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A force transfer mechanism for triggering landslides during rainfall infiltration

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Journal of Mountain Science 2018年第11期15卷 2480-2491页

作者： LIU Gang TONG Fu-guo zhao yi-tong tian Bin College of Hydraulic & Environment Engineering China Three Gorges University

Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely ***-induced landslides are widely recognized to be caused by increases in soil weight, seepage force and pore water pressure or decreases in soil mechanical properties. However, even when all these factors are considered, some landslides still cannot be explained well. The increased pore water pressure in a slope reduces the effective stress of the soil and may trigger slope failure. Similarly, the pore gas pressure in a slope also reduces the effective stress of the soil but has been neglected in previous studies. As the viscosity of air is nearly negligible when compared with that of water, the pore gas pressure spreads faster, and its influence is wider, which is harmful for the stability of the slope. In this paper, the effects of pore gas pressure are considered in a shallow slope stability analysis, and a self-designed experiment is conducted to validate the force transfer *** simulation results show that the pore gas pressure in the slope increases sharply at different locations under heavy rainfall conditions and that the pore gas pressure causes a rapid decrease in the slope safety factor. Laboratory experimental results show that the pore gas pressure throughout the whole unsaturated zone has the same value, which indicates that the gas pressure could spread quickly to the whole sample.

关键词： Landslide Force transfer mechanism Rainfall infiltration Water-air two-phase flow

Experimental study of a supersonic turbulent boundary layer using PIV

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Science China(Physics,Mechanics & Astronomy) 2011年第9期54卷 1702-1709页

作者： HE Lin yi ShiHe zhao YuXin tian LiFeng CHEN Zhi College of Aerospace and Material Engineering National University of Defense Technology Changsha 410073 China

Particle image velocimetry was applied to the study of the statistical properties and the coherent structures of a fiat plate turbulent boundary layer at Mach 3. The nanoparticles with a good flow-following capability in supersonic flows were adopted as the tracer particles in the present experiments. The results show that the Van Driest transformed mean velocity profile satisfies the incompressible scalings and reveals a log-law region that extends to yld=0.4, which is further away from the wall than that in incompressible boundary layers. The Reynolds stress profiles exhibit a plateau-like region in the log-law region. The hairpin vortices in the streamwise-wall-normal plane are identified using different velocity decompositions, which are similar to the results of the flow visualization via NPLS technique. And multiple hairpin vortices are found moving at nearly the same velocity in different regions of the boundary layer. In the streamwise-spanwise plane, elongated streaky structures are observed in the log-law region, and disappear in the outer region of the boundary layer, which is contrary to the flow visualization results.

关键词： PIV turbulence supersonic boundary layer hairpin vortices statistical property coherent structures

Study of density field measurement based on NPLS technique in supersonic flow

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Science China(Physics,Mechanics & Astronomy) 2009年第9期52卷 1357-1363页

作者： tian LiFeng yi ShiHe zhao YuXin HE Lin CHENG ZhongYu College of Aerospace and Material Engineering National University of Defense TechnologyChangsha 410073China

Due to the influence of shock wave and turbulence, supersonic density field exhibits strongly inhomogeneous and unsteady characteristics. Applying traditional density field measurement techniques to supersonic flows yields three problems: low spatiotemporal resolution, limitation of measuring 3D density field, and low signal to noise ratio (SNR). A new method based on Nano-based Planar Laser Scattering (NPLS) technique is proposed in this paper to measure supersonic density field. This method measures planar transient density field in 3D supersonic flow by calibrating the relationship between density and concentration of tracer particles, which would display the density fluctuation due to the influence of shock waves and vortexes. The application of this new method to density field measurement of supersonic optical bow cap is introduced in this paper, and the results reveal shock wave, turbulent boundary layer in the flow with the spatial resolution of 93.2 μm/pixel. By analyzing the results at interval of 5 μs, temporal evolution of density field can be observed.

