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Boosting Adversarial Training with Learnable Distribution

Computers, Materials & Continua 2024年第3期78卷 3247-3265页

作者： Kai Chen Jinwei Wang James Msughter Adeke Guangjie Liu Yuewei Dai School of Electronics and Information Engineering Nanjing University of Information Science and TechnologyNanjing210044China Key Laboratory of Intelligent Support Technology for Complex Environments Ministry of EducationNanjing210044China School of Computer and Software Nanjing University of Information Science and TechnologyNanjing210044China Nanjing Center for Applied Mathematics Nanjing211135China

In recent years,various adversarial defense methods have been proposed to improve the robustness of deep neural *** training is one of the most potent methods to defend against adversarial ***,the difference in the feature space between natural and adversarial examples hinders the accuracy and robustness of the model in adversarial *** paper proposes a learnable distribution adversarial training method,aiming to construct the same distribution for training data utilizing the Gaussian mixture *** distribution centroid is built to classify samples and constrain the distribution of the sample *** natural and adversarial examples are pushed to the same distribution centroid to improve the accuracy and robustness of the *** proposed method generates adversarial examples to close the distribution gap between the natural and adversarial examples through an attack algorithm explicitly designed for adversarial *** algorithm gradually increases the accuracy and robustness of the model by scaling ***,the proposed method outputs the predicted labels and the distance between the sample and the distribution *** distribution characteristics of the samples can be utilized to detect adversarial cases that can potentially evade the model *** effectiveness of the proposed method is demonstrated through comprehensive experiments.

关键词： Adversarial training feature space learnable distribution distribution centroid

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MD-AVB: A Multi-Manifold Based Available Bandwidth Prediction Algorithm

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Tsinghua science and Technology 2020年第1期25卷 140-148页

作者： Pei Zhang Changqing An Zhanfeng Wang Fengyuan Ma institute of Network Technology Beijing University of Posts and TelecommunicationsBeijing 100876China institute for Network sciences and Cyberspace Tsinghua UniversityBeijing 100084China School of Computer science and Engineering Southeast UniversityNanjing 211189China

The performance of Internet applications is heavily affected by the end-to-end available bandwidth. Thus,it is very important to examine how to accurately predict the available Internet bandwidth. A number of available bandwidth prediction algorithms have been proposed to date, but none of the existing solutions are able to achieve a high level of accuracy. In this paper, a Multi-manifold based Available Bandwidth prediction algorithm(MD-AVB)is proposed, based on the observation that the available bandwidth space on the Internet is multi-manifold and asymmetrical. In the proposed algorithm, the available bandwidth space is divided into multiple lower-dimensional domains iteratively, and each domain is embedded separately to predict the available bandwidth. Experiments on HP S^3 datasets demonstrate that the proposed algorithm is more accurate than existing approaches.

关键词： available bandwidth space performance prediction multi-manifold asymmetry

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A pilot study of catching high-z GRBs and exploring circumburst environment in the forthcoming SVOM era

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Research in Astronomy and Astrophysics 2020年第8期20卷 211-216页

作者： Jing Wang Yu-Lei Qiu Jian-Yan Wei Guangxi Key Laboratory for Relativistic Astrophysics School of Physical Science and TechnologyGuangxi UniversityNanning 530004China Key Laboratory of space Astronomy and Technology National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and space science University of Chinese Academy of SciencesBeijing 100049China

Rapid spectroscopy of GRB afterglows is an important and hard *** on the archival XSGRB spectral database,we here perform a pilot study on the afterglow's spectroscopy in the forthcoming SVOM era in two ***,our simulation indicates that the color acquired from the SVOM/VT blue and red channels is effective in discriminating between low-z(z≤3)and distant GRB candidates until z^***,by doubling the sample size,we find that the previously proposed global photoionization response of the circumburst gas to the prompt emission(i.e.,the CIV/CII-L(iso)/E2peak relationship)is roughly *** the confirmation is dissatisfactory at the large L(iso)/E2peak *** believe that this issue can be further addressed in the SVOM era by a larger spectroscopy sample,thanks to its capability of rapid identification of optical candidates of afterglow and its anti-solar pointing strategy.

