6,848 research outputs found
A convenient implementation of the overlap between arbitrary Hartree-Fock-Bogoliubov vacua for projection
Overlap between Hartree-Fock-Bogoliubov(HFB) vacua is very important in the
beyond mean-field calculations. However, in the HFB transformation, the
matrices are sometimes singular due to the exact emptiness () or full
occupation () of some single-particle orbits. This singularity may cause
some problem in evaluating the overlap between HFB vacua through Pfaffian. We
found that this problem can be well avoided by setting those zero occupation
numbers to some tiny values (e.g., ). This treatment does not
change the HFB vacuum state because are numerically zero
relative to 1. Therefore, for arbitrary HFB transformation, we say that the
matrices can always be nonsingular. From this standpoint, we present a
new convenient Pfaffian formula for the overlap between arbitrary HFB vacua,
which is especially suitable for symmetry restoration. Testing calculations
have been performed for this new formula. It turns out that our method is
reliable and accurate in evaluating the overlap between arbitrary HFB vacua.Comment: 5 pages, 2 figures. Published versio
Enabling Work-conserving Bandwidth Guarantees for Multi-tenant Datacenters via Dynamic Tenant-Queue Binding
Today's cloud networks are shared among many tenants. Bandwidth guarantees
and work conservation are two key properties to ensure predictable performance
for tenant applications and high network utilization for providers. Despite
significant efforts, very little prior work can really achieve both properties
simultaneously even some of them claimed so.
In this paper, we present QShare, an in-network based solution to achieve
bandwidth guarantees and work conservation simultaneously. QShare leverages
weighted fair queuing on commodity switches to slice network bandwidth for
tenants, and solves the challenge of queue scarcity through balanced tenant
placement and dynamic tenant-queue binding. QShare is readily implementable
with existing switching chips. We have implemented a QShare prototype and
evaluated it via both testbed experiments and simulations. Our results show
that QShare ensures bandwidth guarantees while driving network utilization to
over 91% even under unpredictable traffic demands.Comment: The initial work is published in IEEE INFOCOM 201
Relationship between Crude Oil Prices and Stock Prices of Alternative Energy Companies with Recent Evidence
This paper examines the recent interactive relationships between crude oil prices and stock performances of alternative energy companies. Oil prices and stock index of alternative energy sector are found independent from each other before late 2006. Contrary to existing studies, however, we find significant interdependence between oil prices and stock index of alternative energy industry in the recent years. Since late 2006, oil prices become significantly responsible for the stock performances of alternative energy companies. This finding suggests that the stock market investors of alternative energy sector incorporate oil price shocks into their trading decisions only recently.Crude oil price; Alternative energy; Oil stock index
High Quality, Transferable Graphene Grown on Single Crystal Cu(111) Thin Films on Basal-Plane Sapphire
The current method of growing large-area graphene on Cu surfaces
(polycrystalline foils and thin films) and its transfer to arbitrary substrates
is technologically attractive. However, the quality of graphene can be improved
significantly by growing it on single-crystal Cu surfaces. Here we show that
high quality, large-area graphene can be grown on epitaxial single-crystal
Cu(111) thin films on reusable basal-plane sapphire (alpha-Al2O3(0001))
substrates and then transferred to another substrate. While enabling graphene
growth on Cu single-crystal surfaces, this method has the potential to avoid
the high cost and extensive damage to graphene associated with sacrificing bulk
single-crystal Cu during graphene transfer.Comment: 10 pages, 3 figure
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