Influence of the Antenna’s Height to the Standing Waves Ratio When Performing the Electromagnetic Susceptibility Tests in Anechoic Chambers

2017 ◽  
pp. 161-167
Author(s):  
Martin Pospisilik ◽  
Milan Adamek ◽  
Petr Neumann
Keyword(s):  
Standing Waves ◽  
Anechoic Chambers ◽  
Susceptibility Tests

scholarly journals Numerical analysis of the interaction between a GTEM-cell and a device under test using a hybrid method

2003 ◽  
Vol 1 ◽  
pp. 49-51 ◽  
Author(s):  
M. Zellerhoff ◽  
L. Klinkenbusch
Keyword(s):  
Hybrid Method ◽  
Low Cost ◽  
Fdtd Method ◽  
Analytical Models ◽  
Device Under Test ◽  
Detailed Knowledge ◽  
Anechoic Chambers ◽  
Susceptibility Tests ◽  
Gtem Cell ◽  
Very High Frequencies

Abstract. Due to the increasing importance of EMC problems through the last years there is a great interest in measurement devices such as GTEM-cells (Giga(Hz)- TEM cells). They promise to allow compact and low-cost emission- as well as susceptibility tests up to very high frequencies. Expensive measurement procedures in open-area test sites or within semi-anechoic chambers would become obsolete in many cases. To estimate the quality and reliability of GTEM-cell measurements it is necessary to have detailed knowledge about the processes within the cell and, in particular, about the interactions between the cell and the DUT (device under test). Due to the high frequency and the cell’s dimensions a purely numerical simulation while using standard techniques such as Finite Element Method, Method of Moments (MoM) or the Finite-Differ-Time-Domain (FDTD) method is inefficient and unnecessary since the GTEM-cell is a mostly empty homogeneous TEM-waveguide. Analytical models allow only the investigation of empty cells. As will be outlined in the following, a suitable way to reduce the numerical complexity of the general problem is the use of a hybrid method, such as the combination of a modal analysis with the MoM.

X-ray standing waves—a new method of studying the structure of crystals

1986 ◽  
Vol 149 (05) ◽  
pp. 69-103 ◽  
Author(s):  
M.V. Koval'chuk ◽  
V.G. Kohn
Keyword(s):  
Standing Waves ◽  
New Method ◽  
X Ray

Extraction and Phytochemicals Determination of Traditional Medicinal Plants for Anti-microbial Susceptibility Test

2020 ◽  
Vol 2020 ◽  
Author(s):  
Firew Admasu
Keyword(s):  
Antimicrobial Activity ◽  
Medicinal Plants ◽  
Traditional Medicine ◽  
Crude Extract ◽  
Susceptibility Test ◽  
Plant Sample ◽  
Traditional Medicinal Plants ◽  
Traditional Health Care ◽  
Susceptibility Tests

Abstract: The study were conducted at Dilla University, College of Natural Sciences, Biological Sciences laboratories. Background: Ethiopia is a country with many ethnic groups, cultures and beliefs which in turn have contributed to the high diversity of traditional health care knowledge and practices of traditional medicine from local growth plants, animals and minerals for various physical and mental disorders of human and livestock population that passed from generation to generation for centuries. Medicinal plants contributors to pharmaceutical, agricultural and food industries in the world. The use of medicinal plants in the industrialized societies has been traced to extraction and development of several drugs used in order to heel some diseases having inhibiting effect against pathogenic microorganism. Objective: The main objective of this study was Extraction and Phytochemicals determination of traditional medicinal plants for anti microbial susceptibility test. Methodology: The extraction and identification of some phytochemicals crude compound which used for antimicrobial susceptibility test from plant sample such as Ocimum lamiifolium (OL), Croton maerosth (Cm) and Ruta chalepesis (RC) were conducted. Plant samples are collected, powdered using mortal and pistil and extracted using ethanol and some susceptibility tests were performed to identify some phytochemicals compound. Result: The main result of Antimicrobial activity test showed that the crude extract of OL has the highest zone of inhibition. The highest yield of crude extract (38.21%) was obtained from Croton maerosth (CM) which followed by Ruta chalepesis (RC) (32.43%). However, the lowest yield (28.37%) was obtained from Oscpmum lamifolium (OL). Conclusion: Traditional Medicine is used by many people to managing numerous conditions; it’s accessible and effective on antimicrobial activity. Therefore, it plays a significant role by reducing life-threatening ailments of people and other animals.

