Analysis of Equivalent Thickness of Geological Media for Lab-scale Study of Radon Exhalation

2021 ◽  
Author(s):  
Changshou Hong ◽  
Yini Yang ◽  
Hong Wang ◽  
Yong Liu ◽  
Xiangyang Li ◽  
...  
Keyword(s):  
Diffusion Length ◽  
Finite Thickness ◽  
Theoretical Models ◽  
Diffusion Experiment ◽  
Medium Thickness ◽  
Equivalent Thickness ◽  
Radon Exhalation ◽  
Mill Tailings ◽  
Radon Diffusion ◽  
The Media

Abstract Geological media are widely distributed in nature. Lab-scale tests are frequently employed in radon studies for these media. Thus, it is critical to find the thickness of the medium at an experimental scale that is equivalent to the medium thickness in a real geological system. Based on the diffusion–advection transport of radon, theoretical models of the surface radon exhalation rate for homogeneous semi-infinite and finite-thickness systems were derived (denoted as Jse and Jfi, respectively). Analysis of the equivalency of Jse and Jfi was subsequently carried out by introducing several dimensionless parameters, including the ratio of the exhalation rates for the semi-infinite and finite-thickness models, ε, and the number of diffusion lengths required to achieve a desired ε value, n. The results showed that when radon transport in geological media is dominantly driven by diffusion, if n > 3.6626, then ε > 95% (and if n > 5.9790, then ε > 99.5%). When radon migration is dominantly driven by advection, if n > 2.5002, then ε > 95% (and if n > 4.0152, then ε > 99.5%). Therefore, if the thickness of the geological media (x0) is greater than a certain n times the radon diffusion length of the media (L), the media can be modeled as semi-infinite. To validate the model, a pure radon diffusion experiment (no advection) was developed using uranium mill tailings, laterite, and radium-bearing rocklike material with different thicknesses (x0). The theoretical model was demonstrated to be reliable and valid. This study provides a basis for determining the appropriate thickness of geological media in lab-scale experiments of radon exhalation.

Analysis of equivalent thickness of geological media for lab-scale study of radon exhalation

2021 ◽  
Author(s):  
Changshou Hong ◽  
Yini Yang ◽  
Hong Wang ◽  
Yong Liu ◽  
Xiangyang Li ◽  
...  
Keyword(s):  
Equivalent Thickness ◽  
Radon Exhalation

scholarly journals Introduction

2007 ◽  
Vol 1 (1) ◽  
Author(s):  
Line Thomsen
Keyword(s):  
Mass Media ◽  
Theoretical Models ◽  
Core Values ◽  
The Other ◽  
Media Convergence ◽  
The Core ◽  
The Press ◽  
The Media

What is journalism? How does it exist and why? How does journalism define itself and in what ways can we make use of looking theoretically at the practice of it? These were the central themes of our workshop; Theoretical Models as Mass Media Practice held at the ‘Minding the Gap’ conference at Reuters Institute in May 2007, from which this collection of papers has been selected. As with the other workshops during the conference, the majority of our panellists were themselves once media practitioners. It is my opinion that this background and inside knowledge of the field in itself can provide an exceptional framework for understanding the workings of mass media while helping the press reflect over these workings too. In a time of change for the journalistic profession, when media convergence is growing; the media is marked by deregulation and fewer journalists are being asked to do more, there is an increased need for the profession to get involved in debating the core values of its existence.

Fractal Analysis of Spatial Distribution of Radon Exhalation Rates of Uranium Mill Tailings

2012 ◽  
Vol 524-527 ◽  
pp. 584-587
Author(s):  
Yan Shi Xie ◽  
Kai Xuan Tan ◽  
Liang Chen ◽  
Kai Guang Hu ◽  
Zheng Qing Wang ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Fractal Structure ◽  
Pore Connectivity ◽  
Fractal Method ◽  
Radon Exhalation ◽  
Two Dimension ◽  
Radium Content ◽  
Mill Tailings ◽  
Radon Exhalation Rates ◽  
Uranium Mill Tailings

A uranium mill tailings, located in Guangdong, was selected for spatial distribution of the radon exhalation rates measured by local static method. The two-dimension surface of radon exhalation rates was established by Surfer using the data of spatial distribution of radon exhalation rates measured at August 14, 2007 to 19 and 21, which was analyzed by fractal method of projective covering. The results show that the two-dimension surface of radon exhalation rates is of fractal structure. The fractal dimension of surface of radon exhalation rates from August 14, 2007 to 19 and 21 are 2.0535, 2.0173, 2.0029, 2.0084, 2.0079, 2.0057 and 2.0034, respectively, which indicates that the complexity of spatial distribution of the radon exhalation rates at 14 and 15 are larger than that of the other days. The phenomenon results from the change of precipitation and temperature, as well as the features of uranium mill tailings, including mineral composition, particle size, radium content, porosity and pore connectivity, etc.

