检索结果-南通市图书馆

On hypersurfaces of H2×H2

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2024年第2期67卷 339-366页

作者： Dong gao Hui Ma Zeke Yao School of Science Beijing University of Civil Engineering and Architecture Department of Mathematical Sciences Tsinghua University

In this paper, we study hypersurfaces of H2× H2. We first classify the hypersurfaces with constant principal curvatures and constant product angle functions. Then we classify homogeneous hypersurfaces and isoparametric hypersurfaces, respectively. Finally, we classify the hypersurfaces with at most two distinct constant principal curvatures, as well as those with three distinct constant principal curvatures under some additional conditions.

关键词： constant principal curvature homogeneous hypersurface isoparametric hypersurface 53C42 53B25 53C40

Varieties of Involution J-Trivial Monoids with Continuum Many Subvarieties

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Algebra Colloquium 2024年第3期31卷 467-480页

作者： Meng gao Wenting Zhang Yanfeng Luo School of Mathematics and Statistics Lanzhou UniversityLanzhou 730000China

In this paper,we give a suficient condition under which an involution monoid generates a variety with continuum many *** to this result,several involution J-trivial monoids are shown to generate varieties with continuum many *** examples include Rees quotients of free involution monoids,Lee monoids with involution,and Straubing monoids with involution.

关键词： monoid involution monoid variety subvariety lattice of varieties

Room temperature self-healing liquid metals:capabilities,applications and challenges

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Smart and Nano Materials 2024年第3期15卷 469-501页

作者： Chen Hua Jianye gao Jing Liu Key Lab of Cryogenic Science and Technology Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijingChina School of Future Technology University of Chinese Academy of SciencesBeijingChina School of Biomedical Engineering Tsinghua UniversityBeijingChina

Self-healing materials span diverse application fields,including flexible electronics,soft robotics,and energy ***,conventional self-healing materials pose a challenge in achiev-ing the delicate balance between flexibility and electrical ***,they also suffer from prolonged healing times,incomplete healing,and high manufacturing *** metals possess excellent self-healing capabilities owing to their unique combination of fluidic and metallic properties,high surface tension,and reversible solid-liquid phase change at room temperature,offering an intriguing material option for addressing the challenges associated with flexibility and elec-trical *** this review article,we comprehensively examine the domain of self-healing liquid metals from the standpoint of typical mechanisms underlying self-healing pro-cesses,as well as practical strategies employed for achieving such ***,we explore representative applications that showcase the potential of these materials while aiming to provide a valuable reference for advancing and enhancing the field of self-healing *** pro-spect along this direction is made.

关键词： Self-healing Liquid metal Smart materials

Precise orbit determination for low Earth orbit satellites using GNSS:Observations,models,and methods

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Astrodynamics 2024年第3期8卷 349-374页

作者： Xinyuan Mao Wenbing Wang Yang gao Technology and Engineering Center for Space Utilization Chinese Academy of SciencesBeijing100094China University of Chinese Academy of Sciences Beijing101408China

Spaceborne global navigation satellite system(GNSS)has significantly revolutionized the development of autonomous orbit determination techniques for low Earth orbit satellites for *** a state-of-the-art combination of GNSS observations and satellite dynamics,the absolute orbit determination for a single satellite reached a precision of 1 *** orbit determination(i.e.,precise baseline determination)for the dual satellites reached a precision of 1 *** paper reviews the recent advancements in GNSS products,observation processing,satellite gravitational and non-gravitational force modeling,and precise orbit determination *** key aspects have increased the precision of the orbit determination to fulfill the requirements of various scientific ***,recommendations are made to further investigate multi-GNSS combinations,satellite high-fidelity geometric models,geometric offset calibration,and comprehensive orbit determination strategies for satellite constellations.

关键词： low Earth orbit(LEO) precise orbit determination(POD) precise baseline determination(PBD) global navigation satellite system(GNSS) multi-GNSS satellite constellation

Experiment and Analysis of Compatibility between New Phase Change Mixed Molten Salt and 316L Stainless Steel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2024年第6期33卷 2259-2273页

作者： REN Chenxing ZHENG Chenghang gao Xiang State Key Laboratory of Clean Energy Utilization Zhejiang University Institute of Carbon Neutrality Zhejiang University Baima Lake Laboratory Zhejiang University

Molten salt is considered as a promising heat storage and heat transfer medium due to its efficient thermophysical *** order to study the compatibility of five new mixed molten salts obtained with KNO3,NaNO3,K2CO3,Ca（NO3）2·4H2O,ZnCl2,NaF,Na2CO3,NaCl and MgO as materials and 316L stainless steel,corrosion weight loss,scanning electron microscopy,elemental analysis and XRD were used to analyze the compatibility of 316L stainless steel in the new mixed molten salt at different time and *** corrosion behavior under the conditions was studied and *** compatibility data was obtained,and the corrosion mechanism of 316L stainless steel in mixed molten salts was *** results show that the corrosion weight of 316L stainless steel increases,and the corrosion degree of grain,crystal crack depth and oxidation degree increase gradually with the increase of temperature and *** corrosion of molten salt on alloy is mainly caused by the selective diffusion loss and corrosion of Cr,Fe and other elements,and is accompanied by the formation of different metal *** formation of metal oxides can slow down metal corrosion and loss to a certain *** corrosion results under different working conditions show that 316L stainless steel has good compatibility with the new mixed molten salt,and has certain application value in the field of heat transfer and energy storage.

