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Athermal scheme based on resonance splitting for silicon-on-insulator microring resonators

Photonics Research 2014年第2期2卷 71-74页

作者： Qingzhong Deng Xinbai Li Zhiping Zhou Huaxiang Yi State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer SciencePeking UniversityBeijing 100871China Xi’an Flight Automatic Control Research Institute Aviation Industries of China(AVIC)Xi’an 710065China

A novel athermal scheme utilizing resonance splitting of a dual-ring structure is *** design and simulation are presented,and a proof of concept structure is optimized to demonstrate an athermal resonator with resonan... 详细信息

关键词： splitting scheme resonance

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Tracking guidance strategy for low-thrust transfer trajectory based on NMPC theory

Tracking guidance strategy for low-thrust transfer trajector...

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Chinese control and Decision Conference, CCDC

作者： Hai-bin Shang Shuai Wang Ting Jin Xiang-yu Huang Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of Education School of Aerospace Engineering Beijing Institute of Technology 100081 China Science and Technology on Space Intelligent Control Laboratory Beijing 100190 China

A tracking guidance scheme based on nonlinear model predictive control is proposed for low-thrust transfer trajectory. According to the optimal nominal transfer trajectory, the NMPC is used to design the predictive model of perturbed orbit. Performance index of receding optimization is established, which can indicate the difference between the nominal trajectory and prediction trajectory. Taking the orbit state of nominal transfer trajectory as the initial value, the optimal control sequence is solved by the sequential quadratic programming algorithm. Meanwhile, in order to eliminate the predictive model error, the accuracy of the next control sequence is improved by the introduction of feedback compensation. Taking earth-mars low-thrust transfer as an example, numerical simulation is used to verify the efficiency of the proposed method.

关键词： Trajectory Optimization Predictive models Orbits Space vehicles Predictive control Accuracy

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A Simulation Model for Airport Runway Capacity Estimation

A Simulation Model for Airport Runway Capacity Estimation

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17th International IEEE Conference on Intelligent Transportation Systems & The Asia-Pacific Council on Systems Engineering Conference 2014

作者： Xiang Zou Peng Cheng Nong Cheng National Key Laboratory of Civil Aircraft Flight Simulation Shanghaiand with the Department of AutomationTsinghua University Department of Automation Tsinghua UniversityBeijingChina Science and Technology of Aircraft Control Laboratory Flight Automatic Control Research Institute

This paper presents a simulation model applied for estimating the capacity of airport's runway *** from most analytical runway capacity estimation models which use mathematical formulas to compute capacity directly and some other programming-intensive simulation models,we utilize a sophisticated discrete event simulation software,Arena,to construct a runway capacity estimation *** model combines arrival's airside phase(final approach) and groundside phase(landing and taxiing) ***'s more,since we have considered several most significant phenomena with effect on the capacity in the model,such as fleet mix,performance,and location of exit way,it can be built into other relevant simulation models to serve as a virtual runway system with enough fidelity and *** the end of this paper,an example for hours' operation in Beijing Capital International Airport demonstrates the estimation made by our model is highly reliable.

关键词： A Simulation Model for Airport Runway Capacity Estimation Model

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A probabilistic spectral graph matching algorithm for robust correspondence between lunar surface images

A probabilistic spectral graph matching algorithm for robust...

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World Congress on Intelligent control and Automation (WCICA)

作者： Xu Yang Chuan-Kai Liu Zhi-Yong Liu Hong Qiao Bao-Feng Wang Zi-Dong Wang State Key Laboratory of Management and Control for Complex Systems Chinese Academy of Sciences Beijing Aerospace Flight Control Center School of Information Science and Technology Donghua University

The correspondence between key points is an important problem in lunar surface image processing, and further lays the foundation for the navigation of a rover and the terrain reconstruction of the lunar surface. However, the problem is still challenging due to the existence of large scale and rotation transformations, reflected view of the same scenery, and different illumination conditions between acquired images as the lunar rover moves forward. Traditional appearance matching algorithms, like SIFT, often fail in handling the above situations. By utilizing the structural cues between points, in this paper we propose a probabilistic spectral graph matching method to tackle the point correspondence problem in lunar surface images acquired by Yutu lunar rover which has been recently transmitted to the moon by China's Chang'e-3 lunar probe. Compared with traditional methods, the proposed method has three advantages. First, the incorporation of the structural information makes the matching more robust with respect to geometric transformations and illumination changes. Second, the assignment between points is interpreted in a probabilistic manner, and thus the best assignments can be easily figured out by ranking the probabilities. Third, the optimization problem can be efficiently approximately solved by spectral decomposition. Simulations on real lunar surface images witness the effectiveness of the proposed method.

