Adaptive spatial-temporal graph attention network for traffic speed prediction

Considering the nonlinear structure and spatial-temporal correlation of traffic network,and the influence of potential correlation between nodes of traffic network on the spatial features,this paper proposes a traffic speed prediction model based on the combination of graph attention network with self-adaptive adjacency matrix(SAdpGAT)and bidirectional gated recurrent unit(BiGRU).First-ly,the model introduces graph attention network(GAT)to extract the spatial features of real road network and potential road network respectively in spatial dimension.Secondly,the spatial features are input into BiGRU to extract the time series features.Finally,the prediction results of the real road network and the potential road network are connected to generate the final prediction results of the model.The experimental results show that the prediction accuracy of the proposed model is im-proved obviously on METR-LA and PEMS-BAY datasets,which proves the advantages of the pro-posed spatial-temporal model in traffic speed prediction.

Two new approaches for image registration based onspatial-temporal relationship

How to improve the probability of registration and precision of localization is a hard problem, which is desiderated to solve. The two basic approaches (normalized cross-correlation and phase correlation) for image registration are analysed, two improved approaches based on spatial-temporal relationship are presented. This method adds the correlation matrix according to the displacements in x- cirection and y- directions, and the registration pose is searched in the added matrix. The method overcomes the shortcoming that the probability of registration decreasing with area increasing owing to geometric distortion, improves the probability and the robustness of registration.

FBG反射谱数据滑动相关滤波算法设计与实现

针对光纤光栅解调系统中现有滤波算法计算速度与滤波效果难以兼顾的问题,提出了一种基于滑动相关滤波的光纤布拉格光栅(Fiber Bragg Grating,FBG)反射谱滤波方法并在现场可编程门阵列(Field Programmable Gate Array,FPGA)上实现算法加速设计。该算法根据FBG半峰全宽确定高斯函数二阶导数的标准差,用函数的负数作为滤波模板权重,通过滑动数据窗口进行反射谱数据与滤波模板的相关计算,从而实现滤波操作。使用该算法处理含高斯噪声、坏点和基线的仿真数据,验证了该方法对多种异常反射谱数据处理的有效性,并与其他下位机滤波算法进行对比分析,该算法能较好地保留原始数据特征,有较好的鲁棒性,信噪比最高提升28.23dB,中心波长平均偏差和偏差标准差最小,分别为1.712 pm和2.996pm。同时在FPGA片上平台实现了该算法,采用循环队列策略设计存储器,提高了存储器使用率,降低了资源消耗。实验表明,该算法可以有效校正多种异常FBG反射谱,在100MHz系统时钟下处理一个反射谱数据所需时间仅5.09μs,易于实现工程化应用,克服了下位机现有滤波算法对FBG反射谱中坏点、基线抑制作用较差和滤波后信号变形的问题,实现了FBG反射谱滑动相关滤波算法的加速设计。

一种改进的Link16信号检测方法

直接序列扩频、高速跳频与跳时相结合的技术,造成了对Link16信号的检测具有相当的难度。文中针对突发Link16信号脉冲宽度强规律性,借鉴双滑动窗算法在突发信号检测上的应用,提出了改进后基于相关处理的双滑动窗Link16信号检测方法,该方法可实现复杂电磁环境下对Link16信号的高灵敏度、高概率检测,同时正确估算出脉宽、码速率等参数信息。仿真实验数据验证了理论分析的正确性和所述方法的有效性,相较于其他Link16信号检测方法,改进后的基于相关处理的双滑动窗检测算法明显提高了在低信噪比下对Link16信号的检测能力。

基于积分滑模观测器的直线振荡电机谐振频率跟踪控制

现有直线振荡电机(LOM)无位置传感器谐振频率跟踪控制方法存在行程观测精度低、抗干扰能力差等问题,容易导致谐振频率跟踪精度低、频率振荡严重。为提高谐振频率跟踪控制性能,该文研究了一种基于积分滑模观测器(ISMO)的新型谐振频率跟踪控制方法。首先,基于LOM工作在系统谐振频率点时行程-电流相位差为90°的特点,提出一种双互相关函数比值方法,消除了行程变化对谐振频率跟踪控制的影响。其次,采用积分滑模面及新型趋近律设计ISMO,并利用二阶广义积分器获取行程估算信号,大大提高了行程估算精度。最后,对比实验结果表明,所提方法能够有效提高谐振频率跟踪精度、稳定时间及抗干扰能力。

