ISSN 
2011 Vol. 40, No. 5
2011, 40(5): 642-647.
doi: 10.3969/j.issn.1001-0548.2011.05.001
Abstract:
In this paper, the charge-controlled and flux-controlled memristor mathematical models are derived detailedly. The continuously variable conductance and memory properties of memristors are researched. An implementation scheme for analog memory using pulse controlled memristors is proposed, and its effectiveness is verified through theoretical analysis and simulation experiments. With crossbar array structure, the scheme is expected to achieve large-scale analog storage arrays, which may greatly promote the development of artificial neural networks and analog computers.
In this paper, the charge-controlled and flux-controlled memristor mathematical models are derived detailedly. The continuously variable conductance and memory properties of memristors are researched. An implementation scheme for analog memory using pulse controlled memristors is proposed, and its effectiveness is verified through theoretical analysis and simulation experiments. With crossbar array structure, the scheme is expected to achieve large-scale analog storage arrays, which may greatly promote the development of artificial neural networks and analog computers.
2011, 40(5): 648-651.
doi: 10.3969/j.issn.1001-0548.2011.05.002
Abstract:
In contrast to the memristor, the memcapacitor has advantage which produces losses during the reading and writing processes. The mathematic model of a memcapacitor is introduced and its Simulink model is built. The typical characteristics of the memcapacitor is simulated. At the same time, influences of input excitation and different parameters on the memcapacitor are considered and analyzed in details, and obtains a lot of the new characteristics of memcapacitor and important data.
In contrast to the memristor, the memcapacitor has advantage which produces losses during the reading and writing processes. The mathematic model of a memcapacitor is introduced and its Simulink model is built. The typical characteristics of the memcapacitor is simulated. At the same time, influences of input excitation and different parameters on the memcapacitor are considered and analyzed in details, and obtains a lot of the new characteristics of memcapacitor and important data.
2011, 40(5): 652-657.
doi: 10.3969/j.issn.1001-0548.2011.05.003
Abstract:
In this paper we propose a method to estimate the Pol-InSAR multi-interferometric phase based on the MUSIC method. In the method we construct the optimum weighted vector with the Wiener filter which takes advantage of the coherence of neighboring pixel pairs. The method employs the orthogonality of the joint subspace onto the corresponding joint noise subspace by Eigen-decomposition to construct the space spectral function. Therefore, it can accurately estimate the interferometric phase in the corresponding pixels of the multi-polarimetric channels. And it can adaptively coregister the SAR images. The effectiveness of the method is tested using real data.
In this paper we propose a method to estimate the Pol-InSAR multi-interferometric phase based on the MUSIC method. In the method we construct the optimum weighted vector with the Wiener filter which takes advantage of the coherence of neighboring pixel pairs. The method employs the orthogonality of the joint subspace onto the corresponding joint noise subspace by Eigen-decomposition to construct the space spectral function. Therefore, it can accurately estimate the interferometric phase in the corresponding pixels of the multi-polarimetric channels. And it can adaptively coregister the SAR images. The effectiveness of the method is tested using real data.
2011, 40(5): 658-661.
doi: 10.3969/j.issn.1001-0548.2011.05.004
Abstract:
With users increasing, location management strategy will be more important to the load of network signal and database access, and a good strategy would decrease the cost remarkably. According to the relativity of the users, the concept of cluster head, introduced and a polymerizing strategy in mobility management is proposed, The strategy decrease the cost of location updating while the configuration of the network and the cost of paging would not change palpably, and can be used with the exiting arithmetic together. This strategy is very suitable for the unit of cluster and the user terminal on the vehicles.
With users increasing, location management strategy will be more important to the load of network signal and database access, and a good strategy would decrease the cost remarkably. According to the relativity of the users, the concept of cluster head, introduced and a polymerizing strategy in mobility management is proposed, The strategy decrease the cost of location updating while the configuration of the network and the cost of paging would not change palpably, and can be used with the exiting arithmetic together. This strategy is very suitable for the unit of cluster and the user terminal on the vehicles.
2011, 40(5): 662-666.
doi: 10.3969/j.issn.1001-0548.2011.05.005
Abstract:
A low complexity block diagonalization precoding algorithm is proposed for multiuser multiple-input multiple-output (MIMO) downlink systems. It is proved that the algorithm can achieve the same sum capacity with that of the traditional block diagonalization one. The algorithm improves the existing zero forcing method. By performing Gram-Schmidt orthogonalization to zero forcing beams, the algorithm can achieve fast global block diagonalization of the equivalent downlink channel, thus further obtaining the precoders. Avoiding matrix singular value decomposition required when calculating null space in the traditional block diagonalization algorithm, the computational complexity of the proposed algorithm is greatly reduced by about 50%.
