The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerge...The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerged entry nozzles,form floaters in the molds,and produce various surface defects on the cast slabs.This review summarizes the effects of nonmetallic inclusions on traditional CaO-SiO_(2)-based(CS)mold fluxes and novel CaO-Al_(2)O_(3)-based(CA)low-or non-reactive fluxes containing TiO_(2),BaO,and B_(2)O_(3)additives to avoid undesirable steel,slag,and inclusion reactions,with the aim of providing a new perspective for research and practice related to balancing the lubrication and heat transfer of mold fluxes to promote smooth operation and reduce surface defects on cast slabs.For traditional CS mold flux,although the addition of solvents such as Na_(2)O,Li_(2)O,and B_(2)O_(3)can enhance flowability,steel-slag reactions persist,limiting the effectiveness of CS mold fluxes in high-Ti steel casting.Low-or non-reactive CA mold fluxes with reduced SiO_(2)content are a research focus,where adding other components can significantly change flux characteristics.Replacing CaO with BaO can lower the melting point and inhibit crystallization,allowing the flux to maintain good flowability at low temperatures.Replacing SiO_(2)with TiO_(2)can stabilize the viscosity and enhance heat transfer.To reduce the environmental impact,fluorides are replaced with components such as TiO_(2),B_(2)O_(3),BaO,Li_(2)O,and Na_(2)O for F-frce mold fluxes with similar lubrication,crystallization,and heat-transfer effects.When TiO_(2)replaces CaF_(2),it stabilizes the viscosity and enhances the heat conductivity,forming CaTiO_(3)and CaSiTiO_(5)phases instead of cuspidine to control crystallization.B_(2)O_(3)lowers the melting point and suppresses crystallization,forming phases such as Ca_(3)B_(2)O_(6)and Ca_(11)Si_(4)B_(2)O_(22).BaO introduces non-bridging oxygen to reduce viscosity and ensure flux flowability at low temperatures.However,further studies are required to determine the optimal mold flux compositions corresponding to the steel grades and the interactions between the various components of the mold flux.In the future,the practical application of new mold fluxes for high-Ti steel will become the focus of further verification to achieve a balance between lubrication and heat transfer,which is expected to minimize the occurrence of casting problems and slab defects.展开更多
From an engineering feasibility standpoint, what level of performance metrics can be ultimately achieved when designing a reactor using well-established nuclear fuels and structural materials that have already undergo...From an engineering feasibility standpoint, what level of performance metrics can be ultimately achieved when designing a reactor using well-established nuclear fuels and structural materials that have already undergone irradiation testing? The irradiation capability, which hinges on parameters like neutron flux level, irradiation channels' volume, and fuel cycle duration, is a core indicator for high-flux reactors. We propose a conceptual design of an ultra-high flux fast reactor(UFFR) with strong irradiation capability, which utilizes U-20Pu-10Zr alloy fuel and employs lead-bismuth as the coolant. The maximum neutron flux in the core reaches 1.32×10^(16) cm^(-2)s^(-1), while the average neutron flux in the irradiation channels attains 1.19×10^(16) cm^(-2)s^(-1). The volume of the central irradiation channel exceeds 10000 cm^(3), and the fuel cycle duration is 165 d, placing all its performance indicators among the top in the world. Based on the analyses of reactor physics and thermalhydraulics, it has been demonstrated that all reactivity coefficients are negative and all physical parameters meet the design criteria, ensuring the inherent safety of UFFR. An assessment of the irradiation capability has been carried out based on californium-252(^(252)Cf) production, indicating that the irradiation capability of UFFR surpasses that of the high flux isotope reactor(HFIR). The yield of ^(252)Cf from UFFR is 14.39 times that of HFIR, and its nuclei conversion rate is 3.21 times that of HFIR.展开更多
Frequent droughts pose considerable threat to global forest carbon uptake,but little is known about the response of forest carbon fluxes in climatic transition zones to seasonal drought.In this study,the responses of ...Frequent droughts pose considerable threat to global forest carbon uptake,but little is known about the response of forest carbon fluxes in climatic transition zones to seasonal drought.In this study,the responses of carbon fluxes to seasonal drought in two natural forests(Quercus aliena var.acute serrata Maxim and Pinus tabuliformis Carr.)in the Baotianman Nature Reserve were investigated.The Q.aliena forest exhibited a high resilience with stable gross primary productivity(GPP).However,ecosystem respiration(Re)significantly declined by 18.4%compared with normal years,leading to an increase in net carbon sequestration capacity of 4.1%.This resilience was attributed to its deep root system accessing soil water(SWC_(50cm))to sustain stomatal openness,coupled with the efficient utilization of photosynthetically active radiation to drive photosynthesis.In contrast,the P.tabuliformis forest,which relied on shallow soil moisture(SWC_(20cm)),experienced simultaneous decreases in both GPP and Re during drought,with a sharply greater decrease in GPP,resulting in low net carbon sink capacity.Further analysis revealed that the Q.aliena forest prioritized carbon assimilation through a deep water-stomatal synergy strategy(anisohydric behavior),whereas the P.tabuliformis forest adopted an isohydric strategy favoring water conservation at the expense of carbon fixation efficiency.These findings highlight distinct mechanisms underlying drought adaptation between forest types,providing critical insight into optimizing forest carbon cycle models and selecting drought-resistant species under the influence of climate change.展开更多
An atmospheric general circulation model(AGCM)is used to analyze the different impact on the Barents Sea(BS)and Greenland Sea(GS)for a perturbation of sea-to-air DMS flux.We compare contemporary anthropogenic S and co...An atmospheric general circulation model(AGCM)is used to analyze the different impact on the Barents Sea(BS)and Greenland Sea(GS)for a perturbation of sea-to-air DMS flux.We compare contemporary anthropogenic S and contemporary DMS sea-to-air flux(as baseline,B00)sulfur emissions,with contemporary anthropogenic S and a perturbed DMS flux(as modified,B01)sulfur emissions.Results show that the global mean surface DMS and DMS vertically integrated concentration all peaked in June and increases more than 63%in BS and increases about 58%in GS.The concentrations of atmospheric sulfur dioxide vertical integral(SO_(2))and sulfate vertical integral(SO_(4))only increase less than 12%in both regions.Sulfur emission(SEM)peaked in June and increased about 67%and 41%in GS and BS,respectively.Aerosol optical depth(AOD)increases less than 4%in GS and in BS.Surface temperature(TSC)peaked in July and reduces 0.25 K and 0.8 K in GS and BS,respectively.Satellite data from 2003 to 2023show that chlorophyll(CHL)concentration in BS exceeds that of GS by 51%.The AOD in GS is only 0.6%higher than in BS.The recent increased rate of DMS surface concentration in BS(from 6%during 1981–2002 to 18.8%in 2003–2023)is mainly caused by elevated CHL concentrations in BS.Finally,the perturbation on DMS flux leads to increase rate of DMS and related sulfur emissions especially in the BS,this tendency will have an offsetting effect on regional warming.展开更多
Correction to:Journal of Forestry Research(2025)36:124 https://doi.org/10.1007/s11676-025-01918-8 In this article the author’s name Yasutomo Hoshika was incorrectly written as Yasutoma Hoshika.The original article ha...Correction to:Journal of Forestry Research(2025)36:124 https://doi.org/10.1007/s11676-025-01918-8 In this article the author’s name Yasutomo Hoshika was incorrectly written as Yasutoma Hoshika.The original article has been corrected.展开更多
