The intersection method is one of the basic approaches for locating earthquakes and is not only robust but also efficient. However, its location accuracy is not high, especially for focal depth because the velocity mo...The intersection method is one of the basic approaches for locating earthquakes and is not only robust but also efficient. However, its location accuracy is not high, especially for focal depth because the velocity model used for the conventional intersection method is based on homogeneous or laterally homogeneous media, which is too simple. In order to improve the accuracy, we have modified the existing intersection method. In the modified approach, the earthquake loci are not assumed to be circular or hyperbolic and calculation accuracy is improved using a minimum traveltime tree algorithm for tracing rays. The numerical model shows that the modified method can locate earthquakes in complex velocity models.展开更多
Light-induced conical intersections(LICIs)present a distinctive mechanism for nonadiabatic coupling,thereby facilitating ultrafast chemical reactions,including the indirect photodissociation of diatomic molecules.In c...Light-induced conical intersections(LICIs)present a distinctive mechanism for nonadiabatic coupling,thereby facilitating ultrafast chemical reactions,including the indirect photodissociation of diatomic molecules.In contrast to static conical intersections,LICIs are dynamically tunable,providing a pathway for precise control of molecular dissociation.In this study,we employ the time-dependent quantum wave packet method to investigate the dissociation dynamics of the OH molecule,focusing on its ground state X^(2)Πand repulsive state 1^(2)Σ~-.By varying laser field parameters(intensity,full width at half maximum(FWHM),and wavelength),we elucidate how nonadiabatic coupling governs selective dissociation channel control.Our findings reveal that the choice of initial vibrational states and the tailoring of laser conditions significantly influence dissociation pathways,providing theoretical insights into manipulating molecular dynamics via LICIs.These results provide a foundation for future experimental studies and the development of advanced molecular control techniques.展开更多
The analytic expression of the special points on the intersection of two cones with their axes intersecting(ITCTAI) is given. It also presents a method to construct the special points graphically according to the anal...The analytic expression of the special points on the intersection of two cones with their axes intersecting(ITCTAI) is given. It also presents a method to construct the special points graphically according to the analytic expression of them. Finally, with computer programming language, it gives a program to generate the intersection in several different cases.展开更多
Optimization analysis and computational fluid dynamics （CFDs） have been applied simultaneously, in which a parametric model plays an important role in finding the optimal solution. However, it is difficult to create...Optimization analysis and computational fluid dynamics （CFDs） have been applied simultaneously, in which a parametric model plays an important role in finding the optimal solution. However, it is difficult to create a parametric model for a complex shape with irregular curves, such as a submarine hull form. In this study, the cubic Bezier curve and curve-plane intersection method are used to generate a solid model of a parametric submarine hull form taking three input parameters into account： nose radius, tail radius, and length-height hull ratio （L/H）. Application program interface （API） scripting is also used to write code in the ANSYS DesignModeler. The results show that the submarine shape can be generated with some variation of the input parameters. An example is given that shows how the proposed method can be applied successfully to a hull resistance optimization case. The parametric design of the middle submarine type was chosen to be modified. First, the original submarine model was analyzed, in advance, using CFD. Then, using the response surface graph, some candidate optimal designs with a minimum hull resistance coefficient were obtained. Further, the optimization method in goal-driven optimization （GDO） was implemented to find the submarine hull form with the minimum hull resistance coefficient （Ct）. The minimum C, was obtained. The calculated difference in （7, values between the initial submarine and the optimum submarine is around 0.26%, with the C, of the initial submarine and the optimum submarine being 0.001 508 26 and 0.001 504 29, respectively. The results show that the optimum submarine hull form shows a higher nose radius （rn） and higher L/H than those of the initial submarine shape, while the radius of the tail （r1） is smaller than that of the initial shape.展开更多
