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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.
1

Analytic modelling of Rosetta Langmuir probe measurements based on SPIS simulations

Hånberg, Christian January 2011 (has links)
The Rosetta spacecraft is on route to rendezvous with the comet 67P/ Churyomov-Gerasimenko. One of the instruments onboard is the Langmuir probe instrument (LAP) developed by the Swedish Institute of Space Physics. The LAP includes two spherical probes used to measure a number of properties of the surrounding plasma. One measured property is the plasma density for which the spacecraft potential is a good proxy. By the determining the potential between spacecraft and Langmuir probe, the spacecraft potential can be measured. But such measurements are sometimes disturbed by the potential from the spacecraft itself, the influence from photoemitted electrons and the solar wind wake behind Rosetta. In order to correct for the errors caused by spacecraft-plasma interaction in the solar wind a model depending on the spacecraft (and Langmuir probe) orientation is developed. The data is obtained from three-dimensional simulations of Rosetta, with varying plasma parameters, using the software SPIS (Spacecraft Plasma Interaction System). Least squares fitting with a set of basis functions then provide the input for a parametric modelling. The developed model makes it possible to estimate the influence of each of the disturbing effects. The developed model gives good fits to data obtained in SPIS simulations. The two angular dependent factors, modelling perturbation on potential measurements caused by photoelectrons and wake effects, show errors below the 100 mV level in all cases. The model describing the influence from spacecraft potential is slightly less accurate, with errors at or below the 400 mV level in all relevant cases.
2

Numerical simulation of Rosetta Langmuir Probe

Johansson, Fredrik January 2013 (has links)
By modelling and simulating the ESA spacecraft Rosetta in a plasma with solar wind parameters, and simultaneously simulating a particle detection experiment of Langmuir probe voltage sweep type using the ESA open source software SPIS Science, we investigate the features of Rosetta’s envi- ronment in the solar wind and the e↵ect of photoemission from the space- craft on the measurements made by the Langmuir Probe instrument on board Rosetta. For a 10 V positively charged spacecraft and Maxwellian distributed photoelectron emission with photoelectron temperature, Tf = 2 eV in a plasma of typical 1 AU solar wind parameters: ne = 5 ⇥ 106 m3, vSW = 4 ⇥ 105 m/s, Te = 12 eV, Tion = 5 eV, we detect a floating potential of 6.4 (± 0.2) V at Langmuir probe 1. Two models used in literature on photoemission was used and compared and we report a clear preference to the Maxwellian energy distribution of photoelectrons from a point source model with our simulation result.
3

Počítačové programy pro podporu auditu / Audit software

Krajčová, Lenka January 2011 (has links)
The goal of this thesis is to compare some of software products for audit. The thesis also contains a survey, which was conducted among auditors. The goal of this thesis was to find out, which types of software they use for audit.
4

Internal charging modelling of the AMBER instrument on-board Jason-3 spacecraft

Hacquart, Jeremie January 2020 (has links)
Internal charging is the accumulation of charged particles inside a material. Thisbuild up represents a serious hazard to satellites and instruments exposed to thespace environment. The Van Allen radiation belts constitute one of the worst spaceenvironments for satellites orbiting the earth. The energy of the electrons is higherthan in any earth orbit. Previous studies have noted the risk of internal charging in alow earth orbit or in geostationary orbit.The internal charging analysis of the AMBER instrument has been performed in amedium earth orbit. To run a relevant internal charging study, a whole dedicatedmodelling chain has been conducted. The instrument has been modelled with thecomputer-aided design software EDGE. The radiation transport analysis has beenperformed with the ESA/GRAS Monte Carlo-based software. The proper internalcharging analysis has been performed with the SPIS-IC software.Depending on various factors such as materials and shielding, the AMBER instrumentpresents few risks of electrostatic discharge. A wrong use of material can represent ahuge hazard in terms of internal charging. A thick shielding can lead to a higher riskof accumulation of charges due to a lower radiation induced conductivity. / Intern uppladdning är en ansamling av laddade partiklar inuti ett material. Denutgör en allvarlig fara för satelliter och instrument som exponeras för rymdmiljön.Strålningsbältena utgör en av de värsta rymdmiljöerna för satelliter som kretsarrunt jorden i detta avseende, pga de höga elektronenergierna. Tidigare studierhar visat på risken för intern uppladdning i låg omloppsbana runt jorden eller ien geostationär bana. Analysen av intern uppladdning av AMBER-instrumentethar här utförts för en medelhög omloppsbana. För att utföra en relevant studiehar en hel särskild modellkedja genomförts. Instrumentet har modellerats medden datorstödda designen EDGE. Strålningsanalysen har utförts med programvaranESA/GRAS MonteCarlo-baserade metod. En korrekt intern laddningsanalys harutförts med SPIS-IC-programvaran. Pga olika faktorer som material och skärmninghos AMBER-instrumentet är risken för elektrostatisk urladdning låg. En felaktiganvändning av material kan dock utgöra en stor fara när det gäller intern laddning. Entjock avskärmning kan leda till en högre risk för ackumulering av laddning på grundav en lägre strålningsinducerad ledningsförmåga.
5

