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Numerical simulation analysis of tunnel backfill grout based on DEM-FDM coupling and particle inlet

Underground Space 2024年第1期14卷 285-299页

作者： Bin Yan Rui Wang Bo-song Ding Fang dai You Wang School of Civil Engineering Central South University.Changsha 410075China

Shield tunnel backfill grouting is vital to stabilize tunnel settlement at a later stage;however,most shield tunnel backfill grouting designs lack a complete theoretical reference,and numerical simulations of the grouting process are rarely *** study presents the fundamental theories of grout diffusion and pressure variation for backfill grouting during shield ***,the numerical simulation methods coupled with discrete element methods(DEM)and finite difference methods(FDM)are achieved to simulate the process of grout injection from the grouting hole into the shield tail gap and generate grout pressure on the surrounding *** diffusion state of the grout in the shield tail gap and the squeezing effect on the surrounding rock under two shield tail disengagement modes are analyzed,as well as the impact of various grouting pressure on the surface *** results indicated that the grout diffusion in the shield tail gap can be divided into three stages:the stage of diffusion with each grouting hole as the starting point,the stage of interconnection and contact of the grout injected in each grouting hole,and the final gap filling *** of the three stages can be described using the proposed *** the grouting process,the grout is injected into the shield tail gap at a certain pressure,but the grout diffuses slowly to both sides and upwards,which causes a rapid rise of the principal stresses in the soil around the *** grouting is complete,the grout pressure gradually dissipates and stabilizes,and the principal stress *** addition,backfill grouting can reduce surface settlement,but it does not affect its distribution width.

关键词： Shield tunnel Backfill grouting Discrete element Finite difference Particle generator

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Viscoacoustic generalized screen propagator in constant-Q model

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Petroleum Science 2024年第4期21卷 2356-2369页

作者： Zhong-Kui dai Jia-Chun You Xing-Guo Huang Wei Liu College of Geophysics Chengdu University of Technology College of Instrumentation and Electrical Engineering Jilin University

When seismic waves propagate through the geological formation, there is a significant loss of energy and a decrease in imaging resolution, because of the viscoacoustic properties of subsurface medium. This profoundly impacts seismic wavefield propagation, imaging and interpretation. To accurately image the true structure of subsurface medium, the consensus among geophysicists is to no longer treat subsurface medium as ideal homogeneous medium, but rather to incorporate the viscoacoustic properties of subsurface medium. Based on the generalized screen propagator using conventional acoustic wave equation(acoustic GSP), our developed method introduces viscoacoustic compensation strategy, and derives a one-way wave generalized screen propagator based on time-fractional viscoacoustic wave equation(viscoacoustic GSP). In numerical experiments, we conducted tests on two-dimensional multi-layer model and the Marmousi model. When comparing with the acoustic GSP using the acoustic data, we found that the imaging results of the viscoacoustic GSP using the viscoacoustic data showed a significant attenuation compensation effect, and achieved imaging results for both algorithms were essentially consistent. However, the imaging results of acoustic GSP using viscoacoustic data showed significant attenuation effects, especially for deep subsurface imaging. This indicates that we have proposed an effective method to compensate the attenuated seismic wavefield. Our application on a set of real seismic data demonstrated that the imaging performance of our proposed method in local areas surpassed that of the conventional acoustic GSP. This suggests that our proposed method holds practical value and can more accurately image real subsurface structures while enhancing imaging resolution compared with the conventional acoustic GSP. Finally, with respect to computational efficiency, we gathered statistics on running time to compare our proposed method with conventional Q-RTM, and it is evid

关键词： One-way wave equation Viscoacoustic wave equation Generalized screen propagator Attenuation and dispersion effects

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纳米纤维素/木质素抗紫外膜的制备与性能

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高分子材料科学与工程 2022年第12期38卷 93-99页

作者：苏雯皓舒璇董茂林罗丹刘秀宇戴红旗卞辉洋南京林业大学轻工与食品学院江苏南京210037 广西民族大学林产化学与工程国家民委重点实验室广西林产化学与工程重点实验室广西南宁530006

