The advancement of integrated die-casting technology calls for high-strength,high-ductility heat-treatment-free Al alloys.This study investigates the use of a new AlSiFeMnVTiSrZr heat-treatment-free die-casting alloy ...The advancement of integrated die-casting technology calls for high-strength,high-ductility heat-treatment-free Al alloys.This study investigates the use of a new AlSiFeMnVTiSrZr heat-treatment-free die-casting alloy for shock tower manufacturing.Results show the alloy has excellent overall mechanical properties,but significant regional differences in microstructure and performance are found in the shock tower casting:Far-gate Position 6 has almost no externally solidified crystals(ESCs),whereas dense coarse dendritic ESCs exist in the center of near-gate Position 5.The fracture surface of Position 6 shows a steeper slope,while Position 5 has a rough crack propagation platform.Far-gate Position 6 also has higher porosity(nearly triple that of near-gate Region 5)and larger average pore size.Analysis reveals microstructural heterogeneity between near-and far-gate regions strongly influences mechanical performance.Notably,coarse dendritic ESCs in the near-gate region restrict grain boundary strengthening,leading to lower yield strength despite low porosity.Conversely,while fine grains in the far-gate region could enhance grain boundary strengthening,abundant porosity acts as crack initiation sites,severely reducing ductility.These findings provide theoretical guidance for evaluating integrated die-cast component performance.展开更多
This study investigates the uncertain dynamic characterization of hybrid composite plates by employing advanced machine-assisted finite element methodologies.Hybrid composites,widely used in aerospace,automotive,and s...This study investigates the uncertain dynamic characterization of hybrid composite plates by employing advanced machine-assisted finite element methodologies.Hybrid composites,widely used in aerospace,automotive,and structural applications,often face variability in material properties,geometric configurations,and manufacturing processes,leading to uncertainty in their dynamic response.To address this,three surrogate-based machine learning approaches like radial basis function(RBF),multivariate adaptive regression splines(MARS),and polynomial neural networks(PNN)are integrated with a finite element framework to efficiently capture the stochastic behavior of these plates.The research focuses on predicting the first three natural frequencies under material uncertainties,which are critical to ensuring structural reliability.Monte Carlo simulation(MCS)is used as a benchmark for generating probabilistic datasets,including mean values,standard deviations,and probability density functions.The surrogate models are then trained and validated against these datasets,enabling accurate representation of uncertainty with substantially fewer samples compared to conventionalMCS.Among the methods studied,the RBFmodel demonstrates superior performance,closely approximating MCS results with a reduced sample size,thereby achieving significant computational savings.The proposed framework not only reduces computational time and costs but also maintains high predictive accuracy,making it well-suited for complex engineering systems.Beyond free vibration analysis,the methodology can be extended to more sophisticated scenarios,such as forced vibration,damping effects,and nonlinear structural responses.Overall,this work presents a computationally efficient and robust approach for surrogate-based uncertainty quantification,advancing the analysis and design of hybrid composite structures under uncertainty.展开更多
Alkali-free SiO_(2)-Al_(2)O_(3)-CaO-MgO with different SiO_(2)/Al_(2)O_(3)mass ratios was prepared by conventional melt quenching method.The glass network structure,thermodynamic properties and elastic modulus changes...Alkali-free SiO_(2)-Al_(2)O_(3)-CaO-MgO with different SiO_(2)/Al_(2)O_(3)mass ratios was prepared by conventional melt quenching method.The glass network structure,thermodynamic properties and elastic modulus changes with SiO_(2)and Al_(2)O_(3)ratios were investigated using various techniques.It is found that when SiO_(2)is replaced by Al_(2)O_(3),the Q^(4) to Q^(3) transition of silicon-oxygen network decreases while the aluminum-oxygen network increases,which result in the transformation of Si-O-Si bonds to Si-O-Al bonds and an increase in glass network connectivity even though the intermolecular bond strength decreases.The glass transition temperature(T_(g))increases continuously,while the thermal expansion coefficient increases and high-temperature viscosity first decreases and then increases.Meanwhile,the elastic modulus values increase from 93 to 102 GPa.This indicates that the elastic modulus is mainly affected by packing factor and dissociation energy,and elements with higher packing factors and dissociation energies supplant those with lower values,resulting in increased rigidity within the glass.展开更多
