Non-linear continuous phase modulation has constant envelope and spectral efficiency, which are desirable for public safety communication systems where both bandwidth and power are limited. A practical design of an innovation based receiver for partial response CPM was recently developed for public safety applications. It is in the form of a linear predictive demodulator with a coefficient look up table. The demodulator shows great performance over multipath fading channels without channel equalization and promises a significant contribution to public safety communication. The work in this thesis is focussed on developing and analyzing modern techniques to improve the receiver performance while maintaining a feasible implementation complexity. Suitable soft output algorithms are incorporated into the demodulator allowing a subsequent convolutional decoder to perform soft decoding. By modifying the design criteria of the predictive demodulator and introducing a feedback loop, an iterative detection scheme is formed for the concatenated structure of demodulator, deinterleaver and decoder. Spatial diversity combining techniques are summarized and a very low complexity combining scheme is developed. It selects the best received sample sequence by considering the average energy of each sequence. In addition, the demodulator is extended to have dual coefficient look up tables supporting its detection by having parallel prediction processes and combining their results. This leads to an improvement in overall demodulator performance. A theoretical proof that only half the number of coefficients need to be stored in memory is also given. Matlab simulations on a Rayleigh fast fading multipath channel have shown that the proposed techniques significantly improve the overall detection accuracy. Each of them provides a good gain in signal to noise ratio or delay spread and when combined, a significant performance gain is achieved.

Deciphering the genetic basis of phenotypic diversity is one of the central aims of biological research. Domestic animals provide a unique opportunity for making substantial progress towards this goal. Intense positive selection has lead to a rich reservoir of phenotypes and underlying genotypes that can be interrogated using genetic tools to gain insight into the genetic basis of phenotypic diversity. The dog is the most phenotypically diverse mammal. It was domesticated from the grey wolf 11-30,000 years ago. After domestication, a period of intense breeding has lead to the massive phenotypic diversity seen amongst dog breeds today. These two phases of strong positive selection at domestication and at breed creation are likely to have left their signature on the genome. In this thesis, we have analysed genome-wide patterns to detect genomic regions involved in selection in both of these phases. We used whole genome sequences from 60 dogs and 12 wolves, to detect dog domestication selective sweeps. We find evidence for genes involved in memory formation, neurotransmission and starch digestion. To decipher the genetic signals underlying breed diversity, we used genome-wide genotype data from >170,000 SNPs in 509 dogs from 46 different breeds. We find evidence for genes under selection in many breeds, and only a few breeds. In addition, we identify novel sweeps underlying morphology and behavior. Recombination can influence the configuration of alleles present on a haplotype, and can thus increase or decrease the efficiency of selection. The PRDM9 protein has been shown to be important for determining recombination hotspot locations in humans and other mammals, but of all the mammals studied so far the dog is the only one to have a non-functional PRDM9. We used the genome-wide genotype data described above to characterise the fine scale recombination map in dogs. We find that recombination hotspots exist in dogs despite the absence of PRDM9. Moreover, we show that these hotspots are enriched for GC rich peaks and that these peaks are getting stronger over time. Our results show that the absence of PRDM9 has lead to the stabilisation of the recombination landscape in dogs.

Due to the attractive advantages of wireless communication technologies, wireless networking and mobile computing has developed expeditiously and gained ample prevalence. Thereby, many practical applications are being designed for the use of wireless ad hoc networks in both military and civilian scenarios. However, some security concerns have arisen from such networks, especially in that misbehaving nodes pose a major threat during the construction of a trusted network. Therefore, security is one of the key challenges in wireless ad hoc networks, requiring significant attention due to their own features and concerns. This thesis presents several computational models and security strategies for the design of secure, trustworthy networks, which are able to make rational decisions when encountering potential threats. In this thesis, we first propose a distributed network management model for secure group communication. Our approach simplifies the complexity of traditional group management and supports the inclusion of other security mechanisms for the purpose of secure communications. As a decentralized management method, trust can perform well in a dynamic and agile environment. Our proposed trust system defines the concept of trust, establishes the trust relationship between distributed nodes, involves the novel and effective computational model, and specifies a set of trust-based rules in this system for wireless nodes. We also propose a hybrid cryptosystem through the application of both symmetric and asymmetric key algorithms to provide reliable and secure protection of data confidentiality. With the design of selective encryption, uncertainty is incorporated into data encryption and the overhead spent on the data protection is significantly reduced. Thus, the communicating parties not only obtain reliable security protection, but also improve the efficiency of data communication. Through security analysis and simulation experiments, we have shown how decentralized management is useful in wireless and ad hoc scenarios, how trust provides feasible solutions for misbehavior detection, and how our proposed strategies offer security properties.

