Study of large-signal stability of an inverter-based generator using a Lyapunov function

This document analyses the large-signal stability for an inverter-based generator such as photovoltaic and wind power sources. The objective of this study is to determine the stability region taking into account the electrical and control signal of the generator. The generator uses the concept of the electrostatic machine for the model of the generator. Finally, the applied procedure to find the Lyapunov's function is the Popov method, which not only permits to generate a valid function but also to determine the stability region of the system.Postprint (author's final draft

The ‘peri-urban turn’:A systems thinking approach for a paradigm shift in reconceptualising urban-rural futures in the global South

With the rapid pace of urbanization, urban sprawl has become a prevalent phenomenon, particularly in the global South, leading to the emergence of peri-urban spaces where rural-urban interfaces occur. These peri-urban areas exhibit dynamic and continuous interactions among social, economic, and environmental systems, offering valuable insights for fostering resilient futures. However, this aspect remains largely unexplored in current research due to a lack of innovative methodological approaches that effectively capture the complementarities, potentialities, and contestations inherent in the dynamics of peri-urban areas. We contend that peri-urbanisation needs to be reconceptualized as an alternative socio-spatial framework that extends the predominantly Eurocentric discourse on counterurbanisation, making it more inclusive of the emerging urban-rural transformations in the global South. By doing so, we can better understand and address the complex dynamics and challenges associated with peri-urban areas and develop strategies to foster resilience in these contexts

Microgrid central controller development and hierarchical control implemetation in the intelligent microgrid lab of Aalborg University

Preprin

El costeo ABC como estrategia de gestión empresarial en el sector de servicios. Caso: Salón los Maderos

Actualmente las empresas afrontan dificultades para mantenerse en un mercado que cada día es más competitivo y globalizado, viéndose obligadas a realizar actividades de reingeniería y reestructuración para reinventarse a sí mismas y poder adaptarse a la problemática actual. La difícil situación económica que atraviesan los diversos países a nivel mundial, incluido el Ecuador, obliga a la gerencia a buscar herramientas efectivas de gestión que le permitan sobrellevar la crisis económica y poder generar estrategias útiles de competencia.        En el presente trabajo se planteó un costeo por actividades para empresas de servicios, teniendo como unidad de análisis el restaurante “Salón los Maderos”. Con el estudio de los fundamentos teóricos de la gestión de costos basados en actividades ABC/ABM y su influencia en la toma de decisiones financieras en las empresas de servicios, se determinó el costo de los productos y/o servicios que ofrece; para ello, fue necesario conocer no sólo los insumos y los recursos que requieren los productos y/o servicios, sino también las áreas relacionadas con ellos y las actividades que los involucra.        En el restaurante “Salón los Maderos” de la ciudad de Cuenca existen dificultades en cuanto a la gestión de costos, debido a la resistencia a formalizar los procesos, usando como única herramienta “la experiencia” además de costos y gastos manejados de forma empírica

Comparative expression of cyclooxygenase 2 and Ki67 in amelanotic and conventional oral melanomas

Oral melanomas have some histopathological resemblance with its cutaneous counterpart; however, an aggressive behavior is more common in tumors that occur in the oral cavity. Several markers have been suggested as indicative of tumoral progression and aggressiveness, such as cyclooxygenase 2 (COX-2) and Ki67. In this study, we have compared the expression of COX-2 and Ki67 in a series of amelanotic (n=7) and melanotic oral melanomas (n=22). The cases were selected from 4 pathology laboratories and submitted to the immunohistochemical (IHC) reactions. We analyzed the IHC staining based on a qualitative ? using visual scores; and a computer-assisted method (quantitative) using scanned slides and software for digital analysis. COX-2 was expressed in all oral melanomas; however, its intensity was significantly higher in the amelanotic ones (P<0.001). Similarly, a high Ki67-positivity index was observed in the amelanotic than melanotic ones (P<0.001). Based on these results, we suggest that amelanotic oral melanomas have marked pro-inflammatory and high-proliferative phenotype, justifying their more aggressive behavior compared with the melanotic ones