【目的】在空间超冗余机械臂动力学建模中,其结构复杂、自由度多及刚性弱导致的动力学耦合问题十分突出,难以获得精准的动力学模型。针对此问题,提出了一种应用迭代WLS-TCS算法的空间超冗余机械臂地面动力学参数辨识方法,为获取机械臂...【目的】在空间超冗余机械臂动力学建模中,其结构复杂、自由度多及刚性弱导致的动力学耦合问题十分突出,难以获得精准的动力学模型。针对此问题,提出了一种应用迭代WLS-TCS算法的空间超冗余机械臂地面动力学参数辨识方法,为获取机械臂的高精度动力学模型和空间在轨动力学控制研究奠定基础。【方法】首先,采用一种基于终端交叉和转向的粒子群优化(Terminal Crossover and Steering-based Particle Swarm Optimization,TCS-PSO)算法来设计满足多约束条件的周期傅里叶级数,并将其作为最优的激励轨迹;其次,应用迭代加权最小二乘(Iterative Weighted Least Squares,IWLS)法获取最小参数集,通过迭代加权逐步剔除数据中的异常值,使得辨识结果更加鲁棒、准确。【结果】试验结果表明,在激励轨迹中,采用TCS优化方法获得的轨迹回归矩阵条件数更少,且能更好满足所给的约束条件。在参数辨识中,采用IWLS法辨识所得的结果对比递归最小二乘法,力矩残差均方根(Root Mean Square,RMS)值平均降低约2.22%;对比加权最小二乘法,力矩残差RMS值平均降低约4.85%。将获取的参数模型代入到零力控制试验中,实际效果符合预期。展开更多
Open and green spaces are essential elements of cities.With the COVID epidemic,the importance of the need for open and green spaces in urban areas has become more understood.The aim of this study is to create a new an...Open and green spaces are essential elements of cities.With the COVID epidemic,the importance of the need for open and green spaces in urban areas has become more understood.The aim of this study is to create a new and contemporary square in the working area where the current use and traffic create chaos,to add a new square to the open and green areas in Ankara(Turkey)and to create a connection between this area and the existing open and green areas.At the same time,health workers are honoured through a memorial area integrated into the square.The importance of the location chosen as the study area is that it is surrounded by many public health facilities and is a point of intersection of Ankara’s existing open green space systems.Throughout the three-stage design process,brainstorming sessions were held,drawings and sketches were made,and urban analyses were carried out on transport,culture,art,education,health,open and green spaces.Solutions were proposed for both indoor and outdoor spaces,and the forms were transformed into functional design elements and reflected in the space.As a result,after the pandemic,a city square has been created where people can socialise again,with a monument,a square,water surfaces,an amphitheatre,viewing terraces,a market area,a bridge,sitting and walking areas that are appropriate to the capital.展开更多
Recently,there have been few reports on the hot extrusion process of magnesium(Mg)alloy square tubes.In this work,we introduce a novel hot extrusion process called tube continuous expanding shear extrusion(t CESE)to p...Recently,there have been few reports on the hot extrusion process of magnesium(Mg)alloy square tubes.In this work,we introduce a novel hot extrusion process called tube continuous expanding shear extrusion(t CESE)to produce Mg alloy square tubes with heterogeneous structures.Compared to previously reported hot-extruded Mg alloy tubes,the tCESE samples exhibit simultaneous enhancements in both strength and ductility.The microstructure evolution during the t CESE process was analyzed in detail.It was found that the microstructure developed consecutively as a result of twinning-induced dynamic recrystallization(TDRX),discontinuous dynamic recrystallization(DDRX)and continuous dynamic recrystallization(CDRX)with different nucleation of new orientations,while static recrystallization(SRX)promoted the formation of heterogeneous structures.The strengthening mechanism in the t CESE samples was revealed by loading-unloading-reloading(LUR)tensile tests,viscoplastic self-consistent(VPSC)simulation and intermittent tensile tests.The improvement of the strength in the tCESE samples is attributed to the size refinement of the grains and the second-phases,and more importantly,to hetero-deformation induced(HDI)strengthening.The improvement of the ductility in the t CESE samples can be attributed to the significant increase in non-basal dislocations within the heterogeneous structures during tensile deformation.展开更多
The three-dimensional(3D)synthetic space offers a platform for exploring the valley Hall insulator,which is usually constructed in graphene lattice.Here,based on the valley transports in the square lattice,we construc...The three-dimensional(3D)synthetic space offers a platform for exploring the valley Hall insulator,which is usually constructed in graphene lattice.Here,based on the valley transports in the square lattice,we construct a synthetic space by treating the rotation angle as the third dimension and observe the emergent Weyl points in this synthetic space.Since the construction of synthetic Weyl points results in the formation of edge states between the phononic crystal(PC)and the hard boundary,and the factors of rotation angle and the distance from the PC to the hard boundary affect the frequency of these edge states,we can construct topological rainbow concentrator based on the above principles.We conduct a comprehensive numerical and experimental study to explore the characteristics of topological rainbow concentrators.This work may play a driving role in the development of topological rainbow devices.展开更多
