针对实际点云数据中存在的噪点与缺陷对拟合平面时带来的影响,提出一种基于最小平方中值算法(least median of squares,LMedS)与距离加权总体最小二乘法(weighted total least squares based on distance,WTLSD)相结合的平面拟合算法。...针对实际点云数据中存在的噪点与缺陷对拟合平面时带来的影响,提出一种基于最小平方中值算法(least median of squares,LMedS)与距离加权总体最小二乘法(weighted total least squares based on distance,WTLSD)相结合的平面拟合算法。通过最小平方中值算法初步去除点云中的噪点,并基于距离构建初始权重矩阵,利用距离加权总体最小二乘法对点云进行平面拟合,减少平面中凸起与凹陷等缺陷对平面拟合的影响,该算法与传统平面拟合算法相比具备消除异常点与平面缺陷的优点,具备更高的拟合精度;与随机采样一致性算法(random sample consensus,RANSAC)相比具有更高的拟合效率与相近的拟合精度。展开更多
为解决现有辨识方法在针对耦合的次/超同步振荡参数提取过程中的噪声适应性差和模态混叠问题,该文提出了一种自适应的变分模态分解法(variational mode decomposition,VMD),定义残差损失总熵、中心频率的切比雪夫距离以及边缘熵共同决...为解决现有辨识方法在针对耦合的次/超同步振荡参数提取过程中的噪声适应性差和模态混叠问题,该文提出了一种自适应的变分模态分解法(variational mode decomposition,VMD),定义残差损失总熵、中心频率的切比雪夫距离以及边缘熵共同决定分解模态数和带宽,结合最小二乘-旋转不变技术(total least square-estimating signal parameter via rotational invariance techniques,TLS-ESPRIT)对分解出的振荡分量进行参数辨识,无需另外使用降噪算法。通过复合信号测试法、PSCAD/EMTDC电磁暂态仿真法验证了所提方法的有效性。最后,将所提方法与改进Prony算法、MCEEMD法在不同噪声水平和振荡频率下进行对比,结果表明,所提方法能够有效地抑制原始信号的噪声干扰,对耦合的次/超同步振荡信号分解更加准确,参数辨识结果可靠性较高,对风电系统振荡溯源、改善系统阻尼具有一定的参考意义。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
This study numerically investigates inclined magneto-hydrodynamic natural convection in a porous cavity filled with nanofluid containing gyrotactic microorganisms.The governing equations are nondimensionalized and sol...This study numerically investigates inclined magneto-hydrodynamic natural convection in a porous cavity filled with nanofluid containing gyrotactic microorganisms.The governing equations are nondimensionalized and solved using the finite volume method.The simulations examine the impact of key parameters such as heat source length and position,Peclet number,porosity,and heat generation/absorption on flow patterns,temperature distribution,concentration profiles,and microorganism rotation.Results indicate that extending the heat source length enhances convective currents and heat transfer efficiency,while optimizing the heat source position reduces entropy generation.Higher Peclet numbers amplify convective currents and microorganism distribution complexity.Variations in porosity and heat generation/absorption significantly influence flow dynamics.Additionally,the artificial neural network model reliably predicts the mean Nusselt and Sherwood numbers(Nu&Sh),demonstrating its effectiveness for such analyses.The simulation results reveal that increasing the heat source length significantly enhances heat transfer,as evidenced by a 15%increase in the mean Nusselt number.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
文摘针对实际点云数据中存在的噪点与缺陷对拟合平面时带来的影响,提出一种基于最小平方中值算法(least median of squares,LMedS)与距离加权总体最小二乘法(weighted total least squares based on distance,WTLSD)相结合的平面拟合算法。通过最小平方中值算法初步去除点云中的噪点,并基于距离构建初始权重矩阵,利用距离加权总体最小二乘法对点云进行平面拟合,减少平面中凸起与凹陷等缺陷对平面拟合的影响,该算法与传统平面拟合算法相比具备消除异常点与平面缺陷的优点,具备更高的拟合精度;与随机采样一致性算法(random sample consensus,RANSAC)相比具有更高的拟合效率与相近的拟合精度。
文摘为解决现有辨识方法在针对耦合的次/超同步振荡参数提取过程中的噪声适应性差和模态混叠问题,该文提出了一种自适应的变分模态分解法(variational mode decomposition,VMD),定义残差损失总熵、中心频率的切比雪夫距离以及边缘熵共同决定分解模态数和带宽,结合最小二乘-旋转不变技术(total least square-estimating signal parameter via rotational invariance techniques,TLS-ESPRIT)对分解出的振荡分量进行参数辨识,无需另外使用降噪算法。通过复合信号测试法、PSCAD/EMTDC电磁暂态仿真法验证了所提方法的有效性。最后,将所提方法与改进Prony算法、MCEEMD法在不同噪声水平和振荡频率下进行对比,结果表明,所提方法能够有效地抑制原始信号的噪声干扰,对耦合的次/超同步振荡信号分解更加准确,参数辨识结果可靠性较高,对风电系统振荡溯源、改善系统阻尼具有一定的参考意义。
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.
基金Dean ship of Scientific Research at King Khalid University,Abha,Saudi Arabia,for funding this work through the Research Group Project(Grant No.RGP.2/610/45)funded by the Princess Nourah bint Abdulrahman University Researchers Supporting Project(Grant No.PNURSP2024R102),Princess Nourah bint Abdulrahman University,Riyadh,Saudi Arabia。
文摘This study numerically investigates inclined magneto-hydrodynamic natural convection in a porous cavity filled with nanofluid containing gyrotactic microorganisms.The governing equations are nondimensionalized and solved using the finite volume method.The simulations examine the impact of key parameters such as heat source length and position,Peclet number,porosity,and heat generation/absorption on flow patterns,temperature distribution,concentration profiles,and microorganism rotation.Results indicate that extending the heat source length enhances convective currents and heat transfer efficiency,while optimizing the heat source position reduces entropy generation.Higher Peclet numbers amplify convective currents and microorganism distribution complexity.Variations in porosity and heat generation/absorption significantly influence flow dynamics.Additionally,the artificial neural network model reliably predicts the mean Nusselt and Sherwood numbers(Nu&Sh),demonstrating its effectiveness for such analyses.The simulation results reveal that increasing the heat source length significantly enhances heat transfer,as evidenced by a 15%increase in the mean Nusselt number.
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.
