ISSN 
2007 Vol. 36, No. 2
2007, 36(2): 161-163,216.
Abstract:
To reduce the protection-switching cost and failure recovery time, the fiber-level P-Cycles is presented to realize network protection. The issue about the joint optimization design of the working path routes with fiber-level P-Cycle placement is further studied; and an improved ILP formulation is developed. To reduce the complexity of joint optimization problem, the simple process of pre-selecting candidate P-Cycles by the efficiency and length metric and candidate working path routes by the hop metric is used. By simulation analysis, the fiber-level P-Cycles scheme efficiently decreases the switching cost compared with the wavelength-level P-Cycles.
To reduce the protection-switching cost and failure recovery time, the fiber-level P-Cycles is presented to realize network protection. The issue about the joint optimization design of the working path routes with fiber-level P-Cycle placement is further studied; and an improved ILP formulation is developed. To reduce the complexity of joint optimization problem, the simple process of pre-selecting candidate P-Cycles by the efficiency and length metric and candidate working path routes by the hop metric is used. By simulation analysis, the fiber-level P-Cycles scheme efficiently decreases the switching cost compared with the wavelength-level P-Cycles.
2007, 36(2): 164-166,175.
Abstract:
This paper discusses issues of feeder link handover and user link handover in Low Earth Orbit (LEO) satellite mobile communication systems without Inter-Satellite Links (ISL). Two feeder link handover schemes are presented. These two schemes are simulated based on two user link handover principles and non-uniform distributed national traffic model of china. Simulation results show that the longest visible duration scheme can greatly reduce the handover frequency of gateway and improve system performance. Consequently this scheme has better value in practice.
This paper discusses issues of feeder link handover and user link handover in Low Earth Orbit (LEO) satellite mobile communication systems without Inter-Satellite Links (ISL). Two feeder link handover schemes are presented. These two schemes are simulated based on two user link handover principles and non-uniform distributed national traffic model of china. Simulation results show that the longest visible duration scheme can greatly reduce the handover frequency of gateway and improve system performance. Consequently this scheme has better value in practice.
2007, 36(2): 167-169,185.
Abstract:
The current analysis focuses on the performance of BPSK modulation on 2-dimensional spread spectrum system with single-tone jamming. The Bit Error Ratio (BER) of the system is analyzed with the method of pilot symbol assisted modulation. Also the simulation result of the BER is provided and shows that the simulation and the analytical result are almost the same. The result derives the effect of the jamming on the system.
The current analysis focuses on the performance of BPSK modulation on 2-dimensional spread spectrum system with single-tone jamming. The Bit Error Ratio (BER) of the system is analyzed with the method of pilot symbol assisted modulation. Also the simulation result of the BER is provided and shows that the simulation and the analytical result are almost the same. The result derives the effect of the jamming on the system.
2007, 36(2): 170-172,192.
Abstract:
Closed-form solutions for the correlated Rayleigh fading channel capacity under L-branch Maximum Ratio Combining (MRC) diversity reception are obtained in this paper. The performance of constant-power adaptive M-ary Quadrature Amplitude Modulation (MQAM) schemes over correlated Rayleigh channels under MRC diversity reception is investigated. Closed-form expressions for spectral efficiency of adaptive MQAM assuming perfect channel estimation and negligible time delay are derived. Numerical results that illustrate the effect of correlation and antenna configurations on the correlated Rayleigh fading capacity and spectral efficiency of adaptive MQAM are also presented.
Closed-form solutions for the correlated Rayleigh fading channel capacity under L-branch Maximum Ratio Combining (MRC) diversity reception are obtained in this paper. The performance of constant-power adaptive M-ary Quadrature Amplitude Modulation (MQAM) schemes over correlated Rayleigh channels under MRC diversity reception is investigated. Closed-form expressions for spectral efficiency of adaptive MQAM assuming perfect channel estimation and negligible time delay are derived. Numerical results that illustrate the effect of correlation and antenna configurations on the correlated Rayleigh fading capacity and spectral efficiency of adaptive MQAM are also presented.
2007, 36(2): 173-175.
Abstract:
Slot allocation is an important issue for Time Division Multiple Access (TDMA) wireless multihop networks. A novel transmission scheduling algorithm, referred as Collision Avoidance-Proper Robust Schedule (CA-PRS) algorithm is presented. The distinguished difference from the traditional Proper Robust Schedule (PRS) is that CA-PRS algorithm can adjust the slot assignments in response to topology changes, to avoid transmission contention. The proposed algorithm has some properties, such as low protocol overhead, easy to implement, and without the requirement of the nodal degree. Simulation results reveal that CA-PRS algorithm has the advantage over simple-PRS and therefore has much higher utilization of wireless resources.
Slot allocation is an important issue for Time Division Multiple Access (TDMA) wireless multihop networks. A novel transmission scheduling algorithm, referred as Collision Avoidance-Proper Robust Schedule (CA-PRS) algorithm is presented. The distinguished difference from the traditional Proper Robust Schedule (PRS) is that CA-PRS algorithm can adjust the slot assignments in response to topology changes, to avoid transmission contention. The proposed algorithm has some properties, such as low protocol overhead, easy to implement, and without the requirement of the nodal degree. Simulation results reveal that CA-PRS algorithm has the advantage over simple-PRS and therefore has much higher utilization of wireless resources.
2007, 36(2): 176-178,206.
Abstract:
This paper introduces the space-time coding and the space-frequency coding technologies of a Multi-Input and Multi-Output(MIMO) system. We combine the Orthogonal Frequency divided Multiplex (OFDM) with MIMO system and research on several MIMO-OFDM systems, for example, Space-Time Block Coding (STBC) OFDM system, Space-Frequency Block Coding(SFBC) OFDM system, and Vertical Bell Laboratories Layered Space Time (VBLAST)-OFDM system. Analysis and simulation of these MIMO-OFDM systems' performance are examined. The results show that the data rate of the VBLAST-OFDM system is the highest, which is at least the twice as high as that of the STBC-OFDM or SFBC-OFDM system. However Bit Error Rate(BER) performance of the VBLAST-OFDM system is worse than that of the others. When BER is equal to 0.001, the required signal-noise ratio for VBLAST-OFDM system is 9.3dB more than that for the STBC or SFBC and OFDM system. On the other hand, the complexity of the VBLAST-OFDM system is higher than that of the STBC or SFBC and OFDM systems.
