Investigation Geological structural morphology of Quaternary sediment on coastal Bac Lieu

2018 ◽  
Vol 25 (2) ◽  
pp. 167-172
Author(s):  
Nguyễn Văn Giảng ◽  
Lê Ngọc Thanh
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Ground Surface ◽  
Field Analysis ◽  
Radio Waves ◽  
Frequency Range ◽  
Quaternary Sediment ◽  
Structural Morphology ◽  
Near Surface ◽  
Shallow Structure

Georadar is a high-resolution near-surface geophysical method which employ radio waves, typically in the 1 to 1000 MHz frequency range tomap structure and features buried in the ground (or in man-made structures). Georadar method with Pulse EKKO 1 OOA instrument offers the highest resolution and rapidly provides continuous graphicformat which permits rapid semi-quantitative interpretation for in-field analysis. VLF method with Wadi instrument records the ratio of the strengths of the vertical and horizontal fields at the ground surface. Then this method can be used to reveal steeply dipping structures with large cross-sections and low resistivities as fructure/ conductivity zones.This paper is presented the result of using Georadar, VLF and electrical profiling methods for geological structural morphology of quaternarysediment investigation on coastal Baclieu. The structural cross-section of morphology of quaternary sediment is established by nine layers of georadar data for shallow structure and several interfaces of conductivity for deeper structure.

scholarly journals ESTIMATION OF LONG-RANGE CORRELATION SCALES BY SEISMOACOUSTIC EMISSION SIGNALS OF NEAR-SURFACE SEDIMENTARY ROCKS IN KAMCHATKA

2019 ◽  
pp. 190-200
Author(s):  
В.Н. Сычёв ◽  
М.А. Мищенко ◽  
С.А. Имашев ◽  
М.Е. Чешев
Keyword(s):  
Long Range ◽  
Ground Surface ◽  
Frequency Range ◽  
Self Similarity ◽  
Observation Site ◽  
Near Surface ◽  
Long Range Correlations ◽  
Seismic Receiver ◽  
Range Correlation ◽  
Geophysical Observation

На Камчатке в пункте комплексных геофизических наблюдений ИКИР ДВО РАН Карымшина для регистрации сигналов сейсмоакустической эмиссии на поверхности земли установлен измерительный комплекс. В качестве датчика сигналов используется трехкомпонентный пьезокерамический сейсмоприемник, который регистрирует колебательное ускорение в частотном диапазоне 0.5-400 Гц. Рассмотрен сейсмоакустический отклик на несколько региональных землетрясений с энергетическим классом Ks 11:0 в период 2017-2018 гг. При помощи статистических методов установлено самоподобие их структуры на ограниченном интервале временных масштабов. Это, в свою очередь, указывает на наличие дальних корреляций в рассматриваемой системе и позволяет получить оценку масштабов корреляций. A measurement complex is installed on the ground surface at Karymshina complex geophysical observation site of IKIR FEB RAS (Kamchatka) to record seismoacoustic emission signals. A three-component piezoceramic seismic receiver, which records oscillatory acceleration in the frequency range from 0.2 to 400 Hz, is used as the signal sensor. A series of seismoacoustic responses on regional earthquakes of 2017-2018 with the energy class Ks 11:0 has been considered. Self-similarity of their structures has been established in a limited interval of time scales by statistical methods. That, in its turn, indicates the presence of long-range correlations in the system under consideration and allows one to estimate correlation scales.

scholarly journals Plant–Environment Interactions in the Low Arctic Torngat Mountains of Labrador

Ecosystems ◽  
2020 ◽  
Author(s):  
Emma Davis ◽  
Andrew Trant ◽  
Luise Hermanutz ◽  
Robert G. Way ◽  
Antoni G. Lewkowicz ◽  
...  
Keyword(s):  
Environmental Change ◽  
Cross Sections ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Regional Climate ◽  
Ground Surface ◽  
Ground Vegetation ◽  
Near Surface ◽  
Plant Environment

