Evidence for nondiffusive transport of 86Rn in the ground and a new physical model for the transport

Geophysics ◽  
1982 ◽  
Vol 47 (10) ◽  
pp. 1444-1452 ◽  
Author(s):  
Krister Kristiansson ◽  
Lennart Malmqvist
Keyword(s):  
Diffusion Length ◽  
Ground Surface ◽  
Constant Depth ◽  
Physical Conditions ◽  
Transport Length ◽  
Carrier Mechanism ◽  
Flow Transport ◽  
And Migration ◽  
Radon Measurements ◽  
Made In

Concentration of radon has been measured in the soil near the ground surface with solid‐state, nuclear track detectors with the inverted cup technique. Measurements were made in the overburden at depth intervals 0.1–0.7 m, at 0.1–6 m, and at a constant depth of 0.2 m, in a narrow rectangular matrix. The results disagree with the hypothesis that radon concentration only depends upon local production and migration by diffusion with a diffusion length of about 1 m. A transport length of 0.1–0.2 m is observed near the ground surface and the transport is dominated by a flow component. Radon measurements in the ground surface over the Laisvall lead mine have given evidence of radon transport through rock exceeding a distance of 100 m, which is possible only if the migration is a flow transport with a characteristic transport length larger than about 10 m/day. To explain the radon transport in the overburden and through the rock with a common transport system, the existence of a general upward flow of geo‐gas is proposed. This geo‐gas works as a carrier mechanism for radon. The physical conditions for the existence of a flow transport of radon are discussed.

scholarly journals On the Coronal and Prominence Structures Observed at the Total Solar Eclipse of 11 July 1991

1994 ◽  
Vol 154 ◽  
pp. 205-210
Author(s):  
Y. Suematsu ◽  
H. Fukushima ◽  
Y. Nishino
Keyword(s):  
Solar Eclipse ◽  
Near Infrared ◽  
Thermal Structure ◽  
Wavelength Region ◽  
Total Solar Eclipse ◽  
Preliminary Results ◽  
Spectroscopic Observations ◽  
Physical Conditions ◽  
Made In

Coronal images were taken in the light of the He I 10830 Å line, the 10000 Å continuum, and the Fe XIV 5303 Å line, with the aim of studying the thermal structure of the corona. In addition, spectroscopic observations were made in the violet wavelength region (3760-4060 Å) and near-infrared (10745-10835 Å), to obtain details of physical conditions of the corona, especially of its cool part. The data obtained do not show any distinct cool structures other than ordinary prominences. Some preliminary results concerning the corona and prominence structures are given.

VARIATIONS OF INDOOR RADON CONCENTRATION IN TRADITIONAL RUSSIAN RURAL WOODEN HOUSES

2020 ◽  
Vol 191 (2) ◽  
pp. 219-222
Author(s):  
Tatiana Petrova ◽  
Petr Miklyaev
Keyword(s):  
Radon Concentration ◽  
Indoor Radon ◽  
Ground Surface ◽  
Radon Exhalation Rate ◽  
Exhalation Rate ◽  
Indoor Radon Concentration ◽  
Radon Exhalation ◽  
Soil Gas Radon ◽  
Radon Measurements ◽  
Indoor And Outdoor

Abstract Continuous indoor radon measurements were carried out in two traditional Russian rural houses located in different villages of the Moscow region in summer of 2017 and 2018. In additional, in the summer of 2017, continuous measurements of soil gas radon activity concentration at depth 0.8 m and radon exhalation rate from the ground surface near the house were performed simultaneously. It was found that the indoor radon concentration in rural houses is subject to strong daily variations, which are characterized by highs at night and lows during the day. Indoor radon concentration is directly proportional to indoor and outdoor temperature difference and inversely proportional to wind speed. While the radon exhalation rate from the ground surface, as well as the ventilation of premises (opening doors and windows) practically do not affect the concentration of radon in Russian rural wooden houses.

scholarly journals The History of Solar Prominence Research: Historical Introduction to IAU Colloquium No. 167 “New Perspectives on Solar Prominences”

1998 ◽  
Vol 167 ◽  
pp. 11-19 ◽  
Author(s):  
Einar Tandberg-Hanssen
Keyword(s):  
Early Period ◽  
Solar Prominence ◽  
Physical Conditions ◽  
Solar Prominences ◽  
Comprehensive Picture ◽  
History Of ◽  
Global Nature ◽  
Made In ◽  
Coronal Structures

AbstractWe trace the history of observational solar prominence research from the early period when total solar eclipses provided the only means of observation, via the introduction of photography and spectroscopy in the 1860’s, to the present epoch when application of the Zeeman and the Hanle effects makes possible determination of the all-important magnetic fields in prominences.Dividing prominence models into two classes, those that treat the support of the prominence against gravity and those concerned with the physical conditions in the prominence plasma itself, we describe the progress made in both classes of models since the 1950’s, when the first models were proposed. Finally, we comment on the necessity of combining aspects of the two classes of prominence models into a comprehensive picture that can account for the global nature of prominence support and stability, and where the adjacent coronal structures play an important role.

