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Showing 1 to 20 of 20 for “"homogeneous medium"”.
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ΑΣΥΠΤΩΤΙΚΗ ΣΥΜΠΕΡΙΦΟΡΑ ΤΗΣ ΕΝΕΡΓΕΙΑΣ ΒΙΣΚΟΕΛΑΣΤΙΚΩΝ ΚΥΜΑΤΩΝ
… VISCOELASTIC MODEL, IN AN ISOTROPIC AND HOMOGENEOUS MEDIUM WITH QUIET PAST, WHOSE VISCOELASTIC BEHAVIOUR IS EXPRESSED BY MEANS OF RELAXATION FUNCTION WHICH DECAY EXPONENTIALLY INTIME. A REGULAR DISTURBANCE WITH COMPACT SUPPORT IS PROPAGATING THROUGH THIS MEDIUM. THE EVOLUTION OF THE …
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Radiative transfer of ultrasound
… of random media. The first type is an isotropic, homogeneous medium containing randomly oriented, randomly located scatterers. The scatterers are assumed to be uncorrelated. This assumption allows an equation of transfer to be written which governs the multiply scattered intensities. This …
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A Study of GPR Performance in the Presence of Buried Biomass
… was employed to model scattering from roots in a homogeneous medium. Slight modifications permitted it to model the GPR data. Comparisons of the DDA code's results against those of well-known codes and various experiments are presented to validate the code. This code was used to simulate …
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ΣΚΕΔΑΣΗ ΘΕΡΜΟΕΛΑΣΤΙΚΩΝ ΚΥΜΑΤΩΝ ΣΕ ΣΥΝΘΕΤΑ ΥΛΙΚΑ ΚΑΙ ΠΡΟΣΔΙΟΡΙΣΜΟΣ ΤΩΝ ΘΕΡΜΟΜΗΧΑΝΙΚΩΝ ΤΟΥΣ ΙΔΙΟΤΗΤΩΝ
… WAVE, PROPAGATING IN AN ISOTROPIC AND HOMOGENEOUS MEDIUM IN THE ABSENCE OF BODY FORCES AND HEAT SOURCES, IS SCATTERED BY A SMOOTH, CONVEX AND BOUNDED THREE- DIMENSIONAL OBSTACLE, WHICH DOESN'T PROPAGATE WAVES IN IT.FIRST IS GIVING THE BIOT SYSTEM OF EQUATIONS WITH THE APPROPRIATE …
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Rapid screening approach for cavity detection using surface-based seismic measurements
… was performed for a cavity buried in a homogeneous medium; Based on results of field and numerical experiments a new constant-offset method for rapid cavity detection is proposed. Parameters introduced include detection index, normalized receiver spacing, and normalized wavelength. All …
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A fast 3D full-wave solver for nanophotonics
… is employed to take advantage of the piecewise homogeneous medium. The Poggio-Miller-Chang-Harrington-Wu (PM-CHW) formulation is formed and the boundary element method is employed to construct and solve a linear system. Moreover, the block Toeplitz matrix property and using FFT helps reduce …
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A numerical study of the effects of inhomogeneous media in diffusion weighted imaging
… from the MR signal under the assumption of homogeneous medium. Unfortunately, the complex structure of a typical volume element of physiological tissue contains many types of cells separated from extracellular space by semi-permeable barriers and is thus far from homogeneous. In this thesis, …
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Simulation of multiple-component charged aerosol evolution
… effects) and condensation, assuming a spatially homogeneous medium and spherical particles. Two problems with different particle compositions were simulated to obtain information about the interactions through the different processes and the interacting particles as well as particle number and …
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Enhanced physics modelling and multistatic data integration for breast tissue reconstruction in microwave radar imaging
… Delay-and-Sum (DAS) beamformers assume a homogeneous medium and ignore tissue heterogeneity; (2) they neglect the frequency dependence of dielectric properties; and (3) true propagation speeds in complex breast tissues are unknown and must be estimated. Moreover, existing image-quality …
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Effect of off-fault low-velocity elastic inclusions on supershear rupture dynamics
… that has a lower rigidity than the background medium. The elastodynamics problem is solved by using the Finite Element software Pylith. The fault operates under linear slip-weakening friction law. Initiate the rupture by artificially overstressing a localized region near the left edge of the …
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Evaluation and Assessment of Inflow Rates in Tunnels Excavated in Jointed Rock Mass
… into a concrete lined tunnel surrounded by a homogeneous medium. (2) An assessment of the in-situ geology needs to be made to determine the potential of highly pervious features which can have hydraulic conductivities that are orders of magnitude larger than the other discontinuities and cause …
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Image Reconstruction in Photoacoustic Computed Tomography with Acoustically Heterogeneous Media
… models that assume a lossless and acoustically homogeneous medium. However, in many applications of PACT these assumptions are violated and the induced photoacoustic (PA) wavefields are scattered and absorbed as they propagate to the receiving transducers. In those applications of PACT, the …
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The very high energy gamma ray burst GRB190114C as observed by MeerKAT
… evolution of GRB190114C as a forward shock in a homogeneous medium for about 100 days post-burst, followed by a jet-break likely occurring simultaneously with the passage of the characteristic peak frequency across our observing band. We constrain the host galaxy component, and compare our …
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Simulation and design optimization of wave propagation in heterogeneous materials
… geometries combining two or more piecewise homogeneous component media. The interest in these materials stems from the fact that when waves propagate through them one can observe phenomena, such as bandgaps, which cannot be obtained with any single homogeneous medium. The design of …
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Der Einfluss regionaler Grundwasserfließsysteme auf die Initialphase der Speläogenese tiefer Karstsysteme
… the laws of groundwater flow in a porous and homogeneous medium (Hubbert 1940). As a result, deep phreatic flow paths form even at a very early stage of speleogenesis. These then have a developmental headstart during the breakthrough phase so that karst systems develop with deep phreatic …
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Advanced Array Imaging for Breast and Prostate Sonography
… to the effects on wave propagation due to an inhomogeneous medium. Since the inhomogenieties are unknown, the goal is to determine their properties – the spatial variation in density, compressibility, geometrical distribution etc. With the scattered wave field, determining the scatterer is …
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Ultrasonic array imaging for multi-layer materials in non-destructive testing applications.
Ultrasonic imaging for a multi-layer medium is a common challenge in seismology, medical diagnosis, and non-destructive testing. One application for multi-layer imaging is ultrasonic immersion test where the material under test and transducer array are immersed in water. The main imaging challenge …
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Investigation of Source Extension Methods, the Discrepancy Algorithm, and Noise Estimation to Overcome Cycle Skipping in Full Waveform Inversion
… in the problem by the penalty term. For a simple homogeneous medium experiment with single trace acoustic data, we illustrate how extended source inversion (ESI) avoids cycle skipping by relaxing the requirement that the source must be compactly supported and by adding a soft penalty to control …
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Surface Wave Analysis in Laterally Varying Media
… dispersion proper of surface waves: in a non-homogeneous medium every frequency is characterized by a different phase velocity, as every frequency component travels through a portion of medium whose thickness is proportional to its wavelength. The curve associating every frequency component to …
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Measurement of a Neutron Pulse Propagation Velocity in a Homogeneous Mediuim
Made available in DSpace on 2017-07-06T18:48:19Z (GMT). No. of bitstreams: 2 Guyot_Jean_C_MS.pdf: 16806523 bytes, checksum: 311bbfaa131263f4d04a039a5bee8bac (MD5) license.txt: 4813 bytes, checksum: 715c4321821a960fa1a1e91d2ac7ebce (MD5) Previous issue date: 1964