In order to solve the so-called ＂bull-eye＂ problem caused by using a simple bilinear interpolation as an observational mapping operator in the cost function in the multigrid three-dimensional variational （3DVAR） d...In order to solve the so-called ＂bull-eye＂ problem caused by using a simple bilinear interpolation as an observational mapping operator in the cost function in the multigrid three-dimensional variational （3DVAR） data assimilation scheme, a smoothing term, equivalent to a penalty term, is introduced into the cost function to serve as a means of troubleshooting. A theoretical analysis is first performed to figure out what on earth results in the issue of ＂bull-eye＂, and then the meaning of such smoothing term is elucidated and the uniqueness of solution of the multigrid 3DVAR with the smoothing term added is discussed through the theoretical deduction for one-dimensional （1D） case, and two idealized data assimilation experiments （one- and two-dimensional （2D） cases）. By exploring the relationship between the smoothing term and the recursive filter theoretically and practically, it is revealed why satisfied analysis results can be achieved by using such proposed solution for the issue of the multigrid 3DVAR.展开更多
This work addresses the problem of estimating the states of nonlinear dynamic systems with sparse observations.We present a hybrid three-dimensional variation（3DVar） and particle piltering（PF） method,which combine...This work addresses the problem of estimating the states of nonlinear dynamic systems with sparse observations.We present a hybrid three-dimensional variation（3DVar） and particle piltering（PF） method,which combines the advantages of 3DVar and particle-based filters.By minimizing the cost function,this approach will produce a better proposal distribution of the state.Afterwards the stochastic resampling step in standard PF can be avoided through a deterministic scheme.The simulation results show that the performance of the new method is superior to the traditional ensemble Kalman filtering（EnKF） and the standard PF,especially in highly nonlinear systems.展开更多
In order to improve the efficiency of the Ocean Variational Assimilation System （OVALS）, which has been widely used in various applications, an improved OVALS （OVALS2） is developed based on the recursive filter ...In order to improve the efficiency of the Ocean Variational Assimilation System （OVALS）, which has been widely used in various applications, an improved OVALS （OVALS2） is developed based on the recursive filter （RF） algorithm. The first advantage of OVALS2 is that memory storage can be substantially reduced in practice because it implicitly computes the background error covariance matrix; the second advantage is that there is no inversion of the background error covariance by preconditioning the control variable. For comparing the effectiveness between OVALS2 and OVALS, a set of experiments was implemented by assimilating expendable bathythermograph （XBT） and ARGO data into the Tropical Pacific circulation model. The results show that the efficiency of OVALS2 is much higher than that of OVALS. The computational time and the computer storage in the assimilation process were reduced by 83% and 77%, respectively. Additionally, the corresponding results produced by the RF are almost as good as those obtained by OVALS. These results prove that OVALS2 is suitable for operational numerical oceanic forecasting.展开更多
Oceanic dissolved oxygen(DO)concentration is crucial for assessing the status of marine ecosystems.Against the backdrop of global warming,DO shows a general decrease,posing a threat to the health of marine ecosystems....Oceanic dissolved oxygen(DO)concentration is crucial for assessing the status of marine ecosystems.Against the backdrop of global warming,DO shows a general decrease,posing a threat to the health of marine ecosystems.Therefore,there is an urgent need to develop advanced tools to characterize the spatio-temporal variations of three-dimensional(3D)DO.To address this challenge,this study introduces the Light Gradient Boosting Machine(Light-GBM),combining satellite remote sensing and reanalysis data with Biogeochemical Argo data to accurately reconstruct the 3D DO structure in the Mediterranean Sea from 2010 to 2022.Various environmental parameters are incorporated as inputs,including spatiotemporal features,meteorological characteristics,and ocean color properties.The LightGBM model demonstrates excellent performance on the testing dataset with R^(2) of 0.958.The modeled DO agrees better with in-situ measurements than products from numerical models.Using the Shapley Additive exPlanations method,the contributions of input features are assessed.Sea surface temperatures provide a correlation with DO at the sea surface,while spatial coordinates supplement the view of the ocean interior.Based on the reconstructed 3D DO structure,we identify an oxygen minimum zone in the western Mediterranean that expands continuously,reaching depths of approximately 300–800 m.The western Mediterranean exhibits a significant declining trend.This study enhances marine environmental evidence by proposing a precise and cost-effective approach for reconstructing 3D DO,thereby offering insights into the dynamics of DO variations under changing climatic conditions.展开更多
Satellite altimetry missions at high latitude have opened new avenues for understanding the changes occurring over the ice-covered region.By incorporating Arctic satellite remote sensing data-including sea surface tem...Satellite altimetry missions at high latitude have opened new avenues for understanding the changes occurring over the ice-covered region.By incorporating Arctic satellite remote sensing data-including sea surface temperature(SST),sea surface height anomaly(SSHA),and sea surface salinity(SSS).This study employs a variational method to reconstruct the three-dimensional thermohaline structure of the Arctic Ocean.Compared to the Regional Arctic Reanalysis(RARE),the reconstruction well captures both the horizontal and vertical temperature and salinity structures in the Arctic.It demonstrates superior skill over RARE,when compared with Argo profiles and Ice-Tethered Profiler(ITP)observations.The reconstruction is particularly effective in ice-covered regions,where it more accurately captures the transition from Pacific water to Atlantic water compared to RARE.These findings underscore the potential of applying Arctic satellite data to reconstruct vertical thermohaline structures in the Arctic,particularly in areas due to lack of the subsurface observation reanalysis data exhibit significant biases.As Arctic satellite observations continue to advance,the applications of this method are becoming increasingly promising,which is useful for monitoring the ice-covered region environment and can be applied to oceanographic research.展开更多
A large number of observational analyses have shown that lightning data can be used to indicate areas of deep convection. It is important to assimilate observed lightning data into numerical models, so that more small...A large number of observational analyses have shown that lightning data can be used to indicate areas of deep convection. It is important to assimilate observed lightning data into numerical models, so that more small-scale information can be incorporated to improve the quality of the initial condition and the subsequent forecasts. In this study, the empirical relationship between flash rate, water vapor mixing ratio, and graupel mixing ratio was used to adjust the model relative humidity, which was then assimilated by using the three-dimensional variational data assimilation system of the Weather Research and Forecasting model in cycling mode at 10-min intervals. To find the appropriate assimilation time-window length that yielded significant improvement in both the initial conditions and subsequent forecasts, four experiments with different assimilation time-window lengths were conducted for a squall line case that occurred on 10 July 2007 in North China. It was found that 60 min was the appropriate assimilation time-window length for this case, and longer assimilation window length was unnecessary since no further improvement was present. Forecasts of 1-h accumulated precipitation during the assimilation period and the subsequent 3-h accumulated precipitation were significantly improved compared with the control experiment without lightning data assimilation. The simulated reflectivity was optimal after 30 min of the forecast, it remained optimal during the following 42 min, and the positive effect from lightning data assimilation began to diminish after 72 min of the forecast. Overall,the improvement from lightning data assimilation can be maintained for about 3 h.展开更多