A low complexity block diagonalization precoding algorithm is proposed for multiuser multiple-input multiple-output (MIMO) downlink systems. It is proved that the algorithm can achieve the same sum capacity with that of the traditional block diagonalization one. The algorithm improves the existing zero forcing method. By performing Gram-Schmidt orthogonalization to zero forcing beams, the algorithm can achieve fast global block diagonalization of the equivalent downlink channel, thus further obtaining the precoders. Avoiding matrix singular value decomposition required when calculating null space in the traditional block diagonalization algorithm, the computational complexity of the proposed algorithm is greatly reduced by about 50%.
2011, 40(5): 667-670,675.
doi: 10.3969/j.issn.1001-0548.2011.05.006
Abstract:
An approximate expression of bit error rate (BER) is derived for a circular cell distributed antenna system with space-time block coding based on Alamouti's scheme and utilizing binary phase shift keying (BPSK) modulation. The analysis is carried out on considering the effects of path loss, log-normal shadowing, multipath fading and background noise. A simulation is carried out under the condition of two transmit and one received antennas, single-path Rayleigh fading channels, antenna spacing of 200 m, and standard deviation of shadowing of 8 dB. The simulation results show that, the numerical results match the simulation results well, and at the BER of 3×10-1, the proposed method is superior by about 1.4 dB to the traditional methods in bit signal-to-noise ratio.
An approximate expression of bit error rate (BER) is derived for a circular cell distributed antenna system with space-time block coding based on Alamouti's scheme and utilizing binary phase shift keying (BPSK) modulation. The analysis is carried out on considering the effects of path loss, log-normal shadowing, multipath fading and background noise. A simulation is carried out under the condition of two transmit and one received antennas, single-path Rayleigh fading channels, antenna spacing of 200 m, and standard deviation of shadowing of 8 dB. The simulation results show that, the numerical results match the simulation results well, and at the BER of 3×10-1, the proposed method is superior by about 1.4 dB to the traditional methods in bit signal-to-noise ratio.
2011, 40(5): 671-675.
doi: 10.3969/j.issn.1001-0548.2011.05.007
Abstract:
To eliminate effect brought from the noise in underwater OFDM system for sparse multi-path channel estimation, iterative least square adaptive channel estimation method based on threshold detection is proposed. According to least-square criterion, error squares are weighted and summed by introducing weighted factor and a iterative equation is derived to execute adaptive channel estimation. The computation complexity of iterative equation is low and it can not bring out big matrix calculation. Based on the solution of LS estimation, the most significant paths of channel are detected using predetermined threshold and the non-significant paths of time channel impulse response are set zero, reducing the effect of noise for channel estimation and increasing estimation precision. At the end, the effect of variant training symbol lengths for MSE performance is discussed, at the same time, the performance simulation of the proposed method is implemented on condition that the training symbol length, threshold, and so on are prescribed and the simulation result is analyzed.
To eliminate effect brought from the noise in underwater OFDM system for sparse multi-path channel estimation, iterative least square adaptive channel estimation method based on threshold detection is proposed. According to least-square criterion, error squares are weighted and summed by introducing weighted factor and a iterative equation is derived to execute adaptive channel estimation. The computation complexity of iterative equation is low and it can not bring out big matrix calculation. Based on the solution of LS estimation, the most significant paths of channel are detected using predetermined threshold and the non-significant paths of time channel impulse response are set zero, reducing the effect of noise for channel estimation and increasing estimation precision. At the end, the effect of variant training symbol lengths for MSE performance is discussed, at the same time, the performance simulation of the proposed method is implemented on condition that the training symbol length, threshold, and so on are prescribed and the simulation result is analyzed.
2011, 40(5): 676-681.
doi: 10.3969/j.issn.1001-0548.2011.05.008
Abstract:
This paper proves that the sequence of two memoryless nonlinear systems, predistorter and RF power amplifier, is commutative through theoretical derivation. For the disadvantages of frequently used predistortion structures, this paper proposes a new predistortion structure combining direct learning structure with indirect learning structure, which is simple and easy to implement. The RF power amplifier predistortion linearization method is extended to the situation with memory effect. Simulation results show the correctness of this predistortion linearization method. Its linearization performance is better than that using the direct inverse indirect learning structure.
This paper proves that the sequence of two memoryless nonlinear systems, predistorter and RF power amplifier, is commutative through theoretical derivation. For the disadvantages of frequently used predistortion structures, this paper proposes a new predistortion structure combining direct learning structure with indirect learning structure, which is simple and easy to implement. The RF power amplifier predistortion linearization method is extended to the situation with memory effect. Simulation results show the correctness of this predistortion linearization method. Its linearization performance is better than that using the direct inverse indirect learning structure.
2011, 40(5): 682-685,696.
doi: 10.3969/j.issn.1001-0548.2011.05.009
Abstract:
Equalization methods are unnecessary for differential modulation OFDM in slowly varying channel. When the channel varies drastically, the bit error rate (BER) will be aggravated. Due to no pilot in differential modulation OFDM, the equalization methods using pilot signal can not be used in differential modulation OFDM. A channel equalization method suitable for mobile TV/mobile multimedia broadcasting systems is proposed in the paper. Cepstral technique is employed in the method to attain the channel equalization. The simulation results indicate that this method has a favorable equalization effect.
