Recent advances in statistical physics highlight the significant potential of machine learning for phase transition recognition.This study introduces a deep learning framework based on graph neural network to investig...Recent advances in statistical physics highlight the significant potential of machine learning for phase transition recognition.This study introduces a deep learning framework based on graph neural network to investigate non-equilibrium phase transitions,specifically focusing on the directed percolation process.By converting lattices with varying dimensions and connectivity schemes into graph structures and embedding the temporal evolution of the percolation process into node features,our approach enables unified analysis across diverse systems.The framework utilizes a multi-layer graph attention mechanism combined with global pooling to autonomously extract critical features from local dynamics to global phase transition signatures.The model successfully predicts percolation thresholds without relying on lattice geometry,demonstrating its robustness and versatility.Our approach not only offers new insights into phase transition studies but also provides a powerful tool for analyzing complex dynamical systems across various domains.展开更多
Bit patterned recording(BPR)has attracted much attention due to its promising potential in achieving high densities in magnetic storage devices.The materials with strong perpendicular magnetic anisotropy(PMA)are alway...Bit patterned recording(BPR)has attracted much attention due to its promising potential in achieving high densities in magnetic storage devices.The materials with strong perpendicular magnetic anisotropy(PMA)are always preferred in designing the BPR.Here,the patterned Co/Ni multilayers showing d-d hybridization induced PMA was studied.In particular,we record the ultrafast spin dynamics by means of time-resolved scanning magneto-optical Kerr effect(TRMOKE)microscopy.We are able to acquire the“snapshot”magnetic maps of the sample surface because of both the femtosecond temporal and submicrometer spatial resolution in our TRMOKE microscopy.Furthermore,the spatially inhomogeneous ultrafast demagnetization was observed in experiment,and this has been evidenced by simulations.展开更多
The bioactive constituents found in natural products(NPs)are crucial in protein-ligand interactions and drug discovery.However,it is difficult to identify ligand molecules from complex NPs that specifically bind to ta...The bioactive constituents found in natural products(NPs)are crucial in protein-ligand interactions and drug discovery.However,it is difficult to identify ligand molecules from complex NPs that specifically bind to target protein,which often requires time-consuming and labor-intensive processes such as isolation and enrichment.To address this issue,in this study we developed a method that combines ultra-high performance liquid chromatography-electrospray ionization-mass spectrometry(UHPLCESI-MS)with molecular dynamics(MD)simulation to identify and observe,rapidly and efficiently,the bioactive components in NPs that bind to specific protein target.In this method,a specific protein target was introduced online using a three-way valve to form a protein-ligand complex.The complex was then detected in real time using high-resolution MS to identify potential ligands.Based on our method,only 10 molecules from green tea(a representative natural product),including the commonly reported epigallocatechin gallate(EGCG)and epicatechin gallate(ECG),as well as the previously unreported eepicatechin(4β→8)-epigallocatechin 3-O-gallate(EC-EGCG)and eepiafzelechin 3-O-gallate-(4β→8)-epigallocatechin 3-O-gallate(EFG-EGCG),were screened out,which could form complexes with Aβ_(1-42)(a representative protein target),and could be potential ligands of Aβ_(1-42).Among of them,EC-EGCG demonstrated the highest binding free energy with Aβ_(1-42)(−68.54±3.82 kcal/mol).On the other side,even though the caffeine had the highest signal among green tea extracts,it was not observed to form a complex with Aβ_(1-42).Compared to other methods such as affinity selection mass spectrometry(ASMS)and native MS,our method is easy to operate and interpret the data.Undoubtedly,it provides a new methodology for potential drug discovery in NPs,and will accelerate the research on screening ligands for specific proteins from complex NPs.展开更多
Molecular dynamics(MD)simulations are employed to delve into the multifaceted effects of TiB_(2) nanoparticles on the intricate grain refinement mechanism,microstructural evolution,and tensile performance of Inconel 7...Molecular dynamics(MD)simulations are employed to delve into the multifaceted effects of TiB_(2) nanoparticles on the intricate grain refinement mechanism,microstructural evolution,and tensile performance of Inconel 718 superalloys during the rapid directional solidification.Specifically,the study focuses on elucidating the role of TiB2 nanoparticles in augmenting the nucleation rate during the rapid directional solidification process of Ni_(60)Cr_(21)Fe_(19) alloy system.Furthermore,subsequent tensile simulations are conducted to comprehensively evaluate the anisotropic behavior of tensile properties within the solidified microstructures.The MD results reveal that the incorporation of TiB₂nanoparticles during the rapid directional solidification of the Ni_(60)Cr_(21)Fe_(19) significantly enhances the average nucleation rate,escalating it from 1.27×10^(34)m^(-3)·s^(-1)to 2.55×10^(34)m^(-3)·s^(-1).Notably,within the face centered cube(FCC)structure,Ni atoms exhibit pronounced compositional segregation,and the solidified alloy maintains an exceptionally high dislocation density reaching up to 10^(16)m^(-2).Crucially,the rapid directional solidification process imparts a distinct microstructural anisotropy,leading to a notable disparity in tensile strength.Specifically,the tensile strength along the solidification direction is markedly superior to that perpendicular to it.This disparity arises from different deformation mechanisms under varying loading orientations.Tensile stress perpendicular to the solidification direction encourages the formation of smooth and organized mechanical twins.These twins act as slip planes,enhancing dislocation mobility and thereby improving stress relaxation and dispersion.Moreover,the results underscore the profound strengthening effect of TiB_(2) nanoparticles,particularly in enhancing the tensile strength along the rapid directional solidification direction.展开更多
Revealing the structure evolution of interfacial active species during a dynamic catalytic process is a challenging but pivotal issue for the rational design of high-performance catalysts.Here,we successfully prepare ...Revealing the structure evolution of interfacial active species during a dynamic catalytic process is a challenging but pivotal issue for the rational design of high-performance catalysts.Here,we successfully prepare sub-nanometric Pt clusters(~0.8 nm)encapsulated within the defects of CeO_(2)nanorods via an in-situ defect engineering methodology.The as-prepared Pt@d-CeO_(2)catalyst significantly boosts the activity and stability in the water-gas shift(WGS)reaction compared to other analogs.Based on controlled experiments and complementary(in-situ)spectroscopic studies,a reversible encapsulation induced by active site transformation between the Pt^(2+)-terminal hydroxyl and Pt^(δ+)-O vacancy species at the interface is revealed,which enables to evoke the enhanced performance.Our findings not only offer practical guidance for the design of high-efficiency catalysts but also bring a new understanding of the exceptional performance of WGS in a holistic view,which shows a great application potential in materials and catalysis.展开更多
