Table of Content

20 September 2001, Volume 37 Issue 5

Previous Issue    Next Issue

Retaining Sampled Units for Changed Probability and the Optimum Matching Ratio in Successive Sampling Survey

YANG Baohui

2001, 37(5):  587-592. 

Asbtract ( )  

Related Articles | Metrics

The method for retaining sampled units in successive sampling survey for changed probability of selection is introduced. For PPS sampling design, a model-design unbiased predictor for the total of a variable for the target population is proposed, and the optimum matching ratio for the predictor under the assumption of unchanged population is calculated. For RHC sampling design, the equation that the optimum matching ration satisfies is given.

Rates of Total Variation Convergence of Order Statistics with Fixed Rank

JIANG Changguo,CHENG Shihong

2001, 37(5):  593-603. 

Asbtract ( )  

Related Articles | Metrics

It is gotten that the rates of total variation of order statistics with fixed rank depending on regular variation of second order. Especialy, the rates of total variation for distribution of extreme values is gotten too.

Existence and Uniqueness for A Class of Degenerate Divergence Elliptic Equations

NI Guoxi

2001, 37(5):  604-608. 

Asbtract ( )  

Related Articles | Metrics

Existence and uniqueness are proved by Lax-Milgram theorem for a type of degenerate divergence elliptic equation in a type of Sobolev spaces with weight, and also the regularity will be studied.

Compound Poisson Approximation of Individual Risk Models

LI Xiande,YANG Jingping

2001, 37(5):  609-617. 

Asbtract ( )  

Related Articles | Metrics

Individual risk models' approximation by Compound Poisson approximation is discussed. Three principles are presented, and the optimal choice of Poisson parameters under the three principles is discussed. It is proved that the individual risk model is also a compound binomial model; And formulas on the calculation of the optimal parameters are given. For two distributions, Exponential and Pareto, calculating results are given.

Asymmetric Digital Watermark

CUI Xiaoyu,CHENG Qiansheng

2001, 37(5):  618-622. 

Asbtract ( )  

Related Articles | Metrics

Aiming at the low efficiency in current architectures of digital watermarking, it provides a new architecture—asymmetric digital watermark. This architecture has the third trusted party as the center. And by using two watermarks(secret watermark and public watermark)and “watermark browser”, users can independently extract and display the intellectual property information hidden in the digital multimedia. It not only makes the intellectual property information public, but also highly improves the efficiency. In the results, this architecture can protect the intellectual property of creators, avoid users from unauthorized use, and regular the authentication and the management of the intellectual property.

On Elementary Submodels of A Lattice-valued Model for Language L(Q)

XIE Huiyang,WANG Hanpin

2001, 37(5):  623-629. 

Asbtract ( )  

Related Articles | Metrics

The two-value weak model for first order logic with generalized quantifier Q is generalized to be valued in complete weak complemented lattices. For finite linearly-ordered weak complemented lattice, some properties on elementary extension of models for L(Q), such as strong downward L-S-T Theorem and the preservation of the elementary diagram under elementary extensions, are discussed.

Bayes Solution to A Continuous Time Sequential Problem

LIU Liping

2001, 37(5):  630-638. 

Asbtract ( )  

Related Articles | Metrics

The problem of Bayes sequential decision rules to hypothesis testing is often reduced to the problem of optimal stopping. In continuous time situation, the existence of Bayes solution is proved by using the general stochastic process theory. In distinguishing among two exponential distributions, the Bayes solutions are found out in different situations as an example, which also shows that the uniqueness of solution does not hold in general.

A Note on the Divisor Function d_k(n)

MENG Zaizhao

2001, 37(5):  639-642. 

Asbtract ( )  

Related Articles | Metrics

Let d_k(n) denote the k-fold iterated divisor function(k≥2). It is proved that for sufficiently large x, {d_k(n)=d_k(n+1), k≥2} hold for ≥x(loglogx)^-2.5 integers n≤x。

Bayesian Estimation of A Circle

TONG Xingwei,ZHENG Zhongguo

2001, 37(5):  643-647. 

