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Searching Activity Tra jectories with Semantics
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作者 Li-Hua Yin Huiwen Liu 《计算机科学技术学报:英文版》 SCIE EI CSCD 2019年第4期775-794,共20页
With the widespread use of smart phones and mobile Internet,social network users have generated massive geo-tagged tweets,photos and videos to form lots of informative trajectories which reveal not only their spatio-t... With the widespread use of smart phones and mobile Internet,social network users have generated massive geo-tagged tweets,photos and videos to form lots of informative trajectories which reveal not only their spatio-temporal dynamics,but also their activities in the physical world.Existing spatial trajectory query studies mainly focus on analyzing the spatio-temporal properties of the users'trajectories,while leaving the understanding of their activities largely untouched.In this paper,we incorporate the semantics of the activity information embedded in trajectories into query modelling and processing,with the aim of providing end users more informative and meaningful results.To this end,we propose a novel trajectory query that not only considers the spatio-temporal closeness but also,more importantly,leverages a proven technique in text mining field,probabilistic topic modelling,to capture the semantic relatedness of the activities between the data and query.To support efficient query processing,we design a hierarchical grid-based index by integrating the probabilistic topic distribution on the substructures of trajectories and their spatio-temporal extent at the corresponding level of the index hierarchy.This specialized structure enables a top-down search algorithm to traverse the index while pruning unqualified trajectories in spatial and topical dimensions simultaneously.The experimental results on real-world datasets demonstrate the good efficiency and scalability performance of the proposed indices and trajectory search methods. 展开更多
关键词 SPATIO-TEMPORAL database ACTIVITY TRAJECTORY semantic understanding TRAJECTORY INDEXING TRAJECTORY QUERY processing
Improved Qualitative Trajectory Calculus for Pair-Activity Analysis 预览
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作者 Shengsheng Wang Guangyao Wang +1 位作者 Yungang Zhu Jingwen Shao 《北京理工大学学报:英文版》 EI CAS 2019年第2期318-326,共9页
Trajectory provides the most robust feature for activity recognition in far-field surveillance videos,in which increasing attentions have been given to the use of qualitative methods with symbolic rather than real-val... Trajectory provides the most robust feature for activity recognition in far-field surveillance videos,in which increasing attentions have been given to the use of qualitative methods with symbolic rather than real-value features.Qualitative trajectory calculus(QTC)showed a good performance in pair-activity from video.However,QTC and similar works are not good at dealing with noise,since they are all considering short-term features.To deal with the problems mentioned above,two types of long-term features,including sub-trajectory feature and point-trajectory feature,are designed.The sub-trajectory feature is a long-term feature in a coarse granularity,while the