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Investigation on the choice of boundary conditions and shape functions for flexible multi-body system

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Acta Mechanica Sinica 2012年第1期28卷 180-189页

作者： ke-qi pan Jin-Yang Liu School of Naval Architecture Ocean and Civil EngineeringShanghai Jiaotong University200240 ShanghaiChina

The objective of this investigation is to examine the correctness and efficiency of the choice of boundary conditions when using assumed mode approach to simulate flexible multi-body systems. The displacement field due to deformation is approximated by the Rayleigh-Ritz assumed modes in floating frame of reference （FFR） formulation. The deformations obtained by the absolute nodal coordinate （ANC） formulation which are transformed by two sets of reference coordinates are introduced as a criterion to verify the accuracy of the simulation results by using the FFR formulation. The relationship between the deformations obtained from different boundary conditions is revealed. Nu- merical simulation examples demonstrate that the assumed modes with cantilevered-free, simply-supported and free- free boundary conditions without inclusion of rigid body modes are suitable for simulation of flexible multi-body system with large over all motion, and the same physical deformation can be obtained using those mode functions, differ only by a coordinate transformation. It is also shown that when using mode shapes with statically indeterminate boundary conditions, significant error may occur. Furthermore, the slider crank mechanism with rigid crank is accurate enough for investigating boundary condition problem of flexible multi-body system, which cost significant less simulating time.

关键词： Multi-body systems. Boundary conditions - Assumed mode approach

Staged dendrite suppression for high safe and stable lithium-sulfur batteries

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Journal of Energy Chemistry 2025年第1期100卷 674-683页

作者： Jun Jiang Zhenjie Lu Yanwen Ding Shujun Liu Zhijie qi Tian Tang Yunfan Zhang Zhiyuan Ma Jingwen Sun Liang Xue Wenyao Zhang pan Xiong Xin Wang Junwu Zhu Yongsheng Fu key Laboratory for Soft Chemistry and Functional Materials of Ministry of Education Nanjing University of Science and Technology Jiangsu Pylon Battery Co.Ltd

The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur ***,we propose a dual-action strategy to address the lithium dendrite issue in stages by constructing a multifunctional surface-negatively-charged nanodiamond layer with high ductility and robust puncture resistance on polypropylene （PP） *** uniformly loaded compact negative layer can not only significantly enhance electron transmission efficiency and promote uniform lithium deposition,but also reduce the formation of dendrite during early deposition *** importantly,under the strong puncture stress encountered during the deterioration of lithium dendrite growth under limiting current,the high ductility and robust puncture resistance（145.88 MPa） of as-obtained nanodiamond layer can effectively prevent short circuits caused by unavoidable lithium *** Li||Li symmetrical cells assembled with nanodiamond layer modified PP demonstrated a stable cycle of over 1000 h at 2 mA cm-2with a polarization voltage of only 29.3 ***,the negative charged layer serves as a physical barrier blocking lithium polysulfide ions,effectively mitigating capacity *** improved cells achieved a capacity decay of only 0.042%per cycle after 700 cycles at 3 C,demonstrating effective suppression of dendrite growth and capacity attenuation,showing promising prospect.

关键词： Lithium-sulfur batteries Staged dendrite suppression Shuttle effect Surface-negatively-charged nanodiamond

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脊柱结核与脊椎转移瘤的CT形态差异

实用放射学杂志 1998年第8期 24-27页

作者：柯祺许灼新潘锦伟陶辉周守国广东省佛山市中医院ＣＴ室佛山市石湾医院ＣＴ室

目的：探讨脊椎结核与脊椎转移瘤的ＣＴ形态差异。方法：：回顾性分析和比较２７例脊椎结核和２４例脊椎转移瘤的ＣＴ形态表现，拟定出ＣＴ形态差异指标进行鉴别诊断。结果：脊椎结核多发生于椎体前中部、多以多发和弥散形式出现、病灶... 详细信息