Equalization methods are unnecessary for differential modulation OFDM in slowly varying channel. When the channel varies drastically, the bit error rate (BER) will be aggravated. Due to no pilot in differential modulation OFDM, the equalization methods using pilot signal can not be used in differential modulation OFDM. A channel equalization method suitable for mobile TV/mobile multimedia broadcasting systems is proposed in the paper. Cepstral technique is employed in the method to attain the channel equalization. The simulation results indicate that this method has a favorable equalization effect.
2011, 40(5): 686-690.
doi: 10.3969/j.issn.1001-0548.2011.05.010
Abstract:
A multi-scale fusion algorithm is proposed and applied in GPS/SINS integrated navigation system by combining the traditional analysis method of dynamic system based on model with the analysis method of signal multi-scale transformation based on statistical characteristics. This algorithm first establishes the dynamic equation and observation equation of system in original scale. The dynamic observation equations are then fused on different scales by wavelet transformation. At last the fused results on different scales are fused globally and optimally and are feedback to correct SINS. The experimental results based on practically measured data and theoretical dynamic simulation show that this method can fuse this system efficiently and optimally, and this method can have better precision than the several common filtering methods.
A multi-scale fusion algorithm is proposed and applied in GPS/SINS integrated navigation system by combining the traditional analysis method of dynamic system based on model with the analysis method of signal multi-scale transformation based on statistical characteristics. This algorithm first establishes the dynamic equation and observation equation of system in original scale. The dynamic observation equations are then fused on different scales by wavelet transformation. At last the fused results on different scales are fused globally and optimally and are feedback to correct SINS. The experimental results based on practically measured data and theoretical dynamic simulation show that this method can fuse this system efficiently and optimally, and this method can have better precision than the several common filtering methods.
2011, 40(5): 691-696.
doi: 10.3969/j.issn.1001-0548.2011.05.011
Abstract:
In order to compensate the Doppler frequency drift and chip period variation of the BPSK-modulated telemetry receiver, a new all-digital-receiver structure is proposed. Both the carrier tracking algorithm and the timing tracking algorithm are studied. The stability conditions of both loops are also addressed. Simulations are employed to prove the feasibility of the algorithms and the receiver structure. Simulations show that the loop can still get acquisition and keep tracking even with the condition of 23 kHz initial frequency offset, 20 g acceleration, π/2initial carrier offset, and 5/8 chip initial code offset.
In order to compensate the Doppler frequency drift and chip period variation of the BPSK-modulated telemetry receiver, a new all-digital-receiver structure is proposed. Both the carrier tracking algorithm and the timing tracking algorithm are studied. The stability conditions of both loops are also addressed. Simulations are employed to prove the feasibility of the algorithms and the receiver structure. Simulations show that the loop can still get acquisition and keep tracking even with the condition of 23 kHz initial frequency offset, 20 g acceleration, π/2initial carrier offset, and 5/8 chip initial code offset.
2011, 40(5): 697-702.
doi: 10.3969/j.issn.1001-0548.2011.05.012
Abstract:
A new time-frequency analysis theory is proposed based on recursive algorithm whose parameter is under control. The time-frequency analysis system has the merits of high speed and low storage with multi-path parallel recursive calculation instead of conventional sliding window FFT calculation. The center frequency or local frequency band can be rectified expediently. The recursive algorithm with controllable time resolution and frequency resolution has very strong go-aheadism and adjustability. It possesses the ability of real-time detection and accurate time-frequency parameter measure. The recursive algorithm can also cooperate with other effectual algorithms or systems.
A new time-frequency analysis theory is proposed based on recursive algorithm whose parameter is under control. The time-frequency analysis system has the merits of high speed and low storage with multi-path parallel recursive calculation instead of conventional sliding window FFT calculation. The center frequency or local frequency band can be rectified expediently. The recursive algorithm with controllable time resolution and frequency resolution has very strong go-aheadism and adjustability. It possesses the ability of real-time detection and accurate time-frequency parameter measure. The recursive algorithm can also cooperate with other effectual algorithms or systems.
2011, 40(5): 703-705,736.
doi: 10.3969/j.issn.1001-0548.2011.05.013
Abstract:
A novel tunable fiber ring laser configuration with a combination of Raman amplification and erbium-doped fiber amplification (EDFA) is proposed for realizing high signal-to-noise ratio (SNR), ultra-long distance (300 km) fiber Bragg grating (FBG) sensor systems. The hybrid Raman–EDF amplification configuration can enhance the optical SNR of FBG sensor signals significantly, so the optical power reflected by the fiber Bragg grating can be compensated. A good optical SNR of 15 dB is achieved for a 275 km transmission distance, which is the best performance to our knowledge, and about 4 dB at 300 km. In the static strain experiments with fiber lengths of 100,200,250,300 km, the linearity is greater than 0.999. This system can be widely used in the ultra-long-distance sensing applications such as railways, oil(gas) pipelines and coastline.
