检索结果-南通市图书馆

Alternative non-Gaussianity measures for quantum states based on quantum fidelity

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第3期31卷 192-200页

作者： Cheng Xiang shan-shan Li sha-sha Wen shao-Hua Xiang College of Electrical and information Engineering Huaihua UniversityHuaihua 418008 China Hunan Provincial Key Laboratory of Ecological Agriculture intelligent Control Technology Huaihua 418008China

We propose three alternative measures for non-Gaussianity of quantum states: sine distance, Bures angle, and Bures distance, which are based on quantum fidelity introduced by Wang [Phys. Lett. A 373 58(2008)]. Using them, we evaluate the non-Gaussianity of some relevant single-mode and two-mode non-Gaussian states and find a good consistency of the three examined measures. in addition, we show that such metrics can exactly quantify the degree of Gaussianity of even Schrödinger-cat-like states of small amplitudes that can not be measured by other known non-Gaussianity measures such as the hilbert–Schmidt metric and the relative entropy metric. We make a comparative study between all existing nonGaussianity measures according to the metric axioms and point out that the sine distance is the best candidate among them.

关键词： non-Gaussianity quantum fidelity non-Gaussian states sine metric

Spectral Gap and Logarithmic Sobolev Constant for Continuous Spin Systems

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2008年第5期24卷 705-736页

作者： Mu fa CHEN School of Mathematical Sciences Beijing Normal University Beijing 100875 P. R. China

The aim of this paper is to study the spectral gap and the logarithmic Sobolev constant for continuous spin systems. A simple but general result for estimating the spectral gap＇of finite dimensional systems is given by Theorem 1.1, in terms of the spectral gap for one-dimensional marginals. The study of this topic provides us a chance, and it is indeed another aim of the paper, to justify the power of the results obtained previously. The exact order in dimension one （Proposition 1.4）, and then the precise leading order and the explicit positive regions of the spectral gap and the logarithmic Sobolev constant for two typical infinite-dimensional models are presented （Theorems 6.2 and 6.3）. Since we are interested in explicit estimates, the computations become quite involved. A long section （Section 4） is devoted to the study of the spectral gap in dimension one.

关键词： spectral gap logarithmic Sobolev constant spin system principal eigenvalue

Lower bounds of principal eigenvalue in dimension one

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2012年第4期7卷 645-668页

作者： Mu-fa CHEN School of Mathematical Sciences Beijing Normal UniversityLaboratory of Mathematics andComplex Systems(Beijing Normal University)Ministry of EducationBeijing 100875China

For the principal eigenvalue with bilateral Dirichlet boundary condition, the so-called basic estimates were originally obtained by capacitary method. The Neumann case （i.e., the ergodic case） is even harder, and was deduced from the Dirichlet one plus a use of duality and the coupling method. in this paper, an alternative and more direct proof for the basic estimates is presented. The estimates in the Dirichlet case are then improved by a typical application of a recent variational formula. As a dual of the Dirichlet case, the refine problem for bilateral Neumann boundary condition is also treated. The paper starts with the continuous case （one-dimensional diffusions） and ends at the discrete one （birth-death processes）. Possible generalization of the results studied here is discussed at the end of the paper

关键词： Principal eigenvalue lower estimate variational formula one- dimensional diffusion birth-death process

Simulation of macrosegregation in a 36-t steel ingot using a multiphase model

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 Minerals,Metallurgy and Materials 2020年第2期27卷 200-209页

作者： Zhuo Chen Hou-fa Shen Key Laboratory for Advanced Material Processing Technology Ministry of Education School of Material Science and Engineering Tsinghua University

Macrosegregation is the major defect in large steel ingots caused by solute partitioning and melt convection during *** this study,a three-phase(liquid,columnar dendrites,and equiaxed grains)model is proposed to simulate macrosegregation in a 36-t steel ingot.A supplementary set of conservation equations are employed in the model such that two types of equiaxed grains,either settling or adhering to the solid shell,are well *** predicted concentration agrees quantitatively with the experimental value.A negative segregation cone was located at the bottom owing to the grain settlement and solute-enriched melt leaving from the mushy *** interdendritic liquid flow was carefully analyzed,and the formation of A-type segregations in the mid-height of the ingot is *** segregation was observed near the riser neck due to the specific relationship between flow direction and temperature ***,the as-cast macrostructure of the ingot is presented,including the grain size distribution and columnar–equiaxed transition.

关键词： macrosegregation multiphase model transportation solidification steel ingot

Comparison of some properties of star forming galaxies and active galactic nuclei between two BOSS galaxy samples from SDSS DR9

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2014年第4期14卷 401-410页

作者： Xin-fa Deng School of Science Nanchang University

Using the LOWZ and CMASS samples of the ninth data release （DR9） from the SDSS-iii Baryon Oscillation Spectroscopic Survey （BOSS）, i investigate properties of star forming galaxies and active galactic nuclei （AGNs）. The CMASS sample seriously suffers from the radial selection effect, even within the redshift 0.44 〈 z 〈 0.6, which will likely lead to statistical conclusions in the CMASS sample being less robust. in the LOWZ sample, the fraction of star-forming galaxies is nearly constant from the least dense regime to the densest regime; the AGN fraction is also insensitive to the local environment. in addition, i note that in the LOWZ sample, the distributions of stellar mass and stellar velocity dispersion for star forming galaxies and AGNs are nearly the same.

