Thesis (MA)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: This study focuses on the prosodic features of imperatives and the role of prosodies in the development of a text-to-speech (TIS) system for Xhosa, an African tone language. The perception of prosody is manifested in suprasegmental features such as fundamental frequency (pitch), intensity (loudness) and duration (length). Very little experimental research has been done on the prosodic features of any grammatical structures (moods and tenses) in Xhosa, therefore it has not yet been determined how and to what degree the different prosodic features are combined and utilized in the production and perception of Xhosa speech. One such grammatical structure, for which no explicit descriptive phonetic information exists, is the imperative mood expressing commands. In this study it was shown how the relationship between duration, pitch and loudness, as manifested in the production and perception of Xhosa imperatives could be determined through acoustic analyses and perceptual experiments. An experimental phonetic approach proved to be essential for the acquisition of substantial and reliable prosodic information. An extensive acoustic analysis was conducted to acquire prosodic information on the production of imperatives by Xhosa mother tongue speakers. Subsequently, various statistical parameters were calculated on the raw acoustic data (i) to establish patterns of significance and (ii) to represent the large amount of numeric data generated, in a compact manner. A perceptual experiment was conducted to investigate the perception of imperatives. The prosodic parameters that were extracted from the acoustic analysis were applied to synthesize imperatives in different contexts. A novel approach to Xhosa speech synthesis was adopted. Monotonous verbs were recorded by one speaker and the pitch and duration of these words were then manipulated with the TD-PSOLA technique. Combining the results of the acoustic analysis and the perceptual experiment made it possible to present a prosodic model for the generation of perceptually acceptable imperati ves in a practical Xhosa TIS system. Prosody generation in a natural language processing (NLP) module and its place within the larger framework of text-to-speech synthesis was discussed. It was shown that existing architectures for TTS synthesis would not be appropriate for Xhosa without some adaptation. Hence, a unique architecture was suggested and its possible application subsequently illustrated. Of particular importance was the development of an alternative algorithm for grapheme-to-phoneme conversion. Keywords: prosody, speech synthesis, speech perception, acoustic analysis, Xhosa / AFRIKAANSE OPSOMMING: Hierdie studie fokus op die prodiese eienskappe van imperatiewe en die rol van prosodie in die ontwikkeling van 'n teks-na-spraak-sisteem vir Xhosa, 'n Afrika-toontaal. Die persepsie van prosodie word gemanifesteer in suprasegmentele eienskappe soos fundamentele frekwensie (toonhoogte), intensiteit (luidheid) en duur (lengte). Weinig eksperimentele navorsing bestaan ten opsigte van die prosodiese eienskappe van enige grammatikale strukture (modus en tyd) in Xhosa. Hoe en tot watter mate die verskillende prosodiese kenmerke gekombineer en gebruik word in die produksie en persepsie van Xhosa-spraak is nog nie duidelik nie. 'n Grammatikale struktuur waarvoor geen eksplisiete deskriptiewe fonetiese inligting bestaan nie, is die van die imperatiewe modus wat bevele uitdruk. Hierdie studie wys hoe die verhouding tussen duur, toonhoogte en luidheid, soos gemanifesteer in die produksie en persepsie van Xhosa-imperatiewe bepaal kon word deur akoestiese analises en persepsueIe eksperimente. Dit het geblyk dat 'n eksperimenteelfonetiese benadering noodsaaklik is vir die verkryging van sinvolle en betroubare prosodiese inligting. 'n Uitgebreide akoestiese analise is uitgevoer om prosodiese data omtrent die produksie van imperatiewe deur Xhosa-moedertaalsprekers te bekom. Vervolgens is verskeie statistiese analises op die rou akoestiese data uitgevoer om (i) patrone van beduidenheid te bepaal en om (ii) die groot hoeveelheid numeriese data wat gegenereer is meer kompak voor te stel. 'n PersepsueIe eksperiment is uitgevoer met die doelom die persepsie van imperatiewe te ondersoek. Die prosodiese parameters soos uit die akoestiese analise bekom, is toegepas in die sintese van bevele in verskillende kontekste. 'n Nuwe benadering tot Xhosaspraaksintese is gevolg. Monotone werkwoorde is vir een spreker opgeneem en die toonhoogte en duur van hierdie woorde is met TD-PSOLA tegniek gemanipuleer. 'n Kombinasie van akoestiese en persepsueie resultate is aangewend om 'n prosodiese model te ontwikkel vir die sintese van persepsueel aanvaarbare imperatiewe in 'n praktiese Xhosa teks- na- spraaksinteti seerder . Prosodie-generering in 'n natuurlike taalprosesering-module en die plek daarvan binne die raamwerk van teks-na-spraaksintese is bespreek. Daar is gewys dat bestaande argitekture vir teks-na-spraaksisteme nie sonder sommige aanpassings toepaslik vir Xhosa sal wees nie. Derhalwe is 'n unieke argitektuur gesuggereer en die moontlike toepassing daarvan geïllustreer. Die ontwikkeling van 'n alternatiewe algoritme vir letter-na-klankomsetting was van besondere belang. Sleutelwoorde: spraaksintese, spraakpersepsie, akoestiese analise, Xhosa

