Mostrando recursos 1 - 20 de 686

  1. Piezoelectric micro-machined ultrasonic transducers for medical imaging

    Smyth, Katherine Marie
    Next generation medical imaging technology hinges on the development of cost effective and array compatible transducers making piezoelectric micro-machined ultrasonic transducers (pMUTs) an attractive alternative to the current bulk piezoelectric technology. This thesis aims to realize pMUT potential starting with the development of an effective single cell model that is further scaled to optimize multi-cell elements in a 1D array. In the first half of this work, a transverse mode, lead zirconate titanate (PZT) pMUT plate cell is fabricated using common micro-fabrication techniques and a PZT sol-gel deposition process. Through derivation using a novel Greens function solution technique, an equivalent...

  2. Spatial heat distribution of inkjet printed heaters in comparison to planar milled circuit board heaters for biosensing applications

    Carolus, Jorne; Vandenryt, Thijs; Vandevenne, Glen; Deferme, Wim; Thoelen, Ronald; Daenen, Michaël
    The heat transfer method can be used in biosensing applications to detect analytes. Until now, the heater module always consisted of a heating element and copper heat-spreader. In order to improve the sensitivity of the sensors, a planar heating- and sensing element is proposed. Milling of circuit boards is an established method for creating planar heaters. An alternative has recently emerged in the form of inkjet printing. In this work, a comparison of the heat distribution is made between milled circuit board heaters on a fibreglass substrate and inkjet printed heaters on a flexible PET substrate.

  3. Definición de bloques de carga en redes de distribución de energía eléctrica basado en un modelo de restablecimiento óptimo del servicio.

    Lopez De Mesa Aguilar, Esteban
    Resumen: Este trabajo presenta un desarrollo conceptual y práctico basado en técnicas de optimización y algoritmos de búsqueda, el cual permite, mediante un modelo de restablecimiento óptimo del servicio en redes de distribución de energía eléctrica, definir la mejor partición en bloques de carga para un sistema de distribución determinado, cuyos circuitos cuenten con elementos de transferencia con otros circuitos adyacentes del mismo sistema. El planteamiento de la metodología, en una primera instancia, propone resolver el problema del restablecimiento del servicio de energía eléctrica mediante la premisa de máxima transferencia de carga en el menor tiempo posible; una vez logrado esto,...

  4. Dinámica y optimización de los sistemas de puesta a tierra

    Jiménez Lozano, Guillermo
    Con la presente Tesis de Doctorado se desarrolló una metodología para el análisis de sistemas de puesta a tierra (SPT) utilizando técnicas de Optimización. El objetivo anterior se trabajó teniendo en cuenta un método de evaluación de SPT, el empleo de métodos de Optimización y su aplicación a la norma de la IEEE–80 (2013) y la realización de un experimento comparativo del método elaborado. Todo este trabajo fue posible con la elaboración de diferentes configuraciones de red caracterizadas por distintas distancias entre conductores, a través de diversas geometrías y también por varias profundidades de excavación. Además, considerando la corriente de falla...

  5. Models for integrated components coupled with their EM environment

    Ioan, Daniel; Schilders, Wil; Ciuprina, Gabriela; van der Meijs, Nick; Schoenmaker, Wim
    Purpose – The main aim of this study is the modelling of the interaction of on‐chip components with their electromagnetic environment. Design/methodology/approach – The integrated circuit is decomposed in passive and active components interconnected by means of terminals and connectors which represent intentional and parasitic couplings of a capacitive and inductive nature. Reduced order models are extracted independently for each component. Findings – The paper shows that one of the main theoretical problems encountered in the modelling of RF components is the difficulty to define a unique terminal voltage, independent of the integration path (this independence being a condition to allow the connection of the...

  6. Sistema de comunicação ótica inter-satélites para aplicações em Defesa - I

    Trindade, João Miguel Madeira
    Atualmente, os sistemas de comunicação via satélite são cada vez mais utilizados pela sociedade, em diversas aplicações, sendo a sua evolução uma grande prioridade para a comunidade científica. A necessidade de larguras de banda cada vez maiores, para satisfazer os utilizadores, torna as comunicações óticas em espaço livre (FSO) inter-satélites preferidas em comparação com as tradicionais comunicações por radiofrequência. A comunicação inter-satélites com ritmos binários elevados e de baixa potência é um fator determinante no desempenho destes sistemas. Como este tipo de comunicações são efetuadas a longas distâncias e em órbitas de elevada altitude, as fontes óticas laser tornam-se essenciais, uma...

