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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.
1

Comparison of the effects of realistic flux surface models on calculations of plasma asymmetries in DIII-D

Collart, Timothy Gerard 07 January 2016 (has links)
Several methods are presented for improving upon the traditional analytic “circular” method for constructing a flux-surface aligned curvilinear coordinate system representation of equilibrium plasma geometry and magnetic fields, and the most accurate Asymmetric Miller method is applied to calculations of poloidal asymmetries in plasma density, velocity, and electric potential. Techniques for developing an orthogonalized coordinate system from a general curvilinear representation of plasma flux surfaces and for representing the poloidal component of the magnetic field in the orthogonalized curvilinear system are developed generally, in order to be applied to four plasma flux-surface models. The formalism for approximating flux surfaces originally presented by Miller is extended to include poloidal asymmetries between the upper and lower plasma hemispheres, and is subsequently shown to be more accurate at fitting the shapes of flux surfaces calculated using EFIT than both the traditional “circular” model and two alternative curvilinear models of comparable complexity based on Fourier expansions of major radius, vertical position, and minor radius. Applying the coordinate system orthogonalization technique to these four models allows for calculations of the poloidal magnetic field which, upon comparison to a calculation of the poloidal field performed in a Cartesian system using the experimentally based EFIT prediction for the Grad-Shafranov equilibrium, demonstrates that the asymmetric “Miller” model is also superior to other methods at representing the poloidal magnetic field. A system of equations developed by representing the poloidal variations of velocity, density, and electric potential using O(1) Fourier expansions in the flux-surface averaged neoclassical plasma continuity and momentum balances is solved using several variations of both the “Miller” and “circular” curvilinear models to set geometric scale factors, illustrating the effects that these improvements in geometric modeling have on tokamak fluid theory calculations.
2

Simulace lokalizace IP stanic pomocí algoritmů Vivaldi a GNP / Simulation of IP node localization, using Vivaldi and GNP algorithms

Sulík, Peter January 2011 (has links)
The work deals with the issues of network coordinate systems. The first chapter is devoted to a brief analysis of this systems and requirements placed on them. Furthermore, it deals with features of Vivaldi algorithm and its three versions: a centralized algorithm, algorithm with constant and adaptive time step. Subsequently it describes the GNP system and eash step of Nelder-Mead method for nodes localization. Next to it a developed simulation library is presented with its own graphical user interface for testing of these algorithms, which is capable of handling RTT responses database amongst individual IP network members. Simulations performed on data from PlanetLab network are evaluated in the conclusion.
3

Organizing a Global Coordinate System from Local Information on an Amorphous Computer

Nagpal, Radhika 29 August 1999 (has links)
This paper demonstrates that it is possible to generate a reasonably accurate coordinate system on randomly distributed processors, using only local information and local communication. By coordinate systems we imply that each element assigns itself a logical coordinate that maps to its global physical location, starting with no apriori knowledge of position or orientation. The algorithm presented is inspired by biological systems that use chemical gradients to determine the position of cells. Extensive analysis and simulation results are presented. Two key results are: there is a critical minimum average neighborhood size of 15 for good accuracy and there is a fundamental limit on the resolution of any coordinate system determined strictly from local communication. We also demonstrate that using this algorithm, random distributions of processors produce significantly better accuracy than regular processor grids - such as those used by cellular automata. This has implications for discrete models of biology as well as for building smart sensor arrays.
4

Mobilní robot s GNSS navigací / GNSS Navigated Mobile Robot

Chmelař, Jakub January 2018 (has links)
The diploma thesis is focused on the topic of global satellite navigation of mobile robots. The paper describes the principle of currently available global satellite navigation systems. The main element of the thesis is the proposal of mobile robot navigation algorithm. An integral part is also the design of a mobile robot to verify the functionality of the navigation algorithm. The robot software program is described. At the end, everything is verified by real experiments.
5

