scholarly journals Statistical significance of displacements in heterogeneous control networks

2013 ◽  
Vol 62 (2) ◽  
pp. 139-156 ◽  
Author(s):  
Krzysztof Nowel ◽  
Waldemar Kamiński
Keyword(s):  
Statistical Significance ◽  
Control Network ◽  
Theoretical Discussion ◽  
Control Networks ◽  
Local Variance ◽  
Deformation Measurements ◽  
Horizontal Control

Abstract This paper proposes a modification of the classical process for evaluating the statistical significance of displacements in the case of heterogeneous (e.g. linear-angular) control networks established to deformation measurements and analysis. The basis for the proposed solution is the idea of local variance factors. The theoretical discussion was complemented with an example of its application on a simulated horizontal control network. The obtained results showed that the evaluation of the statistical significance of displacements in the case of heterogeneous control networks should be carried out using estimators of local variance factors.

scholarly journals Functionality and reliability of horizontal control net (Poland)

2020 ◽  
Vol 12 (1) ◽  
pp. 668-677
Author(s):  
Bogdan Wolski ◽  
Grzegorz Granek
Keyword(s):  
Process Model ◽  
Standard Procedure ◽  
Operating Time ◽  
Control Network ◽  
Control Points ◽  
Destruction Process ◽  
Control Networks ◽  
Geodetic Control ◽  
The Impact ◽  
Horizontal Control

AbstractHorizontal control networks established with monuments are functional if the conditions related to the number of control points, their density, condition and stability of coordinates are met. For functionality defined in those terms, deterministic accuracy characteristics are of little use. The subject matter discussed herein includes the two key features of geodetic control points, i.e., usability and stability. Due to the varying properties of those variables and the impact of the operating time of the system, there is no alternative to reliability-based approach in developing the functionality model. The measures of functionality and the procedures of data acquisition for developing the model of the control network destruction process have been defined. The solution presented herein is relevant for geodetic practice, providing a standard procedure for defining the time frame and the scope of the control network upgrading. The identified destruction process model optimizes this task assuming critical states expressed by the functionality probability. The applied approach is an example of the reliability theory-based approach typical for engineering. The issue of simulating the destruction process is illustrated with the results of the tests of class 3 control networks conducted in Kielce and Lodz regions in Poland. As a result of the tests, the characteristic properties of the control network destruction process have been identified. It was also shown how the patterns of usability and accuracy of the geodetic control points are relevant on the stage of implementing investment project tasks.

scholarly journals Elimination of some unknown parameters and its effect on outlier detection

2012 ◽  
Vol 18 (3) ◽  
pp. 347-362 ◽  
Author(s):  
Serif Hekimoglu ◽  
Bahattin Erdogan ◽  
Nursu Tunalioglu
Keyword(s):  
Outlier Detection ◽  
Functional Model ◽  
Computational Time ◽  
Control Network ◽  
Unknown Parameters ◽  
Reliable Estimation ◽  
Cofactor Matrix ◽  
Simulation Results ◽  
Horizontal Control

Outliers in observation set badly affect all the estimated unknown parameters and residuals, that is because outlier detection has a great importance for reliable estimation results. Tests for outliers (e.g. Baarda's and Pope's tests) are frequently used to detect outliers in geodetic applications. In order to reduce the computational time, sometimes elimination of some unknown parameters, which are not of interest, is performed. In this case, although the estimated unknown parameters and residuals do not change, the cofactor matrix of the residuals and the redundancies of the observations change. In this study, the effects of the elimination of the unknown parameters on tests for outliers have been investigated. We have proved that the redundancies in initial functional model (IFM) are smaller than the ones in reduced functional model (RFM) where elimination is performed. To show this situation, a horizontal control network was simulated and then many experiences were performed. According to simulation results, tests for outlier in IFM are more reliable than the ones in RFM.

