Theoretical Study of Multi-Theodolite Measurement System

In the field of aerospace, theodolite system is often used in the inspection of large object. A new measurement system that consists of four theodolites is presented in this paper, with which the "blind" problem raised in Original dual-theodolite system can be overcome. The principle of multi-theodolite system, together with the mathematicalmodel (both of calibration and of measurement) is given. And also the calibration process is discussed.

MULTIPLE INTERSECTIONS OF SPACE-TIME ANISOTROPIC GAUSSIAN FIELDS

Let X={X(t)∈R^(d),t∈R^(N)}be a centered space-time anisotropic Gaussian field with indices H=(H_(1),…,H_(N))∈(0,1)~N,where the components X_(i)(i=1,…,d)of X are independent,and the canonical metric√(E(X_(i)(t)-X_(i)(s))^(2))^(1/2)(i=1,…,d)is commensurate with■for s=(s_(1),…,s_(N)),t=(t_(1),…,t_(N))∈R~N,α_(i)∈(0,1],and with the continuous functionγ(·)satisfying certain conditions.First,the upper and lower bounds of the hitting probabilities of X can be derived from the corresponding generalized Hausdorff measure and capacity,which are based on the kernel functions depending explicitly onγ(·).Furthermore,the multiple intersections of the sample paths of two independent centered space-time anisotropic Gaussian fields with different distributions are considered.Our results extend the corresponding results for anisotropic Gaussian fields to a large class of space-time anisotropic Gaussian fields.

Novel Distance Measures on Hesitant Fuzzy Sets Based on Equal-Probability Transformation and Their Application in Decision Making on Intersection Traffic Control

The purpose of this study is to reduce the uncertainty in the calculation process on hesitant fuzzy sets(HFSs).The innovation of this study is to unify the cardinal numbers of hesitant fuzzy elements(HFEs)in a special way.Firstly,a probability density function is assigned for any given HFE.Thereafter,equal-probability transformation is introduced to transform HFEs with different cardinal numbers on the condition into the same probability density function.The characteristic of this transformation is that the higher the consistency of the membership degrees in HFEs,the higher the credibility of the mentioned membership degrees is,then,the bigger the probability density values for them are.According to this transformation technique,a set of novel distance measures on HFSs is provided.Finally,an illustrative example of intersection traffic control is introduced to show the usefulness of the given distance measures.The example also shows that this study is a good complement to operation theories on HFSs.

Continuous Flow Intersection Performance Measures Using Connected Vehicle Data

Continuous flow intersections (CFIs), also known as displaced left turns (DLTs), are a type of alternative intersection designed to improve operations at locations with heavy left-turn movements by reallocating these vehicles to the left side of opposing traffic. Currently, simulation is commonly used to evaluate operational performance of CFIs. However, this approach requires significant on-site data collection and is highly dependent on the analyst’s ability to correctly model the intersection and driver behavior. Recently, connected vehicle (CV) trajectory data has become widely available and presents opportunities for the direct measurement of traffic signal performance measures. This study utilizes CV trajectory data to analyze the performance of a CFI located in West Valley City, UT. Over 4500 trajectories and 105,000 GPS points are analyzed from August 2021 weekday data. Trajectories are linear-referenced to generate Purdue Probe Diagrams (PPDs) and extended PPDs to estimate split failures (SF), arrivals on green (AOG), traditional Highway Capacity Manual (HCM) level of service (LOS), and the distribution of stops. The estimated operational performance showed effective progression during the PM peak period at all the critical internal storage areas with AOG levels at exit traffic signals between 83% and 100%. In contrast, all external approaches with longer queue storage areas had AOG values ranging from 2% to 81% during the same time period. The presented analytical techniques and summary graphics provide practitioners with tools to evaluate the performance of any CFI where CV trajectories are available without the need for on-site data collection.

DISTANCE MEASURING MODELING AND ERROR ANALYSIS OF DUALCCD VISION SYSTEM SIMULATING HUMAN EYES AND NECK

A dual-CCD simulating human eyes and neck (DSHEN) vision system is putforward. Its structure and principle are introduced. The DSREN vision system can perform somemovements simulating human eyes and neck by means of four rotating joints, and realize preciseobject recognizing and distance measuring in all orientations. The mathematic model of the DSHENvision system is built, and its movement equation is solved. The coordinate error and measureprecision affected by the movement parameters are analyzed by means of intersection measuringmethod. So a theoretic foundation for further research on automatic object recognizing and precisetarget tracking is provided.

A New Browder Fixed Point Theorem in Noncompact Hyperconvex Metric Spaces and Its Applications to Section Questions and Intersection Questions

In this paper, a new Browder fixed point theorem is established in the noncompact sub-admissible subsets of noncompact hyperconvex metric spaces. As application, a Ky Fan section theorem and an intersection theorem are obtained.