Finding the intersection of two subspaces is of great interest in many fields of signal processing. Over several decades,there have been numerous formulas discovered to solve this problem, among which the alternate pr...Finding the intersection of two subspaces is of great interest in many fields of signal processing. Over several decades,there have been numerous formulas discovered to solve this problem, among which the alternate projection method(APM) is the most popular one. However, APM suffers from high computational complexity, especially for real-time applications. Moreover, APM only gives the projection instead of the orthogonal basis of two given subspaces. This paper presents two alternate algorithms which have a closed form and reduced complexity as compared to the APM technique. Numerical simulations are conducted to verify the correctness and the effectiveness of the proposed methods.展开更多
We made an on-site investigation about pedestrian violation of traffic signals at a signalized intersection in Xi＇an, Shaanxi province, China. Based on it, we studied the impact of pedestrian＇s waiting time on viola...We made an on-site investigation about pedestrian violation of traffic signals at a signalized intersection in Xi＇an, Shaanxi province, China. Based on it, we studied the impact of pedestrian＇s waiting time on violation decision and the impact of the number of pedestrians in colony on the probability of swarming pedestrians＇ violation. The result revealed that the probability of pedestrian violation rose with the waiting time for the pedestrians＇ green signal. Then we developed a Monte Carlo model for simulating mixed vehicles and pedestrians and used the on-site investigation data to validate the model. When traffic volume is fight, the error between the simulated values and the measured ones is 2.67%. When traffic volume is heavy, the error is 3.38%.展开更多
The genetic algorithm and marching method are integrated into a novel algorithm to solve the surface intersection problem. By combining genetic algorithm with local searching method the efficiency of evolution is grea...The genetic algorithm and marching method are integrated into a novel algorithm to solve the surface intersection problem. By combining genetic algorithm with local searching method the efficiency of evolution is greatly improved. By fully utilizing the global searching ability and instinct attribute for parallel computation of genetic algorithm and the local rapid convergency of marching method, the algorithm can compute the intersection robustly and generate correct topology of intersection curves. The details of the new algorithm are discussed here.展开更多
An efficient Advancing Layer Method(ALM)is presented to create semi-structured prisms on viscous walls,in which a procedure that checks possible front intersections is essential to its efficiency.This paper develops v...An efficient Advancing Layer Method(ALM)is presented to create semi-structured prisms on viscous walls,in which a procedure that checks possible front intersections is essential to its efficiency.This paper develops various novel schemes to improve the algorithm’s efficiency precisely while not sacrificing its robustness and the resulting mesh quality.First,it employs a set of new techniques,and data structures are developed to improve the efficiency of the frontcheck procedure.Then,within each octant,a new filter is developed to reduce the intersection computations in the searching process.In addition,data structures are well designed to store the contiguously accessed data in each computing-intensive loop in a contiguous space for a potentially better cache hit ratio.We built a geometry model library formed by examples of industrial complexity to demonstrate the practicability of the algorithm.All the efforts mentioned above enable us to reduce the percentage of computing time taken by intersection check to an acceptable level(approximately 26%),which make it no longer be the most time-consuming part.展开更多