Asbtract ( )  

Related Articles | Metrics

It is shown how to use bayesian theorem in estimating the parameters of a circle when angular differences between successive data points are known. The posterior distribution of the radius and consequently the confidence interval for the radius are derived.

On the Average-shadowing Property

ZHANG Yong

2001, 37(5):  648-651. 

Asbtract ( )  

Related Articles | Metrics

It is proved that a homeomorphism on a compact metric space with the average-shadowing property has only one chain component which is the whole space. In particular, every point is chain recurrent. Using this result it is given a short proof for a recent theorem of Sakai.

Buoyancy Instability in the Natural Convection Boundary Layer around A Heated Vertical Flat Plate

YAN Dachun,ZHANG Hanxun

2001, 37(5):  652-657. 

Asbtract ( )  

Related Articles | Metrics

An experimental investigation on the buoyancy instability in the natural convection boundary layer is presented, including its basic characteristics such as power spectrum, wavelength, phase velocity and related critical layers, and its developing process of growth and dissipation with the variation of Grash of number. Results indicate that the natural convection boundary layer becomes unstable due to buoyancy at a critical modified Grashof number G around 40; the neutral curve obtained by the growth rates of the temperature fluctuation has a ring-like curve separated from the main branch of Nachtsheim's calculation by velocity fluctuation at the lower Grashof number side; and its phase velocity is close to the maximum mean velocity where the critical layer of the eigenmode locates. The thermal fluctuation decays rapidly as the non-dimensional frequency above 0.4, so that it means that the coupling effect between instability wave generated by buoyancy fluctuation and velocity waves by invicid instability seems weak enough for their critical layers in the range of the non-dimensional frequency B＜0.4.

The Calculation of Transport for Curved Tubes with Permeable Arterial Wall

WANG Xin,HUANG Hao,WEN Gongbi

2001, 37(5):  658-668. 

Asbtract ( )  

Related Articles | Metrics

The transport of macromolecules in curved tubes with permeable arterial wall was simulated numerically. The fields of axial velocity, the fields of secondary flow function and the distribution of wall shear stress along the transverse section of arterial wall were obtained under different Dean number, 10≤De≤10800. The concentration fields under different Dean number and Peclet number, 10≤De≤2 000，1≤Pe≤4，were calculated in curved tube with permeable arterial wall and effects of parameters,such as shear stress, mass flux of arterial wall, on mass transfer were studied. It was found that steady laminar flow become unsteady with the increase of De. The concentration in inner section of transverse section of the tube is higher than other areas, and with the increase of De and Pe, the concentration there increase obviously. It indicates that for the permeable arterial wall, the macromolecules are likely to gather in the areas where axial velocity and shear stress are relatively low, thus indicates why location of atherosclerosis frequently occurs at inner side of curved tube.

A Voronoi Cells Based C^∞ Interpolation Basis Function and Its Application in CFD

ZHU Huaiqiu,WU Jianghang

2001, 37(5):  669-678. 

Asbtract ( )  

Related Articles | Metrics

According to the ideal of Natural Neighbor Interpolation, based on the geometric characteristics of Voronoi cells, this paper describes a C^∞ interpolation basis function, which is smooth and continuously differentiable everywhere except at its defining node. The parametric expression of first derivatives of the interpolation basis function is also given. The new theory for function and derivative interpolation has application in CFD to develop a novel Finite Element Method (FEM) which is called Natural Element Method (NEM). In addition, it demonstrates that the C^∞ interpolation basis function can be the promising role in a range of visualization problems of CFD.

Methodological Study on the Estimate of Regional Surface Fluxes over Yhe HUAIHE River Basin Area with Satellite Remote Sensing

HONG Gan,LI Wanbao,ZHU Yuanjing,ZHAO Bolin

2001, 37(5):  693-700. 