Abstract The eastern Canadian Subarctic and Arctic are experiencing significant environmental change with widespread implications for the people, plants, and animals living there. In this study, we integrate 10 years of research at the Nakvak Brook watershed in Torngat Mountains National Park of Canada, northern Labrador, to assess the sensitivity of ecological and geomorphological systems to regional climate warming. A time series of the Normalized Difference Vegetation Index indicates that the area has undergone a significant greening trend over the past four decades. Analyses of shrub cross sections suggest that greening has been caused by a combination of rapid establishment and growth that began in the late 1990’s and coincided with warmer growing season temperatures. Recent (2010–2015) vegetation change has been subtle and heavily moderated by soil moisture status. Plant canopy height is greater in wet areas and has an insulating effect on ground surface temperatures during the winter, a consequence of snow trapping by shrub canopies. Observations of subsurface conditions indicate that the study site is best characterized as having discontinuous near-surface permafrost. The importance of subsurface conditions for above-ground vegetation depends on the geomorphological context, with plants in wet areas underlain by fine materials being the most likely to be growth-limited by permafrost, thus being potential hot-spots for future change. With the expectation of sustained climate change, loss of adjacent sea ice, and proximity to the forest-tundra ecotone, it is likely that the Torngat Mountains will continue to be an area of rapid environmental change in the coming decades.

scholarly journals Scattering of HF Radio Waves from the Sea: A Review of the Theory Based upon a Simplified Model

1991 ◽  
Vol 44 (5) ◽  
pp. 459 ◽  
Author(s):  
BT McCann ◽  
RE Robson
Keyword(s):  
Frequency Shift ◽  
Cross Section ◽  
Cross Sections ◽  
Diffuse Scattering ◽  
Surface Current ◽  
Second Order ◽  
Simplified Model ◽  
Radio Waves ◽  
Intuitive Model ◽  
Main Change

A simplified, physically intuitive model of diffuse scattering of radio waves from a rough surface is used to present a self-contained derivation of first- and second-order cross sections, essentially in agreement with the standard expressions. Incoherent addition of the second-order contributions (electromagnetic and hydrodynamic) leads to a cross section which is slightly different from the more rigorously derived cross sections of Barrick (1972b) and Johnstone (1975). A surface current v has been incorporated in this model, with the main change to the cross section being a frequency shift of the entire spectrum by an amount Llw = -2ko . v.

Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals

1971 ◽  
Vol 29 ◽  
pp. 78-79
Author(s):  
J. P. Colson ◽  
D. H. Reneker
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Detailed Examination ◽  
The Other ◽  
Electron Micrograph ◽  
Irradiation Effects ◽  
Threefold Axis ◽  
Typical Sample ◽  
Polymer Crystals ◽  
Chain Axis

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Oxygen K near edge structures studied with multiple scattering calculations

1988 ◽  
Vol 46 ◽  
pp. 504-505
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Partial Cross Section ◽  
Energy Window ◽  
Edge Structure ◽  
Fine Structures ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
Quantitative Chemical

In electron energy loss spectroscopy, quantitative chemical microanalysis is performed by comparison of the intensity under a specific inner shell edge with the corresponding partial cross section. There are two commonly used models for calculations of atomic partial cross sections, the hydrogenic model and the Hartree-Slater model. Partial cross sections could also be measured from standards of known compositions. These partial cross sections are complicated by variations in the edge shapes, such as the near edge structure (ELNES) and extended fine structures (ELEXFS). The role of these solid state effects in the partial cross sections, and the transferability of the partial cross sections from material to material, has yet to be fully explored. In this work, we consider the oxygen K edge in several oxides as oxygen is present in many materials. Since the energy window of interest is in the range of 20-100 eV, we limit ourselves to the near edge structures.

