Applied Mechanics and Materials Vols. 105-107

Abstract: The phase of complex signals is wrapped since it can only be measured modulo-2; unwrapping searches for the 2-combinations that minimize the discontinuity of the unwrapped phase, as only the unwrapped phase can be analyzed and interpreted by further processing. Weighted least squares phase unwrapping algorithm could avoid errors transmission in the whole phase images, but it could not avoid defect and overlay of interference fringes caused by topographic factors. Therefore, a new phase unwrapping and weights choosing method based on local phase frequency estimate of topographic factors was presented. Experiments show it is an efficient phase unwrapping method which well overcome the defect of under-estimate slopes by least squares algorithm, and has higher accuracy and stability than other methods.

Abstract: In this paper, the heat transfer characters of heat pipe radiator for cooling electronic device with high heat flux were investigated by visualization method. The surface temperature of heat pipe radiator was measured at different heat flux and constant fan speed of 0.7m/s, and the results show that the surface temperature of electronic apparatus is below 75°C for the heat flux 8W/cm2 at constant fan speed of 0.7m/s; The error in measured value using thermocouple and technique of infrared thermography was analyzed based on the principles of temperature measurement of infrared thermal imager.

Abstract: It is difficult to measure torque of high speed rotating machinery, a new mechanical structure torque sensor based on three phase asynchronous is designed, and combined with frequency conversion, a new frequency conversion Torque Measurement system is constucted. The sensor shaft and rotor are separated by bearing, for the accuracy of torque measurement, controlling frequency converter to make the speed difference of sensor shaft and rotor constant. This measurement system based on Filed Programmable Gate Array in signal processing, SCM in data processing and frequency converter controlling, and realize non-contract torque measurement. According to the results of the hardware test, indicated this measurement system is realizable. The good accuracy of measurement system is verified accord to the test, the fiducial error is .

Abstract: Using large-scale true-color images of Zundao Town of Mianzhu quake-hit areas gained form low-altitude remote sensing platforms, the author processed those images based on the 3S and image processing technology, then to presents a new object-oriented scheme of damaged building information extraction in the 5.12 Earthquake from the high-resolution low-altitude remote sensing in Zundao Town of Mianzhu. The scheme has two steps. The first step is that the whole imagery was segmented into image objects which do not intersect mutually. The second step is that to extract damaged buildings and undamaged ones with the features used to classify, like spectral, texture, shape and context. The experimental results indicate that the fast image processing method of UAV and the new object-oriented information extraction technique have high accuracy compared to the traditional classification methods and have a great application potential.

Abstract: A thin sensor based on surface acoustic wave resonator (SAWR) in ZnO/SiO₂/Si structure for wireless contact stress measurement in thin gap is numerically analyzed. Firstly, the scheme of the SAWR stress sensor and surface effective permittivity for analyzing surface acoustic wave (SAW) in ZnO/SiO₂/Si structure are introduced. Then, the phase velocity and electromechanical coupling coefficient of ZnO(1µm)/SiO₂(1.4µm)/Si structure for the fundamental and first Rayleigh mode are obtained. For both Rayleigh modes, the temperature coefficient of frequency (TCF) for the structure at different frequency is calculated. Good temperature stability for the structure is achieved at frequency 1GHz for the first Rayleigh mode with averaged TCF about 0.04ppm/°C and stress sensitivity about 22ppm/MPa.

Abstract: In this paper, the mathematical model with errors for parallel double-joint coordinate measuring machine (CMM) was proposed. The main factor of the impact of circular grating measurement error--radial install eccentric error--was analyzed. The error was measured and the data obtained from measurement was used to curve fitting and form the error compensation formula. Experiments show that the method of error compensation has good usability and accuracy.

Abstract: This paper presents a new wall thickness and ovality measuring method engineered for reliable field use. This paper describes the electromagnetic ultrasonic technique in coiled tubing detection. This paper describes requirements for Coiled Tubing specifications, which measuring different parameters, some of which include diameter, ovality, and wall thickness. This method not only thickness measurements but also ovality measuring will be made. This article discusses the electromagnetic ultrasonic thickness measurement of the system components, and experimental tests have shown. Ovality measurement sensor layout is designed. This paper discusses the development of this new methods, this system is suitable for non-contact, real-time, on-line high-speed data measurements.

Abstract: This paper proposed a new method of cutting attack resistant for color image. The RGB image based on three-color theory was transformed and mapped into the real/complex space, which was composed of intensity-number space and color-number space. The watermark information was embedded into the principle component data of intensity-number space, which was extracted by SVD method. And the color image was attacked by 5 types cutting, the extracted watermarking information image had high value of peak signal-to-noise ratio (PSNR), moreover, it also had the similarity value between the original watermark and the extracted watermark. The experiment results demonstrated its’ robustness, effectiveness and rationality.

Abstract: Monitoring ground subsidence of roadbed in permafrost region is very important for stability evaluation and safety management. To test its applicability to deformation monitoring for railway subgrade settlement in plateau permafrost region, satellite differential interferometric synthetic aperture radar technology (D-InSAR) has been applied to detect subgrade deformation in one test site along the Qinghai-Tibet railway with gathered interferometric SAR images. The preliminary experimental results showed that satellite D-InSAR technology can effectively acquire long-time deformation sequence through analyzing the ground scatterers with relative stable phase and are in accordance with the results obtained by conventional in-situ ground leveling. Along the Qinghai-Tibet railway in permafrost regions, it is found that settlement is the main behavior of subgrade deformation and the deformation amount of railway bridge is less than the sliced or the crushed rock embankment. It has very important engineering significance for state key infrastructure long-term monitoring system in plateau permafrost region.

Abstract: This paper introduces a test system for resonator gyros for education. Two major purposes are to study the phenonmena of resonator gyros and to apply the systems engineering process for development. Resonator gyros have rich sources for engineering education: the Coriolis effect, resonating structures, vibrating mechanism, control algorithm, navigation, and so on. For the reasons, we have designed a resonator gyro system. We also have applied the systems engineering process for design: operational and system requirements are developed and those requirements derive architectural designs. A simulation program is coded by the LabVIEW to study the behaviors of resonator gyros.