Soller slits automatic focusing method for multi-element fluorescence detector

In X-ray absorption fine structure(XAFS) experiments,Soller slits are widely used as filter devices in order to improve the signal to noise ratio.Performing high accuracy manual focusing operations is a time-consuming process;therefore,this work introduces an automatic focusing method for Soller slits in multi-element fluorescence detectors.This method establishes a relation model between the fluorescence intensity distribution and the coordinates of the fluorescence excitation point.According to this relation model,the actual coordinates of the fluorescence excitation point can be deduced from the detected fluorescence intensity distribution and used in focusing operations.This method has proven to be feasible in an XAFS experiment at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facility.

Formula for calculating spatial similarity degrees between point clouds on multi-scale maps taking map scale change as the only independent variable

The degree of spatial similarity plays an important role in map generalization, yet there has been no quantitative research into it. To fill this gap, this study first defines map scale change and spatial similarity degree/relation in multi-scale map spaces and then proposes a model for calculating the degree of spatial similarity between a point cloud at one scale and its gener- alized counterpart at another scale. After validation, the new model features 16 points with map scale change as the x coordinate and the degree of spatial similarity as the y coordinate. Finally, using an application for curve fitting, the model achieves an empirical formula that can calculate the degree of spatial similarity using map scale change as the sole independent variable, and vice versa. This formula can be used to automate algorithms for point feature generalization and to determine when to terminate them during the generalization.

Fitting method of pseudo-polynomial for solving nonlinear parametric adjustment

The optimal condition and its geometrical characters of the least square adjustment were proposed. Then the relation between the transformed surface and least squares was discussed. Based on the above, a non iterative method, called the fitting method of pseudo polynomial, was derived in detail. The final least squares solution can be determined with sufficient accuracy in a single step and is not attained by moving the initial point in the view of iteration. The accuracy of the solution relys wholly on the frequency of Taylor’s series. The example verifies the correctness and validness of the method. [

A Method of Time-Varying Rayleigh Channel Tracking in MIMO Radio System

A method of MIMO channel tracking based on Kalman filter and MMSE-DFE is proposed. The Kalman filter tracks the time-varying channel by using the MMSE-DFE decision and the MMSE-DFE conducts the next decision by using the channel estimates produced by the Kalman filter. Polynomial fitting is used to bridge the gap between the channel estimates produced by the Kalman filter and those needed for the DFE decision. Computer simulation demonstrates that this method can track the MIMO time-varying channel effectively.

An Efficient Maple Program for Calculating Adomian Polynomials

The immense quest for proficient numerical schemes for the solution of mathematical models featuring nonlinear differential equations led to the realization of the Adomian decomposition method (ADM) in the 80th. Undoubtedly, the solution of nonlinear differential equations using ADM is presided over by the acquisition of Adomian polynomials, which are not always easy to find. Thus, the present study proposes easy-to-implement Maple programs for the computation of Adomian polynomials. In fact, the proposed algorithms performed remarkably on several test functions, consisting of one- and multi-variable nonlinearities. Moreover, the introduced programs are advantageous in terms of simplicity;coupled with the requirement of less computational time in comparison with what is known in the literature.

A CONCISE M-METRIC LEAST SQUARE FORMULA FOR POLYNOMIAL ANALOGY

An M-metric least square method for polynomial analogy is presented. The relative normal eqUation is of diagonal form, such that the concise solution formula is explicit, and it is suitable to Parallel computation. On the other hand, by error analysis of a typical example, we can see that the presented method is reliable.

A Modeling Method for Transformer Windings Under VFTO Based on S-parameters

To study the Very Fast Transient Over-voltage (VFTO) distribution in transformer windings in gas insulated substation (GIS), a systematic methodology based on S-parameters is presented for establishing high-frequency model of transformer windings. Firstly, voltage transfer functions are derived from S-parameters which are calculated or measured from transformer windings. Secondly, voltage transfer functions are fitted with rational functions by the vector fitting method and then the rational transfer functions are order-reduced by optimal Pade-approximation algorithm. Lastly, the resultant voltage transfer functions are synthesized by network technology. Computational results are consistent with simulation results of Electromagnetic Transient Program (EMTP) and confirm the feasibility and validity of proposed methodology.

发泡聚乙烯最大加速度-静应力曲线快速获取方法研究

目的研究快速、准确预测最大加速度-静应力曲线的方法。方法首先利用落锤冲击试验机获取了5个不同高度下,5种不同厚度的发泡聚乙烯的最大加速度-静应力曲线。在此基础上,分析对比文中3种不同的改进拟合法与已有的动应力与动能量多项式拟合法的区别。结果研究发现,当不区分高度的情况下,以最大加速度因子为函数值,以跌落高度、衬垫厚度、静应力为变量进行拟合时,其代表预测精度R^(2)的平均为0.835,相比动应力与动能量多项式拟合法的0.2996要高。但曲线右侧的预测精度偏低。引入以静应力为变量的多项式作为修正因子后,R^(2)的平均值为0.934。预测精度有所提高,右侧的预测偏差减小,但仍存在。在区分高度的情况下,以带有修正因子的公式进行预测时,R^(2)的平均值为0.984,曲线向右侧预测偏差逐渐增大的现象明显改善。结论区分高度情况下,利用带修正因子的预测公式可以快速且较准确地预测最大加速度-静应力曲线,可以为冲击防护设计及相关软件的开发提供一定的帮助。

