Z = 4, F（000） = 800, Dc= 1.458 g/cm^3 and ,μ（MoKα） = 1.631 mm^-1. The structure was refined to R = 0.0463 and wR = 0.1065 for 2681 observed reflections （1 〉 2σ（I））. Crystal analyses revealed that the Zn（Ⅱ） atom is coordinated by two nitrogen atoms of two NCS^-, and an oxygen atom as well as a nitrogen atom of amine from the neutral Schiff base ligand of N-（3-dimethyl-aminopropyl）-salicylaldimine to give a distorted tetrahedral geometry.

关键词： 3-dimethylamino-1-propylamine salieylaldehyde Sehiff base,