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2005 Vol. 27, No. 12
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2005, 27(12): 1849-1854.
Abstract:
There exists a problem that is using big quantity of training data to improve classification accuracy in remote sensing supervised classification methods. In this paper, advanced improvements are proposed for the implemented genetic hyperplane algorithm to get the advantage of using smaller quantity of training data and almost the same training effect. Generally, the principle component analysis is used to acquire the 2 principle components and the result is used to classify the data. Now that the improvement is that several bands (above 3) of remote sensing data are used simultaneously for the classification. Henceforth, the information quantity that input the classifier is incremental and the technological flow is simplified. At the same time, the number of classes from the algorithm is extended, while the time consuming is not incremental. The C/C++ is used to implement the whole process, which involve training, classification and test. The ETM+ data of Beijing is given for the classification and the good performance is acquired. The result shows that it can be fully used in practical.
There exists a problem that is using big quantity of training data to improve classification accuracy in remote sensing supervised classification methods. In this paper, advanced improvements are proposed for the implemented genetic hyperplane algorithm to get the advantage of using smaller quantity of training data and almost the same training effect. Generally, the principle component analysis is used to acquire the 2 principle components and the result is used to classify the data. Now that the improvement is that several bands (above 3) of remote sensing data are used simultaneously for the classification. Henceforth, the information quantity that input the classifier is incremental and the technological flow is simplified. At the same time, the number of classes from the algorithm is extended, while the time consuming is not incremental. The C/C++ is used to implement the whole process, which involve training, classification and test. The ETM+ data of Beijing is given for the classification and the good performance is acquired. The result shows that it can be fully used in practical.
2005, 27(12): 1855-1860.
Abstract:
In this paper, according to the physiologic structure and cognitive characteristic of the human vision system, a model of the remote sensing image analysis based on bottom-up visual attention is brought up. Then, based on the model, a novel approach to analyzing remote sensing image comes into being. It has the partial ability of visual selectivity in the human vision system. This approach is applied to the real remote sensing images, and the exciting outputs show it is effective.
In this paper, according to the physiologic structure and cognitive characteristic of the human vision system, a model of the remote sensing image analysis based on bottom-up visual attention is brought up. Then, based on the model, a novel approach to analyzing remote sensing image comes into being. It has the partial ability of visual selectivity in the human vision system. This approach is applied to the real remote sensing images, and the exciting outputs show it is effective.
2005, 27(12): 1861-1866.
Abstract:
The wide-swath method based on multi-receiver is a novel and highly accuracy wide-swath method. This method needs focus in range signal at first, so RD (Range-Doppler) arithmetic can apply to the method easily while CS (Chirp Scaling) arithmetic has some difficulties. An algorithm based on CS algorithm is proposed in this paper that can be applied in the multi-aperture wide-swath SAR method. The error and operand of this algorithm is analyzed. Finally the simulation result is present, it turn out to validate the algorithm.
The wide-swath method based on multi-receiver is a novel and highly accuracy wide-swath method. This method needs focus in range signal at first, so RD (Range-Doppler) arithmetic can apply to the method easily while CS (Chirp Scaling) arithmetic has some difficulties. An algorithm based on CS algorithm is proposed in this paper that can be applied in the multi-aperture wide-swath SAR method. The error and operand of this algorithm is analyzed. Finally the simulation result is present, it turn out to validate the algorithm.
2005, 27(12): 1867-1871.
Abstract:
In Inverse Synthetic Aperture Radar(ISAR) instantaneous imaging, to solve the problems of big computation burden and limited approach precision of adaptive chirplet transform, a fast algorithm is proposed. Based on parameter coarse estimation, it converts a multi-dimension optimization process into a problem of equation solving. Comparing with the conventional algorithm, the proposed algorithm is not only fast but also more acute. Applying the algorithm into simulating and real radar data can reconstruct ISAR images of good quality. It shows that the proposed fast algorithm is an efficient ISAR instantaneous imaging algorithm.
In Inverse Synthetic Aperture Radar(ISAR) instantaneous imaging, to solve the problems of big computation burden and limited approach precision of adaptive chirplet transform, a fast algorithm is proposed. Based on parameter coarse estimation, it converts a multi-dimension optimization process into a problem of equation solving. Comparing with the conventional algorithm, the proposed algorithm is not only fast but also more acute. Applying the algorithm into simulating and real radar data can reconstruct ISAR images of good quality. It shows that the proposed fast algorithm is an efficient ISAR instantaneous imaging algorithm.