采用顺丁烯二酸预处理杨木木屑提取得到木质素,按照不同含量将其与纳米纤维素机械混合,经抽滤干燥工艺得到了纳米纤维素/木质素复合膜材料。采用扫描电镜、万能拉力机、紫外分光光度计、分光密度计和热重分析仪对材料微观形貌、力学性... 详细信息

采用顺丁烯二酸预处理杨木木屑提取得到木质素,按照不同含量将其与纳米纤维素机械混合,经抽滤干燥工艺得到了纳米纤维素/木质素复合膜材料。采用扫描电镜、万能拉力机、紫外分光光度计、分光密度计和热重分析仪对材料微观形貌、力学性能、光学性能及热稳定性进行测试。结果表明,纯纳米纤维素(CNF)膜表面光滑致密,木质素的添加使复合膜的表面粗糙度从19.8 nm增加到62.7 nm。随着木质素含量的增加,复合膜的拉伸强度从140 MPa降低到67.6MPa。木质素质量分数为5%时,弹性模量最高为7.11 GPa。同时,木质素赋予了材料优异的紫外屏蔽性能,复合膜对UVA和UVB波段的屏蔽率分别为99.23%和100%。此外,木质素的引入提高了复合膜的热稳定性,最高热失重降解温度为313℃。纳米纤维素/木质素复合薄膜在食品包装、紫外线防护和农用地膜等领域显示出很好的应用前景。

关键词：纳米纤维素木质素复合材料膜紫外屏蔽

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Online task planning method of anti-ship missile based on rolling optimization

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Journal of Systems Engineering and Electronics 2024年第3期35卷 720-731页

作者： LU Faxing dai Qiuyang YANG Guang JIA Zhengrong College of Weaponry Engineering Naval University of EngineeringWuhan 430033China

Based on the wave attack task planning method in static complex environment and the rolling optimization framework, an online task planning method in dynamic complex environment based on rolling optimization is proposed. In the process of online task planning in dynamic complex environment,online task planning is based on event triggering including target information update event, new target addition event, target failure event, weapon failure event, etc., and the methods include defense area reanalysis, parameter space update, and mission re-planning. Simulation is conducted for different events and the result shows that the index value of the attack scenario after re-planning is better than that before re-planning and according to the probability distribution of statistical simulation method, the index value distribution after re-planning is obviously in the region of high index value, and the index value gap before and after re-planning is related to the degree of posture change.

关键词： target allocation of anti-ship missile defense area rolling optimization task re-planning

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Remnants and fragments of the subducted paleo-Pacific plate:Constraints from geochemistry and geophysics

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Science China Earth Sciences 2024年第10期67卷 3041-3061页

作者： Xisheng XU Zhouchuan HUANG Dingsheng JIANG Gang ZENG Li-Qun dai State Key Laboratory for Mineral Deposits Research School of Earth Sciences and EngineeringNanjing UniversityNanjing 210023China School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China

The subduction and rollback of the paleo-Pacific plate during Mesozoic time was the key engine for the evolution of the continental margin in eastern China. It led to lateral accretion of continental crust in Northeast China, lithospheric destruction beneath the North China Craton, and the generation of huge volumes of felsic magmatic rocks in South China. This had a profound influence on deep material cycles and the evolution of epigenetic environmental systems along the continental margin of East Asia. To fully understand the transformation of the dynamic mechanism during the subduction and rollback of the paleoPacific plate, we have attempted to trace the remnants and fragments of the subducted paleo-Pacific plate at great depths. Such remnants in both temporal and spatial dimensions can be tracked by using geochemical and geophysical approaches. Studies of the trace elements, Mg-Zn isotopes and Os-Nd-Hf-Pb-O isotopes in continental basalts from eastern China reveal a significant number of the remnants of subduction of the paleo-Pacific plate, and the initial subduction can be traced back to the Early Jurassic. Large-scale geophysical imaging unveils a multitude of high-velocity anomalies in the lower mantle of East ***, many high-velocity bodies, aptly referred to as “slab graveyards”, are nestled at the base of the lower mantle. Numerous isolated high-velocity anomalies are also present in the upper part of the lower mantle, creating conduits for the descent of the subducted slabs into the lower mantle. However, a resolution of the remnants for the subducted slabs within the lower mantle are quite low. Consequently, their impact on the lower mantle's dynamics is yet to be thoroughly investigated. Finally, the presently observed big mantle wedge(BMW) in East Asia has developed through subduction of the Pacific plate in the ***, following the rollback of the paleo-Pacific plate(began at ~145 Ma), a Cretaceous BMW system would also form above

