电力配网系统无功优化方法研究

考虑到常规遗传优化算法进行电力配网系统的无功优化时,算法的早熟问题以及局部寻找最优解能力欠缺造成了优化结果收敛速度和收敛精度较低等问题,该文将自适应对偶种群、自适应终止条件以及全新的子代生成条件引入以形成一种改进型遗传优化算法,在种群迭代过程中保证种群的多样性以避免优化算法早熟现象,以及对优化算法的搜索效率进行加快以提高局部寻找最优解能力。通过实验IEEE57和IEEE30节点系统作为测试平台,使用常规遗传优化算法和可控交叉遗传算法(CCGA)与该文研究的改进遗传优化算法进行对比,使用相同的实验条件和实验数据进行测试。结果表明该文研究的改进遗传算法具有最好的优化效果,该算法计算得到的平均网损均低于其他优化算法,收敛精度和收敛速度更高,能够在局部最优解处跳出,距离目标函数的全局最优解更加接近。     

一种用于线性阵列综合的改进遗传算法

为了提高阵列综合收敛速度,实现目标函数局部最优,分析了现有的遗传算法存在的不足,提出了一种应用于线性阵列综合的改进遗传算法。该算法根据现有算法对实数编码搜索能力不强,容易陷于局部最优解的缺陷,提出了能够增强个体寻优范围的搜索方案,以跳出局部最优解,是解决问题的有效途径。仿真结果表明,改进后的算法能够使目标函数迅速跳出局部最优解,收敛速度至少增加了2¹0倍。     

基于遗传算法的BP网络学习算法研究

介绍了遗传算法和标准BP算法及其改进形式,指出遗传算法和BP算法各自的优缺点.利用遗传算法全局寻优和BP神经网络局部寻优相结合的方法,提高了传统BP神经网络的计算精度和收敛速度.最后进行了仿真实验,结果表明,该方法不仅收敛速度快,而且易达到最优解,具有很高的实用价值.     

基于改进遗传算法的多无人机任务分配

为解决传统遗传算法在求解多无人机任务分配问题时易陷入局部最优和收敛速度较慢的问题,文中提出一种融合模拟退火思想的改进遗传算法。首先描述多无人机任务分配问题,将其转化为多旅行商问题,并建立数学模型;然后在传统的遗传算法中引入Metropolis准则,对选择、交叉、变异后的子代种群进行优化调整,使算法可以跳出局部最优并快速收敛;最后进行仿真实验,采用TSPLIB数据库对改进算法进行有效性验证,分别求解不同规模的多旅行商问题,对算法的优越性进行验证,求解任务分配算例以验证改进算法解决多无人机任务分配问题的可行性。实验结果表明,改进的遗传算法能跳出局部最优,收敛速度显著提升,在求解多无人机任务分配问题时,寻优效果优于改进前的算法。     

基于特征散度K-means红外图像分割遗传算法

针对红外图像中目标和背景的对比度低,边缘模糊的特点,本文提出了改进的聚类分割算法KFGA。用特征散度的内积范数作为K-means算法的距离测度,改进算法的普适性;针对K-means算法收敛的局部寻优问题,将遗传算法与K-means算法结合实现全局寻优;在种群每一次演化操作后实行一次K-means聚类,加快算法的收敛速度,在全局寻优的过程中嵌入局部寻优加快算法的收敛速度。     

基于改进遗传算法的必经点最短路径算法

提出一种解决经过必经点的最短路径的改进遗传算法。在传统遗传算法的基础上,引入Dijkstra算法进行种群初始化;针对传统遗传算法易收敛于局部最优解,迭代次数多,迭代时间长的缺点,提出了改进的交叉算子和变异算子。应用改进遗传算法进行网络节点计算,表明该算法在计算性能上优于传统遗传算法,也验证了改进遗传算法的先进性,有效性。     

基于遗传交叉因子的蝙蝠算法的改进

蝙蝠算法(BA)是一类新型的搜索全局最优解的随机优化算法,但是标准的蝙蝠算法存在着寻优精度不高、后期收敛速度慢、易陷入局部最优等问题。针对这些问题,提出了一种基于遗传交叉因子的改进的蝙蝠算法(GHBA),从而提高蝙蝠算法的多样性,避免种群个体陷入局部最优,增强算法全局寻优能力。在MATLAB环境下,运用6个标准测试函数进行实验仿真。结果表明,与BA算法相比,该算法(GHBA)的收敛速度及精度均有明显提高。     

基于混沌遗传算法的非均匀应变分布重构研究

针对基本遗传算法在解决实际最优化问题时可能存在的收敛速度慢、易于陷入局部最优解等问题,提出从适应度排序标定和混沌算子嵌入两方面进行算法性能的改进。前者避免了传统适应度值计算方法中较小目标函数值导致的具有过大适应度值的个体对种群进化方向的影响,使得种群始终能够保持恒定的进化压差促进最优解的搜索;后者则增强了遗传算法局部搜索的能力,从而提高了近似最优解向全局最优解转化的可能性。在此基础上,建立了一种基于混沌遗传算法的光纤布拉格光栅(FBG)轴向非均匀应变分布重构方法,仿真算例表明,混沌遗传算法有效改善了非均匀应变分布重构算法的收敛性能,提高了重构的精度。讨论了算法中相关参数的设置对非均匀应变分布重构精度的影响。     

基于改进遗传算法的图像边缘检测

针对经典边缘检测算法在一定程度上的局限性,提出了一种改进的遗传算法进行边缘检测。阐述了图像梯度的幅值和变化率,并将遗传算法引入到图像边缘检测中。利用天牛须搜索算法来引导遗传算法中交叉点位置的移动方向。通过提高子辈种群的多样性,防止了搜索区域逐渐缩小,克服了传统遗传算法早熟收敛的现象。实验结果表明,与传统的边缘检测算法相比,改进的遗传算法应用于不同的图像检测具有良好的稳定性和较快的收敛速度,可以收敛到全局最优解甚至逼近全局最优解,从而提高被检测图像边缘的完整性。     

基于遗传变异蚁群算法的机器人路径规划的改进

针对基本蚁群算法在机器人路径规划问题中容易陷入局部最优的问题,提出了一种改进的蚁群算法,利用遗传算法加入了变异因子使最优路径产生变异,从而降低了蚁群算法陷入局部极小的可能性。同时改善了基本蚁群算法不收敛或收敛速度比较慢的缺点,加快了收敛速度,增加了最优解的多样性。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

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正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its