INTERSECTION OF MCMULLEN SET WITH ITS RATIONAL TRANSLATION

In this paper, we study the intersection of Mcmullen set with its rational translation. The main difficulty is that the generating structure of the intersection. By the radix expansion of translating vector, we give its fractal characterization. We find that the Hausdorff measure of these sets forms a discrete spectrum whose non-zero values come only from translating the vector （x,y） with its radix expansion.

原子级制造的关键基础科学问题

人类的制造技术逐步向原子级推进,原子作为化学反应中的最小粒子,虽然它可以分成更小的原子核、电子等,但是从制造的角度看,原子级制造可以说是人类制造的最底层技术,也是继微纳制造之后新的制造范式,可将制造精度以及产品性能推向极致水平,代表着人类对物质世界认知和制造能力发展的新阶段,是引领未来产业变革发展的战略性技术,也是保障国家安全和推动国计民生重大装备跨代升级的重要前沿方向。本文基于第330期双清论坛总结了原子级制造的研究现状、发展趋势及机遇挑战,凝练出未来5~10年原子级制造的焦点问题和亟需解决的关键科学问题,探讨了相关领域的前沿发展方向和科学基金资助战略。

面向科学与技术的交叉领域研究--概念内涵、测度方法

[目的/意义]科学与技术的交叉融合是前沿创新突破的重要生长点。系统性梳理与总结国内外交叉领域的研究成果,旨在为本领域研究提供参考。[方法/过程]基于科学领域内部交叉、技术领域内部交叉、科学—技术领域间交叉3种交叉类型,梳理交叉领域的概念关系及其内涵,立足计量学与内容挖掘视角,细致阐释交叉领域的测度方法。[结果/结论]基于现有研究,提出交叉领域研究的概念关系与测度方法框架,从3个方面总结该领域未来发展方向:基于科技报告、专著、标准、论文、专利等海量、多源、异构数据的交叉研究,综合3种类型交叉的全局分析,基于交叉领域的前沿创新方向探测。

双目中子散射相机快速定位方法研究

为了探究使用中子散射成像法对核材料的定位分辨率和测距精度与源项方位之间的关系,以及提高定位性能的可行方案,本文利用Geant4软件模拟了位于不同方位的Cf-252中子源成像过程。使用交点反投影成像法与双目视觉测距法进行二维成像与测距,研究了定位误差与中子源方位之间的依赖性。研究表明:源项位置距离成像平面中心越远,成像效果越差,当改变探测系统布置时可能出现定位死区,并且通使探测器面向源项所在方向会增强成像性能。本文提出的快速定位未知位置中子源或核材料的方法及探测器布置方案有效。

市政道路施工中既有地下管线保护措施研究

本文基于市政道路工程实例,对市政道路施工中既有地下管线保护措施进行了分析和研究,从而达到更好地保护既有管线的目的。针对不同类型的既有管道,采用经济可靠的保护方法,明晰拟建结构物与既有管线交叉分布情况,从保护方法的选择、保护方案的确定、保护制度的建立、施工过程的管理、管道恢复的措施等方面进行阐述,有利于维护市政道路地下管道管线正常运行,延长管线的使用年限,减少项目维修成本费用。

大跨度铁路斜拉桥索力快速识别方法研究

大跨度铁路桥梁天窗时间有限且上道条件苛刻,如何基于常规监测设备利用简易方式实现大跨度铁路斜拉桥索力高精度识别十分重要。研究提出一种考虑斜拉索抗弯刚度的索力快速识别方法,既可提高索力识别精度又可大量简化运营期索力识别步骤,且不受拉索边界条件和铁路桥梁实际运营状态的限制。研究表明,抗弯刚度是对索力识别精度影响较大的因素之一,通过考虑拉索实际抗弯刚度可以提高索力识别的准确性,基于拉索加速度振动实测数据在拉索简支梁模型基础上建立索频、索力以及抗弯刚度的函数关系,通过数值方法计算实测多阶模态下抗弯刚度—索力连续变化图,再通过多阶模态的交线则可进一步确定拉索的唯一抗弯刚度和索力值,并以某大跨度铁路斜拉桥为依托工程,对方法的有效性进行了验证。结果表明:(1)该方法识别的索力结果相对误差可降低5.22%,换算成绝对索力值可达254.45 kN;(2)在实际应用中识别结果易受到低阶频率干扰,宜采用拉索高阶频率进行识别,建议采用5阶及以上实测频率。

