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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

3D Electromagnetic Simulation Tool Exposure for Undergraduate Electrical Engineers: Incorporation Into an Analog Filters Course

Pheng, Bobby B 01 June 2012 (has links) (PDF)
With the growth of wireless communications, comes the need for engineers knowledgeable in 3D electromagnetic (EM) simulation of high-frequency circuits. To give electrical engineering students a better understanding of the behavior of electromagnetic fields, experiments including the use of 3D EM simulation software were proposed. Most students get lost in differential equations, curls, and divergences; this thesis aims to remedy that by exposing them to 3D EM simulation, which may motivate them toward further study in electromagnetics. Also, experience using EMPro is very beneficial for future RF/microwave/antenna engineers, as use of 3D EM simulation is becoming a requirement for this field. 3D EM simulators solve problems where using classical analysis techniques is impractical. Classical EM solutions to simple objects such as boxes, cylinders, and spheres, are widely known; but when the object is more complex, numerical approaches are preferred for their speed. Currently, Cal Poly does not use 3D electromagnetic simulation in any of its courses. Targeted relevant courses include EE 335/375: EM Fields & Transmission Lines, EE 402: EM Waves, EE 405/445: High-Frequency Amplifier Design, EE 425/455: Analog Filter Design, EE 502: Microwave Engineering, and EE 533: Antennas. As a starting point, EE 425/455 was targeted. In choosing which filters to investigate, simplicity and cost were the most important factors. For simplicity, transverse electromagnetic (TEM) mode filters were chosen; also, using a trough design for these filters would allow for simple construction and access. Also, a circular waveguide filter was chosen as an alternative to the TEM filters, as the modes are either transverse electric or transverse magnetic. To lower costs, printed circuit board was used to construct the filters, along with brass tubing, semi-rigid coaxial cable, and copper plumbing caps. From these guidelines, three electronic bandpass filter experiments were investigated: a 1 GHz half-wave coaxial resonator filter, a 2 GHz copper end cap filter, and a tunable 1 GHz quarter-wave coaxial resonator filter. Electric and magnetic field coupling was used to excite the filters. They were then simulated using finite difference time domain (FDTD) simulations in Agilent EMPro. From the simulations, tradeoffs between insertion loss and bandwidth were observed. After, the filters were built and measured using a network analyzer. The quarter-wave filter was incorporated in Cal Poly’s EE 455 course during spring 2012. Students completed an EMPro tutorial, simulated the filters, and measured them using network analyzers. Student feedback was mixed, and modifications were made for future implementations.
132

Microwave Interferometry Diagnostic Applications for Measurements of Explosives

Kline, Loren A 01 July 2017 (has links) (PDF)
Microwave interferometry (MI) is a Doppler based diagnostic tool used to measure the detonation velocity of explosives, which has applications to explosive safety. The geometry used in existing MI experiments is cylindrical explosives pellets layered in a cylindrical case. It is of interest to Lawrence Livermore National Labs to measure additional geometries that may be overmoded, meaning that the geometries propagate higher-order transverse electromagnetic waves. The goal of my project is to measure and analyze the input reflection from a novel structure and to find a good frequency to use in an experiment using this structure. Two methods of determining a good frequency are applied to the phase of the input reflection. The first method is R2, used to measure the linearity of input reflection phase. The second is a zero-crossing method that measures how periodic the input reflection phase is. Frequencies with R2 values higher than .995 may be usable for an experiment in the novel structure.
133

Visitationszoner i en svensk kontext : Förslaget om visitationszoner och dess förenlighet med regeringformen och Europakonventionen

Bassam Hido, Parwen January 2023 (has links)
No description available.
134

Development, Implementation and Validation of Thermal Magnetic Resonance Technology: A New Instrument to Define the Role of Temperature in Biological Systems and Disease

