The hard-disk storage industry is at a critical time as the current technologies are incapable of achieving densities beyond 500 Gb/in2, which will be reached in a few years. Many radically new storage architectures have been proposed, which along with advanced signal processing algorithms are expected to achieve much higher densities. In this dissertation, various signal processing algorithms are developed to improve the performance of current and next-generation magnetic storage systems.Low-density parity-check (LDPC) error correction codes are known to provide excellent performance in magnetic storage systems and are likely to replace or supplement currently used algebraic codes. Two methods are described to improve their performance in such systems. In the first method, the detector is modified to incorporate auxiliary LDPC parity checks. Using graph theoretical algorithms, a method to incorporate maximum number of such checks for a given complexity is provided. In the second method, a joint detection and decoding algorithm is developed that, unlike all other schemes, operates on the non-binary channel output symbols rather than input bits. Though sub-optimal, it is shown to provide the best known decoding performance for channels with memory more than 1, which are practically the most important.This dissertation also proposes a ternary magnetic recording system from a signal processing perspective. The advantage of this novel scheme is that it is capable of making magnetic transitions with two different but predetermined gradients. By developing optimal signal processing components like receivers, equalizers and detectors for this channel, the equivalence of this system to a two-track/two-head system is determined and its performance is analyzed. Consequently, it is shown that it is preferable to store information using this system, than to store using a binary system with inter-track interference. Finally, this dissertation provides a number of insights into the unique characteristics of heat-assisted magnetic recording (HAMR) and two-dimensional magnetic recording (TDMR) channels. For HAMR channels, the effects of laser spot on transition characteristics and non-linear transition shift are investigated. For TDMR channels, a suitable channel model is developed to investigate the two-dimensional nature of the noise.

We study and analyze the performance of iterative equalization and decoding (IED) using an M-BCJR equalizer. We use bit error rate (BER), frame error rate simulations and extrinsic information transfer (EXIT) charts to study and compare the performances of M-BCJR and BCJR equalizers on precoded and non-precoded channels. Using EXIT charts, the achievable channel capacities with IED using the BCJR, M-BCJR and MMSE LE equalizers are also compared. We predict the BER performance of IED using the M-BCJR equalizer from EXIT charts and explain the discrepancy between the observed and predicted performances by showing that the extrinsic outputs of the $M$-BCJR algorithm are not true logarithmic-likelihood ratios (LLR's). We show that the true LLR's can be estimated if the conditional distributions of the extrinsic outputs are known and finally we design a practical estimator for computing the true LLR's from the extrinsic outputs of the M-BCJR equalizer.

This thesis presents two contributions in the area of high speed clock and data recovery systems. These contributions are focused on the fast phase recovery and adaptive equalization techniques. The first contribution of this thesis is an adaptive engine for a 2x blind sampling receiver. The proposed adaptation engine is able to find the phase-dependent DFE coefficients of the receiver on the fly. The second contribution is a burst-mode clock and data recovery architecture which uses an analog phase interpolator. The proposed burst-mode CDR is capable of locking to the first data transition it receives. The phase interpolator uses the inherent timing information in the data transition to rotate the phase of a reference clock and align it with the incoming data edge. The feasibility of the concept is demonstrated through fabrication and measurements.

We present an alternative method of extracting production related differences from time-lapse seismic data sets. Our method is not based on the actual subtraction of the two data sets, risking the enhancement of noise and introduction of artifacts due to local phase rotation and slightly misaligned events. Rather, it mutes events of the monitor survey with respect to the baseline survey based on the magnitudes of coefficients in a sparse and local atomic decomposition. Our technique is demonstrated to be an effective tool for enhancing the time-lapse signal from surveys which have been cross-equalized

In this thesis, new precoding and equalization techniques for multicarrier systems were proposed and analyzed.First, the error performance of precoded filterbank multicarrier (FBMC) systems was analyzed. It was found out that this performance is highly sensitive to complete subchannel equalization. When there is residual intersymbol interference (ISI) stemming from imperfect subchannel equalization there is a loss of diversity; this loss can be prevented with the adoption of a number of subchannels large enough so that each subchannel suffers flat fading or with the utilization of a subchannel equalizer with sufficient length to compensate the subchannel frequency response.After that, an approximation for the signal to interference-plus-noise ratio (SINR) distribution of SC-FDE systems using linear MMSE equalization was proposed. This approximation uses the lognormal distribution with the smallest Kullback-Leibler distance to the true distribution, and was shown to be precise in the error performance sense; it serves as a system abstraction. With this abstraction, a precise method to obtain the analytical coded error performance of these systems was proposed.Finally, widely linear Tomlinson-Harashima precoders and equalizers (linear and decision-feedback) for SC-FDE systems were proposed. These precoders and equalizers have better error performance when compared to their strictly linear versions if signals coming from an improper constellation are transmitted. Their error performance when decision-feedback equalizers are used is less sensitive to the length of the feedback filter. When widely linear precoders are used, this error performance becomes less sensitive to channel estimation errors.

