• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 76
  • 29
  • 8
  • 7
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 152
  • 54
  • 47
  • 42
  • 23
  • 22
  • 21
  • 16
  • 15
  • 15
  • 14
  • 14
  • 12
  • 11
  • 11
  • 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

Reversed-Phase HPLC Determination of Cholesterol in Food Items.

Essaka, David Christian 05 May 2007 (has links) (PDF)
Cholesterol is a fat-like molecule found among lipids in animal (including human) tissues. It is needed for maintaining good health. However, health issues have been raised because of the strong correlation between high levels of cholesterol in the body and cardiovascular disease. An HPLC method for quantitative determination of cholesterol in foods is presented. This involves a C-18 stationary phase using a 70:30 methanol: 2-propanol mobile phase with an UV detector set at 212 nm. The method showed linearity in the range 5.0 to 100.0 μg/mL and also good reproducibility with relative standard deviation of 4.22%, 2.71%, 4.8%, and 3.7% for the different samples analyzed. The mean recovery of the butter sample was 106.5%. The samples under investigation were common food items such as butter, lard, and two different types of cheese.
52

Local positioning system for mobile robots using ultra wide-band technology / Lokalt positioneringssystem för mobila robotar med ultra wideband teknik

Lensund, Filip, Sjöstedt, Mikael January 2018 (has links)
This thesis explores the possibility of using ultra wideband technology to localize anoutdoor mobile robot. More explicitly, this project focuses on the multilaterationproblem where the topology of the static reference anchors are changed. Insteadof having stationary anchors they are placed on a mobile robot and by pinpointingone single static tag node the position of the robot is established. The research usesa robotic lawn mover from Husqvarna, the Automover 430X. The robot is used asa base platform for this thesis to evaluate if this approach is applicable for othergeneric robots in the same size. The feasibility of this solution is demonstratedthrough simulation using Matlab and the robot simulation environment Gazebo.Results show that this specific topology is feasible for tracking a specific point butis also suitable for positioning a mobile robot if coupled with an accurate headingsensor. The system was evaluated for several scenarios of which all indicated anadequate accuracy, provided that data from an encoder was used. The upper limitfor the position error in a one sided 95% confidence interval was 0.469m at a rangeof 40m. / Detta examensarbete tar sig an problemet att lokalisera en långsamtgående mobilrobot i en utomhusmiljö genom att använda sig av ultra wideband radioteknik. Vanligtvisplaceras stationära noder i miljön som används för att positionera en ensamnod i dess närhet. Detta projekt tar sig an frågeställningen om det är möjligt attvända på problemet och placera dessa stationära noder på den mobila roboten föratt sedan fixera robotens position genom att bestämma vart den ensamma nodenär placerad. Husqvarnas robotgräsklippare Automover 430X har används som plattformför att evaluera och testa om denna tes är applicerbar för andra generiska robotari samma storlek. Positionsuppskattningen utförs genom simulationer i Matlabsamt simulationsmiljön Gazebo som tar hänsyn till diverse fysiska fenomen. Resultatenpekar på att denna topologi är möjlig för att lösa multilatereringsproblemetom en riktningssensor med hög precision används. För alla scenarion som simuleradesindikerades att en någorlunda god precision kan uppnås och det krävdes attsystemet kombinerades med annan indata, som en enkoder i detta fall för att förbättraestimeringen. Den övre gränsen för felet i ett 95% konfidensintervall var 0.469mpå ett avstånd upp till 40m.
53

Synthetic biological studies on production of methanol from natural resource-derived carbon compounds / 天然資源由来炭素化合物を基質としたメタノール生成反応に関する合成生物学研究

Takeya, Tomoyuki 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(農学) / 甲第23251号 / 農博第2458号 / 新制||農||1085(附属図書館) / 学位論文||R3||N5341(農学部図書室) / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 阪井 康能, 教授 小川 順, 教授 井上 善晴 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
54

Comparison of the Ultrastructure of HTC And HTC-Reversed Cowpea Seeds Using Scanning Electron Microscopy

