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Adversarial image detection based on the maximum channel of saliency maps

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Optoelectronics Letters 2022年第5期18卷 307-312页

作者： FU Haoran WANG Chundong LIN Hao HAO Qingbo Key Laboratory of Computer Vision and System Tianjin Key Laboratory of Intelligence Computing and Novel Software TechnologyTianjin University of TechnologyTianjin 300384China

Studies have shown that deep neural networks(DNNs) are vulnerable to adversarial examples(AEs) that induce incorrect behaviors. To defend these AEs, various detection techniques have been developed. However, most of them only appear to be effective against specific AEs and cannot generalize well to different AEs. We propose a new detection method against AEs based on the maximum channel of saliency maps(MCSM). The proposed method can alter the structure of adversarial perturbations and preserve the statistical properties of images at the same time. We conduct a complete evaluation on AEs generated by 6 prominent adversarial attacks on the Image Net large scale visual recognition challenge(ILSVRC) 2012 validation sets. The experimental results show that our method performs well on detecting various AEs.

关键词： networks neural maps

Adaptable physics-based super-resolution for electron backscatter diffraction maps

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npj Computational Materials 2022年第1期8卷 2444-2452页

作者： Devendra K.Jangid Neal R.Brodnik Michael G.Goebel Amil Khan SaiSidharth Majeti McLean P.Echlin Samantha H.Daly Tresa M.Pollock B.S.Manjunath Electrical and Computer Engineering University California Santa BarbaraSanta Barbara93106-5050CAUSA Mechanical Engineering University California Santa BarbaraSanta Barbara93106-5050CAUSA Computer Science University California Santa BarbaraSanta Barbara93106-5050CAUSA Materials Department University California Santa BarbaraSanta Barbara93106-5050CAUSA

In computer vision,single-image super-resolution(SISR)has been extensively explored using convolutional neural networks(CNNs)on optical images,but images outside this domain,such as those from scientific experiments,are not well investigated.Experimental data is often gathered using non-optical methods,which alters the metrics for image quality.One such example is electron backscatter diffraction(EBSD),a materials characterization technique that maps crystal arrangement in solid materials,which provides insight into processing,structure,and property relationships.We present a broadly adaptable approach for applying state-of-art SISR networks to generate super-resolved EBSD orientation maps.This approach includes quaternion-based orientation recognition,loss functions that consider rotational effects and crystallographic symmetry,and an inference pipeline to convert network output into established visualization formats for EBSD maps.The ability to generate physically accurate,high-resolution EBSD maps with super-resolution enables high-throughput characterization and broadens the capture capabilities for three-dimensional experimental EBSD datasets.

关键词： maps resolution networks

Constitutive behavior and processing maps of low-expansion GH909 superalloy

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International Journal of Minerals,Metallurgy and Materials 2017年第4期24卷 432-443页

作者： Zhi-hao Yao Shao-cong Wu Jian-xin Dong Qiu-ying Yu Mai-cang Zhang Guang-wei Han School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China The Fu Foundation School of Engineering and Applied Science Columbia University New York 10027 USA Beijing Institute of Aeronautical Materials Beijing 100095 China Department of High Temperature Materials Research Central Iron and Steel Research Institute Beijing 100081 China

The hot deformation behavior of GH909 superalloy was studied systematically using isothermal hot compression tests in a temperature range of 960 to 1040°C and at strain rates from 0.02 to 10 s^(-1) with a height reduction as large as 70%. The relations considering flow stress,temperature,and strain rate were evaluated via power-law,hyperbolic sine,and exponential constitutive equations under different strain conditions. An exponential equation was found to be the most appropriate for process modeling. The processing maps for the superalloy were constructed for strains of 0.2,0.4,0.6,and 0.8 on the basis of the dynamic material model,and a total processing map that includes all the investigated strains was proposed. Metallurgical instabilities in the instability domain mainly located at higher strain rates manifested as adiabatic shear bands and cracking. The stability domain occurred at 960–1040°C and at strain rates less than 0.2 s^(-1); these conditions are recommended for optimum hot working of GH909 superalloy.

