ISSN 
2008 Vol. 37, No. 6
2008, 37(6): 803-806.
Abstract:
In order to overcome the overfitting problem caused by noises and outliers in support vector machine, a method for non-line-of-sight (NLOS) mitigation based on fuzzy least square support vector machines (LS-SVM) is proposed. Using the fuzzy membership model based on support vector data description (SVDD), the membership values to each input sample is computed according to its distance to the center of the hypersphere with minimal volume containing all objects. Simulation results show that the proposed method is robust in NLOS environments and actually increases the accuracy of LS-SVM.
In order to overcome the overfitting problem caused by noises and outliers in support vector machine, a method for non-line-of-sight (NLOS) mitigation based on fuzzy least square support vector machines (LS-SVM) is proposed. Using the fuzzy membership model based on support vector data description (SVDD), the membership values to each input sample is computed according to its distance to the center of the hypersphere with minimal volume containing all objects. Simulation results show that the proposed method is robust in NLOS environments and actually increases the accuracy of LS-SVM.
2008, 37(6): 807-810.
Abstract:
Mining association rules is one of the primary methods used in telecommunication alarm correlation analysis. The efficiency of the algorithms plays an important role in tackling with large datasets. A highly efficient algorithm of weighted association rules mining in telecommunication networks based on weighted frequent pattern tree is proposed. The performance test of the algorithm indicates that compared with other algorithms of weighted association rules mining, this one needs less memory and has higher temporal efficiency, which is significant for the network fault diagnosis and localization.
Mining association rules is one of the primary methods used in telecommunication alarm correlation analysis. The efficiency of the algorithms plays an important role in tackling with large datasets. A highly efficient algorithm of weighted association rules mining in telecommunication networks based on weighted frequent pattern tree is proposed. The performance test of the algorithm indicates that compared with other algorithms of weighted association rules mining, this one needs less memory and has higher temporal efficiency, which is significant for the network fault diagnosis and localization.
2008, 37(6): 811-814.
Abstract:
A multicell joint adaptive resource allocation scheme is proposed for multicell orthogonal frequency division multiplexing (OFDM) systems. In order to reduce the complexity of the system, subchannel allocation and power allocation are performed in different level separately. Subchannels are dynamically allocated in every cell using modified Max C/I algorithm, and then we use tabu search (TS) to find the optimal transmit power allocation on co-channel of multicell base on the results of subchannel allocation. Performance analysis and simulation results show that the proposed scheme can increase system throughput while guarantee the minimum rate request of all users.
A multicell joint adaptive resource allocation scheme is proposed for multicell orthogonal frequency division multiplexing (OFDM) systems. In order to reduce the complexity of the system, subchannel allocation and power allocation are performed in different level separately. Subchannels are dynamically allocated in every cell using modified Max C/I algorithm, and then we use tabu search (TS) to find the optimal transmit power allocation on co-channel of multicell base on the results of subchannel allocation. Performance analysis and simulation results show that the proposed scheme can increase system throughput while guarantee the minimum rate request of all users.
2008, 37(6): 815-817,921.
Abstract:
A spectrum-aware scheduling algorithm is proposed for multimedia applications in cognitive radio system. The algorithm adaptively adjusts the resource share allocated between real-time traffic and non-real-time traffic in varying spectrum environment to provide QoS guarantee for real-time traffic. System simulation based on IEEE 802.22 wireless regional area network shows that the proposed algorithm can provide both better QoS guarantee for real-time traffic and higher system throughput and spectrum utilization compared with conventional scheduling algorithms.
A spectrum-aware scheduling algorithm is proposed for multimedia applications in cognitive radio system. The algorithm adaptively adjusts the resource share allocated between real-time traffic and non-real-time traffic in varying spectrum environment to provide QoS guarantee for real-time traffic. System simulation based on IEEE 802.22 wireless regional area network shows that the proposed algorithm can provide both better QoS guarantee for real-time traffic and higher system throughput and spectrum utilization compared with conventional scheduling algorithms.
2008, 37(6): 818-822.
Abstract:
A novel low-complexity frequency-domain implementation method is proposed for the receiving algorithm combined frequency domain equalization and interference cancellation. By using overlap-cut method, the multiuser interference (MUI) at each stage of iteration is regenerated by multiplication in frequency domain instead of by linear convolution in time domain, and then the regenerated MUI is cancelled in frequency domain. Simulation results show that the proposed method has slight bit-error-rate (BER) performance loss than conventional time-domain methods only at high SNRs, but the former is much simpler than the latter in computational complexity.
A novel low-complexity frequency-domain implementation method is proposed for the receiving algorithm combined frequency domain equalization and interference cancellation. By using overlap-cut method, the multiuser interference (MUI) at each stage of iteration is regenerated by multiplication in frequency domain instead of by linear convolution in time domain, and then the regenerated MUI is cancelled in frequency domain. Simulation results show that the proposed method has slight bit-error-rate (BER) performance loss than conventional time-domain methods only at high SNRs, but the former is much simpler than the latter in computational complexity.
2008, 37(6): 823-827.
Abstract:
Aiming at the lack of the single link's anomaly detection and the network-wide traffic's anomaly detection, we propose a network-wide multi-traffic correlative anomaly detection method. This method uses the characteristic that the anomaly signals on different links or origin-destination (OD) flows, produced by one anomaly, are similar in frequency, the transformation characteristic of the amplitude, and so on. And the comparability is used as the evidence of the anomaly detection. In principle, the traffic is forecasted by the previous data on every OD flow or link, the anomaly traffic is obtained by subtracting the real traffic from the forecast data, and lastly, the traffic anomaly is detected by global correlation analysis on all traffics. Simulation result indicates that this kind of method can detect the anomaly.
