中国科学院机构知识库网格系统: 检索

Understanding the acceleration phenomenon via high-resolution differential equations 期刊论文 OAI收割
MATHEMATICAL PROGRAMMING, 2022, 卷号: 195, 期号: 1-2, 页码: 79-148
作者: Shi, Bin; Du, Simon S.; Jordan, Michael, I; Su, Weijie J.

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收藏 | 浏览/下载：30/0 | 提交时间：2023/02/07

Convex optimization First-order method Polyak's heavy ball method Nesterov's accelerated gradient methods Ordinary differential equation Lyapunov function Gradient minimization

The effect of backlash nonlinear on resonance frequency of electric actuator transmission system (EI CONFERENCE) 会议论文 OAI收割
3rd IEEE International Conference on Advanced Computer Control, ICACC 2011, January 18, 2011 - January 20, 2011, Harbin, China
Han X.; Ge M.; Bai Y.; Jia H.; Ge W.

收藏 | 浏览/下载：23/0 | 提交时间：2013/03/25

In order to study the effect of backlash nonlinear on resonance frequency of electric actuator transmission system then Finally in the premise of meeting the stability the dynamic equilibrium equation of transmission system with backlash is established it makes dynamic simulation analysis for the transmission system based on virtual prototype technology it establishes balanced equation of dynamics system with backlash the effect of backlash on system natural frequency and resonance frequency and the theoretical values and simulation values are compared. Theoretical analysis and simulation results show that the theoretical analysis is basically consistent with simulation results when it is zero backlash and does some theory research and dynamic analysis of backlash nonlinearity and system natural frequency and resonance frequency. First and the error of theoretical analysis and simulation results is within 10%. Therefore according to describing function to theoretically model the backlash nonlinear it can be concluded that considering the transmission system theoretical analysis of backlash nonlinearity is feasible the relation between describing function and the amount of backlash and input amplitude is analyzed and it is much closer to the actual system with instructive significance. 2011 IEEE.

Design of reimaging F/1.0 long-wavelength infrared optical system (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Infrared Imaging and Applications, May 24, 2011 - May 24, 2011, Beijing, China
作者: Zhang X.; Zhang X.; Zhang X.

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A reimaging F/1.0 long-wavelength infrared optical system is proposed. The design has a flexible opto-mechanical layout. The design process is as follows. Firstly the catadioptric reimaging system consists of two reflecting mirrors and a relay lenses. Two reflecting mirrors make up of the first imaging system and are therefore free of chromatic aberrations while low dispersion lenses were used in the reimaging system so the optical system do not need achromatic design for a high image quality. Then to correct high-order aberrations resulting from large relative aperture more parameters need to be used with aspheric or diffractive surfaces due to modern optic technology development. Here aspheric is selected for easily manufacture. Finally the design is completed with the help of ZEMAX software. The effective focal length of the objective is 120mm and the field of view (FOV) is 4. The simulated final design shows adequate image quality and the modulation transfer function (MTF) is close to diffraction limit. The effect of the surrounding environmental temperature is analyzed using the concept of thermal defocusing and the thermal compensation is discussed. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Design of thermostat system based on Proteus simulation software (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electronic and Mechanical Engineering and Information Technology, EMEIT 2011, August 12, 2011 - August 14, 2011, Harbin, China
Han Z.; Song K.

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In order to solve the problem of precise temperature control the thermoelectric cooler (TEC) principle widely used is analyzed for the design of the whole control process and selection of control parameters and then accurate simulation model of the TEC is established in Proteus simulation software. Moreover combined with the traditional circuit simulation model the temperature control loop is designed and the response characteristics of the system are tested using an input signal similar to the unit-step function to achieve the precise temperature control. Simulation results show that the proposed control circuits can precisely convert error signal to output voltage sent to TEC model and TEC model behaves approximately like a two-pole system. The first pole starts at 20mHz and a second pole at 1Hz. 2011 IEEE.

Multi-focus image fusion algorithm based on adaptive PCNN and wavelet transform (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Imaging Detectors and Applications, May 24, 2011 - May 26, 2011, Beijing, China
Wu Z.-G.; Wang M.-J.; Han G.-L.

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Being an efficient method of information fusion image fusion has been used in many fields such as machine vision medical diagnosis military applications and remote sensing.In this paper Pulse Coupled Neural Network (PCNN) is introduced in this research field for its interesting properties in image processing including segmentation target recognition et al. and a novel algorithm based on PCNN and Wavelet Transform for Multi-focus image fusion is proposed. First the two original images are decomposed by wavelet transform. Then based on the PCNN a fusion rule in the Wavelet domain is given. This algorithm uses the wavelet coefficient in each frequency domain as the linking strength so that its value can be chosen adaptively. Wavelet coefficients map to the range of image gray-scale. The output threshold function attenuates to minimum gray over time. Then all pixels of image get the ignition. So the output of PCNN in each iteration time is ignition wavelet coefficients of threshold strength in different time. At this moment the sequences of ignition of wavelet coefficients represent ignition timing of each neuron. The ignition timing of PCNN in each neuron is mapped to corresponding image gray-scale range which is a picture of ignition timing mapping. Then it can judge the targets in the neuron are obvious features or not obvious. The fusion coefficients are decided by the compare-selection operator with the firing time gradient maps and the fusion image is reconstructed by wavelet inverse transform. Furthermore by this algorithm the threshold adjusting constant is estimated by appointed iteration number. Furthermore In order to sufficient reflect order of the firing time the threshold adjusting constant is estimated by appointed iteration number. So after the iteration achieved each of the wavelet coefficient is activated. In order to verify the effectiveness of proposed rules the experiments upon Multi-focus image are done. Moreover comparative results of evaluating fusion quality are listed. The experimental results show that the method can effectively enhance the edge details and improve the spatial resolution of the image. 2011 SPIE.