This paper introduces the space-time coding and the space-frequency coding technologies of a Multi-Input and Multi-Output(MIMO) system. We combine the Orthogonal Frequency divided Multiplex (OFDM) with MIMO system and research on several MIMO-OFDM systems, for example, Space-Time Block Coding (STBC) OFDM system, Space-Frequency Block Coding(SFBC) OFDM system, and Vertical Bell Laboratories Layered Space Time (VBLAST)-OFDM system. Analysis and simulation of these MIMO-OFDM systems' performance are examined. The results show that the data rate of the VBLAST-OFDM system is the highest, which is at least the twice as high as that of the STBC-OFDM or SFBC-OFDM system. However Bit Error Rate(BER) performance of the VBLAST-OFDM system is worse than that of the others. When BER is equal to 0.001, the required signal-noise ratio for VBLAST-OFDM system is 9.3dB more than that for the STBC or SFBC and OFDM system. On the other hand, the complexity of the VBLAST-OFDM system is higher than that of the STBC or SFBC and OFDM systems.
2007, 36(2): 179-181,202.
Abstract:
The Multi-Input and Multi-Output (MIMO) block flat-fading channel is estimated and optimized with colored noise. The lower bounds of mutual information and system capactiy are analyzed based on the optimization result of estimated channel. The approach to improve the lower bound of system capacity by the optimized power allocation of transmit antennas array through waterpouring algorithm is presented. The simulation result shows that some capacity gain is obtained by transmitter power allocation according to the optimal result of estimated channel.
The Multi-Input and Multi-Output (MIMO) block flat-fading channel is estimated and optimized with colored noise. The lower bounds of mutual information and system capactiy are analyzed based on the optimization result of estimated channel. The approach to improve the lower bound of system capacity by the optimized power allocation of transmit antennas array through waterpouring algorithm is presented. The simulation result shows that some capacity gain is obtained by transmitter power allocation according to the optimal result of estimated channel.
2007, 36(2): 182-185.
Abstract:
Robustness of Constrained Cyclic Adaptive Beam-Forming (CCCAB) included in Cyclic Adaptive Beam-Forming (CAB) algorithms will become lower under bad signals environments because its correlation matrix is not very suitable for cyclostationary signals. An improved algorithm for CCAB is presented as a solution to the problem in this paper. The theoretic formula of the correlation matrix for cyclostationary signals is induced firstly, after the inexactness of the old correlation matrix and the positive effect of forgetting factor are analyzed, the recursive formula of the new correlation matrix is concluded. The comparsion of computer simulations shows that the improved algorithm can receive weak signals, depress interferences and decreace the sensitivity to cyclic frequency error more effectively.
Robustness of Constrained Cyclic Adaptive Beam-Forming (CCCAB) included in Cyclic Adaptive Beam-Forming (CAB) algorithms will become lower under bad signals environments because its correlation matrix is not very suitable for cyclostationary signals. An improved algorithm for CCAB is presented as a solution to the problem in this paper. The theoretic formula of the correlation matrix for cyclostationary signals is induced firstly, after the inexactness of the old correlation matrix and the positive effect of forgetting factor are analyzed, the recursive formula of the new correlation matrix is concluded. The comparsion of computer simulations shows that the improved algorithm can receive weak signals, depress interferences and decreace the sensitivity to cyclic frequency error more effectively.
2007, 36(2): 186-189.
Abstract:
A new blind deconvolution algorithm for Weiner model is proposed, based on kurtosis criterion and decision directed. Through analyzing when maximum kurtosis is used to resolve nonlinear blind deconvolution problem, it is found there exist some disadvantages, such as too many local optimum values and large residual error. So the decision directed least mean error is introduced in the cost function, and the number of local optimum values can be reduced and residual error is decreased. To overcome the drawback of traditional gradient search approaches, likely falling into local minimum, the real coded genetic algorithm is adopted to search the optimum solution. Simulation results demonstrate this algorithm not only has fast convergence rate and high accuracy, but also can greatly improve the output signal noise ratio.
A new blind deconvolution algorithm for Weiner model is proposed, based on kurtosis criterion and decision directed. Through analyzing when maximum kurtosis is used to resolve nonlinear blind deconvolution problem, it is found there exist some disadvantages, such as too many local optimum values and large residual error. So the decision directed least mean error is introduced in the cost function, and the number of local optimum values can be reduced and residual error is decreased. To overcome the drawback of traditional gradient search approaches, likely falling into local minimum, the real coded genetic algorithm is adopted to search the optimum solution. Simulation results demonstrate this algorithm not only has fast convergence rate and high accuracy, but also can greatly improve the output signal noise ratio.
2007, 36(2): 190-192.
Abstract:
Direction of Arrival (DOA) estimation is one of the key technologies of Direct Sequence Ultra Wide Bandwidth (DS-UWB) system. The traditional DOA estimation methods which are based on narrow-band signals are not suited for such system. So a fourth-order cumulant-based estimation method of DOA is proposed. This method is founded on the frequency domain model of DS-UWB array signals. The spatial spectral function is then derived for analysis. The performance of the estimation algorithm is evaluated by computer simulation and the results show that the algorithm is effective and can guarantee adequate estimation accuracy.
Direction of Arrival (DOA) estimation is one of the key technologies of Direct Sequence Ultra Wide Bandwidth (DS-UWB) system. The traditional DOA estimation methods which are based on narrow-band signals are not suited for such system. So a fourth-order cumulant-based estimation method of DOA is proposed. This method is founded on the frequency domain model of DS-UWB array signals. The spatial spectral function is then derived for analysis. The performance of the estimation algorithm is evaluated by computer simulation and the results show that the algorithm is effective and can guarantee adequate estimation accuracy.
