Floquet Fractional Chern Insulator in Doped Graphene

Fractional Chern insulators are theoretically predicted states of electronic matter with emergent topological order. They exhibit the same universal properties as the fractional quantum Hall effect, but dispose of the need to apply a strong magnetic field. However, despite intense theoretical work, an experimental realization for these exotic states of matter is still lacking. Here we show that doped graphene turns into a fractional Chern insulator, when irradiated with high-intensity circularly polarized light. We derive the effective steady state band structure of light-driven graphene using Floquet theory and subsequently study the interacting system with exact numerical diagonalization. The fractional Chern insulator state equivalent to the 1/3 Laughlin state appears at 7/12 total filling of the honeycomb lattice (1/6 filling of the upper band). The state also features spontaneous ferromagnetism and is thus an example of the spontaneous breaking of a continuous symmetry along with a topological phase transition.Comment: 10 page

Ensayos Filosóficos

Apreciación de la filosofía analítica. Rubén Sierra Mejía. Universidad Nacional de Colombia, Bogotá, 1987, 134 págs

Criticality Analysis for Maintenance Purposes: A Study for Complex In‐service Engineering Assets

The purpose of this paper is to establish a basis for a criticality analysis, considered here as a prerequisite, a first required step to review the current maintenance programs, of complex in‐service engineering assets. Review is understood as a reality check, a testing of whether the current maintenance activities are well aligned to actual business objectives and needs. This paper describes an efficient and rational working process and a model resulting in a hierarchy of assets, based on risk analysis and cost–benefit principles, which will be ranked according to their importance for the business to meet specific goals. Starting from a multicriteria analysis, the proposed model converts relevant criteria impacting equipment criticality into a single score presenting the criticality level. Although detailed implementation of techniques like Root Cause Failure Analysis and Reliability Centered Maintenance will be recommended for further optimization of the maintenance activities, the reasons why criticality analysis deserves the attention of engineers and maintenance and reliability managers are precisely explained here. A case study is presented to help the reader understand the process and to operationalize the mode

ANÁLISIS DEL COMPORTAMIENTO A FATIGA DE UN ACERO AISI 1045 EN UN AMBIENTE DE JUGO DE CAÑA DE AZÚCAR

Se ha estudiado la sinergia de la fatiga en flexión rotatoria y la corrosión por jugo de caña para un acero AISI (SAE) 1045, usando probetas normalizadas de fatiga. Para las pruebas se usó jugo de caña degradado con pH 4, típico del cuarto molino. Durante la rotación de las probetas se aplicó un flujo continuo de jugo de caña. Se hicieron comparaciones entre las pruebas normalizadas en seco y las que fueron sometidas al ambiente corrosivo. Estas últimas presentaron una disminución del 11 % en el límite de resistencia a fatiga. Estos resultados son aplicables para las zonas del eje que no están protegidas con lubricante

Rubric or assessment matrix, planning tools and implementation of an evaluation by performance

El presente artículo se centra en uno de los procesos que se hacen presentes en la formación contemporánea, la evaluación por desempeños y específcamente el uso de un instrumento que ha tenido una incidencia positiva en el seguimiento de procesos de aprendizaje: las rúbricas o rejillas de valoración. La evaluación a través de rúbricas supone que todos los participantes del hecho educativo tengan claridad respecto a cómo se evalúa, qué se evalúa, para qué se evalúa, qué se espera de la evaluación, esto le exige al maestro someterse a una constante refexión de lo que enseña, así mismo, al estudiante le permite tener claridad del camino que va a recorrer en el aprendizaje, a los demás actores del proceso educativo les da la posibilidad de conocer la actividad de aula y hacer seguimiento a los niveles de desempeño que van alcanzando los estudiantes a lo largo del proceso.This article focuses on one of the processes that are present in training today, evaluation by performance and specifcally the use of an instrument that has had a positive on the monitoring of learning processes: the rubrics. The evaluation through rubrics assumes that all participants in the educational process have clarity about how to evaluate, what is assessed, for what is assessed ,what is expected of the assessment thus requires the teacher undergoes a constant refection of what who teaches, also the student is allowed to have clarity of road to go on learning, other involved in education gives them the opportunity to learning, others involved in education gives them the opportunity to learn the classroom activity and make tracing about the level of performance that students are reaching throughout the process