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Block and parallel modelling of broad domain nonlinear continuous mapping based on NN
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作者 Yang Guowei Tu Xuyan Wang Shoujue 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2006年第3期586-592,共7页
The necessity of the use of the block and parallel modeling of the nonlinear continuous mappings with NN is firstly expounded quantitatively. Then, a practical approach for the block and parallel modeling of the nonli... The necessity of the use of the block and parallel modeling of the nonlinear continuous mappings with NN is firstly expounded quantitatively. Then, a practical approach for the block and parallel modeling of the nonlinear continuous mappings with NN is proposed. Finally, an example indicating that the method raised in this paper can be realized by suitable existed software is given. The results of the experiment of the model discussed on the 3-D Mexican straw hat indicate that the block and parallel modeling based on NN is more precise and faster in computation than the direct ones and it is obviously a concrete example and the development of the large-scale general model established by Tu Xuyan. 展开更多
关键词 model nonlinear continuous mapping neural network parallel modelling.
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Longitudinal crack on slab surface at straightening stage during continuous casting using finite element method 被引量:5
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作者 喻海良 刘相华 《Journal of Central South University》 SCIE EI CAS 2010年第2期235-238,共4页
Deformation behavior of slab at the straightening stage during continuous casting was simulated by the explicit dynamic finite element method,and the stress distribution along the width direction of the slab and its c... Deformation behavior of slab at the straightening stage during continuous casting was simulated by the explicit dynamic finite element method,and the stress distribution along the width direction of the slab and its change regularity at slab center during continuous casting were obtained.The influence of distribution and change of stress on the propagation of longitudinal cracks on slab surface was discussed.The results show that the tensional stress appears on slab surface at the inner arc side and the compressive stress appears on slab surface at the outer arc side at stages 6-8 in straightening zone during continuous casting.Longitudinal cracks generally appear on slab top surface and do not appear on slab bottom surface,which are also observed in industry. 展开更多
关键词 continuous casting slab STRAIGHTENING longitudinal crack finite element method
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A bottom-up method for module-based product platform development through mapping,clustering and matching analysis
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作者 张萌 李国喜 +2 位作者 曹建平 龚京忠 吴宝中 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第3期623-635,共13页
Designing product platform could be an effective and efficient solution for manufacturing firms. Product platforms enable firms to provide increased product variety for the marketplace with as little variety between p... Designing product platform could be an effective and efficient solution for manufacturing firms. Product platforms enable firms to provide increased product variety for the marketplace with as little variety between products as possible. Developed consumer products and modules within a firm can further be investigated to find out the possibility of product platform creation. A bottom-up method is proposed for module-based product platform through mapping, clustering and matching analysis. The framework and the parametric model of the method are presented, which consist of three steps:(1) mapping parameters from existing product families to functional modules,(2) clustering the modules within existing module families based on their parameters so as to generate module clusters, and selecting the satisfactory module clusters based on commonality, and(3) matching the parameters of the module clusters to the functional modules in order to capture platform elements. In addition, the parameter matching criterion and mismatching treatment are put forward to ensure the effectiveness of the platform process, while standardization and serialization of the platform element are presented. A design case of the belt conveyor is studied to demonstrate the feasibility of the proposed method. 展开更多
