• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 153
  • 37
  • 23
  • 13
  • 11
  • 6
  • 5
  • 5
  • 4
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 299
  • 70
  • 48
  • 47
  • 45
  • 44
  • 44
  • 39
  • 35
  • 33
  • 30
  • 30
  • 27
  • 26
  • 26
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Cross section measurement of simultaneously produced Υ(1S) + J/Ψ mesons and upgrade studies for the CMS detector

Dilsiz, Kamuran 01 January 2016 (has links)
A measured cross section of simultaneously produced Υ(1S) and J/ψ mesons is performed using 20 fb-1 integrated luminosity in proton-proton collisions at √s=8 TeV center of mass energy recorded by the CMS detector. Both mesons are fully reconstructed from their final states, μ+ μ-. To extract the signal yield, an extended maximum likelihood fit is used on two (invariant mass of Υ(1S) and J/ψ) and three (invariant mass of Υ(1S) and J/ψ, cτ) dimensional components. A two-dimensional extended likelihood fit is used for the signal yield of data and a three-dimensional extended likelihood fit is used to know the possibility of displaced J/ψ candidate events arising from a B meson decay. A data embedding method is used to correct the efficiency in the data. The cross section in the fiducial region, defined as |y|<2.0, is determined to be 16.5±3.6(stat)±2.6(syst) pb. In order to improve the physics measurements capabilities for the harsh radiation environments at Large Hadron Collider (LHC), radiation hard detectors are needed. Secondary Emission Method (SEM) is a technique to measure the energy of particles such as e, n, and p in extreme radiation environments. Secondary Emission Ionization Calorimetry is a new technique for high radiation conditions. We designed two different types of test boards to test Hamamatsu single anode R7761 and multi-anode R5900-00-M16 PMTs and compared average gain values for both SE and PMT modes. We found that both values (SE and PMT) were comparable, which means the test boards that were developed perform very well and they could be used at Fermilab Test Beam Facility or in the CERN H2 beam area for the detection of minimum ionizing and showering particles.
32

Current Programmed Active Pixel Sensors for Large Area Diagnostic X-ray Imaging

Safavian, Nader 28 August 2009 (has links)
Rapid progress over the last decade on large area thin film transistor (TFT) arrays led to the emergence of high-performance, low-power, low-cost active matrix flat panel imagers. Despite the shortcomings associated with the instability and low mobility of TFTs, the amorphous silicon TFT technology still remains the primary solution for the backplane of flat panel imagers. The use of a-Si:H TFTs as the building block of the large area integrated circuit becomes challenging particularly when the role of the TFT is extended from traditional switching applications to on-pixel signal amplifier for large area digital imaging. This is the idea behind active pixel sensor (APS) architectures in which under each pixel an amplifier circuit consisting of one or two switching TFTs integrated with one amplifying TFT is fabricated. To take advantage of the full potential of these amplifiers, it is crucial to develop APS architectures to compensate for the limitations of the TFTs. In this thesis several APS architectures are designed, simulated, fabricated, and tested addressing these challenges using the mask sets presented in Appendix A. The proposed APS architectures can compensate for inherent stabilities of the comprising TFTs. Therefore, the sensitivity of their output data to the transistor variations is significantly suppressed. This is achieved by using a well defined external current source instead of the traditional voltage source to reset the APS architectures during the reset cycle of their periodic operation. The performance of these circuits is analyzed in terms of their stability, settling time, noise, and temperature-dependence. For appropriate readout of the current mode APS architectures, high gain transresistance amplifiers with correlated double sampling capability is designed, simulated and fabricated in CMOS technology. Measurement and measurement based calculation results reveal that the proposed APS architectures can meet even the stringent requirements of low noise, real-time digital fluoroscopy.
33

Color Segmentation using LVQ-Learning Vector Quantization

Jabbar, Hussain January 2010 (has links)
This thesis aims to present a color segmentation approach for traffic sign recognition based on LVQ neural networks. The RGB images were converted into HSV color space, and segmented using LVQ depending on the hue and saturation values of each pixel in the HSV color space. LVQ neural network was used to segment red, blue and yellow colors on the road and traffic signs to detect and recognize them. LVQ was effectively applied to 536 sampled images taken from different countries in different conditions with 89% accuracy and the execution time of each image among 31 images was calculated in between 0.726sec to 0.844sec. The method was tested in different environmental conditions and LVQ showed its capacity to reasonably segment color despite remarkable illumination differences. The results showed high robustness.
34

Current Programmed Active Pixel Sensors for Large Area Diagnostic X-ray Imaging

Safavian, Nader 28 August 2009 (has links)
Rapid progress over the last decade on large area thin film transistor (TFT) arrays led to the emergence of high-performance, low-power, low-cost active matrix flat panel imagers. Despite the shortcomings associated with the instability and low mobility of TFTs, the amorphous silicon TFT technology still remains the primary solution for the backplane of flat panel imagers. The use of a-Si:H TFTs as the building block of the large area integrated circuit becomes challenging particularly when the role of the TFT is extended from traditional switching applications to on-pixel signal amplifier for large area digital imaging. This is the idea behind active pixel sensor (APS) architectures in which under each pixel an amplifier circuit consisting of one or two switching TFTs integrated with one amplifying TFT is fabricated. To take advantage of the full potential of these amplifiers, it is crucial to develop APS architectures to compensate for the limitations of the TFTs. In this thesis several APS architectures are designed, simulated, fabricated, and tested addressing these challenges using the mask sets presented in Appendix A. The proposed APS architectures can compensate for inherent stabilities of the comprising TFTs. Therefore, the sensitivity of their output data to the transistor variations is significantly suppressed. This is achieved by using a well defined external current source instead of the traditional voltage source to reset the APS architectures during the reset cycle of their periodic operation. The performance of these circuits is analyzed in terms of their stability, settling time, noise, and temperature-dependence. For appropriate readout of the current mode APS architectures, high gain transresistance amplifiers with correlated double sampling capability is designed, simulated and fabricated in CMOS technology. Measurement and measurement based calculation results reveal that the proposed APS architectures can meet even the stringent requirements of low noise, real-time digital fluoroscopy.
35