As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operatio...As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operation.The free-standing cold-water pipe(CWP)in the system withstands various complex loads during operation,posing potential failure risks.To reveal the deformation and stress mechanisms of OTEC CWPs,this study first analyzes wave particle velocity and acceleration to determine wave loads at different water depths.Based on the Euler-Bernoulli beam model,a quasi-static load calculation model for OTEC CWPs was established.The governing equations were discretized using the finite difference method,and matrix equations were solved to analyze bending deformation,bending moments,and surface stresses at discrete points along the pipe.Results indicate that water depths within 50 m represent a critical zone where wave particle velocity,acceleration,and wave loads exhibit significant variations in harmonic patterns,while beyond 50 m depth wave loads decrease linearly.Ocean currents and surface wind-driven currents substantially influence the CWP’s lateral displacement.Considering the effect of clump weights,the maximum lateral displacement occurs at 600–800 m below sea level.Utilizing large-wall-thickness high-strength pipes at the top section significantly enhances the structural safety of the CWP system.展开更多
Since the launch of island-wide special customs operations at Hainan Free Trade Port(Hainan FTP),the proportion of “zero-tariff”imported goods has increased significantly from 21 to 74 percent, and high-quality good...Since the launch of island-wide special customs operations at Hainan Free Trade Port(Hainan FTP),the proportion of “zero-tariff”imported goods has increased significantly from 21 to 74 percent, and high-quality goods from Southeast Asia can enter Hainan at a more competitive price. If goods contain imported materials and achieve at least 30 percent added value through local processing,they can enter the Chinese mainland market with an exemption from import tariffs, effectively gaining market access across China.展开更多
The world economy is now in a period of indepth adjustment.The intensification of geopolitical conflicts,a rise of trade protectionism,and reconfiguration of global supply chains have prompted all countries to re-exam...The world economy is now in a period of indepth adjustment.The intensification of geopolitical conflicts,a rise of trade protectionism,and reconfiguration of global supply chains have prompted all countries to re-examine their openness to trade amid rising uncertainties.Against this backdrop,China’s continuing commitment to promoting higherlevel opening up and building the Hainan Free Trade Port(Hainan FTP)has distinct contemporary significance and strategic value.展开更多
The dedicated freight channel at the Youyiguan Border Gate in south China’s Guangxi Zhuang Autonomous Region buzzes with activity as trucks loaded with export goods move steadily through customs.Thanks to a system up...The dedicated freight channel at the Youyiguan Border Gate in south China’s Guangxi Zhuang Autonomous Region buzzes with activity as trucks loaded with export goods move steadily through customs.Thanks to a system upgraded at the start of 2026,clearance personnel at this China-Vietnam crossing simply place an order online,and the entire process is handled almost instantly via an intelligent platform.Adding to the efficiency,the border gate also features dedicated lanes that support driverless container trucks.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
Let G be a group.The family of all sets which are closed in every Hausdorf group topology of G form the family of closed sets of a T_(1) topology M_(G) on G called the Markov topology.Similarly,the family of all algeb...Let G be a group.The family of all sets which are closed in every Hausdorf group topology of G form the family of closed sets of a T_(1) topology M_(G) on G called the Markov topology.Similarly,the family of all algebraic subsets of G forms a family of closed sets for another T_(1)topology Z_(G) on G called the Zarski topology.A subgroup H of G is said to be Markov(resp.Zarski)embedded if the equality M_(G|H)=M_(H)(resp.Z_(G|H)=Z_(H))holds.I's proved that an abirary subgroup of a free group is both Zariski and Markov embedded in it.展开更多
Labor provisions have become a fundamental trade rule in regional and bilateral trade agreements.Although China’s legislation on pilot Free Trade Zones includes content related to labor protection,it primarily aligns...Labor provisions have become a fundamental trade rule in regional and bilateral trade agreements.Although China’s legislation on pilot Free Trade Zones includes content related to labor protection,it primarily aligns with labor indicators in“Doing Business”,the assessment of business situations issued by the World Bank.It differs from the labor rights protection focus emphasized in trade agreements.The latest strategic documents issued by the State Council of China have addressed this issue to fully achieve the goal of aligning Free Trade Zones with high-standard trade agreements.Building on the development of Free Trade Zone legislation and domestic labor law governance,China should proactively explore a tailored approach to labor provisions in Free Trade Agreements.In this approach,it should explicitly define the“baseline”and“ceiling”for labor provisions during negotiations and,within this framework,establish benchmarks for labor rights protection,enforcement mechanisms,and cross-border regulatory mechanisms suited to the specific conditions of the agreement parties.展开更多
