نتایج جستجو برای: scatter
تعداد نتایج: 12375 فیلتر نتایج به سال:
Many high performance applications spend considerable timepacking data into contiguous communication buffers. Datatypesprovide an alternative by describing the layout of the communi-cated data. This empowers the runtime system to retrieve non-contiguous elements directly from application data structures.However, programmers find complex datatypes hard to use andare reluc...
Scatter search is an evolutionary method that shares with genetic algorithms, a well-known evolutionary approach, the employment of a combination method that combines the features of two parent vectors to form several offspring. Furthermore, it uses improvement strategies to efficiently produce the local tuning of the solutions. An important aspect concerning scatter search is the trade-off bet...
OBJECTIVE The aim of this study was to evaluate the effect of scatter and attenuation correction in region of interest (ROI) analysis in brain perfusion single-photon emission tomography (SPECT) and to assess the influence of selecting the reference area on semi-quantification. METHODS Ten normal subjects were enrolled and injected with 123I-iodoamphetamine to undergo simultaneous emission an...
In the flat panel detector-based cone beam CT system, the scatter photons which reach the flat panel detector increase the detected signal, produce the image cupping artifact and reduce the image contrast. To conquer the X-Ray scatter problem, this study proposes the beam attenuation grid -based scatter correction algorithm that needs to add a beam attenuation grid (BAG) between the X-Ray sourc...
In this paper, a reformative scatter difference discriminant criterion (SDDC) with fuzzy set theory is studied. The scatter difference between between-class and within-class as discriminant criterion is effective to overcome the singularity problem of the within-class scatter matrix due to small sample size problem occurred in classical Fisher discriminant analysis. However, the conventional SD...
It is well known that direct effects of seed predators or dispersers can have strong effects on seedling establishment. However, we have limited knowledge about the indirect species interactions between seeds of different species that are mediated by shared seed predators and/or dispersers and their consequences for plant demography and diversity. Because scatter-hoarding rodents as seed disper...
Cone-beam computed tomography (CBCT) images suffer from poor image quality, in a large part due to contamination from scattered X-rays. In this work, a Monte Carlo (MC)-based iterative scatter correction algorithm was implemented on measured phantom data acquired from a clinical on-board CBCT scanner. An efficient EGSnrc user code (egs_cbct) was used to transport photons through an uncorrected ...
INTRODUCTION One of the important input factors in the commissioning of the radiotherapy treatment planning systems is the phantom scatter factor (Sp) which requires the same collimator opening for all radiation fields. In this study, we have proposed an analytical method to overcome this issue. METHODS The measurements were performed using Siemens Primus Plus with photon energy 6 MV for fiel...
Fisher linear discriminant analysis (FLDA) $nds a set of optimal discriminating vectors by maximizing Fisher criterion, i.e., the ratio of the between scatter to the within scatter. One of its major disadvantages is that the number of its discriminating vectors capable to be found is bounded from above by C-1 for C-class problem. In this paper for binary-class problem, we propose alternative FL...
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