Boateng, Akua F. 20 April 2010 (has links)
No description available.
55

Methods for the Characterization of Electrostatic Interactions on Surface-Confined Ionic Liquid Stationary Phases for High Pressure Liquid Chromatography

Fields, Patrice R. 19 September 2011 (has links)
No description available.
56

On the computer aided design of a shaft subjected to reversed bending and steady torsion

Curcio, Peter L. January 1987 (has links)
No description available.
57

Confined magnetohydrodynamics applied to magnetic fusion plasmas / Magnétohydrodynamique confinée appliquée aux plasmas de fusion magnétiques

Morales Mena, Jorge 01 October 2013 (has links)
La description magnétohydrodynamique est utilisée pour étudier les plasmas de fusion par confinement magnétique dans deux configurations: tokamak et reversed field pinch. Une méthode de Fourier pseudo-spectrale et une technique de pénalisation en volume sont employées pour résoudre les équations. La méthode de pénalisation permet d’introduire des conditions aux limites de Dirichlet et donc de faire varier facilement la géométrie considérée. Les simulations dans des géométries toroïdales de type tokamak montrent l’apparition spontanée de vitesses. Une importante composante toroïdale se développe si le système est peu dissipatif. Il est aussi montré que la brisure de symétrie dans la forme de la section du tore fait apparaitre un moment angulaire toroïdal. Pour le Reversed Field Pinch on montre l’émergence de structures hélicoïdales. La forme de ces structures varie en fonction des coefficients de transport ainsi que du paramètre de pincement du champ magnétique imposé. Pour compléter l’étude on compare les résultats du tore aux calculs dans un cylindre périodique. Les différences dans la dynamique des deux cas sont mises en avant. Finalement les simulations sont confrontées à des expériences et un meilleur accord est observé entre simulation et expérience pour la géométrie toroïdale que pour la géométrie cylindrique. / A magnetohydrodynamic description is used to study magnetic fusion plasmas in two different configurations: tokamak and reversed field pinch. A Fourier pseudo-spectral method with a volume penalization technique are used to solve the system of equations. The penalization method is used to introduce Dirichlet boundary conditions and it al- lows to easily modify the consider geometry. The simulations of a tokamak configuration in a toroidal geometry show the spontaneous appearance of velocities. These velocities are dominated by their toroidal component if the system is little dissipative. It is also shown that the symmetry breaking of the cross section of the torus causes a toroidal angular momentum to develop. For the Reversed Field Pinch configuration we show the appearance of helical structures. The shape of these structures varies with the value of the transport coefficients and with the pinch ratio parameter of the imposed magnetic field. To complete the study, we compare the results of simulations obtained in toroidal and in periodic cylindrical geometries. The differences in the dynamics of these two cases are highlighted. Finally, simulations are compared to experimental data and a significant better agreement is observed between the simulation and the experiment for the toroidal geometry than for the cylindrical case.
58

Optimering av vätskekromatografiska parametrar vid kvantifiering av läkemedel i serum med LC-MS/MS för klinisk diagnostik / Optimizing Chromatographic Parameters for Quantification of Pharmaceuticals in Serum with LC-MS/MS for Clinical Use

