1,993 research outputs found
Hot Zero and Full Power Validation of PHISICS RELAP-5 Coupling
PHISICS is a reactor analysis toolkit developed over
the last 3 years at the Idaho National Laboratory. It has
been coupled with the reactor safety analysis code
RELAP5-3D. PHISICS is aimed at providing an optimal
trade off between needed computational resources (in the
range of 10~100 computer processors) and accuracy. In
fact, this range has been identified as the next 5 to 10
years average computational capability available to
nuclear reactor design and optimization nuclear reactor
cores.
Detailed information about the individual modules of
PHISICS can be found in [1]. An overview of the
modules used in this study is given in the next subsection.
Lately, the Idaho National Laboratory gained access plant
data for the first cycle of a PWR, including Hot Zero
Power (HZP) and Hot Full Power (HFP).
This data provides the opportunity to validate the
transport solver, the interpolation capability for mixed
macro and micro cross section and the criticality search
option of the PHISICS pack
QED correction for H
A quantum electrodynamics (QED) correction surface for the simplest
polyatomic and polyelectronic system H is computed using an approximate
procedure. This surface is used to calculate the shifts to vibration-rotation
energy levels due to QED; such shifts have a magnitude of up to 0.25 cm
for vibrational levels up to 15~000 cm and are expected to have an
accuracy of about 0.02 cm. Combining the new H QED correction
surface with existing highly accurate Born-Oppenheimer (BO), relativistic and
adiabatic components suggests that deviations of the resulting {\it ab initio}
energy levels from observed ones are largely due to non-adiabatic effects
Avaliação de genótipos de milho no municÃpio de Brasiléia-Acre.
A cultura do milho no municÃpio de Brasiléia, assume significa tiva relevância sócio-econômica, contribuindo com 20,65% na produção global do Estado (CEPA/1988). Além de ser utilizado na alimentação humana e ração animal, o excedente da produção tem sido comercializado no mercado local, em Rio Branco e Cobija, cidade frobteiriça (Bolivia). A cultura apresenta problemas diversos: cultivares pouco produtivas, cultivo em consorcio, grandes espaçamentos entre plantas, cultivares de grande porte, Ãndices elevados de acamamento, doenças, ocorrência de baixa produtividade. Estes problemas têm constituÃdo em fatores limitantes a oferta de milho ao mercado, além de resultar no baixo retorno econômico da pequena produção. Com o objetivo de selecionar cultivares mais produtivas e resistentes aos principais problemas da região, a UEPAE de Rio Branco vem desenvolvendo trabalhos no Núcleo de Pesquisa -Quixadá, localizado em Brasiléia.bitstream/item/117388/1/1158.pd
ExoMol molecular line lists XXX: a complete high-accuracy line list for water
A new line list for HO is presented. This line list, which is
called POKAZATEL, includes transitions between rotation-vibrational energy
levels up to 41000 cm in energy and is the most complete to date. The
potential energy surface (PES) used for producing the line list was obtained by
fitting a high-quality ab initio PES to experimental energy levels with
energies of 41000 cm and for rotational excitations up to . The
final line list comprises all energy levels up to 41000 cm and
rotational angular momentum up to 72. An accurate ab initio dipole moment
surface (DMS) was used for the calculation of line intensities and reproduces
high-precision experimental intensity data with an accuracy close to 1 %. The
final line list uses empirical energy levels whenever they are available, to
ensure that line positions are reproduced as accurately as possible. The
POKAZATEL line list contains over 5 billion transitions and is available from
the ExoMol website (www.exomol.com) and the CDS database
High accuracy CO line intensities determined from theory and experiment
Atmospheric CO concentrations are being closely monitored by remote
sensing experiments which rely on knowing line intensities with an uncertainty
of 0.5\%\ or better. Most available laboratory measurements have uncertainties
much larger than this. We report a joint experimental and theoretical study
providing rotation-vibration line intensities with the required accuracy. The
{\it ab initio} calculations are extendible to all atmospherically important
bands of CO and to its isotologues. As such they will form the basis for
detailed CO spectroscopic line lists for future studies.Comment: 5 pages, 2 figures, 1 tabl
Analyzing synchronized clusters in neuron networks
The presence of synchronized clusters in neuron networks is a hallmark of information transmission and processing. Common approaches to study cluster synchronization in networks of coupled oscillators ground on simplifying assumptions, which often neglect key biological features of neuron networks. Here we propose a general framework to study presence and stability of synchronous clusters in more realistic models of neuron networks, characterized by the presence of delays, different kinds of neurons and synapses. Application of this framework to two examples with different size and features (the directed network of the macaque cerebral cortex and the swim central pattern generator of a mollusc) provides an interpretation key to explain known functional mechanisms emerging from the combination of anatomy and neuron dynamics. The cluster synchronization analysis is carried out also by changing parameters and studying bifurcations. Despite some modeling simplifications in one of the examples, the obtained results are in good agreement with previously reported biological data
Design and implementation of a modular interior-point solver for linear optimization
This paper introduces the algorithmic design and implementation of Tulip, an
open-source interior-point solver for linear optimization. It implements a
regularized homogeneous interior-point algorithm with multiple centrality
corrections, and therefore handles unbounded and infeasible problems. The
solver is written in Julia, thus allowing for a flexible and efficient
implementation: Tulip's algorithmic framework is fully disentangled from linear
algebra implementations and from a model's arithmetic. In particular, this
allows to seamlessly integrate specialized routines for structured problems.
Extensive computational results are reported. We find that Tulip is competitive
with open-source interior-point solvers on the H. Mittelmann's benchmark of
barrier linear programming solvers. Furthermore, we design specialized linear
algebra routines for structured master problems in the context of Dantzig-Wolfe
decomposition. These routines yield a tenfold speedup on large and dense
instances that arise in power systems operation and two-stage stochastic
programming, thereby outperforming state-of-the-art commercial interior point
method solvers. Finally, we illustrate Tulip's ability to use different levels
of arithmetic precision by solving problems in extended precision
A room temperature CO line list with ab initio computed intensities
Atmospheric carbon dioxide concentrations are being closely monitored by
remote sensing experiments which rely on knowing line intensities with an
uncertainty of 0.5% or better. We report a theoretical study providing
rotation-vibration line intensities substantially within the required accuracy
based on the use of a highly accurate {\it ab initio} dipole moment surface
(DMS). The theoretical model developed is used to compute CO intensities
with uncertainty estimates informed by cross comparing line lists calculated
using pairs of potential energy surfaces (PES) and DMS's of similar high
quality. This yields lines sensitivities which are utilized in reliability
analysis of our results. The final outcome is compared to recent accurate
measurements as well as the HITRAN2012 database. Transition frequencies are
obtained from effective Hamiltonian calculations to produce a comprehensive
line list covering all CO transitions below 8000 cm
and stronger than 10 cm / molecule at ~
Order Picking Systems: A Queue Model for Dimensioning the Storage Capacity, the Crew of Pickers, and the AGV Fleet
Designing an order picking system can be very complex, as several interrelated control variables are involved. We address the sizing of the storage capacity of the picking bay, the crew of pickers, and the AGV fleet, which are the most important variables from a tactical viewpoint in a parts-to-pickers system. Although order picking is a widely explored topic in the literature, no analytical model that can simultaneously deal with these variables is currently available. To bridge this gap, we introduce a queue model for Markovian processes, which enables us to jointly optimise the aforementioned control variables. A discrete-event simulation is then used to validate our model, and we then test our proposal with real data under different operative scenarios, with the aim of assessing the usefulness of the proposal in real settings
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