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2004 Vol. 26, No. 4
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2004, 26(4): 505-510.
Abstract:
Compared with optimal maximum-likelihood multiuser detection algorithm (MUD) in Space Division Multiuser Access (SDMA) system, probabilistic data association (PDA) algorithm is a near-optimal MUD with low complexity. This paper analyzes the relation between error judging and estimated likely-probability in the 1st iteration of PDA, then proposed the fast PDA which correcting the judging output in the 1st iteration of PDA with Euclidean distance factor. Fast PDA reduces complexity of PDA through eliminating its iterations. Simulation results show that BER of fast PDA is very close to PDA with iterations.
Compared with optimal maximum-likelihood multiuser detection algorithm (MUD) in Space Division Multiuser Access (SDMA) system, probabilistic data association (PDA) algorithm is a near-optimal MUD with low complexity. This paper analyzes the relation between error judging and estimated likely-probability in the 1st iteration of PDA, then proposed the fast PDA which correcting the judging output in the 1st iteration of PDA with Euclidean distance factor. Fast PDA reduces complexity of PDA through eliminating its iterations. Simulation results show that BER of fast PDA is very close to PDA with iterations.
2004, 26(4): 511-516.
Abstract:
This paper proposes a new method for the wireless cellular locating and tracking. The method is based on the E-OTD to get the position of the MS, and the MS profile is tracked on the bases of Markov models and detection gate. This method is concise and robust. In addition, the performance of the proposed wireless cellular locating and tracking method is evaluated by the simulations.
This paper proposes a new method for the wireless cellular locating and tracking. The method is based on the E-OTD to get the position of the MS, and the MS profile is tracked on the bases of Markov models and detection gate. This method is concise and robust. In addition, the performance of the proposed wireless cellular locating and tracking method is evaluated by the simulations.
2004, 26(4): 517-524.
Abstract:
This paper analyzes the performance of DEC- Parallel Interference Canceling(DEC-PIC) multiuser detector exploited in MC-CDMA system. It is compared with Haras Minimum Mean Square Error Combining(MMSEC) single-user detector in the uplink and downlink channels. The simulation results show that MMSEC single user de-tector is better in the downlink, and it can resist the channel estimation error. And in the uplink, the performance of the multiuser detector is better, but the large channel estimation error will bring performance degradation.
This paper analyzes the performance of DEC- Parallel Interference Canceling(DEC-PIC) multiuser detector exploited in MC-CDMA system. It is compared with Haras Minimum Mean Square Error Combining(MMSEC) single-user detector in the uplink and downlink channels. The simulation results show that MMSEC single user de-tector is better in the downlink, and it can resist the channel estimation error. And in the uplink, the performance of the multiuser detector is better, but the large channel estimation error will bring performance degradation.
2004, 26(4): 525-530.
Abstract:
The performance of infrared wireless synchronous Code Division Multiple Ac-cess(CDMA) with Pulse Position Modulation(PPM) signaling systems without optical hard limiter and with optical hard limiter using modified prime sequence codes as signature codes is analyzed. The upper bound on the bit error probability of systems without optical hard limiter and with optical hard limiter are derived taking into account the effect of multiple-user interference, the photodetector shot noise and thermal noise. Numerical results show that the performance of systems with optical hard limiter is superior to that without optical hard limiter.
The performance of infrared wireless synchronous Code Division Multiple Ac-cess(CDMA) with Pulse Position Modulation(PPM) signaling systems without optical hard limiter and with optical hard limiter using modified prime sequence codes as signature codes is analyzed. The upper bound on the bit error probability of systems without optical hard limiter and with optical hard limiter are derived taking into account the effect of multiple-user interference, the photodetector shot noise and thermal noise. Numerical results show that the performance of systems with optical hard limiter is superior to that without optical hard limiter.
2004, 26(4): 531-535.
