Direct Determination of the Power Threshold Value of Vortex Avalanche in YBa2Cu3O7-x Thin Films Triggered by a Laser Pulse

Author(s):  
Cunhong Wang ◽  
Cong Liu ◽  
Xingyi Zhang ◽  
You-He Zhou
2011 ◽  
Vol 44 (2) ◽  
pp. 409-413 ◽  
Author(s):  
D. Faurie ◽  
P.-O. Renault ◽  
E. Le Bourhis ◽  
T. Chauveau ◽  
O. Castelnau ◽  
...  

The anisotropic elastic response of supported thin films with a {111} fiber texture has been studied using anin-situmicro-tensile tester and X-ray diffractometry. It is shown which specific X-ray diffraction measurement geometries can be used to analyze the elastic strains in thin films without requiring any assumptions regarding elastic interactions between grains. It is evidenced (theoretically and experimentally) that the combination of two specific geometries leads to a simple linear relationship between the measured strains and the geometrical variable sin2ψ, avoiding the transition scale models. The linear fit of the experimental data allows a direct determination of the relationship between the three single-crystal elastic compliances or a direct determination of theS44single-crystal elastic compliance and the combination ofS11+ 2S12if the macroscopic stress is known. This methodology has been applied to a model system,i.e.gold film for which no size effect is expected, deposited on polyimide substrate, and it was found thatS44= 23.2 TPa−1andS11+ 2S12= 1.9 TPa−1, in good accordance with values for large crystals of gold.


1985 ◽  
Vol 55 (5) ◽  
pp. 545-548 ◽  
Author(s):  
G. Perluzzo ◽  
G. Bader ◽  
L. G. Caron ◽  
L. Sanche

Author(s):  
Nataliy Filimonova ◽  
Stanislav Zabara

Based on the EEG analysis, a method for determining the set of time parameters of brain activity maxima in different leads and in different frequency ranges was proposed, which determines the functional connectivity of the brain. To counteract the power difference for different frequencies and people with different background activation, a procedure for normalizing the power of the wavelet spectra was proposed. It has been found that the power of normalized wavelet spectra based on the Kravchuk functions for different frequency ranges and for different people is in the range 0.01... 0.9. To determine the power threshold above which the corresponding maximum power can be considered a brain response to an external or internal stimulus, EEG wavelet spectra were constructed based on Krawtchouk functions for 10 people aged 20–22, right-handed students of Taras Shevchenko National University of Kyiv. The Neuron-Spectrum-4 / EP complex was used for EEG registration (NeuroSoft, Certificate of EUROCAT Institute for Certification and Testing, Quarat Center, Darmstadt, Germany); EEG registration was carried out at a frequency of 500 Hz, 19 electrodes placed on the international 10/20 system were used. The length of the EEG recording is 16000 points, ie 32 s. The SOM-Ward method clustered the obtained power of the wavelet spectra by 171 attributes. Power attributes of the wavelet spectra in 19 standard leads F1, F2, Fz, F3, F4, F7, F8, Cz, C3, C4, T3, T4, T5, T6, Pz, P3, P4, O1 and O2 were used as attributes. for frequencies 0.5Hz, 1Hz, 2Hz, 4Hz, 8Hz, 16Hz, 31Hz, 63Hz and 125Hz. As a result of clustering, the smallest number of clusters was obtained — 3 and the largest number was — 5. Wavelet Spectrum Analysis 10 surveyed found that the maximum value of the average wavelet power for clusters attributable to background activity was 0.012, and the minimum value of the average wavelet power for clusters attributable to brain reaction was 0.033. Thus, a threshold value of the wavelet spectrum power was detected, namely 0.033, above which the corresponding maximum of the power can be considered as a brain response to an external or internal stimulus.


1999 ◽  
Vol 5 (S2) ◽  
pp. 112-113
Author(s):  
Y. Yan ◽  
Z. Xu ◽  
X. Lu ◽  
D. Viehland ◽  
M.M. Al-Jassim ◽  
...  

Ferroelectric thin films have received much attention because of their nonvolatile ferroelectric random access memory (NVFRAM) applications. Recently SrBi2Ta2O9 (SBT), a bismuth-layered ferroelectric compound, has been recognized as a leading candidate for the NVFRAM applications because of its negligible fatigue, low leakage currents and ability to maintain bulk characteristics when fabricated in very thin films. While most work up to date has been focused on its thin film forms for nonvolatile memory applications, its intrinsic properties, basic structure and the effects of defects on the properties are not well understood, mainly due to the lack of sizable single crystals and the details of defects. In this paper we report the first direct determination of a novel planar defect structure in SrBi2Ta2O9, using high-resolution Z-contrast imaging.


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