Journal of University of Chinese Academy of Sciences

Numerical simulation research on tsunami hazards

zhang chao-fan, shi yao-lin

2008, 25 (3): 289-296. DOI: 10.7523/j.issn.2095-6134.2008.3.001

Numerical tsunami simulation has significant meaning in helping us understanding its physical characteristics and making prediction and mitigation decisions. More and more researchers are using this tool. This paper reviewed the general method in current numerical tsunami simulation, including the description of its physics, splitting of the physical processes, governing equations for different processes, common numerical tsunami simulation method, the key points and hard points. Then we reviewed some important numerical tsunami simulation models which has great influence among the international tsunami research community, and discussed their implementation and characteristics respectively.

Generalized confidence regions in mixed models

Mu Wei-yan, Xiong Shi-feng

2008, 25 (3): 297-304. DOI: 10.7523/j.issn.2095-6134.2008.3.002

Abstract ( 1385 ) PDF (KB) ( 0 )

This paper discusses inferences for the fixed effects of balanced mixed effects models under both homoscedasticity and heteroscedasticity.By the generalized approach to make statistical inference, we derive the generalized confidence regions and the generalized p-values concerning the fixed effects. Simulation studies show that the performances of the confidence regions are satisfactory.

Global stability of a mathematical model of plankton

Li lin, Yan yan

2008, 25 (3): 305-312. DOI: 10.7523/j.issn.2095-6134.2008.3.003

Abstract ( 1223 ) PDF (KB) ( 0 )

The differential delay model, which is introduced to simulate zooplankton-nutrient interaction, of the form is studied, where is the concentration of nutrient, is a measure of zooplankton population at time t and parameter are positive constants. If , and hold, then the positive steady state of this system is globally attractive. Some sufficient conditions on local stability of the steady state of the model are given.

(Editors: Formulas in the abstract can't be displayed normally. See the pdf file)

Ruin probabilities of a risk model with time-correlated claims

Xie jie-hua, Zou wei

2008, 25 (3): 313-319. DOI: 10.7523/j.issn.2095-6134.2008.3.004

Abstract ( 1277 ) PDF (KB) ( 0 )

Ruin Probabilities of a risk model with time-correlated claims are studied in this paper. It is assumed that every main claim may produce a by-claim and the occurrence of the by-claim may be delayed. By means of the Laplace tansform, the ruin probabilities of the risk model are obtained. The differential equations of the ruin probabilities are obtained and the explicit expressions of the ruin probabilities are given when the claim sizes are exponentially distributed.

Consensus of a class of multi-agent systems with active leader and time delay

Wang jin-huan, Hu jiang-ping, Hong yi-guang, Cheng dai-zhan

2008, 25 (3): 320-328. DOI: 10.7523/j.issn.2095-6134.2008.3.005

Abstract ( 1059 ) PDF (KB) ( 0 )

This paper considers the consensus problem of multi-agent systems with an active leader and time-varying delay. In our problem, the velocity of the leader can not be measured precisely. To track such a leader, a decentralized state-estimation rule is constructed for each agent, which is used to design local controllers. Due to the interconnection delays, both neighbor-based control rules and stat-estimation rules involve time-varying delays. Moreover, with the directed (fixed or variable) interconnection topologies described by digraphs, the leader-following errors are estimated. Particularly, it is proved that each agent can track the leader if th input of the active leader is precisely known.

Research of tunneling magnetoresistance effect in ferromagnet-nonmagnetic impurity-ferromagnet system

Luo yong-feng, Ding kai-he

2008, 25 (3): 329-333. DOI: 10.7523/j.issn.2095-6134.2008.3.006

Abstract ( 1045 ) PDF (KB) ( 0 )

Based on wave-matching method, we investigate the tunneling magnetoresistance effect in ferromagnet-nonmagnetic impurity- ferromagnet system. The results show that existence of the molecular fields in two ferromagnets leads to the form of quasi-bound states under certain conditions. When the incident energy of electrons matches approximately the energy level of the quasi-bound states, the resonant tunneling occurs, which exhibit a peak in conductance. Nonmagnetic impurity and the effective masses of electrons in two ferromagnetic electrodes have remarkable effects on the behaviors of the conductance, including the amplitudes and the positions of the resonance peaks in conductance.

