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Global algorithms for maximal eigenpair

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Frontiers of Mathematics in China 2017年第5期12卷 1023-1043页

作者： Mu-fa CHEN School of Mathematical Sciences Beijing Normal University Laboratory of Mathematics andComplex Systems (Beijing Normal University) Ministry of Education Beijing 100875 China

This paper is a continuation of our previous work [Front. Math. China, 2016, 11（6）： 1379-1418] where an efficient algorithm for computing the maximal eigenpalr was introduced first for tridiagonal matrices and then extended to the irreducible matrices with nonnegative off-diagonal elements. This paper introduces mainly two global algorithms for computing the maximal eigenpair in a rather general setup, including even a class of real （with some negative off-diagonal elements） or complex matrices.

关键词： Maximal eigenpair shifted inverse iteration global algorithm

The environmental dependence of different colors in the CMASS sample of the SDSS DR9

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Research in Astronomy and Astrophysics 2014年第5期14卷 553-564页

作者： Xin-fa Deng School of Science Nanchang University

I investigate the environmental dependence of galaxy colors in the CMASS sample of the Sloan Digital Sky Survey Data Release 9 （SDSS DR9）. To decrease the radial selection effect, I divide the CMASS sample into subsamples with a redshift binning size of △z = 0.01 and analyze the environmental dependence of the u - r, u - g, g - r, r - i and i - z colors for these subsamples in each redshift bin. Statistical analysis shows that all five colors weakly correlate with the local environment, which may mean that the environmental processes responsible for a galaxy＇s properties pro- ceed slowly over cosmic time.

关键词： galaxies fundamental parameters -- galaxies statistics

The Nonexistence of the Solutions for the Non-Newtonian Filtration Equation with Absorption

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Journal of Partial Differential Equations 2021年第4期34卷 369-378页

作者： ou Qitong School of Applied Mathematics Xiamen University of TechnologyXiamen 361024China

The paper proves the nonexistence of the solution for the following Cauchy problem{ut=div(|■u^m|(p-2■u^(m)))^-λu^(q),u(x,0)=δ(x),(x,t)∈S_(T)=R^(N)×(0,T),x∈R^(N),under some conditions on m,p,q,λ,whereδis Dirac... 详细信息

关键词： Non-Newtonian filtration equation Cauchy problem nonexistence

Does white-tailed deer density affect tree stocking in forests of the Eastern United States?

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Ecological Processes 2019年第1期8卷 371-382页

作者： brice B.Hanberry Marc D.Abrams USDA Forest Service Rocky Mountain Research StationRapid CitySD 57702USA Department of Ecosystem Science and Management Pennsylvania State University307 Forest Resources BldgUniversity ParkPA16802USA

Background:White-tailed deer(Odocoileus virginianus)have increased during the past century in the *** deer densities may reduce tree regeneration,leading to forests that are understocked,where growing space is not filled completely by *** deer pressure,a major transition in eastern forests has resulted in increased tree ***:To reconcile conflicting trends,we applied generalized linear mixed models to compare deer densities during 1982 and then 1996 to tree stocking after about 30 years and 15 years of potential reductions of small trees by deer,for the entire eastern US and 11 ecological *** also compiled deer browse preferences and compared preferred browse with trends in tree species composition from historical(1620–1900)and current tree ***:The forested area of the eastern US,including a prairie ecological province,was equally well-stocked(52%)and understocked(48%)during 2011–2017 tree *** 1982 deer densities,38%of area had deer densities>5.8 deer/km2 and for 1996,66%of area had deer densities>5.8 deer/*** densities and tree stocking were not related significantly for the entire eastern *** may reduce tree stocking in the Laurentian Mixed Forest;however,this province had both lower deer densities and greater tree stocking than other ***,major tree species trends did not match tree browse ***:Rather than too few trees,too many trees is an ecological problem where historical open oak and pine forests had herbaceous understories,and currently,trees have captured growing *** attribute other drivers than deer to explain this transition.

关键词： Driver Fire Herbivory Open forests Transition Tree density

On the Variation of a Metric and Its Application

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Acta Mathematica Sinica,English Series 2010年第10期26卷 2003-2014页

作者： fa En WU Department of Mathematics School of Science Beijing Jiaotong University Beijing 100044 P. R. China

Some of the variation formulas of a metric were derived in the literatures by using the local coordinates system, In this paper, We give the first and the second variation formulas of the Riemannian curvature tensor, Ricci curvature tensor and scalar curvature of a metric by using the moving frame method. We establish a relation between the variation of the volume of a metric and that of a submanifold. We find that the latter is a consequence of the former. Finally we give an application of these formulas to the variations of heat invariants. We prove that a conformally flat metric g is a critical point of the third heat invariant functional for a compact 4-dimensional manifold M, then （M, g） is either scalar flat or a space form.

