Tesis: "Formation of the solar system"

1

Crida, Aurélien. "Planetary migration in solar system formation". Nice, 2006. http://www.theses.fr/2006NICE4076.

Resumen

Planetary migration seems to be unavoidable during planet formation in protoplanetary disks. Gravitational interactions between the planet embryos and the gas disk make the angular momentum of the embryo decrease, so that it spirals towards the central star. As the migration timescale is shorter than the disk life time, no planet should survive (chapters 1 and 2). In this thesis, we try to find mechanisms that prevent or slow down migration. In chapter 3, we show that a jump in the gas disk density stops migration and acts like a planet trap. Trapped there, a massif solid core may accrete a gaseous atmosphere and give birth to a giant planet. The planet is then massive enough to repel the gas and open a gap around its orbit. Through analysis of computer simulations, we enlighten the role of pressure effects in this process in chapter 4 ; a new generalized gap opening criterion is derived. After the presentation of a new, reliable and performing algorithm for numerical simulations in chapter 5, we use it in chapter 6 to study the migration of a giant planet and its influence on the disk evolution. The formation of a cavity appears to be less easy than previously expected, but we find a way of preventing migration. Last, in chapter 7, we focus on the case of Jupiter and Saturn, and we find in which conditions the interactions between both planets prevent their migration
La migration planétaire est un phénomène apparemment inévitable lors de la formation des planètes dans les disques protoplanétaires. Les interactions gravitationnelles entre les embryons de planète et le disque de gaz font décroître le moment cinétique de l'embryon, qui spirale vers l'étoile centrale. Le temps de migration étant plus court que la durée de vie du disque, aucune planète ne devrait survivre (chapitres 1 et 2). Dans cette thèse, nous essayons de trouver des mécanismes qui empêchent ou ralentissent la migration. Dans le chapitre 3, nous montrons qu'un saut dans le profil de densité du disque de gaz bloque la migration et agit comme un piège à planète. Ainsi bloqué, un coeur solide massif peut accrèter une atmosphère gazeuse et devenir une planète géante. La planète est alors assez massive pour repousser le gaz et ouvrir un sillon autour de son orbite. En analysant des simulations numériques, nous mettons en évidence le rôle des effets de pression dans ce processus dans le chapitre 4; un nouveau critère unifié d'ouverture du sillon en découle. Après la présentation dans le chapitre 5 d'un nouvel algorithme fiable et performant pour réaliser des simulations numériques, nous l'utilisons dans le chapitre 6 pour étudier la migration d'une planète géante et son impact sur l'évolution du disque. La formation d'une cavité s'avère moins facile que prévu, mais une possibilité d'arrêter la migration apparaît. Enfin, dans le chapitre 7, nous étudions le cas de Jupiter et Saturne, et trouvons dans quelles conditions les interactions entre les deux planètes en empêchent la migration

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Cyr, Kimberly Ellen 1964. "The distribution of water in the solar nebula: Implications for solar system formation". Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/288870.

Texto completo

Resumen

Water is important in the solar nebula both because it is extremely abundant and because it condenses out at 5 AU, allowing all three phases of H₂O to play a role in the composition and evolution of the solar system. In this work, a thorough examination of the inward radial drift of ice particles from 5 AU is undertaken. Drift model results are then linked to the outward diffusion of vapor, in one overall model which is numerically evolved over the lifetime of the nebula. Results of the model indicate that while the inner nebula is generally depleted in water vapor, there is a zone in which the vapor is enhanced by ∼40-100%, depending on the choice of ice grain growth mechanisms and rates. This enhancement peaks in the region from 0.1-2 AU and gradually drops off out to 5 AU. Conversely, ice abundance is enhanced over 3-5 AU. Representative hot (early) and cool (later) conditions during the quiescent phase of nebular evolution are examined. Additionally, the effect of the radial dependence of water depletion on nebular chemistry is quantified using a chemical equilibrium code that computes abundances of nebular elements and major molecular C, N, S, etc. species over a range of temperatures. In particular, changes in the local C/O ratio and organics abundance due to the radially dependent decrease in oxygen fugacity are tracked and plotted. Generally, the diffusion-drift model results in a more complex water distribution than previous models, with both radial and temporal variations in the C/O ratio which produce both relatively oxidizing and reducing nebular conditions across 1-5 AU. Depending on the value assumed for the solar C/O ratio, modest to significant enhancements of CH₄ and other organics abundances are produced in the inner nebula. These results coupled with the revised ice distribution may explain the radial signatures of hydration detections and darkening in asteroids, and perhaps the oxidation states of enstatite chondrites. The results also indicate that the inner nebula could have supplied organics and water to the terrestrial planets, as well as possibly to Europa and beyond, via outward mixing processes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Elliott, Garrett T. "Detecting the debris of solar system formation via stellar occultation". Connect to resource, 2008. http://hdl.handle.net/1811/32191.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Mehta, Anand Vivek 1966. "The role of vortices in the formation of the solar system". Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50500.

Texto completo

Resumen

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1998.
Includes bibliographical references (p. 117-119).
An important part of explaining planet formation is understanding how small particles accumulate into larger bodies. Gas vortices are suggested as a mechanism to enhance the coagulation of dust particles in the solar nebula. An inviscid, barotropic, two-dimensional form of the vorticity equation is derived to study the gas flow. A pseudospectral numerical model uses this equation to calculate the evolution of the vorticity field. The calculations show that locally prograde elliptical vortices with the major axis parallel to the angular axis can persist for at least 103 years with less than 1% change in peak vorticity. The shape of the vortex depends on the strength, similar to analytical expressions for elliptical vortices in a linear shear. Stronger vortices are rounder while weaker vortices are elongated; With ratios of the peak vorticity to the background vorticity of 1.0 and 0.2, the aspect ratios are approximately 0.5 and 0.25. The vortex area is mostly constant, and the linear dimensions change as the shape changes. Two negative vortices within the same radial band tend to merge, forming a larger, stronger vortex in a few orbit periods. A random viscosity field tends to have a few strong vortices form, although not as efficiently as with merging vortices. Dust particles interact with the gas through the Stokes drag force, with the relaxation time specifying how quickly the particle velocity approaches the gas velocity. The particles tend to converge in high pressure vortices and drift out of low pressure systems. The convergence time is dependent on the vortex strength and the particle relaxation time. If the relaxation time is short compared to the period, the particles do not have an appreciable differential velocity compared to the gas, and the Stokes drag force is small. If the relaxation time is long, then the Stokes drag force is not large enough to have a significant effect. If, however, the relaxation time is of the same order as the period, so the dynamical and frictional timescales are similar, then the particles will have the shortest convergence times. This result can be seen analytically in the simple case of an axisymmetric pressure band and numerically in calculations involving the robust vortex. With a robust vortex, the convergence times are approximately 3-4 yr for relaxation times of 0.1-0.2 yr. For typical values of properties of the solar nebula, this relaxation time applies for particles with diameters of around 20 cm. Other particles, both smaller and larger, converge more slowly, but the different times result in more collisions, enhancing the coagulation of larger bodies.
by Anand Vivek Mehta.
Ph.D.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Lawler, Samantha. "The leftovers of planet formation : small body populations of our solar system and exoplanet systems". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44760.

Texto completo

Resumen

The small body populations within a planetary system give information about the planet formation and migration history of the system. In our Solar System, we study these bodies (asteroids, comets, and trans-Neptunian objects), by directly observing them in reflected light. In other solar systems, dust traces the position of the planetesimal belts that produce it, and is observed as an excess above the stellar flux in the infrared. The dust is visible and not the planetesimals because of the much greater cross-sectional surface area of a swarm of dust particles. In this thesis, both leftover large planetesimals in our Solar System and dust around other stars are investigated. Data from the Canada-France Ecliptic Plane Survey (CFEPS) are used to measure the absolute populations of trans Neptunian objects (TNOs) in mean-motion resonances with Neptune, as well as constrain the internal orbital element distributions. Detection biases play a critical role because phase relationships with Neptune make object discovery more likely at certain longitudes. The plutinos (objects in the 3:2 resonance) are given particular attention because the presence of the secular Kozai resonance within the mean-motion resonance causes different detection biases that need to be accounted for to properly debias surveys that include detections of plutinos. Because the TNOs that are trapped in mean-motion resonances with Neptune were likely emplaced there during planet migration late in the giant planet formation process, the structure within and relative populations of the resonances should be a diagnostic of the timescale and method of giant planet migration. Exoplanet systems that host several rocky planets are those that did not experience giant planet migration, and thus are likely to host planetesimal belts which should be detectable as debris disks. The Kepler Mission has detected a host of such systems, and we use data from the Wide-field Infrared Survey Explorer (WISE) Mission to search for debris disks around these stars. Though we tentatively detect more excesses toward these stars than would be expected, contamination from warm dust in the Milky Way Galaxy makes detection unreliable for these systems, and will have to await future infrared space telescopes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Patzelt, Madelein [Verfasser] y Klaus [Akademischer Betreuer] Mezger. "Chondrule formation in the early Solar System / Madelein Patzelt ; Betreuer: Klaus Mezger". Münster : Universitäts- und Landesbibliothek Münster, 2015. http://d-nb.info/1138279943/34.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Theis, Karen Julia. "Iron isotope fractionation of planetary bodies during early solar system formation processes". Thesis, University of Manchester, 2008. http://www.manchester.ac.uk/escholar/uk-ac-man-scw:163898.