关键词 product platform development bottom-up method mapping CLUSTERING MATCHING
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Simulation of thermomechanical behavior during continuous casting process based on MiLE method
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作者 夏云进 王福明 +1 位作者 李长荣 王金龙 《Journal of Central South University》 SCIE EI CAS 2012年第9期2403-2410,共8页
A new method called mixed Lagrangian and Eulerian method (MILE method) was used to simulate the thermomechanical behavior during continuous casting process of steel YF45MnV. The simulation results are basically in a... A new method called mixed Lagrangian and Eulerian method (MILE method) was used to simulate the thermomechanical behavior during continuous casting process of steel YF45MnV. The simulation results are basically in agreement with the measured data. The delaying period at the beginning of solidification is about 0.1. in square root of solidification time which is agreement with the data in literatures, and shell thickness increases in linear relation to square root of solidification time. The bloom surface temperature decreases gradually as the casting proceeds. The effective stress in the comer is much larger than that in the mid-face. The comer area is the dangerous zone of cracking. The effects of mold flux break temperature on the air gap and hot tearing indicator were also modeled. The model predicts that the bloom surface temperature increases with the increase of the mold flux break temperature, but the heat flux decreases with the increase of the mold flux break temperature. ,The hot tearing indicator is much smaller when the mold flux break temperature is higher. 展开更多
关键词 mixed Lagrangian and Eulerian (MILE) method thermomechanical behavior continuous casting mold flux breaktemperature hot tearing indicator
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基于MAP先验的历史数据信息借用在适应性设计临床试验中的应用研究
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作者 黄雅茹 康斌斌 +3 位作者 熊思雨 范敬义 夏结来 李晨 《中国卫生统计》 北大核心 2025年第4期496-501,509,共7页
目的 探索使用MAP(meta analytic predictive)先验方法的历史数据信息借用及其在适应性试验中的应用。方法 以复发或转移性头颈鳞癌的extreme治疗方案相关历史研究为例,通过模拟试验评价MAP方法在适应性试验中的适用性,及其在历史对照... 目的 探索使用MAP(meta analytic predictive)先验方法的历史数据信息借用及其在适应性试验中的应用。方法 以复发或转移性头颈鳞癌的extreme治疗方案相关历史研究为例,通过模拟试验评价MAP方法在适应性试验中的适用性,及其在历史对照数据的不同异质性、与当前试验不同程度数据冲突下对试验I型错误和检验效能的影响。结果 5项可适用extreme方案的历史研究共253名受试者,其MAP先验折合为19例有效样本量,RMAP(robust MAP)先验折合为17例有效样本量。RMAP方法相对于MAP方法能够更好地平衡历史数据与当前试验数据之间的潜在冲突,并控制I型错误和保持较高的检验效能。随着历史对照间异质性增加,加剧了先验与当前数据的冲突,MAP方法与RMAP方法的Ⅰ型错误均略有膨胀。当前试验的对照数据与历史对照趋近一致时,随着数据异质性增加,MAP方法与RMAP方法的检验效能均降低,具有信息先验的两阶段适应性设计可节约对照组30%~35%的预期样本量,随着RMAP中历史先验权重的增大,检验效能提高。结论 在适应性设计框架下,MAP先验及RMAP先验为合理有效地利用历史对照数据提供了统计学上的有效工具和稳健的方法学基础,有助于优化试验设计、节约资源并帮助试验决策。 展开更多
关键词 临床试验 历史数据 贝叶斯方法 map先验 适应性设计
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Logistic映射下N-continuous OFDM加密方案 被引量:2
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作者 曹礼梅 周杰 +1 位作者 罗宏 邵根富 《安徽大学学报(自然科学版)》 CAS 北大核心 2018年第6期71-77,共7页
针对信号传输安全问题,提出利用混沌随机性和初值敏感性相结合的数据传输加密方案.该方案首先利用混沌产生随机混沌序列,然后用该序列改变传输数据的相位以及系统子载波的映射规则,最后利用密钥恢复信号.仿真结果表明该方案能有效对系... 针对信号传输安全问题,提出利用混沌随机性和初值敏感性相结合的数据传输加密方案.该方案首先利用混沌产生随机混沌序列,然后用该序列改变传输数据的相位以及系统子载波的映射规则,最后利用密钥恢复信号.仿真结果表明该方案能有效对系统进行数据加密,加密效果良好,在保证高频谱利用率和较强分配灵活性的同时,能增强旁瓣抑制效果.因此,该方案能确保数据传输安全. 展开更多
关键词 N阶连续正交频分复用 LOGISTIC混沌映射 传输安全 混沌
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One-dimensional nonlinear consolidation analysis of soil with continuous drainage boundary 被引量:10
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作者 ZONG Meng-fan TIAN Yi +3 位作者 LIANG Rong-zhu WUWen-bing XU Mei-juan MEI Guo-xiong 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第1期270-281,共12页
