Local thermal bistability in MgB2 microwave coplanar resonators: Opposite jumpwise response to weak-link switching and to vortex avalanches

2009 ◽  
Vol 94 (5) ◽  
pp. 052505 ◽  
Author(s):  
G. Ghigo ◽  
R. Gerbaldo ◽  
L. Gozzelino ◽  
F. Laviano ◽  
G. Lopardo ◽  
...  
Keyword(s):  
Weak Link ◽  
Vortex Avalanches

Structural analysis of a Σ5 grain boundary in YBa2Cu3O7δ

1993 ◽  
Vol 51 ◽  
pp. 942-943
Author(s):  
J.-Y. Wang ◽  
Y. Zhu ◽  
A.H. King ◽  
M. Suenaga
Keyword(s):  
Grain Boundary ◽  
Lattice Mismatch ◽  
Weak Link ◽  
Coincidence Site Lattice ◽  
Large Angle ◽  
Dislocation Core ◽  
Superconducting Order Parameter ◽  
Outstanding Problem ◽  
Transmission Electron

One outstanding problem in YBa2Cu3O7−δ superconductors is the weak link behavior of grain boundaries, especially boundaries with a large-angle misorientation. Increasing evidence shows that lattice mismatch at the boundaries contributes to variations in oxygen and cation concentrations at the boundaries, while the strain field surrounding a dislocation core at the boundary suppresses the superconducting order parameter. Thus, understanding the structure of the grain boundary and the grain boundary dislocations (which describe the topology of the boundary) is essential in elucidating the superconducting characteristics of boundaries. Here, we discuss our study of the structure of a Σ5 grain boundary by transmission electron microscopy. The characterization of the structure of the boundary was based on the coincidence site lattice (CSL) model.Fig.l shows two-beam images of the grain boundary near the projection. An array of grain boundary dislocations, with spacings of about 30nm, is clearly visible in Fig. 1(a), but invisible in Fig. 1(b).

Effect of thermal annealing on grain boundary chemistry of polycrystalline TiBa2Ca2Cu3Oy films

1994 ◽  
Vol 52 ◽  
pp. 968-969
Author(s):  
Z. L. Wang ◽  
C. L. Briant ◽  
J. DeLuca ◽  
A. Goyal ◽  
D. M. Kroeger ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Weak Link ◽  
Zero Field ◽  
Stabilized Zirconia ◽  
Local Texture ◽  
Transmission Electron ◽  
Axis Alignment ◽  
Boundary Chemistry ◽  
Small Misorientation ◽  
Misorientation Angles

Recent studies have shown that spray-pyrolyzed films of the Tl-1223 compound (TlxBa2Ca2Cu3Oy, with 0.7 < × < 0.95) on polycrystalline yttrium stabilized zirconia substrates can be prepared which have critical current density Jc near 105 A/cm2 at 77 K, in zero field. The films are polycrystalline, have excellent c-axis alignment, and show little evidence of weak-link behavior. Transmission electron microscopy (TEM) studies have shown that most grain boundaries have small misorientation angles. It has been found that the films have a nigh degree of local texture indicative of colonies of similarly oriented grains. It is believed that inter-colony conduction is enhanced by a percolative network of small angle boundaries at colony interfaces. It has also been found that Jc is increased by a factor of 4 - 5 after the films were annealed at 600 °C in oxygen. This study is thus carried out to determine the effect on grain boundary chemistry of the heat treatment.

3-D Characterization of Global and Local Microstructural Effects on Spall Damage in Shock Loaded FCC Metals: Experimental and Modeling

2013 ◽  
Author(s):  
A. Brown ◽  
K. Krishnan ◽  
L. Wayne ◽  
P. Peralta ◽  
S. N. Luo ◽  
...  
Keyword(s):  
Weak Link ◽  
Heat Treatments ◽  
Taylor Factor ◽  
Weak Links ◽  
Spall Damage ◽  
Heat Treated ◽  
Microstructural Effects ◽  
Global And Local ◽  
Low Pressures

