Applied Mechanics and Materials Vols. 568-570

Abstract: The two-point non-uniformity correction based on Least mean square (LMS) algorithm which was proposed by Suxia Xing need one FPGA processor, one DSP processor and four SRAM chips. This will increase the cost and volume of the whole infrared system. In the LMS algorithm, this paper improves the estimation of the ideal signal, so that it can reduce the influence of blind elements and improve the effect of non-uniformity correction. Besides, this paper realizes the two-point non-uniformity correction based on LMS algorithm with only one FPGA processor and two SRAM chips in the final, this will reduce the volume, weight, cost of the whole infrared system. Comparing with the two-point non-uniformity correction based on one FPGA processor, this paper did not need blackbody with uniform radiation in system. Above all, the method of this paper is useful and practical.

Abstract: The excellent time–frequency resolution of the modified S-transform (MST) makes it an attractive candidate for analysis and detection of harmonic in micro-grid. This paper presents a new approach for micro-grid harmonic detection based on the MST. Firstly, the MST was performed for the harmonic signal, and then the feature vectors were extracted from the resulting time-frequency matrix. Finally, the frequency, amplitude and phase of the harmonic were obtained by analyzing and processing these feature vectors. Simulation results show that the proposed approach can detect the harmonic in micro-grid with high accuracy and strong noise immunity.

Abstract: Based on the power quality disturbance problems of the power system connected with micro grid, The detecting method of transient power quality disturbance is mainly studied, which based on lifting wavelet transform, after the analysis of lifting wavelet construction principle, the transient power quality disturbance detecting method based lifting db4 wavelet is put forward, the results of simulation and comparison analysis prove that the method can detect and locate the transient power quality disturbances quickly and accurately, so that ,an effective and feasible method is provided to the research of transient power quality disturbance problems brought by the connection between micro grid and power system.

Abstract: For the composing and the technical maintenance characteristic of new-type weapon, the BIT information collection technology is developed, and the multi-channel inlayed data acquisition system is established. The implement for equipment technical maintenance can be guided and helped by obtaining equipment technical status information from system, which achieves the science character and pertinence of equipment technical maintenance.

Abstract: The speech quality is one of the most important indexes to evaluate the communication system. The objective evaluation is the last goal that people have been pursuing. The most efficient evaluation methods based on the spectrum distortion measure was analysed. The objective evaluation method based on wavelet spectrum distortion measure was simulated on the Matlab simulation environment. The simulation results show that Matlab was very suit to analyse the speech quality. The objective evaluation rules are found out on Matlab and the objective evaluation method was achieved.

Abstract: GOCE satellite gravity data is often used to compute gravity anomaly and geoid height. In the paper, GOCE gravity data is used to inverse the crustal thickness of Chinese mainland (E70°~130°, N20°~50°) in this paper. In order to test the reliability of the result, the computing result is compared with previous studies. The comparative analysis shows that the inversion result by GOCE gravity data has higher resolution and has good consistence with the previous studies.

Abstract: In this paper, a new zenith tropospheric delay (ZTD) correction model is established by using 4 years of ZTD over Southern California, which not require any meteorological data and only related to the site’s elevation and the day of year. The results show that the stability and precision of the new model are better than Saastamoinen model using ECMWF date, and the precision increases along with increasing site’s elevation. The overall accuracy of the new model is about 3.86cm when used to predict zenith troposhperic delays in 2012 over Southern California area.

Abstract: The water-squirting ultrasonic detector can not only reduce wetted area of specimen, volume of detection equipment, but also gain longitudinal wave, shear wave, and surface wave detection by changing the ultrasonic incident angle. The paper discusses the development of a new kind of water-squirting ultrasonic detector, which is based on the study of water immersion ultrasonic detector. In this detector, a removable water column replaces the fixed water container for maneuverability; a composited column replaces the water-only column for the ultrasonic coupling channel; a special optimized nozzle is used to form the composited column; an ultrasonic absorption intracavity and an air-water composited mixture are used for anti-interference. Finally, the new kind of water-squiring ultrasonic detector may replace the original water immersion detector, and can be applied to more extensive detection field.

Abstract: Interferometric Synthetic Aperture Radar (InSAR) has become a research focus in airborne remote sensing systems. In order to improve the image quality, it is essential to apply accurate motion error compensation. In this paper, a high-precision Ring Laser Gyroscope (RLG) Position and Orientation System (POS) is developed, and it can offer time and space reference information for InSAR to compensate motion errors. The developed RLG POS was applied in airborne InSAR surveying and mapping system successfully. The airborne experiments show that height estimation sensitivity of InSAR compensated by RLG POS had been improved to 0.27m from 3m.

Abstract: This thesis, under the guiding of electromagnetic and ultrasonic theory, tries to do numerical simulation based on the Fluent simulation software. The composite flowmeter (CFM) improves the accuracy of metrology on water flow and equipment itself with self-calibration and inter-calibration function. The aim is to calculate the average velocity of fluid on the cross-section at the electrode and the stability of flow field by researching on the influence of transducer. The result shows when the distance between two transducers is close, influences the flow field near the electrode, but when the product of two transducers distance and pipe diameter is around 4000, the average fluid velocity is close to the pre-selected fluid velocity and without any swirl. After comprehensive thinking on the structure influence of excitation coil, the transducer should been equipped on the same longitudinal section with the electrode.