Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can b...Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.展开更多
Traditional track dynamic geometric state(TDGS)simulation incurs substantial computational burdens,posing challenges for developing reliability assessment approach that accounts for TDGS.To overcome these,firstly,a si...Traditional track dynamic geometric state(TDGS)simulation incurs substantial computational burdens,posing challenges for developing reliability assessment approach that accounts for TDGS.To overcome these,firstly,a simulation-based TDGS model is established,and a surrogate-based model,grid search algorithm-particle swarm optimization-genetic algorithm-multi-output least squares support vector regression,is established.Among them,hyperparameter optimization algorithm’s effectiveness is confirmed through test functions.Subsequently,an adaptive surrogate-based probability density evolution method(PDEM)considering random track geometry irregularity(TGI)is developed.Finally,taking curved train-steel spring floating slab track-U beam as case study,the surrogate-based model trained on simulation datasets not only shows accuracy in both time and frequency domains,but also surpasses existing models.Additionally,the adaptive surrogate-based PDEM shows high accuracy and efficiency,outperforming Monte Carlo simulation and simulation-based PDEM.The reliability assessment shows that the TDGS part peak management indexes,left/right vertical dynamic irregularity,right alignment dynamic irregularity,and track twist,have reliability values of 0.9648,0.9918,0.9978,and 0.9901,respectively.The TDGS mean management index,i.e.,track quality index,has reliability value of 0.9950.These findings show that the proposed framework can accurately and efficiently assess the reliability of curved low-stiffness track-viaducts,providing a theoretical basis for the TGI maintenance.展开更多
目的探索能否依据入院常规检查结果及一般资料对中老年住院患者骨质疏松风险进行筛查。方法选取2023年6月至2024年6月因脊柱脆性骨折于泰州市第二人民医院住院治疗的中老年患者。收集患者的人口统计学信息、入院常规检查结果以及骨密度...目的探索能否依据入院常规检查结果及一般资料对中老年住院患者骨质疏松风险进行筛查。方法选取2023年6月至2024年6月因脊柱脆性骨折于泰州市第二人民医院住院治疗的中老年患者。收集患者的人口统计学信息、入院常规检查结果以及骨密度数据,通过组间比较、相关因素二元Logistic回归以及ROC曲线进行统计分析。结果组间比较结果显示,与非骨质疏松组相比,骨质疏松组的身高、亚洲人骨质疏松自我筛查工具(osteoporosis self-assessment tool for Asians,OSTA)、血红蛋白、白蛋白显著降低,下肢动脉粥样硬化阳性率显著增高(P<0.05);二元Logistic回归分析结果显示,OSTA与下肢动脉粥样硬化是骨质疏松症发病的相关因素,OR值分别为8.926和3.971(P<0.05)。ROC曲线结果显示,单独OSTA对骨质疏松风险具有良好的筛查效果(AUC为0.795,P<0.05),OSTA联合下肢血管粥样硬化进一步提高了对骨质疏松风险的筛查效果(AUC为0.835,P<0.05)。结论OSTA与下肢血管粥样硬化在骨质疏松发生、发展中具有相关性。对于中老年患者,可通过由年龄、体重计算而得的OSTA以及入院常规中的下肢血管超声进行骨质疏松风险评估,以达到简便、经济的筛查效果。展开更多
水培叶菜产出高、效益好的同时生产设备成本投入较大,优化出适宜的种植密度,可以使单位面积产出最大化,从而保证种植者取得较高的收益。本研究采用熵权法和TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution)...水培叶菜产出高、效益好的同时生产设备成本投入较大,优化出适宜的种植密度,可以使单位面积产出最大化,从而保证种植者取得较高的收益。本研究采用熵权法和TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution)法结合,对不同种植密度水培生菜进行综合评价,优化出适宜种植密度,为水培装置适宜的生菜种植密度提供依据。共设置4个密度处理,标记为H1、H2、H3、H4(定植密度为株间距10、15、20、25 cm),通过对各处理生菜生长,产量,品质,水分利用效率等因子综合评价,优化出适宜种植密度。结果表明:H4处理水培生菜产量和品质较处理H1略差,但其生长状态、外观品质优于H1,对比所有处理生菜,H2处理综合表现最佳,更适合商业化种植,该研究结果有助于进一步了解种植密度对水培生菜生长、产量品质的综合影响,还可为规模化商业水培叶菜生产提供支持。展开更多
针对点云数据中噪声点的剔除问题,提出了一种基于改进DBSCAN(density-based spatial clustering of applications with noise)算法的多尺度点云去噪方法。应用统计滤波对孤立离群点进行预筛选,去除点云中的大尺度噪声;对DBSCAN算法进行...针对点云数据中噪声点的剔除问题,提出了一种基于改进DBSCAN(density-based spatial clustering of applications with noise)算法的多尺度点云去噪方法。应用统计滤波对孤立离群点进行预筛选,去除点云中的大尺度噪声;对DBSCAN算法进行优化,减少算法时间复杂度和实现参数的自适应调整,以此将点云分为正常簇、疑似簇及异常簇,并立即去除异常簇;利用距离共识评估法对疑似簇进行精细判定,通过计算疑似点与其最近的正常点拟合表面之间的距离,判定其是否为异常,有效保持了数据的关键特征和模型敏感度。利用该方法对两个船体分段点云进行去噪,并与其他去噪算法进行对比,结果表明,该方法在去噪效率和特征保持方面具有优势,精确地保留了点云数据的几何特性。展开更多
基金Project(2023YFB4302500)supported by the National Key R&D Program of ChinaProject(52078485)supported by the National Natural Science Foundation of ChinaProjects(2021-Major-16,2021-Special-08)supported by the Science and Technology Research and Development Program Project of China Railway Group Limited。
文摘Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.
