In situ U-Pb dating of carbonates is very common in the fields of mining and petroleum geology.However,carbonate minerals generally have low U,high common Pb,multiple generations,and uneven elemental distribution,ofte...In situ U-Pb dating of carbonates is very common in the fields of mining and petroleum geology.However,carbonate minerals generally have low U,high common Pb,multiple generations,and uneven elemental distribution,often resulting in relatively low dating precision.Hence,the success rate in U-Pb dating of carbonates by the traditional spot analysis method is generally low.This paper,through combining a mapping method for U-Pb dating with a proprietary visualization and analysis software,ChronoVA,conducted a comparison of the data obtained by both the spot analysis and the mapping method for 3carbonate standards and 2 unknown natural geological samples.We successfully developed a U-Pb dating method for carbonate rocks via LA-SF-ICP-MS elemental mapping and discussed the advantages and limitations of this method.Results show that in comparison with the traditional spot analysis method,the mapping approach has the following advantages:(1)reducing the downhole fractionation effect;(2)simplifying the analytical processes;(3)the elemental imaging data can help to identify multigeneration and mineral inclusions,ensuring the obtained carbonate U-Pb age having an interpretable geological meaning;(4)a large amount of mapping data can significantly improve the accuracy of the dating results.Despite these advantages,in carbonate samples with extremely high common Pb content and high Pb/U ratio,it might be difficult to obtain reliable ages even via the mapping method.In addition,it was understood that the carbonate standard WC-1,which is the most commonly used at present,could be inhomogeneous,and on occasion does not satisfy the SK model in spot analysis.展开更多
Resonant metasurfaces provide a promising solution to overcome the limitations of nonlinear materials in nature by enhancing the interaction between light and matter and amplifying optical nonlinearity.In this paper,w...Resonant metasurfaces provide a promising solution to overcome the limitations of nonlinear materials in nature by enhancing the interaction between light and matter and amplifying optical nonlinearity.In this paper,we design an aluminum(Al)metasurface that supports surface lattice resonance(SLR)with less nanoparticle filling density but more prominent saturable absorption effects,in comparison to a counterpart that supports localized surface plasmon resonance(LSPR).In detail,the SLR metasurface exhibits a narrower resonance linewidth and a greater near-field enhancement,leading to a more significant modulation depth(9.6%)at a low incident fluence of 25μJ∕cm^(2).As an application example,we have further achieved wavelength-tunable Q-switched pulse generation from 1020 to 1048 nm by incorporating the SLR-based Al metasurface as a passive saturable absorber(SA)in a polarization-maintaining ytterbium-doped fiber laser.Typically,the Q-switched pulse with a repetition rate of 33.7 kHz,pulse width of 2.1μs,pulse energy of 141.7 nJ,and signal-to-noise ratio(SNR)of greater than 40 dB at the fundamental frequency can be obtained.In addition,we have investigated the effects of pump power and central wavelength of the filter on the repetition rate and pulse width of output pulses,respectively.In spite of demonstration of only using the Al metasurface to achieve a passive Q-switched fiber laser,our work offers an alternative scheme to build planar,lightweight,and broadband SA devices that could find emerging applications from ultrafast optics to neuromorphic photonics,considering the fast dynamics,CMOScompatible fabrication,and decent nonlinear optical response of Al-material-based nanoplasmonics.展开更多
In situ carbonate U-Pb dating is gaining popularity,and it has great potential for application in petroleum geology.However,the low U content(<10μg/g)and high common Pb content of carbonate minerals,along with the...In situ carbonate U-Pb dating is gaining popularity,and it has great potential for application in petroleum geology.However,the low U content(<10μg/g)and high common Pb content of carbonate minerals,along with the uneven distribution of U and Pb and the lack of matrix-matched reference material make carbonate U-Pb dating inaccurate and less successful,which limits the widespread application in geosciences.This study evaluated the limitations of in situ carbonate U-Pb dating and proposed a method to rationally