Following the assumptions proposed by MESRI and ROKHSAR,the one-dimensional nonlinear consolidation problem of soil under constant loading is studied by introducing continuous drainage boundary.The numerical solution ... Following the assumptions proposed by MESRI and ROKHSAR,the one-dimensional nonlinear consolidation problem of soil under constant loading is studied by introducing continuous drainage boundary.The numerical solution is derived by using finite difference method and its correctness is assessed by comparing with existing analytical and numerical solutions.Based on the present solution,the effects of interface parameters,stress ratios(i.e.,final effective stress over initial effective stress,N_(σ))and the ratio c_(c)/c_(k)of compression index to permeability index on the consolidation behavior of soil are studied in detail.The results show that,the characteristics of one-dimensional nonlinear consolidation of soil are not only related to c_(c)/c_(k)and N_(σ),but also related to boundary conditions.In the engineering practice,the soil drainage rate of consolidation process can be designed by adjusting the values of interface parameters. 展开更多
关键词 one-dimensional nonlinear consolidation continuous drainage boundary finite difference method interface parameter
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A class of twostep continuity Runge-Kutta methods for solving singular delay differential equations and its convergence 被引量:1
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作者 Leng Xin Liu Degui +1 位作者 Song Xiaoqiu Chen Lirong 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第4期908-916,共9页
An idea of relaxing the effect of delay when computing the Runge-Kutta stages in the current step and a class of two-step continuity Runge-Kutta methods (TSCRK) is presented. Their construction, their order conditio... An idea of relaxing the effect of delay when computing the Runge-Kutta stages in the current step and a class of two-step continuity Runge-Kutta methods (TSCRK) is presented. Their construction, their order conditions and their convergence are studied. The two-step continuity Runge-Kutta methods possess good numerical stability properties and higher stage-order, and keep the explicit process of computing the Runge-Kutta stages. The numerical experiments show that the TSCRK methods are efficient. 展开更多
关键词 CONVERGENCE singular delay differential equations two-step continuity Runge-Kutta methods.
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Continuity control method of cutter posture vector for efficient five-axis machining 被引量:1
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作者 HWANG Jong-dae KIM Sang-myung +1 位作者 JUNG Hyun-chul JUNG Yoon-gyo 《Journal of Central South University》 SCIE EI CAS 2011年第6期1969-1975,共7页
During five-axis machining of impeller, the excessive local interference avoidance leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to impr... During five-axis machining of impeller, the excessive local interference avoidance leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to improve the efficiency of five-axis machining of impellers, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. By using an MC-space algorithm for interference avoidance, an MB-spline algorithm for continuous control was intended to create a five-axis machining tool path with excellent surface quality and economic feasibility. A five-axis cutting experiment was performed to verify the effectiveness of the continuity control. The result shows that the surface shape with continuous method is greatly improved, and the surface roughness is generally favorable. Consequently, the effectiveness of the suggested method is verified by identifying the improvement of efficiency of five-axis machining of an impeller in aspects of surface quality and machining time. 展开更多
关键词 five-axis control machining CONFIGURATION-SPACE B-SPLINE continuity control method IMPELLER interference
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Analysis of one-dimensional consolidation of fractional viscoelastic saturated soils under continuous drainage boundary conditions 被引量:1
