Coplanar Waveguide Using Ferroelectric Thin Oxide Film: Dielectric Constant

Coplanar waveguide (CPW) transmission lines were fabricated on thin ferroelectric Ba_{1 – x}Sr_xTiO₃ films for tunable microwave applications. The growth of the ferroelectric oxide films was accomplished by a pulsed laser deposition with a partial oxygen background. Microwave properties of the CPW phase shifter were measured using a HP 8510C vector network analyzer from 0.045–20 GHz with –40–40 V of dc bias. A large phase shift angle of 120 at 10 GHz was observed from the CPW (gap = 4m, length = 3 mm) with a 40 V of dc bias change. The dielectric constant of the thin ferroelectric film was extracted from the dimension of the CPW (gap, width, length) and the measured S-parameter by a modified conformal mapping. However, the dielectric constant of the ferroelectric thin film exhibits a gap dependency; dielectric constant (990–830) decreases with increasing gap size (4–19 m, respectively). By adjusting the filling factors of the film, a constant dielectric constant of BST film is found to be 810 ± 5.     

Novel Core Structure and Iron‐Loss Modeling for Contactless Power Transfer System of Electric Vehicle

A contactless power transfer system for electric vehicles must have high efficiency, a large air gap, good tolerance to misalignment in the lateral direction, compactness, and light weight. In this paper, a new 1.5‐kW transformer has been developed using a novel H‐shaped core which is more efficient, more robust to misalignment, and lighter than previous rectangular cores, to satisfy these criteria, and its characteristics are described. An efficiency of 95% was achieved across a 70‐mm mechanical gap. Iron‐loss modeling of the equivalent circuit is also presented. The calculated efficiency using this model shows good agreement with experimental results. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(2): 61–70, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22377     

Analytical study of optimal layout of permanent magnet in IPMSM for generating sinusoidal flux‐density distribution in air gap

This paper demonstrates an analytical optimization method for rotor designs of interior permanent magnet synchronous machines with multiple flux‐barriers. In particular, this study focuses on the optimal layout of permanent magnets for generating a sinusoidal flux density distribution in the air gap. In addition, practical design methods for realizing the optimal layout are proposed, and the designs are verified through finite‐element analyses. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(2): 39–46, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22344     

Effects of Temperature Cycling and Elevated Temperature/Humidity on the Thermal Performance of Thermal Interface Materials

Thermal interface materials (TIMs) have become increasingly important in reducing the interfacial thermal resistance between contacting surfaces inside electronic devices, such as at the die–heat-sink or heat-spreader–heat-sink interfaces. While the focus regarding implementing TIMs remains on reducing the thermal resistance path, the long-term performance of the TIM is important from a life-cycle standpoint. This paper presents test and analysis results examining the effect of temperature cycling and elevated temperature/humidity on the thermal performance of filled polymer TIMs using the laser flash method. A three-layer sandwich structure was used to simulate loading conditions encountered by TIMs in actual applications and to assess the change in their thermal resistances. The evaluated thermal resistance included contact and bulk resistances and was calculated using the Lee algorithm, an iterative method that uses the properties of the single layers and the three-layer sandwich structures. Test samples included three thermal putties, a gap filler, an adhesive, a gel, and two gap pads. For most materials, little change or slight improvement in the thermal performance was observed over the course of environmental exposures. Scanning acoustic microscope images revealed delamination in one group of gap pad samples and cracking in the putty samples as a result of temperature cycling. One thermal putty material showed degradation due to temperature cycling resulting from bulk material changes near the glass transition temperature, while other samples showed little change or slight improvement in the thermal performance over the course of temperature cycling.      

