Abnormal Crowd Behavior Detection Based on the Entropy of Optical Flow

To improve the detection accuracy and robustness of crowd anomaly detection,especially crowd emergency evacuation detection,the abnormal crowd behavior detection method is proposed.This method is based on the improved statistical global optical flow entropy which can better describe the degree of chaos of crowd.First,the optical flow field is extracted from the video sequences and a 2D optical flow histogram is gained.Then,the improved optical flow entropy,combining information theory with statistical physics is calculated from 2D optical flow histograms.Finally,the anomaly can be detected according to the abnormality judgment formula.The experimental results show that the detection accuracy achieved over 95%in three public video datasets,which indicates that the proposed algorithm outperforms other state-of-the-art algorithms.

Role of Retinal Nerve Fiber Layer Thickness and Optic Disk Measurement by OCT onEarly Diagnosis of Glaucoma

Purpose:.Glaucoma is an eye disease that can lead to irreversible optic nerve damage and cause blindness. Optical coherence tomography.(OCT) allows an early diagnosis of glaucoma by the measurements of the retinal nerve fiber and optic disc parameters.A retrospective study was designed to analyze the effects of the measurement of the retinal nerve fiber layer(RNFL) thickness and the optic disc tomography by spectraldomain OCT on the early diagnosis of suspected glaucoma and primary open angle glaucoma(POAG).Methods:.This was a clinical case-control study. The RNFL thickness around the optic disc and optic disk tomographic parameters of the control(n=51, 98 eyes), suspected glaucoma(n=81,.146 eyes), and POAG groups(n=55, 106 eyes) were measured by OCT. The parameters included superior, inferior, nasal and temporal mean RNFL thickness,.disc area(DA), cup area(CA), rim area(RA), disc volume(DV),cup volume(CV), rim volume(RV), cup / disc area ratio(CA / DA), rim / disc area ratio(RA / DA), cup / disc volume ratio(CV / DV) and rim / disc volume ratio(RV / DV).Results: Superior, nasal, and mean RNFL parameters, DA,CA,RA, DV, CV, CA / DA, RA / DA, CV / DV and RV / DV significantly differed among three groups by single-factorial ANOVA. Inferior and temporal RNFL thickness significantly differed between the control and POAG groups. No significant difference was observed in RV among three groups. In the POAG group,.the maximum area under the ROC curve(AROC) of mean RNFL thickness was 0.845. The maximum AROC of optic disk parameters was RA / DA(0.998), followed by CA / DA(0.997). The AROC of CA, RA, CV, and DV were all > 0.900.Conclusion:.OCT may serve as a useful diagnostic modality in distinguishing suspected glaucoma from POAG.

Detection of Influenza Viruses Attached to an Optical Disk

Detection of polystyrene beads with a diameter of 100 nm was conducted using an optical disk drive tester equipped with a laser of 405 nm wavelength and an objective lens with a numerical aperture of 0.65. The polystyrene beads were used to mimic the influenza virus. A grooved disk with a (ZnS)85(SiO2)15/SiO2 layered surface structure was used for the detection. The detection of influenza viruses (A/Udorn/307/1972) with Au nanoparticles was also demonstrated using the optical disk drive tester. In this case, a grooved disk with an indium tin oxide (ITO) film was used. The ITO film functioned both to tune the reflectance of the disk and as an electrically conductive layer for scanning electron microscopy. In both cases, the target substances were successfully recognized in a single scan with a high scanning speed of 4.9 m/s. The results indicate that this optical disk system can be used to detect 100 nm scale substances like influenza viruses, which are smaller than the diffraction limit of the system.

Magneto-optical Disk Material for Improving the Density of Information Storage

This paper introduces the fundamental principle and features ofmagneto-optical storage technol- ogy, and discuses the trend and aseries of key techniques for increasing the data storage density ofmagneto-opti- cal disk. The three ways including MO media, recordingmethod and readout method for increasing the disk ca- pacity havebeen discussed. Moreover, the importance with the exchange-coupledeffect between the magnetic layers and recording domain morphology isemphasized.