Texto completo

Resumen

The aims of this research programme were twofold: to analyse the iron isotope compositions of metal grains from ordinary chondrite meteorites over a range of class and petrographic type to investigate redox reactions and thermal metamorphism during primitive planetesimal formation; and to analyse the iron isotope composition of secondary carbonate minerals in Martian meteorite ALH84001 to determine the formation temperature and thus constrain near surface conditions on early Mars. To analyse the iron isotope compositions of these materials it was necessary to develop a methodology using a Nu Plasma multi collector inductively coupled plasma mass spectrometer and a new technique for analysing natural iron-bearing samples without first purifying them by anion exchange chromatography. The purification process can cause fractionation within the sample which may mask small natural fractionation variations. The new methodology developed here yielded reproducible iron isotope ratios to within o.osroo (20) ensuring that small isotopic variations of (i56Fe -0.06roo to 0.3sroo were resolved during the analysis of the ordinary chondrite metal grains. The method for analysing samples containing matrix elements was successful and achieved an accuracy and precision comparable to pure analyte solutions for the analysis of the Martian carbonates. The analysis of the metal grains revealed a correlation between their iron isotope compositions and the redox and thermal metamorphism that these materials have experienced. The results indicate that the degree of iron isotope fractionation can be related to thermal metamorphism temperatures, except for metal grains from type 3 chondrites. This was interpreted as resulting from the type 3 chondrites not getting hot enough during thermal metamorphism to overprint the original igneous isotopic signatures. The a-rich carbonates in ALH84001 were petrographically characterised to place them within the known carbonate assemblage sequence which implied that the zoned carbonate deposition occurred during multiple phases. The zoned carbonates were then analysed for iron isotope composition and an isotopic fractionation variation for (i56Fe of -0.6%0 was determined relative to bulk Martian silicates. This indicated a formation temperature of approximately ±800( (20) and implied that liquid water was stable on or near the surface during this time.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Gorlova, Nadiya Igorivna. "Debris Disks in Open Stellar Clusters". Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195908.

Texto completo

Resumen

Indirect searches for planets (such as radial velocity studies)show that their formation may be quite common. The planets are however too small and faint to be seen against the glare of their host stars; therefore, their direct detectionis limited to the nearest systems. Alternatively one can study planets by studying their "by-product" -- dust. We see raw material available for planets around young stars, anddebris dust around old stars betraying planet-induced activity. Dust has a larger surface area per unit mass compared with a large body; it can be spread over a largersolid angle, intercepting more starlight and emitting much more lightvia reprocessing. By studying dusty disks we can infer the presence of planets at larger distances.Here we present results of a survey conducted with the SpitzerSpace Telescope of debrisdisks in three open clusters. With ages of 30--100 Myrs, these clusters are old enough that the primordialdust should have accreted into planetesimals, fallen onto the star, or been blown away due to a numberof physical processes. The dust we observe must come from collisions or sublimation of larger bodies.The purpose of this study is to investigate the dustevolution in the terrestrial planet zone, analogous to the Zodiacal cloud in our Solar system. We are most sensitive to this zone becausethe peak of a 125 K black body radiation falls into the primary pass-band of our survey -- 24 micron. We investigate the fraction and amount of the infra-red excesses around intermediate- to solar-mass stars in open stellar clusterswith well defined ages. The results are analyzed in the context of disk studies at other wavelengths and ages, providing an understanding of the time-scale for diskdissipation and ultimately planet building and frequency.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Miller, Kelly E. y Kelly E. Miller. "The R Chondrite Record of Volatile-Rich Environments in the Early Solar System". Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621016.

Texto completo

Resumen

Chondritic meteorites are undifferentiated fragments of asteroids that contain the oldest solids formed in our Solar System. Their primitive, solar-like chemical compositions indicate that they experienced very little processing following accretion to their parent bodies. As such, they retain the best records of chemical and physical processes active in the protoplanetary disk during planet formation. Chondritic meteorites are depleted relative to the sun in volatile elements such as S and O. In addition to being important components of organic material, these elements exert a strong influence on the behavior of other more refractory species and the composition of planets. Understanding their distribution is therefore of key interest to the scientific community. While the bulk abundance of volatile elements in solid phases present in meteorites is below solar values, some meteorites record volatile-rich gas phases. The Rumuruti (R) chondrites record environments rich in both S and O, making them ideal probes for volatile enhancement in the early Solar System. Disentangling the effects of parent-body processing on pre-accretionary signatures requires unequilibrated meteorite samples. These samples are rare in the R chondrites. Here, I report analyses of unequilibrated clasts in two thin sections from the same meteorite, PRE 95404 (R3.2 to R4). Data include high resolution element maps, EMP chemical analyses from silicate, sulfide, phosphate, and spinel phases, SIMS oxygen isotope ratios of chondrules, and electron diffraction patterns from Cu-bearing phases. Oxygen isotope ratios and chondrule fO2 levels are consistent with type II chondrules in LL chondrites. Chondrule-sized, rounded sulfide nodules are ubiquitous in both thin sections. There are multiple instances of sulfide-silicate relationships that are petrologically similar to compound chondrules, suggesting that sulfide nodules and silicate chondrules formed as coexisting melts. This hypothesis is supported by the presence of phosphate inclusions and Cu-rich lamellae in both sulfide nodules and sulfide assemblages within silicate chondrules. Thermodynamic analyses indicate that sulfide melts reached temperatures up to 1138 °C and fS2 of 2 x 10^(-3) atm. These conditions require total pressures on the order of 1 atm, and a dust- or ice-rich environment. Comparison with current models suggest that either the environmental parameters used to model chondrule formation prior to planetesimal formation should be adjusted to meet this pressure constraint, or R chondrite chondrules may have formed through planetesimal bow shocks or impacts. The pre-accretionary environment recorded by unequilibrated R chondrites was therefore highly sulfidizing, and had fO2 higher than solar composition, but lower than the equilibrated R chondrites.Chalcopyrite is rare in meteorites, but forms terrestrially in hydrothermal sulfide deposits. It was previously reported in the R chondrites. I studied thin sections from PRE 95411 (R3 or R4), PCA 91002 (R3.8 to R5), and NWA 7514 (R6) using Cu X-ray maps and EMP chemical analyses of sulfide phases. I found chalcopyrite in all three samples. TEM electron diffraction data from a representative assemblage in PRE 95411 are consistent with this mineral identification. TEM images and X-ray maps reveal the presence of an oxide vein. A cubanite-like phase was identified in PCA 91002. Electron diffraction patterns are consistent with isocubanite. Cu-rich lamellae in the unequilibrated clasts of PRE 95404 are the presumed precursor materials for chalcopyrite and isocubanite. Diffraction patterns from these precursor phases index to bornite. I hypothesize that bornite formed during melt crystallization prior to accretion. Hydrothermal alteration on the parent body by an Fe-rich aqueous phase between 200 and 300°C resulted in the formation of isocubanite and chalcopyrite. In most instances, isocubanite may have transformed to chalcopyrite and pyrrhotite at temperatures below 210°C. This environment was both oxidizing and sulfidizing, suggesting that the R chondrites record an extended history of volatile-rich interaction. These results indicate that hydrothermal alteration of sulfides on the R chondrite parent body was pervasive and occurred even in low petrologic types. This high temperature aqueous activity is distinct from both the low temperature aqueous alteration of the carbonaceous chondrites and the high temperature, anhydrous alteration of the ordinary chondrites.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Williams, Niel Hamilton. "Titanium isotope cosmochemistry". Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/titanium-isotope-cosmochemistry(571ae148-1673-4b85-bc10-937284bb53fc).html.

Texto completo

Resumen

High precision measurements of Ti isotopes within terrestrial and extra-terrestrial materials were made in order to investigate the processes at work within the early solar system. Variations of Ti isotopes also enabled the investigation of the specific stellar sources that created the material that formed the solar system. Titanium was chosen as it is a refractory element, relatively resistant to secondary processes and found abundantly in all solar system materials. Measurements were performed using a Thermo Fischer Neptune MC-ICPMS at the Open University, Milton Keynes. Various samples of carbonaceous chondrites, ordinary chondrites, enstatite chondrites, achondrites, lunar, terrestrial and early solar system components were analysed. Mass independent measurements of various solar system materials revealed a correlation between ε50/47Ti49/47 and ε46/47Ti49/47 defining a best line with a slope of 5.34 ± 0.34. The correlation indicates that solar system materials contain nucleosynthetic components that match a SNII stellar source. Utilising aliquots previously analysed for Zr isotopes for Ti isotope analyses revealed a correlation between ε50/47Ti49/47 and ε96/90Zr94/90 for the carbonaceous chondrites that is controlled by the CAI content of the particular carbonaceous chondrite group. Step wise dissolution of ordinary chondrites and carbonaceous chondrites revealed multiple nucleosynthetic Ti components contributing to the solar system. Stepwise leachate dissolutions were conducted on the carbonaceous chondrites Allende, Murchison and Orgueil to compliment the study of the same samples for Zr by Schönbächler et al. (2005). In addition, sample aliquots of QUE 97008 and Murchison from the work of Qin et al. (2011) were also investigated for Ti. The two investigations allow the comparison of Ti in different phases to be compared with other isotope systems such as Zr (Schönbächler et al. 2005) and Cr, Sr, Ba, Sm, Nd and Hf (Qin et al. 2011).Mass dependent fractionation and absolute nucleosynthetic anomalies of Ti within solar system materials was determined by utilising the double spike procedure. Mass dependent analysis enabled the Stable isotope composition of terrestrial materials to be investigated, revealing mass dependent fractionation between terrestrial basalts and andesite’s. Utilising the double spike procedure also enabled the calculation of absolute nucleosynthetic anomalies for Ti within solar system materials. The absolute nucleosynthetic anomalies data revealed that CAI’s contain two different compositions with one representing an exotic stellar source and the other representing the mainstream solar system composition.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Morrison, Sarah Jane y Sarah Jane Morrison. "The Dynamics and Implications of Gap Clearing via Planets in Planetesimal (Debris) Disks". Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625603.