Readjustment of Canadian Secondary Horizontal Control Networks

1978 ◽  
Vol 32 (4) ◽  
pp. 433-442
Author(s):  
C.D. McLellan ◽  
J.P. Henderson ◽  
J.D. Boal
Keyword(s):  
Least Squares ◽  
Approximate Method ◽  
Lower Order ◽  
Early Stage ◽  
Geodetic Survey ◽  
Secondary Control ◽  
Control Networks ◽  
Least Squares Adjustment ◽  
Secondary Networks ◽  
Horizontal Control

The readjustment of the Canadian secondary and lower order control networks is scheduled to take place in 1983 following the adoption of new primary framework values. Some 200 000 points are involved. 75 000 of which are the responsibility of the Geodetic Survey. These networks are to be evaluated, strengthened, densified and extended as necessary, prior to integration. The project will be done by regions defined, for the most part, by arcs of framework control. Secondary networks will be integrated with the framework by least squares adjustment; some lower order control may be recomputed by an approximate method. Considering the amount of secondary control to be readjusted, it is essential that agreement on the sharing of responsibilities between the federal and provincial agencies involved be reached at an early stage.

An evaluation of horizontal control networks in Canada

1974 ◽  
Vol 114 (1) ◽  
pp. 335-347
Author(s):  
C. David McLellan
Keyword(s):  
Control Networks ◽  
Horizontal Control

scholarly journals A New Method for Vertical Deformation Detection Using Survey Control Networks

2009 ◽  
Vol 4 (1) ◽  
pp. 14
Author(s):  
Mudathir Omer Ahmed
Keyword(s):  
Least Squares ◽  
Confidence Level ◽  
Specific Area ◽  
New Method ◽  
Control Network ◽  
Vertical Deformation ◽  
Control Networks ◽  
Vertical Control ◽  
Vertical Deformations ◽  
Step Localization

Usually, the Survey control networks are used for deformation detection in a specific area using observations taken at different epochs. Where the coordinates obtained from two epochs, using least squares technique, are compared in order to assess if a deformation of a specified magnitude exists. Traditionally, the global congruency test is carried out so as to detect if the area of the network has undergone any movement (uplift or subsidence) due to natural or manmade causes. As a next step, localization methods are used to determine deformations at specific points in case there are changes in shape. In this research a new method is developed to establish deformations at specific points directly. The method is tested using a vertical control network simulated at various epochs of observation. The results obtained are compared with those obtained by another used method. Results obtained using this method indicate that vertical deformations greater than 0.03m using a precision of observation less than 10 can be detected at a minimum significant level of 0.05 (95% confidence level).

scholarly journals A Hybrid Method of Determining Deformations of Engineering Structures with a Laser Station and a 3D Scanner

2018 ◽  
Vol 28 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Jacek Sztubecki ◽  
Adam Bujarkiewicz ◽  
Karol Derejczyk ◽  
Michał Przytuła
Keyword(s):  
High Accuracy ◽  
Control Network ◽  
Structural Components ◽  
3D Scanner ◽  
Engineering Structures ◽  
Vertical Displacements ◽  
Measurement Methodology ◽  
Analysis Of Results ◽  
Deformation Measurements

Abstract The article presents the technology and an analysis of results of engineering structure displacements and deformation measurements. Two measuring technologies using the TDRA65000 laser station from Leica and the FARO Focus M scanner were applied during the tests. Use of the laser station enabled us to define horizontal and vertical displacements of a control network established on the tested facility. Owing to this, it was also possible to transform scanner measuring stations into one integrated unit. The described measurement methodology ensures a high accuracy of scanner station fitting which translates directly into the accuracy of determination of deformations in structural components of a facility. Integration of methods applied in the tests makes it possible to monitor not only displacements of control network points but also the structure as a whole in a uniform coordinate system.

scholarly journals CRITERION FOR COMPARING THE VARIANCE COMPONENT ESTIMATION METHODS USED FOR ADJUSTING HORIZONTAL CONTROL NETWORKS

