scholarly journals Local vibration modes and nitrogen incorporation in AlGaAs:N layers

2008 ◽  
Vol 5 (6) ◽  
pp. 2345-2348
Author(s):  
E. Gallardo ◽  
S. Lazić ◽  
J. M. Calleja ◽  
J. Miguel-Sánchez ◽  
M. Montes ◽  
...  
Keyword(s):  
Vibration Modes ◽  
Local Vibration ◽  
Nitrogen Incorporation

New Type of Defects Explored by Theory: Silicon Interstitial Clusters in SiC

2008 ◽  
Vol 600-603 ◽  
pp. 413-416
Author(s):  
Adam Gali ◽  
T. Hornos ◽  
Nguyen Tien Son ◽  
Erik Janzén
Keyword(s):  
Ab Initio ◽  
High Temperatures ◽  
Vibration Modes ◽  
Local Vibration ◽  
Ionization Energies ◽  
New Type ◽  
Carbon Interstitial ◽  
Small Clusters

We have studied the small clusters of silicon and carbon interstitials by ab initio supercell calculations in 4H-SiC. We found that silicon interstitials can form stable and electrically active complexes with each other or with a carbon interstitial. Local vibration modes and ionization energies were also calculated in order to help the identification of the defects. We propose that silicon interstitials can emit from these clusters at relatively high temperatures, which may play an important role in the formation of the DI center.

Silicon-Hydrogen Bonds in Boron and Phosphorous Doped Polycrystalline Silicon Thin Films

2004 ◽  
Vol 808 ◽  
Author(s):  
R. Saleh ◽  
N. H. Nickel
Keyword(s):  
Binding Energy ◽  
Polycrystalline Silicon ◽  
Binding Energies ◽  
Vibration Modes ◽  
Laser Crystallization ◽  
Hydrogen Binding ◽  
Local Vibration ◽  
Silicon Thin Films ◽  
The One ◽  
Hydrogen Effusion

ABSTRACTHydrogen bonding in laser crystallized boron and phosphorous doped polycrystalline silicon is investigated using Raman spectroscopy and hydrogen effusion measurements. During laser crystallization the intensity of the local vibration modes near 2000 and 2100 cm−1 decreases. The intensity of vibration mode at 2000 cm−1 decreases faster than the one at 2100 cm−1. From H effusion measurements, the hydrogen density-of-states (H DOS) distribution is derived. For undoped amorphous silicon the H DOS exhibits two prominent peaks at hydrogen binding energies of E– μH = –1.1 and –1.5 eV. In B doped a-Si:H the peak at –1.1 eV is less pronounced while in P doped a-Si:H the H binding energy increases by about 0.1 eV. In all samples laser crystallization causes an increase of the H binding energy by about 0.2 – 0.3 eV. However, the peaks in the H DOS observed in B-doped samples are preserved during laser crystallization.

scholarly journals Toward identifying crack-length-related resonances in acoustic emission waveforms for structural health monitoring applications

2017 ◽  
Vol 17 (3) ◽  
pp. 577-585 ◽  
Author(s):  
Md Yeasin Bhuiyan ◽  
Jingjing Bao ◽  
Banibrata Poddar ◽  
Victor Giurgiutiu
Keyword(s):  
Finite Element ◽  
Acoustic Emission ◽  
Fatigue Crack ◽  
Structural Health Monitoring ◽  
Crack Growth ◽  
Health Monitoring ◽  
Resonance Phenomenon ◽  
Vibration Modes ◽  
Local Vibration ◽  
Structural Health

In this study, we focus on analyzing the acoustic emission waveforms of the fatigue crack growth despite the conventional statistics-based analysis of acoustic emission. The acoustic emission monitoring technique is a well-known approach in the non-destructive evaluation/structural health monitoring research field. The growth of the fatigue crack causes the acoustic emission in the material that propagates in the structure. The acoustic emission happens not only from the crack growth but also from the interaction of the crack tips during the fatigue loading in the structure. The acoustic emission waveforms are generated from the acoustic emission events; they propagate and create local vibration modes along the crack faces (crack resonance). In-situ fatigue and acoustic emission experiments were conducted to monitor the acoustic emission waveforms from the fatigue cracks. Several test specimens were used in the fatigue experiments, and corresponding acoustic emission waveforms were captured. The acoustic emission waveforms were analyzed and distinguished into three types based on the similar nature in both time and frequency domains. Three-dimensional harmonic finite element analyses were performed to identify the local vibration modes. The local crack resonance phenomenon has been observed from the finite element simulation that could potentially give the geometric information of the crack. The laser Doppler vibrometry experiment was performed to identify the crack resonance phenomenon, and the experimental results were used to verify the simulated results.