基金Project(52072412)supported by the National Natural Science Foundation of China。
文摘Traditional track dynamic geometric state(TDGS)simulation incurs substantial computational burdens,posing challenges for developing reliability assessment approach that accounts for TDGS.To overcome these,firstly,a simulation-based TDGS model is established,and a surrogate-based model,grid search algorithm-particle swarm optimization-genetic algorithm-multi-output least squares support vector regression,is established.Among them,hyperparameter optimization algorithm’s effectiveness is confirmed through test functions.Subsequently,an adaptive surrogate-based probability density evolution method(PDEM)considering random track geometry irregularity(TGI)is developed.Finally,taking curved train-steel spring floating slab track-U beam as case study,the surrogate-based model trained on simulation datasets not only shows accuracy in both time and frequency domains,but also surpasses existing models.Additionally,the adaptive surrogate-based PDEM shows high accuracy and efficiency,outperforming Monte Carlo simulation and simulation-based PDEM.The reliability assessment shows that the TDGS part peak management indexes,left/right vertical dynamic irregularity,right alignment dynamic irregularity,and track twist,have reliability values of 0.9648,0.9918,0.9978,and 0.9901,respectively.The TDGS mean management index,i.e.,track quality index,has reliability value of 0.9950.These findings show that the proposed framework can accurately and efficiently assess the reliability of curved low-stiffness track-viaducts,providing a theoretical basis for the TGI maintenance.
文摘目的探索能否依据入院常规检查结果及一般资料对中老年住院患者骨质疏松风险进行筛查。方法选取2023年6月至2024年6月因脊柱脆性骨折于泰州市第二人民医院住院治疗的中老年患者。收集患者的人口统计学信息、入院常规检查结果以及骨密度数据,通过组间比较、相关因素二元Logistic回归以及ROC曲线进行统计分析。结果组间比较结果显示,与非骨质疏松组相比,骨质疏松组的身高、亚洲人骨质疏松自我筛查工具(osteoporosis self-assessment tool for Asians,OSTA)、血红蛋白、白蛋白显著降低,下肢动脉粥样硬化阳性率显著增高(P<0.05);二元Logistic回归分析结果显示,OSTA与下肢动脉粥样硬化是骨质疏松症发病的相关因素,OR值分别为8.926和3.971(P<0.05)。ROC曲线结果显示,单独OSTA对骨质疏松风险具有良好的筛查效果(AUC为0.795,P<0.05),OSTA联合下肢血管粥样硬化进一步提高了对骨质疏松风险的筛查效果(AUC为0.835,P<0.05)。结论OSTA与下肢血管粥样硬化在骨质疏松发生、发展中具有相关性。对于中老年患者,可通过由年龄、体重计算而得的OSTA以及入院常规中的下肢血管超声进行骨质疏松风险评估,以达到简便、经济的筛查效果。
文摘水培叶菜产出高、效益好的同时生产设备成本投入较大,优化出适宜的种植密度,可以使单位面积产出最大化,从而保证种植者取得较高的收益。本研究采用熵权法和TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution)法结合,对不同种植密度水培生菜进行综合评价,优化出适宜种植密度,为水培装置适宜的生菜种植密度提供依据。共设置4个密度处理,标记为H1、H2、H3、H4(定植密度为株间距10、15、20、25 cm),通过对各处理生菜生长,产量,品质,水分利用效率等因子综合评价,优化出适宜种植密度。结果表明:H4处理水培生菜产量和品质较处理H1略差,但其生长状态、外观品质优于H1,对比所有处理生菜,H2处理综合表现最佳,更适合商业化种植,该研究结果有助于进一步了解种植密度对水培生菜生长、产量品质的综合影响,还可为规模化商业水培叶菜生产提供支持。
文摘针对点云数据中噪声点的剔除问题,提出了一种基于改进DBSCAN(density-based spatial clustering of applications with noise)算法的多尺度点云去噪方法。应用统计滤波对孤立离群点进行预筛选,去除点云中的大尺度噪声;对DBSCAN算法进行优化,减少算法时间复杂度和实现参数的自适应调整,以此将点云分为正常簇、疑似簇及异常簇,并立即去除异常簇;利用距离共识评估法对疑似簇进行精细判定,通过计算疑似点与其最近的正常点拟合表面之间的距离,判定其是否为异常,有效保持了数据的关键特征和模型敏感度。利用该方法对两个船体分段点云进行去噪,并与其他去噪算法进行对比,结果表明,该方法在去噪效率和特征保持方面具有优势,精确地保留了点云数据的几何特性。
