ISSN 
2012 Vol. 41, No. 6
2012, 41(6): 809-820.
doi: 10.3969/j.issn.1001-0548.2012.06.001
Abstract:
Since the discovery of the first chaotic Lorenz system, chaos theory has experienced great evolution and development. The complexity and richness of the subject are beyond our wildest imagination. This article demonstrates the beauty of chaos from various points of view, including the ancient philosophical wisdom, the innovation of modern scientific thoughts, the unification of deterministic and stochastic natures, the mystical mechanism of generating chaos, and a variety of complex yet beautiful phase portraits of newly found chaotic attractors.
Since the discovery of the first chaotic Lorenz system, chaos theory has experienced great evolution and development. The complexity and richness of the subject are beyond our wildest imagination. This article demonstrates the beauty of chaos from various points of view, including the ancient philosophical wisdom, the innovation of modern scientific thoughts, the unification of deterministic and stochastic natures, the mystical mechanism of generating chaos, and a variety of complex yet beautiful phase portraits of newly found chaotic attractors.
2012, 41(6): 821-829.
doi: 10.3969/j.issn.1001-0548.2012.06.002
Abstract:
A lot of quantitative theoretical works have been proposed for evolutionary games aiming at evolutionary stable strategies in finite populations. In this paper, we review some latest representative researches, focusing on the risk-dominant strategy and advantageous strategy in well-mixed populations, and the structural dominant strategy in structured populations, including the famous 1/3 law and σ law. Finally, some future directions are pointed out.
A lot of quantitative theoretical works have been proposed for evolutionary games aiming at evolutionary stable strategies in finite populations. In this paper, we review some latest representative researches, focusing on the risk-dominant strategy and advantageous strategy in well-mixed populations, and the structural dominant strategy in structured populations, including the famous 1/3 law and σ law. Finally, some future directions are pointed out.
2012, 41(6): 830-835.
doi: 10.3969/j.issn.1001-0548.2012.06.003
Abstract:
The problem of efficiently mapping a virtual network (VN) over a common physical network is very important for the network virtualization. This paper proposes a VN mapping algorithm based on the relaxed mixed integer linear program (MILP) with close coordination between the node and link mapping. The integer constraints in the MILP formulation of VN mapping problem are relaxed and new linear constraints are added to obtain a strict LP relaxation model, called STRICT_LP. And then a heuristic algorithm is devised to progressively solve the STRICT_LP to get the whole mapping solution. The simulation results show that the proposed algorithm can realize a better coordination between node and link mapping stages and the performances are better than D-ViNE and R-ViNE in term of the acceptance ratio, revenue, cost, and the ratio of revenue to cost.
The problem of efficiently mapping a virtual network (VN) over a common physical network is very important for the network virtualization. This paper proposes a VN mapping algorithm based on the relaxed mixed integer linear program (MILP) with close coordination between the node and link mapping. The integer constraints in the MILP formulation of VN mapping problem are relaxed and new linear constraints are added to obtain a strict LP relaxation model, called STRICT_LP. And then a heuristic algorithm is devised to progressively solve the STRICT_LP to get the whole mapping solution. The simulation results show that the proposed algorithm can realize a better coordination between node and link mapping stages and the performances are better than D-ViNE and R-ViNE in term of the acceptance ratio, revenue, cost, and the ratio of revenue to cost.
2012, 41(6): 836-841.
doi: 10.3969/j.issn.1001-0548.2012.06.004
Abstract:
Noise-normalization combining (NNC) differential frequency hopping (DFH) receiver is proposed to improve the performance of DFH system in rejecting partial-band noise jamming (PBNJ).(SER) performance of this receiver using sequence detection over Rayleigh fading channel is analyzed with consideration of background thermal noise. The anti-PBNJ performances of linear, product and noise-normalization combining DFH receiver are compared. Numerical and simulation results show that the worst-case PBNJ against NNC receiver is full-band jamming. The jamming margin of NNC receiver is improved by more than 8 dB compared with conventional linear combining receiver and nonlinear product combining receiver at 21.4 dB signal-to-noise ratio and the desired 10-4 SER under worst-case PBNJ.
