Combined Migration of GPR data for layered media

<p>In this contribution we will propose the combination of migration results achieved from the same GPR dataset, aimed to mitigate the effects of the nonuniformity of the propagation velocity of the waves throughout the investigated domain. The nonuniformity of the propagation velocity can be appreciated from the diffraction hyperbolas [1] possibly present in the data, or directly from the results of the focusing [2] achieved from different trial values of the propagation velocity. In ref. [3] an algebraic combination of two (but theoretically even more) migration results achieved from different migration parameters applied to the same data has been shown. In that paper, the case of a horizontal variation and the case of a vertical variation of the propagation velocity of the electromagnetic waves in the soil were considered. Here, we will consider the case of a layered medium with non-flat interface between two adjacent layers, which is a case of interest in several practical application, and is a case where we have both a vertical and a horizontal variation of the parameters. Analogously to ref. [3], we will consider both the aspect of the focusing and that of the combined time-depth conversion.</p><p> </p><p><strong>References</strong></p><p><strong> </strong></p><p>[1] R. Persico G. Leucci, L. Matera, L. De Giorgi, F. Soldovieri, A. Cataldo, G. Cannazza, E. De Benedetto, Effect of the height of the observation line on the diffraction curve in GPR prospecting, Near Surface Geophysics, Vol. 13, n. 3, pp. 243-252, 2015.</p><p>[2]G. Gennarelli, I. Catapano, F. Soldovieri, R. Persico, On the Achievable Imaging Performance in Full 3-D Linear Inverse Scattering, IEEE Trans. on Antennas and Propagation,  vol. 63, n. 3, pp. 1150-1155, March 2015.</p><p>[3] R. Persico, G. Morelli, Combined Migrations and Time-Depth Conversions in GPR Prospecting: Application to Reinforced Concrete, Remote Sens. 2020, Volume 12, Issue 17, 2778, open access, DOI 10.3390/rs12172778</p><p> </p><div><br><div> <p> </p> </div> </div>

Структурная характеризация короткопериодной сверхрешетки на основе гетероструктуры CdF-=SUB=-2-=/SUB=-/CaF-=SUB=-2-=/SUB=-/Si(111) методами просвечивающей электронной микроскопии и рентгеновской дифрактометрии

A detailed study of the structure of a short-period superlattice based on alternating layers of cadmium and calcium fluorides, grown by molecular beam epitaxy on a Si (111) substrate, by transmission electron microscopy and X-ray diffractometry, has been carried out. It was found that the superlattice is in a pseudomorphic state, and a lateral inhomogeneity with a fragment size of 10 - 40 nm was found. The reason for the broadening of the main and satellite peaks of the SL on the (111) diffraction curve has been clarified.

IR spectroscopy and X-ray diffraction analysis of industrial polyvinyl chloride suspension

In terms of the contemporary plastic industry, world production of polyvinyl chloride is second only to polyolefins. Recyclable by almost all known methods, polyvinyl chloride offers high strength, good insulating properties, as well as resistance to acids, oxidising agents and solvents. At the same time, the ability to process polyvinyl chloride into products is limited by its lack of stability at high melt viscosity temperatures, since hydrogen chloride released during its heating catalyses further process of polymer decomposition. Thus, due to the softening temperature of polyvinyl chloride being higher than its decomposition temperature, it cannot be processed in its pure form. Consequently, functional polyvinyl chloride-based materials tend to be composites. By varying the composition of mixtures, plastic masses characterised by either very soft (plastic compounds) or hard (vinyl plastics) structures can be obtained. The properties of polyvinyl chloride-based polymer products are largely determined by the structure and morphology of the polymer. In the present work, the properties of industrial suspension polyvinyl chloride (Sayanskkhimplast JSC, Irkutsk Oblast) were studied in detail for the first time. The molecular weight of the polymer determined by the viscometric method was 1.0 · 106. Thermogravimetric analysis showed that polyvinyl chloride mass loss started to occur at 160 °C. Following the complete IR band assignment of the polymer, the polyvinyl chloride under study was established to contain no foreign substances (impurities of stabilisers, emulsifiers and additives). The diffraction curve of the polymer was established to be qualitatively similar to equivalent partially crystalline polymers. Two amorphous halos were detected at 2θ of 24° 30′ and 39° 30′ below a group of crystalline peaks. The crystallinity degree of polyvinyl chloride was determined and mechanisms for the formation of its regular and irregular structure were proposed.

