1,619 research outputs found
A semantic web approach for built heritage representation
In a built heritage process, meant as a structured system of activities
aimed at the investigation, preservation, and management of architectural
heritage, any task accomplished by the several actors involved in it is deeply
influenced by the way the knowledge is represented and shared. In the current
heritage practice, knowledge representation and management have shown several
limitations due to the difficulty of dealing with large amount of extremely heterogeneous
data. On this basis, this research aims at extending semantic web
approaches and technologies to architectural heritage knowledge management in
order to provide an integrated and multidisciplinary representation of the artifact
and of the knowledge necessary to support any decision or any intervention and
management activity. To this purpose, an ontology-based system, representing
the knowledge related to the artifact and its contexts, has been developed through
the formalization of domain-specific entities and relationships between them
Hybridizing the 1/5-th Success Rule with Q-Learning for Controlling the Mutation Rate of an Evolutionary Algorithm
It is well known that evolutionary algorithms (EAs) achieve peak performance
only when their parameters are suitably tuned to the given problem. Even more,
it is known that the best parameter values can change during the optimization
process. Parameter control mechanisms are techniques developed to identify and
to track these values.
Recently, a series of rigorous theoretical works confirmed the superiority of
several parameter control techniques over EAs with best possible static
parameters. Among these results are examples for controlling the mutation rate
of the ~EA when optimizing the OneMax problem. However, it was
shown in [Rodionova et al., GECCO'19] that the quality of these techniques
strongly depends on the offspring population size .
We introduce in this work a new hybrid parameter control technique, which
combines the well-known one-fifth success rule with Q-learning. We demonstrate
that our HQL mechanism achieves equal or superior performance to all techniques
tested in [Rodionova et al., GECCO'19] and this -- in contrast to previous
parameter control methods -- simultaneously for all offspring population sizes
. We also show that the promising performance of HQL is not restricted
to OneMax, but extends to several other benchmark problems.Comment: To appear in the Proceedings of Parallel Problem Solving from Nature
(PPSN'2020
Searching for Radio Pulsars in 3EG Sources at Urumqi Observatory
Since mid-2005, a pulsar searching system has been operating at 18 cm on the
25-m radio telescope of Urumqi Observatory. Test observations on known pulsars
show that the system can perform the intended task. The prospect of using this
system to observe 3EG sources and other target searching tasks is discussed.Comment: a training project about MSc thesi
Deterministic Random Walks on the Integers
Jim Propp's P-machine, also known as the "rotor router model" is a simple deterministic process that simulates a random walk on a graph. Instead of distributing chips to randomly chosen neighbors, it serves the neighbors in a fixed order. We investigate how well this process simulates a random walk. For the graph being the infinite path, we show that, independent of the starting configuration, at each time and on each vertex, the number of chips on this vertex deviates from the expected number of chips in the random walk model by at most a constant c_1, which is approximately 2.29. For intervals of length L, this improves to a difference of O(log L), for the L_2 average of a contiguous set of intervals even to O(sqrt{log L}). All these bounds are tight
The photospheric solar oxygen project: III. Investigation of the centre-to-limb variation of the 630nm [OI]-NiI blend
The solar photospheric abundance of oxygen is still a matter of debate. For
about ten years some determinations have favoured a low oxygen abundance which
is at variance with the value inferred by helioseismology. Among the oxygen
abundance indicators, the forbidden line at 630nm has often been considered the
most reliable even though it is blended with a NiI line. In Papers I and Paper
II of this series we reported a discrepancy in the oxygen abundance derived
from the 630nm and the subordinate [OI] line at 636nm in dwarf stars, including
the Sun. Here we analyse several, in part new, solar observations of the the
centre-to-limb variation of the spectral region including the blend at 630nm in
order to separate the individual contributions of oxygen and nickel. We analyse
intensity spectra observed at different limb angles in comparison with line
formation computations performed on a CO5BOLD 3D hydrodynamical simulation of
the solar atmosphere. The oxygen abundances obtained from the forbidden line at
different limb angles are inconsistent if the commonly adopted nickel abundance
of 6.25 is assumed in our local thermodynamic equilibrium computations. With a
slightly lower nickel abundance, A(Ni)~6.1, we obtain consistent fits
indicating an oxygen abundance of A(O)=8.73+/-0.05. At this value the
discrepancy with the subordinate oxygen line remains. The derived value of the
oxygen abundance supports the notion of a rather low oxygen abundance in the
solar hotosphere. However, it is disconcerting that the forbidden oxygen lines
at 630 and 636nm give noticeably different results, and that the nickel
abundance derived here from the 630nm blend is lower than expected from other