Generalized optical gain analysis in nonparabolic semiconductor laser

A simple generalized theory is developed for optical gain of nonparabolic semiconductor lasers based on the three‐band model of Kane, by taking into account the wave‐vector () dependence of the optical matrix element. The gain in laser of nonparabolic semiconductors is demonstrated, by taking InAs, InSb, Hg_1−xCd_xTe and In_1−xGa_xAs_yP_1−y lattice matched to InP as examples, and it has been found that the peak of the gain spectra for a given carrier density is higher in the three‐band model of Kane than those with parabolic energy band approximations in all the cases. The difference between the peak of gain spectra for three‐band model and the parabolic band model is greater for laser of narrow band gap materials in comparisons with that of laser of wide band gap materials, thereby reveals the necessity for inclusion of the nonparabolicity in modeling lasers of small band gap materials. The well‐known results for wide band gap materials having parabolic energy bands has also been obtained from our generalized formulation under certain limiting condition. Copyright © 2013 John Wiley & Sons, Ltd.     

Quantum-Confined Stark Effect in Ge/SiGe Quantum Wells on Si

In this paper, we present observations of quantum confinement and quantum-confined Stark effect electroabsorption in Ge quantum wells with SiGe barriers grown on Si substrates. Though Ge is an indirect gap semiconductor, the resulting effects are at least as clear and strong as seen in typical III–V quantum well structures at similar wavelengths. We also designed and fabricated a coplanar high-speed modulator, and demonstrated modulation at 10 GHz and a 3.125-GHz eye diagram for 30-$mu$m-sized modulators.      

Effect of Grating Parameters on Mode-Locked External Cavity Lasers

This paper deals with numerical solutions of actively mode-locked fiber grating semiconductor lasers using a time-domain solution of coupled wave equations and rate equations. Simulation of linearly chirped tanh apodized fiber Bragg grating (FBG) utilized in hybrid soliton pulse source (HSPS) shows an extreme increase in the mode-locking frequency range of HSPS. Our model predicts transform-limited pulses over a frequency range of 1.6 GHz (1.8–3.4 GHz) for this grating around a system operating frequency of 2.5 GHz, with a pulsewidth of 46 ps required for a practical soliton transmission system, whereas it ranges to about 1.3 GHz (2–3.3 GHz) for the linearly chirped raised-cosine flat top and 850 MHz (2.1–2.95 GHz) for linearly chirped Gaussian apodized. Furthermore, in this study, the effects of FBG parameters, such as peak reflectivity, grating length, grating chirp, and modulation index, on output of mode-locked HSPS are also described for the first time. The numerical results indicated that although pulsewidths decreased with the increase in grating chirp, shorter grating lengths gave shorter pulses, and the modulation index and peak reflectivity of the grating did not significantly affect the pulsewidths.      

Global unique solvability for memristive circuit DAEs of Index 1

Known solvability results for nonlinear index‐1 differential‐algebraic equations (DAEs) are in general local and rely on the Implicit Function Theorem. In this paper, we derive a global result which guarantees unique solvability on a given time interval for a certain class of index‐1 DAEs with certain monotonicity conditions. Based on this result, we show that memristive circuit DAEs arising from the modified nodal analysis are uniquely solvable if they fulfill certain passivity and network topological conditions. Furthermore we present an error estimation for the solution with respect to perturbations on the right‐hand side and in the initial value. Copyright © 2013 John Wiley & Sons, Ltd.     

Three‐dimensional analysis of light transmittance characteristics in many index ellipsoids connected in series

The three‐dimensional optical technique has been applied to analysis of the experimental results related to magnetic wave scattering phenomena. Recently, we have developed an ideal equation for analyzing the three‐dimensional transmittance character of light scattered due to many index ellipsoids. The index ellipsoids are arranged directly along the light axis in series. In this case, the index ellipsoid size and the gap distance between each index ellipsoid and neighbor one are considered as a calculation condition. By using an analysis equation devised by us, we have sought to determine the condition under which the light can be passed through many transparent mediums with high efficiency. From the numerical calculations, the condition for maximum transmittance of light 100% is obtained when a spherical and elliptic index ellipsoids are alternately arranged with respect to each other. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(3): 12–18, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20311     

棒－板长空气间隙在低气压下雷电冲击特性及电压校正

文中在人工气候室内对0.5～2.0m的棒-板空气间隙雷电冲击50%放电电压U50与气压P的关系进行了系统的试验研究,分析了P对雷电冲击U50的影响,得到了U50与间隙距离d之间的关系.研究结果表明0.5～2.0m棒-板空气间隙的U50与P之间满足幂函数关系,其幂指数即气压对U50影响的特征指数n与电压极性有关;当d＜1.0m时,n与d关系较密切,当d＞1.0m时,n与d关系不明显,且U50与d基本呈线性关系.提出了棒-板长空气间隙雷电冲击U50的海拔高度校正方法,并得到海拔每升高1km,正、负极性的U50分别下降8.7%和8.0%.     