determine the laser ablation parameters of samples by improving the experimental approach based on the laser ablation sector field inductively coupled plasma mass spectrometry(LA-SF-ICP-MS).By setting a different spot size and laser frequency for the reference material and unknown samples in the same session based on the U content of the sample,the ablation craters of the reference material and unknown samples were given the same depth/width ratio,avoiding systematic offset caused by differences in down-hole element fractionation and reducing the consume of reference material.Depending on the heterogeneous distribution of U and Pb contents in carbonate minerals,the method of grid screening and setting ablation spots during screening were used to quickly select domains with high U and low common Pb,which improves the efficiency of setting laser spots and the success rate of dating,as well as reduces the experimental time and economic cost.The accuracy and success rate of carbonate U-Pb dating were effectively improved by improving the experimental method,and the technique was applied to two carbonate samples with low U and high common Pb contents that were difficult to date by traditional methods.The two samples are the saddle dolomite in the central Sichuan Basin and the calcite cement in the sandstone reservoir of the Cretaceous Qingshuihe Formation in the South Junggar Basin.The robust ages have been obtained,which constrains the timing of the diagenetic and hydrocarbon accumulation process in the studied area.展开更多
The analog photonics link(APL) is widely used in microwave photonics. However, in wideband and multi-carrier systems, the third inter-modulation distortion(IMD3) and cross-modulation distortion(XMD) will jointly limit...The analog photonics link(APL) is widely used in microwave photonics. However, in wideband and multi-carrier systems, the third inter-modulation distortion(IMD3) and cross-modulation distortion(XMD) will jointly limit the spurious-free dynamic range(SFDR) of links. In this paper, we experimentally present a linearized wideband and multi-carrier APL, in which the IMD3 and XMD are mitigated simultaneously by using artificial neural networks with transfer learning(TL-ANN). In this experiment, with different artificial neural networks, which are trained with the knowledge obtained from the two-or three-sub-carrier system, the IMD3 and XMD are suppressed by 21.71 d B and 11.11 d B or 22.38 d B and 16.73 d B, and the SFDR is improved by 13.4 d B or 14.3 d B, respectively. Meanwhile, compared with previous studies, this method could reduce the training time and training epochs to 16% and 25%.展开更多
基金supported financially by the National Natural Science Foundation of China(Grant Nos.42472216,42273061 and U22B6002)the Science and Technology Development Program of Petro China Company Limited(Grant Nos.2023ZZ0206 and 2021DJ0105)。
文摘In situ U-Pb dating of carbonates is very common in the fields of mining and petroleum geology.However,carbonate minerals generally have low U,high common Pb,multiple generations,and uneven elemental distribution,often resulting in relatively low dating precision.Hence,the success rate in U-Pb dating of carbonates by the traditional spot analysis method is generally low.This paper,through combining a mapping method for U-Pb dating with a proprietary visualization and analysis software,ChronoVA,conducted a comparison of the data obtained by both the spot analysis and the mapping method for 3carbonate standards and 2 unknown natural geological samples.We successfully developed a U-Pb dating method for carbonate rocks via LA-SF-ICP-MS elemental mapping and discussed the advantages and limitations of this method.Results show that in comparison with the traditional spot analysis method,the mapping approach has the following advantages:(1)reducing the downhole fractionation effect;(2)simplifying the analytical processes;(3)the elemental imaging data can help to identify multigeneration and mineral inclusions,ensuring the obtained carbonate U-Pb age having an interpretable geological meaning;(4)a large amount of mapping data can significantly improve the accuracy of the dating results.Despite these advantages,in carbonate samples with extremely high common Pb content and high Pb/U ratio,it might be difficult to obtain reliable ages even via the mapping method.In addition,it was understood that the carbonate standard WC-1,which is the most commonly used at present,could be inhomogeneous,and on occasion does not satisfy the SK model in spot analysis.
