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Weak Solutions of the Isothermal Bipolar Hydrodynamic Model for Semiconductors with Large Data

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Wuhan University Journal of Natural Sciences 2014年第1期19卷 62-70页

作者： mao jianfeng School of Mathematics and Statistics Hubei Science University

This paper is devoted to weak solutions of Cauchy problem to the isothermal bipolar hydrodynamic model with large data. The model takes the bipolar Euler-Poisson form, with electric field and relaxation terms added to the momentum equations. Using Glimm scheme to the hyperbolic part and the standard theory to the ordinary differential equations, we first construct the approximation solutions, then from the facts that the total charge is quasi-conservation, we can obtain a uniform estimate of the total variation of the electric field, which allows to prove the L∞ estimate of densities and velocities, and the convergence of the scheme. Then we can prove the global existence of weal solution to Cauchy problem with large data.

关键词： weak solution isothermal bipolar hydrodynamic model Glimm scheme

Synthesis and enhanced piezoelectric response of CVD-grown SnSe layered nanosheets for flexible nanogenerators

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Nano Research 2023年第9期16卷 11839-11845页

作者： Fumei Yang Man-Chung Wong jianfeng mao Zehan Wu Jianhua Hao Department of Applied Physics the Hong Kong Polytechnic UniversityHong Kong 999077China

Piezoelectricity is the electric charge which accumulates in certain materials in response to mechanical stimuli,while piezoelectric nanogenerators(PENGs)converting mechanical energy into electricity can be widely used for energy harvesting and self-powered *** group IV-VI monochalcogenides may exhibit strong piezoelectricity because of their puckered C_(2v)symmetry and electronic structure,making them promising for flexible ***,we investigated the synthesis and piezoelectric properties of multilayer SnSe nanosheets grown by chemical vapor deposition(CVD).The SnSe nanosheets exhibited high single-crystallinity,large area,and good *** strong layer-dependent in-plane piezoelectric coefficient of SnSe nanosheets showed a saturated trend to be~110 pm/V,which overcomes the weak piezoelectric response or odd-even effects in other layered nanosheets.A high energy conversion efficiency of 9.3%and a maximum power density of 538 mW/cm^(2)at 1.03%strain have been demonstrated in a SnSe-based *** on the enhanced piezoelectricity of SnSe and attractive output performance of the nanogenerator,a self-powered sensor for human motion monitoring is further *** results demonstrate the strong piezoelectricity in high quality CVD-grown SnSe nanosheets,allowing for application in flexible smart piezoelectric sensors and advanced microelectromechanical devices.

关键词： SnSe piezotronics piezoresponse force microscope piezoelectric nanogenerator self-powered device

Regularization Strategy for the Cauchy Problem of Laplace's Equation from the Viewpoint of Regularization Theory

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Wuhan University Journal of Natural Sciences 2012年第4期17卷 285-289页

作者： QIAN Ailin mao jianfeng School of Mathematics and Statistics Hubei University of Science and TechnologyXianning 437100HubeiChina

Within the framework of the regularization theory, a spectral regularization method is introduced and analyzed. The convergence estimate under an appropriate choice of regularization parameter is obtained. A numerical... 详细信息

关键词： ill-posed problems Cauchy problem regularization error estimate spectral methods

Nonlinear Impact Damage Evolution of Charpy Type and Analysis of Its Key Influencing Factors

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 254-264页

作者： jianfeng mao Qian Xu Jiadong Yang Chi Cao Dasheng Wang Fengping Zhong Mingya Chen Institute of Process Equipment and Control Engineering Zhejiang University of TechnologyHangzhou 310032China Taizhou Key Laboratory of Advanced Manufacturing Technology Taizhou InstituteZhejiang University of TechnologyTaizhou 318014China State Key Laboratory of Nuclear Power Safety Monitoring Technology and Equipment Shenzhen 518172China Zhejiang Academy of Special Equipment Science Hangzhou 310020China Suzhou Nuclear Power Research Institute Suzhou 215004China

The current research of Charpy impact mainly focuses on obtaining the ductile brittle transition temperature of materials by *** with experiments,numerical simulation can study many problems with harsh ***,there are still few studies on the influence of geometric factors such as side *** this paper,the geometry of standard Charpy impact test is *** with different widths and side grooves are *** finite element model of Charpy impact was established by ABAQUS *** test results and simulation results to verify each *** effects of sample width,side groove depth and side groove bottom fillet on the impact fracture resistance of the sample were *** results show that the specimen width is positively correlated with the impact toughness of the *** side groove greatly reduces the impact toughness of the material;the toughness of side groove decreases with the increase of depth;the fracture toughness of side groove decreases with the increase of fillet at the bottom of side *** proportion of toughness energy to impact energy of samples was *** results show that the toughness energy accounts for about 70%of the impact energy of the sample,which has little to do with the geometric characteristics of the *** study presents a reliable method for studying Charpy impact *** influence of geometric parameters is obtained,which provides a reference method for the study of impact toughness of high toughness materials.

