Rain impact soil crust. II. Some effects of surface slope, drop size and soil variation

Soil Research ◽  
1991 ◽  
Vol 29 (2) ◽  
pp. 291 ◽  
Author(s):  
AJ Moss
Keyword(s):  
Drop Size ◽  
Surface Zone ◽  
Special Role ◽  
Soil Crust ◽  
Surface Slope ◽  
Small Surface ◽  
Near Surface ◽  
Loose Packing ◽  
Soil Variation ◽  
Stable Particles

Formation and non-formation of the rain-impact soil crust were studied experimentally over ranges of surface-slope, drop-size and soil variation. In these contexts, the formative process was found to be very versatile. However, stable particles, of a size just movable on the soil surfaces by raindrops, appear to play a special role in preventing crust development. Becoming juxtaposed on the surface, these particles form clusters which allow hydraulic penetration of water from impacting drops, through their large pores. This maintains loose packing in the near-surface zone as opposed to the compaction associated with crust formation where only small surface pores exist. A method of soil modification, involving increasing the proportion of durable, barely rain-movable particles in soils, is suggested as a means of combating crusting on a long-term basis.

DISPERSION IN SEISMIC SURFACE WAVES

Geophysics ◽  
1951 ◽  
Vol 16 (1) ◽  
pp. 63-80 ◽  
Author(s):  
Milton B. Dobrin
Keyword(s):  
Surface Waves ◽  
Water Waves ◽  
Seismic Refraction ◽  
Wave Theory ◽  
Wave Dispersion ◽  
Surface Zone ◽  
Surface Wave Dispersion ◽  
Near Surface ◽  
Arrival Times ◽  
Ground Roll

A non‐mathematical summary is presented of the published theories and observations on dispersion, i.e., variation of velocity with frequency, in surface waves from earthquakes and in waterborne waves from shallow‐water explosions. Two further instances are cited in which dispersion theory has been used in analyzing seismic data. In the seismic refraction survey of Bikini Atoll, information on the first 400 feet of sediments below the lagoon bottom could not be obtained from ground wave first arrival times because shot‐detector distances were too great. Dispersion in the water waves, however, gave data on speed variations in the bottom sediments which made possible inferences on the recent geological history of the atoll. Recent systematic observations on ground roll from explosions in shot holes have shown dispersion in the surface waves which is similar in many ways to that observed in Rayleigh waves from distant earthquakes. Classical wave theory attributes Rayleigh wave dispersion to the modification of the waves by a surface layer. In the case of earthquakes, this layer is the earth’s crust. In the case of waves from shot‐holes, it is the low‐speed weathered zone. A comparison of observed ground roll dispersion with theory shows qualitative agreement, but it brings out discrepancies attributable to the fact that neither the theory for liquids nor for conventional solids applies exactly to unconsolidated near‐surface rocks. Additional experimental and theoretical study of this type of surface wave dispersion may provide useful information on the properties of the surface zone and add to our knowledge of the mechanism by which ground roll is generated in seismic shooting.

scholarly journals Validation of GPM Rainfall and Drop Size Distribution Products through Disdrometers in Italy

2021 ◽  
Vol 13 (11) ◽  
pp. 2081
Author(s):  
Elisa Adirosi ◽  
Mario Montopoli ◽  
Alessandro Bracci ◽  
Federico Porcù ◽  
Vincenzo Capozzi ◽  
...  
Keyword(s):  
Size Distribution ◽  
Drop Size ◽  
Global Scale ◽  
Drop Size Distribution ◽  
Single Frequency ◽  
Dual Frequency ◽  
Near Surface ◽  
Active Sensor ◽  
Long Time ◽  
Global Precipitation

The high relevance of satellites for collecting information regarding precipitation at global scale implies the need of a continuous validation of satellite products to ensure good data quality over time and to provide feedback for updating and improving retrieval algorithms. However, validating satellite products using measurements collected by sensors at ground is still a challenging task. To date, the Dual-frequency Precipitation Radar (DPR) aboard the Core Satellite of the Global Precipitation Measurement (GPM) mission is the only active sensor able to provide, at global scale, vertical profiles of rainfall rate, radar reflectivity, and Drop Size Distribution (DSD) parameters from space. In this study, we compare near surface GPM retrievals with long time series of measurements collected by seven laser disdrometers in Italy since the launch of the GPM mission. The comparison shows limited differences in the performances of the different GPM algorithms, be they dual- or single-frequency, although in most cases, the dual-frequency algorithms present the better performances. Furthermore, the agreement between satellite and ground-based estimates depends on the considered precipitation variable. The agreement is very promising for rain rate, reflectivity factor, and the mass-weighted mean diameter (Dm), while the satellite retrievals need to be improved for the normalized gamma DSD intercept parameter (Nw).