2005, 27(12): 1872-1875.
Abstract:
In the process of SAR (Synthetic Aperture Radar) ATR (Automatic Target Recognition), man-made target detection is very important. In this paper, analyzing the characteristics of SAR images, a new method is proposed to detect man-made targets in SAR images. Firstly, the image is smoothed with the adaptive wavelet filter; the multiple speckles are removed while the edge property of SAR images is sustained. It made the detection easier. Then, the images is segmented with the 2-D C-partition fussy entropy method based on adaptive genetic algorithm. Test results show that the algorithm can detect man-made targets effectively.
In the process of SAR (Synthetic Aperture Radar) ATR (Automatic Target Recognition), man-made target detection is very important. In this paper, analyzing the characteristics of SAR images, a new method is proposed to detect man-made targets in SAR images. Firstly, the image is smoothed with the adaptive wavelet filter; the multiple speckles are removed while the edge property of SAR images is sustained. It made the detection easier. Then, the images is segmented with the 2-D C-partition fussy entropy method based on adaptive genetic algorithm. Test results show that the algorithm can detect man-made targets effectively.
2005, 27(12): 1876-1878.
Abstract:
The concept of broad-sense spotlight is put forward and the simplified space geometry model of spaceborne broad-sense spotlight SAR is built in this paper. On the base of the simplified model, the control method of antenna beam direction angle is studied. The theory for computing the real-time beam direction angle is deduced. Finally, some experimental results are presented by a group of system parameters and the theory formula is validated.
The concept of broad-sense spotlight is put forward and the simplified space geometry model of spaceborne broad-sense spotlight SAR is built in this paper. On the base of the simplified model, the control method of antenna beam direction angle is studied. The theory for computing the real-time beam direction angle is deduced. Finally, some experimental results are presented by a group of system parameters and the theory formula is validated.
2005, 27(12): 1879-1882.
Abstract:
The transient interferences, such as lightening impulse, meteor trail echoes and so on, have to be suppressed since they severely degrade the detection capability of High Frequency (HF) radar. An approach of suppressing the transient interference based on Singular Value Decomposition (SVD) is presented in this paper. In this approach, the HF radar echo is segmented and all segments constitute the columns of some matrix with its SVD computed. Firstly, it can be preliminarily judged whether the transient interference exists in the HF radar echo from the valid rank of the built matrix. Secondly, the orthogonal decomposition of the HF radar echo is obtained using the orthogonality of SVD, thus the transient interference is separated from the radar echo and so easily detected. Finally, the radar echo segment polluted by the transient interference is estimated by building the all-pole autoregressive linear prediction model. The effectiveness of this approach is demonstrated by examples of measured HF radar echo.
The transient interferences, such as lightening impulse, meteor trail echoes and so on, have to be suppressed since they severely degrade the detection capability of High Frequency (HF) radar. An approach of suppressing the transient interference based on Singular Value Decomposition (SVD) is presented in this paper. In this approach, the HF radar echo is segmented and all segments constitute the columns of some matrix with its SVD computed. Firstly, it can be preliminarily judged whether the transient interference exists in the HF radar echo from the valid rank of the built matrix. Secondly, the orthogonal decomposition of the HF radar echo is obtained using the orthogonality of SVD, thus the transient interference is separated from the radar echo and so easily detected. Finally, the radar echo segment polluted by the transient interference is estimated by building the all-pole autoregressive linear prediction model. The effectiveness of this approach is demonstrated by examples of measured HF radar echo.
2005, 27(12): 1883-1886.
Abstract:
Based on the design of three-path calibrator of SAR, this paper proposes one solution of obtaining system errors information from internal calibrator signal to correct the received SAR data in frequency domain. Compared with the methodology of extracting system phase errors from SAR echo data, the method addressed in this paper has two advantages: it is convenient to use since it is independent of ground objects; it can extract system phase errors as well as amplitude errors. Experimental results indicate that the method is very effective to improve image quality.
Based on the design of three-path calibrator of SAR, this paper proposes one solution of obtaining system errors information from internal calibrator signal to correct the received SAR data in frequency domain. Compared with the methodology of extracting system phase errors from SAR echo data, the method addressed in this paper has two advantages: it is convenient to use since it is independent of ground objects; it can extract system phase errors as well as amplitude errors. Experimental results indicate that the method is very effective to improve image quality.
