Journal of University of Chinese Academy of Sciences

MINRES and finite element method for singularly perturbed reaction diffusion
equations

YIN Jun-Wei, CHEN Yu-Fu

2008, 25 (6): 721-725. DOI: 10.7523/j.issn.2095-6134.2008.6.001

In this paper, we discuss the numerical solutions of singularly perturbed reaction diffusion equation , where both and are positive
constants. Based on the finite element method, we use the MINRES algorithm to
obtain numerical solutions of the equation. Our new approach corrects the spurious
oscillations in the presence of boundary layers of the original solutions.

Optimal portfolio selection based on maximizing risk-adjusted return on capital

Wu Dao-Yu, Yin Hong-Xia

2008, 25 (6): 726-731. DOI: 10.7523/j.issn.2095-6134.2008.6.002

Abstract ( 1136 ) PDF (KB) ( 1 )

In this paper, we consider an optimal portfolio selection method based on maximizing risk-adjusted return on capital(RAROC) of the portfolio. The fractional structure of the objective function maximizing RAROC makes it difficult to be solved. We noticed that in real financial practice, the expected return function and risk function of the portfolio are often homogeneous with the amount of investment. Under some conditions we proved that the problem can be solved by minimizing its denominator in certain constraints. When random return follows normal distribution, it maximizes RAROC problem associated with risk measure, such as Value at Risk(VaR) or Conditional Value at Risk(CVaR), can be reformulated as a problem that minimizes a square root function with linear constraints. The latter problem can be solved by using excising second order cone optimization software.

Determination of dissociation heat of hydrate by mixing calorimetry

Dong Fu-Hai, Fan Shuan-Shi, Liang De-Qing

2008, 25 (6): 732-737. DOI: 10.7523/j.issn.2095-6134.2008.6.003

Abstract ( 1180 ) PDF (KB) ( 3 )

A method based on the mixing calorimetry for determination of hydrate dissociation heat was introduced. Under the condition of atmospheric pressure, the dissociation heat of tetrahydrofuran (THF) hydrate, which was about (275.62  2.64) kJ/kg at 4.4 C of phase-transition temperature, was determined by this method. Similarly, the dissociation heat of CH3CFCl2¬ (HCFC-141b) hydrate was about (348.48  3.08) kJ/kg at the phase-transition temperature of 8.4 C. By comparison with those previous results, the maximum relative error is 2% and 6.6%, respectively. To obtain the optimal results of dissociation heat, the mass ratio between hot water and THF hydrate or HCFC-141b hydrate has been optimized as well.

Simulation of water environmental carrying capacity in Liaohe watershed

ZHAO Wei, LIU Jing-Shuang, KONG Fan-E

2008, 25 (6): 738-747. DOI: 10.7523/j.issn.2095-6134.2008.6.004

Abstract ( 1640 ) PDF (KB) ( 0 )

Water environmental carrying capacity (WECC) complex system is characterized by high-step, multi-variables, multi-loops and nonlinear feedback structure. Based on this, the simulation model of WECC in liaohe watershed is built using system dynamics, in order to explore the dynamic variation of WECC in Liaohe watershed of Liaoning Province and its driving factors. The validity test of the model showed that the simulation model constructed could be used to simulate the dynamic variation of WECC and analyze the effect of development policy. From 1996 to 2005, WECC of the region fluctuated significantly, and water environment overloaded with the trend of Deterioration. Water environment is the dependent factor of WECC, but effect of water environmental management on WECC increased gradually. Four schemes of WECC adjustment were designed, and the simulation model constructed was applied to simulate the dynamic variation of WECC in order to select the optimal scheme.

Evolution of urban spatial structure in the arid area of Northwest China: a case study on the city of Bayanhaote

XIE Tian-Cheng , XIE Zheng-Guan

2008, 25 (6): 748-755. DOI: 10.7523/j.issn.2095-6134.2008.6.005

Abstract ( 1438 ) PDF (KB) ( 0 )

