For deep-space mission design,the gravity of the Sun and the Moon can be first considered and utilized.Their gravity can provide the energy change for launching spacecraft and retrieving spacecraft as well as asteroid...For deep-space mission design,the gravity of the Sun and the Moon can be first considered and utilized.Their gravity can provide the energy change for launching spacecraft and retrieving spacecraft as well as asteroids.Regarding an asteroid retrieval mission,it can lead to the mitigation of asteroid hazards and an easy exploration and exploitation of the asteroid.This paper discusses the application of the Sun-driven lunar swingby sequence for asteroid missions.Characterizing the capacity of this technique is not only interesting in terms of the dynamic insights but also non-trivial for trajectory design.The capacity of a Sun-driven lunar swingby sequence is elucidated in this paper with the help of the“Swingby-Jacobi”graph.The capacity can be represented by a range of the Jacobi integral that encloses around 660 asteroids currently cataloged.To facilitate trajectory design,a database of Sun-perturbed Moon-to-Moon transfers,including multi-revolution cases,is generated and employed.Massive trajectory options for spacecraft launch and asteroid capture can then be explored and optimized.Finally,a number of asteroid flyby,rendezvous,sample-return,and retrieval mission options enabled by the proposed technique are obtained.展开更多
Adversarial examples are hot topics in the field of security in deep learning.The feature,generation methods,attack and defense methods of the adversarial examples are focuses of the current research on adversarial ex...Adversarial examples are hot topics in the field of security in deep learning.The feature,generation methods,attack and defense methods of the adversarial examples are focuses of the current research on adversarial examples.This article explains the key technologies and theories of adversarial examples from the concept of adversarial examples,the occurrences of the adversarial examples,the attacking methods of adversarial examples.This article lists the possible reasons for the adversarial examples.This article also analyzes several typical generation methods of adversarial examples in detail:Limited-memory BFGS(L-BFGS),Fast Gradient Sign Method(FGSM),Basic Iterative Method(BIM),Iterative Least-likely Class Method(LLC),etc.Furthermore,in the perspective of the attack methods and reasons of the adversarial examples,the main defense techniques for the adversarial examples are listed:preprocessing,regularization and adversarial training method,distillation method,etc.,which application scenarios and deficiencies of different defense measures are pointed out.This article further discusses the application of adversarial examples which currently is mainly used in adversarial evaluation and adversarial training.Finally,the overall research direction of the adversarial examples is prospected to completely solve the adversarial attack problem.There are still a lot of practical and theoretical problems that need to be solved.Finding out the characteristics of the adversarial examples,giving a mathematical description of its practical application prospects,exploring the universal method of adversarial example generation and the generation mechanism of the adversarial examples are the main research directions of the adversarial examples in the future.展开更多
文摘For deep-space mission design,the gravity of the Sun and the Moon can be first considered and utilized.Their gravity can provide the energy change for launching spacecraft and retrieving spacecraft as well as asteroids.Regarding an asteroid retrieval mission,it can lead to the mitigation of asteroid hazards and an easy exploration and exploitation of the asteroid.This paper discusses the application of the Sun-driven lunar swingby sequence for asteroid missions.Characterizing the capacity of this technique is not only interesting in terms of the dynamic insights but also non-trivial for trajectory design.The capacity of a Sun-driven lunar swingby sequence is elucidated in this paper with the help of the“Swingby-Jacobi”graph.The capacity can be represented by a range of the Jacobi integral that encloses around 660 asteroids currently cataloged.To facilitate trajectory design,a database of Sun-perturbed Moon-to-Moon transfers,including multi-revolution cases,is generated and employed.Massive trajectory options for spacecraft launch and asteroid capture can then be explored and optimized.Finally,a number of asteroid flyby,rendezvous,sample-return,and retrieval mission options enabled by the proposed technique are obtained.
基金This work is supported by the NSFC[Grant Nos.61772281,61703212]the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)and Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment Technology(CICAEET).
文摘Adversarial examples are hot topics in the field of security in deep learning.The feature,generation methods,attack and defense methods of the adversarial examples are focuses of the current research on adversarial examples.This article explains the key technologies and theories of adversarial examples from the concept of adversarial examples,the occurrences of the adversarial examples,the attacking methods of adversarial examples.This article lists the possible reasons for the adversarial examples.This article also analyzes several typical generation methods of adversarial examples in detail:Limited-memory BFGS(L-BFGS),Fast Gradient Sign Method(FGSM),Basic Iterative Method(BIM),Iterative Least-likely Class Method(LLC),etc.Furthermore,in the perspective of the attack methods and reasons of the adversarial examples,the main defense techniques for the adversarial examples are listed:preprocessing,regularization and adversarial training method,distillation method,etc.,which application scenarios and deficiencies of different defense measures are pointed out.This article further discusses the application of adversarial examples which currently is mainly used in adversarial evaluation and adversarial training.Finally,the overall research direction of the adversarial examples is prospected to completely solve the adversarial attack problem.There are still a lot of practical and theoretical problems that need to be solved.Finding out the characteristics of the adversarial examples,giving a mathematical description of its practical application prospects,exploring the universal method of adversarial example generation and the generation mechanism of the adversarial examples are the main research directions of the adversarial examples in the future.