Study on Stereometric Parameters of Optic Nerve Head of Normal, Big-cupped Disk and Glaucomatous Eyes Using Heidelberg Retina Tomograph

Purpose: To investigate the difference of stereometric parameters of optic nerve head between the normal subjects and patients with big-cupped disk and primary open angle glaucoma (POAG).Methods: Twenty-two cases (44 eyes) of normal subjects, 17 cases (34 eyes) of patients with big-cupped disk and 19 cases (37 eyes) of patients with POAG underwent Heidelberg Retina Tomograph (HRT) examination to get topography images and stereometric parameters of optic nerve head.Results: The stereometric parameters of optic nerve head of the normal, patients with big-cupped disk and POAG were 1) disk area (mm2): 1. 995± 0. 501, 2. 407±0. 661 and 2. 248±0.498; 2) cup area (mm2): 0.573±0.264, 1. 095±0. 673 and 1. 340±0. 516; 3) cup/disk ratio: 0. 25±0. 095, 0. 428±0. 176 and 0. 589±0.195; 4) rim area (mm2): 1.461±0.328, 1.312±0.418 and 0. 905± 0.409; 5)cup volume (mm3): 0. 108±0. 073, 0. 347±0. 346 and 0. 550 ±0. 394; 6) rim volume (mm3): 0. 421±0. 111, 0. 378±0. 225 and 0. 224±0. 189; 7) mean cup

基于孤立森林算法的弹性光网络异常流量自动识别方法

弹性光网络流量传输受到时间波动导致异常,为了提高网络传输稳定性,提出基于孤立森林算法的弹性光网络异常流量自动识别算法。根据流量的异常分布特征和正常数据的差异性进行波谱密度检测,构建弹性光网络流量的谱特征提取模型,通过低通滤波器卷积向量重组,实现对异常流量的谱特征筛选,采用孤立森林算法实现对网络流量异常检测的自适应寻优控制,结合多维空间结构重组方法实现对弹性光网络异常流量检测和识别。结果表明,漏检率及误检率较低,分别为3.16%,1.03%。检测用时较少,仅用16秒。在进行检测时,外部入侵率未超过1%,抗扰性较强。

用数字示波器探究光磁共振实验中反常共振信号的机理

本文根据拟合得到的gF因子大小,确定了光磁共振实验中的反常共振信号;用数字示波器测量了反常共振射频信号的频谱,计算了反常共振射频信号各高次谐波的大小;通过线性拟合,得到了正常共振信号幅度与射频信号幅度的关系。利用此关系,计算了各高次谐波产生的反常共振信号大小,计算结果与测量值基本一致。频率计连接射频信号源后,射频信号波形和频谱发生明显变化,反常共振信号随着射频信号频谱的变化发生相应改变,进一步证明了反常共振信号由射频信号的高次谐波共振所引起。这些结果表明,用数字示波器探究光磁共振实验中反常共振信号的机理不仅可行,还能定量估算和预测射频信号波形对反常共振信号大小的影响。

基于OPTICS的变电设备状态监测异常数据过滤算法

针对变电一次设备状态监测中普遍存在的异常数据问题,提出了一种基于点排序识别聚类结构(Ordering Points to Identify the Clustering Structure,OPTICS)的状态监测异常数据过滤算法。通过对一次设备状态监测的历史数据进行异常数据特征分析,建立了基于密度聚类的异常数据过滤机制。并以某110 k V变电站一次设备变压器油色谱以及GIS SF6密度微水实验为例,对该算法的异常数据检测效果进行了验证。该算法与传统异常数据过滤算法的对比试验结果表明,该算法能够准确地识别异常数据的特征,有效过滤状态监测中的异常数据,显著降低噪声干扰,从而提高数据的可靠性。

基于ReSE-AG-Net的青光眼视盘视杯分割方法

分割视盘视杯是诊断青光眼的主要依据,因此提出了一种基于改进U-Net网络的青光眼视盘视杯分割方法,称为ReSE-AG-Net。并将ReSE-AG-Net、U-Net、M-Net、CE-Net和CDED-Net分别在Drishti-GS1数据集和RIM-ONE-R3数据集上进行测试,对得到分割后的视盘视杯的Dice系数和IoU进行对比。实验结果表明,在Drishti-GS1数据集上,分割视盘的Dice系数和IoU分别是0.989 1和0.959 0,分割视杯的Dice系数和IoU分别是0.931 0和0.871 0,在RIMONE-R3数据集上,分割视盘的Dice系数和IoU分别是0.978 9和0.958 7,分割视杯的Dice系数和IoU分别是0.863 7和0.760 1,对比U-Net模型和现有的分割模型均有一定的提升,证明了该方法的可行性。

Reduced macular thickness and vascular density in abnormal glucose metabolism patients:A meta-analysis of optical coherence tomography(OCT)and OCT angiography studies

