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液压起重机操作自由悬浮载荷的动态特性(英文) 被引量:4
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作者 Bozhidar GRIGOROV Rosen MITREV 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2017年第4期268-281,共14页
目的:对载有自由悬浮载荷的液压驱动起重机的动态特性分别在升降运动和回转运动两种工况下进行研究,建立动力学模型并验证其正确性。创新点:1.为了简化任务,将两种运动分开讨论。一次只考虑一种运动,把起重机看作具有三个转动关节连接... 目的:对载有自由悬浮载荷的液压驱动起重机的动态特性分别在升降运动和回转运动两种工况下进行研究,建立动力学模型并验证其正确性。创新点:1.为了简化任务,将两种运动分开讨论。一次只考虑一种运动,把起重机看作具有三个转动关节连接的运动链;2.为起重臂的运动问题构造微分方程,使用了通用的牛顿-欧拉算法;3.对运动和动力模型进行仿真,得到摆动角度、液压压强和连接作用力随时间的变化曲线,并通过实验进行了验证。方法:1.建立系统的运动和动力模型,分别对回转运动和升降运动两种工况下的液压缸压强进行推导;2.在两种工况下,对起重臂转角、液压缸压力和最大行程前臂液压缸反作用力进行仿真计算;3.将实验获得的有关参数的曲线与仿真得到的曲线进行对比,验证模型的正确性。结论:1.在液压起重机运动期间悬浮载荷的摆动对起重机的机械系统和液压驱动系统本身具有强烈的影响,所以在系统设计中不能忽视;2.系统性能提升的主要方向是安装控制系统以减小载荷摆动(特别是在起重机回转运动时);3.本文建立的考虑了负载的大角度摆动和液压驱动系统的动力学模型得到了验证,表明其对起重机运动仿真的适用性。尽管分开考虑了两种典型运动,但所用的建模方法还是适合对起重机一般运动的研究。 展开更多
关键词 液压起重机 载荷摆动 牛顿欧拉方法 液压驱动
原文传递
Hierarchical dynamic modeling for highway network real-time risk forecasting with digitalized vehicle data
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作者 Donghyoek Park Nuri Park +2 位作者 Songha Lee Juneyoung Park Ducknyung Kim 《International Journal of Transportation Science and Technology》 2025年第3期256-268,共13页
In traffic safety management,identifying high-risk areas prone to traffic crashes is crucial.Road authorities focus on these high-risk segments to implement strategies that mitigate the impact of recurring crashes.How... In traffic safety management,identifying high-risk areas prone to traffic crashes is crucial.Road authorities focus on these high-risk segments to implement strategies that mitigate the impact of recurring crashes.However,errors in identifying these hotspots can lead to inefficient resource allocation for safety improvements.These errors often stem from the reliance on aggregated traffic data for predicting crash frequency(CF).The road traffic system is characterized by the interaction of human,vehicle,and road factors,and is inherently complex.While many researchers have used components of the road traffic systems in safety evaluation studies,the use of recurrent traffic patterns remains underexplored.To address this issue,this study proposes a method for hotspot identification that utilizes safety performance analysis derived from real-time traffic data and a model with various crash factors.This paper proposes a hotspot identification approach using a real-time crash prediction model for high-risk traffic patterns.Specifically,a real-time crash prediction model is developed using logistic regression to estimate the likelihood of crashes under high-risk traffic patterns.The model integrates real-time data on traffic,weather,and road geometry to estimate these probabilities.Spearman’s correlation analysis was performed to validate the proposed method.This study reveals a strong correlation between the target frequency—a measure combining crashes and hard braking events—and the number of hazardous traffic patterns identified by the real-time crash prediction model. 展开更多
关键词 Real-time crash prediction Safety performance analysis Probabilistic model Logistic regression
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