Background Hexafluoropropylene oxide dimer acid(GenX),a substitute for per-and polyfluoroalkyl substances,has been widely detected in various environmental matrices and foods recently,attracting great attention.Howeve...Background Hexafluoropropylene oxide dimer acid(GenX),a substitute for per-and polyfluoroalkyl substances,has been widely detected in various environmental matrices and foods recently,attracting great attention.However,a systematic characterization of its reproductive toxicity is still missing.This study aims to explore the male reproductive toxicity caused by GenX exposure and the potential cellular and molecular regulatory mechanisms behind it.Results Normally developing mice were exposed to GenX,and testicular tissue was subsequently analyzed and validated using single-cell RNA sequencing.Our results revealed that GenX induced severe testicular damage,disrupted the balance between undifferentiated and differentiated spermatogonial stem cells,and led to strong variation in the cellular dynamics of spermatogenesis.Furthermore,GenX exposure caused global upregulation of testicular somatic cellular inflammatory responses,increased abnormal macrophage differentiation,and attenuated fibroblast adhesion,disorganizing the somatic-germline interactions.Conclusions In conclusion,this study revealed complex cellular dynamics and transcriptome changes in mouse testis after GenX exposure,providing a valuable resource for understanding its reproductive toxicity.展开更多
Due to scale effects,micromechanical resonators offer an excellent platform for investigating the intrinsic mechanisms of nonlinear dynamical phenomena and their potential applications.This review focuses on mode-coup...Due to scale effects,micromechanical resonators offer an excellent platform for investigating the intrinsic mechanisms of nonlinear dynamical phenomena and their potential applications.This review focuses on mode-coupled micromechanical resonators,highlighting the latest advancements in four key areas:internal resonance,synchronization,frequency combs,and mode localization.The origin,development,and potential applications of each of these dynamic phenomena within mode-coupled micromechanical systems are investigated,with the goal of inspiring new ideas and directions for researchers in this field.展开更多
Gas quenching and vacuum quenching process are widely applied to accelerate solvent volatilization to induce nucleation of perovskites in blade-coating method.In this work,we found these two pre-crystallization proces...Gas quenching and vacuum quenching process are widely applied to accelerate solvent volatilization to induce nucleation of perovskites in blade-coating method.In this work,we found these two pre-crystallization processes lead to different order of crystallization dynamics within the perovskite thin film,resulting in the differences of additive distribution.We then tailor-designed an additive molecule named 1,3-bis(4-methoxyphenyl)thiourea to obtain films with fewer defects and holes at the buried interface,and prepared perovskite solar cells with a certified efficiency of 23.75%.Furthermore,this work also demonstrates an efficiency of 20.18%for the large-area perovskite solar module(PSM)with an aperture area of 60.84 cm^(2).The PSM possesses remarkable continuous operation stability for maximum power point tracking of T_(90)>1000 h in ambient air.展开更多
This study investigates using an antioxidation copper particle-free paste,formulated with self-reducing copper formate,for Cu-Cu bonding in electronic packaging applications.The research highlights the oxidation resis...This study investigates using an antioxidation copper particle-free paste,formulated with self-reducing copper formate,for Cu-Cu bonding in electronic packaging applications.The research highlights the oxidation resistance of copper formate compared to traditional copper nanoparticles(CuNPs)and its ability to generate CuNPs through thermal decomposition.Experimental results demonstrate that the sintering process benefits from releasing reductive gases during decomposition,improving joint quality with reduced porosity and enhanced mechanical strength at elevated temperatures.Molecular dynamics simulations further elucidate the sintering behavior of CuNPs,providing significant insights into pore collapse,atomic mobility,and neck formation.The findings indicate that increased temperatures enhance surface and bulk diffusion,facilitating robust particle connections.Overall,this work establishes the potential of copper formate for achieving reliable interconnects in semiconductor devices,paving the way for advancements in material formulations for direct copper–copper bonding.展开更多
The fatigue fracture under cyclic dynamic direct tensions of brittle rock is an important mechanical characteristic index for the evaluation of geological disasters and underground engineering safety.However,most stud...The fatigue fracture under cyclic dynamic direct tensions of brittle rock is an important mechanical characteristic index for the evaluation of geological disasters and underground engineering safety.However,most studies focus on macroscopic fracture mechanical properties,and the mechanism linking the macroscopic fracture with the microcrack growth during the cyclic dynamic direct tensile loading of brittle rocks is rarely studied.In this paper,a micro-macro fracture model explaining the stress-strain constitutive relationship is established at the last impact failure after being subjected to multiple cyclic direct tensile impacts of brittle rocks.This model is based on the wing crack extension model under direct tensile loading,the quasi-static and dynamic fracture toughness relationship,the suggested crack rate and strain rate relationship,the relationship of damage and dynamic tensile fatigue life N,the relationship of dynamic fracture toughness and dynamic tensile fatigue life N.The variations of dynamic mechanical properties of rocks with dynamic tensile fatigue life for different initial crack sizes and angles within the rocks are further discussed.The compressive strength,elastic modulus,crack initiation stress,limit crack extension length and crack extension rate descend and the failure strain ascends with an increment of dynamic tensile fatigue life in rocks.This study's results provide help for the safety and stability of the underground surrounding rocks under blasting working or seismic disasters.展开更多