point-trajectory feature is a long-term feature in a relatively fine granularity.Using the sub-trajectory feature,a couple of trajectories are segmented into sub-trajectories and enveloping boxes are used to substitute the original sub-trajectory for capturing the major attributes.The point-trajectory feature describes the relationship between a single point in one trajectory and all parts of the other trajectory.The experiments on the human activity classification data demonstrated that our proposed methods are better than the original QTC and previous short-term features. 展开更多
关键词 pair-activity analysis qualitative TRAJECTORY CALCULUS sub-trajectory FEATURE point-trajectory FEATURE
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融合特征熵的轨迹结构异常检测方法 预览
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作者 裴浩然 袁冠 +2 位作者 张艳梅 李月娥 李思宁 《陕西师范大学学报:自然科学版》 CAS CSCD 北大核心 2019年第5期16-24,共9页
从轨迹结构特征出发,分析轨迹内部及整体特征,提出融合特征熵的轨迹结构异常检测方法(TSAD-FE,trajectory structure anomaly detection method based on feature entropy)。根据开放角将轨迹划分为轨迹片段,运用线性回归模型对轨迹片... 从轨迹结构特征出发,分析轨迹内部及整体特征,提出融合特征熵的轨迹结构异常检测方法(TSAD-FE,trajectory structure anomaly detection method based on feature entropy)。根据开放角将轨迹划分为轨迹片段,运用线性回归模型对轨迹片段局部特征进行拟合,完成轨迹片段划分;引入轨迹结构框架描述轨迹内部特征属性,应用轨迹结构距离衡量轨迹片段之间的距离,并提出利用熵对特征权重赋值的方法,全面考虑轨迹内部特征对轨迹的影响;运用DBSCAN(density-based spatial clustering of applications with noise)聚类算法将轨迹集划分为若干簇并提取代表轨迹;通过比较轨迹片段与代表轨迹的结构相似度,提取异常轨迹片段,从轨迹整体上考虑异常轨迹片段占比,进而挖掘出异常轨迹。使用多个数据集的实验表明,融合特征熵的轨迹结构异常检测方法能够从轨迹空间形态及内部特征属性上发现异常,可以全面地发现明显异常轨迹及其分段,使检测结果更具有实际意义。 展开更多
关键词 轨迹 结构相似度 异常检测 轨迹划分 人工智能
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Trajectory Big Data Processing Based on Frequent Activity
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作者 Amina Belhassena Hongzhi Wang 《清华大学学报自然科学版(英文版)》 EI CAS CSCD 2019年第3期317-332,共16页
With the rapid development and wide use of Global Positioning System in technology tools, such as smart phones and touch pads, many people share their personal experience through their trajectories while visiting plac... With the rapid development and wide use of Global Positioning System in technology tools, such as smart phones and touch pads, many people share their personal experience through their trajectories while visiting places of interest. Therefore, trajectory query processing has emerged in recent years to help users find their best trajectories. However, with the huge amount of trajectory points and text descriptions, such as the activities practiced by users at these points, organizing these data in the index becomes tedious. Therefore, the parallel method becomes indispensable. In this paper, we have investigated the problem of distributed trajectory query processing based on the distance and frequent activities. The query is specified by start and final points in the trajectory, the distance threshold, and a set of frequent activities involved in the point of interest of the trajectory.As a result, the query returns the shortest trajectory including the most frequent activities with high support and high confidence. To simplify the query processing, we have implemented the Distributed Mining Trajectory R-Tree index(DMTR-Tree). For this method, we initially managed the large trajectory dataset in distributed R-Tree indexes.Then, for each index, we applied the frequent itemset Apriori algorithm for each point to select the frequent activity set. For the faster computation of the above algorithms, we utilized the cluster computing framework of Apache Spark with MapReduce as the programing model. The experimental results show that the DMTR-Tree index and the query-processing algorithm are efficient and can achieve the scalability. 展开更多