Edlund, Sofie January 2021 (has links)
Vid Klinisk kemi och farmakologi, Specialkemi, vid Skånes universitetssjukhus, Lund, utförs kvantifiering med LC-MS/MS av antipsykotiska och antidepressiva läkemedelskoncentrationer i serum med acetonitril (ACN) som mobilfas. ACN är på grund av sin höga elueringsstyrka ett av de vanligaste organiska lösningsmedlen vid reversed phase (RP) kromatografi, men uppvisar samtidigt en hög toxicitet med risk för stora leveransproblem. I syfte att reducera mängden ACN undersöktes därför möjligheten till ett mobilfasbyte till metanol (MeOH). Ordinarie metod jämfördes med tre nyutvecklade metoder med MeOH-baserad mobilfas. I en av metoderna ändrades endast mobilfas och elueringsgradient, medan två av metoderna även använde andra sorters RP-kolonner med anpassade elueringsgradienter. Samtliga analyter uppvisade godkänd separation och retention vid eluering med MeOH, men stor fluktuation från referensmetod sågs vid kvantifieringen av flera analyter, däribland olanzapin, desmetylolaznapin och mirtazapin. Liknande avvikelser med avseende på regression och kvantifieringsdifferens observerades vid eluering med andra sorters RP-kolonner. Detta indikerar att vidare optimering av andra vätskekromatografiska och masspektrometriska parametrar bör utföras innan metoderna kan valideras. / The quantification of antipsychotics and antidepressants in human serum with LC-MS/MS is usually performed with acetonitrile (ACN) as mobile phase. ACN is one of the most common organic solvents in reversed phase (RP) chromatography thanks to its high elution strength but is also highly toxic and can at times suffer from major delivery problems. The present study investigated the possibility of replacing ACN with methanol (MeOH) as primary organic solvent with the purpose of reducing the total ACN-usage. Three newly developed methods for chromatographic analysis of antipsychotic and antidepressant drugs using MeOH as organic solvent as part of the mobile phase were compared to the routine method in regard to analyte separation and retention, as well as the relative quantification of substance. In one of the methods only the mobile phase and elution gradient was changed whereas different types of RP columns were applied in addition to the changed mobile phase in the other two. All substances showed acceptable separation and retention when eluted with MeOH but displayed large fluctuations in the quantification of the analyzed substances, more specifically olanzapine, desmethylolanzapine and mirtazapine, in comparison to the reference method. Similar deviations in terms of regression and quantification bias were observed when analytes were eluted with MeOH through other types of RP columns. This indicates that further optimization of other parameters relating to the chromatography and mass spectrometer should be performed before validation.
59

Simulação numérica tridimensional do campo médio do escoamento em uma comporta segmento invertida

Dalla Corte, Marcelo 08 1900 (has links)
Submitted by William Justo Figueiro (williamjf) on 2015-06-16T23:47:58Z No. of bitstreams: 1 27.pdf: 3460975 bytes, checksum: 6fb4884eb12bbee8490b27b6414b47c0 (MD5) / Made available in DSpace on 2015-06-16T23:47:58Z (GMT). No. of bitstreams: 1 27.pdf: 3460975 bytes, checksum: 6fb4884eb12bbee8490b27b6414b47c0 (MD5) Previous issue date: 2013-08 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / FINEP - Financiadora de Estudos e Projetos / Furnas Centrais Elétricas / Comportas segmento invertidas são frequentemente utilizadas no controle do enchimento e esgotamento de eclusas de navegação de alta queda. Durante o período de abertura, altas velocidades e flutuações de pressão ocorrem a jusante destas comportas, o que aumenta o potencial para a ocorrência de cavitação no escoamento. Neste trabalho buscou-se analisar por meio de simulação numérica as características do escoamento a jusante de uma comporta segmento invertida. O modelo matemático é bifásico, tridimensional e composto pelas equações da conservação da massa, quantidade de movimento, fração volumétrica e equações do modelo de turbulência. O modelo computacional foi desenvolvido com o software comercial ANSYS-CFX, com malha computacional do tipo hexaédrica. Perfis de pressões no teto e na base do conduto a jusante da comporta foram utilizados para validação do modelo numérico com resultados experimentais, provenientes de estudos realizados pelo IPH-UFRGS (Instituto de Pesquisas Hidráulicas da Universidade Federal do Rio Grande do Sul). A comparação entre os resultados mostrou que o modelo numérico reproduz com boa precisão as principais características do escoamento médio observado no modelo experimental. Os coeficientes hidráulicos calculados para os resultados numéricos também mostraram boa concordância com os resultados do modelo experimental e com os disponíveis na literatura. A análise do campo de pressões mostrou que as pressões mínimas encontram-se sob a borda da comporta. Além disso, verificou-se por meio do campo de tensões cisalhantes na base do conduto e por meio de vetores de velocidade um padrão de escoamento tridimensional no jato a jusante da comporta, caracterizado pela presença de regiões de rotação próximo da base e das paredes. / Reversed Tainter gates are often used to control the filling and emptying of high lift navigation locks. During the opening period, high velocities and pressure fluctuations occur downstream the gates, which increases the potential for the occurrence of cavitation in the flow. In this work we seek to analyze by means of numerical simulation the characteristics of the flow downstream of a reversed Tainter gate. The computational model was validated by comparing the profiles of pressure of the roof and at the base of the conduit downstream of the gate with the average pressure profiles obtained in an experimental model from studies conducted by IPH-UFRGS. A comparison of the results showed that the model reproduced with good accuracy the main flow characteristics observed in experimental medium. The hydraulic coefficient calculated for the numerical results also showed good agreement with experimental results and those available in the literature. The analysis of the pressure field showed that the minimum pressures are under the edge of the gate. Furthermore, it was found by means of the shear stress at the base of the conduit and through velocity vector a threedimensional pattern in the jet flow downstream of the gate, characterized by the presence of vortex near the base and walls.
60

