检索结果-南通市图书馆

Efficient and secure image authentication with robustness and versatility

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2020年第12期63卷 179-196页

作者： Haixia CHEN Xinyi HUANG wei WU yi MU Fujian Provincial Key Laboratory of Network Security and Cryptology Center for Applied Mathematics of Fujian ProvinceCollege of Mathematics and Informatics Fujian Normal University

Image authentication is the technology of verifying image origin, integrity and authenticity. A rich stream of research on image authentication has shown various trade-off among four favorable features,namely robustness, security, versatility and efficiency. Image data authentication has the highest level of security but provides no robustness/versatility. Image content authentication from robust hashing keeps robust to limited types of operations, and as a result its versatility is not satisfactory. Existing designs of image content authentication from advanced cryptographic primitives achieve robustness, security and versatility, at the cost of low efficiency. In this paper, we present a new design of image authentication with an improved trade-off among the aforementioned features. Our versatile design is robust to a number of predefined image processing operations. Its security can be reduced to q-strong Diffie-Hellman(q-SDH), a complexity problem used by existing cryptographic algorithms. From the aspect of efficiency, the new design has a constant-size authentication overhead( ≤2 kB) and a constant verification time(around 0.05 s). While the time of generating authentication overhead increases linearly with the number of permissible editing operations, it only takes around 0.33 s for 1000 types of permissible operations. We believe the new design will facilitate image applications where trustworthy image editing is required.

关键词： image authentication image processing cryptography bilinear maps

3D flower-like hollow CuS@PANI microspheres with superb X-band electromagnetic wave absorption

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第31期126卷 141-151页

作者： Jia Zhao ying wei yi Zhang Qingguo Zhang College of Chemistry and Materials Engineering Bohai UniversityJinzhou 121013China School of Materials Science and Engineering Henan University of Science and TechnologyLuoyang 471023China

Superior electromagnetic(EM)wave absorption properties in 8.2-12.4 GHz(X-band)can be obtained via the effective combination of polyaniline(PANI)and ***,novel 3D flower-like hollow CuS@PANI microspheres were fabricated by a solvothermal process followed by in-situ *** wave absorption properties of 3D flower-like hollow CuS@PANI microspheres in X-band were systematically studied,indicating the minimum reflection loss(RL_(min))of-71.1 dB and effective absorption bandwidth(EAB)covering 81%of test frequency range were achieved with a thickness of 2.75 *** EM wave absorption properties of 3D flower-like hollow CuS@PANI microspheres were mainly ascribed to outstanding impedance matching characteristic and dielectric loss capability(conduction loss,interfacial polarization loss and dipole polarization loss).Moreover,due to the distinctive flower-like hollow struc-ture of CuS@PANI microspheres,an additional wave-absorbing mechanism was provided by increasing the transmission paths of EM waves.

关键词： Flower-like hollow CuS@PANI microspheres Impedance matching Dielectric loss EM wave absorption

Introduction to the Special Issue on Hybrid Intelligent Methods for Forecasting in Resources and Energy Field

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2023年第2期134卷 763-766页

作者： wei-Chiang Hong yi Liang Department of Information Management Asia Eastern University of Science and TechnologyNew Taipei22061Taiwan School of Management Hebei GEO UniversityShijiazhuang050031China

Precise resources and energy forecasting are important to facilitate the decision-making process in order to achieve higher efficiency and reliability in energy system planning,maintenance,operation,security,and so *** the past decades,many resources and energy forecasting models have been continuously proposed to increase the forecasting accuracy,especially intelligence models(e.g.,artificial neural networks,support vector regression,evolutionary computation models,etc.).Meanwhile,due to the great development of optimization methods(e.g.,quadratic programming method,differential empirical mode method,evolutionary algorithms,etc.),many novel hybrid methods combined with the above-mentioned intelligent-optimization-based methods have also been proposed to achieve satisfactory forecasting accuracy *** is worthwhile to explore the tendency and development of intelligent-optimization-based hybrid methodologies and to enrich their practical performances,particularly for resources and energy forecasting.