  7. Reconfiguración en sistemas de distribución considerando las pérdidas y evaluando el impacto económico de la energía no suministrada

    Acevedo, Alejandro Alfonso; Puentes Durán, Diego Alejandro
    En el contenido de este trabajo se encuentra la descripción y aplicación de una metodología para realizar reconfiguración de alimentadores primarios teniendo en cuenta las pérdidas y la con fiabilidad, además de evaluar el impacto de la energía no suministrada (ENS). Esta metodología propuesta se aplicó entre los circuitos principales que pertenecen a la subestación ventorrillo (1VE, 5VE y MVE) ubicada en la ciudad de Pereira del departamento de Risaralda, Colombia. La reconfiguración aplicada a la subestación ventorrillo es descrita en tres pasos principales, primero la selección de cargas a con figurar (Alto impacto social y económico), segundo una simulación que...

  8. El memristor, aplicaciones circuitales con amplificadores operacionales

    González Montoya, Santiago; Arias Varón, Daniel
    En esencia un elemento de circuito pasivo es un componente de vital importancia en el diseño de circuitos eléctricos y electrónicos, pues es el medio por el cual la energía interactúa en forma de almacenamiento o absorción. Se disponen de tres elementos básicos en la teoría clásica de circuitos los cuales son llamados el capacitor (descubierto en 1745), el resistor (descubierto en 1827) y el inductor (descubierto en 1831), pero en el año de 1971 un profesor de ingeniería eléctrica de la universidad de California, Berkeley predijo la existencia de un cuarto dispositivo fundamental, llamado el memristor comprobando que no...

  9. El castigo en Michel Foucault, el control de los sujetos y las relaciones intersubjetivas como mecanismo para ejercer el poder: En búsqueda de una salida a la tensión desde la libertad de los sujetos

    Bustamante Posada, Francisco Javier
    El objetivo que mueve este trabajo es pensar la resistencia y la crítica en Michel Foucault como elementos fundamentales para la posibilidad de la des-sujeción del individuo de las redes del poder-saber. En este sentido, abrir la posibilidad de pensar un ejercicio de la libertad dentro de la estructura misma del poder en el pensador francés, es el fin fundamental en este trabajo de investigación. Para ello se ha utilizado método analítico, dicho método es importante debido al hecho que el mismo Foucault nos presenta una analítica del poder, es decir, el propio pensador francés afirma que su interés no...

  10. Investigation of low‐frequency behaviour of two surface integral full‐Maxwell formulations Article Options and Tools

    Freschi, Fabio; Repetto, Maurizio; Gruosso, Giambattista; Maffucci, Antonio; Villone, Fabio; Zamboni, Walter
    Purpose – To apply two different integral formulations of full‐Maxwell's equations to the numerical study of interconnects in a low‐frequency range and compare the results. Design/methodology/approach – The first approach consists of a surface formulation of the full‐Maxwell's equations in terms of potentials, giving rise to a surface electric field integral equation. The equation, given in a weak form, is solved by using a finite element technique. The solenoidal and non‐solenoidal components of the electric current density are separated using the null‐pinv decomposition to avoid the low‐frequency breakdown. The second model is an extension of partial element equivalent circuit technique to unstructured meshes...

  11. Acoustic impact of the glottal chink on the production of fricatives: A numerical study

    Elie, Benjamin; Laprie, Yves
    The paper presents a numerical study about the acoustic impact of the glottal chink opening on the production of fricatives. Sustained fricatives are simulated by using classic lumped circuit element methods to compute the propagation of the acoustic wave along the vocal tract. A recent glottis model is connected to the wave solver to simulate a partial abduction of the vocal folds during their self-oscillating cycles. Area functions of fricatives at the three places of articulation of French (palato-alveolar, alveolar, and labiodental) have been extracted from static MRI acquisitions. Simulations highlight the existence of three distinct regimes, named A, B,...

  12. Análisis de circuitos con Matlab

    Lobo Sánchez, Belén
    En la actualidad y desde hace algunos años, muchas carreras y módulos de grado superior se basan en la electrónica. En algunos institutos hay asignaturas que hacen una breve introducción a este mundo como es el caso de Tecnología u optativas como Electrotecnia, pero no llegan a profundizar mucho, sólo dan una breve introducción de conceptos básicos. Muchas veces resulta tedioso el resolver los circuitos y más cuando no se sabe si el resultado está bien o no ya que se plantean muchas ecuaciones con muchas incógnitas y es relativamente fácil equivocarse en un número. Esto hace que el análisis no haya...

  13. Simulación de operación de una central nuclear con el simulador gráfico interactivo: LOCA en rama fría en BOL, MOL y EOL

    Penche Alonso, Marta
    La energía nuclear convencional se basa en reacciones de fisión producidas cuando los átomos de uranio absorben neutrones. Se tratan de reacciones autosostenidas en el combustible del reactor nuclear. Este trabajo se enmarca dentro del campo de la seguridad nuclear, estudiando, mediante simulaciones, el desarrollo del accidente base de diseño LOCA. En la seguridad de una central nuclear hay varios niveles: - Primer nivel: la prevención de accidentes. - Segundo nivel: el control de la operación anormal y la detección de fallos. Protección contra accidentes. - Tercer nivel: La contención múltiple de la radiactividad mediante barreras pasivas. Mitigación de accidentes. Este trabajo se realiza en el...

