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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.
221

Využití prostředí Matlab Simulink při výuce Mechaniky letu II / Matlab Simulink for Flight Mechanics II module

Černota, Jiří January 2016 (has links)
The thesis is about the use of Matlab Simulink software for subject Flight Mechanics II. User interface, which allow computing of aerodynamic derivations and state space matrices, was created. It also provides system for launching simulations of longitudinal aircraft movement in Simulink environment and results visualization. In the last part were suggested examples for practice lessons of the aforementioned subject. These lessons focus on mastering basic block programming and to understand concept of aircraft dynamics and controlling aircraft movement.
222

Enhanced frequency regulation functionality of grid-connected PV system

Showers, Obu Samson January 2019 (has links)
Thesis (MEng (Electrical Engineering))--Cape Peninsula University of Technology, 2019 / Electric utilities are confronted with challenges like rising fuel costs, aging equipment, increasing energy demand, frequency regulation and the difficulty to integrate renewable energy resources into the grid. The presence of photovoltaic (PV) penetration on the utility grid is also increasing significantly in recent years. With the recent rise in PV penetration and the advancement of the global PV industry, there is an urgent and a necessary need to introduce features in PV systems that will make them respond smartly. However, much of these can be addressed without negatively affecting the total performance and power quality of the grid. Hence, engaging smart Grid technologies, and leveraging the benefits of the distributed nature of PV, new prospects to unearth value can be created. Through the implementation of progressive energy storage techniques, efficient two-way communications, a grid-tied PV system can create significant value, mostly through improved PV contribution in grid support functions like frequency regulation. An enhanced frequency regulation functioning scheme for a grid-connected photovoltaic (PV) system is modelled in MATLAB/Simulink software environment. The system is designed to operate in grid ancillary services precisely, frequency regulation function. The model consists of a Photovoltaic (PV) plant with a battery connected to the grid through a three-phase inverter. A bi-directional DC-DC converter between the grid and the battery system is included. The model has a battery storage system that provide steady and regular active/reactive powers available while the grid transmit specific amounts of power needed for a specific duration. According to the design, either the grid or the PV system depending on the dominant energy situation charges the battery. The battery is designed to discharge only when the grid demands energy from the PV and if the PV system fails to meet the demanded active power or reactive power. The PV system and the battery storage is integrated with the grid with the aid of dc-ac inverter in such a manner that bi-directional flow of active and reactive power is achieved. A 1 MW PV system is connected to the utility grid through a three-phase voltage source inverter system. The grid nominal frequency is set at 50 Hz under normal operation. However, the frequency decreased when the PV was not producing required power hence, the battery responded almost instantaneously and returned the frequency to the nominal frequency. The effectiveness of battery storage system for utility grid frequency regulation was substantiated from the simulation results attained.
223

CubeSat Constellation Design for Intersatellite Linking

White, Michael T. 20 June 2019 (has links)
This thesis investigates the concept of controlling a CubeSat constellation in low-Earth orbit. Low-Earth orbits are considered because the torque used for satellite control is supplied with magnetorquers, and the closer the satellite is to Earth’s magnetic field the more control gain can be supplied. Also, this is the expected orbit altitude of future CubeSat constellations to enable communications. Controlling a CubeSat relies on attitude determination. This means being able to estimate its attitude relative to a given reference frame. To determine the attitude, we propose to use a star tracker and a Kalman filter. A star tracker scans the stars in the satellite’s view, correlates the object to a database, to return an attitude measurement. The measurement is then processed using the Kalman filter. The attitude estimate is then used as the reference input for the controller. Once the attitude of the satellites is determined, a controller can be implemented; assuming the system is controllable and observable. These parameters are verified by adding enough actuators and sensors, respectively. The novelty of this thesis is constructing a controller that will take three satellites and their attitude estimates and arrange them broadside to a target. For simplicity, the arrangement will be a linear formation, and the target and satellite constellation will all be near-field communication. The goal is to place the satellite constellation in an attitude for an intersatellite link to be established. This is a proposed solution to better budget power and computational constraints associated with CubeSats. In addition to adjusting the topology of the system, a communication method must be considered for the data to be distributed across the system requiring an antenna design to implement the communication method. Both issues are discussed in the thesis; however, the focus is the controller design for attitude control. The control approach is a multi-input multi-output (MIMO) sliding fuzzy controller. The focus of the analysis is attitude control for communication while maintaining the constellation in a linear formation. The results shown this controller to be a valid proof of concept.
224