关键词： gamma ray bursts:general techniques:photometric techniques:spectroscopic methods:statistical

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A high-contrast imaging coronagraph for segmented-mirror large aperture telescopes using a spatial light modulator

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Astronomical Techniques and Instruments 2024年第3期1卷 166-170页

作者： Jiangpei Dou Huanyu Dong Nanjing institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing 210042China CAS Key Laboratory of Astronomical Optics&Technology Nanjing Institute of Astronomical Optics&TechnologyNanjing 210042China University of Chinese Academy of sciences Beijing 100049China

The primary mirrors of current and future large telescopes always employ a segmented mirror *** small but non-negligible gaps between neighboring segments cause additional diffraction,which restricts the performance of high-contrast *** solve this problem,we propose a coronagraph system based on a single liquid crystal spatial light modulator(SLM).This spatial light modulator is used for amplitude apodization,and its feasibility and potential performance are demonstrated using a laboratory setup using the stochastic parallel gradient descent(SPGD)algorithm to control the spatial light modulator,which is based on point spread function(PSF)sensing and evaluation and optimized for maximum contrast in the discovery working area as a merit *** system delivers a contrast in the order of 10−6,and shows excellent potential to be used in current and future large aperture telescopes,both on the ground and in space.

关键词： Liquid crystal spatial light modulator Amplitude apodized pupil Large aperture telescopes

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Research and development on hypervelocity impact protection using Whipple shield:An overview

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Defence Technology（防务技术） 2021年第6期17卷 1864-1886页

作者： Ken Wen Xiao-wei Chen Yong-gang Lu State Key Laboratory of Explosion science and Technology Beijing Institute of TechnologyBeijing100081China institute of Systems Engineering China Academy of Engineering PhysicsMianyangSichuan621999China

Whipple shield,a dual-wall system,as well as its improved structures,is widely applied to defend the hypervelocity impact of space debris(projectile).This paper reviews the studies about the mechanism and process of protection against hypervelocity impacts using Whipple ***-based experiment and numerical simulation for hypervelocity impact and protection are introduced *** steps of the Whipple shield protection are discussed in order,including the interaction between the projectile and bumper,the movement and diffusion of the debris cloud,and the interaction between the debris cloud and rear *** improvements of the protection performance focusing on these three steps are *** works in the last decade are mentioned *** prospects and suggestions for future studies are put forward.

关键词： space debris Hypervelocity impact Debris cloud Whipple shield Ballistic limit

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Review on film coolingofliquidrocketengines

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Propulsion and Power Research 2018年第1期7卷 1-18页

作者： S.R.Shine S.Shri Nidhi Department of Aerospace Engineering Indian Institute of Space Science and TechnologyThiruvananthapuram 695547India

Film cooling in combination with regenerative cooling is presently considered as an efficient method to guarantee safe operation of liquid rocket engines having higher heat flux densities for long *** paper aims to bring all the research carried out in the field of liquid rocket engine film cooling since *** analytical and numerical procedure followed,experimental facilities and measurements made and major inferences drawn are reviewed in detail,and compared where ever *** has been made through a discussion of the analyses methodologies and the factors that influence film cooling *** effort has also been made to determine the status of the research,pointing out critical gaps,which are still to be explained and addressed by future generations.