关键词： Moon Probabilistic logic Image edge detection Surface treatment Accuracy Optimization Robustness

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Simple Precise Time Signal Delivery over Fiber Link Scheme

Simple Precise Time Signal Delivery over Fiber Link Scheme

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第五届中国卫星导航学术年会

作者： Yitang Dai Zhongle Wu Tianpeng Ren Feifei Yin Kun Xu Jintong Lin Geshi Tang State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Science and Technology on Aerospace Flight Dynamics Laboratory Beijing Aerospace Control Center

The capability of transferring time signal to remote locations with high stability and accuracy for synchronization is crucial for many important occasions,involving very long‐baseline interferometry,coherent radio telescope arrays,modern particle accelerator,and the Deep Space *** widely used satellite methods of time and frequency transfer are unable to preserve the stability delivered by modern timekeeping *** meet these high stability requirements,optical fiber link has been used to transfer frequency and time reference,which however still suffers from mechanical perturbation and temperature variation along the link and degrades the phase stability at the remote *** the past decade,researchers mainly focused on the frequency dissemination,and the transfer stability is now sufficient for most frequency ***,the time signal transfer stability is far below frequency reference,which is typically at the nanosecond accuracy *** propose and demonstrate a stable time signal delivery scheme over fiber link utilizing frequency stabilization *** the scheme,we utilizing the frequency reference to compensate the link‐length variation,and the total transfer delay is kept *** time signal is regenerated at the remote *** fiber link we used in this paper is 10‐km,and the long‐term fiber delay variation is more than 800 *** obtain a time deviation of 40 ps at 1‐s and falling to 2.3 ps at 1000‐s averaging time for time *** time delay resolution of scheme is 1 ps,and the compensation range is in direct proportion with the fiber *** proposed scheme shows a potential ability to precisely transfer time signal and frequency reference simultaneously,which is very suitable for long range time and frequency transfer.

关键词： Time and Frequency Delivery Fiber Link Time Deviation

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Synergistic Damage Mechanic Model for Stiffness Properties of Early Fatigue Damage in Composite Laminates

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Procedia Engineering 2014年 74卷 199-209页

作者： Shen Haojie Yao Weixing Wu Yitao Key Laboratory of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle Nanjing University of Aeronautics and Astronautics Nanjing 210016 China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

In the initial period of the life in the composite laminates, the principal types of damage are diffused ones, such as matrix crack, diffused fiber breaking and local delamination. On account of these diffused damages, a synergistic damage mechanic model was proposed for the stiffness properties. The model included the microcosmic responses of the physical damage and macroscopic performance of the material's stiffness. In micro-level, mesoscopic RVE(representative volume element) model was established to obtain crack opening displacement and crack sliding displacement, which were used to define the damage tensor. In macro- level, through homogenizing the material strain and the surface displacement of the damage, the relationship of the stiffness matrix of unidirectional laminate or laminates in damage statue and damage tense was set up. Due to restriction of NDT (non- destructive testing) technology development, only the constitutive relations of matrix cracks were constructed. The influences of the transverse matrix cracks on the stiffness properties of the laminates [0/±45]s was analyzed with the present model and showed that it is capable to predict the reduction of the stiffness properties resulted from the fatigue diffused damage in the laminates.

关键词： Fatigue diffused damage Synergistic damage mechanic Multiscale Stiffness properties

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On the Shear Stress Parameter of Thin-walled Tubular Specimens under Torsional Loading

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Procedia Engineering 2014年 74卷 191-198页

作者： Tian-Xiang Xia Wei-Xing Yao Jian-Guo Lu Key Laboratory of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle Nanjing University of Aeronautics and Astronautics Nanjing 210016 China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

In the most of existing fatigue life prediction models, the maximum shear stress on a tubular specimen's outer surface is chosen as the shear stress parameter to predict fatigue lifetime for torsional loading. It has been experimentally found that the fatigue lifetime observed under fully reversed torsion is always higher than that under tension-compression for the same equivalent stress level. In this paper, an improved shear stress fatigue damage parameter based on Buch's two-parameter model was proposed. In this parameter, the influences of both shear stress gradient and cyclic strain hardening were taken into account. A serial of tensile-compressive and torsional loading tests were carried out on 2024-T4 aluminum alloy to validate the new parameter. Four σ eq - N f curves were plotted using different shear stress parameters. Compared with other shear stress parameters, the σ eq - N f curve translated from the new parameter made best coincide with the tension-compression S - N curve.

