ISSN 
2012 Vol. 41, No. 4
2012, 41(4): 482-490.
doi: 10.3969/j.issn.1001-0548.2012.04.001
Abstract:
In order to describe top-level model in different development stages, tools and departments for the development of complex system more accurately, a novel openended top-level modeling method for complex system is proposed. Based on the facility of Meta modeling framework, SysML is profiled by basic stereotype and Simulink stereotype. In top-level modeling, the complex system is divided into static structure model, dynamic behavior model and the interaction between them. The formal definition of each abstract model is discussed and the integration of various structure models is realized. Take a flight control system of unmanned aerial vehicle as an example, the system is modeled uniformly based on top-level model and the higher-level abstraction of those isomerous models in complex system is implemented. The experimental results validate the effectiveness of the proposed modeling method.
In order to describe top-level model in different development stages, tools and departments for the development of complex system more accurately, a novel openended top-level modeling method for complex system is proposed. Based on the facility of Meta modeling framework, SysML is profiled by basic stereotype and Simulink stereotype. In top-level modeling, the complex system is divided into static structure model, dynamic behavior model and the interaction between them. The formal definition of each abstract model is discussed and the integration of various structure models is realized. Take a flight control system of unmanned aerial vehicle as an example, the system is modeled uniformly based on top-level model and the higher-level abstraction of those isomerous models in complex system is implemented. The experimental results validate the effectiveness of the proposed modeling method.
2012, 41(4): 491-495.
doi: 10.3969/j.issn.1001-0548.2012.04.002
Abstract:
A high-capacity reversible data hiding algorithm based on neighboring pixels is proposed in this paper. Cover image is first converted into one dimensional (1D) sequence by different scan patterns. The difference values between each two neighbor elements in the 1D sequence are calculated and the two difference values with biggest frequencies are distinguished. For each scan pattern, the occurrence number of the two difference values is achieved. The scan pattern with the biggest occurrence number is used for data hiding, where the two difference values with biggest frequencies are exploited to embed secret messages. Experimental results show that the proposed algorithm has large embedding capacity and high PSNR value.
A high-capacity reversible data hiding algorithm based on neighboring pixels is proposed in this paper. Cover image is first converted into one dimensional (1D) sequence by different scan patterns. The difference values between each two neighbor elements in the 1D sequence are calculated and the two difference values with biggest frequencies are distinguished. For each scan pattern, the occurrence number of the two difference values is achieved. The scan pattern with the biggest occurrence number is used for data hiding, where the two difference values with biggest frequencies are exploited to embed secret messages. Experimental results show that the proposed algorithm has large embedding capacity and high PSNR value.
2012, 41(4): 496-500.
doi: 10.3969/j.issn.1001-0548.2012.04.003
Abstract:
In view of the error-correcting performance deterioration of Turbo codes due to the synchronization loss at low SNR environment, a code aided synchronization algorithm named maximum-mean likelihood ratio (MMLR) based on the log-likelihood ratio is proposed by combining with Turbo iterative mechanism. Firstly, improved data aided (DA) method is adopted to ensure the timing error less than one symbol period. And then error information is fed back according to the distribution of likelihood ratio. The iterative phase estimation is carried out. Since the decoder has the error correcting function, the synchronization accuracy of the algorithm is effectively improved. Turbo-minimum shift keying(MSK) simulation model is established. Simulation results show that the algorithm can accurately complete the timing and phase estimates and achieve the reliability close to that of ideal synchronization at very low SNR.
In view of the error-correcting performance deterioration of Turbo codes due to the synchronization loss at low SNR environment, a code aided synchronization algorithm named maximum-mean likelihood ratio (MMLR) based on the log-likelihood ratio is proposed by combining with Turbo iterative mechanism. Firstly, improved data aided (DA) method is adopted to ensure the timing error less than one symbol period. And then error information is fed back according to the distribution of likelihood ratio. The iterative phase estimation is carried out. Since the decoder has the error correcting function, the synchronization accuracy of the algorithm is effectively improved. Turbo-minimum shift keying(MSK) simulation model is established. Simulation results show that the algorithm can accurately complete the timing and phase estimates and achieve the reliability close to that of ideal synchronization at very low SNR.
2012, 41(4): 501-506.
doi: 10.3969/j.issn.1001-0548.2012.04.004
Abstract:
Formation-flying satellite radar is a new technique developed recently. It offers the potential for diversity gain and spatial resolution gain through transmitting the orthogonal waveforms. Combining the performance of LFM signal with the orthogonal code division technology, OCD-LFM (orthogonal code division linear frequency modulation) signals is proposed. Then, the cross-ambiguity and the range resolution on the performance of the designed signals are analyzed. Also, the relationship between the parameters that minimize the cross-correlation peaks and minimize the effect of Doppler frequency shift of the proposed signals is derived. Theoretical analysis and computer simulation results illustrate that the orthogonal performance of OCD-LFM signals gradually enhanced with the increase of phase code length N, while the proposed signal has better performance than the traditional hybrid waveform obtained by combining chirp waveform with binary pseudo-random sequences in range resolution and Doppler tolerance.
