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Characteristic and optimization of ferrite-rich sulfoaluminate-based composite cement suitable for cold region tunnels

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Journal of Central South University 2024年第8期31卷 2794-2809页

作者： Peng, You Li, Li tan, xian-jun Qiu, Xin Zheng, Pei-chao Xie, jun Chen, Wei-zhong Reziwanguli, Sha-ta-er School of Infrastructure Engineering Dalian University of Technology Dalian China Institute of Rock and Soil Mechanics Chinese Academy of Sciences Wuhan China Xinjiang Academy of Transportation Sciences Co. Ltd. Urumqi China

To develop suitable grouting materials for water conveyance tunnels in cold regions, firstly, this study investigated the performance evolution of ferrite-rich sulfoaluminate-based composite cement (FSAC grouting material) at 20 and 3 °C. The results show that low temperature only delays the strength development of FSAC grouting material within the first 3 d. Then, the effect of four typical early strength synergists on the early properties of FSAC grouting material was evaluated to optimize the early (≤1 d) strength at 3 °C. The most effective synergist, Ca(HCOO)2, which enhances the low-temperature early strength without compromising fluidity was selected based on strength and fluidity tests. Its micro-mechanism was analyzed by XRD, TG, and SEM methods. The results reveal that the most suitable dosage range is 0.3 wt%–0.5 wt%. Proper addition of Ca(HCOO)2 changed the crystal morphology of the hydration products, decreased the pore size and formed more compact hydration products by interlocking and overlapping. However, excessive addition of Ca(HCOO)2 inhibited the hydration reaction, resulting in a simple and loose structure of the hydration products. The research results have reference value for controlling surrounding rock deformation and preventing water and mud inrushes during the excavation in cold region tunnels.

关键词： ferrite-rich sulfoaluminate cement cold zone early strength synergist mechanical property micro-structure pumped storage power

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Evaluation of mountain slope stability considering the impact of geological interfaces using discrete fractures model

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Journal of Mountain Science 2019年第9期16卷 2184-2202页

作者： WANG Lu-yu CHEN Wei-zhong tan Xu-yan tan xian-jun YUAN Jing-qiang LIU Qi State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences Wuhan 430071 China University of Chinese Academy of Science Beijing 100049 China Research Center of Geotechnical and Structural Engineering Shandong University Jinan 250100 China

The stability of rock slope is often controlled by the existing discontinuous surfaces, such as discrete fractures, which are ubiquitously distributing in a geological medium. In contrast with the traditional approaches used in soil slope with a continuous assumption, the simulation methods of jointed rock slope are different from that of in soil slope. This paper presents a study on jointed rock slope stability using the proposed discontinuous approach, which considers the effects of discrete fractures. Comparing with traditional methods to model fractures in an implicit way, the presented approach provides a method to simulate fractures in an explicit way, where grids between rock matrix and fractures are independent. To complete geometric components generation and mesh partition for the model, the corresponding algorithms were devised. To evaluate the stability state of rock slope quantitatively, the strength reduction method was integrated into our analysis framework. A benchmark example was used to verify the validation of the approach. A jointed rock slope, which contains natural fractures, was selected as a case study and was simulated regarding the workflow of our framework. It was set up in the light of the geological condition of the site. Slope stability was evaluated under different loading conditions with various fracture patterns. Numerical results show that fractures have significant contributions to slope stability, and different fracture patterns would lead to different shapes of the slip surface. The devised method has the ability to calculate a non-circular slip surface, which is different from a circular slip surface obtained by classical methods.

关键词： Rock slope stability Discrete fractures Discontinuous approach Equivalent model Slip surface

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Design of the yielding support used highly deformable elements for a tunnel excavated in squeezing rock

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Journal of Mountain Science 2023年第5期20卷 1458-1468页

作者： TIAN Hong-ming TIAN Yun CHEN Wei-zhong tan xian-jun SHU Xiao-yun LIU Xia-lin State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province School of Civil EngineeringShaoxing UniversityShaoxing 312000China College of Civil and Transportation Engineering Hohai UniversityNanjing 210024China China communications second highway survey and design institute Co. Ltd.Wuhan 430058China

