- 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.
Search results
Showing 91 to 98 of 98 (0.066 seconds)Spelling suggestions: "subject:"conergy bydistribution"" "subject:"conergy 5mmdistribution""
| 91 |
Magnetfält i elkraftanläggningar : Ett projekteringsverktyg i Excel för bedömning av magnetfält från elkraftsutrustning på lågspänningssidan / Magnetic field in electric power equipment : A planning tool in Excel for estimation of magnetic fields from power components on low voltage systemsPapp Aminnejad, Benjamin, Wieweg, Daniel January 2015 (has links)
Exponering av det lågfrekventa ELF (Extremely low frequency) magnetfältet som genereras vid dagens elnät är något som är relativt nytt för människokroppen och den ökar ständigt i och med den tekniska utvecklingen. Eftersom det inte finns ett klart svar på hur fältet påverkar kroppen så tillämpas försiktighet för att hålla exponeringsnivåerna nere och försäkra sig om att ingen skada sker. Med hjälp av tidigare forskning inom området och uppmätta värden från olika anläggningar samt överslagsberäkningar har ett verktyg i Excel tagits fram för att kunna uppskatta magnituden av magnetfältet. Verktyget innehåller information om styrkan på magnetfältet från transformatorer, ställverk, elcentraler, kraftledningar och kanalskenor. Användaren skriver in ett antal parametrar för att få utdata om hur starkt magnetfältet är på olika avstånd ifrån källan. Detta presenteras i form av en tabell och en graf för respektive utrustning. Eftersom magnetfält alstras beroende på strömmens riktning, påverkar själva geometrin i olika elanläggningar magnetfältets styrka. För att beräkna exakta värden krävs då avancerade simuleringsprogram. Med detta verktyg kan projektörer redan vid ett tidigt skede uppskatta magnetfältet. / The exposure of ELF (Extremely low frequency) magnetic field generated by today’s electrical power system, is something that is relatively new to the human body and it is constantly increasing as more technology is developed. As there is no clear answer on how the field actually affects the body, a measure of caution is applied to ensure that the exposure levels are kept down to make sure no harm is done. With the help of previous research in the field, measured values from different locations and approximate calculations, a tool was developed in Excel to estimate the magnitude of the magnetic fields. The tool provides information about the magnitude of magnetic fields from transformers, switchgears, switchboards, powerlines and busbars. The user enters a number of parameters and the tool provides output data with the magnitude of the magnetic field at different distances from the source. This is presented in the form of a table and a graph for each equipment. Since the magnetic field is generated depending on the currents direction, the actual geometry of the electrical system needs to be taken in consideration when calculating the exact magnetic field. This requires an advanced simulation software to be accurate. With this tool, designers have the opportunity to estimate the magnetic fields at an early stage of development.
|
| 92 |
Magnetfält i elkraftanläggningar : Ett projekteringsverktyg i Excel för bedömning av magnetfält från elkraftsutrustning på lågspänningssidan / Magnetic field in electric power equipment : A planning tool in Excel for estimation of magnetic fields from power components on low voltage systemsPapp Aminnejad, Benjamin, Wieweg, Daniel January 2015 (has links)
Exponering av det lågfrekventa ELF (Extremely low frequency) magnetfältet som genereras vid dagens elnät är något som är relativt nytt för människokroppen och den ökar ständigt i och med den tekniska utvecklingen. Eftersom det inte finns ett klart svar på hur fältet påverkar kroppen så tillämpas försiktighet för att hålla exponeringsnivåerna nere och försäkra sig om att ingen skada sker. Med hjälp av tidigare forskning inom området och uppmätta värden från olika anläggningar samt överslagsberäkningar har ett verktyg i Excel tagits fram för att kunna uppskatta magnituden av magnetfältet. Verktyget innehåller information om styrkan på magnetfältet från transformatorer, ställverk, elcentraler, kraftledningar och kanalskenor. Användaren skriver in ett antal parametrar för att få utdata om hur starkt magnetfältet är på olika avstånd ifrån källan. Detta presenteras i form av en tabell och en graf för respektive utrustning. Eftersom magnetfält alstras beroende på strömmens riktning, påverkar själva geometrin i olika elanläggningar magnetfältets styrka. För att beräkna exakta värden krävs då avancerade simuleringsprogram. Med detta verktyg kan projektörer redan vid ett tidigt skede uppskatta magnetfältet. / The exposure of ELF (Extremely low frequency) magnetic field generated by today’s electrical power system, is something that is relatively new to the human body and it is constantly increasing as more technology is developed. As there is no clear answer on how the field actually affects the body, a measure of caution is applied to ensure that the exposure levels are kept down to make sure no harm is done. With the help of previous research in the field, measured values from different locations and approximate calculations, a tool was developed in Excel to estimate the magnitude of the magnetic fields. The tool provides information about the magnitude of magnetic fields from transformers, switchgears, switchboards, powerlines and busbars. The user enters a number of parameters and the tool provides output data with the magnitude of the magnetic field at different distances from the source. This is presented in the form of a table and a graph for each equipment. Since the magnetic field is generated depending on the currents direction, the actual geometry of the electrical system needs to be taken in consideration when calculating the exact magnetic field. This requires an advanced simulation software to be accurate. With this tool, designers have the opportunity to estimate the magnetic fields at an early stage of development.
