The separation-of-variable(SOV)methods,such as the improved SOV method,the variational SOV method,and the extended SOV method,have been proposed by the present authors and coworkers to obtain the closed-form analytica...The separation-of-variable(SOV)methods,such as the improved SOV method,the variational SOV method,and the extended SOV method,have been proposed by the present authors and coworkers to obtain the closed-form analytical solutions for free vibration and eigenbuckling of rectangular plates and circular cylindrical shells.By taking the free vibration of rectangular thin plates as an example,this work presents the theoretical framework of the SOV methods in an instructive way,and the bisection–based solution procedures for a group of nonlinear eigenvalue equations.Besides,the explicit equations of nodal lines of the SOV methods are presented,and the relations of nodal line patterns and frequency orders are investigated.It is concluded that the highly accurate SOV methods have the same accuracy for all frequencies,the mode shapes about repeated frequencies can also be precisely captured,and the SOV methods do not have the problem of missing roots as well.展开更多
Let f be a primitive holomorphic cusp form with even integral weight k≥2 for the full modular groupΓ=SL(2,Z)andλ_(sym^(j)f)(n)be the n-th coefficient of Dirichlet series of j-th symmetric L-function L(s,sym^(j)f)at...Let f be a primitive holomorphic cusp form with even integral weight k≥2 for the full modular groupΓ=SL(2,Z)andλ_(sym^(j)f)(n)be the n-th coefficient of Dirichlet series of j-th symmetric L-function L(s,sym^(j)f)attached to f.In this paper,we study the mean value distribution over a specific sparse sequence of positive integers of the following sum∑(a^(2)+b^(2)+c^(2)+d^(2)≤x(a,b,c,d)∈Z^(4))λ_(sym^(j))^(i)f(a^(2)+b^(2)+c^(2)+d^(2))where j≥2 is a given positive integer,i=2,3,4 andαis sufficiently large.We utilize Python programming to design algorithms for higher power conditions,combining Perron's formula,latest results of representations of natural integers as sums of squares,as well as analytic properties and subconvexity and convexity bounds of automorphic L-functions,to ensure the accuracy and verifiability of asymptotic formulas.The conclusion we obtained improves previous results and extends them to a more general settings.展开更多
The self-assembled nanoparticles(SAN)formed during the decoction process of traditional Chinese medicine(TCM)exhibit non-uniform particle sizes and a tendency for aggregation.Our group found that the p H-driven method...The self-assembled nanoparticles(SAN)formed during the decoction process of traditional Chinese medicine(TCM)exhibit non-uniform particle sizes and a tendency for aggregation.Our group found that the p H-driven method can improve the self-assembly phenomenon of Herpetospermum caudigerum Wall.,and the SAN exhibited uniform particle size and demonstrated good stability.In this paper,we analyzed the interactions between the main active compound,herpetrione(Her),and its main carrier,Herpetospermum caudigerum Wall.polysaccharide(HCWP),along with their self-assembly mechanisms under different p H values.The binding constants of Her and HCWP increase with rising p H,leading to the formation of Her-HCWP SAN with a smaller particle size,higher zeta potential,and improved thermal stability.While the contributions of hydrogen bonding and electrostatic attraction to the formation of Her-HCWP SAN increase with rising p H,the hydrophobic force consistently plays a dominant role.This study enhances our scientific understanding of the self-assembly phenomenon of TCM improved by p H driven method.展开更多
Most material distribution-based topology optimization methods work on a relaxed form of the optimization problem and then push the solution toward the binary limits.However,when benchmarking these methods,researchers...Most material distribution-based topology optimization methods work on a relaxed form of the optimization problem and then push the solution toward the binary limits.However,when benchmarking these methods,researchers use known solutions to only a single form of benchmark problem.This paper proposes a comparison platform for systematic benchmarking of topology optimization methods using both binary and relaxed forms.A greyness measure is implemented to evaluate how far a solution is from the desired binary form.The well-known ZhouRozvany(ZR)problem is selected as the benchmarking problem here,making use of available global solutions for both its relaxed and binary forms.The recently developed non-penalization Smooth-edged Material Distribution for Optimizing Topology(SEMDOT),well-established Solid Isotropic Material with Penalization(SIMP),and continuation methods are studied on this platform.Interestingly,in most cases,the grayscale solutions obtained by SEMDOT demonstrate better performance in dealing with the ZR problem than SIMP.The reasons are investigated and attributed to the usage of two different regularization techniques,namely,the Heaviside smooth function in SEMDOT and the power-law penalty in SIMP.More importantly,a simple-to-use benchmarking graph is proposed for evaluating newly developed topology optimization methods.展开更多
Tailings produced by mining and ore smelting are a major source of soil pollution.Understanding the speciation of heavy metals(HMs)in tailings is essential for soil remediation and sustainable development.Given the co...Tailings produced by mining and ore smelting are a major source of soil pollution.Understanding the speciation of heavy metals(HMs)in tailings is essential for soil remediation and sustainable development.Given the complex and time-consuming nature of traditional sequential laboratory extraction methods for determining the forms of HMs in tailings,a rapid and precise identification approach is urgently required.To address this issue,a general empirical prediction method for HM occurrence was developed using machine learning(ML).The compositional information of the tailings,properties of the HMs,and sequential extraction steps were used as inputs to calculate the percentages of the seven forms of HMs.After the models were tuned and compared,extreme gradient boosting,gradient boosting decision tree,and categorical boosting methods were found to be the top three performing ML models,with the coefficient of determination(R^(2))values on the testing set exceeding 0.859.Feature importance analysis for these three optimal models indicated that electronegativity was the most important factor affecting the occurrence of HMs,with an average feature importance of 0.4522.The subsequent use of stacking as a model integration method enabled the ability of the ML models to predict HM occurrence forms to be further improved,and resulting in an increase of R^(2) to 0.879.Overall,this study developed a robust technique for predicting the occurrence forms in tailings and provides an important reference for the environmental assessment and recycling of tailings.展开更多