The dynamic behavior of high-speed craft navigating through variable sea states plays a pivotal role in ensuring maritime safety.However,many existing simulation approaches rely on linear or overly simplified represen...The dynamic behavior of high-speed craft navigating through variable sea states plays a pivotal role in ensuring maritime safety.However,many existing simulation approaches rely on linear or overly simplified representations of the marine environment,thereby limiting the fidelity of motion predictions.This study explores the motion characteristics of a 4.5-t high-speed vessel by conducting fully coupled numerical simulations using the STAR-CCM+software.The analysis considers both calm and varying sea conditions,incorporating fluctuations in wave height,wavelength,and wind speed to reflect more realistic operating scenarios.Simulation results reveal that the vessel’s hydrodynamic response is highly sensitive to changes in sea state.As conditions deteriorate,the free surface becomes increasingly complex,with higher wave amplitudes and more pronounced interactions between the waves generated by the vessel and those imposed by the external environment.These effects lead to significant increases in roll,pitch,heave,and sway motions,thereby imposing greater demands on the vessel’s dynamic stability and operational safety.Furthermore,both hydrodynamic resistance and propulsive thrust exhibit notable dependence on sea state and vessel speed.Total resistance generally increases with rougher sea conditions,while thrust tends to rise with increasing forward speed.Under calm or mildly disturbed waters,a Froude number(Fr)of 0.5 appears to offer an optimal balance for initiating and controlling primary motions such as roll,pitch,heave,and sway.Conversely,in more challenging conditions-such as those represented by a Sea State 3-effective motion control is better achieved at a higher Froude number of approximately 1.0.展开更多
In order to better describe the phenomenon of biological invasion,this paper introduces a free boundary model of biological invasion.Firstly,the right free boundary is added to the equation with logistic terms.Secondl...In order to better describe the phenomenon of biological invasion,this paper introduces a free boundary model of biological invasion.Firstly,the right free boundary is added to the equation with logistic terms.Secondly,the existence and uniqueness of local solutions are proved by the Sobolev embedding theorem and the comparison principle.Finally,according to the relevant research data and contents of red fire ants,the diffusion area and nest number of red fire ants were simulated without external disturbance.This paper mainly simulates the early diffusion process of red fire ants.In the early diffusion stage,red fire ants grow slowly and then spread over a large area after reaching a certain number.展开更多
Comprehensive utilization of phosphogypsum(PG)has attracted much attention,especially for the recovery of rare earth elements(REEs)and gypsum due to the issues of stockpile,environmental pollution,and waste of associa...Comprehensive utilization of phosphogypsum(PG)has attracted much attention,especially for the recovery of rare earth elements(REEs)and gypsum due to the issues of stockpile,environmental pollution,and waste of associated resources.Traditional utilization methods suffered the issues of low REEs leaching efficiency,huge amount of CaSO_(4)saturated wastewater and high recovery cost.To solve these issues,this study investigated the occurrence of REEs in PG and the leaching of REEs.The results show that REEs in PG are in the forms of(1)REEs mineral inclusions,(2)REEs isomorphous substitution of Ca^(2+)in gypsum lattice,(3)dispersed soluble REEs salts.Acid leaching results demonstrate that(1)the dissolution of gypsum matrix is the control factor of REEs leaching;(2)H_(2)SO_(4)is a promising leachant considering the recycle of leachate;(3)the gypsum matrix suffers a recrystallization during the acid leaching and releases the soluble REEs from PG to aqueous solution.For the recovery of the undissolved REEs mineral inclusions,wet sieving concentrated 37.1 wt%of the REEs in a 10.7 wt%mass,increasing REEs content from 309 to 1071 ppm.Finally,a green process combining gravity separation and hydrometallurgy is proposed.This process owns the merits of wastewater free,considerable REEs recovery(about 10%increase compared with traditional processes),excellent gypsum purification(>95 wt%CaSO_(4)·2H_(2)O,with<0.06 wt%of soluble P_(2)O_(5) and<0.015 wt%of soluble F)and reagent saving(about 2/3less reagent consumption than non-cyclical leaching).展开更多
The Makran Accretionary Prism is one of the largest accretionary prisms in the world and hosts substantial natural gas hydrate resources.However,research on the distribution characteristics and accumulation mechanisms...The Makran Accretionary Prism is one of the largest accretionary prisms in the world and hosts substantial natural gas hydrate resources.However,research on the distribution characteristics and accumulation mechanisms of free gas remains limited.This study identifies structural elements associated with free gas,such as thrust faults,piggyback basins,unconformities,and décollements,through detailed interpretation of newly acquired seismic data.Free gas reservoirs within piggyback basins are located in the folded zone of the accretionary prism,whereas unconformity-type and horizontal sandstone-type free gas reservoirs are identified in undeformed areas.In the folded zone,décollement,thrust faults,and permeable sand layers act as primary migration pathways for free gas,which accumulates in turbidite sands beneath bottom simulating reflectors(BSRs)in piggyback basins.In the undeformed zone,free gas migrates along décollements and thrust faults into horizontal sandstones,where substantial accumulations are found near unconformities below BSRs.The distribution of free gas reservoirs across the study area is extensive and diverse.This study is the first to document unconformity-type and horizontal sandstone-type free gas reservoirs in the undeformed zone,highlighting their considerable resource potential.The findings are of substantial value for oil and gas exploration at the front of the accretionary prism and provide important theoretical and practical insights into natural gas accumulation systems along active continental margins.展开更多
