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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
371

Lexical blending among young Chinese readers

Kwan, Pun-lok, David., 關本樂. January 2012 (has links)
Lexical compounding refers to the process of word formation through union of lexicalized morphemes. Given that young Chinese readers learn print vocabulary as unanalyzed whole, I am uncertain whether children can effortlessly decompose bound morphemes from disyllabic words for lexical compounding to occur. With this concern, I propose a lexical blending process in parallel with lexical compounding, where words are constructed from previously learnt words that have not yet been decomposed as morphemes. This thesis investigated the mechanisms behind the lexical blending process, as well as its role in word reading among young Chinese readers, in five studies Studies One and Two examined the factors that favor lexical blending to occur. In Study One, I located a high proportion of disyllabic words and bound morphemes within a corpus of Chinese textbooks in Hong Kong. Around 40-50% of disyllabic words in Grade One to Grade Three are composed of one or more bound morphemes, which set a favorable environment for lexical blending to occur. In Study Two, I found that younger readers tended to commit more selection errors, defined as “naming the target character as a character that forms a highly frequent two-character compound word with it” (Shu, Meng, Chen, Luan and Cao, 2005), than older readers during character reading, suggesting that their representations of bound morphemes were not precise. An experiment on morpheme name judgment demonstrated that bound morphemes and low frequency morphemes embedded in high frequency words were most prone to selection errors. I further examined the lexical blending process and its contribution to reading development in Studies Three and Four. Adopting a cross-sequential design in Study Three, I found that lexical blending concurrently and longitudinally predicted Chinese word reading, after lexical compounding and other reading-related variables were partialled out. In Study Four, I located lexical class and structural relation knowledge as significant component skills of lexical blending. The process of lexical blending proceeded first with structural arrangement of words, followed by morphological decomposition and union of morphemes to eventually form a blended word. I also tested Chinese dyslexic readers’ performance on lexical blending in Study Five. Dyslexic readers exhibited difficulties in lexical blending and all the related component skills, when compared with chronological-age (CA) matched controls. Process-wise, the dyslexic readers were weaker than CA controls in both structural arrangement and morphological decomposition, while having particular difficulties in the latter process. I conclude that lexical blending is an important word formation process for young Chinese readers. To aid mastery of lexical blending, readers should be aware of the syntax in phrases and sentences, as it provides cues on structural arrangement of blended words. In addition, I suggest explicit instruction on lexical blending skills in the curriculum, with a particular focus on morphological decomposition, in order to meet the learning needs of dyslexic readers. / published_or_final_version / Psychology / Doctoral / Doctor of Philosophy
372

Numerical simulation of flow in open-channels with hydraulic structures

Kara, Sibel 21 September 2015 (has links)
Extreme hydrological events associated with global warming are likely to produce an increasing number of flooding scenarios resulting in significant bridge inundation and associated damages. During large floods, the presence of a bridge in an open channel triggers a highly turbulent flow field including 3D complex coherent structures around bridge structures. These turbulence structures are highly energetic and possess high sediment entrainment capacity which increases scouring around the bridge foundation and consequently lead to structural stability problems or even failure of the structure. Hence, understanding the complex turbulent flow field for these extreme flow conditions is crucial to estimate the failure risks for existing bridges and better design of future bridges. This research employs the method Large Eddy Simulation (LES) to predict accurately the 3D turbulent flow around bridge structures. The LES code is refined with a novel free surface algorithm based on the Level Set Method (LSM) to determine the complex water surface profiles. The code is used to analyze the hydrodynamics of compound channel flow with deep and shallow overbanks, free flow around a bridge abutment, pressure flow with a partially submerged bridge deck and bridge overtopping flow. All simulations are validated with data from complementary physical model tests under analogous geometrical and flow conditions. Primary velocity, bed shear stress, turbulence characteristics and 3D coherent flow structures are examined thoroughly for each of the flow cases to explain the hydrodynamics of these complex turbulent flows.
373