Improving the computational efficiency of multi-physics simulation and constructing a real-time online simulation method is an important way to realise the virtual-real fusion of entities and data of power equipment w...Improving the computational efficiency of multi-physics simulation and constructing a real-time online simulation method is an important way to realise the virtual-real fusion of entities and data of power equipment with digital twin.In this paper,a datadriven fast calculation method for the temperature field of resin impregnated paper(RIP)bushing used in converter transformer valve-side is proposed,which combines the data dimensionality reduction technology and the surrogate model.After applying the finite element algorithm to obtain the temperature field distribution of RIP bushing under different operation conditions as the input dataset,the proper orthogonal decomposition(POD)algorithm is adopted to reduce the order and obtain the low-dimensional projection of the temperature data.On this basis,the surrogate model is used to construct the mapping relationship between the sensor monitoring data and the low-dimensional projection,so that it can achieve the fast calculation and reconstruction of temperature field distribution.The results show that this method can effectively and quickly calculate the overall temperature field distribution of the RIP bushing.The maximum relative error and the average relative error are less than 4.5%and 0.25%,respectively.The calculation speed is at the millisecond level,meeting the needs of digitalisation of power equipment.展开更多
To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying ...To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying method.The morphology,structure and thermal decomposition properties of the samples were analyzed using scanning electron microscopy(SEM),X-ray energy spectroscopy(EDS),infrared spectroscopy(FT-IR),and simultaneous thermal analyzer(TG-DSC).Additionally,the combustion process of the samples was tested using a high-speed camera.The results show that the addition of nano-Si contributes to the formation of composite explosives with regular morphology and smaller particle size.The Si/NC/CL-20 composite explosive has better and more uniform sphericity,with an average particle size of 73.4 nm,compared to the NC/CL-20 composite explosive.The Si/NC/CL-20 composite explosive which produced by the electrostatic spraying method,achieves physically uniform distribution of the components including NC,CL-20,Si.The addition of Si promotes the thermal decomposition of CL-20.In comparison to the NC/CL-20 composite explosive,the activation energy of the Si/NC/CL-20 composite explosive decreases by 16.78 kJ/mol,and the self-accelerated decomposition temperature and the critical temperature of thermal explosion decreases by 3.12 K and 2.61 K,respectively.Furthermore,Si/NC/CL-20 composite explosive has shorter ignition delay time and faster combustion rate compared to the NC/CL-20 composite explosive,which shows that Si can improve the combustion performance of CL-20.展开更多
The 21 cm radiation of neutral hydrogen provides crucial information for studying the early universe and its evolution.To advance this research,countries have made significant investments in constructing large lowfreq...The 21 cm radiation of neutral hydrogen provides crucial information for studying the early universe and its evolution.To advance this research,countries have made significant investments in constructing large lowfrequency radio telescope arrays,such as the Low Frequency Array and the Square Kilometre Array Phase 1 Low Frequency.These instruments are pivotal for radio astronomy research.However,challenges such as ionospheric plasma interference,ambient radio noise,and instrument-related effects have become increasingly prominent,posing major obstacles in cosmology research.To address these issues,this paper proposes an efficient signal processing method that combines wavelet transform and mathematical morphology.The method involves the following steps:Background Subtraction:Background interference in radio observation signals is eliminated.Wavelet Transform:The signal,after removing background noise,undergoes a two-dimensional discrete wavelet transform.Threshold processing is then applied to the wavelet coefficients to effectively remove interference components.Wavelet Inversion:The processed signal is reconstructed using wavelet inversion.Mathematical Morphology:The reconstructed signal is further optimized using mathematical morphology to refine the results.Experimental verification was conducted using solar observation data from the Xinjiang Observatory and the Yunnan Observatory.The results demonstrate that this method successfully removes interference signals while preserving useful signals,thus improving the accuracy of radio astronomy observations and reducing the impact of radio frequency interference.展开更多
By analyzing the urgent demand for digital talents in the current landscape industry and the challenges faced by the traditional teaching mode,this study aims to explore a set of teaching methodology reform solutions ...By analyzing the urgent demand for digital talents in the current landscape industry and the challenges faced by the traditional teaching mode,this study aims to explore a set of teaching methodology reform solutions based on digital technology to improve the quality of teaching and enhance the practical innovation ability of students.The study firstly describes the application of digital technologies such as CAD/BIM,3D modelling and rendering,virtual reality(VR)/augmented reality(AR),and geographic information system(GIS)in the field of landscape architecture.Then,the current teaching status of plant configuration and landscape architecture courses is analyzed,and the advantages and challenges of digital technology applications are identified.On this basis,this study proposes a multi-dimensional reform path and practice plan including the reconstruction of teaching objectives and content,innovation of teaching mode,improvement of teaching strategies and methods,as well as the construction of teaching resources and the reform of teaching evaluation,guided by modern educational theories such as constructivism,collaborative learning and project-based learning(PBL).Finally,this study emphasizes the key roles of faculty construction,optimization of hardware and software environment,and teaching management and institutional guarantee in the reform.展开更多
This study achieves a notable enhancement in the thermoelectric performance of copper selenide compounds exhibiting liquid-like characteristics via an innovative processing method.A KCl flux-assisted high-temperature ...This study achieves a notable enhancement in the thermoelectric performance of copper selenide compounds exhibiting liquid-like characteristics via an innovative processing method.A KCl flux-assisted high-temperature melting and slow-cooling strategy was employed to fabricate nanolayered Cu_(2)Se(KCl)_(x)materials(x=0-3,denoted as S_(0)-S_(3)).Systematic characterization reveals that the coexistence ofαandβphases at room temperature creates favorable conditions for optimizing carrier transport.XPS analysis confirms the substitution of low-binding-energy Se_(2)-by high-binding-energy Cl^(-)ions within the lattice,effectively suppressing copper ion migration and remarkably improving the material's structural stability.Microstructural investigations demonstrate that all samples exhibit nanolayered stacking architectures abundant with edge dislocations.This multiscale defect architecture induces strong phonon scattering effects.Hall measurements indicate that the KCl flux-assisted processing facilitates the formation of highly ordered nanostructures,thereby enhancing carrier mobility and structural stability.Although the carrier concentration exhibits a slight decrease compared with the flux-free samples,the significant improvement in microstructural quality plays a crucial role in the synergistic optimization of electrical conductivity and the Seebeck coefficient.Notably,sample S_(2)exhibited a considerable electrical conductivity,reaching approximately 1.0×10^(5)S·m^(-1)at 300 K.More strikingly,the cooperative effect of high-density edge dislocations and dopant atoms elevates material entropy,enabling sample S_(3)to attain an ultralow lattice thermal conductivity of 0.55 W·m^(-1)·K^(-1)at 350 K.Through multi-mechanism coordination,sample S_(2)achieved a high ZT value of 1.45 at 700 K,representing a 2.7-fold improvement compared with traditional synthesis methods.This work provides new insights into performance optimization of liquid-like thermoelectric materials through defect engineering and entropy manipulation.展开更多
