Global Tracking Passivity--based PI Control of Bilinear Systems and its Application to the Boost and Modular Multilevel Converters

This paper deals with the problem of trajectory tracking of a class of bilinear systems with time--varying measurable disturbance. A set of matrices {A,B_i} has been identified, via a linear matrix inequality, for which it is possible to ensure global tracking of (admissible, differentiable) trajectories with a simple linear time--varying PI controller. Instrumental to establish the result is the construction of an output signal with respect to which the incremental model is passive. The result is applied to the boost and the modular multilevel converter for which experimental results are given.Comment: 9 pages, 10 figure

Ecosystem functioning of selected estuaries on the east coast of South Africa.

M.Sc. University of KwaZulu-Natal, Durban 2013.River inflow is one of the most important factors influencing the density and biomass of estuarine biotic communities. The aim of this study was to obtain an understanding of the ecosystem functioning of selected estuaries on the east coast of South Africa and to represent their dynamics through ecosystem models. The responses of water column nutrients, plankton density and biomass to inlet phase changes for 16 temporarily open/closed estuaries (TOCEs) in South Africa were first determined. This analysis demonstrated that inlet phase and the duration of mouth closure were the most important factors determining plankton density and biomass of the analysed TOCEs. Estimates of planktonic standing stocks for four of these estuaries revealed that stocks can be from 26 to 10 000 times higher during the closed compared to the open phase. Also, slightly higher variability of planktonic density and biomass was recorded during the closed phase of TOCEs. The second major thrust of this study was to analyse the variability and temporal stability of planktonic and macrobenthic invertebrate density and biomass in two KwaZulu-Natal estuaries over a dry/wet cycle. The results suggest that “stable” variability and species synchronization could be the mechanisms whereby the estuarine biota of these systems compensate for environmental changes and attain a degree of environmental homeostasis. The third major thrust involved an assessment of the spatio-temporal variations in the elemental composition and stoichiometry of suspended and sediment detritus, zooplankton and macrobenthic taxa from two estuaries over a dry/wet cycle. Significant seasonal variations in the elemental composition of detritus, zooplankton and macrobenthic species were found, with the variations in the elemental content of sediment and suspended detritus being related to the seasonal changes in river inflow, while the among-taxa variability was mainly explained by feeding mode. Finally, static seasonal carbon and nitrogen ecosystem network models were developed for the East Kleinemonde, Mlalazi and Mpenjati estuaries to investigate their nutrient dynamics and ecosystem functioning. The results indicated that the East Kleinemonde and Mpenjati estuaries were mainly dependent on primary producers during the dry season, especially the high standing stocks of phytoplankton and microphytobenthos. Similarly, the dependency on detritus was higher during the wet season due to the high riverine imports during this season. Consequently, higher detritivory was recorded in all three study systems during the wet season. Cycling of nitrogen was higher than of carbon on a seasonal basis, with higher recycling of nitrogen during the dry season implying a lower availability of this element due to reduced freshwater inflow and nutrient input during the low rainfall period. System indices indicated that the organization of these systems was higher during the dry season, while the overheads on imports and exports peaked during the wet season. The ecosystem models analysed here provide an initial insight into the overall carbon and nitrogen dynamics of estuaries on the east coast of South Africa

Nonlinear Stability Analysis of the Classical Nested PI Control of Voltage Sourced Inverters

This note provides the first nonlinear analysis of the industry standard "partial decoupling plus nested PI loops" control of voltage sourced inverters. In spite of its enormous popularity, to date only linearization-based tools are available to carry out the analysis, which are unable to deal with large-signal stability and fail to provide estimates of the domain of attraction of the desired equilibrium. Instrumental to establish our result is the representation of the closed-loop dynamics in a suitable Lure-like representation, that is, a forward system in closed-loop with a static nonlinearity. The stability analysis is then done by generating an adequate Popov multiplier. Comparison with respect to linearization is discussed together with numerical results demonstrating non-conservativeness of the proposed conditions

