Laser additive manufacturing(LAM)of titanium(Ti)alloys has emerged as a transformative technology with vast potential across multiple industries.To recap the state of the art,Ti alloys processed by two essential LAM t...Laser additive manufacturing(LAM)of titanium(Ti)alloys has emerged as a transformative technology with vast potential across multiple industries.To recap the state of the art,Ti alloys processed by two essential LAM techniques(i.e.,laser powder bed fusion and laser-directed energy deposition)will be reviewed,covering the aspects of processes,materials and post-processing.The impacts of process parameters and strategies for optimizing parameters will be elucidated.Various types of Ti alloys processed by LAM,includingα-Ti,(α+β)-Ti,andβ-Ti alloys,will be overviewed in terms of micro structures and benchmarking properties.Furthermore,the post-processing methods for improving the performance of L AM-processed Ti alloys,including conventional and novel heat treatment,hot isostatic pressing,and surface processing(e.g.,ultrasonic and laser shot peening),will be systematically reviewed and discussed.The review summarizes the process windows,properties,and performance envelopes and benchmarks the research achievements in LAM of Ti alloys.The outlooks of further trends in LAM of Ti alloys are also highlighted at the end of the review.This comprehensive review could serve as a valuable resource for researchers and practitioners,promoting further advancements in LAM-built Ti alloys and their applications.展开更多
Weather forecasts from numerical weather prediction models play a central role in solar energy forecasting,where a cascade of physics-based models is used in a model chain approach to convert forecasts of solar irradi...Weather forecasts from numerical weather prediction models play a central role in solar energy forecasting,where a cascade of physics-based models is used in a model chain approach to convert forecasts of solar irradiance to solar power production.Ensemble simulations from such weather models aim to quantify uncertainty in the future development of the weather,and can be used to propagate this uncertainty through the model chain to generate probabilistic solar energy predictions.However,ensemble prediction systems are known to exhibit systematic errors,and thus require post-processing to obtain accurate and reliable probabilistic forecasts.The overarching aim of our study is to systematically evaluate different strategies to apply post-processing in model chain approaches with a specific focus on solar energy:not applying any post-processing at all;post-processing only the irradiance predictions before the conversion;post-processing only the solar power predictions obtained from the model chain;or applying post-processing in both steps.In a case study based on a benchmark dataset for the Jacumba solar plant in the U.S.,we develop statistical and machine learning methods for postprocessing ensemble predictions of global horizontal irradiance(GHI)and solar power generation.Further,we propose a neural-network-based model for direct solar power forecasting that bypasses the model chain.Our results indicate that postprocessing substantially improves the solar power generation forecasts,in particular when post-processing is applied to the power predictions.The machine learning methods for post-processing slightly outperform the statistical methods,and the direct forecasting approach performs comparably to the post-processing strategies.展开更多
A dual-phase synergistic enhancement method was adopted to strengthen the Al-Mn-Mg-Sc-Zr alloy fabricated by laser powder bed fusion(LPBF)by leveraging the unique advantages of Er and TiB_(2).Spherical powders of 0.5w...A dual-phase synergistic enhancement method was adopted to strengthen the Al-Mn-Mg-Sc-Zr alloy fabricated by laser powder bed fusion(LPBF)by leveraging the unique advantages of Er and TiB_(2).Spherical powders of 0.5wt%Er-1wt%TiB_(2)/Al-Mn-Mg-Sc-Zr nanocomposite were prepared using vacuum homogenization technique,and the density of samples prepared through the LPBF process reached 99.8%.The strengthening and toughening mechanisms of Er-TiB_(2)were investigated.The results show that Al_(3)Er diffraction peaks are detected by X-ray diffraction analysis,and texture strength decreases according to electron backscatter diffraction results.The added Er and TiB_(2)nano-reinforcing phases act as heterogeneous nucleation sites during the LPBF forming process,hindering grain growth and effectively refining the grains.After incorporating the Er-TiB_(2)dual-phase nano-reinforcing phases,the tensile strength and elongation at break of the LPBF-deposited samples reach 550 MPa and 18.7%,which are 13.4%and 26.4%higher than those of the matrix material,respectively.展开更多
To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the...To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.展开更多
Conventional ignition methods are proving to be ineffective for low-sensitivity energetic materials,highlighting the need to investigate alternative ignition systems,such as laser-based techniques.Over the past decade...Conventional ignition methods are proving to be ineffective for low-sensitivity energetic materials,highlighting the need to investigate alternative ignition systems,such as laser-based techniques.Over the past decade,lasers have emerged as a promising solution,providing focused energy beams for controllable,efficient,and reliable ignition in the field of energetic materials.This study presents a comparative analysis of two state-of-the-art ignition approaches:direct laser ignition and laser-driven flyer ignition.Experiments were performed using a Neodymium-doped Yttrium Aluminum Garnet(Nd:YAG)laser at different energy beam levels to systematically evaluate ignition onset.In the direct laser ignition test setup,the laser beam was applied directly to the energetic tested material,while laserdriven flyer ignition utilized 40 and 100μm aluminum foils,propelled at velocities ranging from 300 to 1250 m/s.Comparative analysis with the Lawrence and Trott model substantiated the velocity data and provided insight into the ignition mechanisms.Experimental results indicate that the ignition time for the laser-driven flyer method was significantly shorter,with the pyrotechnic composition achieving complete combustion faster compared to direct laser ignition.Moreover,precise ignition thresholds were determined for both methods,providing critical parameters for optimizing ignition systems in energetic materials.This work elucidates the advantages and limitations of each technique while advancing next-generation ignition technology,enhancing the reliability and safety of propulsion systems.展开更多
