一种基于视觉特征的地形模型数据提取与快速显示方法

DEM模型是一种重要的地形模型，由于其数据量极其巨大，如何实现快速显示是一个难题。针对DEM地形模型，提出基于视点与观察分辨率的数据抽取及基于法矢量的模型简化的快速绘制方法算法，最后进行实验验证。结果表明，该方法数据压缩量大，绘制速度快，且逼真度无明显变化。     

数据库知识发现技术及其在测绘中的应用

详细介绍了数据挖掘与数据库中的知识发现 (KDD)技术 ,给出了KDD的定义以及KDD具体实现的3种处理模型 ,并从GIS和遥感影像分析两个方面论述了KDD技术在测绘中的应用     

藏北高原双湖地区中侏罗统海相油页岩生物标志化合物分布特征及其意义

重点报道了藏北双湖地区中侏罗统海相油页岩的生物标志化合物特征,首次在该层位油页岩中检出丰富的正烷烃、类异戊二烯烷烃、萜类化合物及甾类化合物。正烷烃图谱呈单峰形,nC₁₅、nC₁₆或nC₁₇为主峰碳,轻烃组份占有绝对优势,OEP值 0.93～ 1.0 1,无明显的奇偶碳数优势分布;Pr/Ph值为 0.77～ 1.5 9,在剖面序列中呈波动分布,显示弱植烷优势或姥鲛烷优势;藿烷以C₃₀ 占优势,萜烷相对丰度五环三萜烷 >三环萜烷 >四环萜烷;规则甾烷∑ (C₂₇+C₂₈) >∑C₂₉,∑C₂₇/∑C₂₉值为 0.79～ 1.2 0,在剖面序列中下部C₂₇甾烷略占优势,上部C₂₉甾烷略占优势,重排甾烷C₂₇/规则甾烷C₂₇值为 0.5 1～ 3.6 3,在剖面序列中具有显著的波动性,同时检出了少量孕甾烷和 4-甲基甾烷。有机质母质构成中,既有丰富的藻类等低等水生生物,可能还有一定比例陆生高等植物输入混合的特点。油页岩处于成熟阶段,整个油页岩剖面序列具有一致的热演化程度。剖面中部油页岩具有极高的原始生产力,氧化-还原条件也是控制油页岩TOC和沥青“A”含量在剖面垂向变化的重要因素.     

Gyrolithes:边缘海沉积的特征遗迹化石

Gyrolithes为螺旋形垂直居住潜穴,是具成对附肢的两侧对称甲壳类所建造,出现在近海泻湖和河口湾等边缘海和极浅海环境中,常与半咸水条件有关。塔里木盆地塔中地区诸多钻井的下志留统塔塔埃尔塔格组上部大量发育有此类潜穴,在局部层位可形成强烈的扰动构造。伴生的遗迹化石很少,只有极个别的Beaconites。根据沉积学、地球化学和古生态学特征,这类潜穴形成在半咸水的泻湖环境中。这类潜穴外壁基本平直,在泥质沉积物中掘穴深度大而不变形,而且其充填物与围岩完全不同,这些特点表明Gyrolithes为固底控制的遗迹化石。     

A correlation between the distributions of pulsars and emission measures in the galaxy

A correlation has been detected between the volume density of pulsars and the density of interstellar ionized gas on scales of more than 500 pc in Galactic longitude and 200 pc in Galactic latitude. On smaller scales, the correlation is present only for pulsars with ages less than 60000 years, which are located predominantly near supernova remnants and H II regions. This all indicates that pulsars are born in regions with high concentrations of interstellar gas. The minimum emission measures observed in the directions toward pulsars are inversely proportional to the pulsar ages. It is concluded that the ionized gas in the vicinities of a number of pulsars was formed during supernova explosions, and corresponds to Strömgren zones. The ionization of the gas in these zones requires a radiation energy on the order of 10⁵⁰–10⁵¹ erg.     

