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本文对矩形波导内金属电容棒和电容膜片进行了矩量法分析。在分析中,未对电容棒和电容膜片的数量、截面形状及相对位置排列做任何限制,因而这一理论方法及相应的计算机软件可以用来分析广泛类型的电容性波导元件。本文计算了若干电容性波导元件实例,其计算结果与实测结果以及相关文献提供的结果吻合良好。 相似文献
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采用渐近波形估计技术 (AWE)和矩量法相结合的方法 ,计算了TM波入射下表面涂敷有耗介质的导体柱的宽角度单站RCS ,本方法首先采用矩量法求解由电磁场等效原理得到的介质层表面等效电磁流耦合方程 ,得到柱体在某一给定方向入射波照射下的电流和磁流密度 ,然后采用渐近波形估计技术将任意角度入射波照射下的电流和磁流密度在给定的角度附近按Taylor级数展开 ,通过Pad埁逼近将Taylor级数转化为有理函数 ,由此可以得到涂敷导体柱在任意角度TM波入射下的电流和磁流密度 ,进而可以得到柱体的宽角度RCS。此方法得到的结果与由MOM计算的结果完全吻合 ,而AWE的计算效率却提高了一个数量级。 相似文献
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渐近波形估计技术用于介质柱宽角度RCS的计算 总被引:10,自引:7,他引:3
基于渐近波开估计(AWE)技术和矩量法(MOM)快速预测任意形状非均匀介质柱体的单站雷达散射截面RCS方向图,采用矩量法求解介质柱的电场积分方程,得到介质柱在某一给定方向入射波照射下的极化电流,然后利用AWE技术将任一角度入射波照射下的极化给定角度附近展开成Taylor级数,通过Pade逼近将Taylor级数转化为有理函数,由此可获得介质柱在任一角度入射波照射下的极化电流,进而计算出RCS方向图。计算结果表明AWE完全能逼近MOM精确计算的曲线,同时可加快计算速度。 相似文献
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为增强工业级机器视觉系统的实时性和稳定性,本文提出一种基于等积环投影与Zernike矩的具有旋转不变性的快速模板匹配方法,该方法采用由粗到精匹配策略,在粗匹配阶段以等积环投影向量作为特征进行匹配得到候选点集,再基于Zenrike矩进行精确匹配.主要创新点为提出复杂度低、抗噪性强和具有旋转不变性的等积环投影向量特征,并利用圆对称性在八分圆法基础上进一步降低Zernike矩计算量.经理论分析和实验对比验证,此法在保障匹配精度前提下,其匹配速度胜于当前同类最优算法,且对高斯噪声及线性亮度变化有强鲁棒性. 相似文献
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This paper investigates the capacitance-voltage (C-V) measurement on fully silicided (FUSI) gated metal-oxide-semiconductor (MOS) capacitors and the applicability of MOS capacitor models. When the oxide leak-age current of an MOS capacitor is large, two-element parallel or series model cannot be used to obtain its real C-V characteristic, A three-element model simultaneously consisting of parallel conductance and series resistance or a four-element model with further consideration of a series inductance should be used. We employed the three-element and the four-element models with the help of two-frequency technique to measure the Ni FUSI gated MOS capacitors. The results indicate that the capacitance of the MOS capacitors extracted by the three-element model still shows some frequency dispersion, while that extracted by the four-element model is close to the real capacitance, showing little frequency dispersion. The obtained capacitance can be used to calculate the dielectric thickness with quantum effect correction by NCSU C-V program. We also investigated the influence of MOS capacitor's area on the measurement accuracy. The results indicate that the decrease of capacitor area can reduce the dissipation fac-tor and improve the measurement accuracy. As a result, the frequency dispersion of the measured capacitance is significantly reduced, and real C-V characteristic can be obtained directly by the series model. In addition, this pa-per investigates the quasi-static C-V measurement and the photonic high-frequency C-V measurement on Ni FUSI metal gated MOS capacitor with a thin leaky oxide. The results indicate that the large tunneling current through the gate oxide significantly perturbs the accurate measurement of the displacement current, which is essential for the quasi-static C-V measurement. On the other hand, the photonic high-frequency C-V measurement can bypass the leakage problem, and get reliable low-frequency C-V characteristic, which can be used to evaluate whether the full silicidation has completed or not, and to extract the interface trap density of the SiO2/Si interface. 相似文献
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压电材料电荷能量回收技术研究 总被引:1,自引:0,他引:1
对压电材料电荷能量回收性能进行研究。通过在压电驱动器收缩时间回收其在伸展时储存于其电场和应变场中的能量,来提高对驱动压电驱动器动作的激励电源使用效率。借助瞬时电容器(flying capacitor)所构成的一套封闭系统来实现电荷能量回收与利用,通过瞬时电容器与另一电容器串并联连接方式的不断切换,来有效收集封闭系统中压电驱动器上电荷,提高对电源利用率;同时,通过对电容串并联切换时间控制,实现压电驱动器所要求的振动频率。文章最后给出了实验结果。 相似文献
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Hang-Ting Lue Chih-Yi Liu Tseung-Yuen Tseng 《Electron Device Letters, IEEE》2002,23(9):553-555