STUDYING OF SPACE WEATHER ELECTROMAGNETIC PARAMETERS OF IONOSPHERE IN «OBSTANOVKA 1-STEP» EXPERIMENT ON THE RUSSIAN SEGMENT OF THE ISS

2021 ◽  
pp. 20-41
Author(s):  
Stanislav I. KLIMOV ◽  
Valery A. GRUSHIN Valery A ◽  
Kalman BALAJTHY ◽  
Dichko Enchev BACHVAROV ◽  
Serhiy M. BELYAEV ◽  
...  
Keyword(s):  
Plasma Wave ◽  
Space Weather ◽  
Space Station ◽  
Scientific Instrument ◽  
Surface Zone ◽  
Electromagnetic Parameters ◽  
Wave Processes ◽  
Near Surface ◽  
Ionosphere Plasma ◽  
Electric And Magnetic Fields

The program and results of physical research in the international (5 countries) space experiment «The situation (1 stage)», conducted onboard the Russian segment of the International Space Station (ISS) in the period 27.02.2013 to 09.05.2015, is presented. The methods and scientific tasks of the experiment and the composition of the Plasma-wave complex based on the combined wave diagnostics method are described in detail, and designed to conduct geophysical studies through long-term monitoring measurements of the electromagnetic parameters of the ionosphere plasma and plasma-wave processes associated with the manifestation in the ionosphere of the solar-magnetosphere-ionosphere and ionosphere-atmosphere relationships, i. e., parameters of space weather. Studies in the near-surface zone of plasma-wave processes of interaction of an extra-large spacecraft, like ISS, with the ionosphere are necessary for both applied and fundamental geophysical studies. The electric and magnetic fields and currents measured at the surface of the ISS are determined by the parameters of the surrounding ionosphere plasma and the nature of the interaction of the materials on the surface with this medium. Key words: orbital space station, fundamental space research, ionosphere plasma, plasma-wave processes, electromagnetic fields and radiation, scientific instrument, space weather.

scholarly journals Modern Geodetic Measurement Techniques in Gravimetric Studies on the Example of Gypsum Karst in the Siesławice Region

2018 ◽  
Vol 35 ◽  
pp. 03002 ◽  
Author(s):  
Sławomir Porzucek ◽  
Monika Łój ◽  
Karolina Matwij ◽  
Wojciech Matwij
Keyword(s):  
Laser Scanning ◽  
Measurement Techniques ◽  
Three Dimensional ◽  
Digital Terrain Model ◽  
Field Studies ◽  
Surface Zone ◽  
Three Dimensional Model ◽  
Geodetic Measurement ◽  
Near Surface ◽  
Gypsum Karst

In the region of Siesławice (near Busko-Zdrój, Poland) there are unique phenomena of gypsum karst. Atmospheric factors caused numerous gypsum outcrops, canals and underground voids. The article presents the possibility of using non-invasive gravimetric surveys supplemented with geodetic measurements to illustrate karst changes occurring around the void. The use of modern geodetic measurement techniques including terrestrial and airborne laser scanning enables to generate a digital terrain model and a three-dimensional model of voids. Gravimetric field studies allowed to map the anomalies of the gravitational field of the near-surface zone. Geodetic measurement results have made it possible to accurately determine the terrain correction that supplemented the gravimetric anomaly information. Geophysical interpretation indicate the presence of weathered rocks in the near surface zone and fractures and loosened zones located surround the karst cave.

Chemical diagenesis in near-surface zone above oil fields in geochemical exploration

2018 ◽  
Vol 95 ◽  
pp. 33-44
Author(s):  
Igor S. Sobolev ◽  
Nikolay P. Bredikhin ◽  
Tatiana Bratec ◽  
Alla Yu. Falk ◽  
Oleg S. Tolkachev ◽  
...  
Keyword(s):  
Oil Fields ◽  
Surface Zone ◽  
Geochemical Exploration ◽  
Near Surface

Rain impact soil crust. IV. Packing of sand and silt fractions by raindrops

Soil Research ◽  
1991 ◽  
Vol 29 (2) ◽  
pp. 331 ◽  
Author(s):  
AJ Moss
Keyword(s):  
Void Ratio ◽  
Packed Bed ◽  
Stress Waves ◽  
Soil Crust ◽  
Structural Element ◽  
Loose Packing ◽  
Impact Events ◽  
Underlying Soil ◽  
Silt Layer ◽  
Critical Void