关键词： 316L stainless steel corrosion resistance heat treatment molten salt

Implications of mosquito metabolism on vector competence

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Insect Science 2024年第3期31卷 674-682页

作者： Li gao Wenxu Yang Jingwen Wang State Key Laboratory of Genetic Engineering School of Life SciencesFudan UniversityShanghaiChina Ministry of Education Key Laboratory of Contemporary Anthropology School of Life SciencesFudan UniversityShanghaiChina

Mosquito-borne diseases(MBDs)annually kill nearly half a million *** to the lack of effective vaccines and drugs on most MBDs,disease prevention relies primarily on controlling *** huge efforts having been put into mosquito control,eco-friendly and sustainable mosquito-control strategies are still lacking and urgently *** mosquito-transmitted pathogens have lost the capacity of de novo nutrition biosynthesis,and rely on their vertebrate and invertebrate hosts for sustenance during the long-term obligate parasitism ***,a better understanding of the metabolic interactions between mosquitoes and pathogens will contribute to the discovery of novel metabolic targets or regulators that lead to reduced mosquito populations or vector *** review summarizes the current knowledge about the effects of mosquito metabolism on the transmission of multiple *** also discuss that research in this area remains to be explored to develop multiple biological prevention and control strategies for MBDs.

关键词： flaviviruses mosquito metabolism Plasmodium vector competence

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2024年第2期67卷 405-430页

作者： Junzhuo gao Lei Wang Heng Lian School of Statistics and Data Science&LPMC Nankai UniversityTianjin 300071China Department of Mathematics City University of Hong KongHong KongChina

In this paper, we consider the unified optimal subsampling estimation and inference on the lowdimensional parameter of main interest in the presence of the nuisance parameter for low/high-dimensionalgeneralized linear models (GLMs) with massive data. We first present a general subsampling decorrelated scorefunction to reduce the influence of the less accurate nuisance parameter estimation with the slow convergencerate. The consistency and asymptotic normality of the resultant subsample estimator from a general decorrelatedscore subsampling algorithm are established, and two optimal subsampling probabilities are derived under theA- and L-optimality criteria to downsize the data volume and reduce the computational burden. The proposedoptimal subsampling probabilities provably improve the asymptotic efficiency of the subsampling schemes in thelow-dimensional GLMs and perform better than the uniform subsampling scheme in the high-dimensional GLMs.A two-step algorithm is further proposed to implement, and the asymptotic properties of the correspondingestimators are also given. Simulations show satisfactory performance of the proposed estimators, and twoapplications to census income and Fashion-MNIST datasets also demonstrate its practical applicability.

关键词： A-optimality decorrelated score subsampling high-dimensional inference L-optimality massive data

维普期刊数据库

A cloud model target damage effectiveness assessment algorithm based on spatio-temporal sequence finite multilayer fragments dispersion

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第10期40卷 48-64页

作者： Hanshan Li Xiaoqian Zhang Junchai gao School of Electronic and Information Engineering Xi'an Technological UniversityXi'an710021China

To solve the problem of target damage assessment when fragments attack target under uncertain projectile and target intersection in an air defense intercept,this paper proposes a method for calculating target damage probability leveraging spatio-temporal finite multilayer fragments distribution and the target damage assessment algorithm based on cloud model *** on the spatial dispersion characteristics of fragments of projectile proximity explosion,we divide into a finite number of fragments distribution planes based on the time series in space,set up a fragment layer dispersion model grounded in the time series and intersection criterion for determining the effective penetration of each layer of fragments into the *** on the precondition that the multilayer fragments of the time series effectively assail the target,we also establish the damage criterion of the perforation and penetration damage and deduce the damage probability calculation *** the damage probability of the fragment layer in the spatio-temporal sequence to the target as the input state variable,we introduce cloud model theory to research the target damage assessment *** the equivalent simulation experiment,the scientific and rational nature of the proposed method were validated through quantitative calculations and comparative analysis.

关键词： Target damage Cloud model Fragments dispersion Effectiveness assessment Spatio-temporal sequence

维普期刊数据库

Numerical Study on the Impacts of Hydrometeor Processes on the“21·7”Extreme Rainfall in Zhengzhou Area of China

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2024年第10期41卷 2061-2078页

作者： Wenhua gao Chengyin LI Lanzhi TANG State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China

The impacts of hydrometeor-related processes on the development and evolution of the“21·7”extremely heavy rainfall in Zhengzhou were investigated using WRF *** precipitation was determined by the hydrometeor microphysical processes(all microphysical source sink terms of hydrometeors)and macrophysical processes(local change and flux convergence of hydrometeors).The contribution of hydrometeor macrophysical processes was commonly less than 10%,but could reach 30%–50%in the early stage of precipitation,which was largely dependent on the size of the study *** macrophysical processes of liquid-phase hydrometeors always presented a promotional effect on rainfall,while the ice-phase hydrometeors played a negative role in the middle and later stages of *** distributions of microphysical latent heat corresponded well with those of buoyancy and vertical velocity(tendency),indicating that the phase-change heating was the major driver for convective *** diagnostic buoyancy was obtained by choosing an area close to the convective size for getting the reference state of *** addition,a new dynamic equilibrium involving hydrometeors with a tilted airflow was formed during the heavy precipitation period(updraft was not the strongest).The heaviest instantaneous precipitation was mainly produced by the warm-rain *** experiments further pointed out that the uncertainty of latent heat parameterization(±20%)did not significantly affect the convective *** when the phase-change heating only altered the temperature tendency,its impact on precipitation was *** results of this study help to deepen our understanding of heavy rainfall mechanisms from the perspective of hydrometeor processes.

关键词： heavy precipitation hydrometeor processes buoyancy latent heat

维普期刊数据库