DC DC convertors can convert the EV's high voltage DC power supply into the low voltage DC power supply. In order to design an excellent convertor one must be guided by theory of automatic control. The principl...DC DC convertors can convert the EV's high voltage DC power supply into the low voltage DC power supply. In order to design an excellent convertor one must be guided by theory of automatic control. The principle and the method of design, modeling and control for DC DC convertors of EV are introduced. The method of the system response to a unit step function input and the frequency response method are applied to researching the convertor's mathematics model and control characteristic. Experiments show that the designed DC DC convertor's output voltage precision is high, the antijamming ability is strong and the adjustable performance is fast and smooth.展开更多
The method of FRactional Fourier Transform (FRFT) is introduced to Transform Domain Communication System (TDCS) for signal transforming in the paper after theoretical analysis. The method yields optimal Basis Function...The method of FRactional Fourier Transform (FRFT) is introduced to Transform Domain Communication System (TDCS) for signal transforming in the paper after theoretical analysis. The method yields optimal Basis Function (BF) by FRFT with optimal transform angle. The TDCS using the proposed method has wider usable spectrum, stronger robustness and better ability of anti non-stationary jamming than using usual methods, such as Fourier Transform (FT), Auto Regressive (AR), Wavelet Transform (WT), etc. The main simulation results are as follows. First, the Bit Error Rate (BER) Pb is close to theoretical bound of no jamming no matter in single tone or in linear chirp interference. Second, the interference-to-signal ratio J /E is at least 12dB more than that of Direct Spread Spectrum System (DSSS) under the same BER if the spectrum hopping-to-signal ratio is 1:20 in chirp plus hopping interfering. Third, the Eb /N 0(when estimation difference is 90% between trans- mitter and receiver) is about 3.5dB or about 0.5dB (when estimation difference is 10% between transmitter and receiver) more than that of theoretical result when no estimation difference un-der Pb=10-2.展开更多
Gasoline blending is a key process in a petroleum refinery, as it can yield 60%–70% of a typical refinery's total revenue. This process not only exhibits non-convex nonlinear blending behavior due to the complica...Gasoline blending is a key process in a petroleum refinery, as it can yield 60%–70% of a typical refinery's total revenue. This process not only exhibits non-convex nonlinear blending behavior due to the complicated blend mechanism of various component feedstocks with different quality properties, but also involves global optimum searching among numerous blending recipes. Since blend products are required to meet a series of quality requirements and highly-sensitive to the proportion changes of blending feedstocks, global optimization methods for NLP problems are often difficult to be applied because of heavy computational burdens. Thus, piecewise linearization methods are naturally proposed to provide an approximate global optimum solution by adding binary variables into the models and converting the original NLP problems into MILP ones. In this paper, Logarithmtransform piecewise linearization(LTPL) method, an improved piecewise linearization, is proposed. In this method a logarithm transform is applied to convert multi-variable multi-degree constraints into a series of single-variable constraints. As a result, the number of 0–1 variables is greatly reduced. In the final part of this paper, an industrial case study is conducted to demonstrate the effectiveness of LTPL method. In principle, this method would be useful for blending problems with complicated empirical or theoretical models.展开更多
A new model of roving frame FA467, which uses four frequency inverters to replace the complex mechanical transmission, is discussed. A Neuron-PID is designed to reduce the effect of various parametric variations such ...A new model of roving frame FA467, which uses four frequency inverters to replace the complex mechanical transmission, is discussed. A Neuron-PID is designed to reduce the effect of various parametric variations such as load inertia. To ensure the constant spinning tension all over the spinning process, a feedforward controller using iterative learning control algorithm is desigend to avoid disturbances caused by changes of temperature, humidity and so on. The simulation result is shown to illustrate the effectiveness of the proposed algorithm, and now the roving frame FA467 has been developed successfully.展开更多
An interference suppression algorithm is proposed to meet challenges of the traditional technique in dealing with the linear frequency modulation(LFM) interference,such as high loss of signal-to-noise ratio(SNR),the o...An interference suppression algorithm is proposed to meet challenges of the traditional technique in dealing with the linear frequency modulation(LFM) interference,such as high loss of signal-to-noise ratio(SNR),the output signal-to-interfer-ence-plus-noise ratio(SINR) sensitive to input interference-to-signal ratio(ISR) that results in an unstable synchronization,and the spectrum leakage serious in strong ISR situation.This approach firstly makes use of the windowed and lapped technique to the fractional Fourier transform(FRFT) to enhance the ISR improvement and lower the SNR loss.Then by weakening the interference and a secondary threshold process,interference energy can be suppressed as much as possible and the output SINR is less sensitive to the ISR.Finally,a joint fractional Fourier domain and time domain technique is proposed to overcome the residual interference energy caused by the strong interference or the discontinuous-phase interference.Theoretical analysis and simulation results show that the proposed algorithm can achieve better performance than the conventional methods in suppressing both the multi period LFM interference and the multi chirp-rate LFM interference,especially in the strong interference environment.展开更多
文摘DC DC convertors can convert the EV's high voltage DC power supply into the low voltage DC power supply. In order to design an excellent convertor one must be guided by theory of automatic control. The principle and the method of design, modeling and control for DC DC convertors of EV are introduced. The method of the system response to a unit step function input and the frequency response method are applied to researching the convertor's mathematics model and control characteristic. Experiments show that the designed DC DC convertor's output voltage precision is high, the antijamming ability is strong and the adjustable performance is fast and smooth.
