scholarly journals Cyclically Deformed Defects and Topological Mass Constraints

2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
A. E. Bernardini ◽  
Roldão da Rocha
Keyword(s):  
Quantum Mechanics ◽  
Cyclic Deformation ◽  
Defect Structure ◽  
Analytical Calculation ◽  
Defect Structures ◽  
Constraint Equations ◽  
Straightforward Generalization ◽  
Deformation Processes ◽  
Usual Theory ◽  
Topological Mass

A systematic procedure for obtaining defect structures through cyclic deformation chains is introduced and explored in detail. The procedure outlines a set of rules for analytically constructing constraint equations that involve the finite localized energy of cyclically generated defects. The idea of obtaining cyclically deformed defects concerns the possibility of regenerating a primitive (departing) defect structure through successive, unidirectional, and eventually irreversible, deformation processes. Our technique is applied on kink-like and lump-like solutions in models described by a single real scalar field such that extensions to quantum mechanics follow the usual theory of deformed defects. The preliminary results show that the cyclic device supports simultaneously kink-like and lump-like defects into 3- and 4-cyclic deformation chains with topological mass values closed by trigonometric and hyperbolic deformations. In a straightforward generalization, results concerning the analytical calculation ofN-cyclic deformations are obtained, and lessons regarding extensions from more elaborated primitive defects are depicted.

A new type of defect structure in 124-superconducting oxide revealed by HREM

1991 ◽  
Vol 49 ◽  
pp. 1092-1093
Author(s):  
R. Sharma ◽  
B.L. Ramakrishna ◽  
N.N. Thadhani ◽  
D. Hianes ◽  
Z. Iqbal
Keyword(s):  
Shock Wave ◽  
Defect Structure ◽  
Neutron Radiation ◽  
Weak Links ◽  
Defect Structures ◽  
New Materials ◽  
New Type ◽  
Current Densities ◽  
Processing Techniques ◽  
Microstructural Studies

After materials with superconducting temperatures higher than liquid nitrogen have been prepared, more emphasis has been on increasing the current densities (Jc) of high Tc superconductors than finding new materials with higher transition temperatures. Different processing techniques i.e thin films, shock wave processing, neutron radiation etc. have been applied in order to increase Jc. Microstructural studies of compounds thus prepared have shown either a decrease in gram boundaries that act as weak-links or increase in defect structure that act as flux-pinning centers. We have studied shock wave synthesized Tl-Ba-Cu-O and shock wave processed Y-123 superconductors with somewhat different properties compared to those prepared by solid-state reaction. Here we report the defect structures observed in the shock-processed Y-124 superconductors.

A New-Type of Defect Generation at a 4H-SiC/SiO2 Interface by Oxidation Induced Compressive Strain

2013 ◽  
Vol 740-742 ◽  
pp. 469-472 ◽  
Author(s):  
Kenta Chokawa ◽  
Shigenori Kato ◽  
Katsumasa Kamaiya ◽  
Kenji Shiraishi
Keyword(s):  
Defect Structure ◽  
Density Functional ◽  
Oxidation Process ◽  
Present Report ◽  
Compressive Strain ◽  
Defect Structures ◽  
Forming Process ◽  
Functional Theory ◽  
New Type ◽  
Related Defect

Our message is oxidation process must be minimized as possible. Many carbon-related defect structures are reported in SiC/SiO2 interface. In this paper, we investigated the effect of oxidation to the defect forming by density functional theory (DFT). In the result, we found carbon defect structure that completely different from in the present report. This defect structure has carbon-carbon single bond with no dangling bond. To see the forming process, compressive strain from inserted oxygen atoms induce the rearrangement of structure and cause C-C defect structure. We can know that this structure is formed with energy gain about 3.8eV. And this C-C defect induces trap state under the conduction bottoms.

Defect Structures in Neutron Irradiated 6H-SiC Studied by X-Ray Diffraction Line Profile Analysis

2000 ◽  
Vol 640 ◽  
Author(s):  
C. Seitz ◽  
A. Magerl ◽  
R. Hock ◽  
H. Heissenstein ◽  
R. Helbig
Keyword(s):  
Line Profile ◽  
Correlation Length ◽  
Defect Structure ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
Defect Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Annealing Temperatures ◽  
Diffraction Line Profile

ABSTRACTWe have investigated by x-ray diffraction defect structures in 6H-SiC after neutron irradiation with different fluences and followed by different annealing procedures. An interpretation along a model of Klimanek [1, 4–6] shows, that higher fluences lead to a stronger than linear reduction of the correlation length, whereas higher annealing temperatures correlate with a better recovery of the correlation length. In addition defects of 1st kind created by irradiation are reduced by annealing. We find that annealing changes the character of the defects and it accentuates a defect structure already present in the original samples.