Studies on applications of well-defined functional polypropylene copolymers

Zhang Liao-Yun, Hu You-liang

2008, 25 (3): 334-339. DOI: 10.7523/j.issn.2095-6134.2008.3.007

Abstract ( 1119 ) PDF (KB) ( 0 )

Differential scanning calorimeter and scanning electron microscopy were used to study effect of well-defined functional i-PP-b-PMMA block copolymer in PP/PMMA blends and that of i-PP-b-PS block copolymer in PP/PS blends. The experimental results showed these functional polypropylene copolymers maintained characteristics of high melting point owned by starting isotactic polypropylene polymers, and were clearly proven to be effective compatibilizer in PP/PMMA blends and PP/PS blends. In addition, i-PP-b-PMMA and i-PP-b-PS could increase bending strength and bending modulus of corresponding blending systems.

Modeling nonlinear internal wave generation and propagation over continental shelf

Li Qun, Xu Zhao-ting, Chen Xu

2008, 25 (3): 340-345. DOI: 10.7523/j.issn.2095-6134.2008.3.008

Abstract ( 1270 ) PDF (KB) ( 0 )

Intense internal waves are common phenomena on mid-latitude continental shelves when the water column is stratified. In this paper, a nonlinear nonhydrostatic two layer model is used to examine the details of the generation and evolution of these waves. This model indicates that the internal waves are generated by the interaction of the barotropic tide with the shelf break topography. The onshore flow of the tides causes an upward displacement of isopycnals. This disturbance splits into a pair of counter propagating waves. The subsequent offshore flow causes a downward displacement which acts in conjunction with advection to steepen the back face of the onshore propagating wave. Thus an internal onshore propagating shock is developed, which eventually disintegrates into a packet of solitary internal waves (SIW) through a process of nonlinear self-interaction. Meanwhile, the model results are compared with available experiment data.

Sensitivity study of photochemical reflectance index to leaf biochemical components

Wu Zhao-Yang, Niu Zheng

2008, 25 (3): 346-354. DOI: 10.7523/j.issn.2095-6134.2008.3.009

Abstract ( 1240 ) PDF (KB) ( 0 )

The photochemical reflectance index (PRI) which is defined as a normalized difference index relating two narrow reflectance wavebands at 531 nm and 570 nm provides a reliable method to estimate light use efficiency (LUE) at the leaf, canopy and sight scales. Therefore, PRI opens a new era for estimating Net primary productivity（NPP）in a relatively high precision. However, a number of disturbances which change with scales will influence the relationship between PRI and LUE. Therefore, it is of great necessity and urgency to explore the influences of different disturbances at different scales on the relationship between PRI and LUE. In this analysis, sensitivity study was carried out at leaf and canopy scale based on PROSPECT and SAIL model respectively. The results proved that leaf PRI was sensitive to leaf biochemical components as leaf mesophyll structure parameter and chlorophyll a+b content while insensitive to dry matter content and equivalent water thickness. At canopy scale, canopy PRI was much influenced by leaf area index, leaf angle distribution, sun zenith angle and view zenith angle. Canopy PRI was depended on the intrinsic characteristic of canopy rather than the soil type of background.

Model reduction of cell signalling transduction networks via hybrid inference method

Jia Jian-Fang Liu Tai-Yuan Yue Hong Wang Hong

2008, 25 (3): 355-366. DOI: 10.7523/j.issn.2095-6134.2008.3.010

Abstract ( 1510 ) PDF (KB) ( 0 )

The mathematical model of cell signal transduction networks is highly nonlinear and complex, which involves a large number of variables and kinetics parameters. How to effectively develop the reduced-order model is a major problem for analyzing complex systems. In this work, a model reduction strategy via hybrid inference method is proposed for complex signal transducion networks. This approach synthesizes metabolic control analysis, sensitivity analysis, principal component analysis, and flux analysis to reduce the dimensions of the model and to decrease the number of the biological reactions. Using NF-κB signaling pathway as an example, the detailed model consists of 24 ordinary differential equations and 64 parameters. According to the model reduction strategy, the reduced-order model is composed of 17 ordinary differential equations, one algebraic equation, and 52 parameters. The simulation results demonstrate that the reduced-order model quantitatively predicts the dynamic characteristics of the system output, which are much the same as that of the detailed model. Therefore, the model reduction strategy provides guidance for the analysis and design of complex cell networks. It is more effective and more straightforward to estimate the unknown parameters by means of the reduced-order model.