A novel tunable fiber ring laser configuration with a combination of Raman amplification and erbium-doped fiber amplification (EDFA) is proposed for realizing high signal-to-noise ratio (SNR), ultra-long distance (300 km) fiber Bragg grating (FBG) sensor systems. The hybrid Raman–EDF amplification configuration can enhance the optical SNR of FBG sensor signals significantly, so the optical power reflected by the fiber Bragg grating can be compensated. A good optical SNR of 15 dB is achieved for a 275 km transmission distance, which is the best performance to our knowledge, and about 4 dB at 300 km. In the static strain experiments with fiber lengths of 100,200,250,300 km, the linearity is greater than 0.999. This system can be widely used in the ultra-long-distance sensing applications such as railways, oil(gas) pipelines and coastline.
2011, 40(5): 706-710.
doi: 10.3969/j.issn.1001-0548.2011.05.014
Abstract:
Expanding application of IEEE 802.11 distributed coordination function (DCF) protocol to vehicle networks(VANETs) will greatly quicken the development of Vehicle networks. However, 802.11 DCF endures severe fairness problem in some scenarios, which would limit it's performance in vehicle networks. Most existing fairness solutions aim at long term fairness issue but not the short term fairness problem which is more popular in vehicle network. In this paper we discuss how the distance between two pairs commnicating vehicles affect the short term fairness . By simultaion we validate that the two-way road communication exhibite fairness problem only under two situations. Based on this result, a power adjusting scheme is proposed. The simulation results show that the fairness problem is solved by our power adjusting strategy.
Expanding application of IEEE 802.11 distributed coordination function (DCF) protocol to vehicle networks(VANETs) will greatly quicken the development of Vehicle networks. However, 802.11 DCF endures severe fairness problem in some scenarios, which would limit it's performance in vehicle networks. Most existing fairness solutions aim at long term fairness issue but not the short term fairness problem which is more popular in vehicle network. In this paper we discuss how the distance between two pairs commnicating vehicles affect the short term fairness . By simultaion we validate that the two-way road communication exhibite fairness problem only under two situations. Based on this result, a power adjusting scheme is proposed. The simulation results show that the fairness problem is solved by our power adjusting strategy.
2011, 40(5): 711-715.
doi: 10.3969/j.issn.1001-0548.2011.05.015
Abstract:
Two kinds of methods for implementing time reversal of electromagnetic signals in time domain based on digital signal processing and analog signal processing are introduced and discussed. The former technique can directly sample and process time domain signal, or use phase conjugation in frequency domain, to implementing time reversal of electromagnetic signals; while the other technique is based on the principle of temporal-imaging to implement time reversal of electromagnetic signals in time domain, including two schemes of microwave photonics technology and fully electronic technology.
Two kinds of methods for implementing time reversal of electromagnetic signals in time domain based on digital signal processing and analog signal processing are introduced and discussed. The former technique can directly sample and process time domain signal, or use phase conjugation in frequency domain, to implementing time reversal of electromagnetic signals; while the other technique is based on the principle of temporal-imaging to implement time reversal of electromagnetic signals in time domain, including two schemes of microwave photonics technology and fully electronic technology.
2011, 40(5): 716-719,782.
doi: 10.3969/j.issn.1001-0548.2011.05.016
Abstract:
A cylindrical resonant cavity working on TE11 mode for microwave plasma chemical vapor deposition (MPCVD) systems is designed on the basis of electromagnetic theory. The expression of the electric field distribution in the cylindrical cavity is derived and the geometrical size of the cylindrical cavity is calculated. The electric field distribution in the cylindrical cavity is simulated by using the electromagnetic software CST. The difference of electric field distribution from different coupling depth of antenna and thickness of quartz window is compared. Through the optimized simulation results, it is proved that the microwave power has a good coupling when the coupling depth of antenna and the thickness of quartz glass are both 5mm, and it can satisfy the requirement of industry. After practical processing, the simulation results shows good agreement the actual system's working condition. plasma chemical vapor deposition system, promote the development.
A cylindrical resonant cavity working on TE11 mode for microwave plasma chemical vapor deposition (MPCVD) systems is designed on the basis of electromagnetic theory. The expression of the electric field distribution in the cylindrical cavity is derived and the geometrical size of the cylindrical cavity is calculated. The electric field distribution in the cylindrical cavity is simulated by using the electromagnetic software CST. The difference of electric field distribution from different coupling depth of antenna and thickness of quartz window is compared. Through the optimized simulation results, it is proved that the microwave power has a good coupling when the coupling depth of antenna and the thickness of quartz glass are both 5mm, and it can satisfy the requirement of industry. After practical processing, the simulation results shows good agreement the actual system's working condition. plasma chemical vapor deposition system, promote the development.