Aiming at the lack of the single link's anomaly detection and the network-wide traffic's anomaly detection, we propose a network-wide multi-traffic correlative anomaly detection method. This method uses the characteristic that the anomaly signals on different links or origin-destination (OD) flows, produced by one anomaly, are similar in frequency, the transformation characteristic of the amplitude, and so on. And the comparability is used as the evidence of the anomaly detection. In principle, the traffic is forecasted by the previous data on every OD flow or link, the anomaly traffic is obtained by subtracting the real traffic from the forecast data, and lastly, the traffic anomaly is detected by global correlation analysis on all traffics. Simulation result indicates that this kind of method can detect the anomaly.
2008, 37(6): 828-831.
Abstract:
This paper presents a theoretical analysis of time-hopping pule position modulation ultra-wideband (TH-PPM-UWB) communication system under time-varying channel condition. The effect of scatters movement is analyzed under indoor channel condition with different channel parameters by simulation. Results show that the scatters movement has a slight effect on the performance of system when the input SNR is small and the effect is increasing rapidly when the SNR is increasing. On the whole, the effect of scatters movement is not greater than that of other interferences. This conclusion is similar to those from either under LOS or NLOS condition.
This paper presents a theoretical analysis of time-hopping pule position modulation ultra-wideband (TH-PPM-UWB) communication system under time-varying channel condition. The effect of scatters movement is analyzed under indoor channel condition with different channel parameters by simulation. Results show that the scatters movement has a slight effect on the performance of system when the input SNR is small and the effect is increasing rapidly when the SNR is increasing. On the whole, the effect of scatters movement is not greater than that of other interferences. This conclusion is similar to those from either under LOS or NLOS condition.
2008, 37(6): 832-835.
Abstract:
An orthogonal frequency division multiplexing-time division duplex (OFDM-TDD) open-loop adaptive modulation (AM) system is proposed. In this system signaling symbols modulated with binary phase shift keying (BPSK) are put on the best sub-carriers in adaptive blocks. In the receiver, signaling can be recovered after the sub-carriers carrying signaling are detected utilizing the specialty of BPSK. Theoretical analysis and simulation results indicate that, the proposed method can enhance reliability of signaling transmission greatly and improve system throughput.
An orthogonal frequency division multiplexing-time division duplex (OFDM-TDD) open-loop adaptive modulation (AM) system is proposed. In this system signaling symbols modulated with binary phase shift keying (BPSK) are put on the best sub-carriers in adaptive blocks. In the receiver, signaling can be recovered after the sub-carriers carrying signaling are detected utilizing the specialty of BPSK. Theoretical analysis and simulation results indicate that, the proposed method can enhance reliability of signaling transmission greatly and improve system throughput.
2008, 37(6): 836-839.
Abstract:
In order to provide connection oriented service in Ad hoc networks, a novel multipath routing protocol, label switching multipath routing (LSMR), is proposed by combining connection oriented property of label switched path in multi-protocol label switching (MPLS) technology and advantage of multipath routing. LSMR can set up multiple node disjoint label switched paths on demand between communicating nodes and allow the entire packet forwarding operation to be executed within the link layer without intervention of the network layer. Simulation results show that compared with Ad hoc on-demand distance vector routing protocol (AODV), LSMR can decrease end-to-end delay and routing overhead while packet delivery ratio is increased.
In order to provide connection oriented service in Ad hoc networks, a novel multipath routing protocol, label switching multipath routing (LSMR), is proposed by combining connection oriented property of label switched path in multi-protocol label switching (MPLS) technology and advantage of multipath routing. LSMR can set up multiple node disjoint label switched paths on demand between communicating nodes and allow the entire packet forwarding operation to be executed within the link layer without intervention of the network layer. Simulation results show that compared with Ad hoc on-demand distance vector routing protocol (AODV), LSMR can decrease end-to-end delay and routing overhead while packet delivery ratio is increased.
2008, 37(6): 840-843.
Abstract:
A novel joint diagonalization fourth-order cumulants DOA matrix method is proposed to estimate the higher 2-D DOAs of uncorrelated narrowband signals in arbitrary Gaussian noise environments. Based on the special structure of the array, the method constructs three subarrays by exploiting fourth-order cumulants, thereby obtaining the 2-D DOAs of the array based on joint diagonalization with neither peak searching nor pair matching. The new method can handle sources with common 1-D angles and remedy the disadvantages of the methods employing pair matching in the case of low SNR, small angular separation, and other severe propagation environments. Simulation results show the effectiveness of the method.
A novel joint diagonalization fourth-order cumulants DOA matrix method is proposed to estimate the higher 2-D DOAs of uncorrelated narrowband signals in arbitrary Gaussian noise environments. Based on the special structure of the array, the method constructs three subarrays by exploiting fourth-order cumulants, thereby obtaining the 2-D DOAs of the array based on joint diagonalization with neither peak searching nor pair matching. The new method can handle sources with common 1-D angles and remedy the disadvantages of the methods employing pair matching in the case of low SNR, small angular separation, and other severe propagation environments. Simulation results show the effectiveness of the method.
2008, 37(6): 844-847,854.
