Showing papers by "Xidian University published in 2002"
TL;DR: Preliminary experiments prove the state transition sequences can express the different mode between normal action and intrusion behaviour in a more stable and simple manner.
Abstract: An anomaly intrusion detection method based on HMM is presented. The system call trace of a UNIX privileged process is passed to a HMM to obtain state transition sequences. Preliminary experiments prove the state transition sequences can express the different mode between normal action and intrusion behaviour in a more stable and simple manner.
172 citations
TL;DR: In this paper, the principle of the decomposition method is described and its advantages as well as drawbacks are discussed, and an aftertreatment technique (AT) is proposed, which yields the analytic approximate solution with fast convergence rate and high accuracy through the application of Pade approximation to the series solution derived from ADM.
Abstract: Adomian's decomposition method (ADM) is a nonnumerical method which can be adapted for solving nonlinear ordinary differential equations. In this paper, the principle of the decomposition method is described, and its advantages as well as drawbacks are discussed. Then an aftertreatment technique (AT) is proposed, which yields the analytic approximate solution with fast convergence rate and high accuracy through the application of Pade approximation to the series solution derived from ADM. Some concrete examples are also studied to show with numerical results how the AT works efficiently.
121 citations
03 Sep 2002
TL;DR: The simulation experiment for the traffic flow of one practice crossing proves the validity and efficiency and high application value in traffic flow prediction.
Abstract: For intelligent transportation systems, a new traffic flow time series prognostication is proposed in this paper. Compared with classical methods, support vector machine has a good generalize ability for limited training samples, which has a characteristic of rapid convergence and avoiding the local minimum. At the end of this paper, the simulation experiment for the traffic flow of one practice crossing proves the validity and efficiency and high application value in traffic flow prediction.
97 citations
TL;DR: Simulation results for both artificial and real data show that the generalization performance of the method is a good approximation of SVMs and the computation complex is largely reduced by the method.
95 citations
04 Nov 2002
TL;DR: It is proved that the antibody clone algorithm is convergent, which is shown to be an evolutionary strategy capable of solving complex machine learning tasks, like multi-modal optimization.
Abstract: Based on clonal selection theory, the main mechanisms of a clone in the immune system, which are explored in the field of artificial intelligence, are analyzed. An artificial immune system algorithm, antibody clone algorithm, is put forward. Compared with an improved gene algorithm, the new algorithm is shown to be an evolutionary strategy capable of solving complex machine learning tasks, like multi-modal optimization. Using Markov chain theories, it is proved that the antibody clone algorithm is convergent.
88 citations
TL;DR: It is shown that the steady-state excess output energy of the Kalman filtering algorithm is identically zero for a stationary environment.
Abstract: Although several Kalman filtering algorithms have been presented for adaptive multiuser detection, none is "blind" due to requiring training data sequences and/or more knowledge than the spreading waveform and delay of the desired user. This paper proposes a novel blind adaptive multiuser detector based on Kalman filtering and compares it with previously published LMS and RLS algorithms for blind adaptive multiuser detection. It is shown that the steady-state excess output energy of the Kalman filtering algorithm is identically zero for a stationary environment. Simulation results show the effectiveness of the new Kalman filtering algorithm.
83 citations
TL;DR: The lower and upper solutions method and the fixed-point theorem on cone are used to establish several existence results of a third-order two-point boundary value problem.
74 citations
TL;DR: In this article, a preprocessing scheme is presented to obtain stable range profiles for automatic target recognition (ATR) based on high-resolution range profiles, which can be divided into many range resolution cells, each of which still contains the echoes of many scatterers.