基于角度交会的二维坐标图像测量系统

针对基准平面障碍物检测定位问题,设计了一种采用角度交会法测量二维坐标的嵌入式图像检测系统。二维坐标测量系统采用双线法标定线阵CCD图像传感器,并采用角度交会法对被测对象进行坐标计算,从而测得未修正的二维坐标测量结果。采用控制变量法分别测量X轴和Y轴坐标,使用Matlab软件对数据进行处理,并对X轴和Y轴测量误差分别进行多项式线性拟合,进而得到坐标修正公式,修正的二维坐标误差明显变小。实验结果表明:基于角度交会的二维坐标图像测量系统能够实时、准确、快速和可靠地测量二维坐标,为基准平面障碍物二维坐标测量定位提供了一种可行的方案,具有一定的应用价值和意义。

基于椭圆成像参数匹配的弹体姿态测量方法

一体化弹丸的弹托分离过程对弹体的飞行稳定性和打击效能具有显著的影响。为此,针对一体化弹丸出膛后弹托相对弹体的六自由度运动过程,提出了基于椭圆成像参数匹配的弹体姿态测量方法,即利用弹体底部为圆形在任意角度下成像为椭圆的特点,通过提取弹体底部椭圆成像轮廓上的几个点,解算得到椭圆参数,再结合双目椭圆成像参数相同的约束条件,通过优化弹体的成像角度实现参数的最优匹配,从而实现对弹体姿态角度的估算。测试结果表明:相比传统基于纹理信息以及基于轮廓匹配的姿态测量方法,该方法不需要识别弹体表面标记点或者完整的轮廓信息,大大提高了测量方法的通用性和可靠性,且测量精度可达0.4°,满足使用要求。

某抽水蓄能电站上库坝表面变形监测及资料分析

某抽水蓄能电站上库坝在坝顶及坝后共布置3条表面变形测线,每条测线布置6~9个水平垂直位移测点,并在两岸布置倒垂线和水准基点,以此为测量基点分别采用前方交会法、几何水准法测量坝体表面水平、垂直位移。经系统分析,该工程表面水平位移、垂直位移测量方法可行,监测精度满足相应规范要求和工程安全监测需要。多年监测资料显示,上库坝表面水平、垂直位移变化已收敛,变化规律合理,符合土石坝的一般变形规律,为大坝的安全运行管理提供了重要的数据支持。

关于两隧道交叉段相互影响的研究应用

当前,空间交叉隧道越来越普遍,由于存在空间距离、建设时序和地质地形等诸多不确定因素,需考虑通过减小扰动、提高支护参数及加强监测等措施来确保两隧道结构安全。该文以沿山货运通道(新图大道)核心区一期工程(Ⅱ标段)为例,介绍了该隧道交叉段的相关加强设计,并通过数值模拟计算两隧道间的相互影响,可为今后类似工程的设计工作提供借鉴。

多CCD交汇测量技术研究

描述了一种坐标测量的新方法——ＣＣＤ交汇测量。文章介绍了ＣＣＤ交汇测量的原理，推导了坐标计算公式。为了得到较高的捕获率，提出了采用多个线阵ＣＣＤ组成交汇光靶的方案。

机载光电平台目标交会定位

根据直线交会测量原理,构建了机载光电平台目标定位数学模型。首先建立5个坐标系,确定了坐标系之间的变换关系,在地心直角坐标系下,根据光电平台观测目标的方位和俯仰角度参数,结合飞机的位置和姿态测量参数,通过坐标变换确定从光电平台到目标之间的观测直线方程。选择一组目标观测直线建立目标交会测量目标函数,根据最小二乘原理,建立关于直线交会点坐标的线性方程组。解出直线交会点的三维坐标并根据从地心直角坐标系到大地地理坐标系的变换关系,计算目标的大地经纬度和高程坐标,通过样本数据进行交会定位精度实验。实验结果表明,本文方法定位结果和实际测量数据接近,经度误差为0.65″,纬度误差为0.82″,高程误差为5 m,验证了本文方法的准确性。本文方法有效可行,对机载光电平台目标定位具有实用价值。

采用光平面交汇的大尺寸坐标测量方法

工业大尺寸测量中常用的经纬仪、跟踪仪等多站式测量系统大多使用基于空间球坐标系的角度交汇测量方式。由于这种测量方法对测站轴系结构有严格的要求,导致现有的测量设备制造成本高、组装困难,并使最终测量结果受轴系误差影响较大。介绍了一种基于光平面交汇的多站式大尺寸测量方法。采用分布于工作空间内的多台激光发射站及接收器测量待测点坐标。建立了基于双旋转激光平面的单发射站数学模型,推导了接收器三维坐标计算公式并对基于光束平差原理的测站定向方法进行了讨论。新方法降低了对测站轴系精度的要求,提高了可靠性。实验结果证明:新方法的测量精度优于0.2mm。