共查询到20条相似文献，搜索用时 312 毫秒
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浅谈GPS在高速公路应用中的高程控制测量 总被引：1，自引：0，他引：1
文章介绍了一种精度高、效率高、简易方便的公路工程GPS控制测量技术,指出了公路工程高程控制测量中GPS大地高系统与我国正常高系统转换的方法。 相似文献
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彭志勋 《北京工业职业技术学院学报》2007,6(3):68-71,96
为了改善GPS大地高向正常高转换的精度,提出了基于二次曲面的周期拟合解算GPS高程异常的新思路.首先用二次曲面函数拟合消除趋势项,然后通过离散傅立叶变换提取频率信息,从而可以获得各种不同周期函数,高程异常值可以通过各种不同周期的函数的叠加来获得,实际数据证明该方法不仅计算简单而且较常规的拟合模型有较好的应用价值. 相似文献
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GPS水准的精度主要取决于GPS大地高差转换为正常高高差所需要的高程异常差的确定精度.本文提出确定测点间高程异常差的高程异常变化梯度法的原理,精度分析及GPS水准应用隧道高程控制测量数据采集技术. 相似文献
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王红 《赤峰学院学报(自然科学版)》2012,(6):85-87
根据GPS高程测量的原理和方法,结合工作中的应用情况,探讨几种GPS高程异常模型,并对影响GPS测高精度的因素进行了分析,给出提高GPS高程拟合精度的方法． 相似文献
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吴松涛 《辽宁科技学院学报》2013,15(1):14-15,35
载波相位差分技术(Reat Time Kinematic简称RTK)又称实时动态定位技术,能够实时提供指定坐标系的三维坐标成果,在测程20km以内可以达到厘米级精度。广泛应用于工程放样、工程地形图测绘、房产测绘,地籍测量及某些控制测量,极大的提高了作业效率。由于GPS定位是直接测定点位在WGS84坐标系中的坐标和高程,故我们需要通过点位校正或求得转换参数将测得的WGS84坐标系成果转换为我们所需要的坐标系。文章以南方灵锐S86T型RTK为例对GPS—RTK的三种常见的校正方法(单点校正、两点校正、参数校正)的点位精度进行对比分析。 相似文献
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目前,在工程水准测量中主要采用传统的方法建立高精度的施工控制网,而GPS高程却常常被忽视。由于受到坐标系不一致的影响,其精度一直被认为不太可靠。本文就是针对这个问题对GPS水准测量的理论和方法进行了比较深入的探讨,并结合实际对GPS拟合高程和四等水准平差高程进行了详细的比较和分析。同时,为了探求动态GPS（RTK）测量的精度,笔者分析和研究了动态GPS（RTK）测量的各种资料及其观测方法。通过一系列的研究,对动态GPS（RTK）测量的精度也有了一定的认识,进一步提高了观测精度和工作效率。 相似文献
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在测量高差较大的点位高程时,通常利用光电测距采用三角高程测量的方法或全站仪自带的悬高测量法,但这种方法需要将棱镜准确安置在高程待求点上(如光电测距三角高程测量)或安置在通过高程待求点的铅垂线下方(如悬高测量)。但有些时候高程待求点不易到达或铅垂线下难以准确安置棱镜,给上述方法的实施带来了很大的困难。本文介绍了特殊情况下免棱镜采用三角高程测量法测定点位高程的原理、计算步骤、施测方法和应用范围。 相似文献
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肖文平 《顺德职业技术学院学报》2005,3(1):41-43
运用GPS与DR组合导航,比单纯的GPS导航在精度和可靠性方面有很大的优势.组合导航中很重要的一项工作是将GPS与DR的数据进行信息融合.GPS与DR数据通过坐标转换程序变换到同一个坐标系统下进行运算.研究了大地坐标转换程序在DEL-PHI语言下的编程方法,并给出了源程序代码. 相似文献
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《洛阳师范学院学报》2015,(11):44-47
基于北斗系统和GPS实测数据,分析了BDS单系统与BDS/GPS组合系统在亚太地区的定位精度.结果表明,BDS单系统水平方向的定位精度可达2m,高程方向定位精度可达6m,可满足导航用户定位需求.同时,BDS/GPS组合系统定位精度优于BDS单系统,能提高导航用户定位的可靠性与可用性. 相似文献
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Optimal choice of parameters for particle swarm optimization 总被引：26，自引：0，他引：26
INTRODUCTION Particle swarm optimization (PSO) is one of the evolutionary computational techniques. Since its introduction (Kennedy and Eberhart, 1995; Eberhart and Kennedy, 1995; Eberhart et al., 1996), PSO has attracted much attention from researchers around the world. It is a population-based search algorithm and is initialized with a population of random solutions, called particles. Each particle in PSO moves over the search space at velocity dynamically adjusted according to th… 相似文献
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ABSTRACT: A food safety education program developed for retail food establishments was evaluated to assess the extent to which participants were practicing selected behaviors linked to reducing the risk of foodborne disease both before and after the program. Scores from the state health department's Certified Food Manager (CFM) exam also were examined. Based on the 189 usable surveys returned, most respondents were female, middle age, and white with nearly 11 y of foodservice experience. Results revealed that after completing the program, participants reported practicing behaviors related to hand washing, maintaining safe food temperatures, preventing crosscontamination, and pest management more frequently ( P < 0.05) compared to before the program. Effect size analysis indicated these results were also practically significant. Most (82.5%; n = 156) participants passed the CFM exam. Compared to those who failed the CFM exam, those who passed reported significantly higher changes in the adoption of selected behaviors; however, these results were of limited practical significance according to effect size analysis. Results suggest the food safety program is effective in promoting the adoption of food safety behaviors that can help reduce the risk of foodborne illness. 相似文献
14.
