An X-ray tube spectra measuring method is presented in this paper. The measurement is accomplished by reconstruction from attenuation data based on a nine-parameter tungsten anode X-ray spectral model. The proposed mo...
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ISBN:
(纸本)0819461857
An X-ray tube spectra measuring method is presented in this paper. The measurement is accomplished by reconstruction from attenuation data based on a nine-parameter tungsten anode X-ray spectral model. The proposed model is derived from a physical basis and composed of three parts: bremsstrahlung spectra, photoemission attenuation by X-ray tube inherent and added filter, characteristic radiations denoted by four Dirac delta functions. Firstly, for simplicity, the four characteristic radiations of the spectra model are merged into two according to a reasonable hypothesis. Secondly, the spectra reconstruction based on the modified model is carried out by calculating the model parameters from measured attenuation data. To further improve stability, two kinds of materials are used as the attenuators. Experiments show that this method can reach high precision and is insensitive to the noise in measured attenuation data. From the 10 measured attenuation data (7 from Al, and 3 from Copper) with 5% Poisson noise added, the precision of the reconstructed spectra can reach 98.56% for the 70kVp X-ray tube with tiny characteristic radiation, and 98.24% for the 120kVp X-ray tube with characteristic radiation. Spectrum is the characteristic of X-ray tube and widely used for many purposes. In engineering, the spectrum is mostly reconstructed from attenuation data, which is an ill-posed problem in mathematics. The method we presented with the features of including characteristic radiation, insensitive to noise and demanding fewer attenuation data will help to solve this problem perfectly.
image segmentation is an important research topic in imageprocessing and computer vision community. In this paper, a new unsupervised method for MR brain image segmentation is proposed based on fuzzy c-means (FCM) an...
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The PnP problem is a widely used technique for pose determination in computer vision community,and finding out geometric conditions of multiple solutions is the ultimate and most desirable goal of the multi-solution a...
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The PnP problem is a widely used technique for pose determination in computer vision community,and finding out geometric conditions of multiple solutions is the ultimate and most desirable goal of the multi-solution analysis,which is also a key research issue of the *** this paper,we prove that given 3 control points,if the camera's optical center lies on the so-called“danger cylinder”and is enough far from the supporting plane of control points,the corresponding P3P problem must have 3 positive *** result can bring some new insights into a better understanding of the multi-solution *** example,it is shown in the literature that the solution of the P3P problem is instable if the optical center lies on this danger cylinder,we think such occurrence of triple-solution is the primary source of this instability.
Motivated by the requirements of the present archaeology, we are developing an automated system for archaeological classification and reconstruction of ceramics. This paper shows a method to answer archaeological ques...
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Motivated by the requirements of the present archaeology, we are developing an automated system for archaeological classification and reconstruction of ceramics. This paper shows a method to answer archaeological questions about the manufacturing process of ancient ceramics, which is important to determine the technological advancement of ancient culture. The method is based on the estimation of the profile lines of ceramic fragments, which can also be applied to complete vessels. With the enhancements shown in this paper, archaeologists get a tool to determine ancient manufacturing techniques.
Recently developed Serial Analysis of Gene Expression (SAGE) technology enables us to simultaneously quantify the expression levels of tens of thousands of genes in a population of cells. SAGE is better than Microarra...
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The work presented in this paper mainly focuses on designing a monolithic current-mode boost DC-DC converter with integrated 22V DMOS FET power switch and control circuits. The boost converter operating at fixed frequ...
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The work presented in this paper mainly focuses on designing a monolithic current-mode boost DC-DC converter with integrated 22V DMOS FET power switch and control circuits. The boost converter operating at fixed frequency of 1.6MHz has been fabricated with a 1.5μm Bipolar-CMOS-DMOS (BCD) process. The chip with features of wide input voltage range (2.7V to 14V), high efficiency over large load range (1mA to 500mA), low shutdown current, fast transient response and low power, was designed for mobile power management applications. Besides issues such as technology choice, power switch optimization and ramp compensation, the paper also copes with the monolithic switching noise in switching power IC circuits.
In this paper, we employ the concept of characteristic line to show some useful properties of planar homography matrix. These properties relate the characteristic line of a planar homography matrix with Euler angles o...
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A new Fuzzy ART neural network model based on dual competition and resonance technique is proposed. This new model takes the competition and resonance method of the input nodes into the output nodes, putting the input...
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In the past decades, most object recognition systems were based on passive approaches. But in the last few years a lot of research was done in the field of active object recognition. In this context, there are several...
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We present a method that partitions a single image into two layers, requiring that one layer has similar properties in terms of pixel colour variation to a provided template patch. First the paper provides a new view ...
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ISBN:
(纸本)1904410146
We present a method that partitions a single image into two layers, requiring that one layer has similar properties in terms of pixel colour variation to a provided template patch. First the paper provides a new view on defining a similarity function for a pixel with its small neighbourhood to be part of the texture described by the template patch. This results in better description of pixels near the texture boundary. Second, it is shown how the Maximally Stable Extremal Regions (MSERs), originally designed for wide baseline stereo matching, can be used to locally merge pixels having the same intensity and thus reduce the dimension of the graph representing the image. The MSERs help in texture description and yield significant reduction of memory and computation time. Finally the graph is fed into the ***/*** algorithm to cut the graph into two parts. Performance of the method is presented on some images from the Berkeley database. Finally, restrictions in using the method are discussed.
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