Polarisation photometric stereo

© 2017 This paper concerns a novel approach to fuse two-source photometric stereo (PS) data with polarisation information for complete surface normal recovery for smooth or slightly rough surfaces. PS is a well-established method but is limited in application by its need for three or more well-spaced and known illumination sources and Lambertian reflectance. Polarisation methods are less studied but have shown promise for smooth surfaces under highly controlled capture conditions. However, such methods suffer from inherent ambiguities and the depolarising effects of surface roughness. The method presented in this paper goes some way to overcome these limitations by fusing the most reliable information from PS and polarisation. PS is used with only two sources to deduce a constrained mapping of the surface normal at each point onto a 2D plane. Phase information from polarisation is used to deduce a mapping onto a different plane. The paper then shows how the full surface normal can be obtained from the two mappings. The method is tested on a range of real-world images to demonstrate the advantages over standalone applications of PS or polarisation methods

What Else Could I Do? The Self Definition of Consequentialists.

Ask yourself, what am I capable of, what incapable of? Answering that question will tell you the kind of person you are. The consequentialist is in principle capable of anything, Thomas More was not. Which kind of person do you want to be? And your children

Decision theory process for making a mitigation decision on harmonic resonance in power systems

Includes bibliographical references.Decision analysis is a scientific tool that is traditionally applied in business and not to electrical engineering decisions. The reason for this research is to show how to use decision analysis to make a decision on the size of a power factor correction capacitor to be installed in an end-user plant in an electrical power system, that has the potential for harmonic resonance. How to make a decision as to whether or not mitigation is needed is also researched. The two-stage decision theory process, developed by management scientists, to assist decision makers on making a decision when uncertainty, risk and certainty situations-exist, is reviewed in this thesis. To understand the application of decision theory, worked examples are included to improve understanding and to provide a foundation for the new work introduced. The addition of capacitors to a harmonic carrying system can result in resonance. Harmonic levels can be magnified well above accepted limits and this can cause damage to system components, especially capacitors. Recognizing and correcting a harmonic resonance problem before disastrous consequences arise is essential for system designers. Traditionally, when considering harmonic resonance, power factor correction capacitors are sized heuristically and a power factor of 0.95 is taken as a starting point. Usually, a harmonic analysis software package is used and a frequency scan study is conducted to generate a resonance curve. Resonant points are then compared to the harmonics in the system. If there is coincidence, the technique of de-tuning is applied to overcome overlapping and to choose the capacitor size. For utilities to maintain system efficiencies at acceptable levels, they encourage end-users to use a capacitor size so that the power factor has a value greater than 0.9 and as a rule of thumb, correction is not done to unity. This traditional technique is subjective and lacks decision structure. A new three-stage decision theory process for making a harmonic resonance mitigation decision in an end-user plant is developed. Two new indices are developed to assist in making the decision. The first index assesses the severity of resonance and the second is used to make a mitigation decision. In Stage 1, a quantitative model is developed to structure and represent the decision problem with the harmonic resonance severity index as the objective function. The model uses a fixed capacitor based on full load rating as this represents the worst case. In Stage 2, Utility Theory is used as the decision criterion to select the most desirable capacitor size. In Stage 3, the mitigation index is applied to assess if mitigation is needed or not for the chosen capacitor. Three case studies, based on deterministic models are conducted and they demonstrate the effectiveness of this newly developed decision theory process

Comparison of Transmission Line Methods for Surface Acoustic Wave Modeling

Surface Acoustic Wave (SAW) technology is low cost, rugged, lightweight, extremely low power and can be used to develop passive wireless sensors. For these reasons, NASA is investigating the use of SAW technology for Integrated Vehicle Health Monitoring (IVHM) of aerospace structures. To facilitate rapid prototyping of passive SAW sensors for aerospace applications, SAW models have been developed. This paper reports on the comparison of three methods of modeling SAWs. The three models are the Impulse Response Method (a first order model), and two second order matrix methods; the conventional matrix approach, and a modified matrix approach that is extended to include internal finger reflections. The second order models are based upon matrices that were originally developed for analyzing microwave circuits using transmission line theory. Results from the models are presented with measured data from devices. Keywords: Surface Acoustic Wave, SAW, transmission line models, Impulse Response Method