基于梁端位移的支座滑动性能评估研究

滑动支座是大跨径悬索桥的重要构件,需定期对其工作状态进行评估,而人工定期检测周期长、检测结果主观性强,很难对支座的状态做出实时、定量的判断,桥梁管养机构迫切需要有效的方法对支座的滑动工作状态进行实时评估。梁端的位移变化规律表征了桥梁支座滑动性能的健康状态,该参数可以利用桥梁健康监测系统采集获取。本文基于桥梁健康监测系统中的梁端位移和环境温度监测数据,通过相关性分析方法,并与理论计算结果进行对比,实时评判支座的滑动性能,对滑动异常情况及时预警,所采用的支座滑动性能评估方法简单实用,在大跨度悬索桥支座的运营养护中具有较高的参考价值。

多源数据融合下无人飞行器最优滑模姿态控制

为解决姿态角速度过大造成的飞行器偏航问题,实现无人飞行器滑模姿态的有效控制,对多源数据融合下的无人飞行器最优滑模姿态控制方法展开研究。计算动态时间弯曲距离,联合数据时空关联度,确定加权参数取值范围,实现飞行器滑模姿态的多源数据融合。求解姿态坐标转换标准,根据力与力矩的求解结果,推导最优控制方程表达式,实现对无人飞行器最优滑模姿态的控制。对比实验结果表明,该方法作用下,姿态角速度波动幅度控制在-10~10 deg/s数值区间之内,较好地解决了飞行器偏航问题,符合有效控制无人飞行器滑模姿态的实际应用需求。

Spatial-Temporal Correlation 3D Vehicle Detection and Tracking System with Multiple Surveillance Cameras

Compared to 3D object detection using a single camera,multiple cameras can overcome some limitations on field-of-view,occlusion,and low detection confidence.This study employs multiple surveillance cameras and develops a cooperative 3D object detection and tracking framework by incorporating temporal and spatial information.The framework consists of a 3D vehicle detection model,cooperatively spatial-temporal relation scheme,and heuristic camera constellation method.Specifically,the proposed cross-camera association scheme combines the geometric relationship between multiple cameras and objects in corresponding detections.The spatial-temporal method is designed to associate vehicles between different points of view at a single timestamp and fulfill vehicle tracking in the time aspect.The proposed framework is evaluated based on a synthetic cooperative dataset and shows high reliability,where the cooperative perception can recall more than 66%of the trajectory instead of 11%for single-point sensing.This could contribute to full-range surveillance for intelligent transportation systems.

Interval finite element method and its application on anti-slide stability analysis

The problem of interval correlation results in interval extension is discussed by the relationship of interval-valued functions and real-valued functions. The methods of reducing interval extension are given. Based on the ideas of the paper, the formulas of sub-interval perturbed finite element method based on the elements are given. The sub-interval amount is discussed and the approximate computation formula is given. At the same time, the computational precision is discussed and some measures of improving computational efficiency are given. Finally, based on sub-interval perturbed finite element method and anti-slide stability analysis method, the formula for computing the bounds of stability factor is given. It provides a basis for estimating and evaluating reasonably anti-slide stability of structures.

千米级铁路悬索桥梁端支座位移长期变化规律分析

为掌握环境温度对大跨铁路悬索桥梁端支座位移及支座累计位移的影响,以某千米级公铁两用悬索桥为背景进行研究。基于该桥结构健康监测系统2021年的梁端支座位移长期监测数据,采用相关性基准值设定方法将梁端支座位移数据回归到合理区间,基于差分累加法获得支座累计位移,通过划分时段分析温度变化率对支座位移与环境温度间相关性的影响。结果表明:支座位移与环境温度间存在显著线性正相关关系;实测主梁伸缩系数和经验计算值基本吻合,全年南、北侧上游支座位移变化幅值和季度总累计位移基本一致,主梁两侧梁端变形具有高度的一致性;列车过桥时会导致主梁振动,支座大概率会发生小幅瞬间滑动现象,释放因主梁微小变形所产生的摩阻力;支座累计位移与桥梁结构体系有关,铁路悬索桥支座累计位移远小于公路缆索结构体系桥梁;温度变化率及其绝对值的大小对支座位移与环境温度间的相关关系存在一定的影响,温度变化率越稳定且绝对值越接近于0,两者相关关系越强。