The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic e...The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic elucidation of the occurrence characteristics,flow behavior,and enhanced oil recovery(EOR)mechanisms of shale oil within commonly developed nanopores.Molecular dynamics(MD)technique can simulate the occurrence,flow,and extraction processes of shale oil at the nanoscale,and then quantitatively characterize various fluid properties,flow characteristics,and action mechanisms under different reservoir conditions by calculating and analyzing a series of MD parameters.However,the existing review on the application of MD simulation in shale oil reservoirs is not systematic enough and lacks a summary of technical challenges and solutions.Therefore,recent MD studies on shale oil res-ervoirs were summarized and analyzed.Firstly,the applicability of force fields and ensembles of MD in shale reservoirs with different reservoir conditions and fluid properties was discussed.Subsequently,the calculation methods and application examples of MD parameters characterizing various properties of fluids at the microscale were summarized.Then,the application of MD simulation in the study of shale oil occurrence characteristics,flow behavior,and EOR mechanisms was reviewed,along with the elucidation of corresponding micro-mechanisms.Moreover,influencing factors of pore structure,wall properties,reservoir conditions,fluid components,injection/production parameters,formation water,and inorganic salt ions were analyzed,and some new conclusions were obtained.Finally,the main challenges associated with the application of MD simulations to shale oil reservoirs were discussed,and reasonable prospects for future MD research directions were proposed.The purpose of this review is to provide theoretical basis and methodological support for applying MD simulation to study shale oil reservoirs.展开更多
This paper addresses urban sustainability challenges amid global urbanization, emphasizing the need for innova tive approaches aligned with the Sustainable Development Goals. While traditional tools and linear models ...This paper addresses urban sustainability challenges amid global urbanization, emphasizing the need for innova tive approaches aligned with the Sustainable Development Goals. While traditional tools and linear models offer insights, they fall short in presenting a holistic view of complex urban challenges. System dynamics (SD) models that are often utilized to provide holistic, systematic understanding of a research subject, like the urban system, emerge as valuable tools, but data scarcity and theoretical inadequacy pose challenges. The research reviews relevant papers on recent SD model applications in urban sustainability since 2018, categorizing them based on nine key indicators. Among the reviewed papers, data limitations and model assumptions were identified as ma jor challenges in applying SD models to urban sustainability. This led to exploring the transformative potential of big data analytics, a rare approach in this field as identified by this study, to enhance SD models’ empirical foundation. Integrating big data could provide data-driven calibration, potentially improving predictive accuracy and reducing reliance on simplified assumptions. The paper concludes by advocating for new approaches that reduce assumptions and promote real-time applicable models, contributing to a comprehensive understanding of urban sustainability through the synergy of big data and SD models.展开更多
Efficient and stable photocathodes with versatility are of significance in photoassisted lithium-ion batteries(PLIBs),while there is always a request on fast carrier transport in electrochemical active photocathodes.P...Efficient and stable photocathodes with versatility are of significance in photoassisted lithium-ion batteries(PLIBs),while there is always a request on fast carrier transport in electrochemical active photocathodes.Present work proposes a general approach of creating bulk heterojunction to boost the carrier mobility of photocathodes by simply laser assisted embedding of plasmonic nanocrystals.When employed in PLIBs,it was found effective for synchronously enhanced photocharge separation and transport in light charging process.Additionally,experimental photon spectroscopy,finite difference time domain method simulation and theoretical analyses demonstrate that the improved carrier dynamics are driven by the plasmonic-induced hot electron injection from metal to TiO_(2),as well as the enhanced conductivity in TiO2 matrix due to the formation of oxygen vacancies after Schottky contact.Benefiting from these merits,several benchmark values in performance of TiO2-based photocathode applied in PLIBs are set,including the capacity of 276 mAh g^(−1) at 0.2 A g^(−1) under illumination,photoconversion efficiency of 1.276%at 3 A g^(−1),less capacity and Columbic efficiency loss even through 200 cycles.These results exemplify the potential of the bulk heterojunction strategy in developing highly efficient and stable photoassisted energy storage systems.展开更多
Currently,there are a limited number of dynamic models available for braided composite plates with large overall motions,despite the incorporation of three-dimensional(3D)braided composites into rotating blade compone...Currently,there are a limited number of dynamic models available for braided composite plates with large overall motions,despite the incorporation of three-dimensional(3D)braided composites into rotating blade components.In this paper,a dynamic model of 3D 4-directional braided composite thin plates considering braiding directions is established.Based on Kirchhoff's plate assumptions,the displacement variables of the plate are expressed.By incorporating the braiding directions into the constitutive equation of the braided composites,the dynamic model of the plate considering braiding directions is obtained.The effects of the speeds,braiding directions,and braided angles on the responses of the plate with fixed-axis rotation and translational motion,respectively,are investigated.This paper presents a dynamic theory for calculating the deformation of 3D braided composite structures undergoing both translational and rotational motions.It also provides a simulation method for investigating the dynamic behavior of non-isotropic material plates in various applications.展开更多
The charge carrier transport and recombination dynamics in the quantum dots-based light-emitting diodes(QLEDs)featuring multiple emitting layers(M-EMLs)has a great impact on the device performance.In this work,QLEDs b...The charge carrier transport and recombination dynamics in the quantum dots-based light-emitting diodes(QLEDs)featuring multiple emitting layers(M-EMLs)has a great impact on the device performance.In this work,QLEDs based on M-EMLs separated by polyethyleneimine ethoxylated(PEIE)layer with different stacking sequences of blue(B),green(G),and red(R)QDs layer were used to intuitively explore the injection,transportation and recombination processes of the charge carriers in QLEDs by using the time-resolved electroluminescence(TrEL)spectra.From the TrEL spectra mea-surements,green and red emissions were obtained first in the QLEDs with the EMLs sequences of G/PEIE/B/PEIE/R and B/PEIE/R/PEIE/G along the direction of light emission,respectively.While the QLEDs adopt EMLs sequences of B/PEIE/G/PEIE/R,the blue,green and red emissions were obtained nearly at the same time.The above phenomenon can be attributed to different charge carrier transmission and radiation recombination process in the EMLs due to different valence band offsets and conduction band offsets between R-,G-and B-QDs by using different sequences of EMLs.White emission with coordi-nates of(0.31,0.31)and correlated color temperature(CCT)of 5916 K was obtained in the QLEDs with the EMLs se-quences of B/PEIE/G/PEIE/R,which can be attributed to the relative uniform emission of B-,G-and R-QDs due to the effec-tive injection and radiation recombination of charge carriers in each of the EMLs.The above results have great significance for further understanding and improving the performance of QLEDs with M-EMLs.展开更多
