中国科学院机构知识库网格系统: 检索

Effect of design parameters on the reduction of top piston ring friction (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Computer-Aided Design, Manufacturing, Modeling and Simulation, CDMMS 2012, September 21, 2012 - September 23, 2012, Chongqing, China
作者: Wang P.

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In order to reduce ring-liner interface friction power loss this paper focuses on the structure parameters of the top ring and investigates how the value of those parameters will influence top ring-liner friction power loss and the minimum thickness of oil film at top ring-liner interface. A mixed lubrication model is developed to simulate the effect of varying design parameters on ring-liner friction. Case study shows that ring-liner friction power loss will be reduced with decreased axial ring height and barrel height. This study provides a theoretical basis for design the top ring with reduced friction power loss at ring-liner interface. (2013) Trans Tech Publications Switzerland.

808nm high-power semiconductor laser therapeutic apparatus based on LPC2138 (EI CONFERENCE) 会议论文 OAI收割
2011 IEEE International conference on Intelligent Computation and Bio-Medical Instrumentation, ICBMI 2011, December 14, 2011 - December 17, 2011, Wuhan, Hubei, China
作者: Wang B.; Wang B.

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In this paper we designed an intelligent 808nm high-power semiconductor laser therapeutic apparatus with the LPC2138 ARM processor. The laser is driven by the digital constant current source module and the apparatus has good human-machine interaction performance on account of set the parameters intelligently. The function such as operation mode output power output pulse width and pulse cycle could be easily set through the TFT touch screen. The application software could transmission the log data to the computer by the USB interface in order to check and study the records later. 2011 IEEE.

Design and demonstration of micro multi-step mirrors and light source in micro FTIR (EI CONFERENCE) 会议论文 OAI收割
6th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2011, February 20, 2011 - February 23, 2011, Kaohsiung, Taiwan
Liang Z.; Fu J.; Feng C.; Liang J.

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To obtain high resolution high signal-to-noise ratio (SNR) high reliability and real time in wide spectral range we study the space modulation Micro Fourier Transform Spectrometer (FTS) based on multi-step mirrors covering the spectral range of 3-5m and 8-12 m in theory and experiment. The influences of spectrum reconstruction caused by the diffraction and extended light source in Fourier Transform Infrared Spectrometer (FTIR) are analyzed. A method to reduce the noises in spectrum reconstruction and the relationship between coherent intensity and solid angle of light source are discussed. An extended light source with suitable size is chosen considering the requirement of SNR and spectrum resolving power in the optical design. Furthermore the fabrication of micro multi-step mirrors which is the core part of FTS is investigated. Three methods for fabricating multi-step micro mirrors are demonstrated. 2011 IEEE.

Experiment analysis of CO2 laser disturbance on long-wave infrared HgCdTe detector (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electric Information and Control Engineering, ICEICE 2011, April 15, 2011 - April 17, 2011, Wuhan, China
作者:

收藏 | 浏览/下载：25/0 | 提交时间：2013/03/25

Theoretical analysis and experimental study were carried out on the high-power CO2 laser disturbance to long-wave infrared (LWIR) HgCdTe detector in this paper. Based on the practical parameters of experiment the theoretical model of temperature-rise is adopted to calculate the variation of the temperature with the time and the power of laser for laser irradiation on the detector. After that the damage threshold is 110W/cm2. This experimental phenomenon well agrees with the results predicted by the theoretical calculation. The conclusions have a certain reference value for the laser defense of detector. 2011 IEEE. the high-power laser damage mechanism to LWIR detector is discussed and compares with the experimental results of laser irradiation the detector on the distance of 15km. The theoretical and experimental results demonstrate that the interference threshold of the detector is 20.5W/cm 2

Study of three-mode parametric instability (EI CONFERENCE) 会议论文 OAI收割
8th Edoardo Amaldi Conference on Gravitational Waves, June 21, 2009 - June 26, 2009, New York, NY, United states
Liang F.; Zhao C.; Gras S.; Ju L.; Blair G.