As urbanization developing rapidly, more and more attentions have been paid to the evolution of urban spatial structure by researchers from western countries and China. Taking the Bayanhaote City in Northwest China as an example, this paper analyzes the characteristics of urban expansion and mechanism of evolution from the viewpoint of urban scale, urban shape and urban structure. As a city in the arid area of Northwest China, Bayanhaote has its own features of the process of urban expansion and the mechanism of evolution. The built-up city of Bayanhaote had grown just in the old district slowly before 1980s; since the “New District” was set up, the city has entered in a fast developing stage. The “New District” extends with high-speed while the old district developing slowly. By and large, the Bayanhaote’s spatial structure evolution is due to the law of “first developing in two flanks of main roads, then inside the construction lots”. The development of urban spatial structure is caused by the comprehensive effects of many factors. The drives of economy, government and society are always mingled in the expansion of urban space and the change of structure. In different stages, the factors that influence the evolution of urban spatial structure are different. Economic development may be the basic factor of the evolution of urban spatial structure, whereas administrative force has also played an important role in it. For Ba-yanhaote, government’s modulation and control could even be the most important factor, while the influence of transportation has not yet become obvious up to now.

Study on the thermal environment effect of land use type and pattern changes：Harbin city

ZHANG Xin-Le, ZHANG Shu-Wen, LI Ying, XIE Yun-Feng, YUE Shu-Ping, ZHANG Yu-Bo

2008, 25 (6): 756-763. DOI: 10.7523/j.issn.2095-6134.2008.6.006

Abstract ( 1434 ) PDF (KB) ( 0 )

Normalizing land surface temperature to eliminate its uncomparableness due to the images acquired in different times, calculating the proportion of land use types in 2km×2km case as a token of the land use pattern, and take Harbin city as an example to study the spatial pattern and the rule of spatial-temporal changes of urban heat field distribution, and uncover the effects of land use types spatial pattern on the urban thermal environment. The results show that: Heat-island effect existed remarkably in the built up area of Harbin , and was swelled; the collectivity land surface temperature of Harbin city ascended. The mean values’ discrepancy of each land use type’s land surface temperature decreased; the function of build up area to heat-island effect boosted up; water’ s function of reducing heat-island effect weakened; spatial discrepancy of thermal environment became unconspicuous.

Evolution study on the ecological carrying capacity of West Jilin province based on the principal component analysis and entropy weight method

WANG Ming-Quan, WANG Jin-Da, LIU Jing-Shuang

2008, 25 (6): 764-770. DOI: 10.7523/j.issn.2095-6134.2008.6.007

Abstract ( 1624 ) PDF (KB) ( 0 )

West Jilin province is a typical area of the frangible agro-pastoral ecotone in northern China, where the sustainable development was heavily restricted by both the natural and socio-economic factors. Principal Component Analysis (PCA) and Entropy methods were used to evaluate the evolution of the ecological carrying capacity (ECC) of West Jilin province from 1995-2004. Through PCA, 3 principal components were obtained from all the indicators to represent 3 main factors of ECC: C₁Development level of ecosystem, C₂ Economic efficiency and C₃ Water resource abundant. Entropy method was utilized to calculate the weight of each component and corresponding indicators and then got the comprehensive index ECC. The results indicated that: ECC of West Jilin province has been increasing with obvious fluctuation in the past 10 years, and the economic efficiency rise contributed most to the ECC increase while the water resource was the main driving force of ECC fluctuation. As a consequence, the ECC increase led more resource requirement and sever ecosystem degradation of West Jilin province, thus the resource-environment developed slowly from 1995-2004. The resource-environment, especially the water resource, will lead great restriction to the ECC in future if no effective countermeasures to improve it.

Privacy-preserving statistical quantitative rules mining

Jing Wei-Wei , Huang Liu-Sheng, Yao Yi-Fei, Xu Wei-Jiang

2008, 25 (6): 771-780. DOI: 10.7523/j.issn.2095-6134.2008.6.008

Abstract ( 1297 ) PDF (KB) ( 2 )

Statistical Quantitative (SQ) rule plays an important and useful role in data mining. Centralized algorithms have been presented for SQ rules mining. However, the algorithms cannot be easily applied to mining SQ rules on distributed data, where privacy of parties becomes great concerns. This paper considers the problem of mining SQ rules without revealing the private information of parties who compute jointly and share distributed data. The issue is an area of Privacy-Preserving Data Mining (PPDM) research. Based on several basic tools for PPDM, including secure sum, secure mean and secure frequent itemsets, this paper presents two algorithms to accomplish privacy-preserving SQ rules mining over horizontally partitioned data. One is to securely compute confidence intervals for testing the significance of rules; the other is to securely discover SQ rules. Besides, the analysis of the correctness, the security and the complexity of our algorithms are provided.

