电子商务的研究

首先简要介绍了电子商务的技术特点,说明了电子商务已成为全球商务发展的趋势。然后提出了企业发展电子商务的几点战略,并进行了详细的分析。最后,研究了电子商务的安全需求手段。     

Numerical simulation of structural response and damage to simultaneous ground shock and airblast loads

Current practice in analysis and design of structures to withhold surface explosions considers only airblast forces on structures. A surface explosion, in fact, generates both ground shock and airblast pressure on a nearby structure. In this paper, the influences of simultaneous ground shock and airblast forces on structural responses are investigated. Blast-induced surface ground motions and airblast pressures estimated in a previous study are employed as input in the analysis. A previously developed three-dimensional homogenized material model for a masonry wall including the equivalent elastic properties, strength envelope and damage threshold is used to model masonry wall. Another material damage model developed for reinforced concrete structures is used for modelling RC behavior due to explosive loads. These material models are programmed and linked to an available computer program LS-DYNA3D through its user subroutine capability. A one-story masonry infilled RC frame is used as an example in the study. Dynamic response and damage of the example structure to simultaneous ground shock and airblast forces, or separately to ground shock only or airblast forces only are calculated. It is found that in general, airblast load governs structural response and damage when the scaled distance is small. However, under certain conditions, structural damage will be critically underestimated if ground shock is neglected. When the scale distance increases, the relative importance of the ground shock on structure response increases, and ground shock will dominate the surface explosion effects on structures at large scaled distance. At large scaled distance, the ground shock and airblast force effects on structures decoupled and structure response and damage to ground shock and airblast force can be analyzed separately.     

TDA5005全站仪用于11m天线测量

对高精度全站仪用于大中型天线安装测量进行了有益的尝试。坐标测量采用TDA5005全站仪配合测距反射片，导出了测距入射角计算公式，提出了一种反射片加常数测定方法。在数据处理方面，讨论了标志厚度对面型的影响。计算发现，对于圆抛物面天线而言，曲面自由拟合法与CAD面型拟合法是相当的。天线机械调整效果得到了电测结果的验证。     

Composite Distance Transformation for Indexing and k-Nearest-Neighbor Searching in High-Dimensional Spaces

Due to the famous dimensionality curse problem, search in a high-dimensional space is considered as a ＂hard＂ problem. In this paper, a novel composite distance transformation method, which is called CDT, is proposed to support a fast κ-nearest-neighbor （κ-NN） search in high-dimensional spaces. In CDT, all （n） data points are first grouped into some clusters by a κ-Means clustering algorithm. Then a composite distance key of each data point is computed. Finally, these index keys of such n data points are inserted by a partition-based B^＋-tree. Thus, given a query point, its κ-NN search in high-dimensional spaces is transformed into the search in the single dimensional space with the aid of CDT index. Extensive performance studies are conducted to evaluate the effectiveness and efficiency of the proposed scheme. Our results show that this method outperforms the state-of-the-art high-dimensional search techniques, such as the X-Tree, VA-file, iDistance and NB-Tree.     

工程结构中曲面与曲线最短距离的计算方法

目的解决工程结构中曲面与曲线之间最短距离问题，为工程结构应用提供参考．方法建立以曲面、曲线上未知点坐标设计变量，以曲面和曲线方程为约束条件，以曲线和曲面距离为目标函数的约束优化方法来精确地确定曲面和曲线之间最短距离，同时确定获得最短距离对应的坐标点．结果进行波动路面和地下电缆之间最短距离的仿真分析并获得相应结果．结论研究方法为解决实际工程问题提供有效计算方法．     

关于生命能量系统稳定性的研究

生命能量系统以失去稳定作为自己发展的重要条件。失稳破坏了能量系统原有的状态,在适当的条件下,由涨落导致新有序结构的产生,而维护相对的稳定有在某些情况下起协调若干组同步生长的作用。与耗散结构理论不同的是,在生命能量系统中,涨落的重要贡献是在系统失稳之后,只有涨落才能在适当条件下帮助系统越过熵垒,形成新的能量有序结构。然而在什么条件下系统失去稳定,在什么条件下涨落导致新结构的产生,对此作了详细的分析,以充足的理论依据阐明了过程的因果关系。     

水下高速航行体的航向角和距离估计方法

为了提高反鱼雷鱼雷拦截成功率,实现其对水下高速航行体的航向角和距离估计尤显重要。该文立足于此,探讨一种对水下高速航行体的航向角和距离的估计方法。该方法可同时使用主被动声纳,对来袭水下航行体进行探测。主被动检测时采用初始轴向对准,检测装置直航,应用双周期检测法,可在极短时间内对水下航行体的航向角、距离和速度进行精确估计。文中给出了估计过程的运算公式,指出检测装置对目标方位的检测精度要求均方差不大于0.1°。对不同速度、距离时水下航行体的航向角和距离估计进行了仿真试验,结果表明,在航行体航向角小于35°,距离大于700m时,可得到理想的估计值。该方法对探索反鱼雷鱼雷检测装置的设计和对水下航行体参量的检测,探讨其拦截方法,具有一定的参考价值。     

基于RF技术的引信定高系统探索

针对某些对于高度有特定需求的弹药引信,提出一种快速精确测定高度的技术措施。利用无线数字通信与GPS定位相配合的方法,通过信标子弹与功能子弹相互之间的无线数字通信,实现了弹药引信最佳起爆高度的控制。接着提出了弹药引信定高系统的组成框架和定高算法,最后对系统中误差问题进行了分析。     

北斗系统在巡航导弹中的应用研究

针对我国自主导航现实情况。论证了北斗双星系统应用于巡航导弹的可行性。在分析北斗系统误差的基础上，提出了巡航导弹中制导基于北斗双星系统的距离判别定位的新方法，并探讨了其工作方式和关键问题。     

基于光源扫描的三角法位移测量方法

对激光三角法测量位移的几种光路布局方案及其特点进行了比较,在此基础上,提出了一种新的基于光源扫描的三角法激光位移测量方法,阐述了激光三角法测量原理,并设计了相应的测量系统,分析了影响系统精度的因素。理论分析可知,该系统的测量分辨力可达到1.5×10-5m。实验结果表明:此系统有很强的实用性,测量范围为0mm~10m,适用于工业生产。