scholarly journals Microcrack Detection Using Spectral Response Data Alone

2021 ◽  
Vol 11 (8) ◽  
pp. 3655
Author(s):  
Gee-Soo Lee ◽  
Chan-Jung Kim
Keyword(s):  
Spectral Response ◽  
Coherence Function ◽  
Cold Forming ◽  
Response Data ◽  
Highly Sensitive ◽  
Bending Mode ◽  
Out Of Plane ◽  
Rectangular Specimen ◽  
Microcrack Detection ◽  
Impulse Force

Microcracks of depth less than 200 μm in mechanical components are difficult to detect because conventional methods such as X-ray or eddy current measurements are less sensitive to such depths. Nonetheless, an efficient microcrack detection method is required urgently in the mechanical industry because microcracks are produced frequently during cold-forming. The frequency response function (FRF) is known to be highly sensitive even to microcracks, and it can be obtained using both the input data of an impact hammer and the response data of an accelerometer. Under the assumption of an impulse force with a similar spectral impulse pattern, spectral response data alone could be used as a crack indicator because the dynamic characteristics of a microcrack may be dependent solely on these measured data. This study investigates the feasibility of microcrack detection using the response data alone through impact tests with a simple rectangular specimen. A simple rectangular specimen with a 200 μm microcrack at one face was prepared. The experimental modal analysis was conducted for the normal (uncracked) specimen and found-first bending mode about 1090 Hz at the X-Y plane (in-plane). Response accelerations were obtained in both at in-plane locations as well as X-Z plane (out-of-plane), and the crack was detected using the coherence function between a normal and a cracked specimen. A comparison of the crack inspection results obtained using the response data and the FRF data indicated the validity of the proposed method.

Highly sensitive infrared polarized photodetector enabled by out-of-plane PSN architecture composing of p-MoTe2, semimetal-MoTe2 and n-SnSe2

Nano Research ◽  
2021 ◽  
Author(s):  
Yiming Sun ◽  
Jingxian Xiong ◽  
Xuming Wu ◽  
Wei Gao ◽  
Nengjie Huo ◽  
...  
Keyword(s):  
Highly Sensitive ◽  
Out Of Plane

A Strain Distribution Based Classification of Ortho-Planar Springs: An Outlook to Piezoelectric Applications

2016 ◽  
Author(s):  
R. B. van Kempen ◽  
J. L. Herder ◽  
N. Tolou
Keyword(s):  
Strain Distribution ◽  
Low Frequency ◽  
Plane Motion ◽  
Piezoelectric Energy Harvesting ◽  
Piezoelectric Energy ◽  
Planar Shape ◽  
Bending Mode ◽  
Frequency Transducer ◽  
Out Of Plane

Ortho-planar springs are characterized by their planar shape and the dominant out of plane motion. These springs have benefits for integration in piezoelectric energy harvesting transducers, because of their compactness and monolithic planar manufacturing. The operating behavior in the first low frequency bending mode can be optimized by obtaining an appropriate strain distribution. A holistic design approach is proposed that contains both the focus on strain distribution as on the low frequency dynamic operation challenge. Therefore a classification based on the strain distribution has been made, which is derived from the perspective of loading, clamping and geometry of single flexures of ortho-planar springs. A comparison based on the type of strain (bending/torsion ratio), strain inversion,off-axis stiffness and the natural frequency-normalized area factor (NFNA) has been performed. The double clamped folded configuration shows the most potential for future optimal low frequency transducer designs.

Remote Sensing Monitoring Model and Method of Methane Emission in Coal Mine Area

2012 ◽  
Vol 462 ◽  
pp. 631-634 ◽  
Author(s):  
Hui Ci ◽  
Yong Qin ◽  
Hui Yang ◽  
Guo Qiang Li ◽  
Ge Fei Feng
Keyword(s):  
Remote Sensing ◽  
Real Time ◽  
Spectral Response ◽  
Theory Model ◽  
Atmospheric Environment ◽  
Space Distribution ◽  
Shanxi Province ◽  
Monitoring Model ◽  
Time Space ◽  
Highly Sensitive

Currently, there lacks real-time, effective, and highly sensitive means to monitor and control Methane emissions in coalmining region. And the related principles, methods and technology are not complete yet. With regards to this point, the technology of remote sensing to monitor the circumstance in coalmining region is expected to have some advantages which other technology can not match. This paper takes the region of southern of Qinshui basin in Shanxi province as the key research object. Then, the best band is chosen to monitor the methane based on the basic theory of remote sensing, such that the theory model of spectral response of methane can be developed completely. Meanwhile the hyper spectral remote sensing model for monitoring the concentrations of methane in coalmining region is developed also, and is used to analyze the discipline of time-space distribution of the methane in coalmining region preliminary to provide the condition for study the highly sensitive method of monitor atmospheric environment of coalmining region in real time.