Modeling and Simulation of a Small-Scale Polygeneration Energy System

Chitas, Dimosthenis January 2015 (has links)
The polygeneration is an innovative and sustainable solution which has become an attractive concept. The simultaneous production of electricity, heating and cooling including hot and cold water respectively in autonomous smaller energy systems can manage a more flexible and environmentally friendly system. Furthermore distributed generation and micro scale polygeneration systems can perform the increase of the utilized renewable energy sources in the power generation. The aforementioned energy systems can consist of several power generation units however the low emission levels, the low investment costs and the fuel flexibility of microturbines are some of the reasons that the study of the microturbines in polygeneration systems is a crucial necessity. In this study, an autonomous small-scale polygeneration energy system is investigated and each component is analyzed. The components of the system are a microturbine, a heat recovery boiler, a heat storage system and an absorption chiller. The purpose of this work is the development of a dynamic model in Matlab/Simulink and the simulation of this system, aiming to define the reliability of the model and understand better the behavior of such a system. Special focus is given to the model of the microturbine due to the complexity and the control methods of this system. The dynamic model is mainly based on thermodynamic equations and the control systems of the microturbine on previous research works. The system has as a first priority the electricity supply while thermal load is supplied depending on the electric demand. The thermal load is supplied by hot water due to the heat recovery which takes place at the heat recovery boiler from the flue gases of the microturbine. Additionally the design of the system is investigated and an operational strategy is defined in order to ensure the efficient operation of the system. For this reason, after creating the load curves for a specific load, two different cases are simulated and a discussion is done about the simulation results and the future work.
225

Modeling and Optimization of a Fuel Cell Hybrid System / Modellering och optimering av en bränslecell hybrid system

Bertini, Lorenzo January 2011 (has links)
The purpose of this project was the modeling, optimization and prediction of a hybrid system composed of a fuel cell, a dc-dc converter and a supercapacitor in series. Lab tests were performed for each device to understand their behavior, and then each one was modeled using software (Simulink). The validation of the model was done by comparing its results with measured data; finally the model was used for the optimization and the prediction of the hybrid system
226

Simulering av tidskontinuerliga inkrementella sigma-delta A/D-omvandlare : Med hjälp av MATLAB/Simulink

Christiansen, Adrian January 2022 (has links)
Detta arbete inleds med en översiktlig teoretiskt bakgrund om analog till digital-omvandlare(A/D-omvandlare). Vartefter arbetet beskriver två kända metoder för att transformera återkopplingsloopar konstruerade i den tidsdiskreta z-domänen till den tidskontinuerliga Laplace-domänen. En simulering genomfördes för att visa hur en av dessa metoder gav en förväntadbrusformning. Mätning av brus med diskret Fouriertransform beskrivs och en modell av en inkrementellsigma-delta A/D-omvandlare simuleras för att visa hur en enkel räknare kan användas i deci-meringen.
227

Untersuchungen zum Einsatz von Elektrokleinkehrmaschinen als Beitrag zur Dekarbonisierung des kommunalen Verkehrs: Können konventionelle Kleinkehrmaschinen (KKM) durch elektrische Äquivalente substituiert werden?

