scholarly journals A Conceptual Investigation of a Large Radio Telescope Support Point Number Effect on Its Pointing Accuracy

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Song Xue ◽  
Kaitong Ma ◽  
Congsi Wang ◽  
Peiyuan Lian ◽  
Yan Wang ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Least Square Method ◽  
Support Point ◽  
Least Square ◽  
Design Stage ◽  
Pointing Error ◽  
Large Radio Telescope ◽  
Point Number ◽  
Pointing Accuracy ◽  
Fourier Function

The purpose of this paper is to investigate a large radio telescope support point number effect on its pointing accuracy and provide a useful guideline for the large radio telescope design engineer. In a large radio telescope system, the azimuth track is used to support the whole telescope structure and the mounting error as well as the telescope wheel-track contact in a long term can cause unevenness on the azimuth track, which can further deteriorate the telescope pointing accuracy. Even though various compensation methods have been proposed to compensate for this pointing error, it remains as one of the challenges for the telescope pointing error reduction. In this paper, a general telescope pointing error estimation formula has been proposed to investigate different telescope support-point number designs on its pointing accuracy. In this approach, the azimuth track unevenness has been modelled as the Fourier function using the least square method after the raw track profile has been measured. Next, the elevation position matrix, azimuth position matrix, and the azimuth profile matrix can be constructed for different telescope support point numbers, and the telescope pointing error can then be obtained based on the proposed general formula. The telescope pointing error root mean square (RMS) value is used to quantify the effect of the telescope support point number on the pointing accuracy. Two interesting results can be observed in the numerical example. The first one is that the telescope pointing error curves have different dominant peaks during one azimuth track rotation, which is corresponding to the support point number. Another interesting finding is that the RMS value experienced a complex trend with the support point number change, and they are not a simple monotonous increasing or decreasing relationship with the support number. All the results in this paper can provide a useful guideline for reducing the telescope pointing error in the initial design stage.

Substructuring: Definition of the Analytical Dynamic Model of a Complex System During its Design Stage

1995 ◽  
Author(s):  
Fabrice Llorca ◽  
Alain Gerard ◽  
Denis Hennequin ◽  
Dominique Brenot
Keyword(s):  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Dynamic Properties ◽  
Least Square Method ◽  
Close Correlation ◽  
Least Square ◽  
Component Mode Synthesis ◽  
Design Stage ◽  
Synthesis Methods ◽  
Rectangular Plates

Abstract A structure is often an assembly of several components coupled by various joints such as bolted or riveted joints. Component mode synthesis methods are very practical tools to define a dynamic model. But, several points have to be examined and improved in order to give a complet representation of the modal behaviour of the whole structure. For example, rotational degrees of freedom on connecting points between adjacent substructures should be estimated to give a better representation of the multidirectional connecting forces. These informations may be evaluated through a method based on both interpolation and spatial derivation of the experimental translational displacements of the components. Unlike many other structural elements, the dynamic properties of a connection are very difficult to evaluate. So, we propose a method of determining joint stiffness characteristics. We consider only the conservative problem so the damping properties of the different components of the considered assembly are not taken into account. The joint characteristics are extracted comparing experimental modal data base and component mode synthesis simulation. The updating procedure is based on a nonlinear iterative least-square method. Results are presented concerning a particular assemblie of rectangular plates. Structural modification is applied for one component. We show that the joint properties stay the same if the connecting interface is not modified. The close correlation between predicted and experimental results demonstrate that this method is well adaptated to the study of structural modifications.

Effect of the rail unevenness on the pointing accuracy of large radio telescope

2017 ◽  
Vol 132 ◽  
pp. 13-18 ◽  
Author(s):  
Na Li ◽  
Jiang Wu ◽  
Bao-Yan Duan ◽  
Cong-Si Wang
Keyword(s):  
Radio Telescope ◽  
Large Radio Telescope ◽  
Pointing Accuracy

Research of 3D EFG of Limiting Nodal Point Number and Applied for Three-Dimensional Elastic Problem

2006 ◽  
Vol 306-308 ◽  
pp. 721-726 ◽  
Author(s):  
Dun Fu Zhang ◽  
Wei Shen Zhu ◽  
Shu Cai Li
Keyword(s):  
Nodal Point ◽  
Three Dimensional ◽  
Least Square Method ◽  
Variable Domain ◽  
Least Square ◽  
Global Approximation ◽  
Energy Principle ◽  
Moving Least Square ◽  
Nodal Points ◽  
Point Number