Owing to their low toxicity and remarkable stability, perovskites based on antimony and bismuth have garnered significant interest in recent years. However, A_(3)B_(2)X_(9) perovskite materials derived from antimony a...Owing to their low toxicity and remarkable stability, perovskites based on antimony and bismuth have garnered significant interest in recent years. However, A_(3)B_(2)X_(9) perovskite materials derived from antimony and bismuth face several challenges, including excessively wide band gaps, elevated defect densities, and suboptimal film quality, all of which hinder advancements in device efficiency. While extensive studies have been undertaken to investigate the effects of modulating the A-site and X-site elements in lead-free A_(3)B_(2)X_(9) perovskites, there remains a notable scarcity of reports addressing the impact of modifications to the B-site element. In this study, we investigated the alloying of antimony and bismuth within the 2D Cs_(3)B_(2)I_(6)Br_(3) perovskite. By systematically varying the ratios of two elements, we found that the incorporation of both antimony and bismuth at the B-site significantly enhances the quality of the perovskite films. Our findings indicate that a 1 : 1 ratio of antimony to bismuth produces the densest films, the highest photoluminescence intensity, and superior photovoltaic performance. Ultimately,the devices fabricated using this optimal ratio achieved an open-circuit voltage(VOC) of 1.01 V and a power conversion efficiency(PCE) of 0.645%.展开更多
Too much screen time is bad for your brain and body.It can also waste your time.So,try to spend less time on scree ns.Changing habits is not easy,but you can do it.Use an app to track your time on your smartphone.Do y...Too much screen time is bad for your brain and body.It can also waste your time.So,try to spend less time on scree ns.Changing habits is not easy,but you can do it.Use an app to track your time on your smartphone.Do you waste a lot of time on some ofyour phone apps?Take them off or set time limits for them.Less screen time means more free time for other things.Go hiking,visit a museum or try a new hobby.Use your phone less and appreciate life more.展开更多
Silicon,a leading candidate for electrode material for lithium-ion batteries,has garnered significant attention.During the initial lithiation process,the alloying reaction between silicon and lithium transforms the pr...Silicon,a leading candidate for electrode material for lithium-ion batteries,has garnered significant attention.During the initial lithiation process,the alloying reaction between silicon and lithium transforms the pristine silicon microstructure from crystalline to amorphous,resulting in plastic deformation of the amorphous phase.This study proposes the free volume theory to develop a fully coupled Cahn-Hilliard phase-field model that integrates viscoplastic deformation,free volume evolution,and diffusion.This model investigates the chemophysical phenomenon of self-limiting behavior occurring during the initial lithiation of silicon anodes.Unlike most existing models,the proposed model considers free volume-dependent diffusion using a physically-based approach.The model’s temporal variation in the lithiated phase thickness aligns well with experimental results,confirming the model’s accuracy.Stress field calculations reveal the coexistence of compressive and tensile stresses within the lithiated phase,which may not cause the limiting effect under the frame of the stress-induced diffusion.Analyses indicate that high effective stress increases free volume,enhancing lithium diffusion and augmenting the diffusion coefficient.Reducing the diffusion coefficient in the lithiated phase due to free volume evolution is the primary cause of self-limiting lithiation.展开更多
Against the backdrop of digital education,the campus network has become an indispensable infrastructure in universities,yet the limitations of traditional operation models have become increasingly prominent.This paper...Against the backdrop of digital education,the campus network has become an indispensable infrastructure in universities,yet the limitations of traditional operation models have become increasingly prominent.This paper systematically presents the entire process of the free campus network reform initiated by Dalian Jiaotong University,focusing on its background,implementation paths,existing challenges,and optimization strategies.It explores the construction of an on-demand service system for campus networks,and practical experience can provide some reference and guidance for sister universities.展开更多
基金the National Natural Science Foundation of China(Grant Nos.52405342 and 52175335)the National Key Research and Development Program of China(Grant No.2022YFB3404201)+2 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.N2302014 and N25ZJL003)the Natural Science Foundation Joint Foundation of Liaoning province(Grant No.2023-BSBA-108)the help provided by China FAW Foundry Co.,Ltd.