The diffusion length of thermal neutrons in water between 18 and 255 °C

1966 ◽  
Vol 289 (1418) ◽  
pp. 342-352 ◽  
Keyword(s):  
Cross Section ◽  
Close Agreement ◽  
Diffusion Length ◽  
Slow Neutron ◽  
Thermal Neutrons ◽  
Absorption Cross ◽  
A Value ◽  
Length Measurements ◽  
Theoretical Predictions ◽  
Made In

The diffusion length of thermal neutrons in water has been measured at various temperatures between 18 and 255 °C, the source being 124 Sb-Be (25 keV). Diffusion length measurements were also made in water with three boric acid concentrations and with water poisoned with a cadmium sulphate solution, the measurements being taken over a temperature range of 18 to 200 °C. The variation with temperature of the diffusion coefficient of water was determined from the experiments with poisoned water. A value 0.324 + 0.006 barn was obtained for the 2200 m/s microscopic absorption cross section of hydrogen. Close agreement was found between the experimental results and theoretical predictions based on the Nelkin model for slow neutron scattering.

Detection of Non-Metallic Cords Using Synthetic Aperture Acoustic Imaging

2012 ◽  
Author(s):  
John A. Judge ◽  
Joseph F. Vignola ◽  
Aldo A. J. Glean ◽  
Teresa J. Ryan ◽  
Chelsea E. Good ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Ground Surface ◽  
Acoustic Imaging ◽  
Acoustic Energy ◽  
Synthetic Aperture ◽  
Two Dimensional ◽  
Two Dimensional Image ◽  
Imaging Approach ◽  
Different Diameters ◽  
Made In

Synthetic aperture acoustic (SAA) imaging is a technique for remotely obtaining information about the location, geometry, and mechanical properties of objects based on the way they scatter incident acoustic energy. Results are presented for an experimental investigation of the use of SAA imaging to detect non-metallic cords of different sizes laid in various configurations on the ground surface in an outdoor urban environment. Interest in this application of SAA stems from the fact that non-metallic cords are not readily detectable with synthetic aperture radar (SAR) and that the SAA imaging approach represents a relatively inexpensive alternative or supplement to SAR. The measurement system is comprised of a mobile acoustic transceiver (a speaker and microphone) that broadcasts a burst chirp with a bandwidth of 2–15 kHz. The recorded signal is used to form a two-dimensional image of the distribution of acoustic scatterers within the scene. For this study, five different diameters (2–15mm) of nylon cord laid on the ground were imaged in different configurations. These measurements were made in the presence of urban ambient noise of varying levels. The goal of this study was to identify the effect of environmental noise and other parameters on detectability. The results demonstrate that non-metallic cords can be detected acoustically if the angle to the transceiver path is sufficiently small.

Dynamic Stress Dissipated Energy Rating of Materials with Maxwell Rheological Behavior

2015 ◽  
Vol 801 ◽  
pp. 115-121 ◽  
Author(s):  
Polidor Bratu
Keyword(s):  
Dynamic System ◽  
Rheological Behavior ◽  
Dynamic Stress ◽  
Hysteresis Loops ◽  
Dissipated Energy ◽  
System Parameters ◽  
Physical Conditions ◽  
Linear Behavior ◽  
Energy Dissipated ◽  
Made In

This paper presents dynamic analysis of rheological behavior of materials modeled as a body under stationary harmonic dynamic action.Excitation force is inertial, because of rotation of eccentric mass, applied directly to the Maxwell rheological body.Based on theoretical and experimental results are highlighted functions for defining both the energy dissipated as hysteresis loops in physical conditions of linear behavior of the components of the Maxwell model.In this context are represented the representative sets of curves that outlines the progress of dissipation made in relation with the dynamic system parameters.

Performance Assessment of Engineered Barriers Using the Vault Model.

1992 ◽  
Vol 294 ◽  
Author(s):  
L.H. Johnson ◽  
D.M. Leneveu
Keyword(s):  
Model Parameters ◽  
Review Panel ◽  
Backfill Materials ◽  
Engineered Barriers ◽  
Uncertainty Analyses ◽  
Engineered Barrier ◽  
And Migration ◽  
Radionuclide Release ◽  
Nuclear Fuel Waste ◽  
Made In

ABSTRACTThe Vault Model for assessing engineered barrier performance has been developed as part of the preparation of an Environmental Impact Statement to be presented to a Federal Environmental Assessment Review Panel reviewing the Canadian nuclear fuel waste disposal concept. The model describes the behaviour of titanium containers, radionuclide release from used fuel, and migration of radionuclides through buffer and backfill materials and into the surrounding geosphere. Vault Model simulations have shown that the release of radionuclides from the engineered barrier system is dominated by the release from the fuel-sheath gap and grain boundaries in used fuel. Sensitivity and uncertainty analyses have illustrated how releases from the vault are affected by both the uncertainty in model parameters and the assumptions made in the development of the models. It is likely that the combined effects of a number of conservatisms in the model result in the releases from the engineered barrier system being overpredicted by several orders of magnitude.