La subsidiarité inversée en droit européen : contribution à l’étude des rapports de systèmes entre les ordres juridiques nationaux et l’ordre juridique de l’Union européenne / The reverse subsidiarity : contribution to the study of relationships between systems of national legal order and the legal order of the European Union

Tetang, Franc de Paul 07 December 2012 (has links)
Depuis le traité de Maastricht, le principe de subsidiarité fait l'objet d'une littérature remarquable tant du point de vue quantitatif que du point de vue qualitatif. La doctrine s'y intéresse au point de bâtir une « Europe de la subsidiarité » dont la finalité est la présentation des différentes formes et des diverses applications de la subsidiarité dans l'articulation des ordres juridiques internes et des ordres juridiques européens. Le résultat d'une telle construction intellectuelle brille cependant par l'absence remarquable, dans l'Europe unionaire, d'une variante de la subsidiarité qui bien que ne portant pas le nom a pourtant déjà dépassé le cap de « la vie cachée » pour celui de « la vie publique ». De ce fait, elle mérite d'être aussi intégrée dans cette « Europe de la subsidiarité » au rang de principe de la structure constitutionnelle du processus d'intégration. Cette autre forme de subsidiarité qu'est la subsidiarité inversée, est manifestement présente dans l'Union européenne où elle peut se définir soit comme la possibilité que se réservent certains États membres de l'Union d'intervenir en cas de défaillance de l'institution supranationale dans un domaine précis en l'occurrence les droits fondamentaux, soit comme une action nationale destinée à contrôler, toujours à titre subsidiaire, la qualité du droit « venu d'ailleurs » et ce, afin de garantir le respect de la « constitution fondamentale européenne ». Pourtant, elle n'a jamais fait l'objet d'une conceptualisation en tant que principe au sens de « proposition purement descriptive par laquelle le juriste rend compte d'une idée ou d'une tendance du droit ».Toutefois, la doctrine européaniste n'ignore pas / Since Maastricht Treaty, the principle of subsidiarity is the subject of many striking written works in quantity as well as in quality. It's so interesting for the doctrine that an “Europe of subsidiarity” has been built a in order to describe the different forms and applications of the subsidiarity in the connection between the national and European juridical orders. The result of this intellectual construction shines by the notable lack, in the “Europe unionaire”, of a variation on the subsidiarity. This one came through a “secret life” to a “public life” and has to be integrated in this “Europe of the subsidiarity” like a real principle of the constitutional structure of the process of integration. This other form of subsidiarity is the reversed subsidiarity and is plainly found in the European Union. It can either be defined as the possibility for some member States to interfere in case of failure in supranational institution in a limited area (here the fundamental rights), or as a national activity in order to control, always in a subsidiary way, the quality of the right “coming from somewhere else” in order to guaranty the respect of the “fundamental European constitution”. Yet there never was any conceptualization of it as an “only descriptive proposition through which the jurist is able to give a move of the law”. However the Europeanist doctrine can't deny it because the reversed subsidiarity is recognized (as a simple phenomenon this time) by many authors seeing only a way of breaking, a way to make the juridical construction more fragile or complicated. But a detailed analysis of its functions makes it possible to defend the contrary and to assert that the rev

Page generated in 0.0404 seconds