Abstract:
A heuristic algorithm based on group local search and double spiral process is proposed in this article, which is applied to optimizing global routing with the objective of network congestion minimization. It makes use of chaos variable to find initial solutions with favorable distribution, combines with heuristic knowledge in local search process, and puts forward especial greedy rerouting and extended greedy principal, all of which are to increase efficiency and global search ability. Simulations manifest its effectiveness and notable virtual value in improving network performance.
A heuristic algorithm based on group local search and double spiral process is proposed in this article, which is applied to optimizing global routing with the objective of network congestion minimization. It makes use of chaos variable to find initial solutions with favorable distribution, combines with heuristic knowledge in local search process, and puts forward especial greedy rerouting and extended greedy principal, all of which are to increase efficiency and global search ability. Simulations manifest its effectiveness and notable virtual value in improving network performance.
2004, 26(4): 536-541.
Abstract:
Recent years, space-time coding technique is gotten more attention. However, the space-time coding application is often under non-frequeucy-selective channel while the channel knowledge is known. All of these constrains the application of space-time coding. This paper presents a differential modulation diversity used in the presence of unknown multi-path. The proposed technique utilizes orthogonal frequency division multiplexing (OFDM) transforming a frequency selective fading channel into multiple flat fading sub-channels. Based on this, a space-time-frequency configuration applied in unknown frequency selective fading channel is given. And this method is verified by the simulation results.
Recent years, space-time coding technique is gotten more attention. However, the space-time coding application is often under non-frequeucy-selective channel while the channel knowledge is known. All of these constrains the application of space-time coding. This paper presents a differential modulation diversity used in the presence of unknown multi-path. The proposed technique utilizes orthogonal frequency division multiplexing (OFDM) transforming a frequency selective fading channel into multiple flat fading sub-channels. Based on this, a space-time-frequency configuration applied in unknown frequency selective fading channel is given. And this method is verified by the simulation results.
2004, 26(4): 542-548.
Abstract:
Traffic grooming, which can multiplex many low-rate traffic streams into one wavelength, has been received much research attention. Much work related to traffic grooming has been done in WDM/SDH rings, and the work is relatively less in WDM mesh networks. In this paper, under static traffic environment, an effective heuristic traffic grooming algorithm based on plane-construction is proposed. Simulation results show that the algorithm performs better than other previously proposed algorithms.
Traffic grooming, which can multiplex many low-rate traffic streams into one wavelength, has been received much research attention. Much work related to traffic grooming has been done in WDM/SDH rings, and the work is relatively less in WDM mesh networks. In this paper, under static traffic environment, an effective heuristic traffic grooming algorithm based on plane-construction is proposed. Simulation results show that the algorithm performs better than other previously proposed algorithms.
2004, 26(4): 549-555.
Abstract:
This paper addresses the dynamic establishment of dependable connections for grooming WDM mesh networks. A shared path-protection algorithm under Shared Risk Link Group(SRLG) constraints for multi-granularity traffic is proposed. The presented scheme establishes SRLG-disjoint primarily and backups traffic stream paths between the source-destination node pairs and reduces the spare capacity. It provides the same level of protection against single SRLG failure as dedicated path-protection scheme. Moreover it is better than dedicated path-protection scheme in network utilization. Network performance, based on dynamic traffic with different load, is investigated via simulations. The results show that the scheme can improve the performance of the network significantly.
This paper addresses the dynamic establishment of dependable connections for grooming WDM mesh networks. A shared path-protection algorithm under Shared Risk Link Group(SRLG) constraints for multi-granularity traffic is proposed. The presented scheme establishes SRLG-disjoint primarily and backups traffic stream paths between the source-destination node pairs and reduces the spare capacity. It provides the same level of protection against single SRLG failure as dedicated path-protection scheme. Moreover it is better than dedicated path-protection scheme in network utilization. Network performance, based on dynamic traffic with different load, is investigated via simulations. The results show that the scheme can improve the performance of the network significantly.
