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Shear behaviours of cohesionless mixed soils using the DEM:The influence of coarse particle shape

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Particuology 2021年第2期19卷 151-165页

作者： Yangui zhu jian Gong Zhihong Nie School of Civil Engineering Central South UniversityChangsha 410075China

The coarse particles in mixed soils can be cobbles or gravels,with the main difference being their roundness(an indicator describing particle shape characteristics at an intermediate scale).The influence of coarse particle shape(i.e.,roundness)on the macroscopic and microscopic shear behaviours of cohesionless mixed soils with various fines contents(FCs)was investigated via the discrete element method in this *** shapes of coarse particles were formed using the rotation-invariant spherical harmonic method proposed by previous *** equation was proposed to predict the initial void ratios of samples in this study.A decrease in the roundness of coarse particles can increase the peak friction angle(FC≤40%)and critical friction angle(FC≤30%).As the roundness of coarse particles decreases,the peak dilatancy angle initially increases and then decreases(FC≤20%).Furthermore,it was found that the roundness of coarse particles hardly affects the classification of cohesionless mixed soils,as determined by probing the percentage contributions of coarse-coarse,coarse-fine,and fine-fine *** cohesionless mixed soils change from an underfilled structure to an interactive-underfilled structure at the critical state,the main forms of coarse-coarse contacts were ***,the force-fabric anisotropy mechanisms of the influences of the roundness and rolling resistance coefficient of coarse particles on the shear strengths of cohesionless mixed soils were found to be different.

关键词： Cohesionless mixed soils Particle shape Roundness Shear behaviours Discrete element method

Mean estimation over numeric data with personalized local differential privacy

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Frontiers of Computer Science 2022年第3期16卷 183-192页

作者： Qiao XUE Youwen zhu jian WANG College of Computer Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China Guangxi Key Laboratory of Trusted Software Guilin University of Electronic TechnologyGuilin 541004China School of Cyber Security Gansu University of Political Science and LawLanzhou 730070China

The fast development of the Internet and mobile devices results in a crowdsensing business model,where individuals(users)are willing to contribute their data to help the institution(data collector)analyze and release useful ***,the reveal of personal data will bring huge privacy threats to users,which will impede the wide application of the crowdsensing *** settle the problem,the definition of local differential privacy(LDP)is ***,to respond to the varied privacy preference of users,resear-chers propose a new model,i.e.,personalized local differential privacy(PLDP),which allow users to specify their own privacy *** this paper,we focus on a basic task of calculating the mean value over a single numeric attribute with *** on the previous schemes for mean estimation under LDP,we employ PLDP model to design novel schemes(LAP,DCP,PWP)to provide personalized privacy for each *** then theoretically analysis the worst-case variance of three proposed schemes and conduct experiments on synthetic and real datasets to evaluate the performance of three *** theoretical and experimental results show the optimality of PWP in the low privacy regime and a slight advantage of DCP in the high privacy regime.

关键词： personalized local differential privacy mean estimation crowdsensing model

A review on lithium-sulfur batteries:Challenge,development,and perspective

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Nano Research 2023年第6期16卷 8097-8138页

作者： Qinjun Shao Shengdong zhu jian Chen Advanced rechargeable battery Laboratory Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100049China

Lithium-sulfur(Li-S)battery is recognized as one of the promising candidates to break through the specific energy limitations of commercial lithium-ion batteries given the high theoretical specific energy,environmental friendliness,and low *** the past decade,tremendous progress have been achieved in improving the electrochemical performance especially the lifespan by various strategies mainly concentrated on the sulfur *** this review,the fundamental electrochemistry of sulfur cathode and lithium anode is revealed to understand the current *** the advances achieved through diverse strategies are comprehensively summarized,which involves lithium polysulfides(LiPSs)limitation,sulfur redox reaction regulation and electrocatalysis in sulfur cathode and artificial solid electrolyte interface(SEI),electrolyte design,and structured anode in lithium ***,the differences between laboratory level coin cells and actual pouch cells need to be addressed that only few reports on practical Li-S pouch cell are available due to the unexpected problems on both sulfur cathode and lithium anode which are masked at lithium and electrolyte ***,the challenges and perspective toward the practical Li-S batteries are also offered.

