In electromagnetic countermeasures circumstances,synthetic aperture radar(SAR)imagery usually suffers from severe quality degradation from modulated interrupt sampling repeater jamming(MISRJ),which usually owes consid...In electromagnetic countermeasures circumstances,synthetic aperture radar(SAR)imagery usually suffers from severe quality degradation from modulated interrupt sampling repeater jamming(MISRJ),which usually owes considerable coherence with the SAR transmission waveform together with periodical modulation patterns.This paper develops an MISRJ suppression algorithm for SAR imagery with online dictionary learning.In the algorithm,the jamming modulation temporal properties are exploited with extracting and sorting MISRJ slices using fast-time autocorrelation.Online dictionary learning is followed to separate real signals from jamming slices.Under the learned representation,time-varying MISRJs are suppressed effectively.Both simulated and real-measured SAR data are also used to confirm advantages in suppressing time-varying MISRJs over traditional methods.展开更多
本文为中国国际扶贫中心进行的《贫困农村地区可持续发展研究》研究报告的一部分,该研究聚焦于世界银行在中国进行的扶贫项目,项目采用了社区自主发展(Community-Driven Development,CDD)与社区发展基金(Community Development Fund,CDF...本文为中国国际扶贫中心进行的《贫困农村地区可持续发展研究》研究报告的一部分,该研究聚焦于世界银行在中国进行的扶贫项目,项目采用了社区自主发展(Community-Driven Development,CDD)与社区发展基金(Community Development Fund,CDF)两个分项目。CDD以社区主导型发展途径进行项目村的基础设施建设,CDF以社区发展基金途径支持村民特别是贫困户开展生产创收活动,该项目以治理创新型精准扶贫模式激发贫困人口内生动力,注重自主发展和社区主导发展,创新了基层扶贫治理机制,为贫困地区的可持续发展提供了有效的途径。展开更多
Dictionary has many functions, in which the function of definition is of very importance because the main purpose of dictionary is providing the entry's meaning information for the readers so that the readers can ...Dictionary has many functions, in which the function of definition is of very importance because the main purpose of dictionary is providing the entry's meaning information for the readers so that the readers can understand and use the entry-word and the realization of the purpose completely depends on lexicographical definition. However, the function of definition is limited, which need the exemplification to assist it. Therefore, the exemplification becomes very important, too. Good exemplification can assist definition, provide grammatical information, and supplement the information usage and so on. Many researches studied the exemplification of dictionary, its principles and so on. Dictionary changed much with the development of technology and many kinds of electronic dictionaries appeared. Few studies are involved with the new-type dictionary. Based on the general principles of the exemplification in a learner's printed dictionary, it is necessary to construct the general principles about the exemplification in the electronic learner's dictionary.展开更多
2002年4月15日,国际货币基金组织(IMF)首次以英文公布了中国统计数据文件,标志着中国正式成为IMF“数据公布通用系统”(General Data Dis-semination System,缩写为GDDS)的正式成员。我国加入GDDS是适应经济全球化、金融市场一体化的需...2002年4月15日,国际货币基金组织(IMF)首次以英文公布了中国统计数据文件,标志着中国正式成为IMF“数据公布通用系统”(General Data Dis-semination System,缩写为GDDS)的正式成员。我国加入GDDS是适应经济全球化、金融市场一体化的需要,也是我国进一步改革和扩大对外开放的需要。 一、GDDS的主要要求 (一)统计范围 GDDS将国民经济活动划分为5大经济部门:实际部门、财政部门、金融部门、对外部门和社会人口部门。对每一部门各选定一组能够反映其活动实绩和政策以及可以帮助理解经济发展和结构变化的最为重要的数据类别。系统提出了五大部门综合框架和相关的数据类别和指标编制、公布的目标,鼓励以适当的。展开更多
The success of ultrasonic nondestructive testing technology depends not only on the generation and measurement of the desired waveform, but also on the signal processing of the measured waves. The traditional time-dom...The success of ultrasonic nondestructive testing technology depends not only on the generation and measurement of the desired waveform, but also on the signal processing of the measured waves. The traditional time-domain methods have been partly successful in identifying small cracks, but not so successful in estimating crack size, especially in strong backscattering noise. Sparse signal representation can provide sparse information that represents the signal time-frequency signature, which can also be used in processing ultrasonic nondestructive signals. A novel ultrasonic nondestructive signal processing algorithm based on signal sparse representation is proposed. In order to suppress noise, matching pursuit algorithm with Gabor dictionary is selected as the signal decomposition method. Precise echoes information, such as crack location and size, can be estimated by quantitative analysis with Gabor atom. To verify the performance, the proposed algorithm is applied to computer simulation signal and experimental ultrasonic signals which represent multiple backscattered echoes from a thin metal plate with artificial holes. The results show that this algorithm not only has an excellent performance even when dealing with signals in the presence of strong noise, but also is successful in estimating crack location and size. Moreover, the algorithm can be applied to data compression of ultrasonic nondestructive signal.展开更多