Noise-normalization combining (NNC) differential frequency hopping (DFH) receiver is proposed to improve the performance of DFH system in rejecting partial-band noise jamming (PBNJ).(SER) performance of this receiver using sequence detection over Rayleigh fading channel is analyzed with consideration of background thermal noise. The anti-PBNJ performances of linear, product and noise-normalization combining DFH receiver are compared. Numerical and simulation results show that the worst-case PBNJ against NNC receiver is full-band jamming. The jamming margin of NNC receiver is improved by more than 8 dB compared with conventional linear combining receiver and nonlinear product combining receiver at 21.4 dB signal-to-noise ratio and the desired 10-4 SER under worst-case PBNJ.
2012, 41(6): 847-852.
doi: 10.3969/j.issn.1001-0548.2012.06.006
Abstract:
Sparse microwave imaging technique is very important in the field of the microwave imaging. On the basis of analysis of conventional high resolution range profile (HRRP) synthesizing and ISAR imaging theory with linear frequency modulation (LFM) signal, a new method of sparse processing based on Compressed Sensing (CS) is proposed in the paper. In the method, the high quality HRRP and ISAR image can be achieved by using the two dimension reconstruction with ISAR data after two dimension sparse sampling, on the condition of apparently reducing the sampling rate and pulse number. The sampling burden of digital signal processor and the captured probability of radar signal would be diminished by using the method. The feasibility and effectiveness of the method are verified and robustness of the method is examined via simulation results.
Sparse microwave imaging technique is very important in the field of the microwave imaging. On the basis of analysis of conventional high resolution range profile (HRRP) synthesizing and ISAR imaging theory with linear frequency modulation (LFM) signal, a new method of sparse processing based on Compressed Sensing (CS) is proposed in the paper. In the method, the high quality HRRP and ISAR image can be achieved by using the two dimension reconstruction with ISAR data after two dimension sparse sampling, on the condition of apparently reducing the sampling rate and pulse number. The sampling burden of digital signal processor and the captured probability of radar signal would be diminished by using the method. The feasibility and effectiveness of the method are verified and robustness of the method is examined via simulation results.
2012, 41(6): 853-858.
doi: 10.3969/j.issn.1001-0548.2012.06.007
Abstract:
An implementation for a 1.2 GHz high-linearity quadrature output frequency synthesizer is presented in standard 0.18 μm RF CMOS technology. For achieving optimized phase-noise performance, a high-linearity and low-tuning-sensitivity LC voltage-controlled oscillator is employed. Based on low-switchingnoise source-coupled logic structure, a high-speed divider-by-2 circuit is realized to achieve quadrature local oscillating signal, and a high-speed 8/9 dual-modulus prescaler circuit is implemented. A digital controlled phase frequency detector and difference charge pump are also integrated in the frequency synthesizer. From the carrier frequency of 1.21 GHz, the phase noise of proposed frequency synthesizer is -99.1dBc/Hz and -123.48 dBc/Hz at 100 kHz and 1 MHz offset respectively. The range of output frequency is from 1.13 GHz to 1.33 GHz, the power dissipation is 20.4 mW from a 1.8 V power supply, and the area is (1.5×1.25) mm2.
An implementation for a 1.2 GHz high-linearity quadrature output frequency synthesizer is presented in standard 0.18 μm RF CMOS technology. For achieving optimized phase-noise performance, a high-linearity and low-tuning-sensitivity LC voltage-controlled oscillator is employed. Based on low-switchingnoise source-coupled logic structure, a high-speed divider-by-2 circuit is realized to achieve quadrature local oscillating signal, and a high-speed 8/9 dual-modulus prescaler circuit is implemented. A digital controlled phase frequency detector and difference charge pump are also integrated in the frequency synthesizer. From the carrier frequency of 1.21 GHz, the phase noise of proposed frequency synthesizer is -99.1dBc/Hz and -123.48 dBc/Hz at 100 kHz and 1 MHz offset respectively. The range of output frequency is from 1.13 GHz to 1.33 GHz, the power dissipation is 20.4 mW from a 1.8 V power supply, and the area is (1.5×1.25) mm2.