2012 ◽  
Vol 32 (1) ◽  
pp. 6-13
Author(s):  
Erol Yavuz ◽  
Orhan Baykal
Keyword(s):  
Stochastic Model ◽  
Variance Component ◽  
Statistical Tests ◽  
Estimation Methods ◽  
Variance Component Estimation ◽  
Control Networks ◽  
Component Estimation ◽  
Using Data ◽  
Horizontal Control

Determination of which stochastic model taken in hand for this study is suitable under conditions, when comparing stochastic models, used for adjusting horizontal control networks, is the aim of this study. Some well-known variance component estimation methods like Conventional, Helmert, MTNQUE, AUE, and Förstner, which have been developed to determine the stochastic model, necessary to be formed in a real way for adjusting geodetic nets, have been compared. For comparing the models mentioned above, concrete deciding criteria, using statistical tests, have been defined and the determination of which model is superior has been studied. For comparison of the models, numerical experiment using data, which belong to the part of Istanbul Metropolitan Triangulation Network (Asiatic side of Istanbul), has been performed.

scholarly journals Comparison of PET [15O]Water Studies with 6-Minute and 10-Minute InterScan Intervals: Single-Subject and Group Analyses

1999 ◽  
Vol 19 (5) ◽  
pp. 570-582 ◽  
Author(s):  
Jolanta Chmielowska ◽  
Robert C. Coghill ◽  
Richard E. Carson ◽  
Kenji Ishii ◽  
Robert Chen ◽  
...  
Keyword(s):  
Statistical Power ◽  
Statistical Significance ◽  
Group Analysis ◽  
Statistical Parametric Mapping ◽  
Brain Regions ◽  
Single Subject ◽  
Local Variance ◽  
Study Duration ◽  
Minute Interval ◽  
Variance Estimate

The authors recently showed that [15O]water PET data obtained with a short interscan interval (6 minutes) produced similar results whether or not the residual background from the previous scan is subtracted. The purpose of the present study was to compare scans obtained during motor activation using a short (6-minute) interscan interval protocol with those obtained with a standard (10-minute) protocol in the same scanning session. Single-subject and group analyses were performed using Worsley's method, which uses a pooled variance estimate and statistical parametric mapping with a local variance estimate. High consistency in both the activation maps, i.e., the number of activated motor brain structures and the Talairach coordinates of peak intensities of the activated regions, was obtained in the 6- and 10-minute studies in both single-subject and group analyses. However, in comparison to the 6-minute studies, a larger cluster size of activated brain regions and an approximately 20% higher peak activation in these regions were observed in the 10-minute studies with the same number of replicates. Analysis of these results suggests that using a 6-minute interval with an increased number of replications, i.e., without changing the subject's total study duration, should produce comparable statistical power to that of the 10-minute interval for group analysis and increased statistical power for single-subject analyses that use a local variance estimate because of increased degrees of freedom. Alternatively, with a small increase in the number of scans and the use of a 6-minute interscan interval, a comparable level of statistical significance may be achieved for single-subject experiments that use a local variance estimate, with an overall shortening of the study duration.

Resurvey and Analysis of GPS Horizontal Network for WZ Bridge

2014 ◽  
Vol 638-640 ◽  
pp. 2169-2173
Author(s):  
Cheng Li ◽  
Xi Xu
Keyword(s):  
Precision Measurement ◽  
Control Network ◽  
Observation Data ◽  
Directed Edge ◽  
Short Side ◽  
Control Networks ◽  
Engineering Control ◽  
Chongqing City ◽  
Mountainous River ◽  
Horizontal Network

This paper discusses the resurvey conditions of the GPS horizontal network for WZ Bridge in Wanzhou District, Chongqing City, China. Through the adjustment of the observation data, this paper shows that using the short side as the lofting directed edge in high-precision lofting should be avoided. Further, resurvey results show that the control network accuracy can meet standard requirements. The control network can be used for precision measurement in the anti-collision facilities installation engineering of WZ Bridge, and can also be a reference for other engineering control networks in mountainous river areas.

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