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.     

试析中国博物馆宏观管理体制发展历程、特点及趋势

 中国博物馆诞生以来，在中国共产党的领导下，其宏观管理体制主要经历了4个阶段的调整，有效推动和加强了博物馆事业高质量发展。目前，中国博物馆宏观管理呈现出分级属地管理、管理主体多元、管理方式多样、法制化建设深入等特点；同时，文旅融合日益紧密、行业协会及联盟推动作用显著、以数字化建设和人才机制建设为抓手也成为了博物馆宏观管理体制发展的新趋势。     

Moving beyond Volatility Index (VIX): HARnessing the term structure of implied volatility

This paper considers how information from the implied volatility (IV) term structure can be harnessed to improve stock return volatility forecasting within the state-of-the-art HAR model. Factors are extracted from the IV term structure and included as exogenous variables in the HAR framework. We found that including slope and curvature factors leads to significant forecast improvements over the HAR benchmark at a range of forecast horizons, compared with the standard HAR model and HAR model with VIX as IV information set.     

高含钡锶离子采出水成垢趋势分析方法研究——以耿83区刘六增压站采出水为例

油田注水开发导致采出液的含水量逐年增加,部分区块采出液水体结垢导致集输管线堵塞等各种问题日益严重。根据耿83区高含钡锶离子的特点,分别采用常规水分析方法、原子吸收光谱法和等离子体原子发射光谱法测试采出水和注入水的水样离子组成成分、水样矿化度、水型等。实验结果表明,在高矿化度含多种阳离子的水溶液中,原子吸收光谱法测试结果更准确。采用原子吸收光谱法对该区块结垢特征系统分析,计算结垢理论值,得出主要为硫酸钡和硫酸锶垢型。将现场垢样通过能谱和扫描电镜分析,验证得到与水样分析出的垢体一致。该方法能准确判定出垢体和垢型,为进一步采取有效的防垢、清垢措施提供重要的依据。     

能量捕获无线通信系统的在线式动态能量分配

为了实现数据传输的可持续保障,通过捕获环境能量供能的无线通信系统具有独到的优越性。文中提出了一种在线式动态能量分配算法,假定发射端可通过反馈信道获得信道状态和能量到达的概率分布函数,根据凹函数特性对能量在各个时隙间进行分配,平衡当前时隙可达的信道容量和未来时隙可达的信道容量期望值。仿真结果表明,该算法实现简单,性能接近离线场景下最优的阶梯注水法,与贪婪算法和半保留算法相比,性能增益至少可以提高3 d B以上,具有更好的应用价值。     

基于轴心轨迹重构的自动平衡控制输入算法优化

以转子呈各向异性、支撑刚度非线性时的自动平衡系统为研究对象，提出一种轴心轨迹重构方法来实时测算稳定的基频振动矢量作为最优自动平衡的控制输入，并在自动平衡试验台上进行了试验验证。结果表明，相较于传统单向传感器自动平衡系统，基于轴心轨迹重构的自动平衡控制输入算法的振动幅值降低了7.54 μm，同比下降约5%。     

Theoretical and experimental design of Pt-Co(OH)_2 electrocatalyst for efficient HER performance in alkaline solution

Design efficient electrocatalysts become significant for the hydrogen evolution reaction (HER) in alkaline solution.Here,the HER performance on Pt-Co(OH)2 has been investigated by using DFT calculations.Compared with pure Pt,the Pt-Co(OH)2 shows excellent hydrogen binding energy (-0.29 eV) and hydrogen adsorption free energy (0.02 eV).More strikingly,the water dissociation process on Pt-Co(OH)2 is an exothermic reaction while that of Pt is an endothermic reaction,demonstrating that the Pt-Co(OH)_2 is an excellent catalyst for HER in alkaline medium.Then the two-step electrodepositions was used to fabricate Pt-Co(OH)2 on the carbon paper (CP).The Pt-Co(OH)_2/CP shows the lowest overpotential of only 37.6 mV at a current density of 10 mA cm~(-2) in 0.1M KOH,the smallest Tafel slope of58 mV dec~(-1) and the good stability for 20000s without obvious degradation.     

基于BIM技术的室内照明仿真模拟软件计算精度解析

建筑照明专业参与BIM （building information modeling）技术的同平台作业还处于起步阶段。DIALux evo 8.2和ElumTools 2019.07是目前仅有的参与BIM技术的室内照明仿真模拟软件。采用CIE （Commission Internationale de i''Eclairage）发布的CIE 171：2006—test cases to assess the accuracy of lighting computer programs的5.2至5.8测试用例，通过验证这2款软件的计算精度，分析得出软件性能的优缺点。结果表明：在计算点光源直接照度、面光源直接照度以及光通量守恒性能这3个方面，2款软件均具有较高精度；计算大面积漫反射、遇遮挡和不同反射率这3种情况的间接照度时，DIALux evo 8.2计算精度优于ElumTools 2019.07；计算小面积漫反射的间接照度精度时，ElumTools 2019.07计算精度优于DIALux evo 8.2；计算定向透射性能时，这2款软件精度均比较低。进一步分析得出：核心算法是产生误差的主要原因，2款软件信息交换均存在一定缺陷。因此，采用光子映射算法，创建建筑与照明全信息交换接口将成为未来基于BIM技术的室内照明仿真模拟软件的研发方向。     

基于偏振复用和反射式半导体光放大器的WDM-RoF-PON系统设计

基于偏振复用原理和反射式半导体光放大器RSOA(reflective semiconductor optical amplifier)的再调制特性,融入了光载无线RoF(radio over fiber)技术,设计了一种新型的可以实现多种信号混传的波分复用无源光网络WDM-PON(wavelength division multiplexing passive optical network)系统。在中心站,无线信号和有线信号同时调制到两个偏振态正交的光载波上,并耦合到标准单模光纤中传输。在基站,将两个偏振态正交的信号分离后,一方面可以探测得到四倍频毫米波信号和有线信号,另一方面还可以通过RSOA实现载波重用。通过Optisystem软件对该系统进行模拟仿真,得到了调制信号的光谱和接收端信号的眼图,分析了传输信号误码率与接收光功率的关系,结果表明,该系统传输性能良好。