Sustainable landscape management in Slovenia: Environmental improvements for the Velenje coal mining community 1991–2000

The Velenje area (almost 200 km² with over 31,000 inhabitants) is based on the Šalek Valley, which became a leading area of industrialisation and urbanisation after the Second World War, with consequent pollution problems. Various industrial plants polluted the river Paka while more serious hazards arose through the coal mine which is a still causing landscape subsidence and the thermal power station in the neighbourhood of Šoštanj which is a major source of sulphur dioxide and nitrogen oxide pollution. In 1987 there was an ecological protest which marked the beginning of a sustainable development strategy for the community. During the past decade programmes have dealt with the degradation of air, soil and water to achieve cleaner air, a transformation in landuse and enhancement the river's formerly weak self-purifying capabilities. This article examines the changes in the valley since the attention of the authorities was drawn to the deterioration of living conditions. Despite the pressures of transition which have seen unemployment rising to over ten percent, significant environmental improvements have been made and the area stands as a model for the rest of the country. This revised version was published online in July 2006 with corrections to the Cover Date.     

A magnetized disk around an O star in W75N. A VLBI map of the OH maser

W75N is a star-forming region containing ultracompact H II regions as well as OH, H₂O, and methanol masers. The VLBA maps obtained show that the masers are located in a thin disk rotating around an O star, which is the exciting star for the ultracompact H II region VLA1. A separate group of maser spots is associated with the ultracompact H II region VLA2. The radial velocity of the maser spots varies across the disk from 3.7 to 10.9 km/s. The disk diameter is 4000 AU. The maser spots revolve in Keplerian orbits around the O9 star.     

Three－dimensional Global Scale Permanent－wave Solutions of the Nonlinear Quasigeostrophic Potential Vorticity Equation and Energy Dispersion

The three-dimensional nonlinear quasi-geostrophic potential vorticity equation is reduced to a linear form in the stream function in spherical coordinates for the permanent wave solutions consisting of zonal wavenumbers from 0 to n and rn vertical components with a given degree n. This equation is solved by treating the coefficient of the Coriolis parameter square in the equation as the eigenvalue both for sinusoidal and hyperbolic variations in vertical direction. It is found that these solutions can represent the observed long term flow patterns at the surface and aloft over the globe closely. In addition, the sinusoidal vertical solutions with large eigenvalue G are trapped in low latitude, and the scales of these trapped modes are longer than 10 deg. lat. even for the top layer of the ocean and hence they are much larger than that given by the equatorial β-plane solutions. Therefore such baroclinic disturb-ances in the ocean can easily interact with those in the atmosphere.Solutions of the shallow water potential vorticity equation are treated in a similar manner but with the effective depth H = RT / g taken as limited within a small range for the atmosphere.The propagation of the flow energy of the wave packet consisting of more than one degree is found to be along the great circle around the globe both for barotropic and for baroclinic flows in the atmosphere.     

Fluorine in tourmalines

The determination of the fluorine content of courmalines yielded 0.28% as an average value for schorlites and dravites and 0.97% for elbaites. The plot of the fluorine contents against the lithium contents shows that the distribution of projection points for pink or green elbaites differs from that for lithian indigolites. Tourmalines are poorer in fluorine than lightcoloured micas at the same stage of pegmatite evolution. Individual regions with pegmatite occurrences can be characterized as rich or poor in fluorine according to the fluorine contents in the tourmalines and micas contained in the pegmatites.     

On a simplified radiative-conductive heat transfer equation

Summary A simplified equation purported to represent the joint influence of radiative and turbulent transfers of heat in the atmosphere is derived by dividing the absorption spectrum of terrestrial radiation into strongly and weakly absorbed regions, classified according to the local scale of variation or to the local heating rate, and introducing two mean absorption coefficients for these two groups of regions. Assurning the validity of theK-theory of turbulent diffusion of heat, it is found that the temperature of the atmosphere is governed by a sixth-order partial differential equation in the heightz. This equation can be simplified to the second order if the mean absorption coefficient of the strongly absorbed regions is much larger while that of the weakly absorbed regions is much smaller than the local scale variation, and the influence of the former is equivalent to an added diffusion while that of the latter is a newtonian cooling, and these two influences are present simultaneously. The values of the two coefficients and their dependencies on the concentration of the absorbing material have been obtained. The equation has been applied to the problem of the thermal interaction between the atmosphere and the underlying earth, as related to the diurnal heat wave, and it was found that the temperature changes within the first few hundred meters from the earth can be predicted accurately by the model when the partition of the two groups is adjusted to the heating rate and the eddy transfer coefficient is allowed to increase very rapidly within the lowest 10 m.