The deformation behavior of GH4169 superalloy under room-temperature uniaxial tension was investigated through synchronized mesoscopic digital image correlation(DIC)and electron backscatter diffraction(EBSD)in-situ ch...The deformation behavior of GH4169 superalloy under room-temperature uniaxial tension was investigated through synchronized mesoscopic digital image correlation(DIC)and electron backscatter diffraction(EBSD)in-situ characterization techniques.Results show that in the field of grain deflection dynamics,through quantitative analysis using the independently developed M-DIC software,during uniaxial tension with significant bidirectional rotation along the tensile axis and the stress level of 1100 MPa,oscillatory rotation of±0.6°can be obtained,and microvoids are generated at the grain boundaries with 45°to the stress axis.EBSD crystallographic analysis demonstrates the load-dependent slip system evolution:in the initial stage,the soft-oriented systems with high Schmid factor(>0.4)is activated and then transformed into hard-oriented systems during cross-slip,generating parallel slip bands and dislocation pile-ups at grain boundaries.During the uniaxial tensile process,the characteristic of strain energy accumulation is observed,which follows a two-stage accumulation pattern:initial grain boundary localization(Stage I)and intragranular propagation(Stage II).Ultimately,the intergranular cracks are initiated at triple junctions,and the twin boundaries exhibit superior mechanical stability compared with the large-angle grain boundaries.Deformation texture characteristics indicate the copper-type components,including C{112}<111¯>,S{123}<634¯>,and B{110}<11¯0>.The complete deformation sequence is as follows:cross-slip of soft-oriented slip systems→initiation of dislocation slip→strain partitioning through grain rotation→intergranular stress concentration→damage dominated by boundary cracking.The cross-scale deformation mechanism revealed in this study provides critical guidance for the crystal boundary engineering to optimize nickel-based superalloys.展开更多
Objectives:One of the most notable challenges in endoscopic procedures is maintaining correct orientation.Mental rotation exercise(MRE)has been suggested as a potential aid for improving orientation.However,there is a...Objectives:One of the most notable challenges in endoscopic procedures is maintaining correct orientation.Mental rotation exercise(MRE)has been suggested as a potential aid for improving orientation.However,there is a lack of research on designing MREs with varying difficultylevels for training purposes.Furthermore,few studies provide solid evidence linking MRE difficultylevels with cognitive load measurements.This study aims to address this gap by investigating the correlation between the MRE difficultylevels and participants’cognitive load,as measured by pupil dilation.Method:We recruited 33 participants to perform MREs on a computer equipped with a screen-mounted eye-tracker.The test consisted of 15 MREs,with the first10 relatively easy(traditional cube)and the next 5 more complex(invented molecule).The participants’eye movements during MREs were recorded.The participants’MRE scores and pupil dilation were obtained and compared between two MRE difficultylevels.Results:The participants who performed traditional cube MREs achieved significantlybetter MRE scores(0.77±0.11 vs.0.58±0.03,p<0.001)and lower pupil dilation(0.27±0.04 pixels vs.0.47±0.09 pixels,p<0.001)than did those who performed the invented molecule MREs.Moreover,there were significant negative correlations(r=0.62,p=0.015)between pupil dilation and MRE scores.Conclusions:The results revealed a significantnegative correlation between MRE scores and pupil dilation.The more challenging MRE questions led to worse MRE scores but increased pupil dilation.The MRE difficultylevels can be evaluated not only by the degrees or dimensions with which the objects were rotated but also by the participants’MRE scores and pupil dilation.The results of this study provide a basis for training orientation skills in endoscopy using MREs.By incorporating MREs with varying difficultylevels,customized training programs can be developed to enhance camera navigation in endoscopic and laparoscopic procedures.展开更多
In this paper,a theoretical model is established for locally resonant plates with general resonators,and the corresponding governing equation is derived.The model provides a mathematical demonstration of the locally r...In this paper,a theoretical model is established for locally resonant plates with general resonators,and the corresponding governing equation is derived.The model provides a mathematical demonstration of the locally resonant effect,which contains two parts:the first part is induced by translation coupling,and the second part is induced by rotation coupling.The second part cannot be reflected by most existing theoretical models.The analytical solutions of the dynamic response are compared with the direct numerical simulation(DNS)results for two locally resonant plates with different resonator types,thereby validating the general applicability of the present model.The rotation coupling effect leads to the frequency-dependent effective rotational inertia density and anisotropic dispersion relation of the locally resonant plate,as well as the enhancement of the structural vibration suppression ability.展开更多
The accurate segmentation of deep gray matter nuclei is critical for neuropathological research,disease diagnosis and treatment.Existing methods employ the supervised learning training approach,which requires large la...The accurate segmentation of deep gray matter nuclei is critical for neuropathological research,disease diagnosis and treatment.Existing methods employ the supervised learning training approach,which requires large labeled datasets.It is challenging and time-consuming to obtain such datasets for medical image analysis.In addition,these methods based on convolutional neural networks(CNNs)only achieve suboptimal performance due to the locality of convolutional operations.Vision Transformers(ViTs)efficiently model long-range dependencies and thus have the potentiality to outperform these methods in segmentation tasks.To address these issues,we propose a novel hybrid network based on self-supervised pre-training for deep gray matter nuclei segmentation.Specifically,we present a CNN-Transformer hybrid network(CTNet),whose encoder consists of 3D CNN and ViT to learn local spatial-detailed features and global semantic information.A self-supervised learning(SSL)approach that integrates rotation prediction and masked feature reconstruction is proposed to pre-train the CTNet,enabling the model to learn valuable visual representations from unlabeled data.We evaluate the effectiveness of our method on 3T and 7T human brain MRI datasets.The results demonstrate that our CTNet achieves better performance than other comparison models and our pre-training strategy outperforms other advanced self-supervised methods.When the training set has only one sample,our pre-trained CTNet enhances segmentation performance,showing an 8.4%improvement in Dice similarity coefficient(DSC)compared to the randomly initialized CTNet.展开更多
African drylands occupied 19.6 million km~2(46%of the total global area)and 525 million people.Soil erosion models are useful for assessing the impact of soil erosion in the dryland areas.This review provides an asses...African drylands occupied 19.6 million km~2(46%of the total global area)and 525 million people.Soil erosion models are useful for assessing the impact of soil erosion in the dryland areas.This review provides an assessment of soil erosion/deposition models and soil conservation practices,which are supportive for mitigating the impact of soil erosion and maintaining soil health and soil functional services for food security in African drylands.The theories of soil erosion models and soil conservation practices provide advanced ways to understand the detailed impact of soil erosion and management solutions.The paper reviews a set of useful soil erosion models and traditional conservation practices,which can control soil erosion and enhance dryland farming systems in Africa.Soil erosion models are classified into three categories:empirical,conceptual,and physical.Soil conservation practices include reduced tillage,advanced cover crops,mechanical structures(barriers made of stones/gravel/vegetation),advanced mechanical roller-crimper technique,mixed cropping,intercropping,crop rotation systems,terracing techniques,and land modification techniques.These conservation practices are effective in controlling soil erosion,reducing soil damage,improving soil health and quality,enhancing soil fertility,and ensuring food security.The existing assessment suggests that understanding the theories of soil erosion models and soil conservation practices is a first step towards addressing soil erosion problems in African drylands.展开更多