Global and local microstructural weak links for spall damage were investigated using 3-D characterization in polycrystalline (PC) and multicrystalline (MC) copper samples, respectively. All samples were shocked via flyer-target plate experiments using a laser drive at low pressures (2–6 GPa). The flyer plates measured approximately 500 μm thick and 8 mm in diameter and the target plates measured approximately 1000 μm thick and 10 mm in diameter. Electron Backscattering Diffraction (EBSD) and optical microscopy were used to determine to presence of voids and relate them to the surrounding microstructure. Statistics on the strength of grain boundaries (GBs) was conducted by analyzing PC samples and collecting the misorientation across GBs with damage present, and it was found that a misorientation range of 25–50° is favorable for damage. Statistics were also taken of copper PC samples that had undergone different heat treatments and it was found that although the 25–50° range is less dominant, it is still favorable for damage nucleation. Removal of initial plastic strain via heat treatments and an increase in Σ3 CSL boundaries, indicative of strong annealing twins, also led to an increased amount of transgranular damage. 3-D X-ray tomography data were used to investigate the shape of the voids present in untreated, as received and heat treated samples. It was found that the as received sample contained a higher amount of “disk”, or, “sheet-like” voids indicative of intergranular damage, whereas the heat treated samples had a higher fraction of spherical shaped voids, indicative of transgranular damage. MC samples were used to study microstructural weak links for spall damage because the overall grain size is much larger than the average void size, making it possible to determine which GBs nucleated damage. Simulations and experimental analysis of damage sites with large volumes indicate that high Taylor factor mismatches with respect to the crystallographic grain GB normal is the primary cause for the nucleation of damage at a GB interface and a low Taylor factor along the shock direction in either grain drives void growth perpendicular to the GB. Cases where experimental results show damage and simulation results show no damage are attributed to the presence of an intrinsic microstructural weak link, such as an incoherent twin boundary.

Understanding the Technology Development Process at the Early Standardization Stage

2014 ◽  
Vol 12 (2) ◽  
pp. 1-20 ◽  
Author(s):  
Vladislav V. Fomin ◽  
Hanah Zoo ◽  
Heejin Lee
Keyword(s):  
Content Analysis ◽  
Software Defined Radio ◽  
Development Process ◽  
Technology Development ◽  
Weak Link ◽  
Early Stage ◽  
Radio Spectrum ◽  
Theoretical Frameworks ◽  
Development Framework ◽  
Practical Usefulness

This research is aimed at developing a document content analysis method to be applied in studies of standardization and technology development. The proposed method integrates two theoretical frameworks: the co-evolutionary technology development framework and the “D-N-S” (Design, Negotiation, Sense-making) framework for anticipatory standardizing. At the backdrop of complex and diversified landscape of science and R&D efforts in the technology domain, and the repeated criticism of the weak link between R&D initiatives and standardization, it is argued that the method offered in this work helps to better understand the internal dynamics of the technology development process at the early stage of standardization or pre-standardization, which, in turn, can help mobilize and direct the R&D initiatives. To demonstrate the practical usefulness of the proposed method, this paper conducts a content analysis of the research contributions presented in the COST Action IC0905 “Techno-Economic Regulatory Framework for Radio Spectrum Access for Cognitive Radio/ Software Defined Radio” (COST-TERRA).

Weak-Link Analysis of Motor-Operated Butterfly Valve

2002 ◽  
Author(s):  
Donghae Kim
Keyword(s):  
Structural Integrity ◽  
Weak Link ◽  
Link Analysis ◽  
Seismic Load ◽  
Seismic Loads ◽  
Static Force ◽  
Bending Stress ◽  
Butterfly Valve ◽  
Load Path ◽  
Valve Assembly

The purpose of this paper is to address the structural integrity of the motor operated butterfly valve assembly by providing the methodology and equations to quantitatively determine the permissible component load in the load path from the operator to the valve. The weak link analysis is to determine the maximum allowable torque on the butterfly valve by equating the stresses caused by the torque and seismic load with the appropriate allowable stress value, and then the unknown torque is solved. Analysis methods are based on classical static force balancing equations and on classical axial, shear, and bending stress equations using the worst possible load combinations including seismic loads resulting from design basis earthquake.

Investigation of Strength and Dynamic Characteristics for the Rolling Mill

2013 ◽  
Vol 706-708 ◽  
pp. 1405-1408
Author(s):  
Xi Ping Guo ◽  
Shuang Zhou
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Rolling Mill ◽  
Maximum Stress ◽  
Weak Link ◽  
Deformation Analysis ◽  
Vibration Model ◽  
Strength And Stiffness ◽  
Stress And Deformation ◽  
Diagram Analysis

Stress and deformation analysis of 950 mill housing was done by means of ANSYS to calculate the maximum stress and deformation. Strength and stiffness of the mill roll were checked to meet requirements. Carries on the modal analysis to the rolling-mill housing, obtains its first 10 steps the natural frequency and the mode of vibration, through the vibration model diagram analysis frame of the weak link,and it is significant for similar mill housing designs.

ac susceptibility and weak-link-free behavior in an epitaxial film ofGdBa2Cu3O7−δ

1992 ◽  
Vol 46 (14) ◽  
pp. 9190-9194 ◽  
Author(s):  
J. W. Li ◽  
R. L. Wang ◽  
H. R. Yi ◽  
H. C. Li ◽  
B. Yin ◽  
...  
Keyword(s):  
Epitaxial Film ◽  
Weak Link ◽  
Ac Susceptibility ◽  
Free Behavior
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