2012, 41(6): 859-864.
doi: 10.3969/j.issn.1001-0548.2012.06.008
Abstract:
A novel improved particle filter based on sequential importance sampling, Monte Carlo Markov Chain (MCMC) cubature particle filter, is proposed for the estimation of non-linear non-Gaussian system. Each particle is estimated by means of cubature Kalman filter. The importance density function gets closer to the real posterior after taking the current observation into consideration on the basis of state transition. MCMC step is added after the selection. The theoretical analysis and the simulation experiment show the cubature particle filter performs much better than the other parallel filters.
A novel improved particle filter based on sequential importance sampling, Monte Carlo Markov Chain (MCMC) cubature particle filter, is proposed for the estimation of non-linear non-Gaussian system. Each particle is estimated by means of cubature Kalman filter. The importance density function gets closer to the real posterior after taking the current observation into consideration on the basis of state transition. MCMC step is added after the selection. The theoretical analysis and the simulation experiment show the cubature particle filter performs much better than the other parallel filters.
2012, 41(6): 865-869.
doi: 10.3969/j.issn.1001-0548.2012.06.009
Abstract:
In this paper, a folded waveguide was adopted as the slow wave structure (SWS) of the extended interaction oscillator (EIO). An EIO with frequency 105 GHz was studied in detail, including the dispersion relation and the impedance of the SWS, the starting current varying with the period number, the structure of the window and the electron gun (E-gun), and the PIC simulation of the beam-wave interaction with output power 26~50 W and the corresponding frequency 105.26~105.31 GHz. The machining method of the SWS was investigated for fabricating the SWS and the window as well as the E-gun. The preliminary experiment of cold test and hot test was finished, including the performance of the SWS, the window and the E-gun with current density up to 100A/cm2.
In this paper, a folded waveguide was adopted as the slow wave structure (SWS) of the extended interaction oscillator (EIO). An EIO with frequency 105 GHz was studied in detail, including the dispersion relation and the impedance of the SWS, the starting current varying with the period number, the structure of the window and the electron gun (E-gun), and the PIC simulation of the beam-wave interaction with output power 26~50 W and the corresponding frequency 105.26~105.31 GHz. The machining method of the SWS was investigated for fabricating the SWS and the window as well as the E-gun. The preliminary experiment of cold test and hot test was finished, including the performance of the SWS, the window and the E-gun with current density up to 100A/cm2.
2012, 41(6): 870-874.
doi: 10.3969/j.issn.1001-0548.2012.06.010
Abstract:
The process of laser irradiated fused silica was dynamically simulated based on ANSYS. temperature field, shape of melt pool, stress evolution and distribution of residual stress were analyzed and the furthermore distressing annealing was simulated. The results show that, in the course of laser irradiation, the temperature is highest at the center of irradiation area and the temperature gradient is biggest at the edge of irradiation area. After cooling to room temperature, there is large tensile stress at the center and large compressive stress at the edge. Residual stress is significantly reduced after annealing.
The process of laser irradiated fused silica was dynamically simulated based on ANSYS. temperature field, shape of melt pool, stress evolution and distribution of residual stress were analyzed and the furthermore distressing annealing was simulated. The results show that, in the course of laser irradiation, the temperature is highest at the center of irradiation area and the temperature gradient is biggest at the edge of irradiation area. After cooling to room temperature, there is large tensile stress at the center and large compressive stress at the edge. Residual stress is significantly reduced after annealing.
2012, 41(6): 875-880.
doi: 10.3969/j.issn.1001-0548.2012.06.011
Abstract:
As the accuracy of edge detection determines the accuracy of actual size measurement, in order to improve the measuring accuracy, this paper proposes that a faster algorithm should be adopted to detect the glass bottle dimension based on the Zernike moments. The traditional Zernike algorithm is combined with Otsu adaptive threshold algorithm to get a faster improved algorithm. The edge of glass bottle with subpixel level is detected by using the improved algorithm. The ellipses formed by the glass bottle's mouth and bottom are fitted by applying the least square method. At last, the system is calibrated by gauge block to get the actual measuring dimension. Experimental results show that the improved algorithm can not only make the edge detection reach the subpixel accuracy, but also avoid the edge misidentification and inefficient which will be caused by repeatedly manual adjustments to select the threshold value when we detect the edge.
