Methodology for local correction of the heights of global geoid models to improve the accuracy of GNSS leveling

At present,one of the methods used to determine the height of points on the Earth’s surface is Global Navigation Satellite System(GNSS)leveling.It is possible to determine the orthometric or normal height by this method only if there is a geoid or quasi-geoid height model available.This paper proposes the methodology for local correction of the heights of high-order global geoid models such as EGM08,EIGEN-6C4,GECO,and XGM2019e_2159.This methodology was tested in different areas of the research field,covering various relief forms.The dependence of the change in corrected height accuracy on the input data was analyzed,and the correction was also conducted for model heights in three tidal systems:"tide free","mean tide",and"zero tide".The results show that the heights of EIGEN-6C4 model can be corrected with an accuracy of up to 1 cm for flat and foothill terrains with the dimensionality of 1°×1°,2°×2°,and 3°×3°.The EGM08 model presents an almost identical result.The EIGEN-6C4 model is best suited for mountainous relief and provides an accuracy of 1.5 cm on the 1°×1°area.The height correction accuracy of GECO and XGM2019e_2159 models is slightly poor,which has fuzziness in terms of numerical fluctuation.

Self-adaptive correction of clutch control with proportional valve

A new method for self-adaptive correction of the clutch proportional valve by Lyapunov stability function is proposed. Compared with displacement curve of hydraulic control cylinder under standard load, pulse width modulation （PWM） voltage imposed on clutch proportional valve is cor- rected according to the error to improve the consistency of the clutch control system in the process of clutch engagement. Computer simulations are conducted with this self-adaptive correction method by establishing the clutch control system model and results indicate that the principle of the method is correct. The flow rate variation obtains effective restraint which is caused by clutch control system characteristic of different vehicle under constant PWM voltage.

Using WGM2012 to Compute Gravity Anomaly Corrections of Leveling Observations in China

Gravity Anomaly Correction(GAC)is a very important term in leveling data processing.In most cases,it is troublesome for field surveyors to measure gravity when leveling.In this paper,based on the complete Bouguer Gravity Anomaly(BGA)map of WGM2012,the feasibility of replacing in-situ gravity surveying in China is investigated.For leveling application,that is to evaluate the accuracy of WGM2012 in China.Because WGM2012 is organized with a standard rectangle grid,two interpolation methods,bilinear interpolating and Inverse Distance Weighted(IDW)interpolating,are proposed.Four sample areas in China,i.e.,Hanzhong,Chengdu,Linzhi and Shantou,are selected to evaluate the systems bias and precision of WGM2012.Numerical results show the average system bias of WGM2012 BGA in west China is about-100.1 mGal(1 mGal=10^(-5) m/s^(2))and the standard deviation is about 30.7 mGal.Tests in Shantou indicate the system bias in plain areas is about-130.4 mGal and standard deviation is about 6.8 mGal.All these experiments means the accuracy of WGM2012 is limited in high mountain areas of western China,but in plain areas,such as Shantou,WGM2012 BGA map is quite good for most leveling applications after calibrating the system bias.

Free Energy Level Correction by Monte Carlo Resampling with Weighted Histogram Analysis Method

Free energy calculations may provide vital information for studying various chemical and biological processes.Quantum mechanical methods are required to accurately describe interaction energies,but their computations are often too demanding for conformational sampling.As a remedy,level correction schemes that allow calculating high level free energies based on conformations from lower level simulations have been developed.Here,we present a variation of a Monte Carlo(MC)resampling approach in relation to the weighted histogram analysis method(WHAM).We show that our scheme can generate free energy surfaces that can practically converge to the exact one with sufficient sampling,and that it treats cases with insufficient sampling in a more stable manner than the conventional WHAM-based level correction scheme.It can also provide a guide for checking the uncertainty of the levelcorrected surface and a well-defined criterion for deciding the extent of smoothing on the free energy surface for its visual improvement.We demonstrate these aspects by obtaining the free energy maps associated with the alanine dipeptide and proton transfer network of the KillerRed protein in explicit water,and exemplify that the MC resampled WHAM scheme can be a practical tool for producing free energy surfaces of realistic systems.

