Magnetic Field Curves and Magnetic Equipotential Surfaces around Crossing Electrical Wires Replacing Classical Magnetic Field Lines

This article is based on a recent model specifically defining magnetic field values around electrical wires. With this model, calculations of field around parallel wires were obtained. Now, this model is extended with the new concept of magnetic equipotential surface to magnetic field curves around crossing wires. Cases of single, double, and triple wires are described. Subsequent article will be conducted for more general scenarios where wires are neither infinite nor parallel.

On-line Estimation of Biomass in Fermentation Process Using Support Vector Machine

Biomass is a key factor in fermentation process, directly influencing the performance of the fermenta- tion system as well as the quality and yield of the targeted product. Therefore, the on-line estimation of biomass is indispensable. The soft-sensor based on support vector machine (SVM) for an on-line biomass estimation was ana- lyzed in detail, and the improved SVM called the weighted least squares support vector machine was presented to follow the dynamic feature of fermentation process. The model based on the modified SVM was developed and demonstrated using simulation experiments.

A Fingerprint Minutiae Matching Method Based on Line Segment Vector

Minutiae-based fingerprint matching is the most commonly used in an automatic fingerprint identification system. In this paper, we propose a minutia matching method based on line segment vector. This method uses all the detected minutiae （the ridge ending and the ridge bifurcation） in a fingerprint image to create a set of new vectors （line segment vector）. Using these vectors, we can determine a truer reference point more efficiently. In addition, this new minutiae vector can also increase the accuracy of the minutiae matching. By experiment on the public domain collections of fingerprint images fvc2004 DID set A and DB4 set A, the result shows that our algorithm can obtain an improved verification performance.

Application of the sun line-of-sight vector in the optimal attitude estimation of deep-space probe

This paper proposed an optimal algorithm using the sun line-of-sight vector to improve the probe attitude estimation accuracy in deep-space mission.Firstly,the elaborate analysis of the attitude estimation error from vector observations was done to demonstrate that the geometric relation between the reference vectors is an important factor which influences the accuracy of attitude estimation.Then,with introduction of the sun line-of-sight vector,the attitude quaternion obtained from the star-sensor was converted into a pair of mutually perpendicular reference vectors perpendicular to the sun vector.The normalized weights were calculated according to the accuracy of the sensors.Furthermore,the optimal attitude estimation in the least squares sense was achieved with the quaternion estimation method.Finally,the results of simulation demonstrated the validity of the proposed optimal algorithm based on the practical data of the Deep Impact mission.

On-line Chatter Detection Using an Improved Support Vector Machine

On-line chatter detection can avoid unstable cutting through monitoring the machining process.In order to identify chatter in a timely manner,an improved Support Vector Machine(SVM)is developed in this paper,based on extracted features.In the SVM model,the penalty factor(e)and the core parameter(g)have important influence on the classification,more than from Kernel Functions(KFs).Hence,first the classification results are conducted using different KFs.Then two methods are presented for exploring the best parameters.The chatter identification results show that the Genetic Algorithm(GA)approach is more suitable for deciding the parameters than the Grid Explore(GE)approach.

基于GS-SVR的架空输电线路工程投资估算预测研究

传统的投资估算编制模式存在过度依赖定额的现象,随着大量工程造价数据的积累,利用其实现投资估算,以弥补传统定额计价模式的不足,能够对建设项目工程造价起到总体控制作用。文章以架空输电线路工程为例,基于支持向量回归机(Support Vector Regression,SVR)研究架空输电线路工程投资估算问题。结果表明:通过选取影响架空输电线路工程投资估算的主要指标,构建基于SVR的架空输电线路工程投资估算模型,并利用改进的网格搜索法(Grid Search,GS)优化模型参数,得到基于GS-SVR的投资估算预测模型;与传统的线性回归和SVR模型相比,GS-SVR模型表现出更为良好的性能。

Construction of a replication-competent hepatitis B virus vector carrying secreted luciferase transgene and establishment of new hepatitis B virus replication and expression cell lines

