Coordinate Reference Research Articles

Three-Dimensional Large Deformation Analysis of the Multibody Pantograph/Catenary Systems

To accurately model the nonlinear behavior of the pantograph/catenary systems, it is necessary to take into consideration the effect of the large deformation of the catenary and its interaction with the nonlinear pantograph system dynamics. The large deformation of the catenary is modeled in this investigation using the three-dimensional finite element absolute nodal coordinate formulation. To model the interaction between the pantograph and the catenary, a sliding joint that allows for the motion of the pan-head on the catenary cable is formulated. To this end, a non-generalized arc-length parameter is introduced in order to be able to accurately predict the location of the point of contact between the pan-head and the catenary. The resulting system of differential and algebraic equations formulated in terms of reference coordinates, finite element absolute nodal coordinates, and non-generalized arc-length and contact surface parameters are solved using computational multibody system algorithms. A detailed three-dimensional multibody railroad vehicle model is developed to demonstrate the use of the formulation presented in this paper. In this model, the interaction between the wheel and the rail is considered. For future research, a method is proposed to deal with the problem of the loss of contact between the pan-head and the catenary cable.

Applications of centroid coordinates for cell image analysis system in ASIPP microbeam

A single-particle microbeam facility has been constructed at the Key Laboratory of Ion Beam Bioengineering of Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). In the image analysis system, the centroid coordinates of each cell are important features of cell images. For irradiation of nuclei, the centroid coordinates of each nucleus are reference coordinates for the points (the centroid itself or some neighbouring points of the centroid at a specific distance from it) to be irradiated. After the coordinates have been calculated, the irradiation points are found relative to the position of the beam exit aperture, and each cell is then positioned over the exit aperture by stepping motors driving a sample plate. Furthermore, in image acquisition, because the size of an image is limited, cells on the cell plate cannot all be scanned in one image. Therefore, the cell dish is divided into several overlapping districts to be acquired. Centroid coordinates are also a useful application for acquisition and recognition of overlapped images. The scheme and operational procedures for acquiring images accurately and recognizing cells are described; the feasibility and validity of the scheme are also discussed using an example.

A Compendium of Directional Calculations Based on the Minimum Curvature Method

Summary The minimum curvature method has emerged as the accepted industry standard for the calculation of 3D directional surveys. Using this model, the well' strajectory is represented by a series of circular arcs and straight lines. Collections of other points, lines, and planes can be used to represent features such as adjacent wells, lease lines, geological targets, and faults. The relationships between these objects have simple geometrical interpretations, making them am enable to mathematical treatment. The calculations are now used extensively in 3D imaging and directional collision scans, making them critical for both business and safety. However, references for the calculations are incomplete, scattered in the literature, and have no systematic mathematical treatment. These features make programming a consistent and reliable set of algorithms more difficult. Increased standardization is needed. Investigation shows that iterative schemes have been used in situations in which explicit solutions are possible. Explicit calculations are preferred because they confer numerical predictability and stability. Though vector methods were frequently adopted in the early stages of the published derivations, opportunities for simplification were missed because of premature translation to Cartesian coordinates. This paper contains a compendium of algorithms based on the minimum curvature method (includes coordinate reference frames, toolface, interpolation, intersection with a target plane, minimum and maximum true vertical depth (TVD) in a horizontal section, point closest to a circular arc, survey station to a target position with and without the direction defined, nudges, and steering runs). Consistent vector methods have been used throughout with improvements in mathematical efficiency, stability, and predictability of behavior. The resulting algorithms are also simpler and more cost effective to code and test. This paper describes the practical context in which each of the algorithms is applied and enumerates some key tests that need to be performed.

New Local Transformation Method: Non-Sibsonian Transformation

Coordinate transformations refer to mathematical processing that enables overlay of digital maps that use different coordinate reference systems, that is, map projections. The transformation from geographical to map (plane) coordinates is the conventional practice in cartography, which is called forward transformation. The inverse transformation, which yields geographical coordinates from map coordinates, is a more recent development, due to the need for transformation between different map projections, especially in geographic information systems (GIS). The combination of the inverse and forward transformation from one projection to another, which may be called grid-on-grid or map-to-map transformation, can be necessary for some custom applications in GIS and in automated cartography. Many different approximation algorithms can be used for this problem on desktop computers. In this paper a new local transformation method called a non-Sibsonian transformation, which uses non-Sibson local coordinates, is suggested for map-to-map transformation or for improving geometrical accuracy of scanned maps. A case study is performed using the Lambert conformal conic projection and is presented with results.