关键词： Paleo-Pacific plate Big mantle wedge Late Mesozoic Remnants and fragments Geochemistry Geophysics

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酸性助水溶剂制备木质纳米纤维素及功能应用研究进展

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化工学报 2023年第6期74卷 2281-2295页

作者：董茂林陈李栋黄六莲吴伟兵戴红旗卞辉洋南京林业大学轻工与食品学院江苏省林业资源高效加工利用协同创新中心江苏南京210037 植物纤维功能材料国家林业和草原局重点实验室福建福州350108

木质纳米纤维素因具有制备工艺简单、环境友好、成本效益高等特点而在各领域受到广泛关注,其制备与应用已成为相关领域的研究热点。然而,木质纤维组分间的聚集结构和复杂的化学键(醚健、酯键等)结合形成了抗解聚屏障,需要对其进行预处... 详细信息

木质纳米纤维素因具有制备工艺简单、环境友好、成本效益高等特点而在各领域受到广泛关注,其制备与应用已成为相关领域的研究热点。然而,木质纤维组分间的聚集结构和复杂的化学键(醚健、酯键等)结合形成了抗解聚屏障,需要对其进行预处理破除屏障。酸性助水溶剂体系具有溶解选择性高、产物易分离、可循环利用等优点,是一种高效环保的绿色预处理工艺,是木质纳米纤维素制备及高值化利用的重要预处理方法。本文首先介绍了酸性助水溶剂的概念及作用机理,综述了酸性助水溶剂体系制备木质纳米纤维素的方法及性能,讨论了木质纳米纤维素的功能化应用进展,最后总结了酸性助水溶剂体系存在的不足,并对其今后的研究方向进行了展望。

关键词：酸性助水溶剂水解生物质木质纳米纤维素纳米材料应用

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Unraveling the mysteries of volatile cycling and habitability on Earth and beyond

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National Science Review 2024年第06期11卷 8-9页

作者： Yi-Gang Xu Ri-Xiang Zhu Min-Han dai State Key Laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences State Key Laboratory of Lithosphere Evolution Institute of Geology and Geophysics Chinese Academy of Sciences State Key Laboratory of Marine Environmental Science Xiamen University

The origin and cycling of volatiles, including water, carbon dioxide, and nitrogen, are fundamental to the very existence of habitable planets. These volatile compounds, often taken for granted,are the lifeblood of planetary systems, influencing almost everything from atmospheric composition and climate regulation to deep Earth processes and the emergence of life.

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Alkaline zinc-based flow battery: chemical stability, morphological evolution, and performance of zinc electrode with ionic liquid

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Frontiers of Materials Science 2024年第1期18卷 113-121页

作者： Tianyong Mao Jing dai Meiqing Xin Deliang Zeng Zhipeng Xie Jiangxi Province Key Laboratory of Power Batteries and Materials Jiangxi University of Science and TechnologyGanzhou 341000China

Zinc-based flow battery is an energy storage technology with good application prospects because of its advantages of abundant raw materials,low cost,and environmental *** chemical stability of zinc electrodes exposed to electrolyte is a very important issue for zinc-based *** paper reports on details of chemical stability of the zinc metal exposed to a series of solutions,as well as the relationship between the morphological evolution of zinc electrodes and their properties in an alkaline *** corrosion of zinc electrodes by the electrolyte will change their surface ***,we observed that chemical corrosion is not the main contributor to the evolution of zinc electrode surface morphology,but the main contributor is the Zn/Zn^(2+)electrode *** morphological evolution of zinc electrodes was controlled by using ionic liquids,1-ethyl-3-methylimidazolium acetate(EMIA),and 1-propylsulfonic-3-methylimidazolium tosylate(PSMIT),and the electrode performance was recorded during the morphological evolution *** was observed that the reversible change of zinc electrode morphology was accompanied by better electrode performance.

