Effect of the Weak Links on the Surface Resistance of YBa2Cu3Ox Bulk Material

1992 ◽  
Vol 275 ◽  
Author(s):  
J. Wosik ◽  
L. M. Xie ◽  
J. Halbritter ◽  
R. Chau ◽  
A. Samaan ◽  
...  
Keyword(s):  
Surface Resistance ◽  
Weak Link ◽  
Bulk Material ◽  
Weak Links ◽  
Wave Surface ◽  
Critical Fields ◽  
High Quality ◽  
Dc Magnetic Field ◽  
Replacement Method ◽  
Field Temperature

ABSTRACTDc magnetic field, temperature, and magnetic history dependencies of the millimeter-wave surface resistance have been measured in high quality grain-aligned and in polycrystalline YBa2Cu3Ox bulk material. The measurements were carried at 75 GHz using the endplate of the cavity replacement method. The data is interpreted in terms of the presence of intra- and inter-grain types of weak links. The values of characteristic critical fields of the bulk and the weak link junctions are determined and discussed.

Measurements of surface resistance of grain-aligned bulk material as a function of DC magnetic field; weak link study

1993 ◽  
Vol 3 (1) ◽  
pp. 1432-1434 ◽  
Author(s):  
J. Wosik ◽  
L.M. Xie ◽  
J. Halbritter ◽  
R. Chau ◽  
A. Samaan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Surface Resistance ◽  
Weak Link ◽  
Bulk Material ◽  
Dc Magnetic Field

Evidence for Weak Link Effects in Epitaxial Thin Films of YBCO on LaAlO3

1992 ◽  
Vol 275 ◽  
Author(s):  
J. Bohandy ◽  
B. F. Kim ◽  
K. Moorjani ◽  
F. J. Adrian
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Weak Link ◽  
Weak Links ◽  
Superconducting Thin Films ◽  
Epitaxial Thin Films ◽  
High Quality ◽  
Microwave Loss

ABSTRACTEvidence of weak link effects in epitaxial thin films of YBa2Cu3O7-yon LaAlO3 is obtained from magnetically modulated resistance (MMR) measurements. This result suggests that weak links could provide a mechanism for the residual microwave loss in high quality superconducting thin films which contain predominantly low angle grain boundaries.

scholarly journals Coherent suppression of backscattering in optical microresonators

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Andreas Ø. Svela ◽  
Jonathan M. Silver ◽  
Leonardo Del Bino ◽  
Shuangyou Zhang ◽  
Michael T. M. Woodley ◽  
...  
Keyword(s):  
Quality Factor ◽  
Bulk Material ◽  
Near Field ◽  
High Quality Factor ◽  
Dual Frequency ◽  
High Quality ◽  
Frequency Combs ◽  
Optical Microresonators ◽  
Whispering Gallery ◽  
The Stability

AbstractAs light propagates along a waveguide, a fraction of the field can be reflected by Rayleigh scatterers. In high-quality-factor whispering-gallery-mode microresonators, this intrinsic backscattering is primarily caused by either surface or bulk material imperfections. For several types of microresonator-based experiments and applications, minimal backscattering in the cavity is of critical importance, and thus, the ability to suppress backscattering is essential. We demonstrate that the introduction of an additional scatterer into the near field of a high-quality-factor microresonator can coherently suppress the amount of backscattering in the microresonator by more than 30 dB. The method relies on controlling the scatterer position such that the intrinsic and scatterer-induced backpropagating fields destructively interfere. This technique is useful in microresonator applications where backscattering is currently limiting the performance of devices, such as ring-laser gyroscopes and dual frequency combs, which both suffer from injection locking. Moreover, these findings are of interest for integrated photonic circuits in which back reflections could negatively impact the stability of laser sources or other components.

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.

Novel Dielectric Stack Actuators for Dynamic Applications

2012 ◽  
Author(s):  
Sven Herold ◽  
William Kaal ◽  
Tobias Melz
Keyword(s):  
Simulation Model ◽  
Surface Resistance ◽  
Design Concept ◽  
Metal Electrodes ◽  
High Quality ◽  
Complex Material ◽  
Simulation Results ◽  
Actuator Design ◽  
Load Conditions

In order to realize dielectric elastomer stack actuators suitable for dynamic applications a new actuator design with rigid, perforated electrodes is developed. The low surface resistance of the metal electrodes predestines this concept for dynamic applications where higher currents are present. Detailed numerical analyses are performed to show the potential of this approach, to study the complex material deformation and to optimize the aperture geometry. A multilayer stack actuator is then manufactured and characterized experimentally under various load conditions to gain suitable parameters for a parametrized model. It is subsequently used to attenuate vibrations of a truss structure. By careful adjusting the parameters it functions both as passive absober and as actuator. A comparison of experimental and simulation results proves the high quality of the simulation model. The work shows the great potential of the new design concept for future applications especially in the field of smart structures.

