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Transport and, United States

Swartz C.H.,Texas State University | Noriega O.C.,Texas State University | Jayathilaka P.A.R.D.,Texas State University | Edirisooriya M.,Texas State University | And 9 more authors.
2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014

Confocal photoluminescence is shown to be a powerful tool for analyzing defect structure in epitaxial CdTe appropriate for photovoltaic applications. Non-radiative defects such as dislocations are easily mapped and quantified. Photoluminescence intensity measurements are shown to be a valuable tool for quantifying interface state density. Very low dislocation density and twin content can be achieved for epitaxial CdTe, and low interface state densities result from using CdMgTe barriers. © 2014 IEEE. Source

Deshpande S.,Arizona State University | Rivera D.E.,School for Engineering of Matter
Proceedings of the IEEE Conference on Decision and Control

This paper examines the design of input signals for identification of Hammerstein systems in a data-centric framework by addressing the optimal distribution of regressors. Data-centric estimation methods such as Model-on-Demand (MoD) generate local function approximations from a database of regressors at the current operating point. The data-centric input signal design formulation aims to develop sufficient support in the regressor space for the MoD estimator, while addressing time-domain constraints on the input and output signals. A numerical example is shown to highlight the benefit of proposed design over classical Pseudo Random Binary Sequence (PRBS), Multi Level Pseudo Random Sequence (MLPRS) and uniform random input designs. © 2013 IEEE. Source

Deshpande S.,Arizona State University | Rivera D.E.,School for Engineering of Matter
Proceedings of the IEEE Conference on Decision and Control

Data-centric system identification approaches generate a local function approximation from a database of regressors at a given operating point. This paper studies the design of input signals for data-centric identification of highly interactive multivariable systems which show strong gain directionality. The input signal design formulation aims to develop uniform coverage in the output space by addressing the optimal distribution of time-indexed output points under general operating constraints on the manipulated input and measured output signals. The solution of resulting nonconvex quadratic program is proposed using semidefinite and nonlinear programming methods. A numerical example is shown to highlight the benefit of proposed design in comparison to the input design based on Weyl's criterion for data of finite length. © 2014 IEEE. Source

Stith J.L.,U.S. National Center for Atmospheric Research | Twohy C.H.,Oregon State University | Demott P.J.,Colorado State University | Baumgardner D.,National Autonomous University of Mexico | And 3 more authors.
Atmospheric Chemistry and Physics

In situ airborne sampling of refractory black carbon (rBC) particles and Ice Nuclei (IN) was conducted in and near an extratropical cyclonic storm in the western Pacific Ocean during the Pacific Dust Experiment, PACDEX, in the spring of 2007. Airmass origins were from Eastern Asia. Clouds associated primarily with the warm sector of the storm were sampled at various locations and altitudes. Cloud hydrometeors were evaporated by a counterflow virtual impactor (CVI) and the residuals were sampled by a single particle soot photometer (SP2) instrument, a continuous flow diffusion chamber ice nucleus detector (CFDC) and collected for electron microscope analysis. In clouds containing large ice particles, multiple residual particles were observed downstream of the CVI for each ice particle sampled on average. The fraction of rBC compared to total particles in the residual particles increased with decreasing condensed water content, while the fraction of IN compared to total particles did not, suggesting that the scavenging process for rBC is different than for IN. In the warm sector storm midlevels at temperatures where heterogeneous freezing is expected to be significant (here ĝ̂'24 to ĝ̂'29 °C), IN concentrations from ice particle residuals generally agreed with simultaneous measurements of total ice concentrations or were higher in regions where aggregates of crystals were found, suggesting heterogeneous freezing as the dominant ice formation process in the mid levels of these warm sector clouds. Lower in the storm, at warmer temperatures, ice concentrations were affected by aggregation and were somewhat less than measured IN concentrations at colder temperatures. The results are consistent with ice particles forming at storm mid-levels by heterogeneous freezing on IN, followed by aggregation and sedimentation to lower altitudes. Compositional analysis of the aerosol and back trajectories of the air in the warm sector suggested a possible biomass burning source for much of the aerosol. Comparison of the particles from the CFDC with the other aerosol in the residuals of ice particles suggested that the largest portion of IN had similar inferred origins (from biomass burning with minor amounts of rBC) as the other aerosol, but contained slightly elevated amounts of calcium and less influence from sea salt. © 2011 Author(s). Source

Cheng Q.,School for Engineering of Matter | Song Z.,School for Engineering of Matter | Ma T.,School for Engineering of Matter | Smith B.B.,School for Engineering of Matter | And 4 more authors.
Nano Letters

Paper folding techniques are used in order to compact a Li-ion battery and increase its energy per footprint area. Full cells were prepared using Li 4Ti5O12 and LiCoO2 powders deposited onto current collectors consisting of paper coated with carbon nanotubes. Folded cells showed higher areal capacities compared to the planar versions with a 5 × 5 cell folded using the Miura-ori pattern displaying a ∼14× increase in areal energy density. © 2013 American Chemical Society. Source

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