The effects ofγ-ray and electron irradiation on the microstructural evolution and mechanical properties of SnPb eutectic solder joints were investigated.Following electron irradiation,the SnO_(2)phase induced byγ-ra...The effects ofγ-ray and electron irradiation on the microstructural evolution and mechanical properties of SnPb eutectic solder joints were investigated.Following electron irradiation,the SnO_(2)phase induced byγ-ray irradiation transformed intoβ-Sn,and the dislocation density in theβ-Sn crystal decreased.Moreover,numerous point defect clusters formed in theβ-Sn crystal,some of which transformed into an amorphous phase,increasing the amorphous layer thickness.Meanwhile,electron irradiation likewise resulted in rotation of the(220)plane ofβ-Sn nanograins and reduction of SnO_(2)in theβ-Sn crystal.Additionally,upon exposure toγ-ray and electron irradiation,the average shear strength of the solder balls was initially increased by 10.10%,followed by a decrease of 3.53%and 4.77%,respectively.The plasticity and the dimple count on the fracture surfaces of the solder joint initially decreased but subsequently increased.展开更多
1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-...1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-sized particles(5-50μm)to fabricate coatings[1-3].CS has been extensively used in a variety of coating applications,such as aerospace,automotive,energy,medical,marine,and others,to provide protection against high temperatures,corrosion,erosion,oxidation,and chemicals[4,5].Nowadays,the technical interest in CS is twofold:(i)as a repair process for damaged components,and(ii)as a solid-state additive manufacturing process.Compared to other fusion-based additive manufacturing(AM)technologies,Cold Spray Additive Manufacturing(CSAM)is a new member of the AM family that can enable the fabrication of deposits without undergoing melting.The chemical composition has been largely preserved from the powder to the deposit due to the minimal oxidation.The significant advantages of CSAM over other additive manufacturing processes include a high production rate,unlimited deposition size,high flexibility,and suitability for repairing damaged parts.展开更多
Global food production faces enormous challenges in increasing yields while promoting environmental sustainability.A field experiments in the ecotone between the Yangtze River Basin and the HuangHuai-Hai Plain evaluat...Global food production faces enormous challenges in increasing yields while promoting environmental sustainability.A field experiments in the ecotone between the Yangtze River Basin and the HuangHuai-Hai Plain evaluated the effects of changing preceding crop rotation cycles(wheat and rapeseed)on long-term wheat-rice(W)and rapeseed-rice(R)rotation systems.A comprehensive evaluation of crop rotation systems was conducted using life cycle assessment,considering productivity,economic benefits,carbon footprint(CF),and soil health.Compared with fallow-rice rotation(F),alternating rapeseed and wheat rotations increased equivalent yield by 60.4%-82.2%,reduced CF by 0.3%-5.7%,and improved soil health by 0.3%-47.5%.Additionally,adding rapeseed to rotations increased soil nutrient content and raised soil organic carbon stocks by 31.3%-40.5%.The 3R rotation(3-year rapeseed-rice and 1-year wheat-rice)boosted rice yield by 82.2%and annual economic benefits by 84.4%,offering an effective model for optimizing long-term R rotations.Similarly,the 2W rotation(2-year wheat-rice and 1-year rapeseed rice)enhanced rice yield by 70.0% and annual economic benefits by 65.9%,providing a successful example for optimizing long-term W rotations.The 3R rapeseed-based rotation and the 2W wheatbased rotation demonstrated good environmental sustainability.These rotation systems have broad potential in sustainable intensive farming,especially in China and similar regions.展开更多
Dislocations and disclinations are fundamental topological defects within crystals,which determine the mechanical properties of metals and alloys.Despite their important roles in multiple physical mechanisms,e.g.,dyna...Dislocations and disclinations are fundamental topological defects within crystals,which determine the mechanical properties of metals and alloys.Despite their important roles in multiple physical mechanisms,e.g.,dynamic recovery and grain boundary mediated plasticity,the intrinsic coupling and correlation between disclinations and dislocations,and their impacts on the deformation behavior of metallic materials still remain obscure,partially due to the lack of a theoretical tool to capture the rotational nature of disclinations.By using a Lie-algebra-based theoretical framework,we obtain a general equation to quantify the intrinsic coupling of disclinations and dislocations.Through quasi in-situ electron backscatter diffraction characterizations and disclination/dislocation density analyses in Mg alloys,the generation,coevolution and reactions of disclinations and dislocations during dynamic recovery and superplastic deformation have been quantitatively analyzed.It has been demonstrated that the obtained governing equation can capture multiple physical processes associated with mechanical deformation of metals,e.g.,grain rotation and grain boundary migration,at both room temperature and high temperature.By establishing the disclination-dislocation coupling equation within a Lie algebra description,our work provides new insights for exploring the coevolution and reaction of disclinations/dislocations,with profound implications for elucidating the microstructure-property relationship and underlying deformation mechanisms in metallic materials.展开更多
This paper demonstrated the generation of multi-wavelength bound state noise-like pulse(BNLP)in a dispersion-managed composite-filtered fiber laser consisting of nonlinear polarization rotation(NPR)and loop.In the cas...This paper demonstrated the generation of multi-wavelength bound state noise-like pulse(BNLP)in a dispersion-managed composite-filtered fiber laser consisting of nonlinear polarization rotation(NPR)and loop.In the case of BNLP,the generation is caused by the interaction between two noise-like pulses(NLPs)induced by the comb-filtering effect,and bound state level can be artificially controlled in the researches.Our work provides a new method for generating low-coherence pulses and establishes a research idea for the study of the comb-filtering effects.展开更多
Internal rotation of conjugated organic backbone seriously impaired room temperature phosphorescence(RTP),leading to rare realization of ultra-long afterglows with RTP lifetimes over 2 s in non-bibulous polymers.Herei...Internal rotation of conjugated organic backbone seriously impaired room temperature phosphorescence(RTP),leading to rare realization of ultra-long afterglows with RTP lifetimes over 2 s in non-bibulous polymers.Herein,N-(bromophenyl)carbazoles are cyclized to lock up phenyl-carbazol internal rotation in advance and the fused nitrogen hetero-cyclic compounds are doped into poly(methyl methacrylate)(PMMA).The results show that locking up the molecular internal rotation can achieve ultra-long RTP polymers with lifetimes over 2 s,in contrast,the unlocked molecules hardly emit RTP in PMMA.The high-lying triplet excitons can transfer the energy to low-lying organic fluorescent dyes,and the persistent multicolor afterglows including white emission can be readily modulated.This work discloses an effective and extendable dopant molecular strategy for developing high-performance ultra-long organic RTP polymers.展开更多
