Numerical simulations on a centrifugal pump operating in turbine mode

123 p.The project presents the study of a centrifugal pump operating in turbine mode as an alternative in micro power generation for isolated regions of Antioquia that are not connected to the national energy network. The use of engineering knowledge as well as powerful computational resources permit development of solutions for environmental problems like the present case where a great amount of people might benefit from natural resources. In the project, computational models were obtained by reverse engineering techniques in order to perform CFD simulations at several conditions for a centrifugal pump when operated in reverse behavior (Flow rate and total head at angular velocity of 1750[rpm]).Contenido parcial: Centrifugal pump -- Centrifugal pump parts -- Digitizing of cad models -- Meshing process -- Simulation process

Diseño de un anemómetro basado en el efecto piezoresistivo

Proyecto de Graduación (Licenciatura en Ingeniería Electrónica) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería Electrónica, 2008.En este proyecto se diseñó un sistema sencillo y de bajo costo capaz de medir la velocidad del viento utilizando el efecto piezoeléctrico o piezoresistivo. Los dispositivos meteorológicos que miden la velocidad del viento se llaman anemómetros y existen de diversos tipos tales como: anemómetros de cazoletas o de molinete (anemómetros mecánicos), ultrasónicos, de filamento caliente y de presión diferencial (anemómetros modernos). Dichos dispositivos son muy importantes ya que permiten la predicción del clima en ciertas zonas. Los anemómetros modernos presentan el gran inconveniente de que son muy costosos en comparación con los anemómetros mecánicos, por eso éstos últimos son los más utilizados, pero aún así dichos instrumentos presentan varios problemas: las piezas móviles se desgastan por el uso, lo afecta la sal, el polvo, la arena y la corrosión por lo que requieren un mantenimiento periódico. También son afectados por varios efectos de inercia lo cual varía las mediciones. Los sensores piezoeléctricos están basados en el efecto piezoeléctrico el cual es la generación de voltaje cuando se aplica un esfuerzo mecánico a dicho sensor y de manera similar, los sensores piezoresistivos están basados en el efecto piezoresistivo, es decir, al aplicar un esfuerzo mecánico al sensor éste cambia su valor de resistencia. Utilizando un sensor piezoresistivo se diseñó un sistema con piezas de bajo costo, fácil adquisición y con muy pocas partes mecánicas para obtener una salida de voltaje proporcional a la fuerza del viento y realizando un proceso de calibración del sistema mecánico mediante un anemómetro fue posible establecer una relación de voltaje y velocidad del viento

Solution of the Navier - Stokes equation using the method of characteristic curves

This project deals about the solution of the Navier Stokes Equations by the Method of Characteristics -- This method is used to eliminate the convective part of equations of the convection-diffusion type, conducting the material derivative in a Lagrangian manner along the characteristic curves of each node in a fixed grid -- Following this approach, the method is able to solve the incompressible Navier Stokes Equations with the advantage of using large timesteps -- In the present case, the solution of the well known Lid Driven Cavity Flow problem is obtained for several Reynolds numbers, showing good agreement when compared to solutions obtained by other method

The Transcription Factor NRF2 Has Epigenetic Regulatory Functions Modulating HDACs, DNMTs, and miRNA Biogenesis

