116 research outputs found
Permafrost hydrology in changing climatic conditions: seasonal variability of stable isotope composition in rivers in discontinuous permafrost
Role of changing climatic conditions on permafrost degradation and hydrology was investigated in the transition zone between the tundra and forest ecotones at the boundary of continuous and discontinuous permafrost of the lower Yenisei River. Three watersheds of various sizes were chosen to represent the characteristics of the regional landscape conditions. Samples of river flow, precipitation, snow cover, and permafrost ground ice were collected over the watersheds to determine isotopic composition of potential sources of water in a river flow over a two year period. Increases in air temperature over the last forty years have resulted in permafrost degradation and a decrease in the seasonal frost which is evident from soil temperature measurements, permafrost and active-layer monitoring, and analysis of satellite imagery. The lowering of the permafrost table has led to an increased storage capacity of permafrost affected soils and a higher contribution of ground water to river discharge during winter months. A progressive decrease in the thickness of the layer of seasonal freezing allows more water storage and pathways for water during the winter low period making winter discharge dependent on the timing and amount of late summer precipitation. There is a substantial seasonal variability of stable isotopic composition of river flow. Spring flooding corresponds to the isotopic composition of snow cover prior to the snowmelt. Isotopic composition of river flow during the summer period follows the variability of precipitation in smaller creeks, while the water flow of larger watersheds is influenced by the secondary evaporation of water temporarily stored in thermokarst lakes and bogs. Late summer precipitation determines the isotopic composition of texture ice within the active layer in tundra landscapes and the seasonal freezing layer in forested landscapes as well as the composition of the water flow during winter months
A supervised hybrid quantum machine learning solution to the emergency escape routing problem
Managing the response to natural disasters effectively can considerably
mitigate their devastating impact. This work explores the potential of using
supervised hybrid quantum machine learning to optimize emergency evacuation
plans for cars during natural disasters. The study focuses on earthquake
emergencies and models the problem as a dynamic computational graph where an
earthquake damages an area of a city. The residents seek to evacuate the city
by reaching the exit points where traffic congestion occurs. The situation is
modeled as a shortest-path problem on an uncertain and dynamically evolving
map. We propose a novel hybrid supervised learning approach and test it on
hypothetical situations on a concrete city graph. This approach uses a novel
quantum feature-wise linear modulation (FiLM) neural network parallel to a
classical FiLM network to imitate Dijkstra's node-wise shortest path algorithm
on a deterministic dynamic graph. Adding the quantum neural network in parallel
increases the overall model's expressivity by splitting the dataset's harmonic
and non-harmonic features between the quantum and classical components. The
hybrid supervised learning agent is trained on a dataset of Dijkstra's shortest
paths and can successfully learn the navigation task. The hybrid quantum
network improves over the purely classical supervised learning approach by 7%
in accuracy. We show that the quantum part has a significant contribution of
45.(3)% to the prediction and that the network could be executed on an
ion-based quantum computer. The results demonstrate the potential of supervised
hybrid quantum machine learning in improving emergency evacuation planning
during natural disasters.Comment: 15 pages, 9 figures, 2 table
Quantum algorithms applied to satellite mission planning for Earth observation
Earth imaging satellites are a crucial part of our everyday lives that enable
global tracking of industrial activities. Use cases span many applications,
from weather forecasting to digital maps, carbon footprint tracking, and
vegetation monitoring. However, there are also limitations; satellites are
difficult to manufacture, expensive to maintain, and tricky to launch into
orbit. Therefore, it is critical that satellites are employed efficiently. This
poses a challenge known as the satellite mission planning problem, which could
be computationally prohibitive to solve on large scales. However,
close-to-optimal algorithms can often provide satisfactory resolutions, such as
greedy reinforcement learning, and optimization algorithms. This paper
introduces a set of quantum algorithms to solve the mission planning problem
and demonstrate an advantage over the classical algorithms implemented thus
far. The problem is formulated as maximizing the number of high-priority tasks
completed on real datasets containing thousands of tasks and multiple
satellites. This work demonstrates that through solution-chaining and
clustering, optimization and machine learning algorithms offer the greatest
potential for optimal solutions. Most notably, this paper illustrates that a
hybridized quantum-enhanced reinforcement learning agent can achieve a
completion percentage of 98.5% over high-priority tasks, which is a significant
improvement over the baseline greedy methods with a completion rate of 63.6%.
