Hα(Balmer-alpha), Hβ (Balmer-beta) and Hγ (Balmer-gamma) spectral line inten- sities in atomic hydrogen plasma are investigated by using a high-power RF source. The intensities of the Hα, Hβ and Hγ spectra...Hα(Balmer-alpha), Hβ (Balmer-beta) and Hγ (Balmer-gamma) spectral line inten- sities in atomic hydrogen plasma are investigated by using a high-power RF source. The intensities of the Hα, Hβ and Hγ spectral lines are detected by increasing the input power (0-6 kW) of ICPs (inductively coupled plasmas). With the increase of net input power, the intensity of Hα im- proves rapidly (0-2 kW), and then reaches its dynamic equilibrium; the intensities of Hβ can be divided into three processes: obvious increase (0-2 kW), rapid increase (2-4 kW), almost constant (4-6 kW); while the intensities of Hγ increase very slowly. The energy levels of the excited hydro- gen atoms and the splitting energy levels produced by an obvious Stark effect play an important role in the results.展开更多
随着我国经济的不断增长,科学技术也在不断进步,在此背景下我国的广播电视业务不断延伸,满足当前的各类需求。广播电视需要稳定的电路,以此来维持节目安全播出,如果电源出现问题,则会导致供电波动,还可能引发各类风险事故。若想规避电...随着我国经济的不断增长,科学技术也在不断进步,在此背景下我国的广播电视业务不断延伸,满足当前的各类需求。广播电视需要稳定的电路,以此来维持节目安全播出,如果电源出现问题,则会导致供电波动,还可能引发各类风险事故。若想规避电源可能出现的异常情况,要考虑到广播电视在运行中需要的电量,借助不间断电源(Uninterruptible Power Supply,UPS)装置进行优化,从而在异常情况下通过蓄电池来保持供电,确保安全播出机房的稳定运行。文章将对UPS电源在广播电视安全播出机房中的应用及维护进行分析论述,并提出具体策略,以期为相关人员提供参考。展开更多
In cognitive radio (CR),power allocation plays an important role in protecting primary user from disturbance of secondary user. Some existing studies about power allocation in CR utilize 'interference temperature'...In cognitive radio (CR),power allocation plays an important role in protecting primary user from disturbance of secondary user. Some existing studies about power allocation in CR utilize 'interference temperature' to achieve this protection,which might not be suitable for the OFDM-based CR. Thus in this paper,power allocation problem in multi-user orthogonal frequency division multiplexing (OFDM) and distributed antenna cognitive radio with radio over fiber (RoF) is firstly modeled as an optimization problem,where the limitation on secondary user is not 'interference temperature',but that total throughput of primary user in all the resource units (RUs) must be beyond the given threshold. Moreover,based on the theorem about maximizing the total throughput of secondary user,equal power allocation algorithm is introduced. Furthermore,as the optimization problem for power allocation is not convex,it is transformed to be a convex one with geometric programming,where the solution can be obtained using duality and Karush-Kuhn-Tucker (KKT) conditions to form the optimal power allocation algorithm. Finally,extensive simulation results illustrate the significant performance improvement of the optimal algorithm compared to the existing algorithm and equal power allocation algorithm.展开更多