The research on test scheme of the digital Electromechanical Actuator based on CAN Bus (EI CONFERENCE) 会议论文 OAI收割
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011, July 15, 2011 - July 17, 2011, Inner Mongolia, China
作者: Zhang J.; Zhang J.; Zhang Y.; Zhang J.

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In order to realize the digital of Electromechanical Actuator(EMA) control system the CAN Bus which has efficient reliable performance and flexible network modes works as data interface.The EMA test scheme is designed based on the CAN Bus.First of all the microcontroller DSP with the CAN Bus works as the core of the EMA control system circuit boards.Then the CAN Bus test network is established with the EMA Ground Test System and Autopilot computer.The function and self-check of the EMA canbe conveniently tested by the network and the result of the test canbe easily displayed in the PC.Finally the CAN Bus test network is established with the EMA the Frequency Characteristics Scanner and etc.The purpose is to test the performance of the EMA.The result of the test can be intuitively showed on the Frequency Characteristics Scanner.In a word the application of the CAN bus provides a new method to test the EMA and reference to engineering the digital EMA which has vital significance. 2011 IEEE.

Adaptive Wiener filtering with Gaussian fitted point spread function in image restoration (EI CONFERENCE) 会议论文 OAI收割
2011 IEEE 2nd International Conference on Software Engineering and Service Science, ICSESS 2011, July 15, 2011 - July 17, 2011, Beijing, China
作者: Yang L.; Zhang X.; Zhang X.; Zhang X.; Yang L.

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In the imaging process of the space remote sensing camera there was degradation phenomenon in the acquired images. In order to reduce the image blur caused by the degradation the remote sensing images were restored to give prominence to the characteristic objects in the images. First the frequency-domain notch filter was adopted to remove strip noises in the images. Then using the ground characters with the knife-edge shape in the images the point spread function of the imaging system was estimated. In order to improve the accuracy the estimated point spread function was corrected with Gaussian fitting method. Finally the images were restored using the adaptive Wiener filtering with the fitted point spread function. Experimental results of the real remote sensing images showed that almost all strip noises in the images were eliminated. After the denoised images were restored its variance and its gray mean gradient increased also its laplacian gradient increased. Restoration with Gaussian fitted point spread function is beneficial to interpreting and analyzing the remote sensing images. After restoration the blur phenomenon of the images is reduced. The characters are highlighted and the visual effect of the images is clearer. 2011 IEEE.

Research on the identification for a nonlinear system (EI CONFERENCE) 会议论文 OAI收割
International Conference on Optical, Electronic Materials and Applications 2011, OEMA 2011, March 4, 2011 - March 6, 2011, Chongqing, China
作者: Liu J.; Jia P.; Liu J.; Liu J.

收藏 | 浏览/下载：32/0 | 提交时间：2013/03/25

The characteristic of the drift error of inertial platform is a high-order nonlinear dynamic system using the neural networks' abilities of universal approximation of differentiable trajectory and capturing system dynamic information this paper presents the drift error identifying project of inertial platform based on Elman networks structure. First the drift error model of inertial platform is established after selecting the input and output for network momentum and alterable speed algorithm is used to speed up the network convergence. On the basis of the algorithm the extended nonlinear node function in the hidden network does not only improve the learning speed of network but also satisfies the need of accuracy on system identification. Through the drift error data measured on inertial platform the training result shows that the scheme achieves satisfied identification results. (2011) Trans Tech Publications.

The parallel computation in one-way hash function designing (EI CONFERENCE) 会议论文 OAI收割
2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, CMCE 2010, August 24, 2010 - August 26, 2010, Changchun, China
作者: Yang H.

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In order to put the parallel one-way hash function into engineering two designing models based on pipeline technology are proposed in this paper. The definition of one-way hash function is shown first and the structure and limitation of the current hash functions are discussed afterward. By analyzing the difference between parallel computation on different platforms and classifying one-way hash functions on application basis the possibility and method of parallel one-way hash function designing on different hardware platforms are described two designing models are constructed for the parallel one-way hash function designing. Finally some attentions for designing are proposed from the engineering angle. The pipeline models that proposed in this paper contact the theoretical rationality and the engineering application of parallel one-way hash function together which can improve the practicality of parallel one-way hash function to a great extent. 2010 IEEE.

Influence of spatial temperature distribution on high accuracy interferometric metrology (EI CONFERENCE) 会议论文 OAI收割
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, April 26, 2010 - April 29, 2010, Dalian, China
作者: Yang H.; Zhang J.; Zhang J.; Zhang J.; Yan F.

收藏 | 浏览/下载：27/0 | 提交时间：2013/03/25

We calculate the influence of temperature change on the refractive index of air establish a model of air temperature distribution and analyze the effect of different temperature distribution on the high accuracy interferometric metrology. First a revised Edlen formula is employed to acquire the relation between temperature and refractive index of air followed by introducing the fixed temperature gradient distribution among the spatial grid within the optical cavity between the reference flat and the test flat of the Fizeau interferometer accompanied by a temperature change random function within each grid. Finally all the rays through the air layer with different incident angles are traced by Matlab program in order to obtain the final output position angle and OPD for each ray. The influence of different temperature distribution and the length of the optical cavity in on the testing accuracy can be analyzed through the RMS value that results from repeatable rays tracing. As a result the horizontal distribution (vertical to optical axis) has a large effect on the testing accuracy. Thus to realize the high accuracy figure metrology the horizontal distribution of temperature must be rigorously controlled as well as to shorten the length of the optical cavity to a large extent. The results from our simulation are of great significant for the accuracy analysis of interferometric testing and the research of manufacturing a interferometer. 2010 Copyright SPIE - The International Society for Optical Engineering.