AES-192的相关密钥飞去来器攻击和矩形攻击

相关密钥攻击是对AES十分有效的分析方法之一.在2022年亚密会上,Derbez等利用概率为2−108的10轮相关密钥飞去来器区分器给出了目前最好的AES-192的全轮攻击.本文改进了全轮AES-192的相关密钥飞去来器和矩形攻击.基于Wang等的9轮相关密钥飞去来器区分器的截断差分,本文利用飞去来器分布表(BDT)技术给出目前概率最高的10轮相关密钥飞去来器区分器,概率为2−105.92.基于该区分器,改进了全轮AES-192的相关密钥飞去来器攻击,时间、数据和存储复杂度分别为2^(121.92)、2^(121.92)和2^(90.92),与之前的结果相比时间复杂度改进了22.08.进一步,给出了全轮AES-192的相关密钥矩形攻击,时间、数据和存储复杂度分别为2^(127.9)、2^(119.5)和2^(131.5),这也是目前在选择明文模式下对全轮AES-192最好的攻击结果.

基于AES的车联网通信加密算法

随着V2X技术发展得越来越快,车辆与其他设备的通信量以及信息重要度都在急速增长,车载信息遭到攻击从而被截取或者发生泄漏的风险也相应地大大增加,因此信息交互安全性成为了一个不可避免的研究课题。本文针对车联网传输数据量大、数据加解密操作频繁等问题,通过分析经典加密算法,进而改进传统AES加密算法,使用RC4加密算法生成伪随机密钥代替AES加密算法的密钥生成模块,优化加密时间的同时提升安全性能,并开展实验验证了其加密效率以及安全性。

基于AES与ECC混合算法的计算机网络通信数据安全加密方法

为了提高通信数据在计算机网络中的安全性,提出一种基于AES与ECC混合算法的计算机网络通信数据安全加密方法。通过时域分析,得到通信数据在计算机网络边缘的频率分布情况,根据通信数据中冗余信息的密度,离散化处理通信数据内的噪声,提取出通信数据的特征向量。根据通信数据的明文空间进行加密处理,计算出待加密通信数据的密文值,将计算机网络通信数据的加密过程约束成加密函数的计算,设定通信数据安全加密的约束条件,采用AES算法加密通信数据的明文,利用ECC算法加密AES密钥,将AES与ECC结合,生成通信数据的密钥密文,实现通信数据的安全加密。实验结果表明,所提方法能够保证通信数据在计算机网络中的安全,可以将通信数据加密后的受攻击指数控制在0.1以内,提高通信数据的加密效果。

基于LSTM-AE的民机空调热交换器性能异常检测方法

空调热交换器性能异常检测技术是快速判断民机空调系统运行状态并合理安排维修任务的关键,传统的异常检测方法难以有效处理高维时序数据,无法实现系统早期故障预警。为此,本文提出了一种基于长短期记忆网络(LSTM,long-short term memory)与自编码器(AE,autoencoder)模型的无监督异常检测方法,用以识别民机空调系统异常运行状态。首先,基于民机空调系统原始传感器参数构建表征空调热交换器性能的特征监测参数;其次,构建LSTM-AE模型进行数据特征重构并计算重构误差;最后,使用孤立森林(iForest, isolation forest)进行无监督异常监测。将本文构建的无监督异常检测方法与传统方法对比,并建立模型评估指标,验证结果表明,所构建的模型方法可以对民机空调热交换器性能异常状态进行有效检测。

基于混沌序列和AES算法的数据库外层数据传输同步加密方法

为保障数据库外层数据的安全传输,提出一种基于混沌序列和AES算法的数据库外层数据传输同步加密方法。该方法结合AES算法的加密安全性和混沌序列的加密速度优势,通过加密代理服务器和应用服务器对数据库外层数据进行处理,利用混沌序列logistic映射参数初始化、混沌序列二进制量化、AES动态加密和尾端处理实现数据库外层数据传输同步加密。实验结果表明,该方法能够成功地对文本和图像数据进行加密和隐藏,同时提高加密效率,并兼顾了数据的安全性和传输效率。

