An aviation hydraulic axial piston pump＇s degradation fiom comprehensive wear is a typical gradual failure model. Accurate wear prediction is difficult as random and uncertain char- acteristics must be factored into ...An aviation hydraulic axial piston pump＇s degradation fiom comprehensive wear is a typical gradual failure model. Accurate wear prediction is difficult as random and uncertain char- acteristics must be factored into the estimation. The internal wear status of the axial piston pump is characterized by the return oil flow based on fault mechanism analysis of the main frictional pairs in the pump. The performance degradation model is described by the Wiener process to predict the remaining useful life （RUL） of the pump. Maximum likelihood estimation （MLE） is performed by utilizing the expectation maximization （EM） algorithm to estimate the initial parameters of the Wiener process while recursive estimation is conducted utilizing the Kalman filter method to estimate the drift coefficient of the Wiener process. The RUL of the pump is then calculated accord- ing to the performance degradation model based on the Wiener process. Experimental results indi- cate that the return oil flow is a suitable characteristic for reflecting the internal wear status of the axial piston pump, and thus the Wiener process-based method may effectively predicate the RUL of the pump.展开更多
The real-time control system corrdativdy dealing with spatial information will become an important part of the artificial control system in the future. Geographical information system, as an analyzing and processing s...The real-time control system corrdativdy dealing with spatial information will become an important part of the artificial control system in the future. Geographical information system, as an analyzing and processing spatial data platform and powerful tool, will play a more and more role in the real-time control fidd. Agent-based architecture, as a concept of artificial intelligence, has been introduced in this paper. A new intdligent soft Agent, spatial-info Agent was developed, compared with the central nerve system, integrated by GIS and the traditional real-time control system. The realization model structure of spatial-info Agent was given too. And the techniques and integration methods were discussed by integrating mapinfo and fiber integration measurement system.展开更多
The application of digital photogrammetry to measure distribution of tree positions with stereo image couple is introduced in detail, and the procedure of stereo vision applied in forestry environment is explored. Non...The application of digital photogrammetry to measure distribution of tree positions with stereo image couple is introduced in detail, and the procedure of stereo vision applied in forestry environment is explored. Nonlinear error in measure model is adopted in the camera calibration; the interactive correlation matching is used under constraint of epipolar line and edge of tree detected by Canny operator. Results prove that application of digital photogrammetry technology to measure distribution of tree positions can meet demand of precision in experimental conditions.展开更多
Nonlinear cascaded femtosecond third harmonic generation was experimentally investigated pumped by 100 fs pulses at optical communication band 1550 nm using a multi-grating 5 mol. % MgO-doped periodically poled lithiu...Nonlinear cascaded femtosecond third harmonic generation was experimentally investigated pumped by 100 fs pulses at optical communication band 1550 nm using a multi-grating 5 mol. % MgO-doped periodically poled lithium niobate crystal. The optimized efficiency of 10.8% was achieved with the simultaneous phase-matching of the second harmonic and sum frequency process. And the third harmonic spectrum reached as broad as 8.7 nm because of the choosing of a small group velocity mismatching between the fundamental and second harmonic pulses. Nonlinear cascaded method will provide a reference for the efficient frequency conversion in the high intensity range.展开更多
以钛酸正丁酯和丙酮为原料,采用溶剂热法一步合成二氧化钛纳米微球样品,通过X射线衍射仪(XRD)、物理吸附仪、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对样品进行表征分析,探讨溶剂与煅烧温度及异丙醇用量对样品晶相与形貌结构的影响...以钛酸正丁酯和丙酮为原料,采用溶剂热法一步合成二氧化钛纳米微球样品,通过X射线衍射仪(XRD)、物理吸附仪、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对样品进行表征分析,探讨溶剂与煅烧温度及异丙醇用量对样品晶相与形貌结构的影响。结果表明:以丙酮为溶剂可制备出形貌规则、分布均匀的二氧化钛纳米微球,以乙醇为溶剂得到的是无序非晶结构的二氧化钛纳米微球;在溶液中添加1 m L异丙醇,200℃下反应12 h得到的样品比表面积最高。展开更多
基金supported by the National Natural Science Foundation of China(No.51305011)the National Basic Research Program of China(No.2014CB046402)the 111 Project of China
文摘An aviation hydraulic axial piston pump＇s degradation fiom comprehensive wear is a typical gradual failure model. Accurate wear prediction is difficult as random and uncertain char- acteristics must be factored into the estimation. The internal wear status of the axial piston pump is characterized by the return oil flow based on fault mechanism analysis of the main frictional pairs in the pump. The performance degradation model is described by the Wiener process to predict the remaining useful life （RUL） of the pump. Maximum likelihood estimation （MLE） is performed by utilizing the expectation maximization （EM） algorithm to estimate the initial parameters of the Wiener process while recursive estimation is conducted utilizing the Kalman filter method to estimate the drift coefficient of the Wiener process. The RUL of the pump is then calculated accord- ing to the performance degradation model based on the Wiener process. Experimental results indi- cate that the return oil flow is a suitable characteristic for reflecting the internal wear status of the axial piston pump, and thus the Wiener process-based method may effectively predicate the RUL of the pump.
文摘The real-time control system corrdativdy dealing with spatial information will become an important part of the artificial control system in the future. Geographical information system, as an analyzing and processing spatial data platform and powerful tool, will play a more and more role in the real-time control fidd. Agent-based architecture, as a concept of artificial intelligence, has been introduced in this paper. A new intdligent soft Agent, spatial-info Agent was developed, compared with the central nerve system, integrated by GIS and the traditional real-time control system. The realization model structure of spatial-info Agent was given too. And the techniques and integration methods were discussed by integrating mapinfo and fiber integration measurement system.
基金the National Natural Science Foundationof China (Grant No. 30271079)
文摘The application of digital photogrammetry to measure distribution of tree positions with stereo image couple is introduced in detail, and the procedure of stereo vision applied in forestry environment is explored. Nonlinear error in measure model is adopted in the camera calibration; the interactive correlation matching is used under constraint of epipolar line and edge of tree detected by Canny operator. Results prove that application of digital photogrammetry technology to measure distribution of tree positions can meet demand of precision in experimental conditions.
文摘Nonlinear cascaded femtosecond third harmonic generation was experimentally investigated pumped by 100 fs pulses at optical communication band 1550 nm using a multi-grating 5 mol. % MgO-doped periodically poled lithium niobate crystal. The optimized efficiency of 10.8% was achieved with the simultaneous phase-matching of the second harmonic and sum frequency process. And the third harmonic spectrum reached as broad as 8.7 nm because of the choosing of a small group velocity mismatching between the fundamental and second harmonic pulses. Nonlinear cascaded method will provide a reference for the efficient frequency conversion in the high intensity range.
文摘以钛酸正丁酯和丙酮为原料,采用溶剂热法一步合成二氧化钛纳米微球样品,通过X射线衍射仪(XRD)、物理吸附仪、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对样品进行表征分析,探讨溶剂与煅烧温度及异丙醇用量对样品晶相与形貌结构的影响。结果表明:以丙酮为溶剂可制备出形貌规则、分布均匀的二氧化钛纳米微球,以乙醇为溶剂得到的是无序非晶结构的二氧化钛纳米微球;在溶液中添加1 m L异丙醇,200℃下反应12 h得到的样品比表面积最高。
