10,926 research outputs found
Thermionic diode switching has high temperature application
Thermionic converter switch permits chopping in the immediate vicinity of a low-voltage, high current power source, eliminating line losses due to temperature limitations of semiconductor devices
Thermionic diode switch Patent
Thermionic diode switch for use in high temperature region to chop current from dc sourc
Sintering and properties of Si3N4 with and without additives by HIP treatment
Hot Isostatic Pressing (HIP) of Si3N4 powders with and without additives was performed using a glass container, and various kinds of pressureless-sintered Si3N4 were HIP'ed without a container. The effects of HIP treatment on density, microstructure, flexural strength, microhardness, and fracture toughness on Si3N4 ceramics were studied. Using a glass container it was difficult to reach theoretical density. The microhardness of HIP'ed Si3N4 without additives was low, and the fracture toughness of HIP'ed Si3N4 with and without additives was 22 to 25 W/m-K, and it decreased with increasing the amount of additives. The density and flexural strength, and hardness of pressureless-sintered Si3N4 which contained Al2O and Y2O3 as oxide additives were remarkably improved by HIP treatment using nitrogen as a pressure transmitting gas. It is very important to select the sintering conditions for fabricating the presintered body of Si3N4 in order to improve the mechanical properties of Si3N4 by HIP treatment
Gate-induced blueshift and quenching of photoluminescence in suspended single-walled carbon nanotubes
Gate-voltage effects on photoluminescence spectra of suspended single-walled
carbon nanotubes are investigated. Photoluminescence microscopy and excitation
spectroscopy are used to identify individual nanotubes and to determine their
chiralities. Under an application of gate voltage, we observe slight blueshifts
in the emission energy and strong quenching of photoluminescence. The
blueshifts are similar for different chiralities investigated, suggesting
extrinsic mechanisms. In addition, we find that the photoluminescence intensity
quenches exponentially with gate voltage.Comment: 4 pages, 4 figure
Exciton diffusion in air-suspended single-walled carbon nanotubes
Direct measurements of the diffusion length of excitons in air-suspended
single-walled carbon nanotubes are reported. Photoluminescence microscopy is
used to identify individual nanotubes and to determine their lengths and chiral
indices. Exciton diffusion length is obtained by comparing the dependence of
photoluminescence intensity on the nanotube length to numerical solutions of
diffusion equations. We find that the diffusion length in these clean, as-grown
nanotubes is significantly longer than those reported for micelle-encapsulated
nanotubes.Comment: 4 pages, 4 figure
Electro-Mechanical Simulation of Switching Characteristics for Nanoelectromechanical Memory
The static switching properties and readout characteristics of proposed high-speed and nonvolatile nanoelectromechanical (NEM) memory devices are investigated By conducting a three-dimensional finite element mechanical simulation combined with an electrostatic analysis, we analyze the electromechanical switching operation of a mechanically bistable NEM floating gate by applying gate voltage. We show that switching voltage can be reduced to less than 10V by reducing the zero-bias displacement of the floating gate and optimizing the cavity structure to improve mechanical symmetry. We also analyze the electrical readout property of the NEM memory devices by combining the electromechanical simulation with a drift-diffusion analysis We demonstrate that the mechanically bistable states of the floating gate can be detected via the changes in drain current with an ON/OFF current ratio of about 3 x 10 (C) 2009 The Japan Society of Applied Physic
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