Steganalysis of neural networks based on parameter statistical bias

Many pretrained deep learning models have been released to help engineers and researchers develop deep learning-based systems or conduct research with minimall effort. Previous work has shown that at secret message can be embedded in neural network parameters without compromising the accuracy of the model. Malicious developers can, therefore, hide malware or other baneful information in pretrained models, causing harm to society. Hence, reliable detection of these vicious pretrained models is urgently needed. We analyze existing approaches for hiding messages and find that they will ineluctably cause biases in the parameter statistics. Therefore, we propose steganalysis methods for steganography on neural network parameters that extract statistics from benign and malicious models and build classifiers based on the extracted statistics. To the best of our knowledge, this is the first study on neural network steganalysis. The experimental results reveal that our proposed algorithm can effectively detect a model with an embedded message. Notably, our detection methods are still valid in cases where the payload of the stego model is low.     

南海的形成与演变

南海是东亚陆缘最大的边缘海，构造类型多样，油气资源丰富。然而，科学家们对于南海如何发育演化成今天的局面、深部的驱动机制以及影响因素尚存在诸多争议。为解决上述问题，科学家在南海开展了大量的地球物理调查以及三轮五次的国际大洋钻探，取得重要进展。文章综合多年来的研究和认识，对南海的成因归属和发育演化历史进行了总结。在此基础上提出尚存在的三个前沿科学问题，包括南海主-被动陆缘转换的机制、南海陆缘破裂方式、南海存在大量岩浆活动的机制等，希望能通过更多深探测手段和更多的大洋钻探去揭示这些问题，从而服务南海的资源开发和灾害预警。     

可自修复的高延性混凝土(ECC)在机场道面的适用性分析

在飞机荷载与环境荷载长期共同作用下,机场道面易出现裂缝、接缝和竖向位移类病害,使运营阶段维修成本高.提出将具有自修复功能的高延性水泥基材料(ECC)用于机场道面,以控制裂缝发展、实现无缝连接;并利用ECC因二次反应而使微裂缝愈合的特性,减少路面维护工作,延长使用寿命.通过试验手段研究了ECC材料应用于机场道面的力学行为、自修复行为和早期开裂潜能.试验结果表明:机场道面用ECC材料在拉伸荷载作用下,其拉伸应变可达3.67％(约为普遍混凝土的400倍);在弯曲荷载作用下,其竖向弯曲变形可达6.33 mm;抗压强度与弯曲强度分别为43.9 MPa和12.68 MPa,可满足机场道面的使用要求.在受约束条件下,ECC表现出较低的早期开裂潜能.由于自修复能力,裂损ECC的拉伸刚度、拉伸应变与拉伸强度几乎可恢复至未裂时的程度;其水渗透系数随自修复进程逐渐降低,最终达到未裂时的渗透水平.研究结果表明ECC材料用于无缝机场道面具有较高适用性.     

具有迁移效应和隔离措施的COVID-19传播模型分析

基于COVID-19传播过程中人口流动的必然性、无症状感染者的普遍性和隔离策略的有效性,该文提出了一类具有迁移效应、无症状感染者、自我防护意识和隔离策略的COVID-19传播动力学模型,利用下一代矩阵方法给出了各类子系统和全系统基本再生数的精确表达式.进一步地,通过采用线性近似理论,构造Lyapunov函数、比较原理等方法,得到了无病平衡点的全局渐近稳定性以及疾病的持久性.最后,数值模拟解释了主要的理论结果以及人口的迁移和隔离对疾病传播的影响.     

基于知识图谱的核电设备健康管理知识建模与分析

随着信息技术发展,设备健康数据与知识图谱技术结合为设备健康发展带来新的发展机遇,知识图谱利用其多种特异性优势,使企业系统中积累的海量设备维修数据得到有效整合利用.本文提出基于知识图谱的核电设备健康管理知识建模与分析方法,并根据实体关系模型构建维修知识图谱本体框架,同时基于核电企业实际的维修工单数据,从统计分析和关联分析两方面取得良好的实践效果.研究结果表明,知识图谱能够在设备维修知识的集成上解决传统的数据孤岛问题,同时能基于故障的可视化分析为维修人员和管理人员提供决策和知识支持.     

