An Algorithm for Short-Circuit Current Interval in Distribution Networks with Inverter Type Distributed Generation Based on Affine Arithmetic

During faults in a distribution network,the output power of a distributed generation(DG)may be uncertain.Moreover,the output currents of distributed power sources are also affected by the output power,resulting in uncertainties in the calculation of the short-circuit current at the time of a fault.Additionally,the impacts of such uncertainties around short-circuit currents will increase with the increase of distributed power sources.Thus,it is very important to develop a method for calculating the short-circuit current while considering the uncertainties in a distribution network.In this study,an affine arithmetic algorithm for calculating short-circuit current intervals in distribution networks with distributed power sources while considering power fluctuations is presented.The proposed algorithm includes two stages.In the first stage,normal operations are considered to establish a conservative interval affine optimization model of injection currents in distributed power sources.Constrained by the fluctuation range of distributed generation power at the moment of fault occurrence,the model can then be used to solve for the fluctuation range of injected current amplitudes in distributed power sources.The second stage is implemented after a malfunction occurs.In this stage,an affine optimization model is first established.This model is developed to characterizes the short-circuit current interval of a transmission line,and is constrained by the fluctuation range of the injected current amplitude of DG during normal operations.Finally,the range of the short-circuit current amplitudes of distribution network lines after a short-circuit fault occurs is predicted.The algorithm proposed in this article obtains an interval range containing accurate results through interval operation.Compared with traditional point value calculation methods,interval calculation methods can provide more reliable analysis and calculation results.The range of short-circuit current amplitude obtained by this algorithm is slightly larger than those obtained using the Monte Carlo algorithm and the Latin hypercube sampling algorithm.Therefore,the proposed algorithm has good suitability and does not require iterative calculations,resulting in a significant improvement in computational speed compared to the Monte Carlo algorithm and the Latin hypercube sampling algorithm.Furthermore,the proposed algorithm can provide more reliable analysis and calculation results,improving the safety and stability of power systems.

Spatial distribution patterns of anorectal atresia/stenosis in China:Use of two-dimensional graph-theoretical clustering

AIM:To investigate the spatial distribution patterns of anorectal atresia/stenosis in China.METHODS:Data were collected from the Chinese Birth Defects Monitoring Network(CBDMN),a hospital-based congenital malformations registry system.All fetuses more than 28 wk of gestation and neonates up to 7 d of age in hospitals within the monitoring sites of the CBDMN were monitored from 2001 to 2005.Two-dimensional graph-theoretical clustering was used to divide monitoring sites of the CBDMN into different clusters according to the average incidences of anorectal atresia/stenosis in the different monitoring sites.RESULTS:The overall average incidence of anorectal atresia/stenosis in China was 3.17 per 10000 from 2001 to 2005.The areas with the highest average incidences of anorectal atresia/stenosis were almost always focused in Eastern China.The monitoring sites were grouped into 6 clusters of areas.Cluster 1 comprised the monitoring sites in Heilongjiang Province,Jilin Province,and Liaoning Province;Cluster 2 was composed of those in Fujian Province,Guangdong Province,Hainan Province,Guangxi Zhuang Autonomous Region,south Hunan Province,and south Jiangxi Province;Cluster 3 consisted of those in Beijing Municipal City,Tianjin Municipal City,Hebei Province,Shandong Province,north Jiangsu Province,and north Anhui Province;Cluster 4 was made up of those in Zhejiang Province,Shanghai Municipal City,south Anhui Province,south Jiangsu Province,north Hunan Province,north Jiangxi Province,Hubei Province,Henan Province,Shanxi Province and Inner Mongolia Autonomous Region;Cluster 5 consisted of those in Ningxia Hui Autonomous Region,Gansu Province and Qinghai Province;and Cluster 6 included those in Shaanxi Province,Sichuan Province,Chongqing Municipal City,Yunnan Province,Guizhou Province,Xinjiang Uygur Autonomous Province and Tibet Autonomous Region.CONCLUSION:The fi ndings in this research allow the display of the spatial distribution patterns of anorectal atresia/stenosis in China.These will have important guiding significance for further analysis of relevant environmental factors regarding anorectal atresia/ stenosis and for achieving regional monitoring for anorectal atresia/stenosis.

