The study of sulfur hexafluoride(SF6) discharge is vital for its application in gas-insulated equipment. Direct current partial discharge(PD) may cause SF6 decomposition, and the decomposed products of SF6, such as F ...The study of sulfur hexafluoride(SF6) discharge is vital for its application in gas-insulated equipment. Direct current partial discharge(PD) may cause SF6 decomposition, and the decomposed products of SF6, such as F atoms, play a dominant role in the breakdown of insulation systems. In this study, the PD caused by metal protrusion defects is simulated by a needle-plate electrode using pulsed high voltage in SF6/Ar mixtures. The spatial and temporal characteristics of SF6/Ar plasma are analyzed by measuring the emission spectra of F and Ar atoms, which are important for understanding the characteristics of PD. The spatial resolved results show that both F and Ar atom spectral intensities increase first from the plate anode to the needle and then decrease under the conditions of a background pressure of400 Pa, peak voltage of-1000 V, frequency of 2 kHz, pulse width of 60 μs, and electrode gap of 5-9 mm. However, the distribution characteristics of F and Ar are significantly different. The temporal distribution results show that the spectral intensity of Ar decreasesfirst and then increases slowly, while the spectral intensity of F increases slowly for the duration of the pulsed discharge at the electrode gap of 5 mm and the pulse width of40-80 μs.展开更多
Optical networks are expected to cater for the future Internet due to the high speed and capacity that they offer. Caching in the core network has proven to reduce power usage for various video services in current opt...Optical networks are expected to cater for the future Internet due to the high speed and capacity that they offer. Caching in the core network has proven to reduce power usage for various video services in current optical networks. This paper investigates whether video caching will still remain power efficient in future optical networks. The study compares the power consumption of caching in a current IP over WDM core network to a future network. The study considers a number of features to exemplify future networks. Future optical networks are considered where： （1） network devices consume less power, （2） network devices have sleep-mode capabilities, （3） IP over WDM implements lightpath bypass, and （4） the demand for video content significantly increases and high definition video dominates. Results show that video caching in future optical networks saves up to 42% of power consumption even when the power consumption of transport reduces. These results suggest that video caching is expected to remain a green option in video services in the future Internet.展开更多
Comparied to traditional optical processing methods,numerical controlled surfacing techniques have irreplaceable effects especially in spherical and aspherical optics. In this paper,fabricating methods,mechanisms and ...Comparied to traditional optical processing methods,numerical controlled surfacing techniques have irreplaceable effects especially in spherical and aspherical optics. In this paper,fabricating methods,mechanisms and processes are analyzed. Also,some processing difficulties and problems are discussed. The possible improvements and feasible methods are given.展开更多
目的:设计一种基于光学字符识别(optical character recognition,OCR)模型的医疗救治装备数据采集平台,以实现应急灾害救援条件下医疗数据的自动化采集。方法:该平台以医疗物联网“感知—网络—平台”架构为基础构建。首先,选取Raspberr...目的:设计一种基于光学字符识别(optical character recognition,OCR)模型的医疗救治装备数据采集平台,以实现应急灾害救援条件下医疗数据的自动化采集。方法:该平台以医疗物联网“感知—网络—平台”架构为基础构建。首先,选取Raspberry Pi 4B作为边缘节点,使用视频采集卡、摄像头、平板计算机等搭建硬件环境。其次,基于卷积循环神经网络(convolutional recurrent neural network,CRNN)优化OCR模型,通过软硬件协同方式实现医疗终端视频流处理与数据提取。最后,采用FineBI工具实现交互界面设计与数据库链接。结果:经实验验证,该平台的硬件环境可靠、稳定,优化后的OCR模型文本识别准确率提升,且采用该平台能够实现对医疗设备数据的快速、自动化采集。结论:采用该平台能够为医护人员提供全面、准确的医疗救治装备数据支撑,有利于提升医疗救治效率。展开更多
基金supported by National Natural Science Foundation of China (Nos. 11605023, 11805028, and 11705020)the National Key R&D Program of China (No. 2017YFE0301300)+1 种基金the China Postdoctoral Science Foundation (Nos. 2017T100172 and 2016M591423)the Fundamental Research Funds for the Central Universities (Nos. DUT17RC(4)53 and DUT18LK38)
文摘The study of sulfur hexafluoride(SF6) discharge is vital for its application in gas-insulated equipment. Direct current partial discharge(PD) may cause SF6 decomposition, and the decomposed products of SF6, such as F atoms, play a dominant role in the breakdown of insulation systems. In this study, the PD caused by metal protrusion defects is simulated by a needle-plate electrode using pulsed high voltage in SF6/Ar mixtures. The spatial and temporal characteristics of SF6/Ar plasma are analyzed by measuring the emission spectra of F and Ar atoms, which are important for understanding the characteristics of PD. The spatial resolved results show that both F and Ar atom spectral intensities increase first from the plate anode to the needle and then decrease under the conditions of a background pressure of400 Pa, peak voltage of-1000 V, frequency of 2 kHz, pulse width of 60 μs, and electrode gap of 5-9 mm. However, the distribution characteristics of F and Ar are significantly different. The temporal distribution results show that the spectral intensity of Ar decreasesfirst and then increases slowly, while the spectral intensity of F increases slowly for the duration of the pulsed discharge at the electrode gap of 5 mm and the pulse width of40-80 μs.
文摘Optical networks are expected to cater for the future Internet due to the high speed and capacity that they offer. Caching in the core network has proven to reduce power usage for various video services in current optical networks. This paper investigates whether video caching will still remain power efficient in future optical networks. The study compares the power consumption of caching in a current IP over WDM core network to a future network. The study considers a number of features to exemplify future networks. Future optical networks are considered where： （1） network devices consume less power, （2） network devices have sleep-mode capabilities, （3） IP over WDM implements lightpath bypass, and （4） the demand for video content significantly increases and high definition video dominates. Results show that video caching in future optical networks saves up to 42% of power consumption even when the power consumption of transport reduces. These results suggest that video caching is expected to remain a green option in video services in the future Internet.
基金the National Natural Science Foundation (59875008)Beijing Nova Program of China (2006B24)
文摘Comparied to traditional optical processing methods,numerical controlled surfacing techniques have irreplaceable effects especially in spherical and aspherical optics. In this paper,fabricating methods,mechanisms and processes are analyzed. Also,some processing difficulties and problems are discussed. The possible improvements and feasible methods are given.
文摘目的:设计一种基于光学字符识别(optical character recognition,OCR)模型的医疗救治装备数据采集平台,以实现应急灾害救援条件下医疗数据的自动化采集。方法:该平台以医疗物联网“感知—网络—平台”架构为基础构建。首先,选取Raspberry Pi 4B作为边缘节点,使用视频采集卡、摄像头、平板计算机等搭建硬件环境。其次,基于卷积循环神经网络(convolutional recurrent neural network,CRNN)优化OCR模型,通过软硬件协同方式实现医疗终端视频流处理与数据提取。最后,采用FineBI工具实现交互界面设计与数据库链接。结果:经实验验证,该平台的硬件环境可靠、稳定,优化后的OCR模型文本识别准确率提升,且采用该平台能够实现对医疗设备数据的快速、自动化采集。结论:采用该平台能够为医护人员提供全面、准确的医疗救治装备数据支撑,有利于提升医疗救治效率。
