scholarly journals A periodic pumping technique of soil gas for 222Rn stabilization in large calibration chambers: part 2—theoretical formulation and experimental validation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Trilochana Shetty ◽  
Y. S. Mayya ◽  
K. Sudeep Kumara ◽  
B. K. Sahoo ◽  
B. K. Sapra ◽  
...  
Keyword(s):  
Large Volume ◽  
Mathematical Formulation ◽  
Temporal Stability ◽  
High Strength ◽  
Soil Gas ◽  
Dynamic Mode ◽  
Theoretical Formulation ◽  
Safety Issues ◽  
Injection Pump ◽  
Calibration Chamber

Abstract In an adjoining publication, we demonstrated the novel technique to harvest soil gas of natural origin as a highly efficient source of 222Rn for calibration applications in a large volume 222Rn calibration chamber. Its advantages over the use of conventional high strength 226Ra sources, such as the capability to serve as a non-depleting reservoir of 222Rn and achieve the desired concentration inside the calibration chamber within a very short time, devoid of radiation safety issues in source handling and licensing requirements from the regulatory authority, were discussed in detail. It was also demonstrated that stability in the 222Rn concentration in large calibration chambers could be achieved within ± 20% deviation from the desired value through a semi-dynamic mode of injection in which 222Rn laden air was periodically pumped to compensate for its loss due to leak and decay. The necessity of developing a theory for determining the appropriate periodicity of pumping was realized to get good temporal stability with a universally acceptable deviation of ≤ ± 10% in the 222Rn concentration. In this paper, we present a mathematical formulation to determine the injection periods (injection pump ON and OFF durations) for the semi-dynamic operation to achieve long term temporal stability in the 222Rn concentration in the chamber. These computed pumping parameters were then used to efficiently direct the injection of soil gas into the chamber. We present the mathematical formulation, and its experimental validations in a large volume calibration chamber (22 m3). With this, the temporal stability of 222Rn concentration in the chamber was achieved with a deviation of ~ 3% from the desired value.

scholarly journals An innovative technique of harvesting soil gas as a highly efficient source of 222Rn for calibration applications in a walk-in type chamber: part-1

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
N. Karunakara ◽  
Trilochana Shetty ◽  
B. K. Sahoo ◽  
K. Sudeep Kumara ◽  
B. K. Sapra ◽  
...  
Keyword(s):  
High Strength ◽  
Soil Gas ◽  
Dynamic Mode ◽  
Safety Issues ◽  
Highly Efficient ◽  
Mode Of Operation ◽  
Flow Through ◽  
Calibration Chamber ◽  
A New Technique ◽  
Calibration Laboratories

Abstract The paper describes a novel technique to harvest 222Rn laden air from soil gas of natural origin as a highly efficient source of 222Rn for calibration applications in a walk-in type 222Rn calibration chamber. The technique makes use of a soil probe of about 1 m to draw soil gas, through a dehumidifier and a delay volume, using an air pump to fill the calibration chamber. 222Rn concentration in the range of a few hundred Bq m−3 to a few tens of kBq m−3 was easily attained in the chamber of volume 22.7 m3 within a short pumping duration of 1 h. A new technique referred to as “semi-dynamic mode of operation” in which soil gas is injected into the calibration chamber at regular intervals to compensate for the loss of 222Rn due to decay and leak is discussed. Harvesting soil gas has many important advantages over the traditional methods of 222Rn generation for calibration experiments using finite sources such as solid flow-through, powdered emanation, and liquid sources. They are: (1) soil gas serves as an instantaneous natural source of 222Rn, very convenient to use unlike the high strength 226Ra sources used in the calibration laboratories, and has no radiation safety issues, (2) does not require licensing from the regulatory authority, and (3) it can be used continuously as a non-depleting reservoir of 222Rn, unlike other finite sources. The newly developed technique would eliminate the need for expensive radioactive sources and thereby offers immense application in a variety of day to day experiments—both in students and research laboratories.

scholarly journals Evaluation and instrumentation of the drop weight tear test

2012 ◽  
Vol 3 (1) ◽  
pp. 52-58
Author(s):  
S. Vervaet ◽  
W. De Waele
Keyword(s):  
High Strength ◽  
Test Method ◽  
Opening Angle ◽  
Safety Issues ◽  
Natural Gas Pipelines ◽  
Drop Weight Tear Test ◽  
Fracture Appearance ◽  
Oil And Natural Gas ◽  
Linepipe Steels ◽  
Crack Tip Opening