Study on the Reference Coordinate System of

This paper reports a visualizing methodology of magnetic field vector distribution and its applications. The vector fields are visualized as the color images by projecting the x, y, and z components in each of the vectors to the red, green, and blue components of light, respectively. However, this visualizing methodology of vector fields has the problem that the visualized images always depend on the reference coordinate. Therefore, we have noticed to the current distributions that is the magnetic field source. As a result, we propose here a deterministic decision methodology of the reference coordinate along with current vector. Thereby, it is shown that the magnetic field vector distributions on the reference coordinate system can be uniquely visualized.As an application of our vector field visualizing methodology, we apply our method to a vector field recognition problem. As a result, we have succeeded in carrying out the machine diagnosis of the vector field.

3D Co-ordinate Comparator Using Reference Workpiece

被測定工作物と同じ幾何学的形状および材質を持つ標準工作物との比較測定に基づく表記測定機を開発し, 主に長さの比較測定精度について調査した. 300mmまでの比較測定を行った結果, 約±1μmの偏差および標準偏差約0.5～1μmが得られた. 測定長が増えても誤差の増加は観察されなかった. また被測定工作物を測定する直前に標準工作物の測定を行うことにより室温変動の影響を排除できる.

One approach to the integration of inertial and visual navigation systems

The algorithm of simultaneous estimation of motion parameters and scene structure using the integrated navigation system consisting from inertial sensors (three rate gyros and three accelerometers) and TV camera has been presented. All mentioned sensors are rigidly fixed to the body of a moving object. It is assumed that the inertial sensors are characterized by constant biases. The recognizable landmarks existing in the scene on known locations in the reference coordinate frame are assumed also. It is enabled by parallel processing of information in two independent navigation systems that they may correct each other, in order to estimate moving object?s linear and angular position relative to the landmark as well as it?s linear and angular velocities in an optimal fashion.

A VISION-MEASURING METHOD FOR AN IMPERFECT CIRCLE

ABSTRACT The positioning center of the circular hole of PCB and the reference coordinates of welding by optical point in the manufacture process of the semiconductor components will cause the circle deformed and will create image noise or blurred image when the image from CCD camera is grabbed by the different lighting method or light source. When the surface of objects inspected reflect the light, it will cause the error of center positioning. This paper proposes a 4-points mode number method for the center positioning to overcome the problem of the measurement of the imperfect circle. The results of simulation and experiments indicate that this method is feasible and it can measure accurately the coordinates of the center of the circle which is covered by the other objects or is deformed over sixty degrees. Based on experiments, it is known that the 4-points mode method is faster and more accurate than the area, 3-points, contour-tracking and least-squares error methods of center-positioning.

施工管理に活用できる道路構造物の基本設計情報の構造化

This research proposes a model of basic design information for more correct, flexible and compact representation of road structures. Using basic design information based on this model, we can not only improve the efficiency of design works of road and the construction management, but decrease mistakes and achieve higher level of quality assurance. The basic design information can also allow using of the coordinate data developed in design phase effectively for the construction works. In addition, coordinate data can be exchanged, together with the definition of coordinate reference system. It makes possible to exchange complex design information between CAD systems and the surveying equipments. To use the data in surveying equipments, the model can make the data size small.

Realtime Three-dimensional Echocardiography – A Perspective

Introduction The heart is a dynamic organ and places special demands on three-dimensional (3-D) techniques. To understand its physiology and pathophysiology, not only the spatial distribution of its structures is important but also their movement during the cardiac cycles. Previous approaches to 3-D echocardiography (3-DE) were offline and based on sequential rotational scanning and acquisition of multiple cross-sectional images together with their spatial position using internal co-ordinate reference systems.

