The radioheliograph is an extensive array of antennas operating on the principle of aperture synthesis to produce images of the Sun.The image acquired by the telescope results from convoluting the Sun’s true brightne...The radioheliograph is an extensive array of antennas operating on the principle of aperture synthesis to produce images of the Sun.The image acquired by the telescope results from convoluting the Sun’s true brightness distribution with the antenna array’s directional pattern.The imaging quality of the radioheliograph is affected by a multitude of factors,with the performance of the“dirty beam”being simply one component.Other factors such as imaging methods,calibration techniques,clean algorithms,and more also play a significant influence on the resulting image quality.As the layout of the antenna array directly affects the performance of the dirty beam,the design of an appropriate antenna configuration is critical to improving the imaging quality of the radioheliograph.Based on the actual needs of observing the Sun,this work optimized the antenna array design and proposed a twodimensional low-redundancy array.The proposed array was compared with common T-shaped arrays,Y-shaped arrays,uniformly spaced circular arrays,and three-arm spiral arrays.Through simulations and experiments,their performance in terms of sampling point numbers,UV coverage area,beam-half width,sidelobe level,and performance in the absence of antennas are compared and analyzed.It was found that each of these arrays has its advantages,but the two-dimensional low-redundancy array proposed in this paper performs best in overall evaluation.It has the shortest imaging calculation time among the array types and is highly robust when antennas are missing,making it the most suitable choice.展开更多
分布式能源规模化接入电网对电网产生了新的挑战,主动配电网(active distribution network,ADN)技术被认为是分布式能源规模化利用的有效技术途径。统一电能质量控制器(unified power quality controller,UPQC)作为定制电力技术中功能...分布式能源规模化接入电网对电网产生了新的挑战,主动配电网(active distribution network,ADN)技术被认为是分布式能源规模化利用的有效技术途径。统一电能质量控制器(unified power quality controller,UPQC)作为定制电力技术中功能最强大的电能质量综合补偿装置,能够综合治理主动配电网中电能质量问题,提高分布式能源接入配电网的渗透率及优化经济运行水平。文章对分布式能源的并网和主动配电网中的电能质量问题做了简要介绍,并对UPQC的概念、基本结构及其工作原理进行了详细阐述,最后仿真验证了UPQC能够有效地综合治理ADN中复杂的多重电压和电流质量问题。展开更多
A new digital receiver with excellent performances has been designed and developed for solar radio observation,which can receive the radio signal from direct current(DC)to 9 GHz in the direct acquisition way.On the di...A new digital receiver with excellent performances has been designed and developed for solar radio observation,which can receive the radio signal from direct current(DC)to 9 GHz in the direct acquisition way.On the digital receiver,the analog-to-digital converter(ADC)with 14-bit,two input channels and 3 Giga Samples per second(Gsps)are used to acquire observed signal,and the field-programmable-gate-array chip XCKU115 acts as the processing module.The new digital receiver can be used to directly sample the solar radio signals of frequency under 9 GHz.When receiving the solar radio signal above 9 GHz,the new digital receiver can save 1–2 stages of frequency down-conversion,and effectively improve many indexes of the solar radio observation system,i.e.,the time resolution,analog front-end circuit,weight and volume of the analog circuit system.Compared with the digital receiver with sampling rate below 1 Gsps used in existing solar radio telescope,the new digital receiver reduces the frequency switching times of large bandwidth,which is beneficial to improving the frequency and time resolutions.The ADC sampling resolution of 14 bits,providing a large dynamic range,is very beneficial to observing smaller solar eruptions.This receiver,which would be used in the solar radio observation system,well meets the latest requirements with the resolutions of time(≤1 ms)and frequency(≤0.5 MHz)for fine observation of radio signals.展开更多
基金supported by the grants of the National Natural Science Foundation of China(42127804,42374219)。
文摘The radioheliograph is an extensive array of antennas operating on the principle of aperture synthesis to produce images of the Sun.The image acquired by the telescope results from convoluting the Sun’s true brightness distribution with the antenna array’s directional pattern.The imaging quality of the radioheliograph is affected by a multitude of factors,with the performance of the“dirty beam”being simply one component.Other factors such as imaging methods,calibration techniques,clean algorithms,and more also play a significant influence on the resulting image quality.As the layout of the antenna array directly affects the performance of the dirty beam,the design of an appropriate antenna configuration is critical to improving the imaging quality of the radioheliograph.Based on the actual needs of observing the Sun,this work optimized the antenna array design and proposed a twodimensional low-redundancy array.The proposed array was compared with common T-shaped arrays,Y-shaped arrays,uniformly spaced circular arrays,and three-arm spiral arrays.Through simulations and experiments,their performance in terms of sampling point numbers,UV coverage area,beam-half width,sidelobe level,and performance in the absence of antennas are compared and analyzed.It was found that each of these arrays has its advantages,but the two-dimensional low-redundancy array proposed in this paper performs best in overall evaluation.It has the shortest imaging calculation time among the array types and is highly robust when antennas are missing,making it the most suitable choice.
文摘分布式能源规模化接入电网对电网产生了新的挑战,主动配电网(active distribution network,ADN)技术被认为是分布式能源规模化利用的有效技术途径。统一电能质量控制器(unified power quality controller,UPQC)作为定制电力技术中功能最强大的电能质量综合补偿装置,能够综合治理主动配电网中电能质量问题,提高分布式能源接入配电网的渗透率及优化经济运行水平。文章对分布式能源的并网和主动配电网中的电能质量问题做了简要介绍,并对UPQC的概念、基本结构及其工作原理进行了详细阐述,最后仿真验证了UPQC能够有效地综合治理ADN中复杂的多重电压和电流质量问题。
基金the National Natural Science Foundation of China(grant Nos.42127804,41774180 and 41904158)Shandong postdoctoral innovation project(202002004)Young Scholars Program of Shandong University,Weihai(208220201005)。
文摘A new digital receiver with excellent performances has been designed and developed for solar radio observation,which can receive the radio signal from direct current(DC)to 9 GHz in the direct acquisition way.On the digital receiver,the analog-to-digital converter(ADC)with 14-bit,two input channels and 3 Giga Samples per second(Gsps)are used to acquire observed signal,and the field-programmable-gate-array chip XCKU115 acts as the processing module.The new digital receiver can be used to directly sample the solar radio signals of frequency under 9 GHz.When receiving the solar radio signal above 9 GHz,the new digital receiver can save 1–2 stages of frequency down-conversion,and effectively improve many indexes of the solar radio observation system,i.e.,the time resolution,analog front-end circuit,weight and volume of the analog circuit system.Compared with the digital receiver with sampling rate below 1 Gsps used in existing solar radio telescope,the new digital receiver reduces the frequency switching times of large bandwidth,which is beneficial to improving the frequency and time resolutions.The ADC sampling resolution of 14 bits,providing a large dynamic range,is very beneficial to observing smaller solar eruptions.This receiver,which would be used in the solar radio observation system,well meets the latest requirements with the resolutions of time(≤1 ms)and frequency(≤0.5 MHz)for fine observation of radio signals.