The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of...The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of the initial spin direction,the spin dynamics of the electron beam are found to depend on the self-injection mechanism.The effects of wakefields and laser fields are studied using test particle dynamics and particle-in-cell simulations based on the Thomas-Bargmann-Michel-Telegdi equation.Compared with transverse injection,longitudinal injection is found to be preferable for obtaining a highly polarized electron beam.展开更多
Tunable mid-infrared and far-infrared laser output was demonstrated based on BaGa_(4)Se_(7)crystals and an optical parametric oscillator(OPO).With a 1.06μm Nd:YAG laser and a double-pass singly resonant OPO cavity,a ...Tunable mid-infrared and far-infrared laser output was demonstrated based on BaGa_(4)Se_(7)crystals and an optical parametric oscillator(OPO).With a 1.06μm Nd:YAG laser and a double-pass singly resonant OPO cavity,a laser energy output of 2.2 mJ at 10μm was obtained.By tuning the angle and temperature,a tunable laser output covering the wavelength range from 6μm to 17μm was obtained with a tuning precision better than 3 nm.The corresponding optical-to-optical conversion efficiency was 2.8%,and the slope efficiency was 4.4%.The damage effect of the output laser on detectors was also investigated,and point damage to the detector occurred at an output energy of 16.4μJ.The laser system has the advantages of miniaturization,a wide tuning range,high energy and high tuning resolution.Its broadband laser characteristics make it highly valuable for applications in atmospheric detection,infrared spectroscopy and electro-optical countermeasures.展开更多
The fatigue crack growth rate of a novel Ti-6Al-4V-1Mo titanium alloy,which is developed for laser directed energy deposition technique,was investigated before and after cyclic heat treatment(CHT).Changes in microstru...The fatigue crack growth rate of a novel Ti-6Al-4V-1Mo titanium alloy,which is developed for laser directed energy deposition technique,was investigated before and after cyclic heat treatment(CHT).Changes in microstructure,fracture surfaces,and crack growth paths were analyzed before and after CHT.Results indicate that in the stable crack growth region,the growth rates for the as-deposited and cyclic heat-treated specimens follow the relationships da/dN=1.8651×10^(−8)(ΔK)^(3.2271)and da/dN=1.4112×10^(−8)(ΔK)^(3.1125),respectively.Compared with that at the as-deposited state,the microstructure after CHT is transformed from a uniform basket-weave microstructure to a dual-phase microstructure consisting of near-sphericalαandβ-transformed matrix phases.The cyclic process also disrupts the continuity of the grain boundaryα(αGB)at the primaryβ-phase grain boundary.The coarsening of primaryαand the disruption ofαGB continuity are the primary factors to release stress concentration and promote crack deflection,thereby decreasing the fatigue crack growth rate.Additionally,the increased occurrence of crack branching,secondary cracking,and crack bridging in cyclic heat-treated specimens further reduces the crack driving force and slows the fatigue crack growth rate.展开更多
The original online version of this article was revised:Several errors occurred in the published version of the article.These have now been corrected as follows:Page 2,section"2.2 Laser Texturing Procedure of Sur...The original online version of this article was revised:Several errors occurred in the published version of the article.These have now been corrected as follows:Page 2,section"2.2 Laser Texturing Procedure of Surfaces",line 2:The device name was corrected from"YDFLP-E-50-M8"to"YDFLP-50-M8."Page 3,Section 2.4:The phrase"95%confidence interval"has been corrected to"95%confidence level."Page 3,Figure 1 caption:The phrase"fandg"has been corrected to"f and g."The order"C4 and C12"has been reversed to"C12 and C4,"in accordance with the display order in the figure.Page 4,Figure reference:The phrase"Figs.4c and d"has been corrected to"Figs.5b and c."Page 5,paragraph starting with"The ANOVA results are presented...":The phrase"95%confidence interval"has been corrected to"95%confidence level."展开更多
We investigate theoretically and experimentally the chaotic dynamics of visible-wavelength all-fiber ring laser.The100-m 630 HP fibers are used to ensure high non-linearity.A 4-m Pr^(3+)/Yb^(3+)-co-doped ZBLAN fiber p...We investigate theoretically and experimentally the chaotic dynamics of visible-wavelength all-fiber ring laser.The100-m 630 HP fibers are used to ensure high non-linearity.A 4-m Pr^(3+)/Yb^(3+)-co-doped ZBLAN fiber provides the gain.The chaotic laser was pumped by the laser diodes with the maximum power of 150 mW at the wavelength of 850 nm.The peak fluorescence spectrum of Pr^(3+)/Yb^(3+)-co-doped ZBLAN fiber at the wavelength of 635 nm shows that the visiblewavelength fiber laser can be achieved by synergistic energy transfer between Pr~(3+)and Yb^(3+)ions.The chaotic fiber laser is generated by adjusting the pump power,polarization controller and the auto-correlation,permutation entropy,skewness,and kurtosis were used to analyze the characteristics of chaotic laser.The noise-like time series and delta-like auto-correlation curve indicate the chaotic output.The complexity and randomness of time series are analyzed by the permutation entropy,skewness,and kurtosis.The result shows that chaotic dynamics is stable when the pump power exceeds a certain value.The visible chaotic all-fiber laser has high stability and can be applied for real-time monitoring and sensing.We believe that this approach may also be feasible for other materials for emission in the visible range.展开更多