收藏 | 浏览/下载：21/0 | 提交时间：2013/03/25

The effect of parametric instability in advanced interferometric gravitational wave detectors is a potential problem for their proper operation. Great efforts have been made to study the onset of parametric instabilities and to find ways to control them. Here we present an experimental design for studying parametric instability in a 72 m cavity with suspended high quality fused silica mirrors. With 5 W input power and 20 kW circulation power inside the cavity it is predicted that parametric instability will occur. The resonant condition of parametric instability can be met by thermally tuning the radius of curvature of a test mass. We will present simulation results of parametric gains for different radii of curvature of a test mass. The simulation results will provide the basis for designing the thermal tuning and observation parametric instability experiments. This will provide a test bed for studying parametric instability and its control for next generation detectors. 2010 IOP Publishing Ltd.

Analysis of laser jamming to satellite-based detector (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2009: Laser Sensing and Imaging, June 17, 2009 - June 19, 2009, Beijing, China
作者: Guo L.-H.; Guo R.-H.; Wang S.-W.

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The reconnaissance satellite communication satellite and navigation satellite used in the military applications have played more and more important role in the advanced technique wars and already become the significant support and aid system for military actions. With the development of all kinds of satellites anti-satellite laser weapons emerge as the times require. The experiments and analyses of laser disturbing CCD (charge coupled detector) in near ground have been studied by many research groups but their results are not suitable to the case that using laser disturbs the satellite-based detector. Because the distance between the satellite-based detector and the ground is very large it is difficult to damage it directly. However the optical receive system of satellite detector has large optical gain so laser disturbing satellite detector is possible. In order to determine its feasibility the theoretical analyses and experimental study are carried out in the paper. Firstly the influence factors of laser disturbing satellite detector are analyzed in detail which including laser power density on the surface of the detector after long distance transmission and laser power density threshold for disturbing etc. These factors are not only induced by the satellite orbit but dependence on the following parameters: laser average power in the ground laser beam quality tracing and aiming precision and atmospheric transmission. A calculation model is developed by considering all factors which then the power density entering into the detector can be calculated. Secondly the laser disturbing experiment is performed by using LD (laser diode) with the wavelength 808 nm disturbing CCD 5 kilometer away which the disturbing threshold value is obtained as 3.5510-4mW/cm2 that coincides with other researcher's results. Finally using the theoretical model the energy density of laser on the photosensitive surface of MSTI-3 satellite detector is estimated as about 100mW/cm2 which is largely exceed the disturbing threshold and therefore verify the feasibility of using this kind of laser disturbing the satellite-based detector. According to the results. using the similar laser power density absolutely saturate the requirements to laser disturbing satellite-based detector. If considering the peak power of pulsed laser even decrease laser average power it is also possible to damage the detector. This result will provide the reliable evidences to evaluate the effect of laser disturbing satellite-based detector. 2009 SPIE.

Research on 10.6 m laser beam monitoring in CO2 laser processing system (EI CONFERENCE) 会议论文 OAI收割
Infrared Materials, Devices, and Applications, November 12, 2007 - November 15, 2007, Beijing, China
作者: Gao Y.; Shao S.

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It is a key point of CO2 laser beam monitoring in the CO 2 laser processing system to achieve alignment between CO2 laser and PL (pointing and launching) system. By monitoring the angle offset of CO2 laser beam the compensation can be gotten witch is given to fast-steering mirror to rectify the direction of laser beam. But the normal photoelectric detector can not get the laser signal because of CO2 laser's high energy and long wavelength. Its wavelength is 10.6m and its power can reach kW level. Consequently it is difficult to detect the high-energy 10.6m laser beam directly. So we monitored the output mirror of laser resonator superseded the laser beam indirectly. The laser beam monitoring system could be designed based on CCD laser auto-collimation angular measurement principle and image processing method. In this paper application of CCD laser auto-collimation angular measurement principle and image processing method for CO2 laser beam monitoring system is introduced particularly After design fabrication and alignment the monitoring system can be used for experimental study that including angular measurement accuracy and angle offset measurement of CO2 laser beam. Angle offset range and angle variation rule of CO2 laser beam is also can be acquired for further research.