Texto completo

Resumen

Exoplanets and debris disks are examples of solar systems other than our own. As the dusty reservoirs of colliding planetesimals, debris disks provide indicators of planetary system evolution on orbital distance scales beyond those probed by the most prolific exoplanet detection methods, and on timescales $\sim$10 Myr to 10 Gyr. The Solar System possesses both planets and small bodies, and through studying the gravitational interactions between both, we gain insight into the Solar System's past. As we enter the era of resolved observations of debris disks residing around other stars, I add to our theoretical understanding of the dynamical interactions between debris, planets, and combinations thereof. I quantify how single planets clear material in their vicinity and how long this process takes for the entire planetary mass regime. I use these relationships to assess the lowest mass planet that could clear a gap in observed debris disks over the system's lifetime. In the distant outer reaches of gaps in young debris systems, this minimum planet mass can exceed Neptune's. To complement the discoveries of wide-orbit, massive, exoplanets by direct imaging surveys, I assess the dynamical stability of high mass multi-planet systems to estimate how many high mass planets could be packed into young, gapped debris disks. I compare these expectations to the planet detection rates of direct imaging surveys and find that high mass planets are not the primary culprits for forming gaps in young debris disk systems. As an alternative model for forming gaps in planetesimal disks with planets, I assess the efficacy of creating gaps with divergently migrating pairs of planets. I find that migrating planets could produce observed gaps and elude detection. Moreover, the inferred planet masses when neglecting migration for such gaps could be expected to be observable by direct imaging surveys for young, nearby systems. Wide gaps in young systems would likely still require more than two planets even with plantesimal-driven migration. These efforts begin to probe the types of potential planets carving gaps in disks of different evolutionary stages and at wide orbit separations on scales similar to our outer Solar System.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Horský, Martin. "Termické solární systémy". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226842.

Texto completo

Resumen

The theoretical part focuses on the formation, transport of solar radiation and its availability in the Czech Republic. There are also discussed solar thermal systems and components of these systems, including their use. Project part addresses two design options of heating the hotel building. The first version is aimed at the common solution in the form of heating radiators with the source in the form of gas boiler and solar hot water. The second option solves superior solutions in the form of heating and cooling ceilings in the form of heat source heat pumps and solar heating support. Experimental solutions are focused on monitoring the operational status of the experimental solar devices and evaluation of operating characteristics of the device.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Mulders, Gijs D., Ilaria Pascucci, Dániel Apai, Antonio Frasca y Joanna Molenda-Żakowicz. "A SUPER-SOLAR METALLICITY FOR STARS WITH HOT ROCKY EXOPLANETS". IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622435.

Texto completo

Resumen

Host star metallicity provides a measure of the conditions in protoplanetary disks at the time of planet formation. Using a sample of over 20,000 Kepler stars with spectroscopic metallicities from the LAMOST survey, we explore how the exoplanet population depends on host star metallicity as a function of orbital period and planet size. We find that exoplanets with orbital periods less than 10 days are preferentially found around metal-rich stars ([Fe/H] similar or equal to 0.15 +/- 0.05 dex). The occurrence rates of these hot exoplanets increases to similar to 30% for super-solar metallicity stars from similar to 10% for stars with a sub-solar metallicity. Cooler exoplanets, which reside at longer orbital periods and constitute the bulk of the exoplanet population with an occurrence rate of greater than or similar to 90%, have host star metallicities consistent with solar. At short orbital periods, P < 10 days, the difference in host star metallicity is largest for hot rocky planets (< 1.7 R-circle plus), where the metallicity difference is [Fe/H] similar or equal to 0.25 +/- 0.07 dex. The excess of hot rocky planets around metal-rich stars implies they either share a formation mechanism with hot Jupiters, or trace a planet trap at the protoplanetary disk inner edge, which is metallicity dependent. We do not find statistically significant evidence for a previously identified trend that small planets toward the habitable zone are preferentially found around low-metallicity stars. Refuting or confirming this trend requires a larger sample of spectroscopic metallicities.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Ng, Ferdinand. "Calibration and image formation in the ABACUS sonar system". Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/5138.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Bonnet, Jean-Yves. "L'azote comme élément mineur dans les macromolécules organiques chondritiques et cométaires : simulations expérimentales contraintes par les cosmomatériaux". Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENU004/document.

Texto completo

Resumen

Le travail réalisé au cours de ma de thèse avait pour but de placer de nouvelles contraintes sur la composition du ou des précurseurs organiques présents dans la nébuleuse proto-solaire. Des expériences de thermodégradation ont été mises en place en utilisant des matériaux modèles riches en azote. La spectrométrie de masse à haute résolution (Orbitrap) à été utilisée afin de mieux caractériser les polymères de HCN, autre matériau modèle. Ce travail apporte de nouvelles informations sur la diversité moléculaire de tels matériaux, ainsi que de nouvelles informations sur leur structure. Les expériences de thermodégradation proprement dites ont ensuite été réalisées, afin de mieux comprendre le comportement de l'azote dans les matériaux organiques macromoléculaires, et ainsi apporter de nouvelles contraintes sur l'origine de la matière organique présente dans les différentes classes de cosmomatériaux (chondrites carbonées, IDPs et UCAMMs). Cette série d'expériences nous a permis de mettre en évidence une probable différence de précurseur entre la matière carbonée des IOMs et celle des IDPs et UCAMMs
The aim of my PhD work was to add some new constraints on the organic precursors compositions in the early solar system. Thermal degradation experiments have been performed, using N-rich analog materials. High resolution mass spectrometry gives us the possibility to better characterize the HCN polymers another type of analog materials. This part of the study provides us new informations about the molecular diversity of HCN polymers and also new constraints on their structure. The thremal degradation experiments were then performed. The aim of this study was to provide some new constraints on the composition of the organic precursors present in the early solar system and incorporated in the different bodies (carbonaceous chondrites, IDPs, UCAMMs). We can conclude that the organic precursor of the IOMs was poor in nitrogen while the organic matter accreted by the parent bodies of IDPs and UCAMMs was probably nitrogen rich

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Matsuno, Junya. "On the origin and formation process of glass with embedded metal and sulfides (GEMS) inferred from 3D observation and reproduction experiment". 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199114.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Luis, Hélio Fernandes. "Study of nuclear reactions relevant for astrophysics by Micro-AMS". Doctoral thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/11274.

Texto completo

Resumen

Dissertação para obtenção do Grau de Doutor em Física
This work of this thesis was dedicated to the application of the Micro-AMS(Accelerator Mass spectrometry with micro-beam) to the study of nuclear reactions relevant to Astrophysics, namely reactions involving the radioisotope 36Cl. Before this could be done, the system had to be installed, tested and optimized. During the installation and testing phase, several isotopes were measured, principally lead and platinum isotopes, which served to show the potential of this technique for applications to Material science and archeology. After this initial stage, the work with 36Cl began. 36Cl is one of several short to medium lived isotopes (as compared to the earth age) whose abundances in the earlier solar system may help to clarify its formation process. There are two generally accepted possible models for the production of this radionuclide: it originated from the ejecta of a nearby supernova (where 36Cl was most probably produced via the s-process by neutron irradiation of 35Cl) and/or it was produced by in-situ irradiation of nebular dust by energetic particles(mostly, p, a, 3He -X-wind irradiation model). The objective of the present work was to measure the cross section of the 35Cl(n,γ)36Cl nuclear reaction which opened the possibility to the future study of the 37Cl(p,d)36Cl and 35Cl(d,p)36Cl nuclear reactions, by measuring the 36Cl content of AgCl samples with Micro-AMS, taking advantage of the very low detection limits of this technique for chlorine measurements. For that, the micro-AMS system of the CTN-IST laboratory had to be optimized for chlorine measurements, as to our knowledge this type of measurements had never been performed in such a system (AMS with micro-beam). This thesis presents the results of these developments, namely the tests in terms of precision and reproducibility that were done by comparing AgCl blanks irradiated at the Portuguese National Reactor with standards produced by the dilution of the NIST SRM 4943 standard material. With these results the cross section of the 37Cl(n,γ)36Cl was calculated.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Lyra, Wladimir. "Turbulence-Assisted Planetary Growth : Hydrodynamical Simulations of Accretion Disks and Planet Formation". Doctoral thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9537.

Texto completo

Resumen

The current paradigm in planet formation theory is developed around a hierarquical growth of solid bodies, from interstellar dust grains to rocky planetary cores. A particularly difficult phase in the process is the growth from meter-size boulders to planetary embryos of the size of our Moon or Mars. Objects of this size are expected to drift extremely rapid in a protoplanetary disk, so that they would generally fall into the central star well before larger bodies can form. In this thesis, we used numerical simulations to find a physical mechanism that may retain solids in some parts of protoplanetary disks long enough to allow for the formation of planetary embryos. We found that such accumulation can happen at the borders of so-called dead zones. These dead zones would be regions where the coupling to the ambient magnetic field is weaker and the turbulence is less strong, or maybe even absent in some cases. We show by hydrodynamical simulations that material accumulating between the turbulent active and dead regions would be trapped into vortices to effectively form planetary embryos of Moon to Mars mass. We also show that in disks that already formed a giant planet, solid matter accumulates on the edges of the gap the planet carves, as well as at the stable Lagrangian points. The concentration is strong enough for the solids to clump together and form smaller, rocky planets like Earth. Outside our solar system, some gas giant planets have been detected in the habitable zone of their stars. Their wakes may harbour rocky, Earth-size worlds.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Sousa, Rafael Ribeiro de. "A instabilidade na evolução dinâmica do sistema solar : considerações sobre o tempo de instabilidade e a formação dinâmica do cinturão de Kuiper /". Guaratinguetá, 2019. http://hdl.handle.net/11449/183463.

