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1.
The authors briefly report their experience regarding the opportunities offered by the use of current ultrasound methods in carotid surgery. They describe: a system for the quantification of athcromasic plaque used to monitor non-operated patients over time; ultrasound methods used to analyse the carotid wall to establish whether it can be utilised as an index of vascular aggression in hypertension, diabetes and atherosclerosis; the use of transcranial Doppler; criteria for the definition of high risk plaque; the applications of eco-color Doppler. The paper also illustrates a new pathology identified by the authors, defined as primary intimal fibrous hyperplasia, and the evolution of the carotid wall after endarterectomy. The structural characteristics of primary hyperplasia can only be shown using ultrasound given that arteriography cannot distinguish it from atheromatic stenosis. After endarterectomy the carotid wall is subject to hematic and hemodynamic stimuli which determine the type of evolution of the wall itself. The authors therefore examine the myointimal reaction, myointimal hyperplasia, early restenosis and late restenosis as different facets of the same phenomenon.  相似文献   
2.
Oil spill detection by satellite remote sensing   总被引:13,自引:0,他引:13  
This paper presents the state of the art for oil spill detection in the world oceans. We discuss different satellite sensors and oil spill detectability under varying conditions. In particular, we concentrate on the use of manual and automatic approaches to discriminate between oil slicks and look-alikes based on pattern recognition. We conclude with a discussion of suggestions for further research with respect to oil spill detection systems.  相似文献   
3.
Oil Spill Detection in Radarsat and Envisat SAR Images   总被引:8,自引:0,他引:8  
We present algorithms for automatic detection of oil spills in synthetic aperture radar (SAR) images. The algorithms consist of three main parts, namely: 1) detection of dark spots; 2) feature extraction from the dark spot candidates; and 3) classification of dark spots as oil spills or look-alikes. The algorithms have been trained on a large number of Radarsat and Envisat Advanced Synthetic Aperture Radar (ASAR) images. The performance of the algorithm is compared to manual and semiautomatic approaches in a benchmark study using 59 Radarsat and Envisat images. The algorithms can be considered to be a good alternative to manual inspection when large ocean areas are to be inspected  相似文献   
4.
New techniques in charged particle therapy and widespread use of modern dynamic beam delivery systems demand new beam monitoring devices as well as accurate 2D dosimetry systems to verify the delivered dose distribution. We are developing dose imaging detectors based on gas electron multipliers (GEM) with the goal of improving dose measurement linearity, position and timing resolution, and to ultimately allow pre-treatment verification of dose distributions and dose delivery monitoring employing scanning beam technology. A prototype 10×10 cm(2) double-GEM detector has been tested in the 205 MeV proton beam using electronic and optical readout modes. Preliminary results with electronic cross-strip readout demonstrate fast response and single-pixel (4 mm) position resolution. In optical readout mode, the line spread function of the detector was found to have σ=0.7 mm. In both readout modes, the detector response was linear up to dose rates of 50 Gy/min, with adequate representation of the Bragg peak in depth-dose profile measurements.  相似文献   
5.
This study examined how pain coping efficacy and pain coping strategies were related to reports of pain during mammography. Subjects were 125 women over the age of 50 undergoing screening mammograms. Prior to their mammogram, all subjects completed the Coping Strategies Questionnaire (CSQ) to assess how they cope with day-to-day pain experiences. Ratings of pain during the mammogram were collected using a 6-point pain/discomfort scale, a 100-mm Visual Analog Scale, the adjective checklist of the McGill Pain Questionnaire, and the Brief Pain Inventory. Up to 93% of the women reported the mammogram examination was painful. On average, women rated the mammography pain in the low to moderate range. Considerable variability in pain ratings was found, however, with some women reporting severe pain and others reporting little or no pain. Correlational analyses were conducted to examine how coping efficacy (CSQ ratings of ability to decrease pain and ability to control pain) and coping strategies (CSQ pain coping strategy subscales) related to variations in pain report. There was a pattern for ratings of ability to decrease pain to be related to lower ratings of current mammography pain. Women who rated their ability to decrease pain as high reported lower average levels of mammography pain, lower ratings on the mammography pain/discomfort scale, and were much more likely to report having had lower levels of pain during their last mammogram. These findings suggest that women who rate their coping efficacy in decreasing day-to-day pain as low may be at higher risk for having a painful mammogram. Individual pain coping strategies were not generally correlated with pain ratings. Behavioral interventions (e.g., patient controlled breast compression) and cognitive therapy interventions (e.g., training in the use of calming self-statements or distraction techniques) designed to increase coping efficacy potentially could be useful in reducing pain in women who are at risk for pain during mammography.  相似文献   
6.
