Graded Quivers, Generalized Dimer Models and Toric Geometry

The open string sector of the topological B-model model on CY $(m+2)$-folds is described by $m$-graded quivers with superpotentials. This correspondence extends to general $m$ the well known connection between CY $(m+2)$-folds and gauge theories on the worldvolume of D$(5-2m)$-branes for $m=0,\ldots, 3$. We introduce $m$-dimers, which fully encode the $m$-graded quivers and their superpotentials, in the case in which the CY $(m+2)$-folds are toric. Generalizing the well known $m=1,2$ cases, $m$-dimers significantly simplify the connection between geometry and $m$-graded quivers. A key result of this paper is the generalization of the concept of perfect matching, which plays a central role in this map, to arbitrary $m$. We also introduce a simplified algorithm for the computation of perfect matchings, which generalizes the Kasteleyn matrix approach to any $m$. We illustrate these new tools with a few infinite families of CY singularities.Comment: 54 pages, 6 figure

Estudio de cortocircuitos bifásicos a tierra del sistema eléctrico de Pereira, analizando sus efectos sobre el nodo en falla

Un sistema eléctrico de potencia es un conjunto de elementos que permiten la interconexión de los grandes centros de generación con grandes centros de consumo, para esto se requiere transmitir grandes cantidades de potencia a niveles elevados de tensión. Los estudios de cortocircuito juegan un papel importante en el análisis de los sistemas eléctricos de potencia en el momento del planeamiento y selección de equipos eléctricos. Para el estudio de cortocircuito se requieren procedimientos precisos y confiables, dando lugar a procedimientos normalizados, estos se usan con el fin de calcular corrientes de cortocircuito en los sistemas eléctricos. La norma IEC de origen europeo y el ANSI/IEEE de origen norteamericano dan resultados que sirven para seleccionar interruptores de circuitos y diseñar esquemas de protecciones

BFT2_2: a General Class of 2d2d N=(0,2)\mathcal{N}=(0,2) Theories, 3-Manifolds and Toric Geometry

We introduce and initiate the study of a general class of $2d$ $\mathcal{N}=(0,2)$ quiver gauge theories, defined in terms of certain 2-dimensional CW complexes on oriented 3-manifolds. We refer to this class of theories as BFT$_2$\mbox{'}s. They are natural generalizations of Brane Brick Models, which capture the gauge theories on D1-branes probing toric Calabi-Yau 4-folds. The dynamics and triality of the gauge theories translates into simple transformation of the underlying CW complexes. We introduce various combinatorial tools for analyzing these theories and investigate their connections to toric Calabi-Yau manifolds, which arise as their master and moduli spaces. Invariance of the moduli space is indeed a powerful criterion for identifying theories in the same triality class. We also investigate the reducibility of these theories.Comment: 44 pages, 32 figure

Diseño e implementación de un sistema fotovoltaico interconectado a red con soporte de almacenamiento en la Universidad Tecnológica de Pereira

Este proyecto comprende el diseño e implementación de un sistema fotovoltaico con interconexión a la red trifásica del sector vivero de la Universidad Tecnológica de Pereira, para el suministro energético del jardín botánico del jardín botánico, incentivando el uso de energías renovables en la región. El aporte tecnológico generado por y para la universidad brinda como solución la generación de energía eléctrica de forma autónoma a bajo costo, de manera eficiente usando tecnologías hibridas de mayor rendimiento, siendo este un proyecto líder en energías renovables en Colombia. Todo el proceso de diseño e implementación genera como resultado un trabajo de investigación que aporta al desarrollo de la generación de energías renovables, análisis de eficiencia, planos eléctricos, programación de equipos y disposición de energía acumulada, afianzado así lo aprendido durante el periodo de formación

El retraimiento militar de la nobleza castellana con motivo de la guerra franco-española (1635-1648). El ejemplo contrapuesto del Reino de Murcia.

