7,616 research outputs found
Polygamy relations of multipartite systems
We investigate the polygamy relations of multipartite quantum states. General
polygamy inequalities are given in the th power of
concurrence of assistance, th power of entanglement of
assistance, and the squared convex-roof extended negativity of assistance
(SCRENoA)
Low-voltage distribution network reconfiguration considering high penetration of electric vehicles:a UK case study
Network reconfiguration is one of the electricity network optimization techniques for losses reduction and load balancing by changing the open-closed status of sectionalized switches. In this paper, an application of network reconfiguration in low-voltage (LV) domestic distribution network with high penetration of electric vehicles (EVs) is presented. Firstly, high resolution time-series domestic load profiles are generated and validated with measured data at substation. Electric vehicle charging profiles at both fast and slow charging modes are modelled and produced. Then the impact of increasing penetration of EVs on the network thermal and voltage constraints is quantified. To optimize the network topology, suitable locations of newly-installed switches and their operational time are identified by branch-exchange method and exhaustive search algorithm (ESA) due to the small size of network and less potential location. The proposed approach is applied to two practical 400V LV distribution networks interconnected by underground linkboxes which are used to provide back-feeds during routine maintenances or emergency conditions. By adding new sectionalized switches, the LV network will obtain more operational flexibility and could better explore its potential for further study under Smart Grid scenarios
Electric Vehicle charging management algorithm for a UK low-voltage residential distribution network
The integration of Electric Vehicles (EVs) into low-voltage (LV) residential distribution networks inevitably increases the overall demand, especially peak demand, which may cause thermal or voltage issues. In this paper, a 400V practical residential distribution network is modelled and used to quantify these impacts due to the growing penetration of EVs. Residential load profiles in 1-minute resolution and EV charging profiles with recorded State of Charge (SOC) are randomly and statistically created. Then, a simple charging management algorithm with locally made decision is suggested at EV users' charging points. Results prove that this approach can mitigate the negative impacts of EV charging on network assets. Moreover, it can reduce EV users' electricity cost for charging based on existing UK electricity price scheme 'Economy 7,' without compromising EV usage or substantial network infrastructure reinforcement or installation of extensive monitor, control and communication system. The simulation models and analysis are implemented in MATLAB/OpenDSS as an LV distribution network simulation platform
Mean dimension of product spaces: a fundamental formula
Mean dimension is a topological invariant of dynamical systems, which
originates with Mikhail Gromov in 1999 and which was studied with deep
applications around 2000 by Elon Lindenstrauss and Benjamin Weiss within the
framework of amenable group actions. Let a countable discrete amenable group
act continuously on compact metrizable spaces and . Consider the
product action of on the product space . The product inequality
for mean dimension is well known: , while it was unknown for a long
time if the product inequality could be an equality. In 2019, Masaki Tsukamoto
constructed the first example of two different continuous actions of on
compact metrizable spaces and , respectively, such that the product
inequality becomes strict. However, there is still one longstanding problem
which remains open in this direction, asking if there exists a continuous
action of on some compact metrizable space such that
. We solve this problem.
Somewhat surprisingly, we prove, in contrast to (topological) dimension theory,
a rather satisfactory theorem: If an infinite (countable discrete) amenable
group acts continuously on a compact metrizable space , then we have
, for any positive integer .
Our product formula for mean dimension, together with the example and
inequality (stated previously), eventually allows mean dimension of product
actions to be fully understood
The Hilbert cube contains a minimal subshift of full mean dimension
We construct a minimal dynamical system of mean dimension equal to , which
can be embedded in the shift action on the Hilbert cube . Our
result clarifies a seemingly plausible impression and finally enables us to
have a full understanding of (a pair of) the exact ranges of all possible
values of mean dimension, within which there will always be a minimal dynamical
system that can be (resp. cannot be) embedded in the shift action on the
Hilbert cube. The key ingredient of our idea is to produce a dense subset of
the alphabet "more gently"
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