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Formulation of cross-anisotropic failure criterion for soils

Water Science and Engineering 2013年第4期6卷 456-468页

作者： yi-fei sun Han-long LIU Gui YANG Yang XIAO Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University School of Civil Engineering University of Wollongong Geotechnical Research Institute Hohai University

Inherently anisotropic soil fabric has a considerable influence on soil strength. To model this kind of inherent anisotropy, a three-dimensional anisotropic failure criterion was proposed, employing a scalar-valued anisotropic variable and a modified general three- dimensional isotropic failure criterion. The scalar-valued anisotropic variable in all sectors of the deviatoric plane was defined by correlating a normalized stress tensor with a normalized fabric tensor. Detailed comparison between the available experimental data and the corresponding model predictions in the deviatoric plane was conducted. The proposed failure criterion was shown to well predict the failure behavior in all sectors, especially in sector II with the Lode angle ranging between 60° and 120°, where the prediction was almost in accordance with test data. However, it was also observed that the proposed criterion overestimated the strength of dense Santa Monica Beach sand in sector III where the intermediate principal stress ratio b varied from approximately 0.2 to 0.8, and slightly underestimated the strength when b was between approximately 0.8 and 1. The difference between the model predictions and experimental data was due to the occurrence of shear bending, which might reduce the measured strength. Therefore, the proposed anisotropic failure criterion has a strong ability to characterize the failure behavior of various soils and potentially allows a better description of the influence of the loading direction with respect to the soil fabric.

关键词： eross-anisotropy soil fabric failure criterion triaxial test torsional shear test

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Acoustic characterization of hydrate formation and decomposition in clay-bearing sediments

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Petroleum Science 2024年第4期21卷 2830-2838页

作者： yi-Jian Zhu Xiao-Mei Yang Xing Huang Hao Li Xiao-Hui Wang yi-fei sun Peng Xiao Chang-Yu sun Guang-Jin Chen State Key Laboratory of Heavy Oil Processing College of Chemical Engineering and EnvironmentChina University of PetroleumBeijing102249China

Understanding the acoustic characteristics of hydrates in various sediments is crucial for hydrate resource detection and safe and efficient exploitation,as hydrate occurrence patterns vary greatly in different *** this work,sediments with different bentonite contents,water saturations,and types were prepared to investigate the characteristics of P-wave velocity(reflecting the magnitude of hydrate saturation in the sediment)and amplitude(reflecting the degree of hydrate-sediment cementation)during hydrate formation and *** hydrate formation,the P-wave velocity and amplitude have similar *** clay content increases,the P-wave velocity increase rates *** the other hand,the increased rate of P-wave velocity slows down with the increase of water saturation in the clay-bearing *** various types of sediment shows that the water absorption and swelling of bentonite reduce the pore space,speeding up the cementation of the hydrate with the sediment and increasing P-wave velocity at a faster *** between P-wave velocity and hydrate saturation is strongly related to sediment type,clay content,and water *** rapidly decreasing amplitude in the early stage of hydrate depressurization indicates that hydrate in clay-bearing sediments is weakly cemented to the sediments,which is prone to stratigraphic *** findings of this study offer guidance for hydrate resource assessments in clay-bearing sediments as well as geologic risk estimations during hydrate mining.

关键词： Gas hydrate Bentonite Illite P-wave velocity Amplitude

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Influences of pore fluid on gas production from hydrate-bearing reservoir by depressurization

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Petroleum Science 2023年第2期20卷 1238-1246页

作者： yi-fei sun Bo-Jian Cao Hong-Nan Chen yin-Long Liu Jin-Rong Zhong Liang-Liang Ren Guang-Jin Chen Chang-Yu sun Dao-yi Chen State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China Division of Ocean Science and Technology Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhenGuangdong 518055China School of Chemistry and Food Engineering Changsha University of Science&TechnologyChangshaHunan 410114China Oilfield Chemicals R&D Institute COSLHebei 065201China