Budich, Rene 30 January 2020 (has links)
Die Substituierung konventionell angetriebener Kleinkehrmaschinen (KKM) durch elektrisch betriebene Äquivalente, kann zu einer Verbesserung der Luft- und Lebensqualität insbesondere in Ballungszentren führen. Dabei sind nicht nur die lokal CO2-neutrale Fortbewegung entscheidend, sondern auch Maßnahmen zur Geräuschminimierung. Diese Arbeit stellt Lösungsansätze vor und wählt aus verschiedenen Konzepten eine Vorzugsvariante aus, die im Anschluss realisiert und untersucht wird. Dabei werden zunächst messtechnische Untersuchungen an ausgewählten KKM durchgeführt, die im Weitern dafür verwendet werden eine Konzeptauswahl zu treffen. Aus den gewonnen Datensätzen werden u. a. ein Analysetool zur routen- und situationsabhängigen Energieverbrauchsermittlung sowie eine Ganzfahrzeugsimulation erstellt. Das realisierte Labormusterfahrzeug wird zur Validierung der Ganzfahrzeugsimulation und als „Proof of Concept“ verwendet, um entsprechende Annahmen zur Verbrauchsreduzierung nachzuweisen. Die vorliegende Dissertation liefert damit einen Beitrag zur Emissionsreduzierung und Dekarbonisierung, speziell in dicht besiedelten Großstädten. Kern der Arbeit ist die Untersuchung der Elektrifizierung von Kleinkehrmaschinen und der damit einhergehenden erwartbaren Emissionsminderung. Dabei werden u. a. folgende Forschungsfragen beantwortet: • Wie können Kleinkehrmaschinen (KKM) wissenschaftlich untersucht und miteinander verglichen werden? • Wie kann eine KKM verbessert/angepasst/optimiert werden, um Emissionen zu reduzieren und somit Schadstoffe für Mensch und Tier sowie Treibhausgase zu minimieren? • Können verbrennungskraftbetriebene Kleinkehrmaschinen (VK-KKM) durch elektrische Kleinkehrmaschinen (E-KKM) substituiert werden?
228

Control and Automation of a Heat Shrink Tubing Process

Yousefi Darani, Shahrokh 08 1900 (has links)
Heat shrink tubing is used to insulate wire conductors, protect wires, and to create cable entry seals in wire harnessing industries. Performing this sensitive process manually is time consuming, the results are strongly dependent on the operator’s expertise, and the process presents safety concerns. Alternatively, automating the process minimizes the operators’ direct interaction, decreases the production cost over the long term, and improves quantitative and qualitative production indicators dramatically. This thesis introduces the automation of a heat shrink tubing prototype machine that benefits the wire harnessing industry. The prototype consists of an instrumented heat chamber on a linear positioning system, and is fitted with two heat guns. The chamber design allows for the directing of hot air from the heat guns onto the wire harness uniformly through radially-distributed channels. The linear positioning system is designed to move the heat chamber along the wire harness as the proper shrinkage temperature level is reached. Heat exposure time as a major factor in the heat shrink tubing process can be governed by controlling the linear speed of the heat chamber. A control unit manages the actuator position continuously by measuring the chamber’s speed and temperature. A model-based design approach is followed to design and test the controller, and MATLAB/Simulink is used as the simulation environment. A programmable logic controller is selected as the controller implementation platform. The control unit performance is examined and its responses follow the simulation results with adequate accuracy.
229

Simulink Based Modeling of a Multi Global Navigation Satellite System

Mukka, Nagaraju 12 1900 (has links)
The objective of this thesis is to design a model for a multi global navigation satellite system using Simulink. It explains a design procedure which includes the models for transmitter and receiver for two different navigation systems. To overcome the problem, where less number of satellites are visible to determine location degrades the performance of any positioning system significantly, this research has done to make use of multi GNSS satellite signals in one navigation receiver.
230

USING N-MODULAR REDUNDANCYWITH KALMAN FILTERS FORUNDERWATER VEHICLE POSITIONESTIMATION

Enquist, Axel January 2022 (has links)
Underwater navigation faces many problems with accurately estimating the absolute positionof an underwater vehicle. Neither Global Positioning system (GPS) nor Long Baseline (LBL) orShort Baseline (SBL) are possible to use for a military vehicle acting under stealth, since thesetechniques require the vehicle to be in the vicinity of a nearby ship or to surface and raise its antenna. It will therefore have to rely on sensors such as Doppler Velocity Log (DVL) and a compassto estimate its absolute position using dead reckoning or an Inertial Navigation System (INS). Thisthesis presents an alternative Multiple model Kalman Filter (KF) to the existing Multiple ModelAdaptive Estimator (MMAE) algorithm using n-Modular Redundancy (NMR), in order to gaina more accurate result than with a single KF. By analyzing how different amounts of filters andvoter types affect the accuracy and precision of the velocity and heading estimations, the potentialbenefits and drawbacks can be drawn for each solution. Such benefits and drawbacks were alsovisually evaluated in a Matlab script which was used to calculate the coordinates using the velocityand heading from the speed sensors and compass, without the need for running the filtered states onthe vehicle’s navigation system. The results present the potential of using a multiple model KF inthe form of an NMR, which was demonstrated by both the amount of reduced noise in the velocitystates and how the filters were used in a virtual navigation system created in Matlab.

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