Tire Vibrations

1977 ◽  
Vol 5 (4) ◽  
pp. 202-225 ◽  
Author(s):  
G. R. Potts ◽  
C. A. Bell ◽  
L. T. Charek ◽  
T. K. Roy
Keyword(s):  
Natural Frequencies ◽  
Standing Waves ◽  
Resonant Mode ◽  
Mode Shapes ◽  
Resonant Vibrations ◽  
Resonant Frequencies ◽  
Radial Tire ◽  
Analysis Techniques ◽  
Thin Ring ◽  
Good Agreement

Abstract Natural frequencies and vibrating motions are determined in terms of the material and geometric properties of a radial tire modeled as a thin ring on an elastic foundation. Experimental checks of resonant frequencies show good agreement. Forced vibration solutions obtained are shown to consist of a superposition of resonant vibrations, each rotating around the tire at a rate depending on the mode number and the tire rotational speed. Theoretical rolling speeds that are upper bounds at which standing waves occur are determined and checked experimentally. Digital Fourier transform, transfer function, and modal analysis techniques used to determine the resonant mode shapes of a radial tire reveal that antiresonances are the primary transmitters of vibration to the tire axle.

A Finite Element Analysis of the General Rolling Contact Problem for a Viscoelastic Rubber Cylinder

1988 ◽  
Vol 16 (1) ◽  
pp. 18-43 ◽  
Author(s):  
J. T. Oden ◽  
T. L. Lin ◽  
J. M. Bass
Keyword(s):  
Finite Element ◽  
Variational Principles ◽  
Standing Waves ◽  
Rolling Contact ◽  
Finite Element Models ◽  
Viscoelastic Cylinder ◽  
Element Analysis ◽  
Elastic Rubber ◽  
Frictional Effects ◽  
Rough Foundation

Abstract Mathematical models of finite deformation of a rolling viscoelastic cylinder in contact with a rough foundation are developed in preparation for a general model for rolling tires. Variational principles and finite element models are derived. Numerical results are obtained for a variety of cases, including that of a pure elastic rubber cylinder, a viscoelastic cylinder, the development of standing waves, and frictional effects.

Formation of Standing Waves in Radial Tires

1984 ◽  
Vol 12 (1) ◽  
pp. 44-63 ◽  
Author(s):  
Y. D. Kwon ◽  
D. C. Prevorsek
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Unit Length ◽  
Standing Waves ◽  
Rolling Resistance ◽  
Damping Coefficient ◽  
Circular Membrane ◽  
Critical Speeds ◽  
Steel Cord ◽  
The Individual

Abstract Radial tires for automobiles were subjected to high speed rolling under load on a testing wheel to determine the critical speeds at which standing waves started to form. Tires of different makes had significantly different critical speeds. The damping coefficient and mass per unit length of the tire wall were measured and a correlation between these properties and the observed critical speed of standing wave formation was sought through use of a circular membrane model. As expected from the model, desirably high critical speed calls for a high damping coefficient and a low mass per unit length of the tire wall. The damping coefficient is particularly important. Surprisingly, those tire walls that were reinforced with steel cord had higher damping coefficients than did those reinforced with polymeric cord. Although the individual steel filaments are elastic, the interfilament friction is higher in the steel cords than in the polymeric cords. A steel-reinforced tire wall also has a higher density per unit length. The damping coefficient is directly related to the mechanical loss in cyclic deformation and, hence, to the rolling resistance of a tire. The study shows that, in principle, it is more difficult to design a tire that is both fuel-efficient and free from standing waves when steel cord is used than when polymeric cords are used.

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