Abstract:
Scalable switching fabrics can be used to implement high performance routers by employing multi-dimensional switching fabrics. But the fault probability of switching fabric also increases with the increase of components. A novel fault-tolerant algorithm on the mesh/torus, named as minimal misrouted adaptive routing (MMAR), is proposed based on deadlock recovery mechanism. According to the status of links around each fault-free node, MMAR can accommodate arbitrary shaped fault models using minimal number of virtual channels. When encountering concave fault models, through setting the position tables for the nodes within the concave regions at the surface nodes of each concave region, MMAR can minimize the length of the misrouted paths by avoiding routing the message into the irrespective holes. Performance results of a simulation on torus with 256 nodes are also given.
Scalable switching fabrics can be used to implement high performance routers by employing multi-dimensional switching fabrics. But the fault probability of switching fabric also increases with the increase of components. A novel fault-tolerant algorithm on the mesh/torus, named as minimal misrouted adaptive routing (MMAR), is proposed based on deadlock recovery mechanism. According to the status of links around each fault-free node, MMAR can accommodate arbitrary shaped fault models using minimal number of virtual channels. When encountering concave fault models, through setting the position tables for the nodes within the concave regions at the surface nodes of each concave region, MMAR can minimize the length of the misrouted paths by avoiding routing the message into the irrespective holes. Performance results of a simulation on torus with 256 nodes are also given.
2008, 37(6): 848-850,859.
Abstract:
A new algorithm for blind channel estimation is proposed. A linear precoder is applied on each pair of OFDM symbols before they enter the OFDM systems. Due to the structure introduced by precoding, a new matrix is built to make the channel state information (CSI) be its one-dimension-subspace, and the CSI is estimated by using adaptive subspace tracking techniques. Simulation results demonstrate that the presented method can decreases the influence caused by the varying data distribution, channel, and noise, and can track the variation of channel, therefore, it lowers the mean squared error (MSE) of the channel estimation and the word error rate (WER) of the communication system.
A new algorithm for blind channel estimation is proposed. A linear precoder is applied on each pair of OFDM symbols before they enter the OFDM systems. Due to the structure introduced by precoding, a new matrix is built to make the channel state information (CSI) be its one-dimension-subspace, and the CSI is estimated by using adaptive subspace tracking techniques. Simulation results demonstrate that the presented method can decreases the influence caused by the varying data distribution, channel, and noise, and can track the variation of channel, therefore, it lowers the mean squared error (MSE) of the channel estimation and the word error rate (WER) of the communication system.
2008, 37(6): 851-854.
Abstract:
Partial retransmission hybrid automatic repeat request (ARQ) scheme is presented based on soft bit value. In this scheme, bits of lower soft bit value is first transmitted in retransmission, because they are the main reason generating wrong data packet. The average bit soft value of new scheme is researched and the formula of BER in the additional white Gaussian noise (AWGN) channel is derived. Theoretic analysis and numerical results indicate that soft bit value-part repeat-hybrid automatic repeat request (SBV-PR-HARQ) could average the bit soft value and make the system have better performance.
Partial retransmission hybrid automatic repeat request (ARQ) scheme is presented based on soft bit value. In this scheme, bits of lower soft bit value is first transmitted in retransmission, because they are the main reason generating wrong data packet. The average bit soft value of new scheme is researched and the formula of BER in the additional white Gaussian noise (AWGN) channel is derived. Theoretic analysis and numerical results indicate that soft bit value-part repeat-hybrid automatic repeat request (SBV-PR-HARQ) could average the bit soft value and make the system have better performance.
2008, 37(6): 855-859.
Abstract:
The optimization of spectrum allocation based on protecting licensed link in Cognitive Radio Network is researched. A new model of spectrum allocation based on game theory is presented and a fast convergent spectrum allocation algorithm for protecting licensed link is proposed. The simulation analysis shows that the algorithm has fast convergent speed and achieves spectrum allocation optimization of cognitive radio link based on protecting licensed link; the simulation also presents the relation between network performance parameters and proportional factor, which provides a basis to algorithm application for cognitive radio network with different performance requirement.
The optimization of spectrum allocation based on protecting licensed link in Cognitive Radio Network is researched. A new model of spectrum allocation based on game theory is presented and a fast convergent spectrum allocation algorithm for protecting licensed link is proposed. The simulation analysis shows that the algorithm has fast convergent speed and achieves spectrum allocation optimization of cognitive radio link based on protecting licensed link; the simulation also presents the relation between network performance parameters and proportional factor, which provides a basis to algorithm application for cognitive radio network with different performance requirement.
2008, 37(6): 860-863,878.
Abstract:
An investigation of space-time clutter spectrum for airborne sparse array applications is given in both theory and simulation, and shown that both the rank and the spectrum of clutter covariance matrix are dependent on the sparse configuration as well as the number of temporal samples. The analysis finds that if the total aperture is unchanged and the number of half-wavelength included in any interelement spacing is lower than the number of temporal pulses, the rank of clutter covariance matrix remain unchanged, no matter how many active elements are remained. The numeric results show good agreement with the proposed theorem.
An investigation of space-time clutter spectrum for airborne sparse array applications is given in both theory and simulation, and shown that both the rank and the spectrum of clutter covariance matrix are dependent on the sparse configuration as well as the number of temporal samples. The analysis finds that if the total aperture is unchanged and the number of half-wavelength included in any interelement spacing is lower than the number of temporal pulses, the rank of clutter covariance matrix remain unchanged, no matter how many active elements are remained. The numeric results show good agreement with the proposed theorem.
2008, 37(6): 864-867.