The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solutio...The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solution were used to regulate the microstructure,mechanical properties,and corrosion properties of B_(4)C/TC4 composite.Results show that with the increase in temperature from 500℃to 800°C,partial lamellarα-Ti in the as-deposited sample is gradually transformed into equiaxedα-Ti,accompanied by the disappearance of basketweave microstructure.At 1100°C,a small portion of TiC phase suffers fusion.This composite exhibits the optimal combination of strength and plasticity after annealing at 500℃for 4 h followed by furnace cooling,which is attributed to the stress release effect and the refined basketweave microstructure.However,this composite shows a decline in corrosion resistance after various heat treatments due to grain coarsening and micro-galvanic corrosion.展开更多
The 193 nm deep-ultraviolet(DUV)laser plays a critical role in advanced semiconductor chip manufacturing[1,2],micro-nano material characterization[3,4]and biomedical analysis[5,6],due to its high spatial resolution an...The 193 nm deep-ultraviolet(DUV)laser plays a critical role in advanced semiconductor chip manufacturing[1,2],micro-nano material characterization[3,4]and biomedical analysis[5,6],due to its high spatial resolution and short wavelength.Efficient and compact 193 nm DUV laser source thus becomes a hot research area.Currently,193 nm Ar F excimer gas laser is widely employed in DUV lithography systems and serves as the enabling technology for 7 and 5 nm semiconductor fabrication.展开更多
The precise excitation of molecular vibrational states is critical for ad-vancing chemical dynamics,preci-sion spectroscopy,and trace gas sensing.This objective,however,is often hindered by the weak oscilla-tor streng...The precise excitation of molecular vibrational states is critical for ad-vancing chemical dynamics,preci-sion spectroscopy,and trace gas sensing.This objective,however,is often hindered by the weak oscilla-tor strengths of ro-vibrational tran-sitions,which render conventional continuous-wave(cw)lasers ineffec-tive due to their limited power.This fundamental challenge is overcome by cavity-enhanced excitation(CEE),a technique that locks a cw laser to a high-finesse optical cavity.This configuration amplifies the intra-cavity light intensity by several orders of magnitude while preserving a narrow spectral linewidth.The resulting synergy enables highly efficient,state-selective population transfer and high-resolution spectroscopy previously considered impractical.This review elucidates the core technique of laser-cavity locking and highlights its applications,notably in the quantitative detection of trace isotopes and the investigation of highly excited vibrational states with kilo-hertz-level accuracy.展开更多
In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields...In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields can slightly change the cluster-decay half-life by affecting the penetration probability within a narrow range.Subsequently,we discuss the correlation between the change rate of the penetration probability and the tunneling path.The results indicate that for different parent nuclei emitting the same cluster,nuclei with longer tunneling paths are more easily affected by the laser fields.The shell effect on this correlation is also observed.In addition,the impact of laser fields on the penetration probability in any direction is investigated.展开更多
Based on the characteristics of laser-induced surface ignition,energetic photosensitive films show promising potential to meet the ignition requirements of various energetic materials(EMs).In this study,DATNBI/ferric ...Based on the characteristics of laser-induced surface ignition,energetic photosensitive films show promising potential to meet the ignition requirements of various energetic materials(EMs).In this study,DATNBI/ferric alginate(DI/FeA),DI/cobalt alginate(DI/CoA),and DI/nickel alginate(DI/Ni A)films are fabricated by employing sodium alginate(SA)with a three-dimensional network structure as the film matrix,via ionic cross-linking of SA with Fe^(3+),Co^(2+),and Ni^(2+)ions.The study demonstrates that the ionic cross-linking enhances the hydrophobic performance of the films,with the water contact angle increasing from 82.1° to 123.5°.Concurrently,the films'near-infrared(NIR)light absorption improved.Furthermore,transition metal ions facilitate accelerated electron transfer,thereby catalyzing the thermal decomposition of DATNBI.Under 1064 nm laser irradiation,the DI/Fe A film exhibits exceptional combustion performance,with an ignition delay time as low as 76 ms.It successfully acts as an NIR laser ignition medium to initiate the self-sustained combustion of CL-20.This study demonstrates the synergistic realization of enhanced hydrophobicity,improved photosensitivity,and promoted catalytic decomposition through microstructural design of the material,providing new insights for the design of additive-free EMs in laser ignition applications.展开更多
The process of nuclear fusion in the presence of a laser field was theoretically analyzed.The analysis is applicable to most fusion reactions and different types of currently available intense lasers,from X-ray free-e...The process of nuclear fusion in the presence of a laser field was theoretically analyzed.The analysis is applicable to most fusion reactions and different types of currently available intense lasers,from X-ray free-electron lasers to solid-state near-infrared lasers.Laser fields were shown to enhance the fusion yields,and the mechanism of this enhancement was explained.Low-frequency lasers are more efficient in enhancing fusion than high-frequency lasers.The calculation results show enhancements of fusion yields by orders of magnitude with currently available intense low-frequency laser fields.The temperature requirement for controlled nuclear fusion may be reduced with the aid of intense laser fields.展开更多