With Beijing Huilongguan Sports and Cultural Park as the research object,this study was conducted to investigate public service satisfaction in the park by the Importance-Performance Analysis(IPA)method.A questionnair...With Beijing Huilongguan Sports and Cultural Park as the research object,this study was conducted to investigate public service satisfaction in the park by the Importance-Performance Analysis(IPA)method.A questionnaire covering six dimensions,including public transportation,sanitation and environment,and supporting facility construction,was designed.A total of 208 valid samples were collected,and SPSS was employed for reliability and validity tests as well as IPA analysis.The findings were as follows:①Visitors were generally quite satisfied with the overall public services in Huilongguan Sports and Cultural Park.②The highest satisfaction levels were observed in sanitation and environment services and the sports and cultural atmosphere,while lower satisfaction was noted for supporting facility construction and public information services.③The advantage enhancement zone includes sanitation and environment services and sports and cultural atmosphere;and the continuous maintenance zone includes public transportation services and security management amd maintenance;the subsequent opportunity zone includes supporting facility construction and public information services;and there are no dimensions in the urgent improvement zone.The study recommends strengthening the service connotations from three aspects:enhancing facilities with sports as the core,optimizing services with a people-centered approach,and upgrading the information platform through technological efficiency.Additionally,a multi-stakeholder collaborative mechanism involving the government in coordinating policy resources,the operator in improving implementation efficiency,and the public participating in supervision and evaluation is proposed to drive the enhancement of public service quality at Huilongguan Sports and Cultural Park.展开更多
A method combining finite difference method(FDM)and k-means clustering algorithm which can determine the threshold of rock bridge generation is proposed.Jointed slope models with different joint coalescence coefficien...A method combining finite difference method(FDM)and k-means clustering algorithm which can determine the threshold of rock bridge generation is proposed.Jointed slope models with different joint coalescence coefficients(k)are constructed based on FDM.The rock bridge area was divided through k-means algorithm and the optimal number of clusters was determined by sum of squared errors(SSE)and elbow method.The influence of maximum principal stress and stress change rate as clustering indexes on the clustering results of rock bridges was compared by using Euclidean distance.The results show that using stress change rate as clustering index is more effective.When the joint coalescence coefficient is less than 0.6,there is no significant stress concentration in the middle area of adjacent joints,that is,no generation of rock bridge.In addition,the range of rock bridge is affected by the coalescence coefficient(k),the relative position of joints and the parameters of weak interlayer.展开更多
To enhance the computational efficiency of spatio-temporally discretized phase-field models,we present a high-speed solver specifically designed for the Poisson equations,a component frequently used in the numerical c...To enhance the computational efficiency of spatio-temporally discretized phase-field models,we present a high-speed solver specifically designed for the Poisson equations,a component frequently used in the numerical computation of such models.This efficient solver employs algorithms based on discrete cosine transformations(DCT)or discrete sine transformations(DST)and is not restricted by any spatio-temporal schemes.Our proposed methodology is appropriate for a variety of phase-field models and is especially efficient when combined with flow field systems.Meanwhile,this study has conducted an extensive numerical comparison and found that employing DCT and DST techniques not only yields results comparable to those obtained via the Multigrid(MG)method,a conventional approach used in the resolution of the Poisson equations,but also enhances computational efficiency by over 90%.展开更多
The visual noise of each light intensity area is different when the image is drawn by Monte Carlo method.However,the existing denoising algorithms have limited denoising performance under complex lighting conditions a...The visual noise of each light intensity area is different when the image is drawn by Monte Carlo method.However,the existing denoising algorithms have limited denoising performance under complex lighting conditions and are easy to lose detailed information.So we propose a rendered image denoising method with filtering guided by lighting information.First,we design an image segmentation algorithm based on lighting information to segment the image into different illumination areas.Then,we establish the parameter prediction model guided by lighting information for filtering(PGLF)to predict the filtering parameters of different illumination areas.For different illumination areas,we use these filtering parameters to construct area filters,and the filters are guided by the lighting information to perform sub-area filtering.Finally,the filtering results are fused with auxiliary features to output denoised images for improving the overall denoising effect of the image.Under the physically based rendering tool(PBRT)scene and Tungsten dataset,the experimental results show that compared with other guided filtering denoising methods,our method improves the peak signal-to-noise ratio(PSNR)metrics by 4.2164 dB on average and the structural similarity index(SSIM)metrics by 7.8%on average.This shows that our method can better reduce the noise in complex lighting scenesand improvethe imagequality.展开更多
This study develops a geological hazard evaluation index system for Shouning County,a key area for disaster prevention in Fujian Province.Through detailed investigation reports and field surveys,six factors were selec...This study develops a geological hazard evaluation index system for Shouning County,a key area for disaster prevention in Fujian Province.Through detailed investigation reports and field surveys,six factors were selected,including elevation,slope gradient,slope aspect,stratigraphic lithological group,distance from the water systems,and geological structures.A geological hazard susceptibility zoning map was created using the Information Quantity Method(IQM).The evaluation showed that elevation,slope aspect,and distance from the water systems are primary risk factors,with high and extremely high susceptibility areas covering 168.57 km^(2)(52.63%of the study area)and a disaster point density of 3.07 points/km^(2).The model achieved an accuracy of 0.73,validating its effectiveness in hazard assessment.These findings provide a valuable reference for disaster prediction and mitigation in Shouning County,supporting improved planning and risk management efforts.展开更多