The formulation and implementation of three-dimensional element free Galerkin method (3D EFG) are developed. A simple and efficient scheme for a variable domain of influence stipulates that a constant number of nodal points are visible from each integration location is proposed. This method significantly increases the efficiency of the variable domain of influence by limiting the size of the least-square problem that is solved when computing approximate functions. The 3D EFG methods based on moving least square method use only nodal points to built local and global approximation. Discrete model of the 3D EFG for three-dimensional elastic problems is derived by least potential energy principle. Reference to the 2D EFG, in the 3D EFG, it is enforced to meet displacements boundary conditions by use of limiting nodal point number method and penalty method. The stress concentration of a small column-shaped cavity in a cube subjected to uniaxial uniform tension at two opposing faces in far field. Compared the approximation solutions with theory ones, the results indicate that the 3D EFG is validity in solving three-dimensional elastic problems and the limiting nodal point number method is validity.

scholarly journals High precision pointing error detection method for large radio telescope

2017 ◽  
Vol 47 (12) ◽  
pp. 129504 ◽  
Author(s):  
JinQing WANG ◽  
LinFeng YU ◽  
RongBing ZHAO ◽  
Michael KESTEVEN ◽  
Li FU ◽  
...  
Keyword(s):  
High Precision ◽  
Radio Telescope ◽  
Error Detection ◽  
Detection Method ◽  
Pointing Error ◽  
Large Radio Telescope

Direct Assessment of Effective Renal Plasma Flow from Renoscintigraphy with a Gamma Camera and an On-Line Computer

1981 ◽  
Vol 20 (06) ◽  
pp. 274-278
Author(s):  
J. Liniecki ◽  
J. Bialobrzeski ◽  
Ewa Mlodkowska ◽  
M. J. Surma
Keyword(s):  
Count Rate ◽  
Renal Plasma Flow ◽  
Early Period ◽  
Least Square Method ◽  
Least Square ◽  
Uptake Coefficient ◽  
Positive Linear Correlation ◽  
On Line ◽  
Best Fit ◽  
Plasma Activity

A concept of a kidney uptake coefficient (UC) of 131I-o-hippurate was developed by analogy from the corresponding kidney clearance of blood plasma in the early period after injection of the hippurate. The UC for each kidney was defined as the count-rate over its ROI at a time shorter than the peak in the renoscintigraphic curve divided by the integral of the count-rate curve over the "blood"-ROI. A procedure for normalization of both curves against each other was also developed. The total kidney clearance of the hippurate was determined from the function of plasma activity concentration vs. time after a single injection; the determinations were made at 5, 10, 15, 20, 30, 45, 60, 75 and 90 min after intravenous administration of 131I-o-hippurate and the best-fit curve was obtained by means of the least-square method. When the UC was related to the absolute value of the clearance a positive linear correlation was found (r = 0.922, ρ > 0.99). Using this regression equation the clearance could be estimated in reverse from the uptake coefficient calculated solely on the basis of the renoscintigraphic curves without blood sampling. The errors of the estimate are compatible with the requirement of a fast appraisal of renal function for purposes of clinical diagknosis.

PENGARUH KNOWLEDGE MANAGEMENT, KOMPETENSI, MOTIVASI TERHADAP KINERJA KARYAWAN

2015 ◽  
Vol 5 (2) ◽  
pp. 1
Author(s):  
Miftahol Arifin
Keyword(s):  
Knowledge Management ◽  
Linear Regression ◽  
Significant Influence ◽  
Employee Performance ◽  
Least Square Method ◽  
Least Square ◽  
Analysis Tool ◽  
Ordinary Least Square ◽  
Competence Motivation ◽  
Performance Analyze

The purpose of this research is to analyze the influence of knowledge management on employee performance, analyze the effect of competence on employee performance, analyze the influence of motivation on employee performance). In this study, samples taken are structural employees PT.centris Kingdom Taxi Yogyakarta. The analysis tool in this study using multiple linear regression with Ordinary Least Square method (OLS). The conclusion of this study showed that the variables of knowledge management has a significant influence on employee performance, competence variables have an influence on employee performance, motivation variables have an influence on employee performance, The analysis showed that the variables of knowledge management, competence, motivation on employee performance.Keywords: knowledge management, competence, motivation, employee performance.

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