Research focused on the selective laser melting (SLM) of stainless steels and aluminium alloys. For steels, the possibility of creating a magnetically graded material was demonstrated as well as the ability to improve consolidation with austenitic and martensitic stainless steel powder mixtures. Stainless Steel/CoCr hybrid samples were also manufactured and tested to investigate the advantages of functionally graded materials (FGMs). Al alloy research began with examining the requirements for successful Al alloy consolidation in SLM and through experimentation it was found that Al alloys with good welding properties were the best choice: pure Al was found to be completely unsuitable. 6061 Al alloy was then used as a base material to manufacture Al-Cu alloy samples. Single layer SLM samples were produced first, which resulted in recognised Al-Cu microstructures forming. Multilayer Al alloy SLM research resulted in the discovery of the theorised ability to manufacture Al-Cu alloy parts with a nanocrystalline Al matrix with dispersed Al2Cu quasicrystals, resulting in a material comparable to a metal matrix composite that showed excellent corrosion resistance and compressive strength. Finally, a demonstration part was made to test the capability of the SLM process producing an aerospace type geometry using a customised Al alloy. Observations during manufacture and post process analysis showed that Al alloys were susceptible to changes in mechanical properties due to the geometry of the manufactured part.

The subject of this thesis is scattering of electromagneticwaves from planar and curved periodic structures. The problemspresented are solved in the frequency domain. Scattering from planar structures with two-dimensionalperiodic dependence of constitutive parameters is treated. Theconstitutive parameters are assumed to vary continuously orstepwise in a cross section of a periodically repeating cell.The variation along a longitudinal coordinate z is arbitrary. Ageneral skew lattice is assumed. In the numerical examples, lowloss and high loss dielectric materials are considered. Theproblem is solved by expanding the .elds and constitutiveparameters in quasi-periodic and periodic functionsrespectively, which are inserted into Maxwell’s equations.Through various inner products de.ned with respect to the cell,and elimination of the longitudinal vector components, a linearsystem of ordinary di.erential equations for the transversecomponents of the .elds is obtained. After introducing apropagator, which maps the .elds from one transverse plane toanother, the system is solved by backward integration.Conventional thin metallic FSS screens of patch or aperturetype are included by obtaining generalised transmission andre.ection matrices for these surfaces. The transmission andre.ection matrices are obtained by solving spectral domainintegral equations. Comparisons of the obtained results aremade with experimental results (in one particular case), andwith results obtained using a computer code based on afundamentally di.erent time domain approach. Scattering from thin singly curved structures consisting ofdielectric materials periodic in one dimension is alsoconsidered. Both the thickness and the period are assumed to besmall. The .elds are expanded in an asymptotic power series inthe thickness of the structure, and a scaled wave equation issolved. A propagator mapping the tangential .elds from one sideto the other of the structure is derived. An impedance boundarycondition for the structure coated on a perfect electricconductor is obtained. Keywords:electromagnetic scattering, periodicstructure, frequency selective structure, frequency selectivesurface, grating, coupled wave analysis, electromagneticbandgap, photonic bandgap, asymptotic boundary condition,impedance boundary condition, spectral domain method,homogenisation