As the accuracy of edge detection determines the accuracy of actual size measurement, in order to improve the measuring accuracy, this paper proposes that a faster algorithm should be adopted to detect the glass bottle dimension based on the Zernike moments. The traditional Zernike algorithm is combined with Otsu adaptive threshold algorithm to get a faster improved algorithm. The edge of glass bottle with subpixel level is detected by using the improved algorithm. The ellipses formed by the glass bottle's mouth and bottom are fitted by applying the least square method. At last, the system is calibrated by gauge block to get the actual measuring dimension. Experimental results show that the improved algorithm can not only make the edge detection reach the subpixel accuracy, but also avoid the edge misidentification and inefficient which will be caused by repeatedly manual adjustments to select the threshold value when we detect the edge.
2012, 41(6): 881-884.
doi: 10.3969/j.issn.1001-0548.2012.06.012
Abstract:
Owing to the low accuracy of traditional method of measuring phase difference and complicated system structure, a new method based on uniform delay of standard frequency phase is proposed in this paper. The standard frequency signal and m-1 equal-delayed standard frequency signals within the zero-crossing interval of the measured signal are counted. The phase differences of the measured signal are obtained after average filtering. Analysis and calculation show that the error of this method is one mth of traditional method. In this method, system-on-a-programmable-chip (SOPC) is applied to design measurement system and phase difference measurement experiments are carried out. Results show that the measurement error is less than ±0.5° and precision is higher than 0.14% under the given conditions. When the standard frequency is increased and the uniform delay interval is reduced, measurement accuracy is further improved. It is concluded that this method has higher precision and better concertedness than traditional method.
Owing to the low accuracy of traditional method of measuring phase difference and complicated system structure, a new method based on uniform delay of standard frequency phase is proposed in this paper. The standard frequency signal and m-1 equal-delayed standard frequency signals within the zero-crossing interval of the measured signal are counted. The phase differences of the measured signal are obtained after average filtering. Analysis and calculation show that the error of this method is one mth of traditional method. In this method, system-on-a-programmable-chip (SOPC) is applied to design measurement system and phase difference measurement experiments are carried out. Results show that the measurement error is less than ±0.5° and precision is higher than 0.14% under the given conditions. When the standard frequency is increased and the uniform delay interval is reduced, measurement accuracy is further improved. It is concluded that this method has higher precision and better concertedness than traditional method.
2012, 41(6): 885-890.
doi: 10.3969/j.issn.1001-0548.2012.06.013
Abstract:
A modified attractive and repulsive particle swarm optimization (MARPSO) algorithm is proposed, which is based on the attractive and repulsive particle swarm optimization (ARPSO) algorithm, by employing new diversity-measure and repulsive operator. Combining both the local convergence ability of hill climbing(HC) algorithm and the characteristic avoid precocious of MARPSO, the way of automatic generation of the software test data based on hill climbing algorithm combined with MARPSO(HC-MARPSO) is proposed. Finally, the results of experiment show that this new algorithm can generate test data more effective than other algorithms, such as genetic algorithm and particle swarm optimization algorithm.
A modified attractive and repulsive particle swarm optimization (MARPSO) algorithm is proposed, which is based on the attractive and repulsive particle swarm optimization (ARPSO) algorithm, by employing new diversity-measure and repulsive operator. Combining both the local convergence ability of hill climbing(HC) algorithm and the characteristic avoid precocious of MARPSO, the way of automatic generation of the software test data based on hill climbing algorithm combined with MARPSO(HC-MARPSO) is proposed. Finally, the results of experiment show that this new algorithm can generate test data more effective than other algorithms, such as genetic algorithm and particle swarm optimization algorithm.
2012, 41(6): 890-892.
doi: 10.3969/j.issn.1001-0548.2012.06.014
Abstract:
The most salient features of Internet of Things (IoT) are its ubiquitous large scale information gathering and intelligent processing to meet everyone's needs. Current solutions in Chinese topic detection and clustering have high time complexity such as O(n2) or O(n3). This paper presents an efficient and patented algorithm for defining topic detection and information clustering over the Internet of Things by combining an improved unigram language model and full text retrieval technique to reduce the time complexity. The experiments and real world applications show that the new method possesses much lesser time complexity.
The most salient features of Internet of Things (IoT) are its ubiquitous large scale information gathering and intelligent processing to meet everyone's needs. Current solutions in Chinese topic detection and clustering have high time complexity such as O(n2) or O(n3). This paper presents an efficient and patented algorithm for defining topic detection and information clustering over the Internet of Things by combining an improved unigram language model and full text retrieval technique to reduce the time complexity. The experiments and real world applications show that the new method possesses much lesser time complexity.