Host Isotope Effect on the Local Vibration Modes of VH2and VOH2Defects in Isotopically Enriched28Si,29Si and30Si Single Crystals

2005 ◽  
Vol 44 (10) ◽  
pp. 7309-7313 ◽  
Author(s):  
Takeru Ohya ◽  
Kohei M. Itoh ◽  
Rui N. Pereira ◽  
Brian Bech Nielsen
Keyword(s):  
Single Crystals ◽  
Isotope Effect ◽  
Vibration Modes ◽  
Local Vibration

The local vibration modes due to impact on the edge of a viaduct

2004 ◽  
Vol 65 (11) ◽  
pp. 1077-1093 ◽  
Author(s):  
Y.Y. Lee ◽  
K.W. Ngai ◽  
C.F. Ng
Keyword(s):  
Vibration Modes ◽  
Local Vibration

scholarly journals The effect of Local Vibration Modes on the Flutter

2011 ◽  
Vol 39 (10) ◽  
pp. 919-926
Author(s):  
Young-Sug Shin ◽  
Heon-Ju Kim ◽  
Seong-Tae Kim ◽  
Jae-Young Kim ◽  
Chul-Ho Hwang
Keyword(s):  
Vibration Modes ◽  
Local Vibration

scholarly journals Probing Local Vibration Modes at Single Planar Defects by Vibrational Spectroscopy

2020 ◽  
Vol 26 (S2) ◽  
pp. 952-953
Author(s):  
Xingxu Yan ◽  
Chengyan Liu ◽  
Chaitanya Gadre ◽  
Lei Gu ◽  
Toshihiro Aoki ◽  
...  
Keyword(s):  
Vibrational Spectroscopy ◽  
Vibration Modes ◽  
Local Vibration ◽  
Planar Defects

scholarly journals DYNAMIC CHARACTERIZATION OF BALL BEARING IN TURBINE PROPELLER USING BUMP TEST METHOD

SINERGI ◽  
2021 ◽  
Vol 25 (2) ◽  
pp. 135
Author(s):  
Monika Audiya Pratiwi ◽  
Muhammad Ikhsan ◽  
Rio Duzan Octavianto ◽  
Abdul Hamid ◽  
Subekti Subekti
Keyword(s):  
Wind Turbines ◽  
Ball Bearing ◽  
Test Method ◽  
Vibration Modes ◽  
Dynamic Characterization ◽  
Local Vibration ◽  
Maintenance System ◽  
Rotating Equipment ◽  
Equipment System

Bearing is an essential component in a mechanical rotating equipment system. It is no less important than lubrication to prevent wear is very important to consider in the mechanical maintenance system of rotating equipment. Bearing wear is one of the problems in wind turbines that will increase maintenance costs, shorten the wind turbines' lifespan, and cause the component or overall damage to the wind turbine. The latest technology has provided instruments for analyzing the damage of elements in a bearing according to the caused vibrations. Therefore, this study was performed on Ball Bearing Turbine Propeller to identify the dynamic characteristics of Ball Bearing with and without lubrication. The test was carried out using the Bump Test method applied in three measured parts: X, Y, and Z axes. The measuring instrument which was used was Fast Fourier Transform (FFT) Analyzer (Ono Sokki) and the data were analyzed using MATLAB. It was identified that the application of oil could reduce the amplitude and decrease the frequency. Personal frequency appearing more than once indicates the existence of global vibration modes. The frequency which only appears once in the measurement spot indicates local vibration modes. The highest frequency both after and before the application of oil was found in the Y-axis.

Wind-Induced Response Analysis of Steel Tower Structure

2012 ◽  
Vol 238 ◽  
pp. 585-588 ◽  
Author(s):  
Chun Feng Wan ◽  
Jiang Wang ◽  
Hong Zhu ◽  
Lei Huang ◽  
Hao Wang ◽  
...  
Keyword(s):  
Wind Speed ◽  
Structural Response ◽  
Time History ◽  
Induced Response ◽  
Response Analysis ◽  
Vibration Modes ◽  
Local Vibration ◽  
Section Area ◽  
History Analysis ◽  
Tower Structure

In this paper, autoregressive (AR) method is firstly introduced to simulate wind speed time series. The agreement of the simulated wind speed spectrum to the target spectrum is verified. A 42m-high steel tower subjected to wind load is analyzed using ANSYS. Through modal analysis, it can be found that the first several modes of the structure are all translational vibration modes. Torsional vibration modes and local vibration modes appear from the 3th order mode. Meanwhile, time history analysis is applied to analyze the structural response. Results show that, under wind loads, the steel tower has large stresses in the chords which have abrupt section area change.

Sign in / Sign up

Export Citation Format

Share Document