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A METHOD OF PREPARING SPHERICAL NANO-CRYSTAL CELLULOSE WITH MIXED CRYSTALLINE FORMS OF CELLULOSE Ⅰ AND Ⅱ 被引量:12
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作者 Xiao-fang Li En-yong Ding +1 位作者 Guo-kang Li Laboratory of Cellulose and Lignocellulosics Chemistry, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650 China College of Material Science and Engineering South China University of Technology, Guangzhou 510641, China 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2001年第3期291-296,共6页
A new kind of nano-crysta cellulose (NCC) prepared from natural cotton fiber has been obtained by the method ofacid hydrolysis. Compared to most other nanophase materials that derive from inorganic materials, our prod... A new kind of nano-crysta cellulose (NCC) prepared from natural cotton fiber has been obtained by the method ofacid hydrolysis. Compared to most other nanophase materials that derive from inorganic materials, our products are preparedfrom natural cotton fibers. The products are of spherical shape with mixed crystal forms of cellulose I and II. The preparationconditions determine the properties of the products. Prior treatment is a critical procedure. The properties of the products arealso strongly affected by such conditions as the kinds of acids used, the ratio of the acid mixture, the acid concentration, theultrasonic agitation time and hydrolysis temperature. The number average molecular weight of NCC is determined by gelpermeation chromatography (GPC). The particle size and shape were determined by transmission electron microscopy(TEM). X-ray diffraction was used to detect the crystallinity and average crystallite size of the panicle. 展开更多
关键词 Spherical nano-crystal cellulose mixed crystal forms of cellulose and Ultrasonic agitation
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MECHANISM ANALYSIS OF THICKNESS EFFECT ON MIXED MODE Ⅰ/Ⅱ FRACTURE OF LC4-CS ALUMINUM ALLOY 被引量:2
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作者 H.R. Dong W.L. Guo 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2004年第3期255-262,共8页
Mixed mode Ⅰ/Ⅱ fracture erperiments of LC4-CS aluminum alloy were conductedby using tension--shear specimens with thicknesses of 2, 4, 8 and 14mm. Fracturemechanisms of thickness effect on mixed mode Ⅰ/Ⅱ fracture ... Mixed mode Ⅰ/Ⅱ fracture erperiments of LC4-CS aluminum alloy were conductedby using tension--shear specimens with thicknesses of 2, 4, 8 and 14mm. Fracturemechanisms of thickness effect on mixed mode Ⅰ/Ⅱ fracture were first examined fromfracture surface morphology to correlate with the macroscopic fracture behavior andstress state. It is found that specimen thickness has a strong influence on mixed modefracture. As thickness varies from thin to thick the macroscopic fracture surfacesappear the characteristics of plane stress state (2mm, 4mm--thick specimen), three--dimensional stress state (8mm--thick specimens), and plane strain state (14mm--thickspecimens), respectively. The specimens of all kinds of thicknesses are typical of ten-sile type failure under mode Ⅰ loading condition and shear type failure under mode Ⅱloading condition. Two distinct features coexist on the fracture surfaces under mixedmode loading conditions, and the corresponding proportion varies with loading mix-ity. Void--growth processes are the failure mechanism in both predominately tensile-and shears--type fractures. The size and depth of dimples on the fracture surface varygreatly with thickness. Therefore, it is extraordinary necessary to take into accountthe thickness effect when a mixed mode fracture criterion is being established. 展开更多