Comparison of resistance to fast and slow deformation by rain-packed and artificially prepared sand and silt fractions showed that, whereas sands are left in loosely packed states after accrual under rain impact, silts are left more densely packed, i.e. below critical void ratio. This contrast is attributed mainly to the declining importance of hydraulic penetration with pore size. Rain-packed silt is dilatant and cannot deform without expansion which, in turn, requires water entry at a rate compatible with the required deformation. In the short duration of rain-impact events, hydrodynamic time lagging occurs because water can move only slowly through the small silt pores. Consequently, densely packed silt remains essentially rigid. However, drop-outflow sheets are able to entrain silt and distribute it over the surface as densely packed bed-load deposits, thus maintaining its dilatancy. Sand, its larger pores invaded by hydraulic penetration jets which maintain loose packing, cannot behave in this manner. Relative stability of the silt layer on soil surfaces, and its suppression of hydraulic penetration, allow transmission of drop-generated stress waves which cause the immediately underlying soil to become compacted into the main structural element of the rain-impact soil crust.

scholarly journals Application of electric resistivity tomography for investigation of geological situation closed to railways

2019 ◽  
Vol 265 ◽  
pp. 03005
Author(s):  
Dmitriy Gorbach ◽  
Valeriya Yakimenko ◽  
Olga Konovalova
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Electric Resistivity ◽  
Practical Work ◽  
Surface Zone ◽  
Two Dimensional ◽  
Resistivity Tomography ◽  
Near Surface ◽  
Geological Situation ◽  
Engineering Geophysics

The paper reviews methods of engineering geophysics which can be applied to sections of railway tracks. The method of electrical resistivity tomography is used to study the properties of the geological situation under an engineering structure. In the course of practical work, two-dimensional geoelectric sections were obtained. Interpretation of the sections allowed to understand the structure of the near-surface zone.

The Materials Science Beamline EDDI for Energy-Dispersive Analysis of Subsurface Residual Stress Gradients

2006 ◽  
Vol 524-525 ◽  
pp. 193-198 ◽  
Author(s):  
Christoph Genzel ◽  
Ingwer A. Denks ◽  
Manuela Klaus
Keyword(s):  
Residual Stress ◽  
Materials Science ◽  
High Energy ◽  
Energy Dispersive ◽  
7 Tesla ◽  
Polycrystalline Materials ◽  
Surface Zone ◽  
Near Surface ◽  
Technical Parameters ◽  
Set Up

In April 2005 the materials science beamline EDDI (Energy Dispersive DIffraction), which the HMI operates at the Berlin synchrotron storage ring BESSY, started user service. The high energy white synchrotron beam up to about 150 keV used for the diffraction experiments is provided by a superconducting 7 Tesla multipole wiggler. Starting with some basic information on the technical parameters of the beamline, its set-up and measuring facilities, the paper focuses on the application of white beam diffraction to the analysis of residual stress fields in the near surface zone of polycrystalline materials. The concept of a program system is introduced, which we offer to our users for preparing and evaluating their measurements performed at the EDDI beamline.

scholarly journals Residual Stress Measurement of Shot-Peened Steel Rings by Barkhausen Noise, ESPI Hole-Drilling and X-Ray Diffraction

2014 ◽  
Vol 996 ◽  
pp. 380-385 ◽  
Author(s):  
Theo J. Rickert ◽  
James J. Thomas ◽  
Lasse Suominen
Keyword(s):  
Stress Measurement ◽  
Nondestructive Method ◽  
Fatigue Properties ◽  
Hole Drilling ◽  
Barkhausen Noise ◽  
Surface Zone ◽  
Near Surface ◽  
Generate Surface ◽  
Noise Measurements ◽  
Quantitative Stress

Shot-Peening is used to generate surface-near compressive residual stresses in final shape parts, usually to improve their fatigue properties. The success of the process can be checked in different ways. XRD and Hole-Drilling determine quantitative stress depth profiles in specific locations. Barkhausen noise measurements evaluate a near-surface zone in real-time and can cover large areas quickly. It is a fully nondestructive method. This study compares ESPI Hole-Drilling, which is a very fast technique, and XRD, which is very precise but slower, to Barkhausen Noise results for the case of three steel rings shot-peened with different intensities.

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