Study on Measurement Methods of Multi-Directional Waves—Wave Gauge Array Method

Measuring multi-directional waves with the wave gauge array is one of the fundamental and easily realised methods. In this paper, the wave gauge array is described and the effects of the gauge spacing, the array orientations, etc. of the three array arrangements, i. e., linear array, T-type array and pentagon array, on the resolution of the directional spreading of waves, are investigated experimentally. This study can be used as a reference in the experimental study and the field measurement of directional waves.

Determination of Fe^(2+)/Fe^(3+)Ratios of Magnetite using Different Methods:A Case Study from the Qimantag Metallogenic Belt

Determination of Fe^(2+)/Fe^(3+) ratios from metallogenic belts to explore controlling physical and chemical conditions of rock formation is of great significance.In order to explore magnetite Fe^(2+)/Fe^(3+) ratios of the Qimantag metallogenic belt,part of the Eastern Kunlun orogenic belt in the northeastern margin of the Qinghai–Tibetan plateau,western Central Orogenic Belt of China,and overcome the limitation of the traditional electronic probe,five different measurement methods are proposed and their respective advantages and disadvantages evaluated,with the composition data of the magnetite obtained using electron probe microanalysis(EPMA).The direct oxygen measurement method has a significant impact on the determination results of FeO and Fe2O3,but the accuracy and uniformity of the results are low.The valence method(Flank method)based on the spectral intensity ratio of Lαto Lβfor iron is also unreliable for FeO and Fe_(2)O^(3) measurements because it is difficult to establish a relationship between Lβ/Lα,the spectral intensity ratio,and the Fe^(2+)/Fe^(3+) content ratio.In comparison,the charge difference method,the surplus-oxygen method and the Mössbauer spectrum method are still the most favorable.Mössbauer spectroscopy,with its isomer movement particularly sensitive to the oxidation state of iron,yields results closer to 0.5,which is relatively reliable.Earlier magnetite deposits are located in intrusions or contact zones and formed by magmatic fluids with high Fe2+/Fe3+ratios,whereas later magnetite deposits are farther away from intrusions and have low Fe^(2+)/Fe^(3+) ratios.The transformation mechanism of hematite and magnetite in the Qimantage metallogenic belt is also studied.No large volume changes,such as pore filling and shrinkage fracture,were detected in the metallogenic belt,and the transformation mechanism is more similar to a reoxidation and reduction mechanism.

Design of Measuring Instrument with Whole Direct Method for Bed Shear Stress Under Two-Dimensional Water-Flow Co-action

The present study aims at the design and making of measuring instrument of whole direct method for bed shear stress under two-dimensional water-flow co-action. The instrument combines the traditional strain gauge with a precise pressure gauge, and adopts the method directly measuring the difference between the lateral hydrodynamic pressure and different head pressures on both sides of the force plate. As a result, such an instrument solves a technical puzzle of the past strain gauge, i.e. the difficulty to set apart shear stress and lateral force. Static force test and sink test both prove that the instrument is precise, stable and applicable to the measurement of rough beds with different shear stresses.

Tower-based observation of air-sea momentum flux:comparisons between onshore and offshore winds

We investigate the air-sea momentum flux in the marine atmospheric boundary layer using a tower-based direct measurement method.First,we compare the collected data with previous observations,and the results are roughly consistent.Next,in the low-to-moderate winds,the exchange coefficients(or drag coefficients)deviate between onshore and offshore winds,which exhibits the influence of surface wave on the momentum flux.Furthermore,we use a surface-wave-involved parameterization scheme to explain the dependence of momentum flux on surface wave.The results consolidate the influence of surface wave on momentum flux on the one hand,and validate the surface-wave-involved parameterization scheme on the other hand.

Similarity evaluation of stratum anti-drilling ability and a new method of drill bit selection

Considering the stratum anti-drilling ability,drill bit working conditions,drill bit application effect and drill bit economic benefits,the similarity of stratum anti-drilling ability was evaluated by grey relational analysis theory to screen out candidate drill bits with reference values.A new comprehensive performance evaluation model of drill bit was established by constructing the absolute ideal solution,changing the relative distance measurement method,and introducing entropy weight to work out the closeness between the candidate drill bits and ideal drill bits and select the reasonable drill bit.Through the construction of absolute ideal solution,improvement of relative distance measurement method and introduction of entropy weight,the inherent defects of TOPSIS decision analysis method,such as non-absolute order,reverse order and unreasonable weight setting,can be overcome.Simple in calculation and easy to understand,the new bit selection method has good adaptability to drill bit selection using dynamic change drill bit database.Field application has proved that the drill bits selected by the new drill bit selection method had significant increase in average rate of penetration,low wear rate,and good compatibility with the drilled formations in actual drilling.This new method of drill bit selection can be used as a technical means to select drill bits with high efficiency,long life and good economics in oilfields.