published_or_final_version / abstract / Zoology / Master / Master of Philosophy

published_or_final_version / abstract / Statistics / Doctoral / Doctor of Philosophy

published_or_final_version / Statistics and Actuarial Science / Master / Master of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Statistics and Actuarial Science / Master / Master of Philosophy

Various climate models have been developed to analyze and predict climate change; however, model uncertainties cannot be easily overcome. A statistical approach has been presented in this paper to calculate the distributions of future climate change based on an ensemble of the Weather Research and Forecasting (WRF) models. Wavelet analysis has been adopted to de-noise the WRF model output. Using the de-noised model output, we carry out Bayesian analysis to decrease uncertainties in model CAM_KF, RRTM_KF and RRTM_GRELL for each downscaling region. / text

Numerous attempts have been made to identify the flavor compounds in Blue cheese, however, duplication of Blue cheese flavor has not yet been accomplished. Therefore, it was desirable to make a qualitative and quantitative investigation of Blue cheese flavor compounds and to study the effect of certain microorganisms on Blue cheese flavor. The aroma fraction of Blue cheese was isolated by centrifugation of the cheese and molecular distillation of the recovered fat. The volatiles were separated by gas chromatography on packed columns containing polar and nonpolar phases and by temperature programmed capillary column gas chromatography. Relative retention time data and fast scan mass spectral analysis of the capillary column effluent were used to identify compounds in the aroma fraction. Compounds positively identified were as follows: 2-pentanone, 2-hexanone, 2-heptanone, 2-octanone, 2-nonanone, 2-decanone, 2-undecanone, 2-tridecanone, 2-propanol, 2-pentanol, 2-heptanol, 2-octanol, 2-nonanol, methyl butanoate, methyl hexanote, methyl octanoate, methyl decanoate, methyl dodecanoate, ethyl formate, ethyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, ethanal, 3-methyl butanal, 2-methyl butanol, 3-methyl butanol, 1-pentanol, benzene, and toluene. Tentatively identified compounds included acetone, delta-octalactone, delta-decalactone, methyl acetate, isopropyl hexanoate, 3-methylbutyl butanoate, pentyl hexanoate, ethyl-2-methylnonanoate, isopropyl decanoate, furfural, 2-methyl propanal, methanol, ethanol, 2-phenylethanol, cresyl methyl ether, dimethylcyclohexane, diacetyl, methyl mercaptan, and hydrogen sulfide. A combination of liquid-liquid column chromatography and gas-liquid chromatography was utilized to quantitate the major free fatty acids in Blue and Roquefort cheese samples. The average concentration (mg acid/kg cheese) in three Blue cheese samples was as follows: 2:0, 826; 4:0, 1, 448; 6:0, 909; 8:0, 771; 10:0, 1,318; 12:0, 1,588; 14:0, 5,856; 16:0, 12,789; 18:0, 4,243; 18:1, 12,455; 18:2, 1,072; 18:3, 987. Roquefort cheese was found to be proportionately more abundant in 8:0 and 10:0 acids and low in 4:0 acid compared to Blue cheese. No formic, propionic, or isovaleric acid was detected in any of the cheeses tested. A quantitative procedure involving adsorption chromatography, liquid-liquid chromatography and absorption spectrophotometry was used to isolate and measure the concentration of the C₃, C₅, C₇, C₉, and C₁₁ methyl ketones in the fat of Blue and Roquefort cheese. The average methyl ketone concentration (micromoles ketone/10 g cheese fat) of five Blue cheese samples was as follows: acetone, 1.7; 2-pentanone, 5.9; 2-heptanone, 11.2; 2-nonanone, 9.3; 2-undecanone, 2. 4. Considerable variation in ketone concentration was noted between samples, but no consistent differences were observed between Blue and Roquefort cheese. One Roquefort sample contained no acetone. The annount of ketone formed during cheese curing does not depend directly on the amount of available fatty acid precursor. There appears to be a selective conversion of the 8:0, and to a lesser extent the 6:0 and 10:0, fatty acids to methyl ketones by the Penicillium roqueforti spores. The concentration of the C₅, C₇, and C₉ secondary alcohols was determined in the same cheeses used for ketone analysis. The previously measured ketones acted as internal standards and facilitated a semi-quantitative calculation of alcohol concentrations from peak areas of gas chrorriatograms. The average alcohol concentration (micromoles alcohol/10 g cheese fat) in five Blue cheese samples was as follows: 2-pentanol, 0. 3; 2-heptanol, 2. 1; 2-nonanol, 0. 8. The alcohols were present in approximately the same ratios as their methyl ketone analogs, but at much lower concentrations. A synthetic Blue cheese flavor was prepared using a blend of butterfat, dry curd cottage cheese, cream, and salt as a base. The most typical flavor was obtained using the following' compounds: the 2:0, 4:0, 6:0, and 8:0 fatty acids at two-thirds the average concentration found in cheese; twice the average concentration of the C₃, C₅, C₇, C₉, and C₁₁ methyl ketones and C₅, C₇, and C₉ secondary alcohols found in cheese: 2.0 mg/kg of base of 2-phenylethanol; 1.5 mg/kg of base of ethyl butanoate; 6.0 mg/kg of base of both methyl hexanoate and methyl octanoate. Incorporation of higher acids caused a soapy flavor. The presence of 2-phenylethanol and the esters was judged as very important in duplicating Blue cheese flavor. The mycelia of Penicillium roqueforti appear to be more active in the reduction of methyl ketones to secondary alcohols than the spores. Yeasts associated with Blue cheese are capable of reducing methyl ketones to secondary alcohols. Yeasts also may play a role in Blue cheese flavor by producing ethanol and other alcohols and certain esters. / Graduation date: 1966

