6,610 research outputs found
Real-time simulation of finite frequency noise from a single electron emitter
We study the real-time emission of single electrons from a quantum dot
coupled to a one dimensional conductor, using exact diagonalization on a
discrete tight-binding chain. We show that from the calculation of the
time-evolution of the one electron states, we have a simple access to all the
relevant physical quantities in the system. In particular, we are able to
compute accurately the finite frequency current autocorrelation noise. The
method which we use is general and versatile, allowing to study the impact of
many different parameters like the dot transparency or level position. Our
results can be directly compared with existing experiments, and can also serve
as a basis for future calculations including electronic interactions using the
time dependent density-matrix renormalisation group and other techniques based
on tight-binding models.Comment: 10 page
Bounds for the discrete correlation of infinite sequences on k symbols and generalized Rudin-Shapiro sequences
Motivated by the known autocorrelation properties of the Rudin-Shapiro
sequence, we study the discrete correlation among infinite sequences over a
finite alphabet, where we just take into account whether two symbols are
identical. We show by combinatorial means that sequences cannot be "too"
different, and by an explicit construction generalizing the Rudin-Shapiro
sequence, we show that we can achieve the maximum possible difference.Comment: Improved Introduction and new Section 6 (Lovasz local lemma
Space shuttle orbiter environmental control and life support systems
Environmental control and life support system for space shuttle orbite
A Nonparametric Solution for Finding the Optimum Useful Life of Equipment
It is often the case that equipment used by industry must be replaced with new equipment from time to time either because frequent malfunctions make it too costly to repair, or because the equipment has simply worn out. The new equipment often has the nature of either malfunctioning soon after installation due to manufacturing defects, or functioning for an extended period of time because it is free of these defects. For this reason, equipment is often given a preliminary running called the burn-in which gives no useful output but merely tests for manufacturing defects. Also, after a given amount of time, equipment is often replaced so as to avoid the added cost of a breakdown while under use. The term useful life is here used to denote the time period starting after burn-in time is reached and ending when replacement time is reached (Shooman, 1968)
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