Thermal vibrational convection(TVC)refers to the time-averaged convection of a non-isothermal fluid subjected to oscillating force fields.It serves as an effective mechanism for heat transfer control,particularly unde...Thermal vibrational convection(TVC)refers to the time-averaged convection of a non-isothermal fluid subjected to oscillating force fields.It serves as an effective mechanism for heat transfer control,particularly under microgravity conditions.A key challenge in this field is understanding the effect of rotation on TVC,as fluid oscillations in rotating systems exhibit unique and specific characteristics.In this study,we examine TVC in a vertical flat layer with boundaries at different temperatures,rotating around a horizontal axis.The distinctive feature of this study is that the fluid oscillations within the cavity are not induced by vibrations of the cavity itself,but rather by the gravity field,giving them a tidal nature.Our findings reveal that inertial waves generated in the rotating layer qualitatively alter the TVC structure,producing time-averaged flows in the form of toroidal vortices.Experimental investigations of the structure of oscillatory and time-averaged flows,conducted using Particle Image Velocimetry(PIV)for flow velocity visualization,are complemented by theoretical calculations of inertial modes in a cavity with this geometry.To the best of our knowledge,this study represents the first of its kind.The agreement between experimental results and theoretical predictions confirms that the formation of convective structures in the form of toroidal vortices is driven by inertial waves induced by the gravity field.A decrease in the rotational velocity leads to a transformation of the convective structures,shifting from toroidal vortices of inertial-wave origin to classical cellular TVC.We present dimensionless parameters that define the excitation thresholds for both cellular convection and toroidal structures.展开更多
The dynamics of fluid and non-buoyant particles in a librating horizontal annulus is studied experimentally.In the absence of librations,the granular material forms a cylindrical layer near the outer boundary of the a...The dynamics of fluid and non-buoyant particles in a librating horizontal annulus is studied experimentally.In the absence of librations,the granular material forms a cylindrical layer near the outer boundary of the annulus and undergoes rigid-body rotation with the fluid and the annulus.It is demonstrated that the librational liquefaction of the granular material results in pattern formation.This self-organization process stems from the excitation of inertial modes induced by the oscillatory motion of liquefied granular material under the influence of the gravitational force.The inertial wave induces vortical fluid flow which entrains particles from rest and forms eroded areas that are equidistant from each other along the axis of rotation.Theoretical analysis and experiments demonstrate that a liquefied layer of granular material oscillates with a radian frequency equal to the angular velocity of the annulus and interacts with the inertial wave it excites.The new phenomenon of libration-induced pattern formation is of practical interest as it can be used to control multiphase flows and mass transfer in rotating containers in a variety of industrial processes.展开更多
Active matter exhibits collective motions at various scales.Geometric confinement has been identified as an effective way to control and manipulate active fluids,with much attention given to external factors.However,t...Active matter exhibits collective motions at various scales.Geometric confinement has been identified as an effective way to control and manipulate active fluids,with much attention given to external factors.However,the impact of the inherent properties of active particles on collective motion under confined conditions remains elusive.Here,we use a highly tunable active nematics model to study active systems under confinement,focusing on the effect of the self-driven speed of active particles.We identify three distinct states characterized by unique particle and flow fields within confined active nematic systems,among which circular rotation emerges as a collective motion involving rotational movement in both particle and flow fields.The theoretical phase diagram shows that increasing the self-driven speed of active particles significantly enhances the region of the circular rotation state and improves its stability.Our results provide insights into the formation of high quality vortices in confined active nematic systems.展开更多
In order to get rid of the dependence on high-precision centrifuges in accelerometer nonlinear coefficients calibration,this paper proposes a system-level calibration method for field condition.Firstly,a 42-dimension ...In order to get rid of the dependence on high-precision centrifuges in accelerometer nonlinear coefficients calibration,this paper proposes a system-level calibration method for field condition.Firstly,a 42-dimension Kalman filter is constructed to reduce impact brought by turntable.Then,a biaxial rotation path is designed based on the accelerometer output model,including orthogonal 22 positions and tilt 12 positions,which enhances gravity excitation on nonlinear coefficients of accelerometer.Finally,sampling is carried out for calibration and further experiments.The results of static inertial navigation experiments lasting 4000 s show that compared with the traditional method,the proposed method reduces the position error by about 390 m.展开更多
Diversifying crop rotation aims to balance production and ecological concerns.However,yield and water use efficiency(WUE)of crop in diversified rotation systems have not been well documented,especially under limited i...Diversifying crop rotation aims to balance production and ecological concerns.However,yield and water use efficiency(WUE)of crop in diversified rotation systems have not been well documented,especially under limited irrigation.Here,we conducted a 6-year experiment with five treatments:1)wheatmaize cropping system(WM),as control;2)WMME,spring maize→WM rotation;3)WMML,spring millet→WM rotation;4)WMMP,spring peanut→WM rotation;and 5)WMMS,spring soybean→WM rotation,to explore how diversified rotations affected yield and WUE of wheat.Results showed that approximately 60% higher precipitation during wheat growing season in Cycle 1(2015-2017)resulted in yield increases by 33.8%-55.7% compared to those in Cycle 2(2017-2019)and Cycle3(2019-2021).Grain yield and WUE of wheat were 16.7% and 9.6% higher in Cycle 1,81.5% and 86.8% higher in Cycle 2,and 56.1% and 78.7% higher in Cycle 3 on average in diversified rotations compared to those in WM,respectively.Further analysis revealed that spike number and aboveground biomass were the main contributors to the increments,which can be explained by the increased evapotranspiration during the middle-late wheat growth stages(e.g.,regreening,jointing,and anthesis)in diversified rotations.In general,diversified rotations enhanced synchronization of soil water supply with crop water demand by affecting the spatiotemporal dynamics of soil moisture under varied precipitation conditions,thereby increasing yield and WUE of wheat.Hence,diversified spring crops→WM rotations offer a sustainable and efficient strategy for enhancing wheat production and water conservation in dry areas.展开更多
Self-propulsion of a deformable ellipse immersed in an unbounded inviscid fluid is discussed in order to explore the effect of the deformation and controlled rotation of the body coupled with the shift of its internal...Self-propulsion of a deformable ellipse immersed in an unbounded inviscid fluid is discussed in order to explore the effect of the deformation and controlled rotation of the body coupled with the shift of its internal mass on the self-motion.The ellipse is capable of symmetric deformation along the two orthogonal axes and endowed with some self-regulation ability via the shift and rotation of its internal mass.From the model,the appropriate velocity potential induced by the motion of the ellipse with the deformation in an otherwise undisturbed fluid is derived,and then the equations of motion are obtained by means of integrals of the unsteady fluid pressure.The equations are utilized to explore self-translational behaviors of the ellipse through the cyclic shift of its internal mass and deformation coupled with its own controllable rotation.Analysis and numerical results show that the ellipse can break the kinematic time-reversal symmetry by properly adjusting its own rotation to coordinate with the deformation and the cyclic shift of the inner mass to meet a forward criterion,and push itself to move persistently forward without a regression at zero system momentum,exhibiting some basic serpentine movements according as the ellipse performs complete revolutions or oscillates between two extreme yaw angles during its self-motion.展开更多
