No description available.

Call number: LD2668 .T4 1963 A25 / Master of Science

Call number: LD2668 .T4 1978 A95 / Master of Science

Call number: LD2668 .T4 1978 L35 / Master of Science

Call number: LD2668 .T4 1979 C53 / Master of Science

Résumé : La cartographie des bio-régions des océans est d'une importance clé pour permettre une meilleure compréhension des dynamiques des écosystèmes qui y sont présents et permettre une saine gestion de ceux-ci. Les classifications actuelles utilisent les mêmes combinaisons d'attributs soit : la bathymétrie, la température de surface, la concentration en chlorophylle a et certaines luminances normalisées (443 nm, 520 nm 550 nm). L'utilisation de la variabilité de 2e ordre du signal optique de la chlorophylle a a permis de mettre en évidence d'autres attributs globaux, indépendants de la concentration en chlorophylle a, ouvrant la porte à de nouvelles démarches de classification non dirigée des océans en provinces biogéochimiques. L'objectif de l'étude est de développer une méthode de classification dynamique, non dirigée des provinces océaniques en utilisant une combinaison de données satellitaires, soit : les signatures optiques des constituants biochimiques présents dans l'océan et les propriétés physiques des masses d'eau selon une nouvelle approche intégrant à la fois des informations complémentaires et indépendantes de la chlorophylle a. Le but étant d'effectuer la classification des provinces océaniques de l'Atlantique Nord pour la période de disponibilité des données MODIS Aqua (2002-2012) et de déterminer l'évolution spatiale des provinces océaniques et leur succession au fil du temps. L'application de différentes techniques de classification a été réalisée sur deux jeux de données mis en place pour les besoins de l'étude. Les résultats montrent que la méthode K-mean et la méthode DBSCAN ne sont pas appropriées pour classifier de manière dynamique les provinces bio-optiques de l'Atlantique Nord. Une nouvelle méthode de classification : PRODENCAN, a été développée pour combler les lacunes de ces techniques. Les résultats obtenus par cette méthode permettent de confirmer le potentiel d'améliorer la classification océanique par l'utilisation de la variabilité de 2e ordre du signal optique de la chlorophylle a mais n'ont pas permis la création d'un patron de classification dynamique pour l'Atlantique Nord. Ceux-ci permettent de préciser le processus de résolution de ce problème par l'implémentation d'un jeu de données spécifiquement choisi d'un point de vue spatial et temporel. L'analyse dynamique a permis de confirmer le potentiel de l'utilisation de la variabilité de 2e ordre du signale optique de la chlorophylle a combinée à la température de surface de l'eau et de la concentration en chlorophylle a pour mieux définir des régions bio-optiques ayant des signatures phénologiques distinctives.||Abstract : Mapping bioregions of the oceans is of key importance for a better understanding the dynamics of ecosystems in oceans and ensure the adequate management of them. Actual existing classifications use the same combinations of attributes including: bathymetry, sea surface temperature, chlorophyll concentration and certain standard luminance (443 nm, 520 nm 550 nm). The use of second order variability of optical signals from chlorophyll a suggest other possible global attributes, independent of chlorophyll a concentration, opening doors to new approaches in unsupervised classification of oceans biogechimical provinces. The objective of the study is to develop a method of ocean provinces dynamic unsupervised classification, using a combination of satellite data as : optical signatures of biochemical constituents in the ocean and the physical properties of water masses according to a new approach that integrates both information complementary and independent of chlorophyll a. The goal is to perform the classification of oceanic provinces of the North Atlantic for the availability period of MODIS Aqua (2002-2012) and to determine the spatial evolution of oceanic provinces and their succession over time. Different techniques of classification were carried out on two data sets developed for the purposes of the study. The results show that the K-mean and DBSCAN method are not appropriate to perform bio-optical provinces dynamic classification of the North Atlantic. A new method of classification: PRODENCAN was developed to fill the gaps of these techniques. The results obtained by this method can confirm the potential to improve the classification by the use of second order variability of chlorophyll a optical signals but have not yet led to the creation of a dynamic pattern classification for North Atlantic. Nevertheless, they allow to specify the process for solving this problem by implementing a set of specifically training data spatially and temporally chosen. Dynamic analysis has confirmed the potential for the use of second order variability of chlorophyll a optical signals combined with sea surface temperature and the chlorophyll a concentration to better define bio-optical regions with distinctive phenology signatures. [symboles non conformes]