In order to establish the groove model for intersecting structures of circular tubes,mathematical model of the intersecting line is established by the method of analytic geometry,and parametric equations are thus dete...In order to establish the groove model for intersecting structures of circular tubes,mathematical model of the intersecting line is established by the method of analytic geometry,and parametric equations are thus determined.The dihedral angle,groove angle and actual cutting angle for any position of the intersecting line are derived as well.In order to identify groove vectors for two pipes,a new analytical method,i.e.coplanarity of vectors,is further proposed to complete the groove model.The established model is virtually verified by programming and simulation calculation in the MATLAB environment.The results show that groove vectors of intersecting structures simulated by MATLAB are consistent with the theoretical groove model,indicating that the theoretical groove model established in this paper is accurate,and further proves that the proposed coplanarity of vectors for solving groove vectors is correct and feasible.Finally,a graphical user interface(GUI)is developed by MATLAB software to independently realize functions such as model drawing,variable calculation and data output.The research outcome provides a theoretical foundation for the actual welding of circular intersecting structures,and lays an essential basis for weld bead layout and path planning.展开更多
采用拉氏时间推进加重映到初始网格的方式,在结构化交错欧拉网格上实现一种新型两步欧拉法。拉氏时间推进采用预估-校正方法,混合网格的拉氏计算中引入压力松弛模型。用MOF(Moment of Fluid)重构显式界面,将混合网格剖分为多个介质多面...采用拉氏时间推进加重映到初始网格的方式,在结构化交错欧拉网格上实现一种新型两步欧拉法。拉氏时间推进采用预估-校正方法,混合网格的拉氏计算中引入压力松弛模型。用MOF(Moment of Fluid)重构显式界面,将混合网格剖分为多个介质多面体,实现了精确的相交重映。考虑到已有拉氏网格与拉氏网格相交算法的低效性,实现了与两步欧拉法更适配的拉氏网格与欧拉网格相交算法。数值模拟结果表明:在欧拉框架下构造显式界面,能够提高欧拉方法对界面的分辨能力,本文构造显式界面进行相交重映的算法具有健壮且高效的特点,在大变形模拟中也可以保持较好的完整性。展开更多
在废旧锂电池模组的自动化拆解过程中,需要快速地对其表面数量众多的各类螺纹紧固件进行精准位姿识别。针对已有特征匹配方法难以适应紧固件周围复杂背景环境及深度学习方法无法实现紧固件中心精确定位与姿态识别的现状,基于轻量化深度...在废旧锂电池模组的自动化拆解过程中,需要快速地对其表面数量众多的各类螺纹紧固件进行精准位姿识别。针对已有特征匹配方法难以适应紧固件周围复杂背景环境及深度学习方法无法实现紧固件中心精确定位与姿态识别的现状,基于轻量化深度学习模型SqueezeNet与紧固件BLOB(Binary Large Object)特征分析,以由粗到精的识别策略将上述两类方法结合,快速实现紧固件的种类判别与精确定位。并在此基础上进一步提出区域相交法用于准确识别各类紧固件的头部姿态角。实验结果表明:所提方法与其他现有识别模型相比,不仅获得了较高的粗定位精度(94.9%),并且紧固件中心精定位误差与头部姿态角误差分别在0.3 mm与3°之内,能够很好地满足机器人拆卸紧固件的应用需求。展开更多
基金This work is supported by the National Natural Science Foundation of China(40674044)the Special Foundation for Basic Professional Scientific Research (DQJB06A02)
文摘The intersection method is one of the basic approaches for locating earthquakes and is not only robust but also efficient. However, its location accuracy is not high, especially for focal depth because the velocity model used for the conventional intersection method is based on homogeneous or laterally homogeneous media, which is too simple. In order to improve the accuracy, we have modified the existing intersection method. In the modified approach, the earthquake loci are not assumed to be circular or hyperbolic and calculation accuracy is improved using a minimum traveltime tree algorithm for tracing rays. The numerical model shows that the modified method can locate earthquakes in complex velocity models.
基金supported by the National Natural Science Foundation of China(Grant Nos.12134005 and 12334011)the Major Research Plan of the National Natural Science Foundation of China(Grant No.92461301)。
文摘Light-induced conical intersections(LICIs)present a distinctive mechanism for nonadiabatic coupling,thereby facilitating ultrafast chemical reactions,including the indirect photodissociation of diatomic molecules.In contrast to static conical intersections,LICIs are dynamically tunable,providing a pathway for precise control of molecular dissociation.In this study,we employ the time-dependent quantum wave packet method to investigate the dissociation dynamics of the OH molecule,focusing on its ground state X^(2)Πand repulsive state 1^(2)Σ~-.By varying laser field parameters(intensity,full width at half maximum(FWHM),and wavelength),we elucidate how nonadiabatic coupling governs selective dissociation channel control.Our findings reveal that the choice of initial vibrational states and the tailoring of laser conditions significantly influence dissociation pathways,providing theoretical insights into manipulating molecular dynamics via LICIs.These results provide a foundation for future experimental studies and the development of advanced molecular control techniques.