Time-averaged thermal convection in a rotating horizontal annulus with a higher temperature at its inner boundary is studied.The centrifugal force plays a stabilizing role,while thermal convection is determined by the...Time-averaged thermal convection in a rotating horizontal annulus with a higher temperature at its inner boundary is studied.The centrifugal force plays a stabilizing role,while thermal convection is determined by the“thermovibrational mechanism”.Convective flow is excited due to oscillations of a non-isothermal rotating fluid.Thermal vibrational convectionmanifests in the form of two-dimensional vortices elongated along the axis of rotation,which develop in a threshold manner with an increase in the amplitude of fluid oscillations.The objective of the present study is to clarify the nature of another phenomenon,i.e.,three-dimensional convective vortices observed in the experiments both before the excitation of the convection described above and in the supercritical region.The experimental study of the oscillatory and the time-averaged flow fields by particle image velocimetry is accompanied by the theoretical research of inertial waves.It is found that three-dimensional fluid flows owe their origin to inertial waves.This is confirmed by a high degree of agreement between the experimental and theoretical results.Experiments with cavities of different lengths indicate that the vortices are clearly seen in cavities thatmeet the conditions of resonant excitation of inertial modes.Furthermore,the length of the cavity has no effect on heat transfer,which is explained by the comparatively low intensity of the wave-induced flows.The main contribution to heat transfer is due to vortices elongated along the axis of rotation.The novel results are of significant practical importance in various fields.展开更多
Winter planting green manures in southern China effectively improve soil properties and rice production through microbial community construction.However,the effects of soil communities of arbuscular mycorrhizal fungi(...Winter planting green manures in southern China effectively improve soil properties and rice production through microbial community construction.However,the effects of soil communities of arbuscular mycorrhizal fungi(AMF)from different winter planting green manures on the soil properties and post-cropping rice production remain unclear.In this study,the soil AMF communities of three common winter planting patterns in southern China,winter fallow,winter ryegrass(Lolium multiflorum L.),and winter Chinese milk vetch(Astragalus sinicus L.),were explored and their effects on post-cropping rice production were investigated.Compared with winter fallow,the winter ryegrass and winter Chinese milk vetch patterns could alleviate soil acidification,significantly increase soil AMF spore density,and improve the soil AMF community structure.Based on sterilized soil,rice production indicators such as thousandseed weight,theoretical yield,and the grain amylose and total sugar contents of rice inoculated with AMF spores from winter Chinese milk vetch soil were 6.68–53.57%higher than those without AMF inoculation.Rice panicle weight,seed setting rate,and theoretical yield were 15.38–22.71%higher in the treatment with AMF spores from winter ryegrass soil than in the treatments with no AMF inoculation.In addition,the protein,amylose,and total sugar contents of rice grains were 14.92,104.82,and 802.23 mg kg^(–1),respectively,which were 31.31,14.25 and 34.47%higher than those without AMF inoculation.The AMF community dominated by Glomus and Acaulospora in winter Chinese milk vetch had a more positive effect on the improvement of rice yield,while the AMF community dominated by Glomus in winter ryegrass soil was more conducive to rice quality improvement.These findings have revealed the critical role of AMF communities from green manure in rice production,which lays the theoretical basis for a promising strategy to promote the sustainable development of southern winter agriculture.展开更多
The dynamic processes responsible for the movement of tropical cyclone Khanun(2017)were studied by analyzing data from the mesoscale WRF model simulation.The simulated motion was induced by the ventilation flow of bot...The dynamic processes responsible for the movement of tropical cyclone Khanun(2017)were studied by analyzing data from the mesoscale WRF model simulation.The simulated motion was induced by the ventilation flow of both the environmentaland asymmetric rotational wind averaged over an area within a radius of 200 km from Khanun's center.The results revealed that during Khanun's intensification period,environmental wind barely changed,whereas the speed and direction of asymmetric rotational wind exhibited significant changes as Khanun's southwestward movement switched to a northwestward movement.The streamfunction analysis revealed that the change in the direction of movement was consistent with the ventilation flow of asymmetric rotational wind across Khanun's center associated with the asymmetric circulation rotation.The cyclonic circulation center rotated counterclockwise,moving from the northeast to the north before and during the rapid intensification period,and exhibited wandering behavior during this period.The rotational rate of asymmetric circulation was quantitatively estimated using the formulation based on the budget of asymmetric rotational kinetic energy.This calculation revealed that the rapid counterclockwise rotation resulted from the conversion of environmental to asymmetric rotational kinetic energy and was related to the horizontal advection of environmental tangential flow.The rotation of the asymmetric circulation displayed a wandering behavior when the dissipation term became significant.The dissipation term plus the conversion from symmetric to asymmetric rotational kinetic energy associated with the advection of symmetric tangential wind by the environmental radial wind led to a slow clockwise rotation of the asymmetric cyclonic center to the north.展开更多
基金National Natural Science Foundation of China(2022YFF0609300)。
文摘The deformation behavior of GH4169 superalloy under room-temperature uniaxial tension was investigated through synchronized mesoscopic digital image correlation(DIC)and electron backscatter diffraction(EBSD)in-situ characterization techniques.Results show that in the field of grain deflection dynamics,through quantitative analysis using the independently developed M-DIC software,during uniaxial tension with significant bidirectional rotation along the tensile axis and the stress level of 1100 MPa,oscillatory rotation of±0.6°can be obtained,and microvoids are generated at the grain boundaries with 45°to the stress axis.EBSD crystallographic analysis demonstrates the load-dependent slip system evolution:in the initial stage,the soft-oriented systems with high Schmid factor(>0.4)is activated and then transformed into hard-oriented systems during cross-slip,generating parallel slip bands and dislocation pile-ups at grain boundaries.During the uniaxial tensile process,the characteristic of strain energy accumulation is observed,which follows a two-stage accumulation pattern:initial grain boundary localization(Stage I)and intragranular propagation(Stage II).Ultimately,the intergranular cracks are initiated at triple junctions,and the twin boundaries exhibit superior mechanical stability compared with the large-angle grain boundaries.Deformation texture characteristics indicate the copper-type components,including C{112}<111¯>,S{123}<634¯>,and B{110}<11¯0>.The complete deformation sequence is as follows:cross-slip of soft-oriented slip systems→initiation of dislocation slip→strain partitioning through grain rotation→intergranular stress concentration→damage dominated by boundary cracking.The cross-scale deformation mechanism revealed in this study provides critical guidance for the crystal boundary engineering to optimize nickel-based superalloys.
