Evaluation of Geometric Elements of Repeat Station Imaging and Registration

2016 ◽  
Vol 82 (10) ◽  
pp. 775-789 ◽  
Author(s):  
Douglas A. Stow ◽  
Lloyd C. Coulter ◽  
Christopher D. Lippitt ◽  
Garrick MacDonald ◽  
Richard McCreight ◽  
...  
Keyword(s):  
Repeat Station ◽  
Geometric Elements

Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering

1970 ◽  
Vol 28 ◽  
pp. 360-361
Author(s):  
John W. Coleman
Keyword(s):  
Boundary Conditions ◽  
High Performance ◽  
Force Fields ◽  
Optical Design ◽  
Direct Conversion ◽  
Design Engineering ◽  
Design Data ◽  
Scalar Potentials ◽  
Geometric Elements ◽  
At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force 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.

Chebyshev approximation to data by geometric elements

1993 ◽  
Vol 5 (10) ◽  
pp. 509-522 ◽  
Author(s):  
Rudolf Drieschner
Keyword(s):  
Chebyshev Approximation ◽  
Geometric Elements

The Geometrical Feature Recognition Method of Part Drawing

2011 ◽  
Vol 415-417 ◽  
pp. 523-526
Author(s):  
Yan Dong ◽  
Mei Li
Keyword(s):  
Feature Recognition ◽  
Graph Matching ◽  
Geometric Feature ◽  
Recognition Method ◽  
Recognition Mechanism ◽  
Chemical Database ◽  
Geometry Feature ◽  
Constraint Structure ◽  
Geometric Elements ◽  
Fine Tune

This paper put forward a geometry feature recognition method of part drawing based on graph matching. Describe the constraints structure of geometric feature in geometric elements and those constraint relationships. Match sub-graph in contour closure graphics and those combination. Using linear symbol notation of chemical compounds in chemical database for reference, encode to constraint structure of geometry graphics, establish recognition mechanism of geometric characteristics by structure codes. Taking the fine-tune screw and fork parts for example, this method has been proved to be effective.

Research on Situated Reconstitution of Non-Manifold Polyhedral from Function-to-Form Mapping

2013 ◽  
Vol 774-776 ◽  
pp. 1766-1769
Author(s):  
Zhi Gang Xu ◽  
Zi Xiang Li ◽  
Jin Wang ◽  
Tao Tao Liu ◽  
Chun Po Sun
Keyword(s):  
Design Automation ◽  
Algebraic Reasoning ◽  
Top Down ◽  
Automation Systems ◽  
Geometric Elements

Situated reconstitution is proposed in this paper to cope with un-manifold polyhedral from the function to form mapping processes. Specifically the situated reconstitution is not simply re-arrangement of geometric elements, mainly face entities in the un-manifold polyhedral, rather it needs a complex geometric/algebraic reasoning to reconstitute a manifold object, novel mathematical as well as AI techniques are introduced in this paper, several tools are developed to testify the proposed situated reconstitution in the “top-down” design automation systems.

FEASIBILITY STUDY OF GEOMETRIC ELEMENTS OF ROAD SURFACES

2021 ◽  
Vol 14 (1) ◽  
pp. 41-45
Author(s):  
Sergey Yu. Sablin ◽  
Aleksey V. Skrypnikov ◽  
Irina A. Vysotskaya ◽  
Denis E. Boltnev ◽  
Andrey N. Bryukhovetsky
Keyword(s):  
Feasibility Study ◽  
Road Surfaces ◽  
Geometric Elements

Kinematic Fixturing With Respect to a Plane Using Contact Sensing

1998 ◽  
Author(s):  
Walter W. Nederbragt ◽  
Bahram Ravani
Keyword(s):  
Spatial Constraint ◽  
Spatial Constraints ◽  
Constraint Equations ◽  
Contact Sensing ◽  
Geometric Elements ◽  
Work Cells

Abstract This paper presents a method for determining the location of geometric elements that compose the external features of referencing fixtures. Since in most applications parts that are handled in robotic work-cells are on a worktable or a floor, this paper focuses on fixture geometries that reside on a plane of known location. The location of the unknown geometric elements are found using contacts to the geometric elements and spatial constraints between the geometric elements. Geometric equations for contacts between lines, planes, points, spheres, and cylinders are derived. Spatial constraint equations are also derived. An algorithm is given for locating the geometric elements that form the fixture. The algorithm uses the contact equations and spatial constraint equations to locate the geometric elements. To illustrate the use of this algorithm, two examples are described in detail.

Enumeration of Contact Geometries for Kinematic Registration Using Tactile Sensing Fixtures

2005 ◽  
Vol 128 (1) ◽  
pp. 34-45 ◽  
Author(s):  
Walter W. Nederbragt ◽  
Bahram Ravani
Keyword(s):  
Group Theory ◽  
Data Driven ◽  
Tactile Sensing ◽  
Geometric Features ◽  
Type Synthesis ◽  
Robot Calibration ◽  
Planar Surfaces ◽  
Spherical Surfaces ◽  
Kinematic Registration ◽  
Geometric Elements

This paper uses group theory for enumeration of contacts between geometric elements necessary for kinematic registration or part referencing in robotics. The results are applied to type synthesis of tactile sensing mechanical fixtures. Kinematic registration is an important step in robot calibration and in data driven automation. Although the scope of the paper is limited to geometric contacts involving points, lines, planar surfaces, cylindrical surfaces, and spherical surfaces, the techniques developed are general and can be applied to other geometric features and non-tactile sensing elements used in robotic calibration and part referencing.

scholarly journals Repeat station data compared to a global geomagnetic field model

2013 ◽  
Vol 55 (6) ◽  
Author(s):  
Monika Korte ◽  
Vincent Lesur
Keyword(s):  
Magnetic Field ◽  
Secular Variation ◽  
Global Model ◽  
Time Interval ◽  
Night Time ◽  
Core Field ◽  
Repeat Station ◽  
Station Data ◽  
Long Term Trends

<p>Geomagnetic repeat station surveys with local variometers for improved data reductions have been carried out in Germany for about ten years. For nearly the same time interval the satellites Ørsted and CHAMP have provided a good magnetic field data coverage of the whole globe. Recent global field models based on these satellite data together with geomagnetic observatory data provide an improved description of the core field and secular variation. We use the latest version of the GFZ Reference Internal Magnetic Model to compare the magnetic field evolution predicted by that model between 2001 and 2010 to the independent repeat station data collected over the same time interval in Germany. Estimates of crustal bias at the repeat station locations are obtained as averages of the residuals, and the scatter or trend around each average provides information about influences in the data from field sources not (fully) described by the global model. We find that external magnetic field signal in the order of several nT, including long-term trends, remains both in processed annual mean and quiet night time repeat station data. We conclude that the geomagnetic core field secular variation in this area is described to high accuracy (better than 1 nT/yr) by the global model. Weak long-term trends in the residuals between repeat station data and the model might indicate induced lithospheric anomalies, but more data are necessary for a robust analysis of such signals characterized by very unfavorable signal-to-noise ratio.</p>

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