为了解决大型回转支承背景噪声大,特征信号微弱,寿命状态难以识别等问题,提出了一种基于改进深度信念网络(Deep Belief Network,DBN)的回转支承寿命状态识别方法。DBN网络拥有强大的深度学习能力,能够有效挖掘回转支承运行状态信息,解...为了解决大型回转支承背景噪声大,特征信号微弱,寿命状态难以识别等问题,提出了一种基于改进深度信念网络(Deep Belief Network,DBN)的回转支承寿命状态识别方法。DBN网络拥有强大的深度学习能力,能够有效挖掘回转支承运行状态信息,解决了传统浅层网络过度依赖特征提取效果和识别精度不高的问题。在DBN学习训练中,采用新的优化学习方法FEPCD(Free Energy in Persistent Contrastive Divergence),解决了DBN在长期学习中近似和分类能力下降的问题。然后利用自主研发试验台的试验数据对所提方法的优越性进行验证。将改进的DBN算法与浅层分类算法的识别结果进行比较。结果表明改进DBN网络比原始DBN网络和浅层算法能更精确反映回转支承寿命特征,所提方法具有稳定性和智能性的特点。展开更多
The structure of a strip LiNbO3 waveguide clad with a planar LiNbOa waveguide is proposed to fabricate a long-period waveguide grating （LPWG）. It is shown theoretically that an LPWG device based on such a special Li...The structure of a strip LiNbO3 waveguide clad with a planar LiNbOa waveguide is proposed to fabricate a long-period waveguide grating （LPWG）. It is shown theoretically that an LPWG device based on such a special LiNbOa waveguide structure is of the merit of thermal stability. The methods for fabrication of planar waveguide, channel waveguide and grating are suggested and discussed. Detailed design consideration is exemplified based on a soft-proton-exchange planar waveguide clad Ti-diffused LiNbOa （Z-cut） strip waveguide.展开更多
We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical stud...We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical studies show that these waveguides are monomode at 1.5~／mu m and have losses of 1.3 and 1.1~dB/cm for the TM and TE modes, respectively. In the waveguide width/depth direction, the mode field follows a Gauss/Hermite--Gauss profile. A secondary ion mass spectrometry study reveals that the Ti profile follows a sum of two error functions along the width direction and a complementary error function in the depth direction. Micro-Raman analysis shows that the Li-composition in the depth direction also follows a complementary error function. The mean Li/Nb ratio in the waveguide layer is about 0.98. The inhomogeneous Li-composition profile results in a varied substrate index in the guiding layer, and the refractive index profile in the guiding layer is given.展开更多
基金the National Natural Science Foundation of China(10574058),Research Grants Council of Hong Kong,China(CityU1194/02E),and TWAS of UNESCO,Trieste,Italy,[RGA(01-137 RG/PHYS/AS)]
文摘为了解决大型回转支承背景噪声大,特征信号微弱,寿命状态难以识别等问题,提出了一种基于改进深度信念网络(Deep Belief Network,DBN)的回转支承寿命状态识别方法。DBN网络拥有强大的深度学习能力,能够有效挖掘回转支承运行状态信息,解决了传统浅层网络过度依赖特征提取效果和识别精度不高的问题。在DBN学习训练中,采用新的优化学习方法FEPCD(Free Energy in Persistent Contrastive Divergence),解决了DBN在长期学习中近似和分类能力下降的问题。然后利用自主研发试验台的试验数据对所提方法的优越性进行验证。将改进的DBN算法与浅层分类算法的识别结果进行比较。结果表明改进DBN网络比原始DBN网络和浅层算法能更精确反映回转支承寿命特征,所提方法具有稳定性和智能性的特点。
文摘The structure of a strip LiNbO3 waveguide clad with a planar LiNbOa waveguide is proposed to fabricate a long-period waveguide grating （LPWG）. It is shown theoretically that an LPWG device based on such a special LiNbOa waveguide structure is of the merit of thermal stability. The methods for fabrication of planar waveguide, channel waveguide and grating are suggested and discussed. Detailed design consideration is exemplified based on a soft-proton-exchange planar waveguide clad Ti-diffused LiNbOa （Z-cut） strip waveguide.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50872089 and 60577012)the Research Grants Council of the Hong Kong Special Administrative Region, China (Grant No. CityU 1194/07)
文摘We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical studies show that these waveguides are monomode at 1.5~／mu m and have losses of 1.3 and 1.1~dB/cm for the TM and TE modes, respectively. In the waveguide width/depth direction, the mode field follows a Gauss/Hermite--Gauss profile. A secondary ion mass spectrometry study reveals that the Ti profile follows a sum of two error functions along the width direction and a complementary error function in the depth direction. Micro-Raman analysis shows that the Li-composition in the depth direction also follows a complementary error function. The mean Li/Nb ratio in the waveguide layer is about 0.98. The inhomogeneous Li-composition profile results in a varied substrate index in the guiding layer, and the refractive index profile in the guiding layer is given.
