186 research outputs found
On the Bottom Blown Processes and the LD-AC Process
In February 1957, we had an opportunity to speak,in this country, in New Delhi, about the results of the research carried out by our centre National de Recherches Metall-urgiques in the feild of steelmaking; to be more precise, in the feild of blowing iron in a basic bottom-blown converter either with oxygen-enriched air or with an ox-ygen and steam mixture.
On that occasion, we also emphasised the results dea- ling with the industrial development of the new blowing processes that we formerly recomended.
From that time the industrial application of these
methods still expanded and at the present time 10 steelworks have recourse to it. Let us point out the
fact that two out of these works are located in
Great-Britain and that a third steelworks will start
running there within a few months
PGTask: Introducing the Task of Profile Generation from Dialogues
Recent approaches have attempted to personalize dialogue systems by
leveraging profile information into models. However, this knowledge is scarce
and difficult to obtain, which makes the extraction/generation of profile
information from dialogues a fundamental asset. To surpass this limitation, we
introduce the Profile Generation Task (PGTask). We contribute with a new
dataset for this problem, comprising profile sentences aligned with related
utterances, extracted from a corpus of dialogues. Furthermore, using
state-of-the-art methods, we provide a benchmark for profile generation on this
novel dataset. Our experiments disclose the challenges of profile generation,
and we hope that this introduces a new research direction.Comment: 4 pages, 2 figure
CH in stellar atmospheres: an extensive linelist
The advent of high-resolution spectrographs and detailed stellar atmosphere
modelling has strengthened the need for accurate molecular data.
Carbon-enhanced metal-poor (CEMP) stars spectra are interesting objects with
which to study transitions from the CH molecule. We combine programs for
spectral analysis of molecules and stellar-radiative transfer codes to build an
extensive CH linelist, including predissociation broadening as well as newly
identified levels. We show examples of strong predissociation CH lines in CEMP
stars, and we stress the important role played by the CH features in the
Bond-Neff feature depressing the spectra of barium stars by as much as 0.2
magnitudes in the 3000 -- 5500 \AA\ range. Because of the extreme
thermodynamic conditions prevailing in stellar atmospheres (compared to the
laboratory), molecular transitions with high energy levels can be observed.
Stellar spectra can thus be used to constrain and improve molecular data.Comment: 33pages, 15 figures, accepted in A&A external data available at
http://www.astro.ulb.ac.be/~spectrotools
Chatbots’ greetings to human-computer communication
In the last years, chatbots have gained new attention, due to the interest showed by widely known personalities and companies. The concept is broad, and, in this paper we target the work developed by the (old) community that is typically associated with chatbot’s competitions. In our opinion, they contribute with very interesting know-how, but specially with large-scale corpora, gathered by interactions with real people, an invaluable resource considering the renewed interest in Deep Nets.info:eu-repo/semantics/publishedVersio
Analysis of ozone and nitric acid in spring and summer Arctic pollution using aircraft, ground-based, satellite observations and MOZART-4 model: source attribution and partitioning
In this paper, we analyze tropospheric O_3 together with HNO_3 during the POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport) program, combining observations and model results. Aircraft observations from the NASA ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) and NOAA ARCPAC (Aerosol, Radiation and Cloud Processes affecting Arctic Climate) campaigns during spring and summer of 2008 are used together with the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4) to assist in the interpretation of the observations in terms of the source attribution and transport of O_3 and HNO_3 into the Arctic (north of 60° N). The MOZART-4 simulations reproduce the aircraft observations generally well (within 15%), but some discrepancies in the model are identified and discussed. The observed correlation of O_3 with HNO_3 is exploited to evaluate the MOZART-4 model performance for different air mass types (fresh plumes, free troposphere and stratospheric-contaminated air masses).
Based on model simulations of O_3 and HNO_3 tagged by source type and region, we find that the anthropogenic pollution from the Northern Hemisphere is the dominant source of O3 and HNO3 in the Arctic at pressures greater than 400 hPa, and that the stratospheric influence is the principal contribution at pressures less 400 hPa. During the summer, intense Russian fire emissions contribute some amount to the tropospheric columns of both gases over the American sector of the Arctic. North American fire emissions (California and Canada) also show an important impact on tropospheric ozone in the Arctic boundary layer.
