Recently,we demonstrated the success of a time-synchronized state estimator using deep neural networks(DNNs)for real-time unobservable distribution systems.In this paper,we provide analytical bounds on the performance...Recently,we demonstrated the success of a time-synchronized state estimator using deep neural networks(DNNs)for real-time unobservable distribution systems.In this paper,we provide analytical bounds on the performance of the state estimator as a function of perturbations in the input measurements.It has already been shown that evaluating performance based only on the test dataset might not effectively indicate the ability of a trained DNN to handle input perturbations.As such,we analytically verify the robustness and trustworthiness of DNNs to input perturbations by treating them as mixed-integer linear programming(MILP)problems.The ability of batch normalization in addressing the scalability limitations of the MILP formulation is also highlighted.The framework is validated by performing time-synchronized distribution system state estimation for a modified IEEE 34-node system and a real-world large distribution system,both of which are incompletely observed by micro-phasor measurement units.展开更多
Lasers with high average and high peak power as well as ultrashort pulse width have been all along demanded by nonlinear optics studies,strong-field experiments,electron dynamics investigations,and ultrafast spectrosc...Lasers with high average and high peak power as well as ultrashort pulse width have been all along demanded by nonlinear optics studies,strong-field experiments,electron dynamics investigations,and ultrafast spectroscopy.While the routinely used titanium-doped sapphire(Ti:sapphire)laser faces a bottleneck in the average power upscaling,ytterbium(Yb)-doped lasers have remarkable advantages in achieving high average power.However,there is still a substantial gap of pulse width and peak power between the Ti:sapphire and Yb-doped lasers.Here we demonstrate a high-power Yb:CaAlGdO4(Yb:CALGO)regenerative amplifier system,delivering 1040 nm pulses with11 W average power,50 fs pulse width,and 3.7 GW peak power at a repetition rate of 43 k Hz,which to some extent bridges the gap between the Ti:sapphire and Yb lasers.An ultrabroadband Yb-doped fiber oscillator,specially designed spectral shapers,and Yb:CALGO gain medium with broad emission bandwidth,together with a double-end pumping scheme enable an amplified bandwidth of 19 nm and 95 fs output pulse width.To the best of our knowledge,this is the first demonstration of sub-100 fs regenerative amplifier based on Yb-doped bulk medium without nonlinear spectral broadening.The amplified pulse is further compressed to 50 fs via cascaded-quadratic compression with a simple setup,producing 3.7 GW peak power,which boosts the record of peak power from Yb:CALGO regenerative amplifiers by 1 order.As a proof of concept,pumped by the high-power,50 fs pulses,7.5–11.5μm midinfrared(MIR)generation via intrapulse difference-frequency generation is performed,without the necessity of nonlinear fiber compressors.It leads to a simple and robust apparatus,and it would find good usefulness in MIR spectroscopic applications.展开更多
Aspects of terrestrial microgrids and ship power systems are examined.The work exposes a variety of technical synergies from these two power systems to effectively advance their technologies.Understanding their overla...Aspects of terrestrial microgrids and ship power systems are examined.The work exposes a variety of technical synergies from these two power systems to effectively advance their technologies.Understanding their overlap allows congruent efforts to target both systems;understanding their differences hinders conflict and redundancy in early-stage design.The paper concludes by highlighting how an understanding of both systems can reduce the investment in research resources.展开更多
基金supported in part by the Department of Energy(No.DE-AR-0001001,No.DE-EE0009355)the National Science Foundation(NSF)(No.ECCS-2145063)。
文摘Recently,we demonstrated the success of a time-synchronized state estimator using deep neural networks(DNNs)for real-time unobservable distribution systems.In this paper,we provide analytical bounds on the performance of the state estimator as a function of perturbations in the input measurements.It has already been shown that evaluating performance based only on the test dataset might not effectively indicate the ability of a trained DNN to handle input perturbations.As such,we analytically verify the robustness and trustworthiness of DNNs to input perturbations by treating them as mixed-integer linear programming(MILP)problems.The ability of batch normalization in addressing the scalability limitations of the MILP formulation is also highlighted.The framework is validated by performing time-synchronized distribution system state estimation for a modified IEEE 34-node system and a real-world large distribution system,both of which are incompletely observed by micro-phasor measurement units.
基金National Natural Science Foundation of China(62075144)Engineering Featured Team Fund of Sichuan University(2020SCUNG105)。
文摘Lasers with high average and high peak power as well as ultrashort pulse width have been all along demanded by nonlinear optics studies,strong-field experiments,electron dynamics investigations,and ultrafast spectroscopy.While the routinely used titanium-doped sapphire(Ti:sapphire)laser faces a bottleneck in the average power upscaling,ytterbium(Yb)-doped lasers have remarkable advantages in achieving high average power.However,there is still a substantial gap of pulse width and peak power between the Ti:sapphire and Yb-doped lasers.Here we demonstrate a high-power Yb:CaAlGdO4(Yb:CALGO)regenerative amplifier system,delivering 1040 nm pulses with11 W average power,50 fs pulse width,and 3.7 GW peak power at a repetition rate of 43 k Hz,which to some extent bridges the gap between the Ti:sapphire and Yb lasers.An ultrabroadband Yb-doped fiber oscillator,specially designed spectral shapers,and Yb:CALGO gain medium with broad emission bandwidth,together with a double-end pumping scheme enable an amplified bandwidth of 19 nm and 95 fs output pulse width.To the best of our knowledge,this is the first demonstration of sub-100 fs regenerative amplifier based on Yb-doped bulk medium without nonlinear spectral broadening.The amplified pulse is further compressed to 50 fs via cascaded-quadratic compression with a simple setup,producing 3.7 GW peak power,which boosts the record of peak power from Yb:CALGO regenerative amplifiers by 1 order.As a proof of concept,pumped by the high-power,50 fs pulses,7.5–11.5μm midinfrared(MIR)generation via intrapulse difference-frequency generation is performed,without the necessity of nonlinear fiber compressors.It leads to a simple and robust apparatus,and it would find good usefulness in MIR spectroscopic applications.
基金supported by a Grant from the Office of Naval Research(ONR)
文摘Aspects of terrestrial microgrids and ship power systems are examined.The work exposes a variety of technical synergies from these two power systems to effectively advance their technologies.Understanding their overlap allows congruent efforts to target both systems;understanding their differences hinders conflict and redundancy in early-stage design.The paper concludes by highlighting how an understanding of both systems can reduce the investment in research resources.