Abstract:
Back-projection imaging algorithm is widely used in through-the-wall and ground penetrating radar(GPR) imaging because of the high image quality and being compensated easily. This paper introduces the Back-Projection(BP) algorithm to the stepped-frequency through-the-wall radar and proposes the time-minimization method to eliminate the wall's effects, such as refraction, changing in speed and attenuation. Proof of concept is provided using real data collected in a laboratory environment. The results show that the BP algorithm outputs a high quality image and the time-minimization method can eliminate the wall's effect very well.
Back-projection imaging algorithm is widely used in through-the-wall and ground penetrating radar(GPR) imaging because of the high image quality and being compensated easily. This paper introduces the Back-Projection(BP) algorithm to the stepped-frequency through-the-wall radar and proposes the time-minimization method to eliminate the wall's effects, such as refraction, changing in speed and attenuation. Proof of concept is provided using real data collected in a laboratory environment. The results show that the BP algorithm outputs a high quality image and the time-minimization method can eliminate the wall's effect very well.
2008, 37(6): 868-871.
Abstract:
In the elliptic curve cryptosystem, Scalar multiplication is the most important and computationally costliest operation, thus it becomes one of hot topics. As a generalization of double base chains, multibase chains are very suitable for efficient computation of scalar multiplications of elliptic curves because of shorter representation length and less Hamming weight. In this paper, the formulas for computing the 5-fold of an elliptic curve point P are given. Using 2, 3 and 5 as bases of the multibase chains, an efficient scalar multiplication algorithm of elliptic curve is proposed. This algorithm can offer some protections against some side-channel attacks for the huge redundancy of the multibase representation and cost less compared with stand double-and-add and nonadjacent form for scalar multiplications.
In the elliptic curve cryptosystem, Scalar multiplication is the most important and computationally costliest operation, thus it becomes one of hot topics. As a generalization of double base chains, multibase chains are very suitable for efficient computation of scalar multiplications of elliptic curves because of shorter representation length and less Hamming weight. In this paper, the formulas for computing the 5-fold of an elliptic curve point P are given. Using 2, 3 and 5 as bases of the multibase chains, an efficient scalar multiplication algorithm of elliptic curve is proposed. This algorithm can offer some protections against some side-channel attacks for the huge redundancy of the multibase representation and cost less compared with stand double-and-add and nonadjacent form for scalar multiplications.
2008, 37(6): 872-874.
Abstract:
A new application to group signature on 1-out-of-n oblivious transfer is proposed. After introducing, the transformation of 1-out-of-n oblivious transfer protocol proposed by Ref.[1], a new membership revocation method in group signature is proposed by use of the transformation protocol. The proposed method is a universal method and can be applied to any group signature scheme; however, the previous revocation methods are only applicable to a specific group signature scheme. Under the random oracle model and computational Diffie-Hellman (CDH) assumption, the proposed protocol is provably secure.
A new application to group signature on 1-out-of-n oblivious transfer is proposed. After introducing, the transformation of 1-out-of-n oblivious transfer protocol proposed by Ref.[1], a new membership revocation method in group signature is proposed by use of the transformation protocol. The proposed method is a universal method and can be applied to any group signature scheme; however, the previous revocation methods are only applicable to a specific group signature scheme. Under the random oracle model and computational Diffie-Hellman (CDH) assumption, the proposed protocol is provably secure.
2008, 37(6): 875-878.
Abstract:
A novel cross-coupled band pass filter (BPF)based on the flute resonator is proposed. Due to the adoption of the same new configuration of coupling coefficient, the distance between the two loops is clearly shortened, which offers BPF an advantage of miniaturization. The configuration is characterized by a higher Q factor by introducing two transmission zeros in the transfer-function. The structural parameter of the coupling coefficient of this configuration is achieved through the analysis of electromagnetic software CST. Thereby, the band pass filter used in X waveband is designed with a dimension of 5.9 mm×5.9 mm, in-passband insertion loss (IL) of 3.2 dB, and out-passband IL of 25 dB. The result of the experiment agrees well with simulation.
A novel cross-coupled band pass filter (BPF)based on the flute resonator is proposed. Due to the adoption of the same new configuration of coupling coefficient, the distance between the two loops is clearly shortened, which offers BPF an advantage of miniaturization. The configuration is characterized by a higher Q factor by introducing two transmission zeros in the transfer-function. The structural parameter of the coupling coefficient of this configuration is achieved through the analysis of electromagnetic software CST. Thereby, the band pass filter used in X waveband is designed with a dimension of 5.9 mm×5.9 mm, in-passband insertion loss (IL) of 3.2 dB, and out-passband IL of 25 dB. The result of the experiment agrees well with simulation.
2008, 37(6): 879-882.
Abstract:
A daptively modified characteristic basis function method (AMCBFM) based on QR factorization with a dual modified Gram-Schmidt (dual-MGS) algorithm called QR-AMCBFM is proposed. In this hybrid method, the object geometry is partitioned into distinct blocks, which are divided into near and far groups depending on distances. The primary basis functions are derived firstly. In order to get the high-level basis functions, QR factorization algorithm based on dual-MGS is applied to decompose the mutual coupling matrixes to decide that the rest interactions arising in farther blocks are ignored or not. Subsequently, the high-level characteristic basis functions and the coefficient of current are calculated. Results show that the QR-AMCBFM can solve the problems very efficiently.