|
| 93 |
Vibrational Energy Distribution, Electron Density and Electron Temperature Behavior in Nanosecond Pulse Discharge Plasmas by Raman and Thomson ScatteringRoettgen, Andrew M. 22 May 2015 (has links)
No description available.
|
| 94 |
Multiwavelength Analysis of the Gamma-Ray Blazar PKS 0528+134 in QuiescencePalma Cruz, Norman I. January 2010 (has links)
No description available.
|
| 95 |
Identification of dynamic oxygen access channels in 12/15-lipoxygenase / molecular dynamics simulations and free-energy landscapesSaam, Jan 04 April 2008 (has links)
Zellen enthalten zahlreiche Enzyme, deren Reaktionen von molekularem Sauerstoff abhängen. Oft sind deren aktive Zentren tief im inneren des Proteins verborgen, was die Frage nach spezifischen Zugangskanälen, die den Sauerstoff gezielt zum Ort der Katalyse leiten, aufwirft. In der vorliegenden Arbeit wird dies am Beispiel der 12/15-Lipoxygenase, als ein typisches Beipiel Sauerstoff verbrauchender Enzyme, untersucht. Die Sauerstoffverteilung innerhalb des Proteins wurde bestimmt und mögliche Routen für den Sauerstoffzugang definiert. Zu diesem Zweck wurden theoretische Untersuchungen eng mit Experimenten verzahnt. Zuerst wurden Molekulardynamik Simulationen des Proteins in Lösung durchgeführt. Aus den Trajektorien konnte die dreidimensionale Verteilung der Freien Enthalpie für Sauerstoff berechnet werden. Die Analyse der günstigsten Pfade in dieser Energielandschaft führte zur Identifikation von vier Sauerstoffkanälen im Protein. Alle Kanäle verbinden die Proteinoberfläche mit einem Gebiet hoher Sauerstoffaffinität am aktiven Zentrum. Diese Region liegt bezüglich des Substrats gegenüber dem Eisenzentrum, wodurch eine strukturelle Erklärung für die Reaktionsspezifität des Enzyms gegeben ist. Der katalytisch bedeutsamste Weg des Sauerstoffs kann durch L367F Austauschmutation blockiert werden, was zu einer stark erhöhten Michaelis-Konstante für Sauerstoff führt. Diese experimentell nachgewiesene Blockade konnte, mit Hilfe entsprechender Molekulardynamik Simulationen, durch eine Umordnung eines Wasserstoffbrücken-Netzwerks von Wassermolekülen innerhalb des Protein im Detail erklärt werden. Die Ergebnisse ermöglichen den Schluss, dass die Hauptroute für Sauerstoff zum aktiven Zentrum des Enzyms einem Kanal folgt, der aus vorübergehend verbundenen Hohlräumen besteht. Hierbei unterliegt das Öffnen und Schließen des Kanals der Dynamik der Proteinseitenketten. / Cells contain numerous enzymes utilizing molecular oxygen for their reactions. Often, their active sites are buried deeply inside the protein which raises the question whether there are specific access channels guiding oxygen to the site of catalysis. In the present thesis this question is investigated choosing 12/15-lipoxygenase as a typical example for such oxygen dependent enzymes. The oxygen distribution within the protein was determined and potential routes for oxygen access were defined. For this purpose an integrated strategy of structural modeling, molecular dynamics simulations, site directed mutagenesis, and kinetic measurements has been applied. First, molecular dynamics simulations of the protein in solution were performed. From the trajectories, the 3-dimensional free-energy distribution for oxygen could be computed. Analyzing energetically favorable paths in the free-energy map led to identification of four oxygen channels in the protein. All channels connect the protein surface with a zone of high oxygen affinity at the active site. This region is localized opposite to the non-heme iron providing a structural explanation for the reaction specificity of this