In addition to the temperature and pressure conditions,the pore fluid composition and migration behavior are also crucial to control hydrate decomposition in the exploitation *** this work,to investigate the effects of these factors,a series of depressurization experiments were carried out in a visible one-dimensional reactor,using hydrate reservoir samples with water saturations ranging from 20%to 65%.The results showed a linear relationship between gas production rates and gas saturations of the reservoir,suggesting that a larger gas-phase space was conducive to hydrate decomposition and gas ***,the rapid water production in the early stage of hydrate exploitation could release more gas-phase space in the water-rich reservoir,which in turn improved the gas production ***,the spatiotemporal evolution of pore fluids could lead to partial accelerated decomposition or secondary formation of *** the unsealed reservoir,the peripheral water infiltration kept reservoir at a high water saturation,which hindered the overall production process and caused higher water ***,depressurization assisted with the N2 sweep could displace the pore water *** to the results,it is recommended that using the short-term N2 sweep as an auxiliary means in the early stage of depressurization to expand the gas-phase space in order to achieve the highest production efficiency.

关键词： CH4 hydrate Water saturation Depressurization Gas-phase space N2 sweep

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Detection performance improvement of photon counting chirped amplitude modulation lidar with response probability correction

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Chinese Physics B 2018年第9期27卷 322-326页

作者： yi-fei sun Zi-Jing Zhang Li-Yuan Zhao Wei-Min sun Yuan Zhao Department of Physics Harbin Institute of TechnologyHarbin 150001China Key Laboratory of In-fiber Integrated Optics Harbin Engineering UniversityHarbin 150001China

Geiger mode avalanche photodiode detector （Gm-APD） possesses the ultra-high sensitivity. Photon counting chirped amplitude modulation （PCCAM） light detection and ranging （lidar） uses the counting results of the returned signal detected by Gm-APD to mix with the reference signal, which makes PCCAM lidar capable of realizing the ultra-high sensitivity, and this is very important for detecting the remote and weak signal. However, Gm-APD is a nonlinear device, different from traditional linear detectors. Due to the nonlinear response of Gm-APD, the counting results of the returned signal detected by Gm-APD are different from those of both the original modulation signal and the reference signal. This will affect the mixing effect and thus degrade the detection performance of PCCAM lidar. In this paper, we propose a response probability correction method. First, the response probability correction model is established on the basis of Gm-APD Poisson prob- ability response model. Then, the response probability correction model is used to adjust the original modulation signal that is used to drive laser, in order to make the counting results of the returned signal detected by Gm-APD better mix with the local reference signal in the same form. Through this method, the detection performance of PCCAM lidar is enhanced efficiently.

关键词： photon counting chirping lidar

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Self-adaptive gas flow and phase change behaviors during hydrate exploitation by alternate injection of N_(2) and CO_(2)

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Petroleum Science 2024年第3期21卷 2120-2129页

作者： Bo-Jian Cao yi-fei sun Hong-Nan Chen Jin-Rong Zhong Ming-Long Wang Ming Wang Chang-Yu sun Guang-Jin Chen State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China School of Chemistry and Chemical Engineering Changsha University of Science&TechnologyChangsha410114HunanChina

Since hydrate resources play a part of the stratigraphic framework structure in sediments,establishing a safe and economic method for hydrates exploitation remains the primary challenge to this *** the proposed methods,the spontaneous displacement of CH_(4) from hydrate cages by CO_(2) seems to be a perfect mechanism to address gas production and CO_(2) storage,especially in today's strong demand for carbon reduction and replacing clean *** extensive lab researches,in the past decade,injecting a mixture of CO_(2) and small molecule gas has become a key means to enhance displacement efficiency and has great potential for ***,there is a lack of in-depth research on gas flow in the reservoir,while the injected gas always passes through low-saturated hydrate areas with high permeability and then occurs gas channel in a short term,finally resulting in the decreases in gas production efficiency and produced gas ***,we explored a new injection-production mode of alternate injection of N2 and CO_(2) in order to fully coordinate the advantages of N_(2) in enhanced hydrate decomposition and CO_(2) in solid storage and heat *** alternate"taking"and"storing"processes perfectly repair the problem of the gas channel,achieving self-regulation effect of CH_(4) recovery and CO_(2) *** 3-D experimental results show that compared to the mixed gas injection,CH_(4) recovery is increased by>50%and CO_(2) storage is increased by>70%.Additionally,this alternate injection mode presented a better performance in CH_(4) concentration of produced gas and showed outstanding N_(2) utilization ***,we analyzed its self-adaptive gas flow mechanism and proposed an application model of"one injection and multiple production".We look forward to this study accelerating the application of CO_(2)-CH_(4) replacement technology.