Accurate quantification of carbon and water fluxes dynamics in arid and semi-arid ecosystems is a critical scientific challenge for regional carbon neutrality assessments and sustainable water resource management.In t...Accurate quantification of carbon and water fluxes dynamics in arid and semi-arid ecosystems is a critical scientific challenge for regional carbon neutrality assessments and sustainable water resource management.In this study,we developed a multi-flux global sensitivity discriminant index(D_(sen))by integrating the Biome-BGCMuSo model with eddy covariance flux observations.This index was combined with a Bayesian optimization algorithm to conduct parameter optimization.The results demonstrated that:(1)Sensitivity analysis identified 13 highly sensitive parameters affecting carbon and water fluxes.Among these,the canopy light extinction coefficient(k)and the fraction of leaf N in Rubisco(FLNR)exhibited significantly higher sensitivity to carbon fluxes(GPP,NEE,Reco;D_(sen)>10%)compared to water flux(ET).This highlights the strong dependence of carbon cycle simulations on vegetation physiological parameters.(2)The Bayesian optimization framework efficiently converged 30 parameter spaces within 50 iterations,markedly improving carbon fluxes simulation accuracy.The Kling-Gupta efficiency(KGE)values for Gross Primary Production(GPP),Net Ecosystem Exchange(NEE),and Total Respiration(Reco)increased by 44.94%,69.23%and 123%,respectively.The optimization prioritized highly sensitive parameters,underscoring the necessity of parameter sensitivity stratification.(3)The optimized model effectively reproduced carbon sink characteristics in mountain meadows during the growing season(cumulative NEE=-375 g C/m^(2)).It revealed synergistic carbon-water fluxes interactions governed by coupled photosynthesis-stomatal pathways and identified substrate supply limitations on heterotrophic respiration.This study proposes a novel multi-flux sensitivity index and an efficient optimization framework,elucidating the coupling mechanisms between vegetation physiological regulation(k,FLNR)and environmental stressors(VPD,SWD)in carbonwater cycles.The methodology offers a practical approach for arid ecosystem model optimization and provides theoretical insights for grassland management through canopy structure regulation and water-use efficiency enhancement.展开更多
The efficiency of energy conversion from mechanical to electrical in AC generators is not entirely optimal,as power losses are converted into heat.Accurate thermal modeling and temperature measurement of advanced elec...The efficiency of energy conversion from mechanical to electrical in AC generators is not entirely optimal,as power losses are converted into heat.Accurate thermal modeling and temperature measurement of advanced electric machines with complex structures are mandatory to confirm their reliability and safe operation.In a unique axial transverse flux switching permanent magnet(ATFSPM)generator,due to its high power density,large stray loss from leakage flux,compact topology,and totally enclosed structure,thermal analysis is of paramount significance.In this paper,thermal modeling and analysis of ATFSPM are carried out in detail using a three-dimensional(3D)finite element analysis(FEA)to evaluate the thermal condition for a precise performance improvement.To begin,all loss sources are accurately derived using 3-D FEA and analytical methods,taking into account the temperature dependence of material properties,and then losses are coupled to the thermal model as heat sources.Afterward,aiming for realistic thermal modelling,the convection heat transfer in the different regions of internal and external areas as well as thin layers of interface gaps between components are all considered.In addition,the prototype of ATFSPM is supplied to validate the accuracy of 3-D FEA temperature prediction.Furthermore,a novel technique is carried out to effectively improve thermal performance,enhance the efficiency,and limit hot-spot temperatures.The steady-state and transient temperature results demonstrate the high accuracy of the thermal modeling,enhance the secure operation of the ATFSPM,and facilitate increased loading utilizing the proposed technique.(1)展开更多
The consequences of climate change continue to threaten European forests,particularly for species located at the edges of their latitudinal and altitudinal ranges.While extensively studied in Central Europe,European b...The consequences of climate change continue to threaten European forests,particularly for species located at the edges of their latitudinal and altitudinal ranges.While extensively studied in Central Europe,European beech forests require further investigation to understand how climate change will affect these ecosystems in Mediterranean areas.Proposed silvicultural options increasingly aim at sustainable management to reduce biotic and abiotic stresses and enhance these forest ecosystems'resistance and resilience mechanisms.Process-based models(PBMs)can help us to simulate such phenomena and capture early stress signals while considering the effect of different management approaches.In this study,we focus on estimating sensitivity of two state-of-the-art PBMs forest models by simulating carbon and water fluxes at the stand level to assess productivity changes and feedback resulting from different climatic forcings as well as different management regimes.We applied the 3D-CMCC-FEM and MEDFATE forest models for carbon(C)and water(H_(2)O)fluxes in two sites of the Italian peninsula,Cansiglio in the north and Mongiana in the south,under managed vs.unmanaged scenarios and under current climate and different climatic scenarios(RCP4.5 and RCP8.5).To ensure confidence in the models’results,we preliminary evaluated their performance in simulating C and H_(2)O flux in three additional beech forests of the FLUXNET network along a latitudinal gradient spanning from Denmark to central Italy.The 3D-CMCC-FEM model achieved R^(2)values of 0.83 and 0.86 with RMSEs of 2.53 and 2.05 for C and H_(2)O fluxes,respectively.MEDFATE showed R^(2)values of 0.76 and 0.69 with RMSEs of 2.54 and 3.01.At the Cansiglio site in northern Italy,both models simulated a general increase in C and H_(2)O fluxes under the RCP8.5 climate scenario compared to the current climate.Still,no benefit in managed plots compared to unmanaged ones,as the site does not have water availability limitations,and thus,competition for water is low.At the Mongiana site in southern Italy,both models predict a decrease in C and H_(2)O fluxes and sensitivity to the different climatic forcing compared to the current climate;and an increase in C and H_(2)O fluxes when considering specific management regimes compared to unmanaged scenarios.Conversely,under unmanaged scenarios plots are simulated to experience first signals of mortality prematurely due to water stress(MEDFATE)and carbon starvation(3D-CMCC-FEM)scenarios.In conclusion,while management interventions may be considered a viable solution for the conservation of beech forests under future climate conditions at moister sites like Cansiglio,in drier sites like Mongiana conservation may not lie in management interventions alone.展开更多
Understanding the characteristics and variations of heat exchange and evaporation of lakes is important for regional water resource management and sustainable development.Based on eddy covariance measurements over Lak...Understanding the characteristics and variations of heat exchange and evaporation of lakes is important for regional water resource management and sustainable development.Based on eddy covariance measurements over Lake Vanajavesi in southern Finland,characteristics of energy fluxes and cold frontal effects on energy exchange were investigated.The lake acted as a heat sink in spring and summer and a heat source in winter.The latent heat flux reached its minimum value in the morning and peaked in the afternoon.The diurnal variation of sensible heat flux was opposite to that of latent heat flux.Impact factors for the sensible heat flux were mainly the lake-air temperature difference and the product of lake-air temperature difference and wind speed.The latent heat flux was mainly affected by the vapor pressure deficit and the product of vapor pressure deficit and wind speed.The annual mean values of bulk transfer coefficients for momentum,heat,and water vapor were 1.98×10^(-3),1.62×10^(-3),and 1.31×10^(-3),respectively.Bulk transfer coefficients for heat and water vapor were not equal,indicating that the parameterization of energy exchange in numerical models,where the assumption that the heat coefficient equals the water vapor coefficient needs improvement.During the ice-free season,cold fronts resulted in 28 sensible heat pulses and 17 latent heat pulses,contributing to 50.59%and 34.89%of sensible and latent heat exchange in Lake Vanajavesi.These results indicate that cold fronts significantly impact the surface energy budget and evaporation over lakes.展开更多