Automated classification of texts into genres can benefit NLP applications, in that the structure, location and even interpretation of information within a text are dictated by its genre. Cross-lingual methods promise such benefits to languages which lack genre-annotated training data. While there has been work on genre classification for over two decades, none has considered cross-lingual methods before the start of this project. My research aims to fill this gap. It follows previous approaches to monolingual genre classification that exploit simple, low-level text features, many of which can be extracted in different languages and have similar functions. This contrasts with work on cross-lingual topic or sentiment classification of texts that typically use word frequencies as features. These have been shown to have limited use when it comes to genres. Many such methods also assume cross-lingual resources, such as machine translation, which limits the range of their application. A selection of these approaches are used as baselines in my experiments. I report the results of two semi-supervised methods for exploiting genre-labelled source language texts and unlabelled target language texts. The first is a relatively simple algorithm that bridges the language gap by exploiting cross-lingual features and then iteratively re-trains a classification model on previously predicted target texts. My results show that this approach works well where only few cross-lingual resources are available and texts are to be classified into broad genre categories. It is also shown that further improvements can be achieved through multi-lingual training or cross-lingual feature selection if genre-annotated texts are available in several source languages. The second is a variant of the label propagation algorithm. This graph-based classifier learns genre-specific feature set weights from both source and target language texts and uses them to adjust the propagation channels for each text. This allows further feature sets to be added as additional resources, such as Part of Speech taggers, become available. While the method performs well even with basic text features, it is shown to benefit from additional feature sets. Results also indicate that it handles fine-grained genre classes better than the iterative re-labelling method.

Mathematical programming (MP) can be used for developing classification models for the two–group classification problem. An MP model can be used to generate a discriminant function that separates the observations in a training sample of known group membership into the specified groups optimally in terms of a group separation criterion. The simplest models for MP discriminant analysis are linear programming models in which the group separation measure is generally based on the deviations of misclassified observations from the discriminant function. MP discriminant analysis models have been tested extensively over the last 30 years in developing classifiers for the two–group classification problem. However, in the comparative studies that have included MP models for classifier development, the MP discriminant analysis models either lack appropriate normalisation constraints or they do not use the proper data transformation. In addition, these studies have generally been based on relatively small datasets. This thesis investigates the development of MP discriminant analysis models that incorporate appropriate normalisation constraints and data transformations. These MP models are tested on binary classification problems, with an emphasis on credit scoring problems, particularly application scoring, i.e. a two–group classification problem concerned with distinguishing between good and bad applicants for credit based on information from application forms and other relevant data. The performance of these MP models is compared with the performance of statistical techniques and machine learning methods and it is shown that MP discriminant analysis models can be useful tools for developing classifiers. Another topic covered in this thesis is feature selection. In order to make classification models easier to understand, it is desirable to develop parsimonious classification models with a limited number of features. Features should ideally be selected based on their impact on classification accuracy. Although MP discriminant analysis models can be extended for feature selection based on classification accuracy, there are computational difficulties in applying these models to large datasets. A new MP heuristic for selecting features is suggested based on a feature selection MP discriminant analysis model in which maximisation of classification accuracy is the objective. The results of the heuristic are promising in comparison with other feature selection methods. Classifiers should ideally be developed from datasets with approximately the same number of observations in each class, but in practice classifiers must often be developed from imbalanced datasets. New MP formulations are proposed to overcome the difficulties associated with generating discriminant functions from imbalanced datasets. These formulations are tested using datasets from financial institutions and the performance of the MP-generated classifiers is compared with classifiers generated by other methods. Finally, the ordinal classification problem is considered. MP methods for the ordinal classification problem are outlined and a new MP formulation is tested on a small dataset.

Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: The phylogenetic relationships and taxonomic status of South African Oxalis L. species are highly unresolved, both regionally and with regard to precise placement within the genus as a whole. Studies based exclusively on morphological and palynological characteristics have hitherto proved only partially successful in resolving natural groupings among the indigenous taxa of the region. Recent studies involving a few native taxa have indicated the plastid trnL-trnF non-coding DNA region as useful for the purposes of reconstructing phylogenetic relationships within the genus. The present study addressed the taxonomic monophyly and relationships of the highly unresolved section Angustatae subsection Lineares, using DNA sequence data. The phylogenetic reconstruction of southern African Oxalis species renders five of the subsections of section Angustatae sensu Salter (1944) polyphyletic, three of them conclusively so. The members of subsection Lineares are split between three clades, two of them with strong bootstrap support. None of these three clades consists exclusively of species of subsection Lineares. Likewise four of the seven assemblages of related taxa within subsection Lineares sensu Salter (1944) are not retrieved as monophyletic. Pollen data sensu Dreyer (1996) supports the clades retrieved in this study, whereas very few morphological characters could be plotted as potential synapomorphies for these clades. The resultant phylogenetic reconstruction thus supports palynological data of this subsection, and indicates the urgent need for a revision of the current morphological classification of Salter (1944). / AFRIKAANSE OPSOMMING: Die filogenetiese verwantskappe en taksonomiese klassifikasie van Suid Afrikaanse Oxalis L. spesies is nog baie onduidelik, beide binne die gebied en ten opsigte van die presiese plasing binne die genus as 'n geheel. Vorige werk, uitsluitlik gebaseer op morfologiese en palinologiese kenmerke, was tot dusver nog net gedeeltelik suksesvol in die identifikasie van natuurlike groepe binne die inheemse taksa van die gebied. Onlangse studies op 'n paar inheemse spesies het die nut van die plastied trnL-trnF nie-koderende DNA area bevestig vir die rekonstruksie van filogenetiese verwantskappe in die genus. Hierdie studie is gerig op die taksonomiese monofilie en verwantskappe van die onnatuurlike seksie Angustatae subseksie Lineares, deur gebruik te maak van DNA basis-volgorde data. Die filogenetiese rekonstruksie van Suid Afrikaanse Oxalis spesies dui aan dat vyf van die subseksies van seksie Angustatae sensu Salter (1944) polifileties is, met sterk steun daarvoor dat drie van hulle onnatuurlik is. Die lede van subseksie Lineares is tussen drie verskillende groepe versprei; twee van dié groepe het sterk ondersteuning. Nie een van die drie groepe bestaan uitsluitlik uit spesies van subseksie Lineares nie. So ook is vier van die sewe groepe van verwante spesies binne subseksie Lineares sensu Salter (1944) polifileties. Stuifmeel data volgens Dreyer (1996) ondersteun die groepe wat deur die DNA volgordes uitgewys is, terwyl baie min morfologiese kenmerke gebruik kan word as potensiële sinapomorfe/kenmerke. Die filogenetiese rekonstruksie ondersteun dus die palinologiese data van die subseksie, en dui op die dringende behoefte aan 'n hersiening van die huidige morfologiese klassifikasie van Salter (1944).