目的：探讨脊椎结核与脊椎转移瘤的ＣＴ形态差异。方法：：回顾性分析和比较２７例脊椎结核和２４例脊椎转移瘤的ＣＴ形态表现，拟定出ＣＴ形态差异指标进行鉴别诊断。结果：脊椎结核多发生于椎体前中部、多以多发和弥散形式出现、病灶内可有死骨；脊椎转移瘤多以单发形式出现、多发生于椎体中后部和附件骨、病灶内少有死骨；结核椎旁肿块常有钙化、多无强化或仅周边强化，而转移瘤椎旁肿块少有钙化、强化明显；结核常累及椎间盘，而转移瘤罕有累及椎间盘。结论：上述ＣＴ形态差异指标的应用，有助于两类病变的鉴别诊断

关键词：脊椎结核转移瘤断层摄影术.X线计算机

Recent advances in self-propelled particles

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Science China Chemistry 2017年第10期60卷 1293-1304页

作者： qi pan Yan He Department of Chemistry Tsinghua University Beijing 100084 China

"Active" components can be introduced into a passive system to completely change its physical behavior from its typical behavior at thermodynamic equilibrium. To reveal the interaction mechanisms between individuals, researchers have designed unique self-propelled particles to mimic the collective behavior of biological systems. This review focuses on recent theoretical and experimental advances in the study of self-propelled particle systems and their individual and collective behaviors. The potential applications of active particles in chemical, biological and environmental sensing and single particle imaging are discussed.

关键词： self-propelled particles micromotors collective behavior single particle tracking

收获工况对甘蔗联合收获机关键机构功耗的影响

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农机化研究 2025年第3期47卷 35-40页

作者：冯玉珍潘明章梁科唐永治潘荥春广西大学机械工程学院南宁530004 广西大学亚热带农业生物资源保护与利用国家重点实验室南宁530004 广西柳工农业机械股份有限公司广西柳州545007

为提高甘蔗联合收获机对不同收获天气、不同甘蔗疏密程度,以及不同收获地形的适应性,将甘蔗联合收获机的收获工况分为晴天收获、雨天收获、甘蔗密度较疏收获、甘蔗密度较密收获、上坡收获和下坡收获6种工况,并对其关键机构进行功耗研究... 详细信息

为提高甘蔗联合收获机对不同收获天气、不同甘蔗疏密程度,以及不同收获地形的适应性,将甘蔗联合收获机的收获工况分为晴天收获、雨天收获、甘蔗密度较疏收获、甘蔗密度较密收获、上坡收获和下坡收获6种工况,并对其关键机构进行功耗研究。田间试验结果可为甘蔗联合收获机的动力系统设计和动力分配提供依据。

关键词：甘蔗联合收获机载荷特征功率分配

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Quantum anomalous Hall heterostructures

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National Science Review 2019年第2期6卷 202-204页

作者： ke He qi-Kun Xue State key Laboratory of Low Dimensional Quantum Physics Department of Physics Tsinghua University Beijing Academy of Quantum Information Sciences

The discoveries of the integer and fractional quantum Hall effects in the early 1980s unveiled an exotic world of topological quantum matter [1]. This fascinating world, however, remains largely Platonic in the sense that most of the predicted topological quantum phases are still far away from experimental realization. For a time, almost the only way to find a new topological quantum phase was to search for

关键词： Quantum anomalous Hall heterostructures FMI TME

Enantioselective reductive conjugate alkenylation of α,β-enones with keto alkenyl acetates by nickel catalysis

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Science China Chemistry 2025年第1期 157-162页

作者： Rong-De He Yun-Lei Luo qiu-Quan pan qi-Wei Yao Xing-Zhong Shu State key Laboratory of Applied Organic Chemistry College of Chemistry and Chemical Engineering Lanzhou University

Reactions involving alkenyl acetates offer cost-effective and environmentally friendly routes for alkene synthesis, yet their asymmetric variant remains elusive. Concurrently, asymmetric conjugate alkenylation predominantly centered on nucleophilic addition using alkenyl–M. This manuscript presents an asymmetric reductive conjugate alkenylation reaction involving alkenyl acetates. The method facilitates the enantioselective addition of keto alkenyl groups to α,β-enones, resulting in the formation of unsaturated diketones—a class of useful structural motifs that are challenging to access otherwise. The use of electron-rich Pyroxy ligand is essential for achieving both high reaction efficiency and enantioselectivity.

