Abnormal event detection by a weakly supervised temporal attention network

Abnormal event detection aims to automatically identify unusual events that do not comply with expectation.Recently,many methods have been proposed to obtain the temporal locations of abnormal events under various determined thresholds.However,the specific categories of abnormal events are mostly neglect,which are important to help in monitoring agents to make decisions.In this study,a Temporal Attention Network(TANet)is proposed to capture both the specific categories and temporal locations of abnormal events in a weakly supervised manner.The TANet learns the anomaly score and specific category for each video segment with only video-level abnormal event labels.An event recognition module is exploited to predict the event scores for each video segment while a temporal attention module is proposed to learn a temporal attention value.Finally,to learn anomaly scores and specific categories,three constraints are considered:event category constraint,event separation constraint and temporal smoothness constraint.Experiments on the University of Central Florida Crime dataset demonstrate the effectiveness of the proposed method.

Influence of stealth aircraft dynamic RCS peak on radar detection probability

For modern stealth aircraft,it is important to analyze the influence of Radar Cross Section(RCS)peak exposure on penetration for guiding stealth design and penetration trajectory planning,which needs to reflect the RCS statistical uncertainty and the RCS difference with the change of incident angle.Based on the RCS characteristics of typical stealth aircraft,this paper established a simplified RCS dynamic fluctuation statistical model with the parameters log mean and log standard deviation.According to the detection probability algorithm in radar signal processing field,this paper built the algorithm of radar detection probability based on the RCS dynamic fluctuation statistical model.The analysis of examples concluded that the key to successful penetration is to shorten the RCS peak exposure time,which can be reduced by decreasing the RCS peak width or increasing velocity.Based on the conclusion,this paper proposed the method of turning maneuvering to reduce RCS peak exposure time dramatically.

Estimation of evaporation losses based on stable isotopes of stream water in a mountain watershed

Water stable isotopes(δ^(2) H andδ^(18)O)can record surface water evaporation,which is an important hydrological process for understanding watershed structure and function evolution.However,the isotopic estimation of water evaporation losses in the mountain watersheds remains poorly explored,which hinders understanding spatial variations of hydrological processes and their relationships with the temperature and vegetation.Here we investigatedδ^(2) H,δ^(18)O,and d-excess values of stream water along an altitude gradient of 2130 to 3380 m in Guan’egou mountain watershed at the east edge of the Qinghai-Tibet Plateau in China.The meanδ^(2) H(-69.6‰±2.6‰),δ^(18)O(-10.7‰±0.3‰),and dexcess values(16.0‰±1.4‰)of stream water indicate the inland moisture as the major source of precipitation in study area.Water stable isotopes increase linearly with decreasing altitudes,based on which we estimated the fractions of water evaporation losses along with the altitude and their variations in different vegetations.This study provides an isotopic evaluation method of water evaporation status in mountain watersheds,the results are useful for further understanding the relationship between hydrological processes and ecosystem function under the changing climate surrounding the Qinghai-Tibet Plateau.

《生物多样性公约》及其议定书下“能力建设与发展”议题的磋商、挑战及政策建议

能力建设与发展一直是《生物多样性公约》(以下简称《公约》)及其议定书下的重要议题,《昆明-蒙特利尔全球生物多样性框架》更是将其作为履约的有效执行手段之一。本文旨在增进生物多样性利益相关方对能力建设与发展问题的全面、深入理解,以及探讨为处理这个问题可选择的优先政策事项。首先,从能力、能力建设和能力发展基本概念入手,概述了这些术语在《公约》及其议定书相关文件中的演变历史;然后,基于历届《公约》及其议定书的决定,全面梳理了能力建设与发展的磋商进程和COP15主要争论焦点,分析了该领域面临的资金、规划、项目、信息分享以及与其他国际公约之间的协同等关键性挑战及其原因;最后,针对能力建设与发展问题,在国际层面上,从扩宽资金渠道、制定或协调不同层次的战略与行动规划、确保项目和方案的长期性和可持续性、完善信息交流机制、提升相关公约间协同增效等方面提出了政策关注点;在国内层面上,从强化顶层设计、更新生物多样性战略与行动计划、查明生物安全和生物遗传资源领域的能力建设需求、加大宣传与参与以及充分利用“昆明生物多样性基金”和“一带一路”倡议等方面提出了政策建议。

垂直排列的六方氮化硼基忆阻器中的突触可塑性

下一代计算系统需要实现每秒1018次浮点运算以解决感知终端数据呈指数增长的问题,这是由人工智能和物联网的进步驱动的.即使超级计算机具备执行这些操作的能力,但当电子突触阵列达到与人类神经网络相当规模时,管理热耗散就成为一个重要挑战.解决电子设备中热点问题的潜在方案之一是使用垂直排列的六方氮化硼(h-BN),这种材料以其高导热性而闻名.在本研究中,我们使用高功率脉冲磁控溅射技术开发了纹理化的h-BN薄膜.定向的h-BN薄膜的热导率约为随机定向对应物的354%.通过制备基于纹理化h-BN薄膜的电子突触,我们展示了该器件中的各种生物突触可塑性.我们的研究结果表明,通过方向工程,可以有效使h-BN成为一种适用的自散热层,从而为未来可穿戴记忆设备、太阳能电池和神经形态器件铺平道路.