This study attempts to develop a method for absolute quantitation in Positron Emission Tomography. This includes the definition of the dimension and the position of a tumour in the brain as well as the evaluation of the amount of drug delivered to the tumour and to surrounding tissues in a pixel-by-pixel way, from the image. The defined objectives can be achieved using the calibrated FWHM values of the distribution of events in the tumour image, versus distance, to determine the dimension and the position of the tumour. The concentration activity in the tumour and the tumour-to-nontumour activity ratios can be obtained from the image, using a modified filter and the calibration of the tomograph. The colour scale of the image can be expressed in absolute units (μCi/ml) and the concentration activity can be evaluated in each pixel of the image or in each volume element of the body. / Thesis / Master of Science (MS)

Encryption, digital signature and digital watermark are three popular methods to prevent a wide variety of multimedia products from illegal copy or subterfuge attacks. In particular, digital watermarking recently draws a lot of attention since it hides desirable information in transmitted audio, image and video data files without affecting much the data quality. The thesis proposes two watermarking methods for audio and image data. And both watermarking methods embed watermark signals in the spatial/time domain using a so-call Pixel Weight Table. The experiment results shows that the two methods have good performance. In addition, I propose a guantitive measuring method, called APSNR, to characterize the audio perceptual transparency.

CMOS active pixel sensors (APS) have shown competitive performance with charge-coupled device (CCD) and offer many advantages in cost, system power reduction and on-chip integration of VLSI electronics. Among CMOS image sensors, sensors with logarithmic pixels are particularly applicable for outdoor environment where the light intensity varies over a wide range. They are also randomly accessible in both time and space. A major drawback comes from process variations during fabrication. This gives rise to a considerable fixed pattern noise (FPN) which deteriorates the image quality. In this thesis, a technique that greatly reduces FPN using on-chip calibration is introduced. An image sensor that consists of 64x64 active pixels has been designed, fabricated and tested. Pixel pitch is 18um x 19.2um? and is fabricated in a 0.5-um? CMOS process. The proposed pixel circuit considerably reduces the FPN as predicted in theoretical analysis. The measured FPN value is 2.29% of output voltage swing and column-wise FPN is 1.49% of mean output voltage over each column.

New generation of Flat Panel Displays, Organic Light Emitting Diode (OLED) with fast response, high brightness, high contrast plays an important role gradually in the further market of flat penal display (FPD). The characteristics of OLED like as bright light¡Bthin¡Bshort¡Bsmall subverts the concept of LCD displays. But the life time of organic materials become the obstruction on the further development of OLED-FPD. In addition, the non-uniformity of OLED Panel could cause the quality of frames worse. Hence, for solve the problem, A more powerful Pixel driving circuit will be designed for achieving the high performance of OLED based FPD. Recently, many researches were related to the compensating pixel driving circuits have reported. The catalogs of pixel driving circuits were divided into two types as voltage-driving circuit and current-driving circuit, which were used to solve the problems like the variation of the threshold voltage, the electronic mobility and the long time with storing capacitors charge and discharge. In this study, a novel pixel driving circuit with new discharged paths was design in order to solve the long time of charge and discharge. Theoretical and circuit simulation show this design can enhance the frame rates effectively. At the same time, it also achieves better performance such as higher resolution and quality of frame rate for the large size OLED panels.

CMOS active pixel sensors (APS) have shown competitive performance with charge-coupled device (CCD) and offer many advantages in cost, system power reduction and on-chip integration of VLSI electronics. Among CMOS image sensors, sensors with logarithmic pixels are particularly applicable for outdoor environment where the light intensity varies over a wide range. They are also randomly accessible in both time and space. A major drawback comes from process variations during fabrication. This gives rise to a considerable fixed pattern noise (FPN) which deteriorates the image quality. In this thesis, a technique that greatly reduces FPN using on-chip calibration is introduced. An image sensor that consists of 64x64 active pixels has been designed, fabricated and tested. Pixel pitch is 18um x 19.2um? and is fabricated in a 0.5-um? CMOS process. The proposed pixel circuit considerably reduces the FPN as predicted in theoretical analysis. The measured FPN value is 2.29% of output voltage swing and column-wise FPN is 1.49% of mean output voltage over each column.

The objective of this study was to evaluate the sensitivity of instantaneous latent heat flux (LE) estimation from Surface Energy Balance Algorithm for Land (SEBAL) by changing hot/cold pixel selections. The SEBAL model was programed in a Matlab environment and applied to Lower Fox Watershed in northeast Illinois using two Landsat 5 Thematic Mapper images acquired in summer 2006. Unlike most previous studies where hot/cold pixel were manually selected by image analysts, we emphasized an automated hot/cold pixel selection based on land cover map, normalized difference vegetation index (NDVI) map, and land surface temperature (LST) map. Various combinations of hot/cold pixels were automatically selected along the LST gradient. The LE estimations were then validated against ground-based eddy covariance observation. Results show that the LE estimations from SEBAL were sensitive to both hot and cold pixel selections and tend to be more sensitive to cold pixel selection. The absolute percentage difference (APD) of LE estimation compared with field observation data can range from 0.67% to 67.2% by varying hot and cold pixel combinations. The location of hot/cold pixels appears to have minor impact on SEBAL LE estimation. The LE estimation become acceptable (APD < 10%) when using the hot/cold pixels with a slightly higher/lower LST than LST extremes from the study area. This study provides insights into hot/cold pixel selection and the sensitivity of SEBAL-based LE estimation. Future research on SEBAL ET estimation should focus on enhancing automated hot/cold pixel selection algorithm to improve the model's operational use. / Master of Science