Ramsey oscillations typically exhibit an exponential decay envelope due to environmental noise. However,recent experiments have observed nonmonotonic Ramsey fringes characterized by beating patterns, which deviate fro...Ramsey oscillations typically exhibit an exponential decay envelope due to environmental noise. However,recent experiments have observed nonmonotonic Ramsey fringes characterized by beating patterns, which deviate from the standard behavior. These beating patterns have primarily been attributed to charge-noise fluctuations.In this paper, we have experimentally observed Ramsey fringe with beating pattern for transmon qubits, and traced the origin to electric instruments induced flux noise.展开更多
The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simu...The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simultaneous fluctuations that are superimposed on the amplitude and phase of the cavity electric field, as well as the atomic population inversion. The correlation function of these fluctuations yields the amplitude, phase, and spontaneous emission noise fluxes, respectively. The amplitude and spontaneous emission noise fluxes exhibit the Lorentzian profiles in both the below-threshold state and the injection-locking region of the above-threshold state. While noise is typically viewed negatively in science and engineering, this research highlights its positive role as a valuable tool for measuring the optical properties of a laser amplifier. For instance, the degree of first-order temporal coherence(DFOTC) is derived by taking the Fourier transform of the amplitude noise flux. The damping rate of DFOTC is associated with the coherence time of the light emitted by the laser amplifier. Furthermore, the uncertainty relation between noise bandwidth and coherence time is confirmed. Finally, it is demonstrated that the input pumping noise flux, together with the output amplitude and spontaneous emission noise fluxes, satisfy the principle of flux conservation.展开更多
Researches on plasma-facing materials/components(PFMs/PFCs)have become a focus in magnetic confinement fusion studies,particularly for advanced tokamak operation scenarios.Similarly,spacecraft surface materials must m...Researches on plasma-facing materials/components(PFMs/PFCs)have become a focus in magnetic confinement fusion studies,particularly for advanced tokamak operation scenarios.Similarly,spacecraft surface materials must maintain stable performance under relatively high temperatures and other harsh plasma conditions,making studies of their thermal and ablation resistance critical.Recently,a low-cost,low-energy-storage for superconducting magnets,and compact linear device,HIT-PSI,has been designed and constructed at Harbin Institute of Technology(HIT)to investigate the interaction between stable high heat flux plasma and PFMs/PFCs in scrape-off-layer(SOL)and divertor regions,as well as spacecraft surface materials.The parameters of the argon plasma beam of HIT-PSI are diagnosed using a water-cooled planar Langmuir probe and emission spectroscopy.As magnetic field rises to 2 T,the argon plasma beam generated by a cascaded arc source achieves high density exceeding 1.2×10^(21)m^(-3)at a distance of 25 cm from the source with electron temperature surpassing 4 eV,where the particle flux reaches 10^(24)m^(-2)s^(-1),and the heat flux loaded on the graphite target measured by infrared camera reaches 4 MW/m^(2).Combined with probe and emission spectroscopy data,the transport characteristics of the argon plasma beam are analyzed.展开更多
Steel–flux reactions involving the high aluminum(0.75–3.85 wt.%Al)low manganese(2.2 wt.%Mn)steel and the 18 wt.%SiO_(2)–18 wt.%Al2O3 mold flux were investigated.The results indicated that the reaction rate increase...Steel–flux reactions involving the high aluminum(0.75–3.85 wt.%Al)low manganese(2.2 wt.%Mn)steel and the 18 wt.%SiO_(2)–18 wt.%Al2O3 mold flux were investigated.The results indicated that the reaction rate increased when the initial aluminum content increased from 0.76 to 3.85 wt.%.Utilizing the two-film theory,a steel–flux reaction kinetic model controlled by mass transfer was established,which considered the influence of the initial composition on the density of liquid steel and flux.The mass transfer of aluminum in the steel phase was the reaction rate-determining step.It was confirmed that the mass transfer coefficient of Al was 1.87×10^(−4).The predicted results of the kinetic model were consistent and reliable with the experimental results.Thermodynamic equilibrium calculation was performed using FactSage 8.2,which was compared with the steel and flux final composition after 30 min.The content of initial aluminum in the liquid steel played a critical role in the SiO_(2)equilibrium content of the mold flux.In addition,the steel–flux reaction between[Al]and(SiO_(2))occurred with the initial SiO_(2)content in the mold flux lower than 3 wt.%.展开更多
Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess ...Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess and understand the spatial distribution of LE and SH fluxes across different underlying surfaces,it is crucial to verify the validity and reliability of ERA-5,GLDAS,and MODIS data against ground measurements obtained from the Flux Net micrometeorological tower network.This study analyzed the spatial patterns of LE and SH over the Tibetan Plateau using data from ERA-5,GLDAS,and MODIS.The results were compared with ground measurements from Flux Net tower observations on different underlying surfaces,and five statistical parameters(Pearson's r,LR slope,RMSE,MBE,and MAE)were used to validate the data.The results showed that:(1)MODIS LE data and ERA-5 SH data exhibited the closest agreement with ground observations,as indicated by their lowest root mean square error and mean bias area values.(2)The accuracy of ERA-5 SH was the highest in meadows and steppes,while GLDAS SH performed optimally in shrublands.Notably,MODIS LE consistently outperformed the other datasets across all vegetation types.(3)The spatial distribution of LE and SH displayed considerable heterogeneity,contingent upon the specific data sources and underlying surfaces.Notably,there was a contrasting trend between GLDAS and ERA-5,as well as MODIS,in terms of SH distribution in the shrubland.In shrublands and meadows,MODIS SH and LE exhibited more pronounced changes than ERA-5 and GLDAS.Additionally,ERA-5 SH demonstrated the opposite variation in meadow and steppe regions compared to GLDAS and MODIS.展开更多
[Objective] The paper was to analyze the quality of flux observation data of rubber plantation.[Method]Based on the FSAM model,footprint and flux source area were analyzed according to the continuous flux measurement ...[Objective] The paper was to analyze the quality of flux observation data of rubber plantation.[Method]Based on the FSAM model,footprint and flux source area were analyzed according to the continuous flux measurement with the open-path eddy covariance system on the 50 m tower of Danzhou Key Field Station of Observation and Research for Tropical Agricultural Resources and Environments,Ministry of Agriculture from Jan 1 to Jun 30,2010.[Result] Under unstable stratification,source areas were smaller than those under stable conditions,and source areas in the dormant season were larger than those in the growing season at the same level.In the main wind direction 130°-270°,the upwind range of source areas was in the magnitude of 100-758 m and vertical upwind range was-251-251 m at 80% level under unstable stratification in the growing season,and they were some large than those under the unstable stratification in the dormant season.The source areas of the upwind and vertical upwind ranges were 173-1 858,-534-534 m especially under stable stratification in the growing season,and they were smaller than those under stable stratification in the dormant season.In the other wind directions of 0°-130° and 270°-360°,the ranges were similar to those of the growing season in the prevailing wind direction under the same atmospheric conditions.[Conclusion] The study would lay a foundation for the future flux calculation and analysis.展开更多
