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Fuzzy dynamic characteristic model based attitude control of hypersonic vehicle in gliding phase

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science china(Information sciences) 2011年第3期54卷 448-459页

作者： LUO Xiong 1,2 & LI Jiang 1 1 Department of Computer science and technology, key laboratory of Advanced control of Iron and Steel Process (Ministry of Education), University of science and technology beijing, beijing 100083, china 2 National laboratory of space intelligent control, beijing 100190, china Department of Computer science and technology Key Laboratory of Advanced Control of Iron and Steel Process (Ministry of Education) University of Science and Technology Beijing Beijing China National laboratory of space intelligent control Beijing China

The intelligent autonomous control of hypersonic vehicles has aroused great interest from the field of spacecraft. To solve the problem of longitudinal attitude control of hypersonic vehicle in gliding phase, a new intelligent controller is proposed in this paper. This new controller is based on the fuzzy dynamic characteristic modeling method. The fuzzy logic is introduced into the characteristic modeling by dividing the whole restriction range into several subspaces. Simulations show that this modification greatly improves the performance of the original method. With the same whole restriction range the fuzzy dynamic characteristic modeling decreases the time of convergence, and at the same time makes the attitude angle tracing more precise and robust. Since the sub-model is a characteristic model that has stronger adaptiveness than a fixed local model, the number of fuzzy rules is greatly reduced. Our model sharply reduces the complexity in constructing a fuzzy dynamic model. Finally, simulation results are given to show the effectiveness of the proposed approach in dealing with the attitude control problem of hypersonic vehicle in gliding phase.

关键词： hypersonic vehicle gliding attitude control fuzzy dynamic characteristic modeling

Fuzzy tracking control design for hypersonic vehicles via T-S model

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science china(Information sciences) 2011年第3期54卷 521-528页

作者： GAO DaoXiang 1 & SUN ZengQi 2 1 School of technology, beijing Forestry University, beijing 100083, china 2 state key laboratory of intelligent technology and System, Department of Computer science and technology, Tsinghua University, beijing 100084, china School of technology Beijing Forestry University Beijing China state key laboratory of intelligent technology and System Department of Computer Science and Technology Tsinghua University Beijing China

The main focus of this paper is on designing a T-S fuzzy controller for the hypersonic vehicle. The longitudinal dynamics of the vehicle are studied using time-scale decomposition to reduce the complexity of T-S modeling. The dynamic inversion with PI control technique is applied for the slow dynamics to derive the flight path angle command and throttle setting by taking the pilot altitude and velocity command as its inputs. The T-S fuzzy controller is designed for the fast dynamics to derive the elevator deflection to track the flight path angle command. The discrepancy between the T-S model and real vehicle model is considered by using sliding mode control for the system stability. Simulation results are included to show the effectiveness of the controller.

关键词： fuzzy control T-S model sliding mode control hypersonic vehicle

Fusion tracking in color and infrared images using joint sparse representation

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science china(Information sciences) 2012年第3期55卷 590-599页

作者： LIU HuaPing1,2,3 & SUN FuChun1,2,3 1Department of Computer science and technology, Tsinghua University, beijing 100084, china 2state key laboratory of intelligent technology and Systems, beijing 100084, china 3Tsinghua National laboratory for Information science and technology, beijing 100084, china Department of Computer science and technology Tsinghua University Beijing China state key laboratory of intelligent technology and Systems Beijing China Tsinghua National laboratory for Information science and technology Beijing China

Currently sparse signal reconstruction gains considerable interest and is applied in many fields. In this paper, a similarity induced by joint sparse representation is designed to construct the likelihood function of particle filter tracker so that the color visual spectrum and thermal spectrum images can be fused for object tracking. The proposed fusion scheme performs joint sparse representation calculation on both modalities and the resultant tracking results are fused using min operation on the sparse representation coefficients. In addition, a co-learning approach is proposed to update the reference templates of both modality and enhance the tracking robustness. The proposed fusion scheme outperforms state-of-the-art approaches, and its effectiveness is verified using OTCBVS database.