Frente a la positiva actitud de la nobleza francesa, que acude masivamente a la llamada de Luis XIII para llevar a cabo la guerra contra la Monarquía Hispánica, la nobleza castellana mostró una actitud retraída y no cumplió con la función que le correspondía por su status: la guerra. El detallado análisis de las hidalguías del Reino de Murcia demuestra la forma contrapuesta en que desempeñaron sus obligaciones militares

Kinetic and chemorheological modeling of thermosetting polyurethanes obtained from an epoxidized soybean oil polyol crosslinked with glycerin

Thermosetting polyurethanes were obtained using an aromatic isocyanate and a hydrophobic polyol formulation obtained from epoxidized soybean oil (ESO) crosslinked with glycerin. A systematic DSC analysis of the effect of catalyst type, crosslinker concentration, isocyanate index and ESO crystallization on the cure kinetics was conducted. The combination of a stannic catalyst at 0.2 wt.\% and glycerin at 20 wt.\% produced a cure kinetics governed by autocatalytic heat flow where vitrification played a key role in the formation of chemical bonds. The evolution of Tg as a function of conversion, which followed Di-Benedetto{\'}s predictions, supported the hypothesis that vitrification was a preponderant phenomenon during cure. The ESO crystallization had a melting endotherm centered at 35{\deg}C, affecting substantially the availability of reactive hydroxide groups. Dynamic Mechanical Analysis (DMA) of a post-cured sample revealed a Tg centered at 220{\deg}C, whereas quasi-static flexural mechanical tests revealed a flexural modulus of 2.14 GPa and a flexural strength of 99.4 MPa. Rheological experiments using a rheometer at isothermal conditions supported the hypothesis that vitrification played a key role in the evolution of apparent viscosity. A master model using Kim-Macosko equations was obtained for the proposed formulation

Comportamiento de una mezcla asfáltica densa en frío adicionada con partículas de policloruro de vinilo (PVC)

Trabajo de investigaciónEsta investigación está enfocada a la modificación de una mezcla asfáltica densa en frío MDF 20 la cual se le adicionaran partículas granulares de Policloruro de vinilo PVC y mediante ensayos de Inmersión-compresión, falla por ensayo Marshall y tracción indirecta RTI evaluar su comportamiento en estado seco y húmedo.INTRODUCCIÓN 1. MARCO TEORICO 2. PROCEDIMIENTO 3. ENSAYOS DE LABORATORIO 4. ANALISIS Y RESULTADOS 5. CONCLUSIONES 6. RECOMENDACIONES BIBLIOGRAFÍAEspecializaciónEspecialista en Ingeniería de Pavimento

Bipartite field theories and D-brane instantons

We study D-brane instantons in systems of D3-branes at toric CY 3-fold singularities. The instanton effect can be described as a backreaction modifying the geometry of the mirror configuration, in which the breaking of U(1) symmetries by the instanton translates into the recombination of gauge D-branes, which also directly generates the instanton-induced charged field theory operator. In this paper we describe the D-brane instanton backreaction in terms of a combinatorial operation in the bipartite dimer diagram of the original theory. Interestingly, the resulting theory is a general Bipartite Field Theory (BFT), defined by a bipartite graph tiling a general (possibly higher-genus) Riemann surface. This provides the first string theory realization of such general BFTs. We study the general properties of the resulting theories, including the construction of the higher-dimensional toric diagrams and the interplay between backreaction and Seiberg duality. In cases where the non-perturbative effects relate to complex deformations, we show that the procedure reproduces and explains earlier existing combinatorial recipes. The combinatorial operation and its properties generalize to an operation on the class of general BFTs, even including boundaries, relating BFTs defined on Riemann surfaces of different genusThe work of S. F. is supported by the U.S. National Science Foundation grant PHY-1518967. He also gratefully acknowledges the Tsinghua Sanya International Mathematics Forum (TSIMF) for hosting the Workshop on SCFTs in Dimension 6 and Lower, where part of this project was carried out. E. G. and A. U. are partially supported by the grants FPA2015-65480-P from the MEIC/FEDER, the ERC Advanced Grant SPLE under contract ERC-2012-ADG-20120216-320421 and the grant SEV-2016-0597 of the "Centro de Excelencia Severo Ochoa" Programm