Re-measuring International Short-term Capital Flow into China with Varying Methods

This paper.fi＇rst conducts a systematic review of domestic and foreign scholars＇ approaches to predicting short-term capital flows, then employs a combination of both direct and indirect methods to carry out its analysis. Three kinds of indicators, both specific and general, are applied in both methods. Thorough consideration is given to short-term international capital inflow from trade, other current account items, capital account, and errors and omissions, as well as other channels through which short term capital might accrue to a nation＇s balance. Based on a comprehensive comparison of year-on-year data, this paper also estimates monthly data using a simplified, indirect calculation approach. Estimates show that, despite a degree of difference in results between methods, most estimates are highly consistent for a given period. Based on monthly estimates, we conclude that turbulence in international financial markets （i.e., the United States subprime mortgage crisis and the European sovereign debt crisis） has had a major impact on China ＇s short-term capital flow.

极近距离煤层开采无煤柱自成巷控制方法研究

极近距离煤层传统长壁开采,受上层遗留煤柱和采空区垮落等因素的影响,下煤层开采过程中应力环境复杂、矿压显现剧烈,易诱发巷道围岩大变形。为解决上述问题,提出了极近距离条件下巷道定向切顶–约束高强支护无煤柱自成巷控制方法。通过顶板定向预裂切顶,主动改变顶板悬臂结构,切断采空区向巷道顶板的应力传递。充分利用矿山压力和岩体碎胀特性,取消煤柱留设,结合高强支护加强巷道顶板整体性,共同实现切顶自成巷。建立了极近距离煤层开采覆岩结构模型,计算了下煤层切顶自成巷巷旁支护阻力。以典型极近距离煤层为工程背景,开展了不同开采方法的数值试验对比研究,结果表明,提出的自成巷控制方法使巷道围岩应力降低59.8%,巷道顶板变形减少70.8%,并明确了极近距离煤层开采无煤柱自成巷控制机理。在此基础上,开展了典型极近距离煤层工程设计及现场应用研究,结果表明该方法有效降低了矿压显现程度,保证了自成巷的安全稳定控制。

基于压差法的波向测量方法初步研究

为解决波向测量误差大的问题,本文首次提出了一种基于压差法的波向测量新技术,根据海浪的运动变化规律,在这里巧妙地引进了压差技术,通过对放置在水下一个圆环上多个压力传感器同圆心点上的压差变化进行分析可以得出,圆环上不同方向上的压力传感器同圆心点上的压力传感器之间的差值及相位是随波浪方向变化而变化的,对圆环上不同方向上的压力传感器同圆心点上的压力传感器之间的差值进行分析,找出变化规律与波向的关系,以此得出真实的波向分布。本文通过波浪水池实验验证了该方法的可行性,并通过对实验数据的解析初步得出了压差变化规律与波向的变换关系。

基于高阶幂的单快拍LDACS系统波达方向估计

L波段数字航空通信系统(L band digital aeronautical communication system,LDACS)是未来航空宽带通信重要的基础设施之一,针对LDACS信号容易受到相邻波道大功率测距仪(distance measuring equipment,DME)信号干扰的问题,提出了联合正交投影干扰抑制与单快拍稀疏分解的波达方向(direction of arrival,DOA)估计方法。通过子空间投影抑制DME干扰,然后使用单快拍数据构建伪协方差矩阵,对伪协方差矩阵求高阶幂,之后进行奇异值分解,并利用约束条件求解稀疏解得到期望信号来向的估计值。所提方法使用高阶伪协方差矩阵降低了噪声影响,仅用单快拍就可以准确估计LDACS信号的入射方向。仿真结果表明,改进单快拍高级幂(improved single snapshot high order power,ISS-HOP)L1-SVD算法的估计精度优于ISS-HOP-MUSIC算法。该方法可以有效抑制DME干扰,提高OFDM接收机性能。