关键词 DISTRIBUTED R-TREE TRAJECTORY frequent ACTIVITY QUERY
Trajectory planning-based control of underactuated wheeled inverted pendulum robots
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作者 Dingkun LIANG Ning SUN +1 位作者 Yiming WU Yongchun FANG 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第5期23-25,共3页
Dear editor,In modern industries, underactuated mechanical systems play an important role in various fields (1–6)The wheeled inverted pendulum robot(WIPR) is a special type of non-linear and underactuated systems wit... Dear editor,In modern industries, underactuated mechanical systems play an important role in various fields (1–6)The wheeled inverted pendulum robot(WIPR) is a special type of non-linear and underactuated systems with strong state coupling.Typically, such a robot comprises two actuated wheels and three to-be-controlled state variables。 展开更多
关键词 Trajectory planning-based CONTROL of UNDERACTUATED WHEELED inverted pendulum ROBOTS Figure
6R工业机械手Adams中空间曲线位姿规划 预览
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作者 周会勇 苏工兵 +1 位作者 袁浪佳 刘天祥 《机械传动》 北大核心 2019年第7期41-45,共5页
机械手空间轨迹和姿态的规划常采用插补计算完成,提出了一种以参数方程式表达的空间圆曲线为基础,通过离散计算空间圆曲线伏雷内标架,获取机械手末端工具在空间圆曲线离散点姿态,反解出卡尔丹角,并在Matlab进行拟合的方法,实现空间曲线... 机械手空间轨迹和姿态的规划常采用插补计算完成,提出了一种以参数方程式表达的空间圆曲线为基础,通过离散计算空间圆曲线伏雷内标架,获取机械手末端工具在空间圆曲线离散点姿态,反解出卡尔丹角,并在Matlab进行拟合的方法,实现空间曲线轨迹和姿态规划。以川崎BA006N型6自由度机械手本体机构参数为依据,在Adams软件中构建机械手仿真平台,以空间圆参数方程和拟合后卡尔丹角参数方程为驱动函数,仿真分析表明,机械手末端工具能准确地跟踪空间圆曲线轨迹和姿态,从而利用Adams分别提取机械手6个关节的角位移、角速度、角加速度和力矩。该方法不仅避免了逆运动学计算,也为控制系统设计和其他空间曲线和曲面轨迹和姿态的规划提供了一种新方法。 展开更多
关键词 空间圆曲线 伏雷内标架 卡尔丹角 轨迹 姿态 ADAMS
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喷水试验机绞车系统钢丝绳轨迹及力学特性研究 预览
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作者 张锋 郝琳召 《机械工程师》 2019年第3期90-92,共3页
喷水试验机绞车系统钢丝绳轨迹及力学特性的准确分析关系到整个桁杆系统的安全收放。参考工程力学弹性柔索的分析方法,计算了在空气动力的作用下,机身外围钢丝绳的轨迹及力学特性,研究了钢丝绳张力、力矩及轨迹随桁杆系统下放角度、钢... 喷水试验机绞车系统钢丝绳轨迹及力学特性的准确分析关系到整个桁杆系统的安全收放。参考工程力学弹性柔索的分析方法,计算了在空气动力的作用下,机身外围钢丝绳的轨迹及力学特性,研究了钢丝绳张力、力矩及轨迹随桁杆系统下放角度、钢丝绳预置张力的相互关系,为桁杆控制小翼的气动设计,桁杆收放控制系统的设计以及绞车系统钢丝绳预置张力的确定等问题,提供了必要的技术输入及设计参考。 展开更多
关键词 喷水试验机 钢丝绳 柔索 轨迹 力学特性
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基于视频的交叉口目标轨迹自动采集 预览
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作者 杨轸 张秋晨 《同济大学学报:自然科学版》 EI CAS CSCD 北大核心 2019年第3期369-377,407共10页
提出了一种基于视频的交叉口内目标运动轨迹自动采集方法.首先利用ViBe(Visual Background Extractor)算法提取目标前景,然后提出了基于光流的目标跟踪OPC(object-point-contour)算法,最后基于透视变换得到目标的真实轨迹和运动参数.方... 提出了一种基于视频的交叉口内目标运动轨迹自动采集方法.首先利用ViBe(Visual Background Extractor)算法提取目标前景,然后提出了基于光流的目标跟踪OPC(object-point-contour)算法,最后基于透视变换得到目标的真实轨迹和运动参数.方法可采集交叉口内所有交通对象的类别、轨迹、速度与加速度信息,并对目标停滞与遮挡现象有较好的跟踪稳定性.经检验,该方法对机动车、非机动车和行人的轨迹提取准确率分别为88.89%、86.00%和83.33%,速度提取准确率为91.71%,为交叉口管理与安全研究提供一种视频处理和数据采集手段. 展开更多
关键词 运动轨迹 目标跟踪 视频处理 光流
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基于大数据分析的水下航行器运行轨迹规划模型研究 预览
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作者 李世科 《舰船科学技术》 北大核心 2019年第14期70-72,共3页