文摘The analytic expression of the special points on the intersection of two cones with their axes intersecting(ITCTAI) is given. It also presents a method to construct the special points graphically according to the analytic expression of them. Finally, with computer programming language, it gives a program to generate the intersection in several different cases.
基金Supported by the Ministry of Research,Technology,and Higher Education Republic of Indonesia,through the Budget Implementation List(DIPA)of Diponegoro University,Grant No.DIPA-023.04.02.189185/2014,December 05,2013
文摘Optimization analysis and computational fluid dynamics （CFDs） have been applied simultaneously, in which a parametric model plays an important role in finding the optimal solution. However, it is difficult to create a parametric model for a complex shape with irregular curves, such as a submarine hull form. In this study, the cubic Bezier curve and curve-plane intersection method are used to generate a solid model of a parametric submarine hull form taking three input parameters into account： nose radius, tail radius, and length-height hull ratio （L/H）. Application program interface （API） scripting is also used to write code in the ANSYS DesignModeler. The results show that the submarine shape can be generated with some variation of the input parameters. An example is given that shows how the proposed method can be applied successfully to a hull resistance optimization case. The parametric design of the middle submarine type was chosen to be modified. First, the original submarine model was analyzed, in advance, using CFD. Then, using the response surface graph, some candidate optimal designs with a minimum hull resistance coefficient were obtained. Further, the optimization method in goal-driven optimization （GDO） was implemented to find the submarine hull form with the minimum hull resistance coefficient （Ct）. The minimum C, was obtained. The calculated difference in （7, values between the initial submarine and the optimum submarine is around 0.26%, with the C, of the initial submarine and the optimum submarine being 0.001 508 26 and 0.001 504 29, respectively. The results show that the optimum submarine hull form shows a higher nose radius （rn） and higher L/H than those of the initial submarine shape, while the radius of the tail （r1） is smaller than that of the initial shape.
基金supported by the National Natural Science Foundation of China(61501142 61871149)the project supported by Discipline Construction Guiding Foundation in Harbin Institute of Technology(Weihai)(WH2-0160107)
文摘Finding the intersection of two subspaces is of great interest in many fields of signal processing. Over several decades,there have been numerous formulas discovered to solve this problem, among which the alternate projection method(APM) is the most popular one. However, APM suffers from high computational complexity, especially for real-time applications. Moreover, APM only gives the projection instead of the orthogonal basis of two given subspaces. This paper presents two alternate algorithms which have a closed form and reduced complexity as compared to the APM technique. Numerical simulations are conducted to verify the correctness and the effectiveness of the proposed methods.
基金The National Natural Science Foundation of China (No.60134010)
文摘We made an on-site investigation about pedestrian violation of traffic signals at a signalized intersection in Xi＇an, Shaanxi province, China. Based on it, we studied the impact of pedestrian＇s waiting time on violation decision and the impact of the number of pedestrians in colony on the probability of swarming pedestrians＇ violation. The result revealed that the probability of pedestrian violation rose with the waiting time for the pedestrians＇ green signal. Then we developed a Monte Carlo model for simulating mixed vehicles and pedestrians and used the on-site investigation data to validate the model. When traffic volume is fight, the error between the simulated values and the measured ones is 2.67%. When traffic volume is heavy, the error is 3.38%.
文摘The genetic algorithm and marching method are integrated into a novel algorithm to solve the surface intersection problem. By combining genetic algorithm with local searching method the efficiency of evolution is greatly improved. By fully utilizing the global searching ability and instinct attribute for parallel computation of genetic algorithm and the local rapid convergency of marching method, the algorithm can compute the intersection robustly and generate correct topology of intersection curves. The details of the new algorithm are discussed here.