A frequent problem in physics and engineering is that of determining a mathematical model for the dynamic performance of a system. It is particularly useful to be able to make measurements which enable such a model to follow changes in the system dynamics in the course of normal operation. Linear control theory, although now being replaced by a more general approach, can still form the basis for such system analysis. Cross correlating signals from a linear process can give a great deal of information about the process dynamics without injecting any test disturbances, or, when test signals are possible, cross correlation can be used to recover dynamic information in the presence of considerable background noise. The use of specially constructed test signals can make cross correlation a powerful technique in the identification of dynamic systems.

Whole safflower seeds of the Mexican variety Kino'76 with a protein content of 17.30% (dwb) were subjected to the processes of dehulling, defatting (n-hexane extraction) and debittering (70% methanol extraction) to produce four types of meals preparations: whole safflower meal, dehulled safflower meal, debittered, whole meal and debittered, dehulled meal with protein contents of 26.90, 66.93, 26.70 and 69.92%, respectively. The proteins of each meal were studied in detail by means of protein fractionation, gel filtration chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Osborne solubility fractionation of the protein of whole safflower meal showed that the amount of protein in the alkali soluble fraction was approximately 71% of the total and the alcohol soluble fraction did not contain any protein. After dehulling and debittering, the amount of protein in the alkali soluble fraction decreased by 30%, whereas the amount of protein in the insoluble residue increased by 12%. SDS-PAGE of the proteins of the water-, salt- and alkali soluble fractions revealed that they consisted of 8, 13 and 13 distinct subunits, respectively, with apparent molecular weights ranging from 14.7 to 88.0 kDa. The number of subunits and molecular weight distribution decreased as a result of debittering. Fractionation of the proteins of each meal by gel filtration chromatography followed by SDS-PAGE demonstrated that proteins of safflower seed are highly heterogeneous. The process of debittering caused major alteration of the molecular weight profile and subunit composition of the gel filtration protein fractions.