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Modeling and analysis for material removal and surface roughness in fluid jet polishing of optical glass

Friction 2024年第7期12卷 1548-1563页

作者： Zhongchen CAO Ming WANG Haitao LIU tian HUANG Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education Tianjin UniversityTianjin 300072China School of Engineering The University of WarwickCoventry CV47ALUK

luid jet polishing(FJP)is a non-contact polishing technology that can fabricate free-form optical surfaces with sub-micron-level form accuracy and nano-level surface roughness,especially for hard and brittle *** surface generation model of FJP can be used to guide the determination and optimization of process parameters and is of great significance for understanding the evolution mechanism of surface ***,predictive models for the microscopic topography of polished surfaces are still *** study established a macroscopic surface profile model for predicting 3D material removal characteristics and surface texture by combining the 3D computer fluid dynamics(CFD)simulation model and single-particle erosion mechanism.A fractal theory-based erosion model has been built to calculate the material removal caused by the erosion of a single abrasive particle on the rough surface;thus,it predicts the micro-topography and surface roughness of the polished samples.A series of polishing experiments were conducted to analyze the feasibility and accuracy of the model quantitatively and study the influence mechanism of process parameters on the material removal characteristics and surface *** indicated that the models could well predict material removal and surface *** prediction accuracy of the surface roughness Ra and maximum removal depth is better than 91.6%and 90%,*** is also found that the material removal rate of FJP could reach 0.517 mm3/min,and the surface roughness convergence rate could reach 62.9%.

关键词： fluid jet polishing(FJP) computational fluid dynamics(CFD) material removal mechanism surface roughness theoretical model

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Force-position collaborative optimization of rope-driven snake manipulator for capturing non-cooperative space targets

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Chinese Journal of Aeronautics 2024年第9期37卷 369-384页

作者： Xiaofeng LI Jian tian Cheng WEI Xibin CAO School of Astronautics Harbin Institute of TechnologyHarbin 150001China Beijing Instiuteof Spacecraft System Engineering China Academy of Space TechnolgyBeijing 100094Chia

With the rapid development of space activities,non-cooperative space targets increase swiftly,such as failed satellites and upper stages,threating normal spacecrafts *** there are some problems in the capture process,such as excessive collision and fast tumbling of targets,manipulator with redundant Degrees of Freedom(DOFs)can be used to improve the compliance and therefore solve these *** Rope-Driven Snake Manipulator(RDSM)is a combina-tion of hyper-redundant DOFs and better compliance,and therefore it is suitable for capturing *** this paper,a snake manipulator mechanism is designed,and the complete kinematic model and system dynamic model considering RDSM,target and contact is ***,to obtain the configuration of joint with hyper-redundant DOFs,an improved motion dexterity index is pro-posed as the joint motion optimization ***,the force-position collaborative optimization index is designed to adjust active stiffness,and the impedance control method based on the modified index is used to capture the space ***,the proposed force-position collaborative opti-mization method is verified by virtual prototype *** results demonstrate that based on the proposed method,the collision force is reduced by about 25%compared to normal impe-dance control,showing higher safety.

关键词： Capturing non-cooperative spacetargets Rope-driven snakemanipu-lator Force-position collaborative optimization Redundant degrees of free-dom Active stiffness adjustment

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Topologically protected entanglement switching around exceptional points

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Light(Science & Applications) 2024年第8期13卷 1631-1644页

作者： Zan Tang tian Chen Xing Tang Xiangdong Zhang Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements of Ministry of Education Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic SystemsSchool of PhysicsBeijing Institute of Technology100081 BeijingChina

The robust operation of quantum entanglement states is crucial for applications in quantum information,computing,and communications^(1–3).However,it has always been a great challenge to complete such a task because of decoherence and ***,we propose theoretically and demonstrate experimentally an effective scheme to realize robust operation of quantum entanglement states by designing quadruple degeneracy exceptional *** encircling the exceptional points on two overlapping Riemann energy surfaces,we have realized a chiral switch for entangled states with high *** to the topological protection conferred by the Riemann surface structure,this switching of chirality exhibits strong robustness against perturbations in the encircling ***,we have experimentally validated such a scheme on a quantum walk *** work opens up a new way for the application of non-Hermitian physics in the field of quantum information.