传统水下航行器轨迹规划计算处理过程中,受到自身算法逻辑参数影响,建模数据计算涵盖不够严谨,无法对小概率误差轨迹进行引入分析,从而导致航行器预判轨迹出现偏离。针对问题产生原因,提出基于大数据分析的水下航行器运行轨迹规划模型... 传统水下航行器轨迹规划计算处理过程中,受到自身算法逻辑参数影响,建模数据计算涵盖不够严谨,无法对小概率误差轨迹进行引入分析,从而导致航行器预判轨迹出现偏离。针对问题产生原因,提出基于大数据分析的水下航行器运行轨迹规划模型研究。首先,对传统模型计算算法进行修正,引入MFT样条差值规划算法对构建模型轨迹数据进行优选规划计算;接着引入迭代多项轨迹构造算法,对规划模型数据进行轨迹模型构建计算;最后,通过对构建模型进行仿真数据测试。通过与传统模型的对比证明提出构建的轨迹模型能够解决传统模型存在的问题与不足。 展开更多
关键词 大数据分析 水下航行器 轨迹 规划模型
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A Single-Cell RNA Sequencing Profiles the Developmental Landscape of Arabidopsis Root
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作者 Tian-Qi Zhang Zhou-Geng Xu +1 位作者 Guan-Dong Shang Jia-Wei Wang 《分子植物:英文版》 SCIE CAS CSCD 2019年第5期648-660,共13页
Cells of eukaryotic multicellular organisms have inherent heterogeneity.Recent advances in single-cell gene expression studies enable us to explore transcriptional regulation in dynamic development processes and highl... Cells of eukaryotic multicellular organisms have inherent heterogeneity.Recent advances in single-cell gene expression studies enable us to explore transcriptional regulation in dynamic development processes and highly heterogeneous cell populations.In this study,using a high-throughput single-cell RNA-sequencing assay,we found that the cells in Arabidopsis root are highly heterogeneous in their transcriptomes.A total of 24 putative cell clusters and the cluster-specific marker genes were identified.The spatial distribution and temporal ordering of the individual cells at different developmental stages illustrate their hierarchical structures and enable the reconstruction of continuous differentiation trajectory of root development.Moreover,we found that each root cell cluster exhibits distinct patterns of ion assimilation and hormonal responses.Collectively,our study reveals a high degree of heterogeneity of root cells and identifies the expression signatures of intermediate states during root cell differentiation at single-cell resolution.We also established a web server(http://wanglab.sippe.ac.cn/rootatlas/)to facilitate the use of the datasets generated in this study. 展开更多
关键词 Arabidopsis ROOT scRNA-seq cell ATLAS differentiation TRAJECTORY MERISTEM
FVID:Fishing Vessel Type Identification Based on VMS Trajectories 预览
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作者 HUANG Haiguang HONG Feng +3 位作者 LIU Jing LIU Chao FENG Yuan GUO Zhongwen 《中国海洋大学学报:英文版》 SCIE CAS CSCD 2019年第2期403-412,共10页
Vessel Monitoring System(VMS)provides a new opportunity for quantified fishing research.Many approaches have been proposed to recognize fishing activities with VMS trajectories based on the types of fishing vessels.Ho... Vessel Monitoring System(VMS)provides a new opportunity for quantified fishing research.Many approaches have been proposed to recognize fishing activities with VMS trajectories based on the types of fishing vessels.However,one research problem is still calling for solutions,how to identify the fishing vessel type based on only VMS trajectories.This problem is important because it requires the fishing vessel type as a preliminary to recognize fishing activities from VMS trajectories.This paper proposes fishing vessel type identification scheme(FVID)based