  14. Hybrid Simulation Approach on MEMS Piezoresistive Microcantilever Sensor for Biosensing Applications ROSMINAZUIN AB. RAHIM1,a, BADARIAH BAIS2,b and BURHANUDDIN


    Abstract. This paper uses a hybrid simulation approach in CoventorWare design environment which combines finite element analysis and circuit simulation modeling to obtain the optimal performance of piezoresistive microcantilever sensor. A 250 µm x 100 µm x 1 µm SiO2 cantilever integrated with 0.2 µm thick Si piezoresistor were used in this study. A finite element analysis on piezoresistive microcantilever sensor was conducted in CoventorWare Analyzer environment which incorporates MemMech and MemPZR modules. The sensor sensitivity was obtained by measuring resistivity changes in piezoresistive material in response to surface stress changes of microcantilever. The simulation results were later integrated with...

  15. Towards the Complete Relational Graph of Fundamental Circuit Elements*


    Abstract: A complete and harmonized fundamental circuit relational graph with four linear and four memory elements is constructed based on newly defined elements, which provides a guide to developing novel circuit functionalities in the future. In addition to resistor, capacitor and inductor which are defined in terms of a linear relationship between the charge q, the current i, the voltage v, and the magnetic flux , Chua proposed in 1971 the fourth linear circuit element to directly relate and q. A non-linear resistive device defined in memory i-v relation and dubbed memristor, was later attributed to such an element and...

  16. SEE PROFILE

    Johannes A Russer; Technische Universität München; Sidina Wane; D. Bajon; Peter Russer; Technische Universität München
    Abstract—In this paper we propose the usage of bond wires as antennas for chip-to-chip communications. A wireless bond-wire communication link is designed and investigated experimentally. A lumped element two-port equivalent circuit model is estab-lished using a system-identification-based combined Bartlett-Brune approach. I.

  17. 1 Purely Mechanical Memristors and the Missing Memristor

    Sascha Vongehra
    This work is suppressed since 2010 and led to established scientists to be banned on the arXiv. We thank VIXRA for making critical work like this still available to relatively uncorrupted parts of the scientific community. We define a mechanical analog to the electrical basic circuit element M = dφ/dQ, the ideal mechanical memristance M = dp/dx, p being momentum. A never before described mechanical memory resistor M(x) is independent of velocity v and has a pinched hysteretic loop that collapses at high frequency in the v versus p plot: a perfect memristor. However, its memristance does not crucially involve...

  18. Chairperson Date Approved

    Lakshmi Anusha Kosuru
    Ultra High Frequency Radio Frequency Identification (UHF RFID) technology has gained prominence in recent years. It is being deployed extensively in supply chain and asset tracking by retailers to better control their inventory. The main drawback of UHF RFID tag antenna is that it is sensitive to the environment in which it operates. The performance of the tag degrades when placed on conductive or dielectric objects. While RFID tags near metal have been extensively evaluated in the literature, tags on and in dielectric media have received less scrutiny and rigorous evaluation. In this thesis, we develop a rigorous theoretical model...

  19. Tailoring piezoresistive sensitivity of multilayer carbon nanotube composite strain sensors

    K. J. Loh; J. P. Lynch; B. S. Shim; N. A. Kotov
    ABSTRACT: In recent years, carbon nanotubes have been utilized for a variety of applications, including nanoelectronics and various types of sensors. In particular, researchers have sought to take advantage of the superior electrical properties of carbon nanotubes for fabricating novel strain sensors. This article presents a single-walled carbon nanotube (SWNT)-polyelectrolyte (PE) composite thin film strain sensor fabricated with a layer-by-layer (LbL) process. Optimization of bulk SWNT-PE strain sensor properties is achieved by varying various LbL fabrication parameters, followed by characterization of strain-sensing electromechanical responses. A resistor and capacitor (RC)-circuit model is proposed and validated with electrical impedance spectroscopy to fit...

  20. G.K.: Sinoatrial reciprocation in the isolated rabbit heart. Circ Res

    Jaok Han; Ph. D; Anna Mae Malozzi; Gordon K. Moe; Ph. D
    Reciprocal beats between sinus node and atrium were studied in isolated rabbit heart tissue by microelectrode techniques. Early premature atrial responses which entered the sinus node frequently emerged to re-excite the atrium as "echoes. " When the premature atrial beats discharged some but not all nodal areas, the atrial echoes, in turn, appeared to re-enter the sinus node. Repetitive reciprocation involving the sino-atrial circuit was occasionally observed. Anatomic and temporal patterns of excitation at multiple recording sites suggest that "entrance " block and slow conduction of premature impulses within the sinus node may explain the observed reciprocation. The results support...

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