关键词： Hydrate Replacement CH_(4)recovery CO_(2)storage Reservoir remediation

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Microscopic experimental study on the effects of NaCl concentration on the self-preservation effect of methane hydrates under 268.15 K

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Chinese Journal of Chemical Engineering 2024年第9期73卷 1-14页

作者： Yu-Jie Zhu Yu-Zhou Chen Yan Xie Jin-Rong Zhong Xiao-Hui Wang Peng Xiao yi-fei sun Chang-Yu sun Guang-Jin Chen State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China Research Centre of Ecology&Environment for Coastal Area and Deep Sea Guangdong University of TechnologyGuangzhou 510006China School of Chemistry and Food Engineering Changsha University of Science and TechnologyChangsha 410114China

It is known that salt ions are abundant in the natural environment where natural gas hydrates are located;thus,it is essential to investigate the self-preservation effect of salt ions on methane *** dissociation behaviors of gas hydrates formed from various NaCl concentration solutions in a quartz sand system at 268.15 K were investigated to reveal the microscopic mechanism of the self-preservation effect under different salt *** showed that as the salt concentration rises,the initial rate of hydrate decomposition *** hydrate hardly shows self-preservation ability in the 3.35%(mass)NaCl and seawater systems at 268.15 *** the morphology of hydrate observed by the confocal microscope with results obtained from in situ Raman spectroscopy,it was found that during the initial decomposition stage of gas hydrate below the ice point,gas hydrate firstly converts into liquid water and gas molecules,then turns from water to solid ice rather than directly transforming into solid ice and gas *** presence of salt ions interferes with the ability of liquid water to condense into solid *** results of this study provide an important guide for the mechanism and application of the self-preservation effect on the storage and transport of gas and the exploitation of natural gas hydrates.

关键词： Gas hydrate Self-preservation Salinity In situ Raman spectroscopy Endothermic behavior Dissociation

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Systematic classification and phylogenetic relationships of the brown‑rot fungi within the Polyporales

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Fungal Diversity 2023年第1期118卷 1-94页

作者： Shun Liu Yuan‑Yuan Chen yi‑fei sun Xiao‑Lan He Chang‑Ge Song Jing Si Dong‑Mei Liu Genevieve Gates Bao‑Kai Cui Institute of Microbiology School of Ecology and Nature ConservationBeijing Forestry UniversityBeijing 100083China College of Forestry Henan Agricultural UniversityZhengzhou 450002HenanChina Sichuan Institute of Edible Fungi Sichuan Academy of Agricultural SciencesChengdu 610066SichuanChina Institute of Ecology Chinese Academy of Environmental SciencesBeijing 100012China Tasmanian Institute of Agriculture Private Bag 98HobartTAS 7001Australia

The brown-rot fungi play an important role in forest ecosystems;they can degrade celluloses and hemicelluloses of wood and maintain nutrient *** of the brown-rot fungi also have important economic value as medicinal or edible *** studies showed that the ability to produce brown rot has evolved independently at least five ***,the Polyporales contains the vast majority of the species of the brown-rot *** this study,the classification system of the brown-rot fungi within the Polyporales is ***,the phylogenetic relationships of brown-rot fungi within the Polyporales are analysed based on DNA sequences of multiple loci including the internal transcribed spacer(ITS)regions,the large subunit nuclear ribosomal RNA gene(nLSU),the small subunit nuclear ribosomal RNA gene(nSSU),the small subunit mitochondrial rRNA gene sequences(mtSSU),the translation elongation factor 1-αgene(TEF1),the RNA polymerase II largest subunit(RPB1)and the second subunit of RNA polymerase II(RPB2).The study showed that the brownrot fungi within the Polyporales formed fourteen lineages,which are assigned at family level,including four new families:Auriporiaceae,Piptoporellaceae,Postiaceae,Taiwanofungaceae,and ten existing families:Adustoporiaceae,Dacryobolaceae,Fibroporiaceae,Fomitopsidaceae,Laetiporaceae,Laricifomitaceae,Phaeolaceae,Pycnoporellaceae,Sarcoporiaceae,and ***,eleven new genera,viz.,Austroporia,Aurantipostia,Austropostia,Daedalella,Nothofagiporus,Pseudoantrodia,Pseudofomitopsis,Rhodoantrodia,Tenuipostia,Wolfiporiella and Wolfiporiopsis are proposed;eighteen new species,viz.,Amyloporia nivea,Antrodia subheteromorpha,Aurantipostia macrospora,Austropostia hirsuta,***,***,Cystidiopostia subhibernica,Daedalella micropora,Fuscopostia subfragilis,Lentoporia subcarbonica,Melanoporia tropica,Neolentiporus tropicus,Phaeolus fragilis,Postia crassicontexta,Pseudoantrodia monomitica,Pseudofomitopsis microcar