高精度管道漏风量测试仪的设计及实验研究

现有的国产漏风量测试仪普遍存在测量精度低、自动化水平低的问题,为此,基于漏风量测试仪的原理,开展了漏风量测试仪的结构设计、系统设计及整机实验研究。首先,对漏风量的测量过程、喷嘴流量测量原理进行了研究,推导了喷嘴流量测量公式,并根据相关标准设计了角接取压方式的喷嘴结构,基于仪器操作便捷性要求,对整机结构进行了设计;其次,采用空气密度补偿公式完成了高精度流量自适应测量,设计了基于自锁式电磁阀的换向调零电路,采用换向调零法对压差传感器零点漂移进行了补偿,使用小波阈值去噪算法消除了信号噪声,提高了流量的测量精度;采用抗积分饱和比例积分微分(PID)算法对流量进行了闭环控制;最后,研制了管道漏风量测试仪样机,开展了压差与流量测量精度与重复性实验。实验及研究结果表明:该高精度漏风量测试仪工作状态稳定,压差测量精度为±0.4%,流量测量精度为±2%;该漏风量测试仪的测量精度优于国内同类仪器,符合国家标准要求,具有良好的市场前景。

行进间地面机动目标射击诸元解算方法

针对地面机动目标运动模式未知、无源跟踪缺乏距离量测信息导致传统射击诸元解算方法解命中精度下降的问题,提出一种基于纯角度测量的行进间地面机动目标射击诸元解算方法。在传统固定参数的当前统计(CS)模型基础上,利用模糊推理动态调整机动频率,并根据加速度历史估计信息设置机动加速度方差,提高目标方位角的估计精度;在一次测距的基础上,基于简化刚体弹道模型,利用割弦迭代法计算出命中点坐标,并在每次迭代中利用虚拟脱靶量对射击诸元进行修正,减少对弹道方程的计算次数,提高射击诸元解算的实时性和精度。仿真结果表明,该方法有效可行,基于模型参数自适应的CS模型提高了目标角度跟踪的精度,基于虚拟脱靶量的迭代修正算法提高了诸元解算的实时性,解命中精度相对于传统射击诸元解算方法得到了显著改善。

电力系统碳排放计量与分析方法综述

碳排放的准确计量与分析是电力部门实现低碳转型与深度脱碳的基础和前提。该文分析电力系统中碳排放的来源与特性,阐明电力系统中直接碳排放与间接碳排放的含义与区别,说明电力系统中精准碳计量与分析的必要性。在此基础上,分别研究和归纳电力系统直接和间接碳排放的计量与分析方法;对现有相关研究中提出的碳计量与分析方法进行总结,围绕原理、优缺点以及应用现状等方面对不同方法进行对比分析。最后,对电力系统直接和间接碳排放计量与分析方法的发展方向进行展望。相关研究成果可为我国电力系统碳排放计量与分析体系的构建和完善提供参考,助力电力系统的低碳转型。

非凸多分块优化的Bregman ADMM的收敛率研究

Wang等提出了求解带线性约束的多块可分非凸优化问题的带Bregman距离的交替方向乘子法(Bregman ADMM),并证明了其收敛性.该文将进一步研究求解带线性约束的多块可分非凸优化问题的Bregman ADMM的收敛率,以及算法产生的迭代点列有界的充分条件.在效益函数的Kurdyka-Lojasiewicz (KL)性质下,该文建立了值和迭代的收敛速率,证明了与目标函数相关的各种KL指数值可获得Bregman ADMM的三种不同收敛速度.更确切地说,该文证明了如下结果:如果效益函数的KL指数θ=0,那么由Bregman ADMM生成的序列经过有限次迭代后收敛;如果θ∈(0,1/2),那么Bregman ADMM是线性收敛的;如果θ∈(1/2,1),那么Bregman ADMM是次线性收敛的.

基于PMU梯度动态偏差的新型电力系统快速稳定性

在能源转型和科技进步双重推动下,高比例可再生能源和高比例电力电子设备正成为电力系统发展重要趋势和关键特征.新型电力系统动态行为随之发生重大变化,传统小干扰稳定性分析方法满足使用需要,在应对运行工况快速变化场合时尚存在亟需解决问题.提出基于同步相量测量装置(PMU)数据梯度动态偏差李雅普诺夫直接分析法对新型电力系统小干扰稳定性进行分析,利用PMU数据矩阵降维得到低维矩阵,代入含双馈异步风力发电机组的电力系统矩阵模型,求解李雅普诺夫方程式得到对角矩阵,通过判定矩阵正定性对系统稳定性作出判断.利用求解后得到的对角矩阵计算相应状态变量动态偏差值,对相应状态变量曲线使用梯度下降法迭代计算该曲线极值点数值,时间加权计算整个振荡过程时间加权动态偏差量,为阻尼稳定控制器配置位置提供指导.利用含风力发电新英格兰10机39节点系统仿真验证方法可以达到改善系统小干扰稳定性以及对新型电力系统快速稳定性分析的有效性.