Yielding support is often used in the squeezing tunnel to prevent damage to the lining induced by large deformation of the surrounding *** Deformable Elements(HDE)which is often installed along the circumferential direction of the shotcrete lining is a common type of yielding *** determine the yield parameters of HDE,the support characteristic of the lining using HDE and the ground pressure considering strain-softening of soft rock were analyzed by an analytical *** analytical solution showed that when considering the strain-softening of squeezing ground,the ground pressure has a non-zero minimum *** minimum value of ground stress can be used to determine the constant yield stress of the HDE,and the corresponding deformation of the minimum ground pressure can be used to determine the deformation capacity of the *** on the variation in the design constant yield stress and yield displacement of HDE with the in-situ stress and the mechanical parameters of the soft rock,equations were proposed for determining of the yield parameters of the HDE.

关键词： Highly deformable elements Squeezing tunnel Yielding support Strain-softening behavior

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Structural engineering of hard carbon through spark plasma sintering for enhanced sodium-ion storage

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Rare Metals 2024年第9期43卷 4274-4285页

作者： Hao-Ming Xiao Heng Zheng Ping Yuan jun-Hui Luo Lin-Lin Shen Jie-Feng tan xian-You Luo De Li Yong Chen Guangdong Key Laboratory for Hydrogen Energy Technologies School of Materials Science and Hydrogen EnergyFoshan University State Key Laboratory of Marine Resource Utilization in South China Sea Hainan Provincial Key Laboratory of Research on Utilization of Si-Zr-Ti ResourcesHainan University

Hard carbon （HC） has emerged as one of the superior anode materials for sodium-ion batteries （SIBs）,with its electrochemical performance significantly influenced by the presence of oxygen functional groups and its closed pore ***,current research on the structural adjustment of these oxygen functional groups and the closed pore architecture within HC remains ***,energy-efficient and contamination-free spark plasma sintering technology was employed to tune the structure of coconut-shell HC,resulting in significant adjustments to the content of carboxyl （decreasing from 5.71 at%to 2.12 at%） and hydroxyl groups （decreasing from 7.73 at % to 6.26 at%）.Crucially,these modifications reduced the irreversible reaction of oxygen functional groups with Na+.Simultaneously,a substantial number of closed pores with an average diameter of 1.22 nm were generated within the HC,offering an ideal environment for efficient Na+*** structural changes resulted in a remarkable improvement in the electrochemical performance of the modified *** reversible specific capacity of the modified HC surged from 73.89 mAh·g-1to an impressive 251.97 m Ah·g-1at a current density of 50 mA·*** at 400 mA·g-1,the reversible specific capacity increased significantly from 14.55 to 85.44 mAh·***,this study provides a novel perspective for designing tailored HC materials with the potential to develop high-performance SIBs.

关键词： Closed pores Hard carbon Oxygen functional groups Sodium-ion batteries Spark plasma sintering

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Polymer electrolytes for flexible zinc-air batteries:Recent progress and future directions

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Nano Research 2024年第7期17卷 6058-6079页

作者： Jing Wu Wen-Ya Wu Suxi Wang Dan Kai Enyi Ye Warintorn Thitsartarn Janet Beng Hoon tan Jianwei Xu Qingyu Yan Qiang Zhu xian jun Loh Institute of Sustainability for Chemicals Energy and Environment(ISCE2)Agency for ScienceTechnology and Research(A*STAR)1 Pesek RoadJurong IslandSingapore 627833Singapore Institute of Materials Research and Engineering(IMRE) Agency for ScienceTechnology and Research(A*STAR)2 Fusionopolis WayInnovis#08-03Singapore 138634Singapore School of Materials Science and Engineering Nanyang Technological University50 Nanyang AvenueSingapore 639798Singapore School of Chemistry Chemical Engineering and BiotechnologyNanyang Technological University21 Nanyang LinkSingapore 637371Singapore Department of Material Science and Engineering National University of Singapore9 Engineering Drive 1#03-09 EASingapore 117575Singapore

This review article delves into the development of electrolytes for flexible zinc-air batteries(FZABs),a critical component driving the advancement of flexible *** started by surveying the current advancements in electrolyte technologies,including solid-state and gel-based types,and their contributions to enhance the flexibility,efficiency,and durability of ***,we explored the challenges in this domain,focusing on maintaining electrolyte stability under mechanical stress,ensuring compatibility with flexible substrates,optimizing ion conductivity,and under harsh environmental ***,the key issues regarding interface details between electrolyte and the electrodes are covered as *** then discussed the future of electrolyte development in FZABs,highlighting potential avenues such as materials development,sustainability,in-situ studies,and battery *** review offers an in-depth overview of the advancements,challenges,and potential breakthroughs in creating electrolytes for FZABs over the past five *** serves as a guide for both researchers and industry professionals in this dynamic area.