With the use of high strength and high toughness steels in the pipeline industry it has become necessary tobetter understand the factors which influence the reliability and integrity of oil and natural gas pipelines. TheDrop-Weight Tear Test (DWTT) is a common test method to determine the fracture appearance andfracture ductility of steel. Its fundamental purpose is to determine the appearance of propagating fracturesin steels over the temperature range where the fracture mode changes from brittle to ductile. But there arestill many subjects of discussion concerning which results must be obtained, in which manner they shouldbe obtained and how they should be interpreted. Is it still possible to deduce a shear appearance fromsamples which have such an abnormal fracture that they used to be discarded as invalid ? Could resultsfrom the DWTT be correlated with the Crack Tip Opening Angle (CTOA), which is particularly important forfinite element modelling ? What to think about methods such as the two specimen CTOA and the simplifiedsingle specimen method ? How severe is the effect of tunnelling in contemporary linepipe steels and howcan this be dealt with ? Many questions still remain and many aspects are still vague despite the correlatingecological, economical and safety issues. Therefore, there is a major necessity for further investigations.

scholarly journals A MATLAB-Based Symbolic Approach for the Quick Developing of Nonlinear Solid Mechanics Finite Elements

2020 ◽  
Author(s):  
Antonio Bilotta
Keyword(s):  
Finite Elements ◽  
Solid Mechanics ◽  
Mathematical Formulation ◽  
Object Oriented Programming ◽  
Theoretical Formulation ◽  
Tetrahedral Element ◽  
Plane Element ◽  
Deformation Kinematics ◽  
Nonlinear Solid Mechanics ◽  
Symbolic Approach

A symbolic mathematical approach for the rapid early phase developing of finite elements is proposed. The algebraic manipulator adopted is MATLAB® and the applicative context is the analysis of hyperelastic solids or structures under the hypothesis of finite deformation kinematics. The work has been finalized through the production, in an object-oriented programming style, of three MATLAB® classes implementing a truss element, a tetrahedral element and plane element. The approach proposed, starting from the mathematical formulation and finishing with the code implementation, is described and its effectiveness, in terms of minimization of the gap between the theoretical formulation and its actual implementation, is highlighted.

The effect of focal depth on the spectra of P waves I. Theoretical formulation

1970 ◽  
Vol 60 (5) ◽  
pp. 1437-1456 ◽  
Author(s):  
Shyamal K. Guha
Keyword(s):  
Boundary Value Problem ◽  
Boundary Value ◽  
Mathematical Formulation ◽  
Focal Depth ◽  
Point Sources ◽  
Body Waves ◽  
Elastic Plane ◽  
Theoretical Formulation ◽  
P Waves ◽  
Homogeneous Half Space

Abstract Since the Earth's free surface acts as a reflector, one may except the spectra of seismic body waves to be influenced by the focal depth of an earthquake. In order to investigate this effect, a boundary value problem has been formulated involving (n − 1) homogeneous, isotropic, perfectly elastic plane layers overlying a homogeneous half-space. The sources of the elastic waves are represented as discontinuities of stress across a conceptual interface inside the medium. Certain functions of the wave potentials which govern the solution of the boundary value problem are denoted as the source functions in the mathematical formulation of the problem. Expressions for the source functions for P and SV waves are derived for different kinds of point sources, including a double couple point source oriented in an arbitrary manner inside the medium.

The Role of Interstitial Fluid Pressurization and Surface Porosities on the Boundary Friction of Articular Cartilage

1998 ◽  
Vol 120 (2) ◽  
pp. 241-248 ◽  
Author(s):  
G. A. Ateshian ◽  
Huiqun Wang ◽  
W. M. Lai
Keyword(s):  
Articular Cartilage ◽  
Friction Coefficient ◽  
Interstitial Fluid ◽  
Mathematical Formulation ◽  
Friction Model ◽  
Experimental Results ◽  
Boundary Friction ◽  
Confined Compression ◽  
Theoretical Formulation ◽  
Fluid Pressurization