Additional analysis of tropospheric O_3 measurements from ground-based FTIR and from the IASI satellite sounder made at the Eureka (Canada) and Thule (Greenland) polar sites during POLARCAT has been performed using the tagged contributions. It demonstrates the capability of these instruments for observing pollution at northern high latitudes. Differences between contributions from the sources to the tropospheric columns as measured by FTIR and IASI are discussed in terms of vertical sensitivity associated with these instruments. The first analysis of O_3 tropospheric columns observed by the IASI satellite instrument over the Arctic is also provided. Despite its limited vertical sensitivity in the lowermost atmospheric layers, we demonstrate that IASI is capable of detecting low-altitude pollution transported into the Arctic with some limitations
Measurements of hydrogen cyanide (HCN) and acetylene (C2H2) from the Infrared Atmospheric Sounding Interferometer (IASI)
Hydrogen cyanide (HCN) and acetylene (C2H2) are ubiquitous atmospheric trace gases with medium lifetime, which are frequently used as indicators of combustion sources and as tracers for atmospheric transport and chemistry. Because of their weak infrared absorption, overlapped by the CO2 Q branch near 720 cm−1, nadir sounders have up to now failed to measure these gases routinely. Taking into account CO2 line mixing, we provide for the first time extensive measurements of HCN and C2H2 total columns at Reunion Island (21° S, 55° E) and Jungfraujoch (46° N, 8° E) in 2009–2010 using observations from the Infrared Atmospheric Sounding Interferometer (IASI). A first order comparison with local ground-based Fourier transform InfraRed (FTIR) measurements has been carried out allowing tests of seasonal consistency which is reasonably captured, except for HCN at Jungfraujoch. The IASI data shows a greater tendency to high C2H2 values. We also examine a nonspecific biomass burning plume over austral Africa and show that the emission ratios with respect to CO agree with previously reported values
Determination of enhancement ratios of HCOOH relative to CO in biomass burning plumes by the Infrared Atmospheric Sounding Interferometer (IASI)
Formic acid (HCOOH) concentrations are often underestimated by models, and its
chemistry is highly uncertain. HCOOH is, however, among the most abundant
atmospheric volatile organic compounds, and it is potentially responsible for
rain acidity in remote areas. HCOOH data from the Infrared Atmospheric
Sounding Interferometer (IASI) are analyzed from 2008 to 2014 to estimate
enhancement ratios from biomass burning emissions over seven regions.
Fire-affected HCOOH and CO total columns are defined by combining total
columns from IASI, geographic location of the fires from Moderate Resolution
Imaging Spectroradiometer (MODIS), and the surface wind speed field from the
European Centre for Medium-Range Weather Forecasts (ECMWF). Robust
correlations are found between these fire-affected HCOOH and CO total columns
over the selected biomass burning regions, allowing the calculation of
enhancement ratios equal to
7.30 × 10−3 ± 0.08 × 10−3 mol mol−1 over Amazonia (AMA),
11.10 × 10−3 ± 1.37 × 10−3 mol mol−1
over Australia (AUS),
6.80 × 10−3 ± 0.44 × 10−3 mol mol−1
over India (IND),
5.80 × 10−3 ± 0.15 × 10−3 mol mol−1
over Southeast Asia (SEA),
4.00 × 10−3 ± 0.19 × 10−3 mol mol−1
over northern Africa (NAF),
5.00 × 10−3 ± 0.13 × 10−3 mol mol−1
over southern Africa (SAF), and
4.40 × 10−3 ± 0.09 × 10−3 mol mol−1
over Siberia (SIB), in a fair agreement with previous studies. In comparison with
referenced emission ratios, it is also shown that the selected agricultural
burning plumes captured by IASI over India and Southeast Asia correspond
to recent plumes where the chemistry or the sink does not occur. An
additional classification of the enhancement ratios by type of fuel burned is
also provided, showing a diverse origin of the plumes sampled by IASI,
especially over Amazonia and Siberia. The variability in the enhancement
ratios by biome over the different regions show that the levels of HCOOH and
CO do not only depend on the fuel types
Decoherence of matter waves by thermal emission of radiation
Emergent quantum technologies have led to increasing interest in decoherence
- the processes that limit the appearance of quantum effects and turn them into
classical phenomena. One important cause of decoherence is the interaction of a
quantum system with its environment, which 'entangles' the two and distributes
the quantum coherence over so many degrees of freedom as to render it
unobservable. Decoherence theory has been complemented by experiments using