Under the strategic framework of rural revitalization and agricultural modernization, Xinjiashan Specialty Coffee Base, located in Zaotang Village, Lujiang Town, Longyang District, Baoshan City, has been proactively i...Under the strategic framework of rural revitalization and agricultural modernization, Xinjiashan Specialty Coffee Base, located in Zaotang Village, Lujiang Town, Longyang District, Baoshan City, has been proactively investigating innovative models for agricultural development. Through extensive communication and collaboration, this base has established close partnerships with research institutions including Kunming University of Science and Technology, Baoshan University, and Yunnan Academy of Agricultural Sciences, with a commitment to thoroughly exploring the potential for resource recycling and ecological complementarity. An innovative four-in-one three-dimensional integrated planting system incorporating "coffee, bananas, green manure, and bees" has been implemented. Concurrently, technological and digital management strategies have been comprehensively integrated to improve planting efficiency. Under this model, the proportion of specialty coffee attains 71%, and the per-unit yield is 17% greater than that of the conventional planting model. This approach not only substantially enhances economic returns but also promotes the integrated development of ecological and social benefits, offering a valuable practical example and experiential reference for the specialty and sustainable advancement of the coffee industry in comparable regions.展开更多
Aerial surveys are dynamic and continuous processes,and there are different height distributions of the ground in the measurement area,which leads to problems such as overlapping measurement areas and inaccurate altit...Aerial surveys are dynamic and continuous processes,and there are different height distributions of the ground in the measurement area,which leads to problems such as overlapping measurement areas and inaccurate altitude correction during the survey process.Commonly used terrain correction methods are based on the concept of finite elementization of ground surface radioactive sources,using GPS coordinates,radar altitude,and ground elevation distribution information from aerial surveys,combined with the sourceless efficiency calibration method to construct a response matrix,which is then inverted for surface nuclide content.However,most of the sourceless efficiency calibration methods used are numerical calculations that consider the body detector as a point detector and do not consider the changes in intrinsic detection efficiency under different incident directions of gamma rays.Therefore,when the altitude of the measurement area varies significantly or the flight altitude of the aerial survey is relatively low,such sourceless efficiency calibration method calculations tend to have a large bias,which affects the accuracy of the terrain correction.To address the above problems,this study employs a novel sourceless efficiency calibration method based on the Boolean operation of the ray deposition process and simplifies the traditional body source measurement model to a surface source measurement model to achieve fast and accurate efficiency calibration.Then,through the discretization of the measurement process,the static measurement process is superposed as equivalent to the dynamic measurement process,and the dynamic measurement response matrix is built and optimized based on the calibration method.Finally,the PSO-MLEM algorithm was used to solve the dynamic measurement response matrix to achieve dynamic terrain correction of aerial survey data.Analysis of the Baiyun'ebo test area revealed that,after applying dynamic terrain correction,the inverted anomalies in uranium(eU),thorium(eTh),and potassium(K)concentrations were closer to ground measurements(within 5.72%-30.79%)and exhibited clearer anomaly boundaries compared to traditional height-based corrections.However,owing to the inherent statistical fluctuations and characteristics of matrix inversion,higher measurement values tend to absorb lower ones,potentially enlarging the anomalous regions.Nevertheless,the highanomaly regions after inversion largely coincided with the ground truth validation,demonstrating that the proposed method can effectively correct airborne gamma spectrometry data.展开更多
Carbonyls play an important role in the atmospheric chemistry as the main precursor for reactive radicals and peroxyacetyl nitrate.However,little research has been conducted so far on the seasonal variations of carbon...Carbonyls play an important role in the atmospheric chemistry as the main precursor for reactive radicals and peroxyacetyl nitrate.However,little research has been conducted so far on the seasonal variations of carbonyls in China’s urban atmosphere.In this study,ambient carbonyls were 24-hourly observed in four seasons in Hangzhou,a mega-city in the Yangtze River Delta Region,China.The concentration of total carbonyls was the highest in summer(44.35μg/m^(3)),the second in winter(44.05μg/m^(3)),the third in spring(29.31μg/m^(3))and autumn(27.11μg/m^(3)).The most abundant species were found to be acetone in spring,summer,and winter,while formaldehyde in autumn.Rainfall can significantly reduce the concentrations of most ambient carbonyls,with the largest decrease observed in the wet precipitation events occurring in spring and summer,while acetone concentrations remained invariable due to its lower water solubility.Multiple linear regression analysis and carbonyls ratios indicated that anthropogenic emissions were the predominant sources of carbonyls,and atmospheric formaldehyde was mainly emitted from primary sources other than secondary sources.Vehicular exhaust was identified as the primary source of ambient carbonyls,particularly in winter,and its contribution reached 92.80%to formaldehyde.Additionally,photochemical reactions were closely associated with the secondary production of formaldehyde in summer.Carbonyls showed strong ozone formation potential in all four seasons.Based on the health risk assessment,the exposure to ambient carbonyls is harmful to outdoor pedestrians.The results could provide essential information and references for simulating regional air quality and analyzing ozone pollution,which is essential for improving air quality in the Yangtze River Delta region.展开更多
Replicating the chaotic characteristics inherent in nonlinear dynamical systems via machine learning(ML)is a key challenge in this rapidly advancing interdisciplinary field.In this work,we explore the potential of var...Replicating the chaotic characteristics inherent in nonlinear dynamical systems via machine learning(ML)is a key challenge in this rapidly advancing interdisciplinary field.In this work,we explore the potential of variational quantum circuits(VQC)for learning the stochastic properties of classical nonlinear dynamical systems.Specifically,we focus on the one-and two-dimensional logistic maps,which,while simple,remain under-explored in the context of learning dynamical characteristics.Our findings reveal that,even for such simple dynamical systems,accurately replicating longterm characteristics is hindered by a pronounced sensitivity to overfitting.While increasing the parameter complexity of the ML model typically enhances short-term prediction accuracy,it also leads to a degradation in the model’s ability to replicate long-term characteristics,primarily due to the detrimental effects of overfitting on generalization power.By comparing the VQC with two widely recognized classical ML techniques,which are long short-term memory(LSTM)networks for timeseries processing and reservoir computing,we demonstrate that VQC outperforms these methods in terms of replicating long-term characteristics.Our results suggest that for the ML of dynamics,it is demanded to develop more compact and efficient models(such as VQC)rather than more complicated and large-scale ones.展开更多