2004, 26(4): 556-561.
Abstract:
In this paper, a specification method using PVS is presented. Higher order logic is chosen as the specification language. Strong spy and ideal encryption are assumed, and trace model is used to define protocols behaviors. Moreover, useful structures such as message, event, protocol rule, etc. are semantically encoded.
In this paper, a specification method using PVS is presented. Higher order logic is chosen as the specification language. Strong spy and ideal encryption are assumed, and trace model is used to define protocols behaviors. Moreover, useful structures such as message, event, protocol rule, etc. are semantically encoded.
2004, 26(4): 562-567.
Abstract:
Compared with RSA and ECC, XTR keys are much smaller than RSA keys of equivalent security, and are at most twice as big as ECC keys, but parameter and key selections for XTR are much faster than ECC. With the fast method for computing the trace of the elements in the finite field, two blind signature schemes based on extended XTR system are presented in this paper, the security is equivalent to solving discrete logarithm problem of extended XTR group while the datum is only 1/3 of the previous schemes.
Compared with RSA and ECC, XTR keys are much smaller than RSA keys of equivalent security, and are at most twice as big as ECC keys, but parameter and key selections for XTR are much faster than ECC. With the fast method for computing the trace of the elements in the finite field, two blind signature schemes based on extended XTR system are presented in this paper, the security is equivalent to solving discrete logarithm problem of extended XTR group while the datum is only 1/3 of the previous schemes.
2004, 26(4): 568-573.
Abstract:
In this paper, a new adaptive filtering algorithm is proposed based on the anal-ysis of the orthogonal projection of gradient vectors described in Lim(2000). In the new algorithm, a time-variant forgetting factor is introduced to estimate the Mean Square Er-ror(MSB) and change the updating direction of adaptive filter coefficient vector. Further-more, the new algorithm is extended to two-channel algorithm for multi-channel acoustic echo cancellation. Simulation in MATLAB shows that the new algorithm has good conver-gence and tracking capability to time-variant and time-invariant system, and can overcome the weakness in convergence and divergence of the Lims algorithm(2000). Moreover, the extended algorithm is of less computation, faster convergence, and higher accuracy when applied in multi-channel acoustic echo cancellation. Its convergent speed and accuracy are better than that of the algorithms proposed by Benesty(1996) and Sankaran(1999).
In this paper, a new adaptive filtering algorithm is proposed based on the anal-ysis of the orthogonal projection of gradient vectors described in Lim(2000). In the new algorithm, a time-variant forgetting factor is introduced to estimate the Mean Square Er-ror(MSB) and change the updating direction of adaptive filter coefficient vector. Further-more, the new algorithm is extended to two-channel algorithm for multi-channel acoustic echo cancellation. Simulation in MATLAB shows that the new algorithm has good conver-gence and tracking capability to time-variant and time-invariant system, and can overcome the weakness in convergence and divergence of the Lims algorithm(2000). Moreover, the extended algorithm is of less computation, faster convergence, and higher accuracy when applied in multi-channel acoustic echo cancellation. Its convergent speed and accuracy are better than that of the algorithms proposed by Benesty(1996) and Sankaran(1999).
2004, 26(4): 574-579.
Abstract:
An adaptive global motion estimation algorithm is proposed in this article. Based on the statistic feature of block matching moving vector, the method calculates the basic translation vector between current frame and referenced frame through a revisable parameter, and adaptively chooses processing algorithm for image sources with different characteristics. Simulation results show that the proposed algorithm not only has the ad-vantages of low complication, short delay and simple implementation, but also can highly improve the coding efficiency when PSNR varies slightly.
An adaptive global motion estimation algorithm is proposed in this article. Based on the statistic feature of block matching moving vector, the method calculates the basic translation vector between current frame and referenced frame through a revisable parameter, and adaptively chooses processing algorithm for image sources with different characteristics. Simulation results show that the proposed algorithm not only has the ad-vantages of low complication, short delay and simple implementation, but also can highly improve the coding efficiency when PSNR varies slightly.