only on VMS trajectories.FVID exploits feature engineering and machine learning schemes of XGBoost as its two key blocks and classifies fishing vessels into nine types.The dataset contains all the fishing vessel trajectories in the East China Sea in March 2017,including 10031 pre-registered fishing vessels and 1350 unregistered vessels of unknown types.In order to verify type identification accuracy,we first conduct a 4-fold cross-validation on the trajectories of registered fishing vessels.The classification accuracy is 95.42%.We then apply FVID to the unregistered fishing vessels to identify their types.After classifying the unregistered fishing vessel types,their fishing activities are further recognized based upon their types.At last,we calculate and compare the fishing density distribution in the East China Sea before and after applying the unregistered fishing vessels,confirming the importance of type identification of unregistered fishing vessels. 展开更多
关键词 VMS VESSEL type identification FISHING DENSITY TRAJECTORY analysis classification
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Characteristics of size distributions and sources of water-soluble ions in Lhasa during monsoon and non-monsoon seasons
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作者 Nannan Wei Zhiyou Xu +5 位作者 Junwen Liu Guanghua Wang Wei Liu Deqing Zhuoga Detao Xiao Jian Yao 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第8期155-168,共14页
To understand the physical and chemical characteristics, particle size distribution and sources of size-separated aerosols in Lhasa, which is located on the Tibetan Plateau(TP), six sizes of aerosol samples were colle... To understand the physical and chemical characteristics, particle size distribution and sources of size-separated aerosols in Lhasa, which is located on the Tibetan Plateau(TP), six sizes of aerosol samples were collected in Lhasa in 2014. Ca^2+, NH4^+, NO3^-,SO4^2-and Cl^-were the dominant ions. The ratio of cation equivalents(CE) to anion equivalents(AE) for each particle size segment indicated that the atmospheric aerosols in Lhasa were alkaline. SO4^2-and NO3-could be neutralized by Ca^2+, but could not be neutralized by NH4^+, according to the [NH4^+]/[NO3^-+ SO4^2-] and [Ca^2+]/[NO3^-+ SO4^2-] ratios. Mobile sources were dominant in PM0.95-1.5,PM1.5-3 and PM3-7.2, while stationary sources were dominant in the other three size fractions according to the [NO3^-]/[SO4^2-] ratios. The particle size distribution of all watersoluble ions during monsoon and non-monsoon periods was characterized by a bimodal distribution due to the different sources and formation mechanisms, and it was revealed that different ions had different sources in different seasons and different particle size segments by combining particle size distribution with correlation analysis. Source analysis of aerosols in Lhasa was performed using the Principal component analysis(PCA) for the first time, which revealed that combustion sources, motor vehicle exhaust, photochemical reaction sources and various types of dust were the main sources of Lhasa aerosols.Furthermore, Lhasa’s air quality was also affected by long-distance transmission, expressed as pollutants from South Asia and West Asia, which were transmitted to Lhasa according to backward trajectory analysis. 展开更多
