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101.
一种TIN生成算法及其三维显示 总被引:11,自引:1,他引:11
基于三角网的数字高程模型可以逼真地表现地表形态。在Visual C 6.0集成开发环境中构建基于等高线数据的三角网,提高构网的速度和精度,利用0penGL完成基于TIN的三维地貌显示。 相似文献
102.
随着数字技术的发展,数字信号处理芯片的速度越来越快,这为高速数字滤波的实时实现提供了可能。简要阐述了数字滤波的原理,并对两种数字滤波的实现方法进行了分析;给出了数字滤波较模拟滤波的优势;介绍了数字滤波在射电天文测量中的各种应用。 相似文献
103.
Marc W. Pound Jave O. Kane Bruce A. Remington Dmitri D. Ryutov Akira Mizuta Hideaki Takabe 《Astrophysics and Space Science》2005,298(1-2):177-181
Over the past few years, our group has been developing hydrodynamic models to simulate formation of the Eagle Nebula pillars.
The true test of any model is, of course, how well it can reproduce the observations. Here, we discuss how we go about testing
our models against observations. We describe the process by which we “observe” the model data to create synthetic maps. We
show an example of this technique using one of our model runs and compare the resultant synthetic map to the real one. 相似文献
104.
Sarino S. E. Serrano 《Stochastic Environmental Research and Risk Assessment (SERRA)》1990,4(2):151-160
Recognizing that simple watershed conceptual models such as the Nash cascade ofn equal linear reservoirs continue to be reasonable means to approximate the Instantaneous Unit Hydrograph (IUH), it is natural to accept that random errors generated by climatological variability of data used in fitting an imprecise conceptual model will produce an IUH which is random itself. It is desirable to define the random properties of the IUH in a watershed in order to have a more realistic hydrologic application of this important function. Since in this case the IUH results from a series of differential equations where one or more of the uncertain parameters is treated in stochastic terms, then the statistical properties of the IUH are best described by the solution of the corresponding Stochastic Differential Equations (SDE's). This article attempts to present a methodology to derive the IUH in a small watershed by combining a classical conceptual model with the theory of SDE's. The procedure is illustrated with the application to the Middle Thames River, Ontario, Canada, and the model is verified by the comparison of the simulated statistical measures of the IUH with the corresponding observed ones with good agreement. 相似文献
105.
106.
We consider two-layer (Fe-FeS core+silicate mantle) and three-layer (Fe-FeS core+silicate mantle+crust) models of the Galilean satellite Io. Two parameters are known from observations for the equilibrium figure of the satellite, the mean density ρ0 and the Love number k2. Previously, the Radau-Darwin formula was used to determine the mean moment of inertia. Using formulas of the Figure Theory, we calculated the principal moments of inertia A, B, and C and the mean moment of inertia I for the two-and three-layer models of Io using ρ0 and k2 as the boundary conditions. We concluded that when modeling the internal structure of Io, it is better to use the observed value of k2 than the moment of inertia I derived from k2 using the Radau-Darwin formula. For the models under consideration, we calculated the Chandlerian wobble periods of Io. For the three-layer model, this period is approximately 460 days. 相似文献
107.
Zhenglu Jiang 《Celestial Mechanics and Dynamical Astronomy》2009,103(1):31-47
In this paper we analyse the relations between a previously described oblate Jaffe model for an ellipsoidal galaxy and the
observed quantities for NGC 2974, and obtain the length and velocity scales for a relevant elliptical galaxy model. We then
derive the finite total mass of the model from these scales, and finally find a good fit of an isotropic oblate Jaffe model
by using the Gauss-Hermite fit parameters and the observed ellipticity of the galaxy NGC 2974. The model is also used to predict
the total luminous mass of NGC 2974, assuming that the influence of dark matter in this galaxy on the image, ellipticity and
Gauss-Hermite fit parameters of this galaxy is negligible within the central region, of radius 0.5R
e. 相似文献
108.
Christoph Schneider Michael Schnirch Csar Acua Gino Casassa Rolf Kilian 《Global and Planetary Change》2007,59(1-4):87
The Gran Campo Nevado (GCN) forms an isolated ice cap on the Península Muñoz Gamero (PMG) located 200 km to the south of the Southern Patagonia Icefield (SPI). We present a glacier inventory of the GCN made up by 27 drainage basins (in total 199.5 km2) and other small cirque and valley glaciers of the southern part of PMG (in total 53 km2). The glacier inventory is based on a digital elevation model (DEM) and ortho-photos. Contour lines from maps, relief information derived from Landsat TM satellite imagery from 1986 and 2002 and stereoscopic data from aerial photos were combined in a knowledge-based scheme to obtain a DEM of the area. A digital ortho-photo map based on aerial photos from 1998 and several ortho-photos based on aerial photos from 1942 and 1984 could be produced from the initial DEM. A geographical information system (GIS) served to outline the extent of the present glaciation. All major glaciers of the GCN show a significant glacier retreat during the last 60 yr. Some of the outlet glaciers lost more than 20% of their total area during this period. Overall glacier retreat amounts to 2.8% of glacier length per decade and the glacier area loss is 2.4% per decade in the period from 1942 to 2002. We hypothesise that GCN glaciers may have reacted faster and more synchronously with the observed warming trend during recent decades when compared with the SPI. 相似文献
109.
针对海洋浮游生物实时探测中,三维形貌特征难以快速获取的问题,本文提出了一种海洋浮游生物三维形貌快速重建的方法。基于离轴菲涅尔数字全息显微系统,通过改进相位恢复方法预消除相位畸变,直接得到正确的相位信息,进而对浮游生物三维形貌重建。该方法不需要进行后期复杂的相位补偿计算,就可以对浮游生物三维形貌进行快速重建,有利于对动态、微小尺寸的浮游生物进行实时探测及分析。论文对青岛近海岸浮游生物桡足类和夜光虫进行了三维形貌重建,分辨率可达到3.5μm。实验结果为离轴菲涅尔数字全息显微系统用于海洋浮游生物原位、实时探测的可行性提供了依据。 相似文献
110.