Aujourd'hui, la durabilité des structures en matériau cimentaire est un des facteurs importants dans les domaines du génie civil et du génie industriel. Elle est influencée non seulement par les chargements mécaniques mais aussi par l'environnement (pollution, pluie...). Ces influences deviennent plus importantes quand on doit garantir une durée de service du matériau pendant une grande période. Le mécanisme de dégradation chimique du matériau cimentaire consiste à une décalcification progressive au cours du temps en contact avec un environnement agressif (par exemple l’attaque par les chlorures, par les sulfates, les cycles gel-dégel, l’alcali-réaction). Cette dégradation provoque la variation de la porosité du béton qui modifie les propriétés physico-chimiques et mécaniques. D'une part cette variation de porosité accélère le processus de transport de matières et entraîne une accélération de la dissolution des hydrates (notamment la portlandite). D'autre part, ceci induit une modification des propriétés mécaniques, notamment le retrait. En plus, les sollicitations mécaniques créent des microfissures qui peuvent être des facteurs accélérant le processus de dégradation chimique. Ce travail de thèse est réalisé pour étudier le phénomène physico-chimique de la carbonatation sur les matériaux cimentaires comme les mortiers et les pâtes de ciment à la base CEM I et CEM III. Le but principal de cette étude est de caractériser expérimentalement et numériquement les effets du dioxyde de carbone (CO2) sur la durabilité et les propriétés mécaniques d’un matériau cimentaire. Dans la partie expérimentale, nous prenons en compte quelques paramètres importants tels que : le retrait, la variation de la porosité et de la masse en fonction de différentes teneurs en dioxyde de carbone (CO2) : 5%, 10%, 13%, 15%, 17%, 20%. Le modèle numérique basé sur l’approche physico-chimique de Bary et Sellier (2004) nous permet de valider les paramètres qui influencent le phénomène de carbonatation en matériau cimentaire comme le taux de saturation en eau, la pression partielle de dioxyde de carbone (CO2), la concentration en ions calcium et la porosité. Ceci confirme que les transferts de dioxyde de carbone (CO2) en phase gazeuse couplent avec les transferts de l’eau liquide et des ions du calcium Ca2+ en solution aqueuse au cours de la carbonatation. / Today, the durability of structures in cementitious materials is an important factor in the areas of civil engineering and industrial engineering. It is influenced not only by mechanical loads but also by the environment (pollution, rain ...). These influences become more important when one has to guarantee a service life of materials for a great period. The mechanism of chemical degradation of the cementitious material is a progressive decalcification over time in contact with aggressive environments (e.g. attack by chlorides, by sulfates, freeze-thaw cycles, alkali reaction). This degradation causes the variation in the porosity of the concrete that modifies the physico-chemical and mechanical properties. On the one hand, the change in porosity accelerates the transport of substances and causes an acceleration of the dissolution of hydrates (notably portlandite). Moreover, this induces a change in mechanical properties, especially shrinkage of carbonation. In addition, the mechanical stress creating microcracks that may be factors accelerating the process of chemical degradation. This work is carried out to study the physicochemical phenomenon of carbonation on cement-based materials such as mortars and cement pastes based on CEM I and CEM III. The main purpose of this study is to characterize experimentally and numerically the effects of carbon dioxide (CO2) on the mechanical properties and durability of cementitious material. In the experimental part, we take into account some important parameters such as shrinkage, variation of porosity and variation of mass in terms of different concentrations of carbon dioxide (CO2): 5%, 10%, 13%, 15%, 17%, 20%. The numerical model based on the physico-chemical approach by Bary and Sellier (2004) allows us to validate the parameters that influence the carbonation in cementitious material as rate of water saturation, partial pressure of carbon dioxide (CO2), calcium ion concentration and porosity. This confirms that the transfer of carbon dioxide (CO2) in gas phase couple with transfers of liquid water and calcium ions Ca2 + in aqueous solution during carbonation.