关键词 Atmospheric AEROSOLS WATER-SOLUBLE ions(WSIs) Size distribution Principal component analysis(PCA) BACKWARD trajectory
我国老年人抑郁情绪的异质性轨迹——基于CHARLS数据 预览
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作者 黄立群 李华 +3 位作者 陈焕琴 张俊杰 张会会 蒋建平 《浙江医学教育》 2019年第4期38-40,共3页
目的:探索我国老年人的抑郁情绪异质性轨迹.方法:基于"中国健康与养老追踪调查"数据,通过增长混合模型拟合轨迹.结果:本研究构建了我国老年人抑郁情绪的5条异质性轨迹,分别是"高水平症状"、"症状缓解"、&... 目的:探索我国老年人的抑郁情绪异质性轨迹.方法:基于"中国健康与养老追踪调查"数据,通过增长混合模型拟合轨迹.结果:本研究构建了我国老年人抑郁情绪的5条异质性轨迹,分别是"高水平症状"、"症状缓解"、"症状复发"、"症状恶化"、"低水平症状".结论:我国老年人的抑郁情绪存在不同类型的轨迹,并非所有老年人都遵循相似的发展历程.近25%的老年人表现出恶化、复发或持续高水平的抑郁情绪,应引起重视. 展开更多
关键词 老年人 抑郁情绪 轨迹
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Cooperative trajectory optimization for unmanned aerial vehicles in a combat environment
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作者 Tingting BAI Daobo WANG 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第1期52-54,共3页
Dear editor,Unmanned aerial vehicles(UAVs)have been widely used in both civil and military tasks.Owing to the limited payload and economic considerations,however,a single UAV is not capable of carrying out complex tas... Dear editor,Unmanned aerial vehicles(UAVs)have been widely used in both civil and military tasks.Owing to the limited payload and economic considerations,however,a single UAV is not capable of carrying out complex tasks,such as large-scale monitoring and surveillance.Therefore,a group of UAVs is usually deployed to perform these tasks. 展开更多
关键词 COOPERATIVE TRAJECTORY optimization unmanned AERIAL VEHICLES
中国高端装备制造上市企业融资效率的实证测度--基于Super-SBM和Malquist模型 预览
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作者 曾刚 耿成轩 《科技管理研究》 CSSCI 北大核心 2019年第10期233-242,共10页
充分发挥Super-SBM精准测量融资效率值并排序的优势,利用上市公司数据计算高端装备制造企业的融资效率差异;运用Malquist模型研究综合效率指数轨迹、技术效率轨迹和技术进步效率轨迹的动态变化。研究表明,我国高端装备业整体的融资效率... 充分发挥Super-SBM精准测量融资效率值并排序的优势,利用上市公司数据计算高端装备制造企业的融资效率差异;运用Malquist模型研究综合效率指数轨迹、技术效率轨迹和技术进步效率轨迹的动态变化。研究表明,我国高端装备业整体的融资效率均值大于0.85,但大部分处于非效率状态;Malquist平均指数总体保持在1.0左右的水平,但是融资效率呈现波动性特征;技术效率指数受规模效率影响大而纯技术效率作用不明显;大部分企业注重技术创新,但是技术进步还未成为提升融资效率的主要动力源。 展开更多
关键词 高端装备制造业 上市公司 融资效率 Super-SBM模型 Malquist模型 轨迹
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“5·12”南昌大暴雨过程水汽来源和输送特征 预览
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作者 许彬 熊秋芬 +1 位作者 姜晓飞 张玉婷 《气象与减灾研究》 2019年第2期89-95,共7页
基于常规高空、地面观测资料,分析了2012年5月12日南昌大暴雨过程的环流背景和主要影响系统,并利用美国国家海洋和大气管理局(NOAA)开发的HYSPLIT模式和6h一次的NCEP1°×1°再分析资料模拟了此次大暴雨过程中气块的240h后... 基于常规高空、地面观测资料,分析了2012年5月12日南昌大暴雨过程的环流背景和主要影响系统,并利用美国国家海洋和大气管理局(NOAA)开发的HYSPLIT模式和6h一次的NCEP1°×1°再分析资料模拟了此次大暴雨过程中气块的240h后向轨迹。结果表明:1)此次大暴雨过程发生在500hPa高度层低槽前,中低层有低涡、切变线和低空急流,200hPa高度层风向分流辐散的环流背景下,且南昌位于地面冷锋前暖区中,有弱的不稳定能量等对流性降水特征。2)在模拟的南昌站6条气块后向轨迹中,有3条轨迹源自陆地,1条来自暴雨区周围,只有2条轨迹来自暖湿的海洋,其中各有3条轨迹来自对流层低层和中高层。3)此次大暴雨过程的水汽主要来自于对流层低层南海西南部向我国陆地的水汽输送和本地周围水汽的贡献,其次是位于我国西部大陆对流层中下层向东的水汽输送。 展开更多
关键词 暴雨 水汽 来源 轨迹 模拟
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吊杯式栽植器运动轨迹优化与试验 预览
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作者 刘洋 王士国 +4 位作者 毛罕平 李斌 王涛 李亚雄 韩绿化 《干旱地区农业研究》 CSCD 北大核心 2019年第3期291-298,共8页