Carbon fluxes are essential indicators assessing vegetation carbon cycle functions.However,the extent and mechanisms by which climate change and human activities influence the spatiotemporal dynamics of carbon fluxes ...Carbon fluxes are essential indicators assessing vegetation carbon cycle functions.However,the extent and mechanisms by which climate change and human activities influence the spatiotemporal dynamics of carbon fluxes in arid oasis and non-oasis area remains unclear.Here,we assessed and predicted the future effects of climate change and human activities on carbon fluxes in the Hexi Corridor.The results showed that the annual average gross primary productivity(GPP),net ecosystem productivity(NEP),and ecosystem respiration(Reco)in the Hexi Corridor oasis increased by 263.91 g C·m^(-2)·yr^(-1),118.45 g C·m^(-2)·yr^(-1)and 122.46 g C·m^(-2)·yr^(-1),respectively,due to the expansion of the oasis area by 3424.84 km^(2) caused by human activities from 2000 to 2022.Both oasis and non-oasis arid ecosystems in the Hexi Corridor acted as carbon sinks.Compared to the non-oasis area,the carbon fluxes contributions of oasis area increased,ranging from 10.21%to 13.99%for GPP,8.50%to11.68%for NEP,and 13.34%to 17.13%for Reco.The contribution of the carbon flux from the oasis expansion area to the total carbon flux change in the Hexi Corridor was 30.96%(7.09 Tg C yr^(-1))for GPP,29.57%(3.39 Tg C yr^(-1))for NEP and 32.40%(3.58 Tg C yr^(-1))for Reco.The changes in carbon fluxes in the oasis area were mainly attributed to human activities(oasis expansion)and temperature,whereas non-oasis area was mainly due to climate factors.Moreover,the future increasing trends were observed for GPP(64.99%),NEP(66.29%)and Reco(82.08%)in the Hexi Corridor.This study provides new insights into the regulatory mechanisms of carbon cycle in the arid oasis and non-oasis area.展开更多
To explore the relationship between dynamic characteristics and wake patterns,numerical simulations were conducted on three equal-diameter cylinders arranged in an equilateral triangle.The simulations varied reduced v...To explore the relationship between dynamic characteristics and wake patterns,numerical simulations were conducted on three equal-diameter cylinders arranged in an equilateral triangle.The simulations varied reduced velocities and gap spacing to observe flow-induced vibrations(FIVs).The immersed boundary–lattice Boltzmann flux solver(IB–LBFS)was applied as a numerical solution method,allowing for straightforward application on a simple Cartesian mesh.The accuracy and rationality of this method have been verified through comparisons with previous numerical results,including studies on flow past three stationary circular cylinders arranged in a similar pattern and vortex-induced vibrations of a single cylinder across different reduced velocities.When examining the FIVs of three cylinders,numerical simulations were carried out across a range of reduced velocities(3.0≤Ur≤13.0)and gap spacing(L=3D,4D,and 5D).The observed vibration response included several regimes:the desynchronization regime,the initial branch,and the lower branch.Notably,the transverse amplitude peaked,and a double vortex street formed in the wake when the reduced velocity reached the lower branch.This arrangement of three cylinders proved advantageous for energy capture as the upstream cylinder’s vibration response mirrored that of an isolated cylinder,while the response of each downstream cylinder was significantly enhanced.Compared to a single cylinder,the vibration and flow characteristics of this system are markedly more complex.The maximum transverse amplitudes of the downstream cylinders are nearly identical and exceed those observed in a single-cylinder set-up.Depending on the gap spacing,the flow pattern varied:it was in-phase for L=3D,antiphase for L=4D,and exhibited vortex shedding for L=5D.The wake configuration mainly featured double vortex streets for L=3D and evolved into two pairs of double vortex streets for L=5D.Consequently,it well illustrates the coupling mechanism that dynamics characteristics and wake vortex change with gap spacing and reduced velocities.展开更多
Global warming and nitrogen(N)deposition have a profound impact on greenhouse gas(GHG)fluxes and consequently,they also affect climate change.However,the global combined effects of warming and N addition on GHG fluxes...Global warming and nitrogen(N)deposition have a profound impact on greenhouse gas(GHG)fluxes and consequently,they also affect climate change.However,the global combined effects of warming and N addition on GHG fluxes remain to be fully understood.To address this knowledge gap,a globalmeta-analysis of 197 datasets was performed to assess the response of GHG fluxes to warming and N addition and their interactions under various climate and experimental conditions.The results indicate that warming significantly increased CO_(2)emissions,while N addition and the combined warming and N addition treatments had no impact on CO_(2)emissions.Moreover,both warming and N addition and their interactions exhibited positive effects on N_(2)O emissions.Under the combined warming and N addition treatments,warming was observed to exert a positive main effect on CO_(2)emissions,while N addition had a positive main effect on N_(2)O emissions.The interactive effects of warming and N addition exhibited antagonistic effects on CO_(2),N_(2)O,and CH_(4)emissions,with CH_(4)uptake dominated by additive effects.Furthermore,we identified biome and climate factors as the two treatments.These findings indicate that both warming and N addition substantially impact soil GHG fluxes and highlight the urgent need to investigate the influence of the combination of warming and N addition on terrestrial carbon and N cycling under ongoing global change.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52204345 and 52474361)the Scientific Research Innovation Projects of Graduate Student of Jiangsu province,China(No.KYCX24_4184)。
文摘The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerged entry nozzles,form floaters in the molds,and produce various surface defects on the cast slabs.This review summarizes the effects of nonmetallic inclusions on traditional CaO-SiO_(2)-based(CS)mold fluxes and novel CaO-Al_(2)O_(3)-based(CA)low-or non-reactive fluxes containing TiO_(2),BaO,and B_(2)O_(3)additives to avoid undesirable steel,slag,and inclusion reactions,with the aim of providing a new perspective for research and practice related to balancing the lubrication and heat transfer of mold fluxes to promote smooth operation and reduce surface defects on cast slabs.For traditional CS mold flux,although the addition of solvents such as Na_(2)O,Li_(2)O,and B_(2)O_(3)can enhance flowability,steel-slag reactions persist,limiting the effectiveness of CS mold fluxes in high-Ti steel casting.Low-or non-reactive CA mold fluxes with reduced SiO_(2)content are a research focus,where adding other components can significantly change flux characteristics.Replacing CaO with BaO can lower the melting point and inhibit crystallization,allowing the flux to maintain good flowability at low temperatures.Replacing SiO_(2)with TiO_(2)can stabilize the viscosity and enhance heat transfer.To reduce the environmental impact,fluorides are replaced with components such as TiO_(2),B_(2)O_(3),BaO,Li_(2)O,and Na_(2)O for F-frce mold fluxes with similar lubrication,crystallization,and heat-transfer effects.When TiO_(2)replaces CaF_(2),it stabilizes the viscosity and enhances the heat conductivity,forming CaTiO_(3)and CaSiTiO_(5)phases instead of cuspidine to control crystallization.B_(2)O_(3)lowers the melting point and suppresses crystallization,forming phases such as Ca_(3)B_(2)O_(6)and Ca_(11)Si_(4)B_(2)O_(22).BaO introduces non-bridging oxygen to reduce viscosity and ensure flux flowability at low temperatures.However,further studies are required to determine the optimal mold flux compositions corresponding to the steel grades and the interactions between the various components of the mold flux.In the future,the practical application of new mold fluxes for high-Ti steel will become the focus of further verification to achieve a balance between lubrication and heat transfer,which is expected to minimize the occurrence of casting problems and slab defects.