7.
INTEGRATED SHOP FLOOR CONTROL USING AUTONOMOUS AGENTS   总被引:26,自引:0,他引:26  
In this paper, we present a generic framework for controlling the work flow in computer controlled manufacturing systems. Based on a market-like model and a combination of objective and price mechanism, the framework allows heterogeneous job objectives, admits job priorities, recognizes multiple resources types, and allows multiple step negotiation between parts and resources. The framework is designed to accommodate frequent changes in the environment such as machine failures, tool shortages, and process requirement variations. An object-oriented simulation system is built to demonstrate the flexibility and effectiveness of die proposed framework. The results show that the proposed framework provides a foundation for highly adaptive, real time shop floor control.  相似文献   
8.
To identify the level of compliance with the new radiation protection regulation among Norwegian health care enterprises (HCEs). Totally, 41 HCEs were authorised to use advanced X-ray equipment for medical purposes during 2005-07. Follow-up inspections with 14 HCEs were carried out during 2007-09. Main topics for the inspections were those requirements identified as most challenging to implement in the authorisation process. Totally, 192 non-conformities with the regulation were revealed during the authorisation process. The inspections revealed that 93 % of the inspected HCEs had non-conformities with the regulation. Most common non-conformities dealt with skills in radiation protection, establishment of local diagnostic reference levels, access to medical physicists and performance of quality control of X-ray equipment. Inspections are an effective tool for implementation of regulation the requirements at the HCEs, thus improving radiation protection awareness.  相似文献   
9.
A general model for multisource classification of remotely sensed data based on Markov random fields (MRF) is proposed. A specific model for fusion of optical images, synthetic aperture radar (SAR) images, and GIS (geographic information systems) ground cover data is presented in detail and tested. The MRF model exploits spatial class dependencies (spatial context) between neighboring pixels in an image, and temporal class dependencies between different images of the same scene. By including the temporal aspect of the data, the proposed model is suitable for detection of class changes between the acquisition dates of different images. The performance of the proposed model is investigated by fusing Landsat TM images, multitemporal ERS-1 SAR images, and GIS ground-cover maps for land-use classification, and on agricultural crop classification based on Landsat TM images, multipolarization SAR images, and GIS crop field border maps. The performance of the MRF model is compared to a simpler reference fusion model. On an average, the MRF model results in slightly higher (2%) classification accuracy when the same data is used as input to the two models. When GIS field border data is included in the MRF model, the classification accuracy of the MRF model improves by 8%. For change detection in agricultural areas, 75% of the actual class changes are detected by the MRF model, compared to 62% for the reference model. Based on the well-founded theoretical basis of Markov random field models for classification tasks and the encouraging experimental results in our small-scale study, the authors conclude that the proposed MRF model is useful for classification of multisource satellite imagery  相似文献   
10.
Nickel 201 and Inconel 600 have been creep and corrosion tested in combustion gas and in an inert atmosphere consisting of argon. At constant temperature, nickel exhibited an improved creep resistance in combustion gas relative to that in argon, probably due to a hardening effect caused by the in-diffusion of impurities along creep dislocations. Creep increased the corrosion attacks on nickel due to cracks in the protective surface scale and an enhanced diffusion along dislocations formed during creep. On the other hand, corrosion had a negative influence on the creep properties of Inconel 600. On the basis of the tertiary creep rate this effect could be associated with the formation of large oxide inclusions and cracks beneath the specimen surface. The creep/corrosion properties of the small grained as-received Inconel 600 were considerably improved by a pretreatment giving large grains and a dense dispersion of carbides on grain boundaries and within grains. Generally, it was demonstrated that the creep rate has a stronger influence than the total strain on the corrosion attacks. The deep corrosion attacks during fast creep are entirely creep-induced, and are attributed to crack formation in the protective oxide scale due to the specimen straining. Formerly with Central Institute for Industrial Research, Oslo, Norway  相似文献   
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