2011, 40(5): 720-725.
doi: 10.3969/j.issn.1001-0548.2011.05.017
Abstract:
Resistance, reactance, and susceptance are estimated as independent variables in the conventional methods of parameter estimation. However, because they have a great difference in value, their estimation errors are inconsistent, especially the errors of small impedance are usually very large. Based on the length and the line parameters per unit length, a new line parameter estimation model is proposed. In this new model, state variables are multi-period voltage amplitude and phase angle at two ends of the line, and parameter variables are the parameters per unit length and the length. Because of introducing the length as the public variables of resistance, reactance and susceptance, the influence of line parameters on power flow is highlighted, so the consistency of line parameter estimation error can be guaranteed, and large estimation error of small impedance which appears in conventional models can be voided in the new model. Besides, the chaos quantum immune algorithm is presented to solve the parameter estimation model. It has the advantages of global optimality and stability. The validity of the proposed model and algorithm is verified by the simulation test.
Resistance, reactance, and susceptance are estimated as independent variables in the conventional methods of parameter estimation. However, because they have a great difference in value, their estimation errors are inconsistent, especially the errors of small impedance are usually very large. Based on the length and the line parameters per unit length, a new line parameter estimation model is proposed. In this new model, state variables are multi-period voltage amplitude and phase angle at two ends of the line, and parameter variables are the parameters per unit length and the length. Because of introducing the length as the public variables of resistance, reactance and susceptance, the influence of line parameters on power flow is highlighted, so the consistency of line parameter estimation error can be guaranteed, and large estimation error of small impedance which appears in conventional models can be voided in the new model. Besides, the chaos quantum immune algorithm is presented to solve the parameter estimation model. It has the advantages of global optimality and stability. The validity of the proposed model and algorithm is verified by the simulation test.
2011, 40(5): 726-731.
Abstract:
In this paper, the practical application of BDD (Binary Decision Diagram, BDD) technique in fault tree analysis is studied. Because there are some disadvantages that the fault tree analysis with traditional method could only get cut-sets of top event, and normal non-intersection strategy was too cumbersome, the principles and method of BDD technique are analyzed. On the basis of researching BDD structure of top-event with recursive technique, a key technique, i.e., inherit technique, is put forward and used to form non-intersection cut-sets. Finally, an example is given to interpret the reasons why the BDD technique is superior to method of traditional fault tree analysis.
In this paper, the practical application of BDD (Binary Decision Diagram, BDD) technique in fault tree analysis is studied. Because there are some disadvantages that the fault tree analysis with traditional method could only get cut-sets of top event, and normal non-intersection strategy was too cumbersome, the principles and method of BDD technique are analyzed. On the basis of researching BDD structure of top-event with recursive technique, a key technique, i.e., inherit technique, is put forward and used to form non-intersection cut-sets. Finally, an example is given to interpret the reasons why the BDD technique is superior to method of traditional fault tree analysis.
2011, 40(5): 732-736.
doi: 10.3969/j.issn.1001-0548.2011.05.019
Abstract:
In software testing based on Markov chain usage model, the sequence of state and stimulus from state”Start”to state”Exit” is a complete test case. Therefore, test input, stimulus, is very important to generate effective test case. Focusing on this, a method for selecting stimulus is proposed in the paper, called a random selection algorithm with probability constrained. This method uses the migrating probability between states of Markov chain usage model as constraints, selects stimulus by roulette selection operator, and then gets the next state. Roulette selection operator is used in genetic algorithm to select next generation of species. In this paper, it is used to select stimulus at every state. Compared with the previous selection method, random selection algorithm with probability constrained can improve the effectiveness of test cases.
In software testing based on Markov chain usage model, the sequence of state and stimulus from state”Start”to state”Exit” is a complete test case. Therefore, test input, stimulus, is very important to generate effective test case. Focusing on this, a method for selecting stimulus is proposed in the paper, called a random selection algorithm with probability constrained. This method uses the migrating probability between states of Markov chain usage model as constraints, selects stimulus by roulette selection operator, and then gets the next state. Roulette selection operator is used in genetic algorithm to select next generation of species. In this paper, it is used to select stimulus at every state. Compared with the previous selection method, random selection algorithm with probability constrained can improve the effectiveness of test cases.
2011, 40(5): 737-741.
doi: 10.3969/j.issn.1001-0548.2011.05.020
Abstract:
Based on the research of the reputation theory, a reputation rating model based on Dirichlet probability density function and “ad-sensitive” rating rule is proposed in e-commerce. The model takes discrete ratings of entity as input, and derives the continuous measures. “Bad-sensitive” rating rule makes the model sensitive and more cautious to the bad ratings and. The model is self-adaptive as the increasing of ratings. Experiments show that the model has several good characters for the reputation rating in e-commerce.