2004, 26(4): 586-592.
Abstract:
At UHF or SHF, the notable effects of Doppler due to platform dynamics must be taken into account. This paper researches on several carrier tracking loop systems. The software with the algorithms of serial PN acquisition and full time early-late DLL, the system may achieve PN acquisition and demodulate data timely, and can be upgraded onto the chips flexibly.
At UHF or SHF, the notable effects of Doppler due to platform dynamics must be taken into account. This paper researches on several carrier tracking loop systems. The software with the algorithms of serial PN acquisition and full time early-late DLL, the system may achieve PN acquisition and demodulate data timely, and can be upgraded onto the chips flexibly.
2004, 26(4): 593-597.
Abstract:
The problem of optimal polarization filtering of partially polarized signals in the interference background is studied. With the index of Signal-to-Interference-and-Noise-Ratio (SINR) as the optimization object, a nonlinear optimization model is built. With the help of Lagrange multiplier method and properties of asymmetric matrix, the problem of SINR optimization is transferred to a root problem of a quadratic equation. Analytical expressions of two candidate solutions are achieved and the complete algorithm is presented.
The problem of optimal polarization filtering of partially polarized signals in the interference background is studied. With the index of Signal-to-Interference-and-Noise-Ratio (SINR) as the optimization object, a nonlinear optimization model is built. With the help of Lagrange multiplier method and properties of asymmetric matrix, the problem of SINR optimization is transferred to a root problem of a quadratic equation. Analytical expressions of two candidate solutions are achieved and the complete algorithm is presented.
2004, 26(4): 598-606.
Abstract:
This paper addresses the research of ground moving target imaging and posi-tioning in Synthetic Aperture Radar (SAR) system. First it analyzes the difference between ground moving target imaging process and that for stationary ones. The method brought forward in this paper uses the direction of road and bridge of the gazing ground as prior known knowledge, and it can accurately estimate the coordinates and velocities of the moving targets while t = 0. It means that the method can get the position of the moving targets and image them with the same precision as stationary targets imaging in SAR system. There is no special postulation in the proposed algorithm contrast to the conventional method which always assumes that the targets located on the vertical side of SAR at the point of t = 0. Finally two different forms of matched filters are given out for moving targets imaging and the different results are analyzed. The smearing and position shifting effect when using sta-tionary target matched filter to process the moving target echo is also analyzed at the last part.
This paper addresses the research of ground moving target imaging and posi-tioning in Synthetic Aperture Radar (SAR) system. First it analyzes the difference between ground moving target imaging process and that for stationary ones. The method brought forward in this paper uses the direction of road and bridge of the gazing ground as prior known knowledge, and it can accurately estimate the coordinates and velocities of the moving targets while t = 0. It means that the method can get the position of the moving targets and image them with the same precision as stationary targets imaging in SAR system. There is no special postulation in the proposed algorithm contrast to the conventional method which always assumes that the targets located on the vertical side of SAR at the point of t = 0. Finally two different forms of matched filters are given out for moving targets imaging and the different results are analyzed. The smearing and position shifting effect when using sta-tionary target matched filter to process the moving target echo is also analyzed at the last part.
2004, 26(4): 607-612.
Abstract:
The azimuth resolution, the Pulse Repetition Frequency(PRF) and the mapping width of the bistatic Synthetic Aperture Radar (bistatic-SAR) are studied in detail in this paper , and the analytical solutions are obtained. The computer simulation results on the azimuth resolution are presented.
The azimuth resolution, the Pulse Repetition Frequency(PRF) and the mapping width of the bistatic Synthetic Aperture Radar (bistatic-SAR) are studied in detail in this paper , and the analytical solutions are obtained. The computer simulation results on the azimuth resolution are presented.
2004, 26(4): 613-618.
