This thesis analyzes the process of deblurring of degraded images generated by space-variant nonlinear image systems with Gaussian observation noise. The restoration of blurred images is performed by using two methods / a modified version of the Optimum Decoding Based Smoothing Algorithm and the Bootstrap Filter Algorithm which is a version of Particle Filtering methods. A computer software called MATLAB is used for performing the simulations of image estimation. The results of some simulations for various observation and image models are presented.

In this thesis, various pilot symbol aided channel estimation and tracking methods are investigated and their performances are compared for an OFDM system with packet based communication on HF channel. For the HF channel, Watterson HF channel model is used. The compared methods are least squares (LS) channel estimation, linear minimum mean square error (LMMSE) channel estimation, least mean squares (LMS) channel tracking, recursive least squares (RLS) channel tracking, constant position model based Kalman filter channel tracking, and constant velocity model based Kalman filter channel tracking. For LMS and RLS methods some adaptive approaches are also investigated.

Implementation aspects of Advanced Encryption Standard (AES) Contest finalist algorithms (MARS, RC6, RIJNDAEL, SERPENT and TWOFISH) are studied on TMS320C54X processor. The C codes written by Brian Gladman in 1999 are adapted to TMS320C54X and the speed and memory usage values are compared with the adaptation of Karol Gorski and Michal Skalski&rsquo / s implementation in 1999. The effects of implementation environment are investigated by comparing the two implementations. The sensitivities of the finalist algorithms to plaintext, key and key length variations together with the possible reasons are studied and scrutinized. Three of the algorithms, MARS, RC6 and RIJNDAEL, are implemented on the same platform by using the assembler language. The results show that assembler implementations are improved with respect to C implementations 13% for MARS, 16-20% for RIJNDAEL and 21-28% for RC6.

Wideband and dual band stacked microstrip patch antennas are investigated for the new wideband and dual band applications in the area of telecommunications. In this thesis, aperture-coupled stacked patch antennas are used to increase the bandwidth of the microstrip patch antenna. By this technique, antennas with 51% bandwidth at 6.1 GHz and 43% bandwidth at 8 GHz satisfying S11&lt / -15 dB are designed, manufactured and measured. A dual-band aperture coupled stacked microstrip patch antenna operating at 1.8 GHz with 3.8% bandwidth and at 2.4 GHz with 1.6% bandwidth is designed, produced and measured for mobile phone and WLAN applications. In addition, an aperture coupled stacked microstrip patch antenna which operates at PCS frequencies in 1.7-1.95 GHz band is designed. Dual and circularly polarized stacked aperture coupled microstrip patch antennas are also investigated. A triple band dual polarized aperture coupled stacked microstrip patch antenna is designed to operate at 900 MHz, at 1.21 GHZ and at 2.15 GHz. Mutual coupling between aperture coupled stacked microstrip patch antennas are examined and compared with the coupling of aperture coupled microstrip patch antennas

Terrestrial Digital Video Broadcasting (DVB-T) is a standard for wireless broadcast of MPEG-2 video. DVB-T is based on channel coding algorithms and uses Orthogonal Frequency Division Multiplexing (OFDM) as a modulation scheme. In this thesis, we have implemented the standard of ETSI EN 300 744 for Digital Video Broadcasting in MATLAB. This system is composed of the certain blocks which include OFDM modulation, channel estimation, channel equalization, frame synchronization, error-protection coding, to name a few of such blocks. We have investigated the performance of the complete system for different wireless broadcast impairments. In this performance analysis, we have considered Rayleigh fading multi-path channels with Doppler shift and framing synchronization errors and obtained the bit error rate (BER), and channel minimum square error performances versus different maximum Doppler shift values, different channel equalization techniques and different channel estimation algorithms. Furthermore, we have investigated different interpolations methods for the interpolation of channel response. It is shown that minimum mean-square error (MMSE) type equalization has a better performance in symbol estimation compared to zero forcing (ZF) equalizer. Also linear interpolation in time and low pass frequency interpolation, for time frequency interpolation of channel response can be used for practical application.

Since direct-sequence code-division multiple-access (DS-CDMA) is an interference-limited random multiple-access scheme, the reduction of co-channel interference with either interference suppression or interference cancellation multiuser receivers and/or power control to prevent detrimental near-far situations is vital for improved performance. Up to date, some contributions investigated randomly-spread asymptotically - large number of users and large bandwidth - large CDMA systems with multiuser receivers and power control via random matrix theoretic and free probability theoretic tools especially over Gaussian and single-path fading channels. As complement within this thesis, we analyze also within the generalized random spreading framework but at finite system sizes and without power control the capacity achievable with linear multichannel multiuser receivers / i.e. RAKE, zero-forcing decorrelator, linear minimum mean-squared error (LMMSE) multiuser receivers, within a single-cell setting over generalized time-varying GWSSUS - Rayleigh/Ricean - fading channels via random matrix theoretic tools. Assuming maximal-ratio combining (MRC) of resolved frequency - multipath - diversity channels due to wideband transmission, the signal-to-interference ratios (SIRs) with multichannel multiuser receivers that set the basis for further derivations are statistically characterized. The information-theoretic ergodic and outage sum-rates spectral efficiencies are then derived and analyzed.

This dissertation studies the impact of the mode of data collection on the quality of answers to survey questions, defined as the product of reliability and validity. Using data from the Netherlands about different topics (media, social and political trust, satisfaction, political orientation, left-right self-placement, attitudes toward immigration), it shows that the quality is similar in a computed assisted face-to-face survey using show cards (the European Social Survey, ESS) and a web survey based on a probability sample (the LISS panel). This is true both at the level of single items and composite scores. It suggests that standardised relationships across variables can be compared across these two modes. On the contrary, telephone interviews lead to some differences in quality. For complex concepts, measurement equivalence also holds, meaning that means and unstandardised relationships can be compared across the faceto- face and web surveys mentioned previously. / Esta tesis estudia el impacto que el método de recolección de datos en encuestas tiene sobre la calidad de las respuestas, definida como el producto de la fiabilidad y la validez. Utilizando datos de Holanda sobre temas diversos (utilización de los medios de comunicación, confianza social y política, satisfacción, orientaciones políticas, autoubicación en la escala izquierda-derecha, actitudes hacia la inmigración), se muestra que la calidad es similar en una encuesta cara-a-cara asistida con ordenador y utilizando tarjetas (la Encuesta Social Europea) y una encuesta online basada en una muestra probabilística (el panel LISS). Esto se cumple tanto para los indicadores simples, como para indicadores complejos. Los resultados sugieren que las relaciones estandardizadas entre variables son comparables entre los dos métodos de recolección. Al contrario, las entrevistas telefónicas producen diferencias de calidad. Para conceptos complejos, la equivalencia de las mediciones también está garantizada: las medias y las relaciones no estandarizadas son comparables en las entrevistas cara-a-cara y online.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Diss. (sammanfattning) Umeå : Univ., 2004. / Härtill 5 uppsatser.

Thesis (M.P.H.)--University of Texas Health Science Center at Houston, School of Public Health, 2007. / Source: Masters Abstracts International, Volume: 46-01, page: 0339. Adviser: Cynthia L. Chappell. Includes bibliographical references.