关键词： flexible zinc-air batteries electrolyte polymer hydrogel electrolyte-electrode interface

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Highly Improved Creep Resistance in Polypropylene Through Thermally Reduced Graphene Oxide and Its Creep Lifetime Prediction

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Chinese Journal of Polymer Science 2024年第2期42卷 256-266,I0010页

作者： Can-Can Zhang jun-Long Yang Ya-Jiang Huang Guang-xian Li College of Polymer Science and Engineering State Key Laboratory of Polymer Materials Engineering of ChinaSichuan UniversityChengdu610065China

Polypropylene(PP) exhibits suboptimal creep resistance due to the presence of methyl groups on its main chain, leading to irregular chain segment distribution, diminished inter-chain interaction, and crystallinity. This structural feature causes chain slippage in PP under stress,significantly constraining its service lifetime. In this study, thermally reduced graphene oxide(TrGO) nanosheets were incorporated into the PP matrix, yielding a nanocomposite with exceptional creep resistance performance. Results demonstrated that at a stress of 25 MPa, a 2.0 wt% TrGO content could enhance the creep failure lifetime of PP by 21.5 times compared to neat PP. Rheology, transmission electron microscopy(TEM),and scanning electron microscopy(SEM) characterization techniques were employed to analyze the mechanism of TrGO's influence on PP's creep behavior. It was observed that when TrGO content exceeded 1.0 wt%, an effective particle network structure formed within the PP matrix. This homogeneously dispersed TrGO-formed particle network structure restricted the migration and rearrangement of PP molecular chains, enabling prolonged stress resistance without structural failure. By combining the time-strain superposition method with the critical failure strain as a criterion, generalized creep compliance curves for PP and its composites were established, facilitating the prediction of material creep failure lifetimes, with a strong agreement between experimental and predicted lifetime values. This research proposes a novel strategy aimed at developing polypropylene materials and products with enhanced long-term stability and durability, thus extending service life, reducing failure risk, and broadening their potential across various application domains.

关键词： Thermally reduced graphene oxide Polypropylene Creep failure and lifetime prediction

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Risk assessment of oil and gas investment environment in countries along the Belt and Road Initiative

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Petroleum Science 2024年第2期21卷 1429-1443页

作者： Bao-jun tang Chang-Jing Ji Yu-xian Zheng Kang-Ning Liu Yi-Fei Ma jun-Yu Chen Center for Energy and Environmental Policy Research Beijing Institute of TechnologyBeijing100081China School of Management and Economics Beijing Institute of TechnologyBeijing100081China Collaborative Innovation Center of Electric Vehicles in Beijing BeijingChina Sustainable Development Research Institute for Economy and Society of Beijing BeijingChina Institute of Carbon Neutrality ShanghaiTech UniversityShanghai201210China

With the implementation of the Belt and Road Initiative, China is deepening its cooperation in oil and gas resources with countries along the Initiative. In order to better mitigate risks and enhance the safety of investments, it is of significant importance to research the oil and gas investment environment in these countries for China's overseas investment macro-layout. This paper proposes an indicator system including 27 indicators from 6 dimensions. On this basis, game theory models combined with global entropy method and analytic hierarchy process are applied to determine the combined weights, and the TOPSIS-GRA model is utilized to assess the risks of oil and gas investment in 76 countries along the Initiative from 2014 to 2021. Finally, the GM(1,1) model is employed to predict risk values for 2022-2025. In conclusion, oil and gas resources and political factors have the greatest impact on investment environment risk, and 12 countries with greater investment potential are selected through cluster analysis in conjunction with the predicted results. The research findings may provide scientific decisionmaking recommendations for the Chinese government and oil enterprises to strengthen oil and gas investment cooperation with countries along the Belt and Road Initiative.

