For high resolution radar, the echoes of target come from several points rather than one point as in low resolution radar. In this case the target is called an extended target. This paper presents two CFAR detectors f...For high resolution radar, the echoes of target come from several points rather than one point as in low resolution radar. In this case the target is called an extended target. This paper presents two CFAR detectors for such a target in non Gaussian clutter, which are CA CFAR and OS CFAR detectors. The detection performances of the two detectors are evaluated.展开更多
AIM： To compare high resolution colonoscopy （Olympus Lucera） with a megapixel high resolution system （Pentax HiLine） as an in-service evaluation. METHODS： Polyp detection rates and measures of performance were c...AIM： To compare high resolution colonoscopy （Olympus Lucera） with a megapixel high resolution system （Pentax HiLine） as an in-service evaluation. METHODS： Polyp detection rates and measures of performance were collected for 269 colonoscopy procedures. Five colonoscopists conducted the study over a three month period, as part of the United Kingdom bowel cancer screening program. RESULTS：There were no differences in procedure duration （x^2 p = 0.98）, caecal intubation rates （x^2 P = 0.67）, or depth of sedation （x^2 P = 0.64）. Mild discomfort was more common in the Pentax group （x^2 p = 0.036）. Adenoma detection rate was significantly higher in the Pentax group （x^2 test for trend P = 0.01）. Most of the extra polyps detected were flat or sessile adenomas. CONCLUSION： Megapixel definition colonoscopes improve adenoma detection without compromising other measures of endoscope performance. Increased polyp detection rates may improve future outcomes in bowel cancer screening programs.展开更多
The application of terahertz（THz） technique in many fields like petroleum industry requires the high resolution and multifunction to realize the precise detection of different materials. In this study water vapor in...The application of terahertz（THz） technique in many fields like petroleum industry requires the high resolution and multifunction to realize the precise detection of different materials. In this study water vapor in atmosphere was scanned with shortand long-path THz spectrometers with different scan ranges. The full width at half maximum of the THz characteristic lines in long-path system reached less than 7 GHz and that in short achieved -5.5 GHz, indicating that the THz spectroscopy of water vapor can be used to calibrate THz devices. THz systems with right scan ranges could be a promising selection for the identification of solid, liquid and gaseous materials with very similar structures due to the high resolution. The research demonstrates that the multifunctional THz test can be realized through the balance of resolution and sampling space in many fields, such as oil-gas industry.展开更多
The three-dimensional structure of mesoscale eddies in the western tropical Pacific(6°S–20°N, 120°E–150°E)is investigated using a high-resolution ocean model simulation. Eddy detection and eddy t...The three-dimensional structure of mesoscale eddies in the western tropical Pacific(6°S–20°N, 120°E–150°E)is investigated using a high-resolution ocean model simulation. Eddy detection and eddy tracking algorithms are applied to simulated horizontal velocity vectors, and the anticyclonic and cyclonic eddies identified are composited to obtain their three-dimensional structures. The mean lifetime of all long-lived eddies is about 52 days, and their mean diameter is 147 km. Two typical characteristics of mesoscale eddies are revealed and possible dynamic explanations are analyzed. One typical characteristic is that surface eddies are generally separated from subthermocline eddies along the bifurcation latitude(~13°N) of the North Equatorial Current in the western tropical Pacific, which may be associated with different eddy energy sources and vertical eddy energy fluxes in subtropical and tropical gyres. Surface eddies have maximum swirl velocities of 8–9 cm s^(-1) and can extend to about 1500 m depth. Subthermocline eddies occur below 200 m, with their cores at about 400–600 m depth, and their maximum swirl velocities can reach 10 cm s^(-1). The other typical characteristic is that the meridional velocity component of the eddy is much larger than the zonal component. This characteristic might be due to more zonal eddy pairs(two eddies at the same latitude),which is also supported by the zonal wavelength(about 200 km) in the high-frequency meridional velocity component of the horizontal velocity.展开更多
文摘For high resolution radar, the echoes of target come from several points rather than one point as in low resolution radar. In this case the target is called an extended target. This paper presents two CFAR detectors for such a target in non Gaussian clutter, which are CA CFAR and OS CFAR detectors. The detection performances of the two detectors are evaluated.