Methods for calculating chemical properties in the condensed phase

Sheppard, Daniel Glen 07 February 2011 (has links)
With advancements in computer technology and processing power, the ability to examine chemical systems using theory continues to be more practicable. Using ab initio methods, such as density functional theory, we are now able to routinely simulate hundreds of atoms. This system size allows us to directly simulate surfaces and nano-materials that are industrially relevant. With the expansion of accessible systems comes the opportunity to develop new computational methods to extract their chemical properties. Of particular interest is bridging the time scale gap between simulation and experiment. The evolution of a system chemical in time can be directly simulated using classical dynamics, however, molecules vibrate on the order of femtoseconds and interesting transitions tend to happen on much longer time scales: milliseconds to seconds. In condensed phase chemical systems these interesting transitions are hindered by energy barriers so state to state dynamics are dominated by rare evens. Luckily, rare event transitions tend to happen through mountain passes in the potential energy landscape. Within harmonic transition state theory, the transition states between minima can be characterized by saddle points. Finding saddle points is a challenging problem which has not been satisfactorily solved; nevertheless, there are algorithms currently being used despite their deficiency. In particular, my work strives to improve the efficiency and stability of the nudged elastic band method and compare its performance to similar algorithms on a variety of test systems. In addition, I present a method to predict how energy-based chemical properties change with respect to the chemical composition of the system. This is achieved by taking a derivative of the property with respect to the atomic numbers of the atoms present in the system. The accuracy and predictive quality of these derivatives are assessed for both model and industrially relevant systems. With this information, we can follow these derivatives to optimize a desired property in the space of chemical composition. This method is a step toward using theory to rationally design compounds with desirable properties. / text
374

Kalbotyros terminai J. Palionio ,,Kalbos mokslo pradmenyse" / Linquistic terms in ,,Kalbos mokslo pradmenyse“ [,,The Elements of Linquistics Science“] by J. Palionis

Bučelienė, Jolanta 24 September 2008 (has links)
Darbe analizuojama kalbotyros mokslo terminų, pavartotų J. Palionio vadovėlyje, kilmė ir sandara. Čia aprašoma terminų kilmė, daryba, sudėtinių terminų struktūra, jų dėmenų sintaksiniai ryšiai. Nustatomas įvairių rūšių terminų (vienažodžių ir sudėtinių; lietuviškų, hibridinių ir tarptautinių ir pan.) procentinis santykis. Iš viso surinkta 2280 terminai. Rasti terminai abėcėlės tvarka surašyti darbo pabaigoje pridėtoje terminų rodyklėje. Terminais šiame darbe laikomi tik daiktavardžiai. Antroje dalyje aptariami J. Palionio ,,Kalbos mokslo pradmenų“ vadovėlio vienažodžiai kalbotyros terminai kilmės atžvilgiu – išskirti ir aprašyti lietuviški, tarptautiniai ir hibridiniai terminai, taip pat aptariama terminų daryba. Lietuviški ir hibridiniai terminai čia skirstomi pagal darybos būdus (priesagų, galūnių, priešdėlių vediniai ir dūriniai), o tarptautiniai – pirminius, darinius ir darybiškai neaiškius. Trečioje dalyje nagrinėjama sudėtinių terminų sandara. Atskirai aptariami sudėtiniai dvižodžiai, trižodžiai ir daugiažodžiai terminai. Aprašoma ir sudėtinių terminų dėmenų kilmė. Terminai grupuojami pagal jų dėmenų sintaksinius santykius, struktūrą. Darbo pabaigoje pateikiamos apibendrintos analizės išvados, šaltiniai, naudotos literatūros sąrašas. / The paper analyses the origin and structure of linguistic terms used in J. Palionis textbook. The paper describes the origin and composition of terms as well as the structure of compound terms and syntactical relations of components. It establishes the percentage of different types of terms (one-words and compounds; Lithuanian, hybrid and international, etc). The total of 2280 terms were collected. The gathered terms are attached in the alphabetical order in the Terms Index of the final section of the paper. This paper considers the terms as nouns. The second section discusses the origin of linguistic one-word terms provided in the textbook “Basics of Linguistics“ by J. Palionis – it identifies and describes Lithuanian, international and hybrid terms as well as discusses the composition of terms. Lithuanian and hybrid terms are grouped on the basis of the methods of composition (suffixes, endings, derivatives and compounds of prefixes) and international terms are grouped into original, compounds and ambiguous terms. The third section deals with the structure of compound terms. It discusses separately compound two-word, three- word and multi-word terms. The section also describes the origin of components of compound terms. The terms are grouped on the basis of the syntactical relations of their components and the structure. The final section of the paper presents the summarized conclusions of the analysis, references and the list of literature.
375

Sorption and desorption of pyridine by Pahokee peat from hexadecane in the presence of organic co-solvents.