Texto completo

Resumen

Orientador: Ernesto Vieira Neto
Resumo: O estudo da formação e evolução do Sistema Solar é uma fonte de informação para entender sob quais condições a vida poderia surgir e evoluir. Nós apresentamos, nesta Tese de doutorado, um estudo numérico da fase final de acresção dos planetas gigantes do Sistema Solar durante e após a fase do disco de gás protoplanetário. Em nossas simulações, utilizamos um modelo recente e confiável para a formação de Urano e Netuno para esculpir as propriedades do disco trans-Netuniano original (Izidoro et al. , 2015a). Nós fizemos este estudo de uma maneira autoconsistente considerando os efeitos do gás e da evolução dos embriões planetários que formam Urano e Netuno por colisões gigantescas. Consideramos diferentes histórias de migração de Júpiter, devido a incerteza de como Júpiter migrou, durante a fase de gás. As nossas simulações permitiram obter pela primeira vez as propriedades orbitais do disco trans-Netuniano original. Então, calculamos o tempo de instabilidade dos planetas gigantes a partir de sistemas planetários que formam similares Urano e Netuno. Nossos resultados indicam fortemente que a instabilidade dos planetas gigantes acontecem cedo em até 500 milhões de anos e mais provável ainda ter acontecido em 136 milhões de anos após a dissipação do gás. Nós também realizamos simulações para discutir alguns efeitos dinâmicos que acontecem na região do cinturão de Kuiper. Estes efeitos acontecem quando Netuno esteve em alta excentricidade durante a instabilidade planetária. Para es... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: A study of the formation and evolution of the Solar System is a source of information for an understanding of what conditions life could arise and evolve. We present a numerical study of the final stage of accretion of the giant planets of the Solar System during and after the protoplanetary gas disc phase. In our simulations, we use a recent and reliable model for the formation of Uranus and Neptune to sculpt the properties of the original trans-Neptunian disk (Izidoro et al. , 2015a). We have done this study in a self-consistent way considering the effects of gas and the evolution of planetary embryos which form Uranus and Neptune by mutual giant collisions. We considered different Jupiter migration stories due to the uncertainty of how Jupiter’s migration was during the gas phase. Our simulations provide for the first time to obtain the orbital properties of the original trans-Neptunian disk. We then calculate the instability time of the giant planets from planetary systems which form similar Uranus and Neptune. Our results strongly indicate that the instability of the giant planets occurs early within 500 million years and even more likely to happen at 136 million years after gas dissipation. We also perform simulations to discuss some dynamical effects that happen in the Kuiper belt region. These effects happen when Neptune was in high eccentricity during planetary instability. For this problem, we use the simulations performed by Gomes et al. (2018) who investigated the... (Complete abstract click electronic access below)
Doutor

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Villeneuve, Johan. "Formation des chondres : Précurseurs et Chronologie". Phd thesis, Institut National Polytechnique de Lorraine - INPL, 2010. http://tel.archives-ouvertes.fr/tel-00564555.

Texto completo

Resumen

Les chondres, sphérules infra-millimétriques composées de minéraux silicatés de haute température, sont les constituants majeurs des météorites primitives. Ils présentent d'importantes variabilités texturales et chimiques révélatrices d'une histoire complexe. Cette thèse s'est intéressée à la chronologie de formation des chondres et de leurs précurseurs à deux échelles de temps distinctes aux moyens de deux approches complémentaires : la géochimie isotopique via le chronomètre isotopique à courte période 26Al-26Mg et la pétrologie expérimentale. Le développement au cours de cette thèse d'un protocole analytique innovant de mesure in situ de haute précision par sonde ionique des compositions isotopiques du Mg et Al, a permis de démontrer l'homogénéité de la distribution de l'26Al dans le disque d'accrétion, ce qui présente d'importantes implications sur la chronologie relative et les processus de formation des chondres, mais aussi sur l'origine de l'26Al dans le Système Solaire. L'application de ce protocole analytique aux olivines reliques des chondres permet de préciser leur origine, ainsi que leur chronologie et leur processus de formation. Les expérimentations permettent de montrer qu'il est aisé de former des analogues de chondres de type II PO à partir de chondres de type I PO. Un tel processus de formation des chondres implique l'application de régimes thermiques isothermes suivis d'une trempe rapide, incompatibles avec les mécanismes classiques d'ondes de choc. D'autre part, nous montrons que les compositions chimiques en éléments majeurs et traces des différents types de chondres porphyriques peuvent être reproduites par le mélange de trois phases réfractaires solides héritées des précurseurs des chondres (olivine réfractaire, liquide réfractaire et métal) et d'une phase gazeuse riche en éléments volatils et modérément volatils. Ces résultats nous ont conduit à proposer un modèle de filiation entre les chondres.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Auge, Basile. "Effet du rayonnement cosmique galactique sur les petits corps glacés du système solaire externe : indices pour la formation de la matière organique des micrométéorites antarctiques ultra-carbonées". Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC228.

Texto completo

Resumen

Les météorites et particules de poussière interplanétaire apportent des contraintes sur la formation et l’évolution de la matière dans le système solaire. Les micrométéorites, dont certaines proviennent des régions externes du système solaire, représentent la source dominante de matière extraterrestre arrivant sur Terre. Les micrométéorites collectées dans les neiges antarctiques sont dans un excellent état de conservation du fait de conditions géographiques et météorologiques favorables à leur préservation. La collection CONCORDIA/CSNSM de micrométéorites contient en particulier des micrométéorites peu altérées thermiquement lors de leur entrée atmosphérique. Certaines sont caractérisées par une très haute teneur en matière organique, dépassant 50% en volume, très largement au dessus des valeurs habituelles trouvées dans les météorites. Cette matière organique présente de plus la spécificité d’être fortement enrichie en deutérium et contient jusqu’à cinq fois plus d’azote celle extraite des météorites.Les différents scénarios proposés pour expliquer la formation de cette matière et satisfaisant à l’ensemble des caractéristiques de ces micrométéorites impliquent des corps parents orbitant au-delà de Neptune, dans la ceinture de Kuiper ou dans le nuage de Oort. La température y est suffisamment basse pour condenser à leur surface les molécules volatiles comme l’azote et le méthane tandis qu’ils sont exposés à l’action radiochimique du rayonnement cosmique galactique. Afin de contraindre ces scénarios, des expériences ont été conduites en exposant différentes glaces N2-CH4 aux faisceaux d’ions du GANIL simulant ce rayonnement. L’évolution chimique des glaces au cours de l’irradiation et pendant le recuit des échantillons a été suivie par spectroscopie infrarouge au moyen de deux dispositifs disponibles au CIMAP : la chambre d’analyse CASIMIR et le nouvel appareil IGLIAS. Des analyses complémentaires ex situ ont été menées par spectrométrie de masse. Les résultats apportant des éléments de réponse à l’origine de la matière organique des micrométéorites ultracarbonées ainsi que sur l’origine de leur enrichissement isotopique seront présentés et discutés
Extraterrestrial materials, such as meteorites and interplanetary dust particles, provide constraints on the formation and evolution of organic matter in the young solar system. Micrometeorites represent the dominant source of extraterrestrial matter at the Earth’s surface, some of them originating from large heliocentric distances.Micrometeorites recovered from Antarctica snows provide a unique source of pristine interplanetary dust particles, which underwent a minimal weathering at atmospheric entry. A few percent are characterized by very large carbon content with at least 50% in volume, much higher than the value found in meteorites. This organic matter exhibits extreme deuterium excesses and is unusually nitrogen-rich.Several formation scenarios have been proposed for the formation of the N-rich organic matter observed in UCAMMs, suggesting that these particles come from a parent body orbiting beyond the nitrogen snow line, in the outer Solar System where they are exposed to ions from the galactic cosmic rays. We experimentally evaluate the scenario involving high energy irradiation of icy bodies subsurface orbiting at large heliocentric distances by irradiating N2-CH4 ices with swift heavy ions provided by the GANIL facility. Chemical evolution was monitored by Fourier transform infrared spectroscopy with two experimental set-up : CASIMIR and IGLIAS. Ex situ mass spectroscopy measurement where also conducted. Results concerning the origin of the organic matter found in ultracarbonaceous micrometeorites and the origin of its deuterium enrichment will be presented and discussed

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Neves, Vasco. "Étude sur les paramétres stellaires des naines M et leur lien à la formation planétaire". Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY082/document.

