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Steganalysis using Regional Correlation and Second-order Markov Features
Su Jinyang,Zeng Xianting,Wang Lei 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.1
A blind steganalysis based on regional correlation and second-order Markov transition probability matrix is proposed for JPEG images. By analyzing the region correlation of JPEG image, the Markov transition probability matrix is used to capture the correlation of intra-block and inter-block DCT coefficients. In addition, the calibrated features are extracted from the calibrated images. The difference features between the original and calibrated images are used for training and classifying. Three different image libraries are used to detect the five kinds of typical JPEG steganography schemes. Experimental results show that, in comparison to the several effective steganalysis, the proposed scheme improves the detection accuracy on some JPEG-based steganography schemes, including outguess, Steghide and MB1.
Junli Wang,Jinyang Li,Shuai Lei,Zhigui Ren,Yayin He 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.2
To explore the geometric nonlinearity of high-aspect-ratio wing due to large deformation, the aerodynamics were solved by Navier–Stokes governing equation based on the loose coupling method of CFD/CSD. Considering the large displacement stiffness matrix of wing structure, the Newton–Raphson method is used to solve the nonlinear elastic deformation of the structure. A geometrically nonlinear static aeroelastic coupling calculation program is developed. During the coupling process, an improved elastic approximation method was used to update the aerodynamic mesh, and the data exchange on the coupling interface was realized by a fixed-volume interpolation method. The reliability of the proposed method was verified by HIRENASD wing model. Finally, the effects of geometric nonlinear static aeroelasticity on longitudinal aerodynamic characteristics and stability of swept wing with high aspect ratio at different angles of attack are studied using this method. The results show that the lift direction of a high-aspect-ratio wing is significantly deformed under the influence of aerodynamic loads. The effective angle of attack of the wing decreases with the whole deformation, and the degree of decrease increases from the root to the tip. The significant flexural and torsional deformation will change the lift coefficient and drag coefficient of the wing and reduce the margin of the static stability of the wing.
High‑Efficiency Inhibition of Gravity Segregation in Al–Bi Immiscible Alloys by Adding Lanthanum
Peng Jia,Jinyang Zhang,Haoran Geng,Xinying Teng,Degang Zhao,Zhongxi Yang,Yi Wang,Song Hu,Jun Xiang,Xun Hu 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.6
The inhibition of gravity segregation has been a long-standing challenge in fabrication and applications of homogeneousimmiscible alloys. Therefore, the effect of rare-earth La on the gravity segregation of Al–Bi immiscible alloys was investigatedto understand the homogenization mechanism. The results showed that the addition of La can completely suppress thegravity segregation. This is attributed to the nucleation of Bi-rich liquid phase on the in-situ produced LaBi2phase and thechange of the shape of LaBi2@Bi droplets. In addition, a novel strategy is developed to prepare the homogeneous immisciblealloys through the addition of rare-earth elements. This strategy not only is applicable to other immiscible alloys, but alsois conducive to finding more elements to suppress the gravity segregation. This study provided a useful reference for thefabrication of the homogeneous immiscible alloys.
Test Study on the Air Permeability of Remolded Q3 Malan Loess
Jia Liu,Xi’an Li,Zeze Guo,Quan Xue,Li Wang,Jinyang Liu 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.8
Gas permeability is an important parameter in the determination of the pore structure characteristics of loess, especially in engineering fields such as earthwork and landfill cover treatment. With an improved ZC-2015 air permeameter, the air permeability (ka) testing under different water contents (w), dry densities (ρd) and wetting paths was conducted on remolded Q3 Malan loess from the Chanhe River area in Xi’an, Shaanxi, China. The results indicate that the ka of the remolded loess decreased rapidly as ρd increased and exhibited a relatively complex pattern as w increased. When w was less than the plastic limit (wp) and ρdwas relatively low (1.35 g·cm−3, 1.45 g·cm−3), ka decreased as we increased. When ρd reached a certain value (1.50 g·cm−3, 1.65 g·cm−3), the ka–we curve exhibited a notable turning point. When ρd continued to increase 1.70 g·cm−3, ka decreased as we increased. The results of microscopic analysis, suggested that under the action of different water content and compaction, levels of aggregates and pore structures were formed. A Poulsen model was used to predict the ka and the test results were in relatively coincident with the calculation results, demonstrating that the Poulsen model is applicable.
Xu Qilin,Liu Ji Ming,Yao Hongmiao,Zhao Jinyang,Wang Zhikuo,Liu Junli,Zhou Jiadi,Yu Zhiqun,Su Weike 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.10
In this paper, the kinetics of acylation reaction of o-phenylenediamine/p-phenylenediamine and benzoic anhydride were determined in microreactors, respectively. A kinetic model was established, all kinetic parameters including reaction orders, reaction rate constants, pre-exponential factors, and activation energies were acquired. Validation experiments showed experimental data fit well with calculated data at different reactant concentrations and residence times. The comparisons of the reaction rate constants and activation energies were summarized to show the difference of chemical reactivities of phenylenediamines. According to the calculation of the kinetic model, the optimized reaction conditions were listed to meet the monoacylation selectivity equal to 97.0%.