对一种白盒SM4方案的差分计算分析

传统密码算法的安全性建立在黑盒攻击模型下. 在这种攻击模型下, 攻击者只能获取密码算法的输入输出, 而无法得知密码算法运行时的内部细节. 近年来白盒攻击模型的概念被提出. 在白盒攻击模型下, 攻击者既可以获取密码算法的输入输出, 也可以直接观测或更改密码算法运行时的内部数据. 为保证已有密码算法在白盒攻击环境下的安全性, 在不改变其功能的基础上通过白盒密码技术对其进行重新设计被称为已有密码算法的白盒实现. 研究白盒实现方案的设计与分析对于解决数字版权管理问题具有重要意义. 近年来, 出现了一类针对白盒实现方案的旁信道分析方法. 这类分析手段只需要知道很少白盒实现方案的内部细节, 却可以提取到密钥, 因此是一类对现有白盒实现方案具有实际威胁的分析手段. 对现有白盒实现方案进行此类分析对于确保方案安全性具有重要现实意义. 此类分析方法中的典型代表是基于差分功耗分析原理的差分计算分析. 基于差分计算分析, 对白-武白盒SM4方案进行了安全性分析. 基于对GF(2)上n阶均匀随机可逆矩阵统计特征的研究结果, 提出了一种改进型差分计算分析(IDCA), 可以在分析成功率几乎不变的前提下显著提升分析效率. 结果表明, 白-武白盒SM4方案在面对差分计算分析时不能保证安全性, 必须对其进行进一步改进使之满足实际应用场景下的安全性需求.     

基于EMD方法的X波段双偏振雷达衰减订正

针对X波段双偏振雷达信号在降雨路径中的衰减现象,本文提出经验模式分解（Empirical Mode Decomposition,EMD）方法进行X波段双偏振雷达衰减订正,首先对总差分传播相移进行EMD分解得到有限个基本模式分量（Intrinsic Mode Function,IMF）,并基于皮尔逊相关系数准则将IMF分为噪声IMF和信号IMF两类,然后对信号IMF进行有效重构得到差分传播相移,再将差分传播相移通过最小二乘法拟合得到差分传播相移率,最后对求得的差分传播相移与差分传播相移率采用自适应约束方法进行反射率衰减订正。利用EMD方法和其他方法进行对比分析,其结果表明,EMD方法能够有效地消除X波段双偏振雷达回波数据中后向散射的影响,在保留真实的气象信息的同时,有效地抑制差分传播相移的显著波动,进而衰减订正效果更好。     

Monitoring the Coefficient of Variation Using the Side Sensitive Group Runs Chart

Many quality characteristics have means and standard deviations that are not independent. Instead, the standard deviations of these quality characteristics are proportional to their corresponding means. Thus, monitoring the coefficient of variation (CV), for these quality characteristics, using a control chart has gained remarkable attention in recent years. This paper presents a side sensitive group runs chart for the CV (called the SSGR CV chart). The implementation and optimization procedures of the proposed chart are presented. Two optimization procedures are developed, i.e. (i) by minimizing the average run length (ARL) when the shift size is deterministic and (ii) by minimizing the expected average run length (EARL) when the shift size is unknown. An application of the SSGR CV chart using a real dataset is also demonstrated. Additionally, the SSGR CV chart is compared with the Shewhart CV, runs rules CV, synthetic CV and exponentially weighted moving average CV charts by means of ARLs and standard deviation of the run lengths. The performance comparison is also conducted using EARLs when the shift size is unknown. In general, the SSGR CV chart surpasses the other charts under comparison, for most upward and downward CV shifts. Copyright © 2015 John Wiley & Sons, Ltd.     

车型意象认知与侧轮廓造型特征关联研究

目的基于感性工学(KE)原理与方法,以各车型侧轮廓为对象,研究意象认知与车型造型要素的关联性,比较并分析在意象差异下所对应各车型侧轮廓的关键造型特征。方法选取目前市场的15款典型车型为研究样本,收集并筛选获取代表性感性意象词汇,结合语义差分法(SD法)与形态分析法,利用贝塞尔曲线对车身侧轮廓进行了简化并提取其造型特征线,在构建车身侧轮廓评价参考模型基础上,对样本侧轮廓进行直接与间接的量化分析。结论综合语义差分法(SD法)与形态对比分析法,提取影响车型意象定位的关键造型特征,获取用户针对不同车型在侧轮廓特征上的识别程度等级,构建车型侧轮廓特征—感性意象的关联模型,辅助汽车车型造型设计与研究,提高车型造型与用户感性需求间的匹配度。     

基于喉部出口流场的核电机组凝汽器壳侧蒸汽流场数值研究

对凝汽器喉部流动进行数值模拟并提取数据,将喉部出口流场数据作为入口边界条件,对凝汽器壳侧蒸汽流场进行了更准确的数值模拟和研究。结果表明,入口蒸汽均匀分布情况下,蒸汽在4个管束模块区域均呈现向心式的流动趋势;蒸汽入口不均匀分布情况下,蒸汽在两侧蒸汽通道内和中间蒸汽通道内有下冲流动,形成了对管束模块的包绕流动。因此,对于开展与凝汽器壳侧蒸汽流场分布相关性能的研究,建议基于喉部出口流场对凝汽器壳侧蒸汽流动进行数值模拟。     

