18,178 research outputs found
Constraints, Lazy Constraints, or Propagators in ASP Solving: An Empirical Analysis
Answer Set Programming (ASP) is a well-established declarative paradigm. One
of the successes of ASP is the availability of efficient systems.
State-of-the-art systems are based on the ground+solve approach. In some
applications this approach is infeasible because the grounding of one or few
constraints is expensive. In this paper, we systematically compare alternative
strategies to avoid the instantiation of problematic constraints, that are
based on custom extensions of the solver. Results on real and synthetic
benchmarks highlight some strengths and weaknesses of the different strategies.
(Under consideration for acceptance in TPLP, ICLP 2017 Special Issue.)Comment: Paper presented at the 33nd International Conference on Logic
Programming (ICLP 2017), Melbourne, Australia, August 28 to September 1,
2017. 16 page
The Design of the Fifth Answer Set Programming Competition
Answer Set Programming (ASP) is a well-established paradigm of declarative
programming that has been developed in the field of logic programming and
nonmonotonic reasoning. Advances in ASP solving technology are customarily
assessed in competition events, as it happens for other closely-related
problem-solving technologies like SAT/SMT, QBF, Planning and Scheduling. ASP
Competitions are (usually) biennial events; however, the Fifth ASP Competition
departs from tradition, in order to join the FLoC Olympic Games at the Vienna
Summer of Logic 2014, which is expected to be the largest event in the history
of logic. This edition of the ASP Competition series is jointly organized by
the University of Calabria (Italy), the Aalto University (Finland), and the
University of Genova (Italy), and is affiliated with the 30th International
Conference on Logic Programming (ICLP 2014). It features a completely
re-designed setup, with novelties involving the design of tracks, the scoring
schema, and the adherence to a fixed modeling language in order to push the
adoption of the ASP-Core-2 standard. Benchmark domains are taken from past
editions, and best system packages submitted in 2013 are compared with new
versions and solvers.
To appear in Theory and Practice of Logic Programming (TPLP).Comment: 10 page
Wood wasp inspired space and earth drill
In this chapter, we explain why the low gravity encountered on Mars or on the Moon and the low mass of the probes, landers and rovers that carry drilling devices limit classical drilling techniques. Novel boring solutions optimised in mass and power consumption are thus needed for space applications. Biologists have identified the wood wasp, an insect that is capable of "drilling" into wood to lay its eggs. A low mass and low power system, like an insect, capable of drilling into wood is of the highest interest for planetary drilling and terrestrial drilling alike. The general working principle of the wood wasp drill ("dual reciprocating drilling") will be exposed and the potential benefits of imitating the wood wasp for planetary drilling will be highlighted. Since the nature of wood is highly fibrous but the nature of extraterrestrial and terrestrial soils are not, it is necessary to adapt the wood wasp ovipositor to our target soils. A test bench to evaluate the influence of the different geometries and operational parameters was produced and is presented here. The dual reciprocating drilling experimental results obtained on this test bench are also highlighted. They should lead to a new and enhanced model and comprehension of dual-reciprocating-drilling
Combining WASP and Kepler data: the case of the Sct star KIC 7106205
Ground-based photometric observations from Wide Angle Search for Planets (WASP) have been calibrated, scaled and combined with Kepler observations of the δ Sct star KIC 7106205, allowing us to extend the time base of the study of the unexplained amplitude and frequency variation of a single pressure mode at ν = 13.3942 d−1 by 2 yr. Analysis of the combined data sets, spanning 6 yr, show that the amplitude modulation in KIC 7106205 has a much larger range than a previous study of the Kepler data alone indicated. The single pressure mode decreased from 11.70 ± 0.05 mmag in 2007, to 5.87 ± 0.03 mmag in 2009, and to 0.58 ± 0.06 mmag in 2013. Observations of the decrease in mode amplitude have now been extended back 2 yr before the launch of Kepler. With observations over a longer time span, we have been able to further investigate the decrease in mode amplitude in KIC 7106205 to address the question of mode amplitude stability in δ Sct stars. This study highlights the usefulness of the WASP data set for extending studies of some Kepler variable stars
A feature-rich transmission spectrum for WASP-127b
WASP-127b is one of the lowest density planets discovered to date. With a
sub-Saturn mass () and super-Jupiter radius
(), it orbits a bright G5 star, which is about to
leave the main-sequence. We aim to explore WASP-127b's atmosphere in order to
retrieve its main atmospheric components, and to find hints for its intriguing
inflation and evolutionary history. We used the ALFOSC spectrograph at the NOT
telescope to observe a low resolution (, seeing limited) long-slit
spectroscopic time series during a planetary transit, and present here the
first transmission spectrum for WASP-127b. We find the presence of a strong
Rayleigh slope at blue wavelengths and a hint of Na absorption, although the
quality of the data does not allow us to claim a detection. At redder
wavelengths the absorption features of TiO and VO are the best explanation to
fit the data. Although higher signal-to-noise ratio observations are needed to
conclusively confirm the absorption features, WASP-127b seems to posses a
cloud-free atmosphere and is one of the best targets to perform further
characterization studies in the near future.Comment: Accepted for Publication A&A Letters, May 22nd, 201
