scholarly journals Method of Multi-Angle Transmission Radiowave Tomography of Dielectric Objects

2020 ◽  
Vol 10 (9) ◽  
pp. 3270
Author(s):  
Dmitry Sukhanov ◽  
Kseniya Zavyalova
Keyword(s):  
Refractive Index ◽  
Time Delay ◽  
Homogeneous Medium ◽  
Projection Algorithm ◽  
Propagation Time ◽  
Destructive Testing ◽  
Internal Structures ◽  
Diffraction Effects ◽  
Dielectric Objects ◽  
Non Destructive

A method for solving the inverse problem for reconstructing the spatial distribution of dielectric permittivity from the results of multi-angle transmission broadband radiosounding is proposed. The method is based on inverse wave propagation. The average refractive index of the medium along the wave trajectory is calculated by comparing the results of the calculation of the time delay of the inverse signal in the entire sounding region and the forward propagation time in a homogeneous medium. This method takes into account diffraction effects in solving a direct problem, which allows one to obtain a resolution in the order of a wavelength. The combination of time delays obtained at different probing angles allows the restoration of the distribution of the refractive index in the medium. The paper presents the results of the numerical simulation of this method. The novelty of the proposed approach compared to the conventional back-projection algorithm is that ray approximation is not applied. Instead of the absorption coefficient (used in X-ray tomography), a time delay is considered, which is restored in the entire probed region. The developed method can be widely used in radiowave tomography or microwave tomography for remote non-destructive testing, diagnostics for the internal structures of inhomogeneous media and the restoration of the shapes of opaque objects based on multisensor sensing.

Nondestructive Extraction of Parameters of Multilayered Media Using Terahertz Pulse Technique

Frequenz ◽  
2019 ◽  
Vol 73 (1-2) ◽  
pp. 63-70
Author(s):  
Surya Prakash Singh ◽  
Nilesh K. Tiwari ◽  
M. Jaleel Akhtar
Keyword(s):  
Refractive Index ◽  
Complex Refractive Index ◽  
Multilayered Structure ◽  
Terahertz Pulse ◽  
Destructive Testing ◽  
Multilayered Media ◽  
Pulse Technique ◽  
Non Invasive ◽  
Full Wave ◽  
Non Destructive

Abstract In this work, an efficient non-invasive terahertz pulse technique is proposed and investigated to determine the thickness and refractive index of each layer in an optically thick stratified media. A closed form formulations are derived for simultaneous extraction of the thickness and complex refractive index of each layer with the help of primary reflected signals from the multilayered structure. The proposed technique is numerically tested using a full wave electromagnetic simulator and is experimental verified in the millimeter wave frequency range by utilizing the power peaks corresponding to the primary reflected signals. The numerical and measured results of multilayered samples under test are in good agreement with the reference data. The proposed terahertz pulse technique can be used for non-destructive testing of the multilayered system existing in various industries.

Non-Destructive Testing of Wood Defects Based on Ultrasonic Technology

2013 ◽  
Vol 401-403 ◽  
pp. 1124-1128 ◽  
Author(s):  
Wen Shu Lin ◽  
Jin Zhuo Wu
Keyword(s):  
Wood Products ◽  
Propagation Path ◽  
Propagation Time ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Ultrasonic Technology ◽  
Propagation Parameters ◽  
Old Trees ◽  
Wooden Structures ◽  
Non Destructive

The elm wood samples were tested by the technique of ultrasonic, and the testing results were analyzed by using the statistic software of SPSS. The results showed that the moister content of wood, wood crack, the sizes of holes and numbers of holes have significant influence on propagation parameters and dynamic modulus of elasticity. If there are holes or cracks in the propagation path, the propagation time will be longer, and the propagation velocity and wood modulus will decrease accordingly. The studying results of this paper will provide a sound background for the application of ultrasonic technique in detecting the inner defects of wood products and other wooden structures, and also offer important reference for testing the inner defects of old trees and ancient buildings.

scholarly journals Non-Contact Measurement of the Thickness and Dielectric Parameters of Dielectric Plates and Shells

2015 ◽  
Vol 52 (2) ◽  
pp. 49-58
Author(s):  
I. Matiss
Keyword(s):  
Computer Simulation ◽  
Potential Distribution ◽  
Non Destructive Testing ◽  
Capacitance Sensor ◽  
Destructive Testing ◽  
Dielectric Parameters ◽  
New Approach ◽  
Plates And Shells ◽  
Dielectric Objects ◽  
Non Destructive

Abstract The paper describes a new approach for non-destructive testing of the structural and geometric parameters of dielectric objects using capacitance techniques. The novelty of this approach lies in the design of a capacitance sensor comprising an array of electrodes with changeable potential distribution on them during a measurement process. This makes solvable the problem of measuring independently three input parameters. To demonstrate the capabilities of the developed measurement algorithms, the case studies based on computer simulation have been carried out.

scholarly journals Non-destructive testing of arbitrarily shaped refractive objects with millimetre-wave synthetic aperture radar imaging

