Table of Content

20 January 2004, Volume 40 Issue 1

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Numerical Study of the Mesoscale Convective Systems in Landfall Typhoon Herb

LIU Wei,ZHANG Qinghong

2004, 40(1):  73-79. 

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The evolution and structure of two organized meso-α-scale convective systems developed sequentially on the landfall typhoon low during 3-5 August 1996 are simulated successfully using Penn State/NCAR mesoscale model version 5(MM5). The simulated cloud and precipitation are coincident with the satellite and conventional precipitation observations, respectively. Based on the model output, the detail structure and characteristic of MCS are studied, and the air trajectories around these MCSs are also calculated. Finally, a concept model of MCS in landfall typhoon was given out; In mature stage, the mesoscale Low-Level Jets (mLLJs) act as mesoscale disturbances that embedded in the synoptic-scale Low-Level Jets (LLJs) at the low-level. Strong convergence and upward motion occurred on the left-front of the mLLJ. Mesoscale Upper-Level Jets (mULJs) was found in the upper level outflow caused by upward motion. This mULJ can be verified from conventional upper-air soundings. Strong divergence happened in the right-rear of the mULJ in simulation.

Smooth Linearizability of Some Hyperbolic Vector Fields

REN Zhihua

2004, 40(1):  1-4. 

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It is studied that smooth linearizability and finitely smooth linearizability of some hyperbolic vector fields.

A New Multiple Control Variate Estimator for Asian Options

ZHAN Huirong,CHENG Qiansheng

2004, 40(1):  5-11. 

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Asian options are such popular exotic options that the valuation, especially the valuation of arithmetic Asian options which are traded in the OTC markets, is a problem of not only theoretical research but also practical applications. However, pricing Asian options is not an easy job, its difficulty lies in no closed-form representation for the probability distribution of the variable, a sum of correlated lognormal random variables, which determines the option payoff at expiration. Under the risk-neutral framework, the price of Asian options is just the risk neutral expectation of discounted payoff. Monte Carlo simulation with variance reduction techniques is a useful approach to estimate this expectation. A new multiple control variate estimator for Asian options is proposed, which is shown by numerical results to have significant improvement over others especially when t he time to maturity is long and the volatility is large.

Some New Properties of Dickson Polynomials

CAO Xiwang

2004, 40(1):  12-18. 

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Dickson polynomials are of special source of permutation polynomials over finite fields. It was found that Dickson polynomials have important applications in both pure and applied mathematics such as pseudoprimality testing and cryptology. Some new properties about Dickson polynomials are given in this note. It was shown that many properties of Dickson polynomials can be derived from our equations easily.

Stationarizing Two Classes of Nonstationary Processes by Wavelet

TANG Hongmin,XIE Zhongjie

2004, 40(1):  19-28. 

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The main purpose is to discuss the stationarity of two classes of nonstationary processes after wavelet transformations. Owing to the fact that the wavelet trans formation possesses localization and implicit difference property, the authors show that after wavelet transformation, the fractionally differenced process and the harmonizable periodically correlated process may be changed into stationary processes.

The Finite Checking Method of the Largest Stability Bound for a Class of Uncertain Interval Systems

LAN Yidong,WANG Long,ZHANG Lin

2004, 40(1):  29-36. 

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The largest stability bound for linear interval system, by guardian map approach, through finite checking can be obtained. The largest stability bound for multilinear interval system containing two interval coefficients, by guardian map approach and complete discrimination system for polynomials, through finite checking can also be obtained. Two examples illuminate the utility of our methods. For the multilinear system containing n(n>2) interval coefficients, it is also given that the method to compute its largest stability bound through finite checking.

The Transcendental Equation in the Refined Theory of Transversely Isotropic Elasticity Plate

ZHAO Baosheng,WANG Minzhong

2004, 40(1):  37-45. 

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Three basic equations on the refined theory of transversely isotropic plate are derived base on Elliott-Lodge solutions and Lure method. The transcendental state is analysed in detail.

An Improvement in the VLSI Implementation of Montgomery Algorithm

ZHANG Yihao,TIAN Ze,YU Dunshan,SHENG Shimin

2004, 40(1):  80-84. 

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Modular exponentiation of large operands is the kernel operation in many public-key cryptosystems, RSA algorithm for instance. Montgomery algorithm is often used as a solution. In the VLSI implementation of Montgomery algorithm, the speed is the top target. An improvement is proposed with little or even no increase in the hardware area but apparently saving much time.

An Objective Forecast Experiment in Precipitation at Stations

SHAO Mingxuan,WU Qingli,LIU Fenghui,WEI Jianming,DOU Yiwen,XU Fang

2004, 40(1):  46-55. 