关键词： Heat transfer Liquid rocketthrust chamber Film cooling Cooling effectiveness

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Tomographic SAR imaging with large elevation aperture: a P-band small UAV demonstration

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science China(Information sciences) 2022年第3期65卷 211-224页

作者： Tao ZENG Minkun LIU Yan WANG Zegang DING Linghao LI Zhen WANG Yangkai WEI Jianping WANG Radar Research Lab School of Information and Electronics Beijing Institute of Technology beijing institute of Technology Chongqing Innovation Center Yangtze Delta Region Academy of beijing institute of Technology Faculty of Electrical Engineering Mathematics and Computer Science (EEMCS) Delft University of Technology

Elevation resolution is an important indicator in tomographic SAR imaging as it represents the ability to discriminate closed targets in elevation. In general, the elevation resolution is proportional to the length of the elevation aperture. However, as the elevation aperture increases, the geometric consistency of the image will undesirably deteriorate and hence fails the image coregistration approach required by the traditional super-resolution tomographic imaging. In this paper, a new super-resolution tomographic imaging method is proposed to overcome the inconsistency problem caused by the large elevation aperture. The core strategy is to get rid of two-dimensional image coregistration by applying a three-dimensional(3 D) back projection like imaging manner: the 3 D space is firstly divided into a 3 D imaging grid, each of which is individually imaged via compressive sensing for super-resolution. The effectiveness of the proposed approach is evaluated by both computer simulations and real P-band UAV SAR data.

关键词： UAV SAR tomography large elevation aperture super-resolution P-band

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Theoretical predictions and experimental verification on the phase stability of enthalpy-stabilized HE TMREB_(2)s

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Journal of Materials science & Technology 2022年第26期121卷 154-162页

作者： Ze Zhang Shizhen Zhu Fu-Zhi Dai Huimin Xiang Yanbo Liu Ling Liu Zhuang Ma Shijiang Wu Fei Liu Kuang Sun Yanchun Zhou School of Materials science and Engineering Beijing Institute of TechnologyBeijing 100081China science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials and Processing TechnologyBeijing 100076China National Key Laboratory of science and Technology on Materials Under Shock and Impact Beijing 100081China beijing institute of Technology Chongqing Innovation Center Chongqing 401120China Yangtze Delta Region Academy of beijing institute of Technology Jiaxing 314019China Zibo Firststar New Material Incorporated Co. Ltd.Zibo 255000China Shanghai Chenhua science and Technology Corporation Ltd. Shanghai 201804China

Transition metal diborides(TMB_(2)s)are the materials of choice in extreme environments due to their excellent thermal and chemical ***,the degradation of oxidation resistance of TMB_(2)s at elevated temperature still hinders their *** cope with this challenge,it is effective to incorporate rare earth elements to form high-entropy transition and rare-earth metal diborides(HE TMREBs).To obtain thermodynamically stable single-phase structures for HE TMREB_(2)s,a“16×16 mixed enthalpy matrix”is constructed using first-principles calculations to predict the single-phase formation ability of120 two-component diborides(TCBs).Through the use of the“16×16 mixed enthalpy matrix”of TCBs,specific combinations of TMB_(2)s and REB_(2)s that are most likely to form single-phase HE TMREB_(2)s are ***,based on the energy distribution of the local mixing enthalpies of all possible configurations,the enthalpy and entropy descriptors of HE TMREB_(2)s(RE=Sc,Lu,Tm,Er,Ho and Dy)are *** is found that the mixing enthalpy plays a critical role in the stability of the single-phase HE TMREB_(2)s,i.e.,HE TMREB_(2)s are enthalpy-stabilized *** experimental results further confirm that enthalpy dominates the thermodynamic domain and drives the stability of REB_(2)s in HE TMREB_(2)*** study validates that enthalpy-stabilized HE TMREB_(2)s can further expand the compositional space of ultrahigh temperature ceramics(UHTCs)and is expected to further improve the oxidation resistance and high temperature properties of UHTCs.

