Experimental Study on Characteristics of Short Wave Irregularity in Urban Rail Transit

Based on the measured irregularity data of Shanghai rail transit 11# line, firstly from the angle of time domain the amplitude stability and amplitude distribution characteristics of the rail surface short wave irregularity whose wavelengths are in the range of 0.01 ∼ 1 m are analyzed. Secondly from the point of view of frequency domain by using the maximum entropy spectrum method the short wave power spectral density is estimated. Then the power spectral density curves are compared with the short spectrum of Wang Lan and Sato and the different track structure effects on the states of the rail surface irregularities are also analyzed. The research show that the amplitude distribution of track surface short wave irregularity is close to the normal distribution. And the maximum amplitudes of some sections in Jiading Xincheng – Malu and Nanxiang – Taopu saemaul undong exceed 2.0mm. In the section of Liziyuan-Shanghai West Railway Station, the power spectral density curves of track structure with the supporting block, DTIII-2 type fasteners and with the conventional integral track bed are also similar to that of Sato spectrum. And it is obviously superior to that of other track structures in this section.

Research on the periodic regularity of annual runoff in the Lower Yellow River

Research on the periodic characteristics of the runoff evolution in the Lower Yellow River is of great importance for flood control, beach regulation and water resources utilization in the Lower Yellow River. By using wavelets to conduct scale analysis of runoff series, the periodic change rule of runoff series on different scales can be obtained. By using the maximum entropy spectrum to analyze the spectrum of runoff, the main period of runoff sequence can be obtained. In this paper, these two methods are applied to the annual runoff of the Lower Yellow River. The results show that: the annual runoff in the Lower Yellow River has multi-scale change law; the four stations have the same main period; there are differences in periodicity between stations, as the catchment area increases, the quasi-periodic value decreases, and the periodic fluctuation becomes more obvious; after 2018, the annual runoff of the Lower Yellow River will be in the dry season. Furthermore, the study can reveal the change law of runoff sequence in the Lower Yellow River to a certain extent, and provide a theoretical basis for river management.

Frequency trend attribute analysis for stratigraphic division and correlation

Stratigraphic sequence interpretation and correlation are part of basic geologic research, but present frequent problems such as subjective and accurate division and correlation of sequence cycles, and a multiplicity of solutions to high-frequency sequences. We developed a novel method, termed frequency trend attribute analysis (FTAA), to solve these problems and improve the accuracy of division. The method was based on maximum entropy spectrum analysis data, built on theoretical foundations, and tested on geologic models as well as empirical data. We developed examples of how FTAA can improve stratigraphic division and correlation. We extracted frequency trend lines from well logging data (using all or a selected part of a facies-sensitive log such as the natural gamma-ray log) whereby the FTAA outcome reflected the overlay series and cycle structures. The resulting frequency trend lines also indirectly reflected changes to the sedimentary environment and base level, and the precise stratigraphic division and isochronous comparisons were automatically deduced from the frequency trend lines. According to the practical comparison with wells in the field, the frequency trend lines were found to be more accurate than using outcrop data, and the method proved to be effective and convenient in use. The FTAA significantly improved the precision and accuracy of automatic division and correlation of sequence cycles.

Periodic Change of River Runoff Based on EMD-MES

This paper discusses stabilizing treatment of runoff time series by empirical mode decomposition (EMD), and periodic analysis of stabilized runoff time series by maximum entropy spectrum, and presents high-resolution character of maximum entropy spectrum and its application prospect in hydrology. It conducts the analysis and calculation in combination with a real example of annual runoff series at the Lanzhou station in the upper of Yellow River, and study proves that annual runoff has 11.1, 6.25 and 3.1 years significant periods at the Lanzhou station. The conclusion illustrates the feasibility of this method and provides scientific data for water resources planning and managing.

A Dynamic Analysis for the Loose Lashing Wire Grouped Blade

The loose lashing wire grouped blade, all blades of which are linked by a loose lashing wire, is a kind of damped blade. The linear analysis method cannot be used for the dynamic analysis of loose lashing wire grouped blade because of the contact between loose lashing wire and blades. A non-linear dynamic analysis method is advanced and an application of the method to a kind of loose lashing wire grouped blade is shown in this paper. First, the nonlinear transient dynamic analysis and maximum entropy spectrum analysis methods for loose lashing wire grouped blade are studied. Then, an algorithm to calculate the dynamical stress of loose lashing wire grouped blade with transient dynamical analysis method is proposed. The proposed method provides a useful numerical calculating method for the calculation of dynamical frequency and dynamical stress of loose lashing wire grouped blades.