基金supported by the National Natural Science Foundation of China (Grant No.12575180)the Lingchuang Research Project of China National Nuclear Corporation (CNNC)。
文摘From an engineering feasibility standpoint, what level of performance metrics can be ultimately achieved when designing a reactor using well-established nuclear fuels and structural materials that have already undergone irradiation testing? The irradiation capability, which hinges on parameters like neutron flux level, irradiation channels' volume, and fuel cycle duration, is a core indicator for high-flux reactors. We propose a conceptual design of an ultra-high flux fast reactor(UFFR) with strong irradiation capability, which utilizes U-20Pu-10Zr alloy fuel and employs lead-bismuth as the coolant. The maximum neutron flux in the core reaches 1.32×10^(16) cm^(-2)s^(-1), while the average neutron flux in the irradiation channels attains 1.19×10^(16) cm^(-2)s^(-1). The volume of the central irradiation channel exceeds 10000 cm^(3), and the fuel cycle duration is 165 d, placing all its performance indicators among the top in the world. Based on the analyses of reactor physics and thermalhydraulics, it has been demonstrated that all reactivity coefficients are negative and all physical parameters meet the design criteria, ensuring the inherent safety of UFFR. An assessment of the irradiation capability has been carried out based on californium-252(^(252)Cf) production, indicating that the irradiation capability of UFFR surpasses that of the high flux isotope reactor(HFIR). The yield of ^(252)Cf from UFFR is 14.39 times that of HFIR, and its nuclei conversion rate is 3.21 times that of HFIR.
基金financially supported by the National Key Research and Development Program of China(2021YFD2200405)the National Natural Science Foundation of China(31930078)special funds for Baotianman Forest Ecosystem Research Station from Chinese Academy of Forestry and Ministry of Science and Technology of China。
文摘Frequent droughts pose considerable threat to global forest carbon uptake,but little is known about the response of forest carbon fluxes in climatic transition zones to seasonal drought.In this study,the responses of carbon fluxes to seasonal drought in two natural forests(Quercus aliena var.acute serrata Maxim and Pinus tabuliformis Carr.)in the Baotianman Nature Reserve were investigated.The Q.aliena forest exhibited a high resilience with stable gross primary productivity(GPP).However,ecosystem respiration(Re)significantly declined by 18.4%compared with normal years,leading to an increase in net carbon sequestration capacity of 4.1%.This resilience was attributed to its deep root system accessing soil water(SWC_(50cm))to sustain stomatal openness,coupled with the efficient utilization of photosynthetically active radiation to drive photosynthesis.In contrast,the P.tabuliformis forest,which relied on shallow soil moisture(SWC_(20cm)),experienced simultaneous decreases in both GPP and Re during drought,with a sharply greater decrease in GPP,resulting in low net carbon sink capacity.Further analysis revealed that the Q.aliena forest prioritized carbon assimilation through a deep water-stomatal synergy strategy(anisohydric behavior),whereas the P.tabuliformis forest adopted an isohydric strategy favoring water conservation at the expense of carbon fixation efficiency.These findings highlight distinct mechanisms underlying drought adaptation between forest types,providing critical insight into optimizing forest carbon cycle models and selecting drought-resistant species under the influence of climate change.
文摘An atmospheric general circulation model(AGCM)is used to analyze the different impact on the Barents Sea(BS)and Greenland Sea(GS)for a perturbation of sea-to-air DMS flux.We compare contemporary anthropogenic S and contemporary DMS sea-to-air flux(as baseline,B00)sulfur emissions,with contemporary anthropogenic S and a perturbed DMS flux(as modified,B01)sulfur emissions.Results show that the global mean surface DMS and DMS vertically integrated concentration all peaked in June and increases more than 63%in BS and increases about 58%in GS.The concentrations of atmospheric sulfur dioxide vertical integral(SO_(2))and sulfate vertical integral(SO_(4))only increase less than 12%in both regions.Sulfur emission(SEM)peaked in June and increased about 67%and 41%in GS and BS,respectively.Aerosol optical depth(AOD)increases less than 4%in GS and in BS.Surface temperature(TSC)peaked in July and reduces 0.25 K and 0.8 K in GS and BS,respectively.Satellite data from 2003 to 2023show that chlorophyll(CHL)concentration in BS exceeds that of GS by 51%.The AOD in GS is only 0.6%higher than in BS.The recent increased rate of DMS surface concentration in BS(from 6%during 1981–2002 to 18.8%in 2003–2023)is mainly caused by elevated CHL concentrations in BS.Finally,the perturbation on DMS flux leads to increase rate of DMS and related sulfur emissions especially in the BS,this tendency will have an offsetting effect on regional warming.
文摘Correction to:Journal of Forestry Research(2025)36:124 https://doi.org/10.1007/s11676-025-01918-8 In this article the author’s name Yasutomo Hoshika was incorrectly written as Yasutoma Hoshika.The original article has been corrected.