A study on MSAR space-time two-dimensional clutter simulation

Huang Yao ，Lei Hong，Xia Yuli

2008, 25 (6): 781-786. DOI: 10.7523/j.issn.2095-6134.2008.6.009

Abstract ( 2122 ) PDF (KB) ( 0 )

Space-time adaptive processing (STAP) is an effective method to suppress ground clutter and extract moving targets in the Multi-Channel SAR (MSAR) system. The space-time two-dimensional filter weight is decided by the evaluation of the clutter covariance matrix. From the MSAR echoes model, a method of raw-data simulation in the frequency domain by two-dimensional FFT is proposed and the evaluating of MSAR clutter space-time covariance matrix is made. The simulation result shows that the data produced by this method retain the reality of MSAR space-time clutter characteristic with lower computational complexity.

The acquirement of the echoes of the side-lobe transmitting wave of GPR

Hu Hai-Tao, Fang Guang-You

2008, 25 (6): 787-791. DOI: 10.7523/j.issn.2095-6134.2008.6.010

Abstract ( 1058 ) PDF (KB) ( 0 )

The obvious echoes of the side-lobe transmitting waves are caused by the transmitting antenna working on the condition of a stimulation pulse with abnormal pulse width. The studies of the properties of the echoes are significant in theory and applications on the GPR. Based on the ratio of the electric field intensity from the echoes of the side transmitting waves to the total receiving electric field intensities, a method of the echoes of the side-lobe transmitting waves is presented. The results obtained from an application with this method are compared with the trial data. The comparisons show that the agreement between the echoes acquired using this method and the trial data is good. The rationality of the method is approved.

A model of efficient intrusion recovery solution based on log-structured file system

WEN Xiao-Yang , JING Ji-Wu, LIU Peng

2008, 25 (6): 792-801. DOI: 10.7523/j.issn.2095-6134.2008.6.011

Abstract ( 1103 ) PDF (KB) ( 4 )

Data content stored in computer systems are more crucial than ever before. Compromised computer systems always suffer from data contaminations in both system and user files, therefore intrusion recovery methods are indispensable today. Existing intrusion recovery methods have shortcomings in certain aspects because, in our observation, the file systems on which these methods work are not inherently apt to realize recovery. In contrast, Log-Structured File System (LFS) is ideal to perform various intrusion recovery algorithms. We explain our claims theoretically, propose data recovery algorithm, validate it in SimuLFS, the LFS simulator we built, and test it in real LFS environment in FreeBSD. Experiment results indicate that even very simple recovery algorithm can achieve fast file recovery from almost any state of the disk, with little throughput degradation, guarantee accuracy, require no extra storage requirements and minimal changes to any original LFS code.

A study of power allocation strategy for amplitude-limited MIMO system

Peng Jing-bo，Wei Guo

2008, 25 (6): 802-809. DOI: 10.7523/j.issn.2095-6134.2008.6.012

Abstract ( 1193 ) PDF (KB) ( 0 )

Power allocation strategy for amplitude-limited MIMO system is studied and a new power allocation method is proposed. In this new method, nonlinear distortion caused by amplitude limiting is taken into account to improve the transmission quality. Simulation results also show that when the amplitude of transmit signal is large, the performance of traditional water-filling method will degrade obviously while the new method could provide better performance.

An efficient realization of MDCT/IMDCT based on N/8-point FFT kernel

Li Lin, Guo Li, Bai Xue-fei, Huang Hao

2008, 25 (6): 810-815. DOI: 10.7523/j.issn.2095-6134.2008.6.013

Abstract ( 1809 ) PDF (KB) ( 0 )

MDCT/IMDCT performs the conversion between the time-domain signal and the frequency representation in the high quality audio codec system, which is based on the concept of time-domain aliasing cancellation. Using the N/8-point FFT kernel, a new MDCT/IMDCT general structure is presented in this paper. The computation rate and the data throughput per transformation of the system are twice as much as the latest algorithm, utilizing both the paralleling procedure and the butterfly unit. In addition, the analyzed results of FPGA implementation on Altera Stratix Device show the proposed structure provides a superior performance in terms of computation speed and data throughput.