The epigenetic regulation of gene expression is a complex and tightly regulated process that defines cellular identity and is associated with health and disease processes. Oxidative stress is capable of inducing epigenetic modifications. The transcription factor NRF2 (nuclear factor erythroid-derived 2-like 2) is a master regulator of cellular homeostasis, regulating genes bearing antioxidant response elements (AREs) in their promoters. Here, we report the identification of ARE sequences in the promoter regions of genes encoding several epigenetic regulatory factors, such as histone deacetylases (HDACs), DNA methyltransferases (DNMTs), and proteins involved in microRNA biogenesis. In this research, we study this possibility by integrating bioinformatic, genetic, pharmacological, and molecular approaches. We found ARE sequences in the promoter regions of genes encoding several HDACs, DNMTs, and proteins involved in miRNA biogenesis. We confirmed that NRF2 regulates the production of these genes by studying NRF2-deficient cells and cells treated with dimethyl fumarate (DMF), an inducer of the NRF2 signaling pathway. In addition, we found that NRF2 could be involved in the target RNA-dependent microRNA degradation (TDMD) of miR-155-5p through its interaction with Nfe2l2 mRNA. Our data indicate that NRF2 has an epigenetic regulatory function, complementing its traditional function and expanding the regulatory dimensions that should be considered when developing NRF2-centered therapeutic strategiesThis work was supported MINECO (SAF2016-76520-R to I.L-B., PID2019-105600RB-I00 to I.L-B) and ISCiii CIBERNED (CB06/05/0089 to I.L.-B.

Characterization of the substrate noise spectrum for mixed-signal ICs

© 2005 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents a simplified analytical model of the substrate noise generated by digital circuitry that captures the most relevant frequency domain characteristics and relates them with parameters of the digital circuit and the package. Simulations and experimental results are used to validate the analytical model.Peer ReviewedPostprint (published version

VCO phase noise and sideband spurs due to substrate noise generated by on-chip digital circuits

© 2006 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents the effects of noise generated by realistic digital circuits on RF voltage controlled oscillators (VCO) integrated in the same silicon die. The digital noise is coupled through the common substrate and generates both phase noise and sideband spurs at the VCO output. The noise coupling and impact mechanisms, and their dependence on the VCO operating conditions (control voltage, gain and bias current) are investigated.Peer ReviewedPostprint (published version

Procedimiento de obtención de partículas de ZnO con morfología acicular

Referencia OEPM: P200001597.-- Fecha de solicitud: 27/06/2000.-- Titular: Consejo Superior de Investigaciones Científicas (CSIC).Procedimiento de obtención de partículas de ZnO con morfología acicular. La presente invención utiliza el método de precipitación controlada para obtener partículas de ZnO con morfología acicular. A través del control de los parámetros de formación de precursores intermedios de compuestos de cinc y la evolución de dichos precursores intermedios mediante el lavado con agua destilada de la suspensión coloidal se obtiene hidróxido de cinc. La destilación entre 100-150°C de una suspensión acuosa del hidróxido de zinc produce la formación de partículas de óxido de cinc con morfología acicular. El tamaño de las partículas varía con las condiciones de obtención, siendo el tamaño estándar de 0.5 μm de diámetro y 5-8 μm de longitud. La eficacia del procedimiento es superior al 90%.Peer reviewe

Design considerations for a low-noise CMOS image sensor

This paper reports a Low-Noise CMOS Image Sensor. Low-noise operation is achieved owing to the combination of a noise-enhanced pixel, the use of a two-step ADC architecture and the analysis, and the optimization thereof, of the noise contributed by the readout channel. The paper basically gathers the sensor architecture, the ADC converter architecture, the outcome of the noise analysis and some basic characterization data. The general low-noise design framework is discussed in the companion presentation.Junta de Andalucía TIC 2012-2338Office of Naval Research (USA) N00014141035

A 2.5MHz bandpass active complex filter With 2.4MHz bandwidth for wireless communications

This paper presents a fully differential 8thorder transconductor-based active complex filter with 2.4MHz bandwidth and centered at 2.5MHz, designed in a 90nm 2.5V 7M and MIM capacitors CMOS process technology. The filter compliants with the requirements of the IEEE802.15.4 standard. Simulation results including mismatching and process variations over the extracted view of the circuit are shown. The filter has a nominal gain of 12dB, good selectivity (20dB@2MHz offset), high image rejection (51dB nominal) and low power consumption (3.6mA @2.5V).Junta de Andalucía TIC-927Gobierno de España TEC2007-6807