基金Supported by Proportion of UCLH/UCL funding from the Department of Health’s NIHR Biomedical Research Centres funding schemeA grant from the UCL experimental cancer medicine centreUnrestricted educational grant support from Pentax United Kingdom (Lovat LB)
文摘AIM： To compare high resolution colonoscopy （Olympus Lucera） with a megapixel high resolution system （Pentax HiLine） as an in-service evaluation. METHODS： Polyp detection rates and measures of performance were collected for 269 colonoscopy procedures. Five colonoscopists conducted the study over a three month period, as part of the United Kingdom bowel cancer screening program. RESULTS：There were no differences in procedure duration （x^2 p = 0.98）, caecal intubation rates （x^2 P = 0.67）, or depth of sedation （x^2 P = 0.64）. Mild discomfort was more common in the Pentax group （x^2 p = 0.036）. Adenoma detection rate was significantly higher in the Pentax group （x^2 test for trend P = 0.01）. Most of the extra polyps detected were flat or sessile adenomas. CONCLUSION： Megapixel definition colonoscopes improve adenoma detection without compromising other measures of endoscope performance. Increased polyp detection rates may improve future outcomes in bowel cancer screening programs.
基金supported by the National Basic Research Program of China(Grant No.2014CB744302)the Specially Funded Program on National Key Scientific Instruments and Equipment Development(Grant No.2012YQ140005)+1 种基金the National Natural Science Foundation of China(Grant Nos.6140525911204191&11574401)
文摘The application of terahertz（THz） technique in many fields like petroleum industry requires the high resolution and multifunction to realize the precise detection of different materials. In this study water vapor in atmosphere was scanned with shortand long-path THz spectrometers with different scan ranges. The full width at half maximum of the THz characteristic lines in long-path system reached less than 7 GHz and that in short achieved -5.5 GHz, indicating that the THz spectroscopy of water vapor can be used to calibrate THz devices. THz systems with right scan ranges could be a promising selection for the identification of solid, liquid and gaseous materials with very similar structures due to the high resolution. The research demonstrates that the multifunctional THz test can be realized through the balance of resolution and sampling space in many fields, such as oil-gas industry.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41576014 & 41330963)the National Basic Research Program of China (Grant No. 2013CB956202)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA11010101)the National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers (Grant No. U1406401)
文摘The three-dimensional structure of mesoscale eddies in the western tropical Pacific(6°S–20°N, 120°E–150°E)is investigated using a high-resolution ocean model simulation. Eddy detection and eddy tracking algorithms are applied to simulated horizontal velocity vectors, and the anticyclonic and cyclonic eddies identified are composited to obtain their three-dimensional structures. The mean lifetime of all long-lived eddies is about 52 days, and their mean diameter is 147 km. Two typical characteristics of mesoscale eddies are revealed and possible dynamic explanations are analyzed. One typical characteristic is that surface eddies are generally separated from subthermocline eddies along the bifurcation latitude(~13°N) of the North Equatorial Current in the western tropical Pacific, which may be associated with different eddy energy sources and vertical eddy energy fluxes in subtropical and tropical gyres. Surface eddies have maximum swirl velocities of 8–9 cm s^(-1) and can extend to about 1500 m depth. Subthermocline eddies occur below 200 m, with their cores at about 400–600 m depth, and their maximum swirl velocities can reach 10 cm s^(-1). The other typical characteristic is that the meridional velocity component of the eddy is much larger than the zonal component. This characteristic might be due to more zonal eddy pairs(two eddies at the same latitude),which is also supported by the zonal wavelength(about 200 km) in the high-frequency meridional velocity component of the horizontal velocity.