Abstract: Wideband radar can obtain much target information due to its high-range resolution. Because its size is smaller than the resolution of conventional radar, for an airplane, it can be regarded as a point. However, for wideband radar with a bandwidth of several hundred megahertz, the range resolution is less than a meter, and airplane echoes of one impulse form a high-resolution range profile (HRRP), which includes the shape information of a target that can be used for automatic target recognition (ATR). A range profile can be divided into many range resolution cells, each of which still contains the echoes of many scatterers. The complex amplitude of one range cell echo can be regarded as the sum of these echoes. A small aspect of change will lead to a big change of the complex amplitude, since, although the variation of the range of each scatterer to radar is very small, it is still large enough compared to the small wavelength and may cause a big phase change. Hence, the range profiles are very sensitive to the aspect angle, which makes the ATR based on HRRPs a well-known challenging problem. The properties of range profiles are investigated and a preprocessing scheme is presented to obtain stable range profiles for ATR.
73 citations
TL;DR: The TD-SCDMA standard makes use of TDD synchronous CDMA technology and offers several operational advantages and can be very attractive to service providers in regions where worldwide popular GSM system is in operation.
Abstract: China, as the largest developing country in the world, has been emerging as a nation with the fastest penetration rate growth in mobile communications, exceeding the United States to become the largest single mobile cellular market in terms of subscriber population. The recent successful admission to the World Trade Organization (WTO) has given China new momentum for further development of its mobile communications infrastructure and fueled international competition as well in the mobile communication market of the country. Since the opening up of its economy, China has spent billions of dollars to purchase equipment from foreign telecommunication manufacturers, which has created a heavy burden to modernize its legacy industrial sectors. This is the situation China is eager to change. The TD-SCDMA standard was proposed by the CWTS of China to ITU in 1998 as an effort to bring China on a par with other developed countries in mobile communications system development and also to make the country less dependent on foreign vendors. The proposal was approved by ITU as one of the candidate standards for 3G mobile communications in May 2000 and accepted by 3GPP in March 2001. The TD-SCDMA standard makes use of TDD synchronous CDMA technology and offers several operational advantages. For instance, it allows the existing GSM core networks to be upgraded to the TD-SCDMA platform along a relatively easy path. Therefore, it can be very attractive to service providers in regions where worldwide popular GSM system is in operation. The TD-SCDMA standard has received the full blessing of the Chinese government and will surely play a critical role in mobile communications development in China as well as in the world; its impact should never be underestimated. In this survey article the historical background as well as the technical content of the TD-SCDMA standard will be addressed.
70 citations
28 May 2002
TL;DR: A new approach for recovering 3D geometry from an uncalibrated image sequence of a single axis (turntable) motion based on fitting a conic locus to corresponding image points over multiple views is described.
Abstract: In this paper, we describe a new approach for recovering 3D geometry from an uncalibrated image sequence of a single axis (turntable) motion. Unlike previous methods, the computation of multiple views encoded by the fundamental matrix or trifocal tensor is not required. Instead, the new approach is based on fitting a conic locus to corresponding image points over multiple views. It is then shown that the geometry of single axis motion can be recovered given at least two such conics. In the case of two conics the reconstruction may have a two fold ambiguity, but this ambiguity is removed if three conics are used.The approach enables the geometry of the single axis motion (the 3D rotation axis and Euclidean geometry in planes perpendicular to this axis) to be estimated using the minimal number of parameters. It is demonstrated that a Maximum Likelihood Estimation results in measurements that are as good as or superior to those obtained by previous methods, and with a far simpler algorithm. Examples are given on various real sequences, which show the accuracy and robustness of the new algorithm.
57 citations
TL;DR: A new and efficient dense matching algorithm is presented based on region growth, which can be applied to a wide range of image pairs including those with large disparity or without rectification, and the results demonstrate its accuracy and efficiency.
TL;DR: In this paper, an adaptive controller based on Lyapunov stability theory is proposed to make the states of two identical Rossler and Chen systems globally asymptotically synchronized in the presence of system's unknown constant parameters.
TL;DR: Simulations show that the new natural-gradient-based RLS algorithm with prewhitening for blind source separation has faster convergence than the existing least-mean-square algorithms and RLS algorithms for BSS.