基于AES算法的计算机数据库加密系统设计与实现

随着信息技术的迅猛发展,中等职业(中职)教育面临着教学资源更新和个性化教学需求的双重挑战。知识图谱是一种通过链接和整合广泛信息资源来创建、利用和分享知识的技术,能够在复杂的数据中寻找规律,为用户提供准确的信息推荐服务。研究通过分析数据库加密的常用方式和数据库透明加密(TDE)原理,设计了一套基于知识图谱的中职线上教学资源推荐系统的体系架构。系统采用高级加密标准(AES)算法加密设计保证数据安全,整合数据库提升系统效能,并详细说明了开发过程的实现。通过实验结果及分析,证明了系统的有效性和实用性,为中职教育提供了一种新的线上教学资源推荐解决方案。

ICP-AES法测定电炉渣中二氧化硅

本文研究了采用酸溶的方式消解样品,ICP-AES光谱法测定电炉渣中二氧化硅的分析方法。采用浓盐酸和浓硝酸溶解电炉尾料样品,加入氢氟酸消解二氧化硅和硼酸络合氟离子,采用ICP-AES法测定电炉尾料样品中的二氧化硅含量。二氧化硅的相对标准偏差RSD为0.35%~0.58%,加标回收率为95.6%~102.3%。方法加标回收率好,满足分析方法要求。

电感耦合等离子体原子发射光谱(ICP-AES)法测定真空精炼镁合金物料中铁、铜、镍

真空精炼是目前镁金属提纯的重要工艺,工艺原料及真空精炼提纯镁金属过程残留物中Fe、Cu、Ni含量的准确测定对工艺参数的优化及调整具有重要的指导作用。传统测定方法中以邻二氮杂菲分光光度法、新亚铜灵分光光度法、丁二酮肟分光光度法测定三种元素含量,结果准确,但操作繁琐,周期较长,难以满足工业生产中高效、快速测定的需要,且方法中所需的有机萃取剂对环境污染较大。选择电感耦合等离子体发射光谱(ICP-AES)法测定真空蒸馏精炼镁合金物料中Fe、Cu、Ni,系统探究溶解酸、溶解温度、溶解时间对物料溶解和测定的影响,选择盐酸(1+1)和过氧化氢溶解体系,200℃加热条件下反应20 min为最佳消解镁合金原料条件;选择王水溶解体系,200℃加热条件下反应25 min为真空精炼残留物最佳溶解条件。并探讨ICP-AES测定过程中各元素的检出限和测定下限以及共存元素的干扰情况,建立了ICP-AES法测定真空精炼提纯镁合金物料的方法。测定结果的相对标准偏差(RSD,n=11)为Fe 5.9%~11.5%、Cu 2.6%~11.8%、Ni 3.4%~11.5%,各元素加标回收率为Fe 96.4%~102%、Cu 101%~108%、Ni 103%~105%;按照建立的方法测定镁合金原料、真空精炼残留物中的铁、铜、镍,并与国家标准方法测定结果进行对比,结果相一致。实现了ICP-AES法快速、准确测定真空蒸馏精炼镁合金物料中铁、铜、镍含量,对及时、高效、准确评估真空精炼提纯镁工艺及产品具有重要意义。

基于AE-BP模型的杨木胶合板应力损伤识别

【目的】利用声发射(AE)技术对应力损伤全过程中的杨木胶合板进行无损检测,并利用BP神经网络对AE检测结果进行识别,以提高胶合板损伤检测精度。【方法】以市场占有量较高的托盘用杨木胶合板作为研究对象,在联合AE和应力损伤试验过程中,提取6个AE特征参数,利用声发射RA-AF联合分析法区分杨木胶合板产生裂纹的类型,采用K-均值聚类分析方法确定损伤演化程度和AE特征参数之间的对应关系,利用BP神经网络建立损伤识别模型,并对识别网络进行测试训练。【结果】AE信号幅度和上升时间可有效地表征杨木胶合板应力损伤从微裂纹萌生、产生宏观裂纹至完全断裂的损伤演化过程;通过RA-AF联合分析发现:杨木胶合板在应力损伤试验第一阶段主要为剪切破坏损伤,第二、三阶段主要为拉伸破坏损伤;通过K-均值聚类分析发现损伤类型与AE峰值频率之间的存在较强对应关系,可有效的表征不同的损伤类型:在31 kHz内为基体开裂,在31~100 kHz内为脱胶分层,大于100 kHz为纤维断裂;构建AE-BP神经网络模型对应力损伤类型训练样本的拟合优度是95.94%,测试集的拟合优度是98.89%,模型总拟合优度是96.51%,网络训练效果较好。【结论】在应力承载AE监测过程中,通过构建AE-BP模型,可对杨木胶合板产生的未知损伤进行有效检测并准确识别。