A daptively modified characteristic basis function method (AMCBFM) based on QR factorization with a dual modified Gram-Schmidt (dual-MGS) algorithm called QR-AMCBFM is proposed. In this hybrid method, the object geometry is partitioned into distinct blocks, which are divided into near and far groups depending on distances. The primary basis functions are derived firstly. In order to get the high-level basis functions, QR factorization algorithm based on dual-MGS is applied to decompose the mutual coupling matrixes to decide that the rest interactions arising in farther blocks are ignored or not. Subsequently, the high-level characteristic basis functions and the coefficient of current are calculated. Results show that the QR-AMCBFM can solve the problems very efficiently.
2008, 37(6): 883-885,937.
Abstract:
Kernel discriminant analysis (KDA) is an effective method for nonlinear feature extraction in radar target recognition, but it is usually difficult to solve due to the singular problem. Based on the idea of subspace projection, an optimal kernel discriminant analysis (OKDA) is given and used to extract features from a range profile. Then, kernel-based nonlinear classifiers are applied for classification. Experimental results on both simulated and measured profiles show comparatively good recognition performance of the proposed method.
Kernel discriminant analysis (KDA) is an effective method for nonlinear feature extraction in radar target recognition, but it is usually difficult to solve due to the singular problem. Based on the idea of subspace projection, an optimal kernel discriminant analysis (OKDA) is given and used to extract features from a range profile. Then, kernel-based nonlinear classifiers are applied for classification. Experimental results on both simulated and measured profiles show comparatively good recognition performance of the proposed method.
2008, 37(6): 886-889.
Abstract:
Some disadvantages in NSGA-algorithm Ⅱ are found throngh multi-objective optimization for Pareto-optimal solutions. Three improved techniques are proposed in this paper for accelerating the convergence speed, enlarging the population diversity, and enhancing the uniformity of spread of solutions of the NSGA-Ⅱ algorithm. The three techniques are (1) sorting strategy with the accumulated fitness, (2) disconnected filling algorithm within the established threshold based on the elitism strategy, and (3) dropping strategy with the given threshold. The simulations prove that the improved algorithm has much better convergence than the traditional NSGA-algorithm. Simultaneously, a better Ⅱ optimization result of the linear antenna array patterns can be obtained as well by using this algorithm.
Some disadvantages in NSGA-algorithm Ⅱ are found throngh multi-objective optimization for Pareto-optimal solutions. Three improved techniques are proposed in this paper for accelerating the convergence speed, enlarging the population diversity, and enhancing the uniformity of spread of solutions of the NSGA-Ⅱ algorithm. The three techniques are (1) sorting strategy with the accumulated fitness, (2) disconnected filling algorithm within the established threshold based on the elitism strategy, and (3) dropping strategy with the given threshold. The simulations prove that the improved algorithm has much better convergence than the traditional NSGA-algorithm. Simultaneously, a better Ⅱ optimization result of the linear antenna array patterns can be obtained as well by using this algorithm.
2008, 37(6): 890-892,950.
Abstract:
A new degradation model includling the influence of outer-and inner-scale of turbulence is presented to restore atmospheric turbulence degradation images. This new model is derived from the wave structure function and refractive index profiles considering turbulence internal and external scale and thin lens imaging degradation function. Compared with the model derived from Kolmogorov spectrum, the new model introduces more complete transcendent constraints and is more similar to the physical characteristics of atmospheric turbulence. Aiming at the turbulent degraded images comprising aircraft targets, constrained least squares filtering method is used to test the recovery power of the new degradation model. Simulation results show the effectiveness of the new model.
A new degradation model includling the influence of outer-and inner-scale of turbulence is presented to restore atmospheric turbulence degradation images. This new model is derived from the wave structure function and refractive index profiles considering turbulence internal and external scale and thin lens imaging degradation function. Compared with the model derived from Kolmogorov spectrum, the new model introduces more complete transcendent constraints and is more similar to the physical characteristics of atmospheric turbulence. Aiming at the turbulent degraded images comprising aircraft targets, constrained least squares filtering method is used to test the recovery power of the new degradation model. Simulation results show the effectiveness of the new model.
2008, 37(6): 893-896.
Abstract:
A model for estimating and predicting the optical turbulence in the surface layer over land is presented based on Monin-Obukhov similarity theory, and some numerical analyses are carried out in comparison with other models. It is found that under unstable conditions, the optical turbulence over land with flat terrain can be well estimated by using standard meteorological parameters and some experiential data. The estimated result shows that the model is in good agreement with the measurements. When wind speed is low, the turbulence intensity (represented by refractive-index structure constant) becomes weaker with the stronger wind. The optical turbulence of some day and year is predicted with the Thiermann-Kohnle model by using geographic information and solar irradiance regularity. Finally, the refractive-index structure constant and inner scale are estimated using meteorological data measured on the spot.
A model for estimating and predicting the optical turbulence in the surface layer over land is presented based on Monin-Obukhov similarity theory, and some numerical analyses are carried out in comparison with other models. It is found that under unstable conditions, the optical turbulence over land with flat terrain can be well estimated by using standard meteorological parameters and some experiential data. The estimated result shows that the model is in good agreement with the measurements. When wind speed is low, the turbulence intensity (represented by refractive-index structure constant) becomes weaker with the stronger wind. The optical turbulence of some day and year is predicted with the Thiermann-Kohnle model by using geographic information and solar irradiance regularity. Finally, the refractive-index structure constant and inner scale are estimated using meteorological data measured on the spot.
2008, 37(6): 897-899.