Spectrum sharing for efficient reuse of licensed spectrum is an important concept for cognitive radio technologies.In a spectrum-sharing system(SSS),deploying the antennas in a distributed manner can offer a new spati...Spectrum sharing for efficient reuse of licensed spectrum is an important concept for cognitive radio technologies.In a spectrum-sharing system(SSS),deploying the antennas in a distributed manner can offer a new spatial dimension for the efficient reuse of licensed frequency bands.To improve the whole performance of multiple secondary users(SUs),this paper addresses the problem of coordinated multi-SU spectrum sharing in a distributed antenna-based SSS.By adopting the Hungarian method,the primal decomposition method and pricing policy,we propose a coordinated multi-user transmission scheme,so as to maximize the sum-rate of SUs.Simulation results show that the proposed method can significantly enhance the system performance,and the computational complexity is low.展开更多
不间断电源(Uninterruptible Power Supply,UPS)是广播电视发射台进行信号传输的关键部分,也是广播电视发射台的重要组成部分。UPS可以保证广播电视发射台不间断供电,保障电视节目顺利播出。广播电视发射台应高度重视UPS的管理维修工作...不间断电源(Uninterruptible Power Supply,UPS)是广播电视发射台进行信号传输的关键部分,也是广播电视发射台的重要组成部分。UPS可以保证广播电视发射台不间断供电,保障电视节目顺利播出。广播电视发射台应高度重视UPS的管理维修工作,加强对智能UPS的研究,充分发挥智能UPS在广播电视发射台中的应用价值。从UPS的相关概述入手,分析UPS系统设计,针对智能UPS在广播电视发射台中应用时存在的常见问题提出针对性的解决策略。展开更多
近年来,随着广播电视业务的发展,播出机房在安全播出和设备用电方面的需求呈现逐渐增长的趋势,老旧的不间断电源(Uninterruptille Power Supply,UPS)设备改造工程越来越多。为有效解决广播电视播出机房因停电导致微机设备中的重要数据...近年来,随着广播电视业务的发展,播出机房在安全播出和设备用电方面的需求呈现逐渐增长的趋势,老旧的不间断电源(Uninterruptille Power Supply,UPS)设备改造工程越来越多。为有效解决广播电视播出机房因停电导致微机设备中的重要数据丢失或播出信号中断等问题,需要在播出机房中合理接入UPS,合理配置在线式UPS是充分保障播出机房安全播出的重要手段。首先阐述了UPS电源的基本工作原理,其次详细论述了UPS在广播电视安全播出机房中的有效应用,最后提出了UPS的日常维护方法,以此确保广播电视的安全播出不会受到断电与跳闸等情况的影响,为相关从业人士提供借鉴。展开更多
已有监测方法存在通信盲区,采集数据平稳度较差,致使设备故障预测误差率较高,无法满足智能电网发展需求。为此,提出基于改进射频识别(radio frequency identification,RFID)技术的输配电设备全生命周期智能化监测方法。划分输配电设备...已有监测方法存在通信盲区,采集数据平稳度较差,致使设备故障预测误差率较高,无法满足智能电网发展需求。为此,提出基于改进射频识别(radio frequency identification,RFID)技术的输配电设备全生命周期智能化监测方法。划分输配电设备全生命周期阶段,并总结生命周期阶段判定特征;以此为基础,改进RFID技术搭建多天线RFID通信框架;以搭建通信框架为依据,结合设备不同生命周期阶段特性,自适应调整运行数据的采集间隔,获取输配电设备运行数据;有效结合整合移动平均自回归(autoregressive integrated moving average,ARIMA)模型与支持向量机算法,提前预测输配电设备故障,从而实现输配电设备全生命周期的智能化监测。试验结果表明:所提方法的输配电设备运行数据采集平稳度数值较小,故障预测误差率较低。输配电设备智能化监测结果可以反映智能电网的稳定运行、发展进度与供电质量,以此保障输配电设备的可靠运行。展开更多
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2011GB108011 and 2010GB103001)the Major International(Regional) Project Cooperation and Exchanges(No.11320101005)
文摘Hα(Balmer-alpha), Hβ (Balmer-beta) and Hγ (Balmer-gamma) spectral line inten- sities in atomic hydrogen plasma are investigated by using a high-power RF source. The intensities of the Hα, Hβ and Hγ spectral lines are detected by increasing the input power (0-6 kW) of ICPs (inductively coupled plasmas). With the increase of net input power, the intensity of Hα im- proves rapidly (0-2 kW), and then reaches its dynamic equilibrium; the intensities of Hβ can be divided into three processes: obvious increase (0-2 kW), rapid increase (2-4 kW), almost constant (4-6 kW); while the intensities of Hγ increase very slowly. The energy levels of the excited hydro- gen atoms and the splitting energy levels produced by an obvious Stark effect play an important role in the results.