Detection of Underground Anomalies Using Analysis of Ground Penetrating Radar Attribute

Need of specifying underground construction works for supporting further tasks as maintenance, repairing, or setting up new underground structures. For these needs, ground penetrating radar, one of the efficient geophysical methods, can bring high-resolution and quick underground image revealing existence of both natural and artificial anomalies. Its fixed receiver-transmitter antennas setting as constant offset is commonly used in urban areas. Conventionally, hyperbolae events are crucial indicator for scattering objects as kinds of pipes, water drainage system, and concrete building structures as well as sink holes. Calculation of their depths and sizes requires migration analysis with the environment velocity. Migrated sections with different velocity show different chaos degrees of transformation from a hyperbola diffraction curve to its focused area. We have researched diagrams of different Ground Penetrating Radar attributes as energy, entropy, and varimax dependent on two variables, velocity and window zone covering diffraction events from a set of synthetic data and real data, in specifying the environment velocity. We have developed a novel technique for evaluation of the ground velocity and object’s size by combination of the new varimax diagram and the Kirchhoff migration method. The technique can define contribution of diffracted ground penetrating radar waves for building the diagram after removing the reflection contribution. The synthetic datasets consist of different random background noise levels and expressions of different-sized circular and rectangular pipes. The real data is measured for detecting two underground gas pipes in Ba Ria – Vung Tau province, Vietnam.

Identification of Cacao Peels Potential as a Basic of Electrodes Environmental Friendly Supercapacitors

Identification of the potential of cacao peel as the basic material of environmentally friendly supercapacitor electrodes had been identified. This identification was carried out through analysis of specific dimensions, densities, and capacitances. Activated carbon electrodes were made by a combination of chemical and physics activation methods. The technique of preparing carbon electrodes started from pre-carbonization, milling, chemical activation, pellet making, carbonization, and completed it with physics activation. In addition, the chemical activation applied 0.3 M KOH activator, whereas the physical activation used CO2 gas at a temperature of 700°C. The physical properties were tested by density and X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dipersive X-Ray (EDX). While the electrochemical properties were tested using the Ciclic Voltammetric (CV) method. The results showed that the mass, diameter, thickness, and density of the electrode decreased after passing the carbonization-activation process. A value of 2θ in the range of 23,569o for the reflection fields 002 and 44,781o for the reflection field 100 was obtained in the XRD measurements . The X-ray diffraction curve pointed out that the surface area of C 0,3 M sample was sizeable with the Lc value and lattice distance d002 around 20,01669 Å and 3,771705 Å. SEM analysis indicated the presence of pores between particles spread almost evenly on the surface of the sample, with an irregular and elongated shape. EDX testing showed carbon element of 87.05% while atomic percentage of 91.02%, and correspondently, electrochemical test showed the value of specific capacitance obtained at a concentration of 0.3 M was 90.2 F/gr with a density of 0.850gr/cm3. From the results of the tests obtained, it was shown that cacao peels was very potential to be used as electrodes for supercapacitors.

Cвойства полуполярного GaN, выращенного на подложке Si(100)

Semipolar GaN layers synthesized on a nanostructured Si(100) substrate are studied. It is shown that using a Si(100) nanoprofile combined with Si_ x N_ y nanostrips on top of nanostructures can yield, via metal-organic chemical-vapor deposition, GaN(10 $$\bar {1}$$ 2) layers. An additional SiC buffer layer makes it possible to obtain GaN(10 $$\bar {1}$$ 1) layers with a full-width at half-maximum of the diffraction-curve of ω_θ ≈ 35′ arcmin. It is found that the luminescence properties of the semipolar layers are mostly due to basal plane stacking faults BSF_ S -I_1, in contrast to polar layers in which these properties are mostly due to the recombination of excitons.

X-ray investigation of strained epitaxial layer systems by reflections in skew geometry

Four different SiGe/Si layer structures, pseudomorphically grown and (partially) relaxed, are used as examples to demonstrate that reflections in symmetric skew geometry can successfully be used to realize a complex analysis of these systems. Taking the intensity exactly along the truncation rod of a reciprocal lattice point, it is possible to simulate this diffraction curve and determine the layer parameter in the projection according to the netplane tilt relative to the surface. The main precondition for this technique and for performing reciprocal space mapping with sufficiently high resolution is a low angular divergence of the incident and detected beams perpendicular to the diffraction plane, which can also be achieved by suitable optical elements on laboratory-based diffractometers.

Crystal growth of Ru-doped congruent LiNbO3and investigation of crystalline perfection and optical properties

Single crystals of undoped and Ru-doped congruent LiNbO3(LN) were successfully grown by the Czochralski method. The axial and radial gradient of the radio frequency furnace was controlled in order to obtain crack-free single crystals. Wafers were cut from the grown Ru-doped single crystal at different axial positions along the growth direction and subjected to various characterization analyses. Good optical homogeneity and low residual strain in the grown crystal is confirmed by the conoscopy patterns. Further, it is confirmed that Ru doping does not influence the optical sign of the crystal. From a high-resolution X-ray diffractometry analysis, it is evident that the as-grown undoped LN crystal exhibited better crystalline perfection with a single and sharp diffraction curve in comparison to the Ru-doped crystals, which are characterized by a broader diffraction curve. Absorption coefficient and band-gap analysis across the axial length revealed a concentration variation of Ru across the length. Refractive index measurements carried out using a prism coupler showed variation in the optical birefringence, also due to the variation of Ru concentration at different positions of the grown single crystal.