Entity

Time filter

Source Type


Wan Y.-G.,Institute of Disaster Prevention
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2015

Crustal stress field is fundamental information in studying earthquake dynamics and seismogenic environments. One of methods to determine stress tensors is to fit observed striation. But such data are seldemly measured in geological field investigations. The sense of fault slip (such as thrust fault or normal faulting, left lateral or right lateral strike-slip faulting) is also tightly associated with the stress tensor, which are abundantly obtained from geological field work. So in the case that striation data are too little to constrain the stress tensor, the data of fault slip can be used to attain this aim. This study attempted to combine the two kinds of data (striation data and fault slip data) to determine stress tensors in a certain area. We analyzed the stress tensor representation in the north-east-down coordinate system, which is composed of three principal stress axes. The stress tensor is represented by 4 parameters, 3 of which give stress directions of the stress tensor and the other one gives the stress shape ratio. We also gave the criteria of fitting the striation data and sense of fault slip with the determined stress tensors. By using a grid search strategy, we provided a method to invert the stress tensors by combination of striation and fault slip data. The confidence itervals of the inverted stress tensors under a certain confidence level were determined by the F-test. Assuming the certain stress tensors of thrust, normal and strike-slip stress regimes, we generated 3 sets of data including 7 striations and 80 fault slip “data”, the strike and dip of which were randomly generated, the rake (for striation) and nature (qualitative data) of which were determined by the corresponding stress tensors with a certain level of “noise”. By using the artifical “data”, we inverted the stress tensors by only striation “data” and the hybrid “data” composed of striation “data” and fault slip “data”, respectively. The results show that the principal stress directions determined by the hybrid “data” are closer to the assumed principal stress directions than that determined only by striation “data”, and the uncertainty of the stress parameters are greatly decreased. We applied this method to the striation and fault slip data in the Urumqi area obtained by geological field investigation, and determined the stress tensors. The results show that the compressive stress is nearly in NS direction, the extensional stress is nearly vertical, the stress shape ratio is 0.03. They mean the dominant thrust faults trending nearly EW in this area are caused by the north-south compressive stress and vertical extensional stress. The low stress shape ratio implies that the NS compressive stress, complemented by nearly east-west extrusion of the Borocco and Bogda Mountains, will result in the uplift of the Urumqi area. ©, 2015, Science Press. All right reserved.


Zhao X.,Institute of Disaster Prevention
Journal of Dispersion Science and Technology | Year: 2015

The triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (L64, PEO13PPO30PEO13) in 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) can form lamellar liquid crystalline (Lα). The effect of apolar cyclohexane molecules on the Lα phase was investigated by using polarized optical microscopy (POM) and small-angle x-ray scattering (SAXS). The results of POM and SAXS show that a suitable amount of cyclohexane can contribute to the formation of lamellar liquid crystals, and the ordering of Lα phase is increased. For comparison, the effect of polar water on Lα phase was explored. After adding water, both EO groups and [BF4]– anion can form hydrogen bonds with water molecules, which weakens the electrostatic interactions between L64 and [Bmim][BF4] and therefore the ordering of lamellar structures is destroyed. © 2015, Taylor & Francis Group, LLC.


Liu Q.,Institute of Disaster Prevention
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2013

In order to increase the flexibility of optical signal demultiplex, a polarization-independent two-port multi-wavelength tunable filter was designed based on the electro-optic effect of birefringent lithium niobate (LiNbO3) crystal. On each arm of an asymmetric interferometer, mode-coupled electrode and phase-shifted electrode periodically alternated cascaded were set to realize mode conversion. Z-transform was utilized in analysis of Jones matrix to get the values of needed driving voltages to select wavelengths simultaneously. Narrow-band multi-wavelength with arbitrary distribution was simulated successfully in free spectrum range (FSR). 100% transmittance was obtained at each wavelength. The number of wavlengths had an influence on sidelobe of each wavelength. And sidelobe of 12 dB could be realized when three wavelengths were selected. Interleaver could also be obtained using this method, which had a flat passband and sidelobe of more than 20 dB.


Qi W.-H.,Institute of Engineering Mechanics | Bo J.-S.,Institute of Disaster Prevention | Liu H.-S.,Institute of Engineering Mechanics
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

The current formula can not calculate the fundamental periods of the sites containing soft soil layers accurately. In order to solve the problem, a fundamental period formula for a horizontal layered site, on which the effect of soil layer construction is considered, is deduced based on the vibration theory. According to the rules of natural vibration periods being equal, a single layer site is simplified into a SDOF system by means of the lumped mass method, and the equivalent height coefficient between their heights is deduced. A horizontal multi-layer site can be simplified into a SDOF system based on any one soil layer, and the height of the SDOF system is equal to that of the soil layer multiplied by the equivalent height coefficient. The natural vibration period of the SDOF system is called contributing fundamental period of the soil layer here, and the fundamental period of the site should be equal to the square root of sum square (SRSS) of the contributing fundamental periods of all the soil layers in the site, and its formula is also deduced. The test results show that (a) the proposed formula can reflect the effect of soil layer construction on fundamental periods of sites very well, and (b) by comparing the calculated fundamental periods with the test ones of 5 engineering sites by use of the microtremor method, the proposed formula is of higher accuracy and reliability than the current formula. A conclusion is drawn that the deduced formula can be adopted to estimate the fundamental period of a layered horizontal site.


Liu Q.,Institute of Disaster Prevention
Guangzi Xuebao/Acta Photonica Sinica | Year: 2013

A polarization-independent two-port wave-guided multi-wavelength tunable fiter is designed based on the electro-optic effect of birefringent Lithium Niobate (LiNbO3) crystal. Mode-coupled electrode and phase-shifted electrode periodically alternated cascaded are set on each arm of an asymmetric interferometer to realize mode conversion. Z-domain analysis of Jones matrix is utilized to get the values of driving voltages so that wavelengths can be selected simultaneous. Narrow-band multi-wavelength with arbitrary distribution is simulated successfully in Free Spectrum Range (FSR). 100% transmittance is obtained at each wavelength. Number of wavlengths has an influence on sidelobe of each wavelength. And sidelobe of 12 dB can be realized when three wavelengths are selected. Comb filter can also be obtained using this method, which has a flat passband and sidelobe of more than 15 dB.

Discover hidden collaborations