弓网滑动电接触失效的影响因素分析与研究

为了研究影响因素对弓网滑动电接触失效的影响程度问题,采用自制的滑动电接触试验机对试验数据进行测量。首先,使用斯皮尔曼等级相关系数分析各因素和电流稳定系数之间的相关性;其次,采用RF、LightGBM和XGBoost算法对影响弓网滑动电接触失效的因素进行重要性排序;最后,利用网格搜索和交叉验证方法对XGBoost模型的参数进行调优,为了解影响因素对GC-XGBoost模型预测结果的影响,引入SHAP归因理论对模型进行解释分析。结果表明,弓网滑动电接触失效的影响因素重要度从高到低依次为波动压力幅值、接触电流、滑动速度和波动频率;XGBoost模型的各评价指标值相较于其他模型最优,经优化后的GC-XGBoost模型的拟合度提高了5.72%,误差精度达到最低;SHAP模型从整体与局部揭示了影响因素对滑动电接触失效的影响规律,帮助研究人员更好地解决电气化铁路中弓网系统接触失效的问题。

基于数字图像的排水沥青路面抗滑性能衰变研究

文中借助小型四轮加速加载试验装置对设计的不同级配排水沥青混合料,采用数字图像处理方法进行试件表面纹理三维重构,构建了表征排水沥青路表面纹理的特征参数灰度值及抗滑衰变Asymptotic指数模型,同时将灰度值与抗滑指标进行了相关性分析.结果表明:2D、3D两种模式下得到的三维重构图像均能很好反映排水沥青路表面三维纹理特征.加速加载作用0.5 h后试件表面形成了明显轮迹带,对应三维重构图像灰度值也出现最大幅度衰变,PAC-16降幅最小.灰度值与作用时间整体相关性均较好,指数模型可用于分析排水沥青路表面灰度值衰变规律.数字图像重构技术可用于获取排水沥青路面平均构造深度和车辆高速行驶下的动摩擦系数.

Forecasting Scenario Generation for Multiple Wind Farms Considering Time-series Characteristics and Spatial-temporal Correlation

Scenario forecasting methods have been widely studied in recent years to cope with the wind power uncertainty problem. The main difficulty of this problem is to accurately and comprehensively reflect the time-series characteristics and spatial-temporal correlation of wind power generation. In this paper, the marginal distribution model and the dependence structure are combined to describe these complex characteristics. On this basis, a scenario generation method for multiple wind farms is proposed. For the marginal distribution model, the autoregressive integrated moving average-generalized autoregressive conditional heteroskedasticity-t (ARIMA-GARCH-t) model is proposed to capture the time-series characteristics of wind power generation. For the dependence structure, a time-varying regular vine mixed Copula (TRVMC) model is established to capture the spatial-temporal correlation of multiple wind farms. Based on the data from 8 wind farms in Northwest China, sufficient scenarios are generated. The effectiveness of the scenarios is evaluated in 3 aspects. The results show that the generated scenarios have similar fluctuation characteristics, autocorrelation, and crosscorrelation with the actual wind power sequences.

利用时空相关性的海岛长期风速序列估计方法

丰富的历史风速数据是开展海岛微电网规划工作的前提。为此,针对待规划海岛无历史风速数据的问题,提出了一种利用周边海岛风速时空相关性估计目标海岛长期风速序列的方法。首先,结合滑动窗和云模型,自适应划分周边海岛风速序列的时序区间;其次,根据各时序区间内风速云模型数字特征的余弦相似度,匹配周边海岛各分段风速序列间的相似性转移关系(similarity transfer relationship,STR);最后,考虑STR与海岛空间位置关系,以权重表示各STR对目标海岛风速序列估计的影响,进而依据各STR及其权重估计目标海岛的长期风速序列。研究结果表明:相较于利用皮尔逊相关系数(Pearson correlation coefficient,PCC)计算各天风速序列间的相关性,进而估计海岛长期风速序列的方法,使用所提方法得到的估计结果与实际序列间的平均绝对误差、均方根误差和PCC分别约改善了7.31%、17.98%和0.46%,所提方法能够实现较高准确度的海岛长期风速序列估计。论文研究可为历史风速数据缺失情况下开展海岛风速预测工作提供参考。