Rosetta Langmuir probe performance

Johansson, Fredrik January 2013 (has links)
Several Langmuir probe voltage sweeps by a model of the ESA spacecraft Rosetta was simulated in a plasma with solar wind parameters using the ESA open source software SPIS 5. The simulations were carried out to in- vestigate the features of the spacecraft’s environment in the solar wind and the effect of photoemission from the spacecraft surface on the measurements made by the Langmuir probes on board Rosetta. We report a best fit to an existing probe sweep result in the solar wind near the Earth at 1 AU from 9 Nov 2009 for a 4 million particle simulation in SPIS of an 8 V positively charged spacecraft with the following parameters: Tph = 2 eV, Te = 12 eV, Ti = 5 eV, ne = 5 cm−3. We also report that the spacecraft is shielding the Langmuir probes on Rosetta from plasma electrons, and particularly low energy electrons. In one instance, this blocking is shown to lead to an over- estimation of solar wind electron temperature by 12% and underestimate the plasma density by 24% by the Langmuir Probe for a +10 V charged spacecraft in ne= 5 cm−3, Te = 12 eV solar wind. Two models used in lit- erature on photoemission, one for isotropical emission from a plane and the other for radial emission from a point, was used and compared. We report a clear preference to the approximation of a Maxwellian energy distribution of photoelectrons emitted radially from a point source model with our sim- ulation result on the Langmuir Probe aboard Rosetta. We also report the solar aspect angle dependence on the plasma potential and plasma density result, which are in overall agreement with Rosetta measurements from the second Earth fly-by.
6

Étude de l'influence de la propreté électrostatique du satellite sur les mesures du champ électrique basse fréquence de TARANIS / Study of the influence of the electrostatic cleanliness of the satellite on the measures of the low frequency electric field TARANIS

Jorba Ferro, Oriol 17 December 2018 (has links)
Les satellites en orbite terrestre se déplacent dans le plasma ionosphérique, un mélange de particules chargées, et éventuellement de particules neutres. Des électrons et des ions issus de ce plasma, ainsi que les émissions Ultra-Violets(UV) en provenance du soleil, interagissent avec les surfaces du satellite et modifient sa charge électrostatique. Cette chargement peut induire elle-même des décharges électrostatiques aux conséquences allant de perturbations électromagnétiques (fausses commandes par exemple) à la perte du satellite. En orbites de basse altitude (LEO) l'énergie cinétique et thermique du plasma est généralement faible et donc, les satellites vont rarement présenter des décharges importantes. Néanmoins, les missions scientifiques qui embarquent des instruments très performants et précis peuvent être affectées par cette interaction satellite-plasma-émissions UV. Cette thèse s'intéresse particulièrement à ces phénomènes de charge des structures externes du satellite et à l'impact de ce chargement sur les mesures scientifiques effectuées à bord, i.e. mesures du champ électrique et de la densité du plasma thermique. / Earth-orbiting satellites travel in ionospheric plasma, a mixture of charged particles, and possibly neutral particles. Electrons and ions from this plasma, as well as Ultra-Violet (UV) emissions from the sun, interact with the surfaces of the satellite and modify its electrostatic charge. This loading can itself induce electrostatic discharges to the consequences ranging from electromagnetic disturbances (false commands for example) to the loss of the satellite. In low-Earth orbits (LEO), the kinetic and thermal energy of the plasma is generally low and therefore satellites rarely exhibit large discharges. Nevertheless, scientific missions that carry high-performance and accurate instruments can be affected by this satellite-plasma-UV-emissions interaction. This thesis is particularly interested in these phenomena of charge of the external structures of the satellite and the impact of this load on the scientific measurements carried out on board, i.e. measures of the electric field and the density of the thermal plasma.
7

Vztah alkoholu a vražd páchaných ženami v ČR - případová studie / The relationship of alcohol and murders of women in the Czech Republic - Case Studies