基金National Natural Science Foundation of China(61905018)Fundamental Research Funds for the Central Universities(ZDYY202102)+2 种基金Beijing Nova Program of Science and Technology(Z191100001119110)State Key Laboratory of Information Photonics and Optical Communications(IPOC2021ZR02)BUPT Excellent Ph.D.Students Foundation(CX20241034)。
文摘Resonant metasurfaces provide a promising solution to overcome the limitations of nonlinear materials in nature by enhancing the interaction between light and matter and amplifying optical nonlinearity.In this paper,we design an aluminum(Al)metasurface that supports surface lattice resonance(SLR)with less nanoparticle filling density but more prominent saturable absorption effects,in comparison to a counterpart that supports localized surface plasmon resonance(LSPR).In detail,the SLR metasurface exhibits a narrower resonance linewidth and a greater near-field enhancement,leading to a more significant modulation depth(9.6%)at a low incident fluence of 25μJ∕cm^(2).As an application example,we have further achieved wavelength-tunable Q-switched pulse generation from 1020 to 1048 nm by incorporating the SLR-based Al metasurface as a passive saturable absorber(SA)in a polarization-maintaining ytterbium-doped fiber laser.Typically,the Q-switched pulse with a repetition rate of 33.7 kHz,pulse width of 2.1μs,pulse energy of 141.7 nJ,and signal-to-noise ratio(SNR)of greater than 40 dB at the fundamental frequency can be obtained.In addition,we have investigated the effects of pump power and central wavelength of the filter on the repetition rate and pulse width of output pulses,respectively.In spite of demonstration of only using the Al metasurface to achieve a passive Q-switched fiber laser,our work offers an alternative scheme to build planar,lightweight,and broadband SA devices that could find emerging applications from ultrafast optics to neuromorphic photonics,considering the fast dynamics,CMOScompatible fabrication,and decent nonlinear optical response of Al-material-based nanoplasmonics.
基金supported by the Scientific Research and Technological Development Project of China National Petroleum Corporation (Grant Nos.2021DJ0105,2021DJ0203,2021DJ0303)the National Natural Science Foundation of China (Grant Nos.42172164,42002177)。
文摘In situ carbonate U-Pb dating is gaining popularity,and it has great potential for application in petroleum geology.However,the low U content(<10μg/g)and high common Pb content of carbonate minerals,along with the uneven distribution of U and Pb and the lack of matrix-matched reference material make carbonate U-Pb dating inaccurate and less successful,which limits the widespread application in geosciences.This study evaluated the limitations of in situ carbonate U-Pb dating and proposed a method to rationally determine the laser ablation parameters of samples by improving the experimental approach based on the laser ablation sector field inductively coupled plasma mass spectrometry(LA-SF-ICP-MS).By setting a different spot size and laser frequency for the reference material and unknown samples in the same session based on the U content of the sample,the ablation craters of the reference material and unknown samples were given the same depth/width ratio,avoiding systematic offset caused by differences in down-hole element fractionation and reducing the consume of reference material.Depending on the heterogeneous distribution of U and Pb contents in carbonate minerals,the method of grid screening and setting ablation spots during screening were used to quickly select domains with high U and low common Pb,which improves the efficiency of setting laser spots and the success rate of dating,as well as reduces the experimental time and economic cost.The accuracy and success rate of carbonate U-Pb dating were effectively improved by improving the experimental method,and the technique was applied to two carbonate samples with low U and high common Pb contents that were difficult to date by traditional methods.The two samples are the saddle dolomite in the central Sichuan Basin and the calcite cement in the sandstone reservoir of the Cretaceous Qingshuihe Formation in the South Junggar Basin.The robust ages have been obtained,which constrains the timing of the diagenetic and hydrocarbon accumulation process in the studied area.
基金This work was supported in part by the National Key R&D Program of China(No.2019YFB1803504)National Natural Science Foundation of China(Nos.61901045,61821001,and 61625104)+1 种基金Fundamental Research Funds for the Central Universities(No.2019RC11)State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications)(No.IPOC2019ZT04)。
文摘The analog photonics link(APL) is widely used in microwave photonics. However, in wideband and multi-carrier systems, the third inter-modulation distortion(IMD3) and cross-modulation distortion(XMD) will jointly limit the spurious-free dynamic range(SFDR) of links. In this paper, we experimentally present a linearized wideband and multi-carrier APL, in which the IMD3 and XMD are mitigated simultaneously by using artificial neural networks with transfer learning(TL-ANN). In this experiment, with different artificial neural networks, which are trained with the knowledge obtained from the two-or three-sub-carrier system, the IMD3 and XMD are suppressed by 21.71 d B and 11.11 d B or 22.38 d B and 16.73 d B, and the SFDR is improved by 13.4 d B or 14.3 d B, respectively. Meanwhile, compared with previous studies, this method could reduce the training time and training epochs to 16% and 25%.
