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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.
51

Convergence Analysis for the Gradient-Projection Method with Different Choices of Stepsizes

Tsai, Jung-Jen 30 June 2009 (has links)
We consider the constrained convex minimization problem min x2C f(x) we will present gradient projection method which generates a sequence fxkg according to the formula xk+1 = PC(xk
52

Study of the substituent effect on coordination modes and physical property of iminoferrocenyl ligands for copper complexes

Tsai, Ming-chen 21 July 2009 (has links)
A series of ferrocenylimine [(£b5-C5H5)Fe(£b5-C5H4-C(Me)=N-R)]¡AR= nhexyl(1a)¡Acyclohexyl(1b)¡Aphenyl(1c)¡AN,N-dimethylethylamino(1d) ¡A4-methoxyphenyl(1e)¡A4-nitrophenyl(1f)¡Aand 2-methoxyethyl(1g)¡Ahave been synthesized by reaction of acetylferrocene and the corresponding amines through condensation reaction. Also 1,1¡¦-ferrocenyldiimines [Fe{(£b5-C5H4)-C(Me)=N-R}2]¡AR= nhexyl(2a)¡Acyclohexyl(2b)¡Aphenyl(2c)¡AN,N-dimethylethylamino(2d)¡A4-methoxyphenyl(2e)¡A4-nitrophenyl(2f)¡A3-nitrophenyl(2g)¡A2-methoxyethyl(2h) have been synthesized by reaction of 1,1¡¦-diacetylferoocene and the corresponding amines through condensation reaction. Solid state crystal X-ray structural analysis revealed the geometry of the ferrocene derivatives are various with the different substituents . In addition, these ferrocene derivatives might coordinate with CuBr to form a series of iminoferrcenyl copper(¢¹) complexes. Solid state crystal X-ray structural analysis revealed the iminoferrcenyl copper(¢¹) complexes 3a~3d showed monomeric or dimeric geometry and diiminoferrcenyl copper(¢¹) complexes 4a~4d exhibited polymeric or dimeric geometry. All synthesized ferrocenylimine and1,1¡¦-ferrocenyldiimines derivatives exhibited a reversible one ¡Velectron redox process in their cyclic voltammograms, and the values of their redox potentials relied on the R groups. The correlation between the redox potential and the Hammett substituent constant, £mp was quite well, with a correlation coefficient of 0.96 in CH2Cl2 and CH3CN. According to the cyclic voltammograms, iminoferrocenyl copper complexes showed that the substituents on the imino parts strongly affect the redox potentials of the iron centers in the ferrocenyl segments as well as the copper metal center. The Cu+/Cu2+ couple redox potentials are in the range of 0.269V and 0.719V dependent on solvent effect. The iminoferrocenyl copper complexes¡¦s UV-vis absorption seems to be red shift comparing with iminoferrocene. In the CH2Cl2, compound 3a¡B3b¡B4d shows emission at £fmax ~ 408 nm . In the CH3CN, compound 3a¡B3b¡B3c¡B3d¡B4a¡B4b and 4c show the blue shift emission band comparing with iminoferrocenyl copper complexes in CH2Cl2. In addition, complex 4d in CH2Cl2 and complex complex 3d in CH3CN showed higher quantum yield value. Moreover, compound 1a and 2a combined with CuBr exhibit good catalytic activity and controlling ability in the MMA ATRP process.
53

Antiquité et Lumières chez Benjamin Constant : 1767-1830 /

Kyrmizi, Maria E. January 2005 (has links)
Texte remanié de: Th. 3ème cycle--Littérature--Ecole des Hautes Etudes en Sciences sociales, 1984. Titre de soutenance : Liberté des anciens et liberté des modernes : thèmes et sources chez Benjamin Constant. / Bibliogr. p. 248-280.
54

Über cassinische Kurven auf der Pseudosphäre

Förster, Otto, January 1911 (has links)
Thesis (doctoral)--Westfälischen Wilhelms-Universität zu Münster, 1911. / Cover title. Vita. Includes bibliographical references.
55

On the variability of the fine structure constant /

Evans, Jason L. January 2004 (has links) (PDF)
Thesis (M.S.)--Brigham Young University. Dept. of Physics and Astronomy, 2004. / Includes bibliographical references (p. 87-88).
56

Benjamin Constant und die politik, 1767-1802 Eine psychologisch-historische studie ...

Bach, Woldemar, January 1936 (has links)
Inaug.-diss.--Leipzig. / Lebenslauf. "Literaturverzeichnis": p. [ix]-x.
57

Sulfonamide Partitioning to Aqueous Cationic Micellar Systems

CASHIN, PATRICK 31 January 2011 (has links)
Advances in analytical chemistry have resulted in a growing body of literature showing measurable concentrations of pharmaceuticals in both drinking and wastewater. Removal of such chemicals is typically inefficient and often poorly characterized. To characterize one such method of removal (micellar enhanced ultrafiltration, (MEUF)), interactions of a cetyl trimethylammonium bromide (CTABr) surfactant and sulfonamide antibiotics were examined by NMR and semi-equilibrium dialysis (SED). The locus and orientation of binding in a micelle was established for seven sulfonamides by 1H NMR, and it was found that hydrophilic sulfonamides showed weak coordination with the micelle, whereas hydrophobic sulfonamides penetrated into the micellar interior with coordination of the SO2NH group to the charged surface layer. Binding constants were determined by 1H NMR and showed apparent order of magnitude differences between nuclei. Several compounds were unable to be characterized in this manner due to low change in chemical shift with addition of CTABr. SED was performed as an alternative method to determine binding constants. Values determined in this manner were higher than those determined by 1H NMR. Binding constants were converted into changes in Gibbs free energy and used to evaluate and, where necessary, modify the orientation and locus proposed by 1H NMR. Attempts are made to correlate binding constants with octanol-water partition coefficients to determine if a free energy relationship can be derived. Characterization of these systems may allow for a predictive methodology to determine the MEUF removal efficiencies of new sulfonamide and surfactant combinations. It is also hoped that this work may be generalized to predict MEUF efficiency for a wide range of contaminants that might be found in wastewater. / Thesis (Master, Chemistry) -- Queen's University, 2011-01-31 09:46:28.248
58