Plastome variation,including single spontaneous nucleotide substitutions and single insertions/deletions,is the major source of leaf variegation in plants.Additionally,one recent study has showed that a simple plastom...Plastome variation,including single spontaneous nucleotide substitutions and single insertions/deletions,is the major source of leaf variegation in plants.Additionally,one recent study has showed that a simple plastome structural variation,which is induced by one pair of small inverted repeats,can also result in leaf variegation.Here we show a complex plastome structural variation caused by intermolecular and intramolecular recombination across three pairs of small inverted repeats accounts for leaf variegation in a widely cultivated shrub Heptapleurum ellipticum(Araliaceae).This plastome structural variation contains two deletions and two duplications,resulting in dramatic expansion of IRs,substantial contraction of LSC and loss of 11 genes that essential for photosynthesis.Plastome heteroplasmy was detected in both green and albino sectors of variegated leaves.Relative to green sectors,albino sectors in the variegated leaves exhibit significantly reduced expression for the 11 genes lost in the mutated plastome as well as 26 other genes,but significantly increased expression for one gene related to translation apparatus.Optical and transmission electron microscopy observations showed that mesophyll cells of albino sectors possess plastids lacking grana lamellae,which likely carry the mutated plastome and contribute to albinism.In both sectors,the first layer of spongy mesophyll cells beneath the lower epidermis contains normal chloroplasts,suggesting periclinal division of the lower epidermis during development.Our study demonstrates that multiple small repeats can collectively mediate intra-and inter-molecular recombination in plastome and offers a new mechanism accounting for leaf variegation in plants.展开更多
Structural variation is an important source of genetic variation in wheat and have been important in the evolution of the wheat's genome.Few studies have examined the relationship between structural variations and...Structural variation is an important source of genetic variation in wheat and have been important in the evolution of the wheat's genome.Few studies have examined the relationship between structural variations and agronomy and drought tolerance.The present study identified structural chromosome variations(SCVs)in a doubled haploid(DH)population and backcross introgression lines(BC5F3)derived from Jinmai 47 and Jinmai 84 using fluorescence in situ hybridization(FISH).There are one simple translocation,10 present/absent variations(PAVs),and one copy number variation(CNV)between Jinmai 47 and Jinmai 84,which distributed in 10 chromosomes.Eight SCVs were associated with 15 agronomic traits.A PAV recombination occurred on chromosome 2A,which was associated with grain number per spike(GNS).The 1BL/1RS translocation and PAV.2D were associated with significant reductions in plant height,deriving from the effects on LI2-LI4,LI2-LI4 and UI,respectively respectively.PAV.2D was also contributed to an increase of 3.13%for GNS,1BL/1RS significantly increased spikelet number,grain length(GL),and grain thickness(GT).The effect of PAV.4A.1 on GL,PAV.6A on spike length(SL)and thousand-grain weight(TGW),PAV.6B on SL,GT and TGW were identified and verified.PAVs on chromosomes 2A,6A,1D,2D,and a CNV on chromosome 4B were associated with the drought tolerance coefficients.Additive and interaction effects among SCVs were observed.Many previously cloned key genes and yield-related QTL were found in polymorphic regions of PAV.2B,PAV.2D,and CNV.4B.Altogether,this study confirmed the genetic effect of SCVs on agronomy and drought tolerance,and identification of these SCVs will facilitate genetic improvement of wheat through marker-assisted selection.展开更多
Signal transduction in a cell is mostly mediated with biochemical reactions which are noisy and often modeled with chemical master equations or Langevin type of dynamics.Thus stochastic simulation constitutes a major ...Signal transduction in a cell is mostly mediated with biochemical reactions which are noisy and often modeled with chemical master equations or Langevin type of dynamics.Thus stochastic simulation constitutes a major part of computation in cell signaling.Nevertheless,the presence of a wide span of time scales or molecular numbers in various pathways may lead to trouble in computation efficiency or accuracy.To avoid this problem,the commonly employed variational method evolves the whole probability distribution and reduces the stochastic equations to deterministic ones of only a few parameters.However,the design of the left variational basis is essential for its successful application,especially to large networks.In this paper,we extend the conventional polynomial basis to the Fourier and further the Gaussian basis,much facilitating description of multi-peaked or localized non-Gaussian distributions and at the same time avoiding numerical instability and computational complexity frequently encountered with conventional basis.The extension here is demonstrated in several typical biochemical signaling networks and achieves similar accuracy as the benchmark Gillespie algorithm,but with much less running time,which seems to open new opportunities in the variational approach to efficient analysis of noisy dynamics.展开更多
Variational quantum algorithms(VQAs)with random structures have poor trainability due to the exponentially vanishing gradient as the circuit depth and the qubit number increase.This result leads to a general belief th...Variational quantum algorithms(VQAs)with random structures have poor trainability due to the exponentially vanishing gradient as the circuit depth and the qubit number increase.This result leads to a general belief that a deep circuit will not be feasible.In this work,we provide a viable solution to the vanishing gradient problem for deep VQAs with theoretical guarantees.Specifically,we prove that for quantum controlled-layer and quantum residual network(QResNet),architectures,the expectation of the gradient norm can be lower bounded by a value that is independent of the qubit number and the circuit depth.Our results follow from a careful analysis of the gradient behavior on parameter space consisting of rotation angles,as employed in almost all VQAs,instead of relying on impractical 2-design assumptions.We conduct several numerical experiments as verifications,where only our circuits are trainable and converge,while hardware-efficient and random circuits with similar number of parameters in comparison cannot converge.展开更多
Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and ...Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and reanalysis data(MERRA-2)from March 2007 to February 2015(eight years).The horizontal distribution reveals lower cirrus fraction values in the northern SCS and higher values in the southern region,with minima observed in March and April and maxima sequentially occurring in August(northern SCS,NSCS),September(middle SCS,MSCS),and December(southern SCS,SSCS).Vertically,the cirrus fraction peaks in summer and reaches its lowest levels in spring.Opaque cirrus dominates during summer in the NSCS and MSCS,comprising 53.6%and 55.9%,respectively,while the SSCS exhibits a higher frequency of opaque cirrus relative to other cloud types.Subvisible cirrus clouds have the lowest frequency year-round,whereas thin cirrus is most prominent in winter in the NSCS(46.3%)and in spring in the MSCS(45.3%).A case study from September 2021 further explores the influence of ice crystal habits on brightness temperature(BT)over the SCS.Simulations utilizing five ice crystal shapes from the ARTS DDA(Atmospheric Radiative Transfer Simulator Discrete Dipole Approximation)database and the RTTOV 12.4 radiative transfer model reveal that the 8-column-aggregate shape best represents BT in the NSCS and SSCS,while the large-block-aggregate shape performs better in the SSCS.展开更多