2005, 27(12): 1887-1891.
Abstract:
The Direction, carrier frequency and polarization information of multi-sources are all required for many systems such as electronic surveillance. Based on one crossed dipole sensor array, a tempo-spatial expanded virtual sensor array is built, so a novel method for 2-Dimentional (2-D) Direction Of Arrive (DOA) angle, carrier frequency and 2-D polarization angle estimation is proposed. The aperture of virtual array is several times to that of real ones, so it is more suitable for multi-sources parameters estimation in high noisy environments. The estimations of all these parameters can be got simultaneously, and automatically paired in calculating process with no spectrum searching. Similar performance with ESPRIT method can be achieved by least calculating burden, or far higher performance by high calculating burden. This algorithm can be used to any plane sensor array and this character would be very useful for applications. Simulations were presented to show the capabilities of this method.
The Direction, carrier frequency and polarization information of multi-sources are all required for many systems such as electronic surveillance. Based on one crossed dipole sensor array, a tempo-spatial expanded virtual sensor array is built, so a novel method for 2-Dimentional (2-D) Direction Of Arrive (DOA) angle, carrier frequency and 2-D polarization angle estimation is proposed. The aperture of virtual array is several times to that of real ones, so it is more suitable for multi-sources parameters estimation in high noisy environments. The estimations of all these parameters can be got simultaneously, and automatically paired in calculating process with no spectrum searching. Similar performance with ESPRIT method can be achieved by least calculating burden, or far higher performance by high calculating burden. This algorithm can be used to any plane sensor array and this character would be very useful for applications. Simulations were presented to show the capabilities of this method.
2005, 27(12): 1892-1896.
Abstract:
A number of publications address the issue of the m-parameter estimation in Nakagami-m fading. The purpose of this contribution is to tackle approximate close form expression for a class of generalized moment-based estimator since it is always a transcendental equation. The details of derivation process are given. Numerical results are presented to demonstrate that the approximate estimator is not only computationally efficient but also accurate enough when compared with other estimators.
A number of publications address the issue of the m-parameter estimation in Nakagami-m fading. The purpose of this contribution is to tackle approximate close form expression for a class of generalized moment-based estimator since it is always a transcendental equation. The details of derivation process are given. Numerical results are presented to demonstrate that the approximate estimator is not only computationally efficient but also accurate enough when compared with other estimators.
2005, 27(12): 1897-1900.
Abstract:
This paper proposes a method to estimate multiple harmonic families parameters of a signal, which is based on subspace matching pursuit decomposition algorithm, and decomposes the signal into harmonic subspace adaptively. It takes advantages of interpolated FFT algorithm and the prior information of signals parameters, with high estimation precision of harmonic frequency, it has ability to distinguish signals harmonic components of different harmonic families, which have closed-spaced fundamental and harmonic frequencies. The trail indicates that it is a preferable method to estimate multiple harmonic families parameters, as it is insensitive to random phase-shift of harmonic components, and is useful to precisely estimate the fundamental, harmonic frequencies and order of a signal. This method also can be used to depict the features of a ship radiated-noise power spectrum, and to reveal the operation condition of the ship propellers. All of above show the advanced method is a valuable method for multiple harmonic parameters estimation of signals.
This paper proposes a method to estimate multiple harmonic families parameters of a signal, which is based on subspace matching pursuit decomposition algorithm, and decomposes the signal into harmonic subspace adaptively. It takes advantages of interpolated FFT algorithm and the prior information of signals parameters, with high estimation precision of harmonic frequency, it has ability to distinguish signals harmonic components of different harmonic families, which have closed-spaced fundamental and harmonic frequencies. The trail indicates that it is a preferable method to estimate multiple harmonic families parameters, as it is insensitive to random phase-shift of harmonic components, and is useful to precisely estimate the fundamental, harmonic frequencies and order of a signal. This method also can be used to depict the features of a ship radiated-noise power spectrum, and to reveal the operation condition of the ship propellers. All of above show the advanced method is a valuable method for multiple harmonic parameters estimation of signals.
2005, 27(12): 1901-1904.
Abstract:
This paper is concerned with the optimum routing and flow assignment problem in packet-switch networks. The optimum objective function is the network-wide average time delay. To make the solution be implemented reliably in real time, a neural network for shortest path computation that is a two-layer recurrent structure is applied to flow deviation method. Simulation results show that improvements can be achieved in the reliability of successful convergence and in the decrease of computation time.