2018 ◽  
Vol 7 (1) ◽  
pp. 309-317 ◽  
Author(s):  
Ingrid Ullmann ◽  
Julian Adametz ◽  
Daniel Oppelt ◽  
Andreas Benedikter ◽  
Martin Vossiek
Keyword(s):  
Reconstruction Algorithm ◽  
Non Destructive Testing ◽  
Frequency Range ◽  
Destructive Testing ◽  
Millimetre Wave ◽  
Material Defects ◽  
Polymer Devices ◽  
Simulated Material ◽  
Dielectric Objects ◽  
Non Destructive

Abstract. Millimetre-wave (mmW) imaging is an emerging technique for non-destructive testing. Since many polymers are transparent in this frequency range, mmW imaging is an attractive means in the testing of polymer devices, and images of relatively high resolution are possible. This contribution presents an algorithm for the precise imaging of arbitrarily shaped dielectric objects. The reconstruction algorithm is capable of automatically detecting the object's contour, followed by a material-sensitive reconstruction of the object's interior. As an example we examined a polyethylene device with simulated material defects, which could be depicted precisely.

3D Non-Destructive Evaluation Techniques for Wood Analysis

2014 ◽  
pp. 247-280
Author(s):  
M. Paulina Fernández ◽  
Cristian Tejos ◽  
Gerson Rojas ◽  
Iván Lillo ◽  
Andrés Guesalaga ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Wood Decay ◽  
Destructive Testing ◽  
Industrial Processing ◽  
Advantages And Disadvantages ◽  
Internal Structures ◽  
Magnetic Resonance Imaging Mri ◽  
Wood Analysis ◽  
End Use ◽  
Non Destructive

Non-destructive testing techniques allow the analysis of wood characteristics without altering its end-use capabilities. Wood morphology, wood density, moisture content, and wood decay are some of the features detectable by means of different non-destructive methods. Among them, Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) stand out because of their ability to measure information in a three-dimensional fashion. This enables one to scan volumetrically an entire tree log, giving measurements of each location of the analyzed volume. The output data can provide information about internal structures or physiological features, which can then be used for optimizing industrial processing or for research purposes. In this chapter, the authors describe CT and MRI in terms of their operational principles, sampling conditions, data outputs, and advantages and disadvantages.

scholarly journals Non-destructive testing of multilayer medium by the method of velocity of elastic waves hodograph

2020 ◽  
Vol 243 ◽  
pp. 348
Author(s):  
Aleksandr Potapov ◽  
Artem Kondratev
Keyword(s):  
Elastic Waves ◽  
Propagation Velocity ◽  
Homogeneous Medium ◽  
Main Task ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Hodograph Method ◽  
Reflected Waves ◽  
Multilayer Medium ◽  
Non Destructive

The method of velocity of elastic waves hodograph, aimed at non-destructive testing of structurally heterogeneous composite materials and products based on them, as well as multilayer products and constructions, is considered. The theoretical basis for determining the propagation velocity of elastic waves in a multilayer medium by the hodograph method is given. Based on the studies, recommendations are given for determining the propagation velocity of elastic waves in each individual layer of a multilayer medium, which allows non-destructive testing of the physicomechanical characteristics of each layer of a multilayer medium. It is shown that in addition to simple multiple reflections in a homogeneous medium, in a multilayer medium with parallel interfaces consisting of two or more layers, complex types of multiple reflected waves and mixed waves (reflected-refracted and refracted-reflected) can arise. The main task of applying the low-frequency ultrasonic method is to determine the acoustic parameters of the propagation of elastic waves (velocities, amplitudes, spectra). The main methods for determining the elastic wave velocities are considered, based on the hodograph equation of the indicated reflected waves in a multilayer medium.

Temperaturvariable Computertomographie*/Temperature-variable computed tomography - Enabling quality assurance for complex assemblies

2018 ◽  
Vol 108 (07-08) ◽  
pp. 530-534
Author(s):  
N. Sawczyn ◽  
M. Polte ◽  
E. Uhlmann
Keyword(s):  
Computed Tomography ◽  
Quality Assurance ◽  
Test Chamber ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Internal Structures ◽  
Industrial Computed Tomography ◽  
Temperature Variable ◽  
Clamping Device ◽  
Non Destructive

Die industrielle Computertomographie (CT) ist aufgrund der Möglichkeit sowohl außen- als auch innenliegende Strukturen zerstörungsfrei zu untersuchen für die Qualitätssicherung komplexer Baugruppen geeignet. Höhere Anforderungen an Produkte verlangen innovative Prüfverfahren. Der Beitrag stellt ein Verfahren zur temperaturvariablen CT vor, basierend auf einer temperier- und durchstrahlungsfähigen Prüfkammer mit integrierter formflexibler Aufnahmevorrichtung.   Industrial computed tomography is suitable for the quality assurance of complex assemblies as it enables the non-destructive testing of both external and internal structures. Higher demands on products require innovative testing methods. The article presents a method for temperature-variable computed tomography, using a temperature-controlled and radiolucent test chamber including a form-flexible clamping device.

Non destructive testing of works of art by terahertz analysis

2013 ◽  
Vol 64 (2) ◽  
pp. 21001 ◽  
Author(s):  
Jean-Luc Bodnar ◽  
Jean-Jacques Metayer ◽  
Kamel Mouhoubi ◽  
Vincent Detalle
Keyword(s):  
Non Destructive Testing ◽  
Destructive Testing ◽  
Works Of Art ◽  
Non Destructive
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