Performance Analysis of a node self-locating scheme in DTN routing algorithms

Wang xing-fu, Wei ping-qing, Miao fu-you, Xiong yan

2008, 25 (3): 367-371. DOI: 10.7523/j.issn.2095-6134.2008.3.011

Abstract ( 1046 ) PDF (0KB) ( 0 )

Probabilistic route algorithm of DTN（Delay Tolerant Network） in “MobySpace” needs to locate the node in advance. But it is hard to know in advance how a node moves. A scheme of self-location, in which all coordinates of a node are adjusted gradually by a adjusting parameter while the node is moving, is proposed in this paper. Finally all coordinates will fluctuate in a usable range. The simulation shows that the scheme is able to find a proper value of adjusting parameter to make the routing algorithm in DTN stable and transplantable.

3D Muscle-Controlled Tongue and Mouth Model

Chen Zhi-xiang, Cheng Yi-min, Zeng Dan, Ge Shi-ming

2008, 25 (3): 372-378. DOI: 10.7523/j.issn.2095-6134.2008.3.012

Abstract ( 1370 ) PDF (0KB) ( 0 )

A 3D Muscle control tongue and mouth(3D-MCTM) model is presented in this paper. Based on anatomy and tongue’s moving characteristic，the model consists of two parts-- the inner model and the outer model. Outer mouth is controlled by nine pieces of muscle which respectively belong to three different kinds, while the tongue is controlled by six pieces of new muscle. The modeling and animation is convenient. The experiments on PC show that the tongue model is realistic, and can simulate mouth movement vividly.

A Cost-Computing Based Task Scheduling in Grid Market

Liu Xiao-qian, Yang Shou-bao, Guo Lei-tao, Shen Kai

2008, 25 (3): 379-385. DOI: 10.7523/j.issn.2095-6134.2008.3.013

Abstract ( 1129 ) PDF (KB) ( 0 )

In Grid environment, with a view to allocate and manage Grid resources, on-line schedulers aim at meeting all kinds of uses’ resources requests, rather than paying enough attention to resources providers. In order to increase resources providers’ profit and encourage sites to provide service actively, a cost-computing based task scheduling scheme is proposed, which calculates sunk cost and opportunity cost, based on relative information provided by users, to decide whether to accept the task, such that both resource providers and customers will achieve their economic goals, therefore, to promote the development of whole market more stably. Experiment shows that the scheduler reduces the cost of resources providers，increases their profit, and effectively encourages sites to offer more resources.

An Information Hiding Method in Speech Using MFCC

Tang Bu-tian , Guo Li , Liu Zhen-hua

2008, 25 (3): 386-394. DOI: 10.7523/j.issn.2095-6134.2008.3.014

Abstract ( 1345 ) PDF (KB) ( 0 )

Information hiding has been a research problem since 1990’s. Random silent gap of speech signal makes less hiding space for speech than space for other audio signals such as music although information hiding in speech has very good prospective in Internet or any other wire/wireless channel. This paper provides an information hiding method in MFCC for speech signal. Because short time energy of speech is more invariable and can ensure the synchrony of frame in hiding and extracting, it makes extracting algorithm restore the secret from hided speech signal correctly. This method can be used in application of Internet or LAN channel with high speed transmission.

A Multi-Recipient Signcryption Scheme of Strong Security

ZHU Zhen-chao，ZHANG Yu-qing ，WANG Feng-jiao

2008, 25 (3): 395-402. DOI: 10.7523/j.issn.2095-6134.2008.3.015

Abstract ( 1424 ) PDF (KB) ( 0 )

This paper defines a strong security model for multi-recipient signcryption scheme in the random oracle model, which is semantically secure against adaptive chosen-ciphertext insider attack, existentially forgeable chosen-message attack and anonymous chosen-ciphertext insider attack. By analyzing, we point out that Li-Hu-Liu Multi-Recipient Signcryption Scheme is insecure against the adaptive and anonymous chosen-ciphertext insider attacks. Later, we present an improved scheme, which is proven to be secure in our newly defined strong security model.