Numerical simulation plays an important role in the dynamic analysis of multibody system.With the rapid development of computer science,the numerical solution technology has been further developed.Recently,data-driven...Numerical simulation plays an important role in the dynamic analysis of multibody system.With the rapid development of computer science,the numerical solution technology has been further developed.Recently,data-driven method has become a very popular computing method.However,due to lack of necessary mechanism information of the traditional pure data-driven methods based on neural network,its numerical accuracy cannot be guaranteed for strong nonlinear system.Therefore,this work proposes a mechanism-data hybrid-driven strategy for solving nonlinear multibody system based on physics-informed neural network to overcome the limitation of traditional data-driven methods.The strategy proposed in this paper introduces scaling coefficients to introduce the dynamic model of multibody system into neural network,ensuring that the training results of neural network conform to the mechanics principle of the system,thereby ensuring the good reliability of the data-driven method.Finally,the stability,generalization ability and numerical accuracy of the proposed method are discussed and analyzed using three typical multibody systems,and the constrained default situations can be controlled within the range of 10^(-2)-10^(-4).展开更多
Since the plasticity of soil and the irregular shape of the excavation,the efficiency and stability of the traditional local radial basis function(RBF)collocation method(LRBFCM)are inadequate for analyzing three-dimen...Since the plasticity of soil and the irregular shape of the excavation,the efficiency and stability of the traditional local radial basis function(RBF)collocation method(LRBFCM)are inadequate for analyzing three-dimensional(3D)deformation of deep excavation.In this work,the technique known as the direct method,where the local influence nodes are collocated on a straight line,is introduced to optimize the LRBFCM.The direct method can improve the accuracy of the partial derivative,reduce the size effect caused by the large length-width ratio,and weaken the influence of the shape parameters on the LRBFCM.The mapping technique is adopted to transform the physical coordinates of a quadratic-type block to normalized coordinates,in which the deformation problem can easily be solved using the direct method.The stability of the LRBFCM is further modified by considering the irregular shape of 3D excavation,which is divided into several quadratic-type blocks.The soil’s plasticity is described by the Drucker-Prager(D-P)model.The improved LRBFCM is integrated with the incremental method to analyze the plasticity.Five different examples,including strip excavations and circular excavations,are presented to validate the proposed approach’s efficiency.展开更多
Block-flexure toppling constitutes the predominant form of toppling failure in rock slopes.Although it has been extensively studied,the current theoretical models are often oversimplified by treating rock layers as ri...Block-flexure toppling constitutes the predominant form of toppling failure in rock slopes.Although it has been extensively studied,the current theoretical models are often oversimplified by treating rock layers as rigid bodies that diverge from actual conditions.The proposed Equivalent Deformation Compatibility Method(EDCM)offers a fresh approach to assess the stability of rock slopes prone to block-flexure toppling.EDCM posits that blocky rock layers,with their inability to withstand significant bending and role in merely transferring forces,can be modeled as intact layers with a reduced modulus.The method simplifies the complex issue of analyzing discrete and continuous rock layers to the study of layered soft and hard rock,establishing deformation compatibility equations subsequently.Validation of the EDCM was achieved through numerical models,physical model testing,and application to an actual slope.The factor of safety(FS)for slopes corresponds with the results from both models and the actual slope,demonstrating the method's applicability for evaluating susceptibility to block-flexure toppling.When applying the EDCM,it is advised to set the elastic modulus reduction coefficient for blocky layers at a value below 0.1.展开更多
Wet flue gas desulfurization(WFGD)could effectively reduce sulfur dioxide emission.However,magnesium sulfite(MgSO_(3)),a by-product of desulfurization,was easy to result in secondary pollution.In this study,the solid ...Wet flue gas desulfurization(WFGD)could effectively reduce sulfur dioxide emission.However,magnesium sulfite(MgSO_(3)),a by-product of desulfurization,was easy to result in secondary pollution.In this study,the solid catalyst Co-Bent(bentonite supported cobalt)was prepared by blending method for MgSO_(3) oxidation with bentonite as the carrier and cobalt as the active component.At the calcination temperature of 550℃ and the Co loading level of 3 wt.%,the catalyst showed excellent catalytic performance for the oxidation of high concentration MgSO_(3) slurry,and the oxidation rate of MgSO_(3) was 0.13 mol/(L·h).The research indicated that the active component was uniformly distributed within porous structure of the catalyst as Co_(3)O_(4),which facilitated the oxidation of SO_(3)^(2-) catalyzed by Co_(3)O_(4).Kinetic researches indicated the oxidation rate of MgSO_(3) was influenced by the catalyst dosage,the reaction temperature,the solution pH,the airflow rate,and the SO_(3)^(2-) concentration.Additionally,after recycling experiments,the regenerated catalyst retained its high catalytic performance for the MgSO_(3) oxidation.The reaction mechanism for the catalytic oxidation of MgSO_(3) by Co-Bent catalyst was also proposed.The generation of active free radicals(OH·,SO_(4)^(-)·,SO_(3)^(-)·,SO_(5)^(-)·)accelerated the MgSO_(3) oxidation.These results provide theoretical support for the treatment of MgSO_(3) and the development of durable catalyst.展开更多
Nano-scale CuF_(2) with superior electrochemical activity was successfully prepared by a mixed solvent co-precipitation method.The SEM and TEM analyses demonstrated that the methanol concentration had a pronounced eff...Nano-scale CuF_(2) with superior electrochemical activity was successfully prepared by a mixed solvent co-precipitation method.The SEM and TEM analyses demonstrated that the methanol concentration had a pronounced effect on both the particle size and the extent of agglomeration.With the increase in methanol content,the particle size and agglomeration of CuF_(2) decreased first and then increased.When the volume ratio of methanol to deionized water was 1:1,the CuF_(2) particles exhibited the smallest size and the lowest degree of agglomeration.CuF_(2) synthesized with 50%methanol exhibited superior electrochemical performances with a voltage plateau above 3 V and a 1st discharge capacity of 525.8 mAh·g^(-1) at 0.01 C due to the synergistic influence of the particle size and dispersion.The analysis results using electrochemical impedance spectroscopy(EIS)and constant current intermittent titration technique(GITT)affirmed the addition of methanol was beneficial for promoting Li+diffusion and accelerating electrochemical reaction kinetics of CuF_(2).展开更多
基金supported by the National Natural Science Foundation of China(12172023).