关键词： High-entropy ceramics Ultrahigh temperature ceramics First-principles calculation Mixing enthalpy Transition and rare earth metal diborides

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Effect of chromium interlayer thickness on interfacial thermal conductance across copper/diamond interface

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international Journal of Minerals,Metallurgy and Materials 2022年第11期29卷 2020-2031页

作者： Xiaoyan Liu Fangyuan Sun Wei Wang Jie Zhao Luhua Wang Zhanxun Che Guangzhu Bai Xitao Wang Jinguo Wang Moon JKim Hailong Zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China beijing institute of Structure and Environment Engineering Beijing 100076China Department of Materials science and Engineering University of Texas at DallasRichardsonTX 75080USA institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China Shandong Provincial Key Laboratory for High Strength Lightweight Metallic Materials Advanced Materials InstituteQilu University of Technology(Shandong Academy of Sciences)Jinan 250014China Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China

The thermal conductivity of diamond particles reinforced copper matrix composite as an attractive thermal management material is significantly lowered by the non-wetting *** paper investigates the heat transport behavior between a 200-nm Cu layer and a single-crystalline diamond substrate inserted by a chromium(Cr)interlayer having a series of thicknesses from 150 nm down to 5 *** purpose is to detect the impact of the modifying interlayer thickness on the interfacial thermal conductance(h)between Cu and *** time-domain thermoreflectance measurements suggest that the introduction of Cr interlayer dramatically improves the h between Cu and diamond owing to the enhanced interfacial adhesion and bridged dissimilar phonon states between Cu and *** h value exhibits a decreasing trend as the Cr interlayer becomes thicker because of the increase in thermal resistance of Cr *** high h values are observed for the Cr interlayer thicknesses below 21 nm since phononic transport channel dominates the thermal conduction in the ultrathin Cr *** findings provide a way to tune the thermal conduction across the metal/nonmetal heterogeneous interface,which plays a pivotal role in designing materials and devices for thermal management applications.

关键词： sputtering diamond metal/nonmetal interface interfacial thermal conductance time-domain thermoreflectance

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Sedimentary elements,evolutions and controlling factors of the Miocene channel system:a case study of the deep-water Taranaki Basin in New Zealand

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Acta Oceanologica Sinica 2023年第11期42卷 44-58页

作者： Guangxu Wang Wei Wu Changsong Lin Quan Li Xiaoming Zhao Yongsheng Zhou Weiqing Liu Shiqin Liang institute of Resources and Environment Henan Polytechnic UniversityJiaozuo 454003China School of Ocean science China University of GeoscienceBeijing 100083China institute of Exploration Technology CNOOC International Ltd.Beijing 100028China School of Geoscience and Technology Southwest Petroleum UniversityChengdu 610500China

Deep-water channel systems are important petroleum reservoirs,and many have been discovered *** deep-water channel sedimentary elements and evolution is helpful for deep-sea petroleum exploration and *** on high-resolution 3D seismic data,the Miocene channel system in the deep-water Taranaki Basin,New Zealand,was analyzed by using seismic interpretation techniques such as interlayer attribute extraction and strata *** channel system was divided into five composite channels(CC-I to CC-V)according to four secondary level channel boundaries,and sedimentary elements such as channels,slump deposits,inner levees,mass transport deposits,and hemipelagic drape deposits were identified in the channel *** morphological characteristics of several composite channels exhibited stark variances,and the overall morphology of the composite channels changed from relatively straight to highly sinuous to relatively *** evolution of the composite channels involved a gradual and repeated process of erosion and filling,and the composite channels could be divided into three evolutionary stages:initial erosion-filling,later erosion-filling(multistage),and channel *** middle Miocene channel system may have formed as a consequence of combined regional tectonic activity and global climatic change,and its intricate morphological alterations may have been influenced by the channel's ability to self-regulate and gravity flow *** studying the sedimentary evolution of a large-scale deep-water channel system in the Taranaki Basin during the Oligocene-Miocene,which transitioned from a passive margin to plate convergence,it can be understood how tectonic activity affected the channel and can also provide a theoretical reference for the evolution of the deepwater channels in areas with similar tectonic conversion environments around the world.

关键词： deep-water channel system channel geomorphology sedimentary evolution climate and region tectonic activities deep-water Taranaki Basin

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