This paper is concerned with the optimum routing and flow assignment problem in packet-switch networks. The optimum objective function is the network-wide average time delay. To make the solution be implemented reliably in real time, a neural network for shortest path computation that is a two-layer recurrent structure is applied to flow deviation method. Simulation results show that improvements can be achieved in the reliability of successful convergence and in the decrease of computation time.
2005, 27(12): 1905-1908.
Abstract:
Fractional delay filters are applied to a wide range such as communications, speech processing, echo cancellation, etc. Based on the multiresolution space model of signals, a method for designing optimal fractional delay FIR filters is derived in this paper. Some numerical simulations are provided to show the effectiveness of the proposed method.
Fractional delay filters are applied to a wide range such as communications, speech processing, echo cancellation, etc. Based on the multiresolution space model of signals, a method for designing optimal fractional delay FIR filters is derived in this paper. Some numerical simulations are provided to show the effectiveness of the proposed method.
2005, 27(12): 1909-1915.
Abstract:
In this paper, a fast face detection algorithm for JPEG2000 color images is presented，which combines both color and texture information in order to find a good balance between speed and detection reliability. The algorithm is designed to work directly on the wavelet compressed domain which possesses the following characters: First of all, the multi-level gradient energy presentation of face pattern is proposed, which not only can highlight the facial parts in possible face patterns, but also can address effectively the problem of unknown size in face detection in compressed domain and therefore avoid the complex resolution transform in arbitrary ratios ; secondly, the skin-color model in YCbCr space is ameliorated to improve the reliability of skin segmentation; finally, a hierarchical detector which integrates the simply rule-based classifiers and complex neural network based classifier is designed to further improve the processing speed. Experimental results show that the proposed scheme is efficient and effective.
In this paper, a fast face detection algorithm for JPEG2000 color images is presented，which combines both color and texture information in order to find a good balance between speed and detection reliability. The algorithm is designed to work directly on the wavelet compressed domain which possesses the following characters: First of all, the multi-level gradient energy presentation of face pattern is proposed, which not only can highlight the facial parts in possible face patterns, but also can address effectively the problem of unknown size in face detection in compressed domain and therefore avoid the complex resolution transform in arbitrary ratios ; secondly, the skin-color model in YCbCr space is ameliorated to improve the reliability of skin segmentation; finally, a hierarchical detector which integrates the simply rule-based classifiers and complex neural network based classifier is designed to further improve the processing speed. Experimental results show that the proposed scheme is efficient and effective.
2005, 27(12): 1916-1921.
Abstract:
Aiming at the special situation of positioning and identifying multi-targets in air, this paper has the advanced invariant moment arithmetic to carry out. Because the moments request good quality of identifying, so this paper provides a new morphological gradient image edge detection operator which can estimate orientation, and proves them in theory and practice. There are four element structures with different direction. In these operators, the blurring processing is added, it makes that the operators not only depress the noise in image, but also enhance edges definition. And then it changes the edge detection image into the binary image through the optimal threshold segmentation. It also shows a new simple arithmetic about jointing broken lines. It does not only make the targets contour smooth, but also can find the single pixel boundary with tracking. Through kinds of tests, the identifying rate has been improved, and the dependability has been strengthened.
Aiming at the special situation of positioning and identifying multi-targets in air, this paper has the advanced invariant moment arithmetic to carry out. Because the moments request good quality of identifying, so this paper provides a new morphological gradient image edge detection operator which can estimate orientation, and proves them in theory and practice. There are four element structures with different direction. In these operators, the blurring processing is added, it makes that the operators not only depress the noise in image, but also enhance edges definition. And then it changes the edge detection image into the binary image through the optimal threshold segmentation. It also shows a new simple arithmetic about jointing broken lines. It does not only make the targets contour smooth, but also can find the single pixel boundary with tracking. Through kinds of tests, the identifying rate has been improved, and the dependability has been strengthened.
2005, 27(12): 1922-1926.
Abstract:
Aim at the problem of multi-sensors target tracking in the dual band IR imaging system, a method of target tracking is presented using adaptive weighting fusion based on fuzzy inference. The algorithm firstly decides the performance of all sensors using a method integrated the BP neural network and fuzzy inference; Then, sums multi-sensors observation data adaptively with different weights based on the measure of these sensors to get the multi-sensors reconstruction observation of target position; Finally, filters the multi-sensors reconstruction observation using the Kalman filter to get the system estimate of target position. The result of experiments proved the effectiveness and robustness of the algorithm.
