Mostrando recursos 1 - 20 de 30

  1. Basic deposited integrated magnetic circuit element for fast computer circuitry

    Reardon, B. C.; Humphrey, F. B.
    A deposited configuration, consisting of a magnetic thin film and coupling loop, was studied with a view to the future development of integrated magnetic circuitry. A line charge model, predicting flux linkages of coupling loops to an accuracy of about one percent was established. The almost complete linkage of the film flux with a deposited loop, due to the very close coupling, was verified. A decrease of about 20 percent in film flux at both ends of the easy axis was noted for the experimental assemblies used. Circulating loop currents were shown to be the chief parasitic factor which modified...

  2. 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...

  3. Optical Frequency Mixing Through Nanoantenna Enhanced Difference Frequency Generation: Metatronic Mixer

    Chettiar, Uday K; Engheta, Nader
    A design for a subwavelength all-optical frequency mixer is proposed. The method relies on enhanced difference-frequency generation, which is achieved in two steps with the help of plasmonic nanoantennas. The interaction of the two input signals with the nonlinear material is increased through the use of input nanoantennas, which focus the incident energy of two different frequencies onto the nanoparticle formed by a nonlinear material. Next, the difference-frequency emission is enhanced through the Purcell effect by the use of a separate output nanoantenna that is resonant at the difference frequency. The application of this twofold approach allows for a significant...

  4. Generation and tuning of learned sensorimotor behavior by multiple neural circuit architectures

    Lynn, Michael (Michael Benjamin)
    Organisms have a remarkable ability to respond to complex sensory inputs with intricate, tuned motor patterns. How does the brain organize and tune these motor responses, and are certain circuit architectures, or connectivity patterns, optimally suited for certain sensorimotor applications? This thesis presents progress towards this particular problem in three subprojects. The first section re-analyzes a large data set of single-unit recordings in zebra finch area HVC during singing. While HVC is known to be essential for proper expression of adult vocalization, its circuit architecture is contentious. Evidence is presented against the recently postulated gesture-trajectory extrema hypothesis for the organization...

  5. A Superconducting-Nanowire 3-Terminal Electronic Device

    McCaughan, Adam N.; Berggren, Karl K.
    Superconducting electronics based on Josephson junctions are used to sense and process electronic signals with minimal loss; however, they are ultrasensitive to magnetic fields, limited in their amplification capabilities, and difficult to manufacture. We have developed a 3-terminal, nanowire-based superconducting electrothermal device which has no Josephson junctions. This device, which we call the nanocryotron, can be patterned from a single thin film of superconducting material with conventional electron-beam lithography. The nanocryotron has a demonstrated gain of >20, can drive impedances of 100 kΩ, and operates in typical ambient magnetic fields. We have additionally applied it both as a digital logic...

  6. Espacio deportivo urbano : parkour park en Vigo

    Lago Costas, Alfredo Alberto
    En la Península Ibérica se está viviendo un fenómeno emergente en el panorama deportivo: el auge del Parkour, deporte urbano que se sirve de la morfología de la ciudad aprovechando elementos del mobiliario, escaleras, desniveles y rampas para realizar circuitos y piruetas. Al tratarse de un deporte relativamente nuevo existe una falta de estudio de la relación del deporte con el entorno urbano. Es por ello que tampoco existen muchas construcciones a día de hoy que conjuguen las necesidades del parkour con la morfología y circuitos urbanos. La ciudad de Vigo tiene un papel destacable dentro de la comunidad gallega, debido...

  7. GATA Factor-G-Protein-Coupled Receptor Circuit Suppresses Hematopoiesis

    Gao, Xin; Wu, Tongyu; Johnson, Kirby D.; Lahvic, Jamie L.; Ranheim, Erik A.; Zon, Leonard I.; Bresnick, Emery H.
    Summary Hematopoietic stem cells (HSCs) originate from hemogenic endothelium within the aorta-gonad-mesonephros (AGM) region of the mammalian embryo. The relationship between genetic circuits controlling stem cell genesis and multi-potency is not understood. A Gata2 cis element (+9.5) enhances Gata2 expression in the AGM and induces the endothelial to HSC transition. We demonstrated that GATA-2 rescued hematopoiesis in +9.5−/− AGMs. As G-protein-coupled receptors (GPCRs) are the most common targets for FDA-approved drugs, we analyzed the GPCR gene ensemble to identify GATA-2-regulated GPCRs. Of the 20 GATA-2-activated GPCR genes, four were GATA-1-activated, and only Gpr65 expression resembled Gata2. Contrasting with the paradigm...

