United States Department of Energy

About: United States Department of Energy is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Catalysis & Coal. The organization has 13656 authors who have published 14177 publications receiving 556962 citations. The organization is also known as: DOE & Department of Energy.

Structure of the (√3 × √3 )R30° Ag/Si(111) surface from first-principles calculations

Abstract: The structure of (\ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 ) Ag/Si(111) is investigated using first-principles total-energy calculations. The lowest-energy configuration consists of a top layer of Ag atoms arranged as ``honeycomb chained trimers'' lying above a distorted ``missing top layer'' Si(111) substrate. We find that the honeycomb structure observed in scanning-tunneling-microscope images arises from the electronic charge density on an empty surface band near the Fermi level.

Fuel cell integrated with steam reformer

Abstract: A H 2 -air fuel cell integrated with a steam reformer is disclosed wherein a superheated water/methanol mixture is fed to a catalytic reformer to provide a continuous supply of hydrogen to the fuel cell, the gases exhausted from the anode of the fuel cell providing the thermal energy, via combustion, for superheating the water/methanol mixture.

A Combined Monte Carlo and Possibilistic Approach to Uncertainty Propagation in Event Tree Analysis

Abstract: In risk analysis, the treatment of the epistemic uncertainty associated to the probability of occurrence of an event is fundamental. Traditionally, probabilistic distributions have been used to characterize the epistemic uncertainty due to imprecise knowledge of the parameters in risk models. On the other hand, it has been argued that in certain instances such uncertainty may be best accounted for by fuzzy or possibilistic distributions. This seems the case in particular for parameters for which the information available is scarce and of qualitative nature. In practice, it is to be expected that a risk model contains some parameters affected by uncertainties that may be best represented by probability distributions and some other parameters that may be more properly described in terms of fuzzy or possibilistic distributions. In this article, a hybrid method that jointly propagates probabilistic and possibilistic uncertainties is considered and compared with pure probabilistic and pure fuzzy methods for uncertainty propagation. The analyses are carried out on a case study concerning the uncertainties in the probabilities of occurrence of accident sequences in an event tree analysis of a nuclear power plant.

Curie-point depth map of Turkey

Abstract: SUMMARY A Curie-point isotherm map of the whole of Turkey has been prepared from aeromagnetic data by means of a spectral analysis technique. The most characteristic signature of this map is that the shallow depths generally correlated with the young volcanic rocks and the thinned crustal thicknesses in the west reveal geothermal fields and several hot springs. The orogenic Pontide belt of the Black Sea region in the north, the western Taurus belt in the south, and some high plateaus in eastern Turkey show that the deepest Curie isotherm depths range between 20 and 29 km. Depth contour lines elongating in an almost E–W direction are due to the overlapping percentage of adjacent data blocks of 50 per cent in the E–W direction and to magnetic anomalies trending in the E–W direction. Curie isotherm depths are in the range 6 to 10 km in the Aegean region and are characterized by E–W- and NE–SW-trending graben structures, as expected, since the region has crustal thinning and many hot springs and geothermal fields. These imply the existence of shallow heat sources that could be utilized for electricity, heating of towns and cities, greenhouse and health purposes.