在工程实际中,设备数据样本往往以正常数据居多。故障样本稀缺且模态单一使得可用于训练的故障信息特征提取不足,同时训练和测试数据分布往往存在差异,从而导致模型迁移诊断能力较弱。针对该问题,提出将深度学习模型CNN与多模态融合迁...在工程实际中,设备数据样本往往以正常数据居多。故障样本稀缺且模态单一使得可用于训练的故障信息特征提取不足,同时训练和测试数据分布往往存在差异,从而导致模型迁移诊断能力较弱。针对该问题,提出将深度学习模型CNN与多模态融合迁移学习技术相结合(Deep Multimodal Fusion Transfer Learning,DMFTL)应用于轴承的故障诊断中。首先以CNN为基本学习框架,将原始一维振动信号的时域和频域进行多模态信息融合对模型预训练;然后以最大均值差异(MMD)为度量准则,通过域自适应来最小化源域和目标域的差异;最后引入构造的正则项到模型中,以完成跨域诊断。通过对CWRU轴承数据集的迁移诊断试验及对比分析,验证了该方法的有效性和优越性。展开更多
针对实际工程中目标样本通常无标签,而人工标记耗时耗力甚至无法实现造成诊断困难的问题,提出一种基于无监督多模态迁移学习诊断方法(unsupervised deep multimodal adaptive network,UDMAN)。首先,将完备丰富的实验数据作为源域,将其...针对实际工程中目标样本通常无标签,而人工标记耗时耗力甚至无法实现造成诊断困难的问题,提出一种基于无监督多模态迁移学习诊断方法(unsupervised deep multimodal adaptive network,UDMAN)。首先,将完备丰富的实验数据作为源域,将其时域和频域特征进行多模态信息融合以提取更全面的故障信息特征;其次,预训练深度迁移模型,共享模型的网络结构和参数;将缺乏标签样本的数据作为目标域,同时适配源域和率分布和条件概率分布以缩小两域之间的差异;最后,通过多次迭代优化迁移模型以实现跨域诊断。通过实验和对比分析,表明该方法可有效解决目标域无标签的难题,验证了该方法在齿轮箱无监督迁移诊断问题上的优越性。展开更多
Electrochemical capacitance-voltage profiling,Raman and absorption spectroscopy measurements are employed to characterize the electronic and optical properties of silicon supersaturated with sulfur above the equilibri...Electrochemical capacitance-voltage profiling,Raman and absorption spectroscopy measurements are employed to characterize the electronic and optical properties of silicon supersaturated with sulfur above the equilibrium solubility limit.Silicon wafers are ion implanted with 50keV 32S+ to a dose of 1 × 10^(16) ions/cm^(2) and subsequently irradiated by femtosecond pulses at a fluence of 0.2 J/cm^(2),followed by thermal annealing at 825K for 30min.The spectral response of the photodiode fabricated from the laser-irradiated sample is also investigated.It is found that femtosecond laser irradiation and subsequent thermal annealing can electrically and optically activate the supersaturated sulfur dopant in silicon,as well as reduce the implantation-induced damage in the silicon lattice.展开更多
Optical and electrical properties of single-crystal Si supersaturated with Se by ion implantation and followed by different thermal annealing conditions are reported.Si is implanted with 1×10^(16) cm^(-2) Se ions...Optical and electrical properties of single-crystal Si supersaturated with Se by ion implantation and followed by different thermal annealing conditions are reported.Si is implanted with 1×10^(16) cm^(-2) Se ions at 100 keV.The total substitutional fraction of Se atoms in Si is 45%under the annealing at 800℃ for 30 min and the peak concentration of substitutional Se atoms is exceeded 1×10^(20) cm^(-3).A temperature-independent carrier concentration of 3×10^(19) cm^(-3) is measured and the near-infrared absorption is closed to 30%.These results indicate the insulator-to-metal transition of the doped layer and the formation of impurity bands in the Si band gap.展开更多
To transfer a photon with a 1.55μm wavelength into an electron in an integrated optoelectronic silicon waveguide detector,selenium-doped silicon with deep energy levels is used.The deep levels in the silicon with imp...To transfer a photon with a 1.55μm wavelength into an electron in an integrated optoelectronic silicon waveguide detector,selenium-doped silicon with deep energy levels is used.The deep levels in the silicon with implanted selenium are studied.Three levels are observed and their captured cross sections,concentrations and in-depth profiles are measured.展开更多
Finish effect of four feeding patterns on weaned lamb was studied in the paper. The results showed that the performance of growing lambs by agricultural byproduct residual forage was superior to other feeding methods;...Finish effect of four feeding patterns on weaned lamb was studied in the paper. The results showed that the performance of growing lambs by agricultural byproduct residual forage was superior to other feeding methods; too high proportion of straw in diet was unfavorable for finish lamb, and corn straw should be combined with complete feed to get better feeding effect.展开更多