文摘Objectives:One of the most notable challenges in endoscopic procedures is maintaining correct orientation.Mental rotation exercise(MRE)has been suggested as a potential aid for improving orientation.However,there is a lack of research on designing MREs with varying difficultylevels for training purposes.Furthermore,few studies provide solid evidence linking MRE difficultylevels with cognitive load measurements.This study aims to address this gap by investigating the correlation between the MRE difficultylevels and participants’cognitive load,as measured by pupil dilation.Method:We recruited 33 participants to perform MREs on a computer equipped with a screen-mounted eye-tracker.The test consisted of 15 MREs,with the first10 relatively easy(traditional cube)and the next 5 more complex(invented molecule).The participants’eye movements during MREs were recorded.The participants’MRE scores and pupil dilation were obtained and compared between two MRE difficultylevels.Results:The participants who performed traditional cube MREs achieved significantlybetter MRE scores(0.77±0.11 vs.0.58±0.03,p<0.001)and lower pupil dilation(0.27±0.04 pixels vs.0.47±0.09 pixels,p<0.001)than did those who performed the invented molecule MREs.Moreover,there were significant negative correlations(r=0.62,p=0.015)between pupil dilation and MRE scores.Conclusions:The results revealed a significantnegative correlation between MRE scores and pupil dilation.The more challenging MRE questions led to worse MRE scores but increased pupil dilation.The MRE difficultylevels can be evaluated not only by the degrees or dimensions with which the objects were rotated but also by the participants’MRE scores and pupil dilation.The results of this study provide a basis for training orientation skills in endoscopy using MREs.By incorporating MREs with varying difficultylevels,customized training programs can be developed to enhance camera navigation in endoscopic and laparoscopic procedures.
基金Project supported by the National Natural Science Foundation of China(No.12472062)。
文摘In this paper,a theoretical model is established for locally resonant plates with general resonators,and the corresponding governing equation is derived.The model provides a mathematical demonstration of the locally resonant effect,which contains two parts:the first part is induced by translation coupling,and the second part is induced by rotation coupling.The second part cannot be reflected by most existing theoretical models.The analytical solutions of the dynamic response are compared with the direct numerical simulation(DNS)results for two locally resonant plates with different resonator types,thereby validating the general applicability of the present model.The rotation coupling effect leads to the frequency-dependent effective rotational inertia density and anisotropic dispersion relation of the locally resonant plate,as well as the enhancement of the structural vibration suppression ability.
基金supported in part by the National Natural Science Foundation of China under Grant 62071405the National Natural Science Foundation of China under Grant 12175189.
文摘The accurate segmentation of deep gray matter nuclei is critical for neuropathological research,disease diagnosis and treatment.Existing methods employ the supervised learning training approach,which requires large labeled datasets.It is challenging and time-consuming to obtain such datasets for medical image analysis.In addition,these methods based on convolutional neural networks(CNNs)only achieve suboptimal performance due to the locality of convolutional operations.Vision Transformers(ViTs)efficiently model long-range dependencies and thus have the potentiality to outperform these methods in segmentation tasks.To address these issues,we propose a novel hybrid network based on self-supervised pre-training for deep gray matter nuclei segmentation.Specifically,we present a CNN-Transformer hybrid network(CTNet),whose encoder consists of 3D CNN and ViT to learn local spatial-detailed features and global semantic information.A self-supervised learning(SSL)approach that integrates rotation prediction and masked feature reconstruction is proposed to pre-train the CTNet,enabling the model to learn valuable visual representations from unlabeled data.We evaluate the effectiveness of our method on 3T and 7T human brain MRI datasets.The results demonstrate that our CTNet achieves better performance than other comparison models and our pre-training strategy outperforms other advanced self-supervised methods.When the training set has only one sample,our pre-trained CTNet enhances segmentation performance,showing an 8.4%improvement in Dice similarity coefficient(DSC)compared to the randomly initialized CTNet.
基金part of the project on soil and water management approved and supported by the Department of Agronomy,Nasarawa State University,Keffi(NSUK),Nigeria。
文摘African drylands occupied 19.6 million km~2(46%of the total global area)and 525 million people.Soil erosion models are useful for assessing the impact of soil erosion in the dryland areas.This review provides an assessment of soil erosion/deposition models and soil conservation practices,which are supportive for mitigating the impact of soil erosion and maintaining soil health and soil functional services for food security in African drylands.The theories of soil erosion models and soil conservation practices provide advanced ways to understand the detailed impact of soil erosion and management solutions.The paper reviews a set of useful soil erosion models and traditional conservation practices,which can control soil erosion and enhance dryland farming systems in Africa.Soil erosion models are classified into three categories:empirical,conceptual,and physical.Soil conservation practices include reduced tillage,advanced cover crops,mechanical structures(barriers made of stones/gravel/vegetation),advanced mechanical roller-crimper technique,mixed cropping,intercropping,crop rotation systems,terracing techniques,and land modification techniques.These conservation practices are effective in controlling soil erosion,reducing soil damage,improving soil health and quality,enhancing soil fertility,and ensuring food security.The existing assessment suggests that understanding the theories of soil erosion models and soil conservation practices is a first step towards addressing soil erosion problems in African drylands.
