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Seismic response of underground utility tunnels: shaking table testing and FEM analysis

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Earthquake Engineering and Engineering Vibration 2010年第4期9卷 555-567页

作者： jiang Luzhen Chen jun Li Jie State Key Laboratory for Disaster Reduction in Civil Engineering Tongji University Shanghai 200092 China Department of Building Engineering Tongji University Shanghai 200092 China

Underground utility tunnels are widely used in urban areas throughout the world for lifeline networks due to their easy maintenance and environmental protection capabilities. However, knowledge about their seismic performance is still quite limited and seismic design procedures are not included in current design codes. This paper describes a series of shaking table tests the authors performed on a scaled utility tunnel model to explore its performance under earthquake excitation. Details of the experimental setup are first presented focusing on aspects such as the design of the soil container, scaled structural model, sensor array arrangement and test procedure. The main observations from the test program, including structural response, soil response, soil-structure interaction and earth pressure, are summarized and discussed. Further, a finite element model （FEM） of the test utility tunnel is established where the nonlinear soil properties are modeled by the Drucker- Prager constitutive model; the master-slave surface mechanism is employed to simulate the soil-structure dynamic interaction; and the confining effect of the laminar shear box to soil is considered by proper boundary modeling. The results from the numerical model are compared with experiment measurements in terms of displacement, acceleration and amplification factor of the structural model and the soil. The comparison shows that the numerical results match the experimental measurements quite well. The validated numerical model can be adopted for further analysis.

关键词： lifeline system utility tunnel shaking table test finite element method soil-structure interaction

After announced carbon neutrality targets,more homework ahead for research

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Advances in Climate Change Research 2022年第2期13卷 157-158页

作者： Ke-jun jiang Energy Research Institute Beijing 100038China

By January 2022,more than 130 countries announced their carbon neutrality target by 2050 or before 2060,with more than 80%of global emissions,making it possible to achieve the Paris Agreement *** on the IEA(2021),COP26 climate pledges could help limit global warming to 1.8℃,but implementing them will be the *** is a big change by looking back the history of human being's action on climate change.

关键词： neutral looking carbon

Adsorption and desorption of Cu(Ⅱ) and Pb(Ⅱ) in paddy soils cultivated for various years in the subtropical China

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Journal of Environmental Sciences 2010年第5期22卷 689-695页

作者： Liang Ma Renkou Xu jun jiang State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 China Graduate University of Chinese Academy of Sciences Beifing 100049 China

The adsorption and desorption of Cu（Ⅱ） and Pb（Ⅱ） on upland red soil,and paddy soils which were originated from the upland soil and cultivated for 8,15,35 and 85 years,were investigated using the batch *** study showed that the organic matter content and cation exchange capacity （CEC） of the soils are important factors controlling the adsorption and desorption of Cu（Ⅱ） and Pb（Ⅱ）.The 15-Year paddy soil had the highest adsorption capacity for Pb（Ⅱ）,followed by the 35-Year paddy *** the 35-Year paddy soil and 15-Year paddy soil adsorbed more Cu（Ⅱ） than the upland soil and other paddy *** 15-Year paddy soils exhibited the highest desorption percentage for both Cu（Ⅱ） and Pb（Ⅱ）.These results are consistent with the trend for the CEC of the soils *** high soil CEC contributes not only to the adsorption of Cu（Ⅱ） and Pb（Ⅱ） but also to the electrostatic adsorption of the two heavy metals by the *** desorption percentages for Cu（Ⅱ）（36.7% to 42.2%） and Pb（Ⅱ）（50.4% to 57.9%） were observed for the 85-Year paddy *** highest content of organic matter in the soil was responsible for the low desorption percentages for the two metals because the formation of the complexes between the organic matter and the metals could increase the stability of the heavy metals in the soils.