Properties of Flammable Gaseous Mixtures Optimized by Corona Tests

There are important applications of discharges occurring in gaseous hydrocarbons. This paper focuses on experimental work on corona discharges aimed at optimizing the electronegative properties of hydrocarbon binary media. Discharges were studied in a needle–plane system with a small electrode gap under controlled pressure, temperature, and homogeneity of the sample. Various highly flammable hydrocarbon mixtures of cyclopentane, 1-pentene, and pentane were analyzed. Experiments show particular patterns of discharges common to the studied hydrocarbons. The concentration of the sample determines the electronegative character of the hydrocarbon mixtures and is reflected in the discharge patterns observed. The results were reproducible on different concentrations of the used mixtures. The present analysis provides data for other studies; the techniques can be employed for engineering the properties of electronegative binary mixtures and for optimizing the characteristics of corona discharges in hydrocarbon media.      

基于背景纹影技术的长空气间隙放电通道温度场测量

长空气间隙放电发展过程中伴随有介质热电离现象,准确获取温度场有助于深度分析间隙放电特性,背景纹影技术突破了传统纹影技术中透镜组镜面尺寸的限制,可获得大尺寸放电通道的温度分布特性。文中搭建了背景纹影测量系统,采集了放电发展过程中的背景斑点图集,利用PIV粒子图像测速技术分析得到了穿过放电通道的光线偏移量;基于Abel逆变换计算得到了光线偏移量对应的折射率,再根据热力学方程和理想气体状态方程定量重构出密度场和温度场,并以酒精灯火焰为参照物进行了温度校验,分析结果与热电偶实测结果基本一致。以1m棒–板空气间隙为研究对象,通过搭建的背景纹影实体测量系统观测间隙正极性放电发展过程,分析了放电通道温度的时空变化规律,结果表明间隙中部横截面温度分布在1 200 K左右,温度场呈轴对称分布且离通道中心越近温度梯度越大,整个通道温度自棒极而下逐渐降低。     

On the asymptotic behavior of the Durbin–Watson statistic for ARX processes in adaptive tracking

A wide literature is available on the asymptotic behavior of the Durbin–Watson statistic for autoregressive models. However, it is impossible to find results on the Durbin–Watson statistic for autoregressive models with adaptive control. Our purpose is to fill the gap by establishing the asymptotic behavior of the Durbin–Watson statistic for ARX models in adaptive tracking. On the one hand, we show the almost sure convergence as well as the asymptotic normality of the least squares estimators of the unknown parameters of the ARX models. On the other hand, we establish the almost sure convergence of the Durbin–Watson statistic and its asymptotic normality. Finally, we propose a bilateral statistical test for residual autocorrelation in adaptive tracking. Copyright © 2013 John Wiley & Sons, Ltd.     

Equivalent circuits for repeater antennas used in wireless power transfer via magnetic resonance coupling

The demand for wireless power transfer via magnetic resonance coupling is increasing. Magnetic resonance coupling is a new technology that achieves power transfers across a large air gap by using transmitting and receiving antennas. However, repeater antennas can enable power transmission across an even larger distance. These repeater antennas without cross coupling can be expressed as a T‐type equivalent circuit. Equivalent circuits that include cross coupling and mutual inductance, which is related to the antenna position, have not been studied. In this paper, a novel way to represent a repeater antenna by an equivalent circuit and a way to determine the mutual inductance are proposed and veri?ed by performing an electromagnetic ?eld analysis and experiment. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(1): 51–62, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22360     

Determination of the optical constants of a semiconductor thin filmemploying the matrix method