文摘在工程实际中,设备数据样本往往以正常数据居多。故障样本稀缺且模态单一使得可用于训练的故障信息特征提取不足,同时训练和测试数据分布往往存在差异,从而导致模型迁移诊断能力较弱。针对该问题,提出将深度学习模型CNN与多模态融合迁移学习技术相结合(Deep Multimodal Fusion Transfer Learning,DMFTL)应用于轴承的故障诊断中。首先以CNN为基本学习框架,将原始一维振动信号的时域和频域进行多模态信息融合对模型预训练;然后以最大均值差异(MMD)为度量准则,通过域自适应来最小化源域和目标域的差异;最后引入构造的正则项到模型中,以完成跨域诊断。通过对CWRU轴承数据集的迁移诊断试验及对比分析,验证了该方法的有效性和优越性。
文摘针对实际工程中目标样本通常无标签,而人工标记耗时耗力甚至无法实现造成诊断困难的问题,提出一种基于无监督多模态迁移学习诊断方法(unsupervised deep multimodal adaptive network,UDMAN)。首先,将完备丰富的实验数据作为源域,将其时域和频域特征进行多模态信息融合以提取更全面的故障信息特征;其次,预训练深度迁移模型,共享模型的网络结构和参数;将缺乏标签样本的数据作为目标域,同时适配源域和率分布和条件概率分布以缩小两域之间的差异;最后,通过多次迭代优化迁移模型以实现跨域诊断。通过实验和对比分析,表明该方法可有效解决目标域无标签的难题,验证了该方法在齿轮箱无监督迁移诊断问题上的优越性。
基金Supported by the National Natural Science Foundation of China under Grant Nos 60976046,60837001 and 61021003the National Basic Research Program of China under Grant No 2012CB934204.
文摘Electrochemical capacitance-voltage profiling,Raman and absorption spectroscopy measurements are employed to characterize the electronic and optical properties of silicon supersaturated with sulfur above the equilibrium solubility limit.Silicon wafers are ion implanted with 50keV 32S+ to a dose of 1 × 10^(16) ions/cm^(2) and subsequently irradiated by femtosecond pulses at a fluence of 0.2 J/cm^(2),followed by thermal annealing at 825K for 30min.The spectral response of the photodiode fabricated from the laser-irradiated sample is also investigated.It is found that femtosecond laser irradiation and subsequent thermal annealing can electrically and optically activate the supersaturated sulfur dopant in silicon,as well as reduce the implantation-induced damage in the silicon lattice.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60976046,60776046,60837001 and 61021003the National Basic Research Program of China(973 Program)(2010CB933800).
文摘Optical and electrical properties of single-crystal Si supersaturated with Se by ion implantation and followed by different thermal annealing conditions are reported.Si is implanted with 1×10^(16) cm^(-2) Se ions at 100 keV.The total substitutional fraction of Se atoms in Si is 45%under the annealing at 800℃ for 30 min and the peak concentration of substitutional Se atoms is exceeded 1×10^(20) cm^(-3).A temperature-independent carrier concentration of 3×10^(19) cm^(-3) is measured and the near-infrared absorption is closed to 30%.These results indicate the insulator-to-metal transition of the doped layer and the formation of impurity bands in the Si band gap.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60776046,60976046,60837001 and 61021003the National Basic Research Program of China under Grant Nos 2006CB302802 and 2010CB933800。
文摘To transfer a photon with a 1.55μm wavelength into an electron in an integrated optoelectronic silicon waveguide detector,selenium-doped silicon with deep energy levels is used.The deep levels in the silicon with implanted selenium are studied.Three levels are observed and their captured cross sections,concentrations and in-depth profiles are measured.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(201203050-4)Agricultural Science and Technology Innovation Funds of Jiangsu Province[CX(11)2050]
文摘Finish effect of four feeding patterns on weaned lamb was studied in the paper. The results showed that the performance of growing lambs by agricultural byproduct residual forage was superior to other feeding methods; too high proportion of straw in diet was unfavorable for finish lamb, and corn straw should be combined with complete feed to get better feeding effect.
