24,516 research outputs found
Characterization of quantum well structures using a photocathode electron microscope
Present day integrated circuits pose a challenge to conventional electronic and mechanical test methods. Feature sizes in the submicron and nanometric regime require radical approaches in order to facilitate electrical contact to circuits and devices being tested. In addition, microwave operating frequencies require careful attention to distributed effects when considering the electrical signal paths within and external to the device under test. An alternative testing approach which combines the best of electrical and optical time domain testing is presented, namely photocathode electron microscope quantitative voltage contrast (PEMQVC)
Start-Up Costs in American Research Universities
Our report briefly summarizes findings from the 2002 Cornell Higher Education Research Institute survey of start-up costs at the over 220 universities classified as Research and Doctoral universities by the Carnegie Foundation in 1994. It reports the mean start-up cost packages across institutions for new assistant professors and senior faculty, broken down by institutional type (public/private), Carnegie classification and field (biology, chemistry, engineering, physics and astronomy) and also discuses the sources of funding for start-up costs
Learning Price-Elasticity of Smart Consumers in Power Distribution Systems
Demand Response is an emerging technology which will transform the power grid
of tomorrow. It is revolutionary, not only because it will enable peak load
shaving and will add resources to manage large distribution systems, but mainly
because it will tap into an almost unexplored and extremely powerful pool of
resources comprised of many small individual consumers on distribution grids.
However, to utilize these resources effectively, the methods used to engage
these resources must yield accurate and reliable control. A diversity of
methods have been proposed to engage these new resources. As opposed to direct
load control, many methods rely on consumers and/or loads responding to
exogenous signals, typically in the form of energy pricing, originating from
the utility or system operator. Here, we propose an open loop
communication-lite method for estimating the price elasticity of many customers
comprising a distribution system. We utilize a sparse linear regression method
that relies on operator-controlled, inhomogeneous minor price variations, which
will be fair to all the consumers. Our numerical experiments show that reliable
estimation of individual and thus aggregated instantaneous elasticities is
possible. We describe the limits of the reliable reconstruction as functions of
the three key parameters of the system: (i) ratio of the number of
communication slots (time units) per number of engaged consumers; (ii) level of
sparsity (in consumer response); and (iii) signal-to-noise ratio.Comment: 6 pages, 5 figures, IEEE SmartGridComm 201
Forming the Dusty Ring in HR 4796A
We describe planetesimal accretion calculations for the dusty ring observed
in the nearby A0 star HR 4796A. Models with initial masses of 10-20 times the
minimum mass solar nebula produce a ring of width 7-15 AU and height 0.3-0.6 AU
at 70 AU in roughly 10 Myr. The ring has a radial optical depth of 1. These
results agree with limits derived from infrared images and from the excess
infrared luminosity.Comment: 6 pages, including 2 figures and 1 table; ApJ Letters, in pres
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