CHANNEL ERROR CORRECTION FOR WIDEBAND SAR-A JOINT MULTIPLE SUBPULSES PROCESSING METHOD

A novel method,referred to as joint multiple subpulses processing,is developed to calibrate the nonideal transfer function of radio frequency front-end and I/Q imbalance in quadrature modulate/demodulate systems simultaneously,which frequently occur in wideband Synthetic Aperture Radar(SAR) systems.Based on the time-frequency relation of the chirp signal and the analyses of the channel errors in wideband SAR,joint multiple subpulses processing method is adopted to separate the image frequency component due to the I/Q channel error.Then,the complete description of the channel error is acquired for building the correction function,which is used to correct the radar raw echo in frequency domain.The validity and capability of this method are demonstrated by the experiments of the channel error correction on the high resolution SAR system with the effective bandwidth of 500 MHz.

Supply Chain Finance Credit Risk Evaluation Method Based on Self-Adaption Weight

Credit risk is the core issue of supply chain finance. In the supply chain, problems happened in different enterprises can influent the whole to different degrees through transferring, thus statuses of all enterprises and their different influences should be considered when evaluating the supply chain’s credit risk. We examine the characters of supply chain network and complex network, use the local growing complex network to simulate the real supply chain, use cluster analysis to classify the company into several levels;Introducing each level’s self-adaption weight formula according to the company’s quantity and degrees of this level and use the weight to improve the credit evaluation method. The research results indicate that complex network can be used to simulate the supply chain. The credit risk evaluation (CRE) of an enterprise level with bigger note degrees has a greater weight in the supply chain system’s CRE, thus has greater effect on the whole chain. Considering different influences of different enterprise levels can improve credit risk evaluation method’s sensitivity.

Design of nuclear radiation level gauge based on normalized LMS filtering correction

In the measurement of liquid level in industrial site environment,noise interference can affect the measurement accuracy.In order to improve the measurement accuracy of liquid level in the viscous state,a nuclear radiation level measurement system based on the least mean square(LMS)filtering correction method is designed.The system uses STM32F103 as the control core and adopts HART bus HT1200M chip for remote signal transmission and reception.The adaptive LMS algorithm can be used for more accurate filtering,calculating iterative weight vector,updating weighted coefficient,effectively removing system measurement noise and improving the measurement accuracy.The results show that the nuclear radiation level gauge based on normalized LMS can correct the measurement system accuracy in adaptive rules,improve the measurement accuracy to meet the requirements of industrial field environment for liquid level measurement and enhance the industrial automation control degree.

An Efficient Overflow Detection and Correction Scheme in RNS Addition through Magnitude Evaluation

Number Systems are media for representing numbers;the popular ones being the Weighted Number Systems (WNS), which sometimes propagate carries during arithmetic computations. The other category, Un-Weighted Number Systems, of which the Residue Number System (RNS) belongs, do not carry weights but have not yet found widespread usage in general purpose computing as a result of some challenges;one of the main challenges of RNS is overflow detection and correction. The presence of errors in calculated values due to such factors as overflow means that systems built on this number system will continue to fail until serious steps are taken to resolve the issue. In this paper, a scheme for detecting and correcting overflow during RNS addition is presented. The proposed scheme used mixed radix digits to evaluate the magnitude of the addends in order to detect the occurrence of overflow in their sum. The scheme also demonstrated a simplified technique of correcting the overflow in the event that it occurs. An analysis of the hardware requirements and speed limitations of the scheme showed that it performs considerably better in relation to similar state of art schemes.

