Multi-band optical networks are a potential technology for increasing network capacity.However,the strong interference and non-uniformity between wavelengths in multi-band optical networks have become a bottleneck res...Multi-band optical networks are a potential technology for increasing network capacity.However,the strong interference and non-uniformity between wavelengths in multi-band optical networks have become a bottleneck restricting the transmission capacity of multi-band optical networks.To overcome these challenges,it is particularly important to implement optical power optimization targeting wavelength differences.Therefore,based on the generalized Gaussian noise model,we first formulate an optimization model for the problems of routing,modulation format,wavelength,and power allocation in C+L+S multi-band optical networks.Our objective function is to maximize the average link capacity of the network while ensuring that the Optical Signal-to-Noise(OSNR)threshold of the service request is not exceeded.Next,we propose a NonLinear Interferenceaware(NLI-aware)routing,modulation format,wavelength,and power allocation algorithm.Finally,we conduct simulations under different test conditions.The simulation results indicate that our algorithm can effectively reduce the blocking probability by 23.5%and improve the average link capacity by 3.78%in C+L+S multi-band optical networks.展开更多
Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims ...Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims to mitigate far-field noise.Among these cases,a reduction in the wavelength is found to be advantageous for noise suppression,with the smallest wavelength case achieving a maximum noise reduction of 1.9 dB.Furthermore,the noise radiation induced by WLEs is suppressed mainly at medium frequencies.The theory of multiprocess aeroacoustics is applied to reveal their underlying mechanisms.The dominant factor is the source cutoff effect,which significantly decreases the source strength on hills.Additionally,spanwise decoherence with phase interference serves as another crucial mechanism,particularly for reducing mid-frequency noise.展开更多
The purpose of this study is to analyze the impact of upper ocean dynamics on velocity bunching,represented by az-imuthal cutoff wavelength(i.e.,sea surface wind,wave,and current).In this study,over 1400 dual-polarize...The purpose of this study is to analyze the impact of upper ocean dynamics on velocity bunching,represented by az-imuthal cutoff wavelength(i.e.,sea surface wind,wave,and current).In this study,over 1400 dual-polarized(vertical-vertical(VV)and vertical-horizontal(VH))Sentinel-1(S-1)synthetic aperture radar(SAR)images collected in tropical cyclones(TC)are utilized.These images are combined with wind and rain observations from the stepped-frequency microwave radiometer(SFMR),wave simu-lations conducted using a third-generation numerical wave model,WAVEWATCH-III(WW3),and SAR-derived wind information collected from CyclObs winds.The WW3-simulated significant wave height(SWH)is validated against measurements from HY-2B altimeter taken in August and September 2021,yielding a root mean square error(RMSE)of 0.48 m and a correlation coefficient(COR)of 0.88.The SAR-based azimuthal cutoff wavelengths in VV polarization,which quantitatively represent the effect of velocity bunching,are compared with theoretical values calculated using WW3-simulated SWH.A notable relationship is observed between the difference in azimuthal cutoff wavelength and SAR-derived wind speed and WW3-simulated SWH.Analysis results show that the correlation between SAR-based azimuthal cutoff wavelength and SWH is stronger than that with wind and current.Finally,a machine learning algorithm is used to develop an algorithm aimed at simulating the azimuthal cutoff wavelength in TCs,including wind,wave,and incidence angle.This method yields an RMSE of 8.90 m,a COR of 0.91,and a scatter index of 0.04 for VV-polar-ization SAR.展开更多
Through active manipulation of wavelengths,a structure exposed to a water-wave field can achieve a target hydrodynamic performance.Based on the form invariance of the governing equation for shallow water waves,wavelen...Through active manipulation of wavelengths,a structure exposed to a water-wave field can achieve a target hydrodynamic performance.Based on the form invariance of the governing equation for shallow water waves,wavelength modulators have been proposed using the space transformation method,which enables wavelength manipulation by distributing an anisotropic medium that incorporates water depth and gravitational acceleration within the modulation space.First,annular wavelength modulators were designed using the space transformation method to reduce or amplify the wavelength of shallow water waves.The control method of wavelength scaling ratios was investigated.In addition to plane waves,the wavelength modulator was applied to manipulate the wavelength of cylindrical waves.Furthermore,the interactions between a vertical cylinder and modulated water waves were studied.Results indicate that the wavelength can be arbitrarily reduced or amplified by adjusting the dimensional parameters of the modulator.Additionally,the modulator is effective for plane waves and cylindrical waves.This wavelength modulator can enable the structure to achieve the desired scattering characteristics at the target wavelength.展开更多
