Real-time comparisons of ionospheric data with outputs from the UAF eulerian parallel polar ionosphere model

Thesis (M.S.) University of Alaska Fairbanks, 2007The UAF theoretical polar ionospheric model (UAF EPPIM) solves 3D equations of mass, momentum, and energy balance for multiple ion species to determine ion and electron parameters in the polar ionosphere region using a parallel numerical code on an Eulerian grid. Real time operation of the model is very important because users are interested in current space weather conditions. Real-time validation of this model with available experimental data is an important task for the following reasons. (1) Real-time validation can provide much information about the model quality and define the directions of improvement. (2) Real-time comparisons help to determine trusted intervals for the model parameters for future data assimilation tasks. In this work, we have developed an operational real-time comparisons capability which assimilates HAARP (High frequency Active Auroral Research Program) experimental data for the model validation purposes. Software has been developed to emulate Total Electron Content (TEC). Results are then compared with real-time data from HAARP. Further, we have developed a Computerized Ionospheric Tomography (ClT) model which provides ionosphere tomography images covering five different stations in Alaska along the geomagnetic latitude (50-78 degrees). Then these images are compared with real-time ionosphere tomography images obtained at the HAARP website.1. Introduction -- 2. Coordinate systems overview -- 3. The ionosphere and its monitoring -- 4. GPS total electron content comparisons -- 5. Ionospheric tomography -- 6. Software development -- 7. Summary, conclusions, and future work -- References -- Appendix: NOAA format data file

Porous ferroelectrics for energy harvesting applications

This paper provides an overview of energy harvesting using ferroelectric materials, with a particular focus on the energy harvesting capabilities of porous ferroelectric ceramics for both piezo- and pyroelectric harvesting. The benefits of introducing porosity into ferro- electrics such as lead zirconate titanate (PZT) has been known for over 30 years, but the potential advantages for energy harvesting from both ambient vibrations and temperature fluctuations have not been studied in depth. The article briefly discusses piezoelectric and pyro- electric energy harvesting, before evaluating the potential benefits of porous materials for increasing energy harvesting figures of merits and electromechanical/electrothermal coupling factors. Established processing routes are evaluated in terms of the final porous structure and the resulting effects on the electrical, thermal and mechanical properties

Electronic properties of negatively charged SiOx films deposited by Atmospheric Pressure Plasma Liquid Deposition for surface passivation of p-type c-Si solar cells

Here we demonstrate the influence of firing temperatures on the electronic properties of Atmospheric Pressure Plasma Liquid Deposition (APPLD) silicon dioxide films due to reformed material composition and its overall impact on surface passivation quality. Experimentally extracted electronic parameters using electrical capacitance voltage-conductance (C-V-G) measurements on aMetal-Oxide-Semiconductor (MOS) structure reveal that films fired at 810 °C show a slightly higher concentration of negative fixed charges (−Qf) and interface trap charges (Dit) compared to films fired at 940 °C. Such a dependency on the firing temperature can be attributed to variation in the net concentrations of silanol and carbon groupswithin the films, subsequently influencing the type of passivation mechanism involved. We show that for films fired at 810 and 940 °C, the predominant passivation mechanisms are related to field effect induced by excess silanol groups and chemical passivation due to the absence of electrically active carbon related defects, respectively. Additionally, dielectric constant (K) extraction from C-V measurements at 1 kHz returns an almost 2-fold higher K-value for films fired at 810 °C (K ~ 21) compared to films fired at 940 °C (K ~ 12), due to excess silanol concentration in the former films