Reddy, Minolen Kistensamy. January 2002 (has links)
A study of the interactions of the specifically interacting organic compound pyridine with a model soil organic matter sorbent (Pahokee peat) was carried out from different nonaqueous organic liquid media, including neat n-hexadecane, acetonitrile, acetone and nhexadecane mixtures with either acetone or acetonitrile. Kinetic and equilibrium studies using an activity-based comparison of the organic compounds in solution was used to study the interactions of soil organic matter (SOM) and pyridine sorption capability in the various non-aqueous organic liquid media. Quantification and qualification of pyridine and the other co-solvents were done using Gas Chromatography (GC). Sorption of pyridine from neat organic solvents was not masked by sorption of the organic solvent. The apparent sorbed amount calculated from the change in solute concentration and reported on a dry weight basis was considered to represent the true sorbed concentration of pyridine in the sorbent phase. Pyridine sorption was found to be non-linear and distribution coefficients decreased with solute concentration, by approximately three times in n-hexadecane, more than five times in acetonitrile, and by ten times in acetone over the experimental concentration range. Pyridine sorption from nhexadecane was also found to be comparable with sorbed amounts from acetone, but much lower in comparison to sorption from acetonitrile. Sorption of pyridine from n-hexadecane mixtures with acetonitrile or acetone demonstrated the solvent assisted effect of pyridine sorption. Sorption uptake of pyridine increased as initial acetonitrile concentration increased, this acetonitrile assisted trend for pyridine sorption was found in the presence of a large excess of n-hexadecane. Sorbed concentrations of pyridine measured in the presence of high concentrations of acetonitrile (close to it's solubility limit) were found to be very similar to pyridine sorption from neat acetonitrile. Sorption behaviour of pyridine in n-hexadecane-acetone mixtures showed that increasing acetone concentrations had no effect on pyridine sorption. Pyridine sorbed from n-hexadecane, n-hexadecane-acetonitrile, and n-hexadecaneacetone mixtures showed a hysteretic desorption to n-hexadecane. After a series of repeated solvent extractions with solvents of increasing solvating power(1,4-dioxane, ethanol, dimethylsulfoxide), a fraction of pyridine remained bound to the peat. This nonrecoverable fraction was approximately the same for the different organic media (OA5± 0.09 in n-hexadecane suspensions, 0.57±O.12 in n-hexadecane-acetonitrile mixtures, and OA6±0.07 in n-hexadecane-acetone mixtures). Acetonitrile sorption by peat from nhexadecane was found to be very non-linear and hysteretic. The acetonitrile sorbed was almost fully recoverable, around 90%, for the initial acetonitrile concentration range varying from 0.14-0.7% by volume. However in the presence of pyridine a significant portion of acetonitrile was not recovered even after multiple extractions of polar organic solvents. Pyridine irreversible binding was not induced by acetonitrile additions and was found to occur to the same extent in both neat n-hexadecane and n-hexadecane-acetone mixtures. The solubilities of acetonitrile and acetone were determined by the flask method at 25°C using GC analysis. Solubility in volume percent for acetonitrile in n-hexadecane, 0.9±0.07, 0.57±0.02 for n-hexadecane in acetonitrile, 24.0±OA for acetone in nhexadecane, and 13 A±O.2 for n-hexadecane in acetone, were found. Log Ostwald coefficient (1.63±O.02) for acetonitrile in n-hexadecane was measured at 25°C using head space analysis and was found to be constant in the acetonitrile concentration range 0.10.8% by volume. Log Ostwald coefficient for pyridine in hexadecane used was 3.02, for the pyridine concentration range 50 mgIL-500 mg/L, this value was constant even with 0.5% by volume additions of acetonitrile. Analyses of sorption isotherms were reported on an activity basis to eliminate the effect of differential solute interactions in the solvent, calculated using the solute equilibrium concentration, the concentration of saturated vapour, and the Ostwald coefficient. Dissolution of peat components into n-hexadecane are known to be negligible. Peat components extracted after 12 hours and 3,5 months acetonitrile and acetone treatment (solid liquid ratio 1: 10) Showed 15 to 20 times less visible absorbance respectively (A. 465, 620, and 665, E4:E6 ratios using DV-Visible Spectroscopy), than the 12 hours aqueous peat extract. Quantification of the dissolved humic materials in the aqueous extract was followed using a Total Organic Carbon analyser. The study found the degree of humification to be much lower in non-aqueous organic solvent extracts (2.5 for acetone extracts, and 3 for acetonitrile extracts) than in aqueous solution extracts (8.2). / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002. / The Moshe Greidinger Scholarship Fund.
376