Observation of the Two-Dimensional Distribution of Impurity Line Emissions Using a Space-Resolved EUV Spectrometer in LHD

A space-resolved EUV spectrometer for measuring the one-dimensional distribution of impurity line emissions in Large Helical Device （LHD） has been upgraded to measure two- dimensional distributions of impurity line emissions with an extension of working wavelength range to 30-650% The two-dimensional measurement is performed by scanning the observation chord horizontally. A rectangular plasma region of 520 × 700 mm2 in vertical and horizontal sizes can be observed during a single horizontal scan. The horizontal scan requires a time duration of 5 s at least. The spatial resolution is 10 mm in the vertical direction when a spatial-resolution slit of 0.2 mm in width is adopted. Although a spatial resolution in the toroidal direction is 75 mm, it is a function of CCD exposure time and horizontal scanning speed. Two-dimensional distribution of EUV line emissions from several impurities has been successfully observed for the first time from steady discharges in LHD. In this paper two-dimensional distributions of He II （303.78A）, C V （40.27A）, C VI （33.73A） and Fe XX （132.85A） located at different radial positions are presented with simple analysis on the magnetic field structure of LHD.

A Two-Dimensional Brightness Distribution of the Visible Zodiacal Light

By adopting a recently developed semi empirical methodology for removing the atmospheric diffuse light and an improved technique of individual star subtraction, we have newly reduced the distribution of the visible zodiacal light (ZL) brightness from almucantar scan observations of the night sky brightness at Mt. Haleakala, Hawaii. The resulting two dimensional map of the ZL brightness covers the sky over 40°≤λ-λ ⊙≤320° and -40°≤β≤40° and its angular resolution 2°×2°is fine enough to reveal optical counterparts of the structures in the zodiacal emission first found from the IRAS space observations.

Two-Dimensional Self-Consistent Kinetic Model for Solenoidal Inductively Coupled Plasma

A two-dimensional self-consistent kinetic model was developed to study the influence of the various factors on the electron energy distribution function. These factors include gas pressure the driving frequency, the radius and length of the inductively coupled plasma equipment, the amplitude of the radio-frequency coil current, and the number of turns of rf coils. The spatial profiles of the rf electric field and power density have also been calculated under the same parameters. Numerical results show that the electron energy distribution functions are significantly modified and the spatial profiles of the rf electric field and rf power density are also demonstrated.

Ionic Liquid Assisted Imprint for Efficient and Stable Quasi-2D Perovskite Solar Cells with Controlled Phase Distribution

Although two-dimensional perovskite devices are highly stable,they also lead to a number of challenges.For instance,the introduction of large organic amines makes crystallization process complicated,causing problems such as generally small grain size and blocked charge transfer.In this work,imprint assisted with methylamine acetate were used to improve the morphology of the film,optimize the internal phase distribution,and enhance the charge transfer of the perovskite film.Specifically,imprint promoted the dispersion of spacer cations in the recrystallization process with the assistance of methylamine acetate,thus inhibited the formation of low-n phase induced by the aggregation of spacer cations and facilitated the formation of 3D-like phase.In this case,the corresponding quasi-2D perovskite solar cells delivered improved efficiency and exhibited superior stability.Our work provides an effective strategy to obtain uniform phase distribution for quasi-2D perovskite.

