Mostrando recursos 1 - 20 de 613

  1. Evaluation of arithmetic operators for the MPPA-256 manycore architecture

    Rocha, Leandro Mateus Giacomini
    1.1 Introdução Este capítulo apresenta um resumo estendido em português sobre o Trabalho de Final de Estudos, escrito em inglês, realizado na França durante a participação do Programa de Intercâmbio Brafitec com a obtenção do duplo diploma. A motivação do trabalho assim como as etapas de desenvolvimento do mesmo são apresentadas brevemente para que se tenha uma compreensão geral texto. 1.1.1 Contexto do trabalho Este trabalho de conclusão de curso em microeletrônica, decorrente da co-tutela firmada entre as universidades Institut Polytechnique de Grenoble – École Nationale de Physique, Électronique et Matériaux (Phelma) e Universidade Federal do Rio Grande do Sul,...

  2. Back-Propagation Operation for Analog Neural Network Hardware with Synapse Components Having Hysteresis Characteristics

    Michihito Ueda; Yu Nishitani; Yukihiro Kaneko; Atsushi Omote
    To realize an analog artificial neural network hardware, the circuit element for synapse function is important because the number of synapse elements is much larger than that of neuron elements. One of the candidates for this synapse element is a ferroelectric memristor. This device functions as a voltage controllable variable resistor, which can be applied to a synapse weight. However, its conductance shows hysteresis characteristics and dispersion to the input voltage. Therefore, the conductance values vary according to the history of the height and the width of the applied pulse voltage. Due to the difficulty of controlling the accurate conductance,...

  3. Operational Amplifiers


    Op amps have many applications. They are used in a wide variety of mathematical applications as a fundamental element of a mathematical circuit. Some more complicated models of an op amp have different properties such as input offset voltage, dc gain, bias current, input and output resistance. To account for these properties, more complicated models are required. This section will ignore practical and more advanced models and focus on the ideal operational amplifier. This module introduces the operational amplifier in a circuit. We will explore the purpose of an op amp, look at the characteristics and examine examples of it....

  4. IEEE MICROWAVE AND GUIDED WAVE LETTERS, VOL. 9, NO. 11, NOVEMBER 1999 467 A 530-GHz Balanced Mixer

    Goutam Chattopadhyay Student; Goutam Chattopadhyay; Student Member; Frank Rice; David Miller; Henry G. Leduc; Jonas Zmuidzinas
    We report on the design and performance of a 530-GHz balanced SIS mixer, the first balanced mixer in this frequency range. This quasi-optical balanced mixer utilizes a cross-slot antenna on a hyperhemispherical substrate lens with eight superconductor--insulator--superconductor (SIS) junctions and a 180 ffi lumped element IF hybrid circuit. The local oscillator (LO) and the radio frequency (RF) signal, orthogonal in polarization to each other, are coupled to the mixer using a wiregrid polarizer. The noise performance of the mixer is excellent, giving an uncorrected receiver noise temperature of 105 K (DSB) at 528 GHz.

  5. Fast On-chip Inductance Simulation Using a Precorrected-FFT Method

    Haitian Hu; David T. Blaauw; Vladimir Zolotov; Kaushik Gala; Min Zhao, et al.
    In this paper, a precorrected-FFT approach for fast and highly accurate simulation of circuits with on-chip inductance is proposed. This work is motivated by the fact that circuit analysis and optimization methods based on the partial element equivalent circuit (PEEC) model require the solution of a subproblem in which a dense inductance matrix must be multiplied by a given vector, an operation with a high computational cost. Unlike traditional inductance extraction approaches, the precorrected-FFT method does not attempt to compute the inductance matrix explicitly, but assumes the entries in the given vector to be the fictitious currents in inductors and...

  6. A small radiation monitor telemeter with transistor circuit element /

    Strebe, Frank C.; Kennedy, William R., 1922-; University of California, Los Angeles.; U.S. Atomic Energy Commission.
    "October 14, 1954."

  7. The Archipelago Ubiquitin Ligase Subunit Acts in Target Tissue to Restrict Tracheal Terminal Cell Branching and Hypoxic-Induced Gene

    Nathan T. Mortimer; Kenneth H. Moberg
    The Drosophila melanogaster gene archipelago (ago) encodes the F-box/WD-repeat protein substrate specificity factor for an SCF (Skp/Cullin/F-box)-type polyubiquitin ligase that inhibits tumor-like growth by targeting proteins for degradation by the proteasome. The Ago protein is expressed widely in the fly embryo and larva and promotes degradation of pro-proliferative proteins in mitotically active cells. However the requirement for Ago in post-mitotic developmental processes remains largely unexplored. Here we show that Ago is an antagonist of the physiologic response to low oxygen (hypoxia). Reducing Ago activity in larval muscle cells elicits enhanced branching of nearby tracheal terminal cells in normoxia. This tracheogenic...

