Spelling suggestions: "subject:"schmidt"" "subject:"loschmidt""
101 |
Kamenná moře neovulkanických pňů v severních Čechách: poloha, morfologie, míra zvětrávání. / Blockfields of the neovulcanic pits in Northern Bohemia: location, morphology, weathering rate.Plecháč, Petr January 2019 (has links)
Blockfields as an indicator of landscape development with a specific microclimate is presented in many scientific publications. This diploma thesis is focused on finding the relationship between the hardness of stone blocks and the intake of potential radiation, with an assessment of morphology, location and local conditions. Within the selected study areas in Northern Bohemia was recorded a total of 73 blockfields, of which 22 sites were selected for further investigation. From the results of the statistical analyses was shown the relationship between the income potential of radiation and the degree of ventilation of stone blocks. The analyses also show the relationship between the hardness of stone blocks in the blockfields and the orientation of the blockfields to the world's sides, which proved to be significant. The tests performed by the analyses of each third (high) stone seas have shown the possibility of moving rock blocks downhill.
|
102 |
Spatially-resolved studies of nearby star-forming galaxiesKumari, Nimisha January 2018 (has links)
Spatially-resolved studies of nearby star-forming galaxies are essential to understand various physical and chemical phenomena at play in the interstellar medium in the galaxies, and consequently to obtain a comprehensive picture of galaxy formation and evolution. In this thesis, I perform spatially-resolved analyses of chemical abundances and star-formation in nearby star-forming galaxies - blue compact dwarf galaxies (BCDs) and spiral galaxies. I map various properties of H II regions and the surrounding gas within three BCDs, using integral field spectroscopic (IFS) data from the Gemini Multi-Object Spectrograph-North. While answering questions related to chemical homogeneity, ionisation mechanisms and stellar populations within BCDs, I address more profound issues, which go beyond the characterisation of studied BCDs and aim to explain global phenomena with broader implications. The BCD NGC 4449 hosts a metal-poor central star-forming region, which I explain by various scenarios related to the interplay between star-formation, metal-distribution and gas dynamics within galaxies. The BCD NGC 4670 shows an unusual negative relationship between the nitrogen-to-oxygen ratio and oxygen abundance at spatially-resolved scales. I explore this relation with chemical evolution models and by comparison to other star-forming galaxies and suggest that nitrogen enrichment, variations in star-formation efficiency or hydrodynamical effects may be responsible for the observed relation. For another BCD, SBS 1415+437, the spatially-resolved abundances on average agree with the integrated abundance, implying that low-redshift spatially-resolved results may be directly compared with unresolved high-redshift results. I study spiral galaxies to address long-standing issues related to the reliability of metallicity calibrators and the Schmidt Law of star-formation. Using IFS data of twenty-four spiral galaxies taken with the Multi-Unit Spectroscopic Explorer, I find that the current strong-line metallicity calibrators for H II regions are unsuitable for regions dominated by diffuse ionised gas (DIG). I devise new recipes for estimating the metal-content of the DIG. For another set of nine spiral galaxies, I use multi-wavelength data to show that the spatially-resolved Schmidt relation is very sensitive to the consideration of diffuse background, which is a component unrelated to the current star-formation. Removal of this component from the SFR tracers and the atomic gas results in similar local and global Schmidt relation. To conclude, the spatially-resolved analyses presented in this thesis have led to discoveries and further questions, which I will address in my ongoing and future works.
|
103 |
A Convenient Synthesis of Pyrrolnitrin and Related Halogenated PhenylpyrrolesMORRISON, MATTHEW 07 October 2009 (has links)
This thesis details a straightforward synthetic route to the antifungal compound pyrrolnitrin 1.2, along with several analogous halogenated phenylpyrroles. The proposed synthetic protocol involved the Suzuki-Miyaura cross-coupling of appropriately halogenated pyrrole pinacolboronate esters and aryl compounds.