matter waves coupled to external photons or molecules, and by investigations
using coherent photon states, trapped ions and electron interferometers. Large
molecules are particularly suitable for the investigation of the
quantum-classical transition because they can store much energy in numerous
internal degrees of freedom; the internal energy can be converted into thermal
radiation and thus induce decoherence. Here we report matter wave
interferometer experiments in which C70 molecules lose their quantum behaviour
by thermal emission of radiation. We find good quantitative agreement between
our experimental observations and microscopic decoherence theory. Decoherence
by emission of thermal radiation is a general mechanism that should be relevant
to all macroscopic bodies.Comment: 5 pages, 4 figure
An examination of the long-term CO records from MOPITT and IASI: comparison of retrieval methodology
International audienceCarbon monoxide (CO) is a key atmospheric compound that can be remotely sensed by satellite on the global scale. Fifteen years of continuous observations are now available from the MOPITT/Terra mission (2000 to present). Another fifteen and more years of observations will be provided by the IASI/MetOp instrument series (2007–2023>). In order to study long term variability and trends, a homogeneous record is required, which is not straightforward as the retrieved products are instrument and processing dependent. The present study aims at evaluating the consistency between the CO products derived from the MOPITT and IASI missions, both for total columns and vertical profiles, during a six year overlap period (2008–2013). The analysis is performed by first comparing the available 2013 versions of the retrieval algorithms, and second using a dedicated reprocessing of MOPITT CO profiles and columns based on the IASI a priori constraints. MOPITT v5T total columns are generally slightly higher over land (bias ranging from 0 to 13%) than IASI v20100815 data. When IASI and MOPITT data are retrieved with the same a priori constraints, correlation coefficients are slightly improved. Large discrepancies (total column bias over 15%) observed in the Northern Hemisphere during the winter months are reduced by a factor of 2 to 2.5. The detailed analysis of retrieved vertical profiles compared with collocated aircraft data from the MOZAIC-IAGOS network, illustrates the advantages and disadvantages of a constant vs. a variable a priori. On one hand, MOPITT agrees better with the aircraft profiles for observations with persisting high levels of CO throughout the year due to pollution or seasonal fire activity (because the climatology-based a priori is supposed to be closer to the real atmospheric state). On the other hand, IASI performs better when unexpected events leading to high levels of CO occur, due to the less constrained variance-covariance matrix
Importance of the Saharan heat low in controlling the North Atlantic free tropospheric humidity budget deduced from IASI <i>δ</i>D observations
The isotopic composition of water vapour in the North Atlantic free
troposphere is investigated with Infrared Atmospheric Sounding Interferometer
(IASI) measurements of the D ∕ H ratio (δD) above the ocean. We
show that in the vicinity of West Africa, the seasonality of δD is
particularly strong (130 ‰), which is related with the influence of
the Saharan heat low (SHL) during summertime. The SHL indeed largely
influences the dynamic in that region by producing deep turbulent mixing
layers, yielding a specific water vapour isotopic footprint. The influence of
the SHL on the isotopic budget is analysed on various time and space scales
and is shown to be large, highlighting the importance of the SHL dynamics on
the moistening and the HDO enrichment of the free troposphere over the North
Atlantic. The potential influence of the SHL is also investigated on the
inter-annual scale as we also report important variations in δD above
the Canary archipelago region. We interpret the variability in the
enrichment, using backward trajectory analyses, in terms of the ratio of air
masses coming from the North Atlantic and air masses coming from the African
continent. Finally, the interest of IASI high sampling capabilities is
further illustrated by presenting spatial distributions of δD and
humidity above the North Atlantic from which we show that the different
sources and dehydration pathways controlling the humidity can be disentangled
thanks to the added value of δD observations. More generally, our
results demonstrate the utility of δD observations obtained from the
IASI sounder to gain insight into the hydrological cycle processes in the
West African region
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