文摘The separation-of-variable(SOV)methods,such as the improved SOV method,the variational SOV method,and the extended SOV method,have been proposed by the present authors and coworkers to obtain the closed-form analytical solutions for free vibration and eigenbuckling of rectangular plates and circular cylindrical shells.By taking the free vibration of rectangular thin plates as an example,this work presents the theoretical framework of the SOV methods in an instructive way,and the bisection–based solution procedures for a group of nonlinear eigenvalue equations.Besides,the explicit equations of nodal lines of the SOV methods are presented,and the relations of nodal line patterns and frequency orders are investigated.It is concluded that the highly accurate SOV methods have the same accuracy for all frequencies,the mode shapes about repeated frequencies can also be precisely captured,and the SOV methods do not have the problem of missing roots as well.
文摘Let f be a primitive holomorphic cusp form with even integral weight k≥2 for the full modular groupΓ=SL(2,Z)andλ_(sym^(j)f)(n)be the n-th coefficient of Dirichlet series of j-th symmetric L-function L(s,sym^(j)f)attached to f.In this paper,we study the mean value distribution over a specific sparse sequence of positive integers of the following sum∑(a^(2)+b^(2)+c^(2)+d^(2)≤x(a,b,c,d)∈Z^(4))λ_(sym^(j))^(i)f(a^(2)+b^(2)+c^(2)+d^(2))where j≥2 is a given positive integer,i=2,3,4 andαis sufficiently large.We utilize Python programming to design algorithms for higher power conditions,combining Perron's formula,latest results of representations of natural integers as sums of squares,as well as analytic properties and subconvexity and convexity bounds of automorphic L-functions,to ensure the accuracy and verifiability of asymptotic formulas.The conclusion we obtained improves previous results and extends them to a more general settings.
基金supported by the National Natural Science Foundation of China(Nos.81873092,82174074)。
文摘The self-assembled nanoparticles(SAN)formed during the decoction process of traditional Chinese medicine(TCM)exhibit non-uniform particle sizes and a tendency for aggregation.Our group found that the p H-driven method can improve the self-assembly phenomenon of Herpetospermum caudigerum Wall.,and the SAN exhibited uniform particle size and demonstrated good stability.In this paper,we analyzed the interactions between the main active compound,herpetrione(Her),and its main carrier,Herpetospermum caudigerum Wall.polysaccharide(HCWP),along with their self-assembly mechanisms under different p H values.The binding constants of Her and HCWP increase with rising p H,leading to the formation of Her-HCWP SAN with a smaller particle size,higher zeta potential,and improved thermal stability.While the contributions of hydrogen bonding and electrostatic attraction to the formation of Her-HCWP SAN increase with rising p H,the hydrophobic force consistently plays a dominant role.This study enhances our scientific understanding of the self-assembly phenomenon of TCM improved by p H driven method.
文摘Most material distribution-based topology optimization methods work on a relaxed form of the optimization problem and then push the solution toward the binary limits.However,when benchmarking these methods,researchers use known solutions to only a single form of benchmark problem.This paper proposes a comparison platform for systematic benchmarking of topology optimization methods using both binary and relaxed forms.A greyness measure is implemented to evaluate how far a solution is from the desired binary form.The well-known ZhouRozvany(ZR)problem is selected as the benchmarking problem here,making use of available global solutions for both its relaxed and binary forms.The recently developed non-penalization Smooth-edged Material Distribution for Optimizing Topology(SEMDOT),well-established Solid Isotropic Material with Penalization(SIMP),and continuation methods are studied on this platform.Interestingly,in most cases,the grayscale solutions obtained by SEMDOT demonstrate better performance in dealing with the ZR problem than SIMP.The reasons are investigated and attributed to the usage of two different regularization techniques,namely,the Heaviside smooth function in SEMDOT and the power-law penalty in SIMP.More importantly,a simple-to-use benchmarking graph is proposed for evaluating newly developed topology optimization methods.
基金financially supported by the Natural Science Foundation of Hunan Province,China(No.2024JJ2074)the National Natural Science Foundation of China(No.22376221)the Young Elite Scientists Sponsorship Program by CAST,China(No.2023QNRC001).
文摘Tailings produced by mining and ore smelting are a major source of soil pollution.Understanding the speciation of heavy metals(HMs)in tailings is essential for soil remediation and sustainable development.Given the complex and time-consuming nature of traditional sequential laboratory extraction methods for determining the forms of HMs in tailings,a rapid and precise identification approach is urgently required.To address this issue,a general empirical prediction method for HM occurrence was developed using machine learning(ML).The compositional information of the tailings,properties of the HMs,and sequential extraction steps were used as inputs to calculate the percentages of the seven forms of HMs.After the models were tuned and compared,extreme gradient boosting,gradient boosting decision tree,and categorical boosting methods were found to be the top three performing ML models,with the coefficient of determination(R^(2))values on the testing set exceeding 0.859.Feature importance analysis for these three optimal models indicated that electronegativity was the most important factor affecting the occurrence of HMs,with an average feature importance of 0.4522.The subsequent use of stacking as a model integration method enabled the ability of the ML models to predict HM occurrence forms to be further improved,and resulting in an increase of R^(2) to 0.879.Overall,this study developed a robust technique for predicting the occurrence forms in tailings and provides an important reference for the environmental assessment and recycling of tailings.
基金supported by China Postdoctoral Science Foundation,Grant 2024M753544Science and Technology Project of CSG,Grant GDKJXM2022106.
文摘Improving the computational efficiency of multi-physics simulation and constructing a real-time online simulation method is an important way to realise the virtual-real fusion of entities and data of power equipment with digital twin.In this paper,a datadriven fast calculation method for the temperature field of resin impregnated paper(RIP)bushing used in converter transformer valve-side is proposed,which combines the data dimensionality reduction technology and the surrogate model.After applying the finite element algorithm to obtain the temperature field distribution of RIP bushing under different operation conditions as the input dataset,the proper orthogonal decomposition(POD)algorithm is adopted to reduce the order and obtain the low-dimensional projection of the temperature data.On this basis,the surrogate model is used to construct the mapping relationship between the sensor monitoring data and the low-dimensional projection,so that it can achieve the fast calculation and reconstruction of temperature field distribution.The results show that this method can effectively and quickly calculate the overall temperature field distribution of the RIP bushing.The maximum relative error and the average relative error are less than 4.5%and 0.25%,respectively.The calculation speed is at the millisecond level,meeting the needs of digitalisation of power equipment.