关键词 LC4-CS aluminum alloy mixed mode /Ⅱ fracture thickness effect macroscopic fracture appearance SEM
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A-site phase segregation in mixed cation perovskite 被引量:1
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作者 Lang Liu Jiuzhou Lu +4 位作者 Hao Wang Zhenhua Cui Giacomo Giorgi Yang Bai Qi Chen 《Materials Reports(Energy)》 2021年第4期3-21,共19页
Mixed cation strategy greatly benefits the enhancement of device performance and chemical stability.However,adverse impact also accompanies the mixed cation system simultaneously.It brings the compositional instabilit... Mixed cation strategy greatly benefits the enhancement of device performance and chemical stability.However,adverse impact also accompanies the mixed cation system simultaneously.It brings the compositional instability,wherein the homogeneous film is likely to segregate into multi-phases during the fabrication and ageing process,thus resulting in the efficiency reduction of perovskite solar cells(PSCs)devices.This review focuses on the cation induced phase segregation,and elucidates the segregation mechanisms from the perspectives of film formation and ageing process,respectively.Furthermore,the influence of cation segregation on device performance and operational stability are discussed.And based on these understandings,viable strategies are proposed for the design of phase-stable mixed composition halide perovskites and for suppressing segregation to benefit its development towards commercial applications. 展开更多
关键词 PHOTOVOLTAIC PEROVSKITE mixed cation Phase segregation STABILITY
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(Ⅰ+Ⅱ)MIXED MODE HYDROGEN INDUCED CRACKING
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作者 GAO Hua XUE Lijue Shanghai University of Engineering Science,Shanghai,China Associate Professor,Dept.of Materials,Shanghai University of Engineering Science,350 Xianxia Road,Shanghai,China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1989年第4期279-283,共5页
Hydrogen induced cracking(HIC)of 0.3% C,1% Cr,1% Mn,1% Si high strength steel has been studied under simple mode Ⅰ,mode Ⅱ and(Ⅰ+Ⅱ)mixed mode loading conditions.Af- ter being hydrogen-charged in IN H_2SO_4 solution... Hydrogen induced cracking(HIC)of 0.3% C,1% Cr,1% Mn,1% Si high strength steel has been studied under simple mode Ⅰ,mode Ⅱ and(Ⅰ+Ⅱ)mixed mode loading conditions.Af- ter being hydrogen-charged in IN H_2SO_4 solution,the material behaved hydrogen embrittlement in all the cases studied.The threshold K_(ⅡH)/K_(ⅡX) of HIC under mode Ⅱ load- ing was 0.27,which was nearly the same as that K(ⅠH)/K_(ⅠX)=0.29 under mode Ⅰ loading. While the thresholds of-HIC under(Ⅰ+Ⅱ)mixed mode loading were 0.36,0.41 and 0.37 cor- responding to the K_Ⅱ/K_Ⅰ ratio of 0.27,0.4 and O.81.The results show that simple mode Ⅰ or mode Ⅱ loading is more susceptible to hydrogen embrittlement than(Ⅰ+Ⅱ)mixed mode. For explaining the experimental results,the effects of triaxial stress as well as plastic deformation ahead of crack tip has been discussed. 展开更多