Controls on the soil solution partitioning of dissolved organic carbon and nitrogen in the mineral horizons of forested soils

Kothawala, Dolly N. January 2009 (has links)
Note: / The soil-solution partitioning of dissolved organic carbon (DOC) withinmineral soil horizons is primarily controlled by processes of adsorption and desorption. These abiotic processes largely occur within a short equilibration time of seconds to minutes, which generally occur faster than microbial processes. To characterise the adsorption of DOC to mineral soils, I used the Langmuir adsorption isotherm, which holds several advantages to the commonly used linear initial mass (IM) isotherm. One advantage to using the Langmuir isotherm is anestimation of the maximum DOC adsorption capacity (Qmax). The Qmax estimates the number of remaining DOC binding sites available on the mineral soil particle surfaces. I modified the traditional Langmuir isotherm in order to estimate the DOC desorption potential of native soil organic matter (SOC).[...] / Le partitionnement entre les solutions de sols du carbone organiquedissous (COD) dans les horizons des sols minéraux est essentiellement contrôle par les processus d'adsorption et de désorption. Ces processus abiotiques se déroulent normalement dans un bref temps d'équilibration variant de quelques secondes a quelques minutes, ce qui est en général plus rapide que les processus microbiens. Pour caractériser Fadsorption de COD aux sols minéraux, nous avons utilise l'isotherme d'adsorption de Langmuir. Cette isotherme présente plusieurs avantages par rapport a Fisotherme de masses initiales (IM) linéaires couramment utilisée, en particulier F estimation de la capacité d'adsorption maximale du COD (Qmax). Le Qmax estime le nombre de sites de liaison de COD restants a la surface du sol minéral. Nous avons aussi modifie Fisotherme de Langmuir traditionnelle afin d'évaluer le potentiel de désorption de COD de la matière organique du sol indigène (MOS).[...]
377

Production and biodegradation of dissolved carbon, nitrogen and phosphorus from Canadian forest floors

Turgeon, Julie. January 2008 (has links)
Dissolved organic matter (DOM) is operationally defined as soluble/colloidal material passing through a 0.45mum filter paper. The importance of DOM in soils relies on its role in soil formation and weathering processes, plant and microbial assimilation and soil and water acidification. However, the scientific community studying DOM still disagrees on whether fresh or humified material is the major source of DOM within the forest floor. One of the factors that could influence the overall importance of DOM production by organic horizons is its potential for biodegradability. In addition, the interaction occurring between the nutrients (i.e. nitrogen (N) and phosphorus (P)) and carbon (C) substrate is believed to be of major importance. / To acquire more knowledge on the production and biodegradation of dissolved C, N and P during decomposition of organic matter (OM), I performed laboratory incubations to evaluate rates of production and transformation, the influence of the degree of OM decomposition and stand type on these rates, and the stoichiometric relationships of the different quotients during the incubations. First, I performed a 30-day incubation of coniferous and deciduous OM from 10 Canadian forest floors representing various degrees of OM decomposition and subsequently measured the amount of: dissolved organic carbon (DOC), total dissolved nitrogen (TDN), nitrate (NO3-N), ammonium (NH4-N), dissolved organic nitrogen (DON), total dissolved phosphorus (TOP) and carbon dioxide (CO2-C). I performed water extractions with the same set of samples to evaluate the biodegradability of DOC and DON and the transformations of TDN, NO3-N and NH4-N. / Fresh material produces more DOM than humified material; material in the midpoint of decomposition (F horizon) produced the largest amount of DIN. Coniferous and deciduous samples did not display different rates of DOM production, most likely because of the overshadowing effect of OM degree of decomposition. I found strong links between the organic matter and dissolved phase C and N content and C:N quotient. The biodegradation, measured as DOC disappearance and mineralization of CO2-C, showed a discrepancy, reflecting the importance of increasing microbial biomass at the beginning of the incubation in response to priming effect. The sharp decrease of TDN and DON observed in the first few days of the incubation, in addition to increasing amount of dissolved inorganic N as waste products during decomposition of DON, supports this hypothesis. A better understanding of the dynamics of dissolved C, N and P in soil is essential to further understand their role in global elemental cycles, including climate change, forest management and pollution.
378

Controls on the soil solution partitioning of dissolved organic carbon and nitrogen in the mineral horizons of forested soils