Formation-flying satellite radar is a new technique developed recently. It offers the potential for diversity gain and spatial resolution gain through transmitting the orthogonal waveforms. Combining the performance of LFM signal with the orthogonal code division technology, OCD-LFM (orthogonal code division linear frequency modulation) signals is proposed. Then, the cross-ambiguity and the range resolution on the performance of the designed signals are analyzed. Also, the relationship between the parameters that minimize the cross-correlation peaks and minimize the effect of Doppler frequency shift of the proposed signals is derived. Theoretical analysis and computer simulation results illustrate that the orthogonal performance of OCD-LFM signals gradually enhanced with the increase of phase code length N, while the proposed signal has better performance than the traditional hybrid waveform obtained by combining chirp waveform with binary pseudo-random sequences in range resolution and Doppler tolerance.
2012, 41(4): 507-511.
doi: 10.3969/j.issn.1001-0548.2012.04.005
Abstract:
In multiple input multiple output (MIMO) downlink systems, if all users send their channel state information (CSI) to the base station, the base station can schedule users whose channels are good and send them information to obtain high system throughout. However, when the number of users in the systems grows quickly, large quantity of feedback information will lead the overflow of the feedback channel. In this paper, we propose a limited feedback strategy based on user rank. In this strategy, only those users whose signal interference and noise ratio (SINR) above a predetermined threshold will send their channel direction information (CDI) and their user ranks to the base station and other users will send nothing to the base station, resulting in the greatly reduced feedback load. Theoretical analysis and computer simulation show the feedback load can be greatly reduced by this method and MIMO downlink systems can achieve multiplexing and multiuser diversity gain at the same time.
In multiple input multiple output (MIMO) downlink systems, if all users send their channel state information (CSI) to the base station, the base station can schedule users whose channels are good and send them information to obtain high system throughout. However, when the number of users in the systems grows quickly, large quantity of feedback information will lead the overflow of the feedback channel. In this paper, we propose a limited feedback strategy based on user rank. In this strategy, only those users whose signal interference and noise ratio (SINR) above a predetermined threshold will send their channel direction information (CDI) and their user ranks to the base station and other users will send nothing to the base station, resulting in the greatly reduced feedback load. Theoretical analysis and computer simulation show the feedback load can be greatly reduced by this method and MIMO downlink systems can achieve multiplexing and multiuser diversity gain at the same time.
2012, 41(4): 512-515.
doi: 10.3969/j.issn.1001-0548.2012.04.006
Abstract:
Aiming at the problem of blind source separation (BSS) in time varying channel, two real time BSS algorithms are presented:equivariant adaptive source separation via independence (EASI) BSS algorithm based on optimal selective function (EASI-function) and BSS based on optimal selective function algorithm with variable step-size based on kurtosis (EASI-function-KVS). EASI-function algorithm adopts the different estimate function in different stage to get the balance between divergence speed and steady-state performance. And the EASI-function-KVS algorithm changes the step-size adaptively based on kurtosis thought so as to improve the performance of algorithm. Simulation results show that the algorithms in the paper can trace the channel changes effectively and the performance is superior to that of conventional EASI algorithm.
Aiming at the problem of blind source separation (BSS) in time varying channel, two real time BSS algorithms are presented:equivariant adaptive source separation via independence (EASI) BSS algorithm based on optimal selective function (EASI-function) and BSS based on optimal selective function algorithm with variable step-size based on kurtosis (EASI-function-KVS). EASI-function algorithm adopts the different estimate function in different stage to get the balance between divergence speed and steady-state performance. And the EASI-function-KVS algorithm changes the step-size adaptively based on kurtosis thought so as to improve the performance of algorithm. Simulation results show that the algorithms in the paper can trace the channel changes effectively and the performance is superior to that of conventional EASI algorithm.
2012, 41(4): 516-521.
doi: 10.3969/j.issn.1001-0548.2012.04.007
Abstract:
This paper describes a new technique to estimate the direction of arrival (DOA) of coherent signals using a uniform circular array. Such an array may be transformed into a virtual uniform linear array in mode space. By exploiting the property of the virtual uniform linear array, a difference matrix can be constructed, whose rank is only related to the directions of arrival of correlated signals. This method can resolve the uncorrelated sources and coherent sources separately. In this way a conventional algorithm can estimate the DOA of uncorrelated sources, while the proposed algorithm can estimate the DOA of correlated and coherent sources. Thus the output data of the array are used repeatedly, and more sources can be estimated with fewer sensors. The effectiveness of the method is illustrated through a number of numerical examples.
