11,467 research outputs found
SHIP MOTION SHORT TERM TIME DOMAIN SIMULATOR AND ITS APPLICATION TO COSTA CONCORDIA EMERGENCY MANOEUVRES JUST BEFORE THE JANUARY 2012 ACCIDENT
In this paper we will present a simple but reliable methodology for short term prediction of a cruise ship behaviour during manoeuvres. The methodology is quite general and could be applied to any kind of ship, because it does not require the prior knowledge of any structural or mechanical parameter of the ship. It is based only on the results of manoeuvrability data contained in the Manoeuvring Booklet, which in turn is filled out after sea trials of the ship performed before his delivery to the owner.
We developed this method to support the investigations around the Costa Concordia shipwreck, which happened near the shores of Italy in January 2012. It was then validated against the data recorded in the “black box” of the ship, from which we have been able to extract an entire week of voyage data before the shipwreck. The aim was investigating the possibility of avoiding the impact by performing an evasive manoeuvre (as ordered by the Captain some seconds before the impact, but allegedly misunderstood by the helmsman). The preliminary validation step showed a good matching between simulated and real values (course and heading of the ship) for a time interval of a few minutes.
The fact that the method requires only the results registered in the VDR (Voyage Data Recorder) during sea trial tests, makes it very useful for several applications. Among them, we can cite forensic investigation, the development of components for autopilots, the prediction of the effects of a given manoeuvre in shallow water, the “a posteriori” verification of the correctness of a given manoeuvre and the use in training simulators for ship pilots and masters
Constraining the abundances of complex organics in the inner regions of solar-type protostars
The high abundances of Complex Organic Molecules (COMs) with respect to
methanol, the most abundant COM, detected towards low-mass protostars, tend to
be underpredicted by astrochemical models. This discrepancy might come from the
large beam of the single-dish telescopes, encompassing several components of
the studied protostar, commonly used to detect COMs. To address this issue, we
have carried out multi-line observations of methanol and several COMs towards
the two low-mass protostars NGC1333-IRAS2A and -IRAS4A with the Plateau de Bure
interferometer at an angular resolution of 2 arcsec, resulting in the first
multi-line detection of the O-bearing species glycolaldehyde and ethanol and of
the N-bearing species ethyl cyanide towards low-mass protostars other than IRAS
16293. The high number of detected transitions from COMs (more than 40 methanol
transitions for instance) allowed us to accurately derive the source size of
their emission and the COMs column densities. The COMs abundances with respect
to methanol derived towards IRAS2A and IRAS4A are slightly, but not
substantitally, lower than those derived from previous single-dish
observations. The COMs abundance ratios do not vary significantly with the
protostellar luminosity, over five orders of magnitude, implying that low-mass
hot corinos are quite chemically rich as high-mass hot cores. Astrochemical
models still underpredict the abundances of key COMs, such as methyl formate or
di-methyl ether, suggesting that our understanding of their formation remains
incomplete.Comment: 60 pages, 10 figures, 17 tables. Accepted for publication in Ap
Comparison of markets for organic food in six EU states.
This report was presented at the UK Organic Research 2002 Conference. Recent research confirms that the decision to convert is now highly influenced by financial incentives arising from EU regulations but the exact mix of incentives depends on prevailing government policies and access to premium markets so that the organic sector in most countries is now referred to as either government-led or market-driven. The objective of the paper is to compare development of the sector along these two polarities but set within the context of "common elements of interest" within new agrifood methodologies: time, space, power, and meaning (Cooke, Uranga and Etxebarria 1998; Morgan and Murdoch 2000). The paper presents preliminary findings relating to six EU States: UK, Ireland, Austria, Denmark, Portugal and Italy, and through the application of "worlds of production" to market outlets and suggests discourses that define these outlets. The analysis aims to inform the further study of farmer marketing decisions and practices
Near-arcsecond resolution observations of the hot corino of the solar type protostar IRAS 16293-2422
Complex organic molecules have previously been discovered in solar type
protostars, raising the questions of where and how they form in the envelope.