2007, 36(2): 193-195.
Abstract:
A chaotic synchronized secure communication method based on time-varying parameters is presented. The method improves communication secure performance greatly and can defeat all known attacking methods at the present time. The parameter sensitivity of chaotic synchronization systems makes chaotic synchronization robust, but eavesdroppers can follow this way to attack and defeat communication systems. The time-varying parameters method can solve this problem. Based on Chua circuit, the simulations show that this method have defeated the attacks of all known breaking methods at present, such as generalized synchronization, adaptive parameter estimation, and so on.
A chaotic synchronized secure communication method based on time-varying parameters is presented. The method improves communication secure performance greatly and can defeat all known attacking methods at the present time. The parameter sensitivity of chaotic synchronization systems makes chaotic synchronization robust, but eavesdroppers can follow this way to attack and defeat communication systems. The time-varying parameters method can solve this problem. Based on Chua circuit, the simulations show that this method have defeated the attacks of all known breaking methods at present, such as generalized synchronization, adaptive parameter estimation, and so on.
2007, 36(2): 196-198,209.
Abstract:
The Finite-State-Machine (FSM) evolution using Genetic Algorithm (GA) is a typical theme in Evolvable Hardware (EHW) research. In this paper, an improved GA is described for FSM evolution. According to the characteristic that output is relevant to state transition in FSM, this algorithm divides the chromosome representing FSM into state transition gene and output gene for stage-by-stage evolution. Experimental results indicate that this improved GA greatly decreases the complexity of FSM evolution and gets better performance.
The Finite-State-Machine (FSM) evolution using Genetic Algorithm (GA) is a typical theme in Evolvable Hardware (EHW) research. In this paper, an improved GA is described for FSM evolution. According to the characteristic that output is relevant to state transition in FSM, this algorithm divides the chromosome representing FSM into state transition gene and output gene for stage-by-stage evolution. Experimental results indicate that this improved GA greatly decreases the complexity of FSM evolution and gets better performance.
2007, 36(2): 199-202.
Abstract:
Ultraviolet (UV) communication bases on atmosphere scatter and absorption. The structure parameters of system are important to UV system. The relationship between transmitter, receiver apex angle, beam divergence, and the value of loss-time delay are simulated by model developed by Luegtten. Energy distributing is elicited in the fixed angles. The value of loss and time-delay is given by simulation calculating in different conditions.
Ultraviolet (UV) communication bases on atmosphere scatter and absorption. The structure parameters of system are important to UV system. The relationship between transmitter, receiver apex angle, beam divergence, and the value of loss-time delay are simulated by model developed by Luegtten. Energy distributing is elicited in the fixed angles. The value of loss and time-delay is given by simulation calculating in different conditions.
2007, 36(2): 203-206.
Abstract:
This paper investigates the technology of determining the attitude of rotating flying object moving at high speed. By installing the microwave antenna and gravity accelerometer to the rotating flying object, the Digital Signal Processing (DSP) systems inside it can receive the linear polarization electromagnetic wave emitted by the land microwave transmitter and the output signal of the accelerometer. Then the DSP systems can determine the attitude of rotating flying object in precision. Our research indicates that this technology has the advantages including the speediness of determining the attitude,low cost of systems, small size and high efficiency of anti-overloading.
This paper investigates the technology of determining the attitude of rotating flying object moving at high speed. By installing the microwave antenna and gravity accelerometer to the rotating flying object, the Digital Signal Processing (DSP) systems inside it can receive the linear polarization electromagnetic wave emitted by the land microwave transmitter and the output signal of the accelerometer. Then the DSP systems can determine the attitude of rotating flying object in precision. Our research indicates that this technology has the advantages including the speediness of determining the attitude,low cost of systems, small size and high efficiency of anti-overloading.
2007, 36(2): 207-209.
Abstract:
In the lower Signal to Noise (S/N) ratio Direct Sequence Spread Spectrum (DS/SS) signals, the estimated Pseudo-Noise (PN) sequence has a problem of phase indetermination in the method based on eignanalysis techniques. In this paper, we propose a simple and valid approach to blind synchronization of DS/SS signals. The problem above can be resolved by the blind synchronization algorithm. The theoretic analysis and experimental results show that the approach can work well on the lower S/N ratio input signals.
In the lower Signal to Noise (S/N) ratio Direct Sequence Spread Spectrum (DS/SS) signals, the estimated Pseudo-Noise (PN) sequence has a problem of phase indetermination in the method based on eignanalysis techniques. In this paper, we propose a simple and valid approach to blind synchronization of DS/SS signals. The problem above can be resolved by the blind synchronization algorithm. The theoretic analysis and experimental results show that the approach can work well on the lower S/N ratio input signals.
2007, 36(2): 210-212,287.
Abstract:
A novel fast convergence blind equalization algorithm based on recurrent neural network is proposed. Four-order statistics of the observation signals are used to calculate the cost function in order to simplify the complexity of the equalization system. Real-time recursion training algorithm is used to dynamically adjust the system parameters. The blind equalization algorithm is "equanimous" and the characteristic of convergence is not influenced by distortion of channel, it is fit for equalizing deep attenuation channel. Simulation results show that the algorithm has good performance on convergence speed and compensating for inter-symbol interference created by multi-path within non-linear channel.
A novel fast convergence blind equalization algorithm based on recurrent neural network is proposed. Four-order statistics of the observation signals are used to calculate the cost function in order to simplify the complexity of the equalization system. Real-time recursion training algorithm is used to dynamically adjust the system parameters. The blind equalization algorithm is "equanimous" and the characteristic of convergence is not influenced by distortion of channel, it is fit for equalizing deep attenuation channel. Simulation results show that the algorithm has good performance on convergence speed and compensating for inter-symbol interference created by multi-path within non-linear channel.
2007, 36(2): 213-216.