针对吊杯式移栽机膜上成穴移栽时膜面穴口大的问题,建立栽植机构的运动模型,通过分析栽植器的运动轨迹特性得出,当栽植器的运动轨迹为余摆线,且余摆线环扣最大横弦的距离等于轨迹线与地膜交点间的距离,栽植器在上拔阶段水平方向零速度... 针对吊杯式移栽机膜上成穴移栽时膜面穴口大的问题,建立栽植机构的运动模型,通过分析栽植器的运动轨迹特性得出,当栽植器的运动轨迹为余摆线,且余摆线环扣最大横弦的距离等于轨迹线与地膜交点间的距离,栽植器在上拔阶段水平方向零速度点两侧打开,有利于减小膜面穴口尺寸。通过仿真分析和膜上移栽番茄盘苗试验得出,运动轨迹特征系数λ对膜面穴口的纵向尺寸影响显著,对横向尺寸和倾斜率影响不明显。随着λ值的增大,穴口纵向尺寸先减小然后增大,在移栽频率为50和55株·min^-1 时,λ为1.093的穴口纵向尺寸分别为10.12 cm和9.49 cm,是最小值;两种移栽频率条件下,随着λ值的增大,移栽株距分别从39.8 cm减小到33.5 cm和从39.1 cm减小到33.1 cm。该结论可用于指导吊杯式移栽机结构和工作参数的优选。 展开更多
关键词 吊杯式栽植器 运动轨迹 移栽 膜面穴口
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A Linear Quadratic Controller Design Incorporating a Parametric Sensitivity Constraint
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作者 Mohamed Yagoubi 《国际自动化与计算杂志:英文版》 EI CSCD 2019年第4期553-562,共10页
The purpose of this paper is to propose a synthesis method of parametric sensitivity constrained linear quadratic (SCLQ) controller for an uncertain linear time invariant (LTI) system. System sensitivity to parameter ... The purpose of this paper is to propose a synthesis method of parametric sensitivity constrained linear quadratic (SCLQ) controller for an uncertain linear time invariant (LTI) system. System sensitivity to parameter variation is handled through an additional quadratic trajectory parametric sensitivity term in the standard LQ criterion to be minimized. The main purpose here is to find a suboptimal linear quadratic control taking explicitly into account the parametric uncertainties. The paper main contribution is threefold: 1) A descriptor system approach is used to show that the underlying singular linear-quadratic optimal control problem leads to a non-standard Riccati equation. 2) A solution to the proposed control problem is then given based on a connection to the so-called Lur'e matrix equations. 3) A synthesis method of multiple parametric SCLQ controllers is proposed to cover the whole parametric uncertainty while degrading as less as possible the intrinsic robustness properties of each local linear quadratic controller. Some examples are presented in order to illustrate the effectiveness of the approach. 展开更多
关键词 LINEAR QUADRATIC control PARAMETRIC uncertainties trajectory sensitivity non-standard RICCATI equation Lur'e matrix equations LINEAR time invariant (LMI) particle SWARM optimization
时序网络控制
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作者 李阿明 王龙 《系统科学与数学》 CSCD 北大核心 2019年第2期184-202,共19页
近年来,网络科学的发展为探究复杂系统动力学提供了有效方法.复杂网络控制的研究,为我们通过外部输入控制系统状态的演化提供了新的思路.针对时序网络控制这一新的研究方向,文章首先介绍了其可控性方面相关研究现状.其次,文章梳理了在... 近年来,网络科学的发展为探究复杂系统动力学提供了有效方法.复杂网络控制的研究,为我们通过外部输入控制系统状态的演化提供了新的思路.针对时序网络控制这一新的研究方向,文章首先介绍了其可控性方面相关研究现状.其次,文章梳理了在实现系统最优控制时所需考虑的控制能量及控制轨迹等相关研究结果.最后总结了该领域仍需解决的重要问题并展望了未来研究方向. 展开更多
关键词 时序网络 复杂系统 控制 能量 轨迹
养老机构老年人抑郁情绪发展轨迹及预测因素分析 预览
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作者 王雅琦 吴方 +3 位作者 黄立群 高洁 李静 王克芳 《护理学杂志》 CSCD 北大核心 2019年第18期1-4,共4页
目的探讨养老机构老年人抑郁的异质性发展轨迹类型,并分析日常生活活动能力(ADL)对抑郁发展轨迹的预测作用。方法采用纵向研究设计,对符合条件的296名养老机构老年人采用Barthel指数评定表、患者健康问卷-2(PHQ-2)、社会网络量表对ADL... 目的探讨养老机构老年人抑郁的异质性发展轨迹类型,并分析日常生活活动能力(ADL)对抑郁发展轨迹的预测作用。方法采用纵向研究设计,对符合条件的296名养老机构老年人采用Barthel指数评定表、患者健康问卷-2(PHQ-2)、社会网络量表对ADL、抑郁和社会支持进行调查,并在6个月、12个月随访抑郁发生情况。结果养老机构老年人抑郁患病率基线调查为14.9%(44/296),第1次随访为20.9%(51/244),第2次随访为17.2%(36/209);以完成2次调查的250人为样本拟合出2条老年人抑郁的异质性轨迹,即高风险(14.8%)和低风险(85.2%);年龄、既往职业、ADL得分影响其抑郁发展轨迹(P<0.05,P<0.01)。结论养老机构老年人抑郁存在异质性轨迹,ADL低者抑郁呈恶化趋势。应关注机构老年人日常生活能力的锻炼,减少抑郁的发生。 展开更多
关键词 老年人 养老机构 抑郁 发展轨迹 日常生活活动能力 社会支持
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