Axicons have been proposed for imaging applications since they offer the advantage of extended depth of field (DOF). This enhanced DOF comes at the cost of degraded image quality. Image processing has been proposed to improve the image quality. Initial efforts were focused on the use of an axicon in a borescope thereby extending depth of focus and eliminating the need for a focusing mechanism. Though promising, it is clear that image processing would lead to improved image quality. This would also eliminate the need, in certain applications, for a fiber optic imaging bundle as many modern day video borescopes use an imaging sensor coupled directly to the front end optics. In the present work, three types of refractive axicons are examined: a linear axicon, a logarithmic axicon and a Fresnel axicon. The linear axicon offers the advantage of simplicity and a significant amount of scientific literature including the application of image restoration techniques. The Fresnel axicon has the advantage of compactness and potential low cost of production. As no physical prior examples of the Fresnel axicons were available for experimentation until recently, very little literature exists. The logarithmic axicon has the advantage of nearly constant longitudinal intensity distribution and an aspheric design producing superior pre-processed images over the aforementioned elements. Point Spread Functions (PSFs) for each of these axicons have been measured. These PSFs form the basis for the design of digital image restoration filters. The performance of these three optical elements and a number of restoration techniques are demonstrated and compared.

Historically, educator post provisioning in South African public schools has been a / Thesis (Ph.D.) - University of Kwazulu-Natal, 2005.

Social discourses and gender equality policies in South Africa has enabled the entry of significant numbers of women into predominantly male domains of educational leadership. In this study, the lived experiences, of four women heads of department in four historically race classified schools in the Durban Metropolitan area, are explored. This study probes the gendered experiences, in which, race and class are inextricably interwoven, as heads of department in commerce and questions the extent to which their leadership positions are a reflection of gender equality. Based on semi-structured interviews with the research participants (black, coloured, Indian and white), this study argues that despite occupying the status of head of department the research participants still assume gender subjective roles. Although, some evidence exists of changing patterns of these women's lives at different stages, the study reveals that the public and private spheres of work and family are not separate entities; they intersect and impinge, with particular implications for the position of women within the sphere of education leadership. The study reveals that despite an overarching discourse of gender equality, discourses of leadership are primarily about gender, race and class structure in the lived experiences of the participants. The gendered experiences overall was such that they inhibited these women from applying for further promotion. In effect, the study shows that these women, irrespective of being educated and occupying positions of leadership, are still in a state of subjugation and male domination. / Thesis (M.Ed.) - University of Durban-Westville, 2002.

The study explores barriers to learning and development experienced by learners at a rural school situated in Upper Tongaat, on the North Coast of KwaZulu-Natal. Qualitative research methodology, which took the form of a case study, was used. The barriers to learning that the learners at the school experienced were examined from the perspective of both the learners and teachers. Other social factors that may affect a learner's development such as poverty, poor health and poor living conditions were also explored. The data was gathered through semi-structured interviews and participant observation. Although policy documents such as the White Paper on Education and Training (1995) and the South African Schools Act (1996) emphasize the provision of quality basic education for all learners, the study found that learners at this rural school continue to be marginalized. Factors in this schooling context, such as the poor physical environment, overcrowded classrooms, inadequate teaching resources, lack of ongoing professional development, and socio-economic factors such as poverty and poor health care, impede access to the curriculum. The major challenge at the school is how areas such as school organization, ethos, curriculum, teacher development and community involvement can be improved so that the barriers to learning and development can be overcome. / Thesis (M.Ed.)-University of Natal, 1998.

Gender inequality, gender oppression and sexism are a violation of human rights. Gender inequality and sexism is a consequence of the power imbalance between men and women. A significant body of research exists on gender and education. Research on gender equality has commonly focused on boys and education, academic performance, masculinity studies, as well as identity formation of adolescent boys. With the emphasis on gender equality and the curriculum implementation, my interest was evoked in terms of engaging boys to achieve gender equality. Given that any work towards social justice requires working with both the oppressed and the oppressor to raise consciousness, identify and name oppression, improve and change attitudes and beliefs, much research on gender oppression and sexism has focused on girls’ experiences. In order to engage men and boys, we need to understand their perceptions of gender, gender equality and sexism and the extent to which they resist or entrench hegemonic masculinity and patriarchal positioning. While many studies focus on women and women’s movements to achieve gender equality, this study acknowledges the significant role that men and boys can play in achieving gender equality. Understanding boys’ perceptions and attitudes towards women and girls is crucial in adopting strategies to interrupt gender oppression. My aim in this study was therefore to investigate the attitudes, beliefs and perceptions of young men regarding gender, gender equality and sexism. Focusing on the role that men and boys can play in the achievement of gender equality will not only benefit women and girls, as well as men and boys, but also contribute effectively to the achievement of human rights and the promotion of democracy. I have adopted a qualitative approach to obtain a rich interpretation and description of the young men’s perceptions. This study concluded that while the majority of participants aligned themselves with the dominant discourse of masculinity, there were the minority divergent voices that valued alternative forms of masculinity. They valued equality for women and girls, and challenged both cultural and traditional norms, indicating a desire to relate to women and girls in non-oppressive ways. These voices need to be encouraged as a viable strategy to promote gender equality. / Thesis (M.Ed.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.