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Finite element response sensitivity analysis of three-dimensional soil-foundation-structure interaction (SFSI) systems

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Earthquake Engineering and Engineering Vibration 2018年第3期17卷 555-566页

作者： Gu quan liu Yongdou li Yong lin Chun School of Architecture and Civil Engineering Xiamen University Department of Civil and Environmental Engineering University of Alberta

The nonlinear finite element（FE） analysis has been widely used in the design and analysis of structural or geotechnical *** response sensitivities（or gradients） to the model parameters are of significant importance in these realistic engineering *** the sensitivity calculation has lagged behind,leaving a gap between advanced FE response analysis and other research hotspots using the response *** response sensitivity analysis is crucial for any gradient-based algorithms,such as reliability analysis,system identification and structural *** various sensitivity analysis methods,the direct differential method（DDM） has advantages of computing efficiency and accuracy,providing an ideal tool for the response gradient *** paper extended the DDM framework to realistic complicated soil-foundation-structure interaction（SFSI） models by developing the response gradients for various constraints,element and materials *** enhanced framework is applied to three-dimensional SFSI system prototypes for a pilesupported bridge pier and a pile-supported reinforced concrete building frame structure,subjected to earthquake loading *** DDM results are verified by forward finite difference method（FFD）.The relative importance（RI） of the various material parameters on the responses of SFSI system are investigated based on the DDM response sensitivity *** FFD converges asymptotically toward the DDM results,demonstrating the advantages of DDM（e.g.,accurate,efficient,insensitive to numerical noise）.Furthermore,the RI and effects of the model parameters of structure,foundation and soil materials on the responses of SFSI systems are investigated by taking advantage of the sensitivity analysis *** extension of DDM to SFSI systems greatly broaden the application areas of the d gradient-based algorithms,*** model updating and nonlinear system identification of complicated SFSI systems.

关键词： finite element method response sensitivity analysis direct differentiation method finite difference method soil-foundation-structure interaction

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Maximum Hydrogen Production by Autothermal Steam Reforming of Bio-oil With NiCuZnAI Catalyst

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Chinese Journal of Chemical Physics 2012年第3期25卷 365-372,374页

作者： Shi-zhi Yan Qi Zhai quan-xin li Department of Chemical Physics Lab of Biomass Clean EnergyUniversity of Science and Technologyof ChinaHefei 230025China

Autothermal steam reforming （ATR） of bio-oil, which couples the endothermic steam reform- ing reaction with the exothermic partial oxidation, offers many advantages from a technical and economic point of view. Effective production of hydrogen through ATR of bio-oil was performed at lower temperature with NiCuZnAl catalyst. The highest hydrogen yield from bio-oil reached 64.3% with a nearly complete bio-oil conversion at 600℃, the ratio of steam to carbon fed （S/C） of 3 and the oxygen to carbon ratio （O/C） of 0.34. The reaction conditions in ATR including temperature, O/C, S/C and weight hourly space velocity can be used to control both hydrogen yield and products distribution. The comparison between the ATR and common steam reforming of bio-oil was studied. The mechanism of the ATR of bio-oil was also discussed.

关键词： Hydrogen Bio-oil Autothermal steam reforming NiCuZnA1 catalyst

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Modern pollen assemblages from surface lake sediments in northwestern China and their importance as indicators of vegetation and climate

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Science China Earth Sciences 2015年第9期58卷 1643-1655页

作者： QIN Feng ZHAO Yan li quan CAI MaoTang Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Nature Resources ResearchChinese Academy of Sciences

The modern pollen assemblages of surface lake sediments and topsoils in northwestern China were studied to understand the relationship of modem pollen data with contemporary vegetation and climate, and the differences between the pollen assem- blages of surface lake sediments and topsoils. The results show that Chenopodiaceae and Artemisia are dominant elements in the pollen assemblages of northwestern China. Additionally, Ephedra, Cyperaceae, Asteraceae, Poaceae, Picea, Pinus, and Betula are also important pollen taxa. Both pollen assemblages and principal component analysis indicate that pollen data from surface lake sediments and topsoils can be used to differentiate the main vegetation types of this region （desert, steppe, mead- ow and forest）. However, differences exist between modern pollen assemblages of the two types of sediments due to the dif- ferent relevant source areas of pollen and degrees of pollen preservation. For example, the larger relevant source area of sur- face lake sediment results in a higher abundance of Betula in pollen assemblage from surface lake sediment, whereas the ten- dency to disintegrate thin-walled pollen types in topsoil leads to a higher proportion of resistant pollen, such as Asteraceae. linear regression analysis indicates that the Artemisia/Chenopodiaceae （A/C） ratio in pollen assemblages of surface lake sedi- ments can be used to indicate humidity changes in the study area. However, the A/C ratio in topsoils should be used carefully. Our results suggest that pollen data from surface lake sediments would be better references for interpreting the fossil pollen assemblages of lake cores or lacustrine profiles.