文摘The advancement of integrated die-casting technology calls for high-strength,high-ductility heat-treatment-free Al alloys.This study investigates the use of a new AlSiFeMnVTiSrZr heat-treatment-free die-casting alloy for shock tower manufacturing.Results show the alloy has excellent overall mechanical properties,but significant regional differences in microstructure and performance are found in the shock tower casting:Far-gate Position 6 has almost no externally solidified crystals(ESCs),whereas dense coarse dendritic ESCs exist in the center of near-gate Position 5.The fracture surface of Position 6 shows a steeper slope,while Position 5 has a rough crack propagation platform.Far-gate Position 6 also has higher porosity(nearly triple that of near-gate Region 5)and larger average pore size.Analysis reveals microstructural heterogeneity between near-and far-gate regions strongly influences mechanical performance.Notably,coarse dendritic ESCs in the near-gate region restrict grain boundary strengthening,leading to lower yield strength despite low porosity.Conversely,while fine grains in the far-gate region could enhance grain boundary strengthening,abundant porosity acts as crack initiation sites,severely reducing ductility.These findings provide theoretical guidance for evaluating integrated die-cast component performance.
文摘This study investigates the uncertain dynamic characterization of hybrid composite plates by employing advanced machine-assisted finite element methodologies.Hybrid composites,widely used in aerospace,automotive,and structural applications,often face variability in material properties,geometric configurations,and manufacturing processes,leading to uncertainty in their dynamic response.To address this,three surrogate-based machine learning approaches like radial basis function(RBF),multivariate adaptive regression splines(MARS),and polynomial neural networks(PNN)are integrated with a finite element framework to efficiently capture the stochastic behavior of these plates.The research focuses on predicting the first three natural frequencies under material uncertainties,which are critical to ensuring structural reliability.Monte Carlo simulation(MCS)is used as a benchmark for generating probabilistic datasets,including mean values,standard deviations,and probability density functions.The surrogate models are then trained and validated against these datasets,enabling accurate representation of uncertainty with substantially fewer samples compared to conventionalMCS.Among the methods studied,the RBFmodel demonstrates superior performance,closely approximating MCS results with a reduced sample size,thereby achieving significant computational savings.The proposed framework not only reduces computational time and costs but also maintains high predictive accuracy,making it well-suited for complex engineering systems.Beyond free vibration analysis,the methodology can be extended to more sophisticated scenarios,such as forced vibration,damping effects,and nonlinear structural responses.Overall,this work presents a computationally efficient and robust approach for surrogate-based uncertainty quantification,advancing the analysis and design of hybrid composite structures under uncertainty.
基金Supported by the National Key Research Program(No.2024-1129-954-112)National Natural Science Foundation of China(No.52372033)Guangxi Science and Technology Major Program(No.AA24263054)。
文摘Alkali-free SiO_(2)-Al_(2)O_(3)-CaO-MgO with different SiO_(2)/Al_(2)O_(3)mass ratios was prepared by conventional melt quenching method.The glass network structure,thermodynamic properties and elastic modulus changes with SiO_(2)and Al_(2)O_(3)ratios were investigated using various techniques.It is found that when SiO_(2)is replaced by Al_(2)O_(3),the Q^(4) to Q^(3) transition of silicon-oxygen network decreases while the aluminum-oxygen network increases,which result in the transformation of Si-O-Si bonds to Si-O-Al bonds and an increase in glass network connectivity even though the intermolecular bond strength decreases.The glass transition temperature(T_(g))increases continuously,while the thermal expansion coefficient increases and high-temperature viscosity first decreases and then increases.Meanwhile,the elastic modulus values increase from 93 to 102 GPa.This indicates that the elastic modulus is mainly affected by packing factor and dissociation energy,and elements with higher packing factors and dissociation energies supplant those with lower values,resulting in increased rigidity within the glass.
