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5G通信主板层压技术难点及对策
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作者 傅立红 唐缨 《印制电路信息》 2024年第6期26-30,共5页
5G通信印制电路板(PCB)主板是5G基站的核心部件之一。主板良好的层压质量决定了5G通信信号在主板线路中传送的质量。根据一款5G通信主板的设计技术特点,从层压结构设计、基板材料的选用、层压流程制作中的技术要点等方面进行技术分析,... 5G通信印制电路板(PCB)主板是5G基站的核心部件之一。主板良好的层压质量决定了5G通信信号在主板线路中传送的质量。根据一款5G通信主板的设计技术特点,从层压结构设计、基板材料的选用、层压流程制作中的技术要点等方面进行技术分析,给出相应的改善对策,并通过实验数据验证了改善对策的有效性。 展开更多
关键词 主板 插入损耗 转压点温度
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压合条件对层偏的影响量化研究
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作者 金文雄 黎钦源 +1 位作者 兰富民 韩明 《印制电路信息》 2016年第A02期273-280,共8页
传统刚性板的层偏的影响因素有很多,从板材涨缩,PE内层拉伸系数,内层曝光对准度,AOI冲孔精度,一直到层压铆合/融合/压合,每个厂商都有各自的一整套控制系统,针对压合这段流程对层偏的影响,本文专门针对压合条件进行识别,通过... 传统刚性板的层偏的影响因素有很多,从板材涨缩,PE内层拉伸系数,内层曝光对准度,AOI冲孔精度,一直到层压铆合/融合/压合,每个厂商都有各自的一整套控制系统,针对压合这段流程对层偏的影响,本文专门针对压合条件进行识别,通过DOE的方式完成压合条件对层偏影响的量化数据分析,从而为指定压合生产条件,减少层偏给出了指引方向。 展开更多
关键词 层偏 温升 转压点
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A new network losses allocation method in deregulated environment
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作者 王承民 侯志俭 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2005年第1期61-66,共6页
Network losses allocation is one of the major problems in the market environment. The quadric function of the injected nodal power is used in this paper as a representation for network losses, which are allocated fair... Network losses allocation is one of the major problems in the market environment. The quadric function of the injected nodal power is used in this paper as a representation for network losses, which are allocated fairly using the called market equilibrium principle while the bidding curves are corrected. The power market equilibrium is simulated as three different models that can be solved simply by the optimal power flow algorithm combining the generation scheduling problem with network losses allocation. The case study is made at an IEEE-30 nodes system and a perfect result is proved in this paper. 展开更多
关键词 power market network losses market equilibrium optimal power flow
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Identification and Modeling of Froth to Spray Transition on Sieve Trays
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作者 刘云义 陈建孟 谭天恩 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2000年第2期113-117,共5页
The transition from froth to spray regime on sieve trays was experimentally studied in an air/water simulator with 300mm diameter. It has been found that the regime transition occurs as the clear liquid height is equa... The transition from froth to spray regime on sieve trays was experimentally studied in an air/water simulator with 300mm diameter. It has been found that the regime transition occurs as the clear liquid height is equal to the residual pressure drop on the trays. A convenient and accurate technique was proposed for determination of the regime transition point. Based on analysis of the transition process at a sieve hole, a new formula which can be used to correlate the experimental results was provided. 展开更多
关键词 sieve tray froth to spray regime transition pressure drop clear liquid height
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Comprehensive predictive control of neutral-point voltage balancing for back-to-back three-level NPC converters
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作者 范必双 谭冠政 +1 位作者 樊绍胜 叶吉祥 《Journal of Central South University》 SCIE EI CAS 2014年第11期4210-4219,共10页
A comprehensive predictive strategy was proposed for the neutral-point balancing control of back-to-back three-level converters. The phase currents at both sides and the DC-link capacitor voltages were measured for th... A comprehensive predictive strategy was proposed for the neutral-point balancing control of back-to-back three-level converters. The phase currents at both sides and the DC-link capacitor voltages were measured for the prediction of the neutral-point current. A quality function was found to balance the neutral-point, and a metabolic on-times distribution factor was used as a predicator to minimize the quality function at each switching state. Simulation results show that the proposed method produces smaller ripples in tested signals compared with the established one, namely, 9.15% less in a total harmonic distortion(THD) of line-to-line voltage, 1.08% less in the THD of phase current, and 0.9 V less in the ripple of the neutral-point voltage. The obtained experimental results show that the main harmonics of the line-to-line voltage and the phase current in the proposed method are improved by 10 d B and 6 d B, respectively, and the ripple of neutral-point voltage is halved compared to the established one. 展开更多
关键词 back-to-back converter three-level converter neutral-point balancing comprehensive control predictive control