Understanding the spatial distributions and corresponding variation mechanisms of key soil nutrients in fragile karst ecosystems can assist in promoting sustainable development.However,due to the implementation of eco...Understanding the spatial distributions and corresponding variation mechanisms of key soil nutrients in fragile karst ecosystems can assist in promoting sustainable development.However,due to the implementation of ecological restoration initiatives such as land-use conversions,novel changes in the spatial characteristics of soil nutrients remain unknown.To address this gap,we explored nutrient variations and the drivers of the variation in the 0–15 cm topsoil layer using a regional-scale sampling method in a typical karst area in northwest Guangxi Zhuang Autonomous Region,Southwest China.Descriptive statistics,geostatistics,and spatial analysis were used to assess the soil nutrient variability.The results indicated that soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP),and total potassium(TK)concentrations showed moderate variations,with coefficients of variance being 0.60,0.60,0.71,and 0.72,respectively.Moreover,they demonstrated positive spatial autocorrelations,with global Moran's indices being 0.68,0.77,0.64,and 0.68,respectively.However,local Moran's index values were low,indicating large spatial variations in soil nutrients.The best-fitting semi-variogram models for SOC,TN,TP,and TK concentrations were spherical,Gaussian,exponential,and exponential,respectively.According to the classification criteria of the Second National Soil Census in China,SOC and TN concentrations were relatively sufficient,with the proportions of rich and very rich levels being up to 90.9 and 96.0%,respectively.TP concentration was in the mediumdeficient level,with the areas of medium and deficient levels accounting for 33.7 and 30.1%of the total,respectively.TK concentration was deficient,with the cumulative area of extremely deficient,very deficient,and deficient levels accounting for 87.6%of the total area.Consequently,the terrestrial ecosystems in the study area were more vulnerable to soil P and K than soil N deficiencies.Furthermore,variance partitioning analysis of the influencing factors showed that,except for the interactions,the single effect of other soil properties accounted more for soil nutrient variations than spatial and environmental variables.These results will aid in the future management of terrestrial ecosystems.展开更多
The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-bas...The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-based observations remain insufficient to clearly reflect the characteristics of the region’s lithospheric magnetism.In this study,we evaluate the lithospheric magnetism of the Tibetan Plateau by using a 3D surface spline model based on observations from>200 newly constructed repeat stations(portable stations)to determine the spatial distribution of plateau geomagnetism,as well as its correlation with the tectonic features of the region.We analyze the relationships between M≥5 earthquakes and lithospheric magnetic field variations on the Tibetan Plateau and identify regions susceptible to strong earthquakes.We compare the geomagnetic results with those from an enhanced magnetic model(EMM2015)developed by the NGDC and provide insights into improving lithospheric magnetic field calculations in the Tibetan Plateau region.Further research reveals that these magnetic anomalies exhibit distinct differences from the magnetic-seismic correlation mechanisms observed in other tectonic settings;here,they are governed primarily by the combined effects of compressional magnetism,thermal magnetism,and deep thermal stress.This study provides new evidence of geomagnetic anomalies on the Tibetan Plateau,interprets them physically,and demonstrates their potential for identifying seismic hazard zones on the Plateau.展开更多
According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing ...According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing differential equations are derived by the Hamilton's variational principle,and then solved by the iterative Separation-of-Variable(i SOV)method,which are applicable to arbitrary combinations of homogeneous Boundary Conditions(BCs).However,only the simply-support,clamped and cantilever panels are considered in this work for the sake of clarity.With the closed-form eigensolutions,the flutter frequency,flutter mode and flutter boundary are presented,and the effect of shear deformation and aerodynamic damping on flutter frequencies is investigated.Besides,the relation between panel energy and the work of aerodynamic load is discussed.The numerical comparisons reveal the following.(A)The flutter eigenvalues obtained by the present method are accurate,validated by the Finite Element Method(FEM)and the Galerkin method.(B)When the span-chord ratio is larger than 3,simplifying a 3D panel to 2D(two-dimensional)panel is reasonable and the relative differences of the flutter points predicted by the two models are less than one percent.(C)The reciprocal relationship between the mechanical energy of the panel and the work done by aerodynamic load is verified by using the present flutter eigenvalues and modes,further indicating the high accuracy of the present solutions.(D)The coupling of shear deformation and aerodynamic damping prevents frequency coalescing.展开更多
In this manuscript,we consider a non-autonomous dynamical system.Using the Carathéodory structure,we define a BS dimension on an arbitrary subset and obtain a Bowen’s equation that illustrates the relation of th...In this manuscript,we consider a non-autonomous dynamical system.Using the Carathéodory structure,we define a BS dimension on an arbitrary subset and obtain a Bowen’s equation that illustrates the relation of the BS dimension to the Pesin-Pitskel topological pressure given by Nazarian[24].Moreover,we establish a variational principle and an inverse variational principle for the BS dimension of non-autonomous dynamical systems.Finally,we also get an analogue of Billingsley’s theorem for the BS dimension of non-autonomous dynamical systems.展开更多
Structural variations(SVs≥50 bp)are a critical but underexplored source of genetic diversity in cattle,shaping traits vital for productivity,adaptability,and health.Advances in long-read sequencing,pangenome graph co...Structural variations(SVs≥50 bp)are a critical but underexplored source of genetic diversity in cattle,shaping traits vital for productivity,adaptability,and health.Advances in long-read sequencing,pangenome graph construction,and near-complete genome assemblies now allow accurate SV detection and genotyping.These innovations overcome the limitations of single-reference genomes,enabling the discovery of complex SVs,including nested and overlapping variants,and providing access to previously inaccessible genomic regions such as centromeres and telomeres.This review highlights the current landscape of cattle SV research,with emphasis on integrating longread sequencing and pangenome frameworks to uncover breed-specific and population-level variation.While many SVs are linked to economically important traits such as feed efficiency and disease resistance,their broader regulatory impacts remain an active area of investigation.Emerging functional genomics approaches,including transcriptomics,epigenomics,and genome editing,will clarify how SVs influence gene regulation and phenotype.Looking forward,the integration of SV catalogs with multi-omics data,imputation resources,and artificial intelligence-driven models will be essential for translating discoveries into breeding and conservation applications.Integrating structural variants into breeding pipelines promises to revolutionize livestock genomics,enabling precision selection and sustainable agriculture despite challenges in cost,data sharing,and functional validation.展开更多
基金The National Basic Research Program of China under contract No. 2013CB430304the National High-Tech R&D Program of China under contract No. 2013AA09A505the National Natural Science Foundation of China under contract Nos 41030854,40906015,40906016,41106005 and 41176003
文摘In order to solve the so-called ＂bull-eye＂ problem caused by using a simple bilinear interpolation as an observational mapping operator in the cost function in the multigrid three-dimensional variational （3DVAR） data assimilation scheme, a smoothing term, equivalent to a penalty term, is introduced into the cost function to serve as a means of troubleshooting. A theoretical analysis is first performed to figure out what on earth results in the issue of ＂bull-eye＂, and then the meaning of such smoothing term is elucidated and the uniqueness of solution of the multigrid 3DVAR with the smoothing term added is discussed through the theoretical deduction for one-dimensional （1D） case, and two idealized data assimilation experiments （one- and two-dimensional （2D） cases）. By exploring the relationship between the smoothing term and the recursive filter theoretically and practically, it is revealed why satisfied analysis results can be achieved by using such proposed solution for the issue of the multigrid 3DVAR.
