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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.
11

Dynamic modeling of hysteresis-free negative capacitance in ferroelectric/dielectric stacks under fast pulsed voltage operation

Hoffmann, M., Slesazeck, S., Mikolajick, T. 26 January 2022 (has links)
To overcome the fundamental limit of the transistor subthreshold swing of 60 mV/dec at room temperature, the use of negative capacitance (NC) in ferroelectric materials was proposed [1]. Due to the recent discovery of ferroelectricity in CMOS compatible HfO₂ and ZrO₂ based thin films [2], [3], the promise of ultra-low power steep-slope devices seems within reach. However, concerns have been raised about switching-speed limitations and unavoidable hysteresis in NC devices [4], [5]. Nevertheless, it was shown that NC effects without hysteresis can be observed in fast pulsed voltage measurements on ferroelectric/dielectric capacitors [6], which was recently confirmed using ferroelectric Hf₀.₅ Zr₀.₅ O₂[7], [8]. While in these works only the integrated charge after each pulse was studied, here we investigate for the first time if the transient voltage and charge characteristics are also hysteresis-free.
12

Complete Measurement System for Measuring High Voltage and Electrical Field Using Slab-Coupled Optical Fiber Sensors

Stan, Nikola 01 January 2018 (has links)
A slab-coupled optical fiber sensor (SCOS) falls into a narrow class of all-dielectric optical fiber electric field sensors, which makes it a perfect candidate for measurements of high electric fields in environments where presence of conductors is highly perturbing to the system under test. Its nonlinear response to high fields requires a new nonlinear calibration technique. A nonlinear calibration method is explained and demonstrated to successfully measure high electric fields, as well as high voltages with dynamic range up to 50 dB. Furthermore, a SCOS can be fitted into narrow spaces and make highly localized measurements due to its small size. This allows a SCOS to be integrated inside a standard high voltage coaxial cable, such as RG-218. Effects of partial discharge and arcing is minimized by development of a fabrication method to avoid introduction of impurities, especially air-bubbles, into the cable during SCOS insertion. Low perturbation of the measured voltage is shown by simulating the introduced voltage reflections to be on the order of –50 dB. It is also shown that a SCOS can be inserted into other cables without significant perturbation to the voltage. A complete high voltage and high electric field measurement system is built based on the high-voltage modifications of the SCOS technology. The coaxial SCOS is enhanced for robustness. Enhancements include packaging a SCOS into stronger ceramic trough, strengthening the fiber with kevlar reinforced furcation tubing and protecting the sensor with metal braces and protective shells. The interrogator is protected from electromagnetic interference with an RF-shielded box. Reduction in power losses introduced by the new PANDA-SCOS technology allows interrogator bandwidths to be increased up to 1.2 GHz. The whole measurement process is streamlined with dedicated software, developed specifically for high voltage and electric field measurements with support for the nonlinear calibration.
13

Complete Measurement System for Measuring High Voltage and Electrical Field Using Slab-Coupled Optical Fiber Sensors

Stan, Nikola 01 January 2018 (has links)
A slab-coupled optical fiber sensor (SCOS) falls into a narrow class of all-dielectric optical fiber electric field sensors, which makes it a perfect candidate for measurements of high electric fields in environments where presence of conductors is highly perturbing to the system under test. Its nonlinear response to high fields requires a new nonlinear calibration technique. A nonlinear calibration method is explained and demonstrated to successfully measure high electric fields, as well as high voltages with dynamic range up to 50 dB. Furthermore, a SCOS can be fitted into narrow spaces and make highly localized measurements due to its small size. This allows a SCOS to be integrated inside a standard high voltage coaxial cable, such as RG-218. Effects of partial discharge and arcing is minimized by development of a fabrication method to avoid introduction of impurities, especially air-bubbles, into the cable during SCOS insertion. Low perturbation of the measured voltage is shown by simulating the introduced voltage reflections to be on the order of −50 dB. It is also shown that a SCOS can be inserted into other cables without significant perturbation to the voltage.A complete high voltage and high electric field measurement system is built based on the high-voltage modifications of the SCOS technology. The coaxial SCOS is enhanced for robustness. Enhancements include packaging a SCOS into stronger ceramic trough, strengthening the fiber with kevlar reinforced furcation tubing and protecting the sensor with metal braces and protective shells. The interrogator is protected from electromagnetic interference with an RF-shielded box. Reduction in power losses introduced by the new PANDA-SCOS technology allows interrogator bandwidths to be increased up to 1.2 GHz. The whole measurement process is streamlined with dedicated software, developed specifically for high voltage and electric field measurements with support for the nonlinear calibration.
14