Han, Haopeng 26 January 2022 (has links)
Die thermische Magnetresonanz (ThermalMR) integriert Radiofrequenz (RF)-induzierte Erwärmung, in vivo Temperaturkartierung mittels MR-Thermometrie, anatomische und funktionelle MR-Bildgebung (MRT) und die Option für die x-Kern-MRT in einem einzigen, vielseitig einsetzbaren RF-Applikator. Der Aufbau erlaubt eine gezielte und überwachte Temperaturmodulation und kann somit als Basis für Studien dienen, welche die Klärung grundlegender Fragen bezüglich der molekularen, biochemischen, sowie physiologischen und therapeutischen Auswirkungen der Temperatur in Organismen ermöglichen. In dieser Arbeit wurde ein kostengünstiges, automatisiertes Open-Source-3D-Mehrzweck-Messsystem mit Submillimeter-Genauigkeit implementiert und validiert, um technische Entwicklungen in der thermischen MR wie Antennendesign, Signalgeneratoren, und simulationsbasierte Methoden zu prüfen. Um den Anforderungen eines modernen ThermalMR-Systems gerecht zu werden, wird ein neuer auf einem Phasenregelkreis basierender RF-Signalgenerator für Hyperthermie entwickelt und über dessen Entwurf, Implementierung, Validierung und Anwendung berichtet. Der Signalgenerator ist in der Lage, 32 unabhängige RF-Signale mit präziser Einstellung der Parameter dieser Signale zu erzeugen. Das in dieser Arbeit entwickelte Mehrkanal-RF-Überwachungsmodul ermöglicht das Detektieren von Abweichungen bezogen auf die gewählten Einstellungen und ermöglicht eine Korrektur der RF-Signale in einem Regelkreis. Darüber hinaus ermöglicht das Überwachungsmodul das Erkennen von Bewegungen und ermöglicht zusätzliche Sicherheit in einem realen Behandlungssetup. In dieser Arbeit wurden Forschung und Entwicklung in Informatik, Physik und Biowissenschaften synergetisch miteinander verbunden. Die in dieser Arbeit entwickelte Infrastruktur bildet eine technologische Basis für zukünftige ThermalMR-Anwendungen. / Thermal magnetic resonance (ThermalMR) integrates radio frequency (RF)-induced heating, in vivo temperature mapping using MR thermometry, anatomic and functional MR imaging (MRI), and the option for x-nuclei MRI in a single, multi-purpose RF applicator. This permits supervised targeted temperature modulation, thus enables pioneering studies to clarify fundamental questions pertaining to the molecular, biochemical, broader physiological and therapeutic effects of temperature in organisms. In this work, a cost-effective, automated open source 3D multipurpose measurement system with submillimeter fidelity was implemented and validated to facilitate technical developments in ThermalMR such as RF antenna design and algorithm verification. The design, implementation, validation, and application of the first phase-locked loop based RF signal generator in hyperthermia that is capable of generating 32 channels of independent RF signals with fine-tuning resolutions of the signals’ parameters meet the demanding requirements of a state-of-the-art RF heating system. The multi-channel RF supervision module developed in this work outperforms state-of-the-art counterparts. The detection of head motion in a hyperthermia setting was demonstrated for the first time with the RF supervision module. This work synergistically connects research and development in computer science, physics, and life science. The infrastructure developed in this work forms a technological basis for future ThermalMR applications.
135

Development of Solution Processed Co-planar Nanogap Capacitors and Diodes for RF Applications Enabled Via Adhesion Lithography

Felemban, Zainab 18 August 2019 (has links)
Fabrication process of capacitors and Schottky diodes with nanogap electrodes is explained in this Thesis. The Schottky diode is made with IGZO in the nanogap, whereas the capacitor is made with ZrO2 in the nanogap which acts as the dielectric. Moreover, the electric characterization of both the diode and capacitor was obtained for different frequencies and different diameters. The end result showed that as the frequency increases the diode performance increases, but the capacitance of the capacitors decreases. Also, the barrier height and concentration were obtained using the Mott-Schottky plot for different frequencies. The 10MHz had the highest carrier concentration (5.9E+18cm-3) and barrier height (1V).
136

Gradient and rf coil issues in magnetic resonance imaging

Martens, Michael Alan January 1991 (has links)
No description available.
137

Effects of Random Responding on the Interpretability of the MMPI-2-RF Substantive Scale Scores

Dragon, Wendy R. 24 July 2012 (has links)
No description available.
138

A Fully-Integrated Four-way Outphasing Architecture in Heterogeneously Integrated CMOS/GaN Process Technologies

LaRue, Matthew 11 September 2018 (has links)
No description available.
139

Design and Testing of a High Gradient Radio Frequency Cavity for the Muon Collider

Wu, Vincent 21 June 2002 (has links)
No description available.
140

Design of controlled RF switch for beam steering antenna array

Abusitta, M.M., Zhou, Dawei, Abd-Alhameed, Raed, Excell, Peter S. January 2008 (has links)
Yes / A printed dipole antenna integrated with a duplex RF switch used for mobile base station antenna beam steering is presented. A coplanar waveguide to coplanar strip transition was adopted to feed the printed dipole. A novel RF switch circuit, used to control the RF signal fed to the dipole antenna and placed directly before the dipole, was proposed. Simulated and measured data for the CWP-to-CPS balun as well as the measured performance of the RF switch are shown. It has demonstrated the switch capability to control the beam in the design of beam steering antenna array for mobile base station applications.

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