关键词： alkaline medium morphological evolution zinc-based flow battery new energy

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Insight of enriched basalts into the nature and evolution of mantle lithosphere beneath craton margins

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Science China Earth Sciences 2024年第10期67卷 3128-3142页

作者： Hong-Kun dai Jianping ZHENG Qing XIONG Linlin HU Xiang ZHOU State Key Laboratory of Geological Processes and Mineral Resources School of Earth SciencesChina University of GeosciencesWuhan 430074China

Refractory lithospheric deep roots are the cornerstone for the prolonged stability of cratons and mantle xenoliths are normally the key targets for study on the evolution of such deep roots. In regions with few mantle xenoliths, the basalts enriched in radiogenic isotopic compositions due to marked lithospheric mantle contribution are crucial to unmask the lithospheric mantle evolution based on a comprehensive study involving petrology, geochemistry and thermodynamic modelling. Here, the Early Cretaceous basalts from the northwest North China Craton with few mantle xenoliths are taken as an example to show the significance of enriched basalts on the study of lithospheric mantle. These basalts are characterized by high silica and alkali contents(SiO_(2)=45.8–59.8 wt.%, K_(2)O+Na_(2)O=4.81–9.88 wt.%), arc-type trace-element patterns and enriched radiogenic isotope compositions(e.g., ε_(Nd)=-2.64–-12.88,^(87)Sr/^(86)Sr=0.7063–0.7093). The TiO_(2) and FeO(total) contents are higher than those of natural and experimental melts from refractory mantle peridotite but comparable to those of partial melts of fertile mantle *** high contents of fluid-loving elements(e.g., Rb and Ba) suggest source metasomatism by aqueous fluids. Combined with thermodynamic modelling and regional tectonic history, these enriched basalts likely record simultaneous decompression melting of asthenosphere and low-extent melting of thin and fertile lithospheric mantle fluxed by aqueous fluids from the subducted Paleo-Asian oceanic slab. The newly unmasked lithospheric mantle under the western NCC contrasts with the coeval thick and refractory one supporting the eastern NCC, and highlights that the craton destruction, especially the loss of its ancient refractory mantle root, should take place in a diachronous manner related to the craton-girded subduction episodes. Our study illustrates the potential of enriched basalts to recover the nature and evolution of mantle lithosphere beneath craton m

关键词： Enriched basalts Lithospheric mantle Northwest North China Craton Tectonic histories Early Cretaceous

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Epicatechin attenuates lead(Pb)-induced cognitive impairment in mice:regulation on Nrf2 signaling pathway,and interference on the interaction between Pb with albumin

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Food Science and Human Wellness 2024年第2期13卷 1065-1078页

作者： dai Cheng Qianqian Yu Kexin Zhu Dingdong Bu Zijian Wu State Key Laboratory of Food Nutrition and Safety Tianjin University of Science&TechnologyTianjin 300457China School of Biotechnology and Food Science Tianjin University of CommerceTianjin 300134China

Epicatechin(EC)was used in this study to antagonize the cognitive dysfunction caused by lead(Pb)exposure in ***-week-old male Kunming mice were treated with PbCl_(2)(20 mg/kg)and/or EC(50 mg/kg)by gavage administration for 4 *** water maze test showed that EC could improve memory dysfunction induced by *** antagonized Ca^(2+)overload,activated Nrf2 signaling pathway and reduced the accumulation of Pb in the brain and serum,which suggested that EC might alter Pb distribution in *** vitro,spectroscopic analysis,potentiometric titration and docking studies were applied to inquiry into the interaction between bovine serum albumin(BSA)and Pb^(2+)in presence or absence of *** was proved to chelate Pb^(2+)and reduced the interaction between BSA and Pb^(2+).In summary,EC might protect Pb-induced cognitive impairment by activating Nrf2 signaling pathway,and suppressing Pb accumulation via interference on the binding of Pb to albumin.

关键词： Lead Epicatechin Bovine serum albumin Interaction Oxidative stress

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