An extensive database (946 measurements) for the frequency of pulsing flow in trickle beds was established by collecting the experimental results published over past 30 years. A new correlation based on artificial neu...An extensive database (946 measurements) for the frequency of pulsing flow in trickle beds was established by collecting the experimental results published over past 30 years. A new correlation based on artificial neural network (ANN) to predict the pulsation frequency was developed. Seven dimensionless numbers (groups) employed in the proposed correlation were liquid and gas Reynolds, liquid Weber, liquid Eotvos, gas Froude, and gas Stokes numbers and a bed correction factor. The comparisons of performance reported in the of literature and present correlations show that ANN correlation is a significant improvement in predicting pulsation frequency with an average absolute relative error (AARE) of 10% and a standard deviation less than 18%.展开更多
Wireless sensor-actuator networks can bring flexibility to smart home.We design and develop a smart home prototype using wireless sensor-actuator network technology to realize environmental sensing and the control of ...Wireless sensor-actuator networks can bring flexibility to smart home.We design and develop a smart home prototype using wireless sensor-actuator network technology to realize environmental sensing and the control of electric appliances.The basic motivation of our solution is to utilize the collaboration among a mass of low-cost sensor nodes and actuator nodes to make life convenient.To achieve it,we design a novel system architecture with assembled component modules.In particular,we address some key technical challenges:1) Field-Programmable Gate Array (FPGA) Implementation of Adaptive Differential Pulse Code Modulation (ADPCM) for audio data;2) FPGA Implementation of Lempel Ziv Storer Szymanski (LZSS) for bulk data;3) combination of complex control logic.Finally,a set of experiments are presented to evaluate the performance of our solution.展开更多
Pulse width modulation （ PWM） drive control digitalization is the key for the full digital invert power supply. New ideas are proposed, which are based on field programmable gate array （ FPGA ）. First, digital PWM...Pulse width modulation （ PWM） drive control digitalization is the key for the full digital invert power supply. New ideas are proposed, which are based on field programmable gate array （ FPGA ）. First, digital PWM principles are discussed. The primary and secondary current characteristics are analyzed when the transformer is in both normal and magnetic bias conditions. Second, two digitalization methods are put forward after the research on PWM adjustment principles, which are based on the primary current feedback. Though the two methods could restrain magnetic bias, their realization is difficult. A new method is researched on double close-loops to overcome the above shortcomings, which uses the secondary current as the feedback signal and the primary current as the protection signal. Finally, the secondary current control made is discussed and realized. Welding experimental results show that the method has strong flexibility and adaptability, which can be used to realize the full digital welding power supply.展开更多
Based on the principle of virtual equivalent gain,the evolution of self-similar pulses in a normal dispersion-decreasing fiber is investigated.The occurrence of wave breaking during the process under highly nonlinear ...Based on the principle of virtual equivalent gain,the evolution of self-similar pulses in a normal dispersion-decreasing fiber is investigated.The occurrence of wave breaking during the process under highly nonlinear conditions and the effect of its revealed four-wave mixing on the process are also analyzed.The results indicate that the pulse spectrum broadeningin the initial stage is dominated by self-phase modulation while by four-wave mixing in the later stage.The more intense nonlinearity is,the faster the pulse evolution converges to the self-similarity synchronously in both the time domain and the spectrum domain.展开更多
基金the State Key Development Program for Basic Research of China (No. G2000048005)the SINOPEC (X503023).
文摘An extensive database (946 measurements) for the frequency of pulsing flow in trickle beds was established by collecting the experimental results published over past 30 years. A new correlation based on artificial neural network (ANN) to predict the pulsation frequency was developed. Seven dimensionless numbers (groups) employed in the proposed correlation were liquid and gas Reynolds, liquid Weber, liquid Eotvos, gas Froude, and gas Stokes numbers and a bed correction factor. The comparisons of performance reported in the of literature and present correlations show that ANN correlation is a significant improvement in predicting pulsation frequency with an average absolute relative error (AARE) of 10% and a standard deviation less than 18%.
基金supported by the Natural Science Foundation of China under Grant No.61070206,No.61070205and No.60833009the National973Project of China under Grant No.2011CB302701+2 种基金the program of New Century Excellent Talents in University of China under Grant No.NCET-080737the Beijing National Natural Science Foundation under Grant No.4092030the Cosponsored Project of Beijing Committee of Education
文摘Wireless sensor-actuator networks can bring flexibility to smart home.We design and develop a smart home prototype using wireless sensor-actuator network technology to realize environmental sensing and the control of electric appliances.The basic motivation of our solution is to utilize the collaboration among a mass of low-cost sensor nodes and actuator nodes to make life convenient.To achieve it,we design a novel system architecture with assembled component modules.In particular,we address some key technical challenges:1) Field-Programmable Gate Array (FPGA) Implementation of Adaptive Differential Pulse Code Modulation (ADPCM) for audio data;2) FPGA Implementation of Lempel Ziv Storer Szymanski (LZSS) for bulk data;3) combination of complex control logic.Finally,a set of experiments are presented to evaluate the performance of our solution.
文摘Pulse width modulation （ PWM） drive control digitalization is the key for the full digital invert power supply. New ideas are proposed, which are based on field programmable gate array （ FPGA ）. First, digital PWM principles are discussed. The primary and secondary current characteristics are analyzed when the transformer is in both normal and magnetic bias conditions. Second, two digitalization methods are put forward after the research on PWM adjustment principles, which are based on the primary current feedback. Though the two methods could restrain magnetic bias, their realization is difficult. A new method is researched on double close-loops to overcome the above shortcomings, which uses the secondary current as the feedback signal and the primary current as the protection signal. Finally, the secondary current control made is discussed and realized. Welding experimental results show that the method has strong flexibility and adaptability, which can be used to realize the full digital welding power supply.
基金supported by the School Key Fund of South-central University for Nationalities(No.yzz05008)the Hubei Provincial Department of Education(No.Q20101613)
文摘Based on the principle of virtual equivalent gain,the evolution of self-similar pulses in a normal dispersion-decreasing fiber is investigated.The occurrence of wave breaking during the process under highly nonlinear conditions and the effect of its revealed four-wave mixing on the process are also analyzed.The results indicate that the pulse spectrum broadeningin the initial stage is dominated by self-phase modulation while by four-wave mixing in the later stage.The more intense nonlinearity is,the faster the pulse evolution converges to the self-similarity synchronously in both the time domain and the spectrum domain.
