According to the requirement of multi-parameter time and frequency measurement without frequency normalization,a different frequency synchronization theory is proposed based on Lissajous figure method and the variatio...According to the requirement of multi-parameter time and frequency measurement without frequency normalization,a different frequency synchronization theory is proposed based on Lissajous figure method and the variation lawof Lissajous figure which are used in practice teaching of frequency measurement. The theory can achieve high-precision transmission and comparison of time and frequency and precise locking and tracking of phase and frequency,improve the level of scientific research on time and frequency for postgraduate,and promote practice teaching innovation of time frequency measurement for undergraduate. Utilizing the ratio of horizontal and vertical inflection point of the Lissajous figure,the nominal frequency of the measured signal is precisely calculated.The frequency deviation between the measured frequency and its nominal frequency can be obtained by combining the turning cycle of the Lissajous figure. By observing the phase relationship between the frequency standard signal and the measured signal,the accurate measurement of the frequency is implemented. Experimental results showthat the direct measurement and comparison better than the 10-11 order of magnitude with common frequency source can be finished between any signal frequencies.The frequency measurement method based on the theory has the advantage of simple operation,quick measurement speed,small error,lownoise and high measurement precision. It plays an important role in time synchronization,communications,metrology,scientific research,educational technology practice and equipment and other fields.展开更多
Exploring the aptitude of the human brain to compensate functional consequences of a lesion damaging its structural architecture is a key challenge to improve patient care in various neurological diseases,to optimize ...Exploring the aptitude of the human brain to compensate functional consequences of a lesion damaging its structural architecture is a key challenge to improve patient care in various neurological diseases,to optimize neuroscientifically-informed strategies of postlesional rehabilitation,and ultimately to develop innovative neuro-regenerative therapies.The term‘plasticity’,initially referring to the intrinsic propensity of neurons to modulate their synaptic transmission in a learning situation,was progressively transposed to brain injury research and clinical neurosciences.Indeed,in the event of brain damage,adaptive mechanisms of compensation allow a partial reshaping of the structure and activities of the central nervous system,thus permitting to some extent the maintenance of brain functions.展开更多
In the field of contemporary sculpture creation,the rich culture and historical depth of Chinese ethnic minorities have attracted the widespread attention of artists.These creations not only emphasize external feature...In the field of contemporary sculpture creation,the rich culture and historical depth of Chinese ethnic minorities have attracted the widespread attention of artists.These creations not only emphasize external features such as ethnic costumes,totems,or life scenes but also touch deep spiritual contents including historical stories,religious beliefs,and living habits of ethnic minorities.This paper discusses the integration process of Chinese ethnic minority themes in figurative sculpture creation and the inheritance of the profound spirit of ethnic groups in this process.At the same time,this paper also places the diversified expression and innovative practice of these themes in sculpture art in the context of the new era for investigation and explores the far-reaching influence of its development on promoting cultural inheritance and artistic innovation.展开更多
研究了一种基于Lissajous图形的光纤分布式扰动传感器定位方法。光纤分布式扰动传感器基于Mach-Zehnder干涉仪，通过两路输出信号的时延得到扰动定位。在两路输出信号的Lissajous图形中构造拟合椭圆，基于实验数据的仿真研究表明：通过...研究了一种基于Lissajous图形的光纤分布式扰动传感器定位方法。光纤分布式扰动传感器基于Mach-Zehnder干涉仪，通过两路输出信号的时延得到扰动定位。在两路输出信号的Lissajous图形中构造拟合椭圆，基于实验数据的仿真研究表明：通过椭圆半短轴长可以得到时延，实现定位。法进行了仿真和实验研究，在无需噪声抑制的条件下定位精度较高：在信噪比为-6~7dB范围，最大定位误差为207 m 多次测量中，最大误差为94 m。研究结论可以为光纤分布式扰动传感器定位方法提供新的技术参考。展开更多
Based on the equivalent circuit model of a two-port optical receiver front-end,the relationship between the equivalent input noise current spectral density and the noise figure is analyzed. The derived relationship ha...Based on the equivalent circuit model of a two-port optical receiver front-end,the relationship between the equivalent input noise current spectral density and the noise figure is analyzed. The derived relationship has universal validity for determining the equivalent input noise current spectral density for optical receiver designs, as verified by measuring a 155Mb/s high-impedance optical receiver front.end. Good agreement between calculated and simulated results has been achieved.展开更多