Målen i matematikämnesplanen uttrycks som matematiska förmågor, vilka eleverna ska få möta i undervisningen. Till de matematiska förmågorna räknas problemlösningsförmåga, metodförmåga, begreppsförmåga, kommunikationsförmåga, och resonemangsförmåga. Läroböckerna i matematik har en väldigt styrande roll och om undervisningen till största delen ska utgå från det som står i böckerna är det viktigt att veta vad de innehåller och vilka kunskaper eleverna får när de arbetar i dem. Syftet med den här undersökningen är att analysera matematikläromedlet Pixel, för att se hur pass stora möjligheter eleverna har att utveckla de fem matematiska förmågorna, listade i LGR 11, när de använder sig av böckerna. Syftet är också att studera om läromedlet till största delen bygger på färdighet eller förståelse. Med anledning av att det inte har forskats så mycket om elevers möjligheter att utveckla de matematiska förmågorna när de använder olika läromedel, är motivet för den här studien att fylla den kunskapsluckan. Analysen visar att eleverna har stora möjligheter att utveckla de fem matematiska förmågorna, listade i LGR 11, när de använder sig av läromedlet Pixel, framförallt begreppsförmågan och metodförmågan. För att eleverna ska utveckla de övriga förmågorna bör läraren ha en aktiv roll och använda sig av de tips och extra aktiviteter som finns i lärarhandledningen, samt ge eleverna utrymme till att diskutera och resonera om olika metoder och lösningar.

The PIXEL method has been used for several years to analyse intermolecular interactions in organic crystals. The simplicity and speed of the calculations, along with the breakdown of intermolecular energies into physical contributing terms, mean that it has had a massive influence on the way organic crystal structures are interpreted. In the work done to date, the parameters required to perform a PIXEL calculation have been established for 1st, 2nd and 3rd row transition metals. Using these parameters, lattice energies of several transition metal complexes containing various chemical environments have been calculated and compared to experimental sublimation enthalpies. Straight line parameters for these results have been comparable to work by Gavezzotti, the author of the program, in testing the method for organic crystal structures. In addition to lattice energies, PIXEL gives dimer interaction energies of molecules in a crystal structure. The values of these interactions have been compared to single point DFT energy calculations. PIXEL has shown good agreement with a range of different intermolecular interactions, along with a significant saving in computer time over the higher level calculations. Aside from four empirical parameters, PIXEL requires only fundamental atomic properties such as ionisation potentials, electronegativities and van der Waals radii. For the most part, these values are obtained from standard reference tables and texts with the exception of atomic polarizabilities. This parameter is of great importance as it is used during the calculation of the dispersion term, an interaction which has a major influence on crystal packing. In previous work, atomic polarizabilities have been calculated using either the Slater-Kirkwood approximation or the Clausius-Mossotti relation. Both of these methods are rather simple, and do not account for possible changes in atomic polarizability resulting from differences in chemical environment. The Atoms in Molecules (AIM) approach has been used to attempt to obtain a range of polarizability values for atoms common to organic chemistry. It is observed that in the series of straight chained primary monoamines, Cn-H2n+3N, an alternation in melting points occurs between odd and even values of n. This alternation could be traced to differences in hydrogen-bonding and chain-packing that occur between odd and even-membered amines. Molecular interaction energy calculations were carried out using the PIXEL method, enabling quantitative energetic analysis of the packing differences. In this work, the crystal structures of the primary amines from ethylamine to decylamine were solved for the first time. All of these compounds are liquids at room temperature, so crystals were grown in situ by laser-assisted zone refinement at 10 K below their melting points. Diffraction data were then collected at 150 K. From propylamine to decylamine, all crystal structures are orthorhombic (or pseudo-orthorhomic) with the unit cell dimensions ~5 Ǻ x ~7 Ǻ x c Ǻ, where c increases with chain length. In the case of ethylamine, a phase characterised by single crystal diffraction at 180 K underwent a transition to a different phase on cooling to 150 K. The low-temperature phase was investigated using powder methods.

Global shutter pixels are indispensable for applications wherein the minimisation of motion artefacts is of critical importance. However, these pixels are more complex than the common rolling shutter type pixels and require some form of per-pixel storage. They are almost invariably reliant upon metal light shielding in order to protect their in-pixel memory nodes and this prevents them from taking advantage of some of the latest developments in CMOS image sensor technology. Backside-illumination is the most prominent example of such a technology. The greater sensitivity afforded by the reduced optical stack height is indispensable for many applications, particularly in the mobile market where form factor and power consumption are constrained. The design challenge is to exploit these advantages offered by backside-illumination without making use of metal shielding of the per-pixel memory. The research in this thesis covers the design, implementation and characterisation of a back-illuminated voltage-domain global shutter pixel. The pixel architecture is a novel 10 transistor-per-pixel architecture with dual independent in-pixel storage nodes. Beginning with the pixel architecture, the design is developed through TCAD-driven photodiode and pixel layout co-optimisation. The behaviour of pixels with differential parasitic light sensitivity (PLS) behaviour is analysed in greater detail than previously reported and a prediction model is developed based upon this. The 10T pixel is characterised and found to have excellent PLS of -73:5 dB native and -82:5 dB differential PLS at 940 nm. The dual in-pixel storage enables the pixel to operate either in a low noise correlated double sampling mode with differential PLS, or in an exposure-bracketed high dynamic range imaging (HDR) mode. This HDR mode is successfully demonstrated and yields substantial enhancement of the pixel dynamic range.

No description available.