We present in this paper a wideband RF demodulator using a five-port correlator and a power detector for channel sounding applications. The demodulator has been fabricated using microstrip components. The correlator r...We present in this paper a wideband RF demodulator using a five-port correlator and a power detector for channel sounding applications. The demodulator has been fabricated using microstrip components. The correlator receives from the five-port qualities that allow it to be low-cost and less sensitive to the phase and amplitude imbalances. A calibration procedure is proposed to find the complex envelope of the RF signal applied at the input of the five-port correlator. Simulation with Advanced Design System software and measurement results have been conducted to demonstrate its capabilities as a RF signal demodulator operating in a wideband around 2.4 GHz frequency.展开更多
The flow boiling heat transfer characteristics of refrigerant R134 a flowing inside two different kinds of minichannels are investigated. One channel is multi-port extruded with the hydraulic diameter of 0.63 mm,and t...The flow boiling heat transfer characteristics of refrigerant R134 a flowing inside two different kinds of minichannels are investigated. One channel is multi-port extruded with the hydraulic diameter of 0.63 mm,and the other one is rectangular with offset fins and a hydraulic diameter of 1.28 mm. The experiments are performed with a mass flow rate between 68 and 630 kg/(m^2·s),a heat flux between 9 and 64 kW/m^2,and a saturation pressure between 0.24 and 0.63 MPa,under the constant heat flux heating mode. It is found that the effect of mass flow rate on boiling heat transfer is related to heat flux,and that with the increase of heat flux,the effect can only be efficient in higher vapor quality region. The effects of heat flux and saturation pressure on boiling heat transfer are related to a threshold vapor quality,and the value will gradually decrease with the increase of heat flux or saturation pressure. Based on these analyses,a new correlation is proposed to predict the boiling heat transfer coefficient of refrigerant R134 a in the mini-channels under the experimental conditions.展开更多
A conventional multi-channel pulse amplitude analyzer acquires single energy spectrum,but provides no information on its tendency with time.To address the limitation,we propose a scheme of time-sharing multichannel pu...A conventional multi-channel pulse amplitude analyzer acquires single energy spectrum,but provides no information on its tendency with time.To address the limitation,we propose a scheme of time-sharing multichannel pulse amplitude analyzer(TSMCA).A dual-port random access memory is divided into two storage spaces,one for current energy spectrum data acquisition and another for previous energy spectrum data storage.The two tasks can be performed simultaneously,and the time-related variation tendency of energy spectrum can be obtained.A prototype system of TSMCA is designed.It performs nicely,with maximum channel number of 4096 in capacity of 2^(32)/Ch,minimal time-sharing slice of 25 ms,the differential nonlinearity of <1.5%,and the integral nonlinearity of <0.3%.展开更多
2023年国内三大通信运营商的财务报表显示,中国联通、中国电信及中国移动的网络运营及支撑成本达到607亿元、1218亿元和2609亿元,且呈现不断攀升的态势。在5G尚无“杀手级”业务和通信行业市场基本饱和的情况下,运营成本压力不容小视。B...2023年国内三大通信运营商的财务报表显示,中国联通、中国电信及中国移动的网络运营及支撑成本达到607亿元、1218亿元和2609亿元,且呈现不断攀升的态势。在5G尚无“杀手级”业务和通信行业市场基本饱和的情况下,运营成本压力不容小视。BBU(Building Base band Unit,基带处理单元)回局及整合做为降本、提质和增效的一种手段,符合工业和信息化部等七部门联合下发的《信息通信行业绿色低碳发展行动计划(2022—2025年)》文件要求,是落实该行动计划“推广集中化无线接入网架构,进一步节省基站机房、电源、空调等配套需求”的具体举措。文章从BBU回局及整合的角度出发,分析实施难点并提出应对和解决策略,以某地市案例为切入点,阐述锚点机房的选取原则、BBU回局及整合的策略、具体的实施过程和实施效果。展开更多
文摘We present in this paper a wideband RF demodulator using a five-port correlator and a power detector for channel sounding applications. The demodulator has been fabricated using microstrip components. The correlator receives from the five-port qualities that allow it to be low-cost and less sensitive to the phase and amplitude imbalances. A calibration procedure is proposed to find the complex envelope of the RF signal applied at the input of the five-port correlator. Simulation with Advanced Design System software and measurement results have been conducted to demonstrate its capabilities as a RF signal demodulator operating in a wideband around 2.4 GHz frequency.
文摘The flow boiling heat transfer characteristics of refrigerant R134 a flowing inside two different kinds of minichannels are investigated. One channel is multi-port extruded with the hydraulic diameter of 0.63 mm,and the other one is rectangular with offset fins and a hydraulic diameter of 1.28 mm. The experiments are performed with a mass flow rate between 68 and 630 kg/(m^2·s),a heat flux between 9 and 64 kW/m^2,and a saturation pressure between 0.24 and 0.63 MPa,under the constant heat flux heating mode. It is found that the effect of mass flow rate on boiling heat transfer is related to heat flux,and that with the increase of heat flux,the effect can only be efficient in higher vapor quality region. The effects of heat flux and saturation pressure on boiling heat transfer are related to a threshold vapor quality,and the value will gradually decrease with the increase of heat flux or saturation pressure. Based on these analyses,a new correlation is proposed to predict the boiling heat transfer coefficient of refrigerant R134 a in the mini-channels under the experimental conditions.
基金supported by the National Natural Science Foundation of China(Nos.11375195,11375263,and 11105143)the project of National Magnetic Confinement Fusion Energy Development Research(No.2013GB104003)
文摘A conventional multi-channel pulse amplitude analyzer acquires single energy spectrum,but provides no information on its tendency with time.To address the limitation,we propose a scheme of time-sharing multichannel pulse amplitude analyzer(TSMCA).A dual-port random access memory is divided into two storage spaces,one for current energy spectrum data acquisition and another for previous energy spectrum data storage.The two tasks can be performed simultaneously,and the time-related variation tendency of energy spectrum can be obtained.A prototype system of TSMCA is designed.It performs nicely,with maximum channel number of 4096 in capacity of 2^(32)/Ch,minimal time-sharing slice of 25 ms,the differential nonlinearity of <1.5%,and the integral nonlinearity of <0.3%.
文摘2023年国内三大通信运营商的财务报表显示,中国联通、中国电信及中国移动的网络运营及支撑成本达到607亿元、1218亿元和2609亿元,且呈现不断攀升的态势。在5G尚无“杀手级”业务和通信行业市场基本饱和的情况下,运营成本压力不容小视。BBU(Building Base band Unit,基带处理单元)回局及整合做为降本、提质和增效的一种手段,符合工业和信息化部等七部门联合下发的《信息通信行业绿色低碳发展行动计划(2022—2025年)》文件要求,是落实该行动计划“推广集中化无线接入网架构,进一步节省基站机房、电源、空调等配套需求”的具体举措。文章从BBU回局及整合的角度出发,分析实施难点并提出应对和解决策略,以某地市案例为切入点,阐述锚点机房的选取原则、BBU回局及整合的策略、具体的实施过程和实施效果。