基金supported by the National Natural Science Foundation of China(61771372,61771367,62101494)the National Outstanding Youth Science Fund Project(61525105)+1 种基金Shenzhen Science and Technology Program(KQTD20190929172704911)the Aeronautic al Science Foundation of China(2019200M1001)。
文摘In electromagnetic countermeasures circumstances,synthetic aperture radar(SAR)imagery usually suffers from severe quality degradation from modulated interrupt sampling repeater jamming(MISRJ),which usually owes considerable coherence with the SAR transmission waveform together with periodical modulation patterns.This paper develops an MISRJ suppression algorithm for SAR imagery with online dictionary learning.In the algorithm,the jamming modulation temporal properties are exploited with extracting and sorting MISRJ slices using fast-time autocorrelation.Online dictionary learning is followed to separate real signals from jamming slices.Under the learned representation,time-varying MISRJs are suppressed effectively.Both simulated and real-measured SAR data are also used to confirm advantages in suppressing time-varying MISRJs over traditional methods.
文摘本文为中国国际扶贫中心进行的《贫困农村地区可持续发展研究》研究报告的一部分,该研究聚焦于世界银行在中国进行的扶贫项目,项目采用了社区自主发展(Community-Driven Development,CDD)与社区发展基金(Community Development Fund,CDF)两个分项目。CDD以社区主导型发展途径进行项目村的基础设施建设,CDF以社区发展基金途径支持村民特别是贫困户开展生产创收活动,该项目以治理创新型精准扶贫模式激发贫困人口内生动力,注重自主发展和社区主导发展,创新了基层扶贫治理机制,为贫困地区的可持续发展提供了有效的途径。
文摘Dictionary has many functions, in which the function of definition is of very importance because the main purpose of dictionary is providing the entry's meaning information for the readers so that the readers can understand and use the entry-word and the realization of the purpose completely depends on lexicographical definition. However, the function of definition is limited, which need the exemplification to assist it. Therefore, the exemplification becomes very important, too. Good exemplification can assist definition, provide grammatical information, and supplement the information usage and so on. Many researches studied the exemplification of dictionary, its principles and so on. Dictionary changed much with the development of technology and many kinds of electronic dictionaries appeared. Few studies are involved with the new-type dictionary. Based on the general principles of the exemplification in a learner's printed dictionary, it is necessary to construct the general principles about the exemplification in the electronic learner's dictionary.
基金supported by National Natural Science Foundation of China (Grant No. 60672108, Grant No. 60372020)
文摘The success of ultrasonic nondestructive testing technology depends not only on the generation and measurement of the desired waveform, but also on the signal processing of the measured waves. The traditional time-domain methods have been partly successful in identifying small cracks, but not so successful in estimating crack size, especially in strong backscattering noise. Sparse signal representation can provide sparse information that represents the signal time-frequency signature, which can also be used in processing ultrasonic nondestructive signals. A novel ultrasonic nondestructive signal processing algorithm based on signal sparse representation is proposed. In order to suppress noise, matching pursuit algorithm with Gabor dictionary is selected as the signal decomposition method. Precise echoes information, such as crack location and size, can be estimated by quantitative analysis with Gabor atom. To verify the performance, the proposed algorithm is applied to computer simulation signal and experimental ultrasonic signals which represent multiple backscattered echoes from a thin metal plate with artificial holes. The results show that this algorithm not only has an excellent performance even when dealing with signals in the presence of strong noise, but also is successful in estimating crack location and size. Moreover, the algorithm can be applied to data compression of ultrasonic nondestructive signal.
