Disturbance observer-based fuzzy fault-tolerant control for high-speed trains with multiple disturbances

The fault-tolerant control problem is investigated for high-speed trains with actuator faults and multiple disturbances.Based on the novel train model resulting from the Takagi–Sugeno fuzzy theory, a sliding-mode fault-tolerant control strategy is proposed. The norm bounded disturbances which are composed of interactive forces among adjacent carriages and basis running resistances are rearranged by the fuzzy linearity technique. The modeled disturbances described as an exogenous system are compensated for by a disturbance observer. Moreover, a sliding mode surface is constructed, which can transform the stabilization problem of position and velocity into the stabilization problem of position errors and velocity errors, i.e., the tracking problem of position and velocity. Based on the parallel distributed compensation method and the disturbance observer, the fault-tolerant controller is solved. The Lyapunov theory is used to prove the stability of the closed-loop system. The feasibility and effectiveness of the proposed fault-tolerant control strategy are illustrated by simulation results.

Refined disturbance observer based prescribed performance fixed-time control of high-speed EMS trains with track irregularities

High-speed Electromagnetic Suspension(EMS)train is continuously impacted by the irregularity of the track,which worsens the levitation performance of the train.In this paper,a composite control scheme for the EMS is proposed to suppress track irregularities by integrating a Refined Disturbance Observer(RDO)and a Prescribed Performance Fixed-Time Controller(PPFTC).The RDO is designed to estimate precisely the track irregularities and lumped disturbances with uncertainties and exogenous disturbances in the suspension system,and reduce input chattering by applying to the disturbance compensation channel.PPFTC is designed to converge the suspension air gap error to equilibrium point with prescribed performance by completing error conversion,and solve the fast dynamic issue of EMS.And the boundary of overshoot and steady-state is limited in the ranged prescribed.A theoretical analysis is conducted on the stability of the proposed control method.Finally,the effectiveness and reasonability of the proposed composite anti-disturbance control scheme is verified by simulation results.

Pulse rate estimation based on facial videos:an evaluation and optimization of the classical methods using both self-constructed and public datasets

Pulse rate is one of the important characteristics of traditional Chinese medicine pulse diagnosis,and it is of great significance for determining the nature of cold and heat in diseases.The prediction of pulse rate based on facial video is an exciting research field for getting palpation information by observation diagnosis.However,most studies focus on optimizing the algorithm based on a small sample of participants without systematically investigating multiple influencing factors.A total of 209 participants and 2,435 facial videos,based on our self-constructed Multi-Scene Sign Dataset and the public datasets,were used to perform a multi-level and multi-factor comprehensive comparison.The effects of different datasets,blood volume pulse signal extraction algorithms,region of interests,time windows,color spaces,pulse rate calculation methods,and video recording scenes were analyzed.Furthermore,we proposed a blood volume pulse signal quality optimization strategy based on the inverse Fourier transform and an improvement strategy for pulse rate estimation based on signal-to-noise ratio threshold sliding.We found that the effects of video estimation of pulse rate in the Multi-Scene Sign Dataset and Pulse Rate Detection Dataset were better than in other datasets.Compared with Fast independent component analysis and Single Channel algorithms,chrominance-based method and plane-orthogonal-to-skin algorithms have a more vital anti-interference ability and higher robustness.The performances of the five-organs fusion area and the full-face area were better than that of single sub-regions,and the fewer motion artifacts and better lighting can improve the precision of pulse rate estimation.

STOCHASTIC NOISE TOLERANCE:ENHANCED FULL STATE OBSERVER VS. KALMAN FILTER FROM VIDEO TRACKING PERSPECTIVE

A control-based full state observer scheme is explored for video target tracking application, and is enhanced with a lowpass filter for improving the tracking precision, thus forming an Enhanced Full State Observer (EFSO). The whole design is based on the given lab-generated video sequence with motion of an articulate target. To evaluate the EFSO’s stochastic noise tolerance, a Kalman Filter (KF) is intentionally employed in tracking the same target with the given Gaussian white noises. The comparison results indicate that, for system noises of certain statistics, the proposed EFSO has its own noise resistance capacity that is superior to that of KF and is more advantageous for implementation.