关键词： Johnson-Cook model Impact toughness Charpy impact

The critical role of carbon in marrying silicon and graphite anodes for high-energy lithium-ion batteries

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Carbon Energy 2019年第1期1卷 57-76页

作者： Jingxing Wu Yinliang Cao Haimin Zhao jianfeng mao Zaiping Guo Institute for Superconducting and Electronic Materials Australian Institute for Innovative MaterialsUniversity of WollongongWollongongNew South WalesAustralia School of Mechanical MaterialsMechatronics and Biomedical EngineeringUniversity of WollongongWollongongNew South WalesAustralia Tianneng Battery Group Co Ltd ZhejiangChina

Increasing the energy density of conventional lithium-ion batteries(LIBs)is important for satisfying the demands of electric vehicles and advanced *** is considered as one of the most-promising anodes to replace the traditional graphite anode for the realization of high-energy LIBs due to its extremely high theoretical capacity,although its severe volume changes during lithiation/delithiation have led to a big challenge for practical *** contrast,the co-utilization of Si and graphite has been well recognized as one of the preferred strategies for commercialization in the near *** this review,we focus on different carbonaceous additives,such as carbon nanotubes,reduced graphene oxide,and pyrolyzed carbon derived from precursors such as pitch,sugars,heteroatom polymers,and so forth,which play an important role in constructing micrometersized hierarchical structures of silicon/graphite/carbon(Si/G/C)composites and tailoring the morphology and surface with good structural stability,good adhesion,high electrical conductivity,high tap density,and good interface chemistry to achieve high capacity and long cycling stability *** first discuss the importance and challenge of the co-utilization of Si and ***,we carefully review and compare the improved effects of various types of carbonaceous materials and their associated structures on the electrochemical performance of Si/G/C *** also review the diverse synthesis techniques and treatment methods,which are also significant factors for optimizing Si/G/C ***,we provide a pertinent evaluation of these forms of carbon according to their suitability for *** also make far-ranging suggestions with regard to the selection of proper carbonaceous materials and the design of Si/G/C composites for further development.

关键词： carbonaceous additives graphite high energy lithium-ion batteries silicon

Practical assessment of the energy density of potassium-ion batteries

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Science China Chemistry 2024年第1期67卷 4-12页

作者： Liang Sun Guanjie Li Shilin Zhang Sailin Liu Jodie Yuwono jianfeng mao Zaiping Guo School of Chemical Engineering and Advanced Materials The University of AdelaideAdelaide 5000Australia

1 Introduction The evolution of modern human society closely depends on affordable,efficient,and safe energy storage ***,lithium-ion batteries(LIBs)are the dominant energy storage systems to power portable electronics... 详细信息

关键词： energy lithium smart

Genetic structure of needle morphological and anatomical traits of Pinus yunnanensis

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Journal of Forestry Research 2016年第1期27卷 13-25页

作者： Yujie Huang jianfeng mao Zhiqiang Chen Jingxiang Meng Yulan Xu Anan Duan Yue Li National Engineering Laboratory for Forest Tree Breeding Key Laboratory for Genetics and Breeding of Forest Trees and Ornamental Plants of Ministry of Education College of Biological Sciences and Technology Beijing Forestry University Key Laboratory for Forest Resources Conservation and the Southwest Mountains of China Ministry of Education Southwest Forestry University