In the efforts towards preparing the cross-coupling partners, we report a regiospecific and high yielding synthesis of a 3-chloro pyrrole compound 2.14, its brominated analog 2.16, an iodinated analog 2.17, and the corresponding pinacolboronate ester 2.18. We also report a generalized reaction sequence (lithiation/carboxylation/Schmidt reaction/oxidation) for the preparation of halogenated benzoic acids, anilines and nitrobenzenes. In particular, we synthesized the desired halogenated nitrobenzene coupling partner 3.27 in excellent yield. We were also able to show that the conditions employed in this sequence were mild enough to allow preparation of the 2-bromo-6-iodo compound 3.33.
Once the coupling partners were prepared, we developed the optimal conditions for our Suzuki-Miyaura cross-coupling reactions. In doing so, we were able to prepare our target compound 1.2 and several halogenated analogs in good yields. We also prepared brominated and deuterated arylpyrroles 4.27 and 4.28, respectively, for future use in mechanistic studies of the pyrrolnitrin biosynthetic enzymes, PrnB, Prn C and PrnD. This required preparation of the corresponding brominated and deuterated pyrrole pinacolboronate esters 4.24 and 4.26. / Thesis (Master, Chemistry) -- Queen's University, 2009-09-29 13:58:35.186
|
104 |
Catalisadores heterogêneos para produção de chalconas: reação de condensação de Claisen-Schmidt / Heterogeneous catalysts for chalcones production: Claisen-Schmidt condensation reactionWinter, Caroline 07 March 2016 (has links)
Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-06-15T19:31:26Z
No. of bitstreams: 2
Dissertação - Caroline Winter - 2016.pdf: 7433726 bytes, checksum: bf2a1b900a9af4a614fcafcacca772fa (MD5)
license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-06-28T12:15:36Z (GMT) No. of bitstreams: 2
Dissertação - Caroline Winter - 2016.pdf: 7433726 bytes, checksum: bf2a1b900a9af4a614fcafcacca772fa (MD5)
license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5) / Made available in DSpace on 2016-06-28T12:15:36Z (GMT). No. of bitstreams: 2
Dissertação - Caroline Winter - 2016.pdf: 7433726 bytes, checksum: bf2a1b900a9af4a614fcafcacca772fa (MD5)
license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5)
Previous issue date: 2016-03-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The members of flavonoids and chalcones family have attracted great interest because of their pharmacological applications as antibacterial, anti-inflammatory and anticarcinogenicagents, and are commonly synthesized by Claisen-Schmidt condensation between acetophenone and benzaldehyde derivatives. This reaction is usually catalyzed under homogeneous conditions which present, however, several drawbacks such as catalyst recovery and waste disposal problems. This work proposes the use of a variety of heterogeneous catalysts to achieve good results for condensation Claisen-Schmidt reaction in terms of conversion and chalcones selectivity, when compared to the homogeneous catalysis. Two groups of catalysts were tested: metal oxides and activated carbons. Magnesium oxide catalysts were prepared by hydrothermal treatment and magnesium, niobium, lanthanum and titanium oxides by rehydration of commercial precursors, all methods followed and not followed by cesium impregnation. The activated carbons used as catalysts were Babassu, Bahia Coconut, ox bone and Dendê, raw and treated with sodium hydroxide. The catalysts were characterized by scanning and transmission electron microscopy, thermogravimetric analysis, differential thermal analysis, determination of the specific superficial area by the adsorption/desorption of N2 at 77 K method, infrared spectroscopy, X-ray diffraction and temperature-programmed desorption of CO2 and NH3. The basic sites of carbons were quantified by Boehm Method. Finally, the performance of the catalysts was evaluated on the Claisen-Schmidt reaction between Acetophenone and 4-nitrobenzaldehyde, and the conversion was quantified by high performance liquid chromatography. The best catalyst was treated babassu activated carbon, whose conversion achieved was 92,38%. / Os membros da família das chalconas e flavonóides têm despertado um grande interesse devido às suas aplicações como agentes farmacológicos, antibacterianos, anti-inflamatórios e anticarcinogênicos, sendo comumente sintetizados via condensação de Claisen-Schmidt entre derivados de acetofenona e de benzaldeído. Esta reação