基于深度学习的视频观测潮位技术研究——以厦门高崎码头为例

近岸潮位观测是海洋工程应用、海岸防灾减灾、海岸带管理以及海洋有关科研工作中最基础的工作之一。文章基于视频图像深度学习的方法,使用YOLOv5目标检测算法从安装在近岸的固定摄像机拍摄的视频帧中提取潮汐水位特征进行潮位分析。研究采用厦门高崎码头的分辨率为1920×1080的高清摄像头2023年2月的影像数据作为训练集和验证集,2023年3月的影像数据作为测试集,利用岸边验潮井逐时潮位数据进行标注,采用YOLOv5目标检测算法来训练。计算结果显示,通过视频观测潮位在训练集和测试集上的误差分别为3.9cm和5.3cm。视频中1个像素点代表3.8cm,因此潮位观测的平均误差为像素级。研究表明在近岸通过高清摄像头基于图像深度学习进行潮位观测的方法是可行的,观测精度取决于图像目标物的分辨率。

婴儿行为观察分析的视频编码方法综述

行为是婴儿表达自身需求、情感等最直接的方式,也是心理发展的外在表现。通过对婴儿进行行为观察,可以更详细、真实地获得婴儿行为和发展的资料;基于视频编码的行为观察分析方法,为全面、客观地进行研究分析创造了条件。本文从视频采集、编码方法、编码工具3个方面介绍了婴儿行为分析中采用的视频编码方法及研究应用,以期为开展婴儿行为观察研究提供支持。

High Speed Observation of Periodic Cavity Behavior in a Convergent-Divergent Nozzle for Cavitating Water Jet

Cloud cavitation shows an unsteady periodic tendency under a certain flow condition. In a cavitating water jet flow with cavitation clouds, the cavities or the clouds produce high impact at their collapse. In order to make clear a mechanism of the periodic cavity behavior, we experimentally examine the behavior in a transparent cylindrical convergent-divergent nozzle using a high-speed video camera. An effect of upstream pressure fluctuation due to a plunger pump is investigated from a viewpoint of unsteady behavior in a cavitating water jet. As a result, it is found that the cavitating flow has two kinds of oscillation patterns in the cavity length (cavitation cloud region). One is due to the upstream pressure fluctuation caused by the plunger pump. The other is much shorter periodic motion related to the characteristic oscillation of cavitation clouds accompanied with the shrinking (reentrant), growing and shedding motion of the clouds.

Determination of frequencies of oscillations of cloud cavitation on a 2-D hydrofoil from high-speed camera observations

A method is presented to determine significant frequencies of oscillations of cavitation structures from high-speed camera recordings of a flow around a 2-D hydrofoil. The top view of the suction side of an NACA 2412 hydrofoil is studied in a transparent test section of a cavitation tunnel for selected cloud cavitation regimes with strong oscillations induced by the leading-edge cavity shedding. The ability of the method to accurately determine the dominant oscillation frequencies is confirmed by pressure measure- ments. The method can resolve subtle flow characteristics that are not visible to the naked eye. The method can be used for non- invasive experimental studies of oscillations in cavitating flows with adequate visual access when pressure measurements are not available or when such measurements would disturb the flow.

A method for using video presentation to increase the vividness and activity of cortical regions during motor imagery tasks

In recent years,mental practice(MP)using laterally inverted video of a subject’s non-paralyzed upper limb to improve the vividness of presented motor imagery(MI)has been shown to be effective for improving the function of a paralyzed upper limb.However,no studies have yet assessed the activity of cortical regions engaged during MI task performance using inverse video presentations and neurophysiological indicators.This study sought to investigate changes in MI vividness and hemodynamic changes in the cerebral cortex during MI performance under the following three conditions in near-infrared spectroscopy:MI-only without inverse video presentation(MI-only),MI with action observation(AO)of an inverse video presentation of another person’s hand(AO+MI(other hand)),and MI with AO of an inverse video presentation of a participant’s own hand(AO+MI(own hand)).Participants included 66 healthy right-handed adults(41 men and 25 women;mean age:26.3±4.3 years).There were 23 patients in the MI-only group(mean age:26.4±4.1 years),20 in the AO+MI(other hand)group(mean age:25.9±5.0 years),and 23 in the AO+MI(own hand)group(mean age:26.9±4.1 years).The MI task involved transferring 1 cm×1 cm blocks from one plate to another,once per second,using chopsticks held in the non-dominant hand.Based on a visual analog scale(VAS),MI vividness was significantly higher in the AO+MI(own hand)group than in the MI-only group and the AO+MI(other hand)group.A main effect of condition was revealed in terms of MI vividness,as well as regions of interest(ROIs)in certain brain areas associated with motor processing.The data suggest that inverse video presentation of a person’s own hand enhances the MI vividness and increases the activity of motor-related cortical areas during MI.This study was approved by the Institutional Ethics Committee of Nagasaki University Graduate School of Biomedical and Health Sciences(approval No.18121303)on January 18,2019.

