GPS/Pseudolites technology based on EMD-wavelet in the complex field conditions of mine

AbstractTo increase the number and improve the geometric condition of visual satellites of GPS in complex environment of mine areas, GPS and pseudolite (PLs) positioning technologies will be integrated in this paper. Integration of GPS/Pseudolites(PLs) positioning technology can be applied to increase the number of visible satellites, strengthen the intensity of the geometry condition of the satellites, and provide an effective solution for precision measurement in the mine. However, the un-modeled systematic errors are still the main restrictive factors for high precision baseline solution. The Empirical Mode Decomposition (EMD)-Wavelet model was proposed for analysing non-linear time series. The EMD decomposes the time series to high-frequency and low-frequency part with the standards of the scale selection for the systematic errors elimination which is given in terms of the mean of the accumulated standardized modes, and the tendency of high-frequency part is extracted by Wavelet. Then low-frequency part and the tendency of high-frequency are reconstructed based on EMD theory and the systematic errors mitigation model is demonstrated as well. Thereafter, the scheme of the GPS/PLs baseline solution based on the EMD-Wavelet is suggested. The experiment shows that the proposed scheme dramatically improves the reliability of ambiguity resolution and the precision of baseline vector after systematic error eliminated

Study on the Rheological Properties and Constitutive Model of Shenzhen Mucky Soft Soil

In order to obtain the basic parameters of numerical analysis about the time-space effect of the deformation occurring in Shenzhen deep soft-soil foundation pit, a series of triaxial consolidated-undrained shear rheology tests on the peripheral mucky soft soil of a deep foundation pit support were performed under different confining pressures. The relations between the axial strain of the soil and time, as well as between the pore-water pressure of the soil and time, were achieved, meanwhile on the basis of analyzing the rheological properties of the soil, the relevant rheological models were built. Analysis results were proved that the rheology of Shenzhen mucky soft soil was generally viscous, elastic, and plastic, and had a low yield stress between 90 and 150 kPa. The increase in pore-water pressure made the rheological time effect of the mucky soft soil more remarkable. Thus, the drainage performance in practical engineering should be improved to its maximum possibility extent to decrease the soft-soil rheological deformation. Lastly, a six-component extended Burgers model was employed to fit the test results and the parameters of the model were determined. Findings showed that the extended Burgers model could satisfactorily simulate the various rheological stages of the mucky soft soil. The constitutive model and the determination of its parameters can be served as a foundation for the time-space effect analysis on the deformation of deep soft-soil foundation pits

LED-Induced Fluorescence System for Tea Classification and Quality Assessment

A fluorescence system is developed by using several light emitting diodes (LEDs) with different wavelengths as excitation light sources. The fluorescence detection head consists of multi LED light sources and a multimode fiber for fluorescence collection, where the LEDs and the corresponding filters can be easily chosen to get appropriate excitation wavelengths for different applications. By analyzing fluorescence spectra with the principal component analysis method, the system is utilized in the classification of four types of green tea beverages and two types of black tea beverages. Qualities of the Xihu Longjing tea leaves of different grades, as well as the corresponding liquid tea samples, are studied to further investigate the ability and application of the system in the evaluation of classification/quality of tea and other foods