This paper describes a new technique to estimate the direction of arrival (DOA) of coherent signals using a uniform circular array. Such an array may be transformed into a virtual uniform linear array in mode space. By exploiting the property of the virtual uniform linear array, a difference matrix can be constructed, whose rank is only related to the directions of arrival of correlated signals. This method can resolve the uncorrelated sources and coherent sources separately. In this way a conventional algorithm can estimate the DOA of uncorrelated sources, while the proposed algorithm can estimate the DOA of correlated and coherent sources. Thus the output data of the array are used repeatedly, and more sources can be estimated with fewer sensors. The effectiveness of the method is illustrated through a number of numerical examples.
2012, 41(4): 522-526.
doi: 10.3969/j.issn.1001-0548.2012.04.008
Abstract:
Traditional ranging methods are to create an one-to-one mapping between received signal strength indicator (RSSI) and distance in wireless sensor networks. In this paper, a ranging method based on one-to-many mapping between RSSI and distance scope is proposed. At off-line stage, a database of the mapping between RSSI and distance scope is created; at on-line stage, by using RSSI values to query the database, some distance scopes are obtained and weighted to generate a new distance scope. At last, the distance between the transmitter and the receiver can be attained through the center of the distance scope. Simulation results show that the scheme provides high ranging precision.
Traditional ranging methods are to create an one-to-one mapping between received signal strength indicator (RSSI) and distance in wireless sensor networks. In this paper, a ranging method based on one-to-many mapping between RSSI and distance scope is proposed. At off-line stage, a database of the mapping between RSSI and distance scope is created; at on-line stage, by using RSSI values to query the database, some distance scopes are obtained and weighted to generate a new distance scope. At last, the distance between the transmitter and the receiver can be attained through the center of the distance scope. Simulation results show that the scheme provides high ranging precision.
2012, 41(4): 527-531.
doi: 10.3969/j.issn.1001-0548.2012.04.009
Abstract:
Expectation-maximization (EM) algorithm is applied in the noisy independent component analysis (ICA) model, i.e., the source signals are assumed statistical independent and formulated in a Bayesian estimation framework. A Bayesian approach with EM algorithm for noisy ICA is proposed. In the noisy ICA model, supposing the means and variances of source signals are uniform, the proposed EM algorithm can efficiently estimate the model parameters of the mixing matrix and hyperparameters under a certain model, and then estimate the sources by processing the mixing matrix and hyperparameters alternatively. Simulation results show that the proposed method can perform blind source separation (BSS) with the noisy ICA model.
Expectation-maximization (EM) algorithm is applied in the noisy independent component analysis (ICA) model, i.e., the source signals are assumed statistical independent and formulated in a Bayesian estimation framework. A Bayesian approach with EM algorithm for noisy ICA is proposed. In the noisy ICA model, supposing the means and variances of source signals are uniform, the proposed EM algorithm can efficiently estimate the model parameters of the mixing matrix and hyperparameters under a certain model, and then estimate the sources by processing the mixing matrix and hyperparameters alternatively. Simulation results show that the proposed method can perform blind source separation (BSS) with the noisy ICA model.
2012, 41(4): 532-536.
doi: 10.3969/j.issn.1001-0548.2012.04.010
Abstract:
This paper designs an improved echo canceller for on-channel repeater in the digital terrestrial television broadcasting (DTTB) networks. The finite impulse response (FIR) filter of the conventional echo canceller is split into several sub-filters and the output error power for the different sub-filters is estimated. Based on comparison of the output error power of the different sub-filters, the improved echo canceller adaptively selects the number of sub-filters or the tap length for the echo canceller. The improved echo canceller overcomes the fault of unknown knowledge of the tap length for the echo canceller design. Simulations illustrate that the improved echo canceller can attain the lower residual echo interference compared with the conventional echo canceller.
This paper designs an improved echo canceller for on-channel repeater in the digital terrestrial television broadcasting (DTTB) networks. The finite impulse response (FIR) filter of the conventional echo canceller is split into several sub-filters and the output error power for the different sub-filters is estimated. Based on comparison of the output error power of the different sub-filters, the improved echo canceller adaptively selects the number of sub-filters or the tap length for the echo canceller. The improved echo canceller overcomes the fault of unknown knowledge of the tap length for the echo canceller design. Simulations illustrate that the improved echo canceller can attain the lower residual echo interference compared with the conventional echo canceller.