一种引入过渡阶段和高斯变异的改进算术优化算法

针对算术优化算法收敛精度低、易陷入局部最优等问题,提出了一种改进的过渡高斯算术优化算法,该算法将新的非线性过渡阶段与改进的高斯变异策略相结合.首先,为了更好地从勘探阶段的高离散度策略过渡到开发阶段的低离散度策略,提出过渡阶段策略,并通过比较三种曲线实验重构数学优化加速函数.其次,引入具有算术优化算法特性的高斯变异策略和边界函数策略,加强算法跳出局部区域的能力.最后,将改进后的算术优化算法与几种著名算法进行对比,并进行不同维度的可扩展性分析,验证了所提算法的有效性.此外,该算法在压力容器设计问题中进行了测试.实验结果表明,TGAOA具有优异的收敛精度、收敛速度和鲁棒性.

Multicellular tumor spheroids bridge the gap between two-dimensional cancer cells and solid tumors: The role of lipid metabolism and distribution

Previous studies demonstrated that three-dimensional(3D) multicellular tumor spheroids(MCTS) could more closely mimic solid tumors than two-dimensional(2D) cancer cells in terms of the spatial structure, extracellular matrix-cell interaction, and gene expression pattern. However, no study has been reported on the differences in lipid metabolism and distribution among 2D cancer cells, MCTS, and solid tumors. Here, we used Hep G2 liver cancer cell lines to establish these three cancer models. The variations of lipid profiles and spatial distribution among them were explored by using mass spectrometry-based lipidomics and matrix-assisted laser desorption/ionization mass spectrometry imaging(MSI). The results revealed that MCTS, relative to 2D cells, had more shared lipid species with solid tumors. Furthermore,MCTS contained more comparable characteristics than 2D cells to solid tumors with respect to the relative abundance of most lipid classes and mass spectra patterns. MSI data showed that 46 of 71 lipids had similar spatial distribution between solid tumors and MCTS, while lipids in 2D cells had no specific spatial distribution. Interestingly, most of detected lipid species in sphingolipids and glycerolipids preferred locating in the necrotic region to the proliferative region of solid tumors and MCTS. Taken together, our study provides the evidence of lipid metabolism and distribution demonstrating that MCTS are a more suitable in vitro model to mimic solid tumors, which may offer insights into tumor metabolism and microenvironment.

结合改进算术优化算法与小波神经网络的网络流量预测模型

网络流量具有非线性、复杂性特征,传统方法预测精度较低。为此,提出结合改进算术优化算法IAOA与小波神经网络WNN的网络流量预测模型。利用IAOA算法对小波神经网络关键参数初值调优,有效解决常规调参易陷入局部最优的缺陷,提高学习精度和收敛速度。对标准算术优化算法进行改进,设计拉丁超立方抽样法进行种群初始化,提高种群多样性;利用余弦函数对AOA的数学优化器非线性更新,均衡算法全局搜索与局部开发;引入针对最优解的高斯变异机制,避免算法陷入局部最优。利用十个基准函数对IAOA算法进行数值仿真,证实算法能够提高搜索精度和收敛速度。而网络流量预测实验结果表明,提出的预测模型具有更高的精确度,预测性能更加稳定,能够满足网络流量预测的高精度和实时性要求。

基于免疫粒子群算法的新能源配电网无功优化

配电网中风力发电机组以及光伏系统等新能源电力系统的介入,易导致其受到不稳定性影响。针对这一问题,提出以免疫粒子群算法为基础的配电网协同电压控制系统。通过梯形模糊数对分布式电源当中具有不确定性的变量进行保证,对相应无功优化模型进行搭建;通过无功补偿以及分布式电源对无功功率进行协同优化,建立相应的目标函数以及约束条件,结合免疫粒子群算法进行求解。算例以IEEE-33节点系统为依据,经过算例验证,该办法能够更好对新能源配电网进行无功调节,保证其稳定运行。

Influence of the channel electric field distribution on the polarization Coulomb field scattering in In_(0.18) Al_(0.82) N/AlN/GaN heterostructure field-effect transistors