Aim at the problem of multi-sensors target tracking in the dual band IR imaging system, a method of target tracking is presented using adaptive weighting fusion based on fuzzy inference. The algorithm firstly decides the performance of all sensors using a method integrated the BP neural network and fuzzy inference; Then, sums multi-sensors observation data adaptively with different weights based on the measure of these sensors to get the multi-sensors reconstruction observation of target position; Finally, filters the multi-sensors reconstruction observation using the Kalman filter to get the system estimate of target position. The result of experiments proved the effectiveness and robustness of the algorithm.
2005, 27(12): 1927-1931.
Abstract:
STFT, WT, WVD and Cohens class are the useful tools of signal processing. This paper analyzes the bilinear TF based on WT, and the relation between the scalogram, VWS and Cohens class, Furthermore, the scalogram is classified into Cohens class, and then WT is generalized to TF domain(scalogram)，ambiguity domain(wavelet AF) and frequency/frequency delay domain(WSCF). The WSCF characteristics of mono-frequency, dual-frequency, WGN, and fractal stochastic noise are analyzed. Finally, a dense algorithm of discrete WT is introduced to the computation of generalized TF distribution based on WT.
STFT, WT, WVD and Cohens class are the useful tools of signal processing. This paper analyzes the bilinear TF based on WT, and the relation between the scalogram, VWS and Cohens class, Furthermore, the scalogram is classified into Cohens class, and then WT is generalized to TF domain(scalogram)，ambiguity domain(wavelet AF) and frequency/frequency delay domain(WSCF). The WSCF characteristics of mono-frequency, dual-frequency, WGN, and fractal stochastic noise are analyzed. Finally, a dense algorithm of discrete WT is introduced to the computation of generalized TF distribution based on WT.
2005, 27(12): 1932-1936.
Abstract:
Based on the interaction of tone and intonation, a new method is proposed to get the top line and the bottom line for continuous speech of mandarin, using the Minimum Mean Square Error (MMSE) principle. The research results demonstrate that the top line and the bottom line have different function to the intonation of continuous speech on the part of quantum. The paper also proposes a primary mathematical model to figure the interaction between the tone and intonation. On the basis of the extraction of two lines and the primary model, the two-lines model and the median fundamental frequency model are established separately, which provides a flexible and effective method to modify the intonation and improves the naturalness of speech synthesis system of mandarin greatly.
Based on the interaction of tone and intonation, a new method is proposed to get the top line and the bottom line for continuous speech of mandarin, using the Minimum Mean Square Error (MMSE) principle. The research results demonstrate that the top line and the bottom line have different function to the intonation of continuous speech on the part of quantum. The paper also proposes a primary mathematical model to figure the interaction between the tone and intonation. On the basis of the extraction of two lines and the primary model, the two-lines model and the median fundamental frequency model are established separately, which provides a flexible and effective method to modify the intonation and improves the naturalness of speech synthesis system of mandarin greatly.
2005, 27(12): 1937-1941.
Abstract:
This paper presents a sliding mode control method for synchronizing a class of unknown parameters time-delayed chaotic system. The variable structure control scheme provides robust synchronization even in the presence of unknown disturbance. And adaptive method is used to estimate unknown parameter. Finally, numerical results are used to show the robustness and effectiveness of the proposed control strategy.
This paper presents a sliding mode control method for synchronizing a class of unknown parameters time-delayed chaotic system. The variable structure control scheme provides robust synchronization even in the presence of unknown disturbance. And adaptive method is used to estimate unknown parameter. Finally, numerical results are used to show the robustness and effectiveness of the proposed control strategy.
2005, 27(12): 1942-1946.
Abstract:
In the paper, assuming frequency-selective channel, a recursive semi-blind joint equalization and decoding method for Alamouti space-time block code is proposed. Based on subspace-based blind equalization method, the proposed method sequentially decodes Alamouti space-time block code without channel state information by exploiting the structure of the space-time block code and a few pilot symbols. In contrast with previous block-based blind decoding methods, the proposed method is more amicable to allowing tradeoff between performance and complexity. Simulation results demonstrate the effectiveness and flexibility of the proposed method.