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Design and Implementation of a Digitally Controlled Photovoltaic System Using Series Connected Buck Converters
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作者 Jaouad Tanouti Mohammed Setti Abdelhak Aziz El Mamoun Aziz 《Journal of Environmental Science and Engineering(B)》 2012年第4期456-464,共9页
In PV (photovoltaic) power systems, a MPPT (maximum power point tracking) algorithm is vital in increasing their efficiency. But it is also vital to take into account the non ideal conditions resulting from comple... In PV (photovoltaic) power systems, a MPPT (maximum power point tracking) algorithm is vital in increasing their efficiency. But it is also vital to take into account the non ideal conditions resulting from complex physical environments in such PV power systems. To minimize the degradation of performances caused by these conditions, and therefore adding reliability and robustness, this paper presents an implementation of a digitally controlled system using a topology based on series connected DC-DC buck converters for a stand-alone PV power system applications, operating with local and autonomous controls, to track the maximum power points of PV modules in non ideal conditions. Simulations are carried out by using C-MEX S-functions under MATLAB-SIMULINK environment. A PV system of 1.44 kWc is described and simulation results are presented. 展开更多
关键词 Buck converter boost converter MPPT control photovoltaic power system solar energy.
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An Integrated System for Active Filter and Photovoltaic Energy Conversion
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作者 H.H. Tumbelaka M. Miyatake 《Journal of Energy and Power Engineering》 2010年第6期39-44,共6页
This paper focuses on the implementation of a three-phase four-wire current-controlled Voltage Source Inverter (CC-VSI) as both power quality improvement and Photovoltaic (PV) energy extraction. For power quality ... This paper focuses on the implementation of a three-phase four-wire current-controlled Voltage Source Inverter (CC-VSI) as both power quality improvement and Photovoltaic (PV) energy extraction. For power quality improvement, the CC-VSI works as a grid current-controller shunt active power filter. Then, the PV array supported by the Hill- Climbing maximum power point tracking (MPPT) controller is coupled to the DC bus of the CC-VSI. The output of the MPPT controller is a DC voltage that determines the DC-bus voltage according to the PV maximum power. From computer simulation results, the CC-VSI is able to compensate for the harmonic and reactive power as well as to extract the PV maximum power. 展开更多
关键词 Active power filter MPPT PV energy conversion.
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Observation of a bi-critical point between antiferromagnetic and superconducting phases in pressurized single crystal Ca0.73La0.27FeAs2 被引量:3
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作者 Yazhou Zhou ShanJiang +14 位作者 Qi wu Vladimir A.Sidorov Jing Guo Wei Yi Shan Zhang Zhe Wang HonghongWang shu Cai Ke Yang Sheng Jiang Aiguo Li Ni Ni Guangming Zhang Liling Sun Zhongxian Zhao 《Science Bulletin》 SCIE EI CAS CSCD 2017年第12期857-862,共6页
One of the most strikingly universal features of the high-temperature superconductors is that the super- conducting phase emerges in the close proximity of the antiferromagnetic phase, and the interplay between these ... One of the most strikingly universal features of the high-temperature superconductors is that the super- conducting phase emerges in the close proximity of the antiferromagnetic phase, and the interplay between these two phases poses a long-standing challenge. It is commonly believed that, as the antifer- romagnetic transition temperature is continuously suppressed to zero, there appears a quantum critical point, around which the existence of antiferromagnetic fluctuation is responsible for the development of the superconductivity. In contrast to this scenario, we report the observation of a bi-critical point identified at 2,88 GPa and 26.02 K in the pressurized high-quality single crystal Cao.73Lao.27FeAs2 by com- plementary in-situ high pressure measurements. At the critical pressure, we find that the antiferromag- netism suddenly disappears and superconductivity simultaneously emerges at almost the same temperature, and that the external magnetic field suppresses the superconducting transition temperature but hardly affects the antiferromagnetic transition temperature. 展开更多
关键词 Iron pnictide superconductorBi-critical pointSuperconductivityAntiferromagnetic orderHigh pressure
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