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作者 CUI Peng-lu CAO Wen-gui +2 位作者 XU Zan WEI Yun-bo ZHANG Jia-chao 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第11期3745-3756,共12页
This paper presents the one-dimensional(1D)viscoelastic consolidation system of saturated clayey soil under continuous drainage boundaries.The fractional-derivative Merchant(FDM)model has been introduced into the cons... This paper presents the one-dimensional(1D)viscoelastic consolidation system of saturated clayey soil under continuous drainage boundaries.The fractional-derivative Merchant(FDM)model has been introduced into the consolidation system to simulate the viscoelasticity.Swartzendruber’s flow law is also introduced to describe the non-Darcian flow characteristics simultaneously.The generalized numerical solution of the 1D consolidation under continuous boundaries is given by the finite difference scheme.Furthermore,to illustrate the effectiveness of the numerical method,two simplified cases are compared against the current analytical and numerical results.Finally,the effects of boundary parameters and model parameters on the viscoelastic consolidation were illustrated and discussed.The results indicated that the boundary parameters have a significant influence on consolidation.The larger the values of boundary parameters,the faster the whole dissipation of the excess pore-water pressure and soils’settlement rate.Fractional-order and viscosity parameter have little effect on consolidation,which are primarily significant in the middle and late consolidation phases.With the increase of the modulus ratio,the whole consolidation process becomes faster.Moreover,considering Swartzendruber’s flow delays the consolidation rate of the soil layer. 展开更多
关键词 continuous drainage boundaries fractional-derivative Swartzendruber’s flow finite difference method VISCOELASTIC
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Mapping analysis of vibrating fundamental frequency for simple-supported elastic rectangle-plates with concentrated mass 被引量:1
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作者 齐红元 王爽心 朱衡君 《Journal of Central South University of Technology》 2007年第5期708-712,共5页
By conformal mapping theory, a trigonometric interpolation method between odd and even sequences in rectangle boundary region was provided, and the conformal mapping function of rectangle-plate with arc radius between... By conformal mapping theory, a trigonometric interpolation method between odd and even sequences in rectangle boundary region was provided, and the conformal mapping function of rectangle-plate with arc radius between complicated region and unite dish region was carried out. Aiming at calculating the vibrating fundamental frequency of special-shaped, elastic simple-supported rectangle-plates, in the in-plane state of constant stress, the vibration function of this complicated plate was depicted by unit dish region. The coefficient of ftmdamental frequency was calculated. Whilst, taking simple-supported elastic rectangle-plates with arc radius as an example, the effects on fundamental frequency caused by the concentrated mass and position, the ratio of the length to width of rectangle, as well as the coefficient of constant in-plane stress were analyzed respectively. 展开更多
关键词 conformal mapping elastic simple-supported plates vibration fundamental frequency mode method of trigonometric interpolation
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Effect of concrete creep on pre-camber of continuous rigid-frame bridge
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作者 贺国京 李媛媛 +1 位作者 邹中权 段靓靓 《Journal of Central South University》 SCIE EI CAS 2008年第S1期337-341,共5页