Chemical oxygen demand(COD)is an important criterion for detecting the emission of pollutants and judging the quality of water.This paper improves the absorption spectrum compensation model for COD and turbidity mixed...Chemical oxygen demand(COD)is an important criterion for detecting the emission of pollutants and judging the quality of water.This paper improves the absorption spectrum compensation model for COD and turbidity mixed solution in the dual-wavelength spectral method based on the Lambert-Beer law additive principle.It compensates for the influence of turbidity on the absorption coefficient of the COD solution at 355 nm by the absorption spectrum coefficient of the mixed solution at 623 nm.This paper establishes a linear relationship model between the absorbance difference of the mixed solution at 355 nm and 623 nm and COD.The experimental determination coefficient R2 of the model is 0.98335,with a relative error of 3.5%and an average error of 0.7 mg/L.The design of the model is simple and easy to systematize,which is of strong significance for practical application.展开更多
This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utiliz...This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utilizes a cascaded and parallel configuration of three Lyot filters, facilitated by a polarization beam splitter(PBS) for branch switching. The transmission properties of the filter are analyzed through theoretical modeling and experimental validation using the transmission matrix method. The experimental results are found to be consistent with the theoretical predictions, demonstrating the effectiveness of the proposed design. By adjusting the polarization controllers(PCs), the proposed laser can switch between wavelength spacings of 0.46 nm, 0.27 nm, and 0.76 nm, with a maximum optical signal-to-noise ratio(OSNR) of 38 d B. However, the stability of the laser with a 0.27 nm spacing is not high due to wavelength competition. Power fluctuation for 0.46 nm and 0.76 nm intervals is less than 0.93 d B and 0.78 d B in 1 h, with wavelength fluctuation less than 0.068 nm and 0.19 nm, respectively. This EDFL has the advantages of simple structure, great flexibility, and switchability, which can be applied to fiber optic sensing, wavelength division multiplexing(WDM) networks, and other fields that require a very flexible light source.展开更多
The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the pla...The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the plasma acceleration phase,shorter wavelengths lead to more efficien coupling between the laser and the kinetic energy of the implosion fluid Under the condition that the laser energy coupled to the implosion flui is constant,the ARTI growth rate decreases as the laser wavelength moves toward the extreme ultraviolet band,reaching its minimum value near λ=65 nm,and when the laser wavelength continuously moves toward the X-ray band,the ARTI growth rate increases rapidly.It is found that the results deviate from the theoretical ARTI growth rate.As the laser intensity benchmark increases,the position of the minimum ARTI growth rate shifts toward shorter wavelengths.As the initial sinusoidal perturbation wavenumber decreases,the position of the minimum ARTI growth rate shifts toward longer wavelengths.We believe that the conclusions drawn from the present simulations and analysis will help provide a better understanding of the ICF process and improve the theory of ARTI growth.展开更多
A dual-wavelength ring-cavity erbium-doped fiber(EDF)laser is designed based on two polarization beam splitters(PBSs)and a polarization controller(PC)performing gain equalization and polarization hole burning(PHB)effe...A dual-wavelength ring-cavity erbium-doped fiber(EDF)laser is designed based on two polarization beam splitters(PBSs)and a polarization controller(PC)performing gain equalization and polarization hole burning(PHB)effect.At room temperature,a stable dual-wavelength laser and a multi-output port laser which can simultaneously emit single-wavelength lasing and dual-wavelength lasing are obtained.The signal-to-noise ratios(SNRs)for single-wavelength outputs were 54.70 dB and 57.10 dB,with power fluctuations less than 0.038 mW and 0.029 mW,respectively.For dual-wavelength lasing,the SNRs were 59.63 dB and 59.25 dB,with power fluctuations less than 0.018 mW and 0.008 mW,respectively.The center wavelength drift was less than 0.006 nm for both single-wavelength and dual-wavelength outputs.展开更多
基金supported in part by the National Natural Science Foundation of China under Grants U21B2005,62201105,62331017,U24B20134,62222103,and 62025105in part by the Chongqing Municipal Education Commission under Grants KJQN202400621,KJQN202100643,and KJZDK202400608+1 种基金in part by the China Postdoctoral Science Foundation under Grant 2021M700563in part by the Chongqing Postdoctoral Funding Project under Grant 2021XM3052。
文摘Multi-band optical networks are a potential technology for increasing network capacity.However,the strong interference and non-uniformity between wavelengths in multi-band optical networks have become a bottleneck restricting the transmission capacity of multi-band optical networks.To overcome these challenges,it is particularly important to implement optical power optimization targeting wavelength differences.Therefore,based on the generalized Gaussian noise model,we first formulate an optimization model for the problems of routing,modulation format,wavelength,and power allocation in C+L+S multi-band optical networks.Our objective function is to maximize the average link capacity of the network while ensuring that the Optical Signal-to-Noise(OSNR)threshold of the service request is not exceeded.Next,we propose a NonLinear Interferenceaware(NLI-aware)routing,modulation format,wavelength,and power allocation algorithm.Finally,we conduct simulations under different test conditions.The simulation results indicate that our algorithm can effectively reduce the blocking probability by 23.5%and improve the average link capacity by 3.78%in C+L+S multi-band optical networks.