Possible formation mechanisms include grain mantle evaporation, interaction of
the outflow with its surroundings or the impact of UV/X-rays inside the
cavities. In this Letter we present the first interferometric observations of
two complex molecules, CH3CN and HCOOCH3, towards the solar type protostar
IRAS16293-2422. The images show that the emission originates from two compact
regions centered on the two components of the binary system. We discuss how
these results favor the grain mantle evaporation scenario and we investigate
the implications of these observations for the chemical composition and
physical and dynamical state of the two components.Comment: 5 pages (apjemulate), 2 figures; accepted by ApJ
The growth and erosion of cinder cones in Guatemala and El Salvador: Models and statistics
Morphologic data for 147 cinder cones in southern Guatemala andwestern El Salvador are comparedwith data from
the San Francisco volcanic field, Arizona (USA), Cima volcanic field, California (USA), Michoácan–Guanajuato
volcanic field, Mexico, and the Lamongan volcanic field, East Java. The Guatemala cones have an average height of
110+/-50 m, an average basal diameter of 660+/-230 m and an average top diameter of 180+/-150 m. The
generalmorphology of these cones can be described by their average cone angle of slope (24+/-7), average heightto-
radius ratio (0.33+/-0.09) and their flatness (0.24+/-0.18). Although the mean values for the Guatemalan
cones are similar to those for other volcanic fields (e.g., San Francisco volcanic field, Arizona; Cima volcanic field,
California; Michoácan–Guanajuato volcanic field, Mexico; and Lamongan volcanic field, East Java), the range of
morphologies encompasses almost all of those observed worldwide for cinder cones.
Three new 40Ar/39Ar age dates are combined with 19 previously published dates for cones in Guatemala and El
Salvador. There is no indication that the morphologies of these cones have changed over the last 500–1000 ka.
Furthermore, a re-analysis of published data for other volcanic fields suggests that only in the Cima volcanic field (of
those studied) is there clear evidence of degradation with age.
Preliminary results of a numerical model of cinder cone growth are used to show that the range of morphologies
observed in the Guatemalan cinder cones could all be primary, that is, due to processes occurring at the time of
eruption
Influence of conformational fluctuations on enzymatic activity: modelling the functional motion of beta-secretase
Considerable insight into the functional activity of proteins and enzymes can
be obtained by studying the low-energy conformational distortions that the
biopolymer can sustain. We carry out the characterization of these large scale
structural changes for a protein of considerable pharmaceutical interest, the
human -secretase. Starting from the crystallographic structure of the
protein, we use the recently introduced beta-Gaussian model to identify, with
negligible computational expenditure, the most significant distortion occurring
in thermal equilibrium and the associated time scales. The application of this
strategy allows to gain considerable insight into the putative functional
movements and, furthermore, helps to identify a handful of key regions in the
protein which have an important mechanical influence on the enzymatic activity
despite being spatially distant from the active site. The results obtained
within the Gaussian model are validated through an extensive comparison against
an all-atom Molecular Dynamics simulation.Comment: To be published in a special issue of J. Phys.: Cond. Mat. (Bedlewo
Workshop
The IC1396N proto-cluster at a scale of 250 AU
We investigate the mm-morphology of IC1396N with unprecedented spatial
resolution to analyze its dust and molecular gas properties, and draw
comparisons with objects of similar mass. We have carried out sensitive
observations in the most extended configurations of the IRAM Plateau de Bure
interferometer, to map the thermal dust emission at 3.3 and 1.3mm, and the
emission from the =13 hyperfine transitions of methyl cyanide
(CHCN). We unveil the existence of a sub-cluster of hot cores in IC1396N,
distributed in a direction perpendicular to the emanating outflow. The cores
are embedded in a common envelope of extended and diffuse dust emission. We
find striking differences in the dust properties of the cores ( 0)
and the surrounding envelope ( 1), very likely testifying to
differences in the formation and processing of dust material. The CHCN
emission peaks towards the most massive hot core and is marginally extended in
the outflow direction
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