Signal Processing and Robust Statistics for Fault Detection in Photovoltaic Arrays

abstract: Photovoltaics (PV) is an important and rapidly growing area of research. With the advent of power system monitoring and communication technology collectively known as the "smart grid," an opportunity exists to apply signal processing techniques to monitoring and control of PV arrays. In this paper a monitoring system which provides real-time measurements of each PV module's voltage and current is considered. A fault detection algorithm formulated as a clustering problem and addressed using the robust minimum covariance determinant (MCD) estimator is described; its performance on simulated instances of arc and ground faults is evaluated. The algorithm is found to perform well on many types of faults commonly occurring in PV arrays. Among several types of detection algorithms considered, only the MCD shows high performance on both types of faults.Dissertation/ThesisM.S. Electrical Engineering 201

Estimating Anthropometric Marker Locations from 3-D LADAR Point Clouds

An area of interest for improving the identification portion of the system is in extracting anthropometric markers from a Laser Detection and Ranging (LADAR) point cloud. Analyzing anthropometrics markers is a common means of studying how a human moves and has been shown to provide good results in determining certain demographic information about the subject. This research examines a marker extraction method utilizing principal component analysis (PCA), self-organizing maps (SOM), alpha hulls, and basic anthropometric knowledge. The performance of the extraction algorithm is tested by performing gender classification with the calculated markers

Determination of chaotic behaviour in time series generated by charged particle motion around magnetized Schwarzschild black holes

We study behaviour of ionized region of a Keplerian disk orbiting a Schwarzschild black hole immersed in an asymptotically uniform magnetic field. In dependence on the magnetic parameter ${\cal B}$, and inclination angle $\theta$ of the disk plane with respect to the magnetic field direction, the charged particles of the ionized disk can enter three regimes: a) regular oscillatory motion, b) destruction due to capture by the magnetized black hole, c) chaotic regime of the motion. In order to study transition between the regular and chaotic type of the charged particle motion, we generate time series of the solution of equations of motion under various conditions, and study them by non-linear (box counting, correlation dimension, Lyapunov exponent, recurrence analysis, machine learning) methods of chaos determination. We demonstrate that the machine learning method appears to be the most efficient in determining the chaotic region of the $\theta-r$ space. We show that the chaotic character of the ionized particle motion increases with the inclination angle. For the inclination angles $\theta \sim 0$ whole the ionized internal part of the Keplerian disk is captured by the black hole.Comment: 21 pages, 9 figure

A 3-DOF Stewart Platform for Trenchless Pipeline Rehabilitation

A major component of the infrastructure of any modern city is a network of underground pipes that transport drinking water, storm water and sewage. Most of the pipes currently being used are made out of concrete or various plastics. As with any material, they have an expected lifespan after which deterioration begins to occur. This can result in cracks, and in some cases, even large holes in the pipe which can cause a complete loss of function of the pipe. These defects invariably lead to water losses that necessitate the repair of the pipeline, which is an expensive undertaking. The purpose of this thesis is to give a detailed report of the development and testing of a robot with a spray head that is autonomously controlled. This spray head will deposit a liquid material onto the pipe that will then cure to form the new interior wall of the pipe. The design of the robot most suited to this task is a Stewart platform: a parallel manipulator that uses prismatic actuators to control a single end-effector. In contrast to the traditional Stewart platform design, which has six independently controlled legs that are used to control the position of the top platform, a novel design is used which has only three independently controlled legs. The advantages of this design are less weight, less complicated kinematics and a smaller design envelope. A circular trajectory was implemented in the microcontroller code and the accuracy of the Stewart platform was evaluated using videos and image processing techniques. An optimization algorithm is proposed which combines the controlled random search algorithm and the particle swarm optimization algorithm. The effectiveness of this algorithm is demonstrated by selecting the design parameters of a 3-DOF Stewart platform so that the radius of the circular spray path is maximized

Application of digital interferogram evaluation techniques to the measurement of 3-D flow fields

A system for digitally evaluating interferograms, based on an image processing system connected to a host computer, was implemented. The system supports one- and two-dimensional interferogram evaluations. Interferograms are digitized, enhanced, and then segmented. The fringe coordinates are extracted, and the fringes are represented as polygonal data structures. Fringe numbering and fringe interpolation modules are implemented. The system supports editing and interactive features, as well as graphic visualization. An application of the system to the evaluation of double exposure interferograms from the transonic flow field around a helicopter blade and the reconstruction of the three dimensional flow field is given