Abstract:
The performance of airborne radar strongly depends on the statistical distribution, the power spectral character and the fluctuation of the ground clutter. This paper presents a clutter modeling method using waveform synthesis theory in order to provide ground clutter simulation for analyzing airborne radar system. Compared with conventional modeling method that uses the distribution and power spectrum of clutter, this method can generate ground clutter data with a given distribution, power spectrum and fluctuation simultaneously. Comparison of simulation results and real radar clutter indicates that this method can model ground clutter of airborne radar more accurate than the conventional method.
The performance of airborne radar strongly depends on the statistical distribution, the power spectral character and the fluctuation of the ground clutter. This paper presents a clutter modeling method using waveform synthesis theory in order to provide ground clutter simulation for analyzing airborne radar system. Compared with conventional modeling method that uses the distribution and power spectrum of clutter, this method can generate ground clutter data with a given distribution, power spectrum and fluctuation simultaneously. Comparison of simulation results and real radar clutter indicates that this method can model ground clutter of airborne radar more accurate than the conventional method.
2007, 36(2): 217-219,274.
Abstract:
To improve tracking accuracy and stability of optic-electronic target tracking system, the conception of generalized synergic target and an algorithm named error-space estimation method are presented. In this algorithm, the motion of target is described by leading data and leading errors, then maneuver of target is separated into leading data and leading errors to reduce maneuver level. The prediction data of target position are acquired by synthesizing the filtering data from target state-space according to kinematics model and the prediction data from error-space according to leading error model. Differing from typical multi-model method, the kinematics model and leading error model work concurrently rather than switch between models. Experiment results show that the performance of the algorithm is better than Kalman filter and strong tracking filter at same maneuver level.
To improve tracking accuracy and stability of optic-electronic target tracking system, the conception of generalized synergic target and an algorithm named error-space estimation method are presented. In this algorithm, the motion of target is described by leading data and leading errors, then maneuver of target is separated into leading data and leading errors to reduce maneuver level. The prediction data of target position are acquired by synthesizing the filtering data from target state-space according to kinematics model and the prediction data from error-space according to leading error model. Differing from typical multi-model method, the kinematics model and leading error model work concurrently rather than switch between models. Experiment results show that the performance of the algorithm is better than Kalman filter and strong tracking filter at same maneuver level.
2007, 36(2): 220-222,297.
Abstract:
In this paper a C-band feeding circuit with 5% relative bandwidth is realized. Firstly the 3D electromagnetic simulation software HFSS and DESIGNER are used to give an initial simulation of the feeding circuit. Then it is realized in a hardware system. Testing results show that the Voltage Standing Wave Ratio(VSWR) is below 1.30 and the phase error is less than 9°. This network has been successfully applied in feeding a line array.
In this paper a C-band feeding circuit with 5% relative bandwidth is realized. Firstly the 3D electromagnetic simulation software HFSS and DESIGNER are used to give an initial simulation of the feeding circuit. Then it is realized in a hardware system. Testing results show that the Voltage Standing Wave Ratio(VSWR) is below 1.30 and the phase error is less than 9°. This network has been successfully applied in feeding a line array.
2007, 36(2): 223-226.
Abstract:
A novel High Temperature Superconducting (HTS) receiver front-end with limiting and selfprotective abilities is proposed aiming at resolving the problems in mobile communication such as lack of frequency resources and regular channel block and so on. A novel HTS microwave filter with the function of limi-filter is adopted and located before low noise amplifier. Based on the excellent filtering and limiting abilities of HTS limi-filter, the receiver front-end with limiting and self-protective abilities is realized. Experimental results show that when input power is -10 dBm, the insertion loss of HTS limi-filter is 0.2 dB and the Standing Wave Ratio (SWR) is less than 1.4; when input power is 15 dBm, the limiting depth of signal is 10 dB. The SWR and Noise Figure (NF) of HTS receiver front-end manufactured by mixed technology is less than 0.7 dB.
A novel High Temperature Superconducting (HTS) receiver front-end with limiting and selfprotective abilities is proposed aiming at resolving the problems in mobile communication such as lack of frequency resources and regular channel block and so on. A novel HTS microwave filter with the function of limi-filter is adopted and located before low noise amplifier. Based on the excellent filtering and limiting abilities of HTS limi-filter, the receiver front-end with limiting and self-protective abilities is realized. Experimental results show that when input power is -10 dBm, the insertion loss of HTS limi-filter is 0.2 dB and the Standing Wave Ratio (SWR) is less than 1.4; when input power is 15 dBm, the limiting depth of signal is 10 dB. The SWR and Noise Figure (NF) of HTS receiver front-end manufactured by mixed technology is less than 0.7 dB.
2007, 36(2): 227-229.
Abstract:
The effect of metallic pit prop on transmission characteristics in tunnel is studied. A fork waveguide model is proposed and the mode matching and multi-mode network technique are used to analyze the transmission characteristics of rectangular tunnel with metallic pit prop. The change of the reflection coefficient of dominant mode with working frequency, the row number of metallic pit prop, and pit prop diameter are obtained, respectively. The present approach can be used to analyze other discontinuity problems caused by metallic obstacle in rectangular tunnel.
The effect of metallic pit prop on transmission characteristics in tunnel is studied. A fork waveguide model is proposed and the mode matching and multi-mode network technique are used to analyze the transmission characteristics of rectangular tunnel with metallic pit prop. The change of the reflection coefficient of dominant mode with working frequency, the row number of metallic pit prop, and pit prop diameter are obtained, respectively. The present approach can be used to analyze other discontinuity problems caused by metallic obstacle in rectangular tunnel.
2007, 36(2): 230-231,301.
Abstract:
On the basis of the perturbation formulae of the g-factors (fourth-order) and the hyperfine structure constants (third-order) for a 3d9 ion in tetragonal symmetry (elongated octahedra), the spin Hamiltonian parameters for the Cu2+-doped LaSrAlO4 crystal are theoretically investigated. In the calculations, the tetragonal field parameters Ds and Dt are determined from the superposition model and the local structure of the impurity center; and the core polarization constant κ ≈0.286. Based on the studies, it is found that the calculated values show good agreement with the experimental data. In addition, the negative sign of A// is also determined theoretically.