基金National Natural Science Foundation of China(No.22275150)。
文摘To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying method.The morphology,structure and thermal decomposition properties of the samples were analyzed using scanning electron microscopy(SEM),X-ray energy spectroscopy(EDS),infrared spectroscopy(FT-IR),and simultaneous thermal analyzer(TG-DSC).Additionally,the combustion process of the samples was tested using a high-speed camera.The results show that the addition of nano-Si contributes to the formation of composite explosives with regular morphology and smaller particle size.The Si/NC/CL-20 composite explosive has better and more uniform sphericity,with an average particle size of 73.4 nm,compared to the NC/CL-20 composite explosive.The Si/NC/CL-20 composite explosive which produced by the electrostatic spraying method,achieves physically uniform distribution of the components including NC,CL-20,Si.The addition of Si promotes the thermal decomposition of CL-20.In comparison to the NC/CL-20 composite explosive,the activation energy of the Si/NC/CL-20 composite explosive decreases by 16.78 kJ/mol,and the self-accelerated decomposition temperature and the critical temperature of thermal explosion decreases by 3.12 K and 2.61 K,respectively.Furthermore,Si/NC/CL-20 composite explosive has shorter ignition delay time and faster combustion rate compared to the NC/CL-20 composite explosive,which shows that Si can improve the combustion performance of CL-20.
基金funded by the National Key Research and Development Program’s intergovernmental International Science and Technology Innovation Cooperation project,titled Remote Sensing and Radio Astronomy Observation of Space Weather in Low and Middle Latitudes(project number:2022YFE0140000)Supported by International Partnership Program of Chinese Academy of Sciences,grant No.114A11KYSB20200001。
文摘The 21 cm radiation of neutral hydrogen provides crucial information for studying the early universe and its evolution.To advance this research,countries have made significant investments in constructing large lowfrequency radio telescope arrays,such as the Low Frequency Array and the Square Kilometre Array Phase 1 Low Frequency.These instruments are pivotal for radio astronomy research.However,challenges such as ionospheric plasma interference,ambient radio noise,and instrument-related effects have become increasingly prominent,posing major obstacles in cosmology research.To address these issues,this paper proposes an efficient signal processing method that combines wavelet transform and mathematical morphology.The method involves the following steps:Background Subtraction:Background interference in radio observation signals is eliminated.Wavelet Transform:The signal,after removing background noise,undergoes a two-dimensional discrete wavelet transform.Threshold processing is then applied to the wavelet coefficients to effectively remove interference components.Wavelet Inversion:The processed signal is reconstructed using wavelet inversion.Mathematical Morphology:The reconstructed signal is further optimized using mathematical morphology to refine the results.Experimental verification was conducted using solar observation data from the Xinjiang Observatory and the Yunnan Observatory.The results demonstrate that this method successfully removes interference signals while preserving useful signals,thus improving the accuracy of radio astronomy observations and reducing the impact of radio frequency interference.
基金Chongqing Institute of Engineering 2023 Education Teaching Reform Research Project,“Exploration of Teaching Methods Reform of Plant Configuration and Landscape Architecture Curriculum under Digital Technology”(Project No.:JY2023214)Chongqing Institute of Engineering 2023 First-class Curriculum Construction Project,“Plant Configuration and Landscape Architecture”(Project No.:KC20230103)。
文摘By analyzing the urgent demand for digital talents in the current landscape industry and the challenges faced by the traditional teaching mode,this study aims to explore a set of teaching methodology reform solutions based on digital technology to improve the quality of teaching and enhance the practical innovation ability of students.The study firstly describes the application of digital technologies such as CAD/BIM,3D modelling and rendering,virtual reality(VR)/augmented reality(AR),and geographic information system(GIS)in the field of landscape architecture.Then,the current teaching status of plant configuration and landscape architecture courses is analyzed,and the advantages and challenges of digital technology applications are identified.On this basis,this study proposes a multi-dimensional reform path and practice plan including the reconstruction of teaching objectives and content,innovation of teaching mode,improvement of teaching strategies and methods,as well as the construction of teaching resources and the reform of teaching evaluation,guided by modern educational theories such as constructivism,collaborative learning and project-based learning(PBL).Finally,this study emphasizes the key roles of faculty construction,optimization of hardware and software environment,and teaching management and institutional guarantee in the reform.
基金Project supported by the National Natural Science Foundation of China(Grant No.62464013)。
文摘This study achieves a notable enhancement in the thermoelectric performance of copper selenide compounds exhibiting liquid-like characteristics via an innovative processing method.A KCl flux-assisted high-temperature melting and slow-cooling strategy was employed to fabricate nanolayered Cu_(2)Se(KCl)_(x)materials(x=0-3,denoted as S_(0)-S_(3)).Systematic characterization reveals that the coexistence ofαandβphases at room temperature creates favorable conditions for optimizing carrier transport.XPS analysis confirms the substitution of low-binding-energy Se_(2)-by high-binding-energy Cl^(-)ions within the lattice,effectively suppressing copper ion migration and remarkably improving the material's structural stability.Microstructural investigations demonstrate that all samples exhibit nanolayered stacking architectures abundant with edge dislocations.This multiscale defect architecture induces strong phonon scattering effects.Hall measurements indicate that the KCl flux-assisted processing facilitates the formation of highly ordered nanostructures,thereby enhancing carrier mobility and structural stability.Although the carrier concentration exhibits a slight decrease compared with the flux-free samples,the significant improvement in microstructural quality plays a crucial role in the synergistic optimization of electrical conductivity and the Seebeck coefficient.Notably,sample S_(2)exhibited a considerable electrical conductivity,reaching approximately 1.0×10^(5)S·m^(-1)at 300 K.More strikingly,the cooperative effect of high-density edge dislocations and dopant atoms elevates material entropy,enabling sample S_(3)to attain an ultralow lattice thermal conductivity of 0.55 W·m^(-1)·K^(-1)at 350 K.Through multi-mechanism coordination,sample S_(2)achieved a high ZT value of 1.45 at 700 K,representing a 2.7-fold improvement compared with traditional synthesis methods.This work provides new insights into performance optimization of liquid-like thermoelectric materials through defect engineering and entropy manipulation.