The effect of concrete creep on the pre-camber of a long-span pre-stressed concrete continuous rigid-frame bridge constructed by cantilever casting method was investigated.The difference of creep coefficients calculat... The effect of concrete creep on the pre-camber of a long-span pre-stressed concrete continuous rigid-frame bridge constructed by cantilever casting method was investigated.The difference of creep coefficients calculated with two Chinese codes was discussed.Based on the calculations,the pre-camber of a pre-stressed concrete continuous rigid-frame box bridge was computed for construction control purpose.The results show that the short-term creep coefficient and long-term creep coefficient calculated with the CC-1985 are larger than those calculated with the CC-2004,while the medium-term creep coefficient calculated with the CC-1985 is smaller than that calculated with the CC-2004.The difference of creep deformation calculated with these two codes is small,and the influences of concrete creep on the pre-camber for most of the segments are negligible.The deflections and stresses of the box girder measured during the construction stages agree very well with the predictions. 展开更多
关键词 CREEP pre-stressed concrete continuous rigid-frame bridge CANTILEVER CASTING method PRE-CAMBER
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A method for extracting anomaly map of Au and As using combination of U-statistic and Euclidean distance methods in Susanvar district,Iran
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作者 Seyyed Saeed Ghannadpour Ardeshir Hezarkhani Mostafa Sharifzadeh 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第11期2693-2704,共12页
Quantitative descriptions of geochemical patterns and providing geochemical anomaly map are important in applied geochemistry. Several statistical methodologies are presented in order to identify and separate geochemi... Quantitative descriptions of geochemical patterns and providing geochemical anomaly map are important in applied geochemistry. Several statistical methodologies are presented in order to identify and separate geochemical anomalies. The U-statistic method is one of the most important structural methods and is a kind of weighted mean that surrounding points of samples are considered in U value determination. However, it is able to separate the different anomalies based on only one variable. The main aim of the presented study is development of this method in a multivariate mode. For this purpose, U-statistic method should be combined with a multivariate method which devotes a new value to each sample based on several variables. Therefore, at the first step, the optimum p is calculated in p-norm distance and then U-statistic method is applied on p-norm distance values of the samples because p-norm distance is calculated based on several variables. This method is a combination of efficient U-statistic method and p-norm distance and is used for the first time in this research. Results show that p-norm distance of p=2(Euclidean distance) in the case of a fact that Au and As can be considered optimized p-norm distance with the lowest error. The samples indicated by the combination of these methods as anomalous are more regular, less dispersed and more accurate than using just the U-statistic or other nonstructural methods such as Mahalanobis distance. Also it was observed that the combination results are closely associated with the defined Au ore indication within the studied area. Finally, univariate and bivariate geochemical anomaly maps are provided for Au and As, which have been respectively prepared using U-statistic and its combination with Euclidean distance method. 展开更多
关键词 mineral ANOMALY Susanvar DISTRICT U-STATISTIC method Euclidean distance BIVARIATE ANOMALY map
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Multiobjective maintenance optimization of the continuously monitored deterioration system
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作者 Changyou Li Minqiang Xu +1 位作者 Song Guo Rixin Wang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2010年第5期791-797,共7页
