Investigation into Photoconductivity in Single CNF/TiO2-Dye Core–Shell Nanowire Devices

A vertically aligned carbon nanofiber array coated with anatase TiO2 (CNF/TiO2) is an attractive possible replacement for the sintered TiO2 nanoparticle network in the original dye-sensitized solar cell (DSSC) design due to the potential for improved charge transport and reduced charge recombination. Although the reported efficiency of 1.1% in these modified DSSC’s is encouraging, the limiting factors must be identified before a higher efficiency can be obtained. This work employs a single nanowire approach to investigate the charge transport in individual CNF/TiO2 core–shell nanowires with adsorbed N719 dye molecules in dark and under illumination. The results shed light on the role of charge traps and dye adsorption on the (photo) conductivity of nanocrystalline TiO2 CNF’s as related to dye-sensitized solar cell performance

Analysis of air radiation measurements obtained in the EAST and X2 shocktube facilities

This paper presents measurements of equilibrium radiation obtained in the NASA Ames Research Center’s EAST facility and the University of Queensland’s X2 facility. These experiments were aimed at measuring the level of radiation encountered during conditions relevant to Orion lunar return into Earth’s atmosphere. The facilities have targeted the same nominal test conditions of 10 km/s and 26.6 Pa (0.2 Torr). In addition, variations on the nominal shock speed have also been the focus of recent testing in the EAST facility. A comprehensive comparison between the EAST data and NEQAIR is presented in this paper with preliminary X2 comparisons where appropriate. Since the two facilities have different dimensions, and the tests have different shock speeds, NEQAIR simulations are used as a point of reference for the EAST and X2 comparison. Results obtained by independently reducing the data from both facilities are compared. The present analysis endeavors to provide a better understanding of the uncertainty in the measurements, as well as provide an initial comparison between EAST and X2. Furthermore, the present analysis explores various radiative mechanisms to determine if they are due to physical processes relevant to flight, or are just facility dependent phenomena. These phenomena include effects such as the magnitude of the background continuum

Analysis of air radiation measurements obtained in the EAST and X2 shocktube facilities

This paper presents measurements of equilibrium radiation obtained in the NASA Ames Research Center’s EAST facility and the University of Queensland’s X2 facility. These experiments were aimed at measuring the level of radiation encountered during conditions relevant to Orion lunar return into Earth’s atmosphere. The facilities have targeted the same nominal test conditions of 10 km/s and 26.6 Pa (0.2 Torr). In addition, variations on the nominal shock speed have also been the focus of recent testing in the EAST facility. A comprehensive comparison between the EAST data and NEQAIR is presented in this paper with preliminary X2 comparisons where appropriate. Since the two facilities have different dimensions, and the tests have different shock speeds, NEQAIR simulations are used as a point of reference for the EAST and X2 comparison. Results obtained by independently reducing the data from both facilities are compared. The present analysis endeavors to provide a better understanding of the uncertainty in the measurements, as well as provide an initial comparison between EAST and X2. Furthermore, the present analysis explores various radiative mechanisms to determine if they are due to physical processes relevant to flight, or are just facility dependent phenomena. These phenomena include effects such as the magnitude of the background continuum

Analysis of air radiation measurements obtained in the EAST and X2 shocktube facilities

This paper presents measurements of equilibrium radiation obtained in the NASA Ames Research Center's EAST facility and the University of Queensland's X2 facility. These experiments were aimed at measuring the level of radiation encountered during conditions relevant to Orion lunar return into Earth's atmosphere. The facilities have targeted the same nominal test conditions of 10 km/s and 26.6 Pa (0.2 Torr). In addition, variations on the nominal shock speed have also been the focus of recent testing in the EAST facility. A comprehensive comparison between the EAST data and NEQAIR is presented in this paper with preliminary X2 comparisons where appropriate. Since the two facilities have different dimensions, and the tests have different shock speeds, NEQAIR simulations are used as a point of reference for the EAST and X2 comparison. Results obtained by independently reducing the data from both facilities are compared. The present analysis endeavors to provide a better understanding of the uncertainty in the measurements, as well as provide an initial comparison between EAST and X2. Furthermore, the present analysis explores various radiative mechanisms to determine if they are due to physical processes relevant to flight, or are just facility dependent phenomena. These phenomena include effects such as the magnitude of the background continuum. © 2010 by the American Institute of Aeronautics and Astronautics, Inc

Magnitude and frequency relations: are there geological constraints to the rockfall size?

There exists a transition between rockfalls, large rock mass failures, and rock avalanches. The magnitude and frequency relations (M/F) of the slope failure are increasingly used to assess the hazard level. The management of the rockfall risk requires the knowledge of the frequency of the events but also defining the worst case scenario, which is the one associated to the maximum expected (credible) rockfall event. The analysis of the volume distribution of the historical rockfall events in the slopes of the Solà d’Andorra during the last 50 years shows that they can be fitted to a power law. We argue that the extrapolation of the F-M relations far beyond the historical data is not appropriate in this case. Neither geomorphological evidences of past events nor the size of the potentially unstable rock masses identified in the slope support the occurrence of the large rockfall/rock avalanche volumes predicted by the power law. We have observed that the stability of the slope at the Solà is controlled by the presence of two sets of unfavorably dipping joints (F3, F5) that act as basal sliding planes of the detachable rock masses. The area of the basal sliding planes outcropping at the rockfall scars was measured with a terrestrial laser scanner. The distribution of the areas of the basal planes may be also fitted to a power law that shows a truncation for values bigger than 50 m2 and a maximum exposed surface of 200 m2. The analysis of the geological structure of the rock mass at the Solà d’Andorra makes us conclude that the size of the failures is controlled by the fracture pattern and that the maximum size of the failure is constrained. Two sets of steeply dipping faults (F1 and F7) interrupt the other joint sets and prevent the formation of continuous failure surfaces (F3 and F5). We conclude that due to the structural control, large slope failures in Andorra are not randomly distributed thus confirming the findings in other mountain range