基金jointly funded by the National Natural Science Foundation of China(Grant No.42161024)the Central Financial Forestry and Grassland Science and Technology Extension Demonstration Project(2025)(Grant No.Xin[2025]TG 09)。
文摘Accurate quantification of carbon and water fluxes dynamics in arid and semi-arid ecosystems is a critical scientific challenge for regional carbon neutrality assessments and sustainable water resource management.In this study,we developed a multi-flux global sensitivity discriminant index(D_(sen))by integrating the Biome-BGCMuSo model with eddy covariance flux observations.This index was combined with a Bayesian optimization algorithm to conduct parameter optimization.The results demonstrated that:(1)Sensitivity analysis identified 13 highly sensitive parameters affecting carbon and water fluxes.Among these,the canopy light extinction coefficient(k)and the fraction of leaf N in Rubisco(FLNR)exhibited significantly higher sensitivity to carbon fluxes(GPP,NEE,Reco;D_(sen)>10%)compared to water flux(ET).This highlights the strong dependence of carbon cycle simulations on vegetation physiological parameters.(2)The Bayesian optimization framework efficiently converged 30 parameter spaces within 50 iterations,markedly improving carbon fluxes simulation accuracy.The Kling-Gupta efficiency(KGE)values for Gross Primary Production(GPP),Net Ecosystem Exchange(NEE),and Total Respiration(Reco)increased by 44.94%,69.23%and 123%,respectively.The optimization prioritized highly sensitive parameters,underscoring the necessity of parameter sensitivity stratification.(3)The optimized model effectively reproduced carbon sink characteristics in mountain meadows during the growing season(cumulative NEE=-375 g C/m^(2)).It revealed synergistic carbon-water fluxes interactions governed by coupled photosynthesis-stomatal pathways and identified substrate supply limitations on heterotrophic respiration.This study proposes a novel multi-flux sensitivity index and an efficient optimization framework,elucidating the coupling mechanisms between vegetation physiological regulation(k,FLNR)and environmental stressors(VPD,SWD)in carbonwater cycles.The methodology offers a practical approach for arid ecosystem model optimization and provides theoretical insights for grassland management through canopy structure regulation and water-use efficiency enhancement.
基金supported by research grants of the Iran National Science Foundation(INSF)under grant No.98002866。
文摘The efficiency of energy conversion from mechanical to electrical in AC generators is not entirely optimal,as power losses are converted into heat.Accurate thermal modeling and temperature measurement of advanced electric machines with complex structures are mandatory to confirm their reliability and safe operation.In a unique axial transverse flux switching permanent magnet(ATFSPM)generator,due to its high power density,large stray loss from leakage flux,compact topology,and totally enclosed structure,thermal analysis is of paramount significance.In this paper,thermal modeling and analysis of ATFSPM are carried out in detail using a three-dimensional(3D)finite element analysis(FEA)to evaluate the thermal condition for a precise performance improvement.To begin,all loss sources are accurately derived using 3-D FEA and analytical methods,taking into account the temperature dependence of material properties,and then losses are coupled to the thermal model as heat sources.Afterward,aiming for realistic thermal modelling,the convection heat transfer in the different regions of internal and external areas as well as thin layers of interface gaps between components are all considered.In addition,the prototype of ATFSPM is supplied to validate the accuracy of 3-D FEA temperature prediction.Furthermore,a novel technique is carried out to effectively improve thermal performance,enhance the efficiency,and limit hot-spot temperatures.The steady-state and transient temperature results demonstrate the high accuracy of the thermal modeling,enhance the secure operation of the ATFSPM,and facilitate increased loading utilizing the proposed technique.(1)
基金the Institute Research Centre for Ecological and Forestry Applications (CREAF) of Barcelona that supported the research by the Spanish “Ministerio de Ciencia e Innovacio'n”(MCIN/AEI/ 10.13039/501100011033) (grant agreement No. PID 2021-126679OBI00)partially supported by MIUR Project (PRIN 2020) between WATER and carbon cycles during droug“Unraveling interactionsht and their impact on water resources and forest and grassland ecosySTEMs in the Mediterranean climate (WATERSTEM)”(Project number: 20202WF53Z),“WAFER”at CNR (Consiglio Nazionale delle Ricerche)+3 种基金Priwitzer et al. (2014) (cod. 2020E52THS)-Research Projects of National Relevance funded by the Italian Ministry of University and Research entitled: “Multi-scale observations to predict Forest response to pollution and climate change”(MULTIFOR, project number: 2020E52THS)funding by the project OptForEU Horizon Europe research and innovation programme under grant agreement No. 101060554the project funded under the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.4-Call for tender No. 3138 of December 16, 2021, rectified by Decree n.3175 of December 18, 2021 of Italian Ministry of UniversityResearch funded by the European UnionationEU under award Number: Project code CN_00000033–Next Gener, Concession Decree No. 1034 of June 17, 2022 adopted by the Italian Ministry of University and Research, CUP B83C22002930006, Project title“National Biodiversity Future Centre-NBFC”
文摘The consequences of climate change continue to threaten European forests,particularly for species located at the edges of their latitudinal and altitudinal ranges.While extensively studied in Central Europe,European beech forests require further investigation to understand how climate change will affect these ecosystems in Mediterranean areas.Proposed silvicultural options increasingly aim at sustainable management to reduce biotic and abiotic stresses and enhance these forest ecosystems'resistance and resilience mechanisms.Process-based models(PBMs)can help us to simulate such phenomena and capture early stress signals while considering the effect of different management approaches.In this study,we focus on estimating sensitivity of two state-of-the-art PBMs forest models by simulating carbon and water fluxes at the stand level to assess productivity changes and feedback resulting from different climatic forcings as well as different management regimes.We applied the 3D-CMCC-FEM and MEDFATE forest models for carbon(C)and water(H_(2)O)fluxes in two sites of the Italian peninsula,Cansiglio in the north and Mongiana in the south,under managed vs.unmanaged scenarios and under current climate and different climatic scenarios(RCP4.5 and RCP8.5).To ensure confidence in the models’results,we preliminary evaluated their performance in simulating C and H_(2)O flux in three additional beech forests of the FLUXNET network along a latitudinal gradient spanning from Denmark to central Italy.The 3D-CMCC-FEM model achieved R^(2)values of 0.83 and 0.86 with RMSEs of 2.53 and 2.05 for C and H_(2)O fluxes,respectively.MEDFATE showed R^(2)values of 0.76 and 0.69 with RMSEs of 2.54 and 3.01.At the Cansiglio site in northern Italy,both models simulated a general increase in C and H_(2)O fluxes under the RCP8.5 climate scenario compared to the current climate.Still,no benefit in managed plots compared to unmanaged ones,as the site does not have water availability limitations,and thus,competition for water is low.At the Mongiana site in southern Italy,both models predict a decrease in C and H_(2)O fluxes and sensitivity to the different climatic forcing compared to the current climate;and an increase in C and H_(2)O fluxes when considering specific management regimes compared to unmanaged scenarios.Conversely,under unmanaged scenarios plots are simulated to experience first signals of mortality prematurely due to water stress(MEDFATE)and carbon starvation(3D-CMCC-FEM)scenarios.In conclusion,while management interventions may be considered a viable solution for the conservation of beech forests under future climate conditions at moister sites like Cansiglio,in drier sites like Mongiana conservation may not lie in management interventions alone.
