机器学习在电力信息物理系统网络安全中的应用

随着信息化程度的不断深入,传统电力系统逐渐发展成为典型的信息物理系统(CPS).开放的信息系统环境使得电力系统的安全运行面临着各种潜在网络攻击的威胁.近年来,机器学习方法迅猛发展,并已广泛应用于电力CPS网络安全领域.一方面,电力CPS中数据的爆炸式增长以及硬件运算能力的提升为机器学习的应用创造了良好条件;另一方面,相...     

一种高精度6位数控移相器研制

采用0.18μm GaAs衬底增强/耗尽型赝配高电子迁移率晶体管(E/D PHEMT)工艺研制了一款2～6.5 GHz高精度6位数控移相器.为了达到较小的插入损耗和较小的版图面积,采用桥T型高/低通滤波器拓扑结构对5.625°移相器单元进行设计.采用开关切换全通滤波拓扑结构对11.25°、22.5°、45°、90°、1...     

普通白光光源应用于ALA-PDT的实验研究

本文根据线光源高压汞灯的特点设计了一个用于光动力疗法的光反应室 ,它输出的光功率连续可调 ,波段选择简单灵活     

半经验风力机尾流模型的研究

以探究基于势流理论的半经验公式型的风力机尾流模型为目的,研究无粘近场尾流模型和两个远场尾流模型,即Jensen模型与改进Jensen模型。针对两种Jensen模型的不足提出物理模型的修正,得到改进的远场尾流模型,同时结合无粘近场尾流模型,建立两种全场尾流模型,并将其分别与风力机尾流流场实测数据和其他模型计算结果进行比较。结果表明,对两种Jensen模型所提出的修正符合实际流场的特性,所建立的两种全场尾流模型结构简单,流速计算结果与实测数据一致,优于常用的Jensen模型与改进Jensen模型。     

基于几何结构的零件切片轮廓特征点提取方法

零件功能的多样性决定了其几何结构的多样性。为深入理解产品的设计意图和获得零件的精确描述,在对零件的三维数据进行预处理时,需要针对不同结构的零件,运用不同的处理方法。本文对预处理中的特征点提取方法做了一些探索。首先,根据传统分类法将零件分为规则结构零件和非规则结构零件,具体描述了其特征点性质;然后,分别采用对应的特征点提取算法对其进行处理;最后,通过实例验证了该方法的可行性。     

基于形态学特征的细胞活性无损检测新方法研究

利用正常细胞、凋亡细胞和坏死细胞在形态学特征上的差异,使用圆度和半径比率2个物理量来表征细胞活性状态,并运用微分干涉相衬（DIC）显微镜获得待测细胞图像,结合图像识别软件,提出了一种基于细胞形态学特征的细胞活性无损检测方法,测得了与细胞活性相关的有关参数。该方法应用于氨乙酰丙酸（ALA）的光动力疗法（PDT）后白血病细胞的活性检测得出的结论与使用四甲基偶氮唑盐比色（MTT）法检测得出的结论基本一致。该方法也可检测出死亡细胞中凋亡、坏死的比例;在对细胞测试的过程不需对细胞进行染色等预处理,是一种无损检测方法。     

Kinetics and mechanistic aspects of As(III) oxidation by aqueous chlorine, chloramines, and ozone: relevance to drinking water treatment

Kinetics and mechanisms of As(III) oxidation by free available chlorine (FAC-the sum of HOCl and OCl-), ozone (O3), and monochloramine (NH2Cl) were investigated in buffered reagent solutions. Each reaction was found to be first order in oxidant and in As(III), with 1:1 stoichiometry. FAC-As(III) and O3-As(III) reactions were extremely fast, with pH-dependent, apparent second-order rate constants, k'app, of 2.6 (+/- 0.1) x 10(5) M(-1) s(-1) and 1.5 (+/- 0.1) x 10(6) M(-1) s(-1) at pH 7, whereas the NH2Cl-As(III) reaction was relatively slow (k'app = 4.3 (+/- 1.7) x 10(-1) M(-1) s(-1) at pH 7). Experiments conducted in real water samples spiked with 50 microg/L As(III) (6.7 x 10(-7) M) showed that a 0.1 mg/L Cl2 (1.4 x 10-6 M) dose as FAC was sufficient to achieve depletion of As(III) to <1 microg/L As(III) within 10 s of oxidant addition to waters containing negligible NH3 concentrations and DOC concentrations <2 mg-C/L. Even in a water containing 1 mg-N/L (7.1 x 10(-5) M) as NH3, >75% As(III) oxidation could be achieved within 10 s of dosing 1-2 mg/L Cl2 (1.4-2.8 x 10(-5) M) as FAC. As(III) residuals remaining in NH3-containing waters 10 s after dosing FAC were slowly oxidized (t1/2 > or = 4 h) in the presence of NH2Cl formed by the FAC-NH3 reaction. Ozonation was sufficient to yield >99% depletion of 50 microg/L As(III) within 10 s of dosing 0.25 mg/L O3 (5.2 x 10(-6) M) to real waters containing <2 mg-C/L of DOC, while 0.8 mg/L O3 (1.7 x 10(-5) M) was sufficientfor a water containing 5.4 mg-C/L of DOC. NH3 had negligible effect on the efficiency of As(III) oxidation by O3, due to the slow kinetics of the O3-NH3 reaction at circumneutral pH. Time-resolved measurements of As(III) loss during chlorination and ozonation of real waters were accurately modeled using the rate constants determined in this investigation.     

泵送商品混凝土裂缝产生原因分析和防裂措施

现在大部份工程采用泵送混凝土施工,但在施工实践中发现泵送混凝土普遍有裂缝的存在,在一定程度上影响结构的抗渗性和耐久性,应该引起足够的重视,并找出防止裂缝的措施。     

Quantal and non-quantal color matches: failure of Grassmann's laws at short wavelengths

Previous studies of color matching found that Grassmann's laws are not obeyed in the short-wavelength region when the method of maximum saturation matching is compared with Maxwell matching. The first experiment evaluated whether the discrepancy might be due to a discrimination matching range asymmetry around either the saturated or desaturated matches and concluded that asymmetry is not the dominant factor. The second and third experiments were designed to evaluate postreceptoral mechanisms. The results pointed to the conjunction of three factors as being the principal cause of the failures of Grassmann's laws: the spatial inhomogeneity of the macular pigment distribution, the spatially dissimilar L/M-and S-cone distributions, and a change in the weightings of postreceptoral mechanisms mediating S-cone chromatic and L/M-cone luminance discriminations.     

高性能桶形整数加法器的设计

为了提高加法器的运算速度,提出了一种新型并行整数加法算法——桶形整数加法算法。该加法器以半加器为基础,将并行与迭代反馈思想相结合,根据每轮迭代后进位链的值判断是否已经累加结束,可以在保持低功耗的同时提高运算速度。仿真结果表明,该桶形整数加法器在面积少量增加的基础上,速度提高明显。