The total nitrogen(TN)is a major factor contributing to eutrophication and is a crucial parameter in assessing surface water quality.Accurate and rapid methods are crucial for determining the TN content in water.Herei...The total nitrogen(TN)is a major factor contributing to eutrophication and is a crucial parameter in assessing surface water quality.Accurate and rapid methods are crucial for determining the TN content in water.Herein,a fast,highly sensitive,and pollution-free approach is proposed,which combines ultraviolet(UV)absorption spectroscopy with Bayesian optimized least squares support vector machine(LSSVM)for detecting TN content in water.Water samples collected from sampling points near the Yangtze River basin in Chongqing of China were analyzed using national standard methods to measure TN content as reference values.The prediction of TN content in water was achieved by integrating the UV absorption spectra of water samples with LSSVM.To make the model quickly and accurately select the optimal parameters to improve the accuracy of the prediction model,the Bayesian optimization(BO)algorithm was used to optimize the parameters of the LSSVM.Results show that the prediction model performs well in predicting TN concentration,with a high coefficient of prediction determination(R^(2)=0.9413)and a low root mean square error of prediction(RMSE=0.0779 mg/L).Comparative analysis with previous studies indicates that the model used in this paper achieves lower prediction errors and superior predictive performance.展开更多
Equations(2)and(6)and the corresponding discussion in the paper[Chin.Phys.Lett.42,056301(2025)]have been corrected.These modiffcations do not affect the results derived in the paper.
Nuclear mass is an important property in both nuclear and astrophysics.In this study,we explore an improved mass model that incorporates a higher-order term of symmetry energy using algorithms.The sequential least squ...Nuclear mass is an important property in both nuclear and astrophysics.In this study,we explore an improved mass model that incorporates a higher-order term of symmetry energy using algorithms.The sequential least squares programming(SLSQP)algorithm augments the precision of this multinomial mass model by reducing the error from 1.863 MeV to 1.631 MeV.These algorithms were further examined using 200 sample mass formulae derived from theδE term of the E_(isospin) mass model.The SLSQP method exhibited superior performance compared to the other algorithms in terms of errors and convergence speed.This algorithm is advantageous for handling large-scale multiparameter optimization tasks in nuclear physics.展开更多
Flow characteristics around a wall-mounted square cylinder have been numerically simulated at aspect ratios (AR) ranging from 4 to 7 at Re =10 000. Four turbulence models have been compared in terms of drag coefficien...Flow characteristics around a wall-mounted square cylinder have been numerically simulated at aspect ratios (AR) ranging from 4 to 7 at Re =10 000. Four turbulence models have been compared in terms of drag coefficient (C_D). The closest result has been provided by two turbulence models, namely, k-ε Realizable and k ?ω Shear Stress Transport (SST). Hence, these models were utilized to present the flow patterns of pressure distributions, turbulent kinetic energy values, velocity magnitude values with streamlines, streamwise velocity components, crossstream velocity components and spanwise velocity components on different planes. Flow stagnation has been attained in front of the cylinder. Pressure values peaked for the upstream region. Over the cylinders, the tip vortex structure was dominant owing to the influence of the free end. Flow separation from the top front edge of the body has been obtained. The dividing streamline affected by the flow separation was highly effective in the wake region and moved nearer to the body when the aspect ratio was decreased;the reason was the wake shrinkage owing to the decreasing aspect ratio. Upwash and downwash have been seen in the cylinder wake. These two models presented similar flow patterns and drag coefficients. These drag coefficients are in good agreement with those in previous studies.展开更多