Abstract:
Since the surveillance area of sky wave Over-The-Horizon Radar (OTHR) is very vast, realizing the ship detection with short coherent integration time (GIT) is an operational requirement for OTHR. However, short CIT and the resulting low Doppler resolution cannot separate the ship target from the close powerful ocean clutter. To resolve this problem, clutter cancellation algorithm can be adopted but it requires accurate estimation for clutter parameters, The conventional cancellation method only uses the maximal amplitude of Fourier transform to estimate the clutter parameters, which may not get satisfied estimation and cause imperfect clutter cancellation. In this paper, the phase information of Fourier transform is combined to provide more accurate estimation of clutter parameters. As the result, the power and spreading of clutter residue are reduced which is helpful for the ship visibility and identification. The above analysis and comparison have been demonstrated by real data.
Since the surveillance area of sky wave Over-The-Horizon Radar (OTHR) is very vast, realizing the ship detection with short coherent integration time (GIT) is an operational requirement for OTHR. However, short CIT and the resulting low Doppler resolution cannot separate the ship target from the close powerful ocean clutter. To resolve this problem, clutter cancellation algorithm can be adopted but it requires accurate estimation for clutter parameters, The conventional cancellation method only uses the maximal amplitude of Fourier transform to estimate the clutter parameters, which may not get satisfied estimation and cause imperfect clutter cancellation. In this paper, the phase information of Fourier transform is combined to provide more accurate estimation of clutter parameters. As the result, the power and spreading of clutter residue are reduced which is helpful for the ship visibility and identification. The above analysis and comparison have been demonstrated by real data.
2004, 26(4): 619-624.
Abstract:
A method of hyperspectral baud reduction based on Rough Sets (RS) and Fuzzy C-Means (FCM) clustering is proposed, which consists of the following two steps. First, Fuzzy C-Means clustering algorithm is used to classify the original bands into equivalent band groups, which employs the concept of attribute dependency defined in RS to define the distance between a group and the cluster center, viz. the correlatives of adjacent bands. Then the data is reduced by selecting the only one from each group with maximum grade of fuzzy membership. With this approach, great dimension of band is decreased while preserving much wanted information. Simulation results prove the effectiveness of this approach.
A method of hyperspectral baud reduction based on Rough Sets (RS) and Fuzzy C-Means (FCM) clustering is proposed, which consists of the following two steps. First, Fuzzy C-Means clustering algorithm is used to classify the original bands into equivalent band groups, which employs the concept of attribute dependency defined in RS to define the distance between a group and the cluster center, viz. the correlatives of adjacent bands. Then the data is reduced by selecting the only one from each group with maximum grade of fuzzy membership. With this approach, great dimension of band is decreased while preserving much wanted information. Simulation results prove the effectiveness of this approach.
2004, 26(4): 625-631.
Abstract:
This paper presents a new method of stock market time series data mining. It combines regularized neural network with rough set. The process includes preprocessing of time series and data mining. The preprocessing cleans and filters time series. Then, the time series are partitionel into a series of static patterns, which is based on the trend (i.e., increasing or decreasing) of closing price. The most important predicting attributes identified from every model form an information table. The regularized neural network is used to learn and predict the data. Rough set can extract rule knowledge in the neural network, which can be used to predict the time series behavior in the future. This method combines the generalization faculty of regularized neural network and the rule reduction capability of rough set. The experimental results demonstrate the effectiveness of the algorithm.
This paper presents a new method of stock market time series data mining. It combines regularized neural network with rough set. The process includes preprocessing of time series and data mining. The preprocessing cleans and filters time series. Then, the time series are partitionel into a series of static patterns, which is based on the trend (i.e., increasing or decreasing) of closing price. The most important predicting attributes identified from every model form an information table. The regularized neural network is used to learn and predict the data. Rough set can extract rule knowledge in the neural network, which can be used to predict the time series behavior in the future. This method combines the generalization faculty of regularized neural network and the rule reduction capability of rough set. The experimental results demonstrate the effectiveness of the algorithm.