scholarly journals Comparison of Theoretical and Laboratory Out-of-Plane Shear Stiffness Values of Cross Laminated Timber Panels

Buildings ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 146 ◽  
Author(s):  
Jan Niederwestberg ◽  
Jianhui Zhou ◽  
Ying-Hei Chui
Keyword(s):  
Shear Modulus ◽  
Cross Section ◽  
Single Layer ◽  
Beam Theory ◽  
Shear Stiffness ◽  
Plane Shear ◽  
Shear Moduli ◽  
Cross Laminated Timber ◽  
Highly Sensitive ◽  
Out Of Plane

The lay-up of cross laminated timber (CLT) leads to significant differences in properties over its cross-section. Particularly the out-of-plane shear behavior of CLT is affected by the changes in shear moduli over the cross-section. Results from laboratory shear tests are used to evaluate the shear stiffness of 3- and 5-layer CLT panels in their major and minor strength direction. The results are compared to calculated shear stiffness values on evaluated single-layer properties as well as commonly used property ratios using the Timoshenko beam theory and the shear analogy method. Differences between the two calculation approaches are pointed out. The shear stiffness is highly sensitive to the ratio of the shear modulus parallel to the grain to the shear modulus perpendicular to the grain. The stiffness values determined from two test measurements are compared with the calculated results. The level of agreement is dependent on the number of layers in CLT and the property axis of the CLT panels.

The effect of intermolecular forces upon the vibrations of molecules in the crystalline state I. The out-of-plane bending of the carbonate ion in aragonite minerals

1963 ◽  
Vol 275 (1362) ◽  
pp. 295-309 ◽  
Keyword(s):  
Intermolecular Forces ◽  
Absolute Intensities ◽  
Carbonate Ion ◽  
Nearest Neighbours ◽  
Bending Mode ◽  
Infra Red ◽  
Out Of Plane ◽  
Plane Bending ◽  
Oxygen Bond ◽  
Dipole Energy

The infra-red absorption of polycrystalline BaCO 3 , SrCO 3 , and CaCO 3 , the latter in both the aragonite and calcite modifications, has been measured in the region 600 to 2000 cm -1 . Absolute intensities were determined for each of the three fundamental bands of the carbonate ion, by the method of extrapolation to infinite dilution of the carbonate in the alkali halide matrix. The band due to the out-of-plane bending mode was examined under high resolution, the samples employed having been enriched to a 50/50 ratio of 12 C/ 13 C. Intermolecular coupling in this band, which is revealed by the isotopic solid solution, has been interpreted as arising primarily from interaction of the dipoles produced during the vibration. The dipole derivatives calculated from this coupling agree fairly well with those estimated from the absolute intensities. Various sources of error are discussed, and in particular, an estimate is made of the dipole-dipole energy summed over the entire lattice, instead of merely for nearest neighbours. The carbon-oxygen bond moment during the vibration has an effective value of from 1.3 to 1.7 debyes.

Rotational transitions within the 21, 31, 41, and 61 states of formaldehyde H212C16O This article is part of a Special Issue on Spectroscopy at the University of New Brunswick in honour of Colan Linton and Ron Lees.

2009 ◽  
Vol 87 (5) ◽  
pp. 425-435 ◽  
Author(s):  
L. Margulès ◽  
A. Perrin ◽  
R. Janečkovà ◽  
S. Bailleux ◽  
C. P. Endres ◽  
...  
Keyword(s):  
Energy Levels ◽  
Ground Vibration ◽  
Chem Phys ◽  
Vibrational States ◽  
Millimetre Wave ◽  
Rotational Spectra ◽  
Wave Measurements ◽  
Bending Mode ◽  
Out Of Plane ◽  
Rotational Transitions