  8. A compact design for the Josephson mixer: The lumped element circuit

    Pillet, J.-D.; Flurin, E.; Mallet, F.; Huard, B.
    International audience

  9. A compact design for the Josephson mixer: The lumped element circuit

    Pillet, J.-D.; Flurin, E.; Mallet, F.; Huard, B.
    International audience

  10. Fabricación y Caracterización de dispositivos basados en Silicio Poroso sobre c-Si. Aplicaciones eléctricas, Ópticas y Térmicas.

    Fonthal Rico, Faruk
    Debido a las propiedades eléctricas y ópticas del Silicio Poroso (PS), este es un material ampliamente utilizado para el desarrollo de los dispositivos electrónicos. Por su compatibilidad con la tecnología de fabricación del Silicio, el Silicio Poroso es estudiado hoy en día en diferentes aplicaciones como: elementos activos en circuitos integrados, estructuras electro luminiscentes, dispositivos fotodetectores, dispositivos térmicos y muchas más.

    El trabajo que se ha desarrollado como tesis doctoral consiste en estudiar, fabricar y caracterizar estructuras basadas en PS en diferentes medios como el luminoso y el térmico, para 1) establecer sus diferentes comportamientos y 2) desarrollo de dispositivos basados...

  11. A Column-Row-Parallel ASIC architecture for 3D wearable / portable medical ultrasonic imaging

    Chen, Kailiang
    This work presents a scalable Column-Row-Parallel ASIC architecture for 3D wearable / portable medical ultrasound. It leverages programmable electronic addressing to achieve linear scaling for both hardware interconnection and software data acquisition. A 16x16 transceiver ASIC is fabricated and flip-chip bonded to a 16x16 capacitive micromachined ultrasonic transducer (CMUT) to demonstrate the compact, low-power front-end assembly. A 3D plane-wave coherent compounding algorithm is designed for fast volume rate (62.5 volume/s), high quality 3D ultrasonic imaging. An interleaved checker board pattern with I&Q excitations is also proposed for ultrasonic harmonic imaging, reducing transmitted second harmonic distortion by over 20dB, applicable to...

  12. Estudio de modelos multifísicos para la simulación holística y concurrente de circuitos impresos

    Luna Rodríguez, J.J.
    La tesis titulada Estudio de Modelos Multifísicos para la Simulación Holística y Concurrente de Circuitos Impresos ha consistido en un análisis teórico y práctico sobre la viabilidad del modelado térmico y electromagnético, compatible con estructuras holísticas, para la simulación multifísica de circuitos impresos, que permita reproducir lo más fielmente posible su comportamiento térmico y electromagnético de forma concurrente. En este trabajo se han cubierto las siguientes etapas: 1. Estudio de diferentes modelos para la conducción, convección y radiación térmica en cuerpos simples de composición material homogénea, aplicables a la transmisión de calor unidireccional, así como su implementación en MATLAB/SIMULINK. 2. Estudio de...

  13. Fast Methods for Full-wave Electromagnetic Simulations of Integrated Circuit Package Modules

    Terizhandur Varadharajan, Narayanan
    Fast methods for the electromagnetic simulation of integrated circuit (IC) package modules through model order reduction are demonstrated. The 3D integration of multiple functional IC chip/package modules on a single platform gives rise to geometrically complex structures with strong electromagnetic phenomena. This motivates our work on a fast full-wave solution for the analysis of such modules, thus contributing to the reduction in design cycle time without loss of accuracy. Traditionally, fast design approaches consider only approximate electromagnetic effects, giving rise to lumped-circuit models, and therefore may fail to accurately capture the signal integrity, power integrity, and electromagnetic interference effects. As part...

  14. Extraction of SOS MOSFET RF equivalent circuit elements by LCR meter measurements

    Bertling, K.; Rakic, A. D.; Yeow, Y. T.; Brawley, A.; Domyo, H.; Rotella, F. M.
    Two methods for the extraction of the small-signal equivalent circuit of high frequency silicon on sapphire (SOS) MOSFETs are compared. One technique employs microwave vector network analyser measurements in the 0.2-24GHz range, while the other uses a low frequency LCR meter at 100kHz to determine the circuit element values. Results presented show excellent agreement between the two methods. It is concluded that the low frequency method can be successfully used to extract high frequency circuit-model elements and reasons for this are offered. © 2010 The Institution of Engineering and Technology.