é catalisada normalmente sob condições homogêneas, que apresentam, no entanto, vários inconvenientes, tais como a recuperação do catalisador e problemas de destinação de resíduos. Neste trabalho foi proposto o uso de uma série de catalisadores heterogêneos para se alcançar bons resultados para a reação de condensação de Claisen-Schmidt, em termos de conversão e seletividade de derivados de chalconas, quando comparados à catálise homogênea. Foram testados dois grupos de catalisadores: óxidos metálicos e carvões ativados. Prepararam-se catalisadores de óxido de magnésio por tratamento hidrotérmico e óxidos de magnésio, nióbio, lantânio e titânio por reidratação de precursores comerciais, todos os métodos seguidos e não seguidos por impregnação de césio. Os carvões ativados utilizados como catalisadores foram de babaçu, coco da Bahia, osso de boi e dendê brutos e tratados com hidróxido de sódio. Os catalisadores foram caracterizados por microscopia eletrônica de varredura e transmissão, análise termogravimétrica, análise térmica diferencial, determinação de área superficial específica por análise textural de adsorção/dessorção de N2 a 77 K, espectroscopia de infravermelho, difração de raios X e dessorção à temperatura programada de CO2 e NH3. Os sítios básicos dos carvões foram quantificados pelo método de Boehm. Finalmente, o desempenho dos catalisadores foi avaliado na reação de Claisen-Schmidt entre Acetofenona e 4-Nitrobenzaldeído, sendo a conversão quantificada por cromatografia líquida de alta eficiência. O melhor catalisador foi o de carvão de babaçu tratado, cuja conversão alcançada foi de 92,38%.
|
105 |
Une approche multifractale pour la modélisation du micro-mélange à grand nombre de Schmidt / A multifractal approach for modeling turbulent micro-mixing at high Schmidt numbersVahe, Jonathan 06 October 2014 (has links)
Cette thèse est consacrée à la simulation du mélange de scalaires passifs à grand nombre de Schmidt (faible diffusion), au moyen d’un modèle de sous-maille structurel pour la Simulation aux Grandes Echelles (LES pour Large Eddy Simulation) reposant sur le caractère multifractal des champs de gradient en turbulence. L’analyse multifractale des champs de dissipation scalaire permet, à l’aide d’une description statistique des singularités, de prendre en compte l’intermittence inhérente à ces champs. Des simulations numériques directes du mélange à différents nombres de Schmidt supérieurs à l’unité sont mises en oeuvre. Une analyse multifractale au moyen de différentes méthodes est menée afin d’obtenir les spectres de singularités de la dissipation scalaire. Une implantation du modèle de sous-maille multifractal pour la vitesse, proposé par Burton et al., est d’abord réalisée dans le code volumes finis YALES2.Une modification du modèle équivalent pour les scalaires, reposant sur une cascade multiplicative pour reconstruire la dissipation scalaire de sous-maille, est proposée afin de prendre en compte le micro-mélange à grand nombre de Schmidt. Ce modèle de sous-maille est alors évalué au moyen de tests a priori. / This thesis is focused on the simulation of turbulent mixing of passive scalars at high Schmidt numbers (low diffusivity). The modeling work is based on a structural subgrid-scale model for Large Eddy Simulation relying on the multifractal nature of gradient fields in turbulence.The multifractal formalism provides a mean to handle the characteristic intermittency of scalar dissipation fields through a statistical description of their singularities. Direct Numerical Simulations of mixing at several Schmidt numbers above unity are run with a dedicated code. Different methods are used to perform a multifractal analysis of scalar dissipation. The multifractal subgrid-scale model of Burton et al. for velocity is implemented in the Finite Volume code YALES2. A modification of the equivalent multifractal model for scalars is proposed to take into account micro-mixing at high Schmidt numbers. The model shows satisfactory results when tested a priori against direct simulations.
|
106 |
Gleiche Sicherheit für alle statt NATO-Vorherrschaft: Beiträge zum 17. Dresdner Friedenssymposium am 21. Februar 2009Bald, Detlef, Crome, Erhard, Krause, Gerda, Sauer, Manfred, Schneider, Horst, Semmelmann, Helmut, Strutynsky, Peter 15 May 2019 (has links)
Die Projektgruppe „Für eine Globale Friedensordnung“ stellt im Dresdener Friedenssymposium Arbeitsergebnisse vor.:Gerda Krause, Eröffnung.