Power line sensor networks for enhancing power line reliability and utilization

Yang, Yi 20 May 2011 (has links)
Over the last several decades, electricity consumption and generation have continually grown. Investment in the Transmission and Distribution (T&D) infrastructure has been minimal and it has become increasingly difficult and expensive to permit and build new power lines. At the same time, a growing increase in the penetration of renewable energy resources is causing an unprecedented level of dynamics on the grid. Consequently, the power grid is congested and under stress. To compound the situation, the utilities do not possess detailed information on the status and operating margins on their assets in order to use them optimally. The task of monitoring asset status and optimizing asset utilization for the electric power industry seems particularly challenging, given millions of assets and hundreds of thousands of miles of power lines distributed geographically over millions of square miles. The lack of situational awareness compromises system reliability, and raises the possibility of power outages and even cascading blackouts. To address this problem, a conceptual Power Line Sensor Network (PLSN) is proposed in this research. The main objective of this research is to develop a distributed PLSN to provide continuous on-line monitoring of the geographically dispersed power grid by using hundreds of thousands of low-cost, autonomous, smart, and communication-enabled Power Line Sensor (PLS) modules thus to improve the utilization and reliability of the existing power system. The proposed PLSN specifically targets the use of passive sensing techniques, focusing on monitoring the real-time dynamic capacity of a specific span of a power line under present weather conditions by using computational intelligence technologies. An ancillary function is to detect the presence of incipient failures along overhead power lines via monitoring and characterizing the electromagnetic fields around overhead conductors. This research integrates detailed modeling of the power lines and the physical manifestations of the parameters being sensed, with pattern recognition technologies. Key issues of this research also include design of a prototype PLS module with integrated sensing, power and communication functions, and validation of the Wireless Sensor Network (WSN) technology integrated to this proposed PLSN.
15

Realizace elektronického laboratorního modelu pro praktickou výuku metod zpracování signálu a identifikace dynamických systémů / Realization of electronic laboratory model for practical education of signal processing and identification methods

Gamba, Jaromír January 2021 (has links)
This thesis deals with design of electronic laboratory model for teaching mechatronic subjects. The main part of the model consists of a RLC-circuit embedded in PCB. Other parts of PCB and data acquisition card mediate communication with Matlab environment. In the thesis the progress of design process, simulation, manufacture and model testing is described. The results are functioning educational model and several educational tasks, for which the solution are presented.
16

Inteligentní převodník 0-10V s rozhraním Ethernet / Analog 0-10V to Ethernet convertor

Hlúpik, Martin January 2010 (has links)
This Master`s thesis concern with problematic of connection analog sensors with voltage output 0-10V to a ethernet communication network. Due to a quick evolution and an application ethernet nets to industry and building technologies is possible to use this solution for connection remote diagnostics and setting of existing analog sensors without bus communication interfaces on instrumentation level of field bus networks. The converter is based on Rabbit module, which can be used like webserver for setting, calibration and data recording. For purpose of wide converter use the data output will be purvey on ethernet interface by Modbus TCP and on asynchronous serial interface RS232. First part of thesis is aimed on description of existing solutions and introduction with principles of linearization and calibration of A/D converters. Description of communication standard Modbus TCP widely used in industry applications. Second part of thesis describes design a realization of project. Here is described equipment block diagram with detail description of each block and devices used. In the part of implementation is description of device firmware with program function description and control. Last part is engage with module function verification supported with plantz of measurements and tests. The thesis is ended with evaluation results, knowledge and detections found out in development of project.
17

High-Precision, Mixed-Signal Mismatch Measurement of Metal-Oxide-Metal Capacitors and a 13-GHz 5-bit 360-Degree Phase Shifter

