: This thesis applies neural network feature selection techniques to multivariate time series data to improve prediction of a target time series. Two approaches to feature selection are used. First, a subset enumeration method is used to determine which financial indicators are most useful for aiding in prediction of the S&P 500 futures daily price. The candidate indicators evaluated include RSI, Stochastics and several moving averages. Results indicate that the Stochastics and RSI indicators result in better prediction results than the moving averages. The second approach to feature selection is calculation of individual saliency metrics. A new decision boundary-based individual saliency metric, and a classifier independent saliency metric are developed and tested. Ruck's saliency metric, the decision boundary based saliency metric, and the classifier independent saliency metric are compared for a data set consisting of the RSI and Stochastics indicators as well as delayed closing price values. The decision based metric and the Ruck metric results are similar, but the classifier independent metric agrees with neither of the other metrics. The nine most salient features, determined by the decision boundary based metric, are used to train a neural network and the results are presented and compared to other published results. (AN)

/pdf/nonlinear-time-series-analysis-1j3a35n4y3.pdf

Nonlinear Time Series Analysis.

(1963). Cybernetics, or Control and Communication in the Animal and the Machine. Technometrics: Vol. 5, No. 1, pp. 128-130.

Cybernetics, or Control and Communication in the Animal and the Machine

Recent progress in flapping wing aerodynamics and aeroelasticity

Biomimetics, a name coined by Otto Schmitt in the 1950s for the transfer of ideas and analogues from biology to technology, has produced some significant and successful devices and concepts in the past 50 years, but is still empirical. We show that TRIZ, the Russian system of problem solving, can be adapted to illuminate and manipulate this process of transfer. Analysis using TRIZ shows that there is only 12% similarity between biology and technology in the principles which solutions to problems illustrate, and while technology solves problems largely by manipulating usage of energy, biology uses information and structure, two factors largely ignored by technology.

/pdf/biomimetics-its-practice-and-theory-461qgvupu6.pdf

Biomimetics: its practice and theory.

Automotive disc brake squeal

It is the objective of this paper to review recent developments in the understanding and prediction of flapping-wing aerodynamics. To this end, several flapping-wing configurations are considered. First, the problem of single flapping wings is treated with special emphasis on the dependence of thrust, lift, and propulsive efficiency on flapping mode, amplitude, frequency, and wing shape. Second, the problem of hovering flight is studied for single flapping wings. Third, the aerodynamic phenomena and benefits produced by the flapping-wing interactions on tandem wings or biplane configurations are discussed. Such interactions occur on dragonflies or on a recently developed micro air vehicle. The currently available two- and three-dimensional inviscid and viscous flapping-wing flow solutions are presented. It is shown that the results are strongly dependent on flapping frequency, amplitude, and Reynolds number. These findings are substantiated by comparison with the available experimental data.