BACKGROUND Previously,we have successfully constructed replication-competent hepatitis B virus(HBV)vectors by uncoupling the P open reading frame(ORF)from the preC/C ORF to carefully design the transgene insertion site to overcome the compact organization of the HBV genome and maintain HBV replication competence.Consequently,the replication-competent HBV vectors carrying foreign genes,including pCH-BsdR,carrying blasticidin resistance gene(399 bp),and pCH-hrGFP,carrying humanized renilla green fluorescent protein gene(720 bp),were successfully obtained.However,the replication efficiency of the former is higher but it is tedious to use,while that of the latter is poor and cannot be quantified.Hence,we need to search for a new reporter gene that is convenient and quantifiable for further research.AIM To establish a helpful tool for intracellular HBV replication and anti-viral drugs screening studies.METHODS We utilized the replication-competent HBV viral vectors constructed by our laboratory,combined with the secreted luciferase reporter gene,to construct replication-competent HBV vectors expressing the reporter gene secretory Nanoluc Luciferase(SecNluc).HepG2.TA2-7 cells were transfected with this vector to obtain cell lines with stably secreted HBV particles carrying secNluc reporter gene.RESULTS The replication-competent HBV vector carrying the SecNluc reporter gene pCHsNLuc could produce all major viral RNAs and a full set of envelope proteins and achieve high-level secreted luciferase expression.HBV replication intermediates could be produced from this vector.Via transfection with pTRE-sNLuc and selection by hygromycin,we obtained isolated cell clones,named HBV-NLuc-35 cells,which could secrete secNLuc recombinant viruses,and were sensitive to existing anti-HBV drugs.Using differentiated HepaRG cells,it was verified that recombinant HBV possessed infectivity.CONCLUSION Our research demonstrated that a replication-competent HBV vector carrying a secreted luciferase transgene possesses replication and expression ability,and the established HBV replication and expression cell lines could stably secrete viral particles carrying secNluc reporter gene.More importantly,the cell line and the secreted recombinant viral particles could be used to trace HBV replication or infection.

激光点云特征与知识规则协同的车道线提取

实现车道线高效的检测提取是自动驾驶领域中亟待攻克的关键技术之一,众多基于视觉方案的检测算法由于图像数据的特点存在一定局限性,如天气光照影响成像质量、难以兼顾弯道直道等。本文结合三维激光点云优势与道路知识规则提出了一种车道线自动提取算法。首先,通过多次强化道路边界高程差异获取路面点;其次,简化Isodata算法,自适应地得到反射强度滤波阈值;然后采用随机一致性算法检测直线聚类得到候选车道,将候选车道映射成二维矢量并通过类间距约束提取正确车道线;最后,基于相邻关键特征点对的向量拓扑关系一致性实现车道线拓扑重构,得到对应现实世界中意义完整的车道线。算法在车道线达5~6条的情况下,召回率达92.46%,准确率达94.79%,综合评价指标达92.41%,实验结果证明了方法的有效性和可行性。

表达猪流行性腹泻病毒N蛋白Vero细胞系的构建及初步鉴定

【目的】构建表达猪流行性腹泻病毒(PEDV)N蛋白的Vero细胞系,将有助于PEDV的进一步深入研究。【方法】本研究将N基因克隆到慢病毒载体中,构建重组质粒pLenti-CMV-N,利用慢病毒载体包装系统转染293T细胞,包装表达N蛋白的慢病毒颗粒,将慢病毒颗粒转导至Vero细胞,用潮霉素B初步筛选阳性细胞,采用终点稀释法,筛选表达PEDV N蛋白的Vero细胞系,最后进行鉴定。【结果】RT-PCR结果表明构建的细胞系基因组中存在N基因序列,Western blot和IFA试验验证了N蛋白在细胞系中的表达。【结论】本研究成功构建了表达PEDV N蛋白的Vero细胞系。

基于单矢量水听器的水中目标高分辨线谱增强方法

微弱信号检测一直是被动声呐系统远程探测面临的技术挑战。为了解决水下微弱信号条件下,即低信噪比(SNR)情况下,目标线谱检测难点问题,本文基于单矢量水听器信号接收,提出一种水下目标声压振速频域解卷积联合(CPVD)处理方法,可以实现线谱增强以及提高频域分辨率。采用单矢量水听器接收,保证声呐系统体积小,同时利用其具有指向性这一特点,可以抑制噪声,提高信号增益。在此基础上,通过CPVD算法对水中微弱信号进行线谱增强,实现有效检测。本文提出的方法克服了一些增强算法以及功率谱分析算法需要一定的先验知识以及频域线谱分辨率较低的缺点,从仿真分析和海试数据处理结果可以看出:本文所提出的基于单矢量水听器的水下目标线谱增强算法在低SNR条件下提高频率分辨率方面具有优势,为被动声呐系统微弱信号下的线谱检测提供有效算法。