关键词： Riemannian functional variation of a metric volume variation space form heat invariant

A tool for the morphological classification of galaxies: the concentration index

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Research in Astronomy and Astrophysics 2013年第6期13卷 651-661页

作者： Xin-fa Deng School of Science Nanchang University

Using galaxy data from the Sloan Digital Sky Survey Data Release 8, I ex- plore whether the concentration index is a good morphological classification tool and find that a reasonable sample of pure late-type galaxies can be constructed with the choice of the r-band concentration index ci=2.85. The opposite is not true, however, due to the fairly high contamination of an early-type sample by late-type galaxies. In such an analysis, the influence of selection effects is less important. To disentangle correlations of the morphology and concentration index with stellar mass, star forma- tion rate （SFR）, specific star formation rate （SSFR） and active galactic nucleus （AGN） activity, I investigate correlations of the concentration index with these properties at a fixed morphology and correlations of the morphology with these properties at a fixed concentration index. It is found that at a fixed morphology, high-concentration galaxies are preferentially more massive and have a lower SFR and SSFR than low- concentration galaxies, whereas at a fixed concentration index, elliptical galaxies are preferentially more massive and have a lower SFR and SSFR than spiral galaxies. This result shows that the stellar mass, SFR and SSFR of a galaxy are correlated with its concentration index as well as its morphology. In addition, I note that AGNs are pref- erentially found in more concentrated galaxies only in the sample of spiral galaxies.

关键词： galaxies: fundamental parameters -- galaxies: statistics

Investigation of the SA evolution by using the CHAOS-4 model over 1997–2013

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Science China Earth Sciences 2016年第5期59卷 1041-1050页

作者： ou JiaMing DU AiMin XU WenYao Key Laboratory of Earth and Planetary Physics Chinese Academy of Sciences Institute of Geology and Geophysics Chinese Academy of Sciences

The temporal and spatial evolution characteristics of the geomagnetic secular acceleration(SA) are investigated, based on CHAOS-4 core field model during the period of 1997–2013. The SA evolution on a short time scale is associated with the phenomenon of the geomagnetic jerk. More details of the global extent and the occurrence time of the successive jerks(the 1999, 2003, 2007, and 2011 jerks) are obtained. The location, size and reversed polarity pattern for the 1999 jerk are similar to those for the 2003 jerk in the Asian-Indian sector. While the 2007 and 2011 jerks mainly take place in the Atlantic sector. The direction and speed of the shift for the four jerks are different, identified by the occurrence time of the jerks. The zonal motions of the SA patches exhibit an oscillation pattern in the Asian-Indian sector, whereas a purely westward drifting pattern is along the equator in the Atlantic sector. It is believed that the shift of the jerks is related to the motion of SA-B_r patches observed at the core-mantle boundary(CMB).

关键词： Geomagnetic secular acceleration Geomagnetic jerk Core-mantle boundary Zonal oscillation

Authenticating GNSS civilian signals:a survey

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Satellite Navigation 2023年第1期4卷 196-213,I0006页

作者： Muzi Yuan Xiaomei Tang Gang ou School of Electronic Science National University of Defense TechnologyChangshaChina

Civilian services of Global Navigation Satellite System are threatened by spoofng attacks since it is hard to determine the authenticity of a navigation signal with a detailed structure open to the *** authentication efectively protects the security of the signal by attaching unforgeable information to one or several elements of the *** can verify the authenticity of the signal by extracting and validating this *** good signal authentication schemes requires understanding possible spoofng modes,signal element specialty,and performance evaluation *** paper is an overview of navigation signal authentication,where the theories and reported approaches are described in detail.A design/performance matrix that demonstrates the advantages and defects of the signal element and its authentication design is *** are proposed to improve the robustness,security,efciency,and implementation hardness for future designs of navigation signal authentication.

关键词： GNSS spoofng Signal authentication Signal structure design Authentication scheme

A highly sensitive DNA-AIEgen-based ＂turn-on＂ fluorescence chemosensor for amplification analysis of Hg^2+ ions in real samples and living cells

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Science China Chemistry 2017年第5期60卷 663-669页

作者： Xiaowen ou Xiaoding Lou fan Xia Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica School of Chemistry and Chemical Engineering Huazhong University of Science and Technology Wuhan 430074 China Shenzhen Institute of Huazhong University of Science and Technology Shenzhen 518000 China

Functional nucleic acids(FNAs)-based biosensors have shown great potential in heavy metal ions detection due to their low-cost and easy to operate merits. However, in most FNAs based fluorescence probes, the ingenious designs of double-labeled(fluorophore and quencher group) DNA sequence, not only bring the annoyance of organic synthesis, but also restrict its use as a robust biosensor in practical duties. In this paper, we design a simple AIEgens functional nucleic acids(AFNAs) probe which consists of only fluorogen but no quencher group. With the help of duplex-specific nuclease(DSN) enzyme based target recycling, high fluorescence signal and superior sensitivity towards Hg^(2+) are achieved. This robust assay allows for sensitive and selective detection of Hg^(2+) in real water samples and mapping of intracellular Hg^(2+), without double-labeling of oligonucleotide with a dye-quencher pair, nor the multiple assay steps.

关键词： functional nucleic acids AIEgen Hg2+ detection real samples living cells