1,377 research outputs found
Deep Tree Transductions - A Short Survey
The paper surveys recent extensions of the Long-Short Term Memory networks to
handle tree structures from the perspective of learning non-trivial forms of
isomorph structured transductions. It provides a discussion of modern TreeLSTM
models, showing the effect of the bias induced by the direction of tree
processing. An empirical analysis is performed on real-world benchmarks,
highlighting how there is no single model adequate to effectively approach all
transduction problems.Comment: To appear in the Proceedings of the 2019 INNS Big Data and Deep
Learning (INNSBDDL 2019). arXiv admin note: text overlap with
arXiv:1809.0909
Combining roller crimpers and flaming for the termination of cover crops in herbicide-free no-till cropping systems
The termination of cover crops in conventional no-till systems is mostly conducted mechanically
in combination with herbicides. Combining flaming and roller crimpers could be a viable
solution to avoid using herbicides for cover crop termination in farming systems where herbicides
are banned, or at least to reduce their use in an integrated management approach.
This research tested the effects of flaming used in combination with three different types of
roller crimpers to terminate a fall-sown cover crop mixture of winter pea and barley. The
cover crop termination rate was visually assessed in terms of percentage of green cover
provided by cover crop plants at different intervals from the termination date, and estimated
using a log-logistic non-linear regression model with four parameters. Machine performance
data are also reported. The results show that, irrespective of the roller type, flaming significantly
boosted the effect of the roller crimpers. In fact, an economic threshold for cover crop
suppression of 85% was reached only when the rollers were used in combination with flaming.
Nevertheless, none of the methods were able to reach the 100% of cover crop suppression.
In some case, the combined use of flaming and roller crimpers allowed reaching the
90% of cover crop devitalisation, which happened six weeks after the termination date.
More importantly, the use of flaming in combination with rollers shortened the time needed
to achieve the estimated levels of devitalisation, compared with the rollers used alone. We
conclude that flaming is an effective tool to increase the effectiveness of roller crimpers.
Nevertheless, further research is needed to identify solutions to overcome the barrier of the
high operational costs of flaming, which is constraining its wider adoption by farmers. Future
studies could focus, for instance, on the development of a new prototype of combined
machine for crimping and flaming the cover crops simultaneously, which could potentially
reduce the operational costs
Displacement power spectrum measurement of a macroscopic optomechanical system at thermal equilibrium
The mirror relative motion of a suspended Fabry-Perot cavity is studied in
the frequency range 3-10 Hz. The experimental measurements presented in this
paper, have been performed at the Low Frequency Facility, a high finesse
optical cavity 1 cm long suspended to a mechanical seismic isolation system
identical to that one used in the VIRGO experiment. The measured relative
displacement power spectrum is compatible with a system at thermal equilibrium
within its environmental. In the frequency region above 3 Hz, where seismic
noise contamination is negligible, the measurement distribution is stationary
and Gaussian, as expected for a system at thermal equilibrium. Through a simple
mechanical model it is shown that: applying the fluctuation dissipation theorem
the measured power spectrum is reproduced below 90 Hz and noise induced by
external sources are below the measurement.Comment: 11 pages, 9 figures, 2 tables, to be submitte
Inertial control of the mirror suspensions of the VIRGO interferometer for gravitational wave detection
In order to achieve full detection sensitivity at low frequencies, the
mirrors of interferometric gravitational wave detectors must be isolated from
seismic noise. The VIRGO vibration isolator, called 'superattenuator', is fully
effective at frequencies above 4 Hz. Nevertheless, the residual motion of the
mirror at the mechanical resonant frequencies of the system are too large for
the interferometer locking system and must be damped. A multidimensional
feedback system, using inertial sensors and digital processing, has been
designed for this purpose. An experimental procedure for determining the
feedback control of the system has been defined. In this paper a full
description of the system is given and experimental results are presented.Comment: 17 pages, 11 figures, accepted for publication on Review of
Scientific Instrument
Sensitivity Studies for Third-Generation Gravitational Wave Observatories
Advanced gravitational wave detectors, currently under construction, are
expected to directly observe gravitational wave signals of astrophysical
origin. The Einstein Telescope, a third-generation gravitational wave detector,
has been proposed in order to fully open up the emerging field of gravitational
wave astronomy. In this article we describe sensitivity models for the Einstein
Telescope and investigate potential limits imposed by fundamental noise
sources. A special focus is set on evaluating the frequency band below 10Hz
where a complex mixture of seismic, gravity gradient, suspension thermal and
radiation pressure noise dominates. We develop the most accurate sensitivity
model, referred to as ET-D, for a third-generation detector so far, including
the most relevant fundamental noise contributions.Comment: 13 pages, 7 picture
The variable finesse locking technique
Virgo is a power recycled Michelson interferometer, with 3 km long Fabry-Perot cavities in the arms. The locking of the interferometer has been obtained with an original lock acquisition technique. The main idea is to lock the instrument away from its working point. Lock is obtained by misaligning the power recycling mirror and detuning the Michelson from the dark fringe. In this way, a good fraction of light escapes through the antisymmetric port and the power build-up inside the recycling cavity is extremely low. The benefit is that all the degrees of freedom are controlled when they are almost decoupled, and the linewidth of the recycling cavity is large. The interferometer is then adiabatically brought on to the dark fringe. This technique is referred to as variable finesse, since the recycling cavity is considered as a variable finesse Fabry-Perot. This technique has been widely tested and allows us to reach the dark fringe in few minutes, in an essentially deterministic way
Scientific Potential of Einstein Telescope
Einstein gravitational-wave Telescope (ET) is a design study funded by the
European Commission to explore the technological challenges of and scientific
benefits from building a third generation gravitational wave detector. The
three-year study, which concluded earlier this year, has formulated the
conceptual design of an observatory that can support the implementation of new
technology for the next two to three decades. The goal of this talk is to
introduce the audience to the overall aims and objectives of the project and to
enumerate ET's potential to influence our understanding of fundamental physics,
astrophysics and cosmology.Comment: Conforms to conference proceedings, several author names correcte
Innovative crop and weed management strategies for organic spinach: crop yield and weed suppression
In organic agriculture, it is important to tackle crop and weed management from a system perspective to make it effective, especially in poorly competitive crops such as vegetables. For that reason, we developed two innovative integrated crop and weed management systems for a field vegetable crop sequence in a commercial organic farm that we have been comparing to a standard farm system from 2006 to 2008. The three systems are applied to a spinach-potato-cabbage-tomato two-year crop sequence and include different levels of technical innovation: Standard Crop Management System (SCMS); Intermediate Crop Management System (ICMS); and Advanced Crop Management System (ACMS). ICMS is based on a sequence of physical weed management treatments, whereas ACMS also includes a subterranean clover (Trifolium subterraneum) living mulch. In this paper we analyse the results obtained on spinach (Spinacia oleracea) in terms of crop yield and weed suppression. Both innovative systems increased total spinach fresh weight yield compared to SCMS, despite higher weed biomass. In ACMS, total weed biomass decreased linearly with increasing biomass of the subterranean clover living mulch
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