关键词 (+Ⅱ)mixed mode hydrogen induced cracking
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Understanding the precursor chemistry for one-step deposition of mixed cation perovskite solar cells by methylamine route
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作者 Manuel Vásquez-Montoya Juan F.Montoya +1 位作者 Daniel Ramirez Franklin Jaramillo 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2021年第6期386-391,I0010,共7页
Upscaling perovskite solar cell fabrication is one of the key challenges in the pathway for commercialization.The slow evaporation of frequently used solvents(DMF or DMSO) limits the fast perovskite layer crystallizat... Upscaling perovskite solar cell fabrication is one of the key challenges in the pathway for commercialization.The slow evaporation of frequently used solvents(DMF or DMSO) limits the fast perovskite layer crystallization,hindering their implementation in large scale deposition methods.Alternatively,methylamine-based precursors have demonstrated rapid crystallization,leading to uniform and specular films.Nonetheless,their application has been limited to MAPbI3 perovskites with limited efficiency and stability.In this work,we report the requirements for stabilizing α-phase of mixed cation perovskites with high amount of formamidinium by using a methylamine-based precursor.We found that even though,there are many methods for incorporating the methylamine(MA) in precursors or films;the MA content determines stabilization of the α-phase and therefore the viscous-solution route is the only method to incorporate high amounts of MA.At low amounts of MA,perovskite tend to crystallize in 1D dimensional FA_(3)(MA)PbI5 phases due to the incomplete solvation of the PbI6-clusters.In contrast,high MA ratio induces a full solvation of the clusters,leading to a rapid crystallization and a full stabilization of the active 3D α-phase.These results open a window in the development and understanding of new precursors for the fabrication of high efficient,stable and scalable perovskite devices. 展开更多
关键词 METHYLAMINE Stabilizingα-phase mixed cation perovskite precursor Formamidinium Upscaling Perovskite Solar cells
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Raman Micro-Imaging of the Coexistence of sⅠ and sⅡ Hydrates Formed from a Mixed Methane-Propane Gas in a Confined Space
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作者 CAI Wenjiu ZHAN Linsen +1 位作者 HUANG Xin LU Hailong 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2022年第2期674-679,共6页
Natural gas hydrate contains a specific amount of heavy hydrocarbons, such as ethane, propane, etc., aside from the primary guest gas of methane. Although the coexistence of two or even three hydrate structures has be... Natural gas hydrate contains a specific amount of heavy hydrocarbons, such as ethane, propane, etc., aside from the primary guest gas of methane. Although the coexistence of two or even three hydrate structures has been discovered at several hydrate sites, the requisite formation mechanism is still not well understood. In-situ observation of the formation process of mixed methane-propane hydrate in a confined space was conducted using confocal Raman imaging microscopy. The Raman imaging results reveal that sI methane hydrate and sII mixed methane-propane hydrate are formed and coexist in the reaction system. In the confined space, the sI hydrate originates from the dissolved gas in water, while the sII hydrate is formed from free gas. The results obtained can help explain the coexistence of sI and sII hydrates found in natural hydrate samples, as well as providing insights into a possible dynamic scenario of hydrate reservoirs in geological history. 展开更多
关键词 Raman imaging mixed hydrate COEXISTENCE shydrate sⅡhydrate
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A mixed-cation lead iodide MA_(1-x)EA_xPbI_3 absorber for perovskite solar cells
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作者 Yong Wang Taiyang Zhang +5 位作者 Ge Li Feng Xu Tian Wang Yihui Li Yang Yang Yixin Zhao 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2018年第1期215-218,共4页
The mixed-cation lead halide perovskites have emerged as a new class of promising light harvesting materials for solar cells. The formamidinium(FA), methylammonium(MA) and Cs cations are widely studied in the fiel... The mixed-cation lead halide perovskites have emerged as a new class of promising light harvesting materials for solar cells. The formamidinium(FA), methylammonium(MA) and Cs cations are widely studied in the field of mixed-cation perovskites. Here, we have investigated ethylammonium(EA) as an alternative cation to fabricate a mixed-cation perovskite of MA_(1-x)EA_xPbI_3. We have characterized the materials using the X-ray diffraction(XRD), scanning electron microscope(SEM), and UV–vis spectrum. Our results have confirmed the successful incorporation of EA cations into MAPbI_3. Interestingly, the optimal amount of EA to achieve the best performance is quite low. This is different from the FA–MA mixed-cation perovskites although EA and FA have similar radii. In short, the EA–MA mixed-cation perovskite has some material and device properties highly distinguishable from the FA–MA one. 展开更多
关键词 mixed cation Ethylammonium MA1-xEAxPbl3 Perovskite solar cell
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Halogen Mediated Self-assembly of Three Mixed Valent Cu(Ⅰ)/Cu(Ⅱ)Complexes
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作者 崔红霞 于楚男 +3 位作者 陈艳红 蒋秀燕 高丽 刘焕荣 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2016年第1期150-156,共7页
Reaction of the ligand dmpt(dmpt=6,7-dimethylbenzo[f][1,10]phenanthroline)with CuCl2 afforded mixed valent Cu(Ⅰ)/Cu(Ⅱ) discrete tetranuclear complexes[Cu(Ⅱ)Cl2(dmpt)Cu(Ⅰ)Cl](1),while the reaction of ... Reaction of the ligand dmpt(dmpt=6,7-dimethylbenzo[f][1,10]phenanthroline)with CuCl2 afforded mixed valent Cu(Ⅰ)/Cu(Ⅱ) discrete tetranuclear complexes[Cu(Ⅱ)Cl2(dmpt)Cu(Ⅰ)Cl](1),while the reaction of ligand dppz(dppz = dipyrido[3,2-a:20,30-c]phenazine) with divalent halogen copper salt CuX2(X=Cl,Br) gave one-dimensional chain mixed valent Cu(Ⅰ)/Cu(Ⅱ) complexes [Cu(Ⅱ)Cl2(dppz)Cu(Ⅰ)Cl]n(2) and discrete mixed valent Cu(Ⅰ)/Cu(Ⅱ)complexes [Cu(Ⅱ)Br2(dppz)(DMF)Cu(Ⅰ)Br](3). Complex 2 consists of a one-dimensional chain-dppzC u(Ⅱ)-Clμ2-Cu(Ⅰ)-Cl-dppzC