基金supported by the National Natural Science Foundation of China(12322210,12172351,92252202,and 12388101)the Fundamental Research Funds for the Central Universities.
文摘Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims to mitigate far-field noise.Among these cases,a reduction in the wavelength is found to be advantageous for noise suppression,with the smallest wavelength case achieving a maximum noise reduction of 1.9 dB.Furthermore,the noise radiation induced by WLEs is suppressed mainly at medium frequencies.The theory of multiprocess aeroacoustics is applied to reveal their underlying mechanisms.The dominant factor is the source cutoff effect,which significantly decreases the source strength on hills.Additionally,spanwise decoherence with phase interference serves as another crucial mechanism,particularly for reducing mid-frequency noise.
基金supported by the National Natural Science Foundation of China(Nos.42076238,42376174)the Natural Science Foundation of Shanghai(No.23ZR1426900).
文摘The purpose of this study is to analyze the impact of upper ocean dynamics on velocity bunching,represented by az-imuthal cutoff wavelength(i.e.,sea surface wind,wave,and current).In this study,over 1400 dual-polarized(vertical-vertical(VV)and vertical-horizontal(VH))Sentinel-1(S-1)synthetic aperture radar(SAR)images collected in tropical cyclones(TC)are utilized.These images are combined with wind and rain observations from the stepped-frequency microwave radiometer(SFMR),wave simu-lations conducted using a third-generation numerical wave model,WAVEWATCH-III(WW3),and SAR-derived wind information collected from CyclObs winds.The WW3-simulated significant wave height(SWH)is validated against measurements from HY-2B altimeter taken in August and September 2021,yielding a root mean square error(RMSE)of 0.48 m and a correlation coefficient(COR)of 0.88.The SAR-based azimuthal cutoff wavelengths in VV polarization,which quantitatively represent the effect of velocity bunching,are compared with theoretical values calculated using WW3-simulated SWH.A notable relationship is observed between the difference in azimuthal cutoff wavelength and SAR-derived wind speed and WW3-simulated SWH.Analysis results show that the correlation between SAR-based azimuthal cutoff wavelength and SWH is stronger than that with wind and current.Finally,a machine learning algorithm is used to develop an algorithm aimed at simulating the azimuthal cutoff wavelength in TCs,including wind,wave,and incidence angle.This method yields an RMSE of 8.90 m,a COR of 0.91,and a scatter index of 0.04 for VV-polar-ization SAR.
基金supported by National Key R&D Program of China(2022YFC3104200)the China Postdoctoral Science Foundation(2023M742157)+3 种基金the Shandong Province Taishan Scholars Project(tsqn201909172)the Shandong Provincial Natural Science Foundation(ZR2023QA097)the Open Research Fund Program of State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology(LP2309)the Innovation Project of Qingdao Post-Doctoral(QDBSH20230202121).
文摘Through active manipulation of wavelengths,a structure exposed to a water-wave field can achieve a target hydrodynamic performance.Based on the form invariance of the governing equation for shallow water waves,wavelength modulators have been proposed using the space transformation method,which enables wavelength manipulation by distributing an anisotropic medium that incorporates water depth and gravitational acceleration within the modulation space.First,annular wavelength modulators were designed using the space transformation method to reduce or amplify the wavelength of shallow water waves.The control method of wavelength scaling ratios was investigated.In addition to plane waves,the wavelength modulator was applied to manipulate the wavelength of cylindrical waves.Furthermore,the interactions between a vertical cylinder and modulated water waves were studied.Results indicate that the wavelength can be arbitrarily reduced or amplified by adjusting the dimensional parameters of the modulator.Additionally,the modulator is effective for plane waves and cylindrical waves.This wavelength modulator can enable the structure to achieve the desired scattering characteristics at the target wavelength.