Asbtract ( )  

Related Articles | Metrics

To improve understanding of the processes of heterogeneous land surface-atmosphere interaction, the utilization of satellite remote sensing is indispensadle. In this paper, With the aid of satellite remote sensing and fiend observational data which observed during intensive observation of Huaihe River Bain energy and Water Cycle Experiment(HUBEX) in 1998, the surface albedo, NDVI(Normalized Difference Vegetaton Index) and surface temperature in regional scale of HUBEX could be derived. Then, the distribution of regional energy balance components could be estimated. This work provided the physical foundation for the numerical simulation of the Huaihe river basin energy and water processes, and is important for us to further analyze the regional distribution of surface characteristic parameters ad energy balance components with the change of the weather situation in HUBEX in 1998. Our work is still in a developing stage, some methods of retrieval in the paper should be improved further.

High Surface Hole Concentration P-type GaN Using Mg Implantation

LONG Tao,YANG Zhijian,ZHANG Guoyi

2001, 37(5):  701-704. 

Asbtract ( )  

Related Articles | Metrics

Mg ions were implanted on Mg-doped GaN grown by metalorganic chemical vapor deposition(MOCVD). The p-type GaN was achieved with high hole concentration(8.28×10¹⁷cm^-3)conformed by Van der pauw Hall measurement after annealing at 800℃ for 1h. This is the first experimental report of Mg implantation on Mg-doped GaN and achieving p-type GaN with high surface hole concentration.

Hemodynamics Factor in Acute Intracranial Hemorrhage Occuring when Cerebral AVM is Embolized

SUN Shujin,YAN Zongyi,WANG Daming,LING Feng

2001, 37(5):  679-684. 

Asbtract ( )  

Related Articles | Metrics

The hemodynamic change induced by embolization of the cerebral arteriovenous malformation(AVM) was analyzed using the Water Hammer principle. The highest pressure that can be reached when the water hammer phenomenon occurs was calculated. The acute instantaneous pressure rising may be an important factor leading to intracranial hemorrhage or swelling when the AVM is embolized. It is shown that long feeding artery of AVM will increase the possibility of direct water hammer, and high wall shear stress of feeding artery will increase the water hammer pressure. This suggests that such kind of AVMs should be embolized stepwise and the systemic pressure should be rationally reduced before embolization.

The Climatic Characteristics of the Equatorial Zonal Circulation Retrieved with IR and WV Channels on Satellite

SHANG Shurong,JIANG Shangcheng

2001, 37(5):  685-692. 

Asbtract ( )  

Related Articles | Metrics

The equatorial zonal circulation is an important component of the tropical general circulation. It's activity and variation are effected both on the anomalies of the mid-high latitudes and the global general circulation. Due to the lack of traditional observation, it is actually not true to describe the zonal circulation over the tropics with conventional data. The OLR observed by satellite observations is appropriate for indicating the convection upward motion over tropics but not for describing the descending motion. It is possible to describe the subsidence over tropics by using HIRS-T_b12 (High-resolution Infra-red Radiation Sounder—HIRS, channel 12, 6.7μm bright temperature T_b12) observed by NOAA satellite. So that the equatorial zonal circulation can be retrieved both with IR and WV channels on the satellite. The climatic characteristics of the equatorial zonal circulation are studied by using monthly 17 years (1979—1995) OLR, HIRS-T_b12 and NCEP/NCAR 2.5°×2.5°reanalysis data.Comparing the OLR, FWV (calculated by HIRS-T_b12 and 500hPa ω climatic mean map, it is further confirmed that it's a good approach to retrieve the equatorial zonal circulation by using the IR(indicate ascending branch) and WV(indicate descending branch) channels. The definition of the index of zonal circulation with the OLR and FWV are presented and the 17 years mean annual and seasonal equatorial circulation are drawn. The climatic characteristics of the equatorial zonal circulation are analyzed in detail. Consequently the fore results of the other observation are corrected.

The Characteristics of Field-aligned Currents during the Substorms

JIAO Weixin,PU Zuyin,GAO Chao

2001, 37(5):  705-709. 

Asbtract ( )  

Related Articles | Metrics

The characteristics of the field-aligned currents (FACs) measured by ISEE 1 and 2 satellites during substorms are studied. These characteristics include the variations of FACs with the Interplanetary Magnetic Field(IMF), local time, L-value, and the current density and intensity versus the substorm phases. Moreover, the characteristics of substorm current wedge are given special attention. It is found that the density and intensity of FACs reach their peak during the expansion phase, the onset of the expansion phase is triggered when IMF is changed to southward from northward or the southward IMF decreases, and the positions of onset are most likely to be at the edge of plasma sheet near the earth.