基金financially supported by the National Natural Science Foundation of China Young Student Basic Research Program(for Ph.D.students)(No.525B2069)the Fundamental Research Funds for the Central Universities,China(No.HIT.DZJJ.2025005)the National Key Laboratory of Precision Welding&Joining of Materials and Structures Research Project,China(No.24-Z-09)。
文摘The effects ofγ-ray and electron irradiation on the microstructural evolution and mechanical properties of SnPb eutectic solder joints were investigated.Following electron irradiation,the SnO_(2)phase induced byγ-ray irradiation transformed intoβ-Sn,and the dislocation density in theβ-Sn crystal decreased.Moreover,numerous point defect clusters formed in theβ-Sn crystal,some of which transformed into an amorphous phase,increasing the amorphous layer thickness.Meanwhile,electron irradiation likewise resulted in rotation of the(220)plane ofβ-Sn nanograins and reduction of SnO_(2)in theβ-Sn crystal.Additionally,upon exposure toγ-ray and electron irradiation,the average shear strength of the solder balls was initially increased by 10.10%,followed by a decrease of 3.53%and 4.77%,respectively.The plasticity and the dimple count on the fracture surfaces of the solder joint initially decreased but subsequently increased.
基金supported by the National Natural Science Foundation of China(No.52061135101 and 52001078)the German Research Foundation(DFG,No.448318292)+3 种基金the Technology Innovation Guidance Special Foundation of Shaanxi Province(No.2023GXLH-085)the Fundamental Research Funds for the Central Universities(No.D5000240161)the Project of Key areas of innovation team in Shaanxi Province(No.2024RS-CXTD-20)The author Yingchun Xie thanks the support from the National Key R&D Program(No.2023YFE0108000).
文摘1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-sized particles(5-50μm)to fabricate coatings[1-3].CS has been extensively used in a variety of coating applications,such as aerospace,automotive,energy,medical,marine,and others,to provide protection against high temperatures,corrosion,erosion,oxidation,and chemicals[4,5].Nowadays,the technical interest in CS is twofold:(i)as a repair process for damaged components,and(ii)as a solid-state additive manufacturing process.Compared to other fusion-based additive manufacturing(AM)technologies,Cold Spray Additive Manufacturing(CSAM)is a new member of the AM family that can enable the fabrication of deposits without undergoing melting.The chemical composition has been largely preserved from the powder to the deposit due to the minimal oxidation.The significant advantages of CSAM over other additive manufacturing processes include a high production rate,unlimited deposition size,high flexibility,and suitability for repairing damaged parts.
基金supported by the National Natural Science Foundation of China(31971855)the Agricultural Science and Technology Innovation Project of the Chinese Academy of Agricultural Science(CAAS-ASTIP-2021-OCRI)+2 种基金the Hubei Provincial Natural Science Foundation of China(2024AFB442)the Wuhan Knowledge Innovation Special Program(2023020201020400)the China Agriculture Research System(CARS-12)。
文摘Global food production faces enormous challenges in increasing yields while promoting environmental sustainability.A field experiments in the ecotone between the Yangtze River Basin and the HuangHuai-Hai Plain evaluated the effects of changing preceding crop rotation cycles(wheat and rapeseed)on long-term wheat-rice(W)and rapeseed-rice(R)rotation systems.A comprehensive evaluation of crop rotation systems was conducted using life cycle assessment,considering productivity,economic benefits,carbon footprint(CF),and soil health.Compared with fallow-rice rotation(F),alternating rapeseed and wheat rotations increased equivalent yield by 60.4%-82.2%,reduced CF by 0.3%-5.7%,and improved soil health by 0.3%-47.5%.Additionally,adding rapeseed to rotations increased soil nutrient content and raised soil organic carbon stocks by 31.3%-40.5%.The 3R rotation(3-year rapeseed-rice and 1-year wheat-rice)boosted rice yield by 82.2%and annual economic benefits by 84.4%,offering an effective model for optimizing long-term R rotations.Similarly,the 2W rotation(2-year wheat-rice and 1-year rapeseed rice)enhanced rice yield by 70.0% and annual economic benefits by 65.9%,providing a successful example for optimizing long-term W rotations.The 3R rapeseed-based rotation and the 2W wheatbased rotation demonstrated good environmental sustainability.These rotation systems have broad potential in sustainable intensive farming,especially in China and similar regions.
基金Financial supports from the National Natural Science Foundation of China(Nos.52171116,U22A20109,52334010 and T2325013)are greatly acknowledgedPartial financial support came from The Program for the Central University Youth Innovation Team,and the Fundamental Research Funds for the Central Universities,JLU.
文摘Dislocations and disclinations are fundamental topological defects within crystals,which determine the mechanical properties of metals and alloys.Despite their important roles in multiple physical mechanisms,e.g.,dynamic recovery and grain boundary mediated plasticity,the intrinsic coupling and correlation between disclinations and dislocations,and their impacts on the deformation behavior of metallic materials still remain obscure,partially due to the lack of a theoretical tool to capture the rotational nature of disclinations.By using a Lie-algebra-based theoretical framework,we obtain a general equation to quantify the intrinsic coupling of disclinations and dislocations.Through quasi in-situ electron backscatter diffraction characterizations and disclination/dislocation density analyses in Mg alloys,the generation,coevolution and reactions of disclinations and dislocations during dynamic recovery and superplastic deformation have been quantitatively analyzed.It has been demonstrated that the obtained governing equation can capture multiple physical processes associated with mechanical deformation of metals,e.g.,grain rotation and grain boundary migration,at both room temperature and high temperature.By establishing the disclination-dislocation coupling equation within a Lie algebra description,our work provides new insights for exploring the coevolution and reaction of disclinations/dislocations,with profound implications for elucidating the microstructure-property relationship and underlying deformation mechanisms in metallic materials.
基金supported by the Research Fund of Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology(No.2020B1212030010)。
文摘This paper demonstrated the generation of multi-wavelength bound state noise-like pulse(BNLP)in a dispersion-managed composite-filtered fiber laser consisting of nonlinear polarization rotation(NPR)and loop.In the case of BNLP,the generation is caused by the interaction between two noise-like pulses(NLPs)induced by the comb-filtering effect,and bound state level can be artificially controlled in the researches.Our work provides a new method for generating low-coherence pulses and establishes a research idea for the study of the comb-filtering effects.