A dynamic model in which multiple consumers of a single nutrient may coexist in a fluctuating environment is given. Only one consumer can persist in a fixed environment, but coexistence may be produced by effects of a fluctuating environmental variable on nutrient utilization differing between consumers. An approximate solution is given for the non-autonomous Lotka-Volterra-Verhulst ordinary differential equations of the model together with heuristic sufficient conditions for construction of a persistent multispecies consumer community. Computational examples demonstrate persistence of an idealized example community for periodic and random environmental fluctuation. Two further examples demonstrate that environmental fluctuation can produce coexistence when environmental variables, standing crops, assimilation efficiencies, primary productivity, utilization rates, and respiration rates are comparable to a tropical grassland, and an oligotrophic temperate lake. The sensitivity of model solutions to functional variations of the component species may be rapidly and accurately calculated. This allows the identification and estimation of unknown species functional responses from time series data of biomasses and a measured environmental variable. Unknown functions of an environmental variable are approximated by a Tchebycheff polynomial expansion in that variable. Unknown coefficients of these expansions are the parameters of the model. These parameters are determined by the unconstrained minimization of the squared deviations of the logarithm of biomass observations and model differential equation solution using a Quasi-Newton algorithm. This least squares estimator was applied to a one year biomass time series of four zooplankton grazers, phytoplankton, and average lake temperature of a small oligotrophic lake. Application of the model to this grazer zooplankton community gives evidence of partial stabilization due to environmental fluctuation in a natural community. It is concluded that environmental variation, which is often assumed on theoretical grounds to be destabilizing, should rather be considered as one of the bases of community persistence. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Interconnects constitute a dominant source of circuit delay for modern chip designs. The variations of critical dimensions in modern VLSI technologies lead to variability in interconnect performance that must be fully accounted for in timing verification. However, handling a multitude of inter-die/intra-die variations and assessing their impacts on circuit performance can dramatically complicate the timing analysis. In this thesis, three practical interconnect delay and slew analysis methods are presented to facilitate efficient evaluation of wire performance variability. The first method is described in detail in Chapter III. It harnesses a collection of computationally efficient procedures and closed-form formulas. By doing so, process variations are directly mapped into the variability of the output delay and slew. This method can provide the closed-form formulas of the output delay and slew at any sink node of the interconnect nets fully parameterized, in-process variations. The second method is based on adjoint sensitivity analysis and driving point model. It constructs the driving point model of the driver which drives the interconnect net by using the adjoint sensitivity analysis method. Then the driving point model can be propagated through the interconnect network by using the first method to obtain the closedform formulas of the output delay and slew. The third method is the generalized second-order adjoint sensitivity analysis. We give the mathematical derivation of this method in Chapter V. The theoretical value of this method is it can not only handle this particular variational interconnect delay and slew analysis, but it also provides an avenue for automatical linear network analysis and optimization. The proposed methods not only provide statistical performance evaluations of the interconnect network under analysis but also produce delay and slew expressions parameterized in the underlying process variations in a quadratic parametric form. Experimental results show that superior accuracy can be achieved by our proposed methods.

Haydn¡¦s variation play an very importment role in the development of variations. Haydn not only continue C.P.E. Bach¡¦s variation technique, but also has innovations both in variation form and variation¡¦s technique. Haydn writes twenty-one keyboard variations, most of them are written as melodic variation with fixed harmony. The form of variation of Haydn can be divided into four types- strophic variations, rondon variations, alternating variations and ABA variations. All these variations are based on subject¡¦s recurrence, and the theme contrast to the subject. Strophic variations was the type that haydn most often use. Haydn¡¦s keyboard variation can be divided into independent keyboard variations and variation¡¦s movement in the keyboard sonata. Haydn have five independent keyboard variations, most of them were sectional variations. There are sixteen variation¡¦s movements, most of them are continuous variations. Most of the time, they are place in the finale. The subject in Haydn¡¦s keyboard variation all have two sections, which divided by repeat sign. Haydn seems prefer using up-beat and dotted rhythm in his subject. Beside writing variations in Allegro movement, he also writes variation in Adagio and Andante movement. In this thesis includes four chapters. The first chapter is to discuss variaion¡¦s development in the classical period. The second chapter is to sort out and analyze the type of Haydn¡¦s keyboard variations. The third chapter is to analyze the variation technique in Haydn¡¦s keyboard variations. The fourth chapter is conclusion.

The eastern subterranean termite, Reticulitermes flavipes, is the most widely dispersed termite in North America. The genus Reticulitermes spp. is responsible for 80% of total termite damage caused to urban structures each year. Little is known about the genetic structure of termites, particularly at the colony level. Evidence for what genetically defines a termite colony is a hotly debated topic in current literature due to the implications such findings would have regarding current lawsuits against pest control operations. Information on termite genetic structure is sparse. In this study, the genetic variation and gene flow among Texas populations of R. flavipes at the statewide level and city level was examined. A 324-337 base pairs segment of the mtDNA, AT-rich region was a polymerase chain reaction amplified from 104 different termite specimens from 12 Texas cities. The DNA extracts were then subjected to PCR amplification using specific primers and it was then sequenced. Using the sequence data and appropriate statistical measures it was found that, at the statewide level, nucleotide and haplotypic diversity is low. Gene flow was found to be low on a statewide basis. At the city level nucleotide and haplotypic diversity was high. The findings of this study provide insights into termite genetic structure.

No description available.

Inaug.-Diss.--Leipzig. / Vita. "Literatur": p. [5]-11.

Silozi came into existence in the early 1800s when Sikololo speakers (Makololo) from South Africa came in contact with the Siluyana speakers (Luyi) in Barotseland. Today the language is spoken by over 700 000 people in Zambia, Namibia, Botswana, Angola and Zimbabwe collectively. Of the wealth of scholarship on the Malozi and their language, most focused on development and structure. Silozi dialect variation is yet to be explored in depth. This is a study of dialect variation in cross-border Silozi. The focus is on the lexicon and the morphosyntactic structures of the Silozi varieties spoken in the towns of Katima Mulilo (Namibia) and Mongu (Zambia). As an example of mixed-methods research, the data collection was conducted using the language documentation and description approach (see Lüpke, 2010; Himmelman, 1998). The data comprised of lexicon and sample sentences elicited via structured interviews from 70 participants. In addition, metalinguistic questions were used to collect information on essential language use patterns during data analysis. The findings confirmed that Silozi is the official language in Katima Mulilo, but Chisubiya and Chifwe are the dominant lingua francas. Contrastingly, in Mongu, Silozi is the main Bantu language, with others spoken minimally. A consequence of this is that the Katima Mulilo variety contained more lexical borrowings from other Bantu languages compared to Mongu. However, both varieties borrowed more lexicon from English than from the Bantu languages. Morphosyntactically, the Katima Mulilo variety contains grammatical features from Chisubiya that are not present in the Mongu variety. Chisubiya plays a central role in the differences that emerge between the two varieties. Overall, the Mongu variety appeared to be more stable and less susceptible to change. This thesis thus illustrates that there is nuanced variation in cross-border Silozi. Language contact and migration are shown to have been significant factors in ongoing language change in cross-border dialects.

This thesis examines acoustic properties of speech which influence perceptions of personality traits, specifically charisma. The following questions are addressed: How does amplitude variation influence ratings of dominance (i), how does voice quality affect personality trait attribution (ii), and how does allophonic variation affect ratings of charisma (iii). Chapter 2 addresses question (i), finding that certain linguistic levels (increased amplitude in sentence and syllable levels) affected dominance ratings while others (increased amplitude at word level and reduction at syllable level) did not. Increased sentence amplitude increased dominance ratings while increased syllable amplitudes had inverse effects. Additionally, two types of dominance were examined (social and physical dominance) but no statistically significant differences were found between the two. Chapter 3 examines question (ii). All voice qualities investigated (modal, creaky, breathy, nasal, and smiling) were found to be statistically significant. Effect sizes for statistical significance varied for each voice quality. Creaky voice (rated the lowest/ most negative) and smiling voice (rated the highest/most positive) had the strongest effects. Chapter 4 examines question (iii). Experiment 1 (in-person) and Experiment 2 (online) examined the effects of allophonic variation, final consonant devoicing (FCD), and /t/ variation, on ratings of charisma. Experiment 1 found statistically significant rating differences for FCD. Final voiced items were rated higher compared to devoiced ones. For the /t/ variation, only speaker differences were found to be statistically significant. Experiment 2 showed no statistically significant results for FCD, whereas /t/ variation found statistical significance for [t] productions versus the glottal stop, and for flap productions versus the glottal stop. No rating differences were found between [t] and flap. Overall, this thesis demonstrates that some acoustic variations within speech affect personality trait ratings, specifically charisma, while others do not. I discuss reasons for these outcomes and their utilization in various domains, including AI. / Dissertation / Doctor of Philosophy (PhD) / This research explores the effects of different aspects of speech on the impressions of the speaker’s personality. It examines three questions: (i) how loudness affects the perception of dominance, (ii) how voice quality influences personality traits, and (iii) how pronunciation variations impact charisma. Chapter 2 (i) found that for sentences, increases in loudness increases perceptions of dominance, while for syllables they reduce them. Chapter 3 (ii) found that each voice quality investigated affects personality trait ratings, but creaky voice was perceived most negatively and smiling voice most positively. Chapter 3 (iii) found that voiced final consonants are rated higher in charisma than devoiced ones for in-person participants, but not for online participants. Regular [t] and flap pronunciations differ from glottal stops but not from each other only for online participants. The findings suggest that certain aspects of speech variation influence personality trait ratings and offer applications to teaching and AI.

No description available.