By making use of the quasi-two-dimensional （quasi-2D） model, the current-voltage （l-V） characteristics of In0AsA10.82N/A1N/GaN heterostructure field-effect transistors （HFETs） with different gate lengths are simulated based on the measured capacitance-voltage （C-V） characteristics and I-V characteristics. By analyzing the variation of the electron mobility for the two-dimensional electron gas （2DEG） with electric field, it is found that the different polarization charge distributions generated by the different channel electric field distributions can result in different polarization Coulomb field scatterings. The difference between the electron mobilities primarily caused by the polarization Coulomb field scatterings can reach up to 1522.9 cm2/V.s for the prepared In0.38AI0.82N/A1N/GaN HFETs. In addition, when the 2DEG sheet density is modulated by the drain-source bias, the electron mobility presents a peak with the variation of the 2DEG sheet density, the gate length is smaller, and the 2DEG sheet density corresponding to the peak point is higher.

基于算术平均融合的分布式多伯努利扩展目标跟踪

在分布式传感网络中,由于同一扩展目标的方位角以及轴长等状态参数在不同传感器下估计结果不一致,因此多扩展目标估计关联困难,从而为后续密度信息融合带来了巨大挑战。相比于点目标后验密度信息,扩展目标后验密度同时包含了质心状态和外形信息。该文结合质心欧氏距离和外形矩阵非欧氏尺寸-形状度量提出了椭圆距离(ED),该椭圆距离同时考虑了扩展目标质心状态与外形信息,更好地实现了不同传感器下同一扩展目标后验密度关联。此外该文在算术平均(AA)融合规则下推导了融合空间密度的近似伽马高斯逆威沙特(GGIW)分布,实现了不同传感器下同一扩展目标后验信息AA融合。仿真实验表明,该文所提算法在分布式传感网络中能有效地进行多扩展目标跟踪。

多策略混合改进的海洋捕食者算法及其工程应用

为解决海洋捕食者算法(MPA)自适应能力有限、易陷入局部最优等问题,提出融合多策略改进的海洋捕食者算法(EMPA)。首先,在种群初始化阶段,采用精英反向学习策略初始化猎物种群,丰富种群的多样性。其次,在阶段更新过程中,设计出具有更强非线性收敛性的自适应惯性权重,控制捕食者在整个过程中的位置更新。在此基础之上,在等速比阶段,引入算术优化算子指导猎物搜索空间,平衡种群的全局勘探和局部开采。进一步,在海洋记忆存储阶段,采用t分布变异策略对猎物位置进行变异,增强个体在迭代后期跳出局部最优的能力。通过在8个测试函数上的算法性能测试及与著名算法的比较,验证了EMPA算法的优越性。最后,针对传统方法设计的断路器储能弹簧结构参数设置不合理、分断性能差等缺陷,应用EMPA对断路器储能弹簧进行优化设计,实验结果表明,EMPA算法的设计结果更加小型化、分断性能更优。

等差分布微槽平行滑动轴承油膜承载力分析

为提升平行滑动轴承的油膜承载力,在平行滑动轴承上加工了间距为等差数列的槽织构,并建立轴承的油膜模型;基于入口吸入理论和连续性方程,对轴承的油膜承载力进行解析计算。解析解表明,在各个槽都空化的前提下,与均匀分布的槽织构相比,槽间距为等差分布的槽织构能提升油膜承载力,且油膜承载力随织构等差分布的公差的增大呈抛物线形式增大。基于Fluent多相流空化模型,计算了带有等差分布微槽轴承的油膜承载力,并结合解析计算和数值计算结果分析不同因素对油膜承载力的影响。结果表明:在满足空化条件时,解析计算与数值计算结果均显示出相同规律,验证了解析计算的正确性;与均布槽织构比较,在不同压差下,等差分布槽织构最大使油膜承载力提升了32.57%,在不同槽深时,等差分布槽织构最大使油膜承载力提升了24.43%,在不同油膜厚度下,等差分布槽织构最大使油膜承载力提升了27.51%。