Flapping Wing Aerodynamics: Progress and Challenges

GENERATION AND RADIATION OF NOISE IN ELECTRICAL MACHINES Vibration, Sound, and Noise Sound Waves Sources of Noise in Electrical Machines Energy Conversion Process Noise Limits and Measurement Procedures for Electrical Machines Deterministic and Statistical Methods of Noise Prediction Economical Aspects Accuracy of Noise Prediction MAGNETIC FIELDS AND RADIAL FORCES IN POLYPHASE MOTORS FED WITH SINUSOIDAL CURRENTS Construction of Induction Motors Construction of Permanent Magnet Synchronous Brushless Motors A.C. Stator Windings Stator Winding MMF Rotor Magnetic Field Calculation of Air Gap Magnetic Field Radial Forces Other Sources of Electromagnetic Vibration and Noise INVERTER-FED MOTORS Generation of Higher Time Harmonics Analysis of Radial Forces for Nonsinusoidal Currents Higher Time Harmonic Torques in Induction Machines Higher Time Harmonic Torques in Permanent Magnet (PM) Brushless Machines Influence of the Switching Frequency of an Inverter Noise Reduction of Inverter-Fed Motors TORQUE PULSATIONS Analytical Methods of Instantaneous Torque Calculation Numerical Methods of Instantaneous Torque Calculation Electromagnetic Torque Components Sources of Torque Pulsations Higher Harmonic Torques of Induction Motors Cogging Torque in Permanent Magnet (PM) Brushless Motors Torque Ripple Due to Distortion of EMF and Current Waveforms in Permanent Magnet (PM) Brushless Motors Tangential Forces vs. Radial Forces Minimization of Torque Ripple in PM Brushless Motors STATOR SYSTEM VIBRATION ANALYSIS Forced Vibration Simplified Calculation of Natural Frequencies of the Stator System Improved Analytical Method of Calculation of Natural Frequencies Numerical Verification ACOUSTIC CALCULATIONS Sound Radiation Efficiency Plane Radiator Infinitely Long Cylindrical Radiator Finite Length Cylindrical Radiator Calculations of Sound Power Level NOISE AND VIBRATION OF MECHANICAL AND AERODYNAMIC ORIGIN Mechanical Noise Due to Shaft and Rotor Irregularities Bearing Noise Noise Due to Toothed Gear Trains Aerodynamic Noise Mechanical Noise Generated by the Load ACOUSTIC AND VIBRATION INSTRUMENTATION Measuring System and Transducers Measurement of Sound Pressure Acoustic Measurement Procedure Vibration Measurements Frequency Analyzers Sound Power and Sound Pressure Indirect Methods of Sound Power Measurement Direct Method of Sound Power Measurement: Sound Intensity Technique Standard for Testing Acoustic Performance of Rotating Electrical Machines NUMERICAL ANALYSIS Introduction FEM Model for Radial Magnetic Pressure FEM for Structural Modeling BEM for Acoustic Radiation Discussion STATISTICAL ENERGY ANALYSIS Introduction Power Flow Between Linearly Coupled Oscillators Coupled Multimodal Systems Experimental SEA Application to Electrical Motors NOISE CONTROL Mounting Standard Methods of Noise Reduction Active Noise and Vibration Control APPENDIX A: BASICS OF ACOUSTICS Sound Field Variables and Wave Equations Sound Radiation from a Point Source Decibel Levels and Their Calculations Spectrum Analysis APPENDIX B: PERMEANCE OF NONUNIFORM AIR GAP Permeance Calculation Eccentricity Effect APPENDIX C: MAGNETIC SATURATION APPENDIX D: BASICS OF VIBRATION A Mass-Spring-Damper Oscillator Lumped Parameter Systems Continuous Systems SYMBOLS AND ABBREVIATIONS BIBLIOGRAPHY INDEX

/pdf/noise-of-polyphase-electric-motors-2k571xl938.pdf

Noise of polyphase electric motors

Water-tunnel tests of a NACA 0012 airfoil that was oscillated sinusoidally in plunge are described. The flowered downstream of the airfoil was explored by dye flow visualization and single-component laser Doppler velocimetry (LDV) measurements for a range of freestream speeds, frequencies, and amplitudes of oscillation. The dye visualizations show that the vortex patterns generated by the plunging airfoil change from drag-producing wake flows to thrust-producing jet flows as soon as the ratio of maximum plunge velocity to freestream speed, i.e., the nondimensional plunge velocity, exceeds approximately 0.4. The LDV measurements show that the nondimensional plunge velocity is the appropriate parameter to collapse the maximum streamwise velocity data covering a nondimensional plunge velocity range from 0.18 to 9.3

Jet characteristics of a plunging airfoil

A review of progress and challenges in flapping foil power generation

The flow over a NACA 0012 airfoil, oscillated sinusoidally in plunge, is simulated numerically using a compressible two-dimensional Navier-Stokes solver at a Reynolds number of 2 ×10 4 . The wake of the airfoil is visualized using a numerical particle tracing method. Close agreement is obtained between numerically simulated wake structures and experimental wake visualizations in the literature, when the flow is assumed to be fully laminar. The wake structures, and the lift and thrust of the airfoil, are shown to be strongly dependent on both the Strouhal number and the reduced frequency k of the plunge oscillation at this Reynolds number. Leading-edge separation appears to dominate the generation of aerodynamic forces for reduced frequencies below approximately k = 4 but becomes secondary for higher frequencies. Wake structures appear to be controlled primarily by trailing-edge effects at all frequencies tested up to k=20. Aerodynamic force results obtained at this Reynolds number show marked differences from those predicted by potential flow analyses at low plunge frequency and high amplitude but are similar at high frequency and low amplitude, consistent with the effect of leading-edge separation.

Joseph C. S. Lai

Papers

Flapping Wing Aerodynamics: Progress and Challenges

Noise of polyphase electric motors

Jet characteristics of a plunging airfoil

A review of progress and challenges in flapping foil power generation

Oscillation Frequency and Amplitude Effects on the Wake of a Plunging Airfoil