With the development of the monitoring technology,it is more and more common that the system is continuously monitored.Therefore,the research on the maintenance optimization of the continuously monitored deterioration... With the development of the monitoring technology,it is more and more common that the system is continuously monitored.Therefore,the research on the maintenance optimization of the continuously monitored deterioration system is important.The deterioration process of the discussed system is described by a Gamma process.The predictive maintenance is considered to be imperfect and formulated.The expected interval of two continuous preventive maintenances is derived.Then,the maintenance optimization model of the continuously monitored deterioration system is presented.In the model,the minimization of the expected operational cost per unit time and the maximization of the system availability are the optimization objectives.The improved ideal point method with the normalized objective functions is employed to solve the proposed model.The validity and sensitivity of the proposed multiobjective maintenance optimization model are analyzed by a numerical example. 展开更多
关键词 monitoring continuously multiobjective decision maintenance optimization AVAILABILITY COST normalized ideal point method.
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Optimization of Process Parameters of Continuous Microwave Drying Raspberry Puree Based on RSM and ANN-GA 被引量:2
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作者 Zheng Xian-zhe Gao Feng +2 位作者 Fu Ke-sen Lu Tian-lin Zhu Chong-hao 《Journal of Northeast Agricultural University(English Edition)》 CAS 2023年第1期69-84,共16页
To improve drying uniformity and anthocyanin content of the raspberry puree dried in a continuous microwave dryer,the effects of process parameters(microwave intensity,air velocity,and drying time)on evaluation indexe... To improve drying uniformity and anthocyanin content of the raspberry puree dried in a continuous microwave dryer,the effects of process parameters(microwave intensity,air velocity,and drying time)on evaluation indexes(average temperature,average moisture content,average retention rate of the total anthocyanin content,temperature contrast value,and moisture dispersion value)were investigated via the response surface method(RSM)and the artificial neural network(ANN)with genetic algorithm(GA).The results showed that the microwave intensity and drying time dominated the changes of evaluation indexes.Overall,the ANN model was superior to the RSM model with better estimation ability,and higher drying uniformity and anthocyanin retention rate were achieved for the ANN-GA model compared with RSM.The optimal parameters were microwave intensity of 5.53 W•g^(-1),air velocity of 1.22 m·s^(-1),and drying time of 5.85 min.This study might provide guidance for process optimization of microwave drying berry fruits. 展开更多
关键词 raspberry puree continuous microwave drying response surface method(RSM) artificial neural network(ANN) genetic algorithm(GA)CLC number:TG376 Document code:A Article ID:1006-8104(2023)-01-0069-16
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Analytical solution to mapping rail deformation under bridge transverse deformation using energy variational principle
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作者 LAI Zhi-peng JIANG Li-zhong +3 位作者 ZHOU Wang-bao LIU Xiang YU Jian ZHANG Yun-tai 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第8期2654-2664,共11页
The track geometry is a critical factor that affects the running safety and riding comfort of trains moving on a high-speed railway bridge.This study addresses the mapping relationship between the track deformation an... The track geometry is a critical factor that affects the running safety and riding comfort of trains moving on a high-speed railway bridge.This study addresses the mapping relationship between the track deformation and lateral deformations of bridges.Equilibrium equations and natural boundary conditions of the track-bridge system are established based on the energy variational principle,and an analytical solution is derived for the track deformation accounting for lateral bridge deformations.A five-span simply-supported bridge with continuous welded rail has been selected as the case study.The mapping rail deformations are compared to the finite element results,and both results agree well with each other,validating the analytical method proposed in this paper.The influence factors on the mapping rail deformation are further evaluated.Results show that the mapping rail deformation is consistent with the girder displacement at the area that is away from the girder ends when the flexural stiffness ratio between the track and the bridge girder is low.The interlayer stiffness has a significant effect on the mapping rail deformation when the track flexural stiffness is of a high value. 展开更多