基于脑功能连接网络和CNN识别情绪的研究

基于脑电信号的情绪识别是当前的研究热门,属于人机交互技术的一种。文章设计一种基于脑功能连接网络和CNN识别情绪的模型。研究中采用滑动窗口方法扩充样本量,筛选出与含有最多情绪特征信息的通道,再利用皮尔森相关系数构建脑功能连接网络。不同的网络密度控制下,将脑网络输入至CNN,并识别三类情绪。脑网络密度为30%时,识别精度达到82.3%±1.4%。实验结果表明,所提模型能有效识别积极、中性和消极三类情绪,为情绪识别提供了一种方法。

基于滑动相关系数法的贵州省降雨-径流变异诊断

选取贵州省1995—2020年降雨与径流实测资料,分析其水文气象要素的演变规律,运用累计距平法和Man-Kendall趋势法直观反映降雨、径流时间序列变化的趋势性、阶段性,采用Spearman秩次相关检验法研究降雨与径流的关联性,将滑动窗口与相关系数结合诊断变异,并采用双累计曲线法对比验证。结果表明:贵州省年径流量以4.382亿m 3/5a的速率大幅减小,未来呈持续下降势态;年降雨量以0.994亿m 3/5a的速率不增不减,未来呈平稳状态。贵州省降雨-径流联合序列发生了一次变异,突变年份为2010年。

湖北省博物馆新馆文展大楼钢筋混凝土斜墙结构设计

文展大楼的两侧立面由于造型立意要求,需要向外倾斜,结构设计时采用钢筋混凝土斜墙来实现此建筑需要。文章分析了斜墙与主体刚性连接时对相邻楼板及整体指标所带来的不利因素,并阐述了斜墙与主体滑动连接所带来的优越性。最后,文章提出了一种与主体弱相关的钢筋混凝土斜墙构造及设计方法,为类似工程提供参考。

AMOUNT OF INFORMATION FOR SPATIAL-TEMPORAL CORRELATION FILTER PATTERN RECOGNITION SYSTEM

In order to relate the design and analysis of an optical pattern recognition system with the structural parameters, only by introducing the prolate spheroidal wave function (PSWF) can the amount of information be computed. Combining the imaging wave function set {ψi(x)} and distorted wave function set {b_i(p)} and two integral equations they satisfy derives the expression of the amount of information. The design method of matched filter connected with its amount of information is studied, and their amounts of information belonging to different pattern recognition systems are illustrated. It can be seen that the difference of the amounts of information for various systems is obvious.

The influence of vessel attitude on spatial-temporal correlation of sea-bottom reverberation

The influence of vessel attitude on spatial-temporal correlation of sea-bottom re- verberation is discussed. The theoretical correlation function is deduced in consideration of the attitude of vessel. The relationship of the spatial-temporal correlation and the vessel attitude is obtained： The greater the sway of the vessel on some direction is, the faster the correlation coefficient decreases on the direction. The theoretical correlation function agrees well with the simulation result when sea-bottom has no large-scale relief but has isotropic roughness. The actual sea-bottom usually has large-scale relief and anisotropic roughness, so the vessel attitude and the large-scale relief cannot determine the shape of the correlation function, but trial data has proved their combined influence. In addition, the influence of the vessel attitude on the measurement of vertical velocity is discussed.

基于扩频序列的高铁无线信道测量仿真系统研究

为了评估不同扩频序列对高铁无线信道测量性能的影响,构建了基于扩频滑动相关的高铁无线信道测量仿真系统。在发射端分别生成Random、m、Kasami、Gold、ZC、Golay等6种扩频序列,通过COST207丘陵场景的标准信道模型传输调制信号,在接收端利用滑动相关算法估计出信道冲击响应。研究结果表明:Golay序列、ZC序列和m序列的自相关特性优于另外3种序列,进行高铁无线信道测量时误差相对较小;接收端利用估计的信道冲击响应可以有效提取信道的多径时延和多普勒扩展特性。仿真结果为构建可工程化应用的高铁无线信道测量系统提供了技术支撑。