基金co-supported by the Zhejiang Provincial Science and Technology Program,China(No.2021C01108)the Innovative Research Foundation of Ship General Performance,China(No.14022105)the Science and Technology on Scramjet Laboratory Fund,China(No.2022-JCJQ-LB020-05).
文摘An efficient Advancing Layer Method(ALM)is presented to create semi-structured prisms on viscous walls,in which a procedure that checks possible front intersections is essential to its efficiency.This paper develops various novel schemes to improve the algorithm’s efficiency precisely while not sacrificing its robustness and the resulting mesh quality.First,it employs a set of new techniques,and data structures are developed to improve the efficiency of the frontcheck procedure.Then,within each octant,a new filter is developed to reduce the intersection computations in the searching process.In addition,data structures are well designed to store the contiguously accessed data in each computing-intensive loop in a contiguous space for a potentially better cache hit ratio.We built a geometry model library formed by examples of industrial complexity to demonstrate the practicability of the algorithm.All the efforts mentioned above enable us to reduce the percentage of computing time taken by intersection check to an acceptable level(approximately 26%),which make it no longer be the most time-consuming part.
基金This work was supported by Natural Science Foundation of Fujian Province(Grant No.2020J01873)Science and Technology Major Project of Fujian Province(Grant No.2020HZ03018).
文摘In order to establish the groove model for intersecting structures of circular tubes,mathematical model of the intersecting line is established by the method of analytic geometry,and parametric equations are thus determined.The dihedral angle,groove angle and actual cutting angle for any position of the intersecting line are derived as well.In order to identify groove vectors for two pipes,a new analytical method,i.e.coplanarity of vectors,is further proposed to complete the groove model.The established model is virtually verified by programming and simulation calculation in the MATLAB environment.The results show that groove vectors of intersecting structures simulated by MATLAB are consistent with the theoretical groove model,indicating that the theoretical groove model established in this paper is accurate,and further proves that the proposed coplanarity of vectors for solving groove vectors is correct and feasible.Finally,a graphical user interface(GUI)is developed by MATLAB software to independently realize functions such as model drawing,variable calculation and data output.The research outcome provides a theoretical foundation for the actual welding of circular intersecting structures,and lays an essential basis for weld bead layout and path planning.
文摘采用拉氏时间推进加重映到初始网格的方式,在结构化交错欧拉网格上实现一种新型两步欧拉法。拉氏时间推进采用预估-校正方法,混合网格的拉氏计算中引入压力松弛模型。用MOF(Moment of Fluid)重构显式界面,将混合网格剖分为多个介质多面体,实现了精确的相交重映。考虑到已有拉氏网格与拉氏网格相交算法的低效性,实现了与两步欧拉法更适配的拉氏网格与欧拉网格相交算法。数值模拟结果表明:在欧拉框架下构造显式界面,能够提高欧拉方法对界面的分辨能力,本文构造显式界面进行相交重映的算法具有健壮且高效的特点,在大变形模拟中也可以保持较好的完整性。
文摘在废旧锂电池模组的自动化拆解过程中,需要快速地对其表面数量众多的各类螺纹紧固件进行精准位姿识别。针对已有特征匹配方法难以适应紧固件周围复杂背景环境及深度学习方法无法实现紧固件中心精确定位与姿态识别的现状,基于轻量化深度学习模型SqueezeNet与紧固件BLOB(Binary Large Object)特征分析,以由粗到精的识别策略将上述两类方法结合,快速实现紧固件的种类判别与精确定位。并在此基础上进一步提出区域相交法用于准确识别各类紧固件的头部姿态角。实验结果表明:所提方法与其他现有识别模型相比,不仅获得了较高的粗定位精度(94.9%),并且紧固件中心精定位误差与头部姿态角误差分别在0.3 mm与3°之内,能够很好地满足机器人拆卸紧固件的应用需求。