The extraordinary strength of metal/graphene composites is significantly determined by the characteristic size,distribution and morphology of graphene.However,the effect of the graphene size/distribution on the mechan...The extraordinary strength of metal/graphene composites is significantly determined by the characteristic size,distribution and morphology of graphene.However,the effect of the graphene size/distribution on the mechanical properties and related strengthening mechanisms has not been fully elucidated.Herein,under the same volume fraction and distribution conditions of graphene,molecular dynamics simulations were used to investigate the effect of graphene sheet size on the hardness and deformation behavior of Cu/graphene composites under complex stress field.Two models of pure single crystalline Cu and graphene fully covered Cu matrix composite were constructed for comparison.The results show that the strengthening effect changes with varying the graphene sheet size.Besides the graphene dislocation blocking effect and the load-bearing effect,the deformation mechanisms change from stacking fault tetrahedron,dislocation bypassing and dislocation cutting to dislocation nucleation in turn with decreasing the graphene sheet size.The hardness of Cu/graphene composite,with the graphene sheet not completely covering the metal matrix,can even be higher than that of the fully covered composite.The extra strengthening mechanisms of dislocation bypassing mechanism and the stacking fault tetrahedra pinning dislocation mechanism contribute to the increase in hardness.展开更多
We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the p...We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the photoexcited carrier dynamics, which can be attributed to the electron-spin and spin-lattice scattering processes influenced by the magnetic phase transition and modifications in magnetic anisotropy. The magnetization change can be revealed by the dynamics of coherent acoustic phonon. We also observe abrupt changes in the photoinduced spin dynamics near T^(*)and T^(†), which not only illustrate the spin-related scatterings closely related to the long-range magnetic order, but also reveal the D'yakonov–Perel and Elliott–Yafet mechanisms dominating at temperatures below and above T^(†), respectively. Our findings provide important insights into the nonequilibrium properties of the photoexcited(In,Fe)Sb.展开更多
The integration of renewable energy sources(RESs)with inverter interfaces has fundamentally reshaped power system dynamics,challenging traditional stability analysis frameworks designed for synchronous generator-domin...The integration of renewable energy sources(RESs)with inverter interfaces has fundamentally reshaped power system dynamics,challenging traditional stability analysis frameworks designed for synchronous generator-dominated grids.Conventional classifica-tions,which decouple voltage,frequency,and rotor angle stability,fail to address the emerging strong voltage‒angle coupling effects caused by RES dynamics.This coupling introduces complex oscillation modes and undermines system robustness,neces-sitating novel stability assessment tools.Recent studies focus on eigenvalue distributions and damping redistribution but lack quantitative criteria and interpretative clarity for coupled stability.This work proposes a transient energy-based framework to resolve these gaps.By decomposing transient energy into subsystem-dissipated components and coupling-induced energy exchange,the method establishes stability criteria compatible with a broad variety of inverter-interfaced devices while offering an intuitive energy-based interpretation for engineers.The coupling strength is also quantified by defining the relative coupling strength index,which is directly related to the transient energy interpretation of the coupled stability.Angle‒voltage coupling may induce instability by injecting transient energy into the system,even if the individual phase angle and voltage dynamics themselves are stable.The main contributions include a systematic stability evaluation framework and an energy decomposition approach that bridges theoretical analysis with practical applicability,addressing the urgent need for tools for managing modern power system evolving stability challenges.展开更多
The quantity of space debris on Earth orbit has escalated tremendously in recent years, presenting a significant hazard to human space operations. It is urgent to develop effective measures to capture and remove vario...The quantity of space debris on Earth orbit has escalated tremendously in recent years, presenting a significant hazard to human space operations. It is urgent to develop effective measures to capture and remove various space debris. For this purpose, this paper presents a tendon-actuated flexible deployable manipulator. The flexible manipulator consists of several deployable units connected by Cardan joints and actuated by tendons. Compared with the present technologies for capturing space debris such as rigid robotic arm or flying net, this flexible manipulator is deployable, reusable, lightweight and applicable to the capture of large space debris. In order to investigate its deployment dynamics, an accurate dynamic model of the flexible manipulator is established based on the natural coordinate formulation (NCF) and the absolute nodal coordinate formulation (ANCF). Subsequently, numerical simulations are carried out to study the effects of system parameters and the base satellite on its deployment dynamics. Finally, ground experiments for both deployment and bending of the flexible manipulator are conducted to verify its effectiveness and feasibility.展开更多
In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not ...In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.展开更多
基金supported by the Fund from the Science and Technology Department of Henan Province,China(Grant Nos.222102210233 and 232102210064)the National Natural Science Foundation of China(Grant Nos.62373169 and 72474086)+5 种基金the Young and Midcareer Academic Leader of Jiangsu Province,China(Grant No.Qinglan Project in 2024)the National Statistical Science Research Project(Grant No.2022LZ03)Shaanxi Provincial Soft Science Project(Grant No.2022KRM111)Shaanxi Provincial Social Science Foundation(Grant No.2022R016)the Special Project for Philosophical and Social Sciences Research in Shaanxi Province,China(Grant No.2024QN018)the Fund from the Henan Office of Philosophy and Social Science(Grant No.2023CJJ112).