Background:Alterations in macular thickness and vascular density before clinically visible diabetic retinopathy(DR)remain inconclusive.This study aimed to determine whether retinal manifestations in abnormal glucose metabolism(AGM)patients differ from those in the healthy individuals.Methods:PubMed,Embase,and Web of Science were searched between 2000 and 2021.The eligibility criteria were AGM patients without DR.Primary and secondary outcomes measured by optical coherence tomography(OCT)and OCT angiography(OCTA)were analyzed and expressed as standardized mean differences(SMDs)with 95%confidence intervals(CIs).A random-effects model was used in the data synthesis.The potential publication bias for the variables was evaluated using Egger’s test.Results:A total of 86 observational studies involving 13,773 participants and 15,416 eyes were included.OCT revealed that compared to healthy controls,the total macular thickness of AGM patients was thinner,including the thickness of fovea(-0.24,95%CI[-0.39,-0.08];P=0.002,I^(2)=87.7%),all regions of parafovea(-0.32,95%CI[-0.54,-0.11];P=0.003;I^(2)=71.7%)and the four quadrants of perifovea;the thickness of peripapillary retinal nerve fiber layer(pRNFL),macular retinal nerve fiber layer(mRNFL),and ganglion cell layer(GCL)also decreased.OCTA indicated that the superficial and deep vascular density decreased,the foveal avascular zone(FAZ)area enlarged,and the acircularity index(AI)reduced in AGM individuals.Conclusions:Retinal thinning and microvascular lesions have occurred before the advent of clinically detectable DR;OCT and OCTA may have the potential to detect these preclinical changes.Registration:PROSPERO;http://www.crd.york.ac.uk/prospero/;No.CRD42021269885.

近视病人青光眼诊断的研究进展

近视是青光眼发病的高危因素,且研究表明近视程度越高,患青光眼的可能性就越大。近视病人青光眼诊断是一个特殊问题,这可能因为早期青光眼与近视的表现相似,所以许多近视病人因青光眼而使视力受到损害,但未引起临床医生考虑青光眼的可能性。近年来随着眼科影像技术的发展,尤其是光学相干断层扫描与共焦激光眼底扫描红外成像及无赤光眼底照相技术的结合、光学相干断层扫描离散傅里叶变换分析与视野的结合,光学相干断层扫描血流成像的快速革新,临床医生可以从多方面了解近视与青光眼的发生发展,为早期诊断近视眼青光眼,及时干预治疗,从而为提高近视病人的视觉生活质量提供坚实的基础。

基于聚类分析提取特征的光通信系统异常数据检测

光通信系统易受多种因素影响,传统方法的光通信系统异常数据检测错误率高,检测效率,为了获得理想的光通信系统异常数据检测结果,设计了基于聚类分析提取特征的光通信系统异常数据检测方法。首先设计光通信系统数据传输模型,采用聚类算法提取光通信系统异常数据特征,然后采用深度学习算法建立光通信系统异常数据检测模型,并采用遗传算法优化深度学习算法,最后进行了光通信系统异常数据检测仿真实验,结果表明:本方法的光通信系统异常数据检测正确率超过98%,光通信系统异常数据检测时间为21.6 ms,具有一定的实际应用价值。

基于CD/DVD光盘的光波衍射研究

白炽灯光入射在CD/DVD光盘会呈现随着角度轻微变化发生相应变化的彩色线.基于CD/DVD光盘的制造工艺,利用MATLAB软件对衍射规律进行理论分析,使用分光计实验观察白炽灯照射下CD/DVD光盘呈现出彩色线的衍射现象,验证不同入射角、衍射角、水平偏转角与波长的关系,获得不同条件下的衍射图案.为光学和材料科学等多个学科领域以及数字储存技术的发展提供新的思路和方向.

突发公共安全事件监控视频异常行为监测仿真

公共安全事件监控视频中的异常目标通常为中小型个体,其监测过程也易受到周围公共场所环境的干扰。提出突发公共安全事件监控视频异常行为监测方法。建立符合人体异常行为特点的增强型Cucker-Smale群体运动模型,描述人体异常行为的目标运动函数。以上述函数为基础,采集监控视频中与突发公共安全事件相关的异常行为数据。利用光流块为单位提取异常行为数据特征,并将异常行为数据特征与K-means聚类算法结合,全面分类异常行为数据特征,实现突发公共安全事件监控视频异常行为的监测。仿真结果表明,研究方法能够准确的识别出监控视频中的异常行为,且AUC值最高可达0.983,说明所提方法具有更好的应用性能。

关于光盘上出现彩色线的实验研究

为了探究光盘(CD或DVD)的光栅衍射规律,以2023年全国大学生物理学术竞赛“色彩线”这一题为例,从理论与实验两方面研究光盘在有无刻录、不同的刻录方式、不同的光路入射角度等条件下衍射条纹颜色的变化情况,探究光盘上光栅衍射规律。结果表明:光盘上衍射条纹颜色与光盘结构、入射光角度和光盘倾角有关。该研究对新型光盘材料和技术的开发有着一定的理论和实践意义。

