Noticias en español
Seminars appear in decreasing order in relation to date. To find an activity of your interest just go down on the list. Normally seminars are given in english. If not, they will be marked as Spanish Only.
Sumas iteradas para clasificación de series de tiempo.
Resumen La clasificación de series de tiempo es una tarea recurrente en ciencia de datos. Usualmente, los datos son transformados de alguna forma para producir una representación concisa, preservando simetrías de interés. En esta charla, presentaré una serie de trabajos que describen cómo las sumas iteradas de una serie de tiempo contienen todas las cantidades (features) polinomiales invariantes bajo realinamiento temporal (time warping). Describiré también como se transforma esta representación bajo la aplicación de cierta clase funciones no...
Virtual levels and virtual states of operators in Banach spaces.
Abstract: Virtual levels admit several equivalent characterizations: (1) there are corresponding eigenstates from L^2 or a space “slightly weaker” than L^2; (2) there is no limiting absorption principle in the vicinity of a virtual level (e.g. no weights such that the “sandwiched” resolvent remains uniformly bounded); (3) an arbitrarily small perturbation can produce an eigenvalue. We develop a general approach to virtual levels in Banach spaces and provide applications to Schroedinger operators with non selfadjoint...
Adaptive bin packing with overflow.
Abstract: Motivated by the allocation of virtual machines into servers in the cloud, we consider the online problem of packing items with random sizes into unit-capacity bins. Items arrive sequentially, but upon arrival an item’s actual size is unknown; only its probabilistic information is available to the decision maker. Without knowing this size, the decision maker must irrevocably pack the item into an available bin or place it in a new bin. Once packed in a bin, the decision maker observes the item’s actual size, and overflowing the bin...
Anisotropic harmonic maps and Ginzburg-Landau type relaxation.
Abstract: Consider maps $u:R^n\to R^k$ with values constrained in a fixed submanifold, and minimizing (locally) the energy $E(u)=\int W(\nablau)$. Here $W$ is a positive definite quadratic form on matrices. Compared to the isotropic case $W(\nabla u)=|\nabla u|^2$ (harmonic maps) this may look like a harmless generalization, but the regularity theory for general $W$’s is widely open. I will explain why, and describe results with Andres Contreras on a relaxed problem, where the manifold-valued constraint is replaced by an integral...
City logistics and smart delivery.
Abstract: he current and expected growing number of people living and working in cities and the limited space available inside city centres implies a greater exchange of inbound and outbound freight flows between city centres and their surrounding regions. Urban freight transports provide economic benefits to society but are also responsible for negative externalities such as congestion, air and water pollution, climate change, accidents and noise. Access restrictions are one of the most applied measures to control urban traffics in the...
COVID-19: Short-term forecast of ICU beds in times of crisis.
Abstract: By early May 2020, the number of new COVID-19 infections started to increase rapidly in Chile, threatening the ability of health services to accommodate all incoming cases. Suddenly, ICU capacity planning became a first-order concern, and the health authorities were in urgent need of tools to estimate the demand for urgent care associated with the pandemic. In this article, we describe the approach we followed to provide such demand forecasts, and we show how the use of analytics can provide relevant support for decision...
On the construction of maximal p-cyclically monotone operators.
Abstract: In this talk we deal with the construction of explicit examples of maximal p-cyclically maximal monotone operators. To the date, there is only one instance of an explicit example of a maximal 2-cyclically monotone operator that is not maximal monotone. We present several other examples, and a proposal of how such examples can be constructed.
Optimization of a Concentrated Solar Power plant.
Abstract This report corresponds to the continuation of another where the characteristics of the parameters and methods of each one of the objects called Parameters, SolarField, Rankine and Reactor were detailed. Here we will present the components of the objective function of the optimization problem described in section 2, which corresponds to the income and costs generated by the concentrated solar power plant for a period of Nyears, as well as the constraints and bounds related to the variables of the problem. Then we...
Eigenvalue splitting of polynomial order for a system of Schrödinger operators with energy-level crossing.
In this talk I will present recent results on the spectral analysis of a 1D semiclassical system of coupled Schrödinger operators each of which has a simple well potential. Such systems arise as important models in the Born-Oppenheimer approximation of molecular dynamics. Focusing on the cases where the two underlying classical periodic trajectories cross to each other which imply an energy-level crossing, we give Bohr-Sommerfeld type quantization rules for the eigenvalues of the system in both tangential and transversal crossing cases. Our...
Aumentando óptimamente la nodo-conectividad de un ciclo en uno.
Abstract: “Definimos el problema de “aumentación de conectividad de grafos” de la forma siguiente: La entrada es un grafo G y un conjunto de aristas E, tal que G es k-conexo y G+E es (k+1)-conexo. Y la salida debe ser un subconjunto F de E de tamaño mínimo tal que G+F sea (k+1)-conexo. Este tipo de problemas se enmarcan en el diseño de redes, muy importante en áreas tales como telecomunicaciones y electricidad. Muchos de estos problemas son NP-dificiles, por lo que es necesario diseñar algoritmos de aproximación para atacar...