u(Ⅱ)-Clμ2-Cu(Ⅰ)-with Cu(Ⅱ) and Cu(Ⅰ) atoms linked together by chloride anion. Complex 3 is a discrete complex,which is the same as complexes 1 and 2 involving two different copper valent Cu(Ⅰ) and Cu(Ⅱ). The Cu(Ⅰ) ion presents a pseudo-trihedral geometry,while the Cu(Ⅱ) ion presents a slightly distorted square-pyramidal geometry. This fact proved that halogen ions play a vital role in the assembly procedure. Our research results demonstrate the structural diversification that can be achieved by halogen ions mediated. Moreover,halogen ions-mediated self-assembly may provide useful information for further design of compounds with novel structures and properties. 展开更多
关键词 anion of halogen mediated self-assembly mixed valence Cu()/Cu(Ⅱ) complexes
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Studies on A Novel Mixed-Valence Complex of Copper(Ⅰ,Ⅱ)α-Methacrylate with Imidazole and Aqua
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作者 Yao Yu WANG Xin WANG +2 位作者 Qian SHI Qi Zhen SHI Yi Ci GAO(Department of Chemistry, Northwest University, Xian, 710069)(Department of Chemistry, Lanzhou University, Lanzhou. 730000) 《Chinese Chemical Letters》 SCIE CAS CSCD 1999年第2期187-188,共2页
A novel mixed-valence copper (Ⅰ,Ⅱ) complex Cu3 [CH2=C(CH3) COO]5 (imH)3 (H2O)has been synthesized and characterized by XPS spectra and single crystal X-ray structural analysis.The title complex crystallized in monoc... A novel mixed-valence copper (Ⅰ,Ⅱ) complex Cu3 [CH2=C(CH3) COO]5 (imH)3 (H2O)has been synthesized and characterized by XPS spectra and single crystal X-ray structural analysis.The title complex crystallized in monoclinic space group P21/c, with α=11 .225 (3), b=13.9023 (12),c=24.559 (2), β=92.372 (10)°and Z=4. Final R=0.0495 for 5546 reflections [I>2σ (Ⅰ)]. 展开更多
关键词 mixed-valence copper ( Ⅱ) complex synthesis crystal structure
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浅析OBE理念下的《汽车构造Ⅰ》一流课程建设
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作者 金标 王书海 +1 位作者 费强 江深 《时代汽车》 2024年第8期105-107,共3页
为体现以学生为中心、产出导向和持续改进教育理念以及课程的高阶性、创新性以及挑战度,文章以《汽车构造Ⅰ》课程为例,按照线上线下混合式一流课程的建设标准,遵循OBE理念,加强课程总体设计,融入课程思政元素,整合优化教学内容,设计“A... 为体现以学生为中心、产出导向和持续改进教育理念以及课程的高阶性、创新性以及挑战度,文章以《汽车构造Ⅰ》课程为例,按照线上线下混合式一流课程的建设标准,遵循OBE理念,加强课程总体设计,融入课程思政元素,整合优化教学内容,设计“AEEA”的三阶线上线下混合式教学模式,开展多种教学方法的应用,建立过程化、多元化、混合式的课程考核评价体系,以期为高校专任教师开展一流课程建设与实施应用提供思路。 展开更多
关键词 OBE理念 线上线下混合式教学 AEEA教学模式 汽车构造
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Addressing cation mixing in layered structured cathodes for lithium-ion batteries:A critical review 被引量:3
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作者 Jingxi Li Gemeng Liang +4 位作者 Wei Zheng Shilin Zhang Kenneth Davey Wei Kong Pang Zaiping Guo 《Nano Materials Science》 EI CAS CSCD 2023年第4期404-420,共17页
High-performance lithium-ion batteries(LIB)are important in powering emerging technologies.Cathodes are regarded as the bottleneck of increasing battery energy density,among which layered oxides are the most promising... High-performance lithium-ion batteries(LIB)are important in powering emerging technologies.Cathodes are regarded as the bottleneck of increasing battery energy density,among which layered oxides are the most promising candidates for LIB.However,a limitation with layered oxides cathodes is the transition metal