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船载雷达风负载设计 被引量:2
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作者 李志坚 胡金辉 《科学技术与工程》 2011年第30期7560-7563,共4页
风负载是船载雷达天线设计计算时的一项重要内容。对风力矩的影响因素进行分析,结合船载雷达设备重点对风速设计方法进行研究,并介绍减小风负载的措施。
关键词 船载雷达 风负载 速设计
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某型天线车抗倾覆能力的计算与检验 被引量:8
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作者 冯大成 《电子机械工程》 2011年第2期28-30,共3页
近年来,米波雷达因其在反隐身目标方面所体现出的优势而引起了雷达界的高度重视,新型米波雷达不断问世。主要用于警戒雷达的米波频率较低,因而雷达天线结构比较稀疏,天线阵面巨大,并且大多部署在沿海或沙漠、戈壁地区,环境条件恶劣,风... 近年来,米波雷达因其在反隐身目标方面所体现出的优势而引起了雷达界的高度重视,新型米波雷达不断问世。主要用于警戒雷达的米波频率较低,因而雷达天线结构比较稀疏,天线阵面巨大,并且大多部署在沿海或沙漠、戈壁地区,环境条件恶劣,风力往往比较大。因此米波雷达天线车的安全性设计尤为重要,而天线车的抗倾覆能力又是安全性设计的重中之重。文中给出了某型号车载米波雷达风负载的计算方法及给定环境条件下天线车的抗倾覆能力,并对抗倾覆能力的检验方法作了简要的介绍,通过实验验证了计算方法的可靠性。 展开更多
关键词 风负载 倾覆力矩 抗倾覆 检验方法
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某雷达天线方位驱动系统设计分析
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作者 陈浩 仙锦 《现代制造技术与装备》 2020年第5期44-44,49,共2页
以某型雷达天线为对象,对雷达天线方位驱动系统计算流程进行梳理与分析,包括回转支承的选型、雷达传动系统风负载、惯性力矩、摩擦力矩的计算、系统方位同步精度的计算,可为类似产品上雷达天线方位驱动系统的计算提供参考。
关键词 方位驱动 风负载 同步精度
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Valuline天线——通信天线小精灵
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作者 《中国经济和信息化》 1998年第18期25-25,共1页
近日,美国安德鲁公司(AndrewCorporation)推出了全新的Valuline高性能、小尺寸(VHLP)0.3和0.6米天线。该天线系列备有22-GHz、26-GHz和38-GHz等多种频率带宽选择,可满足全球移动电话、个人通信服务和专用网络用户对性能和预算的要求。 V... 近日,美国安德鲁公司(AndrewCorporation)推出了全新的Valuline高性能、小尺寸(VHLP)0.3和0.6米天线。该天线系列备有22-GHz、26-GHz和38-GHz等多种频率带宽选择,可满足全球移动电话、个人通信服务和专用网络用户对性能和预算的要求。 VHLP天线由铝、电镀支架和不锈钢硬件制成,能确保性能不受环境影响。其性能满足全球各种技术标准,包括美国联邦通信委员会、无线电通信管理局和欧洲电信标准委员会的性能要求。 展开更多
关键词 通信天线 小精灵 个人通信服务 频率带宽 全球移动电话 电信标准 专用网络 美国联邦通信委员会 无线电通信 风负载
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Determination method of load balance ranges for train operation safety under strong wind 被引量:3
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作者 田红旗 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第3期1146-1154,共9页
The aerodynamic performances of a passenger car and a box car with different heights of windbreak walls under strong wind were studied using the numerical simulations, and the changes of aerodynamic side force, lift f... The aerodynamic performances of a passenger car and a box car with different heights of windbreak walls under strong wind were studied using the numerical simulations, and the changes of aerodynamic side force, lift force and overturning moment with different wind speeds and wall heights were calculated. According to the principle of static moment balance of vehicles, the overturning coefficients of trains with different wind speeds and wall heights were obtained. Based on the influence of wind speed and wall height on the aerodynamic performance and the overturning stability of trains, a method of determination of the load balance ranges for the train operation safety was proposed, which made the overturning coefficient have nearly closed interval. A min(|A1|+|A2|), s.t. |A1|→|A2|(A1 refers to the downwind overturning coefficient and A2 refers to the upwind overturning coefficient)was found. This minimum value helps to lower the wall height as much as possible, and meanwhile, guarantees the operation safety of various types of trains under strong wind. This method has been used for the construction and improvement of the windbreak walls along the Lanzhou–Xinjiang railway(from Lanzhou to Urumqi, China). 展开更多
关键词 strong wind train load balance range overturning coefficient aerodynamic performance
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Reliability analysis of web server cluster systems based on proportional hazards model
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作者 Hou Chunyan Wang Jinsong Chen Chen 《Journal of Southeast University(English Edition)》 EI CAS 2018年第2期187-190,共4页
An approach for web server cluster(WSC)reliability and degradation process analysis is proposed.The reliability process is modeled as a non-homogeneous Markov process(NHMH)composed of several non-homogeneous Poisson p... An approach for web server cluster(WSC)reliability and degradation process analysis is proposed.The reliability process is modeled as a non-homogeneous Markov process(NHMH)composed of several non-homogeneous Poisson processes(NHPPs).The arrival rate of each NHPP corresponds to the system software failure rate which is expressed using Cox s proportional hazards model(PHM)in terms of the cumulative and instantaneous load of the software.The cumulative load refers to software cumulative execution time,and the instantaneous load denotes the rate that the users requests arrive at a server.The result of reliability analysis is a time-varying reliability and degradation process over the WSC lifetime.Finally,the evaluation experiment shows the effectiveness of the proposed approach. 展开更多
关键词 web server cluster LOAD-SHARING proportional hazards model RELIABILITY software aging
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Fuzzy Logic Controlled Dual Active Bridge Series Resonant Converter for DC Smart Grid Application
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作者 Thabit Salim Nassor Atsushi Yona Tomonobu Senjyu 《Journal of Energy and Power Engineering》 2015年第8期741-752,共12页