基于WBOA的3D-DV-Hop节点定位算法

针对三维(3D)-DV-Hop定位算法未知节点从最近的锚节点获取平均跳距估算距离时定位精度低的问题,提出了一种新的基于WBOA的3D-DV-Hop算法。首先,该算法去除了网络中无法通信和无法定位的节点;然后添加了修正因子,修正平均跳距。接着创建一个用于优化的蝴蝶初始种群,构建目标函数。采用自适应权重来平衡全局搜索与局部搜索的能力,使得算法不易陷入局部最优,加快了算法的收敛精度;最终求得全局最优平均跳距。仿真结果表明:尽管算法的平均运行时间略有增加,但算法的定位精度得到了有效提高。

一测多评法测定法制半夏曲中11种成分含量及其GRA、EW-TOPSIS质量评价

目的采用一测多评(QAMS)法同时测定法制半夏曲中肌苷、鸟苷、腺苷等11种成分含量,并建立其灰色关联度分析(GRA)联合熵权逼近理想解排序分析法(EW-TOPSIS)综合质量评价方法。方法采用Shimadzu C 18色谱柱;乙腈-0.5%醋酸为流动相,梯度洗脱,流速1.0 mL·min-1;检测波长254和290 nm。以对甲氧基肉桂酸乙酯为内参比物质,计算其他10个成分的相对校正因子(RCF),测定各成分含量。采用GRA联合EW-TOPSIS模型对法制半夏曲进行综合质量评价。结果法制半夏曲中11种成分在一定浓度范围内线性关系良好,相关系数均>0.999;平均加样回收率96.94%~100.12%(RSD<2.0%,n=9);QAMS与外标法(ESM)实测值无明显差异。GRA模型相对关联度0.2903~0.6187,EW-TOPSIS模型相对接近度0.2114~0.6343;GRA和EW-TOPSIS模型综合评价结果基本一致。结论QAMS法便捷、准确,可用于法制半夏曲多指标成分定量控制,GRA联合EW-TOPSIS模型可用于法制半夏曲综合质量评价。

基于考虑误差修正的非线性自适应权重组合模型的光伏发电功率预测

为了提高光伏电站光伏发电功率预测精度,解决极限梯度提升模型、长短期记忆模型2种传统单一模型及传统组合模型极限梯度提升-长短期记忆模型的光伏发电功率预测结果滞后、预测效果易突变、预测误差较大、线性拟合性较差等不足,基于极限梯度提升算法、长短期记忆算法和线性自适应权重,提出一种考虑误差修正的非线性自适应权重极限梯度提升-长短期记忆模型进行光伏发电功率预测;分别使用极限梯度提升算法和长短期记忆算法训练得到2种单一模型,将2种单一模型的初步预测值和真实值组成新的训练数据集,利用神经网络算法训练所提出的模型,对2种单一模型的初步预测值分配自适应权重系数,并根据训练时所提出模型的预测值大小分段统计预测误差的分布,预测时根据所提出模型的预测值在预测结果的基础上累加误差均值从而进行误差修正,进一步提高所提出模型的预测精度;利用Python语言分别对所提出的模型、传统组合模型和2种传统单一模型在晴天、阴天和雨天的光伏发电功率预测性能进行仿真。结果表明:与极限梯度提升-长短期记忆模型、极限梯度提升模型、长短期记忆模型相比,所提出模型的均方根误差分别减小28.57%、 39.39%、 49.79%,平均绝对误差分别减小44.25%、 53.33%、 64.8%,决定系数分别增大1.43%、 2.38%、 3.34%,所提出的模型更有效地减小了传统单一模型的光伏发电功率预测误差,优化了传统组合模型的权重系数;3种天气条件下所提出模型的光伏发电功率预测误差相对最小且稳健性最强,验证了所提出模型的有效性。

谷幅变形全天时自动化监测的精密气象改正方法

谷幅变形监测对保障蓄水电站等重大基础设施安全有重要作用。然而,传统谷幅变形监测方法大都选择河谷两岸气象条件较为稳定且一致时观测,很大程度上限制了谷幅变形监测全天时自动化监测的实施。为此,引入测量平差理论,研究谷幅变形全天时自动化监测的气象误差改正方法。首先,采用传统气象改正模型初步改正光电测距的气象误差;其次,采用Fourier级数拟合建立初步气象距离的全天时趋势误差模型,并据此削弱趋势项误差;再次,提出联合稳健卡尔曼滤波和加权最小二乘算法获取全天时谷幅变形观测值;最后,选用了锦屏一级水电站测试上述方法。结果显示,该方法估计的谷幅变形精度约0.9 mm,基本能够满足谷幅变形监测对精度的要求。