The exchange and mutual appreciation of different cultures is an important topic in the context of globalization,and traditional patterns are the crystallization of the national cultures of various countries.The study...The exchange and mutual appreciation of different cultures is an important topic in the context of globalization,and traditional patterns are the crystallization of the national cultures of various countries.The study focuses on the Ming Dynasty Mandarin square in ancient China and the Tudor Dynasty coat of arms during the same period in England.By using comparative research,case studies,and combining historical documents and images,the origins of the two types of decorations are traced,and their social connotations and influencing factors are analyzed.Research has shown that under the influence of the historical backgrounds of politics,economy,and culture,the two types of decorative patterns exhibit a realistic aesthetic trend.The cultural connotations not only demonstrate social narrative functions such as customs and rituals,but also reflect political system functions such as hierarchy and honor.The different historical origins give rise to cultural differences in the selection of decorative elements between the two.The comparative study of the two is not only beneficial for conducting decorative design research from a global perspective,but also can promote the modern inheritance of traditional patterns while seeking common ground and reserving differences.展开更多
Aeromagnetic compensation is one of the key issues in high-precision geomagnetic fl ight carrier navigation, directly determining the accuracy and reliability of real-time magnetic measurement data. The accurate model...Aeromagnetic compensation is one of the key issues in high-precision geomagnetic fl ight carrier navigation, directly determining the accuracy and reliability of real-time magnetic measurement data. The accurate modeling and compensation of interference magnetic measurements on carriers are of great signifi cance for the construction of reference and real-time maps for geomagnetic navigation. Current research on aeromagnetic compensation algorithms mainly focuses on accurately modeling interference magnetic fields from model- and data-driven perspectives based on measured aeromagnetic data. Challenges in obtaining aeromagnetic data and low information complexity adversely aff ect the generalization performance of a constructed model. To address these issues, a recursive least square algorithm based on elastic weight consolidation is proposed, which eff ectively suppresses the occurrence of catastrophic forgetting by controlling the direction of parameter updates. Experimental verifi cation with publicly available aeromagnetic datasets shows that the proposed algorithm can eff ectively circumvent historical information loss caused by interference magnetic field models during parameter updates and improve the stability, robustness, and accuracy of interference magnetic fi eld models.展开更多
In the variance component estimation(VCE)of geodetic data,the problem of negative VCE is likely to occur.In the ordinary additive error model,there have been related studies to solve the problem of negative variance c...In the variance component estimation(VCE)of geodetic data,the problem of negative VCE is likely to occur.In the ordinary additive error model,there have been related studies to solve the problem of negative variance components.However,there is still no related research in the mixed additive and multiplicative random error model(MAMREM).Based on the MAMREM,this paper applies the nonnegative least squares variance component estimation(NNLS-VCE)algorithm to this model.The correlation formula and iterative algorithm of NNLS-VCE for MAMREM are derived.The problem of negative variance in VCE for MAMREM is solved.This paper uses the digital simulation example and the Digital Terrain Mode(DTM)to prove the proposed algorithm's validity.The experimental results demonstrated that the proposed algorithm can effectively correct the VCE in MAMREM when there is a negative VCE.展开更多