An improved two-frequency method of capacitance measurement for the high-k gate dielectrics is proposed. The equivalent circuit model of the MOS capacitor including the four parameters of intrinsic capacitance, loss tangent, parasitic series inductance, and series resistance is developed. These parameters can be extracted by independently measuring the capacitor at two different frequencies. This technique is demonstrated for high-k SrTiO3 gate dielectrics and the results show that the calibrated capacitances are invariant over a wide range of frequency. In addition, the extracted loss tangent, inductance and resistance are independent on gate voltage and frequency. The effect of series resistance on the frequency dispersion of the capacitance can be also explained by this model. These results indicate that this modified technique can be incorporated in the routine capacitance-voltage (C-V) measurement procedure providing the physically meaningful data for the high-k gate dielectrics 相似文献
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Use of ESR for deterioration diagnosis of electrolytic capacitor 总被引:2,自引:0,他引:2
A new deterioration diagnosis method for the electrolytic capacitor is proposed for a forward-type converter and a buck-boost converter. It was observed that the ESR (equivalent series resistance) of the electrolytic capacitor increases as it deteriorates, and the knowledge that ripple varies proportionally to the ESR increase was used. With this method, the electrolytic capacitor life-cycle aging rate can be projected for the active circuit over the system life. This approach to deterioration is valid for any load condition, no matter whether the circuit has feedback control or not 相似文献
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串联补偿装电容器能有效降低线路所连接的两端点之间的电抗值,提高最大传输功率和系统运行的稳定性,并降低输电系统工程造价。文中就串联补偿电容器对线路保护装置的影响进行了研究,分析了问题产生的原因,找出了解决问题的方法,并提出了消除串联补偿装电容器影响的具体措施。 相似文献
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《Microwave and Wireless Components Letters, IEEE》2009,19(12):798-800
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It is shown that the thickness of the silicon and oxide layers of a silicon-on-insulator (SOI) structure can be determined from high-frequency capacitance-voltage measurements. The test device consists of a Schottky diode in series with a Si-oxide-Si capacitor. The Si film and the substrate are n-type. The operation of this device is explained for n-type Si with the help of the energy-band diagrams. It is demonstrated that this simple test device can be implemented as a process monitor for silicon thickness control 相似文献
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Multistage amplifiers are urgently needed with the advance in technology, due to the fact that single-stage cascode amplifier is no longer suitable in low-voltage designs. Moreover, the short-channel effects of the sub-micro CMOS transistor cause output-impedance degradation and hence the gain of an amplifier is reduced dramatically[1~6]. For multistage amplifiers, most of the compensation methods are based on pole splitting and pushing the right-half-plane zero to high frequencies or pole-ze… 相似文献
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杨红卫 《电气电子教学学报》2009,31(2)
本文从一个简单电容电路出发,引入所带电量及端点电势构成的状态向量,将电容电路的计算导人了辛体系,以辛矩阵的形式给出了电容多级串联电路以及多支路复杂电容电路的辛传递矩阵解法.辛传递矩阵解法只涉及简单的矩阵计算,为电容电路提供了一个方便的计算方法.将辛数学的方法应用到了电路计算中,将有利于不同学科之间的相互交叉与渗透. 相似文献
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DC-link capacitors are a major factor of degrading reliability of power electric converters because they usually have a shorter lifetime and higher failure rate than those of semiconductor devices or magnetic devices. Characteristics of the capacitors are usually evaluated by a single sinusoidal current waveform. However, actual current flowing out of the converter into the capacitor is a modulated square current waveform. This paper provides experimental comparison of the power loss dissipated in an aluminum electrolytic capacitor between sinusoidal and square-wave current injections. Power loss is estimated by temperature rise of the capacitor. Experimental results confirm that power losses of the square-wave current injection were always lower than those of the sinusoidal current injection by 10–20%. Moreover, the power losses of the square-wave current injection can be estimated by a synthesis of fundamental and harmonic currents based on the Fourier series expansion, which brings a high accuracy less than 1% when more than fifth harmonic current is introduced. This comparison will be useful for estimating power loss and life time of electrolytic capacitors. 相似文献