The dependence of coordinate measurements error of the geometric elements shape characteristics of products on the control points number

Metrologiya ◽  
2021 ◽  
pp. 4-21
Author(s):  
M. F. Danilov ◽  
A. P. Ivanova
Keyword(s):  
A Priori ◽  
Analytical Models ◽  
Confidence Probability ◽  
Control Points ◽  
Regular Structures ◽  
Coordinate Metrology ◽  
Analytical Formulas ◽  
Coordinate Measurements ◽  
Shape Characteristics ◽  
Geometric Elements

The issues of estimating the error of coordinate measurements of the shape characteristics of geometric elements of products depending on the number of control points, taking into account a given confidence probability, are considered. Analytical models are proposed for estimating the error based on a priori data, similar to estimating uncertainty by type B. The correspondence of model and experimental results is verified by the Monte Carlo method using a specially developed program in VBA and the library functions of the Statistical Analysis package of the Microsoft Excel program. Such a characteristic of the shape of the part as roundness is investigated. The influence of the parameters of regular structures associated with the features of the technological processes of manufacturing the part on the parameters of the distribution function of the coordinates of the control points is revealed. Fourier analysis is used to identify and quantify regular structures on the surface of the part. The sources of error that have a significant impact on the results of measurements of the shape characteristics of geometric elements of products are given. Based on the results of statistical calculations, the dependence of the measurement error of the shape characteristics on the number of control points is analyzed, the scope of application of analytical formulas for estimating the error of single measurements for a given confidence probability is determined. The article is intended for specialists in the field of practical coordinate metrology and related fields.

Criteria for evaluation of the coordinate measurements quality of parts geometric parameters at pilot-experimental production

2019 ◽  
pp. 3-8
Author(s):  
N.Yu. Bobrovskaya ◽  
M.F. Danilov
Keyword(s):  
Quality Indicators ◽  
Quality Management System ◽  
Technical Specification ◽  
Experimental Production ◽  
Technological Heredity ◽  
Coordinate Measurements ◽  
Reasonable Choice ◽  
The Stability ◽  
Geometric Elements

The criteria of the coordinate measurements quality at pilot-experimental production based on contemporary methods of quality management system and traditional methods of the measurements quality in Metrology are considered. As an additional criterion for quality of measurements, their duration is proposed. Analyzing the problem of assessing the quality of measurements, the authors pay particular attention to the role of technological heredity in the analysis of the sources of uncertainty of coordinate measurements, including not only the process of manufacturing the part, but all stages of the development of design and technological documentation. Along with such criteria as the degree of confidence in the results of measurements; the accuracy, convergence, reproducibility and speed of the results must take into account the correctness of technical specification, and such characteristics of the shape of the geometric elements to be controlled, such as flatness, roundness, cylindrical. It is noted that one of the main methods to reduce the uncertainty of coordinate measurements is to reduce the uncertainty in the initial data and measurement conditions, as well as to increase the stability of the tasks due to the reasonable choice of the basic geometric elements (measuring bases) of the part. A prerequisite for obtaining reliable quality indicators is a quantitative assessment of the conditions and organization of the measurement process. To plan and normalize the time of measurements, the authors propose to use analytical formulas, on the basis of which it is possible to perform quantitative analysis and optimization of quality indicators, including the speed of measurements.

Foot-mounted Pedestrian Navigation based on Particle Filter with an Adaptive Weight Updating Strategy

2014 ◽  
Vol 68 (1) ◽  
pp. 23-38 ◽  
Author(s):  
Yang Gu ◽  
Qian Song ◽  
Yanghuan Li ◽  
Ming Ma
Keyword(s):  
Particle Filter ◽  
A Priori ◽  
Close Relation ◽  
Building Structures ◽  
New Approach ◽  
Pedestrian Navigation ◽  
Regular Structures ◽  
Time Varying Parameter ◽  
Adaptive Weight

The algorithm flow of an inertial-based Pedestrian Navigation System (PNS) can be divided into a trajectory-generation stage and trajectory-calibration stage. The Zero-velocity UPdaTe (ZUPT)-aided Extended Kalman Filter (EKF) algorithm is commonly used to resolve the trajectory of a walking person, but it still suffers from long-term drift. Many methods have been developed to suppress these drifts and thus to calibrate the trajectory generated by the previous stage. However, these methods have certain requirements, such as explicit map information or frequent location revisits, which are hard to satisfy in such situations as Search and Rescue (SAR) operations. A new approach is proposed in this paper that requires no explicit presupposition. This approach is based on a particle filter framework, with the weight of particles being adaptively adjusted according to the a priori knowledge of building structures and human behaviours. The distribution of particle weights is designed with awareness of the regular structures of buildings. The time-varying parameter of the distribution is acquired from a Hidden Markov Model (HMM) based on the foregoing odometry, which has a close relation with human behaviour. HMM is trained offline based on samples acquired in advance. Many real-world experiments under various scenarios were performed, and the results indicate good accuracy and robustness of the proposed approach.

scholarly journals An analytical model for predicting the natural frequency of retaining structures

2020 ◽  
Vol 15 (1) ◽  
pp. 7-12
Author(s):  
Lyazid Guechi ◽  
Smaïn Belkacemi
Keyword(s):  
Natural Frequency ◽  
Analytical Model ◽  
Current Model ◽  
Accurate Determination ◽  
Analytical Models ◽  
Retaining Structures ◽  
The Earth ◽  
Earth Pressures ◽  
Analytical Formulas ◽  
Failure Wedge

