En este trabajo se ha fabricado un equipo de medida que combina la alta temperatura con transmisión óptica, utilizando el espectro de emisión de un LED comercial de bajo coste de adquisición.A partir de las medidas de transmisión óptica se ha obtenido el coeficiente de absorción y a través de este conocer la temperatura del substrato de c-Si:Así como para conocer los mecanismos fundamentales que intervienen en el proceso de la absorción óptica (Banda a banda y Cargas libres). Se ha ampliado el modelo teórico de calculo del coeficiente de absorción para ajustar las medidas echas con el espectro de emisión de un LED.El equipo construido se ha empleado para monitorizar in-situ la fase de cristalización de las capas de a-SiCx:H intrínsecas y dopadas con fósforo depositadas sobre substrato de c-Si. Los resultados obtenidos se han comparando con otras medidas ópticas que involucran técnicas diferentes: SEM, X-RD, FTIR, Monocromador, que confirman los resultados encontrados.

This masters thesis investigates the possibility to estimate the ethanol content in the fuel using ion currents. Flexible fuel cars can be run on gasoline-ethanol blends with an ethanol content from0 to 85 percentage. It is important for the engine control system to have information about the fuel. In todays cars the measurements of the fuel blend are done by a sensor. If it is possible to do this with ion currents this can be used to detect if the sensor is broken, and then estimate the ethanol content until the sensor gets fixed. The benefit of using ion currents is that the signal is measured directly from the spark plug and therefore no extra hardware is needed. To be able to see how the ethanol ratio affects the ion currents, the dependencies of the operating point have been investigated. This has been done by a literature review and by measurements in a Saab 9-3. Engine speed, load, ignition timing, lambda and spark plugs effects on the ion currents are especially studied. A black box model for the ion currents dependence on operating point is developed. This model describes the engine speed, load and ignition timing dependencies well, but it can not be used to estimate the ethanol ratio.

Emission from cars today is one of the biggest environmental issues, hence stringent government standards have been introduced to decrease emission. Car companies do not only have to satisfy government standards, but also meet consumer demands on increased fuel economy and good drivablility. This report will introduce controllers designed to control the air/fuel ratio in an SI engine. The engine model used is simplified. The engine components modelled include the inlet manifold, fuel dynamics, combustion and exhaust sensor. Nonlinearities and delays are inherent in the engine dynamics and as such a Smith Predictor is utilised as the basis for controller structure to compensate for the delays. Here the Smith Predictor is combined with feedforwarding of the mass air charge, which is estimated from both the inlet and combustion models. Therefore different ways of merging the estimates are also explored. A real engine was not accesible, thus simulators were implemented using data sets provided by General Motors. Model errors were introduced to test the controllers performance. The proposed methods should be tested on a real engine to ensure that this isa viable approach, as the simulations show it maybe promising to use in practice.

Ion current sensing, where information about the combustion process in an SI-engine is gained by applying a voltage over the spark gap, is currently used to detect and avoid knock and misfire. Several researchers have pointed out that information on peak pressure location and air/fuel ratio can be gained from the ion current and have suggested several ways to estimate these parameters. Here a simplified Bayesian approach was taken to construct a lowpass-like filter or estimator that makes use of prior information to improve estimates in crucial areas. The algorithm is computationally light and could, if successful, improve estimates enough for production use. The filter was implemented in several variants and evaluated in a number of simulated cases. It was found that the proposed filter requires a number of trade-offs between variance, bias, tracking speed and accuracy that are difficult to balance. For satisfactory estimates and trade-off balance the prior information must be more accurate than was available. It was also found that similar a task, constructing a general Bayesian estimator, has already been tackled in the area of particle filtering and that there are promising and unexplored possibilities there. However, particle filters require computational power that will not be available to production engines for some years. / Vid jonströmsmätning utvinns information om förbränningsprocessen i en bensinmotor genom att en spänning läggs över gnistgapet och den resulterande strömmen mäts. Jonströmsmätning används idag för knack- och feltändningsdetektion. Flera forskare har påpekat att det finns än mer information i jonströmmen, bl.a. om bränsleblandningen och cylindertrycket och har även föreslagit metoder för att utvinna och använda den informationen för skattning av dessa parametrar. Här presenteras en förenklad Bayesisk metod i form av en lågpassfilter-liknande skattare som använder förkunskap till att förbättra estimat på relevanta områden. Algoritmen är beräkningsmässigt lätt och kan, om den är framgångsrik, leverera skattningar av förbränningsparametrar som är tillräckligt bra för att användas för sluten styrning av en bensinmotor. Skattaren, eller filtret, implementerades i flera varianter och utvärderades i ett antal simulerade fall. Resultaten visade på att flera svåra avvägningar måste göras mellan förbättring i varians, avvikelse och följning eftersom förbättring i den ena ledde till försämring i de andra. För att göra dessa avvägningar och få goda skattningar krävs bättre förhandskunskap och mätdata än vad som var tillgängligt. Bayesisk skattning är ett stort befintligt område inom statistik och signalbehandling och den mest generella skattaren är partikelfiltret som har många intressanta tillämpningar och möjligheter. De har hittills inte använts inom skattning av förbränningsparametrar och har således go potential för framtida utveckling. De är dock beräkningsmässigt tunga och kräver beräkningsresurser utöver vad som är tillgängliga i ett motorstyrsystem idag.