In the paper, assuming frequency-selective channel, a recursive semi-blind joint equalization and decoding method for Alamouti space-time block code is proposed. Based on subspace-based blind equalization method, the proposed method sequentially decodes Alamouti space-time block code without channel state information by exploiting the structure of the space-time block code and a few pilot symbols. In contrast with previous block-based blind decoding methods, the proposed method is more amicable to allowing tradeoff between performance and complexity. Simulation results demonstrate the effectiveness and flexibility of the proposed method.
2005, 27(12): 1947-1951.
Abstract:
In this article, the main point is to describe the fast decoding algorithm of [256,252] RS extended code. In order to correct the error in the received data quickly, the algorithm gets the error type and error pattern through simple parameter-comparison, then adds the error pattern to the receive data. Compared to the algorithms in existence, this algorithm has the advantages of using less hardware resources and decoding time. When this algorithm implements in hardware, its throughput is more than 400Mbit/s.
In this article, the main point is to describe the fast decoding algorithm of [256,252] RS extended code. In order to correct the error in the received data quickly, the algorithm gets the error type and error pattern through simple parameter-comparison, then adds the error pattern to the receive data. Compared to the algorithms in existence, this algorithm has the advantages of using less hardware resources and decoding time. When this algorithm implements in hardware, its throughput is more than 400Mbit/s.
2005, 27(12): 1952-1958.
Abstract:
This paper firstly addresses the joint space-time symbol block for the Vertical Bell labs LAyered Space-Time (V-BLAST) architecture under the frequency-selective fading environment. Successively, one novel Space-Time Rotational-Invariance Coding Technique (STRICT) is proposed for the V-BLAST architecture. By elegantly exploiting the above introduced rotational-invariance property, one blind estimation scheme of the Multiple-Input Multiple-Output (MIMO) frequency-selective wireless channels is derived for the V-BLAST architecture. Extensive simulation results demonstrate both the validity of the novel STRICT and the performance of the blind estimation scheme of frequency-selective channels.
This paper firstly addresses the joint space-time symbol block for the Vertical Bell labs LAyered Space-Time (V-BLAST) architecture under the frequency-selective fading environment. Successively, one novel Space-Time Rotational-Invariance Coding Technique (STRICT) is proposed for the V-BLAST architecture. By elegantly exploiting the above introduced rotational-invariance property, one blind estimation scheme of the Multiple-Input Multiple-Output (MIMO) frequency-selective wireless channels is derived for the V-BLAST architecture. Extensive simulation results demonstrate both the validity of the novel STRICT and the performance of the blind estimation scheme of frequency-selective channels.
2005, 27(12): 1959-1963.
Abstract:
A new method to perform classified vector quantization on wavelet images using directional tree structure vector combination is proposed. It makes vector combination by employing the direction character of subband coefficients and the correlation between and within subbands. It has two steps of classification with the vectors energy and activity and thus reduces the inner dispersion of the classified vectors. The classified information needs few bits to carry. The weighted mean square error rule using human visual characteristics is used to improve quantization gain. Simulation results show its coding efficiency for wavelet images.
A new method to perform classified vector quantization on wavelet images using directional tree structure vector combination is proposed. It makes vector combination by employing the direction character of subband coefficients and the correlation between and within subbands. It has two steps of classification with the vectors energy and activity and thus reduces the inner dispersion of the classified vectors. The classified information needs few bits to carry. The weighted mean square error rule using human visual characteristics is used to improve quantization gain. Simulation results show its coding efficiency for wavelet images.
2005, 27(12): 1964-1968.
Abstract:
Firstly, a method is introduced to estimate motion vectors between two pictures with energy flow information. Secondly, these motion vectors are applied to detect the scene change. Finally, from analyzing MPEG-4 Q2 rate-control algorithm with the situation of scene changes, an improved rate-control algorithm is proposed where the scene change is taken into account. In the improved algorithm, the target bit budget from MPEG-4 Q2 is modified when scene change occurs. Experimental results show that the proposed scheme can improve the picture quality at or after scene change without buffer overflow.
Firstly, a method is introduced to estimate motion vectors between two pictures with energy flow information. Secondly, these motion vectors are applied to detect the scene change. Finally, from analyzing MPEG-4 Q2 rate-control algorithm with the situation of scene changes, an improved rate-control algorithm is proposed where the scene change is taken into account. In the improved algorithm, the target bit budget from MPEG-4 Q2 is modified when scene change occurs. Experimental results show that the proposed scheme can improve the picture quality at or after scene change without buffer overflow.