关键词： exceptional quantum Riemann

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Exogeneous metal ions as therapeutic agents in cardiovascular disease and their delivery strategies

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Regenerative Biomaterials 2024年第2期3卷 1-16页

作者： Xiaoqian Hong Geer tian Yang Zhu Tanchen Ren Department of Cardiology of the Second Affliated Hospital and State Key Laboratory of Transvascular Implantation Devices Cardiovascular Key Laboratory of Zhejiang ProvinceZhejiang University School of MedicineHangzhou 310o09China Binjiang Institute of Zhejiang University Hangzhou 310053China MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China

Metal ions participate in many metabolic processes in the human body,and their homeostasis is crucial for *** cardiovascular diseases(CVDs),the equilibriums of metal ions are frequently interrupted,which are related to a variety of disturbances of physiological processes leading to abnormal cardiac *** supplement of metal ions has the potential to work as therapeutic strategies for the treatment of *** with other therapeutic drugs,metal ions possess broad availability,good stability and safety and diverse drug delivery *** delivery strategies of metal ions are important to exert their ther-apeutic effects and reduce the potential toxic side effects for cardiovascular applications,which are also receiving increasing *** local delivery strategies for metal ions based on various biomaterials are constantly being *** this review,we comprehensively summarized the positive roles of metal ions in the treatment of cVDs from three aspects:protecting cells from oxidative stress,inducing angiogenesis,and adjusting the functions of ion *** addition,we introduced the transferability of metal ions in vascular reconstruction and cardiac tissue repair,as well as the currently available engineered strategies for the precise delivery of metal ions,such as integrated with nanoparticles,hydrogels and scaffolds.

关键词： metal ions cardiovascular disease tissue engineering oxidative stress angiogenesis ion channel

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The origins of catalytic selectivity for the electrochemical conversion of carbon dioxide to methanol

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Nano Research 2024年第1期17卷 5-17页

作者： tian Wang Yating Wang Yuhang Li Chunzhong Li Key Laboratory for Ultrafine Materials of Ministry of Education Shanghai Engineering Research Center of Hierarchical NanomaterialsFrontiers Science Center for Materiobiology and Dynamic ChemistrySchool of Materials Science and EngineeringEast China University of Science&TechnologyShanghai 200237China School of Chemical Engineering East China University of Science&TechnologyShanghai 200237China

The electrocatalytic conversion of carbon dioxide(CO_(2))into useful fuels and chemical feedstocks is an emerging route to alleviate global warming and reduce reliance on fossil ***(CH_(3)OH),as one of the most significant and widely used liquid fuels that can be generated by CO_(2)reduction,is essential in the chemical *** this minireview,we unravel the origins of the selective formation of CH_(3)OH via CO_(2)reduction,including catalyst composition designs,local structure modulations,and electrolyte/catalyst interface ***,the remaining challenges and perspectives for the CO_(2)-to-CH_(3)OH reduction are proposed.

关键词： methanol carbon dioxide(CO_(2))reduction reaction electrochemistry electrocatalyst catalyst-electrolyte interface

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Short-time maritime target detection based on polarization scattering characteristics

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Journal of Systems Engineering and Electronics 2024年第1期35卷 55-64页

作者： CHEN Shichao LUO Feng tian Min LYU Wanghan College of Computer and Information Engineering(College of Artificial Intelligence) Nanjing Tech UniversityNanjing 211816China Hangzhou Institute of Technology Xidian UniversityHangzhou 311200China

In this paper,a detection method combining Cameron decomposition based on polarization scattering characteristics in sea clutter background is ***,the Cameron decomposition is exploited to fuse the radar echoes of full polarization channels at the data *** to the artificial material structure on the surface of the target,it can be shown that the non-reciprocity of the target cell is stronger than that of the clutter ***,based on the analysis of the decomposition results,a new feature with scattering geometry characteristics in polarization domain,denoted as Cameron polarization decomposition scattering weight(CPD-SW),is extracted as the test statistic,which can achieve more detailed descriptions of the clutter scattering characteristics utilizing the difference between their scattering ***,the superiority of the proposed CPD-SW detector over traditional detectors in improving detection performance is verified by the IPIX measured dataset,which has strong stability under short-time observation in threshold detection and can also improve the separability of feature space zin anomaly detection.

关键词： sea clutter small target radar detection Cameron decomposition characteristics analysis

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Design of acceleration control schedule for adaptive cycle engine based on direct simulation model

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Chinese Journal of Aeronautics 2024年第6期37卷 307-318页

作者： Keran SONG Linyuan JIA Yuchun CHEN tian TAN School of Power and Energy Northwestern Polytechnical UniversityXi’an 710072China

To design the optimum acceleration control schedule for the Adaptive Cycle Engine(ACE)in the full flight envelope,this paper establishes a direct simulation model of the ACE transient *** this model,geometric parameters are used to replace the component state *** corresponding relationship between geometric parameters and component state parameters is determined by sensitivity *** geometric variables are controlled when the geometric adjustment speed exceeds the limit,and at the same time the corresponding component state parameters are *** gradient optimization algorism is used to optimize the ground acceleration process of ACE,and the control schedule in terms of operating point of compression components and corrected acceleration rate is used as the full-envelope acceleration control schedule based on the similarity *** acceleration control schedules of the triple-bypass mode and the double-bypass mode are designed in this *** acceleration processes under various flight conditions are simulated using the acceleration control *** with the acceleration process with the linear geometric adjustment schedule,the acceleration performance of ACE is improved by the acceleration control schedule,with the impulse of the acceleration process of the triple-bypass mode being increased by 8.7%-12.3% and the impulse of the double-bypass mode acceleration process being increased by 11.8%-14.1%.