Prediction method of the ionospheric F2 layer critical frequency based on neural networks

Jin Hui-bin, Zhang Can, Qin Lei

2008, 25 (3): 403-407. DOI: 10.7523/j.issn.2095-6134.2008.3.016

Abstract ( 1374 ) PDF (0KB) ( 0 )

During ionospheric storm periods, the existing prediction methods for the critical frequency of ionospheric F2 layer (foF2) can not satisfy the requirements of the practical applications. In this paper, a new prediction method for the foF2 based on neural networks is proposed. This method is driven by the previous time series of the ap index and the monthly mean of the solar spot number, while the output is the estimations of the foF2 in the next 24 hours. The simulation results indicate that the new method outperforms the existing prediction methods (such as STORM model, or neural network method proposed by Cander).

Design of an X Band Broadband Low Noise Amplifier

XIE Tao, ZHOU Yi-guo, GUO Jun-dong

2008, 25 (3): 408-412. DOI: 10.7523/j.issn.2095-6134.2008.3.017

Abstract ( 1966 ) PDF (KB) ( 0 )

An X band broadband low noise amplifier (LNA) is presented. This amplifier, using NEC’s HJFET NE3210S01, had a microstrip stub matching structure and a two-stage topology. ADS was used as a tool to design, optimize and simulate. The designed amplifier exhibited broadband operation from 10GHz-13GHz with noise figure less than 2dB, Gain 21.5dB±1dB and SWR less than 1.8.

Effect of Galactomannan Oligosaccharides on Intestinal Microglora and Bacterial Community in Weaning Pigs

HOU Zhen-Ping, ZHANG Ping, ZHANG Jun, LI Tie-Jun, HUANG Rui-Lin, YIN Yu-Long, CHEN Li-Xiang, GAO Bi

2008, 25 (3): 413-418. DOI: 10.7523/j.issn.2095-6134.2008.3.018

Abstract ( 1139 ) PDF (0KB) ( 0 )

Effect of galactomannan oligosaccharides (GMOS) on intestinal microglora and bacterial community in newly-weaning pigs by denaturing gradient gel electrophoresis (DGGE) analysis of 16S ribosomal RNA. Lincomycin and GMOS included in the diet appeared to have changed PCR-DGGE profiles of cecal microbiota compared to the control diet. The DNA bands of colonic microbiota were more than that of ileal microbiota, and the DNA bands of day 14 were more than that of day 0 post-weaning in ileal, but the bands of day 14 were as much as that of day 0. There were some same bands among different lanes, it meant that Lactobacillus salivarius, Ruminococcus forques and E.coli 0517:H7 existed in every treatment in ileal but Staphylococcus aureus, Lactobacillus salivarius, Ruminococcus forques, Bacillus subtilis and Clostridium perfringens in colon and the different bands showed that each had different microbiota. Similarities between DGGE profiles most were 20%~50%, except that of control and 0.2%GMOS in ileal were 80%. It meant that each treatment had its own microbiota profiles.

Minireview: Molecular Level Devices Based on Electroactive Tetrathiafulvalene and Photochromic Spiropyran

Guo Xue-feng, Zhang De-qingZhu, Dao-ben

2008, 25 (3): 419-432. DOI: 10.7523/j.issn.2095-6134.2008.3.019

Abstract ( 1353 ) PDF (0KB) ( 0 )

This minireview details the design, development, and demonstration of chemical strategies that are used to create molecular level devices and implement digital processing and communication. The design principle here is to integrate two informationally rich but relatively simple nanobuilding blocks with their complements through photoinduced electron transfer, redox processes, conformational changes, photoinduced energy and proton transfer, and supramolecular events into functional molecular devices. Depending on the abundant electrochemical properties of TTF, lots of D-A-D supramolecules and [2]rotaxanes with the different linkages were synthesized for studying photoinduced transient electron transfer and nanorecording abilities. Also detailed below are the methods to take advantage of the distinct abilities of electron, energy, and proton transfer of photochromic spiropyran to design supramolecular ensembles and control their absorption, fluorescence, and conductive properties by light and chemical reagents. Based on the spectral and electrochemical behaviors of these ensembles, a whole bunch of novel molecular switches, logic gates, and molecular circuits were constructed. At last, we present an interesting insight into designing a new type of luminescent spiropyan molecules with stable merocyanine open form in solution as well as in the solid state.

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