关键词： Belt and Road Initiative Oil and Gas Investment Risk assessment

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A 27 GHz,simple 2-bit 1×8 phased array

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Journal of Electronic Science and Technology 2024年第3期22卷 26-34页

作者： jun-xian Liu Yun-Ying Man Hao Yang Peng Yang School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu611731China

This study demonstrates a simple 2-bit phased array operating at 27 GHz that supports one-dimensional beam scanning with left-handed circular polarization(LHCP).The antenna is constructed using a compact four-layer printed circuit board(PCB)structure,consisting of a 90°phase shifter layer with microstrip structures,a ground(GND)layer,a direct current(DC)control layer,and a circularly polarized annular radiation patch layer with 1-bit phase *** on the proposed unit structure,a 1×8 array with half-wavelength inter-element spacing was designed and *** results show that the array achieves a peak gain of 10.23 dBi and is capable of beam scanning within±50°.

关键词： 27 GHz 2-bit P-i-n diodes Phased array Reconfigurable antennas

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FPGA-based position reconstruction method for neutron beam flux spatial distribution measurement in BNCT

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Nuclear Science and Techniques 2024年第3期35卷 96-108页

作者： Wei Jiang Ping Cao Yi-Ming Wu xian-Ke Liu Zhu-jun Fang Zhi-Yong Zhang Bin Shi jun Chen State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China Department of Modern Physics University of Science and Technology of ChinaHefei 230026China School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026China National Key Laboratory for Metrology and Calibration Techniques China Institute of Atomic EnergyBeijing 102413China

A new measurement method for the spatial distribution of neutron beam flux in boron neutron capture therapy(BNCT)is being developed based on the two-dimensional Micromegas *** address the issue of long processing times in traditional offline position reconstruction methods,this paper proposes a field programmable gate array based online position reconstruction method utilizing the micro-time projection chamber *** method encapsulates key technical aspects:a self-adaptive serial link technique built upon the dynamical adjustment of the delay chain length,fast sorting,a coordinate-matching technique based on the mapping between signal timestamps and random access memory(RAM)addresses,and a precise start point-merging technique utilizing a circular combined *** performance test of the selfadaptive serial link shows that the bit error rate of the link is better than 10-12 at a confidence level of 99%,ensuring reliable data *** experiment utilizing the readout electronics and Micromegas detector shows a spatial resolution of approximately 1.4 mm,surpassing the current method’s resolution level of 5 *** beam experiment confirms that the readout electronics system can obtain the flux spatial distribution of neutron beams online,thus validating the feasibility of the position reconstruction *** online position reconstruction method avoids traditional methods,such as bubble sorting and traversal searching,simplifies the design of the logic firmware,and reduces the time complexity from O(n2)to O(n).This study contributes to the advancement in measuring neutron beam flux for BNCT.

关键词： Position reconstruction FPGA Readout electronics Neutron flux spatial distribution

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Recent advances in vacancy engineering for reliable lithiumsulfur batteries

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Rare Metals 2024年第2期43卷 455-477页

作者： Wen-Dong Liu Xiao tang jun-An Feng Chao-Yue Zhang Hao Liu Chuan Shi Xiao-xian Zhao Jian-jun Song College of Physics School of Chemistry and Chemical EngineeringQingdao UniversityQingdao266071China Faculty of Science Centre for Clean Energy TechnologySchool of Mathematical and Physical SciencesUniversity of Technology SydneySydneyNSW2007Australia Department of Chemistry College of ScienceHebei Agricultural UniversityBaoding071001China

The high-energy-density and low-cost features endow lithium-sulfur batteries with broad application ***,many drawbacks,especially the detrimental shuttle effect,have hindered the further development of *** response,a lot of new structures have been applied to suppress the shuttle effect and promote the development of ***,vacancy engineering has gained the attention of researchers due to its unique electronic *** review aims to analyze the application of vacancy engineering in ***,the electrochemistry of LSBs has been systematically discussed and the existing challenges as well as improvement tactics of LSBs have also been ***,the preparation methods and characterization technologies of various vacancies are summarized,including oxygen vacancies,sulfur vacancies,selenium vacancies,other anion vacancies,cation vacancies,*** latest applications of vacancy engineering in LSBs are also summarized in this ***,some prospects and insights for further investigation and practical application of vacancy engineering in LSBs are put forward.

关键词： Lithium-sulfur batteries(LSBs) Defects Vacancy engineering Electronic structure Shuttle effect

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