基于多算法分级权重集成的渤海西岸降水预报技术研究

以渤海西岸为研究区域,基于2019—2021年6—9月实况降水资料和模式预报数据,研发了一种新的降水集成预报技术,采用分级权重分配将3种客观订正预报算法和6种集合统计量算法进行集成,得到多算法分级权重集成预报(Hierarchical-weight Consensus Forecasting,HCF),然后以2021年9月渤海西岸一次典型强降水过程为例进行了检验评估。结果表明:HCF预报(08时—次日08时)的所有降水量级的TS评分均高于欧洲中期天气预报中心(ECMWF)的模式预报;相较于ECMWF模式预报和其他客观预报,HCF在降水量级和落区预报方面均表现良好,08时—次日08时的大雨及以上量级的TS评分最高,其他降水量级检验评估指标也均在前三位;在个例检验中,HCF预报较ECMWF模式的所有降水量级的检验指标均更优秀,其中小雨预报的TS评分较ECMWF模式提升41.76%,大雨预报评分提升54.42%。

高阶数控运动轴的弧齿锥齿轮全工序法加工研究

为解决弧齿锥齿轮全工序法加工齿面误差修正的难题,本文将开展高阶数控运动轴的弧齿锥齿轮全工序法加工研究。首先由刀具和工件的相对空间位置关系完成了传统摇台式机床调整参数到全数控机床运动轴的等效转换,并通过泰勒展开的方法获得了数控机床运动轴6阶表达式;随后推导了6阶多项式表达的齿面方程,分析了多项式系数对齿面拓扑结构的影响。结果表明,同等量的系数变化,随着系数的阶次增高,对齿面偏差影响的程度变小。建立了多项式系数对齿面误差影响的敏感性矩阵,对工作面与非工作面引入权重系数构建了齿面误差协同修正模型。最后通过算例进行了实验验证,经修正后齿面误差得到有效减小。本文的研究为弧齿锥齿轮全工序法加工修正提供了方法,同时本方法也适用于弧齿锥齿轮其他的加工方式。

拟合杂交肉羊生长曲线及构建60、180日龄体重校正公式研究

为探讨杂交肉羊的生长发育规律,选取生长发育良好的南湖杂交羊(南丘羊×湖羊,NH)、陶湖杂交羊(陶赛特羊×湖羊,TH)为研究对象,利用SPSS软件拟合Logistic、Gompertz和Von Bertalanffy三种非线性模型分析NH、TH羊的早期生长发育规律,构建NH、TH羊达到60日龄(断奶)和180日龄时的体重校正公式。结果表明,3种模型均能较好地拟合生长曲线,其中Von Bertalanffy非线性模型对NH、TH羊的拟合度最高。在目标日龄段,构建NH母羊达到60日龄(断奶)的体重校正公式为W_(60校)(kg)=W_(实)×18.254[/18.254+0.0493×(T_(实测日龄)-60)],达到180日龄的体重校正公式为W_(180校)(kg)=W_(实)×30.956[/30.956+0.0515×(T_(实测日龄)-180)];TH母羊达到60日龄(断奶)的体重校正公式为W_(60校)(kg)=W_(实)×17.087[/17.087+0.0439×(T_(实测日龄)-60)],达到180日龄的体重校正公式为W_(180校)(kg)=W_(实)×31.869[/31.869+0.0934×(T_(实测日龄)-180)]。