Tide Stress of the Radially Heterogeneous Spherical Elastic Earth Model

WU Qingpeng

2001, 37(5):  710-715. 

Asbtract ( )  

Related Articles | Metrics

Radially heterogeneous spherical earth model approaches to the real earth very closely. Using the method proposed by Alternan this paper has derived formulas for the calculation of the tide stress in such an earth model. On the basis of these formulas the tide stress inside the GB earth model has been calculated as an example.

Obtaining Ultra-cold Atoms by Optical Molasses Directly from Vapor

HOU Jidong,WANG Xiaohui,CHEN Xuzong,YANG Donghai,WANG Yiqiu

2001, 37(5):  716-720. 

Asbtract ( )  

Related Articles | Metrics

Usually the magneto-optical trap(MOT)is used to obtain the cold atoms from the vapor. It is reported that experiments for obtaining the ultra-cold cesium atoms by optical molasses directly from the vapor cell without MOT. The lowest temperature achieved for the cesium atomic cloud was 3μK. The relationship between the temperature and the detuning of cooling laser was measured.

The Graph Form of A Blocking Optical Cross-connector

TAO Zhenning,WU Deming,XU Anshi

2001, 37(5):  721-726. 

Asbtract ( )  

Related Articles | Metrics

The concept of the graph form of a blocking optical cross-connector is introduced so as to investigate the blocking situation. The principle is that the blocking node can be replaced by a graph which is composed of nonblocking nodes and capacity limited edges. Three graphs of typical optical cross-connector nodes are demonstrated. Several uniform result are derived from these examples.

The Computer Aided Research Work of Chinese Ancient Poems

HU Junfeng,YU Shiwen

2001, 37(5):  727-733. 

Asbtract ( )  

Related Articles | Metrics

Based on 6.4 million chars of Chinese ancient poetry, the “Computer aided research system of Chinese ancient poems” provides a word-based analysis platform of Chinese ancient poems. More than 50000 Chinese words, including 40814 multi-char words, were extracted from the corpora via statistic method. Besides the full text retrieving function, the system also provide word-based statistic analysis, sentence based similarity retrieving, automatic Pinyin tagging and some other useful functions to benefit the profound analysis of the Chinese ancient poems. The National Social Science Foundation of China 1998-1999 funded the project.

The 3^rd Generation Search Engine and WebGather Version 2.0

LEI Ming,WANG Jianyong,ZHAO Jianghua,SHAN Songwei,CHEN Baojue

2001, 37(5):  734-740. 

Asbtract ( )  

Related Articles | Metrics

With the rapid growing of WWW, significant progress has been made in search engine research area. The evolvement of search engine and the system architecture for the 3^rd generation are reviewed. More emphasis will be given on some core technologies related to search engines of the 3^rd generation. For example, the massive and efficient web-crawling technology, the method of hyper-link analysis, and the user behavior analyzing technology will be described in detail. In addition, it is also presented the recent research progress of WebGather, which is a typical search engine of 3^rd generation. Several research hotspots for future search engine systems are pointed out in the conclusion.

The 3^rd Generation Search Engine and WebGather Version 2.0

LEI Ming,WANG Jianyong,ZHAO Jianghua,SHAN Songwei,CHEN Baojue

2001, 37(5):  734-740. 

Asbtract ( )  

Related Articles | Metrics

With the rapid growing of WWW, significant progress has been made in search engine research area. The evolvement of search engine and the system architecture for the 3^rd generation are reviewed. More emphasis will be given on some core technologies related to search engines of the 3^rd generation. For example, the massive and efficient web-crawling technology, the method of hyper-link analysis, and the user behavior analyzing technology will be described in detail. In addition, it is also presented the recent research progress of WebGather, which is a typical search engine of 3^rd generation. Several research hotspots for future search engine systems are pointed out in the conclusion.