基金funded by Nansha District Science and Technology Project(Grant Number.2024ZD008)funded by China Geological Survey(Grant number:No.DD20230066,DD20242659).
文摘As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operation.The free-standing cold-water pipe(CWP)in the system withstands various complex loads during operation,posing potential failure risks.To reveal the deformation and stress mechanisms of OTEC CWPs,this study first analyzes wave particle velocity and acceleration to determine wave loads at different water depths.Based on the Euler-Bernoulli beam model,a quasi-static load calculation model for OTEC CWPs was established.The governing equations were discretized using the finite difference method,and matrix equations were solved to analyze bending deformation,bending moments,and surface stresses at discrete points along the pipe.Results indicate that water depths within 50 m represent a critical zone where wave particle velocity,acceleration,and wave loads exhibit significant variations in harmonic patterns,while beyond 50 m depth wave loads decrease linearly.Ocean currents and surface wind-driven currents substantially influence the CWP’s lateral displacement.Considering the effect of clump weights,the maximum lateral displacement occurs at 600–800 m below sea level.Utilizing large-wall-thickness high-strength pipes at the top section significantly enhances the structural safety of the CWP system.
文摘Since the launch of island-wide special customs operations at Hainan Free Trade Port(Hainan FTP),the proportion of “zero-tariff”imported goods has increased significantly from 21 to 74 percent, and high-quality goods from Southeast Asia can enter Hainan at a more competitive price. If goods contain imported materials and achieve at least 30 percent added value through local processing,they can enter the Chinese mainland market with an exemption from import tariffs, effectively gaining market access across China.
文摘The world economy is now in a period of indepth adjustment.The intensification of geopolitical conflicts,a rise of trade protectionism,and reconfiguration of global supply chains have prompted all countries to re-examine their openness to trade amid rising uncertainties.Against this backdrop,China’s continuing commitment to promoting higherlevel opening up and building the Hainan Free Trade Port(Hainan FTP)has distinct contemporary significance and strategic value.
文摘The dedicated freight channel at the Youyiguan Border Gate in south China’s Guangxi Zhuang Autonomous Region buzzes with activity as trucks loaded with export goods move steadily through customs.Thanks to a system upgraded at the start of 2026,clearance personnel at this China-Vietnam crossing simply place an order online,and the entire process is handled almost instantly via an intelligent platform.Adding to the efficiency,the border gate also features dedicated lanes that support driverless container trucks.
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 the Grant-in-Aid for Scientific Research(C)by the Japan Society for the Promotion of Science(20K03615)。
文摘Let G be a group.The family of all sets which are closed in every Hausdorf group topology of G form the family of closed sets of a T_(1) topology M_(G) on G called the Markov topology.Similarly,the family of all algebraic subsets of G forms a family of closed sets for another T_(1)topology Z_(G) on G called the Zarski topology.A subgroup H of G is said to be Markov(resp.Zarski)embedded if the equality M_(G|H)=M_(H)(resp.Z_(G|H)=Z_(H))holds.I's proved that an abirary subgroup of a free group is both Zariski and Markov embedded in it.
基金result of the“Research on ESG Supply Chain Governance and Labor Rights Protection”(Project Number SUFE-ESG-20250315)a general subject project of the Fullgoal Institute for ESG Research,SUFE in 2025.
文摘Labor provisions have become a fundamental trade rule in regional and bilateral trade agreements.Although China’s legislation on pilot Free Trade Zones includes content related to labor protection,it primarily aligns with labor indicators in“Doing Business”,the assessment of business situations issued by the World Bank.It differs from the labor rights protection focus emphasized in trade agreements.The latest strategic documents issued by the State Council of China have addressed this issue to fully achieve the goal of aligning Free Trade Zones with high-standard trade agreements.Building on the development of Free Trade Zone legislation and domestic labor law governance,China should proactively explore a tailored approach to labor provisions in Free Trade Agreements.In this approach,it should explicitly define the“baseline”and“ceiling”for labor provisions during negotiations and,within this framework,establish benchmarks for labor rights protection,enforcement mechanisms,and cross-border regulatory mechanisms suited to the specific conditions of the agreement parties.
基金funded by the National College Students Innovation and Entrepreneurship Training Program(202411646031)the Zhejiang Xinmiao Talents Program(2024R405A052)the SRIP Research Program of Ningbo University(2025SRIP1707).