Abstract:
The anisotropic g factors gx, gy and gz for Co2+ in CaTiO3 are theoretically investigated from the perturbation formulas of the g factors for a 3d7 ion in orthorhombically distorted octahedra based on the cluster approach. The related orthorhombic field parameters are determined from the local structure of the studied impurity center and the superposition model. Because the impurity Co2+ differs from the host Ti4+ in ionic radius and charge, the Co-O band lengths along two directions may suffer a relative variation by about 5.6%, yielding significant orthorhombic distortion. The calculated g factors by using the above local structure are in reasonable agreement with the experimental findings.
The anisotropic g factors gx, gy and gz for Co2+ in CaTiO3 are theoretically investigated from the perturbation formulas of the g factors for a 3d7 ion in orthorhombically distorted octahedra based on the cluster approach. The related orthorhombic field parameters are determined from the local structure of the studied impurity center and the superposition model. Because the impurity Co2+ differs from the host Ti4+ in ionic radius and charge, the Co-O band lengths along two directions may suffer a relative variation by about 5.6%, yielding significant orthorhombic distortion. The calculated g factors by using the above local structure are in reasonable agreement with the experimental findings.
2008, 37(6): 900-903,921.
Abstract:
A large of logging data must be stored in downhole imminently in the acoustic logging-while-drilling of petroleum engineering. In this paper, an efficient data compression algorithm based on wavelet networks for acoustic wave data is presented. The experiment result shows the features of algorithm such as fast parameter approximation rate and high compression ratio. It can meet the need of the high-speed real-time processing in petroleum engineering.
A large of logging data must be stored in downhole imminently in the acoustic logging-while-drilling of petroleum engineering. In this paper, an efficient data compression algorithm based on wavelet networks for acoustic wave data is presented. The experiment result shows the features of algorithm such as fast parameter approximation rate and high compression ratio. It can meet the need of the high-speed real-time processing in petroleum engineering.
2008, 37(6): 904-907.
Abstract:
To expand the realtime and embedded application of the neural network in industry control, general purpose neural netowrk processor (APP) based on multiple instruction stream and multiple data stream (MIMD) is paoposed. The tasks among PEGs, PEG, and MAC coprocessor can be processed in parallel, and also communications among PEGs and other memorys can be carried out in paralled. The processor has been simulated on FPGA and is used to implement two different neural network:the BP network used in roll eccentricity online control and the Hopfield network used in character recogonition. The simulation result shows that the performance of the proposed APP is better than that of other general methods for neural network implementition.
To expand the realtime and embedded application of the neural network in industry control, general purpose neural netowrk processor (APP) based on multiple instruction stream and multiple data stream (MIMD) is paoposed. The tasks among PEGs, PEG, and MAC coprocessor can be processed in parallel, and also communications among PEGs and other memorys can be carried out in paralled. The processor has been simulated on FPGA and is used to implement two different neural network:the BP network used in roll eccentricity online control and the Hopfield network used in character recogonition. The simulation result shows that the performance of the proposed APP is better than that of other general methods for neural network implementition.
2008, 37(6): 908-912.
Abstract:
This paper describes two parallel algorithms for geometry theorem proving based on the two traditional methods:the forward reasoning and the numerical verification method. The task partitioning, communication, and the task-scheduling algorithm are also described with the message-passing programming model. Tests on the parallel computing environment are reported. The results demonstrate that proving time of the program is shorten effectively.
This paper describes two parallel algorithms for geometry theorem proving based on the two traditional methods:the forward reasoning and the numerical verification method. The task partitioning, communication, and the task-scheduling algorithm are also described with the message-passing programming model. Tests on the parallel computing environment are reported. The results demonstrate that proving time of the program is shorten effectively.
2008, 37(6): 913-916.
Abstract:
To cope with the emerging massive application of wireless sensor networks (WSNs) and its urgent attribute demands in low-energy consumption and high-security, a security and energy considering tree (SEC-Tree) topologized structure is proposed. Based on SEC-Tree, a multi-layer and multi-path routing protocol and a self-adaptation multi-path routing algorithm are presented. By applying pairwise shared key (PSK) in SEC-Tree initialization and route maintenance, a localized technology in encryptation and identification is brought forward to ensure the protocol high security, anti-attackability, and reliability in multi-hop and multi-path route. Theoretical analysis indicates the high efficiency and security of the routing protocol.
To cope with the emerging massive application of wireless sensor networks (WSNs) and its urgent attribute demands in low-energy consumption and high-security, a security and energy considering tree (SEC-Tree) topologized structure is proposed. Based on SEC-Tree, a multi-layer and multi-path routing protocol and a self-adaptation multi-path routing algorithm are presented. By applying pairwise shared key (PSK) in SEC-Tree initialization and route maintenance, a localized technology in encryptation and identification is brought forward to ensure the protocol high security, anti-attackability, and reliability in multi-hop and multi-path route. Theoretical analysis indicates the high efficiency and security of the routing protocol.
2008, 37(6): 917-921.
Abstract:
To improve the speed and correctness of Web service matching for services composition process, a semantic matching mechanism is proposed with the help of services indexes. Based on indexes mechanism and services semantic matching algorithm for single service, a composition-oriented services semantic matching algorithm is proposed and the matching usability of service input/output is analyzed. To improve the accuracy of service matching, the semantic matching degree for services category matching is introduced, and then the computation method of overall semantic matching is provided. Experimental results show that this composition-oriented service semantic matching can enhance the efficiency of services matching based on services index.