基金supported by funds from the National Natural Science Foundation of China(Grant Nos:42275079,41975017,42411530052,and 42161144010)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0105)。
文摘Understanding the characteristics and variations of heat exchange and evaporation of lakes is important for regional water resource management and sustainable development.Based on eddy covariance measurements over Lake Vanajavesi in southern Finland,characteristics of energy fluxes and cold frontal effects on energy exchange were investigated.The lake acted as a heat sink in spring and summer and a heat source in winter.The latent heat flux reached its minimum value in the morning and peaked in the afternoon.The diurnal variation of sensible heat flux was opposite to that of latent heat flux.Impact factors for the sensible heat flux were mainly the lake-air temperature difference and the product of lake-air temperature difference and wind speed.The latent heat flux was mainly affected by the vapor pressure deficit and the product of vapor pressure deficit and wind speed.The annual mean values of bulk transfer coefficients for momentum,heat,and water vapor were 1.98×10^(-3),1.62×10^(-3),and 1.31×10^(-3),respectively.Bulk transfer coefficients for heat and water vapor were not equal,indicating that the parameterization of energy exchange in numerical models,where the assumption that the heat coefficient equals the water vapor coefficient needs improvement.During the ice-free season,cold fronts resulted in 28 sensible heat pulses and 17 latent heat pulses,contributing to 50.59%and 34.89%of sensible and latent heat exchange in Lake Vanajavesi.These results indicate that cold fronts significantly impact the surface energy budget and evaporation over lakes.
文摘Ramsey oscillations typically exhibit an exponential decay envelope due to environmental noise. However,recent experiments have observed nonmonotonic Ramsey fringes characterized by beating patterns, which deviate from the standard behavior. These beating patterns have primarily been attributed to charge-noise fluctuations.In this paper, we have experimentally observed Ramsey fringe with beating pattern for transmon qubits, and traced the origin to electric instruments induced flux noise.
文摘The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simultaneous fluctuations that are superimposed on the amplitude and phase of the cavity electric field, as well as the atomic population inversion. The correlation function of these fluctuations yields the amplitude, phase, and spontaneous emission noise fluxes, respectively. The amplitude and spontaneous emission noise fluxes exhibit the Lorentzian profiles in both the below-threshold state and the injection-locking region of the above-threshold state. While noise is typically viewed negatively in science and engineering, this research highlights its positive role as a valuable tool for measuring the optical properties of a laser amplifier. For instance, the degree of first-order temporal coherence(DFOTC) is derived by taking the Fourier transform of the amplitude noise flux. The damping rate of DFOTC is associated with the coherence time of the light emitted by the laser amplifier. Furthermore, the uncertainty relation between noise bandwidth and coherence time is confirmed. Finally, it is demonstrated that the input pumping noise flux, together with the output amplitude and spontaneous emission noise fluxes, satisfy the principle of flux conservation.
基金supported by National Natural Science Foundation of China(No.12105067)the ITER Organization and China Domestic Agency for the support of this work(No.ITER5.5.P01.CN.05)。
文摘Researches on plasma-facing materials/components(PFMs/PFCs)have become a focus in magnetic confinement fusion studies,particularly for advanced tokamak operation scenarios.Similarly,spacecraft surface materials must maintain stable performance under relatively high temperatures and other harsh plasma conditions,making studies of their thermal and ablation resistance critical.Recently,a low-cost,low-energy-storage for superconducting magnets,and compact linear device,HIT-PSI,has been designed and constructed at Harbin Institute of Technology(HIT)to investigate the interaction between stable high heat flux plasma and PFMs/PFCs in scrape-off-layer(SOL)and divertor regions,as well as spacecraft surface materials.The parameters of the argon plasma beam of HIT-PSI are diagnosed using a water-cooled planar Langmuir probe and emission spectroscopy.As magnetic field rises to 2 T,the argon plasma beam generated by a cascaded arc source achieves high density exceeding 1.2×10^(21)m^(-3)at a distance of 25 cm from the source with electron temperature surpassing 4 eV,where the particle flux reaches 10^(24)m^(-2)s^(-1),and the heat flux loaded on the graphite target measured by infrared camera reaches 4 MW/m^(2).Combined with probe and emission spectroscopy data,the transport characteristics of the argon plasma beam are analyzed.
基金support from the National Key R&D Program of China(No.2023YFB3709900)the National Natural Science Foundation of China(Grant No.U22A20171).
文摘Steel–flux reactions involving the high aluminum(0.75–3.85 wt.%Al)low manganese(2.2 wt.%Mn)steel and the 18 wt.%SiO_(2)–18 wt.%Al2O3 mold flux were investigated.The results indicated that the reaction rate increased when the initial aluminum content increased from 0.76 to 3.85 wt.%.Utilizing the two-film theory,a steel–flux reaction kinetic model controlled by mass transfer was established,which considered the influence of the initial composition on the density of liquid steel and flux.The mass transfer of aluminum in the steel phase was the reaction rate-determining step.It was confirmed that the mass transfer coefficient of Al was 1.87×10^(−4).The predicted results of the kinetic model were consistent and reliable with the experimental results.Thermodynamic equilibrium calculation was performed using FactSage 8.2,which was compared with the steel and flux final composition after 30 min.The content of initial aluminum in the liquid steel played a critical role in the SiO_(2)equilibrium content of the mold flux.In addition,the steel–flux reaction between[Al]and(SiO_(2))occurred with the initial SiO_(2)content in the mold flux lower than 3 wt.%.
基金funded by the West Light Scholar of the Chinese Academy of Sciences(xbzg-zdsys-202202)the Natural Science Foundation of Henan(Grant No.232300420165)Integrated Scientific Investigation of the North-South Transitional Zone of China(2017FY100900)。
文摘Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess and understand the spatial distribution of LE and SH fluxes across different underlying surfaces,it is crucial to verify the validity and reliability of ERA-5,GLDAS,and MODIS data against ground measurements obtained from the Flux Net micrometeorological tower network.This study analyzed the spatial patterns of LE and SH over the Tibetan Plateau using data from ERA-5,GLDAS,and MODIS.The results were compared with ground measurements from Flux Net tower observations on different underlying surfaces,and five statistical parameters(Pearson's r,LR slope,RMSE,MBE,and MAE)were used to validate the data.The results showed that:(1)MODIS LE data and ERA-5 SH data exhibited the closest agreement with ground observations,as indicated by their lowest root mean square error and mean bias area values.(2)The accuracy of ERA-5 SH was the highest in meadows and steppes,while GLDAS SH performed optimally in shrublands.Notably,MODIS LE consistently outperformed the other datasets across all vegetation types.(3)The spatial distribution of LE and SH displayed considerable heterogeneity,contingent upon the specific data sources and underlying surfaces.Notably,there was a contrasting trend between GLDAS and ERA-5,as well as MODIS,in terms of SH distribution in the shrubland.In shrublands and meadows,MODIS SH and LE exhibited more pronounced changes than ERA-5 and GLDAS.Additionally,ERA-5 SH demonstrated the opposite variation in meadow and steppe regions compared to GLDAS and MODIS.