基金Supported by Fund of National Key Lab.of Communication.
文摘The method of FRactional Fourier Transform (FRFT) is introduced to Transform Domain Communication System (TDCS) for signal transforming in the paper after theoretical analysis. The method yields optimal Basis Function (BF) by FRFT with optimal transform angle. The TDCS using the proposed method has wider usable spectrum, stronger robustness and better ability of anti non-stationary jamming than using usual methods, such as Fourier Transform (FT), Auto Regressive (AR), Wavelet Transform (WT), etc. The main simulation results are as follows. First, the Bit Error Rate (BER) Pb is close to theoretical bound of no jamming no matter in single tone or in linear chirp interference. Second, the interference-to-signal ratio J /E is at least 12dB more than that of Direct Spread Spectrum System (DSSS) under the same BER if the spectrum hopping-to-signal ratio is 1:20 in chirp plus hopping interfering. Third, the Eb /N 0(when estimation difference is 90% between trans- mitter and receiver) is about 3.5dB or about 0.5dB (when estimation difference is 10% between transmitter and receiver) more than that of theoretical result when no estimation difference un-der Pb=10-2.
基金Supported by the National Basic Research Program of China(2012CB720500)the National Natural Science Foundation of China(U1462206)
文摘Gasoline blending is a key process in a petroleum refinery, as it can yield 60%–70% of a typical refinery's total revenue. This process not only exhibits non-convex nonlinear blending behavior due to the complicated blend mechanism of various component feedstocks with different quality properties, but also involves global optimum searching among numerous blending recipes. Since blend products are required to meet a series of quality requirements and highly-sensitive to the proportion changes of blending feedstocks, global optimization methods for NLP problems are often difficult to be applied because of heavy computational burdens. Thus, piecewise linearization methods are naturally proposed to provide an approximate global optimum solution by adding binary variables into the models and converting the original NLP problems into MILP ones. In this paper, Logarithmtransform piecewise linearization(LTPL) method, an improved piecewise linearization, is proposed. In this method a logarithm transform is applied to convert multi-variable multi-degree constraints into a series of single-variable constraints. As a result, the number of 0–1 variables is greatly reduced. In the final part of this paper, an industrial case study is conducted to demonstrate the effectiveness of LTPL method. In principle, this method would be useful for blending problems with complicated empirical or theoretical models.
文摘A new model of roving frame FA467, which uses four frequency inverters to replace the complex mechanical transmission, is discussed. A Neuron-PID is designed to reduce the effect of various parametric variations such as load inertia. To ensure the constant spinning tension all over the spinning process, a feedforward controller using iterative learning control algorithm is desigend to avoid disturbances caused by changes of temperature, humidity and so on. The simulation result is shown to illustrate the effectiveness of the proposed algorithm, and now the roving frame FA467 has been developed successfully.
基金partially supported by the National Natural Science Foun-dation of China for Distinguished Young Scholars (Grant No. 60625104) the Foundation for Beijing Excellent Ph.D,Thesis (Grant No. 1320037010901)
文摘An interference suppression algorithm is proposed to meet challenges of the traditional technique in dealing with the linear frequency modulation(LFM) interference,such as high loss of signal-to-noise ratio(SNR),the output signal-to-interfer-ence-plus-noise ratio(SINR) sensitive to input interference-to-signal ratio(ISR) that results in an unstable synchronization,and the spectrum leakage serious in strong ISR situation.This approach firstly makes use of the windowed and lapped technique to the fractional Fourier transform(FRFT) to enhance the ISR improvement and lower the SNR loss.Then by weakening the interference and a secondary threshold process,interference energy can be suppressed as much as possible and the output SINR is less sensitive to the ISR.Finally,a joint fractional Fourier domain and time domain technique is proposed to overcome the residual interference energy caused by the strong interference or the discontinuous-phase interference.Theoretical analysis and simulation results show that the proposed algorithm can achieve better performance than the conventional methods in suppressing both the multi period LFM interference and the multi chirp-rate LFM interference,especially in the strong interference environment.
