A Review on Machine Learning Approaches for Network Malicious Behavior Detection in Emerging Technologies

Network anomaly detection systems (NADSs) play a significant role in every network defense system as they detect and prevent malicious activities. Therefore, this paper offers an exhaustive overview of different aspects of anomaly-based network intrusion detection systems (NIDSs). Additionally, contemporary malicious activities in network systems and the important properties of intrusion detection systems are discussed as well. The present survey explains important phases of NADSs, such as pre-processing, feature extraction and malicious behavior detection and recognition. In addition, with regard to the detection and recognition phase, recent machine learning approaches including supervised, unsupervised, new deep and ensemble learning techniques have been comprehensively discussed; moreover, some details about currently available benchmark datasets for training and evaluating machine learning techniques are provided by the researchers. In the end, potential challenges together with some future directions for machine learning-based NADSs are specified.     

抽样调查的设计与分析(Ⅱ)

本文讨论抽样调查实践中有关设计和数据分析中的若干问题．第二部分主要涉及数据处理与统计分析问题．     

一种有限元并行计算前处理方法

本文研究一种有限元并行计算前处理方法,只需将各子结构的超单元信息发送给各处理机,就可并行自动剖分各子结构和并行优化各子结构单元编号,以达到极小最大波宽和波宽的均主根,算例表明,该方法可大大减少有限元并行计算前处理时间。     

一种改进的光滑粒子流体动力学前处理方法

为了便于对任意边界形状的计算域快速地布置均匀粒子,提出了一种改进的光滑粒子流体动力学前处理方法.该方法是在2012年Colagrossi等提出的算法基础上进行改进后得到的.Colagrossi等提出的算法能够计算一些简单外形分布比较均匀的粒子.然而当光滑长度与初始粒子间距的比值较大时该方法在计算过程中会出现较强的数值震荡问题,收敛速度慢;而且在计算过程中可能会遭遇流体粒子穿透固体壁面的问题.本文通过引入未知因素修正的平滑粒子动力学模型来提高计算稳定性,并通过对边界附近的流体粒子施加边界力来避免流体粒子穿透固体壁面.算例验证结果表明,利用改进后的光滑粒子流体动力学前处理方法能够快速地对各种边界形状的计算域分布均匀粒子,并且避免了流体粒子穿透固体壁面的问题.     

全氟辛烷磺酸水样的前处理技术及固相微萃取剂的研究进展

全氟辛烷磺酸及其盐(PFOS)广泛应用于纺织品、皮革、家具等上千种工业和日用生活用品的生产中,由于具有多脏器毒性,被列为继多氯联苯、有机氯农药和二噁英之后的又一种新型持久性有机污染物.因此,PFOS的准确监测对环境PFOS污染的预警预报具有重要的意义.PFOS在样品中含量低,因此样品前处理技术是准确分析的关键.本文对目...     

基于FPGA的实时中值滤波器设计

在图像生成和采集过程中引入的各种噪声会使图像质量变差。为了实现对图像的实时预处理，首先介绍中值滤波器的基本原理和算法，然后在现场可编程门阵列（FPGA）上根据中值滤波的根基数算法，采用流水技术设计一种快速实时中值滤波器，给出按行输出的图像处理过程中存储前2行图像数据的方法。仿真结果表明：该中值滤波器可实时完成CCD输出图像的预处理，达到了抑制噪声及保持图像细节的目的。     

风与柔性结构流固耦合作用的预处理方法研究

针对强耦合方法求解风与柔性结构流固耦合作用时,大量计算资源都耗费在对强耦合方程求解中这一弊端,本文研究了强耦合方程的预处理求解方法。在风与柔性结构流固耦合作用的强耦合整体方程的基础上,将时空离散和线性化后的类似结构方程看成是鞍点问题,首先推导得到了类似结构方程的预处理矩阵;再基于此推导出了强耦合整体方程的预处理矩阵。首先采用预处理方法对经典二维流固耦合问题进行了计算,验证了提出的预处理矩阵的正确性;然后对风与三维膜结构的流固耦合作用进行了分析,评估了所提出预处理方法的相关计算参数。计算结果表明,所提出的预处理方法可使强耦合整体方程的求解在计算精度和计算效率上都得到较大提升,证明本文提出的预处理方法适用于风与柔性结构的流固耦合分析。     

Collection and preparation of molecular databases for virtual screening

Drug discovery and development research is undergoing a paradigm shift from a linear and sequential nature of the various steps involved in the drug discovery process of the past to the more parallel approach of the present, due to a lack of sufficient correlation between activities estimated by in vitro and in vivo assays. This is attributed to the non-drug-likeness of the lead molecules, which has often been detected at advanced drug development stages. Thus a striking aspect of this paradigm shift has been early/parallel in silico prioritization of drug-like molecular databases (also database pre-processing), in addition to prioritizing compounds with high affinity and selectivity for a protein target. In view of this, a drug-like database useful for virtual screening has been created by prioritizing molecules from 36 catalog suppliers, using our recently derived binary QSAR based drug-likeness model as a filter. The performance of this model was assessed by a comparative evaluation with respect to commonly used filters implemented by the ZINC database. Since the model was derived considering all the limitations that have plagued the existing rules and models, it performs better than the existing filters and thus the molecules prioritized by this filter represent a better subset of drug-like compounds. The application of this model on exhaustive subsets of 4,972,123 molecules, many of which have passed the ZINC database filters for drug-likeness, led to a further prioritization of 2,920,551 drug-like molecules. This database may have a great potential for in silico virtual screening for discovering molecules, which may survive the later stages of the drug development research.     

化学计量学在激光诱导击穿光谱分析中的研究进展

激光诱导击穿光谱作为一种新兴的元素分析技术,具有实时在线、非接触、多元素同时检测等优点,是光谱分析领域内的一种前沿性分析手段.然而,如何从复杂大量的激光诱导击穿光谱数据提取有用信息,提高其定性、定量分析准确度是激光诱导击穿光谱技术目前面临的难题.化学计量学作为多学科交叉的化学分支学科,在数据处理、信号解析和模式识别等方面具有优势,能够解决传统化学研究方法难以解决的一些复杂问题.本文从光谱数据预处理、定性和定量分析三方面综述了近年来化学计量学方法在激光诱导击穿光谱中的研究进展.     

原子吸收光谱法测定金银样品前处理的讨论

讨论了在岩石、矿物及化学探矿样品中金、银的原子吸收光谱分析时,样品前处理应关注的一些问题实践经验表明要注意样品的加工过程和金银的赋存状态,以保证样品有足够的代表性;针对不同矿种类型,选择合适的样品前处理方法,尽量避免样品在处理过程中的挥发损失、包夹、共沉淀吸附等情况的发生;对单矿物金、银的连续测定,建议采用多次湿法酸处理来保证样品的分解,并根据其含量进行必要的分离富集或稀释,以满足测定的要求．