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Study on damage mechanism and damage distribution of the rear plate under impact of debris cloud

Defence Technology（防务技术） 2024年第5期35卷 151-167页

作者： Chenyang wu Xiaowei Chen Qiguang He State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyHaidian DistrictBeijing 100081China School of Mechatronical Engineering Beijing Institute of TechnologyHaidian DistrictBeijing 100081China Institute of Fluid Physics China Academy of Engineering PhysicsMianyang 621900SichuanChina

The debris cloud generated by the hypervelocity impact(HVI)of orbiting space debris directly threatens the spacecraft.A full understanding of the damage mechanism of rear plate is useful for the optimal design of protective *** this study,the hypervelocity yaw impact of a cylindrical aluminum projectile on a double-layer aluminum plate is simulated by the FE-SPH adaptive method,and the damage process of the rear plate under the impact of the debris cloud is analyzed based on the debris cloud *** damage process can be divided into the main impact stage of the debris cloud and the structural response of the rear *** main impact stage lasts a short time and is the basis of the rear plate *** the stage of structure response,the continuous deformation and inertial motion of the rear plate dominate the perforation of the rear *** further analyze the damage mechanism and damage distribution characteristics of the rear plate in ***,the connection between velocity space and position space of the debris cloud is established,which promotes the general analysis of the damage law of debris *** on the relationship,the features of typical damage areas are identified by the localized fine *** the cumulative effect and structural response cause the perforation of rear plate;in the non-perforated area,cratering by the impact of hazardous fragments is the main damage mode of the rear plate.

关键词： Damage of rear plate Debris cloud Secondary impact Hypervelocity yaw impact FE-SPH adaptive method

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Active flutter suppression of nonlinear fin-actuator system via inverse system and immersion and invariance method

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Chinese Journal of Aeronautics 2024年第4期37卷 343-362页

作者： Jin LU Zhigang wu Chao YANG Chinese Aeronautical Establishment Beijing 100029China School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China

Structural nonlinearities such as freeplay will affect the stability and even flight safety of the fin-actuator *** is a lack of a practical method for designing Active Flutter Suppression (AFS) control laws for nonlinear fin-actuator systems.A design method for the AFS controller of the nonlinear all-movable fin-electromechanical actuator system is established by combining the inverse system and the Immersion and Invariance (I&I) ***,the composite control law combining the inverse system principle and internal model control is used to offset the nonlinearity and dynamics of the actuator,so that its driving torque can follow the ideal ***,the ideal torque of the actuator is designed employing the I&I *** unfavorable oscillation of the fin is suppressed by making the output torque of the actuator track the ideal *** simulation results reveal that the proposed AFS method can increase the flutter speed of the nonlinear finactuator system with freeplay,and a set of controller parameters is also applicable for wider freeplay within a certain *** power required for the actuator does not exceed the power that can be provided by the commonly used aviation *** method can also resist a certain level of noise and external disturbance.

关键词： Aeroelasticity Active flutter suppression Fin-actuator system Freeplay Inverse system Immersion and invariance

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一种快校正磁铁电源设计与仿真

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强激光与粒子束 2024年第2期36卷 105-111页

作者：王东兴黄毛毛武万锋深圳综合粒子设施研究院广东深圳518107

快校正磁铁电源是光源和加速器中重要的设备。随着光源性能的提升,加速器对快校正磁铁电源的性能也提出了更高要求。为满足快校正磁铁电源性能要求和简化设计过程,开展了快校正磁铁电源控制策略和仿真研究,并提出了PI控制加二阶相位补... 详细信息

快校正磁铁电源是光源和加速器中重要的设备。随着光源性能的提升,加速器对快校正磁铁电源的性能也提出了更高要求。为满足快校正磁铁电源性能要求和简化设计过程,开展了快校正磁铁电源控制策略和仿真研究,并提出了PI控制加二阶相位补偿的方法作为快校正磁铁电源的控制策略;利用伯德图设计快校正磁铁电源的相位补偿参数,以提高电源系统相位裕量。该方法不仅保证了电源系统工作在深度负反馈状态,而且简化了相位补偿的参数计算过程。为了验证控制策略的正确性和有效性,提出用压控电压源代替开关器件开展电源性能仿真的方法。仿真结果验证了上述控制策略的可行性和有效性,同时验证了上述仿真方法的有效性和高效性。

关键词：快校正磁铁电源直线加速器 PI控制相位补偿电源仿真

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L vector spaces and L fields