lipoxygenase isoform. The catalytically most relevant path can be obstructed by L367F exchange which leads to a strongly increased Michaelis constant for oxygen. This experimetally proven blocking mechanism can, by virtue of molecular dynamics studies, be explained in detail through a reordering of the hydrogen bonding network of water molecules. As a conclusion, the results provide strong evidence that the main route for oxygen access to the active site of the enzyme follows a channel formed by transiently interconnected cavities whereby the opening and closure is governed by sidechain dynamics.
|
| 96 |
[en] ION DESORPTION DESCRIBED BY AN EXTENDED NUCLEAR TRACK MODEL: APPLICATION TO WATER ICE CLUSTERS / [es] EXTENSIÓN DEL MODELO DE TRAZO NUCLEAR PARA DESCRIBIR LA DESORCIÓN IÓNICA: APLICACIÓN A LOS AGLOMERADOS DE HIELO / [pt] EXTENSÃO DO MODELO DE TRAÇO NUCLEAR PARA DESCREVER A DESSORÇÃO IÔNICA: APLICAÇÃO AOS AGREGADOS DE ÁGUAPETER DARWIN IZA TOAPANTA 18 October 2006 (has links)
[pt] A dessorção de íons secundários induzida por impacto de
projéteis velozes
é um fenômeno de interesse tanto da pesquisa fundamental
dos processos de
colisão quanto da Física de Superfícies, Biociência e
Astrofísica. O modelo
teórico de dessorção iônica induzida por elétrons baseado
na formação de
um traço nuclear é aprimorado no presente trabalho.
Considera-se que o
traço seja composto por um infratraço de carga positiva e
um ultratraço de
carga negativa. Ao chegarem na superfície do sólido, os
elétrons secundários
emanados do infratraço geram íons que são em seguida
acelerados por ação
do campo elétrico produzido pelos traços. Os dados
experimentais escolhidos
para testar o modelo correspondem à dessorção iônica
induzida em filmes finos
de gelo (H2O) por íons de nitrogênio de 1,7 MeV. As
velocidades de emissão
e as massas dos íons dessorvidos foram determinadas pela
técnica de tempo-
de-vôo. Empregou-se um detector de íons composto por um
par de placas de
microcanais e por um anodo sensível à posição de impacto
dos íons. Os dados
obtidos pela técnica XY-TOF mostram diferenças de
simetrias na distribuição
angular dos íons secundários. Em especial, observou-se
emissão quase isotrópica
dos agregados leves em relação a normal à superfície,
contrastando com a dos
agregados pesados que apresenta distribuição assimétrica
atribuída a um efeito
de memória da direção do projétil durante a emissão
iônica. Um acordo entre
os resultados do modelo e os dados experimentais é
considerado razoáve / [en] Secondary ion desorption induced by impact of fast
projectiles is an
important phenomenon not only because it is directly
connected to atomic
collision processes in solids, but also to practical
implications in the Physics
of Surfaces, Bioscience and Astrophysics. A theoretical
model describing the
desorption induced by secondary electron (SEID) produced
in nuclear tracks is
extended in the present work. It considers that the
nuclear track is composed
by a positive charged infratrack and a negative charged
ultratrack. Secondary
electrons emanated from infratrack reach the surface of
the solid and generate
molecular ions which are accelerated by an electric field
produced by the
track. The experimental data obtained by a 1.7 MeV
nitrogen beam inducing
electronic sputtering on condensed water target are used
to test the SEID
model. The initial velocity vectors and the masses of the
emitted ions were
obtained by the time-of-fight technique equipped with a
position sensitive
delay line detector XY-TOF. The data obtained by the
technique show
differences of symmetries in the angular distribution of
the secondary ions.