M.A. / The dissemination of relevant information is of critical importance to the success of any organisation that aims at realising its corporate objectives and meeting the requirements of its stakeholders. The emergence of information and communication technologies (ITCs) has had a far-reaching impact on the relationship and power structure between organisations and their audiences, stakeholders and the media. It has become extremely difficult for organisations to define and segment these audiences as, for example, Internet audiences are widely spread across geographical, cultural and economic boundaries. This makes the packaging and dissemination of information a near Herculean task, as information needs to be generic enough to be commonly understood and accessed, yet personalised and customised in such a way that it still addresses the various audience segmentations effectively. The identification and profiling of target audiences, however, are critical for successful information dissemination too, as the information thus gained will guide communicators within organisations to compile relevant (to the specific target audiences) content and to package the information in such a way that it be best suited to the needs and resources of their target groups. Extensive market research should, therefore, be an integrated organisational activity that is performed on an ongoing basis and in a structured manner. The principal aim of this research project is to determine the extent to which information and communication technologies could enable the Alumni Office of the University of Johannesburg (as a newly merged institution) to disseminate information to its alumni effectively. This target audience consists mainly of the merged partners’ alumni groups, namely the RAU and TWR alumni, but also makes provision for the establishment of a third alumni affinity group in the foreseeable future, namely the alumni of the University of Johannesburg. The research consists of an in-depth literature review, followed by an empirical component. The purpose of the literature review is to create a theoretical framework in order to lay a solid foundation from which to conduct the empirical research. The various components of the research problem are discussed, as well as the variables that could possibly influence the outcome of the research. Next, the possible challenges facing the Alumni Office of the University of Johannesburg are investigated, with special emphasis on RAU and TWR alumni, as these two groups would (at least initially) form the basis of the alumni target audience of the University of Johannesburg. The various information and communication technologies that could be employed as information-dissemination tools by the Alumni Office of the University of Johannesburg in order to build and maintain valuable relationships with the alumni target audience are also explored. Following, the so-called “digital divide” is investigated, with an overview of the factors influencing this divide in South Africa, as well as the impact it may have on disseminating and sharing information to and with alumni of the University of Johannesburg. For the empirical study, the sample population for answering the quantitative, close-ended questionnaire by means of telephonic surveys was selected by means of stratified sampling from the RAU and TWR alumni databases respectively. Three hundred RAU alumni and three hundred TWR alumni were sampled from the total target-group population, of which 25% were males older than 35 years, 25% males 35 years and younger, 25% females older than 35 and 25% females 35 years and younger. The research results indicate that information and communication technologies could, to a large extent, enable the Alumni Office of the University of Johannesburg to disseminate information to its alumni effectively. In addition, it indicates that a total of 92.80% of respondents feel that contact between them and the Alumni Office would inspire greater loyalty towards the University. A majority of alumni (86.80%) indicated that they would like to receive information about the benefits to be derived from joining the Alumni Association of the University. A strong correlation exists between the establishment of an alumni benefits programme and the level of alumni involvement with the University. The research findings could provide the Alumni Office with valuable guidelines to plan and implement an interactive information-communication strategy by means of effective information dissemination, which could be to the mutual benefit of both the University and its alumni.

Nous étudions le problème de l'estimation de moyenne et de la densité prédictive d'une population sélectionnée, en obtenant de nouveaux développements qui incluent l'analyse de biais, la décomposition du risque et les problèmes avec restrictions sur les paramètres (chapitre 2). Nous proposons des estimateurs de densité prédictive efficaces en termes de pertes Kullback-Leibler et Hellinger (chapitre 3) améliorant les procédures de plug-in via une perte duale et via une d'expansion de variance. Enfin, nous présentons les résultats de l'amélioration de l'estimateur du maximum de vraisemblance (EMV) d'une moyenne normale bornée pour une classe de fonctions de perte, y compris la perte normale réfléchie, avec des implications pour l'estimation de densité prédictive. A savoir, nous donnons des conditions sur la perte et la largeur de l'espace paramétrique pour lesquels l'estimateur de Bayes par rapport à la loi a priori uniforme sur la frontière domine la EMV. / Abstract : We study the problem of point estimation and predictive density estimation of the mean of a selected population, obtaining novel developments which include bias analysis, decomposition of risk, and problems with restricted parameters (Chapter 2). We propose efficient predictive density estimators in terms of Kullback-Leibler and Hellinger losses (Chapter 3) improving on plug-in procedures via a dual loss and via a variance expansion scheme. Finally (Chapter 4), we present findings on improving on the maximum likelihood estimator (MLE) of a bounded normal mean under a class of loss functions, including reflected normal loss, with implications for predictive density estimation. Namely, we give conditions on the loss and the width of the parameter space for which the Bayes estimator with respect to the boundary uniform prior dominates the MLE.​

