荧光原位杂交(fluorescence in situ hybridization,FISH)分离探针因设计、判读相对简单而广泛应用于肿瘤的病理诊疗。目前针对FISH分离探针中出现的非典型信号类型及意义尚无系统研究。该文根据国内外相关研究,系统总结了FISH分离探针...荧光原位杂交(fluorescence in situ hybridization,FISH)分离探针因设计、判读相对简单而广泛应用于肿瘤的病理诊疗。目前针对FISH分离探针中出现的非典型信号类型及意义尚无系统研究。该文根据国内外相关研究,系统总结了FISH分离探针非典型信号的类型、意义、出现的可能原因及机制,为FISH分离探针非典型信号的判读及深入研究提供理论基础。展开更多
For solving the difficult problem of leakage detection in city gas pipelines, a method using acoustic technique based on instantaneous energy (IE) distribution and correlation analysis was proposed. Firstly, the basic...For solving the difficult problem of leakage detection in city gas pipelines, a method using acoustic technique based on instantaneous energy (IE) distribution and correlation analysis was proposed. Firstly, the basic theory of leakage detection and location was introduced. Then the physical relationship between instantaneous energy and structural state variation of a system was analyzed theoretically. With HILBERT-HUANG transformation (HHT), the instantaneous energy distribution feature of an unstable acoustic signal was obtained. According to the relative contribution method of the instantaneous energy, the noise in signal was eliminated effectively. Furthermore, in order to judge the leakage, the typical characteristic of the instantaneous energy of signal in the input and output end was discussed using correlative analysis. A number of experiments were carried out to classify the leakage from normal operations, and the results show that the leakages are successfully detected and the average recognition rate reaches 93.3% among three group samples. It is shown that the method using acoustic technique with IED and correlative analysis is effective and it may be referred in other pipelines.展开更多
Processes like combustion, pyrolysis or gasification of coal and biomass are typical applications of gas-solid fluidized beds. These reactors normally use silica sand as the inert material inside the bed and the sand ...Processes like combustion, pyrolysis or gasification of coal and biomass are typical applications of gas-solid fluidized beds. These reactors normally use silica sand as the inert material inside the bed and the sand particles represent around 95% of the total bed weight. Pressure measurements have been used to characterize the dynamic behavior of fluidized beds since early researches in the area. Pressure fluctuations are generally due to bubbles flow which characterizes the fluidization regime. The present work aims to perform a time-frequency analysis of the pressure signal acquired in an experimental apparatus on different gas-solid flow regimes. Continuous and discrete wavelet transforms were applied and the results were compared with image records acquired simultaneously with the pressure signal. The main frequencies observed are in accordance with the ones obtained through Fourier spectra. The time-frequency distribution of the signal agrees with the phenomena observed in the image record, remarkably for the slugging flow. Some additional research is still necessary to completely characterize the flow regimes using the wavelet scalograms but the present results show that the task is a very promising one.展开更多
文摘荧光原位杂交(fluorescence in situ hybridization,FISH)分离探针因设计、判读相对简单而广泛应用于肿瘤的病理诊疗。目前针对FISH分离探针中出现的非典型信号类型及意义尚无系统研究。该文根据国内外相关研究,系统总结了FISH分离探针非典型信号的类型、意义、出现的可能原因及机制,为FISH分离探针非典型信号的判读及深入研究提供理论基础。
基金Project(51004005) supported by the National Natural Science Foundation of ChinaProject supported by Open Research Fund Program of Beijing Engineering Research Center of Monitoring for Construction Safety (Beijing University of Civil Engineering and Architecture), China
文摘For solving the difficult problem of leakage detection in city gas pipelines, a method using acoustic technique based on instantaneous energy (IE) distribution and correlation analysis was proposed. Firstly, the basic theory of leakage detection and location was introduced. Then the physical relationship between instantaneous energy and structural state variation of a system was analyzed theoretically. With HILBERT-HUANG transformation (HHT), the instantaneous energy distribution feature of an unstable acoustic signal was obtained. According to the relative contribution method of the instantaneous energy, the noise in signal was eliminated effectively. Furthermore, in order to judge the leakage, the typical characteristic of the instantaneous energy of signal in the input and output end was discussed using correlative analysis. A number of experiments were carried out to classify the leakage from normal operations, and the results show that the leakages are successfully detected and the average recognition rate reaches 93.3% among three group samples. It is shown that the method using acoustic technique with IED and correlative analysis is effective and it may be referred in other pipelines.
文摘Processes like combustion, pyrolysis or gasification of coal and biomass are typical applications of gas-solid fluidized beds. These reactors normally use silica sand as the inert material inside the bed and the sand particles represent around 95% of the total bed weight. Pressure measurements have been used to characterize the dynamic behavior of fluidized beds since early researches in the area. Pressure fluctuations are generally due to bubbles flow which characterizes the fluidization regime. The present work aims to perform a time-frequency analysis of the pressure signal acquired in an experimental apparatus on different gas-solid flow regimes. Continuous and discrete wavelet transforms were applied and the results were compared with image records acquired simultaneously with the pressure signal. The main frequencies observed are in accordance with the ones obtained through Fourier spectra. The time-frequency distribution of the signal agrees with the phenomena observed in the image record, remarkably for the slugging flow. Some additional research is still necessary to completely characterize the flow regimes using the wavelet scalograms but the present results show that the task is a very promising one.