Measurement of radon diffusion and exhalation from uranium mill tailings piles

1979 ◽  
Vol 13 (8) ◽  
pp. 962-964 ◽  
Author(s):  
Wyatt B. Silker ◽  
Nedwin A. Wogman ◽  
Charles W. Thomas ◽  
Daniel B. Carr ◽  
Patrick C. Heasler
Keyword(s):  
Mill Tailings ◽  
Radon Diffusion ◽  
Uranium Mill Tailings

scholarly journals Charismatic Leaders in a New Perspective: Reality in Estonia and Italy

2020 ◽  
Vol 8 (1) ◽  
pp. 11
Author(s):  
Ülle Toode
Keyword(s):  
Political Communication ◽  
Max Weber ◽  
Theoretical Models ◽  
Charismatic Leadership ◽  
Political Leaders ◽  
The Media ◽  
New Perspective ◽  
Popular Subject ◽  
A Current ◽  
Web Media

The purpose of this explorative study is to put the existing theories on charismatic political leadership in a current post-web media context. It also seeks to better understand why “charismatic politicians” seem to have success in present-day cyber politics. The paper considers political charisma in a Weberian perspective and aims to explain what elements it includes in a current electoral environment characterized by a fast-changing media landscape. The paper places the existing theoretical models in the context of two European societies, by comparing Estonia and Italy as case studies. Estonia, a small ex-Soviet country has emerged in recent years as an advanced e-society with highly “internetisized” media. At the same time, Italy became known by the phenomenon of the “Berlusconization” of the media, a popular subject of study in political communication. The analysis considers existing research, mostly based on the work of Max Weber, and aims to test the index of charisma, developed by Pappas (2011), in the two observed countries. The paper concludes with a discussion on if and how charismatic political leaders fit a deliberative democracy. Finally, attention is drawn to the need for further systematic comparative research to better understand the phenomenon of charismatic leadership in the post-web media environment.

Experimental Study of Radon Exhalation Rate in Uranium-Like Rock Based on Closed Chamber Method

2018 ◽  
Author(s):  
Fuliang Jiang ◽  
Xiaoli Wang ◽  
Shuai Zhang ◽  
Xiangyang Li ◽  
Changshou Hong
Keyword(s):  
Diffusion Length ◽  
Underground Mining ◽  
Similarity Theory ◽  
Radon Exhalation Rate ◽  
Exhalation Rate ◽  
Closed Chamber ◽  
Radon Exhalation ◽  
Chamber Method ◽  
Diffusion Phenomena ◽  
Closed Chamber Method

The closed chamber method is widely used in measuring radon exhalation rate, which can avoid the error caused by the leakage and anti-diffusion phenomena. Firstly, considering the actual situation that uranium ore is difficult to obtain and have a high radioactivity, the uranium-like rock was made according to the similarity theory. Secondly, the diffusion length and intrinsic radon exhalation rate were obtained by using the closed chamber method. Thirdly, the theoretical values of radon exhalation rate made by uranium-like ore block were calculated, compared with the measured values. This study shows that the uranium-like rock block made by the best mass ratio is helpful for the subsequent experiment, and the error between the theoretical calculation and the measured value is no more than 9.14%. This indicates it is reliable to estimate radon exhalation rate by diffusion length and intrinsic radon exhalation rate and can also provide a foundation for rapidly gaining radon exhalation rate of the same type material by the closed chamber method. This study can further promote the study of the radon exhalation rate under the complex physical conditions and then better guide the protection work of radon radiation in underground mining.

STEM/X-ray microanalysis across α/γ interfaces in Fe-Ni meteorites

1978 ◽  
Vol 36 (1) ◽  
pp. 416-417
Author(s):  
D. B. Williams ◽  
J. I. Goldstein
Keyword(s):  
Electron Beam ◽  
Spatial Resolution ◽  
Ion Beam ◽  
Finite Thickness ◽  
Theoretical Models ◽  
X Ray ◽  
Internal Precipitation ◽  
Precipitation Reactions ◽  
Two Phases ◽  
Characteristic Microstructure

Fe-Ni meteorites have cooled at rates ∼1-10°C/106 years giving rise to a characteristic microstructure of Widmanstatten bcc α plates that have nucleated and grown from the parent fcc γ phase. This transformation results in rejection of Ni into the remaining γ, which also exhibits a variety of internal precipitation reactions. The Ni concentration at the α/γ interface should be close to the equilibrium value between the two phases and this has been determined in several meteorites, using a Philips EM300 TEM/STEM equipped with X-ray microanalytical facilities. The sharp α/γ interface also permits a practical determination to be made of the spatial resolution of the technique. This has been performed and the result compared with the predictions of two theoretical models describing the spatial resolution in terms of the spreading of the electron beam within specimens of finite thickness.Specimens of the meteorites were sectioned such that the α/γ interface was normal to the surface, then 3mm discs were spark machined, ground to ∼100 μm thick, then ion beam thinned to electron transparency

The Policymaking Process

2017 ◽  
pp. 1-28
Author(s):  
Rajesh Chakrabarti ◽  
Kaushiki Sanyal
Keyword(s):  
Public Policy ◽  
Literature Review ◽  
Policy Process ◽  
Policy Making ◽  
Theoretical Models ◽  
International Literature ◽  
Policy Making Process ◽  
The Media ◽  
Law Making

This introductory chapter is a scene setter, aimed at public policy scholars and practitioners alike. It provides an outline and brief description of the book and provides a background for its subject matter. It provides a dipstick literature review of the existing literature on social movements and external influences on the policy process. It summarizes the key theoretical models of policy making in the international literature for understanding the policy process and provides a brief review of the policy making process in India, as well as a description, in some detail, of the various stages of law-making in the country. The exposition of the various stages of law-making provides an overview of the influence that various stakeholders in the policy process—the media, judiciary, civil society, and so on—can exert in the process.

Measurement of radon diffusion length in thin membranes

2012 ◽  
Vol 150 (4) ◽  
pp. 434-440 ◽  
Author(s):  
A. Malki ◽  
N. Lavi ◽  
M. Moinester ◽  
H. Nassar ◽  
E. Neeman ◽  
...  
Keyword(s):  
Diffusion Length ◽  
Radon Diffusion ◽  
Thin Membranes
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