False Discovery and Its Control in Low Rank Estimation

Models specified by low-rank matrices are ubiquitous in contemporary applications. In many of these problem domains, the row/column space structure of a low-rank matrix carries information about some underlying phenomenon, and it is of interest in inferential settings to evaluate the extent to which the row/column spaces of an estimated low-rank matrix signify discoveries about the phenomenon. However, in contrast to variable selection, we lack a formal framework to assess true/false discoveries in low-rank estimation; in particular, the key source of difficulty is that the standard notion of a discovery is a discrete one that is ill-suited to the smooth structure underlying low-rank matrices. We address this challenge via a geometric reformulation of the concept of a discovery, which then enables a natural definition in the low-rank case. We describe and analyze a generalization of the Stability Selection method of Meinshausen and B\"uhlmann to control for false discoveries in low-rank estimation, and we demonstrate its utility compared to previous approaches via numerical experiments

Design of an electric drivetrain for the Formula Student-class vehicle

Hlavním úkolem této diplomové práce bylo navrhnout a postavit funkční prototyp frekvenčního měniče pro použití ve vozidlech týmu eForce FEE Prague Formula, soutěžícího v mezinárodní inženýrské soutěži Formula Student. Práce je členěna do několika kapitol, kdy je nejdříve prozkoumán již minule provedený vývoj v týmu. Dále je vystavěna potřebná teorie pro vývoj frekvenčního měniče. Další kapitola detailně popisuje provedený vývoj zařízení. Poslední kapitoly se věnují zhodnocení navrženého měniče. Diplomová práce také prozkoumala nové možnosti v měření fázových proudů, umožňující vysokou přesnost při zachování nízké ceny a kompaktních rozměrů. Celkovým cílem bylo navrhnout jednoduché a robustní zařízení s nízkou výrobní cenou. Ověřování návrhu bylo provedeno v laboratořích fakulty pro ujištění připravenosti navrženého měniče pro nasazení do vozidla. Práce bude pokračovat na vylepšování řídícího algoritmu a postupné integraci do týmových vozidel.This thesis' main objective was to design and develop a functional motor controller for usage in a Formula Student competition vehicle of the eForce FEE Prague Formula team. Work is split into several chapters. Exploring a drivetrain development progression in the team, presenting a needed theory for a motor controller development and giving a detailed overview of the designed device. The last chapters are dedicated to evaluation of the design. Thesis had explored a new methodology in a phase current sensing, providing a significant precision while allowing for a low cost and compact design. Overall aim was to create a simple, robust and cheap solution. Verification of the design was performed in the laboratory environment of the faculty in order to ensure preparedness for integration into the vehicle. Further work will focus on control strategy improvements and final integration into the team's vehicles

Integrated Advanced Microwave Sounding Unit-A(AMSU-A). Performance Verification Reports: Final Comprehensive Performance Test Report, P/N: 1356008-1-TST, S/N: 202/A1

This is the Performance Verification Report, Final Comprehensive Performance Test Report, P/N 1356008-1-TST, S/N 202/A1 for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A)

The Solar System in perspective : from debris discs to extrasolar planets

The last twenty-five years have seen our understanding of the formation and abundance of planets revolutionised, thanks to the first detections of debris discs, and, a decade later, of the first extrasolar planets. Hardly a week now goes by without a planet discovery, and the range of methods used to search for planets has expanded to include techniques that are efficient at detecting different types of planets. By combining the discoveries of the various methods, we therefore have the opportunity to build a picture of planet populations across the Galaxy. In this thesis, I am presenting work done as a basis towards such an effort: first I present work carried out to improve modelling methods for gravitational microlensing events. Since the first microlensing observing campaigns, the amount of data of anomalous events has been increasing ever faster, meaning that the time required to model all observed anomalous events is putting a strain on available human and computational resources. I present work to develop a method to fit anomalous microlensing events automatically and show that it is possible to conduct a thorough and unbiased search of the parameter space, illustrating this by analysing an event from the 2007 observing season. I then discuss the possible models found with this method for this event, and their implication (Kains et al. 2009), and find that this algorithm locates good-fit models in regions of parameters that would have been very unlikely to be found using standard modelling methods. Results indicate that it is necessary to use a full Bayesian approach, in order to include prior information on the parameters. I discuss the analytical priors calculated by Cassan et al. (2009) and suggest a possible form of an automatic fitting algorithm by incorporating these priors in the algorithm used by Kains et al. (2009). Another topic with which this thesis is concerned is the evolution of debris discs around solar-type stars. Late-type stars are expected to be the most numerous host stars of planets detected with the microlensing technique. Understanding how their debris discs evolve equates to understanding the earliest stages of planet formation around these stars, allowing us to truly put our Solar System in perspective. Using the analytical model of Wyatt et al. (2007a), I modelled the evolution of infrared excess flux at 24 and 70 microns using published data of debris discs around solar-type (spectral types F, G and K) stars from the Spitzer Space Telescope. By comparing the results of this study to an analogous study carried out by for A stars by Wyatt et al. (2007b), I find that although best-fit parameters are significantly different for solar-type stars, this may be due to the varying number of inefficient emitters around stars of different spectral types. I suggest that although effective properties are different by an order of magnitude or more, intrinsic properties, while still different, are so by a much smaller factor. These differences may be due to the longer timescales over which solar-type stars evolve, which allow for the formation of larger and stronger planetesimals

