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Discrete numerical modeling of granular materials considering crushability

Journal of Mountain Science 2017年第4期14卷 758-770页

作者： QIAN jian-gu gu jian-bo gu Xiao-qiang HUANG Mao-song Key Laboratory of Geotechnieal and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

The aim of this study is to numerically investigate the influence of particle breakage on the mechanical behavior of granular materials using a discrete element method(DEM). To enable particle crushing, non-crushable elementary particles are boned together to represents the granular aggregates which can be crushed when the external force exceeds its strength. The flaw of the aggregate was also modeled by randomly distributed void. Single particle crushing tests were carried out to determine the distribution of particle strength. The results of single particle crushing tests illustrate that the simulated single particle fracture strength and pattern agree well with the Weibull's distribution *** oedometer tests, drained monotonic and cyclic triaxial tests were also carried out to investigate the crushing of the aggregates and the associated mechanical behaviors. The effect of confining pressure on the crushing of aggregates and the mechanical behavior was also analyzed. It was found that the peak stress and dilation decrease significantly when particle crushing was *** deformation behavior of the specimen is essentially controlled by two factors: particle rearrangement-induced dilation and particle crushing-induced contraction. The increase of permanent strain and the reduction of dilation were observed during cyclic loading and they tend to reach a stable state after a certain number of cycles. The crushing of aggregate is most significant in the first two cycles. The results also indicated that for the same axial strain the volumetric strain and the bound breakage in the cyclic loading tests are significantly larger than that in the monotonic loading tests,especially at high cyclic stress ratio.

关键词： DEM simulation Granular materials Crushing Monotonic and Cyclic triaxial test

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Preparation of manganese sulfate from low-grade manganese carbonate ores by sulfuric acid leaching

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International Journal of Minerals,Metallurgy and Materials 2016年第5期23卷 491-500页

作者： qing-quan Lin guo-hua gu Hui Wang Ren-feng Zhu You-cai Liu jian-gang Fu School of Minerals Processing and Bioengineering Central South University School of Chemistry and Chemical Engineering Central South University

In this study, a method for preparing pure manganese sulfate from low-grade ores with a granule mean size of 0.47 mm by direct acid leaching was developed. The effects of the types of leaching agents, sulfitric acid concentration, reaction temperature, and agitation rate on the leaching efficiency of manganese were investigated. We observed that sulfuric acid used as a leaching agent provides a similar leach- ing efficiency of manganese and superior selectivity against calcium compared to hydrochloric acid. The optimal leaching conditions in sul- furic acid media were determined; under the optimal conditions, the leaching efficiencies of Mn and Ca were 92.42% and 9.61%, respec- tively. Moreover, the kinetics of manganese leaching indicated that the leaching follows the diffusion-controlled model with an apparent ac- tivation energy of 12.28 kJ·mol-l. The purification conditions of the leaching solution were also discussed. The results show that manganese dioxide is a suitable oxidant of ferrous ions and sodium dimethyldithiocarbamate is an effective precipitant of heavy metals. Finally, through chemical analysis and X-ray diffraction analysis, the obtained product was determined to contain 98% of MnSOa4·H20.

关键词： manganese ore treamaent manganese carbonate leaching leaching kinetics manganese sulfate

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AIEgens-lightened Functional Polymers: Synthesis, Properties and Applications

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Chinese Journal of Polymer Science 2019年第4期37卷 302-326,I0005页

作者： Shi-Yuan Zhou Hai-Bo Wan Feng Zhou Pei-Yang gu qing-Feng Xu jian-Mei Lu College of Chemistry Chemical Engineering and Materials ScienceCollaborative Innovation Center of Suzhou Nano Science and TechnologySoochow University

Recently, polymers with aggregation-induced emission(AIE) effects have attracted significant attention due to their broad applications in luminescence sensors, stimuli responsive materials, electroluminescence devices, etc. In this review, we summarize recent advances concerning AIE polymers. Four types of AIE polymers including end-functionalized polymers, side-chain polymers, main-chain polymers, and other polymers according to the location of AIEgens, are described. Their synthetic preparation, optical property, AIE effects, and applications are also illustrated in this review.