Comparative seasonality and diets of German (Vespula germanica) and common (V. vulgaris) wasp colonies in Manawatu, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University
German wasp (Vespula germanica) and common wasp (v. vulgaris) colonies were studied in urban and rural habitats in Manawatu, from January to August 1993. Relative abundance of colonies, nest site preferences, colony dynamics, phenology and diet are described. Data quantifying vespulid wasp nest abundance in Manawatu between 1991-1994 were sourced from pest control companies and the Manawatu-Wanganui Regional Council. These data were compared with rainfall records for the same period. Over 75% of nests examined in urban and rural Manawatu were built by common wasps. This trend persisted through the season with German wasps accounting for no more than 28% of nests reported in any one month. Most reports of wasps were made in January, with February and March also being high. Heavy rainfall in spring appeared to promote colony formation in the following year. Continued high rainfall between January-June, especially over 600 mm appeared, however, to suppress colonies during this time. Nest drowning is a possible reason for this. Different nest site preferences between the two species were evident in urban and rural habitats. Over half of all urban common wasp nests and a third of urban German wasp nests reported were in sites associated with buildings. Nests in such sites grow faster and larger than those in other sites. In contrast, all rural German wasp nests and 85% of rural common wasp nests were built in the ground. The invasion of Manawatu by common wasps does not appear to have modified the nest site preferences of German wasps. Seasonal traffic rates for both species were similar, with colonies peaking in late March. Common wasp traffic rates were significantly higher in January-February, probably because of earlier nest initiations. Prior to queen production common wasp colonies were most active in the early afternoon. Around the time of queen production early evening activity increased, possibly as a result of the seasonal decrease in day length. Nests with high numbers of worker/male cells built before male production began produced significantly more queens than those with fewer cells. Although similar in size to German wasp nests, common wasp nests contained more queen cells. Cell weights differed between the castes and species. German wasp nests therefore required more than twice as much effort to build as a common wasp nest of a similar size. The possible competitive effects of such differences are discussed. Manawatu German wasp colonies appear to produce males earlier (early February) than common wasp colonies (early March). The reverse applies to queen production which may have started earlier (March 12) in common wasp colonies than in German wasp colonies (March 20). However, variation within and between the species does occur. The egg laying ability of the founder queen appears to limit oviposition in worker/male cells but the availability of empty queen cells appears to limit oviposition in queen cells. The size of the worker force limits the number of larvae that can be cared for. Reproductives were seen leaving nests from early May and continued until the colonies died. In an overwintering German wasp nest production of all three castes were at levels equivalent to an annual nest at peak. German wasp foragers returned with a higher percentage of protein items (16%) than common wasp foragers (11%). Similar percentages of woodpulp were returned to colonies by both species. Diptera, Lepidoptera. Araneae, and Hemiptera were the main animal prey returned to urban and rural colonies. German wasp foragers returned with prey items that were significantly heavier than those carried by common wasps but woodpulp weight did not differ. However, common wasp colonies killed more invertebrates to meet their needs, suggesting that they represent a substantial threat to invertebrate communities. Both prey provision and woodpulp foraging increased dramatically with the onset of queen rearing, indicating the increased needs of colonies at this time. The ecological significance of woodpulp foraging on both species is discussed. Key areas for future wasp research that are applicable within Manawatu and more widely in New Zealand, are outlined. Main areas needing investigation concern aspects of colony dynamics and phenology
Multi-site campaign for transit timing variations of WASP-12 b: possible detection of a long-period signal of planetary origin
The transiting planet WASP-12 b was identified as a potential target for
transit timing studies because a departure from a linear ephemeris was reported
in the literature. Such deviations could be caused by an additional planet in
the system. We attempt to confirm the existence of claimed variations in
transit timing and interpret its origin. We organised a multi-site campaign to
observe transits by WASP-12 b in three observing seasons, using 0.5-2.6-metre
telescopes. We obtained 61 transit light curves, many of them with
sub-millimagnitude precision. The simultaneous analysis of the best-quality
datasets allowed us to obtain refined system parameters, which agree with
values reported in previous studies. The residuals versus a linear ephemeris
reveal a possible periodic signal that may be approximated by a sinusoid with
an amplitude of 0.00068+/-0.00013 d and period of 500+/-20 orbital periods of
WASP-12 b. The joint analysis of timing data and published radial velocity
measurements results in a two-planet model which better explains observations
than single-planet scenarios. We hypothesize that WASP-12 b might be not the
only planet in the system and there might be the additional 0.1 M_Jup body on a
3.6-d eccentric orbit. A dynamical analysis indicates that the proposed
two-planet system is stable over long timescales.Comment: Accepted for publication in A&
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