基金Supported by the Fundamental Research Funds for Rubber Research Institute,CATAS (1630022011013 )Hainan Natural Science Foundation (807045)Running Costs of Danzhou Key Field Station of Observation and Research for Tropical Agricultural Resources and Environments,Ministry of Agriculture~~
文摘[Objective] The paper was to analyze the quality of flux observation data of rubber plantation.[Method]Based on the FSAM model,footprint and flux source area were analyzed according to the continuous flux measurement with the open-path eddy covariance system on the 50 m tower of Danzhou Key Field Station of Observation and Research for Tropical Agricultural Resources and Environments,Ministry of Agriculture from Jan 1 to Jun 30,2010.[Result] Under unstable stratification,source areas were smaller than those under stable conditions,and source areas in the dormant season were larger than those in the growing season at the same level.In the main wind direction 130°-270°,the upwind range of source areas was in the magnitude of 100-758 m and vertical upwind range was-251-251 m at 80% level under unstable stratification in the growing season,and they were some large than those under the unstable stratification in the dormant season.The source areas of the upwind and vertical upwind ranges were 173-1 858,-534-534 m especially under stable stratification in the growing season,and they were smaller than those under stable stratification in the dormant season.In the other wind directions of 0°-130° and 270°-360°,the ranges were similar to those of the growing season in the prevailing wind direction under the same atmospheric conditions.[Conclusion] The study would lay a foundation for the future flux calculation and analysis.
基金The Foundation for Distinguished Young Scholars of Gansu Province,No.22JR5RA046Key Research Program of Gansu Province,No.23ZDKA0004+2 种基金The Joint Funds of the National Natural Science Foundation of China,No.U22A202690Interdisciplinary Youth Team Project from the Key Laboratory of Cryospheric Science and Frozen Soil Engineering,No.CSFSE-ZQ-2408The Youth Innovation Promotion Association CAS to X.W.,No.2020422。
文摘Carbon fluxes are essential indicators assessing vegetation carbon cycle functions.However,the extent and mechanisms by which climate change and human activities influence the spatiotemporal dynamics of carbon fluxes in arid oasis and non-oasis area remains unclear.Here,we assessed and predicted the future effects of climate change and human activities on carbon fluxes in the Hexi Corridor.The results showed that the annual average gross primary productivity(GPP),net ecosystem productivity(NEP),and ecosystem respiration(Reco)in the Hexi Corridor oasis increased by 263.91 g C·m^(-2)·yr^(-1),118.45 g C·m^(-2)·yr^(-1)and 122.46 g C·m^(-2)·yr^(-1),respectively,due to the expansion of the oasis area by 3424.84 km^(2) caused by human activities from 2000 to 2022.Both oasis and non-oasis arid ecosystems in the Hexi Corridor acted as carbon sinks.Compared to the non-oasis area,the carbon fluxes contributions of oasis area increased,ranging from 10.21%to 13.99%for GPP,8.50%to11.68%for NEP,and 13.34%to 17.13%for Reco.The contribution of the carbon flux from the oasis expansion area to the total carbon flux change in the Hexi Corridor was 30.96%(7.09 Tg C yr^(-1))for GPP,29.57%(3.39 Tg C yr^(-1))for NEP and 32.40%(3.58 Tg C yr^(-1))for Reco.The changes in carbon fluxes in the oasis area were mainly attributed to human activities(oasis expansion)and temperature,whereas non-oasis area was mainly due to climate factors.Moreover,the future increasing trends were observed for GPP(64.99%),NEP(66.29%)and Reco(82.08%)in the Hexi Corridor.This study provides new insights into the regulatory mechanisms of carbon cycle in the arid oasis and non-oasis area.
基金Supported by the National Natural Science Foundation of China(52201350,52201394,and 52271301)the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.SML2022008).
文摘To explore the relationship between dynamic characteristics and wake patterns,numerical simulations were conducted on three equal-diameter cylinders arranged in an equilateral triangle.The simulations varied reduced velocities and gap spacing to observe flow-induced vibrations(FIVs).The immersed boundary–lattice Boltzmann flux solver(IB–LBFS)was applied as a numerical solution method,allowing for straightforward application on a simple Cartesian mesh.The accuracy and rationality of this method have been verified through comparisons with previous numerical results,including studies on flow past three stationary circular cylinders arranged in a similar pattern and vortex-induced vibrations of a single cylinder across different reduced velocities.When examining the FIVs of three cylinders,numerical simulations were carried out across a range of reduced velocities(3.0≤Ur≤13.0)and gap spacing(L=3D,4D,and 5D).The observed vibration response included several regimes:the desynchronization regime,the initial branch,and the lower branch.Notably,the transverse amplitude peaked,and a double vortex street formed in the wake when the reduced velocity reached the lower branch.This arrangement of three cylinders proved advantageous for energy capture as the upstream cylinder’s vibration response mirrored that of an isolated cylinder,while the response of each downstream cylinder was significantly enhanced.Compared to a single cylinder,the vibration and flow characteristics of this system are markedly more complex.The maximum transverse amplitudes of the downstream cylinders are nearly identical and exceed those observed in a single-cylinder set-up.Depending on the gap spacing,the flow pattern varied:it was in-phase for L=3D,antiphase for L=4D,and exhibited vortex shedding for L=5D.The wake configuration mainly featured double vortex streets for L=3D and evolved into two pairs of double vortex streets for L=5D.Consequently,it well illustrates the coupling mechanism that dynamics characteristics and wake vortex change with gap spacing and reduced velocities.
基金supported by Ningxia Key Research and Development Fund Project of China(No.2023BCF01048)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2023-JC-YB-182).
文摘Global warming and nitrogen(N)deposition have a profound impact on greenhouse gas(GHG)fluxes and consequently,they also affect climate change.However,the global combined effects of warming and N addition on GHG fluxes remain to be fully understood.To address this knowledge gap,a globalmeta-analysis of 197 datasets was performed to assess the response of GHG fluxes to warming and N addition and their interactions under various climate and experimental conditions.The results indicate that warming significantly increased CO_(2)emissions,while N addition and the combined warming and N addition treatments had no impact on CO_(2)emissions.Moreover,both warming and N addition and their interactions exhibited positive effects on N_(2)O emissions.Under the combined warming and N addition treatments,warming was observed to exert a positive main effect on CO_(2)emissions,while N addition had a positive main effect on N_(2)O emissions.The interactive effects of warming and N addition exhibited antagonistic effects on CO_(2),N_(2)O,and CH_(4)emissions,with CH_(4)uptake dominated by additive effects.Furthermore,we identified biome and climate factors as the two treatments.These findings indicate that both warming and N addition substantially impact soil GHG fluxes and highlight the urgent need to investigate the influence of the combination of warming and N addition on terrestrial carbon and N cycling under ongoing global change.