CR image filter methods research based on wavelet-domain hidden markov models (EI CONFERENCE) 会议论文 OAI收割
ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China
作者: Wang J.-L.; Wang J.-L.; Li D.-Y.; Wang Y.-P.

收藏 | 浏览/下载：20/0 | 提交时间：2013/03/25

In the procedure of computed radiography imaging we should firstly get across the characters of kinds of noises and the relationship between the image signals and noises. Based on the specialties of computed radiography (CR) images and medical image processing we have study the filtering methods for computed radiography images noises. On the base of analyzing computed radiography imaging system in detail the author think that the major two noises are Gaussian white noise and Poisson noise. Then the different relationship of between two kinds of noises and signal were studied completely. By considering both the characteristics of computed radiography images and the statistical features of wavelet transformed images a multiscale image filtering algorithm which based on two-state hidden markov model (HMM) and mixture Gaussian statistical model has been used to decrease the Gaussian white noise in computed images. By using EM (Expectation Maximization) algorithm to estimate noise coefficients in each scale and obtain power spectrum matrix then this carried through the syncretized two Filter that are IIR(infinite impulse response) Wiener Filter and HMM according to scale size and achieve the experiments as well as the comparison with other denoising methods were presented at last.

Optical fiber transmission of Q-switdied Nd:YAG pulses of 10MW peak power: Mechanism of damage to the fiber (EI CONFERENCE) 会议论文 OAI收割
2nd International Symposium on Advanced Optical Manufacturing and Testing Technologies - Advanced Optical Manufacturing and Testing Technologies, November 2, 2005 - November 5, 2005, Xian, China
作者: Wang L.; Zhang Y.; Chen W.; Tang Y.; Wang L.

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This paper presents theoretical analysis and experiment results of four different fibers transmitting 10MW peak power Nd: YAG laser pulse. The main factors limiting to optical fiber transmission of high power laser pulse is pointed including air breakdown at focus area and surface damage of optical fiber. The theory of air breakdown and the fiber coupling conditions is described briefly. The results of study to the transmission properties and damage conditions are presented on the basis of four different types of optical fibers. The results of the experiments are further analyzed in the aspects of transmitting efficiency air breakdown and surface damage. The local and foreign optical fibers with plastic-cladding and silica-cladding and step- index and graded- index fibers are tested separately in the experiments. The experiments showed that the imported fibers are able to transmit up to 10MW peak power laser pulse with no any visible damage while energy density at the fiber output end surface is 3.54GW/cm2. For local fibers damage on the input surface of both plastic-cladding and silica-cladding step-index fibers was found obviously. The column damage to the graded index fiber was also found and investigated in the research. Damage mechanisms of fiber at high peak power laser pulses are summarized. High quality finishing of fiber end surface will improve damage threshold tremendously. The conclusion of the study is that transmitting Q-switched Nd:YAG pulses of 10MW peak power is feasible for the domestically made fibers if their end surfaces are properly processed.

Numerical analysis and experimental research of output performance for Yb3+-doped double-clad fiber lasers (EI CONFERENCE) 会议论文 OAI收割
High-Power Lasers and Applications III, November 8, 2004 - November 11, 2004, Beijing, China
作者: Wang G.; Gao Y.; Li Y.; Li Y.; Li Y.

收藏 | 浏览/下载：17/0 | 提交时间：2013/03/25

In this paper numerical analysis was investigated for the double-clad fiber lasers and experimental study on the Yb3+-doped double-clad fiber lasers was performed. The results shown that the output power increased monotonically with absorbed power and in lossy cavity the output power is less than in the lossless cavity. The output power decreases for the lossy fiber with the reflectivity of output coupler. There was an optimum fiber length to reach a maximum output and the optimum length was mainly dependent on the loss coefficient. In experiment we obtained a output power of 21.6W slope efficiency of 54% by using Yb3+-doped double-clad fiber and 40W LD pump source.