nickel lines.Comment: to appear in A&
A simple electrostatic model applicable to biomolecular recognition
An exact, analytic solution for a simple electrostatic model applicable to
biomolecular recognition is presented. In the model, a layer of high dielectric
constant material (representative of the solvent, water) whose thickness may
vary separates two regions of low dielectric constant material (representative
of proteins, DNA, RNA, or similar materials), in each of which is embedded a
point charge. For identical charges, the presence of the screening layer always
lowers the energy compared to the case of point charges in an infinite medium
of low dielectric constant. Somewhat surprisingly, the presence of a
sufficiently thick screening layer also lowers the energy compared to the case
of point charges in an infinite medium of high dielectric constant. For charges
of opposite sign, the screening layer always lowers the energy compared to the
case of point charges in an infinite medium of either high or low dielectric
constant. The behavior of the energy leads to a substantially increased
repulsive force between charges of the same sign. The repulsive force between
charges of opposite signs is weaker than in an infinite medium of low
dielectric constant material but stronger than in an infinite medium of high
dielectric constant material. The presence of this behavior, which we name
asymmetric screening, in the simple system presented here confirms the
generality of the behavior that was established in a more complicated system of
an arbitrary number of charged dielectric spheres in an infinite solvent.Comment: 15 pages, 6 figure
Effect of Particle Size on Droplet Infiltration into Hydrophobic Porous Media As a Model of Water Repellent Soil
The wettability of soil is of great importance for plants and soil biota, and in determining the risk for preferential flow, surface runoff, flooding,and soil erosion. The molarity of ethanol droplet (MED) test is widely used for quantifying the severity of water repellency in soils that show reduced wettability and is assumed to be independent of soil particle size. The minimum ethanol concentration at which droplet penetration occurs within a short time (≤10 s) provides an estimate of the initial advancing contact angle at which spontaneous wetting is expected. In this study, we test the assumption of particle size independence using a simple model of soil, represented by layers of small (0.2–2 mm) diameter beads that predict the effect of changing bead radius in the top layer on capillary driven imbibition. Experimental results using a three-layer bead system show broad agreement with the model and demonstrate a dependence of the MED test on particle size. The results show that the critical initial advancing contact angle for penetration can be considerably less than 90° and varies with particle size, demonstrating that a key assumption currently used in the MED testing of soil is not necessarily valid
Global Health Interventions:The Military, the Magic Bullet, the Deterministic Model—and Intervention Otherwise
“Intervention” is central to global health, but the significance and effects of how intervention is practiced are often taken for granted. This review takes interventions into health and medicine as subjects for ethnographic inquiry. We highlight three lines of anthropological contributions: studies of global health interventions that serve imperial and military objectives, studies of “magic bullet” interventions arising from laboratory science, and studies of interventions based on deterministic modeling techniques. We then outline examples of “intervention otherwise,” in which people build relations of solidarity and care through global health programming, design interventions to be interactive and adaptable, and use data and modeling to support health justice. Whereas many global health interventions reproduce Western power hierarchies, intervention otherwise draws attention to alternative forms of knowledge, action, and expertise. Our analysis of lively and multivalent practices of intervention has implications for debates about the im/possibility of decolonizing global health.<br/
Comb-calibrated solar spectroscopy through a multiplexed single-mode fiber channel
We investigate a new scheme for astronomical spectrograph calibration using
the laser frequency comb at the Solar Vacuum Tower Telescope on Tenerife. Our
concept is based upon a single-mode fiber channel, that simultaneously feeds
the spectrograph with comb light and sunlight. This yields nearly perfect
spatial mode matching between the two sources. In combination with the absolute
calibration provided by the frequency comb, this method enables extremely
robust and accurate spectroscopic measurements. The performance of this scheme
is compared to a sequence of alternating comb and sunlight, and to absorption
lines from Earth's atmosphere. We also show how the method can be used for
radial-velocity detection by measuring the well-explored 5-minute oscillations
averaged over the full solar disk. Our method is currently restricted to solar
spectroscopy, but with further evolving fiber-injection techniques it could
become an option even for faint astronomical targets.Comment: 21 pages, 11 figures. A video abstract for this paper is available on
youtube. For watching the video, please follow
https://www.youtube.com/watch?v=oshdZgrt89I . The video abstract is also
available for streaming and download on the related article website of New
Journal of Physic
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