Five years experience with a new method of field testing cross and quadrature polarized mho distance relays. I. Results and observations

1988 ◽  
Vol 3 (3) ◽  
pp. 880-886 ◽  
Author(s):  
W.O. Kennedy ◽  
B.J. Gruell ◽  
C.H. Shih ◽  
L. Yee
Keyword(s):  
Field Testing ◽  
New Method ◽  
Distance Relays

A New Method of Steam Quality Measurement Based on Ultrasound

1999 ◽  
Vol 121 (3) ◽  
pp. 172-175 ◽  
Author(s):  
J. J. S. Shen
Keyword(s):  
Speed Of Sound ◽  
Saturation Temperature ◽  
Quality Measurement ◽  
Field Testing ◽  
Steam Injection ◽  
Oil Field ◽  
New Method ◽  
Steam Quality ◽  
Flowing Fluid

A new method of measuring the steam quality based on ultrasound is presented in this paper. This method is based on rigorous consideration of the steam’s thermodynamic properties. It is shown in the paper that the steam’s speed of sound depends on its quality at a given saturation temperature. Thus, the quality of the wet steam can be determined if its speed of sound is known. The speed of sound of a flowing fluid can be measured using transit-time ultrasonic meters. Field testing of a pair of customdesigned ultrasonic transducers has shown that it is feasible to measure the steam’s speed of sound. An uncertainty analysis of this new method is also presented in the paper. The analysis suggests that this method is capable of achieving a measurement accuracy of better than ±3 percentage points of the steam quality under typical oil field steam injection conditions.

scholarly journals A New Method for Controlling Rockbursts in the Mining Roadway of Ultrathick Coal Seams Based on the Dual Pressure Relief Method

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Guangyuan Yu ◽  
Jiong Wang ◽  
Zimin Ma ◽  
Wei Ming ◽  
Xingen Ma
Keyword(s):  
Energy Release ◽  
Abutment Pressure ◽  
Average Energy ◽  
Field Testing ◽  
High Energy ◽  
Low Energy ◽  
New Method ◽  
Coal Seams ◽  
Pressure Relief ◽  
Working Face

To control rockbursts in mining roadways in ultrathick coal seams, a new method for preventing rockbursts through dual pressure relief by roof cutting through cumulative blasting in medium-deep boreholes from the conveyor gateway and return airway was proposed. The mechanical characteristics of key overlying strata of the working face under the effect of dual pressure relief were theoretically investigated. Furthermore, a mathematical relationship between the roof-cutting depth and the advanced abutment pressure on the working face was established to reveal the mechanism of dual pressure relief in controlling rockbursts. Moreover, the effect of the dual pressure relief method on controlling rockbursts was validated through numerical simulation and field testing. Results showed that artificially increasing the caving height of gangues in goaf based on the dual pressure relief method can restrict the subsidence of key strata, thus reducing the advanced abutment pressure of the working face; the method influences a range of 20 m in front of the working face along the strike and areas 30 m away from the two roadways along the dip. The average energy density of coal in the side of the conveyor gateway is decreased by 15.4%, while that in the side of return airway is reduced by 13.8% within the range of influence. The field test results indicated that the average pressure on support declines by 21.4% within 30 m from the working face to the conveyor gateway, while it decreases by 20.5% within that region 25 m from the return airway by using the dual pressure relief method. After conducting dual pressure relief, the total number of microseismic (MS) events during mining of the working face is decreased by 25.4%. The number of MS events with energy release exceeding 103 J falls by 36.6%, while the number of events releasing less than 103 J is increased by 28.6%. The characteristics of MS energy release change from coexistence of low-energy events and a small number of high-energy events to the occurrence of numerous low-energy events. Results can verify the effectiveness of the dual pressure relief method in controlling rockbursts in the mining roadway of ultrathick coal seams.

scholarly journals Prevention of Cascaded Events of Distance Relay Zone Three Using Logic Controls

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Mohamed Younes E. Henna ◽  
Sayed A. Nagy
Keyword(s):  
Transmission Line ◽  
New Method ◽  
Defense System ◽  
Distance Relay ◽  
System Parameters ◽  
Critical Situation ◽  
Cascaded Events ◽  
Distance Relays ◽  
Line Overload

This paper presents a new method to prevent cascaded events caused by zone 3 elements of distance relays due to transmission line overload by using logic controls. A proposed adaptive distance relay algorithm provides a new concept to distinguish between actual faults and flow transfers and secures time to perform remedial controls by a defense system during cascaded events. Maloperation of distance relay is a very critical situation, leading to more operation of other distance relays and finally partial or total blackout. Logic controls are used to insure the operating decision through observing the system parameters and compare it with a setting already being input to the system. When distance relay is activated and the logic controls find that the system is healthy (unfaulted) and that the activation resulted from transmission line overload not real fault, the operation signal will be blocked to protect the system from maloperation.

scholarly journals Detecting and enumerating soil-transmitted helminth eggs in soil: New method development and results from field testing in Kenya and Bangladesh

2017 ◽  
Vol 11 (4) ◽  
pp. e0005522 ◽  
Author(s):  
Lauren Steinbaum ◽  
Laura H. Kwong ◽  
Ayse Ercumen ◽  
Makeda S. Negash ◽  
Amira J. Lovely ◽  
...  
Keyword(s):  
Method Development ◽  
Field Testing ◽  
New Method ◽  
Helminth Eggs

A New Method for Determining Settings of Zone-2 Distance Relays

2004 ◽  
Vol 32 (3) ◽  
pp. 275-293 ◽  
Author(s):  
T. D. SIDHU ◽  
D. SEBASTIAN BALTAZAR ◽  
M. S. SACHDEV
Keyword(s):  
New Method ◽  
Distance Relays

Selective Sampling and Orientation of Non-Homogeneous Tissues

1968 ◽  
Vol 26 ◽  
pp. 98-99
Author(s):  
C. C. Clawson ◽  
L. W. Anderson ◽  
R. A. Good
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light Microscopy ◽  
Random Sampling ◽  
New Method ◽  
Microscope Examination ◽  
Small Areas ◽  
Selective Sampling ◽  
Large Numbers ◽  
Specific Orientation

Investigations which require electron microscope examination of a few specific areas of non-homogeneous tissues make random sampling of small blocks an inefficient and unrewarding procedure. Therefore, several investigators have devised methods which allow obtaining sample blocks for electron microscopy from region of tissue previously identified by light microscopy of present here techniques which make possible: 1) sampling tissue for electron microscopy from selected areas previously identified by light microscopy of relatively large pieces of tissue; 2) dehydration and embedding large numbers of individually identified blocks while keeping each one separate; 3) a new method of maintaining specific orientation of blocks during embedding; 4) special light microscopic staining or fluorescent procedures and electron microscopy on immediately adjacent small areas of tissue.

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