On the basis of the perturbation formulae of the g-factors (fourth-order) and the hyperfine structure constants (third-order) for a 3d9 ion in tetragonal symmetry (elongated octahedra), the spin Hamiltonian parameters for the Cu2+-doped LaSrAlO4 crystal are theoretically investigated. In the calculations, the tetragonal field parameters Ds and Dt are determined from the superposition model and the local structure of the impurity center; and the core polarization constant κ ≈0.286. Based on the studies, it is found that the calculated values show good agreement with the experimental data. In addition, the negative sign of A// is also determined theoretically.
2007, 36(2): 232-234.
Abstract:
Based on the microwave biological effects, the mechanism of electroporation, and the theory of electromagnetic, a λ/4 coaxial resonant structure of microwave sterilization is simulated and analyzed with CST software in this paper The results of simulation indicates that when the input power reaches 100 W, the amplitude of the E-field in the area of sterilization will attain 106 V/m. So the cell of virus will be punctured; and the air can be sterilized fast.
Based on the microwave biological effects, the mechanism of electroporation, and the theory of electromagnetic, a λ/4 coaxial resonant structure of microwave sterilization is simulated and analyzed with CST software in this paper The results of simulation indicates that when the input power reaches 100 W, the amplitude of the E-field in the area of sterilization will attain 106 V/m. So the cell of virus will be punctured; and the air can be sterilized fast.
2007, 36(2): 235-238.
Abstract:
A distributed security management method of network forensic log is proposed and designed in this paper. The log agents and management gateway collect and forward the log records to the multi-management nodes. The log records are respectively dispersed into n shares by information dispersal arithmetic in the node, and the node stores the corresponding share and the hash values of all shares. The management node can reconstruct the log records through corresponding information in m (mn) random nodes and validate the integrity of the log records through the hash values of all shares.
A distributed security management method of network forensic log is proposed and designed in this paper. The log agents and management gateway collect and forward the log records to the multi-management nodes. The log records are respectively dispersed into n shares by information dispersal arithmetic in the node, and the node stores the corresponding share and the hash values of all shares. The management node can reconstruct the log records through corresponding information in m (mn) random nodes and validate the integrity of the log records through the hash values of all shares.
2007, 36(2): 239-241,270.
Abstract:
In the Linux kernel-based Distributed and Parallel Security Operating System (DPSOS), the system security is not assured because of the lack of global user identification and access right managing mechanism. On the basis of analyzing the mechanism of user authority verification, this paper presents an algorithm to achieve the user consistency. This algorithm consists of global synchronizing algorithm and user information consistency protocol. Through tests, it has been proved that the algorithm can guarantee the user consistency of the system effectively.
In the Linux kernel-based Distributed and Parallel Security Operating System (DPSOS), the system security is not assured because of the lack of global user identification and access right managing mechanism. On the basis of analyzing the mechanism of user authority verification, this paper presents an algorithm to achieve the user consistency. This algorithm consists of global synchronizing algorithm and user information consistency protocol. Through tests, it has been proved that the algorithm can guarantee the user consistency of the system effectively.
2007, 36(2): 242-245.
Abstract:
Cloth motion simulation is a hot topic in computer graphics. To cope with requirements such as real-time, realism and stability cloth motion, this paper proposes a cloth movement simulation approach, which focuses on the cloth motion model and the integral algorithm. The simulation results show that the proposed algorithm has good performance and is easy to implement.
Cloth motion simulation is a hot topic in computer graphics. To cope with requirements such as real-time, realism and stability cloth motion, this paper proposes a cloth movement simulation approach, which focuses on the cloth motion model and the integral algorithm. The simulation results show that the proposed algorithm has good performance and is easy to implement.
2007, 36(2): 246-249.
Abstract:
With the rapid deployment of multimedia applications, the need for real-time scheduling in embedded system continues to increase. However, the strict preemptive nature of traditional scheduling algorithms such as Rate-Monotonic (RM) and Earliest-Deadline-First (EDF) leads to inefficiencies specially in application to schedule protocol processing at high speeds or multimedia encode/decode computation. This paper presents a modified RM scheme called RM with Delayed Preemption (DP-RM). The analysis shows that our scheme solves some scheduling efficiency problems.
With the rapid deployment of multimedia applications, the need for real-time scheduling in embedded system continues to increase. However, the strict preemptive nature of traditional scheduling algorithms such as Rate-Monotonic (RM) and Earliest-Deadline-First (EDF) leads to inefficiencies specially in application to schedule protocol processing at high speeds or multimedia encode/decode computation. This paper presents a modified RM scheme called RM with Delayed Preemption (DP-RM). The analysis shows that our scheme solves some scheduling efficiency problems.
2007, 36(2): 250-253.
Abstract:
Based on the characteristics of the contention relationship between flows in Ad hoc networks, the notion of the link's interference set is introduced in this paper, and then a price framework based on the link's interference set is built. In such a price framework, the aggregated price over the link interference set is interpreted as the congestion information about this link. Correspondingly, a distributed algorithm, Price Coordination Approach (PCA), is presented to solve the congestion control problem for small time interval; and adaptation of PCA for the uncertain changes of network scenarios is analyzed. Simulation results show that PCA can quickly converge to globally optimal solutions. Compared with the Additional Increase Multiplicative Decrease (AIMD) algorithm in TCP-Reno, PCA is more adaptive to time-varying network situations and achieves better network performance.
Based on the characteristics of the contention relationship between flows in Ad hoc networks, the notion of the link's interference set is introduced in this paper, and then a price framework based on the link's interference set is built. In such a price framework, the aggregated price over the link interference set is interpreted as the congestion information about this link. Correspondingly, a distributed algorithm, Price Coordination Approach (PCA), is presented to solve the congestion control problem for small time interval; and adaptation of PCA for the uncertain changes of network scenarios is analyzed. Simulation results show that PCA can quickly converge to globally optimal solutions. Compared with the Additional Increase Multiplicative Decrease (AIMD) algorithm in TCP-Reno, PCA is more adaptive to time-varying network situations and achieves better network performance.