Evolution Handoff Strategy for Real-Time Video Transmission over Practical Cognitive Radio Networks

The transmission delay of realtime video packet mainly depends on the sensing time delay(short-term factor) and the entire frame transmission delay(long-term factor).Therefore,the optimization problem in the spectrum handoff process should be formulated as the combination of microscopic optimization and macroscopic optimization.In this paper,we focus on the issue of combining these two optimization models,and propose a novel Evolution Spectrum Handoff(ESH)strategy to minimize the expected transmission delay of real-time video packet.In the microoptimized model,considering the tradeoff between Primary User's(PU's) allowable collision percentage of each channel and transmission delay of video packet,we propose a mixed integer non-linear programming scheme.The scheme is able to achieve the minimum sensing time which is termed as an optimal stopping time.In the macro-optimized model,using the optimal stopping time as reward function within the partially observable Markov decision process framework,the EHS strategy is designed to search an optimal target channel set and minimize the expected delay of packet in the long-term real-time video transmission.Meanwhile,the minimum expected transmission delay is obtained under practical cognitive radio networks' conditions,i.e.,secondary user's mobility,PU's random access,imperfect sensing information,etc..Theoretical analysis and simulation results show that the ESH strategy can effectively reduce the transmission delay of video packet in spectrum handoff process.

Reviving Direct Observation Methods for Physical Activity Behavior

Purpose:Current Direct Observation(DO)methods are burdensome to the observer and relevant limitations can be identified on the outcome information.This study aims to characterize DO from the observers’point of view and to analyze the feasibility and usefulness of visual information in the form of video.Method:data collection was done with ten adult males,observed while performing different physical activities in an indoor court.Sessions were video recorded by two cameras.Three observers performed systematic observation,using SOPLAY,with different sampling rates.Inter observer’s agreement and with reference data was analyzed by Cohen’s Kappa statistic.Results:SOPLAY highest agreement between observers was 0.611 on vigorous category and walking category had the lowest 0.188.It doubles the time needed to annotate the video with pauses,but half of player’s behavior is preserved.Conclusion(s):using video to support DO permits to collect more accurate data and a more detailed behavior categorization is warranted.Developments in computer vision are expected to reduce the human efforts in DO methods.

Abnormal activity detection for surveillance video synopsis

Video synopsis is an effective and innovative way to produce short video abstraction for huge video archives,while keeping the dynamic characteristic of activities in the original video.Abnormal activity,as the critical event,is always the main concern in video surveillance context.However,in traditional video synopsis,all the normal and abnormal activities are condensed together equally,which can make the synopsis video confused and worthless.In addition,the traditional video synopsis methods always neglect redundancy in the content domain.To solve the above-mentioned issues,a novel video synopsis method is proposed based on abnormal activity detection and key observation selection.In the proposed algorithm,activities are classified into normal and abnormal ones based on the sparse reconstruction cost from an atomically learned activity dictionary.And key observation selection using the minimum description length principle is conducted for eliminating content redundancy in normal activity.Experiments conducted in publicly available datasets demonstrate that the proposed approach can effectively generate satisfying synopsis videos.

基于观测与视频数据的机场能见度预测研究

能见度预测将直接影响交通运输的安全和效率。能见度检测一般需用昂贵的激光能见度仪,但该仪器对团雾检测精度不高,探测的范围很小,维护成本高,从而在无设备区域易出现安全隐患。因此,如何高效的检测能见度是高速管理部门和航空公司十分关注的问题。文章以大数据技术为基础,以预测各种场景中的能见度为最终目的,分别利用测量数据、视频、图像、时间序列四种数据进行分析和预测,最终得到普适性强、精确度高的最佳方案。实验结果表明模型均达到了较好的表现,为未来机场能见度的人工智能预测系统提供了有益的借鉴。