2012, 41(4): 537-540.
doi: 10.3969/j.issn.1001-0548.2012.04.011
Abstract:
Inspired by the multiple signal delay channel sampling technique, we propose an analog signal sampling model based on compressed sensing, and construct the measurement matrix in the context of the sampling architecture. The proposed sampling model can reconstruct the signal from a small number of samples captured at the sub-Nyquist rate. The examples of experiments are given to evaluate the performance of the proposed model.
Inspired by the multiple signal delay channel sampling technique, we propose an analog signal sampling model based on compressed sensing, and construct the measurement matrix in the context of the sampling architecture. The proposed sampling model can reconstruct the signal from a small number of samples captured at the sub-Nyquist rate. The examples of experiments are given to evaluate the performance of the proposed model.
2012, 41(4): 541-544.
doi: 10.3969/j.issn.1001-0548.2012.04.012
Abstract:
A surveillance scene modeling algorithm is proposed by tracklet analysis. A number of tracklets belonging to the same object are found through a bidirectional spatio-temporal continuity tracklet association method. The entry, exit, main path, and scene occluder of a scene model are obtained by analyzing the reason that object's track fall into tracklets. Experiments prove that the scene model can improve tracking result and detect abnormal object tracks.
A surveillance scene modeling algorithm is proposed by tracklet analysis. A number of tracklets belonging to the same object are found through a bidirectional spatio-temporal continuity tracklet association method. The entry, exit, main path, and scene occluder of a scene model are obtained by analyzing the reason that object's track fall into tracklets. Experiments prove that the scene model can improve tracking result and detect abnormal object tracks.
2012, 41(4): 545-551.
doi: 10.3969/j.issn.1001-0548.2012.04.013
Abstract:
The effectiveness, error formula, algorithm flow, and weak classifiers training of Real AdaBoost algorithm are analyzed and proved by a new technique. Real AdaBoost algorithm is improved by weighted combination of weak classifiers and the approximately best combination coefficients are obtained. It is proved that the function of sample weight adjusting method and weak classifiers training method is to guarantee the independence of weak classifiers. Multi-class Real AdaBoost algorithm is proposed based on Bayes statistics deduction. The formula of algorithm and the estimation of classification error are discussed. The training method of weak classifiers is simplified. The estimation of classification error of Gentle AdaBoost is obtained. The effectiveness of the proposed algorithms is verified by the experiment on UCI dataset.
The effectiveness, error formula, algorithm flow, and weak classifiers training of Real AdaBoost algorithm are analyzed and proved by a new technique. Real AdaBoost algorithm is improved by weighted combination of weak classifiers and the approximately best combination coefficients are obtained. It is proved that the function of sample weight adjusting method and weak classifiers training method is to guarantee the independence of weak classifiers. Multi-class Real AdaBoost algorithm is proposed based on Bayes statistics deduction. The formula of algorithm and the estimation of classification error are discussed. The training method of weak classifiers is simplified. The estimation of classification error of Gentle AdaBoost is obtained. The effectiveness of the proposed algorithms is verified by the experiment on UCI dataset.
2012, 41(4): 552-556.
doi: 10.3969/j.issn.1001-0548.2012.04.014
Abstract:
In attribute-based cryptosystem, many attributes of a user were monitored by a single authority, which would inevitably increase its workload and reduce its efficiency. In this paper, a multi-authority signature scheme without a central authority is proposed. In this scheme, many attributes of a user are monitored by many different authorities respectively, in stead of a trusted central authority. The scheme increases the system's applicability. The security of this scheme is proved equal to computational Diffie-Hellman (CDH) problem. So the scheme has two characteristics of existential unforgeability and security preventing collusion attack.
In attribute-based cryptosystem, many attributes of a user were monitored by a single authority, which would inevitably increase its workload and reduce its efficiency. In this paper, a multi-authority signature scheme without a central authority is proposed. In this scheme, many attributes of a user are monitored by many different authorities respectively, in stead of a trusted central authority. The scheme increases the system's applicability. The security of this scheme is proved equal to computational Diffie-Hellman (CDH) problem. So the scheme has two characteristics of existential unforgeability and security preventing collusion attack.
2012, 41(4): 557-560.
doi: 10.3969/j.issn.1001-0548.2012.04.015
Abstract:
This paper describes a new space partition method, which is used in the construction of three-dimensional digital earth simulation system for flight simulation. Through comparing the two space division methods, the same interval and the same area, the space partition method with double longitude span is proposed based on the method of the same interval space partition. The proposed method retains the advantages of the same interval space partition method while significantly reducing data redundancy, and can overcome the problem of the incomplete coverage in visual range.