The laser-clad Fe45 alloy coating inherently comprises multiple crystalline phases,resulting in a heterogeneous microstructural distribution that influences its performance.In this study,the rare earth yttria(Y_(2)O_(...The laser-clad Fe45 alloy coating inherently comprises multiple crystalline phases,resulting in a heterogeneous microstructural distribution that influences its performance.In this study,the rare earth yttria(Y_(2)O_(3))was employed to modify laser-clad Fe45 alloy coatings,and the effects of Y_(2)O_(3) addition on their microstructure,microhardness,and tribological properties were investigated.As the Y_(2)O_(3) content increases from 0%to 0.3wt.%,the dominant microstructure transforms from columnar crystals to fine cellular and equiaxed crystals.The modified coating with 0.3wt.%Y_(2)O_(3) achieves a surface hardness of 568 HV_(0.3)and a wear volume of 1,735.41 um~3,representing a 14.06%increase in hardness and a 51.16%reduction in wear volume compared to the undoped coating.Further increasing the Y_(2)O_(3) content from 0.3wt.%to 0.9wt.%gradually leads to the emergence of a coarser feather-like microstructure,characterized by a dendritic framework with inter-dendritic equiaxed crystals.Concurrently,both the hardness and wear resistance of the coating decrease.Nevertheless,all Y_(2)O_(3)-modified coatings surpass the undoped Fe45 coating in both hardness and wear resistance.Appropriate Y_(2)O_(3) doping effectively refines the Fe45 alloy coating's microstru cture and induces lattice distortion,thereby enhancing its hardness and wear resistance.展开更多
Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-de...Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-density matter,understanding planetary science,and laser-driven fusion energy.However,experimental efforts in this regime have been limited by the lack of accessibility of over-critical densities and the poor spatiotemporal resolution of conventional diagnostics.Over the last decade,the advent of femtosecond brilliant hard X-ray free-electron lasers(XFELs)has opened new horizons to overcome these limitations.Here,for the first time,we present full-scale spatiotemporal measurements of solid-density plasma dynamics,including preplasma generation with tens of nanometer scale length driven by the leading edge of a relativistic laser pulse,ultrafast heating and ionization at the main pulse arrival,the laser-driven blast wave,and transient surface return current-induced compression dynamics up to hundreds of picoseconds after interaction.These observations are enabled by utilizing a novel combination of advanced X-ray diagnostics including small-angle X-ray scattering,resonant X-ray emission spectroscopy,and propagation-based X-ray phase-contrast imaging simultaneously at the European XFEL-HED beamline station.展开更多
Experiments with interacting high-velocity flows in a laser plasma can help answer fundamental questions in plasma physics and improve understanding of the mechanisms behind some astrophysical phenomena,such as the fo...Experiments with interacting high-velocity flows in a laser plasma can help answer fundamental questions in plasma physics and improve understanding of the mechanisms behind some astrophysical phenomena,such as the formation of collisionless shock waves,deceleration of accretion flows,and evolution of solar and stellar flares.This work presents the first direct experimental observations of stagnation and redirection of counterstreaming flows(jets)of laser plasma induced by intense laser pulses with intensity I~2×10^(18) W/cm^(2).Hybrid particlein-cell-fluid modeling,which takes into account the kinetic effects of ion motion and the evolution of the pressure tensor for electrons,demonstrates the compression of counterdirected toroidal self-generated magnetic fields embedded in counterstreaming plasma flows.The enhancement of the toroidal magnetic field in the interaction region results in plasma flow stagnation and redirection of the jets across the line of their initial propagation.展开更多
Biopolymeric nanocomposites have attracted considerable attention because of their biocompatibility,biodegradability,and unique physicochemical properties.It is essential to manufacture three-dimensional(3D)biocompati...Biopolymeric nanocomposites have attracted considerable attention because of their biocompatibility,biodegradability,and unique physicochemical properties.It is essential to manufacture three-dimensional(3D)biocompatible micro/nanostructures using biopolymeric nanocomposites.Herein,we demonstrate the high-fidelity fabrication of biocompatible 3D features with sub-50 nm resolution using femtosecond laser direct writing(FsLDW)of a biopolymeric nanocomposite composed of egg white and sulfonated graphene(S-graphene).The biopolymer nanocomposite acts as a negative photoresist suitable for water-based lithography.The introduction of S-graphene not only dramatically lowered the laser power threshold but also significantly modulated the morphology of the 3D features constructed by FsLDW.Microstructures with porous,rough,or smooth morphologies were obtained by optimizing the S-graphene concentration and laser scanning speed.The fabricated egg-white/S-graphene microstructures exhibited biocompatibility and environmental degradability.Egg white/S-graphene was also employed to fabricate diffractive gratings with superior optical quality.This study provides a promising method to manufacture biocompatible 3D features with controllable morphology,which has potential applications in biological and photonic fields.展开更多
基金financially supported by the 2022 MTC Young Individual Research Grants under Singapore Research,Innovation and Enterprise(RIE)2025 Plan(No.M22K3c0097)the Natural Science Foundation of US(No.DMR-2104933)the sponsorship of the China Scholarship Council(No.202106130051)。
文摘Laser additive manufacturing(LAM)of titanium(Ti)alloys has emerged as a transformative technology with vast potential across multiple industries.To recap the state of the art,Ti alloys processed by two essential LAM techniques(i.e.,laser powder bed fusion and laser-directed energy deposition)will be reviewed,covering the aspects of processes,materials and post-processing.The impacts of process parameters and strategies for optimizing parameters will be elucidated.Various types of Ti alloys processed by LAM,includingα-Ti,(α+β)-Ti,andβ-Ti alloys,will be overviewed in terms of micro structures and benchmarking properties.Furthermore,the post-processing methods for improving the performance of L AM-processed Ti alloys,including conventional and novel heat treatment,hot isostatic pressing,and surface processing(e.g.,ultrasonic and laser shot peening),will be systematically reviewed and discussed.The review summarizes the process windows,properties,and performance envelopes and benchmarks the research achievements in LAM of Ti alloys.The outlooks of further trends in LAM of Ti alloys are also highlighted at the end of the review.This comprehensive review could serve as a valuable resource for researchers and practitioners,promoting further advancements in LAM-built Ti alloys and their applications.