基于声压振速联合处理的稀疏协方差DOA估计

为充分利用矢量水听器中声压振速信息之间的关系来提高DOA估计精度,本文提出了基于声压振速联合处理的稀疏协方差DOA(Direction ofArrival)估计方法。该方法首先利用声压振速之间的相关性,构造阵列协方差矩阵;其次,将空间入射角度集合进行等角度划分,构造超完备冗余字典;然后,在过完备基上寻找阵列协方差矩阵的最稀疏系数,利用系数向量中的非零行所对应的行号得到DOA估计值。将该算法与CBF算法及L1-SVD算法进行对比仿真实验,结果表明,在信号源数分别为3,4,5的情形下,本文所提算法在低信噪比和小快拍数情形时,具有更低的均方根误差,DOA估计性能优势明显。

基于改进灰度重心法的线结构光中心提取算法

针对传统算法无法准确提取线结构光条中曲率变化较大区域中心线的缺陷,提出了一种基于改进灰度重心法的线结构光中心线提取算法。基于阈值法提取感兴趣区域和开闭运算滤除图像中的噪声点,获取质量相对较高的待处理图像;利用灰度重心法提取光条中心点,得到初始坐标并设置一个矩形计算区域,根据最小二乘法计算每个初始点的方向向量和法向量;在设定的矩形区域内计算初始点在其法线方向上的偏移量,得到精确的中心点坐标。实验结果表明:提出的算法能在线结构光中心中曲率变化较大区域精确提取中心线,提取精度均值为0.096 pixels,精度比率为44.2%,平均提取速度为0.082 s。

一种机载LiDAR点云电力线自动化提取和重建方法

针对电力线走廊的机载LiDAR点云,提出了一种电力线自动化提取和重建方法。首先构建规则格网DEM,采用相对高程获得远地面点,分析点云空间分布特征对电力线点云进行粗提取,并利用局部高差的区域生长分割算法进行精细提取;其次,采用最小二乘拟合每个分割单元在xoy平面内的直线,分析该直线与对应高程数据的一阶导数变化趋势,利用密度聚类算法实现电力线的自动分段;最后,依据邻接电力线拟合求交点方式检测悬挂点位置,并采用多项式模型重构每根电力线矢量。实验结果表明,该方法能够自动化检测悬挂点位置,提取准确率高、拟合误差低,具有一定的参考价值。

基于改进U-Net网络的遥感影像农村道路矢量中心线提取及优化

遥感影像中农村道路矢量中心线的准确提取对乡村规划和地理信息数据库建设具有重要意义。针对现有深度学习方法未能充分利用上下文信息,且在下采样过程中易造成图像分辨率下降和局部特征丢失的问题,该文改进U-Net网络模型以提高提取结果的准确性。首先,网络结构设计两次下采样处理,并将上下文两处特征信息用跳跃层连接,使输出的道路细节清晰;其次,为避免样本不均衡导致训练效果不理想,采用交叉熵损失函数与广义骰子损失函数叠加的方式提升训练效果;最后,采用邻域质心投票算法和融合算法对提取的道路进行矢量化和中心线优化,得到高精度的农村道路矢量中心线。试验结果表明:改进方法在复杂场景的农村道路矢量中心线提取中准确率达95.03%,较4种对比算法(U-Net、DC-Net、PA-Net、SM-Net)具有明显优势。

基于计算几何的多波束测线模型

多波束具有测点密度大、精度高、可视化等优点,被广泛应用于海洋测量。根据数学建模赛题给出的案例,在不同的海域条件下,借助计算几何和三角函数定理,建立并推导多波束测深过程中表征覆盖宽度和相邻条带重叠率关系的数学模型。同时,基于向量法提出了一种多波束测线设计优化方法,详细给出了MATLAB求解结果。模型的合理性通过模拟仿真进行检验说明。