Modeling, Analysis and Stabilization of Converter-Dominated Power Distribution Grids

Radwan, Amr A A Unknown Date
No description available.
59

Quantitative Structure-Property Relationships Modeling of Rate Constants of Selected Micropollutants in Drinking Water Treatment Using Ozonation and UV/H2O2

Jin, Xiaohui 16 May 2012 (has links)
Concern over the occurrence of micropollutants in drinking water and their health effects is increasing. Therefore, there is a growing interest in understanding micropollutant removal during drinking water treatment. Ozonation and advanced oxidation processes (AOPs) have been found to be effective in the degradation of many micropollutants. Ozonation involves reactions with both molecular ozone (direct pathway) and hydroxyl radicals (indirect pathway), while hydroxyl radicals are the main oxidants in advanced oxidation processes. Reaction rate constants of micropollutants with molecular ozone (kO3) and hydroxyl radicals (kOH) are indicators of their reactivity and are therefore useful in assessing their removal efficiency in ozonation and AOPs. However, to date, only a limited number of rate constants are available for micropollutants, especially emerging micropollutants such as endocrine disrupting chemicals (EDCs) and pharmaceuticals. Quantitative structure-property relationships (QSPR) are therefore desirable for predicting rate constants of numerous untested micropollutants without experimentation. The overall objective of this thesis was to develop predictive QSPR models which correlate the rate constants of a wide range of structural diverse micropollutants to their structural characteristics. To ensure the wide applicability of the QSPR models, the training set compound selection is critical and a group of heterogeneous compounds which are structurally representative of many others is preferred. A systematic compound selection approach which involves principal component analysis (PCA) and D-optimal onion design was applied for the first time in water treatment research. As a result, 22 micropollutants with diverse structures were selected as representatives from a large pool of micropollutants of interest (182 compounds). In addition, 12 molecular descriptors were identified which link relevant structural features to the removal mechanisms of oxidation processes. The kO3 and kOH values of the 22 selected micropollutants were then determined experimentally in bench-scale reactors at neutral pH using high performance liquid chromatography equipped with a photodiode array detector (HPLC-PDA). Three methods, competition kinetics, compound monitoring, and ozone monitoring were used for kO3 measurement, and competition kinetics was used for kOH measurement. As expected, kO3 values span a wide range from 10-2 to 107 M-1 s-1 because of the selective nature of molecular ozone. The general trends of micropollutant reactivity with ozone can be explained by the micropollutant structures and the electrophilic nature of ozone reactions. The kOH values range from 108 to 1010 M-1 s-1 because hydroxyl radicals are relatively non-selective in their reactions. For the majority of these micropollutants kO3 and kOH values were not reported prior to this study. Thus they provide valuable information for modeling and designing of ozonation and AOP treatment. QSPR models for kO3 and kOH prediction were then developed with special attention to model validation, applicability domain and mechanistic interpretation. With the experimentally determined rate constants, QSPR models were developed for predicting kO3 values using the selected 22 micropollutants as the training set and the 12 identified descriptors as model variables. As a result, two QSPR models were developed using piecewise linear regression (PLR) both showing an excellent goodness-of-fit. Model 1 was governed by average molecular weight and number of phenolic functional groups, and Model 2 was dominated by two principal components extracted from the descriptor matrix. The models were then validated using an external validation set collected from the literature, showing good predictive power of both models. Prior to applying these models to unknown micropollutants they need to be classified as high-reactive (logkO3 > 2 M-1 s-1) or low-reactive (logkO3  2 M-1 s-1), so that the appropriate submodel of the PLR can be applied. A classification function using linear discriminant analysis (LDA) was therefore developed which worked very well for both training and validation sets. With the help of additional compounds collected from the literature, and DRAGON molecular descriptors, a QSPR model for kOH prediction in the aqueous phase was developed using multiple linear regression. As a result, 7 DRAGON descriptors were found to be significant in modeling kOH, which related kOH of micropollutants to their electronegativity, polarizability, presence of double bonds and H-bond acceptors. The model fitted the training set very well and showed great predictive power as assessed by the external validation set. In addition, the model is applicable to a wide range of micropollutants. The model’s applicability domain was defined using a leverage approach. The main contributions of this thesis lie in the successful development of QSPR models for kO3 and kOH value prediction which, for the first time, can be used for a wide range of structurally diverse micropollutants. In addition, all QSPR models were externally validated to verify their predictive power, and the applicability domains were defined so that the applicability of the models to new compounds can be determined. Finally, the applicability of the model to natural water was explored by combining the QSPR models with the established Rct concept which predicts micropollutant removals during ozone treatment of natural water but requires kinetic data as input. Results show that the kinetic data from the QSPR model predictions worked well in the Rct model providing reliable estimations for most of the selected micropollutants. This approach can therefore be used in water treatment for initial assessment and estimation of ozonation efficiency.
60

A pile behaviour model

England, Melvin Gerrard January 1999 (has links)
No description available.

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