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Science China Mathematics 2024年第10期67卷 2195-2216页

作者： Yinhe Peng Liuzhen wu Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China

We construct in ZFC(the Zermelo-Fraenkel system with choice) an L topological vector space—a topological vector space that is an L space—and an L field—a topological field that is an L space. This generalizes earli... 详细信息

关键词： minimal walk topological vector space topological eld L space L vector space L eld

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Topological Dirac-vortex microcavity laser for robust on-chip optoelectronics

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Light(Science & Applications) 2024年第4期13卷 591-592页

作者： Yuanpeng wu Zetian Mi Department of Electrical Engineering and Computer Science University of Michigan1301 Beal AvenueAnn ArborMI 48109USA

Dirac-vortex microcavity laser based on InAs/InGaAs quantum dots have been experimentally realized on silicon *** topological laser features a large spectral range and high robustness against variations such as cavity... 详细信息

关键词： laser optoelectronics cavity

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Matched Volterra reduced-order model for an airfoil undergoing periodic translation

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Chinese Journal of Aeronautics 2024年第1期37卷 19-23页

作者： Lianrui NIE Ziniu wu Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China

This paper is devoted to application of the Reduced-Order Model(ROM)based on Volterra series to prediction of lift and drag forces due to airfoil periodic translation in transonic flow *** there is large amplitude oscillation of the relative Mach number,as appeared in helicopter rotor movement in forward flight,the conventional Volterra ROM is found to be *** cover such applications,a matched Volterra ROM,inspired from previous multistep nonlinear indicial response method based on Duhamel integration,is thus considered,in which the step motions are defined inside a number of equal intervals with both positive and negative step motions to match the airfoil forward and backward movement,and the kernel functions are constructed independently at each *** shows that,at least for the translation movement considered,this matched Volterra ROM greatly improves the accuracy of ***,the matched Volterra ROM,with the total number of step motions and thus the computational cost close to those of the conventional Volterra ROM method,has the additional advantage that the same set of kernels can match various translation motions with different starting conditions so the kernels can be predesigned without knowing the specific motion of airfoil.

关键词： Airfoil periodic translation Lift and drag Reduced-order model Transonic flow Unsteady flow

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A novel Ag/ZnO core-shell structure for efficient sterilization synergizing antibiotics and subsequently removing residuals

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Green Energy & Environment 2024年第2期9卷 366-377页

作者： Wenmei Han Wenli Wang Jie Fan Runping Jia Xuchun Yang Tong wu Qingsheng wu School of Chemical Science and Engineering Shanghai Key Laboratory of Chemical Assessment and SustainabilityInstitute of Advanced StudyTongji UniversityShanghai200092China College of Textile and Clothing Engineering China National Textile and Apparel Council Key Laboratory of Natural DyesSoochow UniversitySuzhou215123China Department of Urology Shanghai First People’s HospitalSchool of MedicineShanghai Jiaotong UniversityShanghai200080China School of Materials Science and Engineering Shanghai Institute of TechnologyShanghai201418China

The massive use of antibiotics has led to the aggravation of bacterial resistance and also brought environmental pollution *** poses a great threat to human *** the dosage of antibiotics is reduced by increasing its bactericidal performance,the emergence of drug resistance is certainly delayed,so that there's not enough time for developing drug resistance during ***,we selected typical representative materials of metal Ag and semiconductor ZnO nano-bactericides to design and synthesize Ag/ZnO hollow core-shell structures(AZ for short).Antibiotics are grafted on the surface of AZ through rational modification to form a composite sterilization *** research results show that the antibacterial efficiency of the composite system is significantly increased,from the sum(34.7%+22.8%-57.5%)of the antibacterial efficiency of AZ and gentamicin to 80.2%,net synergizes 22.7%,which fully reflects the effect of 1+1>***,the dosage of antibiotics can be drastically reduced in this way,which makes both the possibility of bacterial resistance and medical expenses remarkably ***,residual antibiotics can be degraded under simple illumination using AZ-self as a photocatalyst,which cuts off the path of environmental *** short,such an innovative route has guiding significance for drug resistance.

