中国开放科研知识云: 检索

Finite element model and analysis for micro-cutting of aluminum alloy 7050-T7451 (EI CONFERENCE) 会议论文
2012 International Conference on Machine Design and Manufacturing Engineering, ICMDME 2012, May 11, 2012 - May 12, 2012, Jeju Island, Korea, Republic of
Wang F.; Sun J.; Sun P.; Zhou J.

收藏 | 浏览/下载：14/0 | 提交时间：2013/03/25

In this paper a finite element model with respect to actual state of micro-cutting is established by adopting software of ABAQUS/Explicit. Based on the FE model the cutting force and specific cutting force with various uncut depth of cut with different cutting edge radius are compared and then analyzed with regard to this simulation. In micro-cutting the nonlinear scaling phenomenon is more evident with the decreasing of uncut chip thickness. The likely explanations for the size effect in small uncut chip thickness are discussed in this paper. (2012) Trans Tech Publications Switzerland.

Design and experimental research of a new type focus mechanism used in space-based telescope (EI CONFERENCE) 会议论文
2012 9th IEEE International Conference on Mechatronics and Automation, ICMA 2012, August 5, 2012 - August 8, 2012, Chengdu, China
Wang D.; Jia X.

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The position of focal plane will be changed because of temperature fluctuation and vacuum environment. In order to make the telescope work well positioning accuracy of the mechanism is 0.008mm. The performance satisfies the need of precision a focusing mechanism is needed. To majority of large space-based telescopes and the scheme design is reasonable and practicable. 2012 IEEE. the general way to do this would be to use a reflector which was located in the backfocal distance. One of typical schemes of this mechanism was introduced however because of the big axial size the mechanism can't be used when the size of the enclosure was limited. A new type of focusing mechanism was introduced which has such advantages of small size high accuracy and low mass. The design and test methods had been discussed. According to the results the repeatability positioning accuracy is 0.0025mm

Physical layer design for free space optical communication (EI CONFERENCE) 会议论文
2012 International Conference on Control Engineering and Communication Technology, ICCECT 2012, December 7, 2012 - December 9, 2012, Shenyang, Liaoning, China
Wang H.; Guo J.; Wang T.; Zhang Q.; Shao J.

收藏 | 浏览/下载：20/0 | 提交时间：2013/03/25

A small size Free Space Optical Communication System is introduced including the hardware and the hardware specified physical layer protocol. In detail the rapid synchronization method to reduce the handshake bandwidth requirement is demonstrated. The hardware of the system includes the laser driver system the signal amplifying and shaping system the data interface system. The hardware specified physical layer protocol is used to interface the outer data serialize and deserialize the data stream check transmission errors and schedule the data transmission. The overall system is a FIFO-like system and the user can use it as if he's operating a FIFO. The system is designed mainly for terrestrial FSO link whose signal channel is the atmosphere. Due to the complex composition and activity of the atmosphere this signal channel brings in great influence on the transmitting laser in it for example the absorption and scattering of the atmosphere molecules and aerosols the scintillation of received laser power caused by the turbulence of the atmosphere all of which results in a much higher Bit Error Rate (BER) of the communication system than wired communication systems leading to frequent resynchronization. In our system the sampling clock is generated locally using multi-phase sampling technique rather than PLLbased clock recovery which helps to rapid synchronization. 2012 IEEE.

Design of motion compensation mechanism of satellite remote sensing camera (EI CONFERENCE) 会议论文
International Symposium on Photoelectronic Detection and Imaging 2011: Space Exploration Technologies and Applications, May 24, 2011 - May 26, 2011, Beijing, China
Gu S.; Yan Y.; Xu K.; Jin G.

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Simulation and experiment of the static FTIR based on micro multi-step mirrors (EI CONFERENCE) 会议论文
International Symposium on Photoelectronic Detection and Imaging 2011: Sensor and Micromachined Optical Device Technologies, May 24, 2011 - May 26, 2011, Beijing, China
Liang J.; Liang Z.-Z.; Lv J.-G.; Fu J.-G.; Zheng Y.; Feng C.; Wang W.-B.; Zhu W.-B.; Yao J.-S.; Zhang J.

收藏 | 浏览/下载：26/0 | 提交时间：2013/03/25

In recent years Fourier transform spectrometer (FTS) with small size and low mass is required in many applications with growing need for real-time and small platform spectral detection. In this paper a micro Fourier transform infrared spectrometer (FTIR) based on spatial modulation mode was designed. This spectrometer has the advantages of high stability and simplified configuration. It also promises optical path differences (OPD) with high precision as MOEMS technology is used in manufacturing the key components. The simulation and the experiments with regard to this FTIR configuration have been done. Firstly the diffraction effect of the micro multi-step mirrors (MMSMs) is studied. We discuss the influence to the reversed spectrum by different mirror widths and different diffraction distances. Secondly we simulate and analyze the influence of the source solid angle to the spectral resolution. Thirdly we set up the theoretical model of the collimation error which is mainly from the defocus of the optical system and analyze the result caused by the collimation error. Fourthly a new discrete Fourier transform arithmetic using least-squares cosines progression (LSCP) is proposed which can reconstruct the spectrum with nonuniform sampled signals. Finally the MMSMs are fabricated used the MOEMS technology and the structural parameters are tested. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Attitude determination of small, dim and high-speed targets based on multi-CMOS intersecting system (EI CONFERENCE) 会议论文
2nd International Conference on Information Science and Engineering, ICISE2010, December 4, 2010 - December 6, 2010, Hangzhou, China
Li M.; Wang J.; Zhao L.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

In order to measure attitude of small dim and high-speed targets in shooting range intersecting system based on multiple high-speed CMOS cameras was introduced in this paper. CMOS cameras were laid near from objects for small size using multiple CMOS cameras to compose intersecting system for big number of targets tested and selecting CMOS camera between CMOS and CCD for low cost and considering damage to measurement equipment of objects tested. Pitch angle and yaw angle were measured by extracting axle wire through image processing image sequences were obtained from cameras laying on two sides. Velocity of objects was calculated by least square curve-fitting acquiring coordinate of centroid on image received by CMOS camera laying below effective viewing field. One CMOS camera was laid on right ahead for measuring roll angle. Station mode introduced in this paper has virtue of low cost and free extending. 2010 IEEE.