文摘Recent advances in statistical physics highlight the significant potential of machine learning for phase transition recognition.This study introduces a deep learning framework based on graph neural network to investigate non-equilibrium phase transitions,specifically focusing on the directed percolation process.By converting lattices with varying dimensions and connectivity schemes into graph structures and embedding the temporal evolution of the percolation process into node features,our approach enables unified analysis across diverse systems.The framework utilizes a multi-layer graph attention mechanism combined with global pooling to autonomously extract critical features from local dynamics to global phase transition signatures.The model successfully predicts percolation thresholds without relying on lattice geometry,demonstrating its robustness and versatility.Our approach not only offers new insights into phase transition studies but also provides a powerful tool for analyzing complex dynamical systems across various domains.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFA1403302)the National Natural Science Foundation of China(Grant Nos.52031015,U22A20115,and 12104030)+1 种基金the Natural Science Foundation of Zhejiang Province,China(Grant No.LZ25A040007)the Natural Science Foundation of Beijing(Grant No.1252026).
文摘Bit patterned recording(BPR)has attracted much attention due to its promising potential in achieving high densities in magnetic storage devices.The materials with strong perpendicular magnetic anisotropy(PMA)are always preferred in designing the BPR.Here,the patterned Co/Ni multilayers showing d-d hybridization induced PMA was studied.In particular,we record the ultrafast spin dynamics by means of time-resolved scanning magneto-optical Kerr effect(TRMOKE)microscopy.We are able to acquire the“snapshot”magnetic maps of the sample surface because of both the femtosecond temporal and submicrometer spatial resolution in our TRMOKE microscopy.Furthermore,the spatially inhomogeneous ultrafast demagnetization was observed in experiment,and this has been evidenced by simulations.
基金supported by the National Key R&D Program of China(No.2018YFA0800900).
文摘The bioactive constituents found in natural products(NPs)are crucial in protein-ligand interactions and drug discovery.However,it is difficult to identify ligand molecules from complex NPs that specifically bind to target protein,which often requires time-consuming and labor-intensive processes such as isolation and enrichment.To address this issue,in this study we developed a method that combines ultra-high performance liquid chromatography-electrospray ionization-mass spectrometry(UHPLCESI-MS)with molecular dynamics(MD)simulation to identify and observe,rapidly and efficiently,the bioactive components in NPs that bind to specific protein target.In this method,a specific protein target was introduced online using a three-way valve to form a protein-ligand complex.The complex was then detected in real time using high-resolution MS to identify potential ligands.Based on our method,only 10 molecules from green tea(a representative natural product),including the commonly reported epigallocatechin gallate(EGCG)and epicatechin gallate(ECG),as well as the previously unreported eepicatechin(4β→8)-epigallocatechin 3-O-gallate(EC-EGCG)and eepiafzelechin 3-O-gallate-(4β→8)-epigallocatechin 3-O-gallate(EFG-EGCG),were screened out,which could form complexes with Aβ_(1-42)(a representative protein target),and could be potential ligands of Aβ_(1-42).Among of them,EC-EGCG demonstrated the highest binding free energy with Aβ_(1-42)(−68.54±3.82 kcal/mol).On the other side,even though the caffeine had the highest signal among green tea extracts,it was not observed to form a complex with Aβ_(1-42).Compared to other methods such as affinity selection mass spectrometry(ASMS)and native MS,our method is easy to operate and interpret the data.Undoubtedly,it provides a new methodology for potential drug discovery in NPs,and will accelerate the research on screening ligands for specific proteins from complex NPs.
基金supported by the Na⁃tional Natural Science Foundation of China(Nos.12462006,12062016)the high-performance computing services of⁃fered by the Information Center of Nanchang Hangkong Uni⁃versity.
文摘Molecular dynamics(MD)simulations are employed to delve into the multifaceted effects of TiB_(2) nanoparticles on the intricate grain refinement mechanism,microstructural evolution,and tensile performance of Inconel 718 superalloys during the rapid directional solidification.Specifically,the study focuses on elucidating the role of TiB2 nanoparticles in augmenting the nucleation rate during the rapid directional solidification process of Ni_(60)Cr_(21)Fe_(19) alloy system.Furthermore,subsequent tensile simulations are conducted to comprehensively evaluate the anisotropic behavior of tensile properties within the solidified microstructures.The MD results reveal that the incorporation of TiB₂nanoparticles during the rapid directional solidification of the Ni_(60)Cr_(21)Fe_(19) significantly enhances the average nucleation rate,escalating it from 1.27×10^(34)m^(-3)·s^(-1)to 2.55×10^(34)m^(-3)·s^(-1).Notably,within the face centered cube(FCC)structure,Ni atoms exhibit pronounced compositional segregation,and the solidified alloy maintains an exceptionally high dislocation density reaching up to 10^(16)m^(-2).Crucially,the rapid directional solidification process imparts a distinct microstructural anisotropy,leading to a notable disparity in tensile strength.Specifically,the tensile strength along the solidification direction is markedly superior to that perpendicular to it.This disparity arises from different deformation mechanisms under varying loading orientations.Tensile stress perpendicular to the solidification direction encourages the formation of smooth and organized mechanical twins.These twins act as slip planes,enhancing dislocation mobility and thereby improving stress relaxation and dispersion.Moreover,the results underscore the profound strengthening effect of TiB_(2) nanoparticles,particularly in enhancing the tensile strength along the rapid directional solidification direction.
文摘Revealing the structure evolution of interfacial active species during a dynamic catalytic process is a challenging but pivotal issue for the rational design of high-performance catalysts.Here,we successfully prepare sub-nanometric Pt clusters(~0.8 nm)encapsulated within the defects of CeO_(2)nanorods via an in-situ defect engineering methodology.The as-prepared Pt@d-CeO_(2)catalyst significantly boosts the activity and stability in the water-gas shift(WGS)reaction compared to other analogs.Based on controlled experiments and complementary(in-situ)spectroscopic studies,a reversible encapsulation induced by active site transformation between the Pt^(2+)-terminal hydroxyl and Pt^(δ+)-O vacancy species at the interface is revealed,which enables to evoke the enhanced performance.Our findings not only offer practical guidance for the design of high-efficiency catalysts but also bring a new understanding of the exceptional performance of WGS in a holistic view,which shows a great application potential in materials and catalysis.
基金supported by the Guangdong Provincial Key Area Research and Development Program[grant number 2022B0202090002]China Postdoctoral Science Foundation[grant number 2024M760977].
