Frequency-tunable microwave signal generation is proposed and experimentally demonstrated with a dual-wavelength single-longitudinal-mode （SLM） erbium-doped fiber ring laser based on a digital Opto-DMD processor and...Frequency-tunable microwave signal generation is proposed and experimentally demonstrated with a dual-wavelength single-longitudinal-mode （SLM） erbium-doped fiber ring laser based on a digital Opto-DMD processor and four-wave mixing （FWM） in a high-nonlinear photonic crystal fiber （PCF）. The high-nonlinear PCF is employed for the generation of the FWM to obtain stable and uniform dual-wavelength oscillation. Two different short passive sub-ring cavities in the main ring cavity serve as mode filters to make SLM lasing. The two lasing wavelengths are electronically selected by loading different gratings on the Opto-DMD processor controlled with a computer. The wavelength spacing can be smartly adjusted from 0.165 nm to 1.08 nm within a tuning accuracy of 0.055 nm. Two microwave signals at 17.23 GHz and 27.47 GHz are achieved. The stability of the microwave signal is discussed. The system has the ability to generate a 137.36-GHz photonic millimeter signal at room temperature.展开更多
We propose and theoretically analyze a plasmonic corrugated horn structure for enhanced optical transmission. It makes use of the enhancement of unidirectional propagating surface plasmon polaritons at oblique inciden...We propose and theoretically analyze a plasmonic corrugated horn structure for enhanced optical transmission. It makes use of the enhancement of unidirectional propagating surface plasmon polaritons at oblique incidence. Geometric parameters such as the groove depth and width are optimized. Analysis shows that it presents a better performance than the bull＇s eye structure for a small number of grooves.展开更多
This paper focuses on the performance analysis of flexible reactive systems. The performance analysis consists of two phases： first system modeling, second performance evalua-tion. The paper models the flexible react...This paper focuses on the performance analysis of flexible reactive systems. The performance analysis consists of two phases： first system modeling, second performance evalua-tion. The paper models the flexible reactive system by the stochas-tic statecharts method, and uses the simulation method to evalu-ate the performance. To make use of the feature of event-triggered state transitions in the statecharts, a new method of simulation is proposed based on the techniques of the discrete-event system simulation. The new method solves the problem of computer imple-mentation of stochastic events, probabilistic transition, concurrent states, paral el actions, and broadcast communication mechanism in the stochastic statecharts. An example of a flexible manufactur-ing system is presented. The simulation result of the example is consistent with the analytical result, which shows the feasibility of the proposed new simulation method.展开更多
Optical wireless communications have been widely studied during the past decade in short-range applications, such as indoor highspeed wireless networks and interconnects in data centers and high-performance computing....Optical wireless communications have been widely studied during the past decade in short-range applications, such as indoor highspeed wireless networks and interconnects in data centers and high-performance computing. In this paper, recent developments in high-speed short-range optical wireless communications are reviewed, including visible light communications （VLCs）, infrared indoor communication systems, and reconfigurable optical interconnects. The general architecture of indoor high-speed optical wireless communications is described, and the advantages and limitations of both visible and infrared based solutions are discussed. The concept of reconfigurable optical interconnects is presented, and key results are summarized. In addition, the challenges and potential future directions of short-range optical wireless communications are discussed.展开更多