基于相机RGB值的光谱反射率重建方法研究

光谱反射率重建技术可实现背景颜色数据准确校正和复制还原,以此为基础可设计实施高融合迷彩,为机动装备在不同背景环境下提供有效防护屏障,具有重要价值。参照光谱成像技术特点,根据颜色形成原理和三刺激值定量计算公式,通过控制单一变量法设计实验方案,提出加权平均光谱反射率重建方法(TWA),利用相机和光谱仪分别获取训练样本的成像系统响应值(RGB)和光谱反射率数据,对所提取的样本RGB值和光谱反射率数据分别采用传统最小二乘法(OLS)、正则化最小二乘法(RLS)、偏最小二乘法(PLS)、主成分分析法(PCA)和本文中提出的加权平均法(TWA)进行光谱反射率重建训练,获得光谱重建矩阵,最后利用光谱重建矩阵对测试样本响应值进行光谱反射率重建,并对实验结果进行分析,对比不同方法的光谱反射率重建效果。研究结果表明,加权平均法在光谱均方根误差SRMSE、平均拟合优度系数GFC、平均色差等指标上效果更优,重建所得光谱反射率精度更高,颜色校正效果更佳。

线性学术评价中权重扭曲危害、成因及对策研究——最小均值指标权重修正法

[目的/意义]在线性学术评价中,普遍存在初始权重与实际权重不一致问题。[方法/过程]文章以学术期刊评价为例,在对其产生机制进行理论分析的基础上,研究了其危害,并对现有的几种解决方法的不足进行了剖析,提出一种新的最小均值指标权重修正法,并进行了实证检验。[结果/结论]研究结果表明:最小均值指标权重修正法可以彻底解决自然权重问题;要重视自然权重问题对学术评价科学带来的影响;最小均值指标权重修正法也适用于所有的线性评价。

基于自适应修正模型的飞行器外流场三维计算方法

目前飞行器外流场仿真方法中存在流体可压缩性判断依赖经验知识以及目标外流场三维仿真缺乏封闭约束条件的问题。对此,提出一种基于自适应修正模型的三维外流场数值计算方法。根据飞行器外流场变异系数先验知识,采用加权平均N-S方程表示可压缩流体物理量分布,同时利用膨胀压缩修正和激波不定项修正两种策略自适应地修正k-ε湍流模型的可压缩性约束条件,并采用壁面函数对近壁区进行近似计算修正约束条件。以某型号无人机外流场分布三维建模仿真实验,结果表明:当飞行器速度达到1.5马赫时,可压缩修正模型出现边界约束条件临界值,所提自适应可压缩修正算法能有效判断气体可压缩性的变化并提升流体分布计算的准确性。

基于色彩均衡和多权重融合的水下图像增强算法

针对水下图像色偏严重及对比度、饱和度和色彩丰富度不足等问题,提出一种基于色彩均衡和多权重融合的水下图像增强算法。利用暗通道先验(Dark Channel Prior,DCP)算法进行水下图像去模糊预处理,利用基于动态阈值的自动白平衡算法进行色偏校正,将处理后的图像再进行多权重融合。融合处理过程主要建立在2个图像的权重计算,分别是基于伽马校正的对比度提升图像和基于直方图均衡化的边缘增强图像,分别计算2个图谱的显著性权重和饱和度权重,线性融合2个图谱计算后的权重得到增强图像。结果表明,所提算法对水下图像整体清晰度恢复效果较好,而且对比度和图像色彩细节表现均有很大提升。相比其他主流算法,水下图像色彩评价(Underwater Color Image Quality Evaluation,UCIQE)指标和水下图像的质量评价(Underwater Image Quality Measurement,UIQM)指标提升效果显著,平均参数指标分别提升了22.3%和10.2%。

绿色办公建筑评价标准地域性研究

我国绿色办公建筑发展迅速,其评价体系也应不断更新。现有评价体系中的普适性问题和忽视地域差异问题,导致评价实践趋同化,地区针对性不足。为解决办公建筑绿色评价中忽视本地资源环境限制、设计阶段评价高而运行阶段评价低的问题,引入修正权重建立地域特征影响模型,系统地分析各省地域条件对绿色办公建筑评价的影响。结果表明,地域因素显著影响评价得分,并且在绿色资源丰富地区及城市环境高压力地区评价要点的得分更高。