基金Project supported by the National Natural Science Foundation of China (Grant No. 41105063)
文摘This work addresses the problem of estimating the states of nonlinear dynamic systems with sparse observations.We present a hybrid three-dimensional variation（3DVar） and particle piltering（PF） method,which combines the advantages of 3DVar and particle-based filters.By minimizing the cost function,this approach will produce a better proposal distribution of the state.Afterwards the stochastic resampling step in standard PF can be avoided through a deterministic scheme.The simulation results show that the performance of the new method is superior to the traditional ensemble Kalman filtering（EnKF） and the standard PF,especially in highly nonlinear systems.
基金supported by the Chinese Academy of Science(Contract No. KZCX2-YW-202)the 973 Pro-gram (Grant No. 2006CB403606)the National Natural Science Foundation of China (Grant Nos. 40606008,40776011)
文摘In order to improve the efficiency of the Ocean Variational Assimilation System （OVALS）, which has been widely used in various applications, an improved OVALS （OVALS2） is developed based on the recursive filter （RF） algorithm. The first advantage of OVALS2 is that memory storage can be substantially reduced in practice because it implicitly computes the background error covariance matrix; the second advantage is that there is no inversion of the background error covariance by preconditioning the control variable. For comparing the effectiveness between OVALS2 and OVALS, a set of experiments was implemented by assimilating expendable bathythermograph （XBT） and ARGO data into the Tropical Pacific circulation model. The results show that the efficiency of OVALS2 is much higher than that of OVALS. The computational time and the computer storage in the assimilation process were reduced by 83% and 77%, respectively. Additionally, the corresponding results produced by the RF are almost as good as those obtained by OVALS. These results prove that OVALS2 is suitable for operational numerical oceanic forecasting.
基金supported by the Central Guiding Local Science and Technology Development Fund of Shandong-Yellow River Basin(No.YDZX2023019)Shandong Natural Science Foundation of China(Nos.ZR2020QF067 and ZR2023QD073)+6 种基金the Discipline Cluster Research Project of Qingdao University“Deep mining and intelligent prediction of multimodal big data for marine ecological disasters”(No.20240604)sourced from the International Argo Program and the national programs that contribute to it(https://argo.ucsd.edu)the CMEMS(http://marine.copernicus.eu/)the CDS(https://cds.climate.copernicus.eu/)the EMODnet(https://www.emodnet-chemistry.eu/)obtained from the ERA5(https://www.ecmwf.int)derived from the Glob Colour Project(http://globcolour.info).
文摘Oceanic dissolved oxygen(DO)concentration is crucial for assessing the status of marine ecosystems.Against the backdrop of global warming,DO shows a general decrease,posing a threat to the health of marine ecosystems.Therefore,there is an urgent need to develop advanced tools to characterize the spatio-temporal variations of three-dimensional(3D)DO.To address this challenge,this study introduces the Light Gradient Boosting Machine(Light-GBM),combining satellite remote sensing and reanalysis data with Biogeochemical Argo data to accurately reconstruct the 3D DO structure in the Mediterranean Sea from 2010 to 2022.Various environmental parameters are incorporated as inputs,including spatiotemporal features,meteorological characteristics,and ocean color properties.The LightGBM model demonstrates excellent performance on the testing dataset with R^(2) of 0.958.The modeled DO agrees better with in-situ measurements than products from numerical models.Using the Shapley Additive exPlanations method,the contributions of input features are assessed.Sea surface temperatures provide a correlation with DO at the sea surface,while spatial coordinates supplement the view of the ocean interior.Based on the reconstructed 3D DO structure,we identify an oxygen minimum zone in the western Mediterranean that expands continuously,reaching depths of approximately 300–800 m.The western Mediterranean exhibits a significant declining trend.This study enhances marine environmental evidence by proposing a precise and cost-effective approach for reconstructing 3D DO,thereby offering insights into the dynamics of DO variations under changing climatic conditions.
基金The National Key R&D Program of China under contract No.2022YFE0106400the China Scholarship Council under contract No.202206710071+2 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province under contract No.KYCX23_0657the Special Founds for Creative Research under contract No.2022C61540the Opening Project of the Key Laboratory of Marine Environmental Information Technology under contract No.521037412.
文摘Satellite altimetry missions at high latitude have opened new avenues for understanding the changes occurring over the ice-covered region.By incorporating Arctic satellite remote sensing data-including sea surface temperature(SST),sea surface height anomaly(SSHA),and sea surface salinity(SSS).This study employs a variational method to reconstruct the three-dimensional thermohaline structure of the Arctic Ocean.Compared to the Regional Arctic Reanalysis(RARE),the reconstruction well captures both the horizontal and vertical temperature and salinity structures in the Arctic.It demonstrates superior skill over RARE,when compared with Argo profiles and Ice-Tethered Profiler(ITP)observations.The reconstruction is particularly effective in ice-covered regions,where it more accurately captures the transition from Pacific water to Atlantic water compared to RARE.These findings underscore the potential of applying Arctic satellite data to reconstruct vertical thermohaline structures in the Arctic,particularly in areas due to lack of the subsurface observation reanalysis data exhibit significant biases.As Arctic satellite observations continue to advance,the applications of this method are becoming increasingly promising,which is useful for monitoring the ice-covered region environment and can be applied to oceanographic research.
基金National Key Basic Research and Development(973)Program of China(2014CB441406)National Natural Science Foundation of China(91537209 and 41675001)Basic Research Fund of Chinese Academy of Meteorological Sciences(2016Z002and 2016Y008)
文摘A large number of observational analyses have shown that lightning data can be used to indicate areas of deep convection. It is important to assimilate observed lightning data into numerical models, so that more small-scale information can be incorporated to improve the quality of the initial condition and the subsequent forecasts. In this study, the empirical relationship between flash rate, water vapor mixing ratio, and graupel mixing ratio was used to adjust the model relative humidity, which was then assimilated by using the three-dimensional variational data assimilation system of the Weather Research and Forecasting model in cycling mode at 10-min intervals. To find the appropriate assimilation time-window length that yielded significant improvement in both the initial conditions and subsequent forecasts, four experiments with different assimilation time-window lengths were conducted for a squall line case that occurred on 10 July 2007 in North China. It was found that 60 min was the appropriate assimilation time-window length for this case, and longer assimilation window length was unnecessary since no further improvement was present. Forecasts of 1-h accumulated precipitation during the assimilation period and the subsequent 3-h accumulated precipitation were significantly improved compared with the control experiment without lightning data assimilation. The simulated reflectivity was optimal after 30 min of the forecast, it remained optimal during the following 42 min, and the positive effect from lightning data assimilation began to diminish after 72 min of the forecast. Overall,the improvement from lightning data assimilation can be maintained for about 3 h.