2005, 27(12): 1969-1972.
Abstract:
A dynamic rate allocation method is presented which is based on the compression rate of image source coder, channel rate, channel characters and their influence on the distortion of progressive image. The best channel rate is selected according to the optimal rate allocation criterion between the source coder and channel coder, which ensures to achieve the minimal end-to-end distortion.
A dynamic rate allocation method is presented which is based on the compression rate of image source coder, channel rate, channel characters and their influence on the distortion of progressive image. The best channel rate is selected according to the optimal rate allocation criterion between the source coder and channel coder, which ensures to achieve the minimal end-to-end distortion.
2005, 27(12): 1973-1977.
Abstract:
A new Multiple Description Coding (MDC) scheme, X-tree based unequal protected MDC subband coding is proposed in this paper. The information of the wavelet transformed image is decomposed into two parts, the structure information and residues of significant coefficients. The structure information, including positions, signs and bit lengths of significant coefficients, is crucial and should be duplicated into both descriptions. The residues are mapped into couples of indices by a multiple description scalar quantizers, and sent to separate descriptions. Two descriptions are dispatched from different channels. Because every description includes all critical information of the picture, the reconstructed image from any single channel can have acceptable fidelity. The reconstructed image is of much better quality if both channels are available. Simulation results have verified the performance of the proposed algorithm.
A new Multiple Description Coding (MDC) scheme, X-tree based unequal protected MDC subband coding is proposed in this paper. The information of the wavelet transformed image is decomposed into two parts, the structure information and residues of significant coefficients. The structure information, including positions, signs and bit lengths of significant coefficients, is crucial and should be duplicated into both descriptions. The residues are mapped into couples of indices by a multiple description scalar quantizers, and sent to separate descriptions. Two descriptions are dispatched from different channels. Because every description includes all critical information of the picture, the reconstructed image from any single channel can have acceptable fidelity. The reconstructed image is of much better quality if both channels are available. Simulation results have verified the performance of the proposed algorithm.
2005, 27(12): 1978-1982.
Abstract:
Optical Burst Switching (OBS) is a promising solution for realizing IP/DWDM. This paper focuses on the one-way delayed reservation scheme. As a well-known scheme, JET (Just Enough Time) is described first. Then a new scheme called Just Little Time(JLT) is introduced in this paper. JLT is compatible with deflection routing and has no offset redundancy. To support service differentiation, offset time increments are adopted by JLT. JLT proves to be effective via computer simulations.
Optical Burst Switching (OBS) is a promising solution for realizing IP/DWDM. This paper focuses on the one-way delayed reservation scheme. As a well-known scheme, JET (Just Enough Time) is described first. Then a new scheme called Just Little Time(JLT) is introduced in this paper. JLT is compatible with deflection routing and has no offset redundancy. To support service differentiation, offset time increments are adopted by JLT. JLT proves to be effective via computer simulations.
2005, 27(12): 1983-1987.
Abstract:
In IEEE 802.11 WLAN, the average energy consumption in transmission per frame through DCF mechanism is analyzed by mathematical model. Further analysis shows there is an optimum RTS threshold that can minimize the average energy consumption per frame. An algorithm of RTS threshold adjustment is developed based on the relationship of average retransmission times and optimum RTS threshold. With this algorithm a station can adaptively adjust its RTS threshold according to network environment in order to reduce energy consumption in transmission. All theoretical analysis and algorithm are validated by computer simulation.
In IEEE 802.11 WLAN, the average energy consumption in transmission per frame through DCF mechanism is analyzed by mathematical model. Further analysis shows there is an optimum RTS threshold that can minimize the average energy consumption per frame. An algorithm of RTS threshold adjustment is developed based on the relationship of average retransmission times and optimum RTS threshold. With this algorithm a station can adaptively adjust its RTS threshold according to network environment in order to reduce energy consumption in transmission. All theoretical analysis and algorithm are validated by computer simulation.
2005, 27(12): 1988-1993.
Abstract:
Energy problem is very important in Ad hoc networks due to energy-constrained. In this paper, a traffic balanced route setup scheme, called TBDB, is presenred to improve energy efficiency. TBDB routing setup scheme decides whether to reply the route request by the connected flows of the node. Both of them have own threshold values and make routing decisions by the status of the node. The threshold values can be obtained by the normalized throughput values under saturated status. Analysis and simulation results show that both of them balance the energy consumption and the traffic of networks, improve the energy efficiency greatly, and decrease the average end to end delay.
