In this paper, buck converters with input filter are modeled using the Euler Lagrange formalism and then build a PBC （passivity based controller）. The model is validated, by comparing its response with those of two ...In this paper, buck converters with input filter are modeled using the Euler Lagrange formalism and then build a PBC （passivity based controller）. The model is validated, by comparing its response with those of two switched circuits： sylnmetric and asymmetric. In the former, both switches are realized by MOSFETS while in the second one of them is realized by a diode. It is then showed by simulation and, explained with energy-based arguments why the obtained model thoroughly represents only the symmetric circuit. The model is then used to build a passivity-based control law. As this control law assumes the stability of the zero dynamic, conditions under which this hypothesis is satisfied, are first given. It is shown by simulation with switched circuits the robustness of the proposed controller against load variations. Then, a prediction of the source variations is included in the controller in order to render it robust against source variations.展开更多
This study investigates the problem of tracking a satellite performing unknown continuous maneuvers. A new method is proposed for estimating both the state and maneuver acceleration of the satellite. The estimation of...This study investigates the problem of tracking a satellite performing unknown continuous maneuvers. A new method is proposed for estimating both the state and maneuver acceleration of the satellite. The estimation of the maneuver acceleration is obtained by the combination of an unbiased minimum-variance input and state estimation method and a low-pass filter. Then a threshold-based maneuver detection approach is developed to determinate the start and end time of the unknown maneuvers. During the maneuvering period, the estimation error of the maneuver acceleration is modeled as the sum of a fluctuation error and a sudden change error. A robust extended Kalman filter is developed for dealing with the acceleration estimate error and providing state estimation. Simulation results show that, compared with the Unbiased Minimum-variance Input and State Estimation(UMISE) method, the proposed method has the same position estimation accuracy, and the velocity estimation error is reduced by about 5 times during the maneuver period. Besides, the acceleration detection and estimation accuracy of the proposed method is much higher than that of the UMISE method.展开更多
"The Input Hypothesis"and"The Affective Filter Hypothesis"are the most important branches of the"Monitor The ory"declared by the famous American linguist Krashen in 1980s.This thesis is b..."The Input Hypothesis"and"The Affective Filter Hypothesis"are the most important branches of the"Monitor The ory"declared by the famous American linguist Krashen in 1980s.This thesis is based on Krashen's Input Hypothesis and Affec tive Filter Hypothesis,aiming to provide an applicable guide for foreign language teachers and learners in China.展开更多
A new multi function voltage-mode universal biquadratic filter using single Voltage Differencing Differential Input Buffered Amplifier (VD-DIBA), two capacitors and one resistor is proposed. The proposed configuration...A new multi function voltage-mode universal biquadratic filter using single Voltage Differencing Differential Input Buffered Amplifier (VD-DIBA), two capacitors and one resistor is proposed. The proposed configuration has four inputs and one output and can realize all the five standard filters from the same circuit configuration. The presented biquad filter offers low active and passive sensitivities. The validity of proposed universal biquadratic filter has been verified by SPICE simulation using 0.35 μm MIETEC technology.展开更多
In this paper, a new observation equation of non-Gaussian frequency selective fading Bell Labs layered space time （BLAST） architecture system is proposed, which is used for frequency selective fading channels and no...In this paper, a new observation equation of non-Gaussian frequency selective fading Bell Labs layered space time （BLAST） architecture system is proposed, which is used for frequency selective fading channels and non-Gaussian noise in an application environment of BLAST system. With othogonal matrix triangularization （QR decomposition） of the channel matrix, the static observation equation of frequency selective fading BLAST system is transformed into a dynamic state space model, and then the particle filter is used for space-time layered detection. Making the full use of the finite alphabet of the digital modulation communication signal, the optimal proposal distribution can be chosen to produce particle and update the weight. Incorporated with current method of reducing error propagation, a new space-time layered detection algorithm is proposed. Simulation result shows the validity of the proposed algorithm.展开更多
American linguist Krashen proposed the input hypothesis and affective filter hypothesis which has influenced linguistic world deeply. These two assumptions play an important role in improving learners' language ab...American linguist Krashen proposed the input hypothesis and affective filter hypothesis which has influenced linguistic world deeply. These two assumptions play an important role in improving learners' language ability in the process of second language acquisition. Applying two hypothesis theories to college English teaching, teachers' aim is to establish a new mode of language teaching and improve the efficiency of college English teaching.展开更多
Detection of the signal’s breakdown points is important for many science and engineering applications. Numerous signal processing methods have been used for this purpose. Of these, the adaptive prediction is simple a...Detection of the signal’s breakdown points is important for many science and engineering applications. Numerous signal processing methods have been used for this purpose. Of these, the adaptive prediction is simple and easy to implement, however;its simplicity and robustness are hindered by the required delay in the input signal. This paper introduces an efficient alternative to the adaptive prediction in the application of breakdown and inflection points’ detection. Unlike the adaptive predictor, the proposed filter doesn’t require a delay in the primary input to produce the filter’s reference input, which significantly improves the computation speed and overcome the problem of performance sensitivity to the delay value. The Normalized Least-Mean Squares algorithm was used to realize both the adaptive predictor and the proposed filter. The filters were implemented in LabVIEW system design software. The performances of the filters were studied using simulated signals and the simulation results were verified using an experimental signal. The simulation and experimental results showed that the proposed filter efficiently detects the signal breakdowns. Furthermore, the simplicity of the filter offered a significant improvement in the computation speed.展开更多
Noises always disturb the control effect of an environment test especially in multi-input multi-output(MIMO) systems. If the frequency response function matrices are ill-conditioned, the noises in the driving forces w...Noises always disturb the control effect of an environment test especially in multi-input multi-output(MIMO) systems. If the frequency response function matrices are ill-conditioned, the noises in the driving forces will be amplified and the response spectral lines may awfully exceed their tolerances. Most of the major biases between the response spectra and the reference spectra are produced by the amplified noises. However, ordinary control algorithms can hardly reduce the level of noises. The influences of the noises on both the auto- and cross-power spectra are analyzed in this paper. As a conventional frequency domain method on the inverse problem, the Tikhonov filter is adopted in the environment test to suppress the exceeding spectral lines. By altering regularization parameters gradually, the auto-power spectra can be improved in a closed control loop. Instead of using the traditional way of selecting regularization parameters, we observe the coherence change to estimate noise eliminations. Incidentally, the requirement of coherence control can be realized. The errors of the phase are then studied and a phase control algorithm is introduced at the end as a supplement of cross-power spectra control. The Tikhonov filter and the proposed phase control algorithm are tested numerically and experimentally. The results show that the noises in the vicinity of lightly damped resonant peaks are more stubborn. The response spectra are able to be greatly improved by the combination of these two methods.展开更多
The Krashen's second language acquisition theory have two important assumptions: input hypothesis and the affective filter hypothesis. They can guide and inspire vocational teaching, because they start from the st...The Krashen's second language acquisition theory have two important assumptions: input hypothesis and the affective filter hypothesis. They can guide and inspire vocational teaching, because they start from the student's learning situation, guide teachers to adjust their teaching methods, and provide better service for teaching and learning. This paper mainly analyzes the Krashen's input hypothesis and the affective filter hypothesis'enlightenment to the vocational English teaching.展开更多
This paper investigates the problem of state estimation for discrete-time stochastic linear systems, where additional knowledge on the unknown inputs is available at an aggregate level and the knowledge on the missing...This paper investigates the problem of state estimation for discrete-time stochastic linear systems, where additional knowledge on the unknown inputs is available at an aggregate level and the knowledge on the missing measurements can be described by a known stochastic distribution. Firstly, the available knowledge on the unknown inputs and the state equation is used to form the prior distribution of the state vector at each time step. Secondly, to obtain an analytically tractable likelihood function, the effect of missing measurements is broken down into a systematic part and a random part, and the latter is modeled as part of the observation noise. Then, a recursive filter is obtained based on Bayesian inference. Finally, a numerical example is provided to evaluate the performance of the proposed methods.展开更多
针对极端条件下光纤偏振光信号的偏振态旋转(Rotation of State of Polarization,RSOP)速度过快,以及本身存在的偏振模色散(Polarization Mode Dispersion,PMD)、残余色散、偏振相关损耗(Polarization Dependent Loss,PDL)、残余载波频...针对极端条件下光纤偏振光信号的偏振态旋转(Rotation of State of Polarization,RSOP)速度过快,以及本身存在的偏振模色散(Polarization Mode Dispersion,PMD)、残余色散、偏振相关损耗(Polarization Dependent Loss,PDL)、残余载波频率偏移(Carrier Frequency Offset,CFO)和载波相位噪声损伤(Carrier Phase Noise,CPN)严重影响通信质量的问题,提出一种基于多输入多输出系统盲均衡算法(Multiple Input Multiple Output-Constant Modulus Algorithm,MIMO-CMA)级联卡尔曼滤波器光纤信道损伤自适应均衡处理优化算法。首先,将包含各种光纤信道损伤的正交相移键控(Quadrature Phase Shift Keying,QPSK)信号使用MIMO-CMA完成残余色散与初步的偏振效应相关损伤均衡,再使用卡尔曼滤波器均衡残余的RSOP损伤、CFO及CPN。仿真结果表明,经过优化算法均衡后的输入信号,其星座图恢复效果良好,且能追踪的RSOP转速可以达到9 Mrad·s^(-1)以上,有效降低了算法的计算复杂度。展开更多