基于单通道AE盲源分离的结构损伤定位

声发射(acoustic emission,简称AE)能够实现复杂板状结构损伤定位,但多数AE检测定位方法仅针对单AE源的情况,而实际中复杂板状结构产生损伤时会伴随多个AE卷积混合信号。为了解决工程中多AE源定位的问题,提出一种单通道AE盲分离-模态提取定位方法。首先,对采集的AE信号进行信号降噪,使用单通道盲源分离算法分离出无回波成分的AE信号,将多源定位转为多个单源定位问题;其次,通过提取单频模态,求取声波传播速度,估计到达时间差来进行疲劳裂纹损伤定位;最后,经过计算机仿真实验和钢箱梁桥断铅半实物仿真实验,验证了方法的准确性和有效性,并通过载荷破坏AE检测实验验证了方法的实用性。结果表明,所提方法能够应用于复杂板状结构多AE源定位问题,为实际工程应用提供了可靠的依据及参考价值。

AE81镁合金轧制变形显微组织演变的研究

通过重力铸造法制备了AE81稀土镁合金,并对固溶处理后的合金在300℃和350℃进行压下量分别为15%、20%、25%和30%的轧制变形。结果表明:稀土元素Ce的加入导致铸态组织中Mg_(17)Al_(12)相不连续分布,镁基体上分布的Al4Ce相以块状形貌、中空管状形貌和针状形貌存在。轧制变形后,AE81合金所产生的变形组织的体积分数随着压下量的增大而增大,当压下量增大到25%时出现了明显的动态再结晶现象,再结晶晶粒的平均尺寸主要分布在200~400nm之间,且动态再结晶区域主要分布在Al_(4)Ce相周围。同时,Mg_(17)Al_(12)析出相的体积分数随着轧制温度和压下量的增大而增大,Mg_(17)Al_(12)相在基体上的分布得到改善。

ICP-AES法和原子荧光法检测硫熏处理对山药中重金属的影响

目的:研究硫黄熏蒸对山药中重金属含量的影响,为评估硫黄熏蒸的安全性及山药加工工艺提供科学依据。方法:选取13批不同产地的硫黄对山药进行熏蒸处理,使用微波消解法对样品进行前处理,并通过电感耦合等离子体原子发射光谱法与原子荧光光谱分析法定量分析硫黄及熏蒸前后山药中汞(Hg)、砷(As)、铜(Cu)、镉(Cd)和铅(Pb)的含量。结果:13批硫黄中Pb、As、Hg含量偏高。硫黄熏蒸后,山药中Pb含量普遍上升,且部分样品中As、Hg和Cu含量亦有增加。结论:硫黄熏蒸可能导致重金属元素从硫黄迁移到山药中,因此应制定严格的硫黄熏蒸工艺规范,确保山药的安全性和质量,减少对人体健康的潜在风险。

Mechanical anisotropy associated with beddings in shale under Brazilian test conditions:Insights from acoustic emission statistics