2007, 36(2): 254-256,308.
Abstract:
Based on the discussion of the existing distributed job scheduling schemes, a distributed job scheduling based on the resource availability threshold is proposed in this paper. In our scheme the resource status is investigated accurately according to the performance of and workloads on the resource; and the resources are selected for the requests of jobs according to the predetermined resource availability threshold. The simulation results show that the proposed scheme can reduce the average job wait time and the average job response time, and has better performance than the existing distributed schemes.
Based on the discussion of the existing distributed job scheduling schemes, a distributed job scheduling based on the resource availability threshold is proposed in this paper. In our scheme the resource status is investigated accurately according to the performance of and workloads on the resource; and the resources are selected for the requests of jobs according to the predetermined resource availability threshold. The simulation results show that the proposed scheme can reduce the average job wait time and the average job response time, and has better performance than the existing distributed schemes.
2007, 36(2): 257-259.
Abstract:
At present, the network security has become a global problem. The traditional network security measures can only detect the known intrusion. The honeypot has become a valid method to trap the attackers. In this paper, a new network intrusion detection system is designed based on the Honeypot technology. the tracking and analysis for network intrusion are realized. that this method is useful.
At present, the network security has become a global problem. The traditional network security measures can only detect the known intrusion. The honeypot has become a valid method to trap the attackers. In this paper, a new network intrusion detection system is designed based on the Honeypot technology. the tracking and analysis for network intrusion are realized. that this method is useful.
2007, 36(2): 260-262,324.
Abstract:
An automatic On Screen Display(OSD) fake code generation system that addressed the problem of ineffective OSD design is proposed and realized in this paper. The system could be used to design any type of OSD interface in a hassle free way. The application result indicates that software development period could be shorten by this system efficiently.
An automatic On Screen Display(OSD) fake code generation system that addressed the problem of ineffective OSD design is proposed and realized in this paper. The system could be used to design any type of OSD interface in a hassle free way. The application result indicates that software development period could be shorten by this system efficiently.
2007, 36(2): 263-266.
Abstract:
A structure of platform for automatically producing Word design documents is introduced. The design idea is derived in consideration Visual Bisic for Application (VBA), ActiveX, Date Object (ADO) and Active Server Pages (ASP) techniques. The platform is composed of building document templates database, designing making tool of document templates and establishing application of B/S mode for producing documents automatically. The platform is applied to documents designing of satellite thermal control system successfully. It improves work efficiency and standardization greatly.
A structure of platform for automatically producing Word design documents is introduced. The design idea is derived in consideration Visual Bisic for Application (VBA), ActiveX, Date Object (ADO) and Active Server Pages (ASP) techniques. The platform is composed of building document templates database, designing making tool of document templates and establishing application of B/S mode for producing documents automatically. The platform is applied to documents designing of satellite thermal control system successfully. It improves work efficiency and standardization greatly.
2007, 36(2): 267-270.
Abstract:
The traffic black-spot cause of formation is very complex, and every black-spot has the most important inducement for itself. The identification and improvement of black-spot, as an important task of traffic safety management, are very effect measures to reduce the traffic accident frequency. For the complexity and diversity of the black-spot cause of formation, we find a method based on the rough set to determine the most important inducement of the black-spot, then we can repair the inducement in effect and save more time and money.
The traffic black-spot cause of formation is very complex, and every black-spot has the most important inducement for itself. The identification and improvement of black-spot, as an important task of traffic safety management, are very effect measures to reduce the traffic accident frequency. For the complexity and diversity of the black-spot cause of formation, we find a method based on the rough set to determine the most important inducement of the black-spot, then we can repair the inducement in effect and save more time and money.
2007, 36(2): 271-274.
Abstract:
Power management is one of the most important key for lower power design of wearable computing system. A method for dynamic power management of wearable computer based on ant algorithm is proposed in this paper. Through optimizing the power conversion time adaptively, this method can reduce the mean power consumption of each module and extend the working time of the wearable computing system. The experiment results show its validity.
Power management is one of the most important key for lower power design of wearable computing system. A method for dynamic power management of wearable computer based on ant algorithm is proposed in this paper. Through optimizing the power conversion time adaptively, this method can reduce the mean power consumption of each module and extend the working time of the wearable computing system. The experiment results show its validity.
2007, 36(2): 275-277.
Abstract:
This paper proposes an Electronic Commerce (EC) system frame based on grid and multi-agent negotiation strategy. Resources and users can be reasonably organized and managed, thus information isolated island can be eliminated and searching efficiency can be improved. This paper employ Broke Agent (BA) to control transaction process. BA collects real-time information and provider parameters referenced in negotiation. ABuyer and AProvider are used to represent buyer and provider respectively and realize independent negotiation. Flexible and self-adaptive negotiation strategies are designed to improve performance and efficiency of negotiation.
This paper proposes an Electronic Commerce (EC) system frame based on grid and multi-agent negotiation strategy. Resources and users can be reasonably organized and managed, thus information isolated island can be eliminated and searching efficiency can be improved. This paper employ Broke Agent (BA) to control transaction process. BA collects real-time information and provider parameters referenced in negotiation. ABuyer and AProvider are used to represent buyer and provider respectively and realize independent negotiation. Flexible and self-adaptive negotiation strategies are designed to improve performance and efficiency of negotiation.
2007, 36(2): 278-280,290.
Abstract:
In this paper, a general definition of meta-learning is proposed. The selection of learning algorithms in meta-learning is investigated from the point of bias/variance decomposition as well as the effect of correlation on its accuracy. In order to obtain classifiers with variable correlation, artificial datasets are generated based on the simulating algorithm presented in the paper. Experiments are performed on UCI datasets and simulated datasets and show that meta-learning outperforms several combining methods averagely; and that negative correlation measured by Q statistic benefits meta-learning approach.