关键词： iron-based materials superalloys hot deformation constitutive equations processing maps microstructural evolution

Hopf-flip bifurcation of high dimensional maps and application to vibro-impact systems

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Acta Mechanica Sinica 2005年第4期21卷 402-410页

作者： Jianhua Xie Wangcai Ding E.H. Dowell L. N. Virgin Department of Applied Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China School of Mechanical Engineering Lanzhou Jiaotong UniversityLanzhou 730070 China School of Engineering.Duke University. Durham NC27708-0300USA

This paper addresses the problem of Hopf-flip bifurcation of high dimensional maps. Using the center manifold theorem, we obtain a three dimensional reduced map through the projection technique. The reduced map is further transformed into its normal form whose coefficients are determined by that of the original system. The dynamics of the map near the Hopf-flip bifurcation point is approximated by a so called “time-2τ^2 map” of a planar autonomous differential equation. It is shown that high dimensional maps may result in cycles of period two, tori T^1 （Hopf invariant circles）, tori 2T^1 and tori 2T^2 depending both on how the critical eigenvalues pass the unit circle and on the signs of resonant terms＇ coefficients. A two-degree-of-freedom vibro-impact system is given as an example to show how the procedure of this paper works. It reveals that through Hopf-flip bifurcations, periodic motions may lead directly to different types of motion, such as subharmonic motions, quasi-periodic motions, motions on high dimensional tori and even to chaotic motions depending both on change in direction of the parameter vector and on the nonlinear terms of the first three orders.

关键词： maps Vibro-impact dynamics Hopf-flip bifurcation Torus Chaos

Pattern recognition of messily grown nanowire morphologies applying multi-layer connected self-organized feature maps

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Journal of Materials Science & Technology 2019年第5期35卷 946-956页

作者： Qing Liu Hejun Li Yulei Zhang Zhigang Zhao State Key Laboratory of Solidification Processing Carbon/Carbon Composites Technology Research Center Northwestern Polytechnical University

Multi-layer connected self-organizing feature maps(SOFMs) and the associated learning procedure were proposed to achieve efficient recognition and clustering of messily grown nanowire morphologies. The network is made up by several paratactic 2-D SOFMs with inter-layer connections. By means of Monte Carlo simulations, virtual morphologies were generated to be the training samples. With the unsupervised inner-layer and inter-layer learning, the neural network can cluster different morphologies of messily grown nanowires and build connections between the morphological microstructure and geometrical features of nanowires within. Then, the as-proposed networks were applied on recognitions and quantitative estimations of the experimental morphologies. Results show that the as-trained SOFMs are able to cluster the morphologies and recognize the average length and quantity of the messily grown nanowires within. The inter-layer connections between winning neurons on each competitive layer have significant influence on the relations between the microstructure of the morphology and physical parameters of the nanowires within.

关键词： Artificial neural networks Self-organizing feature maps Monte Carlo simulation Pattern recognition Messily grown nanowire morphologies

A semantic geographical knowledge wiki system mashed up with Google maps

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Science China(Technological Sciences) 2010年第S1期53卷 52-60页

作者： GAO Yong,GAO Song,LI RunQiang & LIU YuInstitute of Remote Sensing and Geographical Information Systems,Peking University,Beijing 100871,China Institute of Remote Sensing and Geographical Information Systems Peking University Beijing China

A wiki system is a typical Web 2.0 application that provides a bi-directional platform for users to collaborate and share much useful information online.Unfortunately,computers cannot well understand the wiki pages in plain text.The user-generated geographical content via wiki systems cannot be manipulated properly and efficiently unless the geographical semantics is explicitly represented.In this paper,a geographical semantic wiki system,Geo-Wiki,is introduced to solve this problem.Geo-Wiki is a semantic geographical knowledge-sharing web system based on geographical ontologies so that computers can parse and storage the multi-source geographical knowledge.Moreover,Geo-Wiki mashed up with map services enriches the representation and helps users to find spatial distribution patterns,and thus can serve geospatial decision-making by customizing the Google maps APIs.