面向分布式组网无人机集群的感知数据融合方法

为解决由于全局知识缺失、通信限制、各无人机局部感知信息相关性未知等导致的分布式组网无人机集群中的感知数据融合难的问题,开展了面向分布式组网无人机集群的感知数据融合技术的研究。首先,采用标签随机有限集对各无人机局部感知信息进行建模。其次,分别使用算术平均和一致性作为分布式融合的准则和计算方法,提出了一种基于一致性、算术平均和标签随机有限集理论的分布式数据融合算法,以在分布式组网无人机集群中实现对全局感知信息的集体认同。最终仿真实验表明,所提算法可实现对全局感知信息的分布式融合。

基于算术优化算法的低压配电网故障区段定位方法

为了提高低压配电网故障区段定位的准确性和快速性,保证居民用电安全,文中提出一种基于算术优化算法实现故障区段定位的方法。算术优化算法具有结构简单、收敛速度快以及精确度高等优点。选取IEEE33节点的配电网模型,使用MATLAB对此模型节点支路、节点开关状态和适应度函数进行编程仿真。对单点故障和多点故障以及存在信号畸变的单多点故障进行仿真计算,并对仿真结果进行分析。结果表明,利用算术优化算法的局部搜索和全局搜索分开进行的特点对故障区段定位问题进行局部充分搜索,可实现准确定位,准确度达到97%,优于二进制粒子群算法、遗传算法和改进鲸鱼优化算法。

Two-dimensional extreme distribution for estimating mechanism reliability under large variance

The effective estimation of the operational reliability of mechanism is a significant challenge in engineering practices,especially when the variance of uncertain factors becomes large.Addressing this challenge,a novel mechanism reliability method via a two-dimensional extreme distribution is investigated in the paper.The time-variant reliability problem for the mechanism is first transformed to the time-invariant system reliability problem by constructing the two-dimensional extreme distribution.The joint probability density functions(JPDFs),including random expansion points and extreme motion errors,are then obtained by combining the kernel density estimation(KDE)method and the copula function.Finally,a multidimensional integration is performed to calculate the system time-invariant reliability.Two cases are investigated to demonstrate the effectiveness of the presented method.

物流配送点选址模型及其算法研究

首先介绍以最低送货运输费用为目标 ,借助最小二乘法推导出单物流配送点的选址模型及其迭代算法 ;在此基础上重点分析了已知物流配送点数目条件下的选址和物流服务分配问题 ,提出用二进制数的矩阵来描述物流服务分配方案 ,推导出其选址的数学模型 ,并给出交替选址迭代算法 ;

基于分布式算法的数字滤波器设计

本文对基于分布式算法的FIR数字滤波器设计进行了研究,在完成了以FPGA和单片机为核心的硬件设计的基础上,将分布式FIR算法应用于FIR滤波器设计,实现了16阶FIR滤波器的设计和调试,并对算法进行优化使其能够设计更高阶次的滤波器。由于FIR滤波器所具有的种种优点,在实际电路中被广泛运用。本文将分布式算法引入到滤波器设计中,实现了高阶滤波器的设计。实验结果表明,所设计的硬件具有程序下载方便、便于扩展、通用性强等特点;分布式算法极大地减少了对FPGA资源的占用、有效提高了FPGA内部资源的利用率;滤波器性能指标满足设计要求。

基于DOAS技术的气溶胶粒谱分布反演方法研究

大气气溶胶不仅对全球的气候变化产生重大影响,其本身也是一种污染物,另外它在许多污染气体的化学反应中起重要作用。因此,实时监测大气气溶胶已成为环境领域的重要研究方向。差分吸收光谱技术是一种基于痕量气体"指纹"特性反演其浓度的光学遥感方法,同时该方法也可用于大气气溶胶消光系数的测量。文章介绍了利用闪烁差分吸收光谱系统监测大气气溶胶粒谱分布的方法,重点阐述了基于蒙特卡罗方法的粒谱分布反演算法,监测结果通过与PM10、能见度及Angstrom波长指数的对比证实了该方法的可行性,为近地面大气气溶胶监测提供了新的手段,同时也扩展了差分吸收光谱技术的应用范围,该方法对大气化学的研究有着重要的意义。