Autorenbeiträge:
Peter Strutynsky, Die Globalisierung der NATO oder die Militarisierung des Globus.
Erhard Crome, Gleiche Sicherheit für alle - Alternativen zur NATO.
Manfred Sauer, NATO – nicht die Sicherheit, die wir meinen.
Horst Schneider, Gedanken zum Kolloquiumsthema Gleiche Sicherheit für alle statt NATO-Vorherrschaft.
Nachträglich eingereichter Beitrag zum 13. Dresdner Symposium Für eine globale Friedensordnung, Heft 93/2009:
Detlef Bald, Das Beispiel vom Primat der Politik – Die Kontrolle der Atomwaffen in der Bonner Republik.
|
107 |
Elevation, Longitudinal Profile, And Schmidt Hammer Analysis Of Strath Terraces Through Capitol Reef National Park, Utah: Bedrock Channel Response To Climate Forcing?Eddleman, James L. 13 July 2005 (has links) (PDF)
Elevation, longitudinal profile, and Schmidt hammer data indicate that strath terraces (specifically the lower elevation terraces) mapped in the Fremont River drainage of Capitol Reef National Park are correlative to the terraces of the smaller Pleasant Creek drainage located approximately ten miles to the south. This correlation suggests that drainage development in this area of the Colorado Plateau was strongly dependent upon a regional-scale forcing mechanism (e.g. climate) rather than strictly independent basin-scale processes. Elevations of mapped strath terraces and their associated black volcanic boulder deposits were calculated from geologic maps, Digital Elevation Models (DEM), and Digital Orthophoto Quadrangles of the Fruita and Golden Throne Quadrangles, Wayne and Garfield Counties, Utah. Terraces in both drainages were placed into twenty foot elevation bins and then gathered into larger terrace levels based upon population breaks and the degree of weathering as seen from Schmidt hammer hardness data. Comparison of the two datasets indicate that the two lowest terrace levels of the Fremont River compare well with the two terrace levels of Pleasant Creek both in elevation above the present stream bed and in Schmidt hammer hardness measurements. Our data demonstrate that the Fremont River drainage is likely much older than the smaller Pleasant Creek drainage. Further, correlative terrace data strongly suggests that glacial-interglacial climate forcing played a dominant role in the landscape evolution of both drainages and by inference, the broader Colorado Plateau. Terrace elevation data were compared with recently published cosmogenic ages for several terrace deposits located within the Fremont River drainage. This comparison provides compelling evidence that highest concentrations of preserved terraces may be time correlative with discrete isotopic stages associated with glacial maximum and/or deglacial conditions. Finally, our data also demonstrate that in this area of the Colorado Plateau incision rates are on the order of ~60 to 85 cm/ka, which is on the high end of reported rates from other researchers.
|
108 |
Periodic Forcing of a System near a Hopf Bifurcation PointZhang, Yanyan 17 December 2010 (has links)
No description available.