关键词： Multiaxial fatigue Shear stress gradient Supporting effect Cyclic hardening

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Synergistic damage mechanic model for stiffness properties of composite laminates

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Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics 2014年第2期46卷 255-263页

作者： Shen, Haojie Yao, Weixing Wu, Fuqiang Key Lab. of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle Nanjing University of Aeronautics and Astronautics Nanjing 210016 China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

In connection with diffused damage in composite laminates, a synergistic damage mechanic model was pro-posed for the stiffness properties. The model included the microcosmic responses of the physical damage and macroscopic performance of the material's stiffness. In micro-level, mesoscopic RVE (representative volume element) model was established to obtain crack opening displacement and crack sliding displacement, which were used to define the damage tensor. In macro-level, through homogenizing the material strain and the surface displacement of the damage, the relationship of the stiffness matrix of unidirectional laminate or laminates in damage statue and damage tense was set up. As matrix crack for example, the constitutive relations of the laminates with transverse and longitudinal cracks were constructed, respectively. The influences of the transverse matrix cracks on the stiffness properties of the laminates [±θ/904]S were analyzed with the present model and showed that it is capable to predict the reduction of the stiffness properties resulted from the damage in the laminates.

关键词： Stiffness matrix

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Matching suitable feature construction for SAR images based on evolutionary synthesis strategy

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Chinese Journal of Aeronautics 2013年第6期26卷 1488-1497页

作者： Bu Yanlong Tang Geshi Liu Hongfu Pan Liang National Key Laboratory of Science and Technology on Aerospace Flight Dynamics Beijing Aerospace Control Center (BACC) College of Mechatronic Engineering and Automation National University of Defense Technology

In the paper,a set of algorithms to construct synthetic aperture radar（SAR）matching suitable features are frstly proposed based on the evolutionary synthesis *** the process,on the one hand,the indexes of primary matching suitable features（PMSFs）are designed based on the characteristics of image texture,SAR imaging and SAR matching algorithm,which is a process involving expertise;on the other hand,by designing a synthesized operation expression tree based on PMSFs,a much more flexible expression form of synthesized features is built,which greatly expands the construction ***,the genetic algorithm-based optimized searching process is employed to search the synthesized matching suitable feature（SMSF）with the highest effciency,largely improving the optimized searching *** addition,the experimental results of the airborne synthetic aperture radar ortho-images of C-band and P-band show that the SMSFs gained via the algorithms can reflect the matching suitability of SAR images accurately and the matching probabilities of selected matching suitable areas of ortho-images could reach 99±0.5%.

关键词： Integrated navigation Matching suitability Operation expression tree Primary matching suitable feature（PMSF） SAR image Synthesized matching suitable feature（SMSF

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Saturated Scheduling Anti-windup Design: Static Case

Saturated Scheduling Anti-windup Design: Static Case

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第26届中国控制与决策会议

作者： Xiongjun Wu Kun Cai Department of Automation Shanghai Jiao Tong Universityand Key Laboratory of System Control and Information ProcessingMinistry of Education of China The 802 Institute of Shanghai Academy of Space Flight Technology The Eighth Academy of China Aerospace Science and Technology Corporation

A saturation allowed scheduled anti-windup design method is proposed in this paper for the linear systems subject to input saturation. We introduced the scheduled controller design method into the anti-windup scheme, in which a family of controllers are designed. These controllers are activated depending on the response of the system, rather than only considering the worst noise case off-line. Also, the delayed activation scheme is introduced into the scheduled antiwindup mechanism, i.e., the physical actuator is activated when it really need to, and then the most aggressive controller is activated. In this proposed scheme, since the saturation is allowed and no hard constraint is needed to imposed on the controller input, we can makes fuller utilization of the available actuator capacity. The proposed anti-windup scheme provides the system stability and guaranteed peak-to-peak gain. The control strategy is carried out under the scheme of state feedback and the main results are presented in linear matrix inequality forms. The advantage of the proposed saturated allowed scheduling anti-windup scheme against the traditional saturation avoid method is illustrated through a numerical example.

关键词： Actuator saturation,saturated anti-windup,peak-to-peak gain,scheduling control.

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