Ancillary Services in Hybrid AC/DC Low Voltage Distribution Networks

In the last decade, distribution systems are experiencing a drastic transformation with the advent of new technologies. In fact, distribution networks are no longer passive systems, considering the current integration rates of new agents such as distributed generation, electrical vehicles and energy storage, which are greatly influencing the way these systems are operated. In addition, the intrinsic DC nature of these components, interfaced to the AC system through power electronics converters, is unlocking the possibility for new distribution topologies based on AC/DC networks. This paper analyzes the evolution of AC distribution systems, the advantages of AC/DC hybrid arrangements and the active role that the new distributed agents may play in the upcoming decarbonized paradigm by providing different ancillary services.Ministerio de Economía y Competitividad ENE2017-84813-RUnión Europea (Programa Horizonte 2020) 76409

Concordancia Diagnóstica Clínica, Imagenológelica e Histopatológica en Detección de Cáncer de Mama

A pesar que el cáncer de mama a nivel mundial se encuentra como una de las principales causas de morbilidad y mortalidad en la mujer, en nuestro país solamente una istitución tiene un programa de estudios de tamizaje en patología mamaria(EL ISSS con un promedio de 25,000 estudios al año)El Instituto del Cáncer, realiza estudios de tamizaje así como de diagnóstico, siendo este último tipo el más comú

Sistemática, zoogeografía y evolución del género herichthys (pisces: cichlidae), en el noreste de México

La presente Tesis Doctoral tuvo como objetivo determinar el estatus taxonómico de los miembros del género Herichthys en el noreste de México, así como establecer sus relaciones evolutivas, zoogeográficas y filogenéticas. Se realizaron viajes de colecta a los cuerpos de agua que conforman la distribución histórica de la familia Cichlidae en el norte de la Punta del Morro, y se obtuvo el material biológico, el cual fue fijado y depositado en la Colección Ictiológica de la Facultad de Ciencias Biológicas de la UANL. Se obtuvieron muestras de tejidos de aletas pectoral o pélvica, se extrajo ADN, se amplificó el gen mitocondrial Citocromo Oxidasa I (Cox1) vía reacción en cadena polimerasa (PCR) en el Museo Nacional de Ciencias Naturales de Madrid, España. Se conformó una base de datos genética, y se complementó con datos provenientes del genebank. Se infirió un árbol filogenético de Bayes y se estimó la divergencia genética (Dp=distancias sin corrección) entre los diferentes linajes. Se tomó biometría a 374 ejemplares de Herichthys, se integró una base de datos y se sometió a Análisis de Componentes Principales, Análisis Discriminante y de Similitud en base a Clustering Jerárquico. El análisis de la morfométrica reveló una asociación altamente significantiva entre los grupos analizados y los caracteres predictivos que permiten discriminar entre linajes; además se observa un alto grado de traslape en las medidas de los caractares diagnósticos individuales que los separan y sin el uso de funciones canónicas predictivas, dificultan la categorización taxonómica en base a la morfométrica. Los resultados obtenidos fueron validados por bajos niveles de divergencia interespecífica detectados en el análisis genético, lo cual permitió inferir altos niveles de plasticidad fenotípica en el grupo, y la consecuente presencia de formas geográficas intraespecíficas. En base a lo anterior, se formuló una Teoría de dispersión, aislamiento, hibridación introgresiva, reticulación y especiación simpátrica para el grupo; asociando los resultados con la información disponible sobre los eventos paleohidrológicos, volcánicos y climáticos conocidos para la región. Se clarificó el estatus taxonómico de las especies dentro del género Herichthys, se describe un nuevo género, cuatro nuevas especies, y se desarrolló una propuesta taxonómica con fundamento en los conceptos de especie vigentes conforme al Código Internacional de Nomenclatura Zoológica en su edición de 1999

Development of a single-board computer high-resolution microendoscope (PiHRME) to increase access to cervical cancer screening in underserved areas

Over 85% of cervical cancer deaths occur in developing countries.1 Even though the early detection and treatment of cervical precancerous lesions has been shown to prevent invasive cervical cancer, limited resources make it difficult to implement standard cervical cancer screening methods, such as the Pap Smear, in low-resource areas. Instead, many developing countries rely on the visual inspection of the cervix with acetic acid (VIA) to help identify precancerous and cancerous lesions. While VIA has a high sensitivity (82.14%), it has a poor specificity (50.00%), resulting in the overtreatment of women and misallocation of limited resources.2 Recent studies have shown that combining VIA with high-resolution microendoscope (HRME) imaging increases the specificity of cervical cancer screening.3-4 The HRME is a low-cost imaging system (~$2,100) that allows the user to image epithelial tissue in vivo at sub-cellular resolutions at the point-of-care. The current HRME imaging system is also accompanied with automatic image analysis software to distinguish normal and low-grade lesions from high-grade precancerous and cancerous lesions of the cervix. Please click Additional Files below to see the full abstract