2004, 26(4): 632-639.
Abstract:
Influence of the shielding box 011 the propagation and dispersion characteristics of microstrip has been analyzed by the spectral domain immittance approach. This greatly simplified the formulation process in traditional spectral domain method and the results remain a high level of accuracy. Numerical results show that top metal cover decreases the effective dielectric constant of microstrip, however, it does not have noticeable effects 011 the dispersion characteristics of microstrip. The results also show that metal sidewalls increase the effective dielectric constant of microstrip and lower the dispersion of microstrip.
Influence of the shielding box 011 the propagation and dispersion characteristics of microstrip has been analyzed by the spectral domain immittance approach. This greatly simplified the formulation process in traditional spectral domain method and the results remain a high level of accuracy. Numerical results show that top metal cover decreases the effective dielectric constant of microstrip, however, it does not have noticeable effects 011 the dispersion characteristics of microstrip. The results also show that metal sidewalls increase the effective dielectric constant of microstrip and lower the dispersion of microstrip.
2004, 26(4): 640-644.
Abstract:
A multi-cavity output system with radial coupling is provided with broadband characteristics (frequency dispersed distribution in broadband). In this paper, using the method of equivalent circuit, the equivalent circuit of the radial coupling multi-cavity res-onator is presented. After determining the nature of radial coupling holes, applying Kirch-hoffs second law to the circuit and resulting the equation in matrix form, the three resonance frequencies are given by solving impedance matrix obtained. One of three resonance frequen-cies, which is in middle of three is selected to obtain the mode structure and the ratio of gaps amplitude of equivalent voltage of main cavity to vice-cavity. One typical mode distribution is 2ir-ir-2ir in the radial coupling cavities, it is different from part in axial coupling cavities (two-gap extended-interaction resonantors).
A multi-cavity output system with radial coupling is provided with broadband characteristics (frequency dispersed distribution in broadband). In this paper, using the method of equivalent circuit, the equivalent circuit of the radial coupling multi-cavity res-onator is presented. After determining the nature of radial coupling holes, applying Kirch-hoffs second law to the circuit and resulting the equation in matrix form, the three resonance frequencies are given by solving impedance matrix obtained. One of three resonance frequen-cies, which is in middle of three is selected to obtain the mode structure and the ratio of gaps amplitude of equivalent voltage of main cavity to vice-cavity. One typical mode distribution is 2ir-ir-2ir in the radial coupling cavities, it is different from part in axial coupling cavities (two-gap extended-interaction resonantors).
2004, 26(4): 645-650.
Abstract:
How to select an optimum set of test points or test vectors has become very critical to analog integrated circuit fault diagnosis. A test point selection method based on testability measure is presented in this paper. Using Determinant Decision Diagrams (DDDs), symbolic transfer functions of circuit under test are constructed and its testability measure can be calculated exactly and efficiently. This method eliminates completely the unavoidable round-off errors introduced by numerical algorithms and can handle moderate or large integrated circuits.
How to select an optimum set of test points or test vectors has become very critical to analog integrated circuit fault diagnosis. A test point selection method based on testability measure is presented in this paper. Using Determinant Decision Diagrams (DDDs), symbolic transfer functions of circuit under test are constructed and its testability measure can be calculated exactly and efficiently. This method eliminates completely the unavoidable round-off errors introduced by numerical algorithms and can handle moderate or large integrated circuits.
2004, 26(4): 651-654.
Abstract:
A novel fieldmill used as space electric field sensor is introduced, accompanying with its application. Amplitude and direction of DC electric field are measured with detecting alternating induced charge varying with the rotation of a rotator. Adopting novel mechanical structure and unique circuit, the unexpected influence of space charge and ion current is eliminated to negligible level. This senor is used to detect space electric field ranging lOOV/m to 50000V/m. The experiment of space electric field detection has finished, and satisfying data are got with this sensor.
