共查询到20条相似文献,搜索用时 78 毫秒
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元搜索引擎中基于用户兴趣的查询结果合成研究 总被引:3,自引:2,他引:1
元搜索引擎综合了多个搜索引擎的搜索结果,提高了搜索的覆盖率,但是它们返回的结果往往数目庞大,并且很多结果与用户查询并不相关,这直接影响了用户检索的质量,也大大提高了用户检索的代价。针对这一问题。文章提出了基于用户兴趣的结果合成算法。它根据用户兴趣对结果进行相似度计算和结果去重,从而为用户提供贴切的查询结果。实验表明。该算法提高了用户的检索效率和质量。 相似文献
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使用几何绕射理论,提出数值仿真机载天线隔离值的方法,作为算例,给出了某机载设备任务系统中收姨天线之间隔离值的计算结果,人微言轻验证,同时给出了实际测试结果,两种结果的对比表明,仿真模拟结果与实际测试结果的吻合程序基本令人满意。 相似文献
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使用几何绕射理论,提出数值仿真机载天线隔离值的方法,作为算例,给出了某机载设备任务系统中收发天线之间隔离值的计算结果,作为验证,同时给出了实际测试结果。两种结果的对比表明,仿真模拟结果与实际测试结果的吻合程序基本令人满意。 相似文献
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本文在对发射极开关晶闸管EST正向特性二维数值分析的基础上,提出了EST正向工作时的五个区域,从剖面图及等效电路图出发,分区、分阶段对其正向特性进行了解析分析,最后将实验结果、解析分析结果及数值分析结果进行比较,发现数值分析结果和解析分析结果吻合较好,同时说明了解析结果和实验结果之间存在差别的原因。 相似文献
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底馈矩形,圆形微带贴片天线的谐振频率和输入阻抗的CAD模型 总被引:1,自引:0,他引:1
本文以微带贴片天线的腔模理论为基础,建立了底馈矩形,圆形贴片天线谐振频率和输入阻抗的CAD模型,并将所得的结果同有关文献的实测和理论结果进行了比较,结果表明,我们的计算结果与实测结果吻合得较好。 相似文献
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分析了单端输入非线性光波导耦合器的稳定性,给出了非线性耦合波方程的近似解析解,用近似解析解计算的结果与严格解的结果以及A.T.Pham等的近似结果进行了比较,数值分析表明本文的结果比A.T.Pham等的结果更接近严格解,还分析了非线性光波导耦合器的调制特性和自开关效应 相似文献
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分析了毫米波虚阴极振荡器锁相同题,从经典理论出发,给出了主从锁相和互耦振荡器等同锁相满足的方程及数值计算结果,并进行了分析与讨论,其数值计算结果与理论分析结果相当吻合. 相似文献
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米波雷达副瓣对消系统的设计 总被引:2,自引:1,他引:1
从雷达总体设计的角度,介绍了米波雷达副瓣对消技术在工程设计中的要点和注意事项,并根据所用的具体处理方法,进行了计算机仿真和试验,给出了仿真结果和试验结果,进行了比较。 相似文献
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离子波纹场纵向电场分量对离子波纹激光的影响 总被引:2,自引:0,他引:2
通过非线性数值模拟,研究了离子波纹激光(IRL)中离子波纹场的纵向电场分量对束-波互作用的影响。结果表明,离子波纹场的纵向分量对IRL的工作状况具有较大的影响。其中互作用长度的选择是非常重要的 相似文献
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赵建恒 《电子工业专用设备》2013,(5):58-61
介绍了离子束加工技术在半导体工艺中的应用以及离子束刻蚀机的真空和控制系统、Veeco直流栅极离子源及其电源MPS-5001的结构和工作原理、PBN中和器的原理和作用。介绍了离子源电源参数的调整技巧及需要注意的问题,在此基础上给出了离子源常见故障现象的原因及解决办法。 相似文献
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利用场致发射显微分析综合系统(FEM-FIM-IAPCombinationSystem) ̄[1]进行场致负离子发射方面的研究,探索出场致发射获取负离子及其负离子谱的方法和条件,并对不同实验条件所获得负离子谱进行了分析,总结出场致发射负离子谱的一些基本特点和规律。 相似文献
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The typical noble gas ion laser plasma consists of a high-current-density glow discharge in a noble gas, in the presence of a magnetic field. Typical CW plasma conditions are current densities of 100 to 2000 A/cm2, tube diameters of 1 to 10 mm, filling pressures of 0.1 to 1.0 torr, and an axial magnetic field of the order of 1000 G. Under these conditions the typical fractional ionization is about 2 percent and the electron temperature between 2 and 4 eV. Pulsed ion lasers typically use higher current densities and lower operating pressures. This paper discusses the properties of ion laser plasmas, in terms of both their external discharge parameters and their internal ion and excited state densities. The effect these properties have on laser operation is explained. Many interesting plasma effects, which are important in ion lasers, are given attention. Among these are discharge nonuniformity near tube constrictions, extremely high ion radial drift velocities, wall losses intermediate between ambipolar diffusion and free fall, gas pumping effects, and radiation trapping. The current status of ion laser technology is briefly reviewed. 相似文献
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Russian Microelectronics - A historical overview of the development of domestic ion beam technology is presented. It is shown that the wide application of the ion beam technology is facilitated by... 相似文献
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Recent experiments with positive-ion beams suggest that an ion?electron beam, consisting of an electron beam superimposed on an ion beam, such that the two beams have different drift velocities, is realisable. A five-frequency parametric amplifier using an ion?electron beam is proposed. 相似文献
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Advanced 3D carbon-based electrodes have the potential to significantly enhance the energy-power density of lithium ion batteries and sodium ion batteries, due to their continuous conductive networks, proper porosity distribution, and integrated stable structure. However, it still remains a fundamental scientific challenge to accurately understand the charge/ion transport in 3D carbon-based electrodes. In this review, the operating mechanism of charge/ion transport in 3D carbon-based electrodes are comprehended by introducing a useful architectural analogy to provide a physical insight. In order to better understand the relationship between 3D carbon-based electrode structure and electrode process characteristics, the main design strategies of 3D carbonbased electrodes according to the specific characteristic of pore tortuosity is proposed. Through analysis of 3D carbon electrode architectural models, several key scientific issues and related characterization technologies that are beneficial to improving the charge/ion transport efficiency are also raised. The kinetics difference of ionic transport between Li+ and Na+ ions is also taken into account. Furthermore, the critical parameters of porous structure including porosity and tortuosity to investigate the parameter-structure-performance relationships of 3D carbon-based architecture electrodes are highlighted, which in turn would guide more rational battery design in tradeoff between the high capacity and fast transport. 相似文献