Estrategia lúdica para niños de 5 a 7 años en el uso y cuidado de mascotas

Desde la línea de “Investigación sobre la pedagogía de la lúdica” de la Fundación Universitaria Los Libertadores, se contempla la oportunidad de trabajar, explorar e implementar estrategias lúdicas para el uso y el cuidado de una mascota en el hogar. Teniendo en cuenta lo anterior, el siguiente proyecto tiene como fin optar por el juego como una herramienta que permite a niños y niñas entre los 5 y 7 años de edad, comprender y adoptar como propias las obligaciones que traen consigo la tenencia y manutención de un animal doméstico. Las mascotas o animales domésticos requieren de cuidados especiales tales como limpieza, adiestramiento, alimentación, entre otros. Mediante las dinámicas pedagógicas se busca ampliar la participación de los niños en la ejecución de los distintos oficios para suplir dichas necesidades. El objetivo fundamental de estas dinámicas es concientizar a los niños sobre las diferentes necesidades físicas y mentales que poseen sus mascotas; construyendo habilidades sociales aptas para la convivencia responsable. Se busca con estas actividades que los niños interactúen hasta por 30 minutos diariamente con su mascota y se establezcan nexos o conexiones muy fuertes entre los dos, facilitando el proceso de aprendizaje pedagógico y el descubrimiento guiado. Estas actividades a su vez, permiten establecer valores interpersonales tales como autocuidado, responsabilidad y respeto por la naturaleza en todo aspecto.From the line of “Research on the pedagogy of play” at the Los Libertadores University, the opportunity to work, explore and implement playful strategies for the knowledge and responsibility of caring for a pet at home is contemplated. Taking into account the above, the following project aims to opt for play as a tool that allows children between 5 and 7 years of age, to understand and adopt as their own the obligations that the possession and maintenance of a domestic animal entail. Pets or domestic animals require special care such as cleaning, training, feeding, among others. Through pedagogical dynamics, it seeks to expand the participation of children in the execution of different trades to meet these needs. The fundamental objective of these dynamics is to make children aware of the different physical and mental needs that their pets have, building social skills suitable for responsible coexistence. These activities are intended for children to interact with their pet for up to 30 minutes daily and establish very strong links or connections between the two, facilitating the pedagogical learning process and guided discovery. These activities in turn allow us to establish interpersonal values such as self-care, responsibility and respect for nature In all aspects

EL AMPLIFICADOR MILLER CMOS Y SUS CONSIDERACIONES DE DISEÑO (THE CMOS MILLER AMPLIFIER AND ITS DESIGN CONSIDERATIONS)

Resumen Todo diseño electrónico debe considerar la polarización de la red. El análisis del circuito equivalente, por otro lado, sólo ilustra las prestaciones que la red bajo diseño proporcionará, y ésas están basadas en premisas que no son verificadas, lo que conduce a redimensionar la red a prueba-y-error hasta lograr la respuesta deseada, lo que no es un método de diseño. Si bien el amplificador Miller sólo es una opción de amplificación, es muy usado para introducir el diseño de amplificadores. Por tal razón, el objetivo es resaltar las consideraciones de diseño que deben atenderse y cuáles no porque su efecto en el desempeño del amplificador es irrelevante. En esta contribución el método de diseño se soporta en Leyes Físicas y de su aplicación se señalan las consideraciones relevantes de diseño del amplificador. Se sintetiza las conclusiones del análisis usando facilidades de una tecnología CMOS estándar 0.5m, 2.5V. Palabras Clave: Análisis en CD, amplificador Miller, circuitos CMOS, compensación Miller, enseñanza, Spice. Abstract All electronic design must consider the polarization of the network. The equivalent circuit analysis, on the other hand, only illustrates the benefits that the network under design will provide, and those are based on premises that are not verified, which leads to resizing the network through trial-and-error until the desired response is achieved, which is not a design method. Although the Miller amplifier is only an amplification option, it is widely used to introduce amplifier design. For this reason, the objective of this contribution is to highlight the design considerations that must be addressed, and which are not important because their effect on the performance of the amplifier is irrelevant. In this work the design method is supported in Physical Laws and with them the relevant amplifier design considerations are pointed out. The conclusions of the analysis are synthesized using facilities of a standard 0.5m, 2.5V CMOS technology. Keywords: CMOS circuits, DC analysis, Miller amplifier, Miller Compensation, Spice, Teaching

Implementación de Circuitos Self-Timed de 2 y 4 Fases en FPGAs

Versión electrónica de la ponencia presentada en Jornadas de Computación Reconfigurable y Aplicaciones, celebrado en Madrid en 2003Aunque los dispositivos programables tipo FPGAs están diseñados para la implementación eficiente de circuitos síncronos, en la actualidad constituyen la única opción disponible para prototipado rápido de circuitos self-timed. En este artículo se presentan algunas ideas para el diseño de estos circuitos en FPGAs, para dos principales protocolo: 2 y 4 fases. Como caso de estudio, se ha elegido la multiplicación binaria. Se ilustra el funcionamiento de estos circuitos y se realiza una comparación entre las dos opciones de sincronización. También se resumen los principales resultados en área, velocidad, retardo de pistas y fanout. Como marco tecnológico se utiliza una FPGA Xilinx Virtex II