2012, 41(6): 893-898.
doi: 10.3969/j.issn.1001-0548.2012.06.015
Abstract:
In this paper, we propose a distributed access control scheme based on controlled object, in which we make all of the nodes manage the user's right to simplify the right management, and adopt different encryption policy according to the ability of the device object to realize high level of control and low consumption of calculation. The analysis shows that proposed scheme can effectively control the user's access based on node's low cost, and mitigate DOS attack and reply attack of users.
In this paper, we propose a distributed access control scheme based on controlled object, in which we make all of the nodes manage the user's right to simplify the right management, and adopt different encryption policy according to the ability of the device object to realize high level of control and low consumption of calculation. The analysis shows that proposed scheme can effectively control the user's access based on node's low cost, and mitigate DOS attack and reply attack of users.
2012, 41(6): 899-904.
doi: 10.3969/j.issn.1001-0548.2012.06.016
Abstract:
Network address translation detection is the key in Internet administration and security field. Based on the observation that packets from different source devices have different characteristics, a passive remote network address translation detection system (NDS) is designed. IP identification and TCP timestamp time series are established by suitable processing of the headers of trace data. The tested results in real environment on aggregated local trace data shows that NDS could effectively detect network address translation remotely and has relative high detection rate.
Network address translation detection is the key in Internet administration and security field. Based on the observation that packets from different source devices have different characteristics, a passive remote network address translation detection system (NDS) is designed. IP identification and TCP timestamp time series are established by suitable processing of the headers of trace data. The tested results in real environment on aggregated local trace data shows that NDS could effectively detect network address translation remotely and has relative high detection rate.
2012, 41(6): 905-910.
doi: 10.3969/j.issn.1001-0548.2012.06.017
Abstract:
The automatic test case generation is a key phase of software testing and an important part of software assurance. The study on the heuristic algorithms is an emerging area of the automatic test case generation in recent years. The new heuristic algorithm of PSO for the test case generation is reviewed and analyzed. Key issues on the PSO test case generation are discussed, including PSO fitness functions, PSO premature convergence and local optimum, swarm size impact, and parameter optimization. A contrastive analysis of PSO and GA in software testing is presented in detail. Finally, the future development of PSO test case generation algorithms is prospected including the test case swarm size optimization, the premature restraining, and the parameter optimization.
The automatic test case generation is a key phase of software testing and an important part of software assurance. The study on the heuristic algorithms is an emerging area of the automatic test case generation in recent years. The new heuristic algorithm of PSO for the test case generation is reviewed and analyzed. Key issues on the PSO test case generation are discussed, including PSO fitness functions, PSO premature convergence and local optimum, swarm size impact, and parameter optimization. A contrastive analysis of PSO and GA in software testing is presented in detail. Finally, the future development of PSO test case generation algorithms is prospected including the test case swarm size optimization, the premature restraining, and the parameter optimization.
2012, 41(6): 911-915.
doi: 10.3969/j.issn.1001-0548.2012.06.018
Abstract:
Aiming at the dynamic characteristic of grid, to overcome the shortcomings of genetic algorithms which easily get a local optimum solution, a cloud-based genetic algorithm (CGA) for grid task scheduling is proposed. CGA is based on both the idea of GA and the properties of randomness and stable tendency of a normal cloud model. In this algorithm, Y-conditional cloud generator is used for the crossover operator, and basic cloud generator is used for the mutation operator. CGA can optimizes the solution with genetic algorithm based on cloud-model, ascertains the oriental scenario for scheduling, and improves on the arithmetic operators of population initialization, select, crossover, mutation and reinsertion in the process of task scheduling. The experiment validates the feasibility, validity, and practicality of the algorithm.
Aiming at the dynamic characteristic of grid, to overcome the shortcomings of genetic algorithms which easily get a local optimum solution, a cloud-based genetic algorithm (CGA) for grid task scheduling is proposed. CGA is based on both the idea of GA and the properties of randomness and stable tendency of a normal cloud model. In this algorithm, Y-conditional cloud generator is used for the crossover operator, and basic cloud generator is used for the mutation operator. CGA can optimizes the solution with genetic algorithm based on cloud-model, ascertains the oriental scenario for scheduling, and improves on the arithmetic operators of population initialization, select, crossover, mutation and reinsertion in the process of task scheduling. The experiment validates the feasibility, validity, and practicality of the algorithm.