基金Sponsored by The Youth Project of National Social Science Foundation of China(21CTY007)Special Fund for Basic Scientific Research Business Expenses of Central Universities(2024DAWH008).
文摘With Beijing Huilongguan Sports and Cultural Park as the research object,this study was conducted to investigate public service satisfaction in the park by the Importance-Performance Analysis(IPA)method.A questionnaire covering six dimensions,including public transportation,sanitation and environment,and supporting facility construction,was designed.A total of 208 valid samples were collected,and SPSS was employed for reliability and validity tests as well as IPA analysis.The findings were as follows:①Visitors were generally quite satisfied with the overall public services in Huilongguan Sports and Cultural Park.②The highest satisfaction levels were observed in sanitation and environment services and the sports and cultural atmosphere,while lower satisfaction was noted for supporting facility construction and public information services.③The advantage enhancement zone includes sanitation and environment services and sports and cultural atmosphere;and the continuous maintenance zone includes public transportation services and security management amd maintenance;the subsequent opportunity zone includes supporting facility construction and public information services;and there are no dimensions in the urgent improvement zone.The study recommends strengthening the service connotations from three aspects:enhancing facilities with sports as the core,optimizing services with a people-centered approach,and upgrading the information platform through technological efficiency.Additionally,a multi-stakeholder collaborative mechanism involving the government in coordinating policy resources,the operator in improving implementation efficiency,and the public participating in supervision and evaluation is proposed to drive the enhancement of public service quality at Huilongguan Sports and Cultural Park.
基金supported by the National Natural Science Foundation of China(No.42277175)Guangxi Emergency Management Department 2024 Innovation and Technology Research Project,China(No.2024GXYJ006)+2 种基金Hunan Provincial Department of Natural Resources Geological Exploration Project,China(No.2023ZRBSHZ056)The First National Natural Disaster Comprehensive Risk Survey in Hunan Province,China(No.2022-70)Guizhou Provincial Major Scientific and Technological Program,China(No.2023-425).
文摘A method combining finite difference method(FDM)and k-means clustering algorithm which can determine the threshold of rock bridge generation is proposed.Jointed slope models with different joint coalescence coefficients(k)are constructed based on FDM.The rock bridge area was divided through k-means algorithm and the optimal number of clusters was determined by sum of squared errors(SSE)and elbow method.The influence of maximum principal stress and stress change rate as clustering indexes on the clustering results of rock bridges was compared by using Euclidean distance.The results show that using stress change rate as clustering index is more effective.When the joint coalescence coefficient is less than 0.6,there is no significant stress concentration in the middle area of adjacent joints,that is,no generation of rock bridge.In addition,the range of rock bridge is affected by the coalescence coefficient(k),the relative position of joints and the parameters of weak interlayer.
基金Supported by Shanxi Province Natural Science Research(202203021212249)Special/Youth Foundation of Taiyuan University of Technology(2022QN101)+3 种基金National Natural Science Foundation of China(12301556)Research Project Supported by Shanxi Scholarship Council of China(2021-029)International Cooperation Base and Platform Project of Shanxi Province(202104041101019)Basic Research Plan of Shanxi Province(202203021211129)。
文摘To enhance the computational efficiency of spatio-temporally discretized phase-field models,we present a high-speed solver specifically designed for the Poisson equations,a component frequently used in the numerical computation of such models.This efficient solver employs algorithms based on discrete cosine transformations(DCT)or discrete sine transformations(DST)and is not restricted by any spatio-temporal schemes.Our proposed methodology is appropriate for a variety of phase-field models and is especially efficient when combined with flow field systems.Meanwhile,this study has conducted an extensive numerical comparison and found that employing DCT and DST techniques not only yields results comparable to those obtained via the Multigrid(MG)method,a conventional approach used in the resolution of the Poisson equations,but also enhances computational efficiency by over 90%.
基金supported by the National Natural Science(No.U19A2063)the Jilin Provincial Development Program of Science and Technology (No.20230201080GX)the Jilin Province Education Department Scientific Research Project (No.JJKH20230851KJ)。
文摘The visual noise of each light intensity area is different when the image is drawn by Monte Carlo method.However,the existing denoising algorithms have limited denoising performance under complex lighting conditions and are easy to lose detailed information.So we propose a rendered image denoising method with filtering guided by lighting information.First,we design an image segmentation algorithm based on lighting information to segment the image into different illumination areas.Then,we establish the parameter prediction model guided by lighting information for filtering(PGLF)to predict the filtering parameters of different illumination areas.For different illumination areas,we use these filtering parameters to construct area filters,and the filters are guided by the lighting information to perform sub-area filtering.Finally,the filtering results are fused with auxiliary features to output denoised images for improving the overall denoising effect of the image.Under the physically based rendering tool(PBRT)scene and Tungsten dataset,the experimental results show that compared with other guided filtering denoising methods,our method improves the peak signal-to-noise ratio(PSNR)metrics by 4.2164 dB on average and the structural similarity index(SSIM)metrics by 7.8%on average.This shows that our method can better reduce the noise in complex lighting scenesand improvethe imagequality.
基金2024 Guiding Science and Technology Program of Fujian Province(No.2024H0026)2025 Innovation Fund Project of Fujian Province(No.2025C0004).
文摘This study develops a geological hazard evaluation index system for Shouning County,a key area for disaster prevention in Fujian Province.Through detailed investigation reports and field surveys,six factors were selected,including elevation,slope gradient,slope aspect,stratigraphic lithological group,distance from the water systems,and geological structures.A geological hazard susceptibility zoning map was created using the Information Quantity Method(IQM).The evaluation showed that elevation,slope aspect,and distance from the water systems are primary risk factors,with high and extremely high susceptibility areas covering 168.57 km^(2)(52.63%of the study area)and a disaster point density of 3.07 points/km^(2).The model achieved an accuracy of 0.73,validating its effectiveness in hazard assessment.These findings provide a valuable reference for disaster prediction and mitigation in Shouning County,supporting improved planning and risk management efforts.