Abstract: By using the natural gradient on the Stiefel manifold to minimize a nonlinear principle component analysis criterion, this letter proposes a new adaptive recursive-least-squares (RLS) algorithm with prewhitening for blind source separation (BSS), which makes full use of the orthogonality constraint of the separating matrix. Simulations show that the new natural-gradient-based RLS algorithm has faster convergence than the existing least-mean-square algorithms and RLS algorithm for BSS.
TL;DR: The modified Max-RWA problem is formulated as a integer linear programming (ILP) problem, and then solved using a genetic algorithm, thus reducing the complexity of the genetic algorithm.
Abstract: In this letter, the routing and wavelength assignment problem in all optical networks is considered. We improve the Max-RWA model presented by R. M. Krishnaswamy and K. N. Sivarajan (see ibid., vol.5, p.435-7, Oct. 2001) by introducing limited-range wavelength conversions. Considering transmission performance, we propose a new optimization objective, which is to establish the maximum number of connections with the least number of wavelength converters. The modified Max-RWA problem is formulated as a integer linear programming (ILP) problem, and then solved using a genetic algorithm. The extended layered-graph approach is used to assign routes and wavelengths when necessary, thus reducing the complexity of the genetic algorithm. Numerical results obtained for NSFNET are presented.
TL;DR: In this paper, the authors describe the scattering of light by one spheroid, which is of practical interest for various applications in particle sizing techniques, and examine the validity of the Mobius formula.
Journal Article•
TL;DR: Experimental results have proved that the method of embedding the watermark in digital images based on the discrete wavelet transform is robust enough to some image degradation process such as cropping, JPEG compression and sharpening etc.
Abstract: As a new technique applying to protecting the copyright of digital productions, the digital watermark technique has drawn extensive attention A method of embedding the watermark in digital images based on the discrete wavelet transform is proposed The watermark used here is not the conventional patterns such as a pseudo-random sequence or a bit stream but a text watermark The information which the text watermark contains is abundant and intuitionistic, also the watermark is robust To ensure the security of the watermark and make the watermark be hard to be extracted, the watermark is scrambled with Arnold scrambling transformation before embedded into the original image According to the different characteristics of the high and the low frequency components of the wavelet coefficients of the original image, more watermark information is embedded in the high frequency components while less information in the low ones That is to say, by using the hierarchical structure of the wavelet, the watermark is repeatedly embedded in various places Moreover, experimental results have proved that the method is robust enough to some image degradation process such as cropping, JPEG compression and sharpening etc So it is effective
TL;DR: It is proved strictly an important theoretical result that, for an arbitrary initial point, the trajectory of the proposed network does converge to the set of its equilibrium points, regardless of whether a convex nonlinear programming problem has unique or infinitely many optimal solutions.
Abstract: A neural network for solving convex nonlinear programming problems is proposed in this paper. The distinguishing features of the proposed network are that the primal and dual problems can be solved simultaneously, all necessary and sufficient optimality conditions are incorporated, and no penalty parameter is involved. Based on Lyapunov, LaSalle and set stability theories, we prove strictly an important theoretical result that, for an arbitrary initial point, the trajectory of the proposed network does converge to the set of its equilibrium points, regardless of whether a convex nonlinear programming problem has unique or infinitely many optimal solutions. Numerical simulation results also show that the proposed network is feasible and efficient. In addition, a general method for transforming nonlinear programming problems into unconstrained problems is also proposed.
TL;DR: In this article, the influence of geometrical structure parameters on the hot-carrier effect immunity in deep-sub-micron grooved gate PMOSFET's is studied.
Abstract: Based on the hydrodynamics energy transport model, the influence of geometrical structure parameters on the hot-carrier-effect immunity in deep-sub-micron grooved gate PMOSFET's is studied. The study results are explained based on the device's interior physical mechanism. The structure parameters investigated include the effective channel length, the concave corner and the negative junction depth induced by changing the source/drain junction depth or groove depth. The research results indicate that the hot-carrier effect is depressed deeply for grooved gate PMOSFET's even in deep and super-deep-sub-micron regions, and with the increase of the concave corner and the negative junction depth, the hot-carrier-effect immunity becomes better. Those are mainly because that the structure parameters influence the distribution of the electric field in the devices, which influence the “corner effect” and the transportation of the carriers.