文摘Under the strategic framework of rural revitalization and agricultural modernization, Xinjiashan Specialty Coffee Base, located in Zaotang Village, Lujiang Town, Longyang District, Baoshan City, has been proactively investigating innovative models for agricultural development. Through extensive communication and collaboration, this base has established close partnerships with research institutions including Kunming University of Science and Technology, Baoshan University, and Yunnan Academy of Agricultural Sciences, with a commitment to thoroughly exploring the potential for resource recycling and ecological complementarity. An innovative four-in-one three-dimensional integrated planting system incorporating "coffee, bananas, green manure, and bees" has been implemented. Concurrently, technological and digital management strategies have been comprehensively integrated to improve planting efficiency. Under this model, the proportion of specialty coffee attains 71%, and the per-unit yield is 17% greater than that of the conventional planting model. This approach not only substantially enhances economic returns but also promotes the integrated development of ecological and social benefits, offering a valuable practical example and experiential reference for the specialty and sustainable advancement of the coffee industry in comparable regions.
基金supported by the National Key Research and Development Program(No.2022YFC2807400)the National Natural Science Foundation of China(Nos.12265003 and 12205044)。
文摘Aerial surveys are dynamic and continuous processes,and there are different height distributions of the ground in the measurement area,which leads to problems such as overlapping measurement areas and inaccurate altitude correction during the survey process.Commonly used terrain correction methods are based on the concept of finite elementization of ground surface radioactive sources,using GPS coordinates,radar altitude,and ground elevation distribution information from aerial surveys,combined with the sourceless efficiency calibration method to construct a response matrix,which is then inverted for surface nuclide content.However,most of the sourceless efficiency calibration methods used are numerical calculations that consider the body detector as a point detector and do not consider the changes in intrinsic detection efficiency under different incident directions of gamma rays.Therefore,when the altitude of the measurement area varies significantly or the flight altitude of the aerial survey is relatively low,such sourceless efficiency calibration method calculations tend to have a large bias,which affects the accuracy of the terrain correction.To address the above problems,this study employs a novel sourceless efficiency calibration method based on the Boolean operation of the ray deposition process and simplifies the traditional body source measurement model to a surface source measurement model to achieve fast and accurate efficiency calibration.Then,through the discretization of the measurement process,the static measurement process is superposed as equivalent to the dynamic measurement process,and the dynamic measurement response matrix is built and optimized based on the calibration method.Finally,the PSO-MLEM algorithm was used to solve the dynamic measurement response matrix to achieve dynamic terrain correction of aerial survey data.Analysis of the Baiyun'ebo test area revealed that,after applying dynamic terrain correction,the inverted anomalies in uranium(eU),thorium(eTh),and potassium(K)concentrations were closer to ground measurements(within 5.72%-30.79%)and exhibited clearer anomaly boundaries compared to traditional height-based corrections.However,owing to the inherent statistical fluctuations and characteristics of matrix inversion,higher measurement values tend to absorb lower ones,potentially enlarging the anomalous regions.Nevertheless,the highanomaly regions after inversion largely coincided with the ground truth validation,demonstrating that the proposed method can effectively correct airborne gamma spectrometry data.
基金supported by the National Natural Science Founda-tion of China(Nos.42327806 and 52370108)Zhejiang Provincial Leading Project for Leading Geese Plan(No.2025C03073).
文摘Carbonyls play an important role in the atmospheric chemistry as the main precursor for reactive radicals and peroxyacetyl nitrate.However,little research has been conducted so far on the seasonal variations of carbonyls in China’s urban atmosphere.In this study,ambient carbonyls were 24-hourly observed in four seasons in Hangzhou,a mega-city in the Yangtze River Delta Region,China.The concentration of total carbonyls was the highest in summer(44.35μg/m^(3)),the second in winter(44.05μg/m^(3)),the third in spring(29.31μg/m^(3))and autumn(27.11μg/m^(3)).The most abundant species were found to be acetone in spring,summer,and winter,while formaldehyde in autumn.Rainfall can significantly reduce the concentrations of most ambient carbonyls,with the largest decrease observed in the wet precipitation events occurring in spring and summer,while acetone concentrations remained invariable due to its lower water solubility.Multiple linear regression analysis and carbonyls ratios indicated that anthropogenic emissions were the predominant sources of carbonyls,and atmospheric formaldehyde was mainly emitted from primary sources other than secondary sources.Vehicular exhaust was identified as the primary source of ambient carbonyls,particularly in winter,and its contribution reached 92.80%to formaldehyde.Additionally,photochemical reactions were closely associated with the secondary production of formaldehyde in summer.Carbonyls showed strong ozone formation potential in all four seasons.Based on the health risk assessment,the exposure to ambient carbonyls is harmful to outdoor pedestrians.The results could provide essential information and references for simulating regional air quality and analyzing ozone pollution,which is essential for improving air quality in the Yangtze River Delta region.
基金Project supported in part by Beijing Natural Science Foundation(Grant No.1232025)Peng Huanwu Visiting Pro-fessor Program,and Academy for Multidisciplinary Studies,Capital Normal University.
文摘Replicating the chaotic characteristics inherent in nonlinear dynamical systems via machine learning(ML)is a key challenge in this rapidly advancing interdisciplinary field.In this work,we explore the potential of variational quantum circuits(VQC)for learning the stochastic properties of classical nonlinear dynamical systems.Specifically,we focus on the one-and two-dimensional logistic maps,which,while simple,remain under-explored in the context of learning dynamical characteristics.Our findings reveal that,even for such simple dynamical systems,accurately replicating longterm characteristics is hindered by a pronounced sensitivity to overfitting.While increasing the parameter complexity of the ML model typically enhances short-term prediction accuracy,it also leads to a degradation in the model’s ability to replicate long-term characteristics,primarily due to the detrimental effects of overfitting on generalization power.By comparing the VQC with two widely recognized classical ML techniques,which are long short-term memory(LSTM)networks for timeseries processing and reservoir computing,we demonstrate that VQC outperforms these methods in terms of replicating long-term characteristics.Our results suggest that for the ML of dynamics,it is demanded to develop more compact and efficient models(such as VQC)rather than more complicated and large-scale ones.