Android平台下测量系统开发及应用

为解决工程测量数据采集和处理环节的质量控制问题.在Android平台下进行JAVA测量程序设计.实现了三等与四等水准测量、测回法角度测量数据的输入和观测数据自动计算,测量员基本信息和各项限差输入,如有错误,则给出相应的错误提示信息,否则便可转入下一测站或下一测回的工作.研究结果表明:该程序可避免测量员对各项限差的记忆问题,为信息化测量奠定一定的基础,对Android平台下测量程序的开发有一定的参考价值.

基于改进稀疏重构模型的声学层析温度分布重建

为进一步提高基于声学层析成像的温度分布重建精度,引入了一种偏差较小的误差函数(ERF)对稀疏重构模型进行改进,并使用迭代重加权算法对模型进一步优化,最后采用交替方向乘子算法(ADMM)对模型进行求解,从而完成温度分布重建。进行了仿真与实验测试,并与LASSO、ART及Landweber算法进行比较,仿真实验中基于ERF模型的温度分布重建质量最优,其平均相对误差及均方根误差分别为0.1%和0.14%;实验测试中,其设定温度点重建温度误差绝对值的平均值最小,为0.043%,明显小于其它3种算法。

多路绝对激光测距仪精密三维控制网的建立与解算

建立高精度三维控制网是实现大型粒子加速器等精密工程测量的前提条件,目前主要通过间接测量两点间距离或者自由设站实现,而多路绝对激光测距仪可在0.02~30 m范围内直接测量空间中两点间距离,利用高精度绝对测距值可建立高精度的三维测边控制网。基于多路绝对激光测距仪高精度绝对测距性能,建立仅含控制点间距离的秩亏自由网平差模型,通过任意初值选取,应用改进的LM算法迭代求解非线性超定方程组实现坐标概算,得到方程组的一组解作为未知数的近似值进行整网平差,获得高精度控制点坐标。实验数据分析表明,在8 m×3.5 m×2.5 m的实验范围内,建立控制点平均点位精度优于±1.14μm的三维测边网,可满足现代工业生产中对安装定位的高精度需求。

基于一维直接线性变换的视频中路面距离测量方法

为了解决混行路网中不同交通参与方因通行宽度被侵占引发的交通事故路权纠纷,提出一种基于直接线性变换理论的视频中路面距离测量方法。该方法基于一维直接线性变换算法,利用视频中与待测点共线的3个特征点,确定像方距离与物方距离的直接线性变换关系,进而解算目标距离。以Faro Focus^(3D)激光三维扫描仪现场扫描的测量值为参考值,评估该方法的测量误差。实验结果表明,本方法能够有效测量视频中的路面距离,测量精度可达厘米级,并适用于不同拍摄角度的视频,从而确定混行路网中不同事故参与方所属的通行宽度,为司法鉴定、事故处理提供技术支持。

农机轨迹田路分类的局部方向中心性度量聚类算法

利用海量轨迹数据中蕴藏的时空信息分析农机的行为模式,将轨迹点分割成一系列田间路段和道路路段,并分配相应的语义标签,是后续有关农业机械轨迹研究的重要前置任务。已有基于密度的聚类算法难以有效分离弱连接簇,在聚类时易将弱连接的不同簇识别为同一簇。为克服上述缺陷,设计了一种面向农机轨迹田路分类的局部方向中心性度量和空间距离特征的聚类算法。该算法采用一种基于局部方向中心性度量的分簇机制,用于分离弱连接簇;为进一步提高算法的准确率,提出一种基于空间距离特征的簇边界重置策略,其根据元素点间的空间距离和邻域内其他点的数量分布情况对簇边界处的点进行重置,从而提高算法在簇边界处的识别性能。为验证所提方法的有效性,在农业农村部农机作业监测与大数据应用重点实验室提供的470条真实农机轨迹样本上展开了实验。结果表明所提方法的F1-score比已有聚类算法在田路分类中应用的SOTA方法在玉米、小麦、水稻收割机轨迹数据集上的F1-score分别平均提高了12.82、24.09、14.38个百分点。

优化非线性误差的激光位移传感器测距仿真

激光位移传感器需要具有高精度和高分辨率的测量能力,以满足实际应用的需求,为此提出一种优化非线性误差的激光位移传感器测距方法。在物联网环境下,通过双目视觉系统得到激光位移传感器光束的光斑位置,采用最小二乘法拟合光束直线得到光束方向参数,同时利用激光位移传感器的数值求解零点位置,实现距离测量。由于测距过程中存在非线性固有误差,为此引入BP神经网络对激光位移传感器的测距误差展开训练,完成位移误差补偿。仿真结果表明,所提方法可以有效降低激光位移传感器测距误差,同时还可以有效缩短测距耗时。