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The forecast of precipitation at station is usually as the forecast of a discontinuous variable. In this paper, the forecast is transformed into a forecast of a continuous variable—possibility function of precipitation (PFP). PFP is determined by observations. And a new method, dynamic combination equation of nonlinear multi-factors (DCENMF), has been developed to forecast precipitation at station by forecasting PFP. Based on this approach, experimental objective forecasts of precipitation at stations were made in Beijing district from July to December 1998. Precipitation forecasts for 15 stations are assessed by the critical success index (CSI). The mean CSI is 0.40 for the night, and 0.33 for the next day.

Study on the Vertical Structure of Precipitable Cloud in HUAIHE River Basin Area with Spaceborne Radar and Radiometer

LIU Wenming,JIN Xin,ZHU Yuanjing

2004, 40(1):  56-65. 

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Using data gathered by Tropical Rainfall Measuring Mission (TRMM) Satellite in 2000 during the period of Huaihe River Basin Energy and Water Cycle Experiment (HUBEX), a new precipitable cloud model is established. To validate this model, a vector radiative transfer model is used to simulate the upwelling microwave radiation sensed by TRMM Microwave Imager (TMI). The contribution of each component in this cloud model to the total upwelling brightness temperature is discussed. It is concluded that the new precipitable cloud model is reliable and can fit the requirement for further study in relative areas; also it is pointed out that the influence of icy hydrometeors to the upwelling radiation is severe and needs further study.

Meso-α-Scale Convective Systems over Yellow Sea Region during Summers of 1993～1996

ZHENG Yongguang,ZHU Peijun,CHEN Min,BAI Jie,WANG Likun,LI Yaping,WEI Xue,TAO Zuyu

2004, 40(1):  66-72. 

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Based on the GMS satellite IR images during the summers of 1993～1996，the meso-α-scale convective systems (M_αCS) were investigated over the Yellow Sea region. The results revealed that the Yellow Sea region is a favorable zone for M_αCS in eastern Asia and there exist active-M_αCS period and null-M_αCS period during summer in the region. The majority of M_αCSs originated from the mainland of China, while the minority from the ocean and few from the Korea Peninsula. More than half of M_αCSs dissipated over the Pacific Ocean, and there was few M_αCS influencing on the Korea Peninsula.

A New Automatic Seal Image Retrieval Method Based on Curves Matching

SONG Yong,LIU Hong

2004, 40(1):  85-90. 

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Chinese characters have many smooth vertical and horizontal strokes. According to that, two kinds of retrieval features in Chinese characters images are proposed and named as outer edge contour feature and orientation projection density feature. Further, by formularizing the two features with functional curves, matching of Chinese characters is transformed into matching of functional curves. Experiments show that these two kinds of features are stable and the curves matching based seal image retrieval method is effective.

An Algorithm for Estimating Carrier Frequency Offset in ST-OFDM System

ZOU Li,ZHAO Yuping,WANG Bing,LIANG Qinglin

2004, 40(1):  91-98. 

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According to the feature of ST-OFDM system, we proposed an efficient CFO estimation algorithm, which focus on the IFO estimation algorithm. Compared to the conventional algorithm, this novel algorithm can solve the problem that the wide acquisition range/low probability of failure conflicts with low complexity. The simulation results indicate under multi-path channel for low SNR, the new algorithm has lower probability of failure than the conventional algorithm by adopting proper training symbols. When the probability of failure is needed to be lower and the acquisition range is needed to be wider, the gain of proposed algorithm will be larger.

The Preliminary Probe of 4-Peg Hanoi Tower

YANG Kai,XU Chuan

2004, 40(1):  99-106. 

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In 1941,J.S.Frame gave out an algorithm in American Mathematical Monthly to solve the problem of 4-peg Hanoi Tower, but he did not provide the proof for the final formulae. According to that algorithm, this article puts forward a formula to calculate the number of movements necessary for the 4-peg Hanoi Tower problem, and proves it using mathematical induction.

Some Key Techniques Research in Environmental Mapping Using High Spatial Resolution Remote Sensed Data

GUO Shide,LIN Xudong,MA Ting

2004, 40(1):  116-120. 

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Recently, the environmental mapping is an important application of high spatial resolution remote sensing images. However, with the improvement of spatial resolution, the size and land cover details of imagery significantly increase. Those bring on some hurdles to image processing. In this paper, some key processing techniques are discussed including the choice of spatial and pixel resolution, color match and recovering. Actual works proves that these methods are very useful for environmental mapping based on high spatial resolution remote sensed images.

Anti-Poverty and Environment Sustainability in West China:
A Study for the Hemoluo District

GUO Huaicheng,ZHANG Zhenxing,CHEN Bing,ZOU Rui,ZHANG Ning

2004, 40(1):  144-153. 