Accurate crop and weed discrimination plays a critical role in addressing the challenges of weed management in agriculture.The use of herbicides is currently the most common approach to weed control.However,herbicide ...Accurate crop and weed discrimination plays a critical role in addressing the challenges of weed management in agriculture.The use of herbicides is currently the most common approach to weed control.However,herbicide resistant plants have long been recognised as a major concern due to the excessive use of herbicides.Effective weed detection techniques can reduce the cost of weed management and improve crop quality and yield.A computationally efficient and robust plant classification algorithm is developed and applied to the classification of three crops:Brassica napus(canola),Zea mays(maize/corn),and radish.The developed algorithm is based on the combination of Local Binary Pattern(LBP)operators,for the extraction of crop leaf textural features and Support vector machine(SVM)method,for multiclass plant classification.This paper presents the first investigation of the accuracy of the combined LBP algorithms,trained using a large dataset of canola,radish and barley leaf images captured by a testing facility under simulated field conditions.The dataset has four subclasses,background,canola,corn,and radish,with 24,000 images used for training and 6000 images,for validation.The dataset is referred herein as "bccr-segset"and published online.In each subclass,plant images are collected at four crop growth stages.Experimentally,the algorithm demonstrates plant classification accuracy as high as 91.85%,for the four classes.展开更多
While several recent studies have focused on elimi-nating the imbalance of energy stored in series-connected battery cells,very little attention has been given to balancing the energy stored in parallel-connected batt...While several recent studies have focused on elimi-nating the imbalance of energy stored in series-connected battery cells,very little attention has been given to balancing the energy stored in parallel-connected battery cells.As such,this paper aims at presenting a new balancing approach for parallel LiFePO_(4) battery cells.In this regard,a Backpropagation Neural Network(BPNN)based technique is employed to develop a Battery Management System(BMS)that can assess the charging status of all cells and control its operations through a DC/DC Buck-Boost converter.Simulation results demonstrate the effectiveness of the proposed approach in balancing the energy stored in parallel-connected battery cells in which the state of charge(SoC)estimation error is found to be only 1.15%.展开更多
A stable three-channel dual-wavelength fiber ring laser is proposed and experimentally demonstrated. The dig- ital mieromirror-deviee （DMD） processor can select and reeirculate any dual waveband from the gain spectr...A stable three-channel dual-wavelength fiber ring laser is proposed and experimentally demonstrated. The dig- ital mieromirror-deviee （DMD） processor can select and reeirculate any dual waveband from the gain spectrum of the erbium-doped fiber at each channel. The uniform and stable dual-wavelength oscillation is obtained by a highly nonlinear photonic crystal fiber, which causes two degenerate the four-wave-mixing processes. By loading different reproducibility diffraction gratings on the optoelectronic DMD processor, the laser can be operated stably in a three-channel dual-wavelength scheme at room temperature. The power fluctuation of each laser channel is less than -0.02 dB.展开更多
Irradiation with swift heavy ions causes the deformation of Ferric nanoparticles in direction of the ion beam.Fe nanoparticles with mean diameter of about 20 nm were prepared by gas flow sputtering and subsequently co...Irradiation with swift heavy ions causes the deformation of Ferric nanoparticles in direction of the ion beam.Fe nanoparticles with mean diameter of about 20 nm were prepared by gas flow sputtering and subsequently confined within silica films.Two silica films wherein two different densities of Fe nanoparticles are encapsulated were irradiated with 50 MeV Ag ions with fluences of few 1014 ions.cm^(-2) at 300 K and normal incidence.Transmission electron microscopy analysis shows that the spherical Fe nanoparticles are deformed into prolate nanorods aligned in direction of the incident ion beam.The depth distribution profiles of irradiated particles reveal the presence of a critical fluence above which the elongation kinetics becomes dependent on the nanoparticles density.Analysis indicates that for the lower density particles,a saturation length is reached under irradiation to fluence between 3-4×10^(14) ions.cm^(-2).However,for the higher density,collective growth into aligned nanowires is presumed to take place.Hysteresis curves of the saturation magnetization and coercivity indicate an increasing magnetic anisotropy,which can be correlated with the deformation of nanoparticles in the direction of the ion beam.展开更多