Broklová, Lada January 2014 (has links)
OF THE THESIS Name: Bc. Lada Broklová Specialization: Addictology Head of the thesis: Mgr. Jaroslav Šejvl Opponent: JUDr. Michaela Štefunková, Ph.D. Pages: 91 The name of the thesis: THE RELATIONSHIP OF ALCOHOL AND MURDERS OF WOMEN IN THE CZECH REPUBLIC - CASE STUDIES Abstract: The aim of the thesis is to analyze committing murders by women who are under the influence of alcohol. The theoretical part focuses on explaining the concepts and characteristics of the alcohol, crime, violent crime and the concept of alcohol as a criminogenic factor. There are the chapters specifically aimed at women and alcohol and women-murderess. The first part summarizes the essentials of what was published in this issues. The work is accompanied by several illustrative charts. The practical part focuses on qualitative research using methods of analysis of court files. The work is conceived as case study, detailed studies of three cases of murders committed by women under the influence of alcohol. Using the method of trapping patterns alcohol career perpetrators, the effect of alcohol on the offense, personality structure of perpetrator and the crime were monitored. It was found that the examined cases are without departing from the cases commonly described in the literature. Perpetrators at the time of crimes were...
8

Spis auditora v praktické aplikaci / Audit documentation in practical application

Kraftová, Zdeňka January 2009 (has links)
This thesis focuses on audit documentation in practice. The main aim of thesis is give the comprehensive requirements list on audit documentation. This include international standard on auditig, the Law on auditors and the Law on accounting. These requirements are describe on praktice example. There is include historici development in the Czech Reublic and in the word.
9

Ekman, Daniel January 2007 (has links)
<p>Datum:</p><p>10 maj 2007</p><p>Uppsatsnivå:</p><p>C-uppsats i Industridesign, Kt2130 – Innovativ design, 20 poäng</p><p>Författare:</p><p>Daniel Ekman</p><p>Kungsgatan 24A</p><p>632 20 Eskilstuna</p><p>073 – 952 79 06</p><p>Titel:</p><p>iPower – Spisvakten</p><p>Bakgrund:</p><p>Under ett studiebesök på Hjälpmedelsinstitutet fick jag insikt om olika problem med äldres kvarboende. Ett av de största problemen är brand-risken vid användning av spisen. En person med ett kognitivt funk-tionshinder kan börja koka vatten i en kastrull och gå där ifrån för att göra något annat medans vattnet kokar och helt glömma bort kastrullen. Varvid en brand kan uppstå som för med sig stora personliga och ekonomiska lidanden. Ett hjälpmedel för detta är en så kallad spisvakt eller timer. De fungerar genom att de bryter strömmen när faran för brand är nära.</p><p>Syfte:</p><p>I kursen Innovativ design har jag fått i uppdrag att vidareutveckla ett redan befintligt hjälpmedel. Valet föll på en spisvakt</p><p>Tillvägagångssätt:</p><p>Jag har valt att utgå från personer som har direktkontakt med proble-met. I det här fallet tre personer på tre olika företag/organisationer. Jag intervjuade en person inom varje företag/organisation. Jag har även ar-betat med litteraturstudier, utvärderat idéer och har slutligen tagit fram en design.</p><p>Slutsats:</p><p>Projektet har mynnat ut i en produkt som har en yttre design som tilltalar ögat och som klart och tydligt visar vad man skall göra och visar om produkten är påslagen. Användaren får en omedelbar feedback</p><p>Nyckelord:</p><p>Spisvakt, timer, kognitiva funktionshinder, brand, spis</p>
10

Ekman, Daniel January 2007 (has links)
Datum: 10 maj 2007 Uppsatsnivå: C-uppsats i Industridesign, Kt2130 – Innovativ design, 20 poäng Författare: Daniel Ekman Kungsgatan 24A 632 20 Eskilstuna 073 – 952 79 06 Titel: iPower – Spisvakten Bakgrund: Under ett studiebesök på Hjälpmedelsinstitutet fick jag insikt om olika problem med äldres kvarboende. Ett av de största problemen är brand-risken vid användning av spisen. En person med ett kognitivt funk-tionshinder kan börja koka vatten i en kastrull och gå där ifrån för att göra något annat medans vattnet kokar och helt glömma bort kastrullen. Varvid en brand kan uppstå som för med sig stora personliga och ekonomiska lidanden. Ett hjälpmedel för detta är en så kallad spisvakt eller timer. De fungerar genom att de bryter strömmen när faran för brand är nära. Syfte: I kursen Innovativ design har jag fått i uppdrag att vidareutveckla ett redan befintligt hjälpmedel. Valet föll på en spisvakt Tillvägagångssätt: Jag har valt att utgå från personer som har direktkontakt med proble-met. I det här fallet tre personer på tre olika företag/organisationer. Jag intervjuade en person inom varje företag/organisation. Jag har även ar-betat med litteraturstudier, utvärderat idéer och har slutligen tagit fram en design. Slutsats: Projektet har mynnat ut i en produkt som har en yttre design som tilltalar ögat och som klart och tydligt visar vad man skall göra och visar om produkten är påslagen. Användaren får en omedelbar feedback Nyckelord: Spisvakt, timer, kognitiva funktionshinder, brand, spis

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