关键词： artificial forecasting optimization

Evaluation on cutting performance of novel PDC cutter for pipe jacking machine

在线全文

学校读者我要写书评

暂无评论

Underground Space 2024年第1期14卷 34-52页

作者： Long-Chuan Deng yi-Xiang Yuan Xiao-Zhao Li Qian-wei Zhuang Chi Zhang yi-wei Chen School of Earth Sciences and Engineering Nanjing UniversityNanjingJiangsu 210023China Shanghai Tunnel Engineering Co.Ltd. Shanghai 200232China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhouJiangsu 221116China School of Mechanics and Engineering Science Shanghai UniversityShanghai 200444China

It is inevitable to cut reinforced concrete(RC)appeared in cross passage of city metro by cutting tools when constructing in densely populated *** previous cutters employed to cut RC are insufficient and easily damaged,so a new polycrystalline diamond compact(PDC)cutter is used to solve this *** on the theoretical analysis of cutting mechanism,both circular and tapered PDC cutters with cutting edge angle of 90and negative front rack angle of 10are used to cut *** peeling and breaking patterns of cutting concrete are proposed,the nodular and grainy chips are the preferred modes in cutting steel *** LS-DYNA is employed to investigate the cutting performance in *** simulation results show that the average and peak cutting forces increase with the growth of penetration depth,cutting speed,and roundness,and subsequently the recommended penetration depth less than 1.2 mm is obtained to cut RC due to the existence of steel ***,the linear cutting platform is adopted to investigate the force ability and damage state of PDC *** is concluded that the cutting force increases abruptly and fluctuates heavily when cutting the coarse *** patterns occurred in both numerical and experimental results are generally ***,the steel bar is pulled out and the PDC cutter is damaged at the penetration depth of 0.8 mm,while a good cut occurs at the penetration depth of 0.3 *** tapered PDC cutter with a relatively low cutting force is prone to be broken compared with circular PDC *** is suggested that the circular PDC cutter at the penetration depth of 0.3 mm should be used to cut RC in practical engineering.

关键词： PDC cutter RC Pipe jacking machine Linear cutting tests Damage and wear LS-DYNA

Potassium Transporter KUP7 Is Involved in K^＋ Acquisition and Translocation in Arabidopsis Root under K^＋-Limited Conditions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Molecular Plant 2016年第3期9卷 437-446页

作者： Min Han wei Wu wei-Hua Wu yi Wang State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB) College of Biological Sciences National Plant Gene Research Centre (Beijing) China Agricultural University Beijing 100193 China

Potassium （K^＋） is one of the essential macronutrients for plant growth and development. K^＋ uptake from environment and K^＋ translocation in plants are conducted by K^＋ channels and transporters. In this study, we demonstrated that KT/HAK/KUP transporter KUP7 plays crucial roles in K^＋ uptake and translocation in Arabidopsis root. The kup7 mutant exhibited a sensitive phenotype on Iow-K^＋ medium, whose leaves showed chlorosis symptoms compared with wild-type plants. Loss of function of KUP7 led to a reduction of K^＋ uptake rate and K^＋ content in xylem sap under W-deficient conditions. Thus, the K^＋ content in kup7 shoot was significantly reduced under Iow-K^＋ conditions. Localization analysis revealed that KUP7 was predominantly targeted to the plasma membrane. The complementation assay in yeast suggested that KUP7 could mediate K^＋ transport. In addition, phosphorylation on S80, S719, and S721 was important for KUP7 activity. KUP7 was ubiquitously expressed in many organs/tissues, and showed a higher expression level inArabidopsis root. Together, our data demonstrated that KUP7 is crucial for K^＋ uptake inArabidopsis root and might be also involved in K^＋ transport into xylem sap, affecting K^＋ translocation from root toward shoot, especially under K^＋-Iimited conditions.

关键词： Arabidopsis thaliana K^+ uptake K^+ translocation KUP7 K^+ deficiency

Fractal Dimensions of Fractional Integral of Continuous Functions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2016年第12期32卷 1494-1508页

作者： Yong Shun LIANG wei yi SU Institute of Science Nanjing University of Science and Technology Department of Mathematics Nanjing University

In this paper, we mainly explore fractal dimensions of fractional calculus of continuous functions defined on closed intervals. Riemann-Liouville integral of a continuous function f（x） of order v（v 〉 0） which is written as D-Vf（x） has been proved to still be continuous and bounded. Furthermore, upper box dimension of D-v f（x） is no more than 2 and lower box dimension of D-v f（x） is no less than 1. If f（x） is a Lipshciz function, D-v f（x） also is a Lipshciz function. While f（x） is differentiable on [0, 1], D-v f（x） is differentiable on [0, 1] too. With definition of upper box dimension and further calculation, we get upper bound of upper box dimension of Riemann-Liouville fractional integral of any continuous functions including fractal functions. If a continuous function f（x） satisfying HSlder condition, upper box dimension of Riemann-Liouville fractional integral of f（x） seems no more than upper box dimension of f（x）. Appeal to auxiliary functions, we have proved an important conclusion that upper box dimension of Riemann-Liouville integral of a continuous function satisfying HSlder condition of order v（v 〉 0） is strictly less than 2 - v. Riemann-Liouville fractional derivative of certain continuous functions have been discussed elementary. Fractional dimensions of Weyl-Marchaud fractional derivative of certain continuous functions have been estimated.