To mitigate the effects of the previous symbol decision errors of a decision-feedback （DF） equalizer on the current decision, a particle filter （PF） based DF equalizer for frequency selective multiple-input-multip...To mitigate the effects of the previous symbol decision errors of a decision-feedback （DF） equalizer on the current decision, a particle filter （PF） based DF equalizer for frequency selective multiple-input-multiple-output （MIMO） channel is proposed. On the basis of the analyses of DF equalization for the MIMO wireless system, it is found that a stochastic interference cancellation （IC） scheme can be employed to prevent the error propagation in a severe space-time interference scenario. This is because the random rather than the deterministic scheme can reduce the probability of an error decision even if an error decision occurs. Besides, the signal-to-interference-plus-noise ratio （SINR） based IC order, which is obtained via pilot, can guarantee the optimality of the cancellation. The bit error rate （BER） performance of the proposed scheme is verified through simulation experiments under different multipath interference environment.展开更多
文摘In this paper, buck converters with input filter are modeled using the Euler Lagrange formalism and then build a PBC （passivity based controller）. The model is validated, by comparing its response with those of two switched circuits： sylnmetric and asymmetric. In the former, both switches are realized by MOSFETS while in the second one of them is realized by a diode. It is then showed by simulation and, explained with energy-based arguments why the obtained model thoroughly represents only the symmetric circuit. The model is then used to build a passivity-based control law. As this control law assumes the stability of the zero dynamic, conditions under which this hypothesis is satisfied, are first given. It is shown by simulation with switched circuits the robustness of the proposed controller against load variations. Then, a prediction of the source variations is included in the controller in order to render it robust against source variations.
基金supported by the National Natural Science Fund for Distinguished Young Scholars of China(No.11525208)
文摘This study investigates the problem of tracking a satellite performing unknown continuous maneuvers. A new method is proposed for estimating both the state and maneuver acceleration of the satellite. The estimation of the maneuver acceleration is obtained by the combination of an unbiased minimum-variance input and state estimation method and a low-pass filter. Then a threshold-based maneuver detection approach is developed to determinate the start and end time of the unknown maneuvers. During the maneuvering period, the estimation error of the maneuver acceleration is modeled as the sum of a fluctuation error and a sudden change error. A robust extended Kalman filter is developed for dealing with the acceleration estimate error and providing state estimation. Simulation results show that, compared with the Unbiased Minimum-variance Input and State Estimation(UMISE) method, the proposed method has the same position estimation accuracy, and the velocity estimation error is reduced by about 5 times during the maneuver period. Besides, the acceleration detection and estimation accuracy of the proposed method is much higher than that of the UMISE method.
文摘"The Input Hypothesis"and"The Affective Filter Hypothesis"are the most important branches of the"Monitor The ory"declared by the famous American linguist Krashen in 1980s.This thesis is based on Krashen's Input Hypothesis and Affec tive Filter Hypothesis,aiming to provide an applicable guide for foreign language teachers and learners in China.
文摘A new multi function voltage-mode universal biquadratic filter using single Voltage Differencing Differential Input Buffered Amplifier (VD-DIBA), two capacitors and one resistor is proposed. The proposed configuration has four inputs and one output and can realize all the five standard filters from the same circuit configuration. The presented biquad filter offers low active and passive sensitivities. The validity of proposed universal biquadratic filter has been verified by SPICE simulation using 0.35 μm MIETEC technology.
文摘In this paper, a new observation equation of non-Gaussian frequency selective fading Bell Labs layered space time （BLAST） architecture system is proposed, which is used for frequency selective fading channels and non-Gaussian noise in an application environment of BLAST system. With othogonal matrix triangularization （QR decomposition） of the channel matrix, the static observation equation of frequency selective fading BLAST system is transformed into a dynamic state space model, and then the particle filter is used for space-time layered detection. Making the full use of the finite alphabet of the digital modulation communication signal, the optimal proposal distribution can be chosen to produce particle and update the weight. Incorporated with current method of reducing error propagation, a new space-time layered detection algorithm is proposed. Simulation result shows the validity of the proposed algorithm.