Based on the research of the reputation theory, a reputation rating model based on Dirichlet probability density function and “ad-sensitive” rating rule is proposed in e-commerce. The model takes discrete ratings of entity as input, and derives the continuous measures. “Bad-sensitive” rating rule makes the model sensitive and more cautious to the bad ratings and. The model is self-adaptive as the increasing of ratings. Experiments show that the model has several good characters for the reputation rating in e-commerce.
2011, 40(5): 742-746.
doi: 10.3969/j.issn.1001-0548.2011.05.021
Abstract:
To solve the problem of the loss of information in texture areas using traditional image denoising algorithms, we propose an algorithm for image denoising and enhancing based on 3DDCT according to the characteristic that the number of non-zero discrete Cosine transform (DCT) coefficients in smooth regions is fewer. First, similar blocks of the images is put to a block group according to l2 normal form; second, 2DDCT transformation is applied to each block and the threshold for the first denoising is used according to the correlation of pixels within the block; after that, 1DDCT transformation is applied on block groups according to the similarity between the corresponding pixels; then the threshold is used for a second time denoising; third, α power expansion is made to the non-zero coefficients in high frequency regions of 3D transform domain; finally, the proceed image is combined with Kaiser Window function. Compared with traditional algorithms, the new algorithm has a better visual performance because of its abilities to enlarge non-zero DCT coefficients in high frequency areas and to enhance information in texture and edge areas at the same time.
To solve the problem of the loss of information in texture areas using traditional image denoising algorithms, we propose an algorithm for image denoising and enhancing based on 3DDCT according to the characteristic that the number of non-zero discrete Cosine transform (DCT) coefficients in smooth regions is fewer. First, similar blocks of the images is put to a block group according to l2 normal form; second, 2DDCT transformation is applied to each block and the threshold for the first denoising is used according to the correlation of pixels within the block; after that, 1DDCT transformation is applied on block groups according to the similarity between the corresponding pixels; then the threshold is used for a second time denoising; third, α power expansion is made to the non-zero coefficients in high frequency regions of 3D transform domain; finally, the proceed image is combined with Kaiser Window function. Compared with traditional algorithms, the new algorithm has a better visual performance because of its abilities to enlarge non-zero DCT coefficients in high frequency areas and to enhance information in texture and edge areas at the same time.
2011, 40(5): 747-752.
doi: 10.3969/j.issn.1001-0548.2011.05.022
Abstract:
Layered multicast is a promising solution to address the problem of multicast congestion control in heterogeneity network. However, schemes using this solution suffer from slow response time and lack of fairness, and induce a lot of loss by slow response and failed join experiments. In this paper we propose a new layered multicast based on delay-jitter trend (LM-DJT). LM-DJT introduces the delay-jitter trend model into an amended TCP throughput equation to estimate the TCP-friendly transmission rate, and each receiver adjusts its subscription layers according to the estimated transmission rate. Our simulation results show LM-DJT converges fast to the optimal layer of subscription, induces less loss to track the available bandwidth, and has inter-session fairness and TCP-friendliness.
Layered multicast is a promising solution to address the problem of multicast congestion control in heterogeneity network. However, schemes using this solution suffer from slow response time and lack of fairness, and induce a lot of loss by slow response and failed join experiments. In this paper we propose a new layered multicast based on delay-jitter trend (LM-DJT). LM-DJT introduces the delay-jitter trend model into an amended TCP throughput equation to estimate the TCP-friendly transmission rate, and each receiver adjusts its subscription layers according to the estimated transmission rate. Our simulation results show LM-DJT converges fast to the optimal layer of subscription, induces less loss to track the available bandwidth, and has inter-session fairness and TCP-friendliness.
2011, 40(5): 753-758.
doi: 10.3969/j.issn.1001-0548.2011.05.023
Abstract:
Compared with propositional interval temporal logic (PITL), extended propositional interval temporal logic (EPITL) is equipped with infinite models and the chop-star operator additionally. However, there is no algorithm available for model checking EPITL. To this end, we propose an algorithm for EPITL satisfiability checking. The first step is to translate EPITL formulae with or without chop-star operators into their normal forms (NFs). The second step is to construct normal form graphs (NFGs) from the NF formulae. The last step is to check the satisfiability of the EPITL formulae by using the NFGs. Accordingly, we can translate the NFGs into buchi automata. So, the EPITL model checking problem is solved. As shown in the simulation results, our approach is superior to the existing ones based on other logics in terms of specification and verification of some properties of loop structures.
Compared with propositional interval temporal logic (PITL), extended propositional interval temporal logic (EPITL) is equipped with infinite models and the chop-star operator additionally. However, there is no algorithm available for model checking EPITL. To this end, we propose an algorithm for EPITL satisfiability checking. The first step is to translate EPITL formulae with or without chop-star operators into their normal forms (NFs). The second step is to construct normal form graphs (NFGs) from the NF formulae. The last step is to check the satisfiability of the EPITL formulae by using the NFGs. Accordingly, we can translate the NFGs into buchi automata. So, the EPITL model checking problem is solved. As shown in the simulation results, our approach is superior to the existing ones based on other logics in terms of specification and verification of some properties of loop structures.
