15,390 research outputs found
A Memristor Model with Piecewise Window Function
In this paper, we present a memristor model with piecewise window function, which is continuously differentiable and consists of three nonlinear pieces. By introducing two parameters, the shape of this window function can be flexibly adjusted to model different types of memristors. Using this model, one can easily obtain an expression of memristance depending on charge, from which the numerical value of memristance can be readily calculated for any given charge, and eliminate the error occurring in the simulation of some existing window function models
Early-stage star forming cloud cores in GLIMPSE Extended Green Objects (EGOs) as traced by organic species
In order to investigate the physical and chemical properties of massive star
forming cores in early stages, we analyse the excitation and abundance of four
organic species, CH3OH, CH3OCH3, HCOOCH3 and CH3CH2CN, toward 29 Extended Green
Object (EGO) cloud cores that were observed by our previous single dish
spectral line survey. The EGO cloud cores are found to have similar methanol
J_3-J_2 rotation temperatures of ~44 K, a typical linear size of ~0.036 pc, and
a typical beam averaged methanol abundance of several 10^(-9) (the beam
corrected value could reach several 10^(-7)). The abundances of the latter
three species, normalized by that of methanol, are found to be correlated also
across a large variety of clouds such as EGO cloud cores, hot corinos, massive
hot cores and Galactic Center clouds. The chemical properties of the EGO cloud
cores lie between that of hot cores and hot corinos. However, the abundances
and abundance ratios of the four species can not be satisfactorily explained by
recent chemical models either among the EGO cloud cores or among the various
types of cloud cores from literature
Use of Devolved Controllers in Data Center Networks
In a data center network, for example, it is quite often to use controllers
to manage resources in a centralized man- ner. Centralized control, however,
imposes a scalability problem. In this paper, we investigate the use of
multiple independent controllers instead of a single omniscient controller to
manage resources. Each controller looks after a portion of the network only,
but they together cover the whole network. This therefore solves the
scalability problem. We use flow allocation as an example to see how this
approach can manage the bandwidth use in a distributed manner. The focus is on
how to assign components of a network to the controllers so that (1) each
controller only need to look after a small part of the network but (2) there is
at least one controller that can answer any request. We outline a way to
configure the controllers to fulfill these requirements as a proof that the use
of devolved controllers is possible. We also discuss several issues related to
such implementation.Comment: Appears in INFOCOM 2011 Cloud Computing Worksho
Preliminary study of microtektites first discovered in the central Pacific by China
Electron probe analysis was used to determine the chemical composition of microtektites discovered in the Central Pacific. An X-ray energy spectrum analysis was made, and the surface microstructure was investigated. The found microtektites appear to be younger than the microtektites reported in the Asia Australia Strewn Field
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