基于统计方法的数据挖掘算法研究

在统计方法的基础上提出了一种根据数据集合本身的统计特性数据挖掘算法．该算法利用数据本身的统计特性对数据仓库中的数据进行分析，在给定重要性比例程度的前提下，经过系列的统计运算，得到简化的数据仓库集，并根据分析得到了数据挖掘算法的流程图．提出了比例大小关系函数，反映了数据自身的统计特性，分析表明：这种算法极大的提高了数据的有效水平。     

基于小闪烁室测氡仪快速定值方法研究

高探测效率的闪烁室测氡是氡测量的主要方法，但其取样结束后需静置3 h才开始测量.为实现闪烁室快速测氡的需要，在Rn-222、Po-218和Bi-214的探测效率相同的条件下，依据氡及其子体的衰变关系，本文建立了一种闪烁室测氡仪快速定值的方法.此法基于积分计数法，利用测量周期为60 min时的刻度因子K₀,计算测量周期为30 min和15 min的理论刻度因子.本文选取对氡及其子体探测效率近似100%的54 mL小闪烁室，在氡浓度为20 Bq/mL的条件下开展快速定值实验.实验结果表明，本文测量的实验值与理论值误差在5%以内，能够实现闪烁室快速测氡.     

A self-cited pixel summation based image encryption algorithm

In this paper, a novel image encryption algorithm is presented based on self-cited pixel summation. With the classical mechanism of permutation plus diffusion, a pixel summation of the plain image is employed to make a gravity influence on the pixel positions in the permutation stage. Then, for each pixel in every step of the diffusion stage, the pixel summation calculated from the permuted image is updated. The values from a chaotic sequence generated by an intertwining logistic map are selected by this summation. Consequently, the keystreams generated in both stages are dependent on both the plain image and the permuted image. Because of the sensitivity of the chaotic map to its initial conditions and the plain-image-dependent keystreams, any tiny change in the secret key or the plain image would lead to a significantly different cipher image. As a result, the proposed encryption algorithm is immune to the known plaintext attack (KPA) and the chosen plaintext attack (CPA). Moreover, experimental simulations and security analyses show that the proposed permutation-diffusion encryption scheme can achieve a satisfactory level of security.