Table of Content

20 September 2003, Volume 39 Issue 5

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Retrieval of Atmospheric Vertical Temperature Profileover Ocean with Satellite Remote Sensing

LI Wanbiao,WU Longtao,ZHANG Chengxiang,YU Jiayu

2003, 39(5):  656-665. 

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Statistical and physical retrievalalgorithms are the two methods being widely used to retrieve the atmospheric vertical temperature profile. This paper presents a retrieval algorithm: physical statistical retrieval algorithm. This algorithm uses one-off lab simulation data derived from physical retrieval algorithm instead of historical data from statistical algorithm. Using statistical algorithm to work out the matrix of retrieval coefficient, then the authors can directly carry through real time retrieval from the matrix.

A Class of New Approach for Image Restoration Based on CNN

WANG Haiming,YU Daoheng,GUO Shide

2003, 39(5):  666-674. 

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A new class of approach for image restoration based on two-dimensional Cellular Automata (CA) is proposed. By researching two new kinds of two-dimensional CA, we find two new classes of CA rules to design CNN, which can implement image restoration. The main idea is to design two CNNs with two antithetic CA rules. By this way, Image restoration can be implemented, getting obviously better results than the traditional ones. The simulation results prove our idea reasonable. It is expected to have profound influence on the technology of two-dimensional CA.

The R-Coring and the ×_R-Hopf Algebra

YIN Yanmin,LIU Zhangju

2003, 39(5):  624-634. 

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It is proved that the category of the left comodules over the ×_R-bialgebra L is equivalent to the category of the left L^*-modules, and the monoidal functor from ^L_AM to A#L^*-module is equivalent.For the ×_R-Hopf algebras the generalization of the fundamental structure theorem of Hopf modules is given by introducing the definition of antipode.

A Model of Access Control Systems Based on Group Signatures

WEI Jinwei,QIU Zongyan

2003, 39(5):  635-640. 

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It is described that a practical application of the algorithm of Group Signatures in Access Control System(ACS). The first part includes an introduction on the concepts of Group Signature and ACS, and an analysis of the weakness of current ACS; then there is a description of the proposed model of access control system based on group signatures. In this description, the system, the format definition, the flow description and the characters of it are described, including an analysis on its virtue and weakness.

An Experimental Investigation on Properties of
Strake Vortices Using Particle Image Velocimetry

LI Yiming,SUN Zhili,YAN Dachun

2003, 39(5):  641-648. 

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An experimental investigation on the properties of vortices generated by the strake-wing has been carried out in the wind tunnel using Particle Image Velocimetry (PIV). Measurements of flowfield in the cross-sections vertical to the axes of the model have been made with various attack-angles at the trailing edge of the strake, the 1/2 mean aerodynamics chord of the basic wing and also the leading and trailing edges of the vertical tail. Two-dimensional spectrum analysis has been used to calculate the energy spectra of the flowfield with the strake vortices in the wavenumber space. Results indicate that the strength of the strake vortex increases with a quadric function of the attack angle and the type of vortex breakdown is spiral breakdown in this experiment.

Three-Dimensional Numerical Simulation of Hemodynamics for Intracranial Lateral Aneurysms

WEN Gongbi,LI Junxiu,CHEN Wei

2003, 39(5):  649-655. 

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Hemodynamics of intracranial lateral aneurysms was simulated numerically. The blood was considered as Newtonian fluid and the elasticity of the wall was neglected. Three-dimension N-S equations were solved by using artificial compressibility algorithm. The influence of aneurysmal geometry shape and Reynolds number on hemodynamic factors, such as shear stress on the wall, pressure were calculated in the static and pulsatile conditions. The main results were that the greater depth of intracranial aneurysm, the greater distal shear stress is in which the aneurysm grow up and rupture for the intracranial aneurysms in the early stage in both static and pulsatile conditions; the pulsatile make the variety of distal shear stress with space and time more violent and easier rupture. The distal shear stress of aneurysm increases while the arterial diameter decrease and the velocity keep constant. It shows that the intracranial aneurysm is easier grow in small artery than that in the bigger blood tube. This result is consistent with physiology.

A Cointegration Analysis among Four Exchange Rates and Four Stock Indices

TANG Hongmin,SUN Zhaoli

2003, 39(5):  601-606. 