关键词： NPLS supersonic density field high spatiotemporal resolution

The fractal measurement of experimental images of supersonic turbulent mixing layer

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Science China(Physics,Mechanics & Astronomy) 2008年第8期51卷 1134-1143页

作者： zhao YuXin yi ShiHe tian LiFeng HE Lin CHENG ZhongYu College of Aerospace and Material Engineering National University of Defense TechnologyChangsha 410073China

Flow visualization of supersonic mixing layer has been studied based on the high spatiotemporal resolution Nano-based Planar Laser Scattering(NPLS) method in SML-1 wind tunnel. The corresponding images distinctly reproduced the flow structure of laminar,transitional and turbulent region,with which the fractal measurement can be implemented. Two methods of measuring fractal dimension were introduced and compared. The fractal dimension of the transitional region and the fully developing turbulence region of supersonic mixing layer were measured based on the box-counting method. In the transitional region,the fractal dimension will increase with turbulent intensity. In the fully developing turbulent region,the fractal dimension will not vary apparently for different flow structures,which em-bodies the self-similarity of supersonic turbulence.

关键词： NPLS turbulence mixing layer fractal dimension

A flow control study of a supersonic mixing layer via NPLS

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Science China(Physics,Mechanics & Astronomy) 2009年第12期52卷 2001-2006页

作者： yi ShiHe HE Lin zhao YuXin tian LiFeng CHENG ZhongYu College of Aerospace and Material Engineering National University of Defense TechnologyChangsha 410073China

The flow control of a supersonic mixing layer was studied in a supersonic mixing layer wind tunnel with convective Mach number (Mc) at 0.5. The passive control of the mixing layer was achieved by perturbation tapes on the trailing edge of the splitter plate. The control effects of 2D and 3D perturbation tapes with different sizes were compared. The mixing layer was visualized via NPLS,and the transient fine structures were identifiable in NPLS images,which were used to analyze the effects of flow control. The results show that the 2D tapes can enhance the 2D characteristic of the mixing layer,delaying mixing layer transition; and the 3D tapes can enhance the 3D characteristic of the mixing layer,advancing mixing layer transition. 3D structures of the mixing layer were visualized,and the H-type Λ vortexes were found with 3D tapes control.

关键词： supersonic mixing layer NPLS flow control

Characterization and performance of graphene-PbSe thin film heterojunction

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Rare Metals 2021年第1期40卷 219-224页

作者： Bo He yi-Xuan Ren tian-Jun Dai Shuang Hou Xing-zhao Liu School of Electronics Science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731China State Key Laboratory of Electronic Thin Films and Integrated Devices Chengdu 611731China

An infrared detector with high responsivity based on graphene-PbSe thin film heterojunction was ***-quality PbSe thin film and graphene were prepared by molecular beam epitaxy and chemical vapor deposition,*** physical characteristics of PbSe thin film and graphene were performed using X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and Raman *** photo transistor using PbSe thin film as a sensitizer and graphene as a channel to transport excitons exhibits peak responsivity and detectivity up to~420 A·W^(-1) and 5.9×10^(11) Jones(radiation intensity:0.75 mW·cm^(-2))at room temperature in the near-infrared(NIR)region,*** high optical response is attributed to the photo-excited holes transferring from PbSe film to graphene under ***,it is revealed that the responsivity of graphene-PbSe photo transistor is gate-tunable which is important in photodetectors.