2012, 41(6): 916-920.
doi: 10.3969/j.issn.1001-0548.2012.06.019
Abstract:
Routing metric is critical for performance of wireless mesh networks (WMN). Without considering back-off scheme of IEEE802.11 in Mac layer, expected transmission count (ETX) and expected transmission time (ETT) can not evaluate the average transmission time accurately. A new available transmission time routing metric is proposed based on IEEE 802.11 DCF. We also extend OLSR protocol on Linux platform, and compare ATT with ETX and ETT. The obtained results show that the ATT metric has the lowest packet loss rate and the lowest jitter rate among the analyzed metrics, because it concerns available link bandwidth and also takes physical transmission rates into account.
Routing metric is critical for performance of wireless mesh networks (WMN). Without considering back-off scheme of IEEE802.11 in Mac layer, expected transmission count (ETX) and expected transmission time (ETT) can not evaluate the average transmission time accurately. A new available transmission time routing metric is proposed based on IEEE 802.11 DCF. We also extend OLSR protocol on Linux platform, and compare ATT with ETX and ETT. The obtained results show that the ATT metric has the lowest packet loss rate and the lowest jitter rate among the analyzed metrics, because it concerns available link bandwidth and also takes physical transmission rates into account.
2012, 41(6): 921-926.
doi: 10.3969/j.issn.1001-0548.2012.06.020
Abstract:
To mitigate oscillation phenomenon in Vivaldi Network Coordinate System (NCS) and improve the accuracy of Internet distance prediction, Vivaldi is categorized as a kind of iterative method to solve non-linear equations and thus the adaptive estimation of iterative factor in Vivaldi is raised based on equations' contradictory. By defining a new metric unitization error and measuring it periodically, the awareness of network coordinate oscillation degree can be achieved in real time. Then we separate the iterative process of Vivaldi into 2 logical layers and propose a simple slow-start adaptive algorithm to estimate iterative factor automatically in order to mitigate network coordinate oscillation. The experiments and simulations show this algorithm can reduce the coordinate oscillation by no less than 83.5% without losing any velocity and accuracy, no matter what the initial value of iterative factor is. Furthermore, this algorithm can also be deployed in a hybrid environment together with raw Vivaldi to make the update of NCS smoothly.
To mitigate oscillation phenomenon in Vivaldi Network Coordinate System (NCS) and improve the accuracy of Internet distance prediction, Vivaldi is categorized as a kind of iterative method to solve non-linear equations and thus the adaptive estimation of iterative factor in Vivaldi is raised based on equations' contradictory. By defining a new metric unitization error and measuring it periodically, the awareness of network coordinate oscillation degree can be achieved in real time. Then we separate the iterative process of Vivaldi into 2 logical layers and propose a simple slow-start adaptive algorithm to estimate iterative factor automatically in order to mitigate network coordinate oscillation. The experiments and simulations show this algorithm can reduce the coordinate oscillation by no less than 83.5% without losing any velocity and accuracy, no matter what the initial value of iterative factor is. Furthermore, this algorithm can also be deployed in a hybrid environment together with raw Vivaldi to make the update of NCS smoothly.
2012, 41(6): 927-931.
doi: 10.3969/j.issn.1001-0548.2012.06.021
Abstract:
Basing on the existing (t, n) secret sharing scheme, a dynamic proactive secret sharing scheme which can be applied to access structure is proposed by introducing the concept of adversary structure. The access structure can be changed when the shadows are renewed. The detailed process of the distribution and renewal of the shadows is given, and the validity of the scheme is proved perfectly. The comparisons with the existing schemes show that the proposed scheme is more flexible and its computational cost is less.
Basing on the existing (t, n) secret sharing scheme, a dynamic proactive secret sharing scheme which can be applied to access structure is proposed by introducing the concept of adversary structure. The access structure can be changed when the shadows are renewed. The detailed process of the distribution and renewal of the shadows is given, and the validity of the scheme is proved perfectly. The comparisons with the existing schemes show that the proposed scheme is more flexible and its computational cost is less.