关键词： joint sparse representation fusion tracking color image infrared image

Research on applying physical chaos generator to spacecraft information security

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science china(Technological sciences) 2009年第5期52卷 1463-1470页

作者： ZHAO HePing state key laboratory of Information Security,Graduate University of Chinese Academy of sciences,beijing 100049,china china Academy of space technology,beijing 100094,china state key laboratory of Information Security Graduate University of Chinese Academy of Sciences Beijing China china Academy of space technology Beijing China

The effectiveness of a short-length message extension method based on physical chaos generator was analyzed and the entropy of the extended message was calculated in this *** analysis demon-strated that with the mentioned method the entropy of short-length messages,which are repeatedly used in spacecraft data systems,is obviously increased,and the security of transmission is enhanced as *** paper also presented an improvement of the protocol for secret key agreement presented by *** and *** of depending on characteristics of communication channel,this method takes advantage of the random data produced by physical chaos generator to preset the initial parameters of the procedure on both sides of communication,so that the procedure and quantity of cipher key can be precisely *** method can be used to cipher key management of se-cure communication between long life-span spacecraft and ground system.

关键词： physical chaos generator spacecraft information security message extension cipher key management

Latest progress on interactions between VLF/ELF waves and energetic electrons in the inner magnetosphere

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science china Earth sciences 2010年第3期53卷 317-326页

作者： XIAO FuLiang1,2, ZONG QiuGang3, SU ZhenPeng4, TIAN Tian3 & ZHENG HuiNan4 1 School of Physics and Electronic sciences, Changsha University of science and technology, Changsha 410004, china 2 state key laboratory of space Weather, Chinese Academy of sciences, beijing 100190, china 3 Institute of space Physics and Applied technology, Peking University, beijing 100871, china 4 CAS key Lab for Basic Plasma science, School of Earth and space sciences, University of science and technology of china, Hefei 230026, china School of Physics and Electronic sciences Changsha University of Science and Technology Changsha China state key laboratory of space Weather Chinese Academy of Sciences Beijing China Institute of space Physics and Applied technology Peking University Beijing China CAS key Lab for Basic Plasma science School of Earth and Space Sciences University of Science and Technology of China Hefei China

Interactions between very/extremely low frequency (VLF/ELF) waves and energetic electrons play a fundamental role in dynamics occurring in the inner magnetosphere. Here, we briefly discuss global properties of VLF/ELF waves, along with the variability of the electron radiation belts associated with wave-particle interactions and radial diffusion. We provide cases of electron loss and acceleration as a result of wave-particle interactions primarily due to such waves, and particularly some preliminary results of 3D evolution of phase space density from our currently developing 3D code. We comment on the existing mechanisms responsible for acceleration and loss, and identify several critical issues that need to be addressed. We review latest progress and suggest open questions for future investigation.

关键词： wave-particle interaction VLF/ELF waves energetic electrons acceleration and loss inner magnetosphere

Fuzzy tolerance quotient spaces and fuzzy subsets

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science china(Information sciences) 2010年第4期53卷 704-714页

作者： ZHANG Ling1 & ZHANG Bo2,3,4* 1Computer science & technology College, Anhui University, Anhui 230039, china 2state key laboratory of intelligent technology and Systems, beijing 100084, china 3Tsinghua National laboratory of Information science & technology, beijing 100084, china 4Information science & technology College, Computer science & technology Department, Tsinghua University, beijing 100084, china Computer science & technology College Anhui University Anhui China state key laboratory of intelligent technology and Systems Beijing China Tsinghua National laboratory of Information science & technology Beijing China Information science & technology College Computer Science & Technology Department Tsinghua University Beijing China

The structure and characteristic of fuzzy subsets are discussed by using the concepts of granulation and hierarchy in quotient space theory. First, the equivalence relation based quotient space theory is extended to the fuzzy tolerance relation. Second, the isomorphism and its discriminant of fuzzy tolerance relations are discussed. Finally, by using the fuzzy tolerance relation to define the fuzzy subset, its properties are addressed. The main results are given below: (1) several equivalent statements of fuzzy tolerance relations; (2) the definition of isomorphism of fuzzy tolerance relations; (3) the isomorphic discriminant of fuzzy tolerance relations; (4) the definition and properties of fuzzy subsets based on the fuzzy tolerance relations; and (5) the necessary and sufficient condition of the isomorphism of fuzzy subsets. These results will help us further comprehend the concepts of fuzzy tolerance relations and fuzzy subsets.