Texto completo

Resumen

Au moment d'écrire ma Thèse plus de 900 exoplanètes été annoncées et plus de 2700 planètes détectées par le télescope spatial Kepler sont en attente d'être confirmées. La haute précision des spectres et des courbes de lumière obtenue dans les relevés Doppler et transit, permet l'étude détaillée des paramètres des étoiles hôtes, et ouvre la possibilité d'enquêter sur les corrélations étoile planètes. En outre, la détermination des paramètres stellaires avec précision est un besoin critique pour déterminer les paramètres planétaires, à savoir, la masse, le rayon et la densité.Dans le cas des naines FGK, la détermination des paramètres stellaires est bien établie et peut être utilisée avec confiance pour étudier la relation planète-étoile ainsi que pour obtenir les paramètres planétaires avec une grande precision. Cependant, ce n'est pas le cas pour les naines M, les étoiles les plus communes de la Galaxie. Par rapport à leurs cousines plus chaudes, les naines M sont plus petites, plus froides, et plus faiblement lumineuses, et donc plus difficile à étudier. Le plus grand défi qui concerne les naines M est lié à la présence de milliards de lignes moléculaires qui gomme le continuum et rend l'analyse spectrale classique presque impossible. Trouver des fac ̧ons nouvelles et novatrices pour surmonter cet obstacle et obtenir une mesure des paramètres stellaires est l'objectif principal de cette Thèse .Pour l'atteindre, j'ai concentré mes recherches sur deux approches méthodologiques, photométrique et spectroscopiques. Mon premier travail avait pour objectif d'établir l'étalonnage de métallicité pho- tométrique précis. Par manque de binaires FGK+M avec de bonnes données photométriques je ne pouvais pas atteindre cet objectif. Il m'a cependant était possible, avec les données disponibles, de comparer les étalonnages photométriques déjà établies et légèrement améliorer le meilleur d'entre eux, comme décrit au Chapitre 3.Puis, je me suis concentré sur les approches spectroscopiques pour obtenir des paramètres stel- laires plus précis pour les naines M. À cette fin, j'ai utilisé des spectres HARPS de haute résolution et développé une méthode pour mesurer les lignes spectrales sans tenir compte du continuum . En utilisant cette méthode, je créé un nouvel étalonnage visible avec une précision de 0.08 dex pour [Fe/H] et 80 K pourTeff .Ce travail est détaillé dans le Chapitre 4.Finalement , j'ai également participé à l'amélioration des paramètres de l'étoile GJ3470 et de sa planète, où mon expertise dans les paramètres stellaires de naines M avait un rôle important. Les détails concernant cette enquête sont présentés dans le Chapitre 5
At the time of writing of this Thesis more than 900 planets have been announced and about 2700 planets from the Kepler space telescope are waiting to be confirmed. The very precise spectra and light curves obtained in Doppler and transit surveys, allows the in-depth study of the parameters of the host stars, and opens the possibility to investigate the star-plant correlations. Also, determining the stellar parameters with precision is critical for more precise determinations of the planetary parameters, namely, mass, radius, and density.In the case of the FGK dwarfs, the determination of stellar parameters is well established and can be used with confidence to study the star-planet relation as well as to obtain precise planetary parameters. However, this is not the case for M dwarfs, the most common stars in the Galaxy. Compared to their hotter cousins, M dwarfs are smaller, colder, and fainter, and therefore harder to study. The biggest challenge regarding M dwarfs is related to the presence of billions of molecular lines that depress the continuum making a classical spectral analysis almost impossible. Finding new and innovative ways to overcome this obstacle in order to obtain precise stellar parameters is the goal of this Thesis.To achieve this goal I focused my research into two main avenues: photometric and spectroscopic methods. My initial work had the objective of establishing a precise photometric metallicity calibration, but I could not reach this goal, as I did not have enough FGK+M binaries with good photometric data. However, it was possible, with the available data, to compare the already established photometric calibrations and slightly improve the best one, as described in Chapter 3.Then, I focused on spectroscopic approaches with the aim of obtaining precise M dwarf parame- ters. To this end I used HARPS high-resolution spectra and developed a method to measure the spectral lines disregarding the continuum completely. Using this method I established a new visible calibration with a precision of 0.08 dex for [Fe/H] and 80 K for Te f f . This work is detailed in Chapter 4.Finally, I also participated in the refinement of the parameters of the star GJ3470 and its planet, where my expertise in stellar parameters of M dwarfs had an important role. The details regarding this investigation are shown in Chapter 5
No momento em que escrevo esta Tese, o número de planetas anunciados já ultrapassou os 900 e os cerca de 2700 candidatos detectados pelo telescópio espacial Kepler esperam por confirmação. Os espectros e as curvas de luz obtidos nos programas de procura de planetas permitem, também, o estudo em profundidade dos parâmetros das estrelas com planetas e abrem a possibilidade de investigar a relação estrela-planeta. Neste contexto, a determinação com precisão dos parâmetros estelares é crítica na determinação precisa dos parâmetros planetários, nomeadamente, a massa, o raio e a densidade.No caso das anãs FGK, os métodos de determinação dos parâmetros estelares estão bem estabelecidos e podem ser usados com confiança no estudo da relação estrela-planeta, assim como na obtenção de parâmetros planetários precisos. No entanto, não é esse o caso para as anãs M, as estrelas mais comuns da nossa Galáxia. Ao contrário das suas primas, as estrelas M são mais pequenas, frias e ténues e, assim sendo, mais difíceis de estudar. O grande entrave no estudo das estrelas M está relacionado com a presença de biliões de linhas moleculares que deprimem o contínuo espectral, fazendo com que uma análise espectral clássica se torne quase impossível. A procura de métodos inovadores que possibilitem ultrapassar este obstáculo, tendo em vista a obtenção de parâmetros precisos, é o objectivo desta Tese.Tendo em conta esse objetivo, foquei os meus esforços em duas linhas principais de pesquisa, baseadas em métodos fotométricos e métodos espectroscópicos. O meu trabalho inicial tinha como objetivo o estabelecimento de uma calibração fotométrica para a metalicidade, mas não me foi possível atingir esse objetivo, pois não tinha sistemas binários FGK+M suficientes com bons dados fotométricos. No entanto, foi possível, com os dados disponíveis, comparar as calibrações fotométricas existentes e refinar ligeiramente a melhor delas, como descrito no Capítulo 3.Após este trabalho passei a concentrar-me em técnicas espectroscópicas de obtenção de parâmetros estelares em estrelas M. Tendo em mente esse objetivo, usei espectros HARPS de alta resolução para desenvolver um novo método de medição de linhas espectrais independente do contínuo espectral. Seguidamente, usei este método no desenvolvimento de uma nova calibração de metalicidade e temperatura efectiva em estrelas M na região do visível, através da qual consegui atingir uma precisão de 0.08 dex para a [Fe/H] e de 80 K para a temperatura. Este trabalho está descrito no Capítulo 4.Ao mesmo tempo colaborei na determinação com precisão dos parâmetros da estrela GJ3470 e do seu planeta, onde a minha proficiência na determinação de parâmetros estelares em anãs M teve um papel importante. Os detalhes relacionados com este trabalho de investigação estão descritos no Capítulo 5

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Sengil, Nevsan. "Solar cell concentrator system". Thesis, Monterey, California: U.S. Naval Postgraduate School, 1986. http://hdl.handle.net/10945/22111.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Yang, Sun. "Solar Energy Control System Design". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-141489.

Texto completo

Resumen

This thesis covers design, simulation and implementation of a solar energy control system for an on grid energy storage device. The design covers several control methods such as energy balance control, operating mode switching and data exchange. A genetic algorithm was designed to optimize the control system parameters design, and the algorithm's simulation and real time operating system implementation showed comparable results. The control system was implemented to connect a power supply to the grid. The power supply simulated a solar panel and connected to an electrical grid via Energy Hub equipment, and the energy transfer characteristics of designed control system were tested. The results showed that the selected algorithm matches the target performance criteria.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Shafi, Muhammad Irfan y Md Maidur Rehman Talukder. "Development of Hybrid Solar System". Thesis, Högskolan i Gävle, Akademin för teknik och miljö, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-13927.

Texto completo

Resumen

Technology replaces newer technology with improved efficiency. Solar technology is going to draw out a new life to make a green change in the terms of energy. As a result energy from the sunlight is being changed into electric energy by using solar cell. But still its efficiency could not be able to make a sense as a depending energy technology. In order to look up the solution, solar technology is changing rapidly to get maximum output. To take up this new challenge solar technology is trying to change its building component that are used to make solar cell, for example solar cell material, bypass diode system, blocking diode system etc. Now-a-days, solar energy system is designed as a hybrid system that can make electricity and hot water at the same time. In the hybrid solar system, photovoltaic and solar thermal systems are integrated at the same system and as a result heat and electricity are produced simultaneously at the same area. Solar cells are attached with both top and the bottom side of the module and the collectors are set up inside the module. By using collector inside the module, rejected heat from the solar cell is absorbed by the water that flows through the collectors. But a problem arises at the midday or after midday because the reflector of this system cannot reflect sunlight properly on the bottom side of the module. That’s why shading is occurred on the bottom side which reduce the total electrical output of this system. To work out this shading problem, a bypass diode is connected in parallel with the group of solar cells. Schottky diodes are being used as bypass diodes inside in the most of the solar cells. Schottky diode forward voltage drop is almost 0.45 Volt which is an important cause of reducing the output power as well as the efficiency of this hybrid system. To solve this problem, new lossless diode is attached inside the hybrid solar system instead of schottky diode which can work with a very low forward voltage drop roughly 50mV at 10amp. To make a comparison between the performance of PVT system with the schottky diode and the new lossless diode, many data has been collected from the outdoor test. After getting the output result, it is clear that the output power and efficiency is going to be changed for using the new lossless diode. For using the lossless diode, the efficiency of the bottom side of the module was increased by 0.31 %.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Al-Madhhachi, Hayder. "Solar powered thermoelectric distillation system". Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/107598/.

Texto completo

Resumen

An efficient thermoelectric distillation system was designed, constructed and tested. The unique aspect of this design is to use the waste heat from the hot side of thermoelectric module for heating of the feed water, to improve the evaporation while using the cold side of the module to cool the condenser and improve the condensation process. The developed thermoelectric distillation system produces 28.5 mL of distilled water (equivalent to 678 mL/m2) over a period of 1 hour. The corresponding electrical energy required for the water production is 0.0324 kWh, which gives a specific energy consumption of 0.00114 kWh/mL. The developed system in this research has significantly lower energy consumption than the existing thermoelectric distillation systems. The transient to steady state behaviour of the developed thermoelectric distillation system was investigated. It was found that the system reaches steady state after approximately three hours of the system operation. The water temperature in evaporation chamber was increased from 22.3 oC to 47.8 oC. Similarly, the vapour temperature was increased moderately from 20.3 oC to 30.4 oC. The steady state water production, humidity, energy consumption and COP of the thermoelectric distillation system were 15.3 mL/h, 81%, 0.0324 kWh and 1.04, respectively. Thermal models have been developed through water-vapour phase-change theory to interpret the evaporation and condensation processes involved in the fresh water production of the thermoelectric distillation system. The first model was related to the evaporation process to determine the vapour production in the system. A theoretical distillation ratio of 12% was obtained, with a predicted water temperature of 42.7 oC. This is in reasonable agreement with the 9.5% value experimentally obtained. The second ii model has been developed for the water condensation process. The developed model can be used for determining the key parameters that control the condensation processes and the system thermal performance. This model shows that the rate of water condensation is dependent upon the convection heat transfer coefficient of the cold-side heat exchanger. The fitted value of the convection heat transfer coefficient in the thermoelectric distillation system is 8 W/m2.K. Key factors that influence the total water production and water production rate have been investigated, including sample water temperature, vapour volume at sample water level, Peltier current and thermoelectric input power. The experimental data shows that an increase in sample water temperature from 30 oC to 60 oC gives a 47 % increase in total water production. Peltier current is demonstrated as a control factor in the design of an effective thermoelectric distillation system. The results show that the total water production increases by 61%, when the volume occupied by the vapour is reduced from 600 cm3 to 400 cm3 by increasing the sample water level from 10 mm to 30 mm in the system. The maximum water production is achieved by increasing sample water temperature and the corresponding optimised input power. Measurements of the distilled water show that it has similar quality to drinkable tap water in terms of pH, total dissolved solids and electrical conductivity values. Photovoltaic Geographical Information System was used to estimate the global irradiation per square meter and the solar electricity generation in kWh received by a solar panel in a specific region. Using the experimental prototype, the maximum monthly average water production is 4023.3 mL when using 8.52 kWh of electricity produced during March at the University of Kufa. The minimum average monthly water production is 2970.3 mL using 6.29 kWh of electricity produced during November.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Gibbard, Seran Gwen 1967. "Lightning in the solar system". Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290640.