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The long run relationships of two empirical data sets are investigated respectively.The first one is the exchange rates of Duetsche Mark(Mark), Japanese Yen(Yen), Swiss France(Sf) and Sterling (Ster) between January 3, 1994 and June 5, 1995. Thesecond dataset is the four stock indices between January 4, 1994 and July 31, 1997: Dow Jones Averages 30 Industrials (DJI), Nasdaq composite (IXIC), Nikkei 225(N225) and Hengseng (HSI). In the end there exist cointegrations between Mark and Sf, DJI and HSI, IXIC and HSI.

New Provably Secure Signature Scheme

HAN Song,WANG Jie,GAO Li

2003, 39(5):  607-611. 

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A new mathematical problem-Decisional Relevant-RSA problem was introduced to construct a new signature scheme. It is simple and secure against adaptive chosen-message attacks. In addition its security proof is in the standard model.

Fisher Information for Censored Data from Location Scale Families

WANG Yanhua,HE Shuyuan,MEI Changlin

2003, 39(5):  612-619. 

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Lifetime data with time and failure censoring arises frequently in the controlled lifetime study. The Fisher information matrix I^M(θ) of this data is more complex than that of the typeⅠcensored data. For Location-Scale distribution families, we prove that the asymptotic Fisher information I^M(θ) equals typeⅠcensored Fisher information matrix. The results can be extended to Log Location-Scale family, such as Weibull and Lognormal distributions.

Segal-Bargmann Transform on Covering Groups

LIU Weiping

2003, 39(5):  620-623. 

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Hall has generalized the classical coherent state transform (or Segal-Bargmann transform) on compact Lie Groups and used geometric methods to prove its isometry. The isometry of Bargmann tranform on connected Lie Groups that have compact Lie algebras is proved from the point of view of covering groups.

A XML Based Presentation Technique for Mathematical Expressions on Web Page

LI Junguo,ZHANG Li'ang

2003, 39(5):  675-680. 

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There are two ways to present mathematical expressions on web page now, i.e. as an image or installing special plug-ins on web browser. To make up for the shortage of both methods, a solution named WebMath is presented. Based on XML and implemented in Java language and the support of the IBM's XML4J parser and Java Applet technology, WebMath is implemented and integrated in web page editor tools. This thesis provides WebMath's framework and a technical solution.

Comparisons of Two Smoothing Algorithms for Optimization in One-Dimensional Space

CUI Peng,ZHANG Li'ang,JI Lijiu,GAO Li

2003, 39(5):  681-689. 

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The smoothing method is a heuristic method for global optimization, which is much applicable in the research area of molecular conformations. The diffusion equation method (DEM) and the neighborhood averaging method (NAM) are two kinds of implementations of the smoothing method. The properties of the neighborhood averaging method and the efficiency of the two implementations in one-dimensional space are given. For Griewank-like functions, the optimization results of NAM as a whole excel DEM.

A New Method of Using Pitch Period in Text-Independent Speaker Identification System

DUAN Xin,HUANG Xinyu,WU Shuzhen

2003, 39(5):  690-696. 

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A new method of using pitch period in Text-independent Speaker Identification System is presented. When training, estimate a Gaussian probability density function for pitch period of every person in the training library. When testing, use probability density calculated in the pitch period probability model to weight the likelihood measure of VQ or GMM. Then use the new likelihood measure to identify the testing speech. The experimental results show that this method can improve the recognition rate greatly compared with VQ and GMM. When the amount of codebook is 8, and the testing speech is 8s, this method can improve the recognition rate 13% compared with VQ.

A Study for the Application of RASTA on Objective Communication Speech Quality Evaluation

WANG Wei,LIU Feng,WU Shuzhen

2003, 39(5):  697-702. 

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It is presented that the research result of using PASTA filter on objective communication speech quality evaluation. Perceptually Linear Prediction (PLP) and Mel Frequency Cepstral Coefficient (MFCC) methods with RASTA filter was used to compute the correlation between subjectiveand objective measure for the speech files which was transmitted in the shortwave and super shortwave channel. When RASTA filter is combined with PLP, the result is improved by 12%. When it is combined with MFCC, the result is improved by 4%. It proves that the RASTA filter which filters the lower frequency part of channel noise is useful in objective speech quality evaluation.

Image Pre-processing Based Rough Set and PCNN

GU Xiaodong,CHENG Chengqi,YU Daoheng

2003, 39(5):  703-708. 

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It is described that how to combine rough set with PCNN (Pulse Coupled Neural Network) to enhance the contrast of a noisy image to make the image clear so that the next image processing is easy. Meanwhile, the rough set and PCNN image enhancement algorithm is brought forward. The results of computer simulations show that noisy gray images can be enhanced efficiently by using this algorithm and image noise is reduced and image contrast is enhanced so that the image becomes clearer. In addition, the enhan cement effects of images based on this algorithm are better than those based on the other usual image enhancement algorithm.