关键词： PbSe Graphene Heterojunction Infrared photodetectors

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BP网络在优化精轧AGC硬度系数中的应用

武钢技术 2010年第6期48卷 4-7页

作者：李冀于奕田东赵闻张悫武钢热轧总厂一分厂湖北武汉430083

武钢热轧1700 mm生产线经过2009年的技术改造后,精轧F1~F7的压下部分设备全部更换为电动和液压混合控制。为了提高精轧AGC控制的水平,应用BP网络的理论对AGC厚度模型进行自学习,通过实时数据的统计和分析,证明BP网络的理论对提高带钢的... 详细信息

武钢热轧1700 mm生产线经过2009年的技术改造后,精轧F1~F7的压下部分设备全部更换为电动和液压混合控制。为了提高精轧AGC控制的水平,应用BP网络的理论对AGC厚度模型进行自学习,通过实时数据的统计和分析,证明BP网络的理论对提高带钢的厚度精度有明显的效果。

关键词： AGC模型 BP网络自学习厚度精度

Low intensity ultrasound-induced apoptosis in human gastric carcinoma cells

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World Journal of Gastroenterology 2008年第31期14卷 4873-4879页

作者： yi Feng Zhong-Min tian Ming-Xi Wan zhao-Bin Zheng Key Laboratory of Biomedical Information Engineering of Ministry of Education Department of Biomedical Engineering School of Life Science and Technology Xi'an Jiaotong University Xi'an 710049 Shaanxi Province China

AIM： To investigate the low intensity ultrasound （US）- induced apoptosis in human gastric carcinoma cells and its potential mechanism and to suggest a new therapeutic approach to gastric carcinoma. METHODS： Human SGC-7901 gastric carcinoma cells were cultured in vitro and irradiated by low intensity US for 10 min at different intensities with different incubation times after irradiation. Morphologic changes were examined under microscope with trypan blue staining and then the percentage of early apoptotic cells was detected by flow cytometry （FCM） with double staining of fiuorescein isothiocyanate （FITC）- Annexin V/propidium iodide （PI）. Two-dimensional electrophoresis （2DE） was used to get the protein profile and some proteins differently expressed after US irradiation were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF-MS）. Functional analysis was performed to investigate the mechanism of US-induced cell apoptosis. RESULTS： The percentage of apoptotic cells increased about 10% after US irradiation （12.0 W/cm^2, 12 h culture）, The percentage of early apoptosis and secondary necrosis in the US-irradiated cells increased with the increased US intensity. Moreover, apoptotic cells increased with the increased culture time after US irradiation and reached its maximum at about 12 *** new proteins appeared after US irradiation and were up or down regulated more than 2 times. Some heat shock proteins （HSPs） were found to be associated with the signal process simulating the apoptosis of cells. CONCLUSION： Low intensity US could induce apoptosis in human gastric carcinoma cells. US-induced apoptosis is related to US intensity/culture time. US-induced apoptosis may be caspases-dependent and endoplasmic reticulum （ER） stress-triggered apoptosis may also contribute to it. Proteomic experimental system is useful in finding the protein alteration in carcinoma cells after US irradiation, helping to develop a new cancer

关键词： SGC-7901 human gastric carcinoma cells Low intensity ultrasound Apoptosis Caspasesdependent Proteomics

Face recognition based on subset selection via metric learning on manifold

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Frontiers of Information Technology & Electronic Engineering 2015年第12期16卷 1046-1058页

作者： Hong SHAO Shuang CHEN Jie-yi zhao Wen-cheng CUI tian-shu YU School of Information Science and Engineering Shenyang University of Technology The University of Texas Health Science Center at Houston Schulich School of Engineering University of Calgary

With the development of face recognition using sparse representation based classification(SRC), many relevant methods have been proposed and investigated. However, when the dictionary is large and the representation is sparse, only a small proportion of the elements contributes to the l1-minimization. Under this observation,several approaches have been developed to carry out an efficient element selection procedure before SRC. In this paper, we employ a metric learning approach which helps find the active elements correctly by taking into account the interclass/intraclass relationship and manifold structure of face images. After the metric has been learned, a neighborhood graph is constructed in the projected space. A fast marching algorithm is used to rapidly select the subset from the graph, and SRC is implemented for classification. Experimental results show that our method achieves promising performance and significant efficiency enhancement.

关键词： Face recognition Sparse representation Manifold structure Metric learning Subset selection