关键词： lithium-sulfur batteries shuttle effect lithium dendrite solid electrolyte interface Coulombic efficiency

Finite Volume Hermite WENO Schemes for Solving the Hamilton-Jacobi Equation

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Communications in Computational Physics 2014年第4期15卷 959-980页

作者： Jun zhu jianxian qiu College of Science Nanjing University of Aeronautics and AstronauticsNanjing 210016JiangsuChina School of Mathematical Sciences Xiamen UniversityXiamen 361005FujianChina.

In this paper,we present a new type of Hermite weighted essentially nonoscillatory(HWENO)schemes for solving the Hamilton-Jacobi equations on the finite volume *** cell averages of the function and its first one(in one dimension)or two(in two dimensions)derivative values are together evolved via time approaching and used in the *** the major advantages of the new HWENO schemes are their compactness in the spacial field,purely on the finite volume framework and only one set of small stencils is used for different type of the polynomial *** numerical tests are performed to illustrate the capability of the methodologies.

关键词： HWENO scheme finite volume Hamilton-Jacobi equation

Influence of the rolling-resistance-based shape of coarse particles on the shear responses of granular mixtures

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Particuology 2020年第5期18卷 67-82页

作者： Yangui zhu Zhihong Nie jian Gong School of Civil Engineering Central South UniversityChangsha 410075China School of Hydraulic Engineering Changsha University of Science and TechnologyChangsha 410114China

Shear responses of dense granular mixtures of spherical coarse particles with the rolling resistance and spherical fine particles are studied via triaxial compression tests using the discrete element *** macroscale responses(shear strength and dilatancy)are *** the results with those in the literature indicates that granular mixtures with a rolling resistance coefficient of 0.5 have similar macroscale responses to those of gravel-shaped coarse particle *** quantify the microscale responses including the percentage contributions of contact types,partial coordination number,average particle rotation,average degree of interlocking,and local structural properties,A detailed analysis of the force-fabric anisotropy reveals the mechanisms of the variations in the shear strength with the rolling resistance coefficient and the fines *** mechanism of the variation in the shear strength with the fines content for granular mixtures with a rolling resistance coefficient of 0.5 is different from that for gravel-shaped coarse particle ***,we find that a rolling resistance linear model weakens the linear relationship between the stress ratio and the fabric anisotropy of strong and non-sliding contacts when the fines content is 30% and 40%.

关键词： Granular mixture Rolling resistance Particle shape Fines content Macroscale and microscale responses Anisotropy

Optimization design of chiral hexagonal honeycombs with prescribed elastic properties under large deformation

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Chinese Journal of Aeronautics 2020年第3期33卷 902-909页

作者： Kepeng qiu Ruoyao WANG Jihong zhu Weihong ZHANG School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an 710072China

Flexible chiral honeycomb cores generally exhibit nonlinear elastic properties due to large geometric *** effective elastic moduli and Poisson's ratio typically vary with an increase in ***,the size and shape optimization of the chiral hexagonal honeycombs was performed to keep the Young's moduli and Poisson's ratio unchanged under large *** size of the honeycomb unit cell and the position coordinates of the key points were defined simultaneously as design *** equivalent Young's modulus and Poisson's ratio of chiral honeycombs were calculated through geometric nonlinear *** objective was to minimize the allowable tolerance between the prescribed and actual properties within the range of the target strain.A genetic algorithm was then *** optimal results demonstrate that the chiral honeycombs can maintain effective elastic properties that do not vary under large *** results are meaningful to morphing aircraft designs.

关键词： Chiral hexagonal honeycombs Genetic algorithm Geometric nonlinearity Large deformation Shape optimization

Reconfigurable Modeling Technology of Similar-structure Products Configuration Design

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Chinese Journal of Mechanical Engineering 2013年第1期26卷 189-196页

作者： qiu Lemiao REN Bin ZHANG Shuyou XU jian The State Key Lab of Fluid Power Transmission and Control Zhejiang University

The product configuration modeling is a key technology to realize configuration design. Most of the researches were mainly conducted focusing on how to establish a product configuration model, but were short of the consideration about the application scope and dynamic change features. In this paper, the reconfigurable modeling technology of similar-structure products configuration design is studied to enhance the generality and diversity of product configuration models, and to facilitate the dynamic upgrade of configuration models. The configuration components of products with similar structures are divided into sharable configuration components, essential configuration components and optional configuration components, so the construction of reconfigurable model of configuration design can be converted into the set operation of configuration components. The horizontal adjusting reconstruction of configuration model is carried out through the adding, replacing and deleting of configuration components, the vertical adjusting reconstruction of configuration model is carried out through the parametric deformation of configuration components, and the variable topological configuration model reconstruction can be realized through the transformation of partial structure of configuration components. Finally, NC machine products are used as an example to analyze and verify the reconfigurable modeling technology of products with similar structures. The speed of NC machine configuration design is found to be improved, and the number of NC machine configuration design models is decreased. And the reconfigurable design system of NC machine products is developed. The proposed modeling technology provides references for the processes, methods and steps of model reconstruction.