Distributed consensus-based secondary control of multi-terminal DC railway systems

Electrification of the transportation sector is one of the main pillars of the future decarbonized society. In this context, high-speed railway corridors are expected to reduce as much as possible their environmental impact while maintaining the safety and quality of service with minimum investments. In pursuing those objectives, the multi-terminal DC railway system may become the preferred paradigm. In contrast to conventional AC railway electrification schemes, the multi-terminal DC railway system requires the adoption of a control algorithm to establish suitable references for the power converters. This paper elaborates on a new consensus-based secondary control strategy, which can be implemented in a distributed fashion. In this approach, each power converter controller receives information from its nearest neighbors to adjust its operating point. A 600-km railway system, subject to realistic train traffic, is used to compare the performance of the proposed control strategy with that of purely local controllers. Numerical simulations evidence that the proposed distributed control scheme provides a compromise solution in terms of voltage drops and equalization of power converter loading, surpassing the performance of conventional state-of-the art controllers

Integrated simulation of electromechanical and thermal dynamics of voltage source converters

This paper proposes a simplified yet accurate enough thermal model of Voltage Source Converters (VSC), aimed at circumventing the high computational cost of existing models, which prevents their use in electromechanical simulations. The proposed model reduces to a simple first-order system for thermal dynamics plus two quadratic equations separately modeling the IGBT and diode power losses. In addition, a methodology is provided to derive the proposed VSC thermal model parameters from manufacturer data. The proposed model is tested for two types of devices, both in steady and transient states. The results show that the reduced-order thermal model produces accurate results at a low computational cost, making it especially suitable for the co-simulation of thermal and electrical dynamic phenomena

A model-less control algorithm of DC microgrids based on feedback optimization

This work addresses the problem of the optimal real-time control of a DC microgrid without relying on its corresponding network model. The main goal of such a controller is to keep the nodal network voltages within the regulatory limits while offering current sharing capability between the different controllable generators powering the DC microgrid. The proposed model-less methodology is based on feedback optimization, which takes advantage of the available real-time measurements to update the setpoints of the DC generation assets. The optimal control variables are determined in an iterative manner by applying a primal–dual saddle-point method, which guarantees appropriate convergence features. The paper details both centralized and distributed implementations which are compared through simulations. The results evidence a good dynamic performance and an optimal steady-state operation as the proposed control algorithm converges to the solution provided by a conventional model-based Optimal Power Flow.Universidad de Sevilla VI PPIT-USUnión Europea - Horizonte 2020 No 764090Ministerio de Economía ENE2017-84813-RCentro para el Desarrollo Tecnológico Industrial HySGrid+ CER-2019101

The Combined Effect of Cold and Copper Stresses on the Proliferation and Transcriptional Response of Listeria monocytogenes

Listeria monocytogenes is a foodborne pathogen that can cause severe disease in susceptible humans. This microorganism has the ability to adapt to hostile environmental conditions such as the low temperatures used by the food industry for controlling microorganisms. Bacteria are able to adjust their transcriptional response to adapt to stressful conditions in order to maintain cell homeostasis. Understanding the transcriptional response of L. monocytogenes to stressing conditions could be relevant to develop new strategies to control the pathogen. A possible alternative for controlling microorganisms in the food industry could be to use copper as an antimicrobial agent. The present study characterized three L. monocytogenes strains (List2-2, Apa13-2, and Al152-2A) adapted to low temperature and challenged with different copper concentrations. Similar MIC-Cu values were observed among studied strains, but growth kinetic parameters revealed that strain List2-2 was the least affected by the presence of copper at 8°C. This strain was selected for a global transcriptional response study after a 1 h exposition to 0.5 mM of CuSO4 × 5H2O at 8 and 37°C. The results showed that L. monocytogenes apparently decreases its metabolism in response to copper, and this reduction is greater at 8°C than at 37°C. The most affected metabolic pathways were carbohydrates, lipids and nucleotides synthesis. Finally, 15 genes were selected to evaluate the conservation of the transcriptional response in the other two strains. Results indicated that only genes related to copper homeostasis showed a high degree of conservation between the strains studied, suggesting that a low number of genes is implicated in the response to copper stress in L. monocytogenes. These results contribute to the understanding of the molecular mechanisms used by bacteria to overcome a combination of stresses. This study concluded that the application of copper in low concentrations in cold environments may help to control foodborne pathogens as L. monocytogenes in the industry