分布式DoS攻击检测系统的改进研究

为了对抗分布式DoS攻击,提出了一个改进的分布式DoS攻击检测系统:采用贝叶斯方法,根据第一次连接的状态,计算后验概率,据此对系统检测攻能进行改进;采用被动响应的方式,改进系统响应功能,对检测到的入侵行为,进行实时响应.仿真实验表明,该改进措施减少了误报率和漏报率,提高了系统的实时响应性.     

具有黏土耐受性缓凝剂的制备及在混凝土中的应用

合成了一种含不同磷酸基个数的有机磷酸盐缓凝剂,并将其结构、缓凝性能及抗黏土性能进行了测试表征。混凝土试验测试结果表明,合成出的磷酸盐缓凝剂能延缓水泥水化,缓凝作用好,与聚羧酸减水剂(PCE)复配后,提高了聚羧酸减水剂(PCE)的保坍性能。同时磷酸基缓凝剂还具有很好的抗黏土性能,吸附性能测试表明,所合成的磷酸盐缓凝剂能减少蒙脱土对减水剂的吸附。     

活性炭净化室内甲醛的研究进展

活性炭具有原材料来源广泛、成本低廉、生产工艺简单且成熟、使用灵活等优点,应用前景广阔.甲醛一直是室内空气净化中的难点与重点,长时间处于含有甲醛的环境会影响人类的身心健康.活性炭可有效去除室内甲醛并降低空气净化成本,因而活性炭被运用于治理各种室内环境.本文详细介绍了活性炭的种类,去除室内甲醛的机理,并分别讨论了活性炭原材料特性、改性方法以及环境条件等因素对甲醛去除效果的影响,指出现有研究存在的局限性和待解决的问题,对未来室温下采用活性炭去除甲醛提出了展望.     

支持受损数据定位与恢复的动态群用户可证明存储

The outsourced storage mode of cloud computing leads to the separation of data ownership and management rights of data owners, which changes the data storage network model and security model. To effectively deal with the software and hardware failures of the cloud server and the potential dishonest service provider and also ensure the availability of the data owners’ data, the design of secure and efficient data availability and recoverability auditing scheme has both theoretical and practical importance in solving the concern of users and ensuring the security of cloud data. However, most of the existing studies were designed for the security and efficiency of data integrity or recoverability schemes, without considering the fast identification and reliable recovery of damaged data under dynamic group users. Thus, to quickly identify and recover damaged data, a publicly verifiable proof of storage scheme was proposed for dynamic group cloud users. The designed scheme enabled a trusted third-party auditor to efficiently identify the damaged files through a challenge-response protocol and allowed the cloud storage server to effectively recover them when the degree of data damage is less than an error correction ability threshold. The scheme combined association calculation and accumulation calculation, which effectively reduced the number of calculations for the identification of damaged data. By combining erasure coding and shared coding technology, the scheme achieved effective recovery of damaged data of dynamic group users. At the same time, the scheme also supported dynamic user revocation, which ensured the integrity audit and reliable recovery of the collective data after user revocation. The network model and threat model of the designed scheme were defined and the security of the scheme under the corresponding security model was proved. Through the prototype implementation of the scheme in the real environment and the modular performance analysis, it is proved that the proposed scheme can effectively identify the damaged data and reliably recover the cloud data when the data is damaged. Besides, compared with other schemes, it is also proved that the proposed scheme has less computational overhead in identifying and recovering damaged data. © 2022, Beijing Xintong Media Co., Ltd.. All rights reserved.     

容忍延迟网络中基于生灭模型的消息控制方法

提出了在多拷贝传递的基础上增加消息拷贝消除机制,合理地控制了网络中的消息拷贝数.在网络中根据节点相遇时消息拷贝教发生变化的特性,构造了消息拷贝数的离散时间的马尔可夫链,建立生灭模型,进一步验证并得出了平稳分布.通过仿真实验比较,相遇次数与时间基本上是线性关系,与理论模型极为相近.与传染路由比较,采用拷贝消除机制网络中的...     

数字递推法推导等价组态j-j耦合谱项

ｊ－ｊ耦合谱项的推导对于研究重核原子的结构和光谱十分重要,但用人工方法推导谱项十分繁琐。工作量也很大。其难点在于推导组合组态「（ｊ）＾ｎ」Ｊ的Ｊ值,文章中采用一种新的数字递推法解决了这一难题。     

含稀土Li3VO4基材料的非醇盐溶胶-凝胶法合成及其离子导电性

用非醇盐溶胶－凝胶法制备了含稀土Ｌｉ３ＶＯ４基锂离子导体材料,应用交流阻抗谱技术测定了样品的离子电导。实验表明：稀土氧化物的加入在一定程度上改变了Ｌｉ３ＶＯ４的电导率,讨论了这种影响的机理。     

Li3VO4的非醇盐溶胶—凝胶法合成及其离子导电性

用溶胶凝胶法制备了锂离子导体Ｌｉ３ＶＯ４的纯相,应用交流阻抗谱技术测定了样品的离子电导,实验表明,与传统固相方法制备的Ｌｉ３ＶＯ４相比,用这种方法可以使Ｌｉ３ＶＯ４的生成温度降低,其烧结体具有更高的离子导电率。     

基于三分类的击键序列身份认证

针对基于统计学用户击键模式识别算法识别率较低的不足，提出了一种统计学三分类主机用户身份认证算法。该方法通过对当前注册用户的击键特征与由训练样本得到的标准击键特征进行比较，将当前注册用户划分为合法用户类、怀疑类与入侵类三类,对怀疑类采用二次识别机制。 采用动态判别域值，引入了与系统安全性和友好性相关的可控参量k，由系统管理员根据实际确定。并对该算法性能进行了理论分析与实验测试，结果表明该算法在保持贝叶斯统计算法需要训练样本集规模较小、算法收敛速度快优点的基础上,识别精度高于贝叶斯统计算法，错误拒绝率(FRR)和错误通过率(FAR)分别为1.6%和1.5%。     

改进的软件测试预测模型

基于Gompertz模型进行软件测试预测存在数据拟合精度差的不足,提出改进的Gompertz模型,用高斯-牛顿法将原Gompertz方程式按照泰勒级数展开,选取样本观测值与参数的初始点后,为了进一步估算参数,用最小二乘法反复迭代修正参数校正量。用实测数据验证改进后的模型,结果表明改进后的模型在缺陷发现的准确率、与实际数据的拟合度、预测值与实际值的绝对误差率方面都优于原模型。