In particular, isotropic emission was observed for light
clusters in relation
to normal to the surface, contrasting with heavy clusters
that show an
asymmetric distribution attributed to nuclear track memory
direction during
the emission. The agreement between the model results and
experimental data
is considered reasonable. / [es] La desorción de iones secundarios a partir de la
incidencia de proyectiles
rápidos en superficies es un fenómeno de gran interés
científico en áreas de
Física de Colisiones (interacciones ión-sólido), Física de
Superficies, Bio-ciencia
y Astrofísica. En esta Tesis fue desarrollado un modelo
teórico para describir
el proceso de desorción iónica inducida por los electrones
emitidos durante
la formación del trazo nuclear. El modelo considera que
el trazo trazo
nuclear. Las predicciones del modelo fueron comparadas con
las mediciones
de las especies emitidas por la incidencia de iones de
nitrógeno de 1,7 MeV
en películas delgadas de hielo (H2O). Las especies emitidas
y sus velocidades
iniciales fueron determinadas utilizando la técnica tiempo
de vuelo (TOF).
Fue utilizado un detector formado por un par de placas de
micro canales
con un ánodo sensible a la posición de impacto de los iones
(técnica XY-TOF). Dos tipos de distribuciones angulares de
los iones secundarios fueron
observadas: isotrópica para masas pequeñas y anisotrópica
para masas grandes.
La distribución angular de masas grandes es
preferencialmente simétrica a la
dirección de incidencia del proyectil con respecto a la
normal a la superficie y se
debe al efecto de memoria del trazo nuclear sobre la
dirección de incidencia
del proyectil. Los resultados teóricos y los valores
experimentales concuerdan
parcialmente.
|
| 97 |
Development and improvement of methods for characterization of HPLC stationary phasesUndin, Torgny January 2011 (has links)
High Performance Liquid Chromatography (HPLC) is a widely used tech-nique both for detecting and purifying substances in academy and in the industry. In order to facilitate the use of, and knowledge in HPLC, character-ization of stationary phases is of utmost importance. Tailor made characteri-zation methods and workflows are steadily increasing the speed and accura-cy in which new separation systems and methods are developed. In the field fundamental separation science and of preparative chromatography there is always the need for faster and more accurate methods of adsorption isotherm determination. Some of that demand are met with the steadily increase of computational power, but the practical aspects on models and methods must also be further developed. These nonlinear characterization methods will not only give models capable of describing the adsorption isotherm but also actual values of local adsorption energies and monolayer saturation capacity of an individual interaction sites etc.The studies presented in this thesis use modern alkali stable stationary phas-es as a model phase, which will give an insight in hybrid materials and their separation mechanism. This thesis will include an update and expansion in using the Elution by Characteristic Points (ECP) method for determination of adsorption isotherms. The precision is even further increased due to the ability to use slope data as well as an increase in usability by assigning a set of guidance rules to be applied when determine adsorption isotherms having inflection points. This thesis will further provide the reader with information about stationary phase characterization and the power of using existing tech-niques; combine them with each other, and also what the expansion of meth-ods can revile in terms of precision and increased usability. A more holistic view of what benefits that comes with combining a non-linear characteriza-tion of a stationary phase with more common linear characterization meth-ods are presented.
|
| 98 |
Photodissoziation von Halogenwasserstoff- und orientierten Wasserstoff-Edelgas-Halogen-Molekülen in Clusterumgebungen / Photodissociation of hydrogen halide and oriented hydrogen-rare gas-halogen molecules in cluster environmentsNahler, Nils Hendrik 28 October 2002 (has links)
No description available.
|
Page generated in 0.0886 seconds