and Li site mixing,which significantly impacts battery capacity and cycling stability.Despite recent research on Li/Ni mixing,there is a lack of comprehensive understanding of the origin of cation mixing between the transition metal and Li;therefore,practical means to address it.Here,a critical review of cation mixing in layered cathodes has been provided,emphasising the understanding of cation mixing mechanisms and their impact on cathode material design.We list and compare advanced characterisation techniques to detect cation mixing in the material structure;examine methods to regulate the degree of cation mixing in layered oxides to boost battery capacity and cycling performance,and critically assess how these can be applied practically.An appraisal of future research directions,including superexchange interaction to stabilise structures and boost capacity retention has also been concluded.Findings will be of immediate benefit in the design of layered cathodes for high-performance rechargeable LIB and,therefore,of interest to researchers and manufacturers. 展开更多
关键词 cation mixing Layered oxide cathodes Lithium-ion batteries Electrochemical performance
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A MIXED MODE FRACTURE CRITERION BASED ON THE MAXIMUM TANGENTIAL STRESS IN BRITTLE INCLUSION 被引量:2
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作者 Ji Changjiang Li Zhonghua Sun Jun 《Acta Mechanica Solida Sinica》 SCIE EI 2005年第3期225-233,共9页
A closed-form solution for predicting the tangential stress of an inclusion located in mixed mode Ⅰ and Ⅱ crack tip field was developed based on the Eshelby equivalent inclusion theory. Then a mixed mode fracture cr... A closed-form solution for predicting the tangential stress of an inclusion located in mixed mode Ⅰ and Ⅱ crack tip field was developed based on the Eshelby equivalent inclusion theory. Then a mixed mode fracture criterion, including the fracture direction and the critical load, was established based on the maximum tangential stress in the inclusion for brittle inclusioninduced fracture materials. The proposed fracture criterion is a function of the inclusion fracture stress, its size and volume fraction, as well as the elastic constants of the inclusion and the matrix material. The present criterion will reduce to the conventional one as the inclusion having the same elastic behavior as the matrix material. The proposed solutions are in good agreement with detailed finite element analysis and measurement. 展开更多
关键词 mixed mode and crack fracture toughness INCLUSION Eshelby inclusion theory
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A novel model to evaluate spatial structure in thinned conifer-broadleaved mixed natural forests 被引量:1
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作者 Hui Liu Xibin Dong +3 位作者 Yuan Meng Tong Gao Liangliang Mao Ran Gao 《Journal of Forestry Research》 SCIE CAS CSCD 2023年第6期1881-1898,共18页