|
109 |
Berechnung singulärer Punkte nichtlinearer GleichungssystemeSchnabel, Uwe 20 November 2000 (has links) (PDF)
Diese Arbeit beschäftigt sich mit der Berechnung singulärer Punkte nichtlinearer Gleichungssysteme F(x)=0. Dazu werden minimal erweiterte Systeme der Form F(x)+D*s=0, f(x)=0 betrachtet. Die allgemeine Vorgehensweise zur Berechnung singulärer Punkte mit solchen erweiterten Systemen wird geschlossen dargestellt. Dazu werden zuerst die (teilweise verallgemeinerten Ljapunov-Schmidt-)reduzierten Funktionen von Golubitsky und Schaeffer, Beyn, Jepson und Spence, Griewank und Reddien, Kunkel bzw. Govaerts verallgemeinert und zusammengefasst. Es wird die verallgemeinerte Kontaktäquivalenz all dieser verallgemeinerten reduzierten Funktionen und die Gleichheit der benötigten Regularitätsannahmen bewiesen. Für eine weitere, neu eingeführte reduzierte Funktion wird die in dieser Arbeit definierte Ableitungsäquivalenz zu den anderen reduzierten Funktionen gezeigt. Mit dieser neuen reduzierten Funktion wird eine Reihe singulärer Punkte klassifiziert. Aus dieser Klassifikation ergeben sich Funktionen f aus Ableitungen der neuen reduzierten Funktion. Mit den so eingeführten Funktionen f kann das zweistufiges Newtonverfahren nach Pönisch und Schwetlick effektiv angewendet werden. Alle benötigten Ableitungen werden mittels Automatischer Differentiation bestimmt. Die numerischen Ergebnisse für eine Reihe von Beispielen zeigen die Effizienz dieses Verfahrens. Beim Newtonverfahren werden lineare Gleichungssysteme mit geränderten Matrizen B gelöst. Es wird gezeigt, für welche Ränderungen die Konditionszahl von B minimal ist. Dies ist z.B. für gewisse Vielfache der Singulärvektoren zu den kleinsten Singulärwerten der Fall. Zur Bestimmung dieser Ränderungen wird die inverse Teilraumiteration für Singulärwerte in verschiedenen Algorithmen angewendet. Die Konvergenzeigenschaften werden untersucht. Für einen Algorithmus wird bewiesen, dass die Konditionszahlen der iterierten geränderten Matrizen monoton fallen. Die numerischen Experimente bestätigen diese Eigenschaften.
|
110 |
Berechnung singulärer Punkte nichtlinearer GleichungssystemeSchnabel, Uwe 27 October 2000 (has links)
Diese Arbeit beschäftigt sich mit der Berechnung singulärer Punkte nichtlinearer Gleichungssysteme F(x)=0. Dazu werden minimal erweiterte Systeme der Form F(x)+D*s=0, f(x)=0 betrachtet. Die allgemeine Vorgehensweise zur Berechnung singulärer Punkte mit solchen erweiterten Systemen wird geschlossen dargestellt. Dazu werden zuerst die (teilweise verallgemeinerten Ljapunov-Schmidt-)reduzierten Funktionen von Golubitsky und Schaeffer, Beyn, Jepson und Spence, Griewank und Reddien, Kunkel bzw. Govaerts verallgemeinert und zusammengefasst. Es wird die verallgemeinerte Kontaktäquivalenz all dieser verallgemeinerten reduzierten Funktionen und die Gleichheit der benötigten Regularitätsannahmen bewiesen. Für eine weitere, neu eingeführte reduzierte Funktion wird die in dieser Arbeit definierte Ableitungsäquivalenz zu den anderen reduzierten Funktionen gezeigt. Mit dieser neuen reduzierten Funktion wird eine Reihe singulärer Punkte klassifiziert. Aus dieser Klassifikation ergeben sich Funktionen f aus Ableitungen der neuen reduzierten Funktion. Mit den so eingeführten Funktionen f kann das zweistufiges Newtonverfahren nach Pönisch und Schwetlick effektiv angewendet werden. Alle benötigten Ableitungen werden mittels Automatischer Differentiation bestimmt. Die numerischen Ergebnisse für eine Reihe von Beispielen zeigen die Effizienz dieses Verfahrens. Beim Newtonverfahren werden lineare Gleichungssysteme mit geränderten Matrizen B gelöst. Es wird gezeigt, für welche Ränderungen die Konditionszahl von B minimal ist. Dies ist z.B. für gewisse Vielfache der Singulärvektoren zu den kleinsten Singulärwerten der Fall. Zur Bestimmung dieser Ränderungen wird die inverse Teilraumiteration für Singulärwerte in verschiedenen Algorithmen angewendet. Die Konvergenzeigenschaften werden untersucht. Für einen Algorithmus wird bewiesen, dass die Konditionszahlen der iterierten geränderten Matrizen monoton fallen. Die numerischen Experimente bestätigen diese Eigenschaften.
|
Page generated in 0.0196 seconds