2012, 41(6): 932-936.
doi: 10.3969/j.issn.1001-0548.2012.06.022
Abstract:
In order to improve the adaptive ability and update efficiency of the classic codebook background model when detecting moving targets in complex dynamic scene, an improved codebook model algorithm is proposed. Rapid bubble sorting and short sliding window are used in the new algorithm to sort the position of the code words according to their hit times, which can improve the probability of matching the active code word at the first time. And a short sliding time window is used to buffer the change of the pixel and trace the average and deviations, which can effectively solve the adaptive problem of the model in the case of dynamic background. The result of experiment shows that the improved algorithm provides better detection precision and real-time performance in complex environment conditions.
In order to improve the adaptive ability and update efficiency of the classic codebook background model when detecting moving targets in complex dynamic scene, an improved codebook model algorithm is proposed. Rapid bubble sorting and short sliding window are used in the new algorithm to sort the position of the code words according to their hit times, which can improve the probability of matching the active code word at the first time. And a short sliding time window is used to buffer the change of the pixel and trace the average and deviations, which can effectively solve the adaptive problem of the model in the case of dynamic background. The result of experiment shows that the improved algorithm provides better detection precision and real-time performance in complex environment conditions.
2012, 41(6): 937-940.
doi: 10.3969/j.issn.1001-0548.2012.06.023
Abstract:
SiC photoconducting switches (PCSS) have lots of advantages over conventional switches. By means of device simulator, a two dimension (2D) model of SiC PCSS was set up, and the effect of Vanadium doped concentration on the characteristics of SiC PCSS was explored in a capacitor discharging circuit. In the model, the concentrations of unintentional impurities nitrogen and boron were set to 1×1014 and 1×1011 cm-3 respectively, the wavelength and power of laser were set to 532 nm and 2400 W/cm2, and the initial voltage of the circuit was 1 000 V. When the vanadium doped concentration was 1×1012 cm-3, the circuit generated an unbroken current wave in the initial stage followed by a high leakage current. As soon as the switch was triggered by laser, a peak current of 88 A was formed. After laser triggering, a higher tail current was observed in the circuit. As the vanadium doped concentration was increased to 1×1014 cm-3, the leakage current and tail current both decreased, and the peak current was 8 A. Furthermore, when the vanadium doped concentration was 1×1017cm-3, the peak current reduced to 2.5 A.
SiC photoconducting switches (PCSS) have lots of advantages over conventional switches. By means of device simulator, a two dimension (2D) model of SiC PCSS was set up, and the effect of Vanadium doped concentration on the characteristics of SiC PCSS was explored in a capacitor discharging circuit. In the model, the concentrations of unintentional impurities nitrogen and boron were set to 1×1014 and 1×1011 cm-3 respectively, the wavelength and power of laser were set to 532 nm and 2400 W/cm2, and the initial voltage of the circuit was 1 000 V. When the vanadium doped concentration was 1×1012 cm-3, the circuit generated an unbroken current wave in the initial stage followed by a high leakage current. As soon as the switch was triggered by laser, a peak current of 88 A was formed. After laser triggering, a higher tail current was observed in the circuit. As the vanadium doped concentration was increased to 1×1014 cm-3, the leakage current and tail current both decreased, and the peak current was 8 A. Furthermore, when the vanadium doped concentration was 1×1017cm-3, the peak current reduced to 2.5 A.
2012, 41(6): 941-943.
doi: 10.3969/j.issn.1001-0548.2012.06.024
Abstract:
High field effect mobility (μ) organic thin film transistor (OTFT) was fabricated by using MoO3 buffer layer between organic semiconductor (pentacene) and source/drain electrodes (Ag). The hole mobility of OTFT reached 0.26 cm2/Vs and output current IDS achieved more than 50 μA when the gate voltage was 40 V. The detailed effect of MoO3 buffer layer was analyzed via output characteristics and physical mechanism.
High field effect mobility (μ) organic thin film transistor (OTFT) was fabricated by using MoO3 buffer layer between organic semiconductor (pentacene) and source/drain electrodes (Ag). The hole mobility of OTFT reached 0.26 cm2/Vs and output current IDS achieved more than 50 μA when the gate voltage was 40 V. The detailed effect of MoO3 buffer layer was analyzed via output characteristics and physical mechanism.