In order to ensure the effective analysis and reconstruction of forests,it is key to ensure the quantitative description of their spatial structure.In this paper,a distance model for the optimal stand spatial structur... In order to ensure the effective analysis and reconstruction of forests,it is key to ensure the quantitative description of their spatial structure.In this paper,a distance model for the optimal stand spatial structure based on weighted Voronoi diagrams is proposed.In particular,we provide a novel methodological model for the comprehensive evaluation of the spatial structure of forest stands in natural mixed conifer-broadleaved forests and the formulation of management decision plans.The applicability of the rank evaluation and the optimal solution distance model are compared and assessed for different standard sample plots of natural mixed conifer-broadleaved forests.The effect of crown width on the spatial structure unit of the trees is observed to be higher than that of the diameter at breast height.Moreover,the influence of crown length is greater than that of tree height.There are nine possible spatial structure units determined by the weighted Voronoi diagram for the number of neighboring trees in the central tree,with an average intersection of neighboring crowns reaching 80%.The rank rating of natural forest sample plots is correlated with the optimal solution distance model,and their results are generally consistent for natural forests.However,the rank rating is not able to provide a quantitative assessment.The optimal solution distance model is observed to be more comprehensive than traditional methods for the evaluation of the spatial structure of forest stands.It can effectively reflect the trends in realistic stand spatial structure factors close to or far from the ideal structure point,and accurately assesses the forest spatial structure.The proposed optimal solution distance model improves the integrated evaluation of the spatial structure of forest stands and provides solid theoretical and technical support for sustainable forest management. 展开更多
关键词 Weighted Voronoi diagram Optimal distance model Spatial structure quantifi cation Thinning intensity Conifer-broadleaved mixed natural forests
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Cation mixing (Li_(0.5)Fe_(0.5))_2SO_4F cathode material for lithium-ion batteries
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作者 孙洋 刘磊 +2 位作者 董金平 张斌 黄学杰 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第12期1-7,共7页
We study the crystal structure of a triplite-structured (Li0.5Fe0.5)SO4F with full Li+/Fe2+ mixing. This promising polyanion cathode material for lithium-ion batteries operates at 3.9 V versus Li+/Li with a theor... We study the crystal structure of a triplite-structured (Li0.5Fe0.5)SO4F with full Li+/Fe2+ mixing. This promising polyanion cathode material for lithium-ion batteries operates at 3.9 V versus Li+/Li with a theoretical capacity of 151 mAh/g. Its unique cation mixing structure does not block the Li+ diffusion and results in a small lattice volume change during the charge/discharge process. The calculations show that it has a three-dimensional network for Li-ion migration with an activation energy ranging from 0.53 eV to 0.68 eV, which is comparable with that in LiFePO4 with only one-dimensional channels. This work suggests that further exploring cathode materials with full cation mixing for Li-ion batteries will be valuable. 展开更多
关键词 lithium-ion battery cathode material triplite cation mixing
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混凝土Ⅰ-Ⅱ复合型裂缝扩展准则及扩展全过程的数值模拟 被引量:17