This paper describes a new space partition method, which is used in the construction of three-dimensional digital earth simulation system for flight simulation. Through comparing the two space division methods, the same interval and the same area, the space partition method with double longitude span is proposed based on the method of the same interval space partition. The proposed method retains the advantages of the same interval space partition method while significantly reducing data redundancy, and can overcome the problem of the incomplete coverage in visual range.
2012, 41(4): 561-563,591.
doi: 10.3969/j.issn.1001-0548.2012.04.016
Abstract:
A general scheme of time series data in the food supply chain is proposed. By using functional cluster analysis, the time series data are treated as a complete object of a time function, rather than a simple arrangement of individual observations. In this scheme, the discrete data are transformed into functional data while the distance of the origin function is replaced with the distance of the expansion coefficients' vector of the base function. In this way, the system can reduce the large number of numerical integration and simplify the calculation. Experiments indicate that the availability of the traceability data is enhanced significantly after discrete data are clustered into sequential information.
A general scheme of time series data in the food supply chain is proposed. By using functional cluster analysis, the time series data are treated as a complete object of a time function, rather than a simple arrangement of individual observations. In this scheme, the discrete data are transformed into functional data while the distance of the origin function is replaced with the distance of the expansion coefficients' vector of the base function. In this way, the system can reduce the large number of numerical integration and simplify the calculation. Experiments indicate that the availability of the traceability data is enhanced significantly after discrete data are clustered into sequential information.
2012, 41(4): 564-567.
Abstract:
A new denoising diffusion model is proposed for fluorescence microscopic images, in which fourth-order partial differential equations (PDEs) and contrast enhancement are utilized to overcome the blocky effect and false edges usually caused by second-order PDEs. Compared with second-order PDEs model, the proposed model shows superior performance in terms of both objective criteria and subjective human vision via processing simulated and experimental noisy images.
A new denoising diffusion model is proposed for fluorescence microscopic images, in which fourth-order partial differential equations (PDEs) and contrast enhancement are utilized to overcome the blocky effect and false edges usually caused by second-order PDEs. Compared with second-order PDEs model, the proposed model shows superior performance in terms of both objective criteria and subjective human vision via processing simulated and experimental noisy images.
2012, 41(4): 568-573.
doi: 10.3969/j.issn.1001-0548.2012.04.018
Abstract:
In order to reduce energy consumption of wireless sensor networks, a minimum energy consumption topology control method based on artificial immune response is proposed. The basic principle of topology control in wireless sensor networks is analyzed. An artificial immune response model used to the minimum energy consumption topology control is established. After that the minimum energy consumption topology control is achieved by using the parallel search ability of artificial immune response, and its convergence is also proved. The energy consumption performance of topology control in wireless sensor networks is improved. Compared with genetic algorithm, the simulation results show that the method can obtain better performance in terms of energy consumption transmission efficiency and convergence.
In order to reduce energy consumption of wireless sensor networks, a minimum energy consumption topology control method based on artificial immune response is proposed. The basic principle of topology control in wireless sensor networks is analyzed. An artificial immune response model used to the minimum energy consumption topology control is established. After that the minimum energy consumption topology control is achieved by using the parallel search ability of artificial immune response, and its convergence is also proved. The energy consumption performance of topology control in wireless sensor networks is improved. Compared with genetic algorithm, the simulation results show that the method can obtain better performance in terms of energy consumption transmission efficiency and convergence.
2012, 41(4): 574-579.
doi: 10.3969/j.issn.1001-0548.2012.04.019
Abstract:
Emergent clustering algorithm ACE is one type of clustering algorithms based on swarm intelligence for mobile ad hoc networks. Aiming at the problems that exist during iterations in ACE, this paper introduces a probability mechanism and proposes a novel probability-based clustering algorithm named PACE. With the local information that the cluster head probability of nodes candidate is the highest, PACE can create a global clustering network. In the case of the same probability, the node identifier is used to arbitrate the elections of cluster heads. Meanwhile, the mergence of single node clusters and failure recovery can also be achieved by the strategies above. The theoretical analysis and simulation results show that PACE has a short convergence time, can find a stable and more optimized clustering structure, and provides a capability of failure recovery.
Emergent clustering algorithm ACE is one type of clustering algorithms based on swarm intelligence for mobile ad hoc networks. Aiming at the problems that exist during iterations in ACE, this paper introduces a probability mechanism and proposes a novel probability-based clustering algorithm named PACE. With the local information that the cluster head probability of nodes candidate is the highest, PACE can create a global clustering network. In the case of the same probability, the node identifier is used to arbitrate the elections of cluster heads. Meanwhile, the mergence of single node clusters and failure recovery can also be achieved by the strategies above. The theoretical analysis and simulation results show that PACE has a short convergence time, can find a stable and more optimized clustering structure, and provides a capability of failure recovery.