基金supported by the National Natural Science Foundation of China(Grant No.U2241263)the fellowship of China Postdoctoral Science Foundation(Grant No.2024M750310).
文摘Numerical simulation plays an important role in the dynamic analysis of multibody system.With the rapid development of computer science,the numerical solution technology has been further developed.Recently,data-driven method has become a very popular computing method.However,due to lack of necessary mechanism information of the traditional pure data-driven methods based on neural network,its numerical accuracy cannot be guaranteed for strong nonlinear system.Therefore,this work proposes a mechanism-data hybrid-driven strategy for solving nonlinear multibody system based on physics-informed neural network to overcome the limitation of traditional data-driven methods.The strategy proposed in this paper introduces scaling coefficients to introduce the dynamic model of multibody system into neural network,ensuring that the training results of neural network conform to the mechanics principle of the system,thereby ensuring the good reliability of the data-driven method.Finally,the stability,generalization ability and numerical accuracy of the proposed method are discussed and analyzed using three typical multibody systems,and the constrained default situations can be controlled within the range of 10^(-2)-10^(-4).
基金supported by grants from the National Natural Science Foundation of China(Nos.12172159 and 12362019).
文摘Since the plasticity of soil and the irregular shape of the excavation,the efficiency and stability of the traditional local radial basis function(RBF)collocation method(LRBFCM)are inadequate for analyzing three-dimensional(3D)deformation of deep excavation.In this work,the technique known as the direct method,where the local influence nodes are collocated on a straight line,is introduced to optimize the LRBFCM.The direct method can improve the accuracy of the partial derivative,reduce the size effect caused by the large length-width ratio,and weaken the influence of the shape parameters on the LRBFCM.The mapping technique is adopted to transform the physical coordinates of a quadratic-type block to normalized coordinates,in which the deformation problem can easily be solved using the direct method.The stability of the LRBFCM is further modified by considering the irregular shape of 3D excavation,which is divided into several quadratic-type blocks.The soil’s plasticity is described by the Drucker-Prager(D-P)model.The improved LRBFCM is integrated with the incremental method to analyze the plasticity.Five different examples,including strip excavations and circular excavations,are presented to validate the proposed approach’s efficiency.
基金financially supported by Youth Innovation Promotion Association,CAS(Grant No.2022333)Knowledge Innovation Program of Wuhan e Basic Research(Grant No.2022010801010161)Natural Science Foundation of Hubei Province,China(Grant No.2023AFD219).
文摘Block-flexure toppling constitutes the predominant form of toppling failure in rock slopes.Although it has been extensively studied,the current theoretical models are often oversimplified by treating rock layers as rigid bodies that diverge from actual conditions.The proposed Equivalent Deformation Compatibility Method(EDCM)offers a fresh approach to assess the stability of rock slopes prone to block-flexure toppling.EDCM posits that blocky rock layers,with their inability to withstand significant bending and role in merely transferring forces,can be modeled as intact layers with a reduced modulus.The method simplifies the complex issue of analyzing discrete and continuous rock layers to the study of layered soft and hard rock,establishing deformation compatibility equations subsequently.Validation of the EDCM was achieved through numerical models,physical model testing,and application to an actual slope.The factor of safety(FS)for slopes corresponds with the results from both models and the actual slope,demonstrating the method's applicability for evaluating susceptibility to block-flexure toppling.When applying the EDCM,it is advised to set the elastic modulus reduction coefficient for blocky layers at a value below 0.1.
基金supported by the State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology (No. 2022TS10)the Taishan Industrial Experts Programthe Natural Science Foundation of Shandong Province of China (No. ZR2023ME212).
文摘Wet flue gas desulfurization(WFGD)could effectively reduce sulfur dioxide emission.However,magnesium sulfite(MgSO_(3)),a by-product of desulfurization,was easy to result in secondary pollution.In this study,the solid catalyst Co-Bent(bentonite supported cobalt)was prepared by blending method for MgSO_(3) oxidation with bentonite as the carrier and cobalt as the active component.At the calcination temperature of 550℃ and the Co loading level of 3 wt.%,the catalyst showed excellent catalytic performance for the oxidation of high concentration MgSO_(3) slurry,and the oxidation rate of MgSO_(3) was 0.13 mol/(L·h).The research indicated that the active component was uniformly distributed within porous structure of the catalyst as Co_(3)O_(4),which facilitated the oxidation of SO_(3)^(2-) catalyzed by Co_(3)O_(4).Kinetic researches indicated the oxidation rate of MgSO_(3) was influenced by the catalyst dosage,the reaction temperature,the solution pH,the airflow rate,and the SO_(3)^(2-) concentration.Additionally,after recycling experiments,the regenerated catalyst retained its high catalytic performance for the MgSO_(3) oxidation.The reaction mechanism for the catalytic oxidation of MgSO_(3) by Co-Bent catalyst was also proposed.The generation of active free radicals(OH·,SO_(4)^(-)·,SO_(3)^(-)·,SO_(5)^(-)·)accelerated the MgSO_(3) oxidation.These results provide theoretical support for the treatment of MgSO_(3) and the development of durable catalyst.
文摘Nano-scale CuF_(2) with superior electrochemical activity was successfully prepared by a mixed solvent co-precipitation method.The SEM and TEM analyses demonstrated that the methanol concentration had a pronounced effect on both the particle size and the extent of agglomeration.With the increase in methanol content,the particle size and agglomeration of CuF_(2) decreased first and then increased.When the volume ratio of methanol to deionized water was 1:1,the CuF_(2) particles exhibited the smallest size and the lowest degree of agglomeration.CuF_(2) synthesized with 50%methanol exhibited superior electrochemical performances with a voltage plateau above 3 V and a 1st discharge capacity of 525.8 mAh·g^(-1) at 0.01 C due to the synergistic influence of the particle size and dispersion.The analysis results using electrochemical impedance spectroscopy(EIS)and constant current intermittent titration technique(GITT)affirmed the addition of methanol was beneficial for promoting Li+diffusion and accelerating electrochemical reaction kinetics of CuF_(2).