Bustamante, Danilo 05 August 2020 (has links)
A high-precision mixed-signal mismatch measurement technique for metal-oxide metal (MoM) capacitors as well as the design of a 13-GHz 5-bit 360-degree phase shifter are presented. This thesis presents a high-precision, mixed-signal mismatch measurement technique for metal-oxide–metal capacitors. The proposed technique incorporates a switched-capacitor op amp within the measurement circuit to significantly improve the measurement precision while relaxing the resolution requirement on the backend analog-to-digital converter (ADC). The proposed technique is also robust against multiple types of errors. A detailed analysis is presented to quantify the sensitivity improvement of the proposed technique over the conventional one. In addition, this thesis proposes a multiplexing technique to measure a large number of capacitors in a single chip and a new layout to improve matching. A prototype fabricated in 180 nm CMOS technology demonstrates the ability to sense capacitor mismatch standard deviation as low as 0.045% with excellent repeatability, all without the need of a high-resolution ADC. The 13-GHz 5-bit 360-degree phase shifter consists of 2 stages. The first stage utilizes a delay line for 4-bit 180-degree phase shift. A second stage provides 1-bit 180-degree phase shift. The phase shifter includes gain tuning so as to allow a gain variation of less than 1 dB. The design has been fabricated in 180 nm CMOS technology and measurement results show a complete 360◦ phase shift with an average step size of 10.7◦ at 13-GHz. After calibration the phase shifter presented an output gain S21 of 0.5 dB with a gain variation of less than 1 dB across all codes at 13-GHz. The remaining s-parameter testing showed a S22 and S11 below -11 dB and a S12 below -49 dB at 13 GHz.
18

Стохастичка метода мерења напона и струје на високом напону / Stohastička metoda merenja napona i struje na visokom naponu / Stochastic Method for Measurement of Voltage and Current at High Voltage Level

Čomić Dušan 24 November 2015 (has links)
<p>У раду je обрађен проблем мерења високог напона и струје у несинусидалној високонапонској мрежи, стање технике, предлог решења које подразумева неконвенционални начин мерења ових величина, практично израђен прототип и извршена потребна мерења која су потврђена теоријски. Мерење напона у високонапонској мрежи се врши напонским мерним трансформатором без језгра и интегрисаним мерилом хармоника (IMH), а затим се стохастичком методом мере хармоници напона, смерови и протоци снаге, односно енергије. За мерења струје на високом напону предлаже се калем Роговског и стохастичка метода мерења. Стохастичка метода мерења је заснована на додавању дитерског случајног сигнала на мерени сигнал. Сметње и присуство виших хармоника у мрежном сигналу су, за ову методу, додатни дитерски сигнали који методи не смањују тачност мерења.</p> / <p>U radu je obrađen problem merenja visokog napona i struje u nesinusidalnoj visokonaponskoj mreži, stanje tehnike, predlog rešenja koje podrazumeva nekonvencionalni način merenja ovih veličina, praktično izrađen prototip i izvršena potrebna merenja koja su potvrđena teorijski. Merenje napona u visokonaponskoj mreži se vrši naponskim mernim transformatorom bez jezgra i integrisanim merilom harmonika (IMH), a zatim se stohastičkom metodom mere harmonici napona, smerovi i protoci snage, odnosno energije. Za merenja struje na visokom naponu predlaže se kalem Rogovskog i stohastička metoda merenja. Stohastička metoda merenja je zasnovana na dodavanju diterskog slučajnog signala na mereni signal. Smetnje i prisustvo viših harmonika u mrežnom signalu su, za ovu metodu, dodatni diterski signali koji metodi ne smanjuju tačnost merenja.</p> / <p>A problem of measurement of high voltage and current in non-sinusoidal grid is given in the thesis, along with the current state in the field, the proposed non-conventional measurement method for these values, the realized prototype and the necessary measurement results that are confirmed theoretically. Measurement of voltage in high-voltage grid is performed using the coreless high voltage transformer and the Integrated harmonic measurement device (IMH). The stochastic method is used to measure harmonics of voltage, direction and flow of power and energy. For current measurement at high voltage level a Rogowski coil along with the Stochastic measurement method is proposed. Stochastic measurement method is based on adding a arbitrary dither signal to the measured signal. Disturbances and pollution of the grid signal are, for this method, additional dither signals that do not lower the measurement accuracy.</p>

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