寒区再生砖骨料混凝土路用性能多目标优化

以5~10 mm、10~20 mm再生砖骨料和水灰比为自变量因子,将抗压强度、耐磨性能和抗冻性能等路用性能作为目标,采用中心复合试验设计,确定混凝土中不同因素的影响程度。对试验结果进行回归拟合,提出因子与混凝土路用性能之间的拟合模型,并利用方差分析验证模型的可靠性和稳定性。利用响应面3D图对模型深入分析,确定因子对再生砖骨料混凝土三项寒区路用性能影响程度,从高到低依次是:水灰比、10~20 mm砖骨料和5~10 mm砖骨料。结合渴求函数优化寒区再生砖骨料混凝土的路用性能,以满足3种寒区路况的要求:最大限度强化抗压强度和抗冻性;最大限度提高耐磨性,同时保持优异的抗压强度和抗冻性;根据权重强化抗冻性。研究结果表明:提出的拟合模型可根据工程目标反向求出最佳配比,优化再生砖骨料混凝土的制备工艺,为实际工程应用提供参考。

改进的压差式水听器侦察声纳角度测量方法

压差式矢量水听器是现有侦察声纳体制之一,但是其角度测量原理假设阵元间隔远小于波长,严重地影响了测角精度,因此需要对压差式矢量水听器的角度测量方法进行改进。提出两种角度测量的改进方法,一是压差矢量幅比反函数多项式拟合方法,通过对压差矢量幅度比与角度函数的反函数多项式逼近,利用压差矢量幅度比估计角度;二是比相测角信息融合方法,利用余弦偶极子和正弦偶极子分别进行比相测角,采用角度的预估值确定融合比,对两个比相结果进行信息融合。仿真结果验证了两种改进方法的有效性。

计及配合间隙的输送链传动机构优化设计方法

为提高输送链传动机构的到位精度,首先对输送链传动机构的传动误差进行了建模与分析,得到链轮-链条配合间隙对最大总传动误差的影响规律,并通过实验验证了模型及分析的正确性;然后,考虑到机构零部件制造加工时尺寸公差及配合间隙的随机性,提出了蒙特卡洛-多参数粒子群优化设计方法,对配合间隙进行了优化设计,并对最大总传动误差进行了预测;最后,通过输送链传动机构的优化设计对所提方法进行了验证。结果表明:采用该方法优化设计后的最大总传动误差相比于优化前减小了28.923%,能够改善输送链传动机构的到位精度,可为其他多间隙传动机构的设计及最大总传动误差预测提供有效方法。

基于UWB与PDR的井下人员融合定位方法

现有超宽带(UWB)与行人航位推算(PDR)融合定位方法大多忽略了非视距(NLOS)环境下的定位误差校正,以简单的阈值划分作为NLOS环境判断依据,而阈值划分在很大程度上与定位场景及场地大小相关。针对上述问题,提出一种考虑NLOS环境的基于UWB与PDR的井下人员融合定位方法。首先,利用UWB技术进行井下人员位置解算,通过三边定位算法得到人员初步位置后,使用最小二乘法对位置进行优化,通过多项式拟合实现NLOS环境下基站和标签之间实际值和测量值之间的拟合,减小NLOS环境下的测距误差,提高定位精度。其次,采用PDR算法对步态进行识别和分析,PDR算法使用惯性导航传感器采集的步态数据,通过步态识别、步长估计和方向估计,实现目标位置的更新;然后,通过卷积神经网络(CNN)-长短期记忆(LSTM)网络分析信道脉冲响应(CIR)特征,实现视距(LOS)/NLOS识别,解决NLOS环境判断存在场景限制的问题;最后,根据LOS/NLOS识别结果确定融合系数,实现UWB和PDR定位结果融合。测试结果表明:多项式拟合后UWB平均测距误差降低0.59 m;LOS/NLOS识别的平均准确率为95.3%,召回率和F1分数均在90%以上,验证了CNNLSTM具有较好的识别效果;融合定位方法的平均误差为0.31 m,较UWB降低1.57 m,较PDR降低1.41 m。

基于趋势外推法的分布式光纤测温系统的温度预测

分布式测温传感器被广泛运用于温度监测。本文以此为背景,提出了一种具有温度监测和温度预测功能的分布式光纤系统。在实现温度监测的同时,建立了一种基于机器学习的趋势外推模型,通过不断更新的历史数据来预测未来温度。实验模拟了一般火灾的温度变化并进行预测。结果表明,当采样时间为5 s,预测1 min后的温度时,预测误差最大值为2.88℃,均方误差为0.958℃,说明模型准确度较高,对工程实践具有一定的参考价值。