TL;DR: A weighted information criterion (WINC) for searching the optimal solution of a linear neural network, and analytically shows that the optimum weights globally asymptotically converge to the principal eigenvectors of a stationary vector stochastic process.
Abstract: Principal component analysis (PCA) is an essential technique in data compression and feature extraction, and there has been much interest in developing fast PICA algorithms. On the basis of the concepts of both weighted subspace and information maximization, this paper proposes a weighted information criterion (WINC) for searching the optimal solution of a linear neural network. We analytically show that the optimum weights globally asymptotically converge to the principal eigenvectors of a stationary vector stochastic process. We establish a dependent relation of choosing the weighting matrix on statistics of the input process through the analysis of stability of the equilibrium of the proposed criterion. Therefore, we are able to reveal the constraint on the choice of a weighting matrix. We develop two adaptive algorithms based on the WINC for extracting in parallel multiple principal components. Both algorithms are able to provide adaptive step size, which leads to a significant improvement in the learning performance. Furthermore, the recursive least squares (RLS) version of WINC algorithms has a low computational complexity O(Np), where N is the input vector dimension, and p is the number of desired principal components. In fact, the WINC algorithm corresponds to a three-layer linear neural network model capable of performing, in parallel, the extraction of multiple principal components. The WINC algorithm also generalizes some well-known PCA/PSA algorithms just by adjusting the corresponding parameters. Since the weighting matrix does not require an accurate value, it facilitates the system design of the WINC algorithm for practical applications. The accuracy and speed advantages of the WINC algorithm are verified through simulations.
TL;DR: In this paper, the authors developed a nonlinear calibration method to deal with the overflow of the solar radio broadband dynamic spectrometer, and introduced channel-modification method to handle the images.
Abstract: The processes of the sudden energy release and energy transfer, and particle accelerations are the most challenge fundamental problems in solar physics as well as in astrophysics. Nowadays, there has been no direct measurement of the plasma parameters and magnetic fields at the coronal energy release site. Under the certain hypothesis of radiation mechanism and transmission process, radio measurement is almost the only method to diagnose coronal magnetic field. The broadband dynamic solar radio spectrometer that has been finished recently in China has higher time and frequency resolutions. Thus it plays an important role during the research of the 23rd solar cycle in China. Sometimes when there were very large bursts, the spectrometer will be overflowed. It needs to take some special process to discriminate the instrument and interference effects from solar burst signals. According to the characteristic of the solar radio broadband dynamic spectrometer, we developed a nonlinear calibration method to deal with the overflow of instrument, and introduced channel-modification method to deal with images. Finally the interference is eliminated with the help of the wavelet method. Here we take the analysis of the well-known solar-terrestrial event on July 14th, 2000 as the example. It shows the feasibility and validity of the method mentioned above. These methods can also be applied to other issues.
TL;DR: The logarithm bispectrum feature of a target and that of its high resolution range profile is established and the criterion for target recognition is induced, and its scheme and pseudocode for implementation are given.
TL;DR: A modified IEEE 802.11 PCF protocol, M-PCF is presented, which can supply different service policy to different services with different requirements on QoS.
Abstract: A modified IEEE 802.11 PCF protocol, M-PCF is presented, which can supply different service policy to different services with different requirements on QoS. Analysis and simulation show that the M-PCF protocol can improve real-time quality and network throughput by modifying the polling scheme of PCF.
TL;DR: In this paper, the authors compared the cable and cabin structure with the Stewart platform and showed that the feed cabin can be viewed as a moving platform and the six cables as six legs.
07 Nov 2002
TL;DR: An auto-disturbance rejection controller (ADRC) is designed to achieve high precision motion control for an AC servo system and has the characteristics of high precision and high robustness to the variation of load and parameters.