Absolute inner-shell cross section determination for EELS analysis

1988 ◽  
Vol 46 ◽  
pp. 534-535
Author(s):  
P.A. Crozier
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absolute Cross Section ◽  
Specimen Thickness ◽  
Mass Thickness ◽  
Scattering Cross ◽  
Before And After ◽  
Estimated Error ◽  
Scattering Cross Sections ◽  
Electron Microscopist

Absolute inelastic scattering cross sections or mean free paths are often used in EELS analysis for determining elemental concentrations and specimen thickness. In most instances, theoretical values must be used because there have been few attempts to determine experimental scattering cross sections from solids under the conditions of interest to electron microscopist. In addition to providing data for spectral quantitation, absolute cross section measurements yields useful information on many of the approximations which are frequently involved in EELS analysis procedures. In this paper, experimental cross sections are presented for some inner-shell edges of Al, Cu, Ag and Au.Uniform thin films of the previously mentioned materials were prepared by vacuum evaporation onto microscope cover slips. The cover slips were weighed before and after evaporation to determine the mass thickness of the films. The estimated error in this method of determining mass thickness was ±7 x 107g/cm2. The films were floated off in water and mounted on Cu grids.

Near-Surface Aggregation of Sn In Heavily Sn-Doped GaAs Films Grown By Molecular Beam Epitaxy

1985 ◽  
Vol 43 ◽  
pp. 368-369
Author(s):  
S. H. Chen
Keyword(s):  
Molecular Beam Epitaxy ◽  
Cross Section ◽  
Electron Spectroscopy ◽  
Molecular Beam ◽  
Surface Segregation ◽  
Secondary Ion Mass Spectrometry ◽  
Specimen Preparation ◽  
Near Surface ◽  
Gaas Films ◽  
Secondary Ion

Sn has been used extensively as an n-type dopant in GaAs grown by molecular-beam epitaxy (MBE). The surface accumulation of Sn during the growth of Sn-doped GaAs has been observed by several investigators. It is still not clear whether the accumulation of Sn is a kinetically hindered process, as proposed first by Wood and Joyce, or surface segregation due to thermodynamic factors. The proposed donor-incorporation mechanisms were based on experimental results from such techniques as secondary ion mass spectrometry, Auger electron spectroscopy, and C-V measurements. In the present study, electron microscopy was used in combination with cross-section specimen preparation. The information on the morphology and microstructure of the surface accumulation can be obtained in a fine scale and may confirm several suggestions from indirect experimental evidence in the previous studies.

A technique for preparing semiconductor cross sections for both TEM and SEM analysis

1989 ◽  
Vol 47 ◽  
pp. 712-713
Author(s):  
Stanley J. Klepeis ◽  
J.P. Benedict ◽  
R.M Anderson
Keyword(s):  
Sample Preparation ◽  
Cross Section ◽  
Cross Sections ◽  
Sem Analysis ◽  
Preparation Technique ◽  
Ion Milling ◽  
Tem Analysis ◽  
Polished Cross Section ◽  
Area Of Interest ◽  
Polished Side

The ability to prepare a cross-section of a specific semiconductor structure for both SEM and TEM analysis is vital in characterizing the smaller, more complex devices that are now being designed and manufactured. In the past, a unique sample was prepared for either SEM or TEM analysis of a structure. In choosing to do SEM, valuable and unique information was lost to TEM analysis. An alternative, the SEM examination of thinned TEM samples, was frequently made difficult by topographical artifacts introduced by mechanical polishing and lengthy ion-milling. Thus, the need to produce a TEM sample from a unique,cross-sectioned SEM sample has produced this sample preparation technique.The technique is divided into an SEM and a TEM sample preparation phase. The first four steps in the SEM phase: bulk reduction, cleaning, gluing and trimming produces a reinforced sample with the area of interest in the center of the sample. This sample is then mounted on a special SEM stud. The stud is inserted into an L-shaped holder and this holder is attached to the Klepeis polisher (see figs. 1 and 2). An SEM cross-section of the sample is then prepared by mechanically polishing the sample to the area of interest using the Klepeis polisher. The polished cross-section is cleaned and the SEM stud with the attached sample, is removed from the L-shaped holder. The stud is then inserted into the ion-miller and the sample is briefly milled (less than 2 minutes) on the polished side. The sample on the stud may then be carbon coated and placed in the SEM for analysis.

Experimental Studies Of Multilayer Glass Structures On Compression, Compression With Bending And Simple Bending

2019 ◽  
pp. 22-30
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Applied Load ◽  
Experimental Studies ◽  
Strength Properties ◽  
Research Topic ◽  
Normative Values ◽  
Laminated Glass ◽  
The Cross ◽  
Experimental Values

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.

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