This study presents a closed-form solution for central stress,a semi-analytical model,and a modified anisotropic semi-analytical model to efficiently calculate the forcefrequency coefficients(FFCs)of square quartz cry...This study presents a closed-form solution for central stress,a semi-analytical model,and a modified anisotropic semi-analytical model to efficiently calculate the forcefrequency coefficients(FFCs)of square quartz crystal resonators(QCRs)with different side lengths and azimuth angles under eccentrically concentrated and distributed loads.The semi-analytical model is validated by comparisons between the experimental results and the nonlinear finite element method(FEM)simulation results.Based on the semi-analytical model for the FFC and nonlinear FEM simulations,the FFC variations of square QCRs under external loads and the related mechanisms are investigated.Among the initial stresses caused by external loads,the central stress parallel to the xcrystallographic axis is the primary factor influencing the FFC of quartz.Our findings can provide practical tools for calculating the FFC,and help the design and development of square quartz force sensors.展开更多
Sodium-ion batteries are receiving more and more attention due to their low cost and abundant sodium storage capacity,and are considered to be a promising alternative to lithium-ion batteries.A large number of studies...Sodium-ion batteries are receiving more and more attention due to their low cost and abundant sodium storage capacity,and are considered to be a promising alternative to lithium-ion batteries.A large number of studies have shown that constructing heterostructures are considered an effective strategy to solve the hysteresis problem of electronic and ion dynamics in sodiumion battery anode materials.Herein,a nickel-cobalt bimetallic coordination polymer(NiCoCP)was synthesized using a coprecipitation method,and a CoSe_(2)@NiSe_(2) cross-stacked structure was obtained through high-temperature carbonization and selenization processes.CoSe_(2)@NiSe_(2) has a unique heterostructure and carbon film,which synergistically increases a large number of adsorption sites and alleviates the diffusion energy barrier,thereby improving the rapid diffusion kinetics of Na^(+)ions.It has superior rate performance and long-lasting cycle life.For sodium-ion batteries(SIBs),the specific capacity of CoSe_(2)@NiSe_(2) is around 460 mA h g^(-1) after 400 cycles at 1.0 A g^(-1).For potassium-ion batteries(PIBs),CoSe_(2)@NiSe_(2) also exhibits excellent cycling stability,maintaining a specific capacity of 160 mA h g^(-1) after 700 cycles at 1.0 A g^(-1).This study provides a new way to prepare metal selenide heterostructure as the promising anode material for SIBs.展开更多
针对压电陶瓷的迟滞非线性,建立了基于一种加权最小二乘支持向量机(Weighted Least Squares Support Vector Machine,WLS-SVM)的迟滞动态模型。为了能够方便使用支持向量机,应用了一种动态算子,将迟滞的多值映射变成一一映射。并在传统...针对压电陶瓷的迟滞非线性,建立了基于一种加权最小二乘支持向量机(Weighted Least Squares Support Vector Machine,WLS-SVM)的迟滞动态模型。为了能够方便使用支持向量机,应用了一种动态算子,将迟滞的多值映射变成一一映射。并在传统的最小二乘支持向量机(Least Squares Support Vector Machine,LS-SVM)的基础上加入了支持向量度,以区分数据的重要程度。为了减轻计算量,将数据按照支持向量度从大到小排序,其中支持向量度接近于零的数据被视作非支持向量。使用剪枝法按一定比例减去支持向量度比较小的数据,利用粒子群算法(Particle Swarm Optimization, PSO)辨识出模型的未知参数。最后,实验的结果验证了模型的可行性。展开更多
We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the st...We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the stimulated Raman-induced photoassociation and square-optical-lattice potential.Stationary solutions of the coupled GPE system are obtained by means of the imaginary-time integration,while the temporal dynamics are simulated using the fourth-order Runge-Kutta algorithm.The analysis reveals stable rhombus-shaped VS shapes with topological charges m=1 and 2 of the atomic component.The stability domains and spatial structure of these VSs are governed by three key parameters:the parametric-coupling strength(χ),atomicmolecular interaction strength(g_(12)),and the optical-lattice potential depth(V_(0)).By varyingχand g_(12),we demonstrate a structural transition where four-core rhombus-shaped VSs evolve into eight-core square-shaped modes,highlighting the nontrivial nonlinear dynamics of the system.This work establishes a connection between interactions of cold atoms and topologically structured matter waves in hybrid quantum systems.展开更多