基于改进光流法的视频监控中人群异常行为检测算法

危害社会公共安全的事件频发,研究视频监控中人群异常行为对于恢复治安秩序和保障公众安全有着重要意义。由于视频监控涉及多种多样的场景,复杂环境影响了人群异常行为的准确检测。因此,为提升视频监控中人群异常行为的检测效果,提出基于改进光流法的视频监控中人群异常行为检测算法。利用改进单高斯模型在视频监控中人群视频帧内提取角点作为特征点;基于改进光流法计算特征点的运动速度与方向,提取有效特征点,得到人群运动目标图像;通过计算人群运动目标图像内光流点的方向熵、幅值熵与平均速度的乘积,确定运动混乱度;对比分析运动混乱度与设置阈值,完成人群异常行为检测。实验结果表明,该算法可有效提取人群视频帧内的角点和运动目标图像,准确检测人群异常行为,具有较好的视频监控中人群异常行为检测效果。

基于人体骨架的电梯内异常行为识别预警

为准确识别乘客在封闭狭小的电梯轿厢内发生的打架等异常行为,避免安全事故的发生,提出一种基于人体骨架联合时空特征的乘客异常行为识别方法。首先,使用YOLOv7对视频中乘客位置进行检测,通过YOLOv7-Pose姿态估计算法提取骨骼关键点坐标,滤除复杂背景干扰;其次,针对异常行为动作幅度大、速度较快、方向混乱的特征,使用SURF联合金字塔分层改进的LK光流法对乘客人体骨架特征信息进行时间、空间的联合特征提取;最后,通过特征点的光流变化来判断轿厢内是否发生异常行为并及时发出警报。本文使用的数据集分别来源于电梯场景下的自建数据集和非电梯场景下行为公开数据集,实验结果表明,本文所提方法对异常行为识别准确率达到了95.53%,在速度与准确度上相较于其他方法有一定的提高,能够满足实时要求,可应用于电梯轿厢的视频监控系统,保障乘客的乘梯安全。

基于数据挖掘的光纤通信网络异常数据检测

为提高光纤通信网络异常数据检测能力,研究基于数据挖掘的光纤通信网络异常数据检测方法。采用改进关联聚类算法划分光纤通信网络数据,通过聚类操作获取异常数据;采用基于正则化相关熵异常检测的特征提取方法,结合半二次优化技术获取光纤通信网络异常数据特征向量;以光纤通信网络异常数据特征为依据构建熵目标函数,通过大量迭代获取熵目标函数最优值,实现光纤通信网络异常数据最优检测。实验结果表明:该方法的异常数据检测结果与光时域反射仪一致,且不受数据占用率以及网络、路由所处状态影响,检测正确率及检测效率均较高。

EFFECTS OF SPUTTERING CONDITIONS OF Tb Fe Co MAGNETO OPTICAL FILM ON KERRR OTATION

In the practical magneto opticaldisk productionline,alloysputteringtargetisalwaysusedtosputter recording film , whileinlaid targetisrarely used .In ourlaboratory,a seriesof al loy targets forsputtering magneto- optical recording film were prepared and theeffect ofcomposition andsputtering parameterson magneto opticalpropertiesarestudied . Thesputter ing rateof Al,Siand Tb Fe Co( Mo) undertheconditionsof differentsputtering powerandN2 Argasflux weredetermined and baseontheresults,a variablecomposition andthickness of SiNcan beobtained by meansof regulating sputtering power and gasflux, kindsof Mosputtering filmsareobtained under differentsputtering power and gasflux, and Kerrloop lineofthese magneto opticalfilmsare measuredto acquiretheir propertiessuch as Kerrrota tion,then ,theeffectofsputteringtechnology on Kerrrotationisdiscussed .

Leber Hereditary Optic Neuropathy in a Boy with Fibrous Boney Dysplasia

Purpose:To report a case of Leber hereditary optic neuropathy combined with fibrous boney dysplasia. Methods: Case report. Results:A 16-year-old boy presented with painless vision loss in both eyes. He had a history of a right humerus fracture and right femoral fracture surgery after an uncomplicated fall.On examination in our clinic, his visual acuity was counting fingers at 20 cm OD and counting fingers at 40 cm OS.Both pupils reacted sluggishly to light.The findings on slit-lamp examination and funduscopy after pupillary dilation were all unremarkable. Computed tomography scans demonstrated fibrous dysplasia involving the right frontal, temporal, parietal, and occipital bones but no stenosis of either optic canal. His serum alkaline phosphatase was 522 U/L (reference range: 40-150 U/L). His vision showed no improvement after intravenous methylprednisolone pulse therapy.Finally,a 11778 mitochondrial DNA mutation was detected. He still had no visual recovery after treatment with oral coenzyme Q10,vitamin B1, and citicoline. Conclusion:Fibrous dysplasia of bone may be associated with Leber hereditary optic neuropathy,possibly due to the fact that it increases local oxygen consumption. (Eye Science 2013; 28:48-50)