2,955 research outputs found
Feasibility of Municipal Water Mains as Heat Sink for Residential Air-Conditioning
It has been proposed that municipal
water mains be used as the heat sink or the heat
source for air-conditioning or heating,
respectively. This paper addresses the extent of
thermal contamination associated with the use
of municipal water in the mains for heat
rejection in residential air-conditioning
applications. A small residential neighborhood
in Austin, Texas was selected, and typical
residential a/c loads and measured water
supply rates in the main were used in the
assessment.
Very substantial increases in water
temperature occur in the mains for air-conditioning,
even if a modest fraction of the
residents opt to install such systems. No more
than 1 to 2 % of residents could adopt such
systems before water temperature rises in the
mains become significant. The general conclusion
is that, while the benefit to an individual using
this concept may be positive, the impact on
water temperature is excessive
Analytical and experimental study of stratification and liquid-ullage coupling, 1 June 1964 - 31 May 1965
Closed-form solution for stratification of subcooled fluids in containers subjected to heating, and for liquid-ullage vapor couplin
Microscopic energy flows in disordered Ising spin systems
An efficient microcanonical dynamics has been recently introduced for Ising
spin models embedded in a generic connected graph even in the presence of
disorder i.e. with the spin couplings chosen from a random distribution. Such a
dynamics allows a coherent definition of local temperatures also when open
boundaries are coupled to thermostats, imposing an energy flow. Within this
framework, here we introduce a consistent definition for local energy currents
and we study their dependence on the disorder. In the linear response regime,
when the global gradient between thermostats is small, we also define local
conductivities following a Fourier dicretized picture. Then, we work out a
linearized "mean-field approximation", where local conductivities are supposed
to depend on local couplings and temperatures only. We compare the approximated
currents with the exact results of the nonlinear system, showing the
reliability range of the mean-field approach, which proves very good at high
temperatures and not so efficient in the critical region. In the numerical
studies we focus on the disordered cylinder but our results could be extended
to an arbitrary, disordered spin model on a generic discrete structures.Comment: 12 pages, 6 figure
Shot Noise in Linear Macroscopic Resistors
We report on a direct experimental evidence of shot noise in a linear
macroscopic resistor. The origin of the shot noise comes from the fluctuation
of the total number of charge carriers inside the resistor associated with
their diffusive motion under the condition that the dielectric relaxation time
becomes longer than the dynamic transit time. Present results show that neither
potential barriers nor the absence of inelastic scattering are necessary to
observe shot noise in electronic devices.Comment: 10 pages, 5 figure
ADAMTS-13 and Von Willebrand factor in relation to platelet response during plasma exchange in thrombotic thrombocytopenic purpura: a clue for disease mechanism?
A Comparison of Domestic Water Heating Options in the Austin Electric Service Area
This report examines the energy, demand, and
economic effects of three alternative electric
water heating systems from the perspective of both
the City of Austin Electric Utility and its
ratepayers. An hourly computer simulation was
used to model the operation of (1) a conventional
electric resistance water heater (ERWH), (2) a
heat pump water heater (HPWH), and (3) a heat
recovery water heater (HRWH). Data from a
previously conducted field test of solar water
heaters (SWH) in the Austin area was used to
compare this fourth water heating option. In the
base case, the SWH was found to save the most
energy relative to a conventional ERWH followed by
the HPWH and the HRWH, respectively. However,
under most economic assumptions thought to be
reasonable for the Austin area, the heat recovery
water heater appeared to be the best choice for
the Austin all-electric ratepayer. From the
Utility's perspective, it was determined that: (1)
widespread ratepayer use of heat recovery water
heater systems would be beneficial to the Utility;
(2) ratepayer use of solar water heater systems
would be marginally beneficial to the Utility; and
(3) ratepayer use of heat pump water heater
systems would not be beneficial to the Utility
The Relation Between Galaxy ISM and Circumgalactic OVI Gas Kinematics Derived from Observations and CDM Simulations
We present the first galaxy-OVI absorption kinematic study for 20 absorption
systems (EW>0.1~{\AA}) associated with isolated galaxies (0.150.55) that
have accurate redshifts and rotation curves obtained using Keck/ESI. Our sample
is split into two azimuthal angle bins: major axis () and
minor axis (). OVI absorption along the galaxy major axis is
not correlated with galaxy rotation kinematics, with only 1/10 systems that
could be explained with rotation/accretion models. This is in contrast to
co-rotation commonly observed for MgII absorption. OVI along the minor axis
could be modeled by accelerating outflows but only for small opening angles,
while the majority of the OVI is decelerating. Along both axes, stacked OVI
profiles reside at the galaxy systemic velocity with the absorption kinematics
spanning the entire dynamical range of their galaxies. The OVI found in AMR
cosmological simulations exists within filaments and in halos of ~50 kpc
surrounding galaxies. Simulations show that major axis OVI gas inflows along
filaments and decelerates as it approaches the galaxy while increasing in its
level of co-rotation. Minor axis outflows in the simulations are effective
within 50-75 kpc beyond that they decelerate and fall back onto the galaxy.
Although the simulations show clear OVI kinematic signatures they are not
directly comparable to observations. When we compare kinematic signatures
integrated through the entire simulated galaxy halo we find that these
signatures are washed out due to full velocity distribution of OVI throughout
the halo. We conclude that OVI alone does not serve as a useful kinematic
indicator of gas accretion, outflows or star-formation and likely best probes
the halo virial temperature.Comment: 24 pages, 21 figures, 4 tables. Accepted to ApJ on November 14, 201
Classical simulation of measurement-based quantum computation on higher-genus surface-code states
We consider the efficiency of classically simulating measurement-based
quantum computation on surface-code states. We devise a method for calculating
the elements of the probability distribution for the classical output of the
quantum computation. The operational cost of this method is polynomial in the
size of the surface-code state, but in the worst case scales as in the
genus of the surface embedding the code. However, there are states in the
code space for which the simulation becomes efficient. In general, the
simulation cost is exponential in the entanglement contained in a certain
effective state, capturing the encoded state, the encoding and the local
post-measurement states. The same efficiencies hold, with additional
assumptions on the temporal order of measurements and on the tessellations of
the code surfaces, for the harder task of sampling from the distribution of the
computational output.Comment: 21 pages, 13 figure
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