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The poverty issue and environment issue are very pressing in west China and these two issues are interlaced each other. The poverty is arose by environment issue mainly. The essential approach of anti-poverty is to break the vicious circle between the poverty and environment and harmonize these two issues. So the study of anti-poverty and environment sustainability is very important. In this study, the Hemoluo District of Xinjiang, which is key poverty counties listed in the National Ant-poverty Plan, is taken as a case to study the relations between anti-poverty and environment sustainability. Since the Inexact Multi-Objective Planning (IMOP) model can harmonize several objectives, optimize dynamic system and reflect the uncertainty, it is applied to deal with the environmental economic system planning. During the model building, solving and interpreting, interactive adjustment and scenario analysis are applied. Thus through system analysis and IMOP model, the antipoverty and environment sustainability are studied qualitatively and quantitatively.

The Challenges of Neutron Star Studies

XUE Yongquan,QIAO Guojun,XU Renxin,WANG Hongguang

2004, 40(1):  161-175. 

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Pulsars (PSRs) were identified as neutron stars (NSs) soon after their discoveries, the study of which increases significantly our knowledge of nature. The Nobel prizes of physics had awarded pulsar researchers two times for discovering the first radio pulsar and checking the general theory of relativity with strong gravity, respectively. Recently some new breeds in "neutron star" family have been disc overed: the so-called Soft Gamma-ray Repeaters (SGRs), Anomalous X-ray Pulsars (AXPs), Compact Central Objects (CCOs) in supernova remnants (SNRs) and Dim Thermal Neutron Stars (DTNs). These are challenges for theorists: are some or all of the so-called “neutron stars” actually "strange stars (SSs)" in nature? are there any so-colled "magnetars" (a kind of neutron stars with super-strong magnetic field)? The observed properties of the "neutron stars", the theoretical efforts in understanding their nature, and the debates between different models (especially on SGRs/AXPs) are presented.

Study of the Anti-Chemical Terrorism on Numerical Simulation

HUANG Shunxiang,HU Fei,LI Xin,CHEN Haiping,QIAN Yixin

2004, 40(1):  121-128. 

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Aiming at terrorists attack chemical plants or chemical establishments, the model, based on the 3-D atmospheric diffusion on complex terrain, is completed. The model can be used to simulate the wind fields, concentration fields, dose fields, and make certain the danger areas and make the harm evaluation. The model can provide necessary scientific data for working-out counterplan, emergence response and emergence rescue. The model can be applied to the analogous chemical affairs in character for emergence response and emergence rescue as well as to the risk evaluation in disposed ACW (Abandoned Chemical Weapons) in performing CWC (Chemical Weapons Convention).

Engineering Geological Characteristics and Evaluation of Different Sedimentary Facies of the Recently Deposited Soil in Beijing Area

LI Shude,YUAN Renmao,LU Honghua,SUN Hongwei

2004, 40(1):  139-143. 

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Taking the sediment of Yongding River as an example, the authors discussed the changes of relationship between sedimentary facies and engineering geological features of recently deposited soil vertically and horizontally. It showed that the qualities of recently deposited soil is getting worse as the sediment transforming from riverbed facies to flooded facies vertically, and as for an identical sedimentary facies, the qualities of physical properties seemed to be worse from the upper reaches to the lower reaches of the Yongding River.

Research on Landscape Ecology and Sustainable Land Use

PENG Jian,WANG Yanglin,LIU Song,WU Jiansheng,LI Weifeng

2004, 40(1):  154-160. 

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Sustainable land use is always the research topic of land science and related disciplines. In this paper, we make research on sustainable land use under the guide of newly landscape ecology. It is a beneficial attempt to extend the research scope on sustainable land use. Based on the analysis of the relations hip between land, landscape and landscape ecology, we make a new annotation of the connotation of sustainable land use according to such landscape ecology theories as structure and function, ecological holism and spatial heterogeneity, hierarchy and scale, and landscape change and stability.

Research on Landscape Ecology and Sustainable Land Use

PENG Jian,WANG Yanglin,LIU Song,WU Jiansheng,LI Weifeng

2004, 40(1):  154-160. 

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Sustainable land use is always the research topic of land science and related disciplines. In this paper, we make research on sustainable land use under the guide of newly landscape ecology. It is a beneficial attempt to extend the research scope on sustainable land use. Based on the analysis of the relations hip between land, landscape and landscape ecology, we make a new annotation of the connotation of sustainable land use according to such landscape ecology theories as structure and function, ecological holism and spatial heterogeneity, hierarchy and scale, and landscape change and stability.