Adaptive sliding control of non-autonomous active suspension systems with time-varying loadings

An adaptive sliding controller is proposed in this paper for controlling a non-autonomous quarter-car suspension system with time-varying loadings. The bound of the car-body loading is assumed to be available. Then, the reference coordinate is placed at the static position under the nominal loading so that the system dynamic equation is derived. Due to spring nonlinearities, the system property becomes asymmetric after coordinate transformation. Besides, in practical cases, system parameters are not easy to be obtained precisely for controller design. Therefore, in this paper, system uncertainties are lumped into two unknown time-varying functions. Since the variation bound of one of the unknown functions is not available, conventional adaptive schemes and robust designs are not applicable. To deal with this problem, the function approximation technique is employed to represent the unknown function as a finite combination of basis functions. The Lyapunov direct method can thus be used to find adaptive laws for updating coefficients in the approximating series and to prove stability of the closed-loop system. Since the position and velocity measurements of the unsprung mass are lumped into the unknown function, there is no need to install sensors on the axle and wheel assembly in the actual implementation. Simulation results are presented to show the performance of the proposed strategy.

An innovative image-guided radiotherapy system with a quasi-nonisocenteric feature

An innovative image-guided radiotherapy system with a quasi-nonisocenteric feature

Dynamic analysis of shaker mixers and an asymmetrical twin-container design

The container of a shaker mixer follows a complicated movement. The movement of the mixer is described using six coordinates. Important parameters such as the relative angles and the angular speeds of the main parts of the mixer in the movement are calculated. Expressions for the centroid positions of the main parts of the mixer and the centroid velocity components of the container in the static reference coordinates are given. Using a dynamic analysis of the shaker mixer, the method for calculating the power required for an asymmetrical twin-container shaker mixer is described. An energy-saving design of an asymmetrical twin-container shaker mixer is presented.

C-arm based navigation in total hip arthroplasty—background and clinical experience

After experimental and preclinical evaluation of a CT-free image guided surgical navigation system for acetabular cup placement, the system was introduced into clinical routine. The computation of the angular orientation of the cup is based on reference coordinates from the anterior pelvic plane concept. A hybrid strategy for pelvic landmark acquisition has been introduced, involving percutaneous pointer-based digitization with the noninvasive bi-planar landmark reconstruction using multiple registered fluoroscopy images. From January 2001 to October 2003, a total of 236 consecutive patients (mean age 66 years, 144 male, 92 female, 124 left and 112 right hip joints) were operated on with the hybrid CT-free navigation system. During each operation, the angular orientation of the inserted implant was recorded. To determine the placement accuracy of the acetabular components, the first 50 consecutive patients underwent a CT scan 7-10 days postoperatively to analyze the cup position relative to the anterior pelvic plane. This procedure was done blinded and with commercial planning software. There was no significant learning curve observed for the use of the system. Mean values for postoperative inclination read 42 degrees (SD 3.6, range (37-49)) and anteversion 21 degrees (SD 3.9, range (10-28)). The resulting system accuracy, ie, the difference between intraoperatively calculated cup orientation and postoperatively measured implant position shows a maximum error of 5 degrees for the inclination (mean 1.5 degrees, SD 1.1) and 6 degrees for the anteversion (mean 2.4 degrees, SD 1.3). An accuracy of better than 5 degrees inclination and 6 degrees anteversion was achieved under clinical conditions, which implies that there is no significant difference in performance from the established CT-based navigation methods. Image-guided CT-free cup navigation provides a reliable solution for future total hip arthroplasty (THA).

The present and future management of malignant brain tumours: surgery, radiotherapy, chemotherapy

While the majority of malignant brain tumours remain ultimately incurable, a variety of intermediate outcomes is nevertheless possible, depending on histological tumour type and grade. A common treatment strategy obtains...

A General Framework for the Selection of World Coordinate Systems in Perspective and Catadioptric Imaging Applications