关键词： geo-ontology semantic wiki mashup Google maps

Mitochondrial DNA Polymorphism in Natural Populations of Drosophila albomicans (Ⅰ)——Remarkable mtDNA Polymorphism in the Population of D.albomicans

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Science China Chemistry 1994年第11期37卷 1329-1340页

作者：王文凌发瑶施立明 Laboratory of Cellular and Molecular Evolution Kunming Institute of Zoology Academia SinicaKunming 650223PRC Laboratory of Cellular and Molecular Evolution Kunming Institute of ZoologyAcademia SinicaKunming 650223PRC

The technique of mtDNA restriction fragments length polymorphism(RFLP)was used tosurvey the population structure of D.albomicans.Remarkable mtDNA polymorphism has been observed inD.albomicans populations.A total of 34 nucleomorphs were detected from 82 isofemale lines assayed by only8 restriction enzymes.The cause and the effect of this phenomenon were discussed.As a result,it is sug-gested that a mechanism which maintains mtDNA diversity exists in this fly,and that the high intra-popula-tional polymorphism could numerically conceal the extent of differentiation between populations.In addition,on the base of restriction maps,it was found that the mtDNA molecule of D.albomicans might be impactedby the selection pressure during its evolution process both on the nucleotide composition and on the function-al regions.

关键词： Drosophila albomicans natural population restriction maps mtDNA polymorphism

Deformation behavior and processing maps during isothermal compression of TC21 alloy

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Rare Metals 2017年第2期36卷 86-94页

作者： Jun Gao Miao-Quan Li Ge-Jun Liu Shao-Fei Liu School of Materials Science and Engineering Northwestern Polytechnical UniversityXi'an 710072China

In this study,isothermal compression tests were conducted at a Gleeble-1500 simulator at deformation temperatures ranging from 1073 to 1283 K,strain rates ranging from 0.01 to 5.00 s^（-1）,and height reductions ranging from 20%to 60%.The flow stress and apparent activation energy for deformation and constitutive equation were used to characterize the deformation behavior of TC21 alloy during the isothermal compression.The processing maps combined microstructure observations were established based on dynamic material model（DMM） over a range of strain rates and temperatures.The results show that an initial yield drop is observed above 1203 K or at higher strain rates ranging from 1.00 to 5.00 s^-1,and oscillatory flow curves are presented particularly at a strain rate of 5.00 s^-1.Strain has some influence on the apparent activation energy for deformation during the isothermal compression of TC21 alloy.The Q-values and microstructure observation confirm that dynamic recrystallization（DRX） occurs in the β single-phase region.The constitutive equation during the isothermal compression of TC21 alloy is developed using the Zener-Hollomon parameter in the exponent-type equation.The maximum and minimum relative errors between the calculated and the experimental flow stress are 14.1%and 0.3%,respectively.The peak efficiency of power dissipation at a strain of 0.7 is about 0.51 occurring at a deformation temperature of 1073 K and strain rate of 0.01 s^-1,corresponding to an optimal deformation condition of TC21 alloy.

关键词： TC21 alloy Flow stress Apparent activation energy for deformation Constitutive equation Processing maps

Plasmonic evolution maps for planar metamaterials

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Photonics Research 2021年第1期9卷 73-80页

作者： LIYONG JIANG JIANLI JIANG ZEBIN ZHU GUANGHUI YUAN MING KANG ZE XIANG SHEN Institute of Micro-nano Photonics&Beam Steering School of ScienceNanjing University of Science and TechnologyNanjing 210094China Centre for Disruptive Photonic Technologies The Photonics InstituteSchool of Physical and Mathematical SciencesNanyang Technological UniversitySingapore 637371Singapore College of Physics and Electronic Information Science Tianjin Normal UniversityTianjin 300387China

Understanding the mode’s origin in planar metamaterials is fundamental for related applications in nanophotonics and plasmonics.For complex planar metamaterials,conventional analysis that directly obtains the final charge/current distribution of a mode is usually difficult in helping to understand the mode’s origin.In this paper,we propose a mode evolution method(MEM)with a core analysis tool,i.e.,plasmonic evolution maps(PEMs),to describe the mode evolution in several complementary planar metamaterials with designed plasmonic atoms/molecules.The PEMs could not only clearly explain a mode’s origin,but also reveal the role of a structure’s symmetry in the mode formation process.The MEM with PEMs can work as a simple,efficient,and universal approach for the mode analysis in different kinds of planar metamaterials.

关键词： process. planar maps