In this paper,we have proposed and demonstrated the generation of passively mode-locked pulses and dissipative soliton resonance in an erbium-doped fiber laser based on Fe3O4 nanoparticles as saturable absorbers.We ob...In this paper,we have proposed and demonstrated the generation of passively mode-locked pulses and dissipative soliton resonance in an erbium-doped fiber laser based on Fe3O4 nanoparticles as saturable absorbers.We obtained self-starting mode-locked pulses with fundamental repetition frequency of 7.69 MHz and center wavelength of 1561 nm.The output of a pulsed laser has spectral width of 0.69 nm and pulse duration of 14 ns with rectangular pulse profile at the pump power of 190 mW.As far as we know,this is the first time that Fe3O4 nanoparticles have been developed as low-dimensional materials for passive mode-locking with rectangular pulse.Our experiments have confirmed that Fe3O4 has a wide prospect as a nonlinear photonics device for ultrafast fiber laser applications.展开更多
The pore-scale mechanism of the waterflooding contributes to enhancing oil recovery,which has been widely emphasized in the petroleum industry.In this paper,the performances and accuracy of three tracking interface al...The pore-scale mechanism of the waterflooding contributes to enhancing oil recovery,which has been widely emphasized in the petroleum industry.In this paper,the performances and accuracy of three tracking interface algorithms,including VOF,LS,and VOSET,are compared and analyzed through twophase flow in the conceptual model of pore-throat.The results show that the VOSET method combines the advantages of the other two methods,which not only satisfies the mass conservation but also improves the continuity of the physical quantities near the interface.Then,based on the binary image of the pore,the two-dimensional micro pore model is reconstructed by extracting image contour.The grid independence of the reconstructed pore model is verified by the single-phase flow simulation.The waterflooding process in the reconstructed pore model is simulated using the VOSET method,and the effects of displacement speed and wettability on the oil recovery are analyzed.The morphologies of residual oil under different conditions of wettability are investigated and analyzed.The study provides a basic theory for modeling the pore-scale oil-water flow and optimizing the scheme of the water injection.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.61605106)Funded projects for the Academic Leader and Academic Backbones,Shaanxi Normal University(No.18QNGG006)+3 种基金Shaanxi International Cooperation Project(No.2020KW-005)Starting Grants of Shaanxi Normal University(Nos.1112010209 and 1110010717)Open Research Fund of State Key Laboratory of Transient Optics and Photonics,Chinese Academy of Sciences(No.SKLST201809)Fundamental Research Funds for the Central Universities(Nos.GK201802006 and 2018CSLY005).
文摘In this paper,we have proposed and demonstrated the generation of passively mode-locked pulses and dissipative soliton resonance in an erbium-doped fiber laser based on Fe3O4 nanoparticles as saturable absorbers.We obtained self-starting mode-locked pulses with fundamental repetition frequency of 7.69 MHz and center wavelength of 1561 nm.The output of a pulsed laser has spectral width of 0.69 nm and pulse duration of 14 ns with rectangular pulse profile at the pump power of 190 mW.As far as we know,this is the first time that Fe3O4 nanoparticles have been developed as low-dimensional materials for passive mode-locking with rectangular pulse.Our experiments have confirmed that Fe3O4 has a wide prospect as a nonlinear photonics device for ultrafast fiber laser applications.
基金by the National Natural Science Foundation of China(Grant Number 51909225)National Major Science and Technology Projects of China(Grant Number 2017ZX05013001-002)Open research fund of CNPC(grant No.2018A-0908),and the Natural Science Foundation of SWUST(Grant Number 20zx7129).
文摘The pore-scale mechanism of the waterflooding contributes to enhancing oil recovery,which has been widely emphasized in the petroleum industry.In this paper,the performances and accuracy of three tracking interface algorithms,including VOF,LS,and VOSET,are compared and analyzed through twophase flow in the conceptual model of pore-throat.The results show that the VOSET method combines the advantages of the other two methods,which not only satisfies the mass conservation but also improves the continuity of the physical quantities near the interface.Then,based on the binary image of the pore,the two-dimensional micro pore model is reconstructed by extracting image contour.The grid independence of the reconstructed pore model is verified by the single-phase flow simulation.The waterflooding process in the reconstructed pore model is simulated using the VOSET method,and the effects of displacement speed and wettability on the oil recovery are analyzed.The morphologies of residual oil under different conditions of wettability are investigated and analyzed.The study provides a basic theory for modeling the pore-scale oil-water flow and optimizing the scheme of the water injection.