Texto completo

Resumen

Lightning, a familiar phenomenon on Earth, may also occur at other times and locations in our solar system. It has been suggested as a mechanism for forming chondrules, millimeter-sized beads of glassy silicate found in primitive meteorites formed in the early solar system 4.5 billion years ago. It has also been detected in Voyager images of Jupiter, and there is evidence that it may occur on other planets as well, including Venus, Saturn and Neptune. The mechanism believed to produce lightning discharges on Earth, and possibly other planets, is charge production by collisions of ice particles, followed by gravitational separation of oppositely-charged large and small particles. This work examines the possibility of the occurrence of lightning discharges in the atmospheres of Jupiter and Neptune as well as in the protoplanetary nebula (PPN) of the early solar system by modeling charge separation and growth of the electric field. The model is also applied to the Earth as a test of its predictive power. It is found that the model can reproduce the correct timescale, particle charge and electric field magnitude seen in terrestrial lightning. The model also predicts lightning on Jupiter at the 3-5 bar level provided that the local water abundance is greater than the solar value. This is a much higher abundance than measured by the Galileo probe into Jupiter's atmosphere, which suggests that the water content measured by the probe does not apply to the entire planet. An application of the model to Neptune's water and NH₄SH clouds finds that lightning is unlikely in these clouds due to the large electric field required for electrical breakdown. Lightning may be possible in the overlying H₂S-NH₃ cloud provided that these substances can undergo collisional charge exchange with a magnitude at least 1% of that found in water ice. In the protoplanetary nebula, it appears that large-scale precipitation-induced lightning could not have occurred, due to the small mass density, low temperature and high electrical conductivity of the surroundings. This is a robust conclusion that does not depend sensitively on the values of the parameters involved.

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Mkhize, Mfanafuthi Mthandeni. "Multistage solar still desalination system". Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2848.

Texto completo

Resumen

Thesis (Master of Engineering in Mechanical Engineering)--Cape Peninsula University of Technology, 2018.
The present study was centred on the design of a thermal multistage solar still desalination system. The design is a multistage with new configurations such as direct vapour input into each stage using vapour make-up tubes and the integration of a multistage with a basin type solar still. The incorporation of float a valve in the secondary seawater tank to regulate the seawater in the assembly eliminated the need of pumps to the system. The circulation of seawater between the evaporator and the evacuated tube solar collector (ETC) was through the pressure difference and the flow back was controlled through the incorporation of oneway flow valve. The ETC was used as a heat source to supply the thermal energy into the multistage system. The system had no electrical connections and therefore, no forced circulation as no pumps or any electrical components were used. The system consisted of six stages in total, the evaporator supplied the vapour to five of the six stages of the system. The system was tested on the roof of Mechanical Engineering Department and this location was chosen because of less sun’s intensity obstructions. The system was tested for nine (9) days but the distillate collection was not performed for the whole each day. This was due to the controlled access to the roof and the minor repairs that had to occur before the tests were conducted. The duration on which the tests were conducted varied in each day. The data was supposed to be logged from 08h00 am to 18h00 pm but this was not so due to the controlled access to where the tests were conducted. This data logging period was chosen based on the assumptions that the sun’s intensity would be at maximum within this period. The longest period of test was approximately 7 hours and the system managed to produce about 1500 ml and the maximum temperature for the day was 28oC. The system produced a minimum of 225 ml in the space of 3 hours and the temperature of the day was 26oC. The total amount of distillate produced was about 7600 ml and this amount was produced within the period of 49 hours. The 49 hours is equivalent to two days and 1 hour. It is anticipated that the system would have produced more should there be no repairs involved during the tests. The system produced a maximum of 48 ml at night and a minimum of 8ml in some nights. The night tests were not controlled and monitored due to limited access. It was noticed that the system was empty in each morning of the first few days of the tests. This emptiness contributed to the leakage occurred to the evaporator. The leakage of the evaporator was caused by unmonitored heat supplied by the ETC. The evaporator was constructed using unsuitable material and this was another factor which contributed towards the failure of the evaporator.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Ibrahim, Munzer. "Solar Powered Air Conditioning System". Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-39522.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Lamb, D. A. "Formation and evolution of small-scale solar magnetic fields". Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337117.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Wood, Paul D. "Elements of solar activity : particle acceleration and filament formation". Thesis, University of St Andrews, 2005. http://hdl.handle.net/10023/11309.

Texto completo

Resumen

This thesis studies the acceleration of particles to super-thermal energies in explosive solar events as well as the magnetic changes in connectivity that may be responsible for changes in the morphology of quiescent filaments. Firstly a review of some of the observations of solar flare dynamics is given, as well as an introduction to the competing theories attempting to explain both particle acceleration and filament formation. An explanation of the numerical FORTRAN code that is used to calculate the trajectories of particle distribution functions in prescribed electromagnetic fields is given. Examples of known fields are used to test the accuracy of the code and the simple example of the well-known Litvinenko current sheet field is investigated. The results of charged particle orbit calculations in prescribed electric and magnetic fields motivated by magnetic reconnection models are then presented. The electromagnetic fields are chosen to resemble a current sheet with a localised reconnection region. The dependence of the model on the important physical parameters is considered. An introduction to the mathematical formulation of a collapsing magnetic trap is given. The same numerical code is used to calculate single electron orbits in this more complicated time dependent electromagnetic field. Consideration of important previous work is given before describing the best attempts to model the movement of flare loops in a realistic fashion. Finally the process of flux cancellation and filament formation is studied using a range of data including ground-based Hα and SoHO MDI magnetograms. It is found that the cancellation occurs at the ends of Hα sections of the filament and is accompanied by a noticeable increase in the Hα intensity and linkage of the sections. Measurements of the amount of flux cancelled at each site show it is in agreement with an estimate of the axial flux contained in the filament.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Foley, Brian S. B. (Brian M. ). Massachusetts Institute of Technology. "Solar thermal collector system modeling and testing for novel solar cooker". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92179.

Texto completo

Resumen

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (page 22).
Solar cookers are aimed at reducing pollution and desertification in the developing world. However, they are often disregarded as they do not give users the ability to cook after daylight hours. The Wilson solar cooker is a solar cooker designed to address this problem by converting solar energy and storing that energy as heat in the form of molten salt (lithium nitrate). This thesis involved research, modeling, and experimentation for the solar collection system of the cooker. This thesis looked at prior research on glazing, Fresnel lenses, and absorber surface treatments to identify and evaluate elements for use in the collection system. Borosilicate glass, with a thermal conductivity of 1.005 W/mK and a solar transmittance of 0.91, and flat black paint, with absorptivity 0.96 and emissivity 0.88 were identified as potential elements for use in first trials. Experimentation was performed on copper and aluminum samples with various surface treatments powered by various Fresnel lenses to evaluate the relative efficiency of these treatments. A novel treatment method, machining a conical hole into the sample, was found to improve efficiency on untreated samples, but inferior to flat black paint. Modeling predicted that the minimum collection area for an acrylic Fresnel lens off-number 1.2 was 0.60 m² for and 0.65 m² for the proposed collector without and with glazing, respectively. A recommendation of collection area 1 m² was proposed to account for unexpected losses due to manufacturing errors, positioning errors, and environmental variation. This thesis also analyzed a proposal for a novel solar collector, a polished aluminum cone. Modeling and efficiency testing showed the cone to be inadequate for the radiation collection needed for the solar cooker.
by Brian Foley.
S.B.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Al-Edhari, Ali Jaber. "Complex organic molecules in solar-type star forming regions". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY048/document.