To improve the speed and correctness of Web service matching for services composition process, a semantic matching mechanism is proposed with the help of services indexes. Based on indexes mechanism and services semantic matching algorithm for single service, a composition-oriented services semantic matching algorithm is proposed and the matching usability of service input/output is analyzed. To improve the accuracy of service matching, the semantic matching degree for services category matching is introduced, and then the computation method of overall semantic matching is provided. Experimental results show that this composition-oriented service semantic matching can enhance the efficiency of services matching based on services index.
2008, 37(6): 922-925.
Abstract:
A novel approach to available bandwidth measurement based on the link status is proposed, which is different from the packet train method. The source sends small packets as probes instead of sending packet pair/train back-to-back to achieve the link status and the available bandwidth. This method can measure the capacity and idle ratio of the targeted link. Meanwhile, in order to resolve the influence of cross traffic, the "test stream" and "test level" are designed using the corresponding fields in the IPv6 basic header. This approach is verified through simulations.
A novel approach to available bandwidth measurement based on the link status is proposed, which is different from the packet train method. The source sends small packets as probes instead of sending packet pair/train back-to-back to achieve the link status and the available bandwidth. This method can measure the capacity and idle ratio of the targeted link. Meanwhile, in order to resolve the influence of cross traffic, the "test stream" and "test level" are designed using the corresponding fields in the IPv6 basic header. This approach is verified through simulations.
2008, 37(6): 926-929.
Abstract:
In order to improve sparsity and robustness, a novel sparse penalty function based on smoothly clipped absolute diviation (SCAD) is proposed and applied to Lagrange Constraint Neural Network (LCNN). This method can solve ill-conditioned problem and improve sparsity, stability, and accuracy in blind image restoration. Both artificial and real-world data are calculated under some different restoration methods. Results of the experiments show that Lagrange constraint neural network with sparse penalty has better restoration effect.
In order to improve sparsity and robustness, a novel sparse penalty function based on smoothly clipped absolute diviation (SCAD) is proposed and applied to Lagrange Constraint Neural Network (LCNN). This method can solve ill-conditioned problem and improve sparsity, stability, and accuracy in blind image restoration. Both artificial and real-world data are calculated under some different restoration methods. Results of the experiments show that Lagrange constraint neural network with sparse penalty has better restoration effect.
2008, 37(6): 930-933.
Abstract:
A novel pipelined ADC is designed. The key circuit design includes a switch sample/hold differential folded common source, common gate op amp, a two-bit ADC, and a two-bit DAC. Since the capacitance bottom plate sampling, the fully differential structure, and the bootstrapped switch are employed, the charge injection error of switch MOSFET and the effect of clock feed-through are eliminated; the linearity, SNR, resolution, and speed of the ADC are improved. The ADC have been simulated in 0.6 μm CMOS process with input frequency of 500 kHz, sample frequency of 5 MHz, power consumption of 70 mW, and SFDR of 65dB.
A novel pipelined ADC is designed. The key circuit design includes a switch sample/hold differential folded common source, common gate op amp, a two-bit ADC, and a two-bit DAC. Since the capacitance bottom plate sampling, the fully differential structure, and the bootstrapped switch are employed, the charge injection error of switch MOSFET and the effect of clock feed-through are eliminated; the linearity, SNR, resolution, and speed of the ADC are improved. The ADC have been simulated in 0.6 μm CMOS process with input frequency of 500 kHz, sample frequency of 5 MHz, power consumption of 70 mW, and SFDR of 65dB.
2008, 37(6): 934-937.
Abstract:
Poly (vinylidene fluoride) (PVDF) modified quartz crystal microbalance (QCM) sensor has been prepared for DMMP vapor detection. The temperature influence on the performances of the sensor was emphatically investigated. The results show that the sensitivity of the sensor is higher with the working temperature closer to the glass transition temperature (Tg) of PVDF, and the absolute frequency responses of the PVDF coated QCM sensor all exhibit negative Arrhenius temperature dependency in spite of different vapor concentrations. In this case, increasing the sensor operating temperature resulted in an improved response time while worse sensor sensitivity was also observed.
Poly (vinylidene fluoride) (PVDF) modified quartz crystal microbalance (QCM) sensor has been prepared for DMMP vapor detection. The temperature influence on the performances of the sensor was emphatically investigated. The results show that the sensitivity of the sensor is higher with the working temperature closer to the glass transition temperature (Tg) of PVDF, and the absolute frequency responses of the PVDF coated QCM sensor all exhibit negative Arrhenius temperature dependency in spite of different vapor concentrations. In this case, increasing the sensor operating temperature resulted in an improved response time while worse sensor sensitivity was also observed.
2008, 37(6): 938-942.
Abstract:
Thermal effects of piezoelectric intelligent plate are studied by finite element method. A finite element model including 4 displacement nodes, 2 electric potential nodes, and 8 temperature nodes is presented in this model. The displacement field is defined by plane shell element model; the electric potential field and temperature field are all defined by means of linear interpolation. The detailed element equations are deduced by using virtual work principle. The thermal influences on dynamic characteristics, displacement response, and output voltage are analyzed. The simulation of a intelligent cantilever plate shows that the thermal effect should be considered in the response analysis of intelligent plate.
Thermal effects of piezoelectric intelligent plate are studied by finite element method. A finite element model including 4 displacement nodes, 2 electric potential nodes, and 8 temperature nodes is presented in this model. The displacement field is defined by plane shell element model; the electric potential field and temperature field are all defined by means of linear interpolation. The detailed element equations are deduced by using virtual work principle. The thermal influences on dynamic characteristics, displacement response, and output voltage are analyzed. The simulation of a intelligent cantilever plate shows that the thermal effect should be considered in the response analysis of intelligent plate.