基金supported financially by the National Natural Science Foundation of China(31811530297 and 32170217).
文摘Plastome variation,including single spontaneous nucleotide substitutions and single insertions/deletions,is the major source of leaf variegation in plants.Additionally,one recent study has showed that a simple plastome structural variation,which is induced by one pair of small inverted repeats,can also result in leaf variegation.Here we show a complex plastome structural variation caused by intermolecular and intramolecular recombination across three pairs of small inverted repeats accounts for leaf variegation in a widely cultivated shrub Heptapleurum ellipticum(Araliaceae).This plastome structural variation contains two deletions and two duplications,resulting in dramatic expansion of IRs,substantial contraction of LSC and loss of 11 genes that essential for photosynthesis.Plastome heteroplasmy was detected in both green and albino sectors of variegated leaves.Relative to green sectors,albino sectors in the variegated leaves exhibit significantly reduced expression for the 11 genes lost in the mutated plastome as well as 26 other genes,but significantly increased expression for one gene related to translation apparatus.Optical and transmission electron microscopy observations showed that mesophyll cells of albino sectors possess plastids lacking grana lamellae,which likely carry the mutated plastome and contribute to albinism.In both sectors,the first layer of spongy mesophyll cells beneath the lower epidermis contains normal chloroplasts,suggesting periclinal division of the lower epidermis during development.Our study demonstrates that multiple small repeats can collectively mediate intra-and inter-molecular recombination in plastome and offers a new mechanism accounting for leaf variegation in plants.
基金supported by the Science and Technology Major Project of Shanxi Province,China(202201140601025-2,202302140601001)the Agricultural Science Research Project of Shanxi Agricultural University,China(2023BQ108)+1 种基金the Senior Foreign Experts Introducing Project,China(G202204011L)the Science and Technology Innovation Young Talent Team of Shanxi Province,China(202204051001019)。
文摘Structural variation is an important source of genetic variation in wheat and have been important in the evolution of the wheat's genome.Few studies have examined the relationship between structural variations and agronomy and drought tolerance.The present study identified structural chromosome variations(SCVs)in a doubled haploid(DH)population and backcross introgression lines(BC5F3)derived from Jinmai 47 and Jinmai 84 using fluorescence in situ hybridization(FISH).There are one simple translocation,10 present/absent variations(PAVs),and one copy number variation(CNV)between Jinmai 47 and Jinmai 84,which distributed in 10 chromosomes.Eight SCVs were associated with 15 agronomic traits.A PAV recombination occurred on chromosome 2A,which was associated with grain number per spike(GNS).The 1BL/1RS translocation and PAV.2D were associated with significant reductions in plant height,deriving from the effects on LI2-LI4,LI2-LI4 and UI,respectively respectively.PAV.2D was also contributed to an increase of 3.13%for GNS,1BL/1RS significantly increased spikelet number,grain length(GL),and grain thickness(GT).The effect of PAV.4A.1 on GL,PAV.6A on spike length(SL)and thousand-grain weight(TGW),PAV.6B on SL,GT and TGW were identified and verified.PAVs on chromosomes 2A,6A,1D,2D,and a CNV on chromosome 4B were associated with the drought tolerance coefficients.Additive and interaction effects among SCVs were observed.Many previously cloned key genes and yield-related QTL were found in polymorphic regions of PAV.2B,PAV.2D,and CNV.4B.Altogether,this study confirmed the genetic effect of SCVs on agronomy and drought tolerance,and identification of these SCVs will facilitate genetic improvement of wheat through marker-assisted selection.
基金supported by the National Natural Science Foundation of China under Grants No.12375030。
文摘Signal transduction in a cell is mostly mediated with biochemical reactions which are noisy and often modeled with chemical master equations or Langevin type of dynamics.Thus stochastic simulation constitutes a major part of computation in cell signaling.Nevertheless,the presence of a wide span of time scales or molecular numbers in various pathways may lead to trouble in computation efficiency or accuracy.To avoid this problem,the commonly employed variational method evolves the whole probability distribution and reduces the stochastic equations to deterministic ones of only a few parameters.However,the design of the left variational basis is essential for its successful application,especially to large networks.In this paper,we extend the conventional polynomial basis to the Fourier and further the Gaussian basis,much facilitating description of multi-peaked or localized non-Gaussian distributions and at the same time avoiding numerical instability and computational complexity frequently encountered with conventional basis.The extension here is demonstrated in several typical biochemical signaling networks and achieves similar accuracy as the benchmark Gillespie algorithm,but with much less running time,which seems to open new opportunities in the variational approach to efficient analysis of noisy dynamics.
基金The national research foundation of Singapore(NRF-P2024-001).
文摘Variational quantum algorithms(VQAs)with random structures have poor trainability due to the exponentially vanishing gradient as the circuit depth and the qubit number increase.This result leads to a general belief that a deep circuit will not be feasible.In this work,we provide a viable solution to the vanishing gradient problem for deep VQAs with theoretical guarantees.Specifically,we prove that for quantum controlled-layer and quantum residual network(QResNet),architectures,the expectation of the gradient norm can be lower bounded by a value that is independent of the qubit number and the circuit depth.Our results follow from a careful analysis of the gradient behavior on parameter space consisting of rotation angles,as employed in almost all VQAs,instead of relying on impractical 2-design assumptions.We conduct several numerical experiments as verifications,where only our circuits are trainable and converge,while hardware-efficient and random circuits with similar number of parameters in comparison cannot converge.
基金supported by the National Natural Science Foundation of China(Grant Nos.42027804,41775026,and 41075012)。
文摘Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and reanalysis data(MERRA-2)from March 2007 to February 2015(eight years).The horizontal distribution reveals lower cirrus fraction values in the northern SCS and higher values in the southern region,with minima observed in March and April and maxima sequentially occurring in August(northern SCS,NSCS),September(middle SCS,MSCS),and December(southern SCS,SSCS).Vertically,the cirrus fraction peaks in summer and reaches its lowest levels in spring.Opaque cirrus dominates during summer in the NSCS and MSCS,comprising 53.6%and 55.9%,respectively,while the SSCS exhibits a higher frequency of opaque cirrus relative to other cloud types.Subvisible cirrus clouds have the lowest frequency year-round,whereas thin cirrus is most prominent in winter in the NSCS(46.3%)and in spring in the MSCS(45.3%).A case study from September 2021 further explores the influence of ice crystal habits on brightness temperature(BT)over the SCS.Simulations utilizing five ice crystal shapes from the ARTS DDA(Atmospheric Radiative Transfer Simulator Discrete Dipole Approximation)database and the RTTOV 12.4 radiative transfer model reveal that the 8-column-aggregate shape best represents BT in the NSCS and SSCS,while the large-block-aggregate shape performs better in the SSCS.