关键词： adsorption and desorption Cu(Ⅱ) Pb(Ⅱ) cultivation chronosequence paddy soil

A Sensor Redeployment Algorithm Based on Virtual Forces for Underwater Sensor Networks

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Chinese Journal of Electronics 2018年第2期27卷 413-421页

作者： jiang Peng WANG Xingmin LIU jun College of Automation Hangzhou Dianzi University

Practical underwater sensor networks redeployment algorithm needs to fully consider limited node resources, node move time and other characteristics in real environment. A Redeployment based on virtual forces(RBVF) algorithm is proposed. The non-persistent carrier sense multiple access protocol is introduced to solve communication conflicts between nodes during redeployment process. Based on existing study on three-dimensional space node deployment, the threshold value is determined to divide the attractive and repulsion forces. The speed of the node is considered. Simulation results indicate that the RBVF algorithm can achieve better coverage and less total move distance when moving nodes are not considered in virtual forces *** flow force is introduced, and a Virtual forces redeployment based on energy consuming(VFRBEC) algorithm is proposed, where different energy consumptions in different directions are used to modify node displacement. Simulation results indicate that the VFRBEC algorithm can achieve the same coverage performance with the RBVF algorithm with less energy and is better than the redeployment based on combined virtual forces algorithm in terms of both coverage and energy consumption performances.

关键词： Underwater sensor networks Virtual forces Node redeployment Water flow force

Preparation of double-shell Si@SnO_(2)@C nanocomposite as anode for lithium-ion batteries by hydrothermal method

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Rare Metals 2023年第9期42卷 2972-2981页

作者： Yu Lei Shuai Li Miao Du Jing Mi Dian-Chao Gao Lei hao Li-jun jiang Man Luo Wen-Quan jiang Fan Li Shao-Hua Wang National Engineering Research Center of Nonferrous Metals Materials and Products for New EnergyChina GRINM Group Co.Ltd.Beijing100088China GRINM(Guangdong)Institute for Advanced Materials and Technology Foshan528000China Beijing Key Laboratory for Catalysis and Separation Department of Chemical EngineeringBeijing University of TechnologyBeijing100124China

Silicon is one of the most promising anode materials for lithium-ion batteries(LIBs), but it suffers from pulverization and hence poor cycling stability due to the large volume variation during lithiation/delithiation. The core-shell structure is considered as an effective strategy to solve the expansion problem of silicon-based anodes. In this paper, the double-shell structured Si@SnO_(2) @C nanocomposite with nano-silicon as the core and SnO_(2) , C as the shells is synthesized by a facile hydrothermal *** characterization shows that Si@SnO_(2) @C nanocomposite is composed of crystalline Si, crystalline SnO_(2) and amorphous C, and the contents of them are 42.1wt%, 37.8 wt% and 20.1 wt%, respectively. Transmission electron microscope(TEM) observations confirm the double-shell structure of Si@SnO_(2) @C nanocomposite, and the thicknesses of the SnO_(2) and C layers are 20 and 7 nm. The Si@SnO_(2) @C electrode exhibits a high initial discharge capacity of 2777 mAh·g^(-1)at 100 mA·g^(-1)and an excellent rate capability of 340 mAh·g^(-1)at 1500 mA·g^(-1). The outstanding capacity retention is 50.2% after 300 cycles over a potential of 0.01 to 2.00 V(vs. Li/Li+) at 500 mA·g^(-1). The resistance of solid electrolyte interphase(SEI) film(Rf) and charge transfer resistance(Rct) of Si@SnO_(2) @C are 7.68and 0.82 Ω, which are relatively smaller than those of Si@C(21.64 and 2.62 Ω). It is obviously seen that the SnO_(2) shell can reduce the charge transfer resistance, leading to high ion and electron transport efficiency in the Si@SnO_(2) @C electrode. The incorporation of SnO_(2) shell is attributed to the enhanced rate capability and cycling performance of Si@SnO_(2) @C nanocomposite.

关键词： Lithium-ion batteries(LIBs) Silicon Doubleshell structure Nanocomposite Hydrothermal method

Designing electrolytes for lithium metal batteries with rational interface stability

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Rare Metals 2021年第2期40卷 243-245页

作者： Chen-Xuan Xu Jian-jun jiang School of Physics and Electronics Hunan UniversityChangsha410082China

Lithium(Li)-ion batteries(LIBs)have promoted the development of portable electronics and electric vehicles[1,2].However,with the rapid increase in energy demand,it is increasingly urgent to develop batteries with high energy density[3].Li metal batteries(LMBs)are considered as the"Holy Grail"which have attracted much attention due to the high theoretical capacity(3860 mAh·g^(-1))and low redox potential(-3.040 V *** standard hydrogen electrode)[4,5].