文章作者在植物光谱识别的基础上提出了一种能够识别不同绿色植物的新颖光电子技术.该项技术运用于可见至近红外波段,在实验室环境和农田环境下,可以成功地采集和分析目标的光谱数据,对不同品种的绿色植物实施了精确识别.该项研究是由...文章作者在植物光谱识别的基础上提出了一种能够识别不同绿色植物的新颖光电子技术.该项技术运用于可见至近红外波段,在实验室环境和农田环境下,可以成功地采集和分析目标的光谱数据,对不同品种的绿色植物实施了精确识别.该项研究是由跨学科的西澳大利亚微光电子系统中心有限公司(the Western Australian Centre ofExcellence for MicroPhotonic Systems,Pty Ltd,)和中国大恒集团公司共同研究完成的,其目标是开发国际上首台野草传感器,使得除草剂的使用定位精确,既可显著提高作物的产量,又可节约80%除草剂,更重要的是保护环境,节约用水,对于农业和生态都有重要意义.展开更多
基金supported by the National Basic Research Program of China(Grant No.2010CB327605)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20120005120021)+2 种基金the Fundamental Research Funds for the Central Universities,China(Grant No.2013RC1202)the Program for New Century Excellent Talents in University,China(Grant No.NECT-11-0596)the Beijing Nova Program,China(Grant No.2011066)
文摘Frequency-tunable microwave signal generation is proposed and experimentally demonstrated with a dual-wavelength single-longitudinal-mode （SLM） erbium-doped fiber ring laser based on a digital Opto-DMD processor and four-wave mixing （FWM） in a high-nonlinear photonic crystal fiber （PCF）. The high-nonlinear PCF is employed for the generation of the FWM to obtain stable and uniform dual-wavelength oscillation. Two different short passive sub-ring cavities in the main ring cavity serve as mode filters to make SLM lasing. The two lasing wavelengths are electronically selected by loading different gratings on the Opto-DMD processor controlled with a computer. The wavelength spacing can be smartly adjusted from 0.165 nm to 1.08 nm within a tuning accuracy of 0.055 nm. Two microwave signals at 17.23 GHz and 27.47 GHz are achieved. The stability of the microwave signal is discussed. The system has the ability to generate a 137.36-GHz photonic millimeter signal at room temperature.
基金Supported by the National Natural Science Foundation of China under Grant No 60772002, and the Research Fund for the Doctoral Program of Higher Education under Grant No 200800010037.
文摘We propose and theoretically analyze a plasmonic corrugated horn structure for enhanced optical transmission. It makes use of the enhancement of unidirectional propagating surface plasmon polaritons at oblique incidence. Geometric parameters such as the groove depth and width are optimized. Analysis shows that it presents a better performance than the bull＇s eye structure for a small number of grooves.
基金supported by the National Natural Science Foundation of China(61171120)
文摘This paper focuses on the performance analysis of flexible reactive systems. The performance analysis consists of two phases： first system modeling, second performance evalua-tion. The paper models the flexible reactive system by the stochas-tic statecharts method, and uses the simulation method to evalu-ate the performance. To make use of the feature of event-triggered state transitions in the statecharts, a new method of simulation is proposed based on the techniques of the discrete-event system simulation. The new method solves the problem of computer imple-mentation of stochastic events, probabilistic transition, concurrent states, paral el actions, and broadcast communication mechanism in the stochastic statecharts. An example of a flexible manufactur-ing system is presented. The simulation result of the example is consistent with the analytical result, which shows the feasibility of the proposed new simulation method.
基金supported under Australian Research Council’s Discovery Early Career Researcher Award(DECRA)funding scheme(project number DE150100924)The University of Melbourne’s Early Career Researcher(ECR)funding scheme(project number 602702)the Victoria Fellowship(D2015/35025)
文摘Optical wireless communications have been widely studied during the past decade in short-range applications, such as indoor highspeed wireless networks and interconnects in data centers and high-performance computing. In this paper, recent developments in high-speed short-range optical wireless communications are reviewed, including visible light communications （VLCs）, infrared indoor communication systems, and reconfigurable optical interconnects. The general architecture of indoor high-speed optical wireless communications is described, and the advantages and limitations of both visible and infrared based solutions are discussed. The concept of reconfigurable optical interconnects is presented, and key results are summarized. In addition, the challenges and potential future directions of short-range optical wireless communications are discussed.