The results presented in this work pave the way to quantum-enabled solutions in
the space industry and, more generally, future mission planning problems across
industries.Comment: 13 pages, 10 figues, 3 tables. Submitted to IEEE JSTAR
Pion, kaon, proton and anti-proton transverse momentum distributions from p+p and d+Au collisions at GeV
Identified mid-rapidity particle spectra of , , and
from 200 GeV p+p and d+Au collisions are reported. A
time-of-flight detector based on multi-gap resistive plate chamber technology
is used for particle identification. The particle-species dependence of the
Cronin effect is observed to be significantly smaller than that at lower
energies. The ratio of the nuclear modification factor () between
protons and charged hadrons () in the transverse momentum
range GeV/c is measured to be
(stat)(syst) in minimum-bias collisions and shows little
centrality dependence. The yield ratio of in minimum-bias d+Au
collisions is found to be a factor of 2 lower than that in Au+Au collisions,
indicating that the Cronin effect alone is not enough to account for the
relative baryon enhancement observed in heavy ion collisions at RHIC.Comment: 6 pages, 4 figures, 1 table. We extended the pion spectra from
transverse momentum 1.8 GeV/c to 3. GeV/
Demonstration of the temporal matter-wave Talbot effect for trapped matter waves
We demonstrate the temporal Talbot effect for trapped matter waves using
ultracold atoms in an optical lattice. We investigate the phase evolution of an
array of essentially non-interacting matter waves and observe matter-wave
collapse and revival in the form of a Talbot interference pattern. By using
long expansion times, we image momentum space with sub-recoil resolution,
allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure
Azimuthal anisotropy at RHIC: the first and fourth harmonics
We report the first observations of the first harmonic (directed flow, v_1),
and the fourth harmonic (v_4), in the azimuthal distribution of particles with
respect to the reaction plane in Au+Au collisions at the Relativistic Heavy Ion
Collider (RHIC). Both measurements were done taking advantage of the large
elliptic flow (v_2) generated at RHIC. From the correlation of v_2 with v_1 it
is determined that v_2 is positive, or {\it in-plane}. The integrated v_4 is
about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8)
harmonics upper limits on the magnitudes are reported.Comment: 6 pages with 3 figures, as accepted for Phys. Rev. Letters The data
tables are at
http://www.star.bnl.gov/central/publications/pubDetail.php?id=3
Mid-rapidity anti-proton to proton ratio from Au+Au collisions at GeV
We report results on the ratio of mid-rapidity anti-proton to proton yields
in Au+Au collisions at \rts = 130 GeV per nucleon pair as measured by the
STAR experiment at RHIC. Within the rapidity and transverse momentum range of
and 0.4 1.0 GeV/, the ratio is essentially independent of
either transverse momentum or rapidity, with an average of for minimum bias collisions. Within errors, no
strong centrality dependence is observed. The results indicate that at this
RHIC energy, although the -\pb pair production becomes important at
mid-rapidity, a significant excess of baryons over anti-baryons is still
present.Comment: 5 pages, 3 figures, accepted by Phys. Rev. Let
Transverse-momentum correlations on from mean- fluctuations in Au-Au collisions at 200 GeV
We present first measurements of the pseudorapidity and azimuth
bin-size dependence of event-wise mean transverse momentum
fluctuations for Au-Au collisions at GeV. We invert that
dependence to obtain autocorrelations on differences
interpreted to represent velocity/temperature
distributions on (). The general form of the autocorrelations
suggests that the basic correlation mechanism is parton fragmentation. The
autocorrelations vary strongly with collision centrality, which suggests that
fragmentation is strongly modified by a dissipative medium in the more central
Au-Au collisions relative to peripheral or p-p collisions. \\Comment: 7 pages, 3 figure
DEVELOPMENT AND APPROVEMENT OF ISOTOPE INDICATION METHODS AT STUDY OF CON TAMINATING UNDERGROUND WATERS
The work covers the dissolved noble gases and nitrogen isotopes in the underground waters. The helium-neon systematics for dating purposes of the underground waters has been developed. The isotopy of the water-dissolved nitrogen forms has been used for study of contaminating underground waters. The nature protection measures in the Kirovsk mining region have been grounded, the evaluatiion of the natural resources and limit-permitted radionuclide concentrations has been obtained according to the data about tritium/helium-3-age of underground waters. The investigation results have been introduced in the geological-prospecting and mining enterprisesAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio
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