5,874 research outputs found
Derivative Formula and Applications for Degenerate Diffusion Semigroups
By using the Malliavin calculus and solving a control problem, Bismut type
derivative formulae are established for a class of degenerate diffusion
semigroups with non-linear drifts. As applications, explicit gradient estimates
and Harnack inequalities are derived.Comment: 18 page
Sense, Model and Identify the Load Signatures of HVAC Systems in Metro Stations
The HVAC systems in subway stations are energy consuming giants, each of
which may consume over 10, 000 Kilowatts per day for cooling and ventilation.
To save energy for the HVAC systems, it is critically important to firstly know
the "load signatures" of the HVAC system, i.e., the quantity of heat imported
from the outdoor environments and by the passengers respectively in different
periods of a day, which will significantly benefit the design of control
policies. In this paper, we present a novel sensing and learning approach to
identify the load signature of the HVAC system in the subway stations. In
particular, sensors and smart meters were deployed to monitor the indoor,
outdoor temperatures, and the energy consumptions of the HVAC system in
real-time. The number of passengers was counted by the ticket checking system.
At the same time, the cooling supply provided by the HVAC system was inferred
via the energy consumption logs of the HVAC system. Since the indoor
temperature variations are driven by the difference of the loads and the
cooling supply, linear regression model was proposed for the load signature,
whose coefficients are derived via a proposed algorithm . We collected real
sensing data and energy log data from HaiDianHuangZhuang Subway station, which
is in line 4 of Beijing from the duration of July 2012 to Sept. 2012. The data
was used to evaluate the coefficients of the regression model. The experiment
results show typical variation signatures of the loads from the passengers and
from the outdoor environments respectively, which provide important contexts
for smart control policies.Comment: 5 pages, 5 figure
Algorithms to test open set condition for self-similar set related to P.V. numbers
Fix a P.V. number Given
,
\mathbf{b}=(b_{1},\cdots,b_{m})\in \mathbb{Q^{m}, for the self-similar set
we find an efficient algorithm to
test whether satisfies the open set condition
(strong separation condition) or not
Primordial Black Holes from Sound Speed Resonance during Inflation
We report on a novel phenomenon of the resonance effect of primordial density
perturbations arisen from a sound speed parameter with an oscillatory behavior,
which can generically lead to the formation of primordial black holes in the
early Universe. For a general inflaton field, it can seed primordial density
fluctuations and their propagation is governed by a parameter of sound speed
square. Once if this parameter achieves an oscillatory feature for a while
during inflation, a significant non-perturbative resonance effect on the
inflaton field fluctuations takes place around a critical length scale, which
results in significant peaks in the primordial power spectrum. By virtue of
this robust mechanism, primordial black holes with specific mass function can
be produced with a sufficient abundance for dark matter in sizable parameter
ranges.Comment: 6 pages, 4 figures; v2: figures replotted with corrections, analysis
extended, version accepted by Phys.Rev.Let
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