关键词： modern pollen assemblage surface lake sediment topsoil vegetation climate northwestern China

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Drag reduction of turbulent channel flows over an anisotropic porous wall with reduced spanwise permeability

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Applied Mathematics and Mechanics(English Edition) 2019年第7期40卷 1041-1052页

作者： Qingxiang li Ming PAN quan ZHOU Yuhong DONG Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University Shanghai 200072 China

The direct numerical simulation (DNS) is carried out for the incompressible viscous turbulent flows over an anisotropic porous wall. Effects of the anisotropic porous wall on turbulence modifications as well as on the turbulent drag reduction are investigated. The simulation is carried out at a friction Reynolds number of 180, which is based on the averaged friction velocity at the interface between the porous medium and the clear fluid domain. The depth of the porous layer ranges from 0.9 to 54 viscous units. The permeability in the spanwise direction is set to be lower than the other directions in the present simulation. The maximum drag reduction obtained is about 15.3% which occurs for a depth of 9 viscous units. The increasing of drag is addressed when the depth of the porous layer is more than 25 wall units. The thinner porous layer restricts the spanwise extension of the streamwise vortices which suppresses the bursting events near the wall. However, for the thicker porous layer, the wall-normal fluctuations are enhanced due to the weakening of the wall-blocking effect which can trigger strong turbulent structures near the wall.

关键词： direct numerical simulation (DNS) anisotropic porous medium drag reduction turbulent open channel flow

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Distributed Harmonic Power Sharing with Voltage Distortion Suppression in Islanded Microgrids Considering Non-linear Loads

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 117-128页

作者： Guannan Lou Shanlin li Wei Gu quan Yang School of Electrical Engineering Southeast UniversityNanjingJiangsu 210096China the Jiangsu Provincial Key Laboratory of Smart Grid Technology and Equipment Southeast University Dongguan Power Supply Bureau of Guangdong Power Grid Company Guangdong 523000China

In contemporary power grids or microgrids,harmonic distortion has emerged as one of the critical power quality issues for utility power grids,which has escalated especially due to the high penetration of power-electronic-converter-interfaced distributed generation(DG).This paper first illustrates the prevalent dispute revolving around the harmonic power sharing and distortion restraint,and subsequently proposes a consensusbased framework that facilitates an accurate sharing of harmonics among multi-DGs connected in parallel,with an effective suppression of the output voltage *** with the majority of existing studies addressing the issue of voltage harmonics at the point of common coupling(PCC),our method primarily emphasizes on the output voltage distortion since the power quality requirement for certain local critical loads is often known to be *** the help of adaptive regulation,the overall distortion produced at the output terminals of DGs can be retained within an acceptable *** working principle of the proposed control method,which is not only easy to implement but also independent of model parameters,is further described in *** the small-signal dynamic model,the system stability and robustness are *** hardware-in-the-loop(HIL)simulations aid in determining the outcome of the proposed strategy in microgrid control.

关键词： Distributed generation droop control harmonic power sharing microgrid voltage distortion mitigation

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Spatial variability of soil bulk density and its controlling factors in an agricultural intensive area of Chengdu Plain,Southwest China

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Journal of Integrative Agriculture 2019年第2期18卷 290-300页

作者： li Shan li Qi-quan WANG Chang-quan li Bing GAO Xue-song li Yi-ding WU De-yong College of Resources Sichuan Agricultural UniversityChengdu 611130P.R.China

Soil bulk density is a basic but important physic soil property related to soil porosity,soil moisture and hydraulic conductivity,which is crucial to soil quality assessment and land use *** this study,we evaluated the spatial variability of soil bulk density in the 0–20,20–40,40–60 and 60–100 cm layers as well as its affecting factors in Southwest China’s agricultural intensive *** indicated the mean value of surface soil bulk density(0–20 cm)was 1.26 g cm^(–3),significantly lower than that of subsoil(20–100 cm).No statistical difference existed among the subsoil with a mean soil bulk density of 1.54 g cm^(–3).Spatially,soil bulk density played a similar spatial pattern in soil profile,whereas obvious differences were found in *** nugget effects for soil bulk density in the 0–20 and 20–40 cm layers were 27.22 and27.02%while 12.06 and 3.46%in the 40–60 and 60–100 cm layers,respectively,gradually decreasing in the soil profile,indicating that the spatial variability of soil bulk density above 40 cm was affected by structural and random factors while dominated by structural factors under 40 *** organic matter was the controlling factor on the spatial variability of soil bulk density in each *** use and elevation were another two dominated factor controlling the spatial variability of soil bulk density in the 0–20 and 40–60 cm layers,*** genus was one of the dominated factors controlling the spatial variability of soil bulk below 40 cm.