An imaging system with a single effective viewpoint is called a central projection system. The conventional perspective camera is an example of central projection system. A catadioptric realization of omnidirectional vision combines reflective surfaces with lenses. Catadioptric systems with an unique projection center are also examples of central projection systems. Whenever an image is acquired, points in 3D space are mapped into points in the 2D image plane. The image formation process represents a transformation from ℜ3 to ℜ2, and mathematical models can be used to describe it. This paper discusses the definition of world coordinate systems that simplify the modeling of general central projection imaging. We show that an adequate choice of the world coordinate reference system can be highly advantageous. Such a choice does not imply that new information will be available in the images. Instead the geometric transformations will be represented in a common and more compact framework, while simultaneously enabling newer insights. The first part of the paper focuses on static imaging systems that include both perspective cameras and catadioptric systems. A systematic approach to select the world reference frame is presented. In particular we derive coordinate systems that satisfy two differential constraints (the “compactness” and the “decoupling” constraints). These coordinate systems have several advantages for the representation of the transformations between the 3D world and the image plane. The second part of the paper applies the derived mathematical framework to active tracking of moving targets. In applications of visual control of motion the relationship between motion in the scene and image motion must be established. In the case of active tracking of moving targets these relationships become more complex due to camera motion. Suitable world coordinate reference systems are defined for three distinct situations: perspective camera with planar translation motion, perspective camera with pan and tilt rotation motion, and catadioptric imaging system rotating around an axis going through the effective viewpoint and the camera center. Position and velocity equations relating image motion, camera motion and target 3D motion are derived and discussed. Control laws to perform active tracking of moving targets using visual information are established.

Datum Definition in the Long Range Instantaneous RTK GPS Network Solution

This paper presents the multiple reference station approach to wide area (and regional) instantaneous RTK GPS, implemented in the MPGPSTM (Multi Purpose GPS Processing Software) software, developed at the Ohio State University. A weighted free-net approach (WFN) was applied in the instantaneous RTK software module, which enabled optimal estimation of the rover coordinates, properly reflecting the accuracies of the observations and the coordinates of the CORS stations. The effect of using the distance-dependent weighting scheme in the WFN approach on the final rover solution is analyzed. The influence of the different weights was studied by introducing the distance-dependent weights as a function of the CORS station separation L to the rover (1/L2). The results show that almost 100% of the differences between the computed horizontal rover coordinates and the known reference coordinates are below a decimeter, and 95% of the differences in the vertical coordinate are below 20 cm, when using the suggested approach. In addition, the accuracy analysis of two other solutions, with different datum definition (minimum constraint and over-constrained), is presented. This analysis verifies the suitability of the stochastic models used in the RTK module and the rigorous approach, taking into account inter-baseline correlation as well as the correlation in-between each baseline component.

North Atlantic Simulations with the Hybrid Coordinate Ocean Model (HYCOM): Impact of the Vertical Coordinate Choice, Reference Pressure, and Thermobaricity

The viability of a generalized (Hybrid) Coordinate Ocean Model (HYCOM), together with the importance of thermobaricity and the choice of reference pressure, is demonstrated by analyzing simulations carried out using the World Ocean Circulation Experiment (WOCE) Community Modeling Experiment (CME) Atlantic basin configuration. The standard hybrid vertical coordinate configuration is designed to remain isopycnic throughout as much of the water column as possible while smoothly making a transition to level (pressure) coordinates in regions with weak vertical density gradients, such as the surface mixed layer, and to terrain-following coordinates in shallow-water regions. Single-coordinate (pressure or density) experiments illustrate the flexibility of the model but also bring forward some of the limitations associated with such a choice. Hybrid experiments with potential density referenced to the surface ( su) and to 20 MPa (;2000 m) (s 2) illustrate the increased influence of pressure errors with increasing distance from the reference pressure. The su hybrid experiment does not properly reproduce the northward flow of Antarctic Bottom Water (AABW), and large errors in near-surface pressure gradients in the s 2 experiment produce a wind-driven gyre circulation that is too strong, when compared with observations, and a North Atlantic Current that follows an unrealistic path. These near-surface and nearbottom pressure errors are removed when thermobaric effects are included, resulting in a more accurate representation of the upper-ocean gyre circulation, the northward AABW flow near the bottom, and the meridional overturning circulation and heat flux.

GPS COMPATIBLE POSITIONING IN IRELAND (Part 1)

The paper describes the justification, realisation and implications of a change of coordinate reference system for Ireland It includes consideration of the science and the practicalities of the change, for both data providers and users. The development of a new coordinate reference system for Ireland has profound and positive implications for usability and accuracy of surveys in the future, but introduces significant transition issues which must be dealt with carefully.

GPS COMPATIBLE POSITIONING IN IRELAND (Part 1)

The paper describes the justification, realisation and implications of a change of coordinate reference system for Ireland It includes consideration of the science and the practicalities of the change, for both data providers and users. The development of a new coordinate reference system for Ireland has profound and positive implications for usability and accuracy of surveys in the future, but introduces significant transition issues which must be dealt with carefully.