关键词 energy variational principle simply-supported beam bridge high-speed railway continuous welded rail mapping rail deformation
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过滤函数对拓扑优化效率和灰度单元的影响 被引量:1
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作者 杜家政 陈炬 李功明 《北京工业大学学报》 北大核心 2025年第5期523-538,572,共17页
为了提高拓扑优化效率和减少灰度单元的数量,基于独立连续映射(independent continuous mapping,ICM)方法引入幂函数、复合指数型函数以及有理分式函数作为过滤函数,建立以质量最小为目标、位移为约束的拓扑优化模型。通过数值算例,研究... 为了提高拓扑优化效率和减少灰度单元的数量,基于独立连续映射(independent continuous mapping,ICM)方法引入幂函数、复合指数型函数以及有理分式函数作为过滤函数,建立以质量最小为目标、位移为约束的拓扑优化模型。通过数值算例,研究了3种过滤函数以及单元质量和单元刚度过滤函数的参数比对拓扑优化效率和灰度单元的影响。数值算例表明有理分式函数能有效减少中间灰度单元数量,提高收敛速度,降低结构质量。对于幂函数,当单元质量和单元刚度过滤函数的参数比为1∶7时效果最佳;对于复合指数型函数,当单元质量和单元刚度过滤函数的参数比为1.3∶0.1时效果最佳;对于有理分式过滤函数,当单元质量和单元刚度过滤函数的参数比为3∶63时效果最佳。 展开更多
关键词 ICM方法 过滤函数 拓扑优化 位移约束 优化效率 灰度单元
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基于ORB-SLAM3视觉与惯导融合的煤矿机器人定位算法研究 被引量:2
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作者 陈伟 巫帅达 +2 位作者 田子建 张帆 刘毅 《煤炭科学技术》 北大核心 2025年第S1期297-307,共11页
针对煤矿井下空间狭窄、光线昏暗且严重不均匀使矿井图像存在照度低、纹理稀疏、颜色失真等缺陷,严重影响了视觉SLAM特征点提取匹配结果,导致定位性能急剧下降,提出1种基于改进ORB-SLAM3算法的煤矿移动机器人单目视觉定位算法。首先对OR... 针对煤矿井下空间狭窄、光线昏暗且严重不均匀使矿井图像存在照度低、纹理稀疏、颜色失真等缺陷,严重影响了视觉SLAM特征点提取匹配结果,导致定位性能急剧下降,提出1种基于改进ORB-SLAM3算法的煤矿移动机器人单目视觉定位算法。首先对ORB-SLAM3定位算法进行改进,在前端特征点提取(ORB)算法的基础上引入了直方图均衡化、非极大值抑制法、自适应阈值法以及基于四叉树策略的特征点均匀化性质;然后在特征点匹配工作中,引入了基于图像金字塔的LK光流法,减少优化的迭代次数,在特征点匹配完成后加入RANSAC算法去除误匹配的特征点,提高特征点的匹配准确率。在后端通过三角测量的方法,得到像素的深度信息,将2D-2D位姿求解问题转化成3D-2D(pnp)位姿求解问题。根据视觉惯导紧耦合的原理,通过融合视觉残差和IMU残差构建整个定位系统的残差函数,并使用基于非线性优化的滑动窗口BA算法不断迭代优化残差函数,获取精确的移动机器人位姿估计。将改进后的算法在4个数据集下与ORB-SLAM3算法以及VINSMono算法进行了充分的对比实验。研究表明:(1)相比于ORB-SLAM3算法以及VINS-Mono算法,提出定位系统的运动轨迹和真值轨迹最接近;(2)提出定位系统的APE各项指标均优于ORB-SLAM3算法以及VINS-Mono算法;(3)提出定位系统均方根误差为0.049 m(4次实验平均值),相较于ORBSLAM3均方根误差降低了31.1%(四次实验平均值)。 展开更多
关键词 单目视觉 惯性导航 移动机器人 视觉SLAM(即时定位与地图构建)定位 LK光流法
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基于状态空间离散的非线性动力系统全局分析方法进展:从模型驱动到数据驱动
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作者 李自刚 洪灵 江俊 《力学进展》 北大核心 2025年第3期455-496,共42页
非线性动力系统的一切响应行为均受制于其内在的全局结构,诸如多稳吸引子及其影响域的形貌和空间分布,不稳定不变集和不变流形等.因而,在指定状态空间内开展全局分析,不仅可以获得认识和预测系统响应的全部信息,还能深刻揭示诱发系统复... 非线性动力系统的一切响应行为均受制于其内在的全局结构,诸如多稳吸引子及其影响域的形貌和空间分布,不稳定不变集和不变流形等.因而,在指定状态空间内开展全局分析,不仅可以获得认识和预测系统响应的全部信息,还能深刻揭示诱发系统复杂分岔、激变或边界蜕变等众多动力学现象的内在机制.目前,数值方法仍是非线性动力系统全局分析的最有效手段.相较于点尺度的数值积分方法或点映射法,基于状态空间离散思想的方法(如:胞映射方法等),其采用子集覆盖来逼近系统的不变集,一方面可以高效刻画系统的全局结构形貌,另一方面可以实现对相邻轨道动态特征的集合表征.胞映射方法经历40余年的发展,其功能不断增强,计算效率和精度已显著提升,应用场景也逐渐拓宽.本文第2节从当前的视角对状态空间离散方式进行简要归类,以便于读者更好地了解在全局分析实施过程中该框架体系的本质及优势.第3节着重介绍近些年提出的一系列状态空间离散方法,展示在非线性系统全局结构的高效刻画和内在特征的数据表征两方面已取得的最新进展,突出全局分析从模型驱动向数据驱动的思维模式转变.第4节总结意义和价值,并就如何在状态空间离散框架下进一步泛化全局分析的概念,以及应对未来发展和应用需求可能面临的问题和可以拓展的方向提出见解. 展开更多
关键词 状态空间离散 全局分析 胞映射方法 模型驱动 数据驱动
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地心运动的时变分析与预报
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作者 魏二虎 吴俊杰 +4 位作者 张云龙 罗一乐 邹贤才 田晓静 刘经南 《大地测量与地球动力学》 北大核心 2025年第4期331-338,共8页
以美国德克萨斯大学空间研究中心提供的地心运动时间序列为实验数据,首先采用经验模态分解(empirical mode decomposition,EMD)对数据进行降噪处理;然后利用快速傅里叶变换(fast Fourier transform,FFT)和连续小波变换(continuous wavel... 以美国德克萨斯大学空间研究中心提供的地心运动时间序列为实验数据,首先采用经验模态分解(empirical mode decomposition,EMD)对数据进行降噪处理;然后利用快速傅里叶变换(fast Fourier transform,FFT)和连续小波变换(continuous wavelet transform,CWT)对该数据进行频域转换、功率谱分析和周期项提取;最后采用自回归积分滑动平均(autoregressive integrated moving average,ARIMA)模型和指数平滑法对未来20个月的地心运动进行预报。结果表明,利用FFT提取的周年项的振幅和相位与以往的地心运动研究较为接近;ARIMA模型对于Y方向20个月内的地心运动预测结果较好,指数平滑法对X、Z方向的地心运动预测结果更优。 展开更多
关键词 地心运动 快速傅里叶变换 连续小波变换 ARIMA 指数平滑法
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