  8. Digital Phase Recovery Adjustment for High Speed Transfer of ATM and ATM like Data Formats

    Thomas J. Chaney
    A significant, if not over riding, problem with electronic systems that must transmit data rapidly between IC (Integrated Circuit) packages is the issue of determining, at the receiver, when to sample the interconnecting wires to record the transmitted data values. Traditionally, the sampling time is established by a “clock ” signal that is distributed to all IC packages. As data transmission rates have increased, the simple “clock ” signal schemes have began to fail as it has become more difficult to assure that the “clock ” signal is received by all IC packages at same time. The “clock skew” problem...

  9. The stochastic I-pot: A circuit block for programming bias currents

    Rafael Serrano-gotarredona; Luis Camuñas-mesa; Teresa Serrano-gotarredona; Juan A. Leñero-bardallo; Bernabé Linares-barranco
    Abstract—In this brief, we present the “Stochastic I-Pot. ” It is a circuit element that allows for digitally programming a precise bias current ranging over many decades, from pico-amperes up to hundreds of micro-amperes. I-Pot blocks can be chained within a chip to allow for any arbitrary number of programmable bias currents. The approach only requires to provide the chip with three external pins, the use of an external current measuring instrument, and a computer. This way, once all internal I-Pots have been characterized, they can be programmed through a computer to provide any desired current bias value with very...

  10. On the Sequence of State Configurations in the Garden of Eden

    Yukihiro Kamada; Kiyonori Miyasaki
    Autonomous threshold element circuit networks are used to inves-tigate the structure of neural networks. With these circuits, as the transition functions are threshold functions, it is necessary to consider the existence of sequences of state configurations that cannot be tran-sitioned. In this study, we focus on all logical functions of four or fewer variables, and we discuss the periodic sequences and transient series that transition from all sequences of state configurations. Fur-thermore, by using the sequences of state configurations in the Garden of Eden, we show that it is easy to obtain functions that determine the operation of circuit networks....

  11. EPEEC: A Compact Reluctance Based Interconnect Model Considering Lossy Substrate Eddy Currents

    Rong Jiang
    Abstract — Lossy silicon substrate has significant effects on the already complicated interconnect modeling issue. To account for the substrate loss, traditional electromagnetic methods are often computationally prohibitive for large scale VLSI geometries. In this paper, we present EPEEC (Eddy-current-aware Partial Equivalent Element Circuit) which extends the traditional PEEC model to consider substrate eddy current loss based on complex image theory and skin and proximity effects by discretization of conductors. To deal with even larger scale of interconnects, we enhance EPEEC model to use reluctance by equipping it with an advanced windowing algorithm to further reduce the model size and...

  12. EPEEC: Comprehensive SPICE-Compatible Reluctance Extraction for High-Speed Interconnects above Lossy Multilayer Substrate

    Rong Jiang; Student Member; Wenyin Fu; Charlie Chung-ping Chen
    Abstract — With continuous advances in radio frequency (RF) mixed-signal very large scale integration (VLSI) technology, the creation of eddy currents in lossy multilayer substrates has made the already complicated interconnect analysis and modeling issue more challenging. To account for substrate losses, traditional electromagnetic methods are often computationally prohibitive for today’s VLSI geometries. In this paper, an accurate and efficient interconnect modeling approach – EPEEC (Eddy-currentaware Partial Equivalent Element Circuit) – is proposed. Based on complex image theory, it extends the traditional partial equivalent element circuit (PEEC) model to simultaneously take multilayer substrate eddy current losses and frequency dependent effects...

  13. AN EXPERT SYSTEM FOR UNDERSTANDING EXPRESSIONS FROM ELECTRIC CIRCUIT ANALYSIS ABSLRACT

    Rostam Joobbani; Sarosh N. Talukdar
    important that students master the skills it requires. Most of cuaiit analysis is concerned with writing expressions that embody transtoamations, conservation laws and the electrical behaviors of various devices This paper describes work in progress or. an expert system that can examine the expressions that students write, diagnose the errors in them and suggest corrections. The expert system is implemented in OPS5 and uses the strategies of divide and conquer, forward chaining and hypoihesize and-test The system can now recognise most of the Common errors that students make in dealing with linear resistive circuits and operates at about the level...