VOLTAGE-CURRENT CHARACTERISTICS AND MAGNETORESISTANCE OF BiPbSrCaCuO SILVER CLAMP THICK FILM

1992 ◽  
Vol 06 (26) ◽  
pp. 1639-1647 ◽  
Author(s):  
HAN GUCHANG ◽  
WANG YUGUI ◽  
HAN HANMIN ◽  
WANG SHUNXI
Keyword(s):  
Thick Film ◽  
Weak Link ◽  
Weak Links ◽  
Flux Flow ◽  
Type Ii Superconductors ◽  
Flux Lines ◽  
Flux Trapping ◽  
Physical Deposition ◽  
History Effect ◽  
Current Characteristics

Bi(2223) silver clamp thick film with Jc=1.5×104A/cm2 at 77 K and 0 T was fabricated by a physical deposition method. Voltage-current characteristics and magnetoresistance were investigated in detail at low magnetic fields. It can be concluded that the transport Jc limitation of the present samples was still dominated by weak links although their connectivity has been greatly improved in comparison with bulk materials. The weak links may exert an effective pinning on flux lines. When the transport current exceeds the critical current of weak links their resistances change, just as does the flux flow resistance of traditional type-II superconductors. A history effect of the magnetoresistivity below a certain field (about 1.0 kG) was found at various constant measuring currents and can be ascribed to the Jc (H) characteristics and flux trapping both in the weak link network and the grains.

scholarly journals Copper Oxide Nanomaterials Prepared by Solution Methods, Some Properties, and Potential Applications: A Brief Review

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Thi Ha Tran ◽  
Viet Tuyen Nguyen
Keyword(s):  
Large Scale ◽  
Cupric Oxide ◽  
Bulk Material ◽  
Precursor Solution ◽  
High Quality ◽  
Chemical Methods ◽  
Narrow Bandgap ◽  
Solution Methods ◽  
Potential Applications ◽  
Near Future

Cupric oxide (CuO), having a narrow bandgap of 1.2 eV and a variety of chemophysical properties, is recently attractive in many fields such as energy conversion, optoelectronic devices, and catalyst. Compared with bulk material, the advanced properties of CuO nanostructures have been demonstrated; however, the fact that these materials cannot yet be produced in large scale is an obstacle to realize the potential applications of this material. In this respect, chemical methods seem to be efficient synthesis processes which yield not only large quantities but also high quality and advanced material properties. In this paper, the effect of some general factors on the morphology and properties of CuO nanomaterials prepared by solution methods will be overviewed. In terms of advanced nanostructure synthesis, microwave method in which copper hydroxide nanostructures are produced in the precursor solution and sequentially transformed by microwave into CuO may be considered as a promising method to explore in the near future. This method produces not only large quantities of nanoproducts in a short reaction time of several minutes, but also high quality materials with advanced properties. A brief review on some unique properties and applications of CuO nanostructures will be also presented.

Research on Machine Tool Components Contribution Calculation and the Weak Link Identification of the Whole Machine

2011 ◽  
Vol 52-54 ◽  
pp. 1496-1502
Author(s):  
Hong Lin Zhao ◽  
Qing Fu Wang ◽  
Wei Hua Li ◽  
Guang Peng Zhang ◽  
Zhi Heng Wu ◽  
...  
Keyword(s):  
Weak Link ◽  
General Structure ◽  
Weak Links ◽  
Work Piece ◽  
Space Vector ◽  
Finite Element Software ◽  
Weakest Link ◽  
Vertical Milling ◽  
Vertical Milling Machine ◽  
Key Nodes

After modeling and calculating of whole machine, the static and dynamic characteristics are obtained, since it is difficult not only to judge out machine components’ influence on machining precision intuitively , but also to identify the weak link of the whole machine. Therefore, through extracting key nodes coordinates of machine components and deformation information of finite element software calculated, we brought forward a space vector transfer algorithm, calculated the contribution of components for tools and work piece system and expressed impact of machine components on tool and work piece system by histogram. By this means ,we can judge out the whole machine’s weak links intuitively. Take XK713B Vertical Milling Machine as the case research object, extract key nodes and their deformation information of general structure such as lathe bed , column, headstock, sliding table, workbench etc. By using space vector transfer algorithm, the result shows that the largest contribution to tool system and workbench system is column, which is the weakest link in the whole machine and its vibration type is swing. According to this, further optimize design of column can be proceed.

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