基金supported by the Youth Project of National Natural Science Foundation of China(No.61505145)the Tianjin Science and Technology Commissioner Project(No.20YDTPJC02010)+1 种基金the Tianjin Municipal Education Commission(No.2021KJ003)the Tianjin Zhonghuan Tianjia Electronics Company(No.HX20193)。
文摘Chemical oxygen demand(COD)is an important criterion for detecting the emission of pollutants and judging the quality of water.This paper improves the absorption spectrum compensation model for COD and turbidity mixed solution in the dual-wavelength spectral method based on the Lambert-Beer law additive principle.It compensates for the influence of turbidity on the absorption coefficient of the COD solution at 355 nm by the absorption spectrum coefficient of the mixed solution at 623 nm.This paper establishes a linear relationship model between the absorbance difference of the mixed solution at 355 nm and 623 nm and COD.The experimental determination coefficient R2 of the model is 0.98335,with a relative error of 3.5%and an average error of 0.7 mg/L.The design of the model is simple and easy to systematize,which is of strong significance for practical application.
基金supported by the Primary Research and Development Plan of Zhejiang Province (No.2023C03014)the Key Research and Development Program of Zhejiang Province (No.2022C03037)。
文摘This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utilizes a cascaded and parallel configuration of three Lyot filters, facilitated by a polarization beam splitter(PBS) for branch switching. The transmission properties of the filter are analyzed through theoretical modeling and experimental validation using the transmission matrix method. The experimental results are found to be consistent with the theoretical predictions, demonstrating the effectiveness of the proposed design. By adjusting the polarization controllers(PCs), the proposed laser can switch between wavelength spacings of 0.46 nm, 0.27 nm, and 0.76 nm, with a maximum optical signal-to-noise ratio(OSNR) of 38 d B. However, the stability of the laser with a 0.27 nm spacing is not high due to wavelength competition. Power fluctuation for 0.46 nm and 0.76 nm intervals is less than 0.93 d B and 0.78 d B in 1 h, with wavelength fluctuation less than 0.068 nm and 0.19 nm, respectively. This EDFL has the advantages of simple structure, great flexibility, and switchability, which can be applied to fiber optic sensing, wavelength division multiplexing(WDM) networks, and other fields that require a very flexible light source.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.12074399,12204500,and 12004403)the Key Projects of the Intergovernmental International Scientifi and Technological Innovation Cooperation(Grant No.2021YFE0116700)+1 种基金the Shanghai Natural Science Foundation(Grant No.20ZR1464400)the Shanghai Sailing Program(Grant No.22YF1455300)。
文摘The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the plasma acceleration phase,shorter wavelengths lead to more efficien coupling between the laser and the kinetic energy of the implosion fluid Under the condition that the laser energy coupled to the implosion flui is constant,the ARTI growth rate decreases as the laser wavelength moves toward the extreme ultraviolet band,reaching its minimum value near λ=65 nm,and when the laser wavelength continuously moves toward the X-ray band,the ARTI growth rate increases rapidly.It is found that the results deviate from the theoretical ARTI growth rate.As the laser intensity benchmark increases,the position of the minimum ARTI growth rate shifts toward shorter wavelengths.As the initial sinusoidal perturbation wavenumber decreases,the position of the minimum ARTI growth rate shifts toward longer wavelengths.We believe that the conclusions drawn from the present simulations and analysis will help provide a better understanding of the ICF process and improve the theory of ARTI growth.
基金supported by the Key Scientific Research Project of Hunan Education Department,China(No.23A0446)the Natural Science Foundation of Hunan Province,China(provinces and cities combined)(No.2022JJ50067)+1 种基金the Hunan Province Degree and Postgraduate Teaching Reform Research Project,China(No.2022JGYB182)the Scientific Research and Innovation Foundation of Hunan University of Technology(No.CX2314).
文摘A dual-wavelength ring-cavity erbium-doped fiber(EDF)laser is designed based on two polarization beam splitters(PBSs)and a polarization controller(PC)performing gain equalization and polarization hole burning(PHB)effect.At room temperature,a stable dual-wavelength laser and a multi-output port laser which can simultaneously emit single-wavelength lasing and dual-wavelength lasing are obtained.The signal-to-noise ratios(SNRs)for single-wavelength outputs were 54.70 dB and 57.10 dB,with power fluctuations less than 0.038 mW and 0.029 mW,respectively.For dual-wavelength lasing,the SNRs were 59.63 dB and 59.25 dB,with power fluctuations less than 0.018 mW and 0.008 mW,respectively.The center wavelength drift was less than 0.006 nm for both single-wavelength and dual-wavelength outputs.