关键词： Fuzzy tolerance relation quotient space isomorphism fuzzy subset

Interaction between electromagnetic waves and energetic particles by a realistic density model

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science china(Technological sciences) 2010年第9期53卷 2552-2557页

作者： HE YiHua1,2,CHEN LiangXu1,XIAO FuLiang1 & YANG Chang1 1 School of Physics and Electronic sciences,Changsha University of science and technology,Changsha 410004,china 2 state key laboratory of space Weather,Chinese Academy of sciences,beijing 100190,china School of Physics and Electronic sciences Changsha University of Science and Technology Changsha China state key laboratory of space Weather Chinese Academy of Sciences Beijing China

Using a realistic density model,we present a first study on the interactions between electromagnetic waves and energetic particles in the inner *** calculations show that as the latitude λ increases,the number density ne increases,and resonant frequency range moves to lower pitch *** L-mode/electron and L-mode/proton interactions,the pitch angle diffusion dominates over the momentum *** indicates that L-mode waves are primarily responsible for pitch angle *** R-mode/electron interaction,the momentum diffusion is found to be comparable to the pitch angle diffusion,implying that R-mode waves can play an important role in both pitch angle scattering and stochastic acceleration of *** R-mode/proton interaction,diffusion coefficients locate primarily below pitch angle 60° and increase as kinetic energy increases,suggesting that R-mode waves have potential for pitch angle scattering of highly energetic (~1 MeV) protons but cannot efficiently accelerate protons.

关键词： wave-particle interaction energetic particles resonant frequency pitch angle and momentum diffusion density model

Salient region detection and segmentation for general object recognition and image understanding

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science china(Information sciences) 2011年第12期54卷 2481-2490页

作者： HUANG TieJun 1 , TIAN YongHong 1 , LI Jia 2 & YU HaoNan 11 National Engineering laboratory for Video technology, School of Electrical Engineering and Computer science, Peking University, beijing 100871, china 2 key laboratory of intelligent Information Processing, Institute of Computing technology, Chinese Academy of sciences, beijing 100190, china National Engineering laboratory for Video technology School of Electrical Engineering and Computer Science Peking University Beijing China key laboratory of intelligent Information Processing Institute of Computing Technology Chinese Academy of Sciences Beijing China

General object recognition and image understanding is recognized as a dramatic goal for computer vision and multimedia retrieval. In spite of the great efforts devoted in the last two decades, it still remains an open problem. In this paper, we propose a selective attention-driven model for general image understanding, named GORIUM (general object recognition and image understanding model). The key idea of our model is to discover recurring visual objects by selective attention modeling and pairwise local invariant features matching on a large image set in an unsupervised manner. Towards this end, it can be formulated as a four-layer bottom-up model, i.e., salient region detection, object segmentation, automatic object discovering and visual dictionary construction. By exploiting multi-task learning methods to model visual saliency simultaneously with the bottom-up and top-down factors, the lowest layer can effectively detect salient objects in an image. The second layer exploits a simple yet effective learning approach to generate two complementary maps from several raw saliency maps, which then can be utilized to segment the salient objects precisely from a complex scene. For the third layer, we have also implemented an unsupervised approach to automatically discover general objects from large image set by pairwise matching with local invariant features. Afterwards, visual dictionary construction can be implemented by using many state-of-the-art algorithms and tools available nowadays.

关键词： object recognition image understanding visual saliency salient object segmentation visual dictionary

Dynamic evolution of outer radiation belt electrons driven by superluminous R-X mode waves

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science china(Technological sciences) 2010年第10期53卷 2734-2738页

作者： XIAO FuLiang1,2, CHEN LiangXu1, HE YiHua1 & YANG Chang1 1 School of Physics and Electronic sciences, Changsha University of science and technology, Changsha 410004, china 2 state key laboratory of space Weather, Chinese Academy of sciences, beijing 100190, china School of Physics and Electronic sciences Changsha University of Science and Technology Changsha China state key laboratory of space Weather Chinese Academy of Sciences Beijing China

We present initial results on the temporal evolution of the phase space density (PSD) of the outer radiation belt energetic electrons driven by the superluminous R-X mode waves. We calculate diffusion rates in pitch angle and momentum assuming the standard Gaussian distributions in both wave frequency and wave normal angle at the location L=6.5. We solve a 2D momentum-pitch-angle Fokker-Planck equation using those diffusion rates as inputs. Numerical results show that R-X mode can produce significant acceleration of relativistic electrons around geostationary orbit,supporting previous findings that superluminous waves potentially contribute to dramatic variation in the outer radiation belt electron dynamics.

关键词： wave-particle interaction superluminous R-X waves phase space density evolution radiation belt electrons