A novel fieldmill used as space electric field sensor is introduced, accompanying with its application. Amplitude and direction of DC electric field are measured with detecting alternating induced charge varying with the rotation of a rotator. Adopting novel mechanical structure and unique circuit, the unexpected influence of space charge and ion current is eliminated to negligible level. This senor is used to detect space electric field ranging lOOV/m to 50000V/m. The experiment of space electric field detection has finished, and satisfying data are got with this sensor.
2004, 26(4): 655-658.
Abstract:
In this paper, the effect on shaping of self-similar traffic is investigated through leaky bucket. Analysis and simulation show that the self-similar character of output traffic of the leaky bucket will be increased for long-range dependence traffic in heavy load con-dition because of the storage procedure. Furthermore, the heavier the short dependence traffic through the leak-bucket, the worse the performance of the network. Therefore, the storage procedure would be a rational explanation for the generation of the traffic self-similar characteristics.
In this paper, the effect on shaping of self-similar traffic is investigated through leaky bucket. Analysis and simulation show that the self-similar character of output traffic of the leaky bucket will be increased for long-range dependence traffic in heavy load con-dition because of the storage procedure. Furthermore, the heavier the short dependence traffic through the leak-bucket, the worse the performance of the network. Therefore, the storage procedure would be a rational explanation for the generation of the traffic self-similar characteristics.
2004, 26(4): 659-661.
Abstract:
The lifting scheme is a new idea of constructing wavelet filters. Its key element is to find the predict operator and the update operator. The polynomial local regression is used to find these operators in the paper. These lifting steps take integers downwardly. Then the wavelet transforms that map integers to integers are realized. The algorithm is applied to two dimensions digital image processing, and the simulation indicates that compression ratio is high with allowable distortion. The scale coefficients and wavelet coefficients are integers, thus the quantification is not needed. This brings the sigiiifican importance of the proposed algorithm for integer data compression.
The lifting scheme is a new idea of constructing wavelet filters. Its key element is to find the predict operator and the update operator. The polynomial local regression is used to find these operators in the paper. These lifting steps take integers downwardly. Then the wavelet transforms that map integers to integers are realized. The algorithm is applied to two dimensions digital image processing, and the simulation indicates that compression ratio is high with allowable distortion. The scale coefficients and wavelet coefficients are integers, thus the quantification is not needed. This brings the sigiiifican importance of the proposed algorithm for integer data compression.
2004, 26(4): 664-667.
Abstract:
The model of fractional multipole is presented for calculating the characteristic impedance of coaxial transmission line with circular outer conductor and complex inner conductor. The model has a higher accuracy in analyzing the potential of a point close to a sharp conducting edge. The validity of this model is confirmed by numerical results.
The model of fractional multipole is presented for calculating the characteristic impedance of coaxial transmission line with circular outer conductor and complex inner conductor. The model has a higher accuracy in analyzing the potential of a point close to a sharp conducting edge. The validity of this model is confirmed by numerical results.
2004, 26(4): 668-671.
Abstract:
A H-plane waveguide duplexer is analysized with a multi-mode microwave network method in this paper. This method is carried out through three steps: dividing the microwave device to be analyzed into a group of unit components at first, then numerically solving, the electromagnetic boundary-value problems of components one by one to yield their multi-mode network scattering parameters, finally re-combining all the unit components to obtain the total scattering parameters of the original devices to be analyzed.
A H-plane waveguide duplexer is analysized with a multi-mode microwave network method in this paper. This method is carried out through three steps: dividing the microwave device to be analyzed into a group of unit components at first, then numerically solving, the electromagnetic boundary-value problems of components one by one to yield their multi-mode network scattering parameters, finally re-combining all the unit components to obtain the total scattering parameters of the original devices to be analyzed.
