中国科学院机构知识库网格系统: 检索

Evaluation of the operating range for ground-based infrared imaging tracking 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 Z.-D.

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Ground-based infrared imaging tracking system (GIITS) is of great importance for aerial target warning and guard. The operating range is one of the key performance specifications on the other which should be calculated calculate the radiation power received on the detector in order to analysis whether the output signal meets the detection requirements or not analyzed and studied during the whole GIITS design process. The operating range is mostly influenced by a few factors without considering the effect of the background radiation. By improving of the traditional method including atmospheric attenuation a new operating range calculation model of the GIITS was established based on two requirements. One is that the image size of observed target should meet the requirement of the processor signal extraction. The number of the pixel occupied by target image should be more than 9. The other is that the signal noise ratio (SNR) of the GIITS should not be less than 5 to meet the requirements of the target detection probability and spatial frequency. The SNR calculation equation in form of energy is deduced and the radiation characteristic of the observed target and background are analyzed. When evaluate the operating range of the GIITS using the new method the performance of GIITS and feature of target and background. This paper firstly makes analysis and summarization on the definite localizations of the traditional operating range equation of the GIITS. The localizations are mainly in two aspects. On one hand we should successively calculate two operating range values according to two requirements mentioned above and choose the minimum value as the analytic result. In the end the dispersion of the image and the effect of image dispersion are not considered in the traditional method an evaluation of operating range for fighter aircraft is accomplished as an example. The influence factors in every aspect on operating range were explored by the calculated result. The new operating range calculation model provides the theoretical basis for the design and applications as well as the comprehensive evaluation of a GIITS. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Analysis of zenith pass problem in a roll-pitch optics seeker (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electronics and Optoelectronics, ICEOE 2011, July 29, 2011 - July 31, 2011, Dalian, China
作者: Jiang H.

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There are mainly two kind of structures for a missile two-axes seeker which is always mentioned as elevate-azimuth and roll-pitch. The elevate-azimuth structured seeker has been studied for a long time and it is applied in all sort of missiles. Not only structure design but also control algorithm of the elevate-azimuth seeker are deeply developed. But for elevate-azimuth seeker there are several disadvantages such as big size and large abaxial angle blind. So the elevate-azimuth seeker gimbal angle is designed up to 65 according to relative references. In modern air war it is important for a missile to have the ability of "first recognize" and "first attack". That means the air to air missile seeker is required to be a system with large gimbal angle and large abaxial launch angle. With the mentioned requirement roll-pitch seeker with its advantages smart size and large gimbal angle is studied widely and deeply. The pitch angle of roll-pitch is up to 90 while its roll angle up to n 360. But there are also some disadvantages for the roll-pitch seeker the most troublesome one is the zenith pass problem. The zenith pass problem is brought about from the gimbal kinematics it is said that when target moves in the center of image plane roll servo command gotten from the kinematics algorithm will go to infinite. Math model of zenith pass problem is proposed in this paper and two ways to solve the problem are brought forward. 2011 IEEE.

Design of high precision star image locating method used in star sensor technology (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: Sun H.; Wang Y.; Wang Y.; Wang Y.; Wang Y.

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Nowadays star sensor technology used in aircraft attitude measurement has become more and more popular for its high precision light weight without attitude accumulation errors and other advantages. In order to enhance the accuracy of star sensor it is critical to make efforts to promote the precision of star image locating. High precision star image locating method mentioned in this article includes two aspects. One is sub-pixel dividing algorithm used to acquire the coordinate of stars. The other one is imaging calibration method used to weaken the effect caused by imaging distortion. This method is finally realized in some type of star sensor system. Then an experiment is designed to verify the precision of the method. The result of the experiment shows that the precision of the method is 2" in the experimental environment. 2010 IEEE.

New phase measurement method for laser rangefinder (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: Meng Z.; Meng Z.