关键词： Aggregation-induced emission Functional polymers Synthetic method Application

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Entropy majorization, thermal adiabatic theorem, and quantum phase transitions

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Frontiers of physics 2012年第2期7卷 244-251页

作者： Shi-jian gu (1) 1. Department of Physics and Institute of Theoretical Physics The Chinese University of Hong Kong Hong Kong China

Let a general quantum many-body system at a low temperature adiabatically cross through the vicinity of the system＇s quantum critical point. We show that the system＇s temperature is signif- icantly suppressed due to both the entropy majorization theorem in quantum information science and the entropy conservation law in reversible adiabatic processes. We take the one-dimensional transverse-field Ising model and the spinless fermion system as concrete examples to show that the inverse temperature might become divergent around the systems＇ critical points. Since the temper- ature is a measurable quantity in experiments, it can be used, via reversible adiabatic processes at low temperatures, to detect quantum phase transitions in the perspectives of quantum information science and quantum statistical mechanics.

关键词： quantum phase transition entropy majorization

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Review of Some Advances and Applications in Real-time High-speed Vision: Our Views and Experiences

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International Journal of Automation and computing 2016年第4期13卷 305-318页

作者： qing-Yi gu Idaku Ishii Robotics Laboratory Graduate School of Engineering Hiroshima University Higashi-Hiroshima Hiroshima 738-8527 Japan

The frame rate of conventional vision systems is restricted to the video signal formats （e.g., NTSC 30 fps and PAL 25 fps） that are designed on the basis of the characteristics of the human eye, which implies that the processing speed of these systems is limited to the recognition speed of the human eye. However, there is a strong demand for real-time high-speed vision sensors in many application fields, such as factory automation, biomedicine, and robotics, where high-speed operations are carried out. These high-speed operations can be tracked and inspected by using high-speed vision systems with intelligent sensors that work at hundreds of Hertz or more, especially when the operation is difficult to observe with the human eye. This paper reviews advances in developing real-time high Speed vision systems and their applications in various fields, such as intelligent logging systems, vibration dynamics sensing, vision-based mechanical control, three-dimensional measurement/automated visual inspection, vision-based human interface, and biomedical applications.

关键词： Real-time high-speed vision target tracking abnormal behavior detection behavior mining vibration analysis 3D shapemeasurement cell sorting.

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A Framework of Convergence Analysis of Mini-batch Stochastic Projected Gradient Methods

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Journal of the Operations Research Society of China 2023年第2期11卷 347-369页

作者： jian gu Xian-Tao Xiao School of Sciences Dalian Ocean UniversityDalian 116023China School of Mathematical Sciences Dalian University of TechnologyDalian 116023China

In this paper,we establish a unified framework to study the almost sure global convergence and the expected convergencerates of a class ofmini-batch stochastic(projected)gradient(SG)methods,including two popular types of SG:stepsize diminished SG and batch size increased *** also show that the standard variance uniformly bounded assumption,which is frequently used in the literature to investigate the convergence of SG,is actually not required when the gradient of the objective function is Lipschitz ***,we show that our framework can also be used for analyzing the convergence of a mini-batch stochastic extragradient method for stochastic variational inequality.

关键词： Stochastic projected gradient method Variance uniformly bounded Convergence analysis

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Fidelity spectrum:A tool to probe the property of a quantum phase

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Chinese Physics B 2016年第3期25卷 84-90页

作者： Wing Chi Yu Shi-jian gu Department of Physics and ITR The Chinese University of Hong KongHong KongChina

Fidelity measures the similarity between two states and is widely adapted by the condensed matter community as a probe of quantum phase transitions in many-body systems. Despite its success in witnessing quantum critical points, information about the fine structure of a quantum phase one can get from this approach is still limited. Here, we proposed a scheme called fidelity spectrum, By studying the fidelity spectrum, one can obtain information about the characteristics of a phase. In particular, we investigated the spectra in the one-dimensional transverse-field Ising model and the two- dimensional Kitaev model on a honeycomb lattice. It was found that the sPectra have qualitative differences in the critical and non-critical regions of the two models. From the distributions of them, the dominating k modes in a particular phase could also be captured.