文摘Background Hexafluoropropylene oxide dimer acid(GenX),a substitute for per-and polyfluoroalkyl substances,has been widely detected in various environmental matrices and foods recently,attracting great attention.However,a systematic characterization of its reproductive toxicity is still missing.This study aims to explore the male reproductive toxicity caused by GenX exposure and the potential cellular and molecular regulatory mechanisms behind it.Results Normally developing mice were exposed to GenX,and testicular tissue was subsequently analyzed and validated using single-cell RNA sequencing.Our results revealed that GenX induced severe testicular damage,disrupted the balance between undifferentiated and differentiated spermatogonial stem cells,and led to strong variation in the cellular dynamics of spermatogenesis.Furthermore,GenX exposure caused global upregulation of testicular somatic cellular inflammatory responses,increased abnormal macrophage differentiation,and attenuated fibroblast adhesion,disorganizing the somatic-germline interactions.Conclusions In conclusion,this study revealed complex cellular dynamics and transcriptome changes in mouse testis after GenX exposure,providing a valuable resource for understanding its reproductive toxicity.
基金supported by the National Key Research and Development Program of China(No.2022YFB3203600)the National Natural Science Foundation of China(Nos.12202355,12132013,and 12172323)the Zhejiang Provincial Natural Science Foundation of China(No.LZ22A020003)。
文摘Due to scale effects,micromechanical resonators offer an excellent platform for investigating the intrinsic mechanisms of nonlinear dynamical phenomena and their potential applications.This review focuses on mode-coupled micromechanical resonators,highlighting the latest advancements in four key areas:internal resonance,synchronization,frequency combs,and mode localization.The origin,development,and potential applications of each of these dynamic phenomena within mode-coupled micromechanical systems are investigated,with the goal of inspiring new ideas and directions for researchers in this field.
基金supported by National Natural Science Foundation of China(62104082)Guangdong Basic and Applied Basic Research Foundation(2022A1515010746,2022A1515011228,and 2022B1515120006)the Science and Technology Program of Guangzhou(202201010458).
文摘Gas quenching and vacuum quenching process are widely applied to accelerate solvent volatilization to induce nucleation of perovskites in blade-coating method.In this work,we found these two pre-crystallization processes lead to different order of crystallization dynamics within the perovskite thin film,resulting in the differences of additive distribution.We then tailor-designed an additive molecule named 1,3-bis(4-methoxyphenyl)thiourea to obtain films with fewer defects and holes at the buried interface,and prepared perovskite solar cells with a certified efficiency of 23.75%.Furthermore,this work also demonstrates an efficiency of 20.18%for the large-area perovskite solar module(PSM)with an aperture area of 60.84 cm^(2).The PSM possesses remarkable continuous operation stability for maximum power point tracking of T_(90)>1000 h in ambient air.
基金financially supported by the Shenzhen Science and Technology Project(GXWD20220818163456002)the Key-Area Research and Development Program of Guangdong Province(No.2022B0701180002)+1 种基金the Sauvage Laboratory for Smart Materials of Harbin Institute of Technology(Shenzhen)the Guangdong Province College Students Science and Technology Innovation Cultivation Special Project.
文摘This study investigates using an antioxidation copper particle-free paste,formulated with self-reducing copper formate,for Cu-Cu bonding in electronic packaging applications.The research highlights the oxidation resistance of copper formate compared to traditional copper nanoparticles(CuNPs)and its ability to generate CuNPs through thermal decomposition.Experimental results demonstrate that the sintering process benefits from releasing reductive gases during decomposition,improving joint quality with reduced porosity and enhanced mechanical strength at elevated temperatures.Molecular dynamics simulations further elucidate the sintering behavior of CuNPs,providing significant insights into pore collapse,atomic mobility,and neck formation.The findings indicate that increased temperatures enhance surface and bulk diffusion,facilitating robust particle connections.Overall,this work establishes the potential of copper formate for achieving reliable interconnects in semiconductor devices,paving the way for advancements in material formulations for direct copper–copper bonding.
基金supported by the National Natural Science Foundation of China(Grant Nos.51708016,52438007 and 12172036)the R&D program of Beijing Municipal Education Commission(Grant No.KM202110016014)+1 种基金the Pyramid Talent Training Project of Beijing University of Civil Engineering and Architecture(Grant No.JDYC20200307)the Graduate Innovation Program of Beijing University of Civil Engineering and Architecture(Grant No.PG2025060).
文摘The fatigue fracture under cyclic dynamic direct tensions of brittle rock is an important mechanical characteristic index for the evaluation of geological disasters and underground engineering safety.However,most studies focus on macroscopic fracture mechanical properties,and the mechanism linking the macroscopic fracture with the microcrack growth during the cyclic dynamic direct tensile loading of brittle rocks is rarely studied.In this paper,a micro-macro fracture model explaining the stress-strain constitutive relationship is established at the last impact failure after being subjected to multiple cyclic direct tensile impacts of brittle rocks.This model is based on the wing crack extension model under direct tensile loading,the quasi-static and dynamic fracture toughness relationship,the suggested crack rate and strain rate relationship,the relationship of damage and dynamic tensile fatigue life N,the relationship of dynamic fracture toughness and dynamic tensile fatigue life N.The variations of dynamic mechanical properties of rocks with dynamic tensile fatigue life for different initial crack sizes and angles within the rocks are further discussed.The compressive strength,elastic modulus,crack initiation stress,limit crack extension length and crack extension rate descend and the failure strain ascends with an increment of dynamic tensile fatigue life in rocks.This study's results provide help for the safety and stability of the underground surrounding rocks under blasting working or seismic disasters.
基金supported by the National Natural Science Foundation of China(52304021,52104022,52204031)the Natural Science Foundation of Sichuan Province(2022NSFSC0205,2024NSFSC0201,2023NSFSC0947)the National Science and Technology Major Projects of China(2017ZX05049006-010).