基金the Young Investigator Group“Artificial Intelligence for Probabilistic Weather Forecasting”funded by the Vector Stiftungfunding from the Federal Ministry of Education and Research(BMBF)and the Baden-Württemberg Ministry of Science as part of the Excellence Strategy of the German Federal and State Governments。
文摘Weather forecasts from numerical weather prediction models play a central role in solar energy forecasting,where a cascade of physics-based models is used in a model chain approach to convert forecasts of solar irradiance to solar power production.Ensemble simulations from such weather models aim to quantify uncertainty in the future development of the weather,and can be used to propagate this uncertainty through the model chain to generate probabilistic solar energy predictions.However,ensemble prediction systems are known to exhibit systematic errors,and thus require post-processing to obtain accurate and reliable probabilistic forecasts.The overarching aim of our study is to systematically evaluate different strategies to apply post-processing in model chain approaches with a specific focus on solar energy:not applying any post-processing at all;post-processing only the irradiance predictions before the conversion;post-processing only the solar power predictions obtained from the model chain;or applying post-processing in both steps.In a case study based on a benchmark dataset for the Jacumba solar plant in the U.S.,we develop statistical and machine learning methods for postprocessing ensemble predictions of global horizontal irradiance(GHI)and solar power generation.Further,we propose a neural-network-based model for direct solar power forecasting that bypasses the model chain.Our results indicate that postprocessing substantially improves the solar power generation forecasts,in particular when post-processing is applied to the power predictions.The machine learning methods for post-processing slightly outperform the statistical methods,and the direct forecasting approach performs comparably to the post-processing strategies.
基金Shaanxi Province Qin Chuangyuan“Scientist+Engineer”Team Construction Project(2022KXJ-071)2022 Qin Chuangyuan Achievement Transformation Incubation Capacity Improvement Project(2022JH-ZHFHTS-0012)+8 种基金Shaanxi Province Key Research and Development Plan-“Two Chains”Integration Key Project-Qin Chuangyuan General Window Industrial Cluster Project(2023QCY-LL-02)Xixian New Area Science and Technology Plan(2022-YXYJ-003,2022-XXCY-010)2024 Scientific Research Project of Shaanxi National Defense Industry Vocational and Technical College(Gfy24-07)Shaanxi Vocational and Technical Education Association 2024 Vocational Education Teaching Reform Research Topic(2024SZX354)National Natural Science Foundation of China(U24A20115)2024 Shaanxi Provincial Education Department Service Local Special Scientific Research Program Project-Industrialization Cultivation Project(24JC005,24JC063)Shaanxi Province“14th Five-Year Plan”Education Science Plan,2024 Project(SGH24Y3181)National Key Research and Development Program of China(2023YFB4606400)Longmen Laboratory Frontier Exploration Topics Project(LMQYTSKT003)。
文摘A dual-phase synergistic enhancement method was adopted to strengthen the Al-Mn-Mg-Sc-Zr alloy fabricated by laser powder bed fusion(LPBF)by leveraging the unique advantages of Er and TiB_(2).Spherical powders of 0.5wt%Er-1wt%TiB_(2)/Al-Mn-Mg-Sc-Zr nanocomposite were prepared using vacuum homogenization technique,and the density of samples prepared through the LPBF process reached 99.8%.The strengthening and toughening mechanisms of Er-TiB_(2)were investigated.The results show that Al_(3)Er diffraction peaks are detected by X-ray diffraction analysis,and texture strength decreases according to electron backscatter diffraction results.The added Er and TiB_(2)nano-reinforcing phases act as heterogeneous nucleation sites during the LPBF forming process,hindering grain growth and effectively refining the grains.After incorporating the Er-TiB_(2)dual-phase nano-reinforcing phases,the tensile strength and elongation at break of the LPBF-deposited samples reach 550 MPa and 18.7%,which are 13.4%and 26.4%higher than those of the matrix material,respectively.
基金National Natural Science Foundation of China(51504138,51674118,52271177)Hunan Provincial Natural Science Foundation of China(2023JJ50181)Supported by State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(P2024-022)。
文摘To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.