关键词： Adaptive Cycle Engine(ACE) Direct simulation method Acceleration Control schedule Full flight envelope

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Effect of geometry simplification and boundary condition specification on flow field and aerodynamic noise in the train head and bogie region of high-speed trains

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第9期25卷 716-731页

作者： Jiawei SHI Yuan HE Jiye ZHANG tian LI State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong UniversityChengdu 610031China Institute of Sound and Vibration Research Faculty of Engineering and Physical SciencesUniversity of SouthamptonSouthampton SO171BJUK

The purpose of this study is to determine a suitable modeling method to make computational fluid dynamics(CFD)simulation more efficient for aeroacoustics optimization of the bogie region of high-speed *** this end,four modeling methods are considered,which involve different geometry simplifications and boundary condition *** corresponding models are named the three-car marshalling model,computational domain shortening model,carbody shortening model,and sub-domain *** the detached eddy simulation(DES)model and Ffowcs Williams-Hawkings(FW-H)equation,the unsteady flow field and far-field noise of the four models are *** evaluate the effect of the different modeling methods,the time-averaged flow field,fluctuating flow field,and far-field noise results of the four models are compared and analyzed in detail with the results of the three-car marshalling model used as basis for *** results show that the flow field results of the bogie region predicted by the four models have relatively high ***,the usage of the non-time varying outlet boundary conditions in the computational domain shortening model and sub-domain model could affect the pressure fluctuation on the upstream carbody *** only the bogie region is used as the source surface,the differences between the far-field noise results of the three simplified models and the three-car marshalling model are all within 1 dB;when the train head is used as the source surface,the results of the carbody shortening model and the three-car marshalling model are more consistent.

关键词： Bogie region Train head Flow field Aerodynamic noise Geometry simplification Boundary conditions

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Adversarial attacks and defenses for digital communication signals identification

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Digital Communications and Networks 2024年第3期10卷 756-764页

作者： Qiao tian Sicheng Zhang Shiwen Mao Yun Lin College of Computer Science and Technology Harbin Engineering UniversityHarbin150001China College of Information and Communication Engineering Harbin Engineering UniversityHarbin150000China Department of Electrical and Computer Engineering Auburn UniversityAuburnAL36849USA

As modern communication technology advances apace,the digital communication signals identification plays an important role in cognitive radio networks,the communication monitoring and management *** has become a promising solution to this problem due to its powerful modeling capability,which has become a consensus in academia and ***,because of the data-dependence and inexplicability of AI models and the openness of electromagnetic space,the physical layer digital communication signals identification model is threatened by adversarial *** examples pose a common threat to AI models,where well-designed and slight perturbations added to input data can cause wrong ***,the security of AI models for the digital communication signals identification is the premise of its efficient and credible *** this paper,we first launch adversarial attacks on the end-to-end AI model for automatic modulation classifi-cation,and then we explain and present three defense mechanisms based on the adversarial *** we present more detailed adversarial indicators to evaluate attack and defense ***,a demonstration verification system is developed to show that the adversarial attack is a real threat to the digital communication signals identification model,which should be paid more attention in future research.

关键词： Digital communication signals identification AI model Adversarial attacks Adversarial defenses Adversarial indicators

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New‑Generation Ferroelectric AlScN Materials

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Nano-Micro Letters 2024年第11期16卷 88-118页

作者： Yalong Zhang Qiuxiang Zhu Bobo tian Chungang Duan Key Laboratory of Polar Materials and Devices Ministry of EducationShanghai Center of Brain‑Inspired Intelligent Materials and DevicesDepartment of ElectronicsEast China Normal UniversityShanghai 200241People’s Republic of China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006ShanxiPeople’s Republic of China

Ferroelectrics have great potential in the field of nonvolatile memory due to programmable polarization states by external electric field in nonvolatile ***,complementary metal oxide semiconductor compatibility and uniformity of ferroelectric performance after size scaling have always been two thorny issues hindering practical application of ferroelectric memory *** emerging ferroelectricity of wurtzite structure nitride offers opportunities to circumvent the *** review covers the mechanism of ferroelectricity and domain dynamics in ferroelectric AlScN *** performance optimization of AlScN films grown by different techniques is summarized and their applications for memories and emerging in-memory computing are ***,the challenges and perspectives regarding the commercial avenue of ferroelectric AlScN are discussed.

关键词： AlScN Ferroelectrics Nonvolatile memory In-memory computing

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