Análisis de los mecanismos de poder en el contexto de la biopolítica en México a través del discurso

La emergencia por Covid-19 que comenzó en México a partir de marzo de 2020, permitió visualizar las acciones que el sistema de gobierno llevó a cabo para contrarrestar los efectos que se suscitaron por la pandemia. The Covid-19 emergency that began in Mexico as of March 2020, made it possible to visualize the actions that the government system carried out to counteract the effects that were caused by the pandemic. A emergência da Covid-19, iniciada no México a partir de março de 2020, permitiu visualizar as ações que o sistema governamental realizou para neutralizar os efeitos causados pela pandemia.&nbsp

Fisheries and Biodiversity in the Upper Gulf of California, Mexico

The Upper Gulf of California (UGC) has been recognized by its high primary productivity and abundant fishing (Aragon-Noriega & Calderon-Aguilera, 2000). Sediments and nutrients from the Colorado River, and complex hydrodynamics render this as an Important site for spawning, mating and nursing for numerous species of commercial and ecological importance (Cudney & Turk, 1998; Ramirez-Rojo & Aragón-Noriega 2006). Temperature, salinity and abundance of nutrients in this region vary depending on fresh water runoff from the Colorado River (Alvarez-Borrego et al., 1975; Hernández-Ayón et al., 1993; Lavín & Sánchez, 1999). Commercial fishing of high market value resources such as shrimp takes place in the UGC by artisanal or small scale, and industrial fishing. Artisanal fishing is done on relatively small (30 feet) fiber glass boats or artisanal boats with outboard motors, usually operated by two fishers; their primary fishing gear is drift gillnets, which they use to catch croakers, Spanish mackerel and even shrimp. This type of fishing is carried out by cooperatives and individual fishers from the three ports of the UGC: Puerto Peñasco and El Golfo de Santa Clara, in the State of Sonora, and San Felipe, in Baja California. Because marine resources in the region are migratory, fisheries are seasonal generating bursts of accumulated fishing effort over a few months depending on availability of species (see Cudney & Turk 1998). Increasing demand of economically important species has motivated a steady rise in fishing effort and use of gear and fishing practices jeopardizing critical species such as totoaba, Totoaba macdonaldi, an endemic croaker declared under risk of extinction (Cisneros-Mata et al., 1995), and the rare vaquita, Phocoena sinus. Vaquita are accidentally caught in all kinds of gillnets used in the Upper Gulf (D’Agrosa et al., 1995; Blanco 2002)

Identification of Potential Visceral Pain Biomarkers in Colon Exudates from Mice with Experimental Colitis: An Exploratory In Vitro Study

Chronic visceral pain (CVP) is extremely difficult to diagnose, and available analgesic treatment options are quite limited. Identifying the proteins secreted from the colonic nociceptors, or their neighbor cells within the tube walls, in the context of disorders that course with visceral pain, might be useful to decipher the mechanism involved in the establishment of CVP. Addressing this question in human with gastrointestinal disorders entails multiple difficulties, as there is not a clear classification of disease severity, and colonic secretion is not easy to manage. We propose using of a murine model of colitis to identify new algesic molecules and pathways that could be explored as pain biomarkers or analgesia targets. Descending colons from naïve and colitis mice with visceral hyperalgesia were excised and maintained ex vivo. The proteins secreted in the perfusion fluid before and during acute noxious distension were evaluated using high-resolution mass spectrometry (MS). Haptoglobin (Hp), PZD and LIM domain protein 3 (Pdlim3), NADP-dependent malic enzyme (Me1), and Apolipoprotein A-I (Apoa1) were increased during visceral insult, whilst Triosephosphate isomerase (Tpi1), Glucose-6-phosphate isomerase (Gpi1), Alpha-enolase (Eno1), and Isoform 2 of Tropomyosin alpha-1 chain (Tpm1) were decreased. Most identified proteins have been described in the context of different chronic pain conditions and, according to gene ontology analysis, they are also involved in diverse biological processes of relevance. Thus, animal models that mimic human conditions in combination with unbiased omics approaches will ultimately help to identify new pathophysiological mechanisms underlying pain that might be useful in diagnosing and treating pain. Perspective: Our study utilizes an unbiased proteomic approach to determine, first, the clinical relevance of a murine model of colitis and, second, to identify novel molecules/pathways involved in nociception that would be potential biomarkers or targets for chronic visceral pain