基金Supported by the Project of Higher Education Teaching Reform and Practice in Henan Province(2017SJGLX353)the Project of Science and Technology on Electronic Information Control Laboratory,the Science and Technology Innovation Talents in Colleges and Universities of Henan Province(16HASTIT036)+2 种基金the Educational Technology Equipment and Practical Education of Henan Province(GZS028)the National Natural Science Foundation of China(U1304618)the Key Projects of Science And Technology of Henan Province(152102210351)
文摘According to the requirement of multi-parameter time and frequency measurement without frequency normalization,a different frequency synchronization theory is proposed based on Lissajous figure method and the variation lawof Lissajous figure which are used in practice teaching of frequency measurement. The theory can achieve high-precision transmission and comparison of time and frequency and precise locking and tracking of phase and frequency,improve the level of scientific research on time and frequency for postgraduate,and promote practice teaching innovation of time frequency measurement for undergraduate. Utilizing the ratio of horizontal and vertical inflection point of the Lissajous figure,the nominal frequency of the measured signal is precisely calculated.The frequency deviation between the measured frequency and its nominal frequency can be obtained by combining the turning cycle of the Lissajous figure. By observing the phase relationship between the frequency standard signal and the measured signal,the accurate measurement of the frequency is implemented. Experimental results showthat the direct measurement and comparison better than the 10-11 order of magnitude with common frequency source can be finished between any signal frequencies.The frequency measurement method based on the theory has the advantage of simple operation,quick measurement speed,small error,lownoise and high measurement precision. It plays an important role in time synchronization,communications,metrology,scientific research,educational technology practice and equipment and other fields.
文摘Exploring the aptitude of the human brain to compensate functional consequences of a lesion damaging its structural architecture is a key challenge to improve patient care in various neurological diseases,to optimize neuroscientifically-informed strategies of postlesional rehabilitation,and ultimately to develop innovative neuro-regenerative therapies.The term‘plasticity’,initially referring to the intrinsic propensity of neurons to modulate their synaptic transmission in a learning situation,was progressively transposed to brain injury research and clinical neurosciences.Indeed,in the event of brain damage,adaptive mechanisms of compensation allow a partial reshaping of the structure and activities of the central nervous system,thus permitting to some extent the maintenance of brain functions.
文摘In the field of contemporary sculpture creation,the rich culture and historical depth of Chinese ethnic minorities have attracted the widespread attention of artists.These creations not only emphasize external features such as ethnic costumes,totems,or life scenes but also touch deep spiritual contents including historical stories,religious beliefs,and living habits of ethnic minorities.This paper discusses the integration process of Chinese ethnic minority themes in figurative sculpture creation and the inheritance of the profound spirit of ethnic groups in this process.At the same time,this paper also places the diversified expression and innovative practice of these themes in sculpture art in the context of the new era for investigation and explores the far-reaching influence of its development on promoting cultural inheritance and artistic innovation.
文摘研究了一种基于Lissajous图形的光纤分布式扰动传感器定位方法。光纤分布式扰动传感器基于Mach-Zehnder干涉仪，通过两路输出信号的时延得到扰动定位。在两路输出信号的Lissajous图形中构造拟合椭圆，基于实验数据的仿真研究表明：通过椭圆半短轴长可以得到时延，实现定位。法进行了仿真和实验研究，在无需噪声抑制的条件下定位精度较高：在信噪比为-6~7dB范围，最大定位误差为207 m 多次测量中，最大误差为94 m。研究结论可以为光纤分布式扰动传感器定位方法提供新的技术参考。
文摘Based on the equivalent circuit model of a two-port optical receiver front-end,the relationship between the equivalent input noise current spectral density and the noise figure is analyzed. The derived relationship has universal validity for determining the equivalent input noise current spectral density for optical receiver designs, as verified by measuring a 155Mb/s high-impedance optical receiver front.end. Good agreement between calculated and simulated results has been achieved.