基金supported by the National Natural Science Foundation of China(U2344201 and 42101316)the Natural Science Foundation of Hunan Province,China(2022JJ40866)the Outstanding Youth Project of Education Bureau of Hunan Province,China(20B613)。
文摘Understanding the spatial distributions and corresponding variation mechanisms of key soil nutrients in fragile karst ecosystems can assist in promoting sustainable development.However,due to the implementation of ecological restoration initiatives such as land-use conversions,novel changes in the spatial characteristics of soil nutrients remain unknown.To address this gap,we explored nutrient variations and the drivers of the variation in the 0–15 cm topsoil layer using a regional-scale sampling method in a typical karst area in northwest Guangxi Zhuang Autonomous Region,Southwest China.Descriptive statistics,geostatistics,and spatial analysis were used to assess the soil nutrient variability.The results indicated that soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP),and total potassium(TK)concentrations showed moderate variations,with coefficients of variance being 0.60,0.60,0.71,and 0.72,respectively.Moreover,they demonstrated positive spatial autocorrelations,with global Moran's indices being 0.68,0.77,0.64,and 0.68,respectively.However,local Moran's index values were low,indicating large spatial variations in soil nutrients.The best-fitting semi-variogram models for SOC,TN,TP,and TK concentrations were spherical,Gaussian,exponential,and exponential,respectively.According to the classification criteria of the Second National Soil Census in China,SOC and TN concentrations were relatively sufficient,with the proportions of rich and very rich levels being up to 90.9 and 96.0%,respectively.TP concentration was in the mediumdeficient level,with the areas of medium and deficient levels accounting for 33.7 and 30.1%of the total,respectively.TK concentration was deficient,with the cumulative area of extremely deficient,very deficient,and deficient levels accounting for 87.6%of the total area.Consequently,the terrestrial ecosystems in the study area were more vulnerable to soil P and K than soil N deficiencies.Furthermore,variance partitioning analysis of the influencing factors showed that,except for the interactions,the single effect of other soil properties accounted more for soil nutrient variations than spatial and environmental variables.These results will aid in the future management of terrestrial ecosystems.
基金supported by the CAS Pioneer Hundred Talents Program and Second Tibetan Plateau Scientific Expedition Research Program(2019QZKK0708)as well as the Basic Research Program of Qinghai Province:Lithospheric Geomagnetic Field of the Qinghai-Tibet Plateau and the Relationship with Strong Earthquakes(2021-ZJ-969Q).
文摘The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-based observations remain insufficient to clearly reflect the characteristics of the region’s lithospheric magnetism.In this study,we evaluate the lithospheric magnetism of the Tibetan Plateau by using a 3D surface spline model based on observations from>200 newly constructed repeat stations(portable stations)to determine the spatial distribution of plateau geomagnetism,as well as its correlation with the tectonic features of the region.We analyze the relationships between M≥5 earthquakes and lithospheric magnetic field variations on the Tibetan Plateau and identify regions susceptible to strong earthquakes.We compare the geomagnetic results with those from an enhanced magnetic model(EMM2015)developed by the NGDC and provide insights into improving lithospheric magnetic field calculations in the Tibetan Plateau region.Further research reveals that these magnetic anomalies exhibit distinct differences from the magnetic-seismic correlation mechanisms observed in other tectonic settings;here,they are governed primarily by the combined effects of compressional magnetism,thermal magnetism,and deep thermal stress.This study provides new evidence of geomagnetic anomalies on the Tibetan Plateau,interprets them physically,and demonstrates their potential for identifying seismic hazard zones on the Plateau.
基金support of the National Natural Science Foundation of China(No.12172023)。
文摘According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing differential equations are derived by the Hamilton's variational principle,and then solved by the iterative Separation-of-Variable(i SOV)method,which are applicable to arbitrary combinations of homogeneous Boundary Conditions(BCs).However,only the simply-support,clamped and cantilever panels are considered in this work for the sake of clarity.With the closed-form eigensolutions,the flutter frequency,flutter mode and flutter boundary are presented,and the effect of shear deformation and aerodynamic damping on flutter frequencies is investigated.Besides,the relation between panel energy and the work of aerodynamic load is discussed.The numerical comparisons reveal the following.(A)The flutter eigenvalues obtained by the present method are accurate,validated by the Finite Element Method(FEM)and the Galerkin method.(B)When the span-chord ratio is larger than 3,simplifying a 3D panel to 2D(two-dimensional)panel is reasonable and the relative differences of the flutter points predicted by the two models are less than one percent.(C)The reciprocal relationship between the mechanical energy of the panel and the work done by aerodynamic load is verified by using the present flutter eigenvalues and modes,further indicating the high accuracy of the present solutions.(D)The coupling of shear deformation and aerodynamic damping prevents frequency coalescing.
基金supported by the NSFC(12461012)and the NSF of Chongqing(CSTB2024NSCQ-MSX1246).
文摘In this manuscript,we consider a non-autonomous dynamical system.Using the Carathéodory structure,we define a BS dimension on an arbitrary subset and obtain a Bowen’s equation that illustrates the relation of the BS dimension to the Pesin-Pitskel topological pressure given by Nazarian[24].Moreover,we establish a variational principle and an inverse variational principle for the BS dimension of non-autonomous dynamical systems.Finally,we also get an analogue of Billingsley’s theorem for the BS dimension of non-autonomous dynamical systems.
基金supported in part by AFRI grant numbers 2019-7015-29321 and 2021-67015-33409 from the USDA National Institute of Food and Agriculture(NIFA)the SCINet project of the USDA ARS project number 0500-00093-001-00-D。
文摘Structural variations(SVs≥50 bp)are a critical but underexplored source of genetic diversity in cattle,shaping traits vital for productivity,adaptability,and health.Advances in long-read sequencing,pangenome graph construction,and near-complete genome assemblies now allow accurate SV detection and genotyping.These innovations overcome the limitations of single-reference genomes,enabling the discovery of complex SVs,including nested and overlapping variants,and providing access to previously inaccessible genomic regions such as centromeres and telomeres.This review highlights the current landscape of cattle SV research,with emphasis on integrating longread sequencing and pangenome frameworks to uncover breed-specific and population-level variation.While many SVs are linked to economically important traits such as feed efficiency and disease resistance,their broader regulatory impacts remain an active area of investigation.Emerging functional genomics approaches,including transcriptomics,epigenomics,and genome editing,will clarify how SVs influence gene regulation and phenotype.Looking forward,the integration of SV catalogs with multi-omics data,imputation resources,and artificial intelligence-driven models will be essential for translating discoveries into breeding and conservation applications.Integrating structural variants into breeding pipelines promises to revolutionize livestock genomics,enabling precision selection and sustainable agriculture despite challenges in cost,data sharing,and functional validation.