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A new phase measurement method is designed and presented by using the technique of signal shifting phase and the technique of signal multiplication for laser rangefinder. The intensity of laser light is modulated by cosine circuit signal at the same time the cosine circuit signal is thansformed sine signal by the shifting phase technique. Two signals mentioned above are multiplied by received signal from the target respectively then being transmitted into signal processor after passing through low band filter respectively. The result of phase-shift between the received signal and sent signal is calculated by means of signal processor and time-counter with double frequency of modulation signal. The proposed system is composed of four units such as control and count unit emitting and receiving unit of laser light signal processing unit and result display unit. The two most advantages of proposed system over others are its ability of proper isolation which reduces crosstalk and its independency thermal drift. Theoretical calculations and experimental results have shown the accuracy better than 2 mm. 2010 Copyright SPIE - The International Society for Optical Engineering.

Position servo control of a DC electromotor using a hybrid method based on model reference adaptive control (MRAC) (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: Chen J.

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This paper dealed with position control problems of a DC motor servo system that had nonlinear friction and was subject to parametric uncertainties external disturbances etc. In order to overcame those unfavourable factors mentioned above a model reference adaptive control method was proposed to regulate the important and main speed loop in the positioning system which was designed with three closed control loop where a compensatory measure was given so as to counterbalance the friction torque disturbances. In addition the other two close loops were built in adjusting the position and the current of the servo system respectively that aimed to achieve the fast and precise positioning and increase dynamic stiffness against load disturbances. Experimental results illustrate satisfactory performances in steady state error load capability high rapidity and so on. 2010 IEEE.

Micro-motion exposure method based on PZT piezoelectric ceramics (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2009: Material and Device Technology for Sensors, June 17, 2009 - June 19, 2009, Beijing, China
作者: Meng Z.; Meng Z.

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There mainly is laser digital photofinishing technique and digital photofinishing technique based on LCD consisting of TFT and LCOS in the digital photofinishing field at the present time. The former have a good many merit such as wide color gamut high processing rate large output size and high brightness but his cost is very high his maintain technique being comparatively complex that result in difficult use for people. The utilization ratio of the latter is low because of lower resolution and lower aperture ratio for LCD but the digital photofinishing based on LCD have lower cost and higher utilization ration being suitable for people's current standard of living. Considering above mentioned problem a micro-motion exposure method based on PZT piezoelectric ceramics used in digital image photofinishing is presented. The two-dimension micro-motion exposure system consisting of PZT piezoelectric ceramics LCD panel polarizing film and spring strip is designed. By means of PZT piezoelectric ceramics the LCD panel is removed about the one half of the pixel size of the LCD panel for four times from the original place at the same time imaging system is exposed four times at the printing paper. The software is used to control the time synchronization the exposure time and motion range of the LCD panel. The system has advantages such as shorter response time than 0.1seconds lesser motion error than 0.01 microns high stability and repeatability. Experimental results show that the proposed micro-motion exposure method improve the picture brightness and enlarge output size at the meantime reducing the cost of the system. 2009 SPIE.

Study on experiment of grinding SiC mirror with fixed abrasive (EI CONFERENCE) 会议论文 OAI收割
4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies, November 19, 2008 - November 21, 2008, Chengdu, China
作者: Wang X.; Zhang X.-J.; Wang X.; Wang X.

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A brand-new technology for manufacturing SiC reflecting mirror that is different from the traditional method is adopted which is called as fixed abrasive surfacing technology. Not only the new method achieves better mirror quality with bigger diamond in diameter quickly but also because of the fixed motion between the abrasive and workpiece and it will be good for surface finishing. During experiment material removal characteristic which is on SiC under certain rotation speed and pressure by W7 W5 W3.5 W1.5 pellets has been tested. Through those removal curves we come to a conclusion that the technology not only has a higher removal rate but also has much more stability. In addition the surface roughness experiment is mentioned. In the first stage we achieved a mirror with surface roughness 42.758nm rms with W7 pellets. The surface roughness is descending as we change pellets with smaller diamond in diameter . At the end of experiment a smooth surface with roughness 1.591nm rms has been achieved after using W1.5 pellets. Experiment results indicate that the technology which manufactures SiC reflecting mirror with fixed abrasive is able to replace the traditional slurry abrasive completely in certain finishing phase and also has a great foreground in application. 2009 SPIE.