2008, 37(6): 943-946.
Abstract:
A new path tracking control method is proposed for uncertain mobile environment and high nonlinear dynamic of differential drived robot. The method applies fuzzy control theory to obtain the appropriate velocity and angular velocity by selecting optimal parameter of fuzzy logic controller. In order to obtain the optimal planning path of mobile robot, the dynamic model of differential drived robot is presented to expand the suitable range of geometric parameter derived from fuzzy controller. The effectiveness of the method developed is verified in the design of a robot vehicle with experiment.
A new path tracking control method is proposed for uncertain mobile environment and high nonlinear dynamic of differential drived robot. The method applies fuzzy control theory to obtain the appropriate velocity and angular velocity by selecting optimal parameter of fuzzy logic controller. In order to obtain the optimal planning path of mobile robot, the dynamic model of differential drived robot is presented to expand the suitable range of geometric parameter derived from fuzzy controller. The effectiveness of the method developed is verified in the design of a robot vehicle with experiment.
2008, 37(6): 947-950.
Abstract:
A method for aero-engine electronic control system's CPU board-level collaborative simulation based on Smartmodel is presented. This method is tied in CPU module's characteristic and the project application. The models of 385EX and some peculiar component which are compatible with actual chip's property, and have escalate ability are built. The contravention of intactness and operation efficiency in board-level simulating model is figured out by PCL program, associate with software arithmetic model. The method are discussed from the simulate process of CPU module of aeroengine controller. The simulation results confirm that the method presented is concrete and effective.
A method for aero-engine electronic control system's CPU board-level collaborative simulation based on Smartmodel is presented. This method is tied in CPU module's characteristic and the project application. The models of 385EX and some peculiar component which are compatible with actual chip's property, and have escalate ability are built. The contravention of intactness and operation efficiency in board-level simulating model is figured out by PCL program, associate with software arithmetic model. The method are discussed from the simulate process of CPU module of aeroengine controller. The simulation results confirm that the method presented is concrete and effective.
2008, 37(6): 951-954.
Abstract:
A robust speed control of a gasoline engine for a mini unmanned helicopter is presented. A set of linear interval plants used for controller design is developed from step responses. According to the nonlinear nature of the engine and the induction-to-power delay of the manifold filling dynamics, a robust feedback control approach is adopted to realize the speed control of engine based on quantitative feedback theory (QFT), which can provide reference speed tracking despite the presence of torque load disturbances. The off-line simulations show that the proposed engine control strategy has quick transient response and is robust to disturbances such as overall pitch variation.
A robust speed control of a gasoline engine for a mini unmanned helicopter is presented. A set of linear interval plants used for controller design is developed from step responses. According to the nonlinear nature of the engine and the induction-to-power delay of the manifold filling dynamics, a robust feedback control approach is adopted to realize the speed control of engine based on quantitative feedback theory (QFT), which can provide reference speed tracking despite the presence of torque load disturbances. The off-line simulations show that the proposed engine control strategy has quick transient response and is robust to disturbances such as overall pitch variation.
2008, 37(6): 955-958.
Abstract:
The harmonic distortion of the double side band (DSB) algorithm for the audio directional loudspeaker is investigated. The research results show that the harmonic distortion of the DSB algorithm is only influenced by the modulation factor, and is not related to either the modulation signal frequency or the carrier signal frequency. An effective way to obtain a lower harmonic distortion reduce the modulation factor, but it will also result in a lower output signal power. It is necessary and significant for the DSB algorithm to reduce the harmonic distortion and compensate its 12 dB frequency response slope per octave simultaneously.
The harmonic distortion of the double side band (DSB) algorithm for the audio directional loudspeaker is investigated. The research results show that the harmonic distortion of the DSB algorithm is only influenced by the modulation factor, and is not related to either the modulation signal frequency or the carrier signal frequency. An effective way to obtain a lower harmonic distortion reduce the modulation factor, but it will also result in a lower output signal power. It is necessary and significant for the DSB algorithm to reduce the harmonic distortion and compensate its 12 dB frequency response slope per octave simultaneously.
2008, 37(6): 959-962.
Abstract:
The influence of static magnetic field on the properties of water is studied systematically. From experiment results, it is found that, under the action of static magnetic field, the properties of water such as viscosity, conductivity and contact angels are changed. Viscosity of water decreases with the increase of processed time and the strength of the static magnetic field, and the conductivity of water increases when the time processed by magnetic field increases. Meantime, after processed by 0.40 T magnetic filed for 30 minutes, the contact angels of water on Cu and graphite are decrease about 0.4° and 2.4°, respectively. The essential reason of above phenomena might be that the hydrogen bonding in liquid water is influenced by the static magnetic field.
The influence of static magnetic field on the properties of water is studied systematically. From experiment results, it is found that, under the action of static magnetic field, the properties of water such as viscosity, conductivity and contact angels are changed. Viscosity of water decreases with the increase of processed time and the strength of the static magnetic field, and the conductivity of water increases when the time processed by magnetic field increases. Meantime, after processed by 0.40 T magnetic filed for 30 minutes, the contact angels of water on Cu and graphite are decrease about 0.4° and 2.4°, respectively. The essential reason of above phenomena might be that the hydrogen bonding in liquid water is influenced by the static magnetic field.