Stresses in anvil — strip system during production of copper sheets in continuous casting and deformation installation

2020 ◽  
pp. 508-511
Author(s):  
O.S. Lekhov ◽  
D.Kh. Bilalov
Keyword(s):  
Continuous Casting ◽  
Cyclic Deformation ◽  
Deformation Zone ◽  
Deformation Process ◽  
Loading Pattern ◽  
Tangential Stresses ◽  
Nite Element ◽  
Calculation Results ◽  
Deformation Processes

The prospects for development of combined continuous casting and deformation processes in production of sheets from nonferrous metals and alloys are considered. Technological possibilities of combined continuous casting and deformation process installation for production of cooper sheets are described. Problem of simultaneous determination of stress-strain state of metal in cyclic deformation zone and stresses in anvils on reduction force in the production on installation of cooper sheets is given. The calculation results are obtained by solving the problems of elastic-plasticity and elastic by fi nite element method using the ANSYS package. The regularities for the distribution of axial and tangential stresses in the cyclic deformation zone in the production on instal lation of cooper sheets are presented. Design scheme and loading pattern of anvil in the production on installation of cooper sheets is described. The values and regularities of axial stresses distribution in anvils of installation depending on reduction force are presented.

Strain-Rate-Dependent Deformation Behavior of Carbon-Black-Filled Rubber under Monotonic and Cyclic Straining

2007 ◽  
Vol 340-341 ◽  
pp. 1017-1024 ◽  
Author(s):  
Yoshihiro Tomita ◽  
K. Azuma ◽  
M. Naito
Keyword(s):  
Strain Rate ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Viscoelastic Deformation ◽  
Rate Dependent ◽  
Filled Rubber ◽  
Deformation Behaviors ◽  
Deformation Processes ◽  
The Individual ◽  
Cyclic Straining

The constitutive equation of rubber is derived by employing a nonaffine molecular chain network model for an elastic deformation behavior and the reptation theory for a viscoelastic deformation behavior. The results reveal the roles of the individual springs and dashpot, and the strain rate dependence of materials and disentanglement of molecular chains in the monotonic and cyclic deformation behaviors, particularly softening and hysteresis loss, that is, the Mullins effect, occurring in stress-stretch curves under cyclic deformation processes.

An expert system for the structural characterization of kaolinites

Clay Minerals ◽  
1990 ◽  
Vol 25 (3) ◽  
pp. 249-260 ◽  
Author(s):  
A. Plançon ◽  
C. Zacharie
Keyword(s):  
Expert System ◽  
Defect Structure ◽  
Defect Structures ◽  
X Ray Diffraction ◽  
Diffraction Profile ◽  
X Ray ◽  
Diffraction Patterns ◽  
Xrd Patterns

AbstractUntil recently, the determination of the defect structures (previously referred to incorrectly as “crystallinity”) of kaolinites has been obtained in one of two ways: (1) measurement of the Hinckley index, or (2) by comparing calculated X-ray diffraction patterns based on a model of the defect structure (including types of defects and abundances) with experimental diffraction profiles. The Hinckley method is simple and easy to perform but contains no real information about the defect structure. Calculated XRD patterns are based on real defects but these calculations are time consuming and require some skill in application. Another approach is proposed: an expert system which will accurately describe the defect structure of kaolinites based on a few measurements taken from a normal powder diffraction profile. This system has been verified for nine kaolinite samples for which the defect structure was previously determined by comparison of calculated and observed diffraction profiles. The expert system reproduced the correct defect structure for each of the samples.

Effect of Impurities on the Defects in Oxides and Their Relationship to Oxidation of Metal

CORROSION ◽  
1968 ◽  
Vol 24 (11) ◽  
pp. 379-388 ◽  
Author(s):  
PER KOFSTAD
Keyword(s):  
Point Defect ◽  
Defect Structure ◽  
Oxygen Vacancies ◽  
Defect Concentration ◽  
Defect Structures ◽  
Small Deviations ◽  
Effect Of Impurities ◽  
And Control ◽  
Simple Behavior ◽  
Wagner Theory

Abstract The defect structure of the oxygen-deficient oxides of Nb2O5, Ta2O5, and ZrO2 are discussed. It is suggested that the oxygen vacancies are probably the important defects, except possibly at the most oxygen deficient part of the homogeneity ranges where interstitial cations may predominate. At high oxygen pressures, (small deviations from stoichiometry) effects of impurities become important and, in reported studies, probably determine the point defect concentration. Oxidation of Nb, Ta, Zr, resulting in growth of compact scales of Nb2O5 Ta2O5, and ZrO2, is discussed on the basis of these considerations. It is shown that effects of impurities may explain apparent deviations from the simple behavior predicted by the Wagner theory. It is emphasized that analysis and control of impurities is essential in interpretation of defect structures of oxides and defect-controlled properties and reactions.

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