scholarly journals Simple rules guide dragonfly migration

2006 ◽  
Vol 2 (3) ◽  
pp. 325-329 ◽  
Author(s):  
Martin Wikelski ◽  
David Moskowitz ◽  
James S Adelman ◽  
Jim Cochran ◽  
David S Wilcove ◽  
...  
Keyword(s):  
Decision Rules ◽  
Population Level ◽  
Long Distance ◽  
Migration Strategy ◽  
Anax Junius ◽  
Wind Speeds ◽  
Radio Transmitters ◽  
Migratory Patterns ◽  
And Migration ◽  
Made In

Every year billions of butterflies, dragonflies, moths and other insects migrate across continents, and considerable progress has been made in understanding population-level migratory phenomena. However, little is known about destinations and strategies of individual insects. We attached miniaturized radio transmitters ( ca 300 mg) to the thoraxes of 14 individual dragonflies (common green darners, Anax junius ) and followed them during their autumn migration for up to 12 days, using receiver-equipped Cessna airplanes and ground teams. Green darners exhibited distinct stopover and migration days. On average, they migrated every 2.9±0.3 days, and their average net advance was 58±11 km in 6.1±0.9 days (11.9±2.8 km d −1 ) in a generally southward direction (186±52°). They migrated exclusively during the daytime, when wind speeds were less than 25 km h −1 , regardless of wind direction, but only after two nights of successively lower temperatures (decrease of 2.1±0.6 °C in minimum temperature). The migratory patterns and apparent decision rules of green darners are strikingly similar to those proposed for songbirds, and may represent a general migration strategy for long-distance migration of organisms with high self-propelled flight speeds.

scholarly journals Scaling of instability timescales of Antarctic outlet glaciers based on one-dimensional similitude analysis

2019 ◽  
Vol 13 (6) ◽  
pp. 1621-1633 ◽  
Author(s):  
Anders Levermann ◽  
Johannes Feldmann
Keyword(s):  
Response Time ◽  
Dynamic Modeling ◽  
Ice Sheet ◽  
West Antarctica ◽  
Ice Shelf ◽  
One Dimensional ◽  
Physical Conditions ◽  
The One ◽  
The Antarctic ◽  
Made In

Abstract. Recent observations and ice-dynamic modeling suggest that a marine ice-sheet instability (MISI) might have been triggered in West Antarctica. The corresponding outlet glaciers, Pine Island Glacier (PIG) and Thwaites Glacier (TG), showed significant retreat during at least the last 2 decades. While other regions in Antarctica have the topographic predisposition for the same kind of instability, it is so far unclear how fast these instabilities would unfold if they were initiated. Here we employ the concept of similitude to estimate the characteristic timescales of several potentially MISI-prone outlet glaciers around the Antarctic coast. Our results suggest that TG and PIG have the fastest response time of all investigated outlets, with TG responding about 1.25 to 2 times as fast as PIG, while other outlets around Antarctica would be up to 10 times slower if destabilized. These results have to be viewed in light of the strong assumptions made in their derivation. These include the absence of ice-shelf buttressing, the one-dimensionality of the approach and the uncertainty of the available data. We argue however that the current topographic situation and the physical conditions of the MISI-prone outlet glaciers carry the information of their respective timescale and that this information can be partially extracted through a similitude analysis.

XXIV.—The Scattering of Light

1914 ◽  
Vol 33 ◽  
pp. 264-281
Author(s):  
James Robert Milne
Keyword(s):  
Light Scattering ◽  
Systematic Study ◽  
Ground Surface ◽  
Single Layer ◽  
The Other ◽  
Total Emission ◽  
Special Apparatus ◽  
The Many ◽  
The One ◽  
Made In

SummaryThe present paper describes a number of experiments made in connection with Christiansen's experiment in which a beam of light is passed through a transparent insoluble powder immersed in a liquid, with the result that light of the particular colour for which the indices of powder and liquid are the same passes unaffected, while light of all other colours is scattered. In this communication only the simplest case of the above is dealt with, that, namely, in which a flat piece of glass, ground on one side, takes the place of the powder, the rugosities of the ground surface representing a single layer of grains, and air takes the place of the liquid. In such a case there is, of course, no colour of light for which the indices of solid and liquid are alike, and indeed it was found that the colour of the light made very little difference to the results. On the other hand, however, it soon became apparent that different ways of grinding the glass surface led to very different effects. Accordingly, as no previous work appears to have been done in this field, and as it seemed a promising one, it was decided to make a systematic study of the various cases. Each specimen of glass employed was photomicrographed, and had its polar light distribution measured by a photometer. Two methods of characterising the particular scattering power of a screen soon suggested themselves and have been formally defined—the one connected with the Angle of Maximum Total Emission, and the other with the Equivalent Cavity.It is hoped to continue the investigation not only on the above lines, but also in the direction of ascertaining the effect of a number of plates, i.e. of successive layers of light-scattering particles; and in investigating the polarisation effects, which some rough preliminary experiments have shown to be marked.I am glad of this opportunity of acknowledging the help I have received from the Trustees of the Carnegie Trust in the form of grants for the construction of the special apparatus necessary; and desire to tender my grateful thanks to Professor MacGregor for the many facilities for carrying on the work which he kindly placed at my disposal.

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