The goal of this work is to extend the state-of-the-art in digital medical X-ray imaging as it pertains to real-time, low-noise imaging and multi-mode imager functionality. One focus of this research in digital flat-panel imagers is to increase the detective quantum efficiency, particularly at low X-ray exposures, in order to enable low-noise imaging applications such as fluoroscopy or tomographic mammography. Another focus of this research is in the creation of a multi-mode imager, such as a combined radiographic and fluoroscopic (R&F) imager, which will reduce hospital costs, both in terms of equipment acquisition and storage space. To that end, we propose a novel three-transistor multi-mode digital flat-panel imager with a dynamic range capable for use in R&F applications, with a particular focus on noise optimization for low-noise real-time digital flat-panel X-ray fluoroscopy. This work involves the derivation and optimization of the total input referred noise of an active pixel sensor (APS) in terms of the on-pixel thin-film transistor device dimensions. It is determined that in order to minimize noise, all non-transistor capacitances at the pixel sense node needed to be minimized. This leads to a design where the on-pixel storage capacitance is eliminated; and instead the gate capacitance of the sense-node transistor is used to store the incoming X-ray converted charge. This work allows researchers to gain insight into the fundamental noise operation of active pixels used in medical imaging, and to appropriately choose device dimensions. Due to the inherent large feature sizes of thin-film transistors, active pixel flat-panel X-ray medical imagers offer lower resolution than their film-screen counterparts. By demonstrating the desirability of smaller device dimensions for reduced noise and the elimination of a storage capacitor, this research frees some of the area constraints that exist in active pixel flat-panel imagers, allowing for smaller pixels, and thus higher resolution medical imagers. The noise analysis and optimization as a function of pixel TFT device dimensions in this work is applicable to any amorphous silicon (a-Si) based charge-sensitive pixel, and is easily extended to other device technologies such as polysilicon (poly-Si). iv In addition, experimental results of a 64x64 pixel four-transistor APS imaging array fabricated in a-Si technology and mated with an a-Se photoconductor for use in medical X-ray imaging is presented. MTF results and transient response in the presence of X-rays (image lag) for the APS array are poor, which is ascribed to high charge trapping at the silicon nitride/a-Se interface. Improvements to the silicon nitride passivation layer and pixel layout are suggested to reduce this charge trapping. The prototype imager is compared directly with a state-of-the-art a-Si PPS imaging array and demonstrates good SNR performance for X-ray exposures down to 1.5μR. Pixel design and fabrication process improvements are suggested for low-exposure APS testing and improved low-noise performance.

Microstructural evolution in a naturally-aged and cold-rolled AA6451 aluminum alloy during a non-isothermal annealing process, which leads to significant grain refinement, is investigated through: (a) conducting a comprehensive experimental analysis and (b) developing a computational modeling technique. The underlying mechanisms of annealing have been investigated through analysing interactive phenomena between precipitation and concurrent recovery and recrystallization. It is shown that the interactions between solute elements, clusters, and fine precipitates with dislocations restrict dynamic and static recovery during deformation and subsequent annealing. Inhibition of recovery favours recrystallization that initiates at 300oC and progresses through a nucleation and growth mechanism. Despite localized inhomogeneities, nucleation mainly occurs in non-recovered high energy sites which are uniformly distributed within the entire structure. Growth of the recrystallized nuclei is restricted by pinning precipitates that undergo a concurrent coarsening process. The fine, uniform distribution of recrystallized nuclei and their limited growth result in the formation of a fine-grained microstructure, after completion of recrystallization. The acquired knowledge has been used to develop a computational modeling technique for simulating microstructural evolution of the alloy. Microstructural states are simulated by integrating analytical approaches in a Monte Carlo algorithm. The effects of deformation-induced and pre-existing inhomogeneities, as well as precipitate coarsening and grain boundary pinning on the competitive recovery-recrystallization process are included in the simulation algorithm. The developed technique is implemented to predict the microstructural evolution during isothermal and non-isothermal annealing of AA6xxx sheets. A good quantitative agreement is found between the model predictions and the results from the experimental investigations.