A comprehensive understanding of shale’s bedding anisotropy is crucial for shale-related engineering activities,such as hydraulic fracturing,drilling and underground excavation.In this study,seven Brazilian tests were conducted on shale samples at different bedding orientations with respect to the loading direction(0°,45°and 90°)and the disc end face(0°,45°and 90°).An acoustic emission(AE)system was employed to capture the evolution of damage and the temporal-spatial distribution of microcracks under splitting-tensile stress.The results show that the Brazilian tensile strength decreases with increasing bedding inclination with respect to the disc end face,while it increases with the angle between bedding and loading directions.Increasing the bedding inclination with respect to the end face facilitates the reduction in b value and enhances the shale’s resistance to microcrack growth during the loading process.Misalignment between the bedding orientation and the end face suppresses the growth of mixed tensile-shear microcracks,while reducing the bedding angle relative to the loading direction is beneficial for creating mixed tensile-shear and tensile cracks.The observed microscopic failure characteristics are attributed to the competing effects of bedding activation and breakage of shale matrix at different bedding inclinations.The temporal-spatial distribution of microcracks,characterized by AE statistics including the correlation dimension and spatial correlation length,illustrates that the fractal evolution of microcracks is independent of bedding anisotropy,whereas the spatial distribution shows a stronger correlation.The evolution features of correlation dimension and spatial correlation length could be potentially used as precursors for shale splitting failure.These findings may be useful for predicting rock mass instability and analyzing the causes of catastrophic rupture.

A robust triaxial localization method of AE source using refraction path

Acoustic emission(AE)localization algorithms based on homogeneous media or single-velocity are less accurate when applied to the triaxial localization experiments.To the end,a robust triaxial localization method of AE source using refraction path is proposed.Firstly,the control equation of the refraction path is established according to the sensor coordinates and arrival times.Secondly,considering the influence of time-difference-of-arrival(TDOA)errors,the residual of the governing equation is calculated to estimate the equation weight.Thirdly,the refraction points in different directions are solved using Snell’s law and orthogonal constraints.Finally,the source coordinates are iteratively solved by weighted correction terms.The feasibility and accuracy of the proposed method are verified by pencil-lead breaking experiments.The simulation results show that the new method is almost unaffected by the refraction ratio,and always holds more stable and accurate positioning performance than the traditional method under different ratios and scales of TDOA outliers.

Characteristic stress variation and microcrack evolution of granite subjected to uniaxial compression using acoustic emission methods

The size of mineral grain has a significant impact on the initiation and propagation of microcracks within rocks.In this study,fine-,medium-,and coarse-grained granites were used to investigate microcrack evolution and characteristic stress under uniaxial compression using the acoustic emission(AE),digital image correlation(DIC),and nuclear magnetic resonance(NMR)measurements.The experimental results show that the characteristic stress of each granite decreased considerably with increasing grain sizes.The inflection points of the b-value occurred earlier with an increase in grain sizes,indicating that the larger grains promote the generation and propagation of microcracks.The distribution characteristics of the average frequency(AF)and the ratio of rise time to amplitude(RA)indicate that the proportion of shear microcracks increases with increasing grain size.The NMR results indicate that the porosity and the proportion of large pores increased with increasing grain size,which may intensify the microcrack evolution.Moreover,analysis of the DIC and AE event rates suggests that the high-displacement regions could serve as a criterion for the degree of microcrack propagation.The study found that granites with larger grains had a higher proportion of high-displacement regions,which can lead to larger-scale cracking or even spalling.These findings are not only beneficial to understand the pattern of microcrack evolution with different grain sizes,but also provide guidance for rock monitoring and instability assessment.

Shear band evolution and acoustic emission characteristics of sandstone containing non-persistent flaws

Direct shear tests were conducted on sandstone specimens under different constant normal stresses to study the coalescence of cracks between non-persistent flaws and the shear sliding characteristics of the shear-formed fault.Digital image correlation and acoustic emission(AE)techniques were used to monitor the evolution of shear bands at the rock bridge area and microcracking behaviors.The experimental results revealed that the shear stresses corresponding to the peak and sub-peak in the stressdisplacement curve are significantly affected by the normal stress.Strain localization bands emerged at both the tip of joints and the rock bridge,and their extension and interaction near the peak stress caused a surge in the AE hit rate and a significant decrease in the AE b value.Short and curvilinear strain bands were detected at low normal stress,while high normal stress generally led to more microcracking events and longer coplanar cracks at the rock bridge area.Furthermore,an increase in normal stress resulted in a higher AE count rate and more energetic AE events during friction sliding along the shearformed fault.It was observed that the elastic energy released during the crack coalescence at the prepeak stage was much greater than that released during friction sliding at the post-peak stage.More than 75%of AE events were located in the low-frequency band(0e100 kHz),and this proportion continued to rise with increasing normal stress.Moreover,more AE events of low AF value and high RA value were observed in specimens subjected to high normal stress,indicating that greater normal stress led to more microcracks of shear nature.