文摘The dynamic behavior of high-speed craft navigating through variable sea states plays a pivotal role in ensuring maritime safety.However,many existing simulation approaches rely on linear or overly simplified representations of the marine environment,thereby limiting the fidelity of motion predictions.This study explores the motion characteristics of a 4.5-t high-speed vessel by conducting fully coupled numerical simulations using the STAR-CCM+software.The analysis considers both calm and varying sea conditions,incorporating fluctuations in wave height,wavelength,and wind speed to reflect more realistic operating scenarios.Simulation results reveal that the vessel’s hydrodynamic response is highly sensitive to changes in sea state.As conditions deteriorate,the free surface becomes increasingly complex,with higher wave amplitudes and more pronounced interactions between the waves generated by the vessel and those imposed by the external environment.These effects lead to significant increases in roll,pitch,heave,and sway motions,thereby imposing greater demands on the vessel’s dynamic stability and operational safety.Furthermore,both hydrodynamic resistance and propulsive thrust exhibit notable dependence on sea state and vessel speed.Total resistance generally increases with rougher sea conditions,while thrust tends to rise with increasing forward speed.Under calm or mildly disturbed waters,a Froude number(Fr)of 0.5 appears to offer an optimal balance for initiating and controlling primary motions such as roll,pitch,heave,and sway.Conversely,in more challenging conditions-such as those represented by a Sea State 3-effective motion control is better achieved at a higher Froude number of approximately 1.0.
基金Supported by National Natural Science Foundation of China(12101482)Postdoctoral Science Foundation of China(2022M722604)+2 种基金General Project of Science and Technology of Shaanxi Province(2023-YBSF-372)The Natural Science Foundation of Shaan Xi Province(2023-JCQN-0016)Shannxi Mathmatical Basic Science Research Project(23JSQ042)。
文摘In order to better describe the phenomenon of biological invasion,this paper introduces a free boundary model of biological invasion.Firstly,the right free boundary is added to the equation with logistic terms.Secondly,the existence and uniqueness of local solutions are proved by the Sobolev embedding theorem and the comparison principle.Finally,according to the relevant research data and contents of red fire ants,the diffusion area and nest number of red fire ants were simulated without external disturbance.This paper mainly simulates the early diffusion process of red fire ants.In the early diffusion stage,red fire ants grow slowly and then spread over a large area after reaching a certain number.
基金Project supported by the National Natural Science Foundation of China(52104354)the National Natural Science Foundation of China(51674036)+1 种基金Joint Fund for Nuclear Technology Innovation Sponsored by the National Natural Science Foundation of Chinathe China National Nuclear Corporation(U2067201)。
文摘Comprehensive utilization of phosphogypsum(PG)has attracted much attention,especially for the recovery of rare earth elements(REEs)and gypsum due to the issues of stockpile,environmental pollution,and waste of associated resources.Traditional utilization methods suffered the issues of low REEs leaching efficiency,huge amount of CaSO_(4)saturated wastewater and high recovery cost.To solve these issues,this study investigated the occurrence of REEs in PG and the leaching of REEs.The results show that REEs in PG are in the forms of(1)REEs mineral inclusions,(2)REEs isomorphous substitution of Ca^(2+)in gypsum lattice,(3)dispersed soluble REEs salts.Acid leaching results demonstrate that(1)the dissolution of gypsum matrix is the control factor of REEs leaching;(2)H_(2)SO_(4)is a promising leachant considering the recycle of leachate;(3)the gypsum matrix suffers a recrystallization during the acid leaching and releases the soluble REEs from PG to aqueous solution.For the recovery of the undissolved REEs mineral inclusions,wet sieving concentrated 37.1 wt%of the REEs in a 10.7 wt%mass,increasing REEs content from 309 to 1071 ppm.Finally,a green process combining gravity separation and hydrometallurgy is proposed.This process owns the merits of wastewater free,considerable REEs recovery(about 10%increase compared with traditional processes),excellent gypsum purification(>95 wt%CaSO_(4)·2H_(2)O,with<0.06 wt%of soluble P_(2)O_(5) and<0.015 wt%of soluble F)and reagent saving(about 2/3less reagent consumption than non-cyclical leaching).