关键词： Ag/ZnO hollow Core-shell structures Antibiotics Gentamycin Synergistic sterilization Photodegradation

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High-dimensional robust inference for censored linear models

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Science China Mathematics 2024年第4期67卷 891-918页

作者： Jiayu Huang Yuanshan wu School of Mathematics and Statistics Wuhan UniversityWuhan 430072China School of Statistics and Mathematics Zhongnan University of Economics and LawWuhan 430073China

Due to the direct statistical interpretation,censored linear regression offers a valuable complement to the Cox proportional hazards regression in survival *** propose a rank-based high-dimensional inference for censored linear regression without imposing any moment condition on the model *** develop a theory of the high-dimensional U-statistic,circumvent challenges stemming from the non-smoothness of the loss function,and establish the convergence rate of the regularized estimator and the asymptotic normality of the resulting de-biased estimator as well as the consistency of the asymptotic variance *** censoring can be viewed as a way of trimming,it strengthens the robustness of the rank-based high-dimensional inference,particularly for the heavy-tailed model error or the outlier in the presence of the *** evaluate the finite-sample performance of the proposed method via extensive simulation studies and demonstrate its utility by applying it to a subcohort study from The Cancer Genome Atlas(TCGA).

关键词： censoring mechanism heavy-tailed distribution non-smooth loss function outlier rank regression

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Research progresses on cathode materials of aqueous zinc-ion batteries

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Journal of Energy Chemistry 2024年第10期97卷 237-264,I0005页

作者： Zengyuan Fan Jiawei Wang Yunpeng wu Xuedong Yan Dongmei Dai Xing-Long wu Jilin Provincial Science and Technology Innovation Centre of Optical Materials and Chemistry Jilin Provincial International Joint Research Center of Photo-functional Materials and ChemistrySchool of Chemistry and Environmental EngineeringChangchun University of Science and TechnologyChangchun 130022JilinChina PMOE Key Laboratory for UV LightEmitting Materials and Technology School of PhysicsNortheast Normal UniversityChangchun 130024JilinChina Chongqing Research Institute Changchun University of Science and TechnologyChongqing 401135China Institute of Energy Storage and Conversion Technology College of Chemical EngineeringNingbo PolytechnicNingbo 315800ZhejiangChina School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiang 453007HenanChina

Electrochemical energy storage and conversion techniques that exhibit the merits such as high energy density,rapid response kinetics,economical maintenance requirements and expedient installation procedures will hold a pivotal role in the forthcoming energy storage technologies *** recent years,aqueous zinc-ion batteries(AZIBs)have garnered substantial attention as a compelling candidate for large-scale energy storage systems,primarily attributable to their advantageous featu res encompassing cost-effectiveness,environmental sustainability,and robust safety ***,one of the primary factors hindering the further development of AZIBs originates from the challenge of cathode ***,the three mainstream types of mainstream cathode materials,in terms of manganese-based compounds,vanadium-based compounds and Prussian blue analogues,surfer from the dissolution of Mn~(2+),in the low discharge voltage,and the low specific capacity,*** strategies have been developed to compensation the above intrinsic defects for these cathode materials,including the ionic doping,defect engineering,and materials ***,this review first provides a systematic summarization of the zinc storage mechanism in AZIBs,following by the inherent merit and demerit of three kind of cathode materials during zinc storage analyzed from their structure characteristic,and then the recent development of critical strategies towards the intrinsic insufficiency of these cathode *** this review,the methodologies aimed at enhancing the efficacy of manganese-based and vanadium-based compounds are emphasis ***,the article outlines the future prospective directions as well as strategic proposal for cathode materials in AZIBs.

关键词： Aqueous zinc-ion batteries Cathode materials Optimization strategies

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DLP:towards active defense against backdoor attacks with decoupled learning process

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Cybersecurity 2024年第1期7卷 122-134页

作者： Zonghao Ying Bin wu State Key Laboratory of Information Security Institute of Information EngineeringChinese Academy of SciencesBeijingChina School of Cyber Security University of Chinese Academy of SciencesBeijingChina

Deep learning models are well known to be susceptible to backdoor attack,where the attacker only needs to provide a tampered dataset on which the triggers are *** trained on the dataset will passively implant the backdoor,and triggers on the input can mislead the models during *** study shows that the model shows different learning behaviors in clean and poisoned subsets during *** on this observation,we propose a general training pipeline to defend against backdoor attacks *** models can be trained from the unreli-able dataset by decoupling the learning process into three stages,i.e.,supervised learning,active unlearning,and active semi-supervised *** effectiveness of our approach has been shown in numerous experiments across various backdoor attacks and datasets.

关键词： Deep learning Backdoor attack Active defense

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