Survey on biological fouling and corrosion of vessels

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Reconstruction of the rainfall in rainy season based on historical drought/ flood grades

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Algorithm for extracting intersections in PPV space of filaments

A filament is an important structure for studying star formation,especially intersections of filaments which are believed to be more dense than other regions.Identifying filament intersections is the first step in studying them.Current methods can only extract two-dimensional intersections without considering the velocity dimension.In this paper,we propose a method to identify three-dimensional(3 D)intersections by combining Harris Corner Detection and Hough Line Transform,which achieve a precision of 98%.We apply this method for extracting intersection structures of the OMC-2/3 molecular cloud and to study its physical properties and obtain the associated PDF distribution.Results show denser gas is concentrated in those 3 D intersections.     

七连屿海滩沙-沿岸沙丘-现代植物-砂岛成因模式

海滩沙是砂岛形成的基础,成长初始状态原生态海滩沙是砂岛形成的标志;沿岸沙丘是植被成长屏障,二者都具有重要的研究意义。笔者以2019年科考航次现场海滩沙-沿岸沙丘、砂岛及植被调查与卫星遥感资料分析为基础,对七连屿海滩沙-沿岸沙丘-植被地质特征,形态、位置,它们与砂岛的关系进行讨论;揭示了海滩沙-沿岸沙丘形成不但决定于海浪、潮汐,风暴潮等动力作用,而且也与沉积物搬运过程、沉积作用关系密切;同时探讨了岛屿形成过程中现代植物的分布：从点状发育过渡到逐渐覆盖整个潮上带区域,即先是沿岸沙丘,再是海岛中心,最后呈面状覆盖全岛。其中,植物的定植起到了重要作用,不但能够起到固沙作用,而且参与了砂岛的型成。由此,提出建立七连屿海滩沙-海滩岩-植被-砂岛成因模式。     

An Estimation of the Initial Period of Pulsars

The initial period of a pulsar is an important factor in our understanding of the formation of neutron stars and of the nature of the equation of state of neutron star matter.Up to now this quantity can only be obtained for a few pulsars for which accurate age and braking index are known.Based on the theory of the offcenter dipole emission,in which pulsars obtain theiry high velocities depending on the initial periods,we calculate the initial period using the proper motion data,Because the orbital velocity of the progenitor and asymmetric kick in the supernova explosion may also contribute to the observed velocity of the pusar,the derived values of initial periods are lower limits.For normal pulsars,the initial periods are in the range of 0.6～2.6ms.For the millisecond pulsars,the initial periods are comparable to their current periods,and the ratio between the initial period and the current period increases with the decrease of the current period.For PSR B1937 21 with the shortest period of 1.56ms,the ratio is 0.77.     

Determination of the Proper Motions and Membership of the Globular Cluster M3 and of its Orbit in the Galaxy

We examine 14 plates of the globular cluster M3 (NGC 5272) taken with the 40 cm refractor at the Sheshan station of Shanghai Astronomical Observatory. The plates span over a period of about 77 years. The positions and absolute proper motions of eight stars in the Hipparcos Catalogue and of 49 stars in the Tycho-2 Catalogue are used as the reference frame. The astrometric reduction is made with the central overlapping principle. The absolute proper motions of 534 stars in a region of about 100' × 100' around the cluster are measured. With the new proper motion data the membership probabilities of the stars are determined. The average absolute proper motion obtained for the cluster is -0.06@0.30 mas yr-1 in R.A. and -2.6@0.30 mas yr-1 in Decl. By combining this result with the known distance and radial velocity of the cluster, we also obtained the Galactic orbit of M3 for a chosen three-component Galactic potential.     

GPS DATA INVERSION OF KINEMATIC MODEL OF MAIN FAULTS IN YUNNAN

1　IntroductionThemodernspacegeodesytechnology (GPSes pecially)israpidlydeveloping ,andisabletoprecise lymonitorongoingsurfacechangeprocessatun precedentedspatialandtemporalresolution .Soithasgraduallybecomethemostsuitabletooltoob servegeodynamicalphenomena[1 - 5] .Theearthquakepreparationandoccurrencearecloselyrelatedtofaultanditsmovement.Activefaultanditsquantitativeanalysisisstillthepredomi nantfieldofseismologicalresearch[6,7] .Faultdislo cationmaycausecrustaldeformationaroundit.Onthebas…     

Forecast of blind ore body in Zhangcaigou area around Wulaga gold deposit

By the study of metalflogenetic conditions and ore-controUing factors, the metallogenetic indicators in geology, geochemistry and geophysics about Wulaga gold deposit have been obtained. Using the indicators the blind ore bodies have been forecasted in Zhangcaigou area. By drilling check, a gold-bearing ore body with 3 m thickness in an average tenor of 20.4 × 10^-6at the depth of 70 m has been found in the forecast area. It shows that the forecast method should be effective.     

Environmental records of snow pits in Yuzhufeng Glacier and Xiao Dongkemadi Glacier in the Tibetan Plateau

The contents and distribution characteristics of ions, n-alkanes, and polycyclic aromatic hydrocarbons in snow pits on the Yuzhufeng (YZF) Glacier and the Xiao Dongkemadi (XDKMD) Glacier are studied. Parameter characteristics and correlation coefficients between ions and two organic compounds are used to explore the possible sources of these chemical compositions. The results indicated that both glaciers are influenced by west wind circulation, but the contents of ions, n-alkanes, and polycyclic aromatic hydrocarbons in the YZF Glacier are higher than in the XDKMD Glacier because of differences in geographical position. The ratios of ΣnC₂₁^–/ΣnC₂₂⁺ and CPI values (CPI: carbon preference index) indicate that the n-alkanes from natural sources in these two glaciers are mainly derived from higher plants, whereas the contribution from lower organisms was small, also, n-alkanes from anthropogenic sources in the YZF Glacier are higher than in the XDKMD Glacier. The ratios of LPAHs/HPAHs and (Fly+Pyr)/(BghiP+INP) indicate that the polycyclic aromatic hydrocarbons in these two glaciers are mainly derived from low temperature combustion of coal and biomass, and, in the XDKMD Glacier, partially from the vehicle exhaust.     

Optimizing the ratio of the spike to sample for isotope dilution analysis:a case study with selenium isotopes

Isotope dilution(ID)method has been widely applied to studies of elemental speciation and certification of the concentrations of geological reference materials.One of the key factors restricting the application of the ID method is the difficulty in identifying the optimal ratios of the isotope tracer(spike)to sample(S/N)and in estimating the error propagation.Here,using Se isotope as an example and employing a Monte Carlo method,we found that the optimal choice of spike and S/N are⁷⁷Se(spike)and 0.7,respectively.The S/N in the range from 0.1 to 4 can produce sufficiently low errors(<0.4%).Extending this method to other elements such as Cr,Fe,Ni,Sr,Cd and etc.,their optimal spike and S/N were also presented.According to the optimized parameters of Se,we determined the Se concentrations of geological reference materials(GRMs)by thiol cotton fiber(TCF)-hydride generation ID-MC-ICP-MS.The relative standard deviation is<5%,and the detection limit is reduced to0.1 ng/g.Most of the measured concentrations are consistent with those recommended by IGGE or reported previously.For some GRMs,discrepancies(e.g.6.90%for GSS-5)exist between our measurements and previous ones,which can be explained by the inhomogeneity of GRMs and/or the different digestion,purification and measurement methods among laboratories.