Applied Mechanics and Materials Vols. 548-549

Abstract: In order to find a new measurement method for continuous blood pressure (BP), pulse image sensor, pressure sensor and data acquisition card MP425 were used to build the BP simulation platform of multi-information synchronous acquisition, including dynamic pulse images, pressure on the wrist (POW) and BP signals. Multi-point pulse wave (PW) amplitudes of film grid on the pulse image sensor were extracted from the dynamic pulse images by grid area method. Diastolic BP (DBP) and systolic BP (SBP) were estimated by multi-linear regression analysis. The results show that the maximum error of SBP (mmHg) and DBP (mmHg) satisfy the AAMI requirements (mmHg).

Abstract: Studying the bond stress-slip relationship between concrete and corroded steel bar by cutting the steel bars into two separate parts and attaching electric strain gauges in the slots is no longer suitable. To overcome the disadvantages of electric strain gauges in the measuring the stress of corroded steel bars, this paper introduced a new kind of FBG sensor measuring steel stress. By calibration tests, the proportion coefficient between variation of wavelength and steel strain was confirmed as 0.0012. The bond behavior between concrete and steel bar was also investigated by performing pullout tests on beam end specimens.

Abstract: In order to make best use of the neutron flux, a polarized neutron reflectometry with vertical sample geometry is simulated by Vitess package based on Monte Carlo method. The results prove that the neutron flux gain up to a factor reaches 4.3 and the vertical neutron angle divergence is proved, when the optimal tilting angle of the vertically focusing geranium monochromator is 1.3°. At last the optimal separations of horizontal blades of slit packages are optimized. The parameters can be an instruction for polarized neutron reflectometry construction or project analysis in the future.

Abstract: The development of shear-slip cracks and motion trend of fracture water were presented for discussing the shear-slip behavior and analyzing the stability of fractured rock slope under hydraulic action. Seepage behavior of epigenetic cracks and the positions of slip or collapse were also investigated by monitoring pore water pressure using DEM. The analysis method of discrete element simulation for fractured rock slope was proposed. The results of numerical simulation indicated that interpenetrating fractures are more likely to be slip planes.

Abstract: Industrial wastewater control is an important issue for protection of the environment. Liquid characterization using radio frequency signal is an interesting approach for selective detection of heavy metal contaminants in industrial wastewater. A simple sensor based on open-ended coaxial structure filled with the liquid under test is proposed. Liquid samples for the experiments are copper, zinc and nickel solutions with various concentrations of 1, 10, 100 and 1000 mg/liter each. From the measurement results using a vector network analyzer (VNA) in combination with the proposed sensor, the concentration of a specific contaminant can be determined by the magnitude of the measured reflection coefficient in a frequency range lower than 2 GHz. Applying a capacitive model of the sensor, complex permittivity of the liquid under test can be calculated from the measured reflection coefficient. Obvious relationship between the imaginary part of complex permittivity and the concentration of contaminant in a frequency range lower than 2 GHz was observed. The type of contaminants in the liquid samples can be identified by the position of the resonant peaks when the magnitude of reflection coefficient is plotted in the spectrum. The frequency range for contaminant’s identification lies between 2 and 3 GHz.

Abstract: To avoid an unnecessary catastrophic accident due to a failure of a railway track, it is important to have a reliable condition monitoring system for the railway track. The integrity of the railway track can be assessed by monitoring the displacement field of the track, which can then be used to determine the strain and stress field. By knowing the stress history of the track and the S–N curves of the track material, the remaining life of the railway track can be predicted. In the present work, a simple system to monitor and record the displacement field of the railway track has been developed by using Digital Image Correlation (DIC) technique. The set–up to monitor the displacement field of the railway track was developed using a high speed video camera of Nikon J1 to capture the image of the railway track when the train passing through. The DIC technique was then employed off line to measure the displacement field of the 2D image captured. The results showed that the full field displacement measured by using DIC technique gives a good agreement compared to the finite element results. The full field displacement can be used to calculate the strain-stress field, and later on the remaining life assessment can be conducted based on the results.

Abstract: The camera calibration is the basis of the binocular stereo vision technology. The purpose of the stereo calibration camera is to obtain the camera internal and external parameters and distortion coefficients. However, disturbances such as current are usually accompanied with the static water in the actual operation environment of underwater binocular cameras, which may cause further coefficients distortion. Therefore it is necessary to carry out the binocular calibration experiment in the flow disturbance. The camera distortion is analyzed both in static water condition and flow disturbance state. The analysis results indicate that the calibration methods used in this article is verified and the obtained parameters and distortion coefficients are accurate and reliable.

Abstract: Content-based video hashing was proposed for the purpose of video copy detection. Conventional video copy detection algorithms apply image hashing algorithm to either every frame or key frame which is sensitive to video variation. In our proposed algorithm, key frames including temporal and spatial information are used to video copy detection, Discrete cosine transform (DCT) is done for video key frame and feature vector is extracted by principal component analysis ( PCA ). An average true positive rate of 99.31% and false positive rate of 0.37% demonstrate the robustness and uniqueness of the proposed algorithm. Experiments indicate that it is easy to implement and more efficient than other video copy detection algorithms.

Abstract: This paper presents a new method in damage detection by taking the sound signals of the rolling bearings in different levels. The tested bearing was put on the end of the shaft rotated by permanent magnet synchronous motor. The sound signal produced by this rig was recorded separately for each bearing condition with the same experimental environment. The sound data signals are compared each other. Based on the cross-correlation analysis, the recorded sound signal proved that the signals were recorded with the same environment. The power spectra calculation has shown different harmonic frequencies according to various bearing conditions. The total power of the sound is decreased along with the increasing damage. This is also confirmed by the auto-correlation of each sound signal that shows the appearance of the sounds impulse repetition with a wider period.

Abstract: Tool fault analysis is a common task for process engineers in modern industries to maintain high yields of the final products. Statistical process control is a monitoring method normally adopted by most engineers. Recently, there has been enormous awareness among industrial and manufacturing engineers that intelligent techniques from the data mining and machine learning fields can be applied to discover subtle patterns from the manufacturing process data. In this paper, we present the two data mining techniques, i.e. decision tree induction and sequence mining, to discover frequently occurred patterns of the low performance wafer lots in the semiconductor manufacturing industries. The comparative analysis results of both techniques are presented through experimentation over the standard data set for the purpose of re-experimentation.