This work, besides its fundamental interest, is motivated by the atmospheric and astrophysical importance of formaldehyde (H2CO). The goal of this study is to complete the already existing list of rotational transitions within the ground vibration state by a list of transitions within the four first excited 21, 31, 41, and 61 vibrational states, to help the detection of this species by microwave or millimetre wave techniques. For this purpose, the rotational spectra of H2CO in the 21, 31, 41, and 61 excited vibrational states have been investigated in Lille and Cologne in the millimetre region at 160–600 GHz and 850–903 GHz, respectively. The results of these millimetre wave measurements were combined with the 21, 31, 41, and 61 infrared energy levels, which were obtained from previous analysis of FTS spectra of the ν4 (out of plane bending mode), ν6 (CH2 rock mode), and ν3 (CH2 bending mode) bands recorded in the 10 µm region (D.C. Reuter, S. Nadler, S.J. Daunt, and J.W.C. Johns. J. Chem. Phys. 91, 646 (1989)) and more recently for the ν2 fundamental band (C=O stretching, located at 1746.009 cm–1) (F. Kwabia Tchana, A. Perrin, and N. Lacome. J. Mol. Spectrosc. 245, 141, (2007)). The energy level calculation of the 21, 31, 41, and 61 interacting states accounts for the various Coriolis-type resonances that perturb the energy levels of the 21, 31, 41, and 61 vibrational states as well as for the anharmonic resonances coupling the 21 and 31 energy levels, and in this way the microwave and infrared data could be reproduced within their associated experimental uncertainty. However, it is clear that the theoretical model used to account for the very large A-type Coriolis resonance linking the 41 and 61 energy levels of H2CO is only effective with poor physical meaning.

A Bulk Micromachined Si-on-Glass Tunneling Accelerometer

2007 ◽  
Author(s):  
Min Miao ◽  
Qifang Hu ◽  
Yilong Hao ◽  
Haifeng Dong ◽  
Haixia Zhang
Keyword(s):  
Closed Loop ◽  
Proof Mass ◽  
Anodic Bonding ◽  
Analysis And Design ◽  
Icp Etching ◽  
Highly Sensitive ◽  
Out Of Plane ◽  
Input Range ◽  
Pyrex 7740 ◽  
Si Wafer

A bulk micromachined tunneling accelerometer on Pyrex 7740 substrate is reported in this paper, which is intended for the applications in highly sensitive inertia measurements, such as those in microgravity environments and self-contained navigation. The tunneling tip is defined by an isotropic wet etching followed by a maskless wet thermal oxidation for the sharpening of the tip. Unlike the process ever reported by other facilities, an ICP etching on the side of the Si wafer with the tip is utilized to partially define the suspension and the proof mass before the anodic bonding of the Si wafer with the glass substrate, and an addition maskless ICP etching is used to release the whole movable structure after the bonding. Fabricated samples have displayed the effectiveness of the process proposed, which is relatively simple and may guarantee the yield of mass production. The theoretical analysis and design of the closed loop architecture of the device are demonstrated. Capable of sensing out-of-plane acceleration, this device has demonstrated a high resolution of 0.015mg/rtHz (@ 1∼100Hz) and a nonlinearity of less than 1% over ±1g input range.

Sweet Potato Periderm Components Inhibit Yellow Nutsedge (Cyperus esculentus) Growth

1994 ◽  
Vol 8 (1) ◽  
pp. 168-171 ◽  
Author(s):  
Howard F. Harrison ◽  
Joseph K. Peterson
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Root Growth ◽  
Sweet Potato ◽  
Dry Weight ◽  
Cyperus Esculentus ◽  
Yellow Nutsedge ◽  
Response Data ◽  
Weight Concentration ◽  
Highly Sensitive

Sequential extraction and chromatographic procedures were used to isolate inhibitors of yellow nutsedge growth from sweet potato periderm tissue. Most of the inhibitory activity was found in a single high pressure liquid chromatography peak that contained 1.2% of the periderm dry weight. Concentration-response data indicated that yellow nutsedge is highly sensitive to this fraction. Several other fractions inhibited yellow nutsedge root growth, but they did not compose a major portion of the inhibitory capacity of the periderm extracts.

scholarly journals Improved Efficiency in Hydrogenated Amorphous Silicon Solar Cells Irradiated by Excimer Laser

2004 ◽  
Vol 836 ◽  
Author(s):  
A. A. Damitha ◽  
T. Adikaari ◽  
S. Ravi ◽  
P. Silva ◽  
Michael J. Kearney ◽  
...  
Keyword(s):  
Solar Cells ◽  
Excimer Laser ◽  
Indium Tin Oxide ◽  
Laser Energy ◽  
Spectral Response ◽  
Device Fabrication ◽  
Maximum Efficiency ◽  
Response Data ◽  
Nanocrystalline Thin Film ◽  
Energy Irradiation

ABSTRACTExcimer laser crystallisation is used to fabricate nanocrystalline thin film silicon Schottky barrier solar cells, in a superstrate configuration with indium tin oxide as the front contact and chromium as the back contact. 150 nm thick intrinsic absorber layers are used for the solar cells, and was crystallised using an excimer laser with different laser energy densities. These layers were characterised using Raman spectroscopy and optical absorption before device fabrication. External quantum efficiencies of the devices were calculated from the spectral response data of the devices. A maximum efficiency of 70 % is observed for low energy irradiation, which is significant for very thin absorber layers. Device operation is discussed with proposed band structures for the devices and supplementary measurements.

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