Abstract The importance of the retaining structures is crucial in geotechnical engineering and the accurate determination of static and seismic earth pressures and natural frequency is important for study the dynamic behavior of these structures. Usually analytical formulas which do not consider the earth pressures behind retaining structure are used. An analytical model for predicting the natural frequency of retaining structures including the earth pressures by failure wedges is proposed in the present analysis. The model considers the effect of Coulomb and Mononobe Okabe failure wedges. Backfill material is considered in the analysis as cohesionless. The failure wedge is an important factor which should be considered in determining the natural frequency of retaining structures. As the weight of failure wedge increases the natural frequency decreases significantly. The current model is validated using several analytical models reported in the literature of the earlier researcher.

Critical fluid volumes and the start of 'self-sustaining' fracture ascent

2020 ◽  
Author(s):  
Timothy Davis
Keyword(s):  
A Priori ◽  
Laboratory Data ◽  
Theoretical Models ◽  
Three Dimensions ◽  
Analytical Models ◽  
Conservative Estimate ◽  
Industrial Data ◽  
Fluid Properties ◽  
Asymmetric Growth ◽  
Natural Settings

<p>In theory, pockets of fluid in brittle media can be transported large distances, provided that both the fluid volume is large enough, such that fluid pressures can fracture the rock, and that stress gradients exist causing asymmetric growth of the fracture's front. Currently, industrial injections are deemed safe based on empirical observations of volumes, rates and pressures from closed-access industrial data. Existing theoretical models are difficult to use a priori to predict the critical volume of fluid that will cause unhindered fracture ascent, as they are expressed in terms of the fracture’s length, which is hard to predict a priori and difficult to measure. Here we constrain scale-independent critical volumes as a function of only rock and fluid properties by supplementing simple analytical models with numerical simulations in three dimensions. We apply our model to laboratory and natural settings, showing that the volumes we estimate match well with laboratory data and can be used as a conservative estimate in geological applications.</p>

scholarly journals Influence of soil particle shape on saturated hydraulic conductivity

2017 ◽  
Vol 65 (1) ◽  
pp. 80-87 ◽  
Author(s):  
Zofia Zięba
Keyword(s):  
Hydraulic Conductivity ◽  
Particle Shape ◽  
Pore Diameter ◽  
Grain Shape ◽  
Saturated Hydraulic Conductivity ◽  
Analytical Models ◽  
Particle Structure ◽  
Constant Head ◽  
Shape Characteristics ◽  
The Relationship

AbstractThe aim of this paper is to define the correlation between the geometry of grains and saturated hydraulic conductivity of soils. The particle shape characteristics were described by the ζ0Cindex (Parylak, 2000), which expresses the variability of several shape properties, such as sphericity, angularity and roughness.The analysis was performed on samples of four soils, which were characterised by the same grain size distribution and extremely different particle structure. The shape characteristics varied from ideally spherical, smooth grains (glass microbeads GM) to highly irregular and rough particles (fly ash FA).For each soil, laboratory tests of saturated hydraulic conductivity (constant head test CHT and falling head test FHT) were performed. Additionally, an empirical analysis of effective pore diameter was conducted with use of the analytical models developed by Pavchich (Wolski, 1987) and Indraratna and Vafai (1997). The models were modified by introducing the ζ0Cindex.Experiments have shown that saturated hydraulic conductivity depends on grains shape and surface roughness. This parameter decreases with the increase in the irregularity of soil particles. Moreover, it was proven that the ζ0Creflects the relationship between effective pore diameter and grain shape characteristics.

scholarly journals Validation of Digital Elevation Models around Merapi Volcano, Java, Indonesia

2005 ◽  
Vol 5 (6) ◽  
pp. 863-876 ◽  
Author(s):  
C. Gerstenecker ◽  
G. Läufer ◽  
D. Steineck ◽  
C. Tiede ◽  
B. Wrobel
Keyword(s):  
Digital Elevation Models ◽  
A Priori ◽  
High Accuracy ◽  
Ground Control ◽  
Control Points ◽  
Mountainous Region ◽  
Merapi Volcano ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Wide Range

Abstract. The accuracy of 4 Digital Elevation Models (SRTM30, GTOPO30, SRTM3 and local DEM produced from aerial photogrammetric images) for the volcanoes Merapi and Merbabu in Java, Indonesia is investigated by comparison with 443 GPS ground control points. The study confirms the high accuracy of SRTM3 and SRTM30, even if the a priori defined 90% confidence level of 16 m for the SRTM3 is not always achieved in this mountainous region. Accuracy of SRTM30, GTOPO30 and SRTM3 is mainly dependent on the altitude itself and the slopes' inclinations, whereas the photogrammetric DEM exhibits constant accuracy over a wide range of altitudes and slopes. For SRTM3 and SRTM30 a statistically significant correlation between heights and aspects of the slopes is also found. Accuracy of DEMs which are generated by interpolation on a finer grid does not change significantly. Smoothing of DEMs on a coarser grid, however, decreases accuracy. The decrease in accuracy is again dependent on altitude and slope inclination. The comparison of SRTM30 with GTOPO30 exhibits a significant improvement of SRTM30 data.

Sign in / Sign up

Export Citation Format

Share Document