分布式数据挖掘的隐私保护问题

隐私保护是数据挖掘中一个重要的研究方向,如何在不违反隐私规定的情况下,利用数据挖掘工具发现有意义的知识是一个热点问题。本文介绍了分布式数据挖掘中隐私保护的现状,着重介绍分布式数据挖掘中隐私保护问题和技术。     

浅吃水肥大双尾船型水动力系数的一种计算方法

根据高梨、伊三夫提出的浅吃水肥大型船横摇实用计算方法,采用流域分割理论,推出一种适合双尾浅吃水肥大型船的水动力系数实用计算方法。本文方法弥补了多极展开法、普通切片法之不足,并与Frank法比较,输入数据的准备工作简单,易于上机实现,所用的C.P.U时间短,而精度良好,便于对船舶耐波性的初步设计。是一种较为实用的计算方法。本文还对高梨、伊三夫的横摇实用计算方法,进行摄动分析,导出该方法的物形影响高阶项,在理论上给予说明。     

Controlled linear perturbation

We present an algorithmic solution to the robustness problem in computational geometry, called controlled linear perturbation, and demonstrate it on Minkowski sums of polyhedra. The robustness problem is how to implement real RAM algorithms accurately and efficiently using computer arithmetic. Approximate computation in floating point arithmetic is efficient but can assign incorrect signs to geometric predicates, which can cause combinatorial errors in the algorithm output. We make approximate computation accurate by performing small input perturbations, which we compute using differential calculus. This strategy supports fast, accurate Minkowski sum computation. The only prior robust implementation uses a less efficient algorithm, requires exact algebraic computation, and is far slower based on our extensive testing.     

Perturbation analysis and condition numbers of symmetric algebraic Riccati equations

This paper is devoted to the perturbation analysis of symmetric algebraic Riccati equations. Based on our perturbation analysis, the upper bounds for the normwise, mixed and componentwise condition numbers are presented. The results are demonstrated by our preliminary numerical experiments.     

铁氧体双模器件的广义理论

铁氧体双模器件包括双模移相器,圆极化移相器,旋转场移相器.双模变极化器等等.其种类繁多,每种器件由若干基本双模段级联而成.每个基本单元上,外加磁场形式各不相同,有四磁极磁化场,纵向磁化场,双磁极磁化场及其混合磁化场.本文拟用统一的理论对其进行处理及分析并引入具体实例使用CAD技术进行计算,从而进一步确认理论的正确性.     

Development of bilinear power system representations for small signal stability analysis

In this paper, a new analysis technique for predicting and characterizing nonlinear behavior of stressed power networks is proposed. Making use of an analytical approximation of the system nonlinear model via the use of a truncated Carleman linearization technique, a bilinear state-space model of the power system is developed in which the second and higher order nonlinear terms are explicitly incorporated in the series expansion representation of the system model.     

Sliding mode controller with sliding perturbation observer based on gain optimization using genetic algorithm

The Stewart platform manipulator is a closed-kinematics chain robot manipulator that is capable of providing high structural rigidity and positional accuracy. However, this is a complex and nonlinear system, so the control performance of the system is not so good. In this paper, a new robust motion control algorithm is proposed. The algorithm uses partial state feedback for a class of nonlinear systems with modeling uncertainties and external disturbances. The major contribution is the design of a robust observer for the state and the perturbation of the Stewart platform, which is combined with a variable structure controller (VSC). The combination of controller and observer provides the robust routine called sliding mode control with sliding perturbation observer (SMCSPO). The optimal gains of SMCSPO, which is determined by nominal eigenvalues, are easily obtained by genetic algorithm. The proposed fitness function that evaluates the gain optimization is to put sliding function. The control performance of the proposed algorithm is evaluated by the simulation and experiment to apply to the Stewart platform. The results showed high accuracy and good performance.     

基于Blinn算法的三维瓜果造型

Blinn算法是一种典型的几何纹理算法,可模拟物体表面凹凸不平的效果.利用该算法的思想,对物体的表面进行大幅度的扰动,使物体变形得到一种新的物体模型,而不单单是在表面产生凹凸效果.从瓜果的静态和动态生长造型两方面来说明该算法的优越性.     

基于GA-BP神经网络的BDS轨道误差模型研究

在对导航卫星轨道误差数据进行研究时发现,卫星广播星历轨道误差客观存在着一些不确定性的规律现象,针对这一无法用现有确定性模型表示的误差信息,建立了基于遗传算法优化BP神经网络的轨道误差预测模型。利用遗传算法来全局寻优BP神经网络的初始权值与阈值,同时根据广播星历解算出的卫星位置和速度,结合参考时刻及摄动改正项对神经网络进行训练和测试。试验结果表明,上述模型能较好的预测轨道误差,应用该模型进行卫星轨道解算时能有效提高轨道精度,降低轨道误差。     

谐振腔体外微扰及应用研究

本文分析圆柱TE011模端盖对称隙缝特性。在隙缝辐射较小的条件下,提出适于损耗小,厚度薄(1mm左右)的片状材料腔外微扰的近似计算方法,测得聚四氟乙烯、聚氯乙烯、纯陶瓷片等复介电常数与准确值相当吻合的结果。测得相同厚度的片状半导体材料电阻率(≥20Ω·cm),与1／QL有线性关系,与提出的近似方法所预期结果一致。理论分析和实验表明,应用圆柱TEo11模端盖对称隙缝可实现无接触、高精度、多功能测量片状材料的参数,且预期可用于二维测量。