Dissertation (PhD)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The previous revision of Zygophyllum L. by Van Huyssteen (1937) included all known species of the cosmopolitan genus Zygophyllum. The present study deals with the species of Zygophyllum occurring in the southern African region which includes Angola, Namibia, Botswana and South Africa. The majority of Zygophyllum species occur in the arid and semi-arid, western parts as well as in the interior parts but some species do occur to the south of the area where milder climatic conditions are experienced. Zygophyllum species are typically described as shrubs or shrublets, rarely herbaceous annuals or biennials, with simple, sessile leaves or sessile, bifoliolate or petiolate, bifoliolate leaves of a succulent texture. Macromorphological as well as phytogeographical data were studied in order to delimit the taxa and to determine their relationships as well as their distributions. Various tables summarizing diagnostic characters of taxonomic importance as well as line drawings depicting the salient features of the species are given. The division of the genus Zygophyllum into two subgenera was investigated and this division is corroborated with additional evidence concerning floral, fruit and seed morphology. The absence or presence of an elaiosome on the seeds found in the two subgenera reflects on their different dispersal strategies. The structure of the morphologically different mucilage produced by the seeds of the two subgenera is touched on. The division of the subgenera Agrophyllum (Neck.) End!. and Zygophyllum, each into several sections, was investigated. Two sections, one from each subgenus, were transferred: the monotypic § Morgsana (Huysst.) Van Zyl to subgenus Zygophyllum; and the monotypic § Grandifolia Eng!. to subgenus Agrophyllum. The § Prismatica Van Zyl is newly described and the §Annua Eng!. is reinstated. seventeen new species are described, a few names sunk into synonymy and several name changes made. / AFRIKAANSE OPSOMMING: Die vorige hersiening van Zygophyllum L., deur Van Huyssteen (1937), het alle bekende spesies van die kosmopolitaanse genus Zygophyllum ingesluit. Die huidige studie handel slegs oor die Suider afrikaanse Zygophyllum-spesies wat in Angola, Namibië, Botswana en Suid-Afrika voorkom. Die meerderheid Zygophyllum spesies groei in ariede en semi-ariede dele aan die weskus asook in die binneland van die area maar sommige spesies groei ook in die suide van die gebied met 'n meer gematigde klimaat. Zygophyllum-spesies word beskryf as struike of halfstuike, is selde kruidagtige, een- of tweejariges en het gewoonlik eenvoudige, sittende blare of sittende verdeelde of gesteelde verdeelde, sukkulente blare. Makromorfologiese en geografiese data is bestudeer om die verskillende taxa af te baken, om verwantskappe tussen die onderskeie spesies vas te stel sowel as om die verspreiding vir elke takson aan te gee. Tabelle met die vernaamste taksonomies kenmerke asook lynsketse van die mees belangrike kenmerke van die verskillende species word verskaf. Die verdeling van Zygophyllum in twee subgenera is ondersoek en is, met behulp van bykomende blom-, vrug- en saadmorfologiese inligting, volkome regverdig bevind. Die aan- of afwesigheid van elaiosome op sade dui op verskillende saadverspreidings metodes. Die morfologies-verskillende slymlaag wat deur die saad van die twee subgenera produseer word, is kortliks beskryf. Die verdeling van die subgenera Agrophyllum en Zygophyllum in verskeie seksies is ondersoek. Die monotipiese subseksie Morgsana word na subgenus Zygophyllum en die monotipiese § Grandifolia na subgenus Agrophyllum verskuif. Die § Prismafica word as nuut beskryf en die § Annua word in hergebruik geneem. Sestien nuwe spesies word beskryf, enkele name word in sinonimie geplaas.