文摘Conventional ignition methods are proving to be ineffective for low-sensitivity energetic materials,highlighting the need to investigate alternative ignition systems,such as laser-based techniques.Over the past decade,lasers have emerged as a promising solution,providing focused energy beams for controllable,efficient,and reliable ignition in the field of energetic materials.This study presents a comparative analysis of two state-of-the-art ignition approaches:direct laser ignition and laser-driven flyer ignition.Experiments were performed using a Neodymium-doped Yttrium Aluminum Garnet(Nd:YAG)laser at different energy beam levels to systematically evaluate ignition onset.In the direct laser ignition test setup,the laser beam was applied directly to the energetic tested material,while laserdriven flyer ignition utilized 40 and 100μm aluminum foils,propelled at velocities ranging from 300 to 1250 m/s.Comparative analysis with the Lawrence and Trott model substantiated the velocity data and provided insight into the ignition mechanisms.Experimental results indicate that the ignition time for the laser-driven flyer method was significantly shorter,with the pyrotechnic composition achieving complete combustion faster compared to direct laser ignition.Moreover,precise ignition thresholds were determined for both methods,providing critical parameters for optimizing ignition systems in energetic materials.This work elucidates the advantages and limitations of each technique while advancing next-generation ignition technology,enhancing the reliability and safety of propulsion systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.11804348,11775056,11975154,12225505,and 12405281)the Science Challenge(Project No.TZ2018005)+2 种基金supported by the Shanghai Pujiang Program(Grant No.23PJ1414600)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0890203)supported by the Accelerator Technology Helmholtz Infrastructure consortium ATHENA.
文摘The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of the initial spin direction,the spin dynamics of the electron beam are found to depend on the self-injection mechanism.The effects of wakefields and laser fields are studied using test particle dynamics and particle-in-cell simulations based on the Thomas-Bargmann-Michel-Telegdi equation.Compared with transverse injection,longitudinal injection is found to be preferable for obtaining a highly polarized electron beam.
基金supported by Independent Innovation Science Foundation of National University of Defense Technology(Grant No.23-ZZCX-JDZ-44)。
文摘Tunable mid-infrared and far-infrared laser output was demonstrated based on BaGa_(4)Se_(7)crystals and an optical parametric oscillator(OPO).With a 1.06μm Nd:YAG laser and a double-pass singly resonant OPO cavity,a laser energy output of 2.2 mJ at 10μm was obtained.By tuning the angle and temperature,a tunable laser output covering the wavelength range from 6μm to 17μm was obtained with a tuning precision better than 3 nm.The corresponding optical-to-optical conversion efficiency was 2.8%,and the slope efficiency was 4.4%.The damage effect of the output laser on detectors was also investigated,and point damage to the detector occurred at an output energy of 16.4μJ.The laser system has the advantages of miniaturization,a wide tuning range,high energy and high tuning resolution.Its broadband laser characteristics make it highly valuable for applications in atmospheric detection,infrared spectroscopy and electro-optical countermeasures.
基金National Key Research and Development Program of China(2024YFB4610803)。
文摘The fatigue crack growth rate of a novel Ti-6Al-4V-1Mo titanium alloy,which is developed for laser directed energy deposition technique,was investigated before and after cyclic heat treatment(CHT).Changes in microstructure,fracture surfaces,and crack growth paths were analyzed before and after CHT.Results indicate that in the stable crack growth region,the growth rates for the as-deposited and cyclic heat-treated specimens follow the relationships da/dN=1.8651×10^(−8)(ΔK)^(3.2271)and da/dN=1.4112×10^(−8)(ΔK)^(3.1125),respectively.Compared with that at the as-deposited state,the microstructure after CHT is transformed from a uniform basket-weave microstructure to a dual-phase microstructure consisting of near-sphericalαandβ-transformed matrix phases.The cyclic process also disrupts the continuity of the grain boundaryα(αGB)at the primaryβ-phase grain boundary.The coarsening of primaryαand the disruption ofαGB continuity are the primary factors to release stress concentration and promote crack deflection,thereby decreasing the fatigue crack growth rate.Additionally,the increased occurrence of crack branching,secondary cracking,and crack bridging in cyclic heat-treated specimens further reduces the crack driving force and slows the fatigue crack growth rate.
文摘The original online version of this article was revised:Several errors occurred in the published version of the article.These have now been corrected as follows:Page 2,section"2.2 Laser Texturing Procedure of Surfaces",line 2:The device name was corrected from"YDFLP-E-50-M8"to"YDFLP-50-M8."Page 3,Section 2.4:The phrase"95%confidence interval"has been corrected to"95%confidence level."Page 3,Figure 1 caption:The phrase"fandg"has been corrected to"f and g."The order"C4 and C12"has been reversed to"C12 and C4,"in accordance with the display order in the figure.Page 4,Figure reference:The phrase"Figs.4c and d"has been corrected to"Figs.5b and c."Page 5,paragraph starting with"The ANOVA results are presented...":The phrase"95%confidence interval"has been corrected to"95%confidence level."
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61975141,61575137,and61675144)。
文摘We investigate theoretically and experimentally the chaotic dynamics of visible-wavelength all-fiber ring laser.The100-m 630 HP fibers are used to ensure high non-linearity.A 4-m Pr^(3+)/Yb^(3+)-co-doped ZBLAN fiber provides the gain.The chaotic laser was pumped by the laser diodes with the maximum power of 150 mW at the wavelength of 850 nm.The peak fluorescence spectrum of Pr^(3+)/Yb^(3+)-co-doped ZBLAN fiber at the wavelength of 635 nm shows that the visiblewavelength fiber laser can be achieved by synergistic energy transfer between Pr~(3+)and Yb^(3+)ions.The chaotic fiber laser is generated by adjusting the pump power,polarization controller and the auto-correlation,permutation entropy,skewness,and kurtosis were used to analyze the characteristics of chaotic laser.The noise-like time series and delta-like auto-correlation curve indicate the chaotic output.The complexity and randomness of time series are analyzed by the permutation entropy,skewness,and kurtosis.The result shows that chaotic dynamics is stable when the pump power exceeds a certain value.The visible chaotic all-fiber laser has high stability and can be applied for real-time monitoring and sensing.We believe that this approach may also be feasible for other materials for emission in the visible range.