Impact of the RMB Joining in the SDR Basket on Its Internationalization from the Perspective of Risk Spillover

For evaluating the influence of the Chinese renminbi(RMB) joining in the special drawing right(SDR) basket on RMB's internationalization, the authors systemically study the risk spillover networks and examine the dynamic relationship of exchange rates among the SDR currencies including the US dollar(USD), European Union euro(EUR), Japanese yen(JPY) and British pound(GBP).The empirical results demonstrate that the USD takes a dominant position and holds the biggest risk spillover to other currencies, and the RMB's inclusion to the SDR basket makes the risk spillover to get average, giving rise to the SDR currency system more stable to a certain degree. The inclusion of the RMB in the SDR not only can reduce the systematic risk of the SDR, but also has a certain impact on the international exchange rate markets. Nowadays, in front of the growing trade friction, more such researches could help to effectively deal with the currency disputes.     

双向认知网络物理层安全策略建模及仿真研究

为提高移动通信系统的性能,构建了一个存在主网络干扰和窃听者的双向认知中继网络的物理层安全传输模型,设计了一种中继选择和功率分配的联合优化策略,用于对抗窃听者,保护收发节点的信息传输。通过仿真分析得出,此非凸优化问题限制条件较多,难以保证粒子群优化算法随机生成的初始解的可行性,从而造成求解困难。提出了一种基于可变网格优化和粒子群优化算法的混合优化算法。仿真结果表明此算法提高了次级网络的保密速率,提升了次级网络的安全性能。     

Evolutionary game analysis of low-carbon behavior credit supervision of logistics enterprises

Based on the low-carbon obligation fulfillment of Chinese logistics enterprises, this study constructs a tripartite evolutionary game model to analyze the evolutionary process of the interaction between the local government, logistics enterprises and the public in the process of low-carbon behavior credit supervision. Then using Netlogo software, a parameter simulation experiment is conducted to determine the optimal policy for improving the effect of supervision. The results are as follows: ① The combined influence of the local government and the public can effectively change the strategic choice of enterprises and promote the low-carbon behavior of enterprises. ② In terms of improving the effect of supervision, reducing the cost of government supervision would have a highly significant effect, and reducing the cost of the public would be counterproductive. ③ Increasing the government subsidies to enterprises and the government’s fines to enterprises both have a significant effect, and the effect of improving the former is better. However, increasing the severity of higher-level governments punishing local governments will reduce the stability of the system. ④ Supervision can be more effective by increasing the public’s impact on enterprises’ earnings rather than by increasing government subsidies to the public.     

基于动态博弈的补贴模式对机场群航线网络结构的影响研究

为探讨不同补贴模式对机场群航线网络结构的影响，本文构建了关于机场、航空公司和乘客之间的动态博弈模型，通过逆向归纳法得到了纳什均衡条件. 研究结果发现：（1）不同的补贴模式对多机场航线网络结构产生重要影响，低补贴模式促使机场群倾向于形成点对点航线网络结构，反之，在高补贴模式下机场群易于形成枢纽辐射航线网络； （2）在较低的空铁联运总运营成本环境下，补贴竞争使得航空公司倾向于选择系统内的大型机场作为枢纽机场；反之，如果空铁联运总运营成本相对较高，补贴竞争使得航空公司倾向于选择小机场作为枢纽节点； （3）随航班固定成本和空铁联运总运营成本的增大，大型机场作为枢纽节点的概率逐渐减少，而小机场被选为枢纽节点的概率将逐渐增大. 随着机场群内大型机场腹地服务人口比例的增大，航空公司选择点对点航线网络的概率在减小. 研究结论能够为民航管理部门科学制定和应用航线补贴政策提供决策依据.