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	Oscillations in a circular scramjet combustor operating at different inflow total pressures 期刊论文 OAI收割 APPLIED THERMAL ENGINEERING, 2025, 卷号: 280, 页码: 9 作者: Yu FY(于方游); Wang, Ziren \| 收藏 \| 浏览/下载：20/0 \| 提交时间：2025/10/27 Scramjet Combustion oscillation Main frequency Different inflow total pressures
	Comparison and simulation of subpixel imaging modes for linear CCD (EI CONFERENCE) 会议论文 OAI收割 2012 3rd International Conference on Information Technology for Manufacturing Systems, ITMS 2012, September 8, 2012 - September 9, 2012, Qingdao, China 作者: Li Y.; He B.; Li Y.; Li Y.; Li Y. 收藏 \| 浏览/下载：67/0 \| 提交时间：2013/03/25 Subpixel technique of linear CCD is effective to enhance the spatial resolution without increasing the focal length of optics and reducing the pixel size. To compare image quality of two main subpixel imaging modes quincunx sampling and four-point sampling a method to quantitatively evaluate image quality of subpixel based on MTF was proposed. The MTF of quincunx and four-point sampling modes were derived. Analytical results shows that theoretical limiting resolution of quincunx sampling and four-point sampling is improved to 1.4 and 1.86 times respectively and MTF values at Nyquist frequency of two modes are increased by 0.1106 and 0.1679 respectively. MTFA in (0 0.5) of two subpixel imaging modes were calculated and results illustrates that four-point sampling offers much more improvement with image quality than quincunx sampling at the cost of double amount of data. A model for simulating subpixel imaging using Matlab was established and simulation results of spoke target verify the theoretical analysis. (2012) Trans Tech Publications Switzerland.
	Stabilization and tracking precision improved based on disturbance observer (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 Sun G.; Zhu M.; Jia H. 收藏 \| 浏览/下载：54/0 \| 提交时间：2013/03/25 Based on the kinematics of semi-strapdown seeker the framework coordinate of the semi-strapdown seeker is established and the optical axis stabilization equation of semistrapdown seeker is deduced based on product of exponential (POE) formula. The stabilization control principle block diagram of semi-strapdown seeker is shown based on the stabilization equation. The main influence factors of the stability precision are pointed out such as friction disturbance velocity measurement noise and missile disturbance. For the sake of improving the stabilization precision and tracking precision disturbance observer was proposed in the inner loop of semi-strapdown seeker servo-control system. The low frequency external disturbance and high frequency velocity measurement noise are effectively restrained by the disturbance observer as shown in hardware-in-loop simulation and optical axis stabilization precision and tracking precision are greatly improved. 2011 IEEE.
	Research on lightweight outer baffle for coaxial space camera (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 作者: Zhang L.; Zhang L. 收藏 \| 浏览/下载：33/0 \| 提交时间：2013/03/25 Stray light is non-imaging light that reach the optical system imaging plane. The non-imaging light can be received by detector if it is not effectively controlled and stray light which directly irradiates on the detector has great influence on the imaging quality. Stray light can be effectively inhibited if the outer baffle of space camera is designed optimally. Carbon fiber composite material is chosen as main material to meet requirements of a coaxial space optical system. The outer baffle should have advantages such as lightweight high stiffness and dimensional stability etc. Using optimization design tools the lightweight outer baffle is designed. And finite element method is used to check the structure. Development and test results show that the outer baffle with a diameter of 620mm and a total length of 1200mm only weighs 7.3kg. And the baffle's natural frequency reaches 88Hz and it can satisfy the requirements of the space camera. 2011 IEEE.
	Optical axis stabilization of semi-strapdown seeker based on disturbance observer (EI CONFERENCE) 会议论文 OAI收割 2011 International Conference on Information and Automation, ICIA 2011, June 6, 2011 - June 8, 2011, Shenzhen, China Sun G.; Zhu M.; Yin S.; Jia H. 收藏 \| 浏览/下载：51/0 \| 提交时间：2013/03/25 Based on the kinematics of semi-strapdown seeker the framework coordinate of the seeker is established. The optical axis stability equation of semi-strapdown seeker is deduced by using attitude transformation matrix. Then the stability control principle block diagram of semi-strapdown seeker is shown based on the stability equation. The main factors that influence the stabilization precision are pointed out such as friction disturbance velocity-measuring noise and missile disturbance. In order to improve the stabilization precision disturbance observer was proposed in semi-strapdown seeker stability control. The low frequency external disturbance and high frequency velocity measurement noise are effectively restrained by the disturbance observer as shown in hardware-in-loop simulation and optical axis stabilization precision is improved nearly 20 times and 5 times due to two different frequencies with same amplitude. 2011 IEEE.
	Research on shaftless fast-steering mirror used in a precision tracking-aiming system (EI CONFERENCE) 会议论文 OAI收割 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies, AOMATT 2007: Large Mirrors and Telescopes, July 8, 2007 - July 12, 2007, Chengdu, China 作者: Wang Y.; Guo J.; Guo J.; Wang Y.; Wang Y. 收藏 \| 浏览/下载：47/0 \| 提交时间：2013/03/25 Based on the analysis of principle of tracking and aiming system some important factors to design the structure of tracking-aiming system and the layout of optical system are discussed. Besides the paper gives the present developing situation of fast-steering mirror at home and abroad analyzes the advantages and disadvantages of FSM with axis and presents a novel design of flexible axis FSM. The main axis of composite axis system is tracked by motor to drive the frame and the sub-axis is tracked by voice coil motor (VCM) to drive FSM. The structure of FSM and designing principle of VCM are introduced and the emulation analyses of inherent frequency and deformation under load of the FSM with software COSMOS are also given.