Pinus yunnanensis Franch. is an particular conifer tree species in Yunnan-Guizhou plateau in south- west China. The morphological and anatomical traits of needles are important to evaluate geographic variation and population dynamics of conifer species. Seedlings from seven populations of P. yunnanensis were analyzed, look- ing at 22 morphological and anatomical needle traits. The results showed that variations among and within popula- tions were significantly different for all traits and the variance components within populations were generally higher than that among populations in the most tested needle traits. The proportions of three-needle fascicle were significantly different among populations. The traits related to needle size in both morphology and anatomy were positive with latitude and negative with annual temperature and precipitation. Ratio indices, including mesophyllarea/vascular bundle area, mesophyll area/resin canals area, vascular bundle area/resin canals area and mesophyU area/（resin canals area and vascular bundle area）, were negatively correlated with elevation and positively corre- lated with the annual mean temperature, showing some fitness feature for the populations. Needle traits were more significantly correlated with longitude than with other four environmental factors. Needle length was significantly correlated with almost all environmental factors. First four principal components accounted for 81.596 % of the variation with eigenvalues 〉1; the differences among populations were mainly dependent on needle width, stomatal density, section areas of vascular bundle, total resin canals, and mesophyll, as well as area ratio traits. Seven populations were divided into three categories by Euclidean distance. Variations in needle traits among the populations have shown systematic microevolution in terms of geographic impact on P. yunnanensis. This study would provide empirical data to characterize adaptation and genetic variation of P. yunnanens

关键词： Genetic structure Needle Morphologicaland anatomical traits Geographic population Pinusyunnanensis

Germination and early seedling growth of Pinus densata ***

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Journal of Forestry Research 2016年第2期27卷 283-294页

作者： Yulan Xu Nianhui Cai Bin He Ruili Zhang Wei Zhao jianfeng mao Anan Duan Yue Li Keith Woeste Key Laboratory for Forest Resources Conservation and Usein the Southwest Mountains of China College of ForestrySouthwest Forestry UniversityKunming 650224China The State Engineering Laboratory for Tree Breeding Collegeof Biological Science and BiotechnologyBeijing Forestry UniversityBeijing 100083China State Key Laboratory of Systematic and Evolutionary Botany Institute of BotanyChinese Academy of ScienceBeijing 100093China USDA Forest Service Hardwood Tree Improvement and Regeneration Center at Purdue University West LafayetteIN 47906USA

We studied seed germination and early seedling growth of Pinus densata to explore the range of variability within the species and to inform afforestation practices. Phenotypes were evaluated at a forest tree nursery under conditions that support Pinus yunnanensis, one of the presumed parental species of P. densata. Seeds were col- lected from 20 open-pollinated trees within each of eight autochthonous populations representing the natural distri- bution of P. densata in China to assess variation in ger- mination traits and early seedling growth, and to examine the relationships among these traits. Results showed that seeds from all populations germinated and seedlings established successfully. There were significant differences among populations in 13 of 14 traits evaluated. Seed germination and early seedling growth were strongly related to seed size and seed weight. Bigger seeds germi- nated earlier and faster than small seeds, and seedling size was positively correlated with seed size. Some germination traits were strongly and significantly correlated with cli- matic variables associated with the provenance of the studied populations. Based on these observations, we conclude there were large, significant, and biologically important differences among P. densata populations in seed germination and seedling growth traits. The observed variability probably reflects a high degree of adaptive dif- ferentiation among populations that is likely to be relevant for future afforestation.

关键词： Afforestation Conifer Gaoshan pine Provenance Seed germination Seed size Seedling vigor

Recent progress in electrolyte design for advanced lithium metal batteries

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SmartMat 2023年第5期4卷 1-29页

作者： Mingnan Li Caoyu Wang Kenneth Davey Jingxi Li Guanjie Li Shilin Zhang jianfeng mao Zaiping Guo School of Chemical Engineering&Advanced Materials The University of AdelaideAdelaideAustralia

Lithium metal batteries(LMBs)have attracted considerable interest for use in electric vehicles and as next-generation energy storage devices because of their high energy ***,a significant practical drawback with LMBs is the instability of the Li metal/electrolyte interface,with concurrent parasitic reactions and dendrite growth,that leads to low Coulombic efficiency and poor cycle *** to the significant role of electrolytes in batteries,rationally designed electrolytes can improve the electrochemical performance of LMBs and possibly achieve fast charge and a wide range of working temperatures to meet various requirements of the market in the *** there are some review papers about electrolytes for LMBs,the focus has been on a single parameter or single performance separately and,therefore,not sufficient for the design of electrolytes for advanced LMBs for a wide range of working *** review presents a systematic summary of recent progress made in terms of electrolytes,covering the fundamental understanding of the mechanism,scientific challenges,and strategies to address drawbacks of electrolytes for high-performance *** advantages and disadvantages of various electrolyte strategies are also analyzed,yielding suggestions for optimum properties of electrolytes for advanced LMBs ***,the most promising research directions for electrolytes are discussed briefly.

关键词： anion-derived SEI fast charge liquid electrolyte design lithium metal batteries safe electrolytes wide working temperature