文摘The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic elucidation of the occurrence characteristics,flow behavior,and enhanced oil recovery(EOR)mechanisms of shale oil within commonly developed nanopores.Molecular dynamics(MD)technique can simulate the occurrence,flow,and extraction processes of shale oil at the nanoscale,and then quantitatively characterize various fluid properties,flow characteristics,and action mechanisms under different reservoir conditions by calculating and analyzing a series of MD parameters.However,the existing review on the application of MD simulation in shale oil reservoirs is not systematic enough and lacks a summary of technical challenges and solutions.Therefore,recent MD studies on shale oil res-ervoirs were summarized and analyzed.Firstly,the applicability of force fields and ensembles of MD in shale reservoirs with different reservoir conditions and fluid properties was discussed.Subsequently,the calculation methods and application examples of MD parameters characterizing various properties of fluids at the microscale were summarized.Then,the application of MD simulation in the study of shale oil occurrence characteristics,flow behavior,and EOR mechanisms was reviewed,along with the elucidation of corresponding micro-mechanisms.Moreover,influencing factors of pore structure,wall properties,reservoir conditions,fluid components,injection/production parameters,formation water,and inorganic salt ions were analyzed,and some new conclusions were obtained.Finally,the main challenges associated with the application of MD simulations to shale oil reservoirs were discussed,and reasonable prospects for future MD research directions were proposed.The purpose of this review is to provide theoretical basis and methodological support for applying MD simulation to study shale oil reservoirs.
基金sponsored by the U.S.Department of Housing and Urban Development(Grant No.NJLTS0027-22)The opinions expressed in this study are the authors alone,and do not represent the U.S.Depart-ment of HUD’s opinions.
文摘This paper addresses urban sustainability challenges amid global urbanization, emphasizing the need for innova tive approaches aligned with the Sustainable Development Goals. While traditional tools and linear models offer insights, they fall short in presenting a holistic view of complex urban challenges. System dynamics (SD) models that are often utilized to provide holistic, systematic understanding of a research subject, like the urban system, emerge as valuable tools, but data scarcity and theoretical inadequacy pose challenges. The research reviews relevant papers on recent SD model applications in urban sustainability since 2018, categorizing them based on nine key indicators. Among the reviewed papers, data limitations and model assumptions were identified as ma jor challenges in applying SD models to urban sustainability. This led to exploring the transformative potential of big data analytics, a rare approach in this field as identified by this study, to enhance SD models’ empirical foundation. Integrating big data could provide data-driven calibration, potentially improving predictive accuracy and reducing reliance on simplified assumptions. The paper concludes by advocating for new approaches that reduce assumptions and promote real-time applicable models, contributing to a comprehensive understanding of urban sustainability through the synergy of big data and SD models.
基金supported by the project of the National Natural Science Foundation of China(52202115 and 52172101)Guangdong Basic and Applied Basic Research Foundation(2024A1515012325)+2 种基金the Natural Science Foundation of Chongqing,China(CSTB2022NSCQ-MSX1085)the Shaanxi Science and Technology Innovation Team(2023-CXTD-44)the Fundamental Research Funds for the Central Universities(G2022KY0604).
文摘Efficient and stable photocathodes with versatility are of significance in photoassisted lithium-ion batteries(PLIBs),while there is always a request on fast carrier transport in electrochemical active photocathodes.Present work proposes a general approach of creating bulk heterojunction to boost the carrier mobility of photocathodes by simply laser assisted embedding of plasmonic nanocrystals.When employed in PLIBs,it was found effective for synchronously enhanced photocharge separation and transport in light charging process.Additionally,experimental photon spectroscopy,finite difference time domain method simulation and theoretical analyses demonstrate that the improved carrier dynamics are driven by the plasmonic-induced hot electron injection from metal to TiO_(2),as well as the enhanced conductivity in TiO2 matrix due to the formation of oxygen vacancies after Schottky contact.Benefiting from these merits,several benchmark values in performance of TiO2-based photocathode applied in PLIBs are set,including the capacity of 276 mAh g^(−1) at 0.2 A g^(−1) under illumination,photoconversion efficiency of 1.276%at 3 A g^(−1),less capacity and Columbic efficiency loss even through 200 cycles.These results exemplify the potential of the bulk heterojunction strategy in developing highly efficient and stable photoassisted energy storage systems.
基金Project supported by the National Natural Science Foundation of China(Nos.12372071 and 12372070)the Aeronautical Science Fund of China(No.2022Z055052001)the Foundation of China Scholarship Council(No.202306830079)。
文摘Currently,there are a limited number of dynamic models available for braided composite plates with large overall motions,despite the incorporation of three-dimensional(3D)braided composites into rotating blade components.In this paper,a dynamic model of 3D 4-directional braided composite thin plates considering braiding directions is established.Based on Kirchhoff's plate assumptions,the displacement variables of the plate are expressed.By incorporating the braiding directions into the constitutive equation of the braided composites,the dynamic model of the plate considering braiding directions is obtained.The effects of the speeds,braiding directions,and braided angles on the responses of the plate with fixed-axis rotation and translational motion,respectively,are investigated.This paper presents a dynamic theory for calculating the deformation of 3D braided composite structures undergoing both translational and rotational motions.It also provides a simulation method for investigating the dynamic behavior of non-isotropic material plates in various applications.
文摘The charge carrier transport and recombination dynamics in the quantum dots-based light-emitting diodes(QLEDs)featuring multiple emitting layers(M-EMLs)has a great impact on the device performance.In this work,QLEDs based on M-EMLs separated by polyethyleneimine ethoxylated(PEIE)layer with different stacking sequences of blue(B),green(G),and red(R)QDs layer were used to intuitively explore the injection,transportation and recombination processes of the charge carriers in QLEDs by using the time-resolved electroluminescence(TrEL)spectra.From the TrEL spectra mea-surements,green and red emissions were obtained first in the QLEDs with the EMLs sequences of G/PEIE/B/PEIE/R and B/PEIE/R/PEIE/G along the direction of light emission,respectively.While the QLEDs adopt EMLs sequences of B/PEIE/G/PEIE/R,the blue,green and red emissions were obtained nearly at the same time.The above phenomenon can be attributed to different charge carrier transmission and radiation recombination process in the EMLs due to different valence band offsets and conduction band offsets between R-,G-and B-QDs by using different sequences of EMLs.White emission with coordi-nates of(0.31,0.31)and correlated color temperature(CCT)of 5916 K was obtained in the QLEDs with the EMLs se-quences of B/PEIE/G/PEIE/R,which can be attributed to the relative uniform emission of B-,G-and R-QDs due to the effec-tive injection and radiation recombination of charge carriers in each of the EMLs.The above results have great significance for further understanding and improving the performance of QLEDs with M-EMLs.