文摘Internal rotation of conjugated organic backbone seriously impaired room temperature phosphorescence(RTP),leading to rare realization of ultra-long afterglows with RTP lifetimes over 2 s in non-bibulous polymers.Herein,N-(bromophenyl)carbazoles are cyclized to lock up phenyl-carbazol internal rotation in advance and the fused nitrogen hetero-cyclic compounds are doped into poly(methyl methacrylate)(PMMA).The results show that locking up the molecular internal rotation can achieve ultra-long RTP polymers with lifetimes over 2 s,in contrast,the unlocked molecules hardly emit RTP in PMMA.The high-lying triplet excitons can transfer the energy to low-lying organic fluorescent dyes,and the persistent multicolor afterglows including white emission can be readily modulated.This work discloses an effective and extendable dopant molecular strategy for developing high-performance ultra-long organic RTP polymers.
基金funded by the Ministry of Education of the Russian Federation within the framework of a state assignment,number 1023032300071-6-2.3.1.
文摘Thermal vibrational convection(TVC)refers to the time-averaged convection of a non-isothermal fluid subjected to oscillating force fields.It serves as an effective mechanism for heat transfer control,particularly under microgravity conditions.A key challenge in this field is understanding the effect of rotation on TVC,as fluid oscillations in rotating systems exhibit unique and specific characteristics.In this study,we examine TVC in a vertical flat layer with boundaries at different temperatures,rotating around a horizontal axis.The distinctive feature of this study is that the fluid oscillations within the cavity are not induced by vibrations of the cavity itself,but rather by the gravity field,giving them a tidal nature.Our findings reveal that inertial waves generated in the rotating layer qualitatively alter the TVC structure,producing time-averaged flows in the form of toroidal vortices.Experimental investigations of the structure of oscillatory and time-averaged flows,conducted using Particle Image Velocimetry(PIV)for flow velocity visualization,are complemented by theoretical calculations of inertial modes in a cavity with this geometry.To the best of our knowledge,this study represents the first of its kind.The agreement between experimental results and theoretical predictions confirms that the formation of convective structures in the form of toroidal vortices is driven by inertial waves induced by the gravity field.A decrease in the rotational velocity leads to a transformation of the convective structures,shifting from toroidal vortices of inertial-wave origin to classical cellular TVC.We present dimensionless parameters that define the excitation thresholds for both cellular convection and toroidal structures.
基金funded by the Ministry of Education of the Russian Federation within the framework of a state assignment,number 1023032300071-6-2.3.1.
文摘The dynamics of fluid and non-buoyant particles in a librating horizontal annulus is studied experimentally.In the absence of librations,the granular material forms a cylindrical layer near the outer boundary of the annulus and undergoes rigid-body rotation with the fluid and the annulus.It is demonstrated that the librational liquefaction of the granular material results in pattern formation.This self-organization process stems from the excitation of inertial modes induced by the oscillatory motion of liquefied granular material under the influence of the gravitational force.The inertial wave induces vortical fluid flow which entrains particles from rest and forms eroded areas that are equidistant from each other along the axis of rotation.Theoretical analysis and experiments demonstrate that a liquefied layer of granular material oscillates with a radian frequency equal to the angular velocity of the annulus and interacts with the inertial wave it excites.The new phenomenon of libration-induced pattern formation is of practical interest as it can be used to control multiphase flows and mass transfer in rotating containers in a variety of industrial processes.
基金supported by the National Key Research and Development Program of China under Grant No.2022YFA1405000Innovation Program for Quantum Science and Technology under Grant No.2024ZD0300101the National Natural Science Foundation of China under Grant Nos.12274212,12174184,12347102。
文摘Active matter exhibits collective motions at various scales.Geometric confinement has been identified as an effective way to control and manipulate active fluids,with much attention given to external factors.However,the impact of the inherent properties of active particles on collective motion under confined conditions remains elusive.Here,we use a highly tunable active nematics model to study active systems under confinement,focusing on the effect of the self-driven speed of active particles.We identify three distinct states characterized by unique particle and flow fields within confined active nematic systems,among which circular rotation emerges as a collective motion involving rotational movement in both particle and flow fields.The theoretical phase diagram shows that increasing the self-driven speed of active particles significantly enhances the region of the circular rotation state and improves its stability.Our results provide insights into the formation of high quality vortices in confined active nematic systems.
基金supported by the National Natural Science Foundation of China(42276199).
文摘In order to get rid of the dependence on high-precision centrifuges in accelerometer nonlinear coefficients calibration,this paper proposes a system-level calibration method for field condition.Firstly,a 42-dimension Kalman filter is constructed to reduce impact brought by turntable.Then,a biaxial rotation path is designed based on the accelerometer output model,including orthogonal 22 positions and tilt 12 positions,which enhances gravity excitation on nonlinear coefficients of accelerometer.Finally,sampling is carried out for calibration and further experiments.The results of static inertial navigation experiments lasting 4000 s show that compared with the traditional method,the proposed method reduces the position error by about 390 m.
基金supported by the National Natural Science Foundation of China(32172125 and U21A20218)。
文摘Diversifying crop rotation aims to balance production and ecological concerns.However,yield and water use efficiency(WUE)of crop in diversified rotation systems have not been well documented,especially under limited irrigation.Here,we conducted a 6-year experiment with five treatments:1)wheatmaize cropping system(WM),as control;2)WMME,spring maize→WM rotation;3)WMML,spring millet→WM rotation;4)WMMP,spring peanut→WM rotation;and 5)WMMS,spring soybean→WM rotation,to explore how diversified rotations affected yield and WUE of wheat.Results showed that approximately 60% higher precipitation during wheat growing season in Cycle 1(2015-2017)resulted in yield increases by 33.8%-55.7% compared to those in Cycle 2(2017-2019)and Cycle3(2019-2021).Grain yield and WUE of wheat were 16.7% and 9.6% higher in Cycle 1,81.5% and 86.8% higher in Cycle 2,and 56.1% and 78.7% higher in Cycle 3 on average in diversified rotations compared to those in WM,respectively.Further analysis revealed that spike number and aboveground biomass were the main contributors to the increments,which can be explained by the increased evapotranspiration during the middle-late wheat growth stages(e.g.,regreening,jointing,and anthesis)in diversified rotations.In general,diversified rotations enhanced synchronization of soil water supply with crop water demand by affecting the spatiotemporal dynamics of soil moisture under varied precipitation conditions,thereby increasing yield and WUE of wheat.Hence,diversified spring crops→WM rotations offer a sustainable and efficient strategy for enhancing wheat production and water conservation in dry areas.
