scholarly journals TOPOLOGY MEASUREMENT OF SUBSTATION'S GROUNDING GRID BY USING ELECTROMAGNETIC AND DERIVATIVE METHOD

2016 ◽  
Vol 67 ◽  
pp. 71-90 ◽  
Author(s):  
Aamir Qamar ◽  
Fan Yang ◽  
Wei He ◽  
Ammad Jadoon ◽  
Muhammad Zeeshan Khan ◽  
...  
Keyword(s):  
Grounding Grid ◽  
Derivative Method

scholarly journals BREAKPOINT DIAGNOSIS OF SUBSTATION GROUNDING GRID USING DERIVATIVE METHOD

2017 ◽  
Vol 57 ◽  
pp. 73-80 ◽  
Author(s):  
Aamir Qamar ◽  
Nadir Shah ◽  
Zeeshan Kaleem ◽  
Zahoor Uddin ◽  
Farooq Alam Orakzai
Keyword(s):  
Grounding Grid ◽  
Derivative Method

scholarly journals Derivative Method Based Orientation Detection of Substation Grounding Grid

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1873 ◽  
Author(s):  
Aamir Qamar ◽  
Muhammad Umair ◽  
Fan Yang ◽  
Muhammad Uzair ◽  
Zeeshan Kaleem
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Critical Parameters ◽  
Magnetic Flux Density ◽  
Main Peak ◽  
Diagonal Branch ◽  
Grounding Grid ◽  
Derivative Method ◽  
Grounding Grids ◽  
Orientation Detection

The grounding grid is a key part of substation protection, which provides safety to personnel and equipment under normal as well as fault conditions. Currently, the topology of a grounding grid is determined by assuming that its orientation is parallel to the plane of earth. However, in practical scenarios, the assumed orientation may not coincide with the actual orientation of the grounding grid. Hence, currently employed methods for topology detection fails to produce the desired results. Therefore, accurate detection of grounding grid orientation is mandatory for measuring its topology accurately. In this paper, we propose a derivative method for orientation detection of grounding grid in high voltage substations. The proposed method is applicable to both equally and unequally spaced grounding grids. Furthermore, our method can also determine the orientation of grounding grid in the challenging case when a diagonal branch is present in the mesh. The proposed method is based on the fact that the distribution of magnetic flux density is perpendicular to the surface of the earth when a current is injected into the grid through a vertical conductor. Taking the third order derivative of the magnetic flux density, the main peak coinciding with the position of underground conductor is accurately obtained. Thus, the main peak describes the orientation of buried conductor of grounding grid. Simulations are performed using Comsol Multiphysics 5.0 to demonstrate the accuracy of the proposed method. Our results demonstrate that the proposed method calculate the orientation of grounding grid with high accuracy. We also investigate the effect of varying critical parameters of our method.

A COMPARISON OF TWO METHODS FOR MEASUREMENT OF ALDOSTERONE SECRETION RATE IN MAN

1966 ◽  
Vol 53 (2) ◽  
pp. 177-188 ◽  
Author(s):  
P. Lund-Johansen ◽  
T. Thorsen ◽  
K. F. Støa
Keyword(s):  
Urinary Excretion ◽  
Normal Subjects ◽  
Secretion Rate ◽  
Aldosterone Secretion ◽  
Simple Method ◽  
Mean Values ◽  
Pathological Conditions ◽  
Significant Difference ◽  
Derivative Method ◽  
The Mean

ABSTRACT A comparison has been made between (A), a relatively simple method for the measurement of aldosterone secretion rate, based on paper chromatography and direct densitometry of the aldosterone spot and (B) a more elaborate isotope derivative method. The mean secretion rate in 9 normal subjects was 112 ± 26 μg per 24 hours (method A) and 135 ± 35 μg per 24 hours (method B). The »secretion rate« in one adrenalectomized subject after the intravenous injection of 250 μg of aldosterone was 230 μg per 24 hours (method A) and 294 μg per 24 hours (method B). There was no significant difference in the mean values, and correlation between the two methods was good (r = 0.80). It is concluded that the densitometric method is suitable for clinical purposes as well as research, being more rapid and less expensive than the isotope derivative method. Method A also measures the urinary excretion of the aldosterone 3-oxo-conjugate, which is of interest in many pathological conditions. The densitometric method is obviously the less sensitive and a prerequisite for its use is an aldosterone secretion of 20—30 μg per 24 hours. Lower values are, however, rare in adults.

On Calculation Schemes of Spatial Gradient for Spatio-temporal Derivative Method

2003 ◽  
Vol 23 (Supplement1) ◽  
pp. 21-24
Author(s):  
Yasufumi YAMAMOTO ◽  
Yuya AKAMATSU ◽  
Noriyoshi YONEHARA ◽  
Tomomasa UEMURA
Keyword(s):  
Spatial Gradient ◽  
Derivative Method ◽  
Temporal Derivative ◽  
Spatio Temporal

scholarly journals THE ISOTOPE DERIVATIVE METHOD OF PROTEIN AMINO END-GROUP ANALYSIS

1951 ◽  
Vol 190 (2) ◽  
pp. 733-740 ◽  
Author(s):  
Sidney. Udenfriend ◽  
Sidney F. Velick
Keyword(s):  
Group Analysis ◽  
Derivative Method ◽  
End Group
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