2011, 40(5): 759-764.
doi: 10.3969/j.issn.1001-0548.2011.05.024
Abstract:
According to the principle of the image edge formation, the image edges consist of the triangle edge and the ramp edge. Based on orientation average, this paper proposes a new image edge detection algorithm which segments the neighborhood of the center pixel into two semicircles along different direction and then calculates the difference of the mean values of the two semicircles. With the directions of maximum difference and the minimum difference, an edge magnitude response function is designed to judge the edge type of the pixel, the triangle edge or the ramp edge. For inhibiting the effects of the noise, this method adopts Gauss-smooth pre-filter which inhibits the noise in images effectively. The edge-detection fitness function combining omission ratio is designed. By utilizing the fitness function, the algorithm analyzes the relationship of the size of the smoothing filter and the radius of the neighborhood of the center pixel. Experimental results show that the algorithm has good precision, and to a certain extent, inhibits the effects of noise on edge detection.
According to the principle of the image edge formation, the image edges consist of the triangle edge and the ramp edge. Based on orientation average, this paper proposes a new image edge detection algorithm which segments the neighborhood of the center pixel into two semicircles along different direction and then calculates the difference of the mean values of the two semicircles. With the directions of maximum difference and the minimum difference, an edge magnitude response function is designed to judge the edge type of the pixel, the triangle edge or the ramp edge. For inhibiting the effects of the noise, this method adopts Gauss-smooth pre-filter which inhibits the noise in images effectively. The edge-detection fitness function combining omission ratio is designed. By utilizing the fitness function, the algorithm analyzes the relationship of the size of the smoothing filter and the radius of the neighborhood of the center pixel. Experimental results show that the algorithm has good precision, and to a certain extent, inhibits the effects of noise on edge detection.
2011, 40(5): 765-771.
doi: 10.3969/j.issn.1001-0548.2011.05.025
Abstract:
RNA secondary structure prediction is an important problem in the research field of bioinformatics. Recently, researchers applied metaheuristics to predict RNA secondary structure. In this article, a new predicting method called tabu genetic algorithm based RNA secondary structure prediction (TGARNA) is developed. In the TGARNA algorithm, an improved method for testing the compatibility of stems is given to improve the performance of the population. In addition, tabu search is integrated into genetic operations to prevent inbreeding and maintain a high level of population diversity. Computer simulations show that the proposed approach is effective for predicting RNA secondary structure.
RNA secondary structure prediction is an important problem in the research field of bioinformatics. Recently, researchers applied metaheuristics to predict RNA secondary structure. In this article, a new predicting method called tabu genetic algorithm based RNA secondary structure prediction (TGARNA) is developed. In the TGARNA algorithm, an improved method for testing the compatibility of stems is given to improve the performance of the population. In addition, tabu search is integrated into genetic operations to prevent inbreeding and maintain a high level of population diversity. Computer simulations show that the proposed approach is effective for predicting RNA secondary structure.
2011, 40(5): 772-776.
doi: 10.3969/j.issn.1001-0548.2011.05.026
Abstract:
An image enhancement algorithm based on 0~1 order Riemann-Liouville fractional differential is presented in this paper. The Riemann-Liouville differential equation and its discretization form are deduced from the Riemann-Liouville definition. According to the discretization equation, the structures and parameters of eight fractional differential masks are constructed respectively. The numerical implementation algorithms of the eight differential masks are discussed too. Finally, the relationships between the entropies of enhanced images with the orders are discussed, then, the most optimal order is obtained. The computer experiments show that the algorithm has excellent feedback for nonlinearly enhancing the textural details of the digital image and it can obviously enhance texture details and edges, the enhanced images have markedly visual effect enhance capabilities of the Gaussian smoothed images are also obvious too.
An image enhancement algorithm based on 0~1 order Riemann-Liouville fractional differential is presented in this paper. The Riemann-Liouville differential equation and its discretization form are deduced from the Riemann-Liouville definition. According to the discretization equation, the structures and parameters of eight fractional differential masks are constructed respectively. The numerical implementation algorithms of the eight differential masks are discussed too. Finally, the relationships between the entropies of enhanced images with the orders are discussed, then, the most optimal order is obtained. The computer experiments show that the algorithm has excellent feedback for nonlinearly enhancing the textural details of the digital image and it can obviously enhance texture details and edges, the enhanced images have markedly visual effect enhance capabilities of the Gaussian smoothed images are also obvious too.
2011, 40(5): 777-782.
doi: 10.3969/j.issn.1001-0548.2011.05.027
Abstract:
Energy limitation is one of main constraints to depress the network life time. However, network effective working hours can be extended by transforming the natural energy into the electric energy. Based on the analysis of characteristics of dry batteries and rechargeable batteries, by using combined power supply and energy management fuzzy control strategy, rechargeable sensor nodes suitable for low energy environment and the corresponding network platform are designed. The indoor and outdoor experiment validates that this design has a certain practical significance to solve the problem of energy limitation of wireless sensor network node.