文摘【目的】在空间超冗余机械臂动力学建模中,其结构复杂、自由度多及刚性弱导致的动力学耦合问题十分突出,难以获得精准的动力学模型。针对此问题,提出了一种应用迭代WLS-TCS算法的空间超冗余机械臂地面动力学参数辨识方法,为获取机械臂的高精度动力学模型和空间在轨动力学控制研究奠定基础。【方法】首先,采用一种基于终端交叉和转向的粒子群优化(Terminal Crossover and Steering-based Particle Swarm Optimization,TCS-PSO)算法来设计满足多约束条件的周期傅里叶级数,并将其作为最优的激励轨迹;其次,应用迭代加权最小二乘(Iterative Weighted Least Squares,IWLS)法获取最小参数集,通过迭代加权逐步剔除数据中的异常值,使得辨识结果更加鲁棒、准确。【结果】试验结果表明,在激励轨迹中,采用TCS优化方法获得的轨迹回归矩阵条件数更少,且能更好满足所给的约束条件。在参数辨识中,采用IWLS法辨识所得的结果对比递归最小二乘法,力矩残差均方根(Root Mean Square,RMS)值平均降低约2.22%;对比加权最小二乘法,力矩残差RMS值平均降低约4.85%。将获取的参数模型代入到零力控制试验中,实际效果符合预期。
文摘Open and green spaces are essential elements of cities.With the COVID epidemic,the importance of the need for open and green spaces in urban areas has become more understood.The aim of this study is to create a new and contemporary square in the working area where the current use and traffic create chaos,to add a new square to the open and green areas in Ankara(Turkey)and to create a connection between this area and the existing open and green areas.At the same time,health workers are honoured through a memorial area integrated into the square.The importance of the location chosen as the study area is that it is surrounded by many public health facilities and is a point of intersection of Ankara’s existing open green space systems.Throughout the three-stage design process,brainstorming sessions were held,drawings and sketches were made,and urban analyses were carried out on transport,culture,art,education,health,open and green spaces.Solutions were proposed for both indoor and outdoor spaces,and the forms were transformed into functional design elements and reflected in the space.As a result,after the pandemic,a city square has been created where people can socialise again,with a monument,a square,water surfaces,an amphitheatre,viewing terraces,a market area,a bridge,sitting and walking areas that are appropriate to the capital.
基金the National Science Foundation of China(52071042)Chongqing Talent Plan(CQYC202003047)+1 种基金the Chongqing Natural Science Foundation Project of CSTB2021YCJH-BGZXM0148 and CSTB2023NSCQ-MSX0079the Open Fund of the National Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle,Hunan University(Grant No.82315001)。
文摘Recently,there have been few reports on the hot extrusion process of magnesium(Mg)alloy square tubes.In this work,we introduce a novel hot extrusion process called tube continuous expanding shear extrusion(t CESE)to produce Mg alloy square tubes with heterogeneous structures.Compared to previously reported hot-extruded Mg alloy tubes,the tCESE samples exhibit simultaneous enhancements in both strength and ductility.The microstructure evolution during the t CESE process was analyzed in detail.It was found that the microstructure developed consecutively as a result of twinning-induced dynamic recrystallization(TDRX),discontinuous dynamic recrystallization(DDRX)and continuous dynamic recrystallization(CDRX)with different nucleation of new orientations,while static recrystallization(SRX)promoted the formation of heterogeneous structures.The strengthening mechanism in the t CESE samples was revealed by loading-unloading-reloading(LUR)tensile tests,viscoplastic self-consistent(VPSC)simulation and intermittent tensile tests.The improvement of the strength in the tCESE samples is attributed to the size refinement of the grains and the second-phases,and more importantly,to hetero-deformation induced(HDI)strengthening.The improvement of the ductility in the t CESE samples can be attributed to the significant increase in non-basal dislocations within the heterogeneous structures during tensile deformation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074184,12274219,and 11934009)the Key Research and Development Project of Jiangsu Province,China(Grant No.BE2022814)。
文摘The three-dimensional(3D)synthetic space offers a platform for exploring the valley Hall insulator,which is usually constructed in graphene lattice.Here,based on the valley transports in the square lattice,we construct a synthetic space by treating the rotation angle as the third dimension and observe the emergent Weyl points in this synthetic space.Since the construction of synthetic Weyl points results in the formation of edge states between the phononic crystal(PC)and the hard boundary,and the factors of rotation angle and the distance from the PC to the hard boundary affect the frequency of these edge states,we can construct topological rainbow concentrator based on the above principles.We conduct a comprehensive numerical and experimental study to explore the characteristics of topological rainbow concentrators.This work may play a driving role in the development of topological rainbow devices.
