913 research outputs found
Astrophysical parameter determination using chaotic orbital regions
The goal of this thesis is to show that chaotic orbits of a dynamical system are advantageous (compared with regularnes) to determine the characteristic parameters of the system, and to give an estimate about the behaviour of the error as a function of the number of observations. The utility of chaotic trajectories for parameter determination in a complex dynamical system such as the restricted full three-body problem is assessed. The model takes into consideration the motion of a particle of negligible mass around a binary system where the main body is modeled as a tri-axial ellipsoid, taking into account its mass distribution, and the smaller one as point mass sphere. It is studied by means of a program coded in Python, capable of simulating the binary system gravity field and propagating trajectories in three dimensions around it. It returns verification values such as the Jacobi constant, the state transition matrix and crashing event assessment allowing lots of flexibility in the parameter settings. A combination of Poincaré maps, which allow to study the periodicity of a trajectory in a visual way; and mathematical tools such as the finite time Lyapunov exponents and the Pesin entropy formula, which indicate how sensitive a trajectory is to initial conditions (main condition for chaotic behaviour) is used. They return similar and reliable values providing redundancy and robustness to the procedure. For the determination of parameters we have developed a procedure, based on least squares approximations, that determines how much the uncertainty in the parameter determination of the system decreases as more measurements are taken. There is a strong correlation between the error in the parameter determination and the length of the trajectory, obviously, the error is reduced as more measurements are taken. If N denotes the number of measurements, for a regular orbit the uncertainty in the determination behaves as N^-(1/2). For chaotic orbits we have found scalings of up to N^-3, which are better than the scalings found in previous works for simple systems, which were between N^-1 and N^-2
Design and construction of a picosatellite’s primary structure by using 3D printing technologies
The viability of developing the design and manufacture of the structure of a small satellite CubeSat, at the School of Telecommunications and Aerospace Engineering of Castelldefels( EETAC), at the Polytechnical University of Catalonia (UPC), is analyzed. The design and detailed simulations of the most relevant mechanical tests have been performed by using the software SolidWorks. A honeycomb pattern monocoque structural design -called Hexagon- is proposed for a single unit CubeSat primary structure. Additionaly, Hexagon's mechanical behaviour is compared to that of the operational CubeSat structure Pumpkin. A preliminary viability study is developed, based on the results of structure simulations and theoretical studies. The resulting structure meets the corresponding CubeSat design requirements, both at the Qualification and at the Acceptance testing levels. Therefore Hexagon can be considered a viable design of a CubeSat's primary structure. After a process of research of manufacture techniques and appropriate materials, we propose to use laser sintering 3D-printing, and justify its convenience versus the use of traditional construction technologies. We suggest the material to use is a polyamide based (PA11) carbon fiber reinforced composite (PA11CF), provided by ADVANC3D Materials. We describe the construction and testing procedure and justify that the entire process can be completed by EETAC students, using equipment available to them. Finally, we propose the lines of future work to test PA11CF and, eventually, build and test the entire CubeSat structure
Perfect Necklaces
We introduce a variant of de Bruijn words that we call perfect necklaces. Fix
a finite alphabet. Recall that a word is a finite sequence of symbols in the
alphabet and a circular word, or necklace, is the equivalence class of a word
under rotations. For positive integers k and n, we call a necklace
(k,n)-perfect if each word of length k occurs exactly n times at positions
which are different modulo n for any convention on the starting point. We call
a necklace perfect if it is (k,k)-perfect for some k. We prove that every
arithmetic sequence with difference coprime with the alphabet size induces a
perfect necklace. In particular, the concatenation of all words of the same
length in lexicographic order yields a perfect necklace. For each k and n, we
give a closed formula for the number of (k,n)-perfect necklaces. Finally, we
prove that every infinite periodic sequence whose period coincides with some
(k,n)-perfect necklace for any n, passes all statistical tests of size up to k,
but not all larger tests. This last theorem motivated this work
Methodologies to detect leakages from geological carbon storage sites
2014 Summer.Includes bibliographical references.Geological carbon storage (GCS) has been proposed as a favorable technology to reduce carbon dioxide (CO2) emissions to the atmosphere. Candidate storage formations include abandoned oil and natural gas reservoirs, un-mineable coal seams, and deep saline aquifers. The large global storage capacity and widespread occurrence of deep saline formations make them ideal repositories of large volumes of CO2, however they generally lack of data for geological characterization in comparison to oil and gas reservoirs. Thus, properties of the injected formation or the sealing formation are unknown, which implies that the evolution and movement of the CO2 plume are uncertain in these geological formations. The first part of this research aims to provide an understanding of the main sources of uncertainty during the injection of CO2 that cause leakage variability and fluid pressure change near the injection well, which could be responsible for fracturing the sealing formation. With this purpose the effect of uncertain parameters such as permeability and porosity of injected aquifer, permeability of CO2 leakage pathways through the sealing layers, system compressibility, and brine residual saturation are investigated using stochastic and global sensitivity analyses. These analyses are applied to a potential candidate site for GCS located at the Michigan Basin. Results show aquifer permeability and system compressibility are the most influential parameters on fluid overpressure and CO2 mass leakage. Other parameters, such as rock porosity, permeability of passive wells, and brine residual saturation do not influence fluid overpressure nearby the injection well. CO2 mass leakage is found to be sensitive to passive well permeability as well as the type of statistical distribution applied to describe well permeability. Scarce data of the Michigan Basin exist that can be used directly to describe the spatial distribution at the basin scale of the caprock overlying the candidate site. The continuity of this formation is uncertain. The second part of this investigation explores the application of binary permeability fields for the study of CO2 leakage from GCS at the candidate site. A sequential indicator simulation algorithm is used to populate binary permeability fields representing a caprock formation with potential leaky areas (or inclusions). Results of the caprock continuity uncertainty conclude that increasing the probability of inclusions occurrence increases the CO2 leakage. In addition, the correlation length used by the sequential indicator simulator affects the occurrence of inclusions. The third part investigates the detection and location of the presence of possible brine or carbon leakage pathways at the caprock during the injection operations of a GCS system. A computational framework for the assimilation of changes in head pressure data into a subsurface flow model is created to study the evolution of the CO2 plume and brine movement. The capabilities of two data assimilation algorithms, the ensemble smoother (ES) and the ensemble Kalman smoother (EnKS), to identify and locate the leaky pathways are examined. Results suggest that the EnKS is more effective than the ES in characterizing caprock discontinuities
Effect of Industry 4.0 on Education Systems: An Outlook
Congreso Universitario de Innovación Educativa En las Enseñanzas Técnicas, CUIEET (26º. 2018. Gijón
Sobresaliente en Derechos Humanos
Unidad didáctica premiada.Este trabajo desde el punto de vista metodológico pretende introducir
de forma sistemática en la programación actividades que contribuyan
a desarrollar la destreza de expresión oral (y la indisociable
comprensión auditiva) en vertientes como la exposición,
argumentación o interacción, pues "las actividades de interacción, en
general, son esenciales en cualquier metodología que se asiente sobre
bases comunicativas". A su vez, la práctica interactiva consolida lo
aprendido o conocido, pasando “a una fase más activa en la cual se
libera la potencialidad de los alumnos para producir ellos mismos
lenguaje comunicativo”.Ministerio de Educación, Cultura y Deporte del Gobierno de España
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