PPP协议在GPRS无线网络中的嵌入式实现

介绍了PPP协商机制,给出了一个利用GPRS模块实现快速小数据量的无线数据通信的实例,此例中PPP协议采用了优化的协商流程以提高链路建立的速度,项目实施中还采用了串口监测的方式检测收发的数据值,这个重要的调试手段保证了系统的正确实现.     

G-凸空间中的广义KKM定理及极小极大定理

在G凸空间中证明了一个广义KKM定理,并给出了KyFan极小极大定理在G凸空间的推广.     

SPM电场加工纳米结构的评价方法

纳米结构形状特征及其相关参数的评价是扫描探针显微镜(SPM)加工面临的一个主要问题．文中对原子力显微镜(AFM)电场诱导硅氧化结构的部分形状特征进行了分析和讨论．借助传统评价方法，结合纳米加工实际，提出了几个评价参数，并用于SPM加工方法的评价中，其中加工线宽是一个关键参数．与加工线宽相关的参数还包括直线度、线平行度、垂直度、倾斜度、加工高度及纵横比等．通过对AFM加工生成的线结构进行评价，说明了该方法的可行性。     

基于EPIC技术的VLIW并行体系结构分析

介绍了微处理器体系结构的发展和当今微处理器设计中的新理念EPIC技术,并在此基础上分析了EPIC高性能微处理器Itanium的VLIW体系结构特征.     

关于丢番图方程Ax4+Bx2y2+Cy4=z2的解

证明了丢番图方程4x4-6x2y2 3y4=z2,(x,y)=1的全部正整数解为(x,y,z)=(x0／2,ab,(3a4 b4)／4), (Xn,2yn,2zn),认为仅有正整数解(x,y,z)=(1,1,1)是不妥的,它漏掉了(xn,2yn,2zn)及(x0／2,ab,(3a4 b4)／ 4);丢番图方程x4-6x2y2 12y4=z2,(x,y)=1的全部正整数解为(x,y,z)=(x0,ab,(3a4 b4)／2),(xn,yn, zn),认为仅有正整数解(xn,yn,zn),则漏掉了(x0,ab,(3a4 b4)／2)。     

滑坡三维有限元计算前后处理技术

应用高级语言与AutoCAD的接口,提出了滑坡三维有限元数值计算前处理和后处理的一般原理和方法.该技术使原始数据可视化,简单易懂,处理速度快、精度高、效果好,有效地解决了CAD图形与滑坡数据和计算结果数据图形化的矛盾.最后针对台子上滑坡进行了有限元三维网格的剖分和计算结果的图形显示.     

The trend and fluctuation of historical floods in the middle reaches of the Yangtze River

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Efficient volume preserving approach for skeleton-based implicit surfaces

This paper presents an efficient way to preserve the volume of implicit surfaces generated by skeletons. Recursive subdivision is used to efficiently calculate the volume. The criterion for subdivision is obtained by using the property of density functions and treating different types of skeletons respectively to get accurate minimum and maximum distances from a cube to a skeleton. Compared with the criterion generated by other ways such as using traditional Interval Analysis, Affine Arithmetic, or Lipschitz condition, our approach is much better both in speed and accuracy.     

Subwavelength-diameter silica wires for low-loss optical wave guiding

Silica waveguides with diameters larger than the wavelength of transmitted light are widely used in optical communications, sensors and other applications. Minimizing the width of the waveguides is desirable for photonic device applications, but the fabrication of low-loss optical waveguides with subwavelength diameters remains challenging because of strict requirements on surface roughness and diameter uniformity. Here we report the fabrication of subwavelength-diameter silica 'wires' for use as low-loss optical waveguides within the visible to near-infrared spectral range. We use a two-step drawing process to fabricate long free-standing silica wires with diameters down to 50 nm that show surface smoothness at the atomic level together with uniformity of diameter. Light can be launched into these wires by optical evanescent coupling. The wires allow single-mode operation, and have an optical loss of less than 0.1 dB mm(-1). We believe that these wires provide promising building blocks for future microphotonic devices with subwavelength-width structures.     

Cloning of theAspergillus awamori glucoamylase gene and expression inSaccharomyces cerevisiae

The A. awamori glucoamylase I gene was obtained by RT_PCR and inserted into the plasmid pAC1. We constructed an expression vector pAC1_GA, which was used to transform the yeast S. cerevisiae AS 2 1364 without auxotrophic marker. The transformant secreted glucoamylase into the medium efficiently and degraded starch. The glucoamylase activity of the culture filtrate is up to 8 4 U/mL.