Development and radiance calibration of three-waveband camera (EI CONFERENCE) 会议论文
International Symposium on Photonics and Optoelectronics, SOPO 2010, June 19, 2010 - June 21, 2010, Chengdu, China
Lu Z.; Sun Q.; Wang J.; Lu Z.; Liu Y.

收藏 | 浏览/下载：23/0 | 提交时间：2013/03/25

An imaging system with three-waveband sharing one lens and an area CCD was developed. By rotating different filters into the beam path the required waveband was selected. The optical system which can image in ultraviolet visible and near infrared region was designed and the signal collecting system was integrated. The optical design and system integration have some advantages such as low cost small size and light in weight. To obtain a high imaging quality the radiation calibration is carried out in order to establish the relation between the average grey level of output image and the input radiance from the integrating sphere. According to the calibration data in experiments the radiation dynamic range and the best working point of the system are determined. The experiment result shows that the dynamic range of the image system is maximal when the exposure time is 8ms in ultraviolet 0.5ms in visible and 0.125ms in near infrared region. 2010 IEEE.

An image matching algorithm based on sub-block coding (EI CONFERENCE) 会议论文
2nd International Workshop on Computer Science and Engineering, WCSE 2009, October 28, 2009 - October 30, 2009, Qingdao, China
Feng Y.; Li S.; Dai M.

收藏 | 浏览/下载：21/0 | 提交时间：2013/03/25

In order to improve the speed of matching algorithm and simplify the processing of existing sub-block coding matching a new template matching method combined local gray value encoding matching and phase correlation is proposed. Matching process is divided into rough matching and fine matching. Rough matching divides the image into certain size blocks called R-block sums the gray value of each R-block pixel encodes the R-block according to the gray value distribution of R-block with the adjacent R-block and matches by step between the template and each search sub-image. Then fine matching results are obtained using phase correlation according to initial match parameters. The time complexity of the proposed method is (M2) .The new algorithm is faster than traditional algorithm by two orders of magnitude and the speed has improved twice compared with existing sub-block coding method. Experiments demonstrate that the new algorithm is robust to the linear transformation of pixel grey value and image noise and it also has the stability of small-angle rotation. 2009 IEEE.

An improved two-dimensional entropy method for star trail tracing in deep sky (EI CONFERENCE) 会议论文
ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China
Yao Z.-J.; Wang Y.-J.; Han Q.-L.

收藏 | 浏览/下载：15/0 | 提交时间：2013/03/25

The trace of star trail is an important component of deep sky detection. The stars are low contrast targets and their self-rotation will make their brightness change in cycle. Above all the trail trace is vulnerable to the block and disturbance of other stars. Traditional one-dimensional maximum entropy thresholding algorithm is vulnerable to the noise and the calculation of two-dimensional entropy methods is too large and takes too much time. This paper proposes an improved two-dimensional entropy threshold algorithm. We use recursion iteration method to eliminate the redundancy calculation and reduce the size of two-dimensional histogram based on the deep sky stars characteristic such as low contrast fuzziness and the centralized histogram. We also combine our algorithm with the space trail trace model to forecast the star trace. Experiments results show when the star are blocked or they turn dark the method still can well extrapolate the star trace. Our method improves the capability of trailing the ebb and small star and increases the precision of tracing. It is also robust to the noise so there is a good application foreground for the method.

Low drive-voltage and high-bandwidth electro-optic modulators based on BaTiO3 thin-film waveguides (EI CONFERENCE) 会议论文
Science and Technology of Dielectrics for Active and Passive Photonic Devices - 210th Electrochemical Society Meeting, October 29, 2006 - November 3, 2006, Cancun, Mexico
Sun D. G.; Fu X. H.; Liu Z. F.; Ho S. T.; Wessels B. W.

收藏 | 浏览/下载：31/0 | 提交时间：2013/03/25

We investigated electro-optic modulator structures to target low drive voltage high-speed modulation and small device size with c-axis grown BaTiO3/MgO ferro-electric thin films. In this study the calculations are focused on the ideal thin film with a quadratic relation between the half-wave drive voltage V and the interaction length L in the electro-optic modulation case we obtained in previous work. With the quadratic electro-optic modulating relation and the optimal rib waveguide structure of BaTiO3/MgO thin films the frequency-voltage-size performances for 2.5GHz 10GHz 40GHz and 100GHz modulation bandwidths have been obtained under half-wave drive voltages of 0.8V 1.6V 3.0V and 4.8V respectively for the ideal film with r51=730 pm/V at 1550nm wavelength where both the phase velocity matching condition and the conductor induced microwave attenuation are considered. The required device lengths to achieve these four typical values of modulation bandwidth are 3.3 mm 0.8 mm 0.4 mm and 0.2 mm respectively. With the c-axis grown BaTiO3/MgO crystal thin films and the quadratic electro-optic modulating relation an electro-optic coefficient of reff=180 pm/V for the c-axis grown BaTiO3/MgO ferro-electric thin films was measured which is relatively far from the ideal value of r51=560 pm/V. copyright The Electrochemical Society.

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