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作者 吴智敏 董伟 许青 《水利学报》 EI CSCD 北大核心 2009年第2期180-187,共8页
本文基于从试验中得出的混凝土Ⅰ-Ⅱ复合型裂缝起裂时的临界KⅠ-KⅡ曲线,提出了Ⅰ-Ⅱ复合型裂缝的扩展准则,即由外荷载在裂缝尖端产生的应力强度因子与虚拟裂缝黏聚力产生的应力强度因子的差大于或等于起裂时的临界KⅠ-KⅡ曲线时裂缝扩... 本文基于从试验中得出的混凝土Ⅰ-Ⅱ复合型裂缝起裂时的临界KⅠ-KⅡ曲线,提出了Ⅰ-Ⅱ复合型裂缝的扩展准则,即由外荷载在裂缝尖端产生的应力强度因子与虚拟裂缝黏聚力产生的应力强度因子的差大于或等于起裂时的临界KⅠ-KⅡ曲线时裂缝扩展,在此基础上采用有限元法对混凝土Ⅰ-Ⅱ复合型裂缝的起裂、稳定扩展及失稳扩展全过程进行了数值模拟,并计算了试件高度分别为2003、00、400、5006、00mm混凝土四点剪切梁的裂缝扩展路径、荷载-剪切位移曲线,数值模拟结果与试验结果吻合良好。研究表明,只要从试验中测得混凝土材料的Ⅰ-Ⅱ复合型裂缝起裂时的临界KⅠ-KⅡ曲线、抗拉强度及弹性模量,即可计算混凝土Ⅰ-Ⅱ复合型裂缝扩展全过程。 展开更多
关键词 混凝土 -Ⅱ复合型裂缝 有限元 扩展准则 数值模拟
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类岩石脆性材料非闭合裂纹的Ⅰ–Ⅱ压剪复合型断裂准则研究 被引量:12
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作者 李部 黄润秋 吴礼舟 《岩土工程学报》 EI CAS CSCD 北大核心 2017年第4期662-668,共7页
实际工程中,结构体裂纹常处于拉剪和压剪复合受力状态,研究适合于复合型裂纹的断裂准则和裂纹扩展机理具有重要的理论意义和实用价值。以Ⅰ-Ⅱ复合型裂纹为研究对象,基于线弹性理论,在考虑裂纹几何特征及受力形式的基础上,系统介绍了裂... 实际工程中,结构体裂纹常处于拉剪和压剪复合受力状态,研究适合于复合型裂纹的断裂准则和裂纹扩展机理具有重要的理论意义和实用价值。以Ⅰ-Ⅱ复合型裂纹为研究对象,基于线弹性理论,在考虑裂纹几何特征及受力形式的基础上,系统介绍了裂纹应力强度因子(SIF)的理论解。提出了适用于Ⅱ型断裂的径向剪应力准则和双剪应力准则。对于Ⅰ-Ⅱ复合型裂纹,提出用等效Ⅰ、Ⅱ型SIF比值与Ⅰ、Ⅱ型断裂韧度比值的关系判定裂纹断裂类型,并分别选择适合于Ⅰ、Ⅱ型断裂的断裂准则,计算了裂纹断裂扩展理论角度。理论断裂角与预制非闭合裂纹类岩石脆性材料压剪断裂试验结果符合得较好。 展开更多
关键词 非闭合裂纹 -Ⅱ复合型断裂 应力强度因子 准则
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国产HTPB复合固体推进剂Ⅰ-Ⅱ型裂纹断裂性能实验研究 被引量:18
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作者 张亚 强洪夫 杨月诚 《含能材料》 EI CAS CSCD 2007年第4期359-362,共4页
采用WDN-10KN材料实验机对含Ⅰ-Ⅱ复合型裂纹的HTPB复合固体推进剂进行了拉伸速率为2mm.min-1的单轴拉伸试验,用摄像机记录了推进剂裂纹扩展至断裂的整个过程。得到了六种不同裂纹倾斜角下的力-变形曲线及裂纹扩展开裂角和断裂载荷。与... 采用WDN-10KN材料实验机对含Ⅰ-Ⅱ复合型裂纹的HTPB复合固体推进剂进行了拉伸速率为2mm.min-1的单轴拉伸试验,用摄像机记录了推进剂裂纹扩展至断裂的整个过程。得到了六种不同裂纹倾斜角下的力-变形曲线及裂纹扩展开裂角和断裂载荷。与T断裂准则、S断裂准则和σθ断裂准则进行比较,结果表明推进剂裂纹扩展开裂角与T断裂准则的数值计算结果较为接近,说明可以借助于T断裂准则对推进剂裂纹扩展的初始开裂角进行初步的理论预测。 展开更多
关键词 固体力学 HTPB复合固体推进剂 -Ⅱ复合型裂纹 初始开裂角
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混凝土 Ⅰ-Ⅱ 复合型断裂试验的试件形式及试验装置系统 被引量:4
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作者 胡蓓雷 赵国藩 +1 位作者 宋玉普 黄承逵 《大连理工大学学报》 EI CAS CSCD 北大核心 1997年第S1期40-46,共7页
在总结分析有关研究的基础上,对进行稳定混凝土断裂试验所需的条件及试验测量误差进行了分析,提出了适于混凝土Ⅰ-Ⅱ复合型断裂试验研究的试件及其加载测量系统,并分析了引起测量误差的原因.结果表明。
关键词 混凝土 断裂/-Ⅱ复合型断裂
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基于损伤理论的混凝土Ⅰ-Ⅱ复合型裂缝扩展角 被引量:6
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作者 王玉琳 王向东 +1 位作者 韩金启 杨林 《河南科技大学学报(自然科学版)》 CAS 北大核心 2015年第6期51-54,60,共5页
基于混凝土断裂与损伤的基本理论,进行了Ⅰ-Ⅱ复合型裂缝扩展方向研究,研究结果表明:Ⅰ-Ⅱ复合型裂缝扩展趋势是随着缝端损伤场的变化而变化的。通过缝端损伤场及损伤梯度的计算,分析了Ⅰ-Ⅱ复合型裂缝从起裂至失稳断裂裂缝扩展方向的... 基于混凝土断裂与损伤的基本理论,进行了Ⅰ-Ⅱ复合型裂缝扩展方向研究,研究结果表明:Ⅰ-Ⅱ复合型裂缝扩展趋势是随着缝端损伤场的变化而变化的。通过缝端损伤场及损伤梯度的计算,分析了Ⅰ-Ⅱ复合型裂缝从起裂至失稳断裂裂缝扩展方向的变化规律,得到了Ⅰ-Ⅱ复合型裂缝的起裂扩展角和失稳扩展角。将其与文献结果进行对比,对比结果表明:用损伤理论研究裂缝的扩展角是可行的。 展开更多
关键词 混凝土 损伤梯度 断裂 -Ⅱ复合型裂缝 扩展角
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数字图像相关法测定岩石Ⅰ-Ⅱ复合型裂纹应力强度因子 被引量:26
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作者 代树红 马胜利 潘一山 《岩土工程学报》 EI CAS CSCD 北大核心 2013年第7期1362-1368,共7页
提出了一种通过数字图像相关方法测定岩石Ⅰ-Ⅱ复合型裂纹尖端位置和应力强度因子的试验方法。试验通过数字图像相关方法测定裂纹尖端区域位移场数据,将位移场数据带入极坐标系下位移场方程,计算裂纹尖端位置和应力强度因子。试验结果表... 提出了一种通过数字图像相关方法测定岩石Ⅰ-Ⅱ复合型裂纹尖端位置和应力强度因子的试验方法。试验通过数字图像相关方法测定裂纹尖端区域位移场数据,将位移场数据带入极坐标系下位移场方程,计算裂纹尖端位置和应力强度因子。试验结果表明:采用该方法可以准确的测定岩石Ⅰ-Ⅱ复合型裂纹应力强度因子、裂纹尖端位置及裂纹扩展长度,解决了以往研究方法因不能准确测定裂纹尖端位置和扩展方向,而无法准确测定岩石应力强度因子的难题。 展开更多
关键词 数字图像相关方法 -Ⅱ复合型裂纹应力强度因子 裂纹扩展长度 岩石断裂
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