基金Tianjin Municipal Natural Science Foundation(23JCYBJC00040)National Natural Science Foundation of China(52175369)。
文摘The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solution were used to regulate the microstructure,mechanical properties,and corrosion properties of B_(4)C/TC4 composite.Results show that with the increase in temperature from 500℃to 800°C,partial lamellarα-Ti in the as-deposited sample is gradually transformed into equiaxedα-Ti,accompanied by the disappearance of basketweave microstructure.At 1100°C,a small portion of TiC phase suffers fusion.This composite exhibits the optimal combination of strength and plasticity after annealing at 500℃for 4 h followed by furnace cooling,which is attributed to the stress release effect and the refined basketweave microstructure.However,this composite shows a decline in corrosion resistance after various heat treatments due to grain coarsening and micro-galvanic corrosion.
基金supported by the National Natural Science Foundation of China(Grant Nos.62450006,62304217,62274157,62127807,62234011,62034008,62074142,62074140)Tianshan Innovation Team Program(Grant No.2022TSYCTD0005)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0880000)Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant Nos.2023124,Y2023032)。
文摘The 193 nm deep-ultraviolet(DUV)laser plays a critical role in advanced semiconductor chip manufacturing[1,2],micro-nano material characterization[3,4]and biomedical analysis[5,6],due to its high spatial resolution and short wavelength.Efficient and compact 193 nm DUV laser source thus becomes a hot research area.Currently,193 nm Ar F excimer gas laser is widely employed in DUV lithography systems and serves as the enabling technology for 7 and 5 nm semiconductor fabrication.
基金supported by the Chinese Acade-my of Sciences(Grant Nos.YSBR-055,XDB0970100)the National Natural Science Foundation of China(Nos.22241302,12393825).
文摘The precise excitation of molecular vibrational states is critical for ad-vancing chemical dynamics,preci-sion spectroscopy,and trace gas sensing.This objective,however,is often hindered by the weak oscilla-tor strengths of ro-vibrational tran-sitions,which render conventional continuous-wave(cw)lasers ineffec-tive due to their limited power.This fundamental challenge is overcome by cavity-enhanced excitation(CEE),a technique that locks a cw laser to a high-finesse optical cavity.This configuration amplifies the intra-cavity light intensity by several orders of magnitude while preserving a narrow spectral linewidth.The resulting synergy enables highly efficient,state-selective population transfer and high-resolution spectroscopy previously considered impractical.This review elucidates the core technique of laser-cavity locking and highlights its applications,notably in the quantitative detection of trace isotopes and the investigation of highly excited vibrational states with kilo-hertz-level accuracy.
基金supported in part by the National Natural Science Foundation of China(Nos.12175100 and 11975132)the Construct Program of the Key Discipline in Hunan Province+5 种基金the Research Foundation of Education Bureau of Hunan Province,China(Nos.21B0402,18A237,22A0305)the Natural Science Foundation of Hunan Province,China(No.2018JJ2321)the Innovation Group of Nuclear and Particle Physics in USCthe Shandong Province Natural Science Foundation,China(No.ZR2022JQ04)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(No.2019KFZ10)the Hunan Provincial Innovation Foundation for Postgraduate(No.CX20251453)。
文摘In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields can slightly change the cluster-decay half-life by affecting the penetration probability within a narrow range.Subsequently,we discuss the correlation between the change rate of the penetration probability and the tunneling path.The results indicate that for different parent nuclei emitting the same cluster,nuclei with longer tunneling paths are more easily affected by the laser fields.The shell effect on this correlation is also observed.In addition,the impact of laser fields on the penetration probability in any direction is investigated.
基金supported by Research Fund of SWUST for PhD(Grant No.22zx7175)Sichuan Science and Technology Program(Grant No.2024NSFSC1097)。
文摘Based on the characteristics of laser-induced surface ignition,energetic photosensitive films show promising potential to meet the ignition requirements of various energetic materials(EMs).In this study,DATNBI/ferric alginate(DI/FeA),DI/cobalt alginate(DI/CoA),and DI/nickel alginate(DI/Ni A)films are fabricated by employing sodium alginate(SA)with a three-dimensional network structure as the film matrix,via ionic cross-linking of SA with Fe^(3+),Co^(2+),and Ni^(2+)ions.The study demonstrates that the ionic cross-linking enhances the hydrophobic performance of the films,with the water contact angle increasing from 82.1° to 123.5°.Concurrently,the films'near-infrared(NIR)light absorption improved.Furthermore,transition metal ions facilitate accelerated electron transfer,thereby catalyzing the thermal decomposition of DATNBI.Under 1064 nm laser irradiation,the DI/Fe A film exhibits exceptional combustion performance,with an ignition delay time as low as 76 ms.It successfully acts as an NIR laser ignition medium to initiate the self-sustained combustion of CL-20.This study demonstrates the synergistic realization of enhanced hydrophobicity,improved photosensitivity,and promoted catalytic decomposition through microstructural design of the material,providing new insights for the design of additive-free EMs in laser ignition applications.