指数法和双曲线法组合预测单桩极限承载力 总被引：3，自引：0，他引：3
根据水泥搅拌桩静载试验的有限实测数据预测其极限承载力是工程中常用的方法，文章简要介绍了指数和双曲线这两种预测方法。以权重将两种方法的预测值进行组合。通过工程实例的验算，说明组合预测法的有效性和可行性，并对指数法和双曲线法的结果进行比较。 相似文献
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The nonequivalent groups with anchor test (NEAT) design involves missing data that are missing by design. Three equating methods that can be used with a NEAT design are the frequency estimation equipercentile equating method, the chain equipercentile equating method, and the item-response-theory observed-score-equating method. We suggest an approach to perform a fair comparison of the three methods. The approach is then applied to compare the three equating methods using three data sets from operational tests. For each data set, we examine how the three equating methods perform when the missing data satisfy the assumptions made by only one of these equating methods. The chain equipercentile equating method is somewhat more satisfactory overall than the other methods. 相似文献
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Cindi Mason Janet Twomey David Wright Lawrence Whitman 《Research in higher education》2018,59(3):382-400
As the need for engineers continues to increase, a growing focus has been placed on recruiting students into the field of engineering and retaining the students who select engineering as their field of study. As a result of this concentration on student retention, numerous studies have been conducted to identify, understand, and confirm relationships between student attributes and attrition. Methods of prediction have also been evaluated and compared. Utilizing the attributes found in previous studies to have correlation with student attrition, this study considers the results of three different prediction methods—logistic regression, a multi-layer perceptron artificial neural network, and a probabilistic neural network (PNN)—to predict engineering student retention at a case study university. The purpose of this study was to introduce the PNN to the study of engineering student retention prediction and compare the results of the PNN to other commonly used methods in this field of study. The accuracy, sensitivity, specificity and overall results for each method are reported, compared, and discussed as the major contribution of this paper. 相似文献
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以20世纪80年代以来高等师范音乐专业使用的三部视唱练耳教材《视唱教程》、《视唱练耳——卫星电视教育音乐教材（一-四）》和《基本乐科教程视唱卷、练耳卷》为研究对象，运用教材论，采用了文献检索法、访谈法、逻辑法、对比分析法等调查研宄方法，对这三部处于不同历史时期的教材在编写原理、编写结构和编写方式等方面进行比较，并对高师视唱练耳教材以培养首调音感为主，发展一定的固定音感，补充弹唱教材，推行视唱练耳教学分级制的发展趋势进行了展望。 相似文献
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Mohammad Khajehzadeh Mohd Raihan Taha Ahmed El-Shafie Mahdiyeh Eslami 《浙江大学学报(A卷英文版)》2011,12(6):415-427
This paper deals with the economically optimized design and sensitivity of two of the most widely used systems in geotechnical
engineering: spread footing and retaining wall. Several recent advanced optimization methods have been developed, but very
few of these methods have been applied to geotechnical problems. The current research develops a modified particle swarm optimization
(MPSO) approach to obtain the optimum design of spread footing and retaining wall. The algorithm handles the problem-specific
constraints using a penalty function approach. The optimization procedure controls all geotechnical and structural design
constraints while reducing the overall cost of the structures. To verify the effectiveness and robustness of the proposed
algorithm, three case studies of spread footing and retaining wall are illustrated. Comparison of the results of the present
method, standard PSO, and other selected methods employed in previous studies shows the reliability and accuracy of the algorithm.
Moreover, the parametric performance is investigated in order to examine the effect of relevant variables on the optimum design
of the footing and the retaining structure utilizing the proposed method. 相似文献
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航空发动机一直是民航飞机的核心产业和技术。目前,世界上主要由六家发动机制造商,他们是美国CFM国际发动机公司、美国通用电气公司、英国罗尔斯·罗伊斯公司、美国普拉特·惠特尼公司(Pratt&Whitney)、美国国际航空发动机公司、美国发动机联盟(GE-P&W Engine Alliance)。目前,国产大飞机C919选装了美国通用电气公司的Leap发动机,而国产支线飞机ARJ21选装了国际发动机公司的CFM34。为了国内航空发动机技术的发展,根据有限的资料及实际维护经验对CFM公司的经典机型(CFM56-3)的原理和常见故障进行了分析和推导。 相似文献
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Anna-Karin Carstensen 《European Journal of Engineering Education》2019,44(1-2):85-102
ABSTRACTModelling is a central activity in practical engineering and something that is also useful in engineering education research (EER). Additionally, qualitative research methods have found important applications in engineering research, although their use in EER has not always been widely accepted. Design science research is a qualitative research approach in which the object of study is the design process, i.e. it simultaneously generates knowledge about the method used to design an artefact and the design or the artefact itself. This paper uses techniques from design science research to analyse the method used when deriving the ‘learning of a complex concept’ (LCC) model, which we developed while designing teaching sequences for a course on electrical engineering. Our results demonstrate the value of design science research in EER and suggest that the LCC model is generally applicable in this field. 相似文献