Nelson and Palmer (2007) concluded that figures/figural properties automatically attract attention, after they found that participants were faster to detect/discriminate targets appearing where a portion of a familiar object was suggested in an otherwise ambiguous display. We investigated whether these effects are truly automatic and whether they generalize to another figural property-convexity. We found that Nelson and Palmer's results do generalize to convexity, but only when participants are uncertain regarding when and where the target will appear. Dependence on uncertainty regarding target location/timing was also observed for familiarity. Thus, although we could replicate and extend Nelson and Palmer's results, our experiments showed that figures do not automatically draw attention. In addition, our research went beyond Nelson and Palmer's, in that we were able to separate figural properties from perceived figures. Because figural properties are regularities that predict where objects lie in the visual field, our results join other evidence that regularities in the environment can attract attention. More generally, our results are consistent with Bayesian theories in which priors are given more weight under conditions of uncertainty.

Este trabalho estudou alguns programas e atividades de coleta seletiva de materiais recicláveis presentes nos resíduos sólidos urbanos. Foram selecionados quatro programas municipais oficiais (São Sebastião, São José dos campos, Santos e São Paulo) e dois trabalhos de organização espontânea (Favela Monte Azul e COOPAMARE/Cooperativa dos Catadores de Papel, Aparas e Materiais Recicláveis de São Paulo). Levantaram-se as formas de implantação das diferentes experiências em estudo e de mobilização das suas respectivas comunidades. Constatou-se que, apesar das variações encontradas nos diferentes casos, o envolvimento das comunidades foi significativo, fornecendo excelente oportunidade de percepção do espaço urbano e do exercício da cidadania, assim como da prática da máxima ambiental ista \"Pense globalmente, aja localmente\". Constatou-se ainda, que, pela complexidade do tema, é fundamental garantir a todas as pessoas envolvidas e interessadas o acesso às informações técnicas claras e precisas, assim como às práticas que motivem a participação de todos e ressaltem a importância do trabalho conjunto. Concluiu-se que, apesar do bom resultado dessas iniciativas, devem ser buscadas e enfatizadas ações que promovam maior integração entre os vários segmentos da sociedade (catadores, populacão, empresários, políticos, artistas, meios de comunicação, instituicões de ensino, entidades religiosas, etc). Deve-se priorizar práticas realmente integradoras e holísticas, capazes de promover a real prevenção da poluição, através da minimizacão de resíduos, isto é, de sua diminuição, a partir da reducão na fonte, reutilização e reciclagem. / This work consisted of a study of activities and programs of selective collection of recycled materials from urban solid waste. The study is based on four official municipal programs (São Sebastião, São José dos Campos, Santos and São Paulo) and two programs of spontaneous organization (Favela Monte Azul and COOPAMARE). This work analyzed the ways of implementation of the referred different experiences and the mobilization of their respective communities. It was verified that despite the observed variation in the different cases, the involvement of the communities was significant, providing an excellent opportunity of perception of the urban space and the practice of citizenship, as well as the environmentalist maximm \"Think globally, act locally\". It was also verified that due to the complexity of the subject, it is essential to ensure that all the people involved and interested have access to clear and precise technical information as well as to practices that stimulate participation and enhance the importance of collective work. It was concluded that despite the good results of the referred initiatives, one must pursue and emphasize actions which encourage integration among different members of society (population, business people, politicians, artists, media, educational institutions, religious groups, etc). One must also emphasize holistic and integrated practices, in order to promote a real pevention of pollution, with waste minimization through reduction in the sources, reuse and recycling.

Thesis advisor: Ana Martínez-Alemán / Research has demonstrated that attending a selective college increases the probability of graduating and accessing certain economic and social opportunities, but few community college transfer students obtain such an opportunity. In an effort to seriously consider how to increase access to this underserved population, it is important to examine the bridges by which academically-qualified community college transfer students access selective institutions. This multi-case study looks at why and how three private selective institutions in Massachusetts currently recruit community college students. The four main themes identified as to why these institutions recruit community college students were: strategic enrollment practices, diversity, institutional enrichment, and community engagement. The two themes identified for how institutions recruit community college students were: information sharing and infrastructure support. Several challenges facing both the selective colleges, and the community college transfer students were also identified and explored. The major finding of the study was that the unique position occupied by each institution within the hierarchy of the higher education system influences the rationale as well as the methods by which it approaches and considers the transfer of community college students. / Thesis (PhD) — Boston College, 2009. / Submitted to: Boston College. Lynch School of Education. / Discipline: Educational Administration.