scholarly journals Comparison of near-field range results

1988 ◽  
Vol 36 (6) ◽  
pp. 845-851 ◽  
Author(s):  
J. Lemanczyk ◽  
F.H. Larsen
Keyword(s):  
Near Field ◽  
Field Range

Measurement of array element excitations using a planar near-field range

2005 ◽  
Author(s):  
K. Sherman
Keyword(s):  
Near Field ◽  
Array Element ◽  
Field Range

Reflection Test at Planar Near Field Range for Reflector Antenna

2004 ◽  
Author(s):  
Jeom-Hun Lee ◽  
S. Yun ◽  
J. Park ◽  
S. Lee ◽  
Y. Kim ◽  
...  
Keyword(s):  
Near Field ◽  
Reflector Antenna ◽  
Field Range

Non-Destructive Detection of GIS Aluminum Alloy Shell Weld Based on Oblique Incidence Full Focus Method

2020 ◽  
Vol 1007 ◽  
pp. 105-110
Author(s):  
Xin Xin Wang ◽  
Cheng He ◽  
Pu Zhi Zhao ◽  
Yi Zheng ◽  
Shi Hao Jiang ◽  
...  
Keyword(s):  
Oblique Incidence ◽  
Near Field ◽  
Calibration Coefficient ◽  
Quantitative Detection ◽  
Imaging Method ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Field Range ◽  
Weld Defects ◽  
Non Destructive

In this paper, a new ultrasonic phased array full focus imaging method based on oblique incidence is proposed to solve the problem of the non-destructive testing of the internal defects in the GIS (gas insulated switchgear) shell welds. By using wedge coupling, the measured weld is far away from the near-field range of the transducer, and the detection angle range can be increased by changing the propagation direction of the acoustic beam. Based on Snell's law, the propagation characteristics of the ultrasonic wave in the interface are studied. On the basis of the conventional ultrasonic array matrix and the full focus imaging algorithm, by introducing the energy attenuation calibration coefficient of the acoustic wave propagation through the wedge, the correction amplitude of the specific focus point p(x, z) is obtained, The non-destructive testing of weld defects of GIS shell in the spot is carried out, and the test results show that the qualitative and quantitative detection of the weld defects can be well realized by using this method.

scholarly journals Lidar Overlap Function Determination Using the Raman Lidar Signals

2020 ◽  
Vol 237 ◽  
pp. 07018
Author(s):  
Jaswant ◽  
Shishir Kumar Singh ◽  
Radhakrishnan S.R. ◽  
Devesh Shukla ◽  
Chhemendra Sharma
Keyword(s):  
Optical Properties ◽  
Simple Technique ◽  
Near Field ◽  
Lower Atmosphere ◽  
Raman Lidar ◽  
Lidar System ◽  
Field Range ◽  
The Mean ◽  
Overlap Factor

The determination of vertical distribution of optical properties of clouds and aerosols using the lidar system is affected by the incomplete overlap between the field of view of transmitter i.e. laser beam & the receiver in the near‐field range. Thus, the study of vertical profiles of aerosol optical properties in the lower atmosphere is erroneous without the correction of lidar overlap function. Here we have analysed the effect of overlap using a simple technique proposed by Ansmann and Wandinger to determine overlap function. We have determined the overlap factor for 5 different days of June 2016 and then calculated the mean overlap profile and determined the relative deviation of each day with respect to mean overlap factor. Results reveal that the complete overlap was achieved beyond 300 meters.

scholarly journals Similarity of the asymmetric swirl generator and a double bend in the near-field range

2019 ◽  
Vol 70 ◽  
pp. 101647 ◽  
Author(s):  
M. Straka ◽  
T. Eichler ◽  
C. Koglin ◽  
J. Rose
Keyword(s):  
Near Field ◽  
Field Range ◽  
Swirl Generator

Segmental orifice plates and the emulation of the 90°-bend

2020 ◽  
Vol 87 (1) ◽  
pp. 18-31
Author(s):  
Martin Straka ◽  
Christian Koglin ◽  
Thomas Eichler
Keyword(s):  
Near Field ◽  
Flow Conditions ◽  
Structural Element ◽  
Field Range ◽  
Flow Meters ◽  
Piping Systems ◽  
Approval Procedure ◽  
Electromagnetic Flow Meter ◽  
Coverage Rates ◽  
Water Meters

AbstractThe 90 ° - bend represents the most common structural element in piping systems and can have a significant impact on the measuring accuracy of flow meters installed downstream. Within the type-approval procedure of water meters, its impact is emulated by means of a segmental orifice plate with a segment area of 7 % (SOP7). In research and development, coverage rates of 33 % (SOP33) or more are sometimes used as an alternative. The purpose of this study is to evaluate the comparability of the flow conditions and their influence on the measurement deviation of flow meters, which is the basic requirement for using SOPs as a substitute for the 90°- bend. We present laser Doppler measurements downstream of an SOP33 and a 90°- bend and describe the flow development in a distance range from 2 to 30 diameters. Besides a quantitative comparison with performance indicators, the measurements are used to model the response of an ultrasonic and electromagnetic flow meter, including recent investigations of an SOP7. The results demonstrate the consistently poor agreement between the SOP7 and the 90°- bend, whereas the SOP33 provides similar flow conditions starting at a distance of 10 diameters. Further studies are necessary to develop a disturbance generator emulating the near-field range.

scholarly journals Compact short-pulse laser for near-field range-gated imaging

1997 ◽  
Author(s):  
Fred J. Zutavern ◽  
Wesley D. Helgeson ◽  
Guillermo M. Loubriel ◽  
George J. Yates ◽  
Robert A. Gallegos ◽  
...  
Keyword(s):  
Pulse Laser ◽  
Short Pulse ◽  
Near Field ◽  
Field Range ◽  
Short Pulse Laser ◽  
Gated Imaging

scholarly journals mmWave Measurement of RF Reflectors for 5G Green Communications

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Tao Hong ◽  
Jin Yao ◽  
Cong Liu ◽  
Fei Qi
Keyword(s):  
Near Field ◽  
Computation Time ◽  
Line Of Sight ◽  
Green Communications ◽  
Green Communication ◽  
High Quality ◽  
Field Range ◽  
Imaging Algorithm ◽  
Array Configuration ◽  
Range Migration

In recent years, with the energy consumption and environmental degradation, science and technology embarked on a path of sustainable development. In this situation, 5G green communication system has been widely used. This paper introduces the application of RF reflectors to 5G mmWave, where line-of-sight (LoS) blockage is a major hindrance for the coverage. In particular, we investigate the lab measurement of RF reflectors, which is a critical step from the theory to the practice. Furthermore, through the lab measurement, a 3D near-field range migration (RM) imaging algorithm for MIMO array configuration is proposed, and the sampling scheme is improved to save the computation time while providing high-quality images.

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