关键词： soil bulk density profile spatial variability controlling factors Chengdu Plain

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Phase transformation and thermal analysis during combustion synthesis of Mg_(17)Al_(12) alloy

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Rare Metals 2014年第1期33卷 37-40页

作者： Yu-li Zhou Yun Lu Yun-Feng Zhu li-quan li College of Materials Science and Engineering Nanjing University of Technology

The Mg-A1 hydrogen storage alloy was suc- cessfully prepared by combustion synthesis （CS） method. The formation of alloy phases during the CS process was studied using X-ray diffraction （XRD）, scanning electron microscope （SEM）, and differential scanning calorimetry （DSC）. When the time increases from 0, 0.5, 1.0 to 2.0 h at 733 K, the products are Mg and A1; Mg2A13, Mg and A1; Mgl7All2, Mg2A13; and Mg; and eventually only MgI7A112, respectively. Combined with three peaks in the DSC traces, it is concluded that the formation of MglyAll2 during the CS includes three processes, namely, the formation of MgzA13 first; then the unsaturated solid solution, MglvAla2; and finally the complete MglvA112 alloy. The formation of MgzA13 prior to MglvA112 in this work is different from those prepared by mechanical alloying. This is thought to be related to the instant high temperature during the ther- mal explosion of CS.

关键词： Mg-A1 alloy Combustion synthesis Phasetransformation Thermal analysis

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Analysis of humidity-dependent adhesion between a probe tip and a surface

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Particuology 2017年第4期15卷 91-97页

作者： li Yang Junhui Hu Huapeng Xiao Wenwen quan College of Physics Science and Technology Guangxi Normal University Guilin 541004 China

Adhesive forces commonly exhibit a monotonic increase or a maximum with increasing relative humidity. However, anomalous behavior has been reported. Here, a numerical model of adhesive forces, comprised mainly of capillary and van der Waals forces, between a tip and a surface is established. It is described by a power law that considers the geometry, the liquid bridge wetting radius, the contact angle, and the separation distance. Capillary forces （sum of surface tension and Laplace pressure） and van der Waals forces are calculated. The latter cannot be neglected in the adhesion even at high humidity. Decrease in adhesion with increasing relative humidity can be attributed to a blunt tip shape, which is validated by experimental data. Specifically, the decrease in adhesion is attributed primarily to a transition from a rounded to a blunt tip shape. Structuring objects at the micro- or nanoscale can either increase or decrease adhesion as a function of relative humidity. This has a wide range of applications in robotic manipulation and can provide a better understanding of adhesion mechanisms in atomic force microscopy in ambient air.

关键词： Abnormality decrease Adhesive force Tip shape Capillary force Van der Waals force

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Gastrotracheal fistula:Treatment with a covered self-expanding Y-shaped metallic stent

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World Journal of Gastroenterology 2015年第3期21卷 1032-1035页

作者： Fei Wang Hong Yu Ming-Hui Zhu quan-Peng li Xian-Xiu Ge Jun-Jie Nie lin miao Institute of Digestive Endoscopy and Medical Center for Digestive Diseases Second Affiliated Hospital of Nanjing Medical University Department of Gastroenterology People’s Hospital of Jingjiang

A 67-year-old man had a sev-ere cough and pulmonary infection for 1 wk before seeking evaluation at our *** had undergone esophagectomy with gastric pull-up and radiotherapy for esophageal cancer 3 years *** admission to our hospital,gastroscopy and bronchoscopy revealed a fistulous communication between the posterior tracheal wallnear the carina and the upper residual *** measured the diameter of the trachea and bronchus and determined the site and size of the fistula using multislice computed tomography and gastroscopy.A covered self-expanding Y-shaped metallic stent was implanted into the trachea and ***,the fistula was closed *** patient tolerated the stent well and had good palliation of his symptoms.

关键词： Gastrotracheal fistula Y-shaped metallic stent Eso

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Effect of processing parameters on flow behaviors and microstructure during high temperature deformation of GH4586 superalloy

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Journal of Central South University 2021年第2期28卷 338-350页

作者： LUO Jiao li Xiang-yang li Cong li miao-quan State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China

The apparent activation energy for deformation(Q)and strain rate sensitivity(m)of GH4586 superalloy are calculated and the variation trend is reasonably explained by the microstructure *** modelling of this superalloy is established and the processing maps at different strains are *** results show that the Q value is in the range of 751.22−878.29 kJ/*** a temperature of 1060°C,strain rate of 0.001 s^(−1),and strain of 0.65,the m value of GH4586 superalloy reaches a maximum of *** optimal processing parameter of GH4586 superalloy is at a deformation temperature of 1050°C and a strain rate of 0.001 s^(−1).The domains of flow instability notably expand with increasing strain during high temperature deformation of GH4586 superalloy.

关键词： GH4586 superalloy apparent activation energy for deformation strain rate sensitivity constitutive model processing maps

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