Over the last few years, smart grids have become a topic of intensive research, development and deployment across the world. This is due to the fact that, through the smart grid, stable and reliable power systems can ... Over the last few years, smart grids have become a topic of intensive research, development and deployment across the world. This is due to the fact that, through the smart grid, stable and reliable power systems can be achieved. This paper presents a fuzzy logic control for dual active bridge series resonant converters for DC smart grid application. The DC smart grid consists of wind turbine and photovoltaic generators, controllable and DC loads, and power converters. The proposed control method has been applied to the controllable load's and the grid side's dual active bridge series resonant converters for attaining control of the power system. It has been used for management of controllable load's state of charge, DC feeder's voltage stability during the loads and power variations from wind energy and photovoltaic generation and power flow management between the grid side and the DC smart grid. The effectiveness of the proposed DC smart grid operation has been verified by simulation results obtained by using MATLAB and PLECS cards. 展开更多
关键词 DC smart grid dual active bridge series resonant converter wind turbine controllable loads photovoltaic.
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Assessing Micro-generation's and Non-linear Loads' Impact in the Power Quality of Low Voltage Distribution Networks
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作者 Paulo Bonifacio Susana Viana +1 位作者 Luis Rodrigues Ana Estanqueiro 《Journal of Energy and Power Engineering》 2013年第12期2321-2335,共15页
Distribution networks face an increasing penetration of solar PV (photovoltaic) and small WTG (wind turbine generator) as well as other forms of micro-generation. To this scenario, one must add the dissemination o... Distribution networks face an increasing penetration of solar PV (photovoltaic) and small WTG (wind turbine generator) as well as other forms of micro-generation. To this scenario, one must add the dissemination of non-linear loads such as EV (electric vehicles). There is something in common between those loads and sources: the extensive use of power electronic converters with commutated switches. These devices may be a source of medium-to-high frequency harmonic distortion and their impact on the local distribution grid must be carefully assessed in order to evaluate their negative impacts on the network, on the existing conventional loads and also on other active devices. In this paper, methodologies to characterize effects such as: harmonics, network unbalances, damaging power line resonance conditions, and over/under voltages are described and applied to a real local grid configuration. 展开更多
关键词 MICRO-GENERATION distribution network power quality HARMONICS smart grid electric vehicle.
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Smart load control of the large-scale offshore wind turbine blades subject to wake effect 被引量:1
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作者 Mingming Zhang Bin Tan Jianzhong Xu 《Science Bulletin》 SCIE EI CAS CSCD 2015年第19期1680-1687,共8页
The smart fatigue load control of a large-scale wind turbine blade subject to wake effect was numerically investigated in this paper. The performances were evaluated and compared at selected typical wind speeds within... The smart fatigue load control of a large-scale wind turbine blade subject to wake effect was numerically investigated in this paper. The performances were evaluated and compared at selected typical wind speeds within the whole operational region under three turbine layout strategies, i.e., column, row and array arrangements, together with a single turbine case as reference, utilizing our newly developed aero-servo-elastic platform. It was observed that not only the blade fatigue loads but the stabilities of power and collective pitch angle were effectively controlled for all cases, especially at the highest studied hub velocity of20 m/s, leading to the averaged reduction percentages in the standard deviations of the flapwise root moment, the flapwise tip deflection and the root damage equivalent load, of about 30.0 %, 20.0 % and 20.0 %, respectively. Furthermore, the control effectiveness gradually lessened in the sequences of single, column, row and array cases, with successively increasing effective turbulence intensity,within regions II and III. The performances in region III,associated with the impaired flow separation on the blade by the effective pitching action, were much better than those in region II, related to enhanced flow detachment. In addition,at the rated wind velocity, the control for the array case was superior over other three cases, which was thought to be originated from the more pitch activities to impair the uncontrolled flow separation on the blade surface. 展开更多
关键词 Smart rotor control Offshore wind energy Fatigue load Wake effect Turbine layout strategy
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