2012, 41(4): 586-591.
doi: 10.3969/j.issn.1001-0548.2012.04.021
Abstract:
Aiming at possible failure in software system, a novel software fault tolerance and fault rectification approach is proposed based on data flow abnomity supervision, software watch dog technique and rollback recover technique. This approach backups the object program regularly, establishes data flow analysis model by extracting a group of related variables in object program, and filtrates ‘outliers’ from the data flow by using data flow abnormity detection method. Implementation framework, operation procedure for above software fault tolerance and fault rectification strategy are presented. Binary regression model based on least square-support vector machine and ‘outliers’ detection algorithm are also studied. Simulation results demonstrate the correctness of the binary regression model and the validity of the ‘outliers’ detection algorithm.
Aiming at possible failure in software system, a novel software fault tolerance and fault rectification approach is proposed based on data flow abnomity supervision, software watch dog technique and rollback recover technique. This approach backups the object program regularly, establishes data flow analysis model by extracting a group of related variables in object program, and filtrates ‘outliers’ from the data flow by using data flow abnormity detection method. Implementation framework, operation procedure for above software fault tolerance and fault rectification strategy are presented. Binary regression model based on least square-support vector machine and ‘outliers’ detection algorithm are also studied. Simulation results demonstrate the correctness of the binary regression model and the validity of the ‘outliers’ detection algorithm.
2012, 41(4): 592-595.
doi: 10.3969/j.issn.1001-0548.2012.04.022
Abstract:
After analyzing the four basic information elements of traditional feature selection methods, a new measurement of strong class information is introduced and a new feature selection method is proposed for imbalanced text classification. The strong class information and the frequency of terms are used to improve the classification performance of minority classes and majority classes respectively. The experiments on reuter-21578 dataset show that the proposed method is better than IG and CHI. Both Micro F1 and Macro F1 are improved to some degree.
After analyzing the four basic information elements of traditional feature selection methods, a new measurement of strong class information is introduced and a new feature selection method is proposed for imbalanced text classification. The strong class information and the frequency of terms are used to improve the classification performance of minority classes and majority classes respectively. The experiments on reuter-21578 dataset show that the proposed method is better than IG and CHI. Both Micro F1 and Macro F1 are improved to some degree.
2012, 41(4): 596-598,604.
doi: 10.3969/j.issn.1001-0548.2012.04.023
Abstract:
Three-party password-based authenticated key exchange protocols allow two clients to authenticate each other and establish a shared session key through a trusted server who preserves clients' passwords or verifiers about passwords. However, because of the low entropy of passwords, password-based authenticated key exchange protocols are vulnerable to dictionary attacks. Based on available protocols, a new efficient three-party password-based authenticated key exchange protocol is proposed by combining the symmetric encryption algorithm with the method of two-party key exchange protocol of Diffie-Hellman. Results indicate that and the proposed protocol can resist against various attacks and provide the perfect forward security.
Three-party password-based authenticated key exchange protocols allow two clients to authenticate each other and establish a shared session key through a trusted server who preserves clients' passwords or verifiers about passwords. However, because of the low entropy of passwords, password-based authenticated key exchange protocols are vulnerable to dictionary attacks. Based on available protocols, a new efficient three-party password-based authenticated key exchange protocol is proposed by combining the symmetric encryption algorithm with the method of two-party key exchange protocol of Diffie-Hellman. Results indicate that and the proposed protocol can resist against various attacks and provide the perfect forward security.
2012, 41(4): 599-604.
doi: 10.3969/j.issn.1001-0548.2012.04.024
Abstract:
A general and configurable simulation platform based on SEMI standard is designed. On this general platform, a gas pressure subsystem simulation platform is implemented, which has the function layer, logic layer and communication interface layer. This system can meet the needs of both a single device and a whole system. Results show that the operation of the valve and the change of the gas flow in physical vapor deposition (PVD) system can be simulated in real time.
A general and configurable simulation platform based on SEMI standard is designed. On this general platform, a gas pressure subsystem simulation platform is implemented, which has the function layer, logic layer and communication interface layer. This system can meet the needs of both a single device and a whole system. Results show that the operation of the valve and the change of the gas flow in physical vapor deposition (PVD) system can be simulated in real time.