Energy problem is very important in Ad hoc networks due to energy-constrained. In this paper, a traffic balanced route setup scheme, called TBDB, is presenred to improve energy efficiency. TBDB routing setup scheme decides whether to reply the route request by the connected flows of the node. Both of them have own threshold values and make routing decisions by the status of the node. The threshold values can be obtained by the normalized throughput values under saturated status. Analysis and simulation results show that both of them balance the energy consumption and the traffic of networks, improve the energy efficiency greatly, and decrease the average end to end delay.
2005, 27(12): 1994-1999.
Abstract:
In wireless sensor networks, the nodes with valued information are usually space-time varying. This paper presents a framework for spatio-temporal information integration based on directed diffusion and mobile agent. In the framework, the bi-direction gradients are constructed by the flood of the observers interest and the sensors Object Detected Signal (ODS). ODSs are collected and analyzed to program the visiting itineraries for mobile agents during a rhythm which is a period of time triggered by an ODS message, the space-time integration is completed by mobile agents with fusion algorithms accessing the nodes on the path. A rhythm acts as a label for spatial processing, and thus the series of rhythms become a time axis for temporal integration. In addition, the relations among some key parameters of framework are discussed. Finally, results based on experiments of collaborative target recognition demonstrate the effectiveness of the proposed framework.
In wireless sensor networks, the nodes with valued information are usually space-time varying. This paper presents a framework for spatio-temporal information integration based on directed diffusion and mobile agent. In the framework, the bi-direction gradients are constructed by the flood of the observers interest and the sensors Object Detected Signal (ODS). ODSs are collected and analyzed to program the visiting itineraries for mobile agents during a rhythm which is a period of time triggered by an ODS message, the space-time integration is completed by mobile agents with fusion algorithms accessing the nodes on the path. A rhythm acts as a label for spatial processing, and thus the series of rhythms become a time axis for temporal integration. In addition, the relations among some key parameters of framework are discussed. Finally, results based on experiments of collaborative target recognition demonstrate the effectiveness of the proposed framework.
2005, 27(12): 2000-2004.
Abstract:
A hybrid method by combining the methods of circuit and subcell FDTD is proposed. The coupling mechanism of the differential mode to common mode caused by a coax cable with a narrow gap around the circumference and by a symmetrical pair wire cable with insert of unbalanced electronic elements is analyzed. The frequency domain energy and the time domain waveform of the common mode electromagnetic leakage related to the above two instances are simulated by the proposed hybrid method.
A hybrid method by combining the methods of circuit and subcell FDTD is proposed. The coupling mechanism of the differential mode to common mode caused by a coax cable with a narrow gap around the circumference and by a symmetrical pair wire cable with insert of unbalanced electronic elements is analyzed. The frequency domain energy and the time domain waveform of the common mode electromagnetic leakage related to the above two instances are simulated by the proposed hybrid method.
2005, 27(12): 2005-2007.
Abstract:
The shielding effectiveness of a rectangular enclosure perforated with a slot is analyzed and the influences of the slot length on the magnitude and frequency of the lowest mode stimulated by the slot are given. Joint time-frequency analysis is also applied to explore the time domain waveform of every frequency component at observation point. The influence of the slot length to the time domain characteristics of different resonant mode is also obtained.
The shielding effectiveness of a rectangular enclosure perforated with a slot is analyzed and the influences of the slot length on the magnitude and frequency of the lowest mode stimulated by the slot are given. Joint time-frequency analysis is also applied to explore the time domain waveform of every frequency component at observation point. The influence of the slot length to the time domain characteristics of different resonant mode is also obtained.
2005, 27(12): 2008-2010.
Abstract:
In this paper, a novel compact Artificial Magnetic Conductor (AMC )structure is presented. For same unit size, this structure can provide lower frequency of phase reflection bandgap. So the large size problem of normal AMC structure can be solved effectively. Several practical circuits are manufactured, and the measured results are basically accordant to simulated results.
In this paper, a novel compact Artificial Magnetic Conductor (AMC )structure is presented. For same unit size, this structure can provide lower frequency of phase reflection bandgap. So the large size problem of normal AMC structure can be solved effectively. Several practical circuits are manufactured, and the measured results are basically accordant to simulated results.
