结合通道共生和选择集成的彩色图像隐写分析

目的 为了有效对抗针对彩色图像的隐写方案,提出一种新的基于RGB格式的彩色图像隐写分析方法.方法 该方法中的特征包括通道内特征和通道间特征,首先从通道内差分平面上提取共生矩阵特征构成通道内特征集合,通道内特征可以有效捕捉到每一个颜色通道内差分系数之间的相关性;然后对通道与通道相互之间的二次差分平面上提取共生矩阵特征构成通道间特征集合,通道间特征可以捕捉到两两通道之间的相关性.在分类阶段利用遗传算法对多个子分类器进行权值优化,选择权值最优的若干个子分类器,通过众数投票进行集成判决,最终获得最佳的检测性能.结果 针对误检率,提出的通道共生特征比SPAM特征要降低4%~5%,而选择性集成分类器要比完全集成分类器要降低1%~2%.结论 该方法具有较低的时间复杂度,适合小嵌入率的RGB格式彩色图像,在整体性能上优于已有的隐写分析方法.     

外包钢-混凝土组合梁与钢筋混凝土柱节点的试验研究

外包钢-混凝土组合梁是一种新型组合梁,在负弯矩作用下具有良好的工作性能,其与柱连接节点的构造还有待合理设计并试验验证。采用两种不同的构造形式,设计4个外包钢-混凝土组合梁与钢筋混凝土柱的连接节点,并对其进行低周反复荷载作用下的试验研究。对节点的破坏形态、滞回曲线、强度、延性和钢筋、钢板的应变等性能进行分析,结果表明:通过合理的构造措施,外包钢-混凝土组合梁与钢筋混凝土柱的连接节点具有较好的受剪承载力、延性和耗能能力,能够满足工程要求。在此基础上对节点的受力机理进行探讨,提出节点核心区受剪承载力的计算公式,计算结果和试验结果吻合良好。     

Adaptive JPEG steganography with new distortion function

This paper presents an adaptive steganographic scheme in JPEG images by designing a novel distortion function. While some previous works employed distortion functions based on coefficient difference, we point out that the data embedding on coefficients with larger absolute values may cause less steganalytic detectability. In the proposed scheme, the distortion function is derived from both the coefficient residual and coefficient value, which measures the risks of detection due to the modification on cover data. With an exhaustive searching method, the parameters of the proposed distortion function are optimized. Then, we may employ syndrome trellis coding to embed the secret data into JPEG images when keeping a low risk. This way, the modifications are forced into high textured areas in JPEG images, and experimental results demonstrate that the steganographic security is improved by the designed distortion function.     

PAC阳离子聚合物压裂液体系的研究

研制了一种新型的PAC阳离子聚合物压裂液体系，对其配方与性能进行了研究。确定了PAC阳离子聚合物压裂液体系最佳配方：(0．30％～0．80％)PAC (0．05％．0．10％)HPAM (1．0HD％～2．0HD％)KCl 0．10％AE169 (0．05％～0．10％)TA—1，破胶剂可选用0．30％～0．50％的过硫酸铵溶液。该体系流变性能好，携砂能力强，粘土稳定性好，防乳破乳效果明显，具有很好的破胶性，破胶后水不溶性残渣含量低，对地层渗透率损害值很小，适应于粘土含量较高即存在水敏或低渗透油藏的油层压裂改造，取得了很好的现场应用效果。     

Unsupervised steganalysis over social networks based on multi-reference sub-image sets

Multimedia Tools and Applications - This work proposes a new unsupervised steganalysis scheme which mainly tackles the challenge in identifying individual JPEG image as stego or cover. The proposed...     