2012, 41(4): 605-610.
doi: 10.3969/j.issn.1001-0548.2012.04.025
Abstract:
For low cost and low power portable mobile applications, a unique intra prediction architecture for H.264/AVC and AVS dual-mode decoder is proposed based on the idea of programmability. By analyzing the similarity of the data path of different prediction modes in H.264/AVC and AVS, a specific programmable core with customized 8 bit microcode set and efficient data path is implemented. It contains only one 16-bit accumulator and one 16-bit barrel shifter. Implementation results show that the total gates count is only about 6.3K under 0.18 μm process, and the circuit can process real-time H.264/AVC and AVS sequences at D1(720×480) 30 f/s at 35 MHz with only 0.53 mW power consumption at 1.8 V power supply.
For low cost and low power portable mobile applications, a unique intra prediction architecture for H.264/AVC and AVS dual-mode decoder is proposed based on the idea of programmability. By analyzing the similarity of the data path of different prediction modes in H.264/AVC and AVS, a specific programmable core with customized 8 bit microcode set and efficient data path is implemented. It contains only one 16-bit accumulator and one 16-bit barrel shifter. Implementation results show that the total gates count is only about 6.3K under 0.18 μm process, and the circuit can process real-time H.264/AVC and AVS sequences at D1(720×480) 30 f/s at 35 MHz with only 0.53 mW power consumption at 1.8 V power supply.
2012, 41(4): 611-615.
doi: 10.3969/j.issn.1001-0548.2012.04.026
Abstract:
To design a novel power factor correction (PFC) controller integrated circuit, the principle of the PFC pre-regulator is introduced based on the stable operating station of a boost converter in continuous current mode (CCM). The relationships between duty ratio and input current are analyzed in detail, and the requirement for the regulating voltage is also discussed. Matlab simulation results confirm the relationships among the duty-ratio, regulating voltage, slope of input current, input current, and output voltage of the boost converter. The mechanism of the key part of the PFC pre-regulator, the block of regulating voltage VM, is given out, and a kind of VM multiplier integrated circuit is proposed. The whole system simulation results based on HSPICE show that the proposed PFC pro-regulator has good PFC performance.
To design a novel power factor correction (PFC) controller integrated circuit, the principle of the PFC pre-regulator is introduced based on the stable operating station of a boost converter in continuous current mode (CCM). The relationships between duty ratio and input current are analyzed in detail, and the requirement for the regulating voltage is also discussed. Matlab simulation results confirm the relationships among the duty-ratio, regulating voltage, slope of input current, input current, and output voltage of the boost converter. The mechanism of the key part of the PFC pre-regulator, the block of regulating voltage VM, is given out, and a kind of VM multiplier integrated circuit is proposed. The whole system simulation results based on HSPICE show that the proposed PFC pro-regulator has good PFC performance.
2012, 41(4): 616-620.
doi: 10.3969/j.issn.1001-0548.2012.04.027
Abstract:
A novel current reference circuit based on current summing mode and TransLinear structure is proposed in this paper. To enhance the performance, the resistors are also optimized. With curvature compensated, the circuit is of high precision. The circuit is simply designed without operational amplifier. A pre-regulator is also included to improve PSRR. HSPICE simulation with 0.40 μm BCD process shows the temperature coefficient is 27 ppm/℃ in the range -40℃~125℃, the line regulation achieves 0.000 68%/V[7~20 V] at 25℃, and 12 V supply voltage, the quiescent current is 128.09 μA. As described above, the circuit is very suitable for the system of high voltage, low power consumption and high precision.
A novel current reference circuit based on current summing mode and TransLinear structure is proposed in this paper. To enhance the performance, the resistors are also optimized. With curvature compensated, the circuit is of high precision. The circuit is simply designed without operational amplifier. A pre-regulator is also included to improve PSRR. HSPICE simulation with 0.40 μm BCD process shows the temperature coefficient is 27 ppm/℃ in the range -40℃~125℃, the line regulation achieves 0.000 68%/V[7~20 V] at 25℃, and 12 V supply voltage, the quiescent current is 128.09 μA. As described above, the circuit is very suitable for the system of high voltage, low power consumption and high precision.
2012, 41(4): 621-625.
doi: 10.3969/j.issn.1001-0548.2012.04.028
Abstract:
A Brillouin optical time domain analysis (BOTDA) system based on Raman amplification has been theoretically analyzed. The detected probe waveshape has been simulated by using the probe-pump coupled equations combined with Raman. The numerical simulation shows that the bi-directional Raman amplification is very effective for enhancing the measurement accuracy. The experimental exploration of the BOTDA with Raman amplification and semiconductor optical amplifier (SOA) has been demonstrated. The experimental results are in good agreement with the theoretical analysis. The results show that a temperature resolution of 1℃ was achieved over a sensing distance of 49.6 km with a 40 m spatial resolution.