基金supported by the National Natural Science Foundation of China(Nos.12405288,12374241,12474484,U2330401,12088101)the Natural Science Foundation of Top Talent of SZTU(No.GDRC202526)。
文摘The process of nuclear fusion in the presence of a laser field was theoretically analyzed.The analysis is applicable to most fusion reactions and different types of currently available intense lasers,from X-ray free-electron lasers to solid-state near-infrared lasers.Laser fields were shown to enhance the fusion yields,and the mechanism of this enhancement was explained.Low-frequency lasers are more efficient in enhancing fusion than high-frequency lasers.The calculation results show enhancements of fusion yields by orders of magnitude with currently available intense low-frequency laser fields.The temperature requirement for controlled nuclear fusion may be reduced with the aid of intense laser fields.
基金supported by the Jiangxi Provincial Natural Science Foundation of China(Grant number 20224BAB204049)the Fund Project of Jiangxi Provincial Department of Education(Grant number GJJ2200602)the National Natural Science Foundation of China(Grant number 52205194)。
文摘The laser-clad Fe45 alloy coating inherently comprises multiple crystalline phases,resulting in a heterogeneous microstructural distribution that influences its performance.In this study,the rare earth yttria(Y_(2)O_(3))was employed to modify laser-clad Fe45 alloy coatings,and the effects of Y_(2)O_(3) addition on their microstructure,microhardness,and tribological properties were investigated.As the Y_(2)O_(3) content increases from 0%to 0.3wt.%,the dominant microstructure transforms from columnar crystals to fine cellular and equiaxed crystals.The modified coating with 0.3wt.%Y_(2)O_(3) achieves a surface hardness of 568 HV_(0.3)and a wear volume of 1,735.41 um~3,representing a 14.06%increase in hardness and a 51.16%reduction in wear volume compared to the undoped coating.Further increasing the Y_(2)O_(3) content from 0.3wt.%to 0.9wt.%gradually leads to the emergence of a coarser feather-like microstructure,characterized by a dendritic framework with inter-dendritic equiaxed crystals.Concurrently,both the hardness and wear resistance of the coating decrease.Nevertheless,all Y_(2)O_(3)-modified coatings surpass the undoped Fe45 coating in both hardness and wear resistance.Appropriate Y_(2)O_(3) doping effectively refines the Fe45 alloy coating's microstru cture and induces lattice distortion,thereby enhancing its hardness and wear resistance.
基金funding from Grant No. HIDSS-0002 DASHH (Data Science in Hamburg-Helmholtz Graduate School for the Structure of Matter)partially supported by the Helmholtz Imaging platform through the project “Smart Phase.”
文摘Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-density matter,understanding planetary science,and laser-driven fusion energy.However,experimental efforts in this regime have been limited by the lack of accessibility of over-critical densities and the poor spatiotemporal resolution of conventional diagnostics.Over the last decade,the advent of femtosecond brilliant hard X-ray free-electron lasers(XFELs)has opened new horizons to overcome these limitations.Here,for the first time,we present full-scale spatiotemporal measurements of solid-density plasma dynamics,including preplasma generation with tens of nanometer scale length driven by the leading edge of a relativistic laser pulse,ultrafast heating and ionization at the main pulse arrival,the laser-driven blast wave,and transient surface return current-induced compression dynamics up to hundreds of picoseconds after interaction.These observations are enabled by utilizing a novel combination of advanced X-ray diagnostics including small-angle X-ray scattering,resonant X-ray emission spectroscopy,and propagation-based X-ray phase-contrast imaging simultaneously at the European XFEL-HED beamline station.
基金supported by Russian Science Foundation Grant No.24-62-00032.
文摘Experiments with interacting high-velocity flows in a laser plasma can help answer fundamental questions in plasma physics and improve understanding of the mechanisms behind some astrophysical phenomena,such as the formation of collisionless shock waves,deceleration of accretion flows,and evolution of solar and stellar flares.This work presents the first direct experimental observations of stagnation and redirection of counterstreaming flows(jets)of laser plasma induced by intense laser pulses with intensity I~2×10^(18) W/cm^(2).Hybrid particlein-cell-fluid modeling,which takes into account the kinetic effects of ion motion and the evolution of the pressure tensor for electrons,demonstrates the compression of counterdirected toroidal self-generated magnetic fields embedded in counterstreaming plasma flows.The enhancement of the toroidal magnetic field in the interaction region results in plasma flow stagnation and redirection of the jets across the line of their initial propagation.
基金financially supported by the National Key Research and Development Program of China(Nos.2024YFB4607402 and 2016YFC1100502)the National Natural Science Foundation of China(Nos.51673208 and 61975213)。
文摘Biopolymeric nanocomposites have attracted considerable attention because of their biocompatibility,biodegradability,and unique physicochemical properties.It is essential to manufacture three-dimensional(3D)biocompatible micro/nanostructures using biopolymeric nanocomposites.Herein,we demonstrate the high-fidelity fabrication of biocompatible 3D features with sub-50 nm resolution using femtosecond laser direct writing(FsLDW)of a biopolymeric nanocomposite composed of egg white and sulfonated graphene(S-graphene).The biopolymer nanocomposite acts as a negative photoresist suitable for water-based lithography.The introduction of S-graphene not only dramatically lowered the laser power threshold but also significantly modulated the morphology of the 3D features constructed by FsLDW.Microstructures with porous,rough,or smooth morphologies were obtained by optimizing the S-graphene concentration and laser scanning speed.The fabricated egg-white/S-graphene microstructures exhibited biocompatibility and environmental degradability.Egg white/S-graphene was also employed to fabricate diffractive gratings with superior optical quality.This study provides a promising method to manufacture biocompatible 3D features with controllable morphology,which has potential applications in biological and photonic fields.