A robust PCR-based multi-object tracking algorithm

WU Bo, WANG Hong-Qi

2008, 25 (6): 816-823. DOI: 10.7523/j.issn.2095-6134.2008.6.014

Abstract ( 1260 ) PDF (KB) ( 0 )

Multi-object tracking is one of the key technologies in video surveillance. In this paper, a new PCR-based multi-object tracking algorithm is proposed and principal colors are used to characterize the appearance of each object. Combined with the kalman filter prediction a PCR-based mean shift procedure is applied to estimate the current location of each object. Then an association matrix between the estimate locations and foreground blobs is built to distinguish many different situations that possibly occur in complex real world applications. Lastly the state of object including location, size and color model is updated according to different situations. Experimental results on many image sequences have shown that the proposed algorithm can efficiently deal with complex occlusions. The performance of this new tracking algorithm is robust.

Implementation of a web mathematical equation editor providing the mathematical semantics

Dong Guo-Ming, Zhang Jun-Yu

2008, 25 (6): 824-829. DOI: 10.7523/j.issn.2095-6134.2008.6.015

Abstract ( 1366 ) PDF (KB) ( 0 )

There are two ways to present mathematical expressions on web pages now, i.e. as an image or installing plug-ins on web browser. To make up the shortage of both methods, a web mathematical equation editor named E-Math is presented. E-Math is based on Content MathML and implemented in JavaScript and XSLT, and therefore supports further numerical and symbolic computation online. Furthermore, the source code of E-Math is openly available. This paper provides E-Math’s framework and a technical solution.

A compact planar ultra-broadband sum-and-difference network

Chai Wen-Wen, Zhang Xiao-Juan

2008, 25 (6): 830-834. DOI: 10.7523/j.issn.2095-6134.2008.6.016

Abstract ( 1493 ) PDF (KB) ( 0 )

In this paper, a novel power divider is proposed. Based on this power divider, a planar ultra-broadband microstrip sum-and-difference network is designed. This network employs the novel power divider and anti-phase balun as a building block. An equivalent 180^o coupler is achieved by back-connecting the power divider and balun together. Four such couplers are connected to form the ultra-broadband sum-and-difference network. The features of this network are verified to be excellent, resulting in the advantages of being compact, easy manufacturing and low cost.

A traffic model for space communication video algorithm

Li Zhe, Zhang Can, Yan Feng-Gang

2008, 25 (6): 835-842. DOI: 10.7523/j.issn.2095-6134.2008.6.017

Abstract ( 1218 ) PDF (KB) ( 0 )

In this paper，we propose a traffic model for space communication video algorithm. The model makes good use of decorrelation performance of Hadamard transform and the characteristic of GOP structure of 3D (3 Dimension) wavelet video algorithm. We demonstrated the validity of our model by statistical measurements and Bit Loss Rate performance evaluation. The model is proved to be simple and efficient. It is suitable for the research of space network communication systems as the video source model.

The mechanical model of computer animation based on numerical manifold method

LIU Ting-Ting, WANG Ying

2008, 25 (6): 843-848. DOI: 10.7523/j.issn.2095-6134.2008.6.018

Abstract ( 1042 ) PDF (KB) ( 0 )

Physics-based animation has always been an issue of computer graphics. A new numerical computing method named Numerical Manifold Method is firstly introduced into the area of computer animation. A general mechanical model is developed by making use of the advantage of numerical manifold method. It is simulated that an elastic object is being unfolded, a ball collapses into a square consisting of several little elastic blocks, and an elastic ball is pulled through rigid running gears. Simulation results show that the mechanical model has the potential advantage on multi-deformable objects simulation and the creation and spread of the joints.

Geometric theory of elasticity on biomembranes

Tu Zhan-Chun, Ou-Yang Zhong-Can

2008, 25 (6): 849-854. DOI: 10.7523/j.issn.2095-6134.2008.6.019

Abstract ( 1231 ) PDF (KB) ( 0 )

This paper is focused on discussing the elasticity of biomembranes by using modern differential geometry. The shape equation and boundary conditions of open lipid bilayers are derived. A cell membrane is simplified as a composite shell of lipid bilayer and membrane skeleton. The membrane skeleton is shown to enhance highly the mechanical stability of cell membranes.

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