基于贝叶斯算法优化的多阈值图像分割仿真

在多阈值图像分割过程中,若分割精度较低,会直接影响图像的分割效果。为提升图像的分割精度,提出基于贝叶斯算法优化的多阈值图像分割方法。通过确定贝叶斯算法优化时存在的影响因素,建立对应的适应度函数实时更新算法中种群个体适应度值;利用最小爬山法对算法中的变量展开独立性测试,建立算法的优化框架,利用蚁群算法学习贝叶斯网络结构,寻找算法种群的高阶优良模式,从而实现贝叶斯算法的优化;基于贝叶斯优化算法对图像灰度级的发生概率均值展开计算,获取图像类间方差,确定最佳分割阈值完成多阈值图像的分割处理。实验结果表明,所提方法在图像分割时,概率兰德系数(PRI)值接近1,全局一致性误差指数(GCE)与信息变化指数(VOI)值小,表明所提方法性能高、图像分割效果好。

利用改进的PnMl方法处理GRACE南北条带误差

GRACE无约束月时变重力场球谐系数模型的反演结果存在明显的南北条带误差。为此,提出一种改进方法,通过对PnMl方法未作处理的高阶系数进行分层多项式拟合,以进一步减少条带误差,并分析其在空域、频域和时域的性能。结果表明,相比于PnMl(P4M6)方法,改进方法可进一步减少30°S~30°N区域的残余条带误差,抑制50阶后信号阶方差的异常抬升,减少质量变化时间序列中的异常峰值。此外,采用信噪比指标和广义三角帽方法对改进方法进行定量评估。结果表明,CSR、GFZ、JPL发布的3种重力场模型经改进方法处理后均达到最优信噪比,分别为1.77、1.35和1.39;其结果的不确定性水平较P4M6方法分别降低20.50 mm、36.40 mm和19.61 mm。

基于MCM的多项式最小二乘法拟合的不确定度评定

通过利用仪器校准证书中的校准结果内容,可以从中得到测量值对应的修正值。为了获得任意测量值的修正数据,采用多项式最小二乘法进行拟合是一种常用手段。在研究拟合后修正值的不确定度的评定时发现,测量值的扩展不确定度会对其评定产生较大的影响。本文基于蒙特卡洛法(CMC法),对多项式最小二乘法拟合的修正值进行不确定度评定,通过利用Python编程实现MCM法评定其不确定度的步骤,获得不确定度结果。因此,MCM法在评定多项式最小二乘法修正值拟合的不确定度评定提供一定的技术参考。

复杂背景下激光等离子体光斑中心亚像素提取方法

激光等离子体光斑中心提取由于图像降噪效果不佳,导致复杂背景下的中心提取不准确,因此,设计一种新的复杂背景下激光等离子体光斑中心亚像素提取方法。该方法采用多图平均法和高斯滤波算法,将两者结合,降噪处理激光等离子体光斑图像,完整图像预处理。引入Zernike矩法,提取激光等离子体光斑中心,采用圆拟合方法优化该算法,实现光斑图像中心亚像素提取。实验结果表明,所提方法在复杂背景下提取激光等离子体光斑中心亚像素时,提取的光斑中心图像更加清晰,并且信噪比达到了47.0 dB以上,提取的中心位置的绝对误差仅为1 mm,说明该方法提取准确性较高,图像质量更好。

基于多点空间直线拟合和图像阈值分割的地下管线三维定位方法

为了精确地掌握地下管线的分布状态和形状,本文研究一种基于多点空间直线拟合和图像阈值分割的地下管线三维定位方法。采用极大值法,将发射器放置在已知图根点上,并将其与管道连接,对地下管线图像进行阈值分割操作,并将地下管线与周围环境分离开来,对图像数据进行多点空间直线拟合。通过拟合地下管线的走向,得到管线方向信息,以地下管线位置和形态为依据,完成地下管线三维定位。测试结果表明:所研究方法应用下,10个测点平面测量误差均小于50 mm,高程(埋深)测量中误差均小于30 mm。基于多点空间直线拟合和图像阈值分割的地下管线三维定位方法的准确性较优,能准确、高效地获取地下管线的位置信息。

含复杂芯材夹层复合材料弯曲性能的多构型测试方法研究

提出了一种多构型的夹芯结构弯曲刚度测试方法,该方法在弯曲测试中考虑到剪切效应的影响,实现弯曲测试中弯曲效应和剪切效应的解耦合,并采用多重线性拟合方法进行数据处理,有效提高了测试的稳定性和可靠性。采用该方法实现了对一种含有复杂芯材结构的夹芯复合材料弯曲刚度性能的评价。

基于多项拟合的电力设备红外测温方法研究

电力设备发热会对电网造成较大隐患,若处理不及时将引起电力系统故障,从而极大地降低电网系统的供电可靠性。因此,有必要在电网常规巡检中监测变压器、高压开关柜、绝缘子及导线接触点的温度,以确保电气设备正常稳定运行。文章提出一种通过高阶多项式拟合红外图像像素RGB值到摄氏温度值的映射关系的方法,该方法将红外图像像素点的RGB值作为多项式函数的输入,其中函数值为摄氏温度值。