Design of Analog Circuits in Σ-Δ Modulator

YANG Hong,SHENG Shimin

2003, 39(5):  709-715. 

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Based on the brief description of the principle of Σ-ΔADC and analyses of modulator's noise characteristics, the Top-down design method of modulators is introduced. Then, combining with practical requirement, this paper focuses on the discussion of designing the analog circuits in a Σ-Δ modulator. Some key of design, circuit details and simulation results are also presented.

Chancelloriids from Late Middle Cambrian of Huayuan, Hunan, South China

ZHU Caifa,DONG Xiping,CHEN Meng'e

2003, 39(5):  716-726. 

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The Chancelloriids were recovered from dark grey thin-bedded micrites and bioclastic micrites of the upper Middle Cambrian Huaqiao Formation at the Paibi section in Huayuan County, Hunan Province, China. About 40 samples with diverse sclerites have been identified, including Chancelloria altaica with 6-7+1 ray patterns, Archiasterlla sp. with 4+0 ray patterns and Allonnia sp. with 3+0 ray patterns as well as Chancelloria sp. with peculiar sclerite patterns. In addition to chancelloriids, these chancelloriid-bearing rocks, yield abundant and diverse trilobites, conodonts, hyolithids, hyolithellids, brachiopods, sponge spicules and ornamented tubular fossils. Compared with the materials reported from the Cambrian of Australia, Northwestern Canada, Western Argentina, West Africa and Iran etc., it is indicated that the Hunan assemblage is the latest records of Middle Cambrian chancelloriids in China and is one of a few higher horizons of occurrence of chancelloriids recovered in the world. Based on analysis of sclerite structure, preservation and the stratigraphic distributions of chancelloriids, the authors support the opinion that the chancelloriid may belong to a group of extinct metazoans which is closer to Porifera, in the systematic phylogenetic position. It probably represents a sessile animal which adapted to shallow sea environments.

Researching on the Characteristics of Microstructures of Carbonated Tree

FENG Youli,ZHENG Zhe,GUO Yanjun

2003, 39(5):  727-731. 

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The carbonated tree in volcanic breccia has been studied through high resolution transmission electronic microscopy (HRTEM), X-ray powder diffraction and laser Raman spectroscopy. The HRTEM imagine shows that it was the product of transition from micro-column to flexible crape graphite. The D-peak position is 1359.7～1369.2cm^-1. The O-peak position is 1601.5～1603.4cm^-1. Its second Raman spectroscopy reflect its crystallinity and the peak area ratio A_D/(A_D+A_O) reflects the crystal size (L_a). The estimated L_aof carbonated tree in volcanic tree is 7.6～11.8nm.

Wavelet Analysis of Turbulent Signal in the Lee of Windbreak

LIN Guanming,YE Wenhu

2003, 39(5):  732-735. 

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The turbulent flow near the windbreak is simulated in the boundary layer wind tunnel. Wavelet analysis is used to study the turbulent signal in the lee side of the windbreak. Compared with the flow without windbreak, the turbulent energy and the frequency of vortex are reduced dramatically. The evidence shows how the wind break prevents the dust emission.

Study on Faster Algorithm for Constructing Delaunay Triangulations DTM

HU Jinxing,PAN Mao,MA Zhaoting,WU Huanping

2003, 39(5):  736-741. 

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Based on the analysis of common Delaunay triangulations methods, especially the divide-and-conquer method, a faster algorithm for constructing Delaunay triangulations is presented. It divides the point set by self-adaptive grid, constructs and merges the sub-triangulations. The key problems of merging sub-triangulations, dealing with the terrain features and the flat triangles are described. The experiments show that the expected time of the algorithm is O(n).

Brain Imaging Studies of Semantic Representations in Bilinguals

ZHANG Huijuan,LI Lianjing,ZHOU Xiaolin

2003, 39(5):  742-748. 

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The authors review current brain imaging (fMRI and PET) studies of semantic representations in bilinguals and point out that the three issues have taken central ground in these studies: (1) whether semantic representations of different languages have identical neural mechanisms? (2) What effects do the proficiency in languages and the age of second language acquisition have on semantic representation in the brain? (3) Which brain areas are responsible for the switching and translation between languages? And whether these areas are devoted exclusively to language switching and/or translation?