海底沉积物岩芯横向声学测量系统的标定

水平轴向测量技术相对成熟,但较难获取海底沉积物的无扰动分层声学特性,采用横向测量技术可以解决这一问题。文章研究了海底沉积物岩芯横向测量技术,将水作为海底沉积物测量的参考标准,进行测量系统的标定。提出了等效换能器的概念,将样品以外的声传播介质整合成等效换能器的一部分,标定测量等效换能器声延时和声传播初始能量。以水为标准介质,分别采用33、80、100 kHz三种频率的声学换能器,以及75、90、110 mm三种管径的聚氯乙烯(Polyvinyl Chloride,PVC),测量所得的水中的声速与标准计算水中的声速具有一致性,其中以采用80 kHz频率声学换能器和90 mm管径PVC管测量时的声速误差最小,选用此状态进行标定,得出当隔水耦合测量法换能器相对距离为142.02 mm时,标定的等效换能器声延时为45.88±0.08 μs,等效换能器声传播初始能量(以接收换能器的接收电压表示)为0.86±0.03 V。应用标定的等效换能器声延时和声传播初始能量测量海底沉积物。计算得到声速和声衰减系数符合黏土质粉砂的声学特性。     

基于光声差分衰减频谱的骨质评估仿真研究

光声层析成像术(Photoacoustic Tomography,PAT)在骨组织微结构的量化评估方面具有潜力,但在传统PAT工作模式下,松质骨的固液两相多孔结构导致骨小梁等分布式光吸收成分激发的光声信号混叠,增加了定量分析骨微结构特性的难度和复杂度。针对这一问题,文章将PAT系统改进为偏心激励-差分检测模式,获取差分衰减频谱(Differential Attenuation Spectrum,DAS);并通过数值仿真计算和验证了松质骨孔隙率与光声差分衰减频谱特征参数的相关性。研究结果表明：提取的光声差分衰减频谱特征参数与骨头孔隙率呈强线性相关,基于光声差分衰减频谱的分析方法可有效实现骨质定量评估和诊断。     

光纤到户（FTTH）的ODN工程设计及测试

文章针对PON系统的基本保护要求,提出了光分路器（OBD）设计原则;采用最坏值法对PON系统最远的用户终端,进行ODN光通道衰减核算;同时,对ODN光缆线路进行分段衰减测试和全程衰减测试,测试结果满足FTTH系统工程规范。根据现场试验的研究和测试结果,规范光纤到户（FTTH）工程系统的规划、设计、施工、监理及竣工验收等工作。     

电力负荷控制技术在需求侧管理中的应用

对电力负荷控制系统在需求侧管理中的应用进行论述。     

An approach to quantify depth-resolved marine photochemical fluxes using remote sensing: Application to carbon monoxide (CO) photoproduction

This paper presents a model to calculate depth-resolved marine photochemical fluxes from remotely sensed ocean color and modeled solar irradiance. The basic approach uses three components: 1) below-sea-surface spectral downward scalar irradiance calculated from a radiative transfer model (STAR) and corrected for clouds using TOMS UV reflectivities; 2) surface-ocean spectral diffuse attenuation coefficients and absorption coefficients for chromophoric dissolved organic matter retrieved from SeaWiFS ocean color using the SeaUV/SeaUVc algorithms; and (3) spectral apparent quantum yield for the photochemical reaction considered. The output of the model is a photochemical rate profile, Ψ_PR(z), where z represents depth.We implemented the model for carbon monoxide (CO) photochemistry using an average apparent quantum yield spectrum and generated a monthly climatology of depth-resolved CO photoproduction rates in the global ocean. The climatology was used to compute global budgets and investigate the spatial and seasonal variabilities of CO photoproduction in the ocean. The model predicts a global CO photoproduction rate of about 41 TgC yr^− 1, in good agreement with other recent published estimates ranging from 30 to 84 TgC yr^− 1. The fate of photochemically derived CO and its role in global biogeochemical cycles remains uncertain however, with biological consumption and sea-air exchange competing for its removal in the surface ocean. Knowledge of the vertical distribution of CO photoproduction is critical in the quantification of the relative magnitudes of these sink mechanisms. The depth-resolution capabilities of this model, together with US Naval Research Laboratory climatology for mixed layer depths allowed further estimation that > 95% of the total water-column CO photoproduction occurs within the mixed layer on a global, yearly basis. Despite this compelling figure, the model also suggests significant spatio-temporal variability in the vertical distribution of CO photoproduction in the subtropical gyres, where up to 40% of water-column CO can be produced below the mixed layer during summertime.While the approach can be applied to other photochemical fluxes (e.g. DIC formation or DMS removal), accurate quantification of such processes with remote sensing will be limited until the mechanisms regulating observed oceanic variability in the apparent quantum yields are better understood. Minor modification to this model can also make it applicable for the determination of the effects of UV and visible solar radiation on sensitive biological systems.