Texto completo

Resumen

Le but de la présente thèse est l'étude de la compléxité moléculaire dans les régions de formation stellaires. Cette thèse s'axe sur deux classes de molécule aux caractéristiques prébiotiques : les molécules organiques complexes et les cyanopolyynes.Dans ce contexte, j'ai analysé des données d'un seul échantillon de relevés spec- traux en exploitant des codes de transfert radiatif à l'équilibre thermodynamique local (LTE) et/ou non-LTE pour deux sources : une proto-étoile de type solaire dans un environnement calme (IRAS 16293-2422) et un proto-ama constitué de proto-étoile de type solaire (OMC2-FIR4).L'objectif est de trouver des similar- ités et des différences entre ces deux cas.J'ai utilisé des données issu de deux relevés spectraux : TIMASSS (The IRAS16293-2422 Millimeter And Submilimeter Spectral Survey) réalisés en 2011 (Caux et al. 2011), et ASAI(Astrochemical Surveys At IRAM) réalisés pen- dant la période 2013-2015 (eg Lopez-Sepulcre et al.2015). J'ai extrais les lignes (identification et intensité intégrée) en utilisant le paquet disponible publique- ment : CASSIS (Centre d'Analyse Scientifique de Spectres Infrarouges et Sub- millimetrique). Pour finir, j'ai utilisé le paquet GRAPES (GRenoble Analysis of Protostellar Envelope Spectral) afin de modéliser la distribution spectrale énergétique de ligne (SLED) des molécules détectées, mais aussi afin d'estimer leurs abondances à travers l'envelope de IRAS16293 et du coeur chaud OMC2- FIR4.Les principaux résultats de la thèse sont :1. Le premier recensement complet des molecules organiques complexes (COMs) dans IRAS162932. La première détéction de COMs dans l'enveloppe froide d'une proto-étoile de type solaire (IRAS16293-2422) supportant l'idée qu'un méchanisme de formation, relativement efficace pour les COMs détectées, doit exister en phase gazeuse froide.3. La découverte d'une fine corrélation entre le diméthyle-éther (DME) et le méthyle-formate (MF) suggère une relation mère fille entre ces deux espèces.4. La detection de formamide, espèce avec un très fort potentiel prébiotique, dans plusieurs protoétoiles incluant IRAS16293-2422 et OMC2-FIR4.5. Le recensement complet des cyanopolyynes dans IRAS16293 et OMC2- FIR4 avec la détection de HC3N, HC5N, DC3N et pour OMC2-FIR4: le C13 isotopologue du HC3N cyanopolyynes.Ces résultats sont le sujet principal de deux publications (Jaber et al.2014, ApJ; Lopez-Sepulcre, Jaber et al.2015,MNRAS), un article accepté (Jaber et al., A & A) et un article à soumettre (Jaber et al. A & A)
The present PhD thesis goal is the study of the molecular complexity in solar type star forming regions. It specifically focuses on two classes of molecules with a pre-biotic value, the complex organic molecules and the cyanopolyynes.At this scope, I analyzed data from single-dish spectral surveys by means of non-LTE or/and non-LTE radiative transfer codes in two sources, a solar type protostar in an isolated and quiet environment (IRAS16293-2422) and a proto-cluster of solar type protostars (OMC2-FIR4). The goal is to find similarities and differences between these two cases.I used data from two spectra surveys: TIMASSS (The IRAS16293-2422 Millimeter And Submillimeter Spectral Survey), which has been carried out in 2011 (Caux et al. 2011), and ASAI (Astrochemical Surveys At IRAM), which has been carried out in 2013-2015 (e.g. Lopez-Sepulcre et al. 2015).I extracted the lines (identification and integrated intensity) by means of the publicly available package CASSIS (Centre dAnalyse Scientifique de Spectres Infrarouges et Submillimtriques).Finally, I used the package GRAPES (GRenoble Analysis of Protostellar Envelope Spectra) to model the Spectral Line Energy Distribution (SLED) of the detected molecules, and to estimate their abundance across the envelope and hot corino of IRAS16293-2422 and OMC2-FIR4, respectively.The major results of the thesis are:1) The first full census of complex organic molecules (COMs) in IRAS16293-2422;2) The first detection of COMs in the cold envelope of a solar type protostar (IRAS16293-2422), supporting the idea that a relatively efficient formation mechanism for the detected COMs must exist in the cold gas phase;3) The discovery of a tight correlation between the dimethyl ether (DME) and methyl format (MF), suggesting a mother-daughter relationship;4) The detection of formamide, a species with a very high pre-biotic value, in several protostars, included IRAS16293-2422 and OMC2-FIR4;5) The full census of the cyanopolyynes in IRAS16293-2422 and OMC2-FIR4, with the detection of HC3N and HC5N, DC3N and, for OMC2-FIR4, the 13C isotopologue of HC3N cyanopolyynes.These results are the focus of two published articles (Jaber et al. 2014, ApJ; Lopez-Sepulcre, Jaber et al. 2015, MNRAS), one accepted article (Jaber et al., A&A) and a final article to be submitted (Jaber et al., A&A)

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Javelle, Thomas. "Caractérisation de molécules organiques au sein d’analogues d’objets du système solaire". Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0490.

Texto completo

Resumen

La matière organique est une matière dont les molécules contiennent au moins une liaison chimique carbone-hydrogène. Sur Terre, elle est intrinsèquement liée à la biosphère. Cependant, cette matière n’est pas exclusivement liée aux systèmes vivants. Elle peut être liée à des processus biologiques (photosynthèse), géologiques (pétroles) et abiotiques (aérosols secondaires). Elle présente une diversité dans tout le système solaire : les observations suggèrent la présence d’une chimie organique complexe abiotique dans les nuages de Titan, les océans d’Europe et d'Encelade, les roches des météorites ou encore les glaces cométaires. Les comètes sont les objets qui ont été le moins altérés depuis 4,5 milliards d’années. L’étude de leur composition permet de mieux comprendre les processus à origine de la matière organique sur Terre.- Durant cette thèse, la composition possible d’une comète telle qu’elle pourrait être identifiée lors d’une mission spatiale est étudiée. On suppose que la matière organique d’une comète se répartit en deux phases principales : solide ou gazeuse. L’objectif de cette thèse est d’identifier les corrélations existantes entre la composition en matière organique de ces phases. Dans le premier chapitre on détaille les connaissances actuelles concernant la matière organique et les comètes ainsi que les résultats déjà existants dans ce domaine. Dans le deuxième, on décrit les protocoles mis au point durant la thèse pour l’analyse de la phase solide. Dans le troisième, le protocole expérimental permettant l’analyse de la phase gazeuse est présenté. Enfin, dans le dernier, les premiers résultats et premières corrélations mises en évidence sont exposés
Organic matter is at least composed of one carbon-hydrogen bond. It is highly linked to biological activity on earth. However, we know from two centuries old studies that this matter is not exclusively produced from living systems. Three main production and alteration processes can be identified: biological (photosynthesis…), geological (petroleum…) and abiotic (secondary aerosols…). Titan's clouds, Europa's and Enceladus' oceans, meteoritic rocks or even cometary ices… All over the solar system a surprisingly complex abiotic organic chemistry has been found. Among all of these wonderful places, comets are the ones that remained unchanged for almost 4.5 billion years. Studying their composition provides a better understanding of both the solar system formation and the origin of organic matter on Earth. During this PhD thesis, the expected comet composition as space missions would study them is studied. Thus, an original experimental protocol allowing the recovery and identification of organic matter from synthetic comets is developed. The keystone of this study is that organic matter of a comet is divided into two main phases: solid or gaseous. The main objective is to identify the existing correlations between both of them. This manuscript is organized into four chapters. First, the current knowledge linking organic matter and comets as well as the first results in this field is detailed. Second, the developed protocols for cometary analogs solid phase analysis as well as developed tools is described. Third, the gas phase recovery experimental protocol is presented. Lastly, the first results and the first highlighted correlations are shown

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Sule, Aniket. "Formation and stability of the solar tachocline in MHD simulations". Phd thesis, kostenfrei, 2007. http://opus.kobv.de/ubp/volltexte/2007/1461/.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Bowness, Ruth. "Current sheets in the solar corona : formation, fragmentation and heating". Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2081.

Texto completo

Resumen

In this thesis we investigate current sheets in the solar corona. The well known 1D model for the tearing mode instability is presented, before progressing to 2D where we introduce a non-uniform resistivity. The effect this has on growth rates is investigated and we find that the inclusion of the non-uniform term in η cause a decrease in the growth rate of the dominant mode. Analytical approximations and numerical simulations are then used to model current sheet formation by considering two distinct experiments. First, a magnetic field is sheared in two directions, perpendicular to each other. A twisted current layer is formed and we find that as we increase grid resolution, the maximum current increases, the width of the current layer decreases and the total current in the layer is approximately constant. This, together with the residual Lorentz force calculated, suggests that a current sheet is trying to form. The current layer then starts to fragment. By considering the parallel electric field and calculating the perpendicular vorticity, we find evidence of reconnection. The resulting temperatures easily reach the required coronal values. The second set of simulations carried out model an initially straight magnetic field which is stressed by elliptical boundary motions. A highly twisted current layer is formed and analysis of the energetics, current structures, magnetic field and the resulting temperatures is carried out. Results are similar in nature to that of the shearing experiment.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Bendapudi, Sree Satya Kanth. "Novel Film Formation Pathways for Cu2ZnSnSe4 for Solar Cell Applications". Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3005.

Texto completo

Resumen

Because of the anticipated high demand for Indium, ongoing growth of CIGS technology may be limited. Kesterite materials, which replace In with a Zn/Sn couple, are thought to be a solution to this issue. However, efficiencies are still below the 10% level, and these materials are proving to be complex. Even determination of the bandgap is not settled because of the occurrence of secondary phases. We use a film growth process, 2SSS, which we believe helps control the formation of secondary phases. Under the right growth conditions we find 1/1 Zn/Sn ratios and XRD signatures for Cu2ZnSnSe4 with no evidence of secondary phases. The optical absorption profile of our films is also a good match to the CIS profile even for films annealed at 500° C. We see no evidence of phase separation. The effect of intentional variation of the Zn/Sn ratio on material and device properties is also presented.

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

WANG, ZHONG-SHENG. "DYNAMICS ANALYSIS OF SATELLITE FORMATION FLIGHT USING SOLAR RADIATION PRESSURE". University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1005854591.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Lin, Wei-Chun. "IN-SITU SOLAR CELL STUDIES OF PEROVSKITE FORMATION AND DEGRADATION". Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1491403121789203.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Magnusson, Erik y Johan Schedwin. "Development of solar water heating system". Thesis, Högskolan i Skövde, Institutionen för teknik och samhälle, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-4428.

