Electric propulsion using C.sub.60 molecules

Fullerene propellants, which are stable carbon cage structures composed of even numbers of carbon atoms in the range of about 32 to 200 atoms, particularly a combination of conveniently obtainable C.sub.60 and C.sub.70, may be carried in solid form in a spacecraft, sublimated to produce the appropriate molecular propellant such as C.sub.60 or C.sub.70, which may then be ionized by DC discharge or RF radiation to efficiently produce specific impulses in the range above 1000 lbf -s/lbm

Energy Efficient Servers

Computer scienc

Energy Efficient Servers: Blueprints for Data Center Optimization

Energy Efficient Servers: Blueprints for Data Center Optimization introduces engineers and IT professionals to the power management technologies and techniques used in energy efficient servers. The book includes a deep examination of different features used in processors, memory, interconnects, I/O devices, and other platform components. It outlines the power and performance impact of these features and the role firmware and software play in initialization and control. Using examples from cloud, HPC, and enterprise environments, the book demonstrates how various power management technologies are utilized across a range of server utilization. It teaches the reader how to monitor, analyze, and optimize their environment to best suit their needs. It shares optimization techniques used by data center administrators and system optimization experts at the world’s most advanced data centers

Nanometer-scale GaAs clusters from organometallic precursors

We report the synthesis of crystalline nanometer-scale GaAs clusters by homogeneous vapor-phase nucleation from organometallic precursors. Cluster synthesis is performed in a hot wall organometallic vapor-phase epitaxy reactor at atmospheric pressure. High resolution transmission electron microscopy studies reveal that the aerosol produced is composed of highly faceted single crystal GaAs particles in the 10–20 nm range. The influence of growth temperature and reactant concentration on cluster morphology is discussed

Vapor phase synthesis of crystalline nanometer-scale GaAs clusters

We report the synthesis of crystalline nanometer-scale GaAs clusters in the 5-10 nm size regime. The clusters are formed by the homogeneous nucleation of a nonequilibrium vapor created by the explosive vaporization of a bulk GaAs sample in an inert atmosphere. High resolution electron microscopy and diffraction show that the clusters have zincblende crystal structure and are faceted. Optical measurements on the particles are suggestive of quantum confinement effects

Energy Efficient Servers

Computer scienc

Synthesis of luminescent silicon clusters by spark ablation

The synthesis of luminescent nanometer-scale Si clusters by spark ablation from a crystalline Si substrate is described. The cluster source, described in the text, generates clusters in a flowing Ar stream at atmospheric pressure. Electron microscopy reveals that the clusters have diameters in the 2-4 nm size range. The luminescence spectra of the clusters, similar to that of porous Si, are presented

Resonance-enhanced spontaneous emission from quantum dots

Enhanced and inhibited spontaneous emission from a pointlike quantum dot embedded in a finite dielectric sphere are treated classically. Numerical results given for a GaAs quantum dot embedded in an Al0.4Ga0.6As sphere show the spontaneous emission rate is decreased by a factor of 80 when the radius of the sphere is small compared to the wavelength of emitted light. When the radius of the sphere is comparable to the wavelength, the spontaneous emission rate depends strongly on the radius. Sharp resonances, related to Mie resonances, with enhancements up to a factor of 100, are found in some cases