Articular cartilage is the remarkable bearing material of diarthrodial joints. Experimental measurements of its friction coefficient under various configurations have demonstrated that it is load-dependent, velocity-dependent, and time-dependent, and it can vary from values as low as 0.002 to as high as 0.3 or greater. Yet, many studies have suggested that these frictional properties are not dependent upon the viscosity of synovial fluid. In this paper, a theoretical formulation of a boundary friction model for articular cartilage is described and verified directly against experimental results in the configuration of confined compression stress-relaxation. The mathematical formulation of the friction model can potentially explain many of the experimentally observed frictional responses in relation to the pressurization of the interstitial fluid inside cartilage during joint loading, and the equilibrium friction coefficient which prevails in the absence of such pressurization. In this proposed model, it is also hypothesized that surface porosities play a role in the regulation of the frictional response of cartilage. The good agreement between theoretical predictions and experimental results of this study provide support for the proposed boundary friction formulation.

Research on Chip Breaking Mechanism of High-Temperature and High-Strength Steel 2.25Cr-1Mo-0.25V

2010 ◽  
Vol 142 ◽  
pp. 248-252
Author(s):  
Er Liang Liu ◽  
Yu Fu Li ◽  
X.Z. Wang ◽  
Fei Xiao ◽  
Xian Li Liu
Keyword(s):  
High Temperature ◽  
High Strength Steel ◽  
Mathematical Formulation ◽  
High Strength ◽  
Cutting Parameters ◽  
Chip Breaking ◽  
Section Profile ◽  
Paper Chip ◽  
Breaking Mechanism ◽  
On Chip

In the process of turning high-temperature and high-strength steel, it is an effective method for chip breaking with complicated groove insert. In this paper, chip breaking mechanism is analyzed using the coated complicate groove insert for cutting high-temperature and high-strength steel. The model of chip curl radios is constructed though analyzing the effect of complicated groove insert on chip formation. The mathematical formulation of chip section profile coefficient is built through analyzing influential effect of complicated groove on chip section profile. The chip breaking model is developed according to chip-breaking criterion. Finally, a full experimental validation of the model is presented for chip breaking when the workpiece is high-temperature and high-strength steel, 2.25Cr-1Mo-0.25V. The tested results show the chip breaking model is reasonable, and the optimization cutting parameters are obtained.

Safety Issues In Ultrasound-Assisted Large-Volume Lipoplasty

1999 ◽  
Vol 26 (2) ◽  
pp. 317-335 ◽  
Author(s):  
Mark D. Gilliland ◽  
George W. Commons ◽  
Bruce Halperin
Keyword(s):  
Large Volume ◽  
Safety Issues ◽  
Ultrasound Assisted

scholarly journals Three-Dimensional Modeling of Thermal-Mechanical Behavior of Accident Tolerant Fuels

2021 ◽  
Vol 9 ◽  
Author(s):  
Zitao Zeng ◽  
Yongyu Pan ◽  
Xi Chen ◽  
Chunyu Zhang ◽  
Chunyu Yin ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Three Dimensional ◽  
High Strength ◽  
Physical Models ◽  
Safety Issues ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
High Oxidation Resistance ◽  
Release Model ◽  
Physical Quantities

Considering the safety issues of the traditional UO2-Zr fuel, a variety of accident-tolerant fuel (ATF) candidates have been proposed in recent years. Among the several ATFs, U3Si2, and UN are the two promising candidates for fuel materials owing to their high thermal conductivity and high uranium density. The FeCrAl alloy and the SiC/SiC composite material are the two promising candidates for cladding owing to their high oxidation resistance and high strength. In order to quantitatively evaluate the performance of ATFs, this study summarizes the physical models of typical ATF cladding materials (FeCrAl and SiC) and pellet materials (UN and U3Si2). Then a three-dimensional non-linear finite element method is applied to simulate the thermal-mechanical behavior of several typical fuel-cladding combinations, including UO2-FeCrAl, UN-FeCrAl, U3Si2-FeCrAl, U3Si2-Zr, and U3Si2-SiC. The important physical quantities, such as the fuel centerline temperature, the deformation of the pellet and the cladding as well as the pellet-cladding mechanical interaction (PCMI) were studied. The fission gas release model was also verified and improved.

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