  14. ONE INCREMENTAL ADAPTATION STRATEGY OF THE DECISION-MAKING FORMAL NEURON

    Archil Prangishvili; Natia Namicheishvili
    The general objective of formal neuron adaptation is to give the reliable inputs more influence in determining the output than the unreliable inputs have. Adaptation is introduced into the threshold decision element by a circuit that performs two operations: estimates the error probability of each input and uses the estimate to change each vote-weight. A cyclic error-counting adaptation procedure is the one in which vote-weights are changed periodically (cyclically), based on data collected during computations in a period (cycle). If appropriate incremental adjustments are made to the estimate of inputs ' each error after each computation, then we deal with...

  15. 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...

  16. 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...

  17. Relación entre descargas eléctricas atmosféricas a tierra y fallas en líneas de transmisión y distribución de energía - operador centrales eléctricas de Norte de Santander Colombia

    Jiménez Rodríguez, Sebastián Darío
    El presente es un trabajo investigativo que determina la diferencia de las tensiones inducidas en líneas de aéreas de distribución de energía que recorren terreno montañoso (no-plano), respecto a los valores obtenidos al asumir una típica aproximación de terreno plano. Esta tesis busca contribuir en el mejoramiento de los sistemas de protección contra rayos para los operadores de red en Colombia, considerando que los rayos por impactos directos o indirectos, son los causantes de cerca del 70% de las fallas que ocurren en los circuitos aéreos de distribución. Se realizan simulaciones de tramos de líneas en Norte de Santander considerando...

  18. Direct functionalization of Mn12-(methacrylate) clusters on Si(100): surface characterization and electrochemical properties

    Ledezma Gairaud, Marisol; Moehl, Thomas; Montero, Mavis L.; Pineda, Leslie W.
    The reaction of H–terminated Si(100) with methacrylate–substituted manganese carboxylate clusters [Mn12O12{CH2C(CH3)COO}16(H2O)4], [Mn12–(methacrylate)] via hydrosilylation afforded Mn12–(methacrylate)−Si(100). The chemically modified surface was studied with an atomic force microscope (AFM), X–ray photoelectron spectra (XPS), a cyclic voltammeter (CV) and electrochemical impedance spectra (EIS). XPS show several Mn and Si electronic signatures that indicate the tailoring of Mn12–(methacrylate) on the surface. The CV plot of Mn12–(methacrylate)−Si(100) has two irreversible cathodic waves at −0.76 and −0.44 V, assigned to Mn(IV)/Mn(III) and Mn(III)/Mn(II) processes. The calculated charge at –0.44 V was 3.14 x 10–5 C cm–2. An equivalent-circuit model was proposed based on EIS data...

  19. Memristor. Una perspectiva general

    Oyarce Marambio, Carlos; Chandía Valenzuela, Kristopher; Rodríguez Estay, Alejandro
    For almost two centuries the whole electronics was based on three fundamental elements: resistor, capacitor, and inductor. In 1971, Leon Chua theorized about a fourth fundamental circuit element termed ‘Memristor’ that was implemented for the first time by Stanley Williams and co-workers at HP Labs, in 2008. The Memristor behaves as a variable resistor capable of remembering its last resistance value after the polarization is removed, like a non-volatile memory. Due to its properties, the memristor has become an important topic under study in several areas such: as non-volatile memories, neural networks and logical circuits. This paper presents an overview of the state of the art of theory, models, circuits,...

  20. White matter integrity of the cerebellar peduncles as a mediator of effects of prenatal alcohol exposure on eyeblink conditioning

    Fan, Jia; Meintjes, Ernesta M.; Molteno, Christopher D.; Spottiswoode, Bruce S.; Dodge, Neil C.; Alhamud, Alkathafi A.; Stanton, Mark E.; Peterson, Bradley S.; Jacobson, Joseph L.; Jacobson, Sandra W.
    Fetal alcohol spectrum disorders (FASD) are characterized by a range of neurodevelopmental deficits that result from prenatal exposure to alcohol. These can include cognitive, behavioural, and neurological impairment, as well as structural and functional brain damage. Eyeblink conditioning (EBC) is among the most sensitive endpoints affected in FASD. The cerebellar peduncles, large bundles of myelinated nerve fibers that connect the cerebellum to the brainstem, constitute the principal white matter element of the EBC circuit. Diffusion tensor imaging (DTI) is used to assess white matter integrity in fibre pathways linking brain regions. DTI scans of 54 children with FASD and 23...

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