检索结果-南通市图书馆

Existence of unbiased estimate of regression parameters in simple linear EV models

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2005年第7期48卷 915-928页

作者： LIU Jixue & CHEN Xiru Department of statistics and Finance, university of Science and Technology of china, Hefei 230026, china Department of Mathematics, Graduate school of Chinese Academy of Sciences, beijing 100049, china Department of statistics and Finance University of Science and Technology of China Hefei 230026 China Department of Mathematics Graduate School Chinese Academy of Sciences Beijing 100049 China

It is well known that for one-dimensional normal EV regression model X = x+ u,Y =α+βx+e, where x, u, e are mutually independent normal variables and Eu=Ee=0, the regression parameters a and β are not identifiable without some restriction imposed on the parameters. This paper discusses the problem of existence of unbiased estimate for a and β under some restrictions commonly used in practice. It is proved that the unbiased estimate does not exist under many such restrictions. We also point out one important case in which the unbiased estimates of a and β exist, and the form of the MVUE of a and β are also given.

关键词： EV regression model unbiased estimate identiflability.

CABOSFV algorithm for high dimensional sparse data clustering

在线全文

学校读者我要写书评

暂无评论

Journal of university of Science and Technology beijing 2004年第3期11卷 283-288页

作者： Sen Wu Xuedong Gao Management school, university of Science and Technology beijing, beijing 100083, china Mgmt. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

An algorithm, Clustering Algorithm Based On Sparse Feature Vector (CABOSFV),was proposed for the high dimensional clustering of binary sparse data. This algorithm compressesthe data effectively by using a tool 'Sparse Feature Vector', thus reduces the data scaleenormously, and can get the clustering result with only one data scan. Both theoretical analysis andempirical tests showed that CABOSFV is of low computational complexity. The algorithm findsclusters in high dimensional large datasets efficiently and handles noise effectively.

关键词： clustering data mining sparse high dimensionality

UNIFORM　CONVERGENCY　FOR　WEIGHTED　PERIODOGRAM　OF　STATIONARY　LINEAR　RANDOM　FIELDS

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 1995年第3期16卷 331-340页

作者： HE SHUYUAN(Department of Probability and statistics, beijing university, beijing 100871, china.) beijing UNIV DEPT PROBABIL & STATBEIJING 100871PEOPLES R CHINA

Let {Xn; n ∈ N2} be a two dimensionally indexed linear stationary random field generated by a 1/4 martingale difference white noise. The logarithm uniform convergency resulte for the weighted periodogram of is proved.

关键词： Periodogram Random field Martingale difference Log-convergency.

Producing Calcium-Bearing Mullite Thermal-Insulating Refractories by Kyanite

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 50-53页

作者： Wen Ni (Resources Engineering school, university of Science and Technology beijing, beijing 100083, china) Resources Engineering school University of Science and Technology Beijing Beijing 100083 China

To improve the physical properties, a series of experiments have been camed out to produce calcium-bearing mullite thermal-insulating refractories by using kyanite as major raw materials. The experiments were carried out by a foaming technique and using white cement as a combing agent. The results show that the calcium-bearing mullite refractory has much better physical properhes than traditional clay refractory and high-alumina refractory.

关键词： mullite thermal-insulating refractory kyanite

Calculation Models of Mass Action Concentrations for Metallic Melts Involving Monotectic

在线全文

学校读者我要写书评

暂无评论

Journal of university of Science and Technology beijing 2001年第4期8卷 248-253页

作者： Jian Zhang Metallurgy school, university of Science and Technology beijing, beijing 100083, china Univ Sci & Technol beijing Met Sch Beijing 100083 Peoples R China

Based on the phase diagrams, measured activities as well asDeltaG(m) and DeltaG(xs), calculating models of mass action concentrations for metallic melts involving monotectic have been formulated. The calculated results agree with practice on the whole, showing that the models deduced generally can reflect the structural characteristics of these melts. The metastable compounds formed in the melts are of the types A(2)B(3), AB(2), A(2)B(3) or AB and A(2)B(3)+AB etc..

关键词： metallic melts monotectic activity mass action concentration

Fractal Structure of the Core Loss Spectrum of Co-based Amorphous Soft Magnetic Alloy with Constant Permeability

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 54-56页

作者： Yiping Chen (Applied Science school, university of Science and Technology beijing, beijing 100083, china) Applied Science school University of Science and Technology Beijing Beijing 100083 China

In order to check the traditional core loss formula, the core loss spectrum P(f) of Co-based amorphous soft magnetic alloy with constant permeability has been studied. It is found that within a high frequency range from 10 kHz to 200 kHz and at Bm = 0. 1 T,the P(f) has the fractal structure P (f) = Po, and with the increasing of induced anisotropy energy Ku, the fractal dimension Dfrises, thus the total power loss at high frequency increases and the frequency characteristic of P(f) becomes worse.

关键词： amorphous soft magnetic alloy constant permeability core loss fractal

A New Safety Electric Initiating System

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 1999年第4期13卷 306-308页

作者： Daze Lin(Resource Engineering school, university of Science and Technology beijing, beijing 100083, china) Univ of Science and Technology Beijing Beijing China

Based on the analysis of weakness on the safety of traditional electric detonators, a BJ-l safety electric detonator initiatingsystem and its corresponding safe examination technique were successfully developed. By leading false foot wires and taking advantageof the transmitting frequency band of Mo-Zn ferrite, detonators in this new system can completely impede the direct induction of outsidecrosstalk that may cause casual firing in the ordinary as well as eleclromagnetic ones. Possible causality by lightning was discussed. Results are presented, of its safety tests on resistance to direct and alternating current, electrostatic, and crosstalk induced by damp leakagein saturated salty water.

关键词： electric detonator blasting engineering, electric initiating system, safety

REGULARITY OF SOLUTIONS TO THE DIRICHLET PROBLEM FOR DEGENERATE ELLIPTIC EQUATION

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2003年第4期24卷 529-540页

作者： CHEN YEMIN school of Mathematics, Peking university, beijing 100871, china. Peking Univ Sch Math Beijing 100871 Peoples R China

In this paper, the author studies the regularity of solutions to the Dirichlet problem forequation Lu = f, where L is a second order degenerate elliptic operator in divergence form inΩ, a bounded open subset of Rn (n... 详细信息

关键词： Regularity Dirichlet problem Degenerate Weighted spaces

Convergence rates for reversible Markov chains without the assumption of nonnegative definite matrices

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2010年第8期53卷 1979-1988页

作者： MAO Yong-Hua school of Mathematical Sciences,beijing Normal university,Laboratory of Mathematics and Complex Systems,Ministry of Education,beijing 100875,china 1. school of Mathematical Sciences Beijing Normal University Laboratory of Mathematics and Complex Systems Ministry of Education Beijing 100875 China

Explicit convergence rates in geometric and strong ergodicity for denumerable discrete time Markov chains with general reversible transition matrices are obtained in terms of the geometric moments or uniform moments of the hitting times to a fixed *** way by Lyapunov's drift conditions is also used to derive these convergence *** a typical example,the discrete time birth-death process(random walk) is studied and the explicit criteria for geometric ergodicity are presented.

关键词： Markov chain spectral theory convergence rate geometric ergodicity strong ergodicity Lyapunov’s condition