2012, 41(6): 944-948.
doi: 10.3969/j.issn.1001-0548.2012.06.025
Abstract:
According to the first and second principles of thermodynamics, the influence of the magnitude of radio-frequency voltage and variations of duty ratio on the heat of high-field asymmetric waveform ion mobility spectrometry (FAIMS) is studied. The absolute value of heat produced by migration tube of FAIMS increases with increasing size of radio-frequency voltage. However, the absolute value is smaller with increasing duty ratio. The result shows that a change in radio-frequency voltage could lead to the temperature difference generated by FAIMS system,which causes the heat transfer and then affects the reliability and stability of FAIMS. By theoretical analysis and algorithm processing, it can be found that the influence of the temperature caused by the performance of the system on FAIMS is minimal when duty ratio is 0.1 and radio-frequency voltage is 2 700 V, which provides essential data for the design of portable FAIMS.
According to the first and second principles of thermodynamics, the influence of the magnitude of radio-frequency voltage and variations of duty ratio on the heat of high-field asymmetric waveform ion mobility spectrometry (FAIMS) is studied. The absolute value of heat produced by migration tube of FAIMS increases with increasing size of radio-frequency voltage. However, the absolute value is smaller with increasing duty ratio. The result shows that a change in radio-frequency voltage could lead to the temperature difference generated by FAIMS system,which causes the heat transfer and then affects the reliability and stability of FAIMS. By theoretical analysis and algorithm processing, it can be found that the influence of the temperature caused by the performance of the system on FAIMS is minimal when duty ratio is 0.1 and radio-frequency voltage is 2 700 V, which provides essential data for the design of portable FAIMS.
2012, 41(6): 949-953.
doi: 10.3969/j.issn.1001-0548.2012.06.026
Abstract:
In this paper, the fluctuation of the performance function at a given percentile is taken as product robustness index, and the interval reliability of the limit state function bigger than the reliability target is formulated as constraint, the reliability-based robust design single objective optimization problem is developed with the mixture of random design variables and interval variables. To improve the efficiency of probability design optimization problem, the two coupled optimization loops are decomposed into two level structure design optimization, the top level is robust design optimization problem, and the lower level is the reliability analysis problem. Finally, the reliability-based robust design of a reducer is presented to verify the efficiency and accuracy of the proposed method.
In this paper, the fluctuation of the performance function at a given percentile is taken as product robustness index, and the interval reliability of the limit state function bigger than the reliability target is formulated as constraint, the reliability-based robust design single objective optimization problem is developed with the mixture of random design variables and interval variables. To improve the efficiency of probability design optimization problem, the two coupled optimization loops are decomposed into two level structure design optimization, the top level is robust design optimization problem, and the lower level is the reliability analysis problem. Finally, the reliability-based robust design of a reducer is presented to verify the efficiency and accuracy of the proposed method.
2012, 41(6): 954-959.
doi: 10.3969/j.issn.1001-0548.2012.06.027
Abstract:
This paper discusses the quality control method of nestedness and auto-correlation manufacturing processes. A novel quality control model based on hybrid modeling is presented, which is combined with the characteristics of nestedness and auto-correlation. By taking nested control model as a framework and introducing auto-covariance function and auto-correlation function, the nested auto-correlation control model is established and the steps for the control chart are presented. The analysis of the model shows that the larger the auto-correlation function value is, the greater the control limit of nested auto-correlation control chart is; and the effect of autocorrelation to the control limit is more prominent when the sample size is smaller. Finally, an example is given to demonstrate the effectiveness of the presented approach.
This paper discusses the quality control method of nestedness and auto-correlation manufacturing processes. A novel quality control model based on hybrid modeling is presented, which is combined with the characteristics of nestedness and auto-correlation. By taking nested control model as a framework and introducing auto-covariance function and auto-correlation function, the nested auto-correlation control model is established and the steps for the control chart are presented. The analysis of the model shows that the larger the auto-correlation function value is, the greater the control limit of nested auto-correlation control chart is; and the effect of autocorrelation to the control limit is more prominent when the sample size is smaller. Finally, an example is given to demonstrate the effectiveness of the presented approach.