Development of High Accuracy 2-D Inspection Software

Hung, Tzu-Yu 15 August 2000 (has links)
The CCD sensors have the advantage for small size clear image and low prices, It is the image capture unit of computer-vision system which developed fast in the past years, especially in the 2-D image capture CCD sensors are better then another sensors, so in the industry it be used on products detection . There are two different sections on using CCD sensors to detect products,the first section is about the detection of what kind of objects amount of objects and position of objects, the second section is about looking for lines ¡Bcircles ¡Bareas of objects¡Bdiameter¡Bcircularity and the angles between two lines The research purpose is finding a high accuracy algorithmic with low complicacy and high accuracy conditions; the accuracy can reach the sub-pixel accuracy with low price facilities and high speed .
36

Μέθοδοι ανάλυσης των περιεχομένων εικονοστοιχείων

Εγγλεζοπούλου, Βαρβάρα 13 November 2008 (has links)
Στην παρούσα εργασία γίνεται ανάλυση της διαδικασίας subpixel spectral unmixing. Η διαδικασία αυτή αρχικά αναπτύχθηκε για εφαρμογές δορυφορικών εικόνων, με την εξέλιξη της τεχνολογίας βρήκε σημαντικές εφαρμογές και σε άλλους τομείς όπως η ιατρική. Η τιμή ενός Pixel αντιστοιχεί στην τιμή του φάματος σε μία συγκεκριμένη ζώνη. Η τιμή αυτή συνήθως συνίσταται από ένα σύνολο τιμών του φάσματος που αντιστοιχούν σε χαρακτηριστικά (είδη επίγειας καλύψης). Με τη διαδικασία Pixel unmixing πραγματοποιείται ο διαχωρισμός των ειδών αυτών και ταυτόχρονα υπολογίζονται οι αναλογίες κάθε είδους σε κάθε pixel. Στην εργασία αυτή παρούσιάζονται: α) οι βασικές αρχές που διέπουν το ηλεκτρομαγνητικό φάσμα, β) οι διαδιασίες ταξινόμησης αντικειμένων, γ) βασικές αρχές τηλεπισκόπησης, δ) ανάπτυξη της πολυφασματικής ανάλυσης και τέλος ε)ανάπτυξη της γραμμικής διαδικασίας pixel unmixing και πειραματικές εφαρμογές σε matlab 6.5. / ----
37

COMMERCIALIZATION AND OPTIMIZATION OF THE PIXEL ROUTER

Dominick, Steven James 01 January 2010 (has links)
The Pixel Router was developed at the University of Kentucky with the intent of supporting multi-projector displays by combining the scalability of commercial software solutions with the flexibility of commercial hardware solutions. This custom hardware solution uses a Look Up Table for an arbitrary input to output pixel mapping, but suffers from high memory latencies due to random SDRAM accesses. In order for this device to achieve marketability, the image interpolation method needed improvement as well. The previous design used the nearest neighbor interpolation method, which produces poor looking results but requires the least amount of memory accesses. A cache was implemented to support bilinear interpolation to simultaneously increase the output frame rate and image quality. A number of software simulations were conducted to test and refine the cache design, and these results were verified by testing the implementation on hardware. The frame rate was improved by a factor of 6 versus bilinear interpolation on the previous design, and by as much as 50% versus nearest neighbor on the previous design. The Pixel Router was also certified for FCC conducted and radiated emissions compliance, and potential commercial market areas were explored.
38

Pixelating Vector Art

Inglis, Tiffany C. January 2014 (has links)
Pixel art is a popular style of digital art often found in video games. It is typically characterized by its low resolution and use of limited colour palettes. Pixel art is created manually with little automation because it requires attention to pixel-level details. Working with individual pixels is a challenging and abstract task, whereas manipulating higher-level objects in vector graphics is much more intuitive. However, it is difficult to bridge this gap because although many rasterization algorithms exist, they are not well-suited for the particular needs of pixel artists, particularly at low resolutions. In this thesis, we introduce a class of rasterization algorithms called pixelation that is tailored to pixel art needs. We describe how our algorithm suppresses artifacts when pixelating vector paths and preserves shape-level features when pixelating geometric primitives. We also developed methods inspired by pixel art for drawing lines and angles more effectively at low resolutions. We compared our results to rasterization algorithms, rasterizers used in commercial software, and human subjects---both amateurs and pixel artists. Through formal analyses of our user study studies and a close collaboration with professional pixel artists, we showed that, in general, our pixelation algorithms produce more visually appealing results than na\"{i}ve rasterization algorithms do.
39

Algorithmic geometry via graphics hardware

Denny, Markus Oswald. Unknown Date (has links) (PDF)
University, Diss., 2003--Saarbrücken.
40

Subpixel-Filterung für eine autostereoskopische Multiperspektiven-3-D-Darstellung hoher Qualität

Müller, Dirk. Unknown Date (has links)
Universiẗat, Diss., 2006--Kassel.

Page generated in 0.1106 seconds