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Improved crop protection and biodiversity of the agroecosystem by reduced tillage in rice paddy ffelds in southern China

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Journal of Integrative Agriculture 2022年第8期21卷 2345-2356页

作者： LU qi-qi SONG Yuan-feng pan ke-qing LI Yun TANG Ming-xin ZHONG Guo-hua LIU Jie key Laboratory of Crop Integrated Pest Management in South China Ministry of Agriculture and Rural Affairs/Key Laboratory of Natural Pesticide and Chemical BiologyMinistry of Education/South China Agricultural UniversityGuangzhou 510640P.R.China

Agricultural sustainability has benefited from the broad adoption of conservation agriculture(CA)practices for decades,in which the reduction of mechanical disturbances to soil(also known as reduced tillage,RT)is one of the most essential principles for CA *** studies have recommended the advantages of CA practices in the promotion of biodiversity,but the integrated impacts on crop productivity and biodiversity remain *** CA has been applied in rice production in the subtropical area of southern China for several years,the effects of CA,particularly the RT methods,need to be evaluated for the local and long-term *** this study,we established an integrated network to illustrate how the reduction of tillage intensity influenced organisms including invertebrates(such as rice pests and their predators),pathogens and weeds,and then led to an impact on rice *** two-year study demonstrated that major rice pests,such as rice planthoppers,stem borers and apple snails,were effectively controlled by RT ***,the occurrence of common diseases declined with less *** to the conventional tillage(CT)treatment,the density of weeds in paddy fields deceased significantly in the RT *** addition,the diversity and richness of pest predators increased remarkably in paddy fields where either reduced or no tillage was applied,which highlighted the significance of a CA strategy for the promotion of biodiversity in the *** importantly,the rice yield gradually increased after the two-year reduction of *** together,our results suggest that the reduction of tillage intensity is beneficial for the protection of rice crops from various pests,and facilitates the sustainability of the agroecosystem and rice yield,which provides a solid basis and novel insights for the establishment of sustainable agroecosystems by CA-related practices in rice production in southern China.

关键词： conservation agriculture reduced tillage biodiversity pest control sustainable agriculture

General variational solution for seismic and static active earth pressure on rigid walls considering soil tensile strength cut-off

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第5期24卷 432-449页

作者： Shiguo XIAO Yuan qi pan XIA key Laboratory of High-Speed Railway Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 60031China School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Department of Geological Engineering Southwest Jiaotong UniversityChengdu 610031China

According to the limit equilibrium state of soils behind rigid walls and the pseudo-static approach,a general closed-form solution to seismic and static active earth pressure on the walls,which considers shear and tension failure of the retained soil,is put forward using a variational calculus *** application point of the active resultant force specified in the proposed method is explained with a clear physical meaning related to possible movement modes of the *** respect of the derived nine dependent equations reflecting the functional characteristics of the earth pressure,the proposed method can be performed easily via an implicit *** are 13 basic factors related to the retained soils,walls,and external loads to be involved in the proposed *** tension crack segment of the slip surface is obviously influenced by these parameters,apart from vertical seismic coefficient and geometric bounds of the surcharge,but the shear slip segment maintains an approximately planar shape almost uninfluenced by these ***,the proposed method quantitatively reflects that the resultant of the active earth pressure is always within a limited range under different possible movements of the same wall.

关键词： Active earth pressure Tensile strength cut-off Variational calculus method Pseudo-static method Strip surcharge