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在压力容器的超声检测中,为解决传统相控阵(PA)二维成像存在缺陷图像畸变,难以准确定性等问题,采用1种基于全聚焦法(TFM)的实时超声成像技术,使用一维线阵和二维面阵分别对孔等典型实际缺陷进行扫查,获得缺陷的二维和三维图像,从定量角度对比分析2者的准确度。结果表明:该方法获得的三维图像测量误差在8%以内,具有更高的精确度和检出率,对于孔类缺陷的还原度更高,这对于缺陷检测与评估以及和特种设备的安全生产具有重要意义。 相似文献
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Monitoring Plant Phenology Using Digital Repeat Photography 总被引:1,自引:0,他引:1
Repeated observations of plant phenology have been shown to be important indicators of global change. However, capturing the
exact date of key events requires daily observations during the growing season, making phenologic observations relatively
labor intensive and costly to collect. One alternative to daily observations for capturing the dates of key phenologic events
is repeat photography. In this study, we explored the utility of repeat digital photography for monitoring phenologic events
in plants. We provide an illustration of this approach and its utility by placing observations made using repeat digital imagery
in context with local meteorologic and edaphic variables. We found that repeat photography provides a reliable, consistent
measurement of phenophase. In addition, digital photography offers advantages in that it can be mathematically manipulated
to detect and enhance patterns; it can classify objects; and digital photographs can be archived for future analysis. In this
study, an estimate of greenness and counts of individual flowers were extracted by way of mathematic algorithms from the photo
time series. These metrics were interpreted using meteorologic measurements collected at the study site. We conclude that
repeat photography, coupled with site-specific meteorologic measurements, could greatly enhance our understanding environmental
triggers of phenologic events. In addition, the methods described could easily be adopted by citizen scientists and the general
public as well as professionals in the field. 相似文献
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Monitoring effects of a controlled subsurface carbon dioxide release on vegetation using a hyperspectral imager 总被引:1,自引:0,他引:1
Charlie J. Keith Kevin S. Repasky Rick L. Lawrence Steven C. Jay John L. Carlsten 《International Journal of Greenhouse Gas Control》2009,3(5):626-632
A hyperspectral imaging system was used to monitor vegetation during a subsurface controlled release of carbon dioxide (CO2). From August 3 to 10, 2007, 0.3 tons CO2/day were released through a 70 m horizontal pipe located at a nominal depth of 1.8 m below the surface. Hyperspectral images of alfalfa plants were collected during the controlled release and used along with classification tree analysis to study changes in the reflectance spectra as a function of perpendicular distance from the horizontal pipe. Changes in the reflectance spectra near the red edge (650–750 nm) were observed over the course of the controlled release experiment for plants within a perpendicular distance of 1 m of the release pipe. These results indicate monitoring vegetation over a carbon sequestration site has the potential to allow monitoring of the integrity of the CO2 storage. 相似文献
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Sun-Kwon Kim Hye-Sung Won Shin Wha Lee Jeong Kon Kim Jae-Yoon Shim Pil Ryang Lee Ahm Kim 《黑龙江环境通报》2006,26(2):171-174
Congenital epulis is a benign intraoral tumor that has rarely been diagnosed prenatally. We report a fetus with congenital epulis diagnosed by three-dimensional (3-D) ultrasound and fetal magnetic resonance imaging (MRI) at 35 weeks' gestation. We show an image of congenital epulis using a new ultrasound technique, the 3-D multislice view, which shows images similar to CT or MRI. This is a short case report of congenital epulis diagnosed prenatally by 3-D ultrasound using multislice view and MRI. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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The antenatal ultrasound diagnosis of renal tract abnormalities is now firmly established. Postnatal imaging protocols are constantly evolving and still many questions remain unanswered. Most infants are asymptomatic at birth and aggressive imaging is unwarranted both for the infant and overburdened Radiology departments. The urgency with which to undertake imaging relates to the suspected antenatal diagnosis and clinical scenario, with bilateral hydronephrosis, posterior urethral valves and complicated duplex systems taking a high priority. The main imaging modality postnatally remains ultrasound, and together with nuclear medicine gives a powerful combination of both anatomy and function. Intravenous urography is never indicated in the neonate. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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