基金supported by the National Natural Science Foundation of China(Grant No.11672182).
文摘Self-propulsion of a deformable ellipse immersed in an unbounded inviscid fluid is discussed in order to explore the effect of the deformation and controlled rotation of the body coupled with the shift of its internal mass on the self-motion.The ellipse is capable of symmetric deformation along the two orthogonal axes and endowed with some self-regulation ability via the shift and rotation of its internal mass.From the model,the appropriate velocity potential induced by the motion of the ellipse with the deformation in an otherwise undisturbed fluid is derived,and then the equations of motion are obtained by means of integrals of the unsteady fluid pressure.The equations are utilized to explore self-translational behaviors of the ellipse through the cyclic shift of its internal mass and deformation coupled with its own controllable rotation.Analysis and numerical results show that the ellipse can break the kinematic time-reversal symmetry by properly adjusting its own rotation to coordinate with the deformation and the cyclic shift of the inner mass to meet a forward criterion,and push itself to move persistently forward without a regression at zero system momentum,exhibiting some basic serpentine movements according as the ellipse performs complete revolutions or oscillates between two extreme yaw angles during its self-motion.
基金funded by the Ministry of Education of the Russian Federation within the framework of a state assignment,number 1023032300071-6-2.3.1.
文摘Time-averaged thermal convection in a rotating horizontal annulus with a higher temperature at its inner boundary is studied.The centrifugal force plays a stabilizing role,while thermal convection is determined by the“thermovibrational mechanism”.Convective flow is excited due to oscillations of a non-isothermal rotating fluid.Thermal vibrational convectionmanifests in the form of two-dimensional vortices elongated along the axis of rotation,which develop in a threshold manner with an increase in the amplitude of fluid oscillations.The objective of the present study is to clarify the nature of another phenomenon,i.e.,three-dimensional convective vortices observed in the experiments both before the excitation of the convection described above and in the supercritical region.The experimental study of the oscillatory and the time-averaged flow fields by particle image velocimetry is accompanied by the theoretical research of inertial waves.It is found that three-dimensional fluid flows owe their origin to inertial waves.This is confirmed by a high degree of agreement between the experimental and theoretical results.Experiments with cavities of different lengths indicate that the vortices are clearly seen in cavities thatmeet the conditions of resonant excitation of inertial modes.Furthermore,the length of the cavity has no effect on heat transfer,which is explained by the comparatively low intensity of the wave-induced flows.The main contribution to heat transfer is due to vortices elongated along the axis of rotation.The novel results are of significant practical importance in various fields.
基金supported by the National Natural Science Foundation of China(32171683)the Shenzhen Science and Technology Program,China(JCYJ20220530145606015)+4 种基金the Agricultural and Social Development Project of Guangzhou Municipal Science and Technology Bureau,China(202206010058)the Special Fund for Agro-scientific Research in the Public Interest of China(201503122)the Natural Science Foundation of Guangdong Province,China(2020A1515010494)the Yangfan Innovative&Entrepreneurial Research Team Project,China(2015YT02H032)the Zhang Hong-da Science Research Fund of Sun Yat-sen University,China。
文摘Winter planting green manures in southern China effectively improve soil properties and rice production through microbial community construction.However,the effects of soil communities of arbuscular mycorrhizal fungi(AMF)from different winter planting green manures on the soil properties and post-cropping rice production remain unclear.In this study,the soil AMF communities of three common winter planting patterns in southern China,winter fallow,winter ryegrass(Lolium multiflorum L.),and winter Chinese milk vetch(Astragalus sinicus L.),were explored and their effects on post-cropping rice production were investigated.Compared with winter fallow,the winter ryegrass and winter Chinese milk vetch patterns could alleviate soil acidification,significantly increase soil AMF spore density,and improve the soil AMF community structure.Based on sterilized soil,rice production indicators such as thousandseed weight,theoretical yield,and the grain amylose and total sugar contents of rice inoculated with AMF spores from winter Chinese milk vetch soil were 6.68–53.57%higher than those without AMF inoculation.Rice panicle weight,seed setting rate,and theoretical yield were 15.38–22.71%higher in the treatment with AMF spores from winter ryegrass soil than in the treatments with no AMF inoculation.In addition,the protein,amylose,and total sugar contents of rice grains were 14.92,104.82,and 802.23 mg kg^(–1),respectively,which were 31.31,14.25 and 34.47%higher than those without AMF inoculation.The AMF community dominated by Glomus and Acaulospora in winter Chinese milk vetch had a more positive effect on the improvement of rice yield,while the AMF community dominated by Glomus in winter ryegrass soil was more conducive to rice quality improvement.These findings have revealed the critical role of AMF communities from green manure in rice production,which lays the theoretical basis for a promising strategy to promote the sustainable development of southern winter agriculture.
基金supported by the National Natural Science Foundation of China(Grant No.41930967)。
文摘The dynamic processes responsible for the movement of tropical cyclone Khanun(2017)were studied by analyzing data from the mesoscale WRF model simulation.The simulated motion was induced by the ventilation flow of both the environmentaland asymmetric rotational wind averaged over an area within a radius of 200 km from Khanun's center.The results revealed that during Khanun's intensification period,environmental wind barely changed,whereas the speed and direction of asymmetric rotational wind exhibited significant changes as Khanun's southwestward movement switched to a northwestward movement.The streamfunction analysis revealed that the change in the direction of movement was consistent with the ventilation flow of asymmetric rotational wind across Khanun's center associated with the asymmetric circulation rotation.The cyclonic circulation center rotated counterclockwise,moving from the northeast to the north before and during the rapid intensification period,and exhibited wandering behavior during this period.The rotational rate of asymmetric circulation was quantitatively estimated using the formulation based on the budget of asymmetric rotational kinetic energy.This calculation revealed that the rapid counterclockwise rotation resulted from the conversion of environmental to asymmetric rotational kinetic energy and was related to the horizontal advection of environmental tangential flow.The rotation of the asymmetric circulation displayed a wandering behavior when the dissipation term became significant.The dissipation term plus the conversion from symmetric to asymmetric rotational kinetic energy associated with the advection of symmetric tangential wind by the environmental radial wind led to a slow clockwise rotation of the asymmetric cyclonic center to the north.