Carbon emission reduction:Contribution of photovoltaic power and practice in China

As a clean and renewable form of energy,photovoltaic(PV)power generation converts solar energy into electrical energy,reducing the consumption of fossil fuels and significantly lowering greenhouse gas emissions.Amidst the global transition towards cleaner forms of energy,countries all around the world are vigorously developing PV technology.

Global hybrid simulations of soft X-ray emissions in the Earth’s magnetosheath

Earth’s magnetopause is a thin boundary separating the shocked solar wind plasma from the magnetospheric plasmas,and it is also the boundary of the solar wind energy transport to the magnetosphere.Soft X-ray imaging allows investigation of the large-scale magnetopause by providing a two-dimensional(2-D)global view from a satellite.By performing 3-D global hybrid-particle-in-cell(hybrid-PIC)simulations,we obtain soft X-ray images of Earth’s magnetopause under different solar wind conditions,such as different plasma densities and directions of the southward interplanetary magnetic field.In all cases,magnetic reconnection occurs at low latitude magnetopause.The soft X-ray images observed by a hypothetical satellite are shown,with all of the following identified:the boundary of the magnetopause,the cusps,and the magnetosheath.Local X-ray emissivity in the magnetosheath is characterized by large amplitude fluctuations(up to 160%);however,the maximum line-of-sight-integrated X-ray intensity matches the tangent directions of the magnetopause well,indicating that these fluctuations have limited impact on identifying the magnetopause boundary in the X-ray images.Moreover,the magnetopause boundary can be identified using multiple viewing geometries.We also find that solar wind conditions have little effect on the magnetopause identification.The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)mission will provide X-ray images of the magnetopause for the first time,and our global hybrid-PIC simulation results can help better understand the 2-D X-ray images of the magnetopause from a 3-D perspective,with particle kinetic effects considered.

基于FPGA的AES和ECC算法图像加密

随着数字图像的使用次数日益增多,保护机密图像数据免受未经授权的访问较为重要。针对数字图像在通信、存储和传输等领域存在的安全问题,文中基于对称算法模型和非对称算法模型的优点提出一种具有高安全性和高速度性的数字信封技术密码方案。该方案以AES(Advanced Encryption Standard)和ECC(Elliptic Curve Cryptography)为基础,经优化后用于对称密钥共享的ECC硬件架构来提高密钥的安全性。通过加入伪随机数、使用列移位替代列混淆运算以及三维S-box等方式对传统AES进行优化,在保持香农扩散和混淆原理的同时降低了时间复杂性。基于FPGA(Field Programmable Gate Array)实现AES算法的数字图像加密仿真以及性能测试。测试结果表明,所提密码方案具有快速性、高安全性和有效性等优点,能够有效地实现图像加密。

基于AES的改进视频加密测试

为了使得视频加密技术具有更加良好的加密效果,在原本AES加密算法基础上进行了创新,通过加密元素的选取、运动矢量的加密方案设计、DCT变化系数的加密方案设计三部分进行了展开分析与实验;经过后续仿真验证,密钥敏感性得到了很好的提升;视频质量方面,改进后的AES算法的RGB直方图可知其加密效果和解密还原效果良好,经过对比分析,改进后的AES算法加密的SSIM值最小、PSNR值更低,即加密效果相对更好;经过计算可知,编码时间百分比增加了0.23%,解码时间百分比增加了8.56%,对NPCR、UACI以及加密前后视频帧像素对的相关系数等参数分别测试可知,相比前人的几种加密方式,改进后视频加密安全性能最好;综上分析可知,改进后视频加密效果最好。