Texto completo

Resumen

This report includes development of an already designed solar water heater. The product shall be constructed in a way that it will suit a manufacturing line in Kampala, Uganda. To find the most suitable design for each area a research was carried out which included study visits, interviews and background reading. It provided the following results: Regarding the attachment of in- and outgoing pipes from the water tank many methods were taken into consideration and it was found that the best and most suitable way for this case is to weld the fittings using a weld robot. Regarding the fitting of the acrylic, a suitable solution is to make a flange when vacuum forming the plastic casing to further support the design. This could also be used to waterproof the case by using a sealing material. A suggestion of using pre-molded PU-foam is also presented. Regarding the ability to open the case for maintenance, two solutions were recommended. Either the use of spire clips or having the clips integrated into the casing. Regarding the calculation of material usage when deep drawing the tank and collector, it is possible to do a reasonably accurate assumption. The complicated design in this product makes the estimation less accurate. It is recommended that test draws are done and often the machine producer has more precise numbers. Regarding the coloring of the collector; chemical coloration is not possible on a galvanized surface. The method used is painting, either with powder coating or with wet paint.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Franklin, Edward A. "Mounting Your Solar Photovoltaic (PV) System". College of Agriculture, University of Arizona (Tucson, AZ), 2017. http://hdl.handle.net/10150/625443.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Flynn, Angela Elizabeth. "Rotational dynamics in the solar system". Thesis, Queen Mary, University of London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420310.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Arden, John Walter. "Lead in the early solar system". Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257664.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Busch, Brian C. "Space-based solar power system architecture". Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/27802.

Texto completo

Resumen

Fossil fuels are, by their very nature, finite resources. There are, however, numerous renewable energy sources that should be taken advantage of. One of the most abundant is also the most difficult to produce on Earthsolar energy. This thesis explores the feasibility of a space-based solar power satellite. The thesis focuses specifically on the satellite design as opposed to the end-to-end design to include the ground segment. It explores the potential orbits for such a satellite to operate from and ultimately concludes that a geostationary orbit is the only logical location for an operational orbit. This thesis also focuses on two segments of the spacecraft the solar array and the power transmission payload. The solar array area was calculated using the current best theoretical solar cells and assumed a 1 GW transmission power. Finally, this thesis explored which transmission payload to recommend for an operational system, concluding that a laser system is the most efficient use of space and weight. The final portion of this thesis was to examine the business case. Based on the design in this thesis, space-based solar power cannot compete with fossil fuels and likely will not for the foreseeable future.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Court, Richard W. "Organic polymerisation in the solar system". Thesis, Open University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427735.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Kargel, Jeffrey Stuart. "Cryomagmatism in the outer solar system". Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185177.

Texto completo

Resumen

Cryovolcanism has played an important role in the geological histories of many icy satellites. Cryovolcanism, like the more familiar silicate volcanism on Earth and the other terrestrial planets, takes many forms. Many individual cryovolcanic landforms are morphologically surprisingly similar to terrestrial volcanic landforms and can be explained with similar mechanisms. However, assemblages of cryovolcanic, tectonic, and impact structures form unique and varied landscapes quite alien in their collective expression. Many variables can affect the cryovolcanic style of a satellite but none more so than cryolava composition. This work considers the compositional variable in considerable detail. This work summarises existing knowledge of phase equilibria and physical properties of cosmochemically relevant unary, binary, and multi-component chemical systems, and where published knowledge was found lacking, the author presents his own measurements of the physical chemistry of volatile mixtures. The author then takes the reader on a brief tour of cryovolcanic landscapes, and applies knowledge of the physical chemistry of volatile mixtures to problems of cryovolcanological interest. Aqueous cryolavas may range in composition from salt-water brines to cryogenic ammonia-water-rich multi-component solutions possibly involving methanol, ammonium sulfide, alkali chlorides, and many other potential components. Cryomagmatic distillation can greatly accentuate the importance of trace and minor constituents of icy satellites. The viscosities, densities, and other physical properties of these liquids vary considerably and depend sensitively on their exact compositions. These properties affect everything from cryovolcanic eruptive styles and landforms, to the way cryovolcanic crusts respond to tectonic stresses. It is believed that the compositional variable is directly or indirectly implicated in a wide variety of geomorphic aspects of contrast among the icy satellites. Thus, even though we can not as yet confidently attribute any specific morphology to a specific composition (for lack of in situ compositional analyses), there appears to be a powerful link between the composition of the ices originally accreted by a satellite and its subsequent interior evolution and exterior geomorphic appearance.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Dorn, Lawrence Tyrone. "NPS-SCAT electrical power system". Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Sep/09Sep_Dorn.pdf.

Texto completo

Resumen

Thesis (M.S. in Space Systems Operations)--Naval Postgraduate School, September 2009.
Thesis Advisor(s): Newman, James H. "September 2009." Description based on title screen as viewed on November 5, 2009. Author(s) subject terms: Satellite, CubeSat, NPS-SCAT, solar cell tester, Power system, Clyde Space, Spectrolabs, improved triple junction, solar power. Includes bibliographical references (p. 83-85). Also available in print.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Постол, В. О. "Enterprise risk management system formation". Thesis, Чернігів, 2020. http://ir.stu.cn.ua/123456789/20040.

Texto completo

Resumen

Postol, V. O. Enterprise risk management system formation=Формування системи управління ризиками підприємства : дипломна робота : 073 Менеджмент / В. О. Постол ; керівник роботи Дука А. П. ; Національний університет «Чернігівська політехніка», кафедра публічного управління та менеджменту організацій. – Чернігів, 2020. – 83 с.
The work is devoted to the theoretical and practical aspects of revealing the essence of the formation of the enterprise risk management system in market conditions. The work consists of three sections, introduction and conclusions. The introduction substantiates the relevance of the topic, purpose and objectives of the thesis. The first section reveals the theoretical foundations of the concept of risk, highlights the issues of risk management of the enterprise. The system of measures of formation of the risk management system of the enterprise is considered. The second section considers the methodological aspects of forming a risk management system. This section contains a description of the tools for forming a risk management system in the enterprise, highlights the organizational structure of the risk management system in the enterprise, describes a system of indicators for assessing the risks of the enterprise. The third section contains proposals for building a risk management algorithm on the example of innovation, recommendations for the implementation of risk management system of innovation in the enterprise. The conclusions contain generalizations of the problems of the enterprise, measures to solve the problems of the enterprise.
Робота присвячена теоретичним та практичним аспектам розкриття сутності формування системи управління ризиками підприємства в умовах ринку. Робота складається з трьох розділів, вступу та висновків. У вступі обґрунтовується актуальність теми, мета і завдання дипломної роботи. У першому розділі розкриті теоретичні основи поняття ризиків, висвітлені питання управління ризиками діяльності підприємства. Розглянуто систему заходів формування системи управління ризиками підприємства. У другому розділі розглянуто методичні аспекти формування системи управління ризиками. У цьому розділі міститься характеристика інструментів формування системи ризик-менеджменту в діяльності підприємства, висвітлені питання організаційної структури системи ризик-менеджменту в діяльності підприємства, описана система показників оцінки ризиків діяльності підприємства. Третій розділ містить пропозиції щодо побудови алгоритму ризик-менеджменту на прикладі здійснення інноваційної діяльності, наведені рекомендації з впровадження системи ризик-менеджменту інноваційної діяльності на підприємстві. У висновках містяться узагальнення проблем підприємства, заходів щодо вирішення проблем діяльності підприємства.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Сема, І. М. "Enterprise risk management system formation". Thesis, Чернігів, 2020. http://ir.stu.cn.ua/123456789/20042.

Texto completo

Resumen

Sema, І. М. Enterprise risk management system formation=Формування конкурентної стратегії розвитку підприємства : дипломна робота : 073 Менеджмент / І. М. Сема ; керівник роботи Дука А. П. ; Національний університет «Чернігівська політехніка», кафедра публічного управління та менеджменту організацій. – Чернігів, 2020. – 76 с.
The work is devoted to theoretical and practical aspects of revealing the essence of formation of competitive strategy of enterprise development. The work consists of three sections, introduction and conclusions. The introduction substantiates the relevance of the topic, purpose and objectives of the thesis. The first section reveals the theoretical foundations of the concept of competition, competitiveness. The system of measures of formation is considered. The questions of formation of competitive strategy of the enterprise are covered. In the second section the methodical aspects of formation of competitive strategy for the enterprise are considered. Features of application of competitive advantages according to M. Porter are revealed. Based on the generalization of the agricultural sector in Ukraine, the position of the enterprise is analyzed, the PEST-analysis of the formation of market advantages is carried out. general characteristics of risk management. This section contains a description of the activities of the enterprise, covers issues of economic activity of LLC agro-industrial enterprise "RESSKI". The third section contains proposals for the formation of a competitive strategy for the development of LLC, recommendations for the implementation of a competitive strategy for the company. The conclusions contain generalizations of the problems of the enterprise, measures to solve the problems of the enterprise.
Робота присвячена теоретичним та практичним аспектам розкриття сутності формування конкурентної стратегії розвитку підприємства. Робота складається з трьох розділів, вступу та висновків. У вступі обґрунтовується актуальність теми, мета і завдання дипломної роботи. У першому розділі розкриті теоретичні основи поняття конкуренції, конкурентоспроможності. Розглянуто систему заходів формування висвітлені питання формування конкурентної стратегії підприємства. У другому розділі розглянуто методичні аспекти формування конкурентної стратегії для підприємства Розкриті особливості застосування конкурентних переваг за М. Портером. На основі узагальнення аграрної сфери в Україні, проаналізовано позизії підприємства, здійснено PEST-аналіз формування переваг на ринку. загальної характеристики управління ризиками. У цьому розділі міститься характеристика діяльності підприємства, висвітлені питання особливостей господарської діяльності ТОВ агропромислового підприємства «РЕССКІ». Третій розділ містить пропозиції щодо формування конкурентної стратегії розвитку ТОВ, наведені рекомендації з впровадження конкурентної стратегії для підприємства. У висновках містяться узагальнення проблем підприємства, заходів щодо вирішення проблем діяльності підприємства.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

LI, HONGMING. "APPLICATION OF SOLAR RADIATION PRESSURE TO FORMATION CONTROL NEAR LIBRATION POINTS". University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1205166301.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Tesis sobre el tema "Formation of the solar system"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros