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Existence of Solutions for Three Dimensional Stationary Incompressible Euler Equations with Nonvanishing Vorticity

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Chinese Annals of Mathematics,Series B 2009年第6期30卷 803-830页

作者： Chunlei TANG Zhouping XIN Department of Mathematics,Southwest University,Chongqing 400715,China The Institute of Mathematical Sciences,The Chinese University of Hong Kong,Hong Kong,China The Institute of Mathematical Sciences,The Chinese University of Hong Kong,Hong Kong,China Department of Mathematics Southwest University Chongqing 400715 China The Institute of Mathematical Sciences The Chinese University of Hong Kong Hong Kong China

In this paper,solutions with nonvanishing vorticity are established for the three dimensional stationary incompressible Euler equations on simply connected bounded three dimensional domains with smooth boundary.A clas... 详细信息

关键词： Three dimensional stationary incompressible Euler equations Boundaryvalue condition Nonvanishing vorticity

How Does a Polymer Brush Repel Proteins?

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Chinese Journal of Polymer Science 2014年第11期32卷 1575-1580页

作者：吴奇 Department of Chemistry The Chinese University of Hong KongShatinN.T.Hong KongChina The Open Laboratory of Bond Selective Chemistry Department of Chemical PhysicsUniversity of Science and Technology of China

The captioned question has been addressed by the steric effect; namely, the adsorption of proteins on a surface grafted with linear polymer chains decreases monotonically as the grafting density increases. However, there is no quantitative and satisfactory explanation why the adsorption starts to increase when the grafting density is sufficiently high and why polyethylene glycol（PEG） still remains as one of the best polymers to repel proteins. After considering each grafted chain as a molecular spring confined inside a ＂tube＂ made of its surrounding grafted chains, we estimated how its free energy depends on the grafting density and chain length, and calculated its thermal energy-agitated chain conformation fluctuation, enabling us to predict an adsorption minimum at a proper grafting density, which agrees well with previous experimental results. We propose that it is such a chain fluctuation that slows down the adsorption kinetically.

关键词： Polymer brush Protein adsorption Antifouling.

Synthesis and structure of a novel MoFe_4S_4 cubane-like cluster (Me_3PhCH_2N)_2[MoFe_4S_4(SC_6H_(11))_7]

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Science China Chemistry 1998年第3期41卷 301-308页

作者：陈昌能邓玉恒洪茂椿温庭斌张纯喜刘秋田卢嘉锡陈小明康北笙周忠远麦松威 1. State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences 350002 Fuzhou China 2. Department of Chemistry Zhongshan University 510275 Guangzhou China 3. Department of Chemistry The Chinese University of Hong Kong Shatin New Territories Hong Kong China

A novel (Me 3PhCH 2N) 2[MoFe 4S 4(SC 6H 11 ) 7] cubane like cluster was obtained from a reaction system including (NH 4) 2MoS 4, FeCl 2 and NaSC 6H 11 in methanol, and characterized by X ray crystallography. The title compound crystallizes in triclinic space group P 1 with a =1.523 1(3), b =1.610 5(3), c =1.838 3(4) nm, α =77.18 (3)°, β =75.17(3)°, γ =64.60 (3)°, and Z =2. Also included in this paper are the discussions on the variation of the reaction products obtained from the participation of cyclohexylthiolate and on the changes of the structural features of the products.

关键词： molybdenum iron sulfur cluster single cubane cluster crystal structure iron cluster.

A study of oil spill detection using ASAR images

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Acta Oceanologica Sinica 2009年第4期28卷 32-37页

作者： WANG Guiwu ZHANG Yuanzhi LIN Hui Institute of Space and Earth Information Science The Chinese University of Hong Kong Shatin NT Hong Kong

The oil spilled worldwide causes ecological disasters that result in enormous damages to the quality of marine environment, and great expenses on clear-up operations are needed. Due to its wide coverage and day-night all-weather observation capability, Synthetic Aperture Radar （SAR） is an important tool for oil spill monitoring and detection. C-band SAR is well adapted to detect oil pollution because oil slicks dampen the Bragg waves and reduce radar backscattering coefficients. In order to detect the area of oil slicks, the algorithm consists of these steps： Preprocessing, Masking of land areas, Detection of dark spots, Spot feature extraction, Dark spot classification. In this paper, the authors examined two coastal regions around Hong Kong and Yantai, China. The obtained results performed on Envisat ASAR images have demonstrated that it is efficient to detect oil spill around the coastal regions. The methodology still needs to be refined with the collection of more SAR data in the near future.

关键词： Oil spill dectection SAR imagery

Spatial-temporal evolution of injection-induced earthquakes in the Weiyuan Area determined by machine-learning phase picker and waveform cross-correlation

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Earth and Planetary Physics 2021年第6期5卷 485-500页

作者： Wing Ching Jeremy Wong JinPing Zi HongFeng Yang JinRong Su Earth System Science Programme Faculty of ScienceThe Chinese University of Hong KongSha TinHong Kong 999077China Earthquake Monitoring Center Sichuan Earthquake AgencyChengdu 610041China

Anthropogenic induced seismicity has been widely reported and investigated in many regions,including the shale gas fields in the Sichuan basin,where the frequency of earthquakes has increased substantially since the commencement of fracking in late ***,the details of how earthquakes are induced remain poorly understood,partly due to lack of high-resolution spatial-temporal data documenting the evolution of such seismic *** previous studies have been based on a diffusive earthquake catalog constructed by routine ***,however,we have constructed a high resolution catalog using a machine learning detector and waveform *** limited data,this new approach has detected one-third more earthquakes and improves the magnitude completeness of the catalog,illuminating the comprehensive spatial-temporal migration of the emerging seismicity in the target *** of the clusters clearly delineates a potential unmapped fault trace that may have led to the Mw 5.2 in September 2019,by far the largest earthquake recorded in the *** migration of the seismicity also demonstrates a pore-pressure diffusion front,suggesting additional constraints on the inducing mechanism of the *** patterns of the highly clustered seismicity reconcile the causal link between the emerging seismicity and the activity of hydraulic fracturing in the region,facilitating continued investigation of the mechanisms of seismic induction and their associated risks.

关键词： hydraulic fracturing Sichuan Basin machine learning injection-induced earthquake Weiyuan earthquake

Prognostic value of alcohol consumptionand some other dietary habits for survival in a cohort of Chinese men with lung cancer

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Chinese Journal of Cancer 2017年第7期36卷 298-305页

作者： Wentao Li Lap Ah Tse Joseph S.K.Au Kai Shing Yu Feng Wang Ignatius Tak-sun Yu JC School of Public Health and Primary Care The Chinese University of Hong Kong4F School of Public Health and Primary CarePrince of Wales Hospital Department of Clinical Oncology Hong Kong Adventist Hospital

Background:Alcohol consumption and some other dietary habits are thought to be associated with lung cancer ***,the effects of these habits on lung cancer prognosis have been studied *** purpose of this study was to address these gaps in ***:We studied a cohort of 1052 Chinese men in Hong Kong who were diagnosed with primary lung *** proportional hazards models were used to determine the prognostic values of consumption of alcohol,fresh fruits or vegetables,meat,and fried or preserved ***:Compared with never drinkers,men who drank alcohol 1-3 days per week had a more favorable lung cancer prognosis(hazard ratio[HR]:0.82,95%confidence interval[CI]0.68-0.97);however,this survival advantage was not significant in men who drank alcohol more frequently(HR:0.91,95%CI 0.73-1.14).Compared with men who consumed preserved or fried food only occasionally,men who consumed these foods frequently had a higher risk of lung cancer mortality(HR:1.20,95%CI 1.00-1.42).Conclusions:Occasional consumption of alcohol was a favorable survival factor for Chinese men with lung ***,this survival benefit did not exist for frequent drinkers of *** men with lung cancer who were frequent consumers of fried or preserved food had a worse prognosis than those who consumed these foods only occasionally.

关键词： Dietary habits Alcohol Lung cancer Prognosis Epidemiology

A phase model for point spread function estimation in ground-based astronomy

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Science China Mathematics 2013年第12期56卷 2701-2710页

作者： CHAN Raymond Honfu YUAN XiaoMing ZHANG WenXing Department of Mathematics The Chinese University of Hong Kong Department of Mathematics Hong Kong Baptist University School of Mathematical Sciences University of Electronic Science and Technology of China

In ground-based astronomy, images of objects in outer space are acquired via ground-based tele- scopes. However, the imaging system is generally interfered by atmospheric turbulence and hence images so acquired are blurred with unknown point spread function （PSF）. To restore the observed images, aberration of the wavefront at the telescope＇s aperture, i.e., the phase, is utilized to derive the PSF. However, the phase is not readily available. Instead, its gradients can be collected by wavefront sensors. Thus the usual approach is to use regularization methods to reconstruct high-resolution phase gradients and then use them to recover the phase in high accuracy. Here, we develop a model that reconstructs the phase directly. The proposed model uses the tight frame regularization and it can be solved efficiently by the Douglas-Rachford alternating direction method of multipliers whose convergence has been well established. Numerical results illustrate that our new model is efficient and gives more accurate estimation for the PSF.

关键词： point spread function astronomical imaging phase model tight frame alternating directionmethod of multipliers

Repeater-Assisted Zeno Effect in Classical Stochastic Processes

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Chinese Physics Letters 2012年第1期29卷 17-19页

作者： GU Shi-Jian WANG Li-Gang WANG Zhi-Guo LIN Hai-Qing Department of Physics and ITP The Chinese University of Hong KongHong Kong Department of Physics Zhejiang UniversityHangzhou 310027 Department of Physics Tongji UniversityShanghai 200092

We address the possibility of the classical Zeno effect in classical stochastic processes as sampled by transferring a digitized image through a classical channel with surrounding *** is shown that the the classical state of the image decays inevitably with the distance of the channel due to the interference of the ***,if there are enough repeaters,which can both check and recover the state’s information,the classical state’s decay rate will be significantly suppressed,then a classical Zeno effect might occur.

关键词： decay stochastic digit

STM study of selenium adsorption on Au(111)surface

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Chinese Physics B 2020年第5期29卷 435-439页

作者： Bin Liu Yuan Zhuang Yande Que Chaoqiang Xu Xudong Xiao Department of Physics the Chinese University of Hong KongShatinHong KongChina

Adsorption of chalcogen atoms on metal surfaces has attracted increasing interest for both the fundamental research and industrial ***,we report a systematic study of selenium(Se)adsorption on Au(111)at varies substrate temperatures by scanning tunneling *** room temperature,small Se clusters are randomly dispersed on the *** the temperature up to 200℃,a well-ordered lattice of Se molecules consisting of 8 Se atoms in ring-like structure is *** increasing the temperature to 250℃gives rise to the formation of Se monolayer with Au(111)-√3×√3 lattices superimposed with a quasi-hexagonal *** of Se atoms rather than the reaction between the Se atoms and the Au substrate occurs if further increasing the *** ordered structures of selenium monolayers could serve as templates for self-assemblies and our findings in this work might provide insightful guild for the epitaxial growth of the two-dimensional transition metal dichalcogenides.

关键词： STM adsorption selenium structure transitions