In the present work a formalism is developed based on the matrix method for the purpose of obtaining the values of the optical constants (n refractive index and k extinction coefficient) of thin film materials from the experimental reflectance (R) and transmittance (T) spectra. This formalism has been applied to the determination of the dependence on the wavelength (λ) of n and k values in the visible range corresponding to a semiconductor (SnO₂) thin film deposited onto glass. The dependence on λ of the absorption coefficient (α) as well as the value of the energy gap has also been calculated. The nature of the optical transitions has also been ascertained. This technique has been found suitable for use as a student experiment     

基于相关性度量算法的台区线损异常判断及精准定位

针对台区发生线损异常时关联用户辨识困难的实际问题,提出一种基于相关性度量算法的台区线损异常判断及精准定位方法。首先,通过间隙统计-轮廓系数融合算法确定数据集的最佳聚类数,并在此基础上采用二分K-means++构建台区线损标准库;其次,基于标准库完成台区线损异常辨识,确定异常时间段;再次,计算异常时间段内各用户电量和线损的斯皮尔曼相关性系数(SCC)和欧式-离散弗雷歇距离(E-DFD),并基于SCC和E-DFD构造综合评判指标分析用户关联性;最后,采用TOPSIS算法对综合评判指标值进行排序,实现异常关联用户的精准定位。算例采用某台区真实现场数据进行分析,结果表明文中所提方法在聚类有效性、计算时间以及辨识准确度等方面具有较好的性能和优势。     

温湿变化对北京城区气象敏感电力负荷的影响分析

为研究气象条件与近年来北京城区空调用电负荷压力不断增加之间的关系,利用2012年和2013年北京夏季日瞬时最大电力负荷和城区逐日气象资料,并引入反映温湿变化的气象指数,采用统计方法分析了北京城区夏季温湿变化对日瞬时最大电力负荷的影响,发现日瞬时最大电力负荷受温湿指数的影响比平均气温以及考虑了风速的北京舒适度气象指数要更加显著,当温湿指数变化1个单位时,日最大气象敏感负荷将增加或减少38.6万kW。同时,建立了基于温湿变化的日最大气象敏感负荷的计算方程,并进行了应用分级和服务用语编写。     

基于Ansys的短路脱扣器电磁吸力仿真研究

借助三维场分析软件Ansys建立短路脱扣器三维有限元模型,通过分析静态电磁特性,得到了短路脱扣器电磁力与动、静铁心间空气气隙的关系特性。研究仿真脱扣器模型外部的空气体对仿真影响,可为类似Ansys仿真分析提供借鉴,也可对实际产品技术指标提升和产品优化设计提供建议。     

世界一流城市电网评价指标体系

近年来,随着国内城市电网建设的快速发展,亟需建立科学、客观的指标体系来评价电网的运行建设水平与世界一流水平的差距。该文通过借鉴国际电力行业常用指标体系,从安全可靠、经济高效、服务优质、绿色低碳、友好互动等5个方面,筛选了能够表征世界一流电网特质的核心指标,并通过核心指标专业驱动因素的分析,层层分解形成二级指标。实例表明,本文提出的指标体系,能够全面客观地反映电网的发展水平与薄弱之处,引领电网发展的重点与方向。     

35kV配电线路绝缘子串与多断点灭弧防雷间隙雷电冲击绝缘配合研究

多断点灭弧防雷间隙能有效降低35 kV配电线路雷击跳闸率,但目前暂无对多断点灭弧防雷间隙和绝缘子的雷电冲击绝缘配合的研究。因此,对35 kV玻璃、复合绝缘子串及不同间隙距离的多断点灭弧防雷间隙进行雷电冲击特性和伏秒特性的实验研究。实验结果表明：多断点灭弧防雷间隙能够在雷击后有效保护绝缘子;有效相同间隙距离下,多断点灭弧防雷间隙的绝缘水平要高于并联间隙;通过实验给出多断点灭弧防雷间隙的有效保护距离。此结论可为安装多断点灭弧防雷间隙的工程提供参考。