AUTOMATED GUIDED ROBOT (AGR)

This project concerns the design and fabrication of the Automated Guided Robot (AGR) prototype, utilizing artificial intelligence (AI) and genetic algorithm (GA) as a mainframe in helping the robot to generate a self-understanding of the area of work and mobilization to a destination desired by the user. The main objective of this project is to create and develop a Path Planning Mobile Robot able to avoid obstacles in its path and reach a target designated position from its starting point utilizing 3 wheel-based rover body, sensors, linear motors and microcontrollers. Compared to manual mobile robots, AGRs require sensors and control systems that generate feedback for the re-evaluation of an unexpected situation and to detect obstacles in the path the AGR is required to follow. The paper describes the network algorithms developed and used in the design process of the AGR including simulations and circuit designs done for the prototype. A general robotics circuit construction of the mainframe target board for central processing, a controller board for the sensor feedbacks and a small base tri-wheeled structure has been fabricated by the author and continual troubleshooting and enhancement has been done for these components of the AGR. Algorithm conversion to C code programming has been done throughout the project for the obstacle avoidance and path planning algorithms based upon the GA platform ofAI

On-Line Loss of Control Detection Using Wavelets

Wavelet transforms are used for on-line detection of aircraft loss of control. Wavelet transforms are compared with Fourier transform methods and shown to more rapidly detect changes in the vehicle dynamics. This faster response is due to a time window that decreases in length as the frequency increases. New wavelets are defined that further decrease the detection time by skewing the shape of the envelope. The wavelets are used for power spectrum and transfer function estimation. Smoothing is used to tradeoff the variance of the estimate with detection time. Wavelets are also used as front-end to the eigensystem reconstruction algorithm. Stability metrics are estimated from the frequency response and models, and it is these metrics that are used for loss of control detection. A Matlab toolbox was developed for post-processing simulation and flight data using the wavelet analysis methods. A subset of these methods was implemented in real time and named the Loss of Control Analysis Tool Set or LOCATS. A manual control experiment was conducted using a hardware-in-the-loop simulator for a large transport aircraft, in which the real time performance of LOCATS was demonstrated. The next step is to use these wavelet analysis tools for flight test support

Reliability Abstracts and Technical Reviews January - December 1970

Reliability Abstracts and Technical Reviews is an abstract and critical analysis service covering published and report literature on reliability. The service is designed to provide information on theory and practice of reliability as applied to aerospace and an objective appraisal of the quality, significance, and applicability of the literature abstracted

A Small Acoustic Goniometer for General Purpose Research

Understanding acoustic events and monitoring their occurrence is a useful aspect of many research projects. In particular, acoustic goniometry allows researchers to determine the source of an event based solely on the sound it produces. The vast majority of the acoustic goniometry research projects used custom hardware targeted to the specific application under test. Unfortunately, due to the wide range of sensing applications, a flexible general purpose hardware/firmware system does not exist for this research. This dissertation focuses on the development of such a system which encourages the continued exploration of general purpose hardware/firmware and lowers barriers to research in projects requiring the use of acoustic goniometry. Simulations have been employed to verify system feasibility, and a complete hardware implementation of the acoustic goniometer has been designed and field tested. The results are reported, and suggested areas for improvement and further exploration are discussed