关键词： quantum phase.transitions quantum information quanfized spin models

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Optimal placement of piezoelectric active bars in vibration control by topological optimization

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Acta Mechanica Sinica 2008年第6期24卷 699-708页

作者： guozhong Zhao jian Wang Yuanxian gu State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering Mechanics Dalian University of Technology Dalian 116024 China

A continuous variable optimization method and a topological optimization method are proposed for the vibration control of piezoelectric truss structures by means of the optimal placements of active bars. In this optimization model, a zero-one discrete variable is defined in order to solve the optimal placement of piezoelectric active bars. At the same time, the feedback gains are also optimized as continuous design variables. A two-phase procedure is proposed to solve the optimization problem. The sequential linear programming algorithm is used to solve optimization problem and the sensitivity analysis is carried out for objective and constraint functions to make linear approximations. On the basis of the Newmark time integration of structural transient dynamic responses, a new sensitivity analysis method is developed in this paper for the vibration control problem of piezoelectric truss structures with respect to various kinds of design variables. Numerical examples are given in the paper to demonstrate the effectiveness of the methods.

关键词： Piezoelectric intelligent truss Vibrationcontrol Design optimization Sensitivity analysis

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Molecular Mediators of Estrogen Reduction-induced Otolith Shedding

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Current Medical Science 2021年第4期41卷 667-672页

作者： Mei-yan FENG Huan-huan gu qing TIAN Hua-lan YANG jian-hua ZHUANG Department of Neurology Medical Center for Vertigo and Balance DisordersShanghai Changzheng Hospital of Navy Medical UniversityShanghai200003China Department of Neurology Shanghai Pudong HospitalFudan University Pudong Medical CenterShanghai201399China

Objective Previous study suggested that estradiol(E2)plays an important role in otolith shedding by regulating the expression of otoconin 90(OC90).The purpose of this article is to provide further data on the effect and mechanism of E2 on the morphology of *** The rats receiving bilateral ovariectomy(OVX)were used as animal ***-immunoprecipitation was used to observe the relationship between estrogen receptor(ER)and estrogen-related receptorα(ERRα).The morphology of otolith was observed under the scanning electron *** blotting and qPCR were used for quantitative analysis of the roles of ER and ERRαin regulating OC90 *** The looser otoliths were observed in rats receiving bilateral OVX,which could be reversed by supplementation with *** level of ERRαwas decreased in bilateral OVX *** and ERRαinteracted with each other on the regulation of the expression of *** Our results suggest ER and ERRαare both important downstream receptors involved in regulating OC90 expression in utricles of rats,and ERRαprobably functions by interacting with *** provides evidence for the mechanism of otolith *** it may be significant for future studies of targeted prevention and therapies for benign paroxysmal positional vertigo.

关键词： estrogen-related receptorα estrogen receptor otoconin 90 otolith benign paroxysmal positional vertigo

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Intercalation-pseudocapacitance hybrid anode for high rate and energy lithium-ion capacitors

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Journal of Energy Chemistry 2021年第4期30卷 459-467页

作者： Chang Liu Ali Khosrozadeh qing-qing Ren Ling-Hui Yan Kokswee Goh Shi-Han Li jian Liu Lei Zhao Da-Ming gu Zhen-Bo Wang MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage State Key Lab of Urban Water Resource and EnvironmentSchool of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150001HeilongjiangChina School of Engineering Faculty of Applied ScienceUniversity of British ColumbiaKelowna V1V 1V7BCCanada

Existing rechargeable batteries not only fail to meet the demand for high power applications but also cause heavy metal ***-ion capacitors(LICs),which can achieve higher charging speeds and energy densities than supercapacitors,have attracted extensive ***,sluggish Li-ion diffusion of the battery-type anode results in limited rate performance of ***,highperformance LICs using both battery and capacitor type Mn_(2)V_(2)O_(7)-graphene(MVO-G)anodes and hempstem-derivated activated carbon(HSAC)cathodes with a large surface area are first *** addition to high pseudocapacitance,the MVO-G possesses the advantage of fast Li^(+)storage performance making it a suitable choice for advanced LIC *** is employed to enhance overall conductivity and cycling stability leading to enhanced energy *** MVO-G//HSAC LICs exhibit a high energy density of 148.1 Wh kg^(-1) at a power density of 150 W kg^(-1) and 25 Wh kg^(-1) even at15 k W kg^(-1).More importantly,the MVO-G//HSAC LICs also show excellent cycling stability of 90%after15,000 cycles,which is expected for high performance energy storage systems.

关键词： Manganese vanadate Graphene Pseudocapacity Hempstem-based activated carbons Lithium ion capacitor

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