基于ICEEMDAN-GWO-SVM的煤矿井下单相接地故障选线

为解决煤矿配电网发生单相接地故障时,难以对故障线路准确识别的问题,提出一种基于改进的自适应噪声完备集合经验模态分解(ICEEMDAN)的灰狼算法优化支持向量机(GWO-SVM)配电网单相接地故障选线方法。采用ICEEMDAN对不同工况下的每一条线路的零序电流进行分解,对各线路分解后的第一个模态分量IMF1求裕度因子、残差量相对能量系数和综合相关系数,然后将求解出的3种特征值组合形成特征向量,最后输入GWO-SVM中进行模式识别。通过Matlab/Simulink搭建包含4条馈线的10 kV配电网仿真模型进行验证。仿真结果表明,该方法不受故障位置、故障初始角、过渡电阻的影响,具有较高的选线准确率。

基于声音特征的隧道衬砌空洞识别方法研究

目前隧道衬砌空洞检测以人工敲击判断为主,检测过程中由于受到检测人员水平、注意力等主观因素影响,检测结果存在较大不确定性,因此有必要研制一种智能化的检测装置实现空洞自动识别。文章开展了衬砌空洞敲击回声智能识别算法研究,通过提取隧道衬砌冲击回波的梅尔倒谱系数(Mel Frequency Cepstral Coefficient,MFCC)作为特征,针对敲击回声脉冲信号长度不一的特点,提出了变帧长MFCC优化算法,并面向小样本条件,建立了支持向量机(Support Vector Machine,SVM)的识别模型。试验结果表明,该模型对衬砌空洞识别准确率可达89.9%。

顾及邻域几何特性的露天矿台阶线提取方法

台阶线数据是露天矿开采过程中的重要基础资料,也是确保露天矿高效、智能开采的重要前提。针对现有的基于点云的露天矿台阶线提取方法存在局部特征丢失、台阶线不连续等问题,将识别台阶线特征点转为识别几何特征面,从特征面轮廓中提取出台阶线特征点,由此提出了一种顾及邻域几何特性的露天矿台阶线自动提取方法。该方法首先对露天矿点云进行规则重采样,依据露天矿台阶平盘、坡面点云法向量与竖直平面夹角具有明显差异这一几何特性提取坡面的特征点云;在此基础上,采用区域生长算法分割坡面点云,通过凹包算法提取分割后的坡面点云轮廓边界获得台阶线特征点;最后利用三阶贝塞尔曲线拟合特征点以生成露天矿台阶线。为验证算法的提取精度,将台阶线与露天矿数字高程模型(Digital Elevation Model,DEM)叠加,并计算该方法提取的台阶线与实际台阶线的位置偏差。结果表明:该方法提取的台阶线完整且连续性好,与手工绘制的台阶线基本重合,能够满足比例尺为1∶2000的制图精度要求;运行效率高,对于面积为3 km2的露天矿,提取时间在4 min以内。证明所提方法能够准确、高效地提取露天矿台阶线,为实现露天矿山台阶线自动绘制提供重要的技术支持。

考虑换相过程的电网换相换流器小信号阻抗建模

建立准确的数学模型对于判断电力系统稳定性具有重要意义,其中阻抗模型凭借简单有效的优势成为判断系统稳定性的常用工具。为完成考虑换相过程的电网换相换流器阻抗建模,在dq坐标系下采用了基于平均化的小信号建模方法。首先,将换相重叠过程中各物理量的非线性变化过程利用小信号法线性化,建立了物理量之间的传递函数;然后,加入了交流电源侧的交流网络简化模型,同时考虑了定电压控制方式和锁相环的建模,得到电网换相换流器直流侧和交流侧的等效阻抗模型;最后,通过对比PSCAD/EMTDC仿真结果和模型计算结果,证明了阻抗模型的准确性。

基于SSA优化SVM的交通标线识别算法研究

针对智能驾驶汽车对交通标线识别率不高的问题,提出一种改进LBP特征和SSA优化SVM的交通标线识别算法.该算法采用改进的LBP算法提取路面交通标线特征,通过PCA降维处理,获得最佳维度;通过对SSA、PSO、WOA和GWO 4种群智算法分析比较,发现采用SSA优化SVM的惩罚系数和核函数参数,获得路面交通标线识别的最优模型.实验结果表明,该模型的平均识别速度分别比PSO、WOA和GWO优化的SVM模型提高了1.0%、6.19%和8.35%,平均识别精度最高,达到96.7%,比优化前提高了4.5%,且模型的最佳参数稳定.