关键词： lithium rational interface

Effects of annealing temperature and time on microstructure and magnetic properties of Pr-Co thin films

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Rare Metals 2012年第2期31卷 121-124页

作者： Li, Zhi Ding, hao Zhang, jun Wang, Hanbin Wang, hao Faculty of Physics and Electronic Technology Hubei University Wuhan 430062 China

A series of Pr-Co thin films were deposited on the Si (100) substrates with Cr underlayer by magnetron sputtering. The effects of both the post-annealing temperature and the annealing time on the microstructure and magnetic properties for the Pr-Co films were studied systemati- cally. The as-deposited Pr-Co thin films are mostly amorphous and tend to crystallize after annealing at temperatures above 600 C. When the annealing time is increased, the films show a complicated structure with various phases coexisting. Accordingly, the as-deposited film and low temperature annealed films are soft magnets and films annealed at temperatures beyond 600 C tend to be hard magnets. When the annealing time is increased from 5 min to 2 h, the films transfer from hard magnets to soft again. The sample annealed at 600 C for 10 min shows the largest coercivity of 0.59 T.

关键词： Pr-Co coercivity magnetic recording

Influence of Strut Cross-section of Stents on Local Hemodynamics in Stented Arteries

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Chinese Journal of Mechanical Engineering 2016年第3期29卷 624-632页

作者： jiang Yongfei ZHANG jun Zhao Wanhua State Key Laboratory for Manufacturing System Engineering Xi'an Jiaotong University

Stenting is a very effective treatment for stenotic vascular diseases, but vascular geometries altered by stent implantation may lead to flow disturbances which play an important role in the initiation and progression of restenosis, especially in the near wall in stented arterial regions. So stent designs have become one of the indispensable factors needed to be considered for reducing the flow disturbances. In this paper, the structural designs of strut cross-section are considered as an aspect of stent designs to be studied in details. Six virtual stents with different strut cross-section are designed for deployments in the same ideal arterial model. Computational fluid dynamics（CFD） methods are performed to study how the shape and the aspect ratio（AR） of strut cross-section modified the local hemodynamics in the stented segments. The results indicate that stents with different strut cross-sections have different influence on the hemodynamics. Stents with streamlined cross-sectional struts for circular arc or elliptical arc can significantly enhance wall shear stress（WSS） in the stented segments, and reduce the flow disturbances around stent struts. The performances of stents with streamlined cross-sectional struts are better than that of stents with non-streamlined cross-sectional struts for rectangle. The results also show that stents with a larger AR cross-section are more conductive to improve the blood flow. The present study provides an understanding of the flow physics in the vicinity of stent struts and indicates that the shape and AR of strut cross-section ought to be considered as important factors to minimize flow disturbance in stent designs.

关键词： stent restenosis wall shear stress hemodynamics computational fluid dynamics

Studying the Fermi GeV light curve of Vela with the two-pole caustic model

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Research in Astronomy and Astrophysics 2009年第12期9卷 1324-1330页

作者： Huan Yu jun Fang Ze-jun jiang Department of Physics Yunnan University Kunming 650091 China

An observation of the Vela pulsar with the Fermi Large Area Telescope has been recently reported and the GeV light curve shows two main peaks with a phase separation of ～0.43. We study the GeV light curve using the two-pole caustic model in which the peaks of the light curves of the pulsar result from caustic effects. The results show that the two-pole caustic model can reproduce the observed emission pattern of the two peaks and the bridge emission between them well, but overestimates the flux outside the two peaks. After taking account of the pair production effect on the azimuthal angle, we find that the resulting light curve is more consistent with the observation. We excluded the emissions from the field lines for which the distance from the null charge surface, where the pairs can be significantly produced, is larger than the radius of the light cylinder.

关键词： gamma rays: theory -- pulsars: individual (PSR B0833-45)