	Design of dual-FOV refractive/diffractive LWIR optical system (EI CONFERENCE) 会议论文 OAI收割 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies, AOMATT 2007: Advanced Optical Manufacturing Technologies, July 8, 2007 - July 12, 2007, Chengdu, China 作者: Wang L.-J.; Zhang J.-P.; Wang L.-J.; Zhang X.; Zhang X. 收藏 \| 浏览/下载：59/0 \| 提交时间：2013/03/25 An infrared-optical zoom system using binary element is proposed in this paper. The two main advantages of the zoom system introducing here are: bigger F-number and lower cost. The primary optical properties are: F/#=1 Second Others zoom ratio =1:4 binary element is used to correct the chromatical aberration by taking the advantage of negative dispersion characteristics and the cost of the system is lower than that of conventional ones with Zinc Selenide (Znse) material at the same level. In the binary element is rotational symmetric with one step which is easy to fabricate in order to balance 5th spherical aberration and dual field are 26.6 and 5.6respectively. Wider field of view is used for search and the smaller one is used for imaging details. This system uses un-cooled infrared detector with 320240 pixels and 45m pixel size. The F-number matches the sensitivity range of the detector array. Three aspects are considered during design process to make the system more satisfactory and more achievable. First 5th coma aberration and 5th astigmatic aberration the manner of zoom is accomplished by exchanging tow lenses into the smaller field of view system layout. The lens exchange manner faces the requirement of simple system structure and good image quality in both focal points. It can also make the system more feasible in the alignment process than mechanical-zooming manner and optical-zooming manner high-order asphere surfaces with 2th order to 10 th order are also hired in the system. Asphere surface is useful in compressing the system and improving optical system transmittance. This kind asphere surface is on industrial level featuring low cost and easy to fabricate. It is shown that good image quality can achieved by implementing five Germanium lenses and the transmittance of system is 72%. All aberrations are diffraction-limited both spherical aberration and astigmatic aberration are corrected. When the field of view(FOV) is 26.6 and the focal length is 152mm MTF at Nyquist frequency(11lp/mm) is great than 0.7. The spherical aberration is -0.0073. The coma aberration is 0.0978 and the astigmatic aberration is -0.013. When the field of view(FOV) is 5.6 and the focal length is 38mm MTF at Nyquist frequency is great than 0.8 with spherical aberration -0.0046 the coma aberration 0.055 and astigmatic aberration 0.034.
	Compression of remote sensing image based on Listless Zerotree Coding and DPCM (EI CONFERENCE) 会议论文 OAI收割 ICO20: Remote Sensing and Infrared Devices and Systems, August 21, 2005 - August 26, 2005, Changchun, China Chen S.-L.; Huang L.-Q. 收藏 \| 浏览/下载：50/0 \| 提交时间：2013/03/25 The data quantity of remote sensing image is very large. Furthermore the lowest frequency subband contains the main energy of original image and reflects the coarse of original image after remote sensing image is transformed by wavelet so it is very important to the reconstructed image. Therefore a hybrid image compression method based on Listless Zerotree Coding (LZC) and DPCM is presented namely the lowest frequency subband is compressed by DPCM and others are compressed by LZC. LZC is a kind of zerotree coding algorithm for hardware implementation which is based on SPIHT and substitutes two significant bit maps for three lists in SPIHT algorithm. Thereby LZC significantly reduces the memory requirement and complexity during encoding and decoding procedure. But LZC doesn't recognize the significance of grandchild sets so the PSNR values of LZC are lower than SPIHT's and the compression speed drops. It is improved by adding a significant bit map that recognizes the significance of grandchild sets. A comparison reveals that the PSNR results of the hybrid compression method are 2 dB higher than those of LZC and the compression speed is also improved.
	The advanced position compensation to improve the dynamic tracking ability for fast moving target in an optoelectronic tracking system (EI CONFERENCE) 会议论文 OAI收割 ICO20: Optical Devices and Instruments, August 21, 2005 - August 26, 2005, Changchun, China 作者: Zhao L.; Chen J. 收藏 \| 浏览/下载：27/0 \| 提交时间：2013/03/25 The servo control system of the optoelectronic tracking equipment usually is a kind of SISO. When the fast moving target is tracked the over-tune of the servo system is the main representation for the dynamic tracking error. As the result the tracking ability may be improved by limiting the over-tune. We put forward a method the advanced position compensation (called as APC in short) which is to check the speed-overtune by applying the advanced position information. For the large accelerate target small over-tune tracking is achieved but it lowers the ability for tracking the sine signal at low frequency area. While the dynamic high-type can improve the tracking precision for the sine signal at low frequency area we work out a brand-new method which combines the advantages of the both. It increases the tracking precision in the whole frequency band at large scale for the optoelectronic tracking system. The simulation results show that when the target moves with the largest accelerate 120/s2 120/s the maximum static tracking error is about 0.6.