矿井皮带集控人员的6点工作经验

文章总结了矿井皮带集控人员的6点工作经验:⑴视频观察法;⑵现场声音辅助判断;(3)日常皮带保护测试;(4)高效通讯,将同一系统多台皮带的沿线语音信号进行联通,并接1个语音箱到集控室;(5)集控人员要指挥现场巡视人员快速处理异常情况;(6)具备应急预案,高效、快速、准确地处理异常情况。最终,这些经验保障了皮带集控系统的安全与可靠运行。

农作物虫害的机器检测与监测技术研究进展

在早期发现并准确定位害虫,对其未来的发展趋势作出评价,可提高施药处方决策和综合防治的针对性和准确性。在作物虫害信息的获取中,传统的检测和监测方法不但耗时、费力,而且导致的预报滞后会进一步增加损失程度,很难较好地满足现代农业的精准生产要求。本文介绍了国内外学者在田间作物上开展害虫及其危害状况的机器检测和监测技术研究取得的进展,包括声特征检测法、雷达观测法、图像识别法以及光谱监测法等,讨论了现有技术的局限性,指出了未来作物虫害机器检测和监测技术的可能发展方向是采用多种技术相结合的组合式检测和监测方法,从多个角度获取特定虫害的相关信息,相互进行实证检验,以提高作物虫害机器检测和监测的精度及效率。

技术支持下的课堂教学行为观察方法探究

在比较分析四类课堂教学行为编码系统的基础上,文章从行为方式和行为主体两个维度出发,构建了新的课堂教学行为分析编码系统,将课堂教学行为划分为四大类16种;提出了"时间抽样,动态补偿"的教学行为样本采集原则,并针对课堂教学行为的特殊情况制定了3个约束规则,用于指导课堂教学行为的观察和记录。在理论研究的基础上,文章还研制了课堂教学行为采集与分析软件,并通过应用分析证明了所述方法的有效性。

活性剂钨极惰性气体保护电弧焊接熔池行为的观察

利用高速数字摄相机对涂敷活性剂与不涂活性剂条件下的熔池表面流体流动形态及等离子体行为进行观察。利用X射线实时焊缝数字观察系统,用钨粒子示踪法测试熔池流体流动的规律。试验结果表明,活性剂使电弧收缩、改变熔池流体的流动方向并使流体流动速度加快,有活性剂时的涡流流动速度比无活性剂的涡流流动速度增加4倍,强烈的熔池流体向内对流是活性剂钨极惰性气体保护电弧焊熔深增加的主要原因,验证了数值模拟得到的结果。

数学课堂教师教学行为的继承和发展——3节录像课的比较研究

在课堂教学中，教师的教学行为是影响学生学习的重要因素之一．分别从20世纪80年代、20世纪90年代和2006年选出3节具有时代特征的录像课，发现：从上世纪80年代以来，数学教育历经3个时代的变革，课堂教学产生了一些合理的变化，但是教师的课堂教学行为还是存在共同的、稳定的特点，这表明数学教学是在继承传统的基础上逐步向前发展的．

基于视频的改进型S-T分析法的应用研究

随着信息技术的发展,基于视频的课堂教学观察方法在教育研究中得到越来越广泛的应用。该方法具有对课堂干扰少、支持回溯、可有效提高课堂观察的效率和质量等特点。本文从数据采集、统计及分析三方面对S-T分析法进行了改进,提出了一种基于视频的改进型S-T分析方法。该方法提出"时间抽样,动态补偿"的教学行为数据采集原则,以行为持续时间作为行为占有率的统计标准,并对教学模式的结构分布进行了调整。在理论研究的基础上,选取了11个教学视频样本,分别用原始S-T分析法和改进型S-T分析法两种方法进行数据采集与分析,对两种方法进行了比较研究,验证了改进型S-T分析法的有效性。

录像示范和现场示范对运动技能观察学习的影响

目的:探讨录像示范和现场示范对运动技能观察学习的影响。办法:48名受试随机分为练习组、现场示范观察组、录像示范观察组和控制组,采用计算机追踪任务,以RMSE为评价指标,对4组受试分别进行10 min后保持测试、24 h后保持测试和迁移测试。结果显示:在所有测试中,录像示范观察组和现场示范组受试操作绩效没有显著性差异;在10 min后保持测试和24 h后保持测试中,练习组受试操作绩效显著好于其他组受试,现场示范观察组和录像示范观察组受试操作绩效显著好于控制组;在迁移测试中,练习组、录像示范观察组、现场示范观察组受试操作绩效没有显著性差异,但都显著好于控制组。