Applied Mechanics and Materials Vols. 333-335

Abstract: Rapid determination of soil moisture in the arid area has important ecological significance and practical value. This study carried out a series of measurements in the alpine meadow of Urumqi Southern Mountain on April 28^th, 2011 right after the snow melt. Ground-penetrating radar (GPR), time domain reflectometry (TDR) were used simultaneously for measuring the soil moisture of a 50 × 50 m² plot, and a vertical soil profile was dug for validation analysis. The results show that: (1) a clear and continuous reflective layer in the experimental plot can be found from the GPR radar data and have a depth range from 0.362 to 0.656 m, while the GPR calculated average soil moisture above this layer is approximate 0.191 ~ 0.341; (2) TDR derived soil moistures of surface 10 cm and 20 cm depth show a consistent distribution with GPR measurements, and the former is slightly higher than the latter is likely to be due to the snow melt water accumulated more in the surface layer and not transferred immediately to the deep; (3) the vertical soil profile displays a actual compacted layer which is just at same position with the corresponding GRP measured reflective layer, and the TDR measured average soil moisture above this layer is only 0.001 less than the GPR derived data. The results give fully demonstrates to the accuracy of GPR reflected wave model to measure soil reflector and average moisture, which provides a scientific and effective technique for field-scale soil moisture and structure studies.

Abstract: SonTek’s Riversurveyor Catamaran (the RiverCAT) is a fully integrated river discharge measurement system. In this paper, the RiverCAT is applied to measure the topography under water in a middle industry water supply reservoir. The whole measurement process is introduced. Area of each cross-section is calculated with complex trapezoidal quadratic formula, and the capacity of the reservoir is computed with complex prismaid quadratic formula. The relationship between capacity and water level is researched by regression analysis method.

Abstract: Concerning the critical issue that how to measure the gain of AC open-loop of operational amplifier accurately, in the field of electronic measuring. The measure system design of the AC open-loop gain of amplifier is designed in the paper based on labVIEW. The system consists of two parts of hardware and software. The hardware is composed by the multifunctional signal source, the low noise preamplifier, the awaiting measured amplifier, the data acquisition card and the computer; the software is composed by the human-computer interface program, measurement program and data post-processing. Using the virtual instrument cross-correlation detection technology, it can measure the gain of amplifier AC open-loop accurately, with the function of acquisition, measurement, real-time display and playback, constituting a programming flexibility, concise and efficient, accurate measurement, higher resolution, steady performance personalized automatic measurement system.

Abstract: The acoustic transducer is a nonlinear system, which will cause a time delay to signals. The system group and phase delay have a large influence on the results in the transmit-time measurement. In order to solve the problem, this paper proposes to use the signal phase difference to eliminate the phase delay, and precisely determine the group delay by the method of experiment. At first, this paper theoretically proves that the group delay of the acoustic measurement system is constant, and the phase delay changes over signal frequency, then it analyzes the influence of group and phase delay on the measuring results and meanwhile puts forward a method to use the multi-frequency signal phase difference to eliminate group delay .Finally, it achieves the group delay through experiments, and there is a good consistency between the experimental results and theoretical analysis.

Abstract: Laser-induced breakdown spectroscopy (LIBS) is excellent for its potential of online compositional analysis. Large signal fluctuation is the major obstacle of LIBS for quantitative analysis application. A kalman filtering method is proposed to estimate the elemental concentration and smooth the quantitative results. The system state model and the measurement model are deduced. The relation matrix between the measured values and system state is estimated based on calibration curve built on some standard samples, and the measurement noise matrix is estimated by the variance of multiple measurements of the spectral intensity. In order to make Kalman filter follow the changes of elemental concentration, the initial value of the covariance matrix of estimation error is reset as a certain rule. The experimental results show that the Kalman filtering method can greatly reduce the fluctuation of quantitative results and improve the measurement accuracy.

Abstract: Target parameters of the K&C test-rig is introduced in this paper. Establish McPherson independent suspension and K&C test-rig multi-body dynamics model .The measurement data of angle sensors is obtained in the wheel travel simulation. Accuracy analysis of target parameters when there are machining errors, installation errors and calibration errors in the measuring system. Accuracy analysis of target parameters when using the different measurement precision angle sensor. Comprehensively consideration of the measuring system all error factors, the accuracy is analyzed. The coordinate error of the installation point between measuring plate and the hub has greater effect on the toe and camber calculation.

Abstract: This paper presents a method improving accuracy for evaluating S-parameters (Scattering-parameters) of MCP (Microwave Coplanar Probe). This method may be named one-port two-tier Multi-TRL (Thru-Reflect-Line) calibration method. It measures two-port devices only at one port of VNA (Vector Network Analyzer). It decreases the random errors caused of cable movements and connecting times. This method is implemented with coaxial OSL (Open-Short-Load) and on-wafer TRL calibration kit. It directly calculates and removes the residual errors caused of coaxial OSL calibration kit imperfection. It significantly reduced system errors by using on-wafer TRL calibration kit. To verify the effectiveness of the proposed method, the measured S-parameters up to 50GHz of MCP configured with GSG-100 are given and discussed.

Abstract: In order to accurately measure and trace micro-force, a micro-force calibration device is designed. According to the principle of electrostatic force reproduction, a coaxial cylindrical variable area capacitor is designed. Through the balance between the standard weight and micro-force generated by micro displacement of the two electrodes, the micro-force be measured for traceability. Electromagnetic finite element method analysis results show that the improved capacitor has little effect on micro-force and applicable to the device. The calibration principle and device to the micro-force standards establishment, traceability and transmission is of great significance.

Abstract: This paper introduces measurement principle, structure and technical indicators of the fullbore turbine flowmeter, presents application examples and measurement results in Daqing oilfield, analyzes and discusses the result chart of measurement, and puts forward relevant insights on the flowmeter.

Abstract: In this paper, a high accuracy and efficiency pose estimation algorithm is proposed for space cooperative targets in RVD based on binocular visual measurement. At first, the scheme of visual measurement toward RVD is presented and the environment conditions and performance requirement are analysed and discussed. Then the relationship of pose estimation with detection and tracking is studied to give an implementing strategy of pose estimation with high accuracy and efficiency. Moreover, the key point is focused on the pose estimation of cooperative targets, in which a stereo vision mapping relation between three dimensionl coordinates of spacial feature points of cooperative targets and their corresponding image coordinates is established, then the least square method is employed to estimate the three-dimensional coordinates of feature points so as to calculate the relative position and attitude between tracking spacecraft and target spacecraft with high precision, finally a series of experimental resluts indicate that the proposed pose estimation algorithm under binocular visual measurement demonstrates well performance in the estimation accuracy, anti-noise and real-time thus can achieve the application requriements of RVD under binocular visual measurement.