基金Foundation of Northwest Institute for Nonferrous Metal Research(ZZXJ2203)Capital Projects of Financial Department of Shaanxi Province(YK22C-12)+3 种基金Innovation Capability Support Plan in Shaanxi Province(2023KJXX-083)Key Research and Development Projects of Shaanxi Province(2024GXYBXM-351,2024GX-YBXM-356)National Natural Science Foundation of China(62204207,12204383)Xi'an Postdoctoral Innovation Base Funding Program。
文摘The extraordinary strength of metal/graphene composites is significantly determined by the characteristic size,distribution and morphology of graphene.However,the effect of the graphene size/distribution on the mechanical properties and related strengthening mechanisms has not been fully elucidated.Herein,under the same volume fraction and distribution conditions of graphene,molecular dynamics simulations were used to investigate the effect of graphene sheet size on the hardness and deformation behavior of Cu/graphene composites under complex stress field.Two models of pure single crystalline Cu and graphene fully covered Cu matrix composite were constructed for comparison.The results show that the strengthening effect changes with varying the graphene sheet size.Besides the graphene dislocation blocking effect and the load-bearing effect,the deformation mechanisms change from stacking fault tetrahedron,dislocation bypassing and dislocation cutting to dislocation nucleation in turn with decreasing the graphene sheet size.The hardness of Cu/graphene composite,with the graphene sheet not completely covering the metal matrix,can even be higher than that of the fully covered composite.The extra strengthening mechanisms of dislocation bypassing mechanism and the stacking fault tetrahedra pinning dislocation mechanism contribute to the increase in hardness.
基金supported by the National Key R&D Program of China (Grant No. 2024YFA1408502)the National Natural Science Foundation of China (Grant Nos. 92365102, 62027807, 12474107, and 12174383)+1 种基金the Chinese Academy of Sciences project for Yong Scientists in Basic Research (Grant No. YSBR-030)the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2024A1515011600)。
文摘We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the photoexcited carrier dynamics, which can be attributed to the electron-spin and spin-lattice scattering processes influenced by the magnetic phase transition and modifications in magnetic anisotropy. The magnetization change can be revealed by the dynamics of coherent acoustic phonon. We also observe abrupt changes in the photoinduced spin dynamics near T^(*)and T^(†), which not only illustrate the spin-related scatterings closely related to the long-range magnetic order, but also reveal the D'yakonov–Perel and Elliott–Yafet mechanisms dominating at temperatures below and above T^(†), respectively. Our findings provide important insights into the nonequilibrium properties of the photoexcited(In,Fe)Sb.
基金supported by the Science and Technology Project of China Southern Power Grid Co.,Ltd under Grant 036000KC23090004(GDKJXM20231026).
文摘The integration of renewable energy sources(RESs)with inverter interfaces has fundamentally reshaped power system dynamics,challenging traditional stability analysis frameworks designed for synchronous generator-dominated grids.Conventional classifica-tions,which decouple voltage,frequency,and rotor angle stability,fail to address the emerging strong voltage‒angle coupling effects caused by RES dynamics.This coupling introduces complex oscillation modes and undermines system robustness,neces-sitating novel stability assessment tools.Recent studies focus on eigenvalue distributions and damping redistribution but lack quantitative criteria and interpretative clarity for coupled stability.This work proposes a transient energy-based framework to resolve these gaps.By decomposing transient energy into subsystem-dissipated components and coupling-induced energy exchange,the method establishes stability criteria compatible with a broad variety of inverter-interfaced devices while offering an intuitive energy-based interpretation for engineers.The coupling strength is also quantified by defining the relative coupling strength index,which is directly related to the transient energy interpretation of the coupled stability.Angle‒voltage coupling may induce instability by injecting transient energy into the system,even if the individual phase angle and voltage dynamics themselves are stable.The main contributions include a systematic stability evaluation framework and an energy decomposition approach that bridges theoretical analysis with practical applicability,addressing the urgent need for tools for managing modern power system evolving stability challenges.
基金the National Natural Science Foundation of China(Nos.11832005,12372042,12232011)Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001)+1 种基金the Fundamental Research Funds for the Central Universities(No.NS2023002)State Key Laboratory of Mechanics and Control for Aerospace Structures(Nanjing University of Aeronautics and Astronautics)(No.MCAS-S-0223K04).
文摘The quantity of space debris on Earth orbit has escalated tremendously in recent years, presenting a significant hazard to human space operations. It is urgent to develop effective measures to capture and remove various space debris. For this purpose, this paper presents a tendon-actuated flexible deployable manipulator. The flexible manipulator consists of several deployable units connected by Cardan joints and actuated by tendons. Compared with the present technologies for capturing space debris such as rigid robotic arm or flying net, this flexible manipulator is deployable, reusable, lightweight and applicable to the capture of large space debris. In order to investigate its deployment dynamics, an accurate dynamic model of the flexible manipulator is established based on the natural coordinate formulation (NCF) and the absolute nodal coordinate formulation (ANCF). Subsequently, numerical simulations are carried out to study the effects of system parameters and the base satellite on its deployment dynamics. Finally, ground experiments for both deployment and bending of the flexible manipulator are conducted to verify its effectiveness and feasibility.
基金supported by the Guangdong Basic and Applied Basic Research Foundation (No.2023A1515010093)the Shenzhen Fundamental Research Program (Stable Support Plan Program)(Nos.JCYJ20220809170611004, 20231121110828001 and 20231121113641002)the National Taipei University of Technology-Shenzhen University Joint Research Program (No.2024001)。
文摘In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.