A Brillouin optical time domain analysis (BOTDA) system based on Raman amplification has been theoretically analyzed. The detected probe waveshape has been simulated by using the probe-pump coupled equations combined with Raman. The numerical simulation shows that the bi-directional Raman amplification is very effective for enhancing the measurement accuracy. The experimental exploration of the BOTDA with Raman amplification and semiconductor optical amplifier (SOA) has been demonstrated. The experimental results are in good agreement with the theoretical analysis. The results show that a temperature resolution of 1℃ was achieved over a sensing distance of 49.6 km with a 40 m spatial resolution.
2012, 41(4): 626-630,636.
doi: 10.3969/j.issn.1001-0548.2012.04.029
Abstract:
In order to ensure the fitting of stressed-lap and optical elements with aspheric surface with different local position in real time, regression analysis is used to analyze the changing rule between stressed-lap surface displacements and driving forces. The relationship between stressed-lap surface displacements and driving forces was formulated as a multivariate regression model. The surface displacements of a stressed-lap are modeled as a function of driving forces. The regression coefficients of the model are determined by using the least-squares method. The surface displacements can therefore be calculated quickly based on arbitrary given driving forces. At the same time, the multivariate regression model between driving forces and stressed-lap surface displacements is also proposed in this paper. The solution method is similar to the former model. The driving forces are also quickly calculated based on arbitrary given surface displacements. The proposed models are used to a 420 mm diameter stressed-lap with 12 motors and 60 macro-movement sensors. The case studies show that the results are very close to testing values, and indicate that the proposed models have the accuracy and feasibility.
In order to ensure the fitting of stressed-lap and optical elements with aspheric surface with different local position in real time, regression analysis is used to analyze the changing rule between stressed-lap surface displacements and driving forces. The relationship between stressed-lap surface displacements and driving forces was formulated as a multivariate regression model. The surface displacements of a stressed-lap are modeled as a function of driving forces. The regression coefficients of the model are determined by using the least-squares method. The surface displacements can therefore be calculated quickly based on arbitrary given driving forces. At the same time, the multivariate regression model between driving forces and stressed-lap surface displacements is also proposed in this paper. The solution method is similar to the former model. The driving forces are also quickly calculated based on arbitrary given surface displacements. The proposed models are used to a 420 mm diameter stressed-lap with 12 motors and 60 macro-movement sensors. The case studies show that the results are very close to testing values, and indicate that the proposed models have the accuracy and feasibility.
2012, 41(4): 631-636.
doi: 10.3969/j.issn.1001-0548.2012.04.030
Abstract:
The thermal response of stochastic elastic pole structure under random temperature field is researched in this paper. The transient temperature field is solved by using the method of implicit difference and the numerical characteristics of node temperature field in every time step is obtained with Monte-Carlo simulation. The computation expressions of mean and variance of displacement and stress in every time step are derived from finite element method based on random factor with consideration of mechanical loads. An example of cantilever pole analysis shows the change to the mean value and mean-square deviation of displacement and stress of the random variables in transient duration, and the influence of the response dispersion due to the dispersion of the random parameters under both random static load and random thermal load.
The thermal response of stochastic elastic pole structure under random temperature field is researched in this paper. The transient temperature field is solved by using the method of implicit difference and the numerical characteristics of node temperature field in every time step is obtained with Monte-Carlo simulation. The computation expressions of mean and variance of displacement and stress in every time step are derived from finite element method based on random factor with consideration of mechanical loads. An example of cantilever pole analysis shows the change to the mean value and mean-square deviation of displacement and stress of the random variables in transient duration, and the influence of the response dispersion due to the dispersion of the random parameters under both random static load and random thermal load.
2012, 41(4): 637-640.
doi: 10.3969/j.issn.1001-0548.2012.04.031
Abstract:
To solve the heavy wear and poor life of thrust bearing in vertical motor because of its axial load long-term overload, the paper proposes a method that the axial load is offset by axial electromagnetic tension generated after the asynchronous motor rotor magnetized. Taking the vertical motor of condensed water pump in a 200 MW thermal power unit as example, the life of thrust bearing is calculated in the case of a part of axial loads on the axial magnetic force auxiliary. Experiment result shows that the method can lower the wear of thrust bearing and improve its life.
To solve the heavy wear and poor life of thrust bearing in vertical motor because of its axial load long-term overload, the paper proposes a method that the axial load is offset by axial electromagnetic tension generated after the asynchronous motor rotor magnetized. Taking the vertical motor of condensed water pump in a 200 MW thermal power unit as example, the life of thrust bearing is calculated in the case of a part of axial loads on the axial magnetic force auxiliary. Experiment result shows that the method can lower the wear of thrust bearing and improve its life.