2500 m3高炉低风温运行的应对措施

针对河钢承钢2 500 m~3高炉因检修而导致热风温度大幅降低,严重影响高炉稳定顺行的现状,通过提高热风炉烧炉效率、降低焦炭负荷和煤比、调整送风制度和装料制度等措施,炉温波动幅度显著减小,煤气利用率提升至48%以上,高炉产量逐渐恢复,保证了高炉在低风温条件下的稳定顺行。     

Separable reversible data hiding in encrypted images based on scalable blocks

This paper proposes a new separable reversible data hiding method for encrypted images. Proposed scheme employs the pixel redundancy of natural images to construct embedding space. First, cover image is divided into multiple blocks with different scales. According to the pixel average value of each block, the lowest two bits of every pixel are vacated as reserved rooms. Subsequently, the whole image is encrypted by using stream cipher and the secret messages are finally embedded into the reserved rooms by the embedding key. Proposed scheme is separable in the sense that the recipient can achieve different function by the following ways: (a) If the recipient has only decryption key, an approximation plaintext image containing the embedded information can be obtained. (b) If the recipient has only embedded key, secret messages can be extracted correctly. (c) If the recipient has both decryption key and embedded key, he can not only extract the secret messages, but recover the original cover image perfectly. Extensive experiments are performed to show that our proposed schemes outperform existing reversible data hiding schemes in terms of visual quality, embedding capacity and security performance, even if a large-scale image database is used.

     

3D Solar Evaporation Enhancement by Superhydrophilic Copper Foam Inverted Cone and Graphene Oxide Functionalization Synergistic Cooperation

Solar evaporation has become a promising and sustainable technique for harvesting freshwater from seawater and wastewater. However, the applicability and efficacy of solar evaporation need further improvement to achieve high production closer to theoretical limits in compact systems. A 3D (three-dimensional) hierarchical inverted conical solar evaporation is developed, which consists of a 3D copper foam skeleton cone decorated with micro-/nano-structures functionalized with graphene oxide, fabricated via easy and scalable wet oxidation, impregnation, and drying at room temperature. The proposed configuration empowers high-efficiency solar absorption, continuous liquid film spreading and transport, enhanced interfacial local evaporation, and rapid vapor diffusion through the pores. More notably, the 3D conical evaporator realizes thermal localization at the skeleton interface and allows evaporation to occur along the complete structure with unimpeded liquid and vapor rapid diffusion. The solar–thermal evaporation efficiency under 1-Sun is as high as 93% with a maximum evaporation rate per unit area of 1.71 kg·m⁻²·h⁻¹. This work highlights the benefits of synergistic cooperation of an easily scalable 3D hierarchical functiomicro-/nano-structured copper foam skeletons and functionalized graphene oxide for high-efficient solar evaporation of interest to numerous applications.     

掺有机塑化剂砌筑砂浆的配合比设计

在砌筑砂浆中掺入有机塑化剂可以经济有效地改善砂浆的工作性已广为人知,但其对砌体强度的影响易被忽视.砌筑砂浆是将砖、石、砌块等粘结成为砌体的砂浆,砂浆本身的强度要保证,砌体的强度更重要.     

SD大鼠McA- RH7777细胞系肝癌模型构建及其特点

【摘要】 目的 研究SD大鼠McA- RH7777细胞系肝细胞肝癌（HCC）模型构建及其相关瘤体生长、检测指标及影像学特点,评价该模型构建方法可行性和模型稳定性。方法 40只SD大鼠随机分为实验组（A组,n=30,肝脏注射种植McA- RH7777细胞0.2 mL）、空白对照组（B组,n=10,肝脏单纯注射等量0.9%氯化钠溶液）。A组大鼠开腹手术后7、14、21 d分别接受MR和增强CT检查并测量瘤体长径。手术后7、14、21 d,分别随机取A、B组10、3只大鼠麻醉,经颈静脉取血检测碱性磷酸酶（ALP）、丙氨酸转氨酶（ALT）、天冬氨酸转氨酶（AST）、肌酐（Crea）、尿素（Urea）;放血法处死大鼠,HE染色和VEGF免疫组化检测肿瘤组织形态。结果 A组27只（90%）大鼠成功成瘤,7、14、21 d时瘤体长径分别为（9.4±2.6） mm、（20.6±4.3） mm、（17.4±1.2） mm;成瘤大鼠CT平扫可见肝脏内低密度病灶,增强CT显示病灶环形强化,MR提示病灶T1加权为低信号,T2加权为高信号,弥散加权成像（DWI）为高信号。两组7、14、21 d血液ALP、ALT、AST、Crea、Urea检测结果比较,差异均无统计学意义（P＜0.05）。HE染色和VEGF免疫组化检测结果均提示肿瘤组织形态。结论 SD大鼠McA- RH7777细胞系HCC模型是可行、稳定、安全的。