Correction method for detection of the frequencies of railway fsk signals (EI CONFERENCE) 会议论文 OAI收割
2008 9th International Conference on Signal Processing, ICSP 2008, October 26, 2008 - October 29, 2008, Beijing, China
作者: Yu J.

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In order to acquire the information of railway binary frequency-shift keying signals which include upper/down side frequencies and base low-frequency with high-accuracy a novel frequency detection algorithm for France UM-71 system is proposed. Combining fast Fourier transform with the ratio correction method the carrier frequency and the base frequency are obtained. Furthermore the hardware consumption has been decreased. And it possesses the advantage of simple algorithm and fast operation speed. Comparing with the detection of the base frequency the upper/down side frequency of railway signal is more difficult. Based on spectrum analysis and the spectrum correction a new method which adopts the sliding window is put forward in this paper. The absolute differences between the upper side frequencies and the down side frequencies obtained are regarded as the criterion for judgment. Then the set of data in which the maximum absolute value is is to be the result of the upper/down side frequency. Because the sliding window will go through every stage when the upper/down side frequency changes therefore it is not sensitive enough to the position of data which need to be transformed. Using the method mentioned above the experiment results show that the accuracy requirement of the side frequency is satisfied well. 2008 IEEE.

Driving techniques for high frame rate CCD camera (EI CONFERENCE) 会议论文 OAI收割
Electronic Imaging and Multimedia Technology V, November 12, 2007 - November 15, 2007, Beijing, China
Guo W.; Jin L.; Xiong J.

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This paper describes a high-frame rate CCD camera capable of operating at 100 frames/s. This camera utilizes Kodak KAI-0340 an interline transfer CCD with 640(vertical)480(horizontal) pixels. Two output ports are used to read out CCD data and pixel rates approaching 30 MHz. Because of its reduced effective opacity of vertical charge transfer registers interline transfer CCD can cause undesired image artifacts such as random white spots and smear generated in the registers. To increase frame rate a kind of speed-up structure has been incorporated inside KAI-0340 then it is vulnerable to a vertical stripe effect. The phenomena which mentioned above may severely impair the image quality. To solve these problems some electronic methods of eliminating these artifacts are adopted. Special clocking mode can dump the unwanted charge quickly then the fast readout of the images cleared of smear follows immediately. Amplifier is used to sense and correct delay mismatch between the dual phase vertical clock pulses the transition edges become close to coincident so vertical stripes disappear. Results obtained with the CCD camera are shown.

A high-accuracy parameter estimation algorithm for jointless Frequency-shift track circuit (EI CONFERENCE) 会议论文 OAI收割
ISECS International Colloquium on Computing, Communication, Control, and Management, CCCM 2008, August 3, 2008 - August 4, 2008, Guangzhou, China
作者: Zheng X.

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FSK (Frequency Shift keying) signal which has advantages of narrow-bandwidth strong anti-interference ability long transmission distance and so on is used in jointless Frequency-shift track circuit to send different kinds of control signals. However as FSK is non-linearly modulated parameter estimation with high accuracy is hard to realize. Based on the spectrum analysis complement with time-frequency distribution a highaccuracy FSK signal parameter estimation algorithm is put forward in this paper. According to the signal characteristics under-sampling and ZFFT are used to improve the accuracy of spectrum analysis and the base frequency resolution meets system requirement of 0.02Hz. Wigner-Ville distribution has an excellent time-frequency concentration while serious cross-term interference at the same time. Through the design of kernel function the cross-terms are almost suppressed and the upper/down side frequency resolution meets the system requirement of 0.2Hz. The effectivities of all the methods mentioned above have been proved by MATLAB simulation which pave a solid way for the development of high-accuracy FSK signal parameter estimation devices. 2008 IEEE.