基金supported by the National Natural Science Foundation of China(Nos.32171627 and 62105252)the Science and Technology Research Program of Chongqing Municipal Education Commission(No.KJZD-M202200602)the Hangzhou Science and Technology Development Project(No.202204T04).
文摘The total nitrogen(TN)is a major factor contributing to eutrophication and is a crucial parameter in assessing surface water quality.Accurate and rapid methods are crucial for determining the TN content in water.Herein,a fast,highly sensitive,and pollution-free approach is proposed,which combines ultraviolet(UV)absorption spectroscopy with Bayesian optimized least squares support vector machine(LSSVM)for detecting TN content in water.Water samples collected from sampling points near the Yangtze River basin in Chongqing of China were analyzed using national standard methods to measure TN content as reference values.The prediction of TN content in water was achieved by integrating the UV absorption spectra of water samples with LSSVM.To make the model quickly and accurately select the optimal parameters to improve the accuracy of the prediction model,the Bayesian optimization(BO)algorithm was used to optimize the parameters of the LSSVM.Results show that the prediction model performs well in predicting TN concentration,with a high coefficient of prediction determination(R^(2)=0.9413)and a low root mean square error of prediction(RMSE=0.0779 mg/L).Comparative analysis with previous studies indicates that the model used in this paper achieves lower prediction errors and superior predictive performance.
文摘Equations(2)and(6)and the corresponding discussion in the paper[Chin.Phys.Lett.42,056301(2025)]have been corrected.These modiffcations do not affect the results derived in the paper.
基金supported by the National Natural Science Foundation of China(Nos.U2267205 and 12475124)a ZSTU intramural grant(22062267-Y)Excellent Graduate Thesis Cultivation Fund(LW-YP2024011).
文摘Nuclear mass is an important property in both nuclear and astrophysics.In this study,we explore an improved mass model that incorporates a higher-order term of symmetry energy using algorithms.The sequential least squares programming(SLSQP)algorithm augments the precision of this multinomial mass model by reducing the error from 1.863 MeV to 1.631 MeV.These algorithms were further examined using 200 sample mass formulae derived from theδE term of the E_(isospin) mass model.The SLSQP method exhibited superior performance compared to the other algorithms in terms of errors and convergence speed.This algorithm is advantageous for handling large-scale multiparameter optimization tasks in nuclear physics.
文摘Flow characteristics around a wall-mounted square cylinder have been numerically simulated at aspect ratios (AR) ranging from 4 to 7 at Re =10 000. Four turbulence models have been compared in terms of drag coefficient (C_D). The closest result has been provided by two turbulence models, namely, k-ε Realizable and k ?ω Shear Stress Transport (SST). Hence, these models were utilized to present the flow patterns of pressure distributions, turbulent kinetic energy values, velocity magnitude values with streamlines, streamwise velocity components, crossstream velocity components and spanwise velocity components on different planes. Flow stagnation has been attained in front of the cylinder. Pressure values peaked for the upstream region. Over the cylinders, the tip vortex structure was dominant owing to the influence of the free end. Flow separation from the top front edge of the body has been obtained. The dividing streamline affected by the flow separation was highly effective in the wake region and moved nearer to the body when the aspect ratio was decreased;the reason was the wake shrinkage owing to the decreasing aspect ratio. Upwash and downwash have been seen in the cylinder wake. These two models presented similar flow patterns and drag coefficients. These drag coefficients are in good agreement with those in previous studies.