关键词： similar-structure products configuration component product configuration model reconstruction

Protection of ghrelin postconditioning on hypoxia/ reoxygenation in gastric epithelial cells

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World Journal of Gastroenterology 2012年第38期18卷 5377-5388页

作者： Zhang-Bo Liu Su-Juan Fei Sheng-Ping zhu Jin-Zhou zhu Hong-Xia Han qiu-Ju Dong jian-Fu Zhang DepartmentofGastroenterol-ogy TheAffiliatedHospitalofXuzhouMedicalCollege99WestHuaihaiRoadXuzhou221002JiangsuProvinceChina Department of Physiology Xuzhou MedicalCollege Xuzhou 221002 Jiangsu Province China

AIM: To investigate the protective effect and mechanisms of ghrelin postconditioning against hypoxia/reoxygenation (H/R)-induced injury in human gastric epithelial cells. METHODS: The model of H/R injury was established in gastric epithelial cell line (GES-1) human gastric epithelial cells. Cells were divided into seven groups: normal control group (N); H/R postconditioning group; DMSO postconditioning group (DM); ghrelin postconditioning group (GH); D-Lys3-GHRP-6 + ghrelin postconditioning group (D + GH); capsazepine + ghrelin postconditioning group (C + GH); and LY294002 + ghrelin postconditioning group (L + GH). 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to detect GES-1 cell viability. Hoechst 33258 fluorochrome staining and flow cytometry were conducted to determine apoptosis of GES-1cells. Spectrophotometry was performed to determine release of lactate dehydrogenate (LDH). Protein expression of Bcl-2, Bax, Akt, and glycogen synthase kinase (GSK)-3β was determined by western blotting. Expression of vanilloid receptor subtype 1 (VR1), Akt and GSK-3β was observed by immunocytochemistry. RESULTS: Compared with the H/R group, cell viability of the GH group was significantly increased in a dosedependent manner (55.9% ± 10.0% vs 69.6% ± 9.6%, 71.9% ± 17.4%, and 76.3% ± 13.3%). Compared with the H/R group, the percentage of apoptotic cells in the GH group significantly decreased (12.38% ± 1.51% vs 6.88% ± 0.87%). Compared with the GH group, the percentage of apoptotic cells in the D + GH group, C + GH group and L + GH groups significantly increased (11.70% ± 0.88%, 11.93% ± 0.96%, 10.20% ± 1.05% vs 6.88% ± 0.87%). There were no significant differences in the percentage of apoptotic cells between the H/R and DM groups (12.38% ± 1.51% vs 13.00% ± 1.13%). There was a significant decrease in LDH release following ghrelin postconditioning compared with the H/R group (561.58 ± 64.01 U/L vs 1062.45 ± 105.29 U/L). There was a significant

关键词： Protection of ghrelin postconditioning on hypoxia/ reoxygenation in gastric epithelial cells

Experimental and analytical studies on the deformability of a precast RC shear wall involving bolted connections

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Science China(Technological Sciences) 2015年第8期58卷 1439-1448页

作者： SUN jian qiu HongXing YANG Yuan LU Bo Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education Southeast University Suzhou Institute of Architectural Design Co.Ltd.

To study the deformability and ductility of an innovative precast shear wall joined by bolted connections,experimental tests were conducted on two test walls under monotonic and cyclic loading,respectively;subsequently,theoretical analysis was performed on the deformation performance of the shear wall *** test results confirmed the favorable deformability and ductility of the *** top displacement of the shear wall assembly was analytically decomposed into several constituent parts,the theoretical formulae of which were subsequently *** compositional analysis demonstrated that the top displacement of the test wall was primarily induced by the elastic deformation of the upper wall panel(UWP),the relative slippages within the bolted connections,and the flexural deformation within the plastic region of the UWP,while the constituent part contributed by the deformation in the connecting steel frame can be neglected.

关键词： precast shear wall bolted connections deformability analytical formulae