关键词： Brown-rot fungi Fomitopsidaceae Multi-gene phylogeny New taxa Taxonomy Wood-rotting fungi

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高精度星敏感器标定方法研究

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仪器仪表学报 2017年第9期38卷 2154-2160页

作者：易敏邢飞孙婷王宏北京信息科技大学先进光电子技术国际合作联合实验室北京100192 清华大学精密仪器系北京100084

星敏感器是一种广泛应用在航天飞行器中的高精度姿态测量器件,精度标定是保证高精度测量的重要环节。为了尽量提高星敏感器的整体精度,对传统星敏感器标定方法进行了仿真分析,针对传统星敏感器标定方法模型参数难以解耦的弊端,提出单独... 详细信息

星敏感器是一种广泛应用在航天飞行器中的高精度姿态测量器件,精度标定是保证高精度测量的重要环节。为了尽量提高星敏感器的整体精度,对传统星敏感器标定方法进行了仿真分析,针对传统星敏感器标定方法模型参数难以解耦的弊端,提出单独标定主点,将星敏感器光学参数误差(如焦距、成像平面倾斜和畸变)等看作一个整体误差源,采用直接映射的方式进行标定。该方法简单方便、标定精度高,避免了传统方法中误差影响因素分析不全面及多次求取拟合近似值造成的累积误差。实验结果表明,该标定方法完全满足测量角误差2″的要求。

关键词：光学参数高精度标定整体误差源直接映射

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Design and Implementation of differential RS422 serial transceiver module based on FPGA

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微计算机信息 2010年第35期 127-128+53页

作者： SUO yi-fang GAO fei sun Lei(Beijing Institute of Technology,Beijing,100081,China)

This paper introduces a RS422 signal processing system of differential based on FPGA,The system use the VIRTEX XILINX chips XQV300 for control,use the LTC2851 LINEAR differential signal processing chip for the RS422 *** of VHDL hardware design language within the FPGA to design the receive and send serial *** to realize the design of differential serial transceiver *** design has a very good universal,flexibility and the practical value.

关键词： FPGA Serial Transceiver Module RS422 VHDL language

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Preparation of gradient wettability surface by anodization depositing copper hydroxide on copper surface

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Transactions of Nonferrous Metals Society of China 2015年第7期25卷 2301-2307页

作者：程江孙逸飞赵安黄子恒徐守萍华南理工大学化学与化工学院广州510640

A facile route for preparation of gradient wettability surface on copper substrate with contact angle changing from 90.3°to4.2°was *** Cu（OH）2 nanoribbon arrays were electrochemically deposited on copper foil via a modified anodization technology,and the growth degree and density of the Cu（OH）2 arrays may be controlled varying with position along the substrate by slowly adding aqueous solution of KOH into the two-electrode cell of an anodization system to form the gradient *** prepared surface was water resistant and thermal stable,which could keep its gradient wetting property after being immersed in water bath at 100℃ for 10 *** results of scanning electron microscopy（SEM）,X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS） demonstrate that the distribution of Cu（OH）2 nanoribbon arrays on copper surface are responsible for the gradient wettability.

关键词： gradient wettability surface Cu(OH)2 nanoribbon array anodization depositing contact angle

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