文摘The exchange and mutual appreciation of different cultures is an important topic in the context of globalization,and traditional patterns are the crystallization of the national cultures of various countries.The study focuses on the Ming Dynasty Mandarin square in ancient China and the Tudor Dynasty coat of arms during the same period in England.By using comparative research,case studies,and combining historical documents and images,the origins of the two types of decorations are traced,and their social connotations and influencing factors are analyzed.Research has shown that under the influence of the historical backgrounds of politics,economy,and culture,the two types of decorative patterns exhibit a realistic aesthetic trend.The cultural connotations not only demonstrate social narrative functions such as customs and rituals,but also reflect political system functions such as hierarchy and honor.The different historical origins give rise to cultural differences in the selection of decorative elements between the two.The comparative study of the two is not only beneficial for conducting decorative design research from a global perspective,but also can promote the modern inheritance of traditional patterns while seeking common ground and reserving differences.
基金supported by the National Natural Science Foundation of China under Grant 61673017in part by the Science and Technology Department of Shaanxi Province under Grant 2024JC-YBQN-0657。
文摘Aeromagnetic compensation is one of the key issues in high-precision geomagnetic fl ight carrier navigation, directly determining the accuracy and reliability of real-time magnetic measurement data. The accurate modeling and compensation of interference magnetic measurements on carriers are of great signifi cance for the construction of reference and real-time maps for geomagnetic navigation. Current research on aeromagnetic compensation algorithms mainly focuses on accurately modeling interference magnetic fields from model- and data-driven perspectives based on measured aeromagnetic data. Challenges in obtaining aeromagnetic data and low information complexity adversely aff ect the generalization performance of a constructed model. To address these issues, a recursive least square algorithm based on elastic weight consolidation is proposed, which eff ectively suppresses the occurrence of catastrophic forgetting by controlling the direction of parameter updates. Experimental verifi cation with publicly available aeromagnetic datasets shows that the proposed algorithm can eff ectively circumvent historical information loss caused by interference magnetic field models during parameter updates and improve the stability, robustness, and accuracy of interference magnetic fi eld models.
基金supported by the National Natural Science Foundation of China(No.42174011)。
文摘In the variance component estimation(VCE)of geodetic data,the problem of negative VCE is likely to occur.In the ordinary additive error model,there have been related studies to solve the problem of negative variance components.However,there is still no related research in the mixed additive and multiplicative random error model(MAMREM).Based on the MAMREM,this paper applies the nonnegative least squares variance component estimation(NNLS-VCE)algorithm to this model.The correlation formula and iterative algorithm of NNLS-VCE for MAMREM are derived.The problem of negative variance in VCE for MAMREM is solved.This paper uses the digital simulation example and the Digital Terrain Mode(DTM)to prove the proposed algorithm's validity.The experimental results demonstrated that the proposed algorithm can effectively correct the VCE in MAMREM when there is a negative VCE.
基金supported by the Ningbo Youth Science and Technology Innovation Leading Talents of China(No.2023QL020)the Ningbo Science and Technology Major of China(No.2022Z015)the K.C.Wong Magana Fund through Ningbo University。
文摘This study presents a closed-form solution for central stress,a semi-analytical model,and a modified anisotropic semi-analytical model to efficiently calculate the forcefrequency coefficients(FFCs)of square quartz crystal resonators(QCRs)with different side lengths and azimuth angles under eccentrically concentrated and distributed loads.The semi-analytical model is validated by comparisons between the experimental results and the nonlinear finite element method(FEM)simulation results.Based on the semi-analytical model for the FFC and nonlinear FEM simulations,the FFC variations of square QCRs under external loads and the related mechanisms are investigated.Among the initial stresses caused by external loads,the central stress parallel to the xcrystallographic axis is the primary factor influencing the FFC of quartz.Our findings can provide practical tools for calculating the FFC,and help the design and development of square quartz force sensors.