关键词： Holder condition fractional calculus fractal dimension bound variation

Two-dimensional Wave Equations with Fractal Boundaries

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2013年第12期29卷 2321-2342页

作者： Lin Tao MA wei yi SU Department of Mathematics Nanjing University College of Mathematical Sciences Guangxi Normal University

This paper focuses on two cases of two-dimensional wave equations with fractal boundaries. The first case is the equation with classical derivative. The formal solution is obtained. And a definition of the solution is given. Then we prove that under certain conditions, the solution is a kind of fractal function, which is continuous, differentiable nowhere in its domain. Next, for specific given initial position and 3 different initial velocities, the graphs of solutions are sketched. By computing the box dimensions of boundaries of cross-sections for solution surfaces, we evaluate the range of box dimension of the vibrating membrane. The second case is the equation with p-type derivative. The corresponding solution is shown and numerical example is given.

关键词： Von Koch type curve p-type derivative two-dimensional wave equation fractal boundary fractal dimension

Normalized Wolfe-Powell-type local minimax method for finding multiple unstable solutions of nonlinear elliptic PDEs

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2023年第10期66卷 2361-2384页

作者： wei Liu Ziqing Xie Wenfan yi Key Laboratory of Computing and Stochastic Mathematics(Ministry of Education) Hunan Normal UniversityChangsha 410081China School of Mathematics Hunan UniversityChangsha 410082China

The local minimax method(LMM)proposed by Li and Zhou(2001,2002)is an efficient method to solve nonlinear elliptic partial differential equations(PDEs)with certain variational structures for multiple *** steepest descent direction and the Armijo-type step-size search rules are adopted in Li and Zhou(2002)and play a significant role in the performance and convergence analysis of traditional *** this paper,a new algorithm framework of the LMMs is established based on general descent directions and two normalized(strong)Wolfe-Powell-type step-size search *** corresponding algorithm framework,named the normalized Wolfe-Powell-type LMM(NWP-LMM),is introduced with its feasibility and global convergence rigorously justified for general descent *** a special case,the global convergence of the NWP-LMM combined with the preconditioned steepest descent(PSD)directions is also ***,it extends the framework of traditional *** addition,conjugate-gradient-type(CG-type)descent directions are utilized to speed up the ***,extensive numerical results for several semilinear elliptic PDEs are reported to profile their multiple unstable solutions and compared with different algorithms in the LMM’s family to indicate the effectiveness and robustness of our *** practice,the NWP-LMM combined with the CG-type direction performs much better than its known LMM companions.

关键词： semilinear elliptic PDE multiple unstable solution local minimax method normalized strong Wolfe-Powell-type search rule conjugate-gradient-type descent direction general descent direction global convergence

Numerical study of free end effect of cylinder with low aspect ratios on vortex induced motion

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2022年第1期34卷 106-115页

作者： Jia-wei He wei-wen Zhao De-cheng Wan yi-qian Wang Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Ocean College Zhejiang UniversityZhoushan316021China School of Mathematical Science Soochow UniversitySuzhou215006China

In this paper,numerical simulation is conducted via our in-house solver,vim-FOAM-SJTU,developed on open-source software,*** around static rigid cylinders and elastically mounted rigid cylinder constrained to free stream with free end are numerically *** significant conclusions are made by analyzing the different results between cases with and without free *** turbulence model is implemented with a shear stress transport-based(SST-based)improved delayed detached eddy simulation(IDDES)approach in the ***,The paper starts with the application of the vim-FOAM-SJTU solver to flow past fixed cylinder with free end at Reynolds number *** numerical results are compared with experimental *** are satisfactory which implies the validity and accuracy of the current computational fluid dynamics(CFD)*** flow visualization in the vicinity of free-end is ***,the solver is utilized to simulate the free end effect associated with the VIM of a cylinder submerged in *** motion responses under different inflow velocities are *** relationship between transverse motion frequency,in-line motion frequency is ***,the effect of the free end on the vortex of the wake field is analyzed by comparing the 3-D vorticity diagrams of the free end *** responses of circular cylinder with or without free end are compared.

关键词： Fluid-structure interaction vim-FOAM-SJTU solver vortex induced motion(VIM) Three-dimensional character