An Algorithm and System for Measuring Impedance in D-Q Coordinates

Francis, Gerald 10 May 2010 (has links)
This dissertation presents work conducted at the Center for Power Electronics Systems (CPES) at Virginia Polytechnic Institute and State University. Chapter 1 introduces the concept of impedance measurement, and discusses previous work on this topic. This chapter also addresses issues associated with impedance measurement. Chapter 2 introduces the analyzer architecture and the proposed algorithm. The algorithm involves locking on to the voltage vector at the point of common coupling between the analyzer and the system via a PLL to establish a D-Q frame. A series of sweeps are performed, injecting at least two independent angles in the D-Q plane, acquiring D- and Q-axis voltages and currents for each axis of injection at the point of interest. Chapter 3 discusses the analyzer hardware and the criteria for selection. The hardware built ranges from large-scale power level hardware to communication hardware implementing a universal serial bus. An eight-layer PCB was constructed implementing analog signal conditioning and conversion to and from digital signals with high resolution. The PCB interfaces with the existing Universal Controller hardware. Chapter 4 discusses the analyzer software. Software was written in C++, VHDL, and Matlab to implement the measurement process. This chapter also provides a description of the software architecture and individual components. Chapter 5 discusses the application of the analyzer to various examples. A dynamic model of the analyzer is constructed, considering all components of the measurement system. Congruence with predicted results is demonstrated for three-phase balanced linear impedance networks, which can be directly derived based on stationary impedance measurements. Other impedances measured include a voltage source inverter, Vienna rectifier, six-pulse rectifier and an autotransformer-rectifier unit. / Ph. D.
6

Automation of depowdering step in binder-jet additive manufacturing : Commissioning of KUKA robot

Kolluri, Sowjanya January 2017 (has links)
The aim of this thesis is to automate the depowdering step in binder-jet additive manufacturing using KUKA kr6 robot. The major tasks involved in this thesis work are commissioning of the KUKA kr6 robot, plan the actions required for automation process of binder jet considering the scaling factor of green bodies. For this purpose KUKA robot with a standard KUKA compact controller (KRC4) and KUKA system software 8.3 (KSS) has been used. In Peter Corke Matlab toolbox (Matlab toolbox), KUKA kr6 robot model has been simulated to understand forward kinematics problem which shows the study the motion of end effector of robot in space for picking process. These transformations between the Joint coordinate systems and Cartesian coordinate systems give the forward and inverse kinematics. Firstly, a KUKA kr6 robot has been programmed in a KUKA Robot Language (KRL) using an algebraic approach with geometric operator to automate the picking process of green bodies. These are fragile bodies thereby many number of tests have been conducted to improve the program. Also additional effort has been placed to test the customized gripper used for the layered pick and place of the components, customized vacuum cleaner for the vacuum cleaning in between the layers and to consider the scaling factor during the sintering step of the binder jet. Finally, KUKA kr6 robot model has been simulated in Matlab toolbox. The picking point in the space has been simulated to study the forward kinematics and to understand how the robot reaches a position and orientation in space. Cartesian trajectory has been simulated. Also, the Jacobian matrix, its rank and determinant are studied to understand the singularities in KUKA kr6 robot, basing on which the thesis work can be continued and enhanced further.
7

Lokalizace stanic v síti Internet pomocí umělých souřadnicových systémů / Node localization on the Internet using artificial coordinate systems

Škvor, Martin January 2010 (has links)
This thesis is focused on methods for nodes localization in Internet using latency prediction in synthetic coordinates systems. Thesis also deal with methods, which latency prediction between nodes is based on other systems. Among such a methods particularly belongs King, which uses DNS (domain name service). Furthermore, thesis deal with relevance of overlay networks in latency prediction and their use for different services. Practical part of this thesis concentrates on method for latency prediction in synthetic coordinate system Global Network positioning. There were made two programs for counting coordinates of landmarks and hosts in this system. Measurements and calculations made in this thesis, are focused to determine accuracy of latency prediction of this method and their evaluation is made at the end of thesis.
8

Polohový a kursový referenční systém / Attitude and Heading Reference System

Chotaš, Kryštof January 2014 (has links)
This thesis deals with inertial navigation systems issues. It describes basics of reference frames, coordinate systems and matrix calculations for AHRS. There are also basic information about inertial sensors, inertial measurements units and its mistakes. One of the purposes of this paper could be explanation of inertial navigation systems terms. The main object of this thesis is to explore the influence of using multiple sensors of same type to enhance measurements of AHRS systems.
9

Webové služby pro podporu geolokace v rozsáhlých sítích / Web-Services for Geo-Location Support in Wide-Area Networks

Imlauf, Michal January 2012 (has links)
The goal of this master's thesis is to describe geolocation techniques in wireless wide-area networks and the ways of expressing the individual node location. Practical part describes implementation of web services that simulate the node movement in these wireless networks and implementation of web service that is going to agregate the coordinate systems of these wireless networks.
10

The Effects of Radial Core Decompression on Lunate and Scaphoid Kinematics

Smith, Andrew E. 06 July 2012 (has links)
No description available.

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