  15. Magnetostrictive Metal-Matrix Composites

    Scheidler, Justin
    In this research, the prospect of embedding rolled Galfenol samples with wound induction coils was tested by embedding steel samples wound with induction coils. A 10.16 mm (0.4 in) wide steel sample, wound with a 60 turn induction coil was successfully embedded with two Al 3003-H18 foil using ultrasonic consolidation. Despite the embedding success, the induction coil was shorted to the Al matrix, although embedding was achieved with minimal deformation of the coil windings. It was theorized that a thicker insulation layer will provide increased protection during welding and will result in a reduction in the possibility of coil shorting. From...

  16. Circuit-coupled FEM analysis of the electric-field type intra-body communication channel

    Xu, Ruoyu; Zhu, Hongjie; Yuan, Jie
    The electric-field (EF) intra-body communication (IBC) is a promising data transmission method for high-speed low-power biomedical sensors. A good model of the EF-IBC channel is needed for better understanding the signal propagation principle and more efficient IBC transceiver design. Although various effective models have been developed for the waveguide IBC channel, the EF-IBC channel has only been modeled by empirical distributed RC network. In this paper, a circuit-coupled finite-element-method (FEM) model is established to analyze the EF-IBC channel. A multi-layer FEM model is developed for the human forearm. The parasitic effects of the probe PCBs and the return path are...

  17. Finite Element and Electrical Circuit Modelling of Faulty Induction Machines - Study of Internal Effects and Fault Detection Techniques/Modélisation par éléments finis et par équations de circuits des machines asynchrones en défaut - Etude des effets internes et techniques de détection de défauts.

    Sprooten, Jonathan
    This work is dedicated to faulty induction motors. These motors are often used in industrial applications thanks to their usability and their robustness. However, nowadays optimisation of production becomes so critical that the conceptual reliability of the motor is not sufficient anymore. Motor condition monitoring is expanding to serve maintenance planning and uptime maximisation. Moreover, the use of drive control sensors (namely stator current and voltage) can avoid the installation and maintenance of dedicated sensors for condition monitoring. Many authors are working in this field but few approach the diagnosis from a detailed and clear physical understanding of the localised phenomena...

  18. Thin-film bulk acoustic wave resonators - FBAR: fabrication, heterogeneous integration with CMOS technologies and sensor applications

    Campanella Pineda, Humberto
    El gran impacto de la tecnología FBAR tanto en sistemas de radio frecuencia como más recientemente en sensores han motivado el desarrollo de aplicaciones integradas. Esto implica que los procesos de fabricación deberían lograr producir dispositivos resonadores con un alto factor de calidad, al tiempo que permitir la integración de los FBAR con tecnologías CMOS estándar. De tal manera, esta tesis doctoral aborda dichos requerimientos, contribuyendo con el diseño, fabricación y caracterización de resonadores FBAR; su integración con tecnologías CMOS estándar; y su aplicación a sistemas de sensores. El desarrollo de la tecnología de fabricación de los FBAR ha involucrado la...

  19. Experimental verification for the design of a doubly-fed permanent magnetic generator

    Lu, Bin, Ph. D. Massachusetts Institute of Technology
    This is a continuous work on the project of a doubly-fed permanent magnet (DFPM) generator for wind turbines. The construction of a prototype machine was finally finished and experiments were conducted to verify the design of the DFPM machine and to establish a basis for designing more powerful machines in industry usage. In the thesis, a finite element model of the machine is established, from which the parameters of the prototype machine are estimated. Then the experiment data are compared with the estimated values to verify the model of the machine. At last a vector control method is proposed with...

  20. Methods for Synthesis of Multiple-Input Translinear Element Networks

    Subramanian, Shyam
    Translinear circuits are circuits in which the exponential relationship between the output current and input voltage of a circuit element is exploited to realize various algebraic or differential equations. This thesis is concerned with a subclass of translinear circuits, in which the basic translinear element, called a multiple-input translinear element (MITE), has an output current that is exponentially related to a weighted sum of its input voltages. MITE networks can be used for the implementation of the same class of functions as traditional translinear circuits. The implementation of algebraic or (algebraic) differential equations using MITEs can be reduced to the...

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