基金supported by the National Natural Science Foundation of China(52472194,52101243)the Natural Science Foundation of Guangdong Province,China(2023A1515012619,2025A1515012571,2025A1515010345)the Science and Technology Planning Project of Guangzhou(202201010565).
文摘Sodium-ion batteries are receiving more and more attention due to their low cost and abundant sodium storage capacity,and are considered to be a promising alternative to lithium-ion batteries.A large number of studies have shown that constructing heterostructures are considered an effective strategy to solve the hysteresis problem of electronic and ion dynamics in sodiumion battery anode materials.Herein,a nickel-cobalt bimetallic coordination polymer(NiCoCP)was synthesized using a coprecipitation method,and a CoSe_(2)@NiSe_(2) cross-stacked structure was obtained through high-temperature carbonization and selenization processes.CoSe_(2)@NiSe_(2) has a unique heterostructure and carbon film,which synergistically increases a large number of adsorption sites and alleviates the diffusion energy barrier,thereby improving the rapid diffusion kinetics of Na^(+)ions.It has superior rate performance and long-lasting cycle life.For sodium-ion batteries(SIBs),the specific capacity of CoSe_(2)@NiSe_(2) is around 460 mA h g^(-1) after 400 cycles at 1.0 A g^(-1).For potassium-ion batteries(PIBs),CoSe_(2)@NiSe_(2) also exhibits excellent cycling stability,maintaining a specific capacity of 160 mA h g^(-1) after 700 cycles at 1.0 A g^(-1).This study provides a new way to prepare metal selenide heterostructure as the promising anode material for SIBs.
文摘针对压电陶瓷的迟滞非线性,建立了基于一种加权最小二乘支持向量机(Weighted Least Squares Support Vector Machine,WLS-SVM)的迟滞动态模型。为了能够方便使用支持向量机,应用了一种动态算子,将迟滞的多值映射变成一一映射。并在传统的最小二乘支持向量机(Least Squares Support Vector Machine,LS-SVM)的基础上加入了支持向量度,以区分数据的重要程度。为了减轻计算量,将数据按照支持向量度从大到小排序,其中支持向量度接近于零的数据被视作非支持向量。使用剪枝法按一定比例减去支持向量度比较小的数据,利用粒子群算法(Particle Swarm Optimization, PSO)辨识出模型的未知参数。最后,实验的结果验证了模型的可行性。
基金supported by the National Natural Science Foundation of China(Grant No.62275075)the Natural Science Foundation of Hubei Soliton Research Association(Grant No.2025HBSRA09)+1 种基金joint supported by Hubei Provincial Natural Science Foundation and Xianning of China(Grant Nos.2025AFD401 and 2025AFD405)Israel Science Foundation(Grant No.1695/22).
文摘We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the stimulated Raman-induced photoassociation and square-optical-lattice potential.Stationary solutions of the coupled GPE system are obtained by means of the imaginary-time integration,while the temporal dynamics are simulated using the fourth-order Runge-Kutta algorithm.The analysis reveals stable rhombus-shaped VS shapes with topological charges m=1 and 2 of the atomic component.The stability domains and spatial structure of these VSs are governed by three key parameters:the parametric-coupling strength(χ),atomicmolecular interaction strength(g_(12)),and the optical-lattice potential depth(V_(0)).By varyingχand g_(12),we demonstrate a structural transition where four-core rhombus-shaped VSs evolve into eight-core square-shaped modes,highlighting the nontrivial nonlinear dynamics of the system.This work establishes a connection between interactions of cold atoms and topologically structured matter waves in hybrid quantum systems.