文摘随着我国经济的不断增长,科学技术也在不断进步,在此背景下我国的广播电视业务不断延伸,满足当前的各类需求。广播电视需要稳定的电路,以此来维持节目安全播出,如果电源出现问题,则会导致供电波动,还可能引发各类风险事故。若想规避电源可能出现的异常情况,要考虑到广播电视在运行中需要的电量,借助不间断电源(Uninterruptible Power Supply,UPS)装置进行优化,从而在异常情况下通过蓄电池来保持供电,确保安全播出机房的稳定运行。文章将对UPS电源在广播电视安全播出机房中的应用及维护进行分析论述,并提出具体策略,以期为相关人员提供参考。
文摘In cognitive radio (CR),power allocation plays an important role in protecting primary user from disturbance of secondary user. Some existing studies about power allocation in CR utilize 'interference temperature' to achieve this protection,which might not be suitable for the OFDM-based CR. Thus in this paper,power allocation problem in multi-user orthogonal frequency division multiplexing (OFDM) and distributed antenna cognitive radio with radio over fiber (RoF) is firstly modeled as an optimization problem,where the limitation on secondary user is not 'interference temperature',but that total throughput of primary user in all the resource units (RUs) must be beyond the given threshold. Moreover,based on the theorem about maximizing the total throughput of secondary user,equal power allocation algorithm is introduced. Furthermore,as the optimization problem for power allocation is not convex,it is transformed to be a convex one with geometric programming,where the solution can be obtained using duality and Karush-Kuhn-Tucker (KKT) conditions to form the optimal power allocation algorithm. Finally,extensive simulation results illustrate the significant performance improvement of the optimal algorithm compared to the existing algorithm and equal power allocation algorithm.
基金supported in part by the National Science Foundation of China for Young Scholars under grant No.61201186The National Basic Research Program undergrant No.2012AA01A502+5 种基金National Natural Science Foundation of China under grant No.61201192National S&T Major Project under grant No.2014ZX03003003-002Tsinghua-HUAWEI Joint R&D on Soft Defined Protocol StackTsinghua-HUAWEI Joint Research on 5G Air Interface TechnicalTsinghua-Qualcom joint research programIndependent innovation on Future Virtualization Platform under grant No.015Z02-3
文摘Spectrum sharing for efficient reuse of licensed spectrum is an important concept for cognitive radio technologies.In a spectrum-sharing system(SSS),deploying the antennas in a distributed manner can offer a new spatial dimension for the efficient reuse of licensed frequency bands.To improve the whole performance of multiple secondary users(SUs),this paper addresses the problem of coordinated multi-SU spectrum sharing in a distributed antenna-based SSS.By adopting the Hungarian method,the primal decomposition method and pricing policy,we propose a coordinated multi-user transmission scheme,so as to maximize the sum-rate of SUs.Simulation results show that the proposed method can significantly enhance the system performance,and the computational complexity is low.
文摘不间断电源(Uninterruptible Power Supply,UPS)是广播电视发射台进行信号传输的关键部分,也是广播电视发射台的重要组成部分。UPS可以保证广播电视发射台不间断供电,保障电视节目顺利播出。广播电视发射台应高度重视UPS的管理维修工作,加强对智能UPS的研究,充分发挥智能UPS在广播电视发射台中的应用价值。从UPS的相关概述入手,分析UPS系统设计,针对智能UPS在广播电视发射台中应用时存在的常见问题提出针对性的解决策略。
文摘近年来,随着广播电视业务的发展,播出机房在安全播出和设备用电方面的需求呈现逐渐增长的趋势,老旧的不间断电源(Uninterruptille Power Supply,UPS)设备改造工程越来越多。为有效解决广播电视播出机房因停电导致微机设备中的重要数据丢失或播出信号中断等问题,需要在播出机房中合理接入UPS,合理配置在线式UPS是充分保障播出机房安全播出的重要手段。首先阐述了UPS电源的基本工作原理,其次详细论述了UPS在广播电视安全播出机房中的有效应用,最后提出了UPS的日常维护方法,以此确保广播电视的安全播出不会受到断电与跳闸等情况的影响,为相关从业人士提供借鉴。