Energy limitation is one of main constraints to depress the network life time. However, network effective working hours can be extended by transforming the natural energy into the electric energy. Based on the analysis of characteristics of dry batteries and rechargeable batteries, by using combined power supply and energy management fuzzy control strategy, rechargeable sensor nodes suitable for low energy environment and the corresponding network platform are designed. The indoor and outdoor experiment validates that this design has a certain practical significance to solve the problem of energy limitation of wireless sensor network node.
2011, 40(5): 783-786.
doi: 10.3969/j.issn.1001-0548.2011.05.028
Abstract:
For the bit-search generator, a fast probabilistic key recovery attack based on multi segments of keystream bites is presented using the idea of Martin Hell's attack on the self-shrinking generator. Compared with the best known attack, the attack complexity can be significantly reduced from O(20.5LL3) to O(20.43LL3) if we have O(NL) of keystream bits. Here L is the length of the linear feedback shift register (LFSR); N is the number of the segments of keystream bits. The experimental results show that: the complexity of this algorithm can be significantly degraded as the number of attacks increases; The longer the length of the key is, the more efficient our attack is.
For the bit-search generator, a fast probabilistic key recovery attack based on multi segments of keystream bites is presented using the idea of Martin Hell's attack on the self-shrinking generator. Compared with the best known attack, the attack complexity can be significantly reduced from O(20.5LL3) to O(20.43LL3) if we have O(NL) of keystream bits. Here L is the length of the linear feedback shift register (LFSR); N is the number of the segments of keystream bits. The experimental results show that: the complexity of this algorithm can be significantly degraded as the number of attacks increases; The longer the length of the key is, the more efficient our attack is.
2011, 40(5): 787-790.
doi: 10.3969/j.issn.1001-0548.2011.05.029
Abstract:
Based on an application of the digital image watermarking of the wavelet and chaotic theory, an watermarking method is proposed to resolve copyright deadlock. By using Chebyshev and Henon chaose system with non-blind watermarking, Keys K1 and K2 are obtained, where K1 correlates with the initial value of chaose system, and K2 with the initial image. Experiments indicate that the proposed algorithm is effective and superior to the traditional algorithms.
Based on an application of the digital image watermarking of the wavelet and chaotic theory, an watermarking method is proposed to resolve copyright deadlock. By using Chebyshev and Henon chaose system with non-blind watermarking, Keys K1 and K2 are obtained, where K1 correlates with the initial value of chaose system, and K2 with the initial image. Experiments indicate that the proposed algorithm is effective and superior to the traditional algorithms.
2011, 40(5): 791-795.
doi: 10.3969/j.issn.1001-0548.2011.05.030
Abstract:
According to preventative maintenance scheduling for Multi-products and Semi-flexible Parallel Production Line (MSPPL) in semiconductor chipset assembly and test factories, the preventive maintenance scheduling model for MSPPL is proposed with the maximal production time as the objective function and under four constraints semi-flexible limits, multi-product production time requirements, preventive maintenance time windows, and the amount of preventive maintenance worker group. The proposed model has been applied in the multi-products and semi-flexible parallel production line of a chipset assembly and test factory by using the software named lingo (version is 9.0). The scheduling results have been successfully applied the actual production, which validates the feasibility and accuracy of the proposed model.
According to preventative maintenance scheduling for Multi-products and Semi-flexible Parallel Production Line (MSPPL) in semiconductor chipset assembly and test factories, the preventive maintenance scheduling model for MSPPL is proposed with the maximal production time as the objective function and under four constraints semi-flexible limits, multi-product production time requirements, preventive maintenance time windows, and the amount of preventive maintenance worker group. The proposed model has been applied in the multi-products and semi-flexible parallel production line of a chipset assembly and test factory by using the software named lingo (version is 9.0). The scheduling results have been successfully applied the actual production, which validates the feasibility and accuracy of the proposed model.
2011, 40(5): 796-799.
doi: 10.3969/j.issn.1001-0548.2011.05.031
Abstract:
By using method of condensation of degree of freedom, a condensation method of degree of freedom for parts and components is proposed, and base on this method, a new support position layout optimization method in printed circuit board structure is built up. This optimization method makes computation amount reduce greatly and reuse the condensation model easily. Additionally, by using genetic algorithm method and second- develop technique, the solving software is developed. Optimization examples show the optimization method is feasible and effective for engineering projects.
By using method of condensation of degree of freedom, a condensation method of degree of freedom for parts and components is proposed, and base on this method, a new support position layout optimization method in printed circuit board structure is built up. This optimization method makes computation amount reduce greatly and reuse the condensation model easily. Additionally, by using genetic algorithm method and second- develop technique, the solving software is developed. Optimization examples show the optimization method is feasible and effective for engineering projects.
