A Novel PDF Shape Control Approach for Nonlinear Stochastic Systems

In this work, a novel shape control approach of the probability density function (PDF) for nonlinear stochastic systems is presented. First, we provide the formula for the PDF shape controller without devising the control law of the controller. Then, based on the exact analytical solution of the Fokker-Planck-Kolmogorov (FPK) equation, the product function of the polynomial and the exponential polynomial is regarded as the stationary PDF of the state response. To validate the performance of the proposed control approach, we compared it with the exponential polynomial method and the multi-Gaussian closure method by implementing comparative simulation experiments. The results show that the novel PDF shape control approach is effective and feasible. Using an equal number of parameters, our method can achieve a similar or better control effect as the exponential polynomial method. By comparison with the multi-Gaussian closure method, our method has clear advantages in PDF shape control performance. For all cases, the integral of squared error and the errors of first four moments of our proposed method were very small, indicating superior performance and promising good overall control effects of our method. The approach presented in this study provides an alternative for PDF shape control in nonlinear stochastic systems.      

SDMP: A secure detector for epidemic disease file based on DNN

In the era of intelligent office, reading and processing PDF files by mobile devices have become important parts of various businesses. However, due to the universality of mobile device and PDF file, they are also often used by attackers to disguise malicious codes, which makes users in danger. Especially in medical field, once computer virus invades medical experts’ devices, a large number of data with high medical research value will face huge damage and irreparable loss. Therefore, how to ensure the security when users make use of PDF files is a challenging and meaningful task. In this paper, we design an secure detector of malicious PDF file for epidemic disease file based on Deep Neural Network to solve the problem of privacy and security in handling epidemic disease file. Experiment shows that the detection accuracy of our detector can achieve up to 99.3%. Moreover, the time cost on raining and forecasting of the proposed DNN model is extremely low, less than 1s per epoch.     

PDF文档与Web数据库接口技术初探

本文详细讨论了PDF文档表单数据存贮文件FDF的基本组成结构 ,并通过实例给出结合ASP技术实现将浏览器端PDF表单数据提交给Web数据库、从Web数据库读取记录动态生成PDF文档的过程。     

基于微博扩展的用户兴趣主题挖掘算法

为解决基于微博的用户兴趣建模存在建模不全面的问题,提出一种基于微博扩展的用户兴趣主题挖掘算法。通过结合用户自身兴趣及用户关注人的兴趣来扩充微博用户兴趣,将兴趣分为长期兴趣、过期兴趣、近期兴趣,利用改进的TF． IDF算法分析相关微博内容,利用基于时间及文档频率加权的主题词重要度计算兴趣主题词得分,得出综合全面的用户兴趣。实验结果表明,综合分析用户及用户关注人的兴趣,可以有效得到真实、全面、包含潜在兴趣的用户个人兴趣。     

面向恶意PDF文档分类的对抗样本生成方法研究CSCD

通过恶意文档来传播恶意软件在现代互联网中是非常普遍的,这也是众多机构面临的最高风险之一。PDF文档是全世界应用最广泛的文档类型,因此由其引发的攻击数不胜数。使用机器学习方法对恶意文档进行检测是流行且有效的途径,在面对攻击者精心设计的样本时,机器学习分类器的鲁棒性有可能暴露一定的问题。在计算机视觉领域中,对抗性学习已经在许多场景下被证明是一种有效的提升分类器鲁棒性的方法。对于恶意文档检测而言,我们仍然缺少一种用于针对各种攻击场景生成对抗样本的综合性方法。在本文中,我们介绍了PDF文件格式的基础知识,以及有效的恶意PDF文档检测器和对抗样本生成技术。我们提出了一种恶意文档检测领域的对抗性学习模型来生成对抗样本,并使用生成的对抗样本研究了多检测器假设场景的检测效果(及逃避有效性)。该模型的关键操作为关联特征提取和特征修改,其中关联特征提取用于找到不同特征空间之间的关联,特征修改用于维持样本的稳定性。最后攻击算法利用基于动量迭代梯度的思想来提高生成对抗样本的成功率和效率。我们结合一些具有信服力的数据集,严格设置了实验环境和指标,之后进行了对抗样本攻击和鲁棒性提升测试。实验结果证明,该模型可以保持较高的对抗样本生成率和攻击成功率。此外,该模型可以应用于其他恶意软件检测器,并有助于检测器鲁棒性的优化。     

Transmutation-incineration potential of transuraniums discharged from PWR-UO2 spent fuel in modified PROMETHEUS fusion reactor

This study presents the potential of the burning and/or transmutation (B/T) of transuraniums (TRUs), discharged from the pressured water reactor PWR-UO₂ spent fuel, in the modified PROMETHEUS-H fusion reactor. Two different design shapes (Models A and B) were considered. The transmutation zone (TZ), which contains the mixture of TRU nuclides (10%), was located in the modified blankets. The volume fraction of Pu in the mixture is raised from 0 to 40% stepped by 10% to determine its effect on the B/T. The fuel spheres were cladded with SiC (5%) and cooled with high-pressured helium gas (85%) for nuclear heat transfer. The calculations were performed for an operation period (OP) of up to 10 years by 75% plant factor (η) under a neutron wall load (P) of 4.7 MW/m². The results bring out that: (1) the Model B transmutes the TRUs more rapidly than the Model A; (2) the effective half-lives decrease about 20 and 40% with the increase of Pu fraction in the cases of Models A and B, respectively; (3) the M values are quite high with respect to the M value of the original PROMETHEUS fusion reactor; (4) the blankets can produce substantial electricity in situ.     

PDF417纠错码原理及实现

介绍了Reed Solomon纠错码原理和它在PDF417二维条形码中的应用方法。详尽推导了在迦罗华域GF(929)域内编译码的方法,并通过实例进行了具体说明。同时提出一种适用于PDF417纠错编码和译码的查表方法,可以简单确定任意码字在GF(929)内所对应的本原元的幂次。运用该方法可以快速而准确地计算出纠错码生成多项式的系数序列以及差错伴随式。     

DES算法在二维条码数据加密中的应用

DES算法将整个算法的安全性寓于密钥之中,具有算法简单、成本低等特点,因此是实现条形码加密的理想算法。结合DES加密技术设计并实现了二维条码PDF4 17数据生成和自动识别系统。加密技术的有效使用防止了信息的窃取或篡改,起到了保密和防伪的效果,通过采用加密技术还克服了普通二维条码所载信息容易被破译和复制的缺点,提高了二维条码上信息的安全性、可靠性,从而更好地满足对信息安全性有特殊要求的领域。     

将光栅图象转换成PDF文件的研究与实现

本文研究了将TIFF／IT格式的光栅图象文件转换成PDF文件的方法。该方法通过将TIFF／IT文件中的图形文字矢量化，并采用高效的数据压缩方法存储图象和矢量化的图形命令，使得生成的PDF文件不仅质量好而且数据量小。它完全可以满足印刷业双字节文字PDF文件生产的要求。     

PDF文件链接信息提取与修改

主要介绍了航空规章采用PDF文件格式,使用了书签、链接功能;利用AdobeAcrobat提供的编程接口编写Plug-in插件,实现了文件内和文件间的链接信息自动生成技术。