In this paper, a general definition of meta-learning is proposed. The selection of learning algorithms in meta-learning is investigated from the point of bias/variance decomposition as well as the effect of correlation on its accuracy. In order to obtain classifiers with variable correlation, artificial datasets are generated based on the simulating algorithm presented in the paper. Experiments are performed on UCI datasets and simulated datasets and show that meta-learning outperforms several combining methods averagely; and that negative correlation measured by Q statistic benefits meta-learning approach.
2007, 36(2): 281-284.
Abstract:
For large-scale distributed data sets, a new hierarchical mining model based on mobile agent is proposed to perform distributed mining tasks. Based on hierarchical idea, the proposed approach integrates multiple local results using mobile agent and incremental optimization. The experimental results demonstrate that the proposed approach is scalable and particularly suited to large-scale distributed environments. In addition, the proposed model can reduce dramatically communication cost based on network characteristics.
For large-scale distributed data sets, a new hierarchical mining model based on mobile agent is proposed to perform distributed mining tasks. Based on hierarchical idea, the proposed approach integrates multiple local results using mobile agent and incremental optimization. The experimental results demonstrate that the proposed approach is scalable and particularly suited to large-scale distributed environments. In addition, the proposed model can reduce dramatically communication cost based on network characteristics.
2007, 36(2): 285-287.
Abstract:
Silica-Ni-P composite coating is fabricated by dip-coating onto a 200-mesh copper-screen substrate. The sensing characteristics of the oxygen photosensor is studied with[Ru(bpy)3]Cl2 as sensing element and Silica-Ni-P composite coating as support system. The sample coating has good repeatability, photostability, sensitivity, and good response to oxygen; it accords with Stern-Volmer equation during the oxygen concentration range 0%~20%.
Silica-Ni-P composite coating is fabricated by dip-coating onto a 200-mesh copper-screen substrate. The sensing characteristics of the oxygen photosensor is studied with[Ru(bpy)3]Cl2 as sensing element and Silica-Ni-P composite coating as support system. The sample coating has good repeatability, photostability, sensitivity, and good response to oxygen; it accords with Stern-Volmer equation during the oxygen concentration range 0%~20%.
2007, 36(2): 288-290.
Abstract:
A automatic resolution measurement system of Cathode Ray Tubes (CRT), display tubes has been developed. The width of a scanning line displayed at screen can be measured accurately and quickly by an area array Charge Coupled Device (CCD) camera with a microscope lens. The system has voltage auto-adjusting functions of optics focusing and CRT's focusing. Measuring results show that the auto-adjusting improves the precision and efficiency of the measurement effectively.
A automatic resolution measurement system of Cathode Ray Tubes (CRT), display tubes has been developed. The width of a scanning line displayed at screen can be measured accurately and quickly by an area array Charge Coupled Device (CCD) camera with a microscope lens. The system has voltage auto-adjusting functions of optics focusing and CRT's focusing. Measuring results show that the auto-adjusting improves the precision and efficiency of the measurement effectively.
2007, 36(2): 291-293.
Abstract:
Based on Friston's Blood Oxygenation Level Dependent (BOLD) dynamic model, an extended BOLD dynamic model is proposed in combination with Agnes Aubert's coupling model of brain electrical activity and metabolism. In this model, the cerebral metabolism is connected with blood flow or blood volume of the hemo-dynamic model after discussion of nonlinear character of the blood flow in hemo-dynamic model. The better simulation effect of physiological process is achieved with the restructured input signal of the BOLD model.
Based on Friston's Blood Oxygenation Level Dependent (BOLD) dynamic model, an extended BOLD dynamic model is proposed in combination with Agnes Aubert's coupling model of brain electrical activity and metabolism. In this model, the cerebral metabolism is connected with blood flow or blood volume of the hemo-dynamic model after discussion of nonlinear character of the blood flow in hemo-dynamic model. The better simulation effect of physiological process is achieved with the restructured input signal of the BOLD model.
2007, 36(2): 294-297.
Abstract:
The control strategies for Compressed Natural Gas (CNG) engine air-fuel ratio of ProportionalIntegral-Derivative (PID) control, fuzzy self-adapting setting PID control and neural network control are introduced systemically. The simulation model is established. The character of these different control strategies are analyzed according to the simulation results. Lastly, the problems which need to be attended in practical applications are pointed out.
The control strategies for Compressed Natural Gas (CNG) engine air-fuel ratio of ProportionalIntegral-Derivative (PID) control, fuzzy self-adapting setting PID control and neural network control are introduced systemically. The simulation model is established. The character of these different control strategies are analyzed according to the simulation results. Lastly, the problems which need to be attended in practical applications are pointed out.
2007, 36(2): 298-301.
Abstract:
To provide a virtual manufacturing environment and verify machining process, research on the simulation method for machining process on computer is conducted in the paper. A simulation system for machining process is developed based on OpenGL by Visual C++6.0. In the system, the simulation of 17 kinds of often used machining, including turning, milling, planning, grinding, etc., is realized. The animation of cutting tools movement and the material removing of part can be controlled by some process parameters, such as cutting speed and cutting path. The time and cost of machining can be computed automatically and optimized. The system is user-friendly and ease-to-use and can run rightly and effectively.
To provide a virtual manufacturing environment and verify machining process, research on the simulation method for machining process on computer is conducted in the paper. A simulation system for machining process is developed based on OpenGL by Visual C++6.0. In the system, the simulation of 17 kinds of often used machining, including turning, milling, planning, grinding, etc., is realized. The animation of cutting tools movement and the material removing of part can be controlled by some process parameters, such as cutting speed and cutting path. The time and cost of machining can be computed automatically and optimized. The system is user-friendly and ease-to-use and can run rightly and effectively.
2007, 36(2): 302-304.