关键词： galaxies: active- galaxies: statistics

Efficient initials for computing maximal eigenpair

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2016年第6期11卷 1379-1418页

作者： Mu-fa CHEN School of Mathematical Sciences Beijing Normal University Laboratory of Mathematics and Complex Systems (Beijing Normal University) Ministry of Education Beijing 100875 China

This paper introduces some efficient initials for a well-known algorithm （an inverse iteration） for computing the maximal eigenpair of a class of real matrices. The initials not only avoid the collapse of the algorithm but are also unexpectedly efficient. The initials presented here are based on our analytic estimates of the maximal eigenvalue and a mimic of its eigenvector for many years of accumulation in the study of stochastic stability speed. in parallel, the same problem for computing the next to the maximal eigenpair is also studied.

关键词： Perron-Frobenius theorem power iteration rayleigh quotient iteration efficient initial tridiagonal matrix Q-matrix

The Optimal Constant in Hardy-type inequalities

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2015年第5期31卷 731-754页

作者： Mu-fa CHEN School of Mathematical Sciences Beijing Normal University

To estimate the optimal constant in Hardy-type inequalities, some variational formulas and approximating procedures are introduced. The known basic estimates are improved considerably. The results are illustrated by typical examples. it is shown that the sharp factor is meaningful for each finite interval and a classical sharp model is re-examined.

关键词： Hardy-type inequality optimal constant variational formulas approximating procedure

Constructing an Educational Knowledge Graph with Concepts Linked to Wikipedia

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2021年第5期36卷 1200-1211页

作者： Fu-Rong Dang Jin-Tao Tang Kun-Yuan Pang Ting Wang sha-sha Li Xiao Li College of Computer Science and Technology National University of Defense TechnologyHunan 410073China information Center National University of Defense TechnologyHunan 410073China

To use educational resources efficiently and dig out the nature of relations among MOOCs(massive open online courses),a knowledge graph was built for MOOCs on four major platforms:Coursera,EDX,XuetangX,and *** paper demonstrates the whole process of educational knowledge graph construction for *** this knowledge graph,the largest knowledge graph of MOOC resources at present,stores and represents five classes,11 kinds of relations and 52779 entities with their corresponding properties,amounting to more than 300000 ***,24188 concepts are extracted from text attributes of MOOCs and linked them directly with corresponding Wikipedia entries or the closest entries calculated semantically,which provides the normalized representation of knowledge and a more precise description for MOOCs far more than enriching words with explanatory ***,prerequisites discovered by direct extractions are viewed as an essential supplement to augment the connectivity in the knowledge *** knowledge graph could be considered as a collection of unified MOOC resources for learners and the abundant data for researchers on MOOC-related applications,such as prerequisites mining.

关键词： concept extraction educational resource knowledge graph massive open online course(MOOC) prerequisite

Management of CO_(2) in a tomato greenhouse using WSN and BPNN techniques

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 Agricultural and Biological Engineering 2015年第4期8卷 43-51页

作者： Li Ting Zhang Man Ji Yuhan sha sha Jiang Yiqiong Li Minzan Key Laboratory of Modern Precision Agriculture System integration Research Ministry of EducationCollege of Information and Electrical EngineeringChina Agriculture UniversityBeijing 100083China

rational management of CO_(2) can improve the net photosynthetic rate of plants,thereby improving crop yield and *** order to precisely manage CO_(2) in a greenhouse,a wireless sensor network(WSN)system was developed to monitor greenhouse environmental parameters in real time,including air temperature,humidity,CO_(2) concentration,soil temperature,soil moisture,and light *** WSN system includes several sensor nodes,a gateway node,and remote management *** sensor nodes can collect 0-5 V and 4-20 mA analog signals and universal asynchronous receiver/transmitter(UART)*** gateway node can process and transmit the data and commands between sensor nodes and remote management *** remote management software provides a friendly interface between user and *** can inquire about real-time data,and set the parameters of the *** photosynthetic rate of tomato plants were studied in the flowering stage.A Li-6400XT portable photosynthesis analyzer was used to measure the photosynthetic rates of the tomato plants,and the environmental parameters of leaves were controlled according to the presetting *** photosynthetic rate prediction model of a single leaf was established based on a back propagation neural network(BPNN).The environmental parameters were used as input neurons after being processed by principal component analysis(PCA),and the photosynthetic rate was taken as the output *** performance of the prediction model was evaluated,and the results showed that the correlation coefficient between the simulated and observed data sets was 0.9899,and root-mean-square error(RMSE)was ***,when different CO_(2) concentrations were selected as the input to predict the photosynthetic rate,the simulated and observed data showed the same *** to the above analysis,it was concluded that the model can be used for quantitative regulation of CO_(2) for tomato plants in greenhouses.

关键词： WSN ZigBee greenhouse information photosynthetic rate CO_(2)fertilization