A Study on Educations Role in Establishing Strategies for Improving Safety at Sea

AbstractSafety at sea is a major concern of the maritime industry and it is through education and training that continued improvement can be realized. Despite increased awareness there has often only been minimal improvement made to training programs. The steady stream of accidents and disasters at sea are testament to this situation. This paper has been written to encourage a review of present maritime education and training so as to provide a catalyst for improved safety at sea.In order to deal with these issues, three specific areas have been selected from extant literature that clearly demonstrate the important role education plays in the improvement of safety at sea. Parallels have been made to ways in which the aviation industry also deals with safety. The opinions of cadets at one maritime university in South Korea have been surveyed which afford a very powerful insight into the viewpoints of our future seafarers. A major rationale of this study is that issues of safety at sea are kept clearly in the attention of all involved in the maritime industry. By understanding the important role that education plays in improving safety at sea it is hoped that trainers and educators will continuously take time to improve the service they provide to seafarers and to the industry as a whole. The implications of the strategies outlined in this paper will hopefully encourage those with the power to induce change to search for ways to improve and implement the education and training that seafarers urgently need in order to enjoy a safe working environment

Online bayesian inference in some time-frequency representations of non-stationary processes

The use of Bayesian inference in the inference of time-frequency representations has, thus far, been limited to offline analysis of signals, using a smoothing spline based model of the time-frequency plane. In this paper we introduce a new framework that allows the routine use of Bayesian inference for online estimation of the time-varying spectral density of a locally stationary Gaussian process. The core of our approach is the use of a likelihood inspired by a local Whittle approximation. This choice, along with the use of a recursive algorithm for non-parametric estimation of the local spectral density, permits the use of a particle filter for estimating the time-varying spectral density online. We provide demonstrations of the algorithm through tracking chirps and the analysis of musical data

An Improved Red Spectrum of the Methane or T-dwarf SDSS 1624+0029: Role of the Alkali Metals

A Keck~II low resolution spectrum shortward of ome-micron is presented for SDSS 1624+0029, the first field methane or T dwarf discovered in the Sloan Digital Sky Survey. Significant flux is detected down to the spectrum's short wavelength limit of 6200\AA. The spectrum exhibits a broad absorption feature centered at 7700\AA, which we interpret as the K~I 7665/7699 resonance doublet. The observed flux declines shortward of 7000\AA, due most likely to the red wing of the Na~I doublet. Both Cs~I doublet lines are detected more strongly than in an earlier red spectrum. Neither Li~I absorption nor H$\alpha$ emission are detected. An exploratory model fit to the spectrum suggests that the shape of the red spectrum can be primarily accounted for by the broad wings of the K~I and Na~I doublets. This behavior is consistent with the argument proffered by Burrows, Marley and Sharp that strong alkali absorption is principally responsible for depressing T dwarf spectra shortward of 1$\mu$m. In particular, there seems no compelling reason at this time to introduce dust or an additional opacity source in the atmosphere of the SDSS object. The width of the K~I and strengths of the Cs~I lines also indicate that the Sloan object is warmer than Gl~229B.Comment: accepted March 3, 2000 for Ap.J. Letters, LaTeX, 2 figure

A Flaring L5 Dwarf: The Nature of H\alpha Emission in Very Low Mass (Sub)Stellar Objects

Time series spectrophotometry of the L5 dwarf 2MASS 01443536-0716142 showed strong H\alpha emission which declined by nearly 75% in four consecutive exposures. The line was not detected in emission on a spectrum obtained eleven months later. This behavior constrasts with that of 2MASSI J1315309-264951, an L5 dwarf which has shown even stronger H\alpha emission on four separate occasions. The observational database suggests that L dwarfs can be found in such strong flares only occasionally, with a duty cycle of order 1%. In contrast, the few, continuously-strong H\alpha emitters, including PC 0025+0447 and 2MASSI J1237392+652615, must either be (1) objects no older than 10-100 Myrs with continuously-active accretion and/or chromospheres, but which apparently formed in isolation from known young stellar clusters and associations, or (2) objects empowered by a different and unknown mechanism for the H\alpha energy.Comment: 11 pages, 2 figures, Astronomical Journal in press -- Jan 2003 issu

The 2MASS Wide-Field T Dwarf Search. IV Unting out T dwarfs with Methane Imaging

We present first results from a major program of methane filter photometry for low-mass stars and brown dwarfs. The definition of a new methane filter photometric system is described. A recipe is provided for the differential calibration of methane imaging data using existing 2MASS photometry. We show that these filters are effective in discriminating T dwarfs from other types of stars, and demonstrate this with Anglo-Australian Telescope observations using the IRIS2 imager. Methane imaging data and proper motions are presented for ten T dwarfs identified as part of the 2MASS "Wide Field T Dwarf Search" -- seven of them initially identified as T dwarfs using methane imaging. We also present near-infrared moderate resolution spectra for five T dwarfs, newly discovered by this technique. Spectral types obtained from these spectra are compared to those derived from both our methane filter observations, and spectral types derived by other observers. Finally, we suggest a range of future programs to which these filters are clearly well suited: the winnowing of T dwarf and Y dwarf candidate objects coming from the next generation of near-infrared sky surveys; the robust detection of candidate planetary-mass brown dwarfs in clusters; the detection of T dwarf companions to known L and T dwarfs via deep methane imaging; and the search for rotationally-modulated time-variable surface features on cool brown dwarfs.Comment: 20 pages. To appear in The Astronomical Journal