Abstract:
The optimal motion planning problem of four wheeled mobile robot systems, due to the nonholonomic constraints, is usually transformed into an optimal control problem of nonlinear system. The ameliorated genetic algorithm of optimal control for motion planning is presented with encoding the optimized variables with float-point number. The strategy the best individual to be reserved in the ameliorated genetic algorithm operation is applied. With appropriate crossover parameter and self-adaptive aberrance factor, the convergence of the algorithm is improved and the system's motion precision is leveraged. The numerical simulation indicates the effectiveness of the algorithm for motion control of four wheeled mobile robot systems.
The optimal motion planning problem of four wheeled mobile robot systems, due to the nonholonomic constraints, is usually transformed into an optimal control problem of nonlinear system. The ameliorated genetic algorithm of optimal control for motion planning is presented with encoding the optimized variables with float-point number. The strategy the best individual to be reserved in the ameliorated genetic algorithm operation is applied. With appropriate crossover parameter and self-adaptive aberrance factor, the convergence of the algorithm is improved and the system's motion precision is leveraged. The numerical simulation indicates the effectiveness of the algorithm for motion control of four wheeled mobile robot systems.
2007, 36(2): 305-308.
Abstract:
The major factors that contribute the working accuracy of flame cutting machine ard considered. By using the opening characteristic of software in open Computer Numerical Control (CNC) system, this paper gives a neural network method based on IGCAQBP learning algorithm to improve working accuracy. Error compensation unit based on neural network is designed and the applied error compensation function of open CNC is extended. The simulation result and the practical application indicate that this method is effective and stable.
The major factors that contribute the working accuracy of flame cutting machine ard considered. By using the opening characteristic of software in open Computer Numerical Control (CNC) system, this paper gives a neural network method based on IGCAQBP learning algorithm to improve working accuracy. Error compensation unit based on neural network is designed and the applied error compensation function of open CNC is extended. The simulation result and the practical application indicate that this method is effective and stable.
2007, 36(2): 309-311,321.
Abstract:
A navigation system for mobile robot based on simultaneous-firing sonar ring is developed. To eliminate error data due to crosstalk in the simultaneous firing, a filter method based on pattern matching using neural network is used in the system. To show the advantage of this method, a prototype of sonar ring with 24 sonar sensors is fabricated and installed to a mobile robot. As a result, a scanning rate up to 66 Hz of panoramic detection is achieved. The experimental results show that the navigation system is applicable to rapid navigation for mobile robot in unknown indoor environments.
A navigation system for mobile robot based on simultaneous-firing sonar ring is developed. To eliminate error data due to crosstalk in the simultaneous firing, a filter method based on pattern matching using neural network is used in the system. To show the advantage of this method, a prototype of sonar ring with 24 sonar sensors is fabricated and installed to a mobile robot. As a result, a scanning rate up to 66 Hz of panoramic detection is achieved. The experimental results show that the navigation system is applicable to rapid navigation for mobile robot in unknown indoor environments.
2007, 36(2): 312-314.
Abstract:
Resolution is one of the key specifications for instruments. Generally, the resolution of digitized instruments dependent on their internal Analog to Digital Converter (ADC); but few related studies are published concern with the resolution of measurement system composed of instrument and sensors. Firstly it's argued that resolution is only related to random errors; in order to improve resolution, the random fluctuations of measured results have to be decreased. Provided with mass experimental data, a formula for quantified calculating the resolution of measurement system is then presented, and 2.35σ is recommended to be an appreciated acceptable resolution. Lastly, more than 90.9% of confidence probability is proved to be achieved by using the formula.
Resolution is one of the key specifications for instruments. Generally, the resolution of digitized instruments dependent on their internal Analog to Digital Converter (ADC); but few related studies are published concern with the resolution of measurement system composed of instrument and sensors. Firstly it's argued that resolution is only related to random errors; in order to improve resolution, the random fluctuations of measured results have to be decreased. Provided with mass experimental data, a formula for quantified calculating the resolution of measurement system is then presented, and 2.35σ is recommended to be an appreciated acceptable resolution. Lastly, more than 90.9% of confidence probability is proved to be achieved by using the formula.
2007, 36(2): 315-317.
Abstract:
Negotiation is important function acting by managers. In this paper, previous research on individual personality on negotiation process is reviewed,conflict resolutions resulted by different personality are compared, and relation between individual cooperativeness and negotiation effectiveness is explained. The extracted conclusions provide some theoretical and practical guiding to the daily increasing negotiation activities.
Negotiation is important function acting by managers. In this paper, previous research on individual personality on negotiation process is reviewed,conflict resolutions resulted by different personality are compared, and relation between individual cooperativeness and negotiation effectiveness is explained. The extracted conclusions provide some theoretical and practical guiding to the daily increasing negotiation activities.
2007, 36(2): 318-321.
Abstract:
Based on the game theory, the confirmation of enterprise's logistics service level has been seen as a kind of game. According to the Nash equilibrium, the model of demand distributing and use frame is built. At the same time, the relating logistics revenue function used to choosing different logistics service level is educed. The function can help the enterprise set down the optimized decision between logistics cost and logistics service level.
Based on the game theory, the confirmation of enterprise's logistics service level has been seen as a kind of game. According to the Nash equilibrium, the model of demand distributing and use frame is built. At the same time, the relating logistics revenue function used to choosing different logistics service level is educed. The function can help the enterprise set down the optimized decision between logistics cost and logistics service level.
2007, 36(2): 322-324.
Abstract:
According to the reality of dynamic alliance in China, the partner appraisement index system is established. The partner appraisement indexes are classified into several subindexes:enterprise resource, operation status, management level, geographical location, service, and enterprise culture, each subindex can be subdivided further. A new method for partner appraisement in dynamic alliance based on certainty factor is introduced to consider the uncertainty of appraisement. This method provides a useful solution for evaluating alliance partner effectively and efficiently.
According to the reality of dynamic alliance in China, the partner appraisement index system is established. The partner appraisement indexes are classified into several subindexes:enterprise resource, operation status, management level, geographical location, service, and enterprise culture, each subindex can be subdivided further. A new method for partner appraisement in dynamic alliance based on certainty factor is introduced to consider the uncertainty of appraisement. This method provides a useful solution for evaluating alliance partner effectively and efficiently.