基金the National Natural Science Foundation of China(Nos.42076069,41406080)the Laoshan Laboratory Science and Technology Innovation Project(No.LSKJ202203401)the China Geological Survey Project(Nos.DD20190581,DD20160155)。
文摘The Makran Accretionary Prism is one of the largest accretionary prisms in the world and hosts substantial natural gas hydrate resources.However,research on the distribution characteristics and accumulation mechanisms of free gas remains limited.This study identifies structural elements associated with free gas,such as thrust faults,piggyback basins,unconformities,and décollements,through detailed interpretation of newly acquired seismic data.Free gas reservoirs within piggyback basins are located in the folded zone of the accretionary prism,whereas unconformity-type and horizontal sandstone-type free gas reservoirs are identified in undeformed areas.In the folded zone,décollement,thrust faults,and permeable sand layers act as primary migration pathways for free gas,which accumulates in turbidite sands beneath bottom simulating reflectors(BSRs)in piggyback basins.In the undeformed zone,free gas migrates along décollements and thrust faults into horizontal sandstones,where substantial accumulations are found near unconformities below BSRs.The distribution of free gas reservoirs across the study area is extensive and diverse.This study is the first to document unconformity-type and horizontal sandstone-type free gas reservoirs in the undeformed zone,highlighting their considerable resource potential.The findings are of substantial value for oil and gas exploration at the front of the accretionary prism and provide important theoretical and practical insights into natural gas accumulation systems along active continental margins.
基金financially supported by the Natural Science Foundation of Zhejiang Province, China (Grant No. LQ22F040001)China Postdoctoral Science Foundation (Grant No. 2022M723281)Science and Technology Planning Project of Shaoxing City (Grant No. 2023B41006)。
文摘Owing to their low toxicity and remarkable stability, perovskites based on antimony and bismuth have garnered significant interest in recent years. However, A_(3)B_(2)X_(9) perovskite materials derived from antimony and bismuth face several challenges, including excessively wide band gaps, elevated defect densities, and suboptimal film quality, all of which hinder advancements in device efficiency. While extensive studies have been undertaken to investigate the effects of modulating the A-site and X-site elements in lead-free A_(3)B_(2)X_(9) perovskites, there remains a notable scarcity of reports addressing the impact of modifications to the B-site element. In this study, we investigated the alloying of antimony and bismuth within the 2D Cs_(3)B_(2)I_(6)Br_(3) perovskite. By systematically varying the ratios of two elements, we found that the incorporation of both antimony and bismuth at the B-site significantly enhances the quality of the perovskite films. Our findings indicate that a 1 : 1 ratio of antimony to bismuth produces the densest films, the highest photoluminescence intensity, and superior photovoltaic performance. Ultimately,the devices fabricated using this optimal ratio achieved an open-circuit voltage(VOC) of 1.01 V and a power conversion efficiency(PCE) of 0.645%.
文摘Too much screen time is bad for your brain and body.It can also waste your time.So,try to spend less time on scree ns.Changing habits is not easy,but you can do it.Use an app to track your time on your smartphone.Do you waste a lot of time on some ofyour phone apps?Take them off or set time limits for them.Less screen time means more free time for other things.Go hiking,visit a museum or try a new hobby.Use your phone less and appreciate life more.
基金the National Natural Science Foundation of China under grant No.12372173the Natural Science Foundation of Shanghai under grant No.23ZR1468600.
文摘Silicon,a leading candidate for electrode material for lithium-ion batteries,has garnered significant attention.During the initial lithiation process,the alloying reaction between silicon and lithium transforms the pristine silicon microstructure from crystalline to amorphous,resulting in plastic deformation of the amorphous phase.This study proposes the free volume theory to develop a fully coupled Cahn-Hilliard phase-field model that integrates viscoplastic deformation,free volume evolution,and diffusion.This model investigates the chemophysical phenomenon of self-limiting behavior occurring during the initial lithiation of silicon anodes.Unlike most existing models,the proposed model considers free volume-dependent diffusion using a physically-based approach.The model’s temporal variation in the lithiated phase thickness aligns well with experimental results,confirming the model’s accuracy.Stress field calculations reveal the coexistence of compressive and tensile stresses within the lithiated phase,which may not cause the limiting effect under the frame of the stress-induced diffusion.Analyses indicate that high effective stress increases free volume,enhancing lithium diffusion and augmenting the diffusion coefficient.Reducing the diffusion coefficient in the lithiated phase due to free volume evolution is the primary cause of self-limiting lithiation.
文摘Against the backdrop of digital education,the campus network has become an indispensable infrastructure in universities,yet the limitations of traditional operation models have become increasingly prominent.This paper systematically presents the entire process of the free campus network reform initiated by Dalian Jiaotong University,focusing on its background,implementation paths,existing challenges,and optimization strategies.It explores the construction of an on-demand service system for campus networks,and practical experience can provide some reference and guidance for sister universities.