Abstract: An auto-disturbance rejection controller (ADRC) is designed to achieve high precision motion control for an AC servo system. The simulation and experimental results show that the designed AC servo system has the characteristics of high precision and high robustness to the variation of load and parameters, and easy implementation in engineering.
TL;DR: This technique solves the problem of the Doppler mismatch of binary phase-coded waveforms at the expense of about 3 dB loss in signal-to-noise ratio (SNR) and may be used in tracking applications, such as accurately and rapidly measuring and tracking targets of unknown speeds.
Abstract: Codes used in phase-coded pulse compression waveforms suffer from Doppler mismatch. Based on an analysis of the effects of Doppler mismatch on binary phase-coded waveforms, a class of codes is proposed (hereafter referred to as the component codes), its derivation and processing is described, and the performance results are analyzed. This technique solves the problem of the Doppler mismatch of binary phase-coded waveforms at the expense of about 3 dB loss in signal-to-noise ratio (SNR). This technique may be used in tracking applications, such as accurately and rapidly measuring and tracking targets of unknown speeds. Simulation results demonstrate the validity of this technique.
TL;DR: Based on the reciprocity theorem, the light scattering from a spherical particle above a slightly dielectric rough surface was studied in this paper, where the theoretical formulation that accounts for the near-field interaction between a spherical particles and a rough surface is given, the analytical solution of the scattering cross section for the composite model is presented, and the backscattering cross sections are calculated and discussed in detail.
Abstract: Based on the reciprocity theorem, the light scattering from a spherical particle above a slightly dielectric rough surface is studied. The theoretical formulation that accounts for the near-field interaction between a spherical particle and a rough surface is given, the analytical solution of the scattering cross section for the composite model is presented, and the backscattering cross sections are calculated and discussed in detail. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 142–146, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10259
26 Aug 2002
TL;DR: A new method is proposed which can appropriately tune multiple parameters in the kernel functions of an SVM and can improve the algorithm performance and make it approach to the real problem, but also can avoid those methods available which are too complex.
Abstract: In recent years, research into SVMs has focused on two main areas. One is to improve the precision of the SVM algorithm, and another is to improve its speed. We propose a new method which can appropriately tune multiple parameters in the kernel functions of an SVM. It not only can improve the algorithm performance and make it approach to the real problem, but also can avoid those methods available which are too complex; the kernel must be differential and the result may be not optimal.
TL;DR: A synchronizer is derived, which can make the states of the driven system globally track theStates of the drive system asymptotically and is simply constructed by an analytic formula, without knowledge in advance of the unknown bounds of the uncertain parameters.
Abstract: We propose a novel adaptive synchronization method for a class of nonlinear chaotic systems with uncertain parameters. Using the chaos control method, we derive a synchronizer, which can make the states of the driven system globally track the states of the drive system asymptotically. The advantage of our method is that our problem setting is more general than those that already exist and the synchronizer is simply constructed by an analytic formula, without knowledge in advance of the unknown bounds of the uncertain parameters. A computer simulation example is given to validate the proposed approach.
TL;DR: In this article, the absorption and scattering of a Gaussian beam and a plane wave by an oblate particle with different size parameters were studied. And the scattered intensities distribution for the oblate particles with different sizes parameters were computed in the Gaussian beams and the plane wave.
Abstract: In this paper, we have studied the absorption and scattering of a Gaussian beam and a plane wave by an oblate particle. The scattered intensities distribution for an oblate particle with different size parameters are computed in the Gaussian beam and plane wave.
26 Aug 2002
TL;DR: A new fragile watermarking technique is proposed for image authentication, where a logo is embedded as the watermark for integrity authentication and tamper detection.
Abstract: A new fragile watermarking technique is proposed for image authentication. A logo is embedded as the watermark for integrity authentication and tamper detection. Different from most existing schemes, to resolve the existing security problem, an image feature is selected and hashed to generate the chaotic key, which adds uncertainty to the bits of each watermark. Theoretical analysis and experimental results demonstrate its effectiveness in resisting existing attacks and its good localization property.