Recent Additions
- Some of the metrics are blocked by yourconsent settings
Thesis Reducción Dimensional Afín: Un Enfoque Kaluza-Klein sin Métrica Preexistente(Universidad Técnica Federico Santa María, 2026)En este trabajo, desarrollamos una generalización de la teoría de Kaluza-Klein considerando un marco puramente afín, sin asumir una estructura métrica previa. Formulamos la reducción dimensional utilizando la geometría de los haces principales de fibras y la conexión de Ehresmann, introduciendo bases adaptadas que permiten una descomposición explícita de tensores, vectores y conexiones. Este formalismo proporciona una definición geométrica natural del campo electromagnético como la diferencia entre el espacio horizontal y el espacio generado por el marco del observador. Demostramos que la presencia de un campo electromagnético no trivial requiere la no integrabilidad de la distribución horizontal, y derivamos un ansatz completo para descomponer la conexión afín en campos definidos en el espacio reducido. Bajo supuestos como torsión nula, fibras autoparalelas y condiciones de normalización adecuadas, demostramos que la teoría reducida corresponde al sistema de Einstein-Maxwell para campos electromagnéticos puramente radiativos. Además, proponemos una interpretación donde la métrica emerge dinámicamente de la estructura afín a través de la dinámica del campo electromagnético. - Some of the metrics are blocked by yourconsent settings
Publication A review on mechanical alloying and spark plasma sintering of refractory high-entropy alloys: Challenges, microstructures, and mechanical behavior(Elsevier BV, 2024-05)Refractory high-entropy alloys (RHEAs) are promising candidates for those applications requiring of strong materials at high temperatures with elevated thermal stability and excellent oxidation, irradiation, and corrosion resistance. Particularly, RHEAs synthesized using mechanical alloying (MA) followed by spark plasma sintering (SPS) has proven to be a successful path to produce stronger alloys than those produced by casting techniques. This superior behavior, at both room and high temperature, can be attributed to the microstructural features resultant from this powder metallurgy route, that include the presence of homogeneously distributed nonmetallic particles, fine- and ultrafine-grained microstructures, and higher content of interstitial solutes. Nevertheless, the powder metallurgy fabrication relies over a complex balance of several operational variables, and the process is no exempt of certain challenges, such as contamination or the presence of pores in the bulk parts. This review aims to cover all the peculiarities of the MA + SPS route, the resultant microstructures, their mechanical properties, and the strengthening and deformation mechanisms behind their superior performance, as well as a brief description of their oxidation resistance. - Some of the metrics are blocked by yourconsent settings
Publication A precise measurement of the Z-boson double-differential transverse momentum and rapidity distributions in the full phase space of the decay leptons with the ATLAS experiment at s=8 TeV(Springer Science and Business Media LLC, 2024-03-25)This paper presents for the first time a precise measurement of the production properties of the Z boson in the full phase space of the decay leptons. This is in contrast to the many previous precise unfolded measurements performed in the fiducial phase space of the decay leptons. The measurement is obtained from proton-proton collision data collected by the ATLAS experiment in 2012 at root s = 8 TeV at the LHC and corresponding to an integrated luminosity of 20.2 fb(-1). The results, based on a total of 15.3 million Z-boson decays to electron and muon pairs, extend and improve a previous measurement of the full set of angular coefficients describing Z-boson decay. The double-differential crosssection distributions in Z-boson transverse momentum p(T) and rapidity y are measured in the pole region, defined as 80 < m(ll) < 100 GeV, over the range vertical bar y vertical bar < 3.6. The total uncertainty of the normalised cross-section measurements in the peak region of the p(T) distribution is dominated by statistical uncertainties over the full range and increases as a function of rapidity from 0.5-1.0% for vertical bar y vertical bar < 2.0 to 2 - 7% at higher rapidities. The results for the rapidity-dependent transverse momentum distributions are compared to state-of-the-art QCD predictions, which combine in the best cases approximate (NLL)-L-4 resummation with (NLO)-L-3 fixed-order perturbative calculations. The differential rapidity distributions integrated over p(T) are even more precise, with accuracies from 0.2-0.3% for vertical bar y vertical bar < 2.0 to 0.4-0.9% at higher rapidities, and are compared to fixed-order QCD predictions using the most recent parton distribution functions. The agreement between data and predictions is quite good in most cases. - Some of the metrics are blocked by yourconsent settings
Publication A polynomial system of degree four with an invariant triangle containing at least four small amplitude limit cycles(Mathematical Notes, 2024)In this work, the existence of a polynomial system of degree four with an invariant triangle containing at least four small-amplitude limit cycles is proved. This result improves the result obtained in [2]. - Some of the metrics are blocked by yourconsent settings
Publication A Polynomial System of Degree Four with an Invariant Square Containing At Least Five Limit Cycles(Springer Science and Business Media LLC, 2024-07-26)We consider a class of polynomial systems of degree four with four real invariant straight lines that form a square, called this an invariant square, and also that contains in its interior at least five small amplitude limit cycles for a certain choice of the parameters. Moreover, we will obtain the necessary and sufficient conditions for the critical point inside the square to be a center.
Most viewed
- Some of the metrics are blocked by yourconsent settings
Organizational Unit - Some of the metrics are blocked by yourconsent settings
Thesis Retroceso glaciar en la zona central de Chile, causas antrópicas y consecuencias hídricas(Universidad Técnica Federico Santa María, 2023)La zona central de Chile, especialmente la Cordillera de los Andes, alberga una de las criósferas más diversas del planeta y constituye una fuente crítica de recursos hídricos almacenados en forma de nieve y hielo glaciar. Estudios recientes han evidenciado un retroceso significativo de glaciares en esta región, especialmente en la cuenca del río Maipo, como consecuencia del cambio climático global y de factores antrópicos locales. Investigaciones han mostrado que la reducción en la acumulación nival invernal, junto con el aumento de temperaturas estivales, ha derivado en una severa sequía prolongada, conocida como Megasequía. A través de diversos estudios glaciológicos y análisis satelitales, se ha documentado la disminución de superficie y volumen de glaciares emblemáticos como Echaurren Norte, El Morado y Olivares Alfa, todos ubicados en los Andes Centrales. Además, se ha identificado una influencia directa de contaminantes como el carbono negro (Black Carbon, BC) y material particulado (MP) en la aceleración del derretimiento glaciar. Estos contaminantes, emitidos por actividades industriales y vehiculares, reducen el albedo de la superficie glaciar, favoreciendo la absorción de radiación solar y, por ende, el derretimiento. Un caso ilustrativo es el Glaciar Olivares Alfa, cuyo mayor retroceso ha sido asociado a su cercanía con faenas mineras, en contraste con el Glaciar Bello, ubicado en la misma cuenca pero con menor exposición a dichas emisiones. Pese a los avances, aún existe escasa investigación nacional que permita cuantificar con precisión el impacto de estas causas antrópicas sobre los glaciares y los recursos hídricos. Las diferencias en las tasas de retroceso entre glaciares sometidos a condiciones climáticas similares sugieren la necesidad urgente de más estudios enfocados en la influencia de la contaminación local. - Some of the metrics are blocked by yourconsent settings
Organizational Unit
Política de Privacidad 