Kothawala, Dolly N., 1972- January 2009 (has links)
The soil-solution partitioning of dissolved organic carbon (DOC) within mineral soil horizons is primarily controlled by processes of adsorption and desorption. These abiotic processes largely occur within a short equilibration time of seconds to minutes, which generally occur faster than microbial processes. To characterise the adsorption of DOC to mineral soils, I used the Langmuir adsorption isotherm, which holds several advantages to the commonly used linear initial mass (IM) isotherm. One advantage to using the Langmuir isotherm is an estimation of the maximum DOC adsorption capacity (Qmax). The Qmax estimates the number of remaining DOC binding sites available on the mineral soil particle surfaces. I modified the traditional Langmuir isotherm in order to estimate the DOC desorption potential of native soil organic matter (SOC). / Sorption characteristics were derived for a broad range of52 mineral soils collected from 17 soil profiles spanning across Canada from British Columbia to Quebec. Mineral horizons with the greatest Qmax included the Fe-enriched B horizons of acidic Podzols and Volcanic soils, followed by B horizons not enriched in Fe, followed by A and C horizons. Podzol B horizons were distinct from all other horizons due to significantly higher desorption potential. Soil properties predicting the adsorption characteristics of DOC also predicted the adsorption characteristics of dissolved organic nitrogen (DON). Adsorption of DOC and DON was tightly coupled (R 2 = 0.86), however the ratio of DOC:DON in the final equilibrium solution lowered for 48 out of 52 minerals horizons. These results suggest that DON may be slightly more mobile than DOC. / A short-term (32 day) incubation was perform to establish the fate of indigenous soil C, relative to newly adsorbed soil C to four mineral soils with different adsorption characteristics. Soil columns were leached periodically and sampled for DOC and CO2 production. Two Fe-enriched mineral horizons with high adsorption capacity released low amounts of old SOC, yet released almost all of the newly adsorbed SOC. In contrast, two B horizons without Fe-enrichment released greater amounts of old SOC, and retained a greater fraction of the newly adsorbed SOC than the Fe-enriched horizons. These results identify a contrast between the fate of indigenous and newly adsorbed SOC on mineral soils with differing Qmax. / The final component of this study examined changes to the molecular structure of DOC after equilibration with mineral soils. Multiple techniques were used to assess changes in the molecular composition of DOC, including the analysis of aromatic content by specific UV absorbance (SUVA) and fluorescence spectroscopy, analysis of molecular weight distribution (MWD) with high performance size exclusion chromatography (HPSEC) and functional group analysis with Fourier transform infra-red spectroscopy (FTIR). The solution phase DOC generally showed a reduced aromatic content, along with the removal of organic compounds with carboxyl groups. The MWD of DOC was reduced after equilibration to mineral soils, and the reduction in average molecular weight was related to the Qmax of mineral soils. / The various components of this thesis have contributed to the overall understanding of controls on the adsorption of DOC and DON species to mineral soils of the Canadian temperate and boreal forest.
379

Netolygūs įverčiai, aproksimuojant sudėtiniu Puasono dėsniu / Nonuniform estimates in approximation by the compound Poisson law

Andreikėnas, Giedrius 11 August 2009 (has links)
Šiame darbe nagrinėjama atsitiktinio dydžio X skirstinio aproksimacijos sudėtiniu Puasono dėsniu netolygūs įverčiai. / In this paper we analyze nonuniform estimates in approximation by the compound Poisson distribution.
380

Fractionation of carbon isotopes during fatty acid metabolism in Atlantic pollock (Pollachius virens)

AuCoin, Lacey R 02 September 2011 (has links)
Feeding experiments were conducted on Atlantic pollock (Pollachius virens) to examine the variability in tissue fatty acid (FA) composition and stable carbon isotope fractionation of FA during digestion, assimilation and mobilization of lipids. The FA profiles and compound-specific carbon isotopes of chylomicrons, liver, muscle and fasted serum were compared to diet. FA analysis demonstrated similarity among tissue groups despite differences in feeding states. The FA results indicate the blood of post-prandial fish may serve as an alternative to tissue biopsies for the estimation of marine fish diets with compound-specific isotope analysis (CSIA). Despite similarity among FA profiles, the carbon isotope discrimination factors of FA varied independently, which suggests that fractionation is influenced by the degree to which individual FA are oxidized. These results provide preliminary information that is necessary in order to use CSIA to estimate the effects of fish diets.

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