The Severity of Renal Disease Scale (SORDS) was developed to provide a single score reflecting disease severity of renal patients independent of confounding psychosocial influences. This study examined SORDS' reliability and validity and its relevance as a research tool assessing the psychological effect of illness severity. Data was collected from 127 renal patients (predialysis, HD, CAPD). SORDS was compared with the Endstage Renal Disease Severity Index (ESRD-SI), the SF-36, the Beck Depression Inventory - 2nd Edition and a subset of BDI-II items reflecting cognitive features only at differing stages of renal disease and time on dialysis. SORDS and ESRD-SI data from twenty-two CAPD patients was included in reliability analyses. SORDS reliability estimates were low suggesting that the use of SORDS with medical chart data at this time is problematic. SORDS should be used only by medical practitioners who are aware of patients' standing on SORDS variables. There was however strong support for SORDS' validity. Validity was demonstrated by correlations between SORDS and the ESRD-SI. Compared to the ESRD-SI, SORDS was better able to discriminate between dialysis and pre-dialysis patients. SORDS and ESRD-SI scores were related to self-perceptions of decreased health status on the SF-36 independent of dialysis duration and age. SORDS utility in psychosocial research with renal patients was demonstrated by a finding that disease severity differentially impacts levels of depression for HD versus CAPD patients independent of age or dialysis duration. At the lowest level of illness severity as assessed by SORDS, CAPD patients scored in the moderate range of depression and were significantly more depressed than HD patients. Using the same analyses but with the ESRD-SI, no differences in level of depression were detected. These results imply a relationship between adjustment to treatment and illness severity. It is concluded that SORDS is a valid index of renal disease severity and that illness severity as assessed by SORDS may have an important role as a moderator variable in psychosocial research with renal patients. These results may have important implications for treatment assignment and psychosocial assessment and intervention of renal patients and their families.

A fully integrated optical chem/bio sensor complete with integrated source, chemically sensitive waveguide, detector arrays, and associated signal processing electronics on a Si-CMOS chip is a challenging, but highly desirable goal. An evanescent-wave multimode interferometric sensing element is a sensitive method for sensing, which is easily integrated on Si-CMOS. This work is concerned with the design, analysis, and demonstration of a planar multimode interferometric chem/bio sensor that is compatible with the fabrication constraints of Si-CMOS. A 4000-micron-long interferometric that can be adapted for different agents by a particular sensing layer has been fabricated on silicon using silicon dioxide and silicon oxynitride. Hexaflouro-isopropanol substituted polynorbornene is the sensing layer. This sensor has also been fabricated on a Si-CMOS circuit with embedded photodetectors. A sensor on silicon was demonstrated with a minimum detectable index change of 2.0x10-6 using an accurate gas delivery system and a custom hermetic waveguide test chamber. A modal pattern analysis strategy has also been developed to extract the optimal SNR from the measured modal patterns. An understanding of the noise processes and spatial bandwidth effects has enabled an experimentally-based prediction of the index sensitivity of a fully integrated multimode chem/bio sensor on Si-CMOS at 9.2 x10-7. Theoretically, the sensitivity enhancement of high over low index sensing layers and transverse-magnetic over transverse electric modes is described. Also, the sensitivity enhancement of higher-order-transverse modes has been quantified. The wide-angle beam propagation method has been used to simulate the sensor. This simulation showed the relation between the modal pattern repetition period and sensor sensitivity. Further, the modal coupling properties of the multimode y-junction have been described. A second multimode y-junction has been designed to change the modal excitation under the SL, and thus the sensitivity. The chemo-optic response of the `substituted polynorbornene' polymer., hexaflouro-isopropanol substituted polynorbornene to methanol, water, iso-propanol, and benzene has been measured. Also, its thermo-optic response has been measured. Athermal interferometric chem/bio sensors have then been suggested.

The purpose of the thesis is to investigate the improvement of single-crystal Si solar cell efficiency using porous Indium tin oxide (ITO)/ITO double layer antireflection(AR) coating. The resistivity, transmittance and refraction index of the porous ITO films prepared by supercritical CO2 treatment were investigated. At a 2000 psi pressure and 60¡CC, the resistivity of porous ITO films is 15 £[-cm, the average transmittance is better than 95 %, and the refraction index is 1.54. In addition, the resistivity of ITO thin films fabricated by reactive ratio-frequency magnetron sputtering is 7¡Ñ10-4 £[-cm, the average transmittance are 85 %, and the refraction index is 2.0. For the single crystal-Si solar cell with porous ITO/ITO double layer AR coating, the open circuit voltage, short circuit current, fill factor and efficiency are measured.

Reverberation is the phenomenon when the sound source transmits and causes scattering in active sonar system. This kind of effects often produced in the waveguide, resulting signal interference and signal mask issues. Reverberation can affect the signal to noise ratio, thus understanding the characteristic of environmental reverberation is important. In recent years, there were many studies for the Sizihwan Bay Marine Test Field (MTF), including environmental surveys, Harbor defense and acoustic inversion, however the issue related to reverberation has not been explored. The purpose of this study is to research reverberation in the MTF and focusing on volume reverberation and surface reverberation. In the past, the experiment of Underwater Intruder Detection with active sonar system demonstrated the reverberation in Kaohsiung second harbor. Therefore, this research is about using the experimental data to questions about volume reverberation. Results show, volume reverberation in the port area caused by ship, boundaries, current, impurities in water and biota. On the other hand surface reverberation, this study focusing on numerical simulation, match the results of experimental. Numerical results of RMS height, correlation length and frequency affect the reverberation intensity, but it does not identify the phenomenon of reverberation in experimental results, mainly is the intensity of the source is not enough. This study combined with simulation and experiment, and overviewed the reverberation properties in MTF. Also provided suggestions for following studies.