文摘Accurate crop and weed discrimination plays a critical role in addressing the challenges of weed management in agriculture.The use of herbicides is currently the most common approach to weed control.However,herbicide resistant plants have long been recognised as a major concern due to the excessive use of herbicides.Effective weed detection techniques can reduce the cost of weed management and improve crop quality and yield.A computationally efficient and robust plant classification algorithm is developed and applied to the classification of three crops:Brassica napus(canola),Zea mays(maize/corn),and radish.The developed algorithm is based on the combination of Local Binary Pattern(LBP)operators,for the extraction of crop leaf textural features and Support vector machine(SVM)method,for multiclass plant classification.This paper presents the first investigation of the accuracy of the combined LBP algorithms,trained using a large dataset of canola,radish and barley leaf images captured by a testing facility under simulated field conditions.The dataset has four subclasses,background,canola,corn,and radish,with 24,000 images used for training and 6000 images,for validation.The dataset is referred herein as "bccr-segset"and published online.In each subclass,plant images are collected at four crop growth stages.Experimentally,the algorithm demonstrates plant classification accuracy as high as 91.85%,for the four classes.
基金research and innovation management center(RIMC)UNIMAS via Fundamental Research Grant Scheme FRGS/1/2017/TK10/UNIMAS/03/1,Ministry of Higher Education,Malaysia.
文摘While several recent studies have focused on elimi-nating the imbalance of energy stored in series-connected battery cells,very little attention has been given to balancing the energy stored in parallel-connected battery cells.As such,this paper aims at presenting a new balancing approach for parallel LiFePO_(4) battery cells.In this regard,a Backpropagation Neural Network(BPNN)based technique is employed to develop a Battery Management System(BMS)that can assess the charging status of all cells and control its operations through a DC/DC Buck-Boost converter.Simulation results demonstrate the effectiveness of the proposed approach in balancing the energy stored in parallel-connected battery cells in which the state of charge(SoC)estimation error is found to be only 1.15%.
基金supported by the National Basic Research Program of China(2010CB327600)the Fundamental Research Funds for the Central Universities(2013RC1202)+2 种基金the Specialized Research Fund for the Doctoral Program of Higher Education(20120005120021)the Program for New Century Excellent Talents in University(NECT-11-0596)the Beijing Nova program(2011066)
文摘A stable three-channel dual-wavelength fiber ring laser is proposed and experimentally demonstrated. The dig- ital mieromirror-deviee （DMD） processor can select and reeirculate any dual waveband from the gain spectrum of the erbium-doped fiber at each channel. The uniform and stable dual-wavelength oscillation is obtained by a highly nonlinear photonic crystal fiber, which causes two degenerate the four-wave-mixing processes. By loading different reproducibility diffraction gratings on the optoelectronic DMD processor, the laser can be operated stably in a three-channel dual-wavelength scheme at room temperature. The power fluctuation of each laser channel is less than -0.02 dB.
文摘Irradiation with swift heavy ions causes the deformation of Ferric nanoparticles in direction of the ion beam.Fe nanoparticles with mean diameter of about 20 nm were prepared by gas flow sputtering and subsequently confined within silica films.Two silica films wherein two different densities of Fe nanoparticles are encapsulated were irradiated with 50 MeV Ag ions with fluences of few 1014 ions.cm^(-2) at 300 K and normal incidence.Transmission electron microscopy analysis shows that the spherical Fe nanoparticles are deformed into prolate nanorods aligned in direction of the incident ion beam.The depth distribution profiles of irradiated particles reveal the presence of a critical fluence above which the elongation kinetics becomes dependent on the nanoparticles density.Analysis indicates that for the lower density particles,a saturation length is reached under irradiation to fluence between 3-4×10^(14) ions.cm^(-2).However,for the higher density,collective growth into aligned nanowires is presumed to take place.Hysteresis curves of the saturation magnetization and coercivity indicate an increasing magnetic anisotropy,which can be correlated with the deformation of nanoparticles in the direction of the ion beam.
文摘文章作者在植物光谱识别的基础上提出了一种能够识别不同绿色植物的新颖光电子技术.该项技术运用于可见至近红外波段,在实验室环境和农田环境下,可以成功地采集和分析目标的光谱数据,对不同品种的绿色植物实施了精确识别.该项研究是由跨学科的西澳大利亚微光电子系统中心有限公司(the Western Australian Centre ofExcellence for MicroPhotonic Systems,Pty Ltd,)和中国大恒集团公司共同研究完成的,其目标是开发国际上首台野草传感器,使得除草剂的使用定位精确,既可显著提高作物的产量,又可节约80%除草剂,更重要的是保护环境,节约用水,对于农业和生态都有重要意义.