文摘American linguist Krashen proposed the input hypothesis and affective filter hypothesis which has influenced linguistic world deeply. These two assumptions play an important role in improving learners' language ability in the process of second language acquisition. Applying two hypothesis theories to college English teaching, teachers' aim is to establish a new mode of language teaching and improve the efficiency of college English teaching.
文摘Detection of the signal’s breakdown points is important for many science and engineering applications. Numerous signal processing methods have been used for this purpose. Of these, the adaptive prediction is simple and easy to implement, however;its simplicity and robustness are hindered by the required delay in the input signal. This paper introduces an efficient alternative to the adaptive prediction in the application of breakdown and inflection points’ detection. Unlike the adaptive predictor, the proposed filter doesn’t require a delay in the primary input to produce the filter’s reference input, which significantly improves the computation speed and overcome the problem of performance sensitivity to the delay value. The Normalized Least-Mean Squares algorithm was used to realize both the adaptive predictor and the proposed filter. The filters were implemented in LabVIEW system design software. The performances of the filters were studied using simulated signals and the simulation results were verified using an experimental signal. The simulation and experimental results showed that the proposed filter efficiently detects the signal breakdowns. Furthermore, the simplicity of the filter offered a significant improvement in the computation speed.
基金supported by the Fundamental Research Funds for the Central Universities (No. NS2015008)the corresponding work was performed in the State Key Laboratory of Mechanics and Control of Mechanical Structures
文摘Noises always disturb the control effect of an environment test especially in multi-input multi-output(MIMO) systems. If the frequency response function matrices are ill-conditioned, the noises in the driving forces will be amplified and the response spectral lines may awfully exceed their tolerances. Most of the major biases between the response spectra and the reference spectra are produced by the amplified noises. However, ordinary control algorithms can hardly reduce the level of noises. The influences of the noises on both the auto- and cross-power spectra are analyzed in this paper. As a conventional frequency domain method on the inverse problem, the Tikhonov filter is adopted in the environment test to suppress the exceeding spectral lines. By altering regularization parameters gradually, the auto-power spectra can be improved in a closed control loop. Instead of using the traditional way of selecting regularization parameters, we observe the coherence change to estimate noise eliminations. Incidentally, the requirement of coherence control can be realized. The errors of the phase are then studied and a phase control algorithm is introduced at the end as a supplement of cross-power spectra control. The Tikhonov filter and the proposed phase control algorithm are tested numerically and experimentally. The results show that the noises in the vicinity of lightly damped resonant peaks are more stubborn. The response spectra are able to be greatly improved by the combination of these two methods.
文摘The Krashen's second language acquisition theory have two important assumptions: input hypothesis and the affective filter hypothesis. They can guide and inspire vocational teaching, because they start from the student's learning situation, guide teachers to adjust their teaching methods, and provide better service for teaching and learning. This paper mainly analyzes the Krashen's input hypothesis and the affective filter hypothesis'enlightenment to the vocational English teaching.
基金jointly funded by UK Engineering and Physical Sciences Research Council(EPSRC)and BAE System(EP/H501401/1)
文摘This paper investigates the problem of state estimation for discrete-time stochastic linear systems, where additional knowledge on the unknown inputs is available at an aggregate level and the knowledge on the missing measurements can be described by a known stochastic distribution. Firstly, the available knowledge on the unknown inputs and the state equation is used to form the prior distribution of the state vector at each time step. Secondly, to obtain an analytically tractable likelihood function, the effect of missing measurements is broken down into a systematic part and a random part, and the latter is modeled as part of the observation noise. Then, a recursive filter is obtained based on Bayesian inference. Finally, a numerical example is provided to evaluate the performance of the proposed methods.
基金supported in part by the National Natural Science Foundation of China (60672047)the Shanghai Postdoctoral Scientific Program (05R214110).
文摘To mitigate the effects of the previous symbol decision errors of a decision-feedback （DF） equalizer on the current decision, a particle filter （PF） based DF equalizer for frequency selective multiple-input-multiple-output （MIMO） channel is proposed. On the basis of the analyses of DF equalization for the MIMO wireless system, it is found that a stochastic interference cancellation （IC） scheme can be employed to prevent the error propagation in a severe space-time interference scenario. This is because the random rather than the deterministic scheme can reduce the probability of an error decision even if an error decision occurs. Besides, the signal-to-interference-plus-noise ratio （SINR） based IC order, which is obtained via pilot, can guarantee the optimality of the cancellation. The bit error rate （BER） performance of the proposed scheme is verified through simulation experiments under different multipath interference environment.
