CAD到ArcGIS数据转换问题

为将以AutoCAD格式存在的测量基础数据转换成GIS数据,从理论和实践两方面进行了研究。通过AO+VB进行开发设计数据转换程序。最终实现了AutoCAD环境下的大比例尺地形图数据向ArcGIS数据格式的无信息损失转换,降低了地理信息系统开发过程中数据采集的费用。     

Recent Advance in Non-Krylov Subspace Model Order Reduction of Interconnect Circuits

Model order reduction of interconnect circuits is an important technique to reduce the circuit complexity and improve the efficiency of post-layout verification process in the nanometer VLSI design. Existing works using the Krylov subspace method are very efficient, but the resulting models are less compact and lack global accuracy. Also, existing methods cannot handle interconnect circuits with large input and output ports. Recent advances in reduction techniques using non-Krylov subspace techniques such a...     

Rendering Grass Blowing in the Wind with Global Illumination

We have simulated a time varying wind field using the lattice Boltzmann model, and its effect on blades of grass with a simple mass-spring model. We present a global illumination model for multiple scattering of incident sun and sky illumination within the field of grass. We model the grass as a continuous distribution of infinitesimal colored scattering flakes and solve a system of differential equations for the radiance transport. We repeat this for a collection of grass bending directions and amounts, an...     

Emission-Based Scatter Correction in SPECT Imaging

Scatter correction in single photon emission computed tomography(SPECT) has been focused on either using multiple-window acquisition technique or the scatter modeling technique in iterative image reconstruction.We propose a technique that uses only the emission data for scatter correction in SPECT.We assume that the scatter data can be approximated by convolving the primary data with a scatter kernel followed by the normalization using the scatter-to-primary ratio(SPR).Since the emission data is the superpo...     

太阳能捕集器

太阳每天向地球倾泻成万倍于人类活动所需的能量,人们需要解决如何廉价地开发太阳能的问题。而自然界则不存在这个问题。“太阳能电池”就长在树上,绿叶的光合作用把太阳光转化为化学能,几乎为一切自然生态系统提供着能源。的确,人们可以从植物得到启迪：如何充分利用太阳光。差不多所有商品太阳能电池均系由无定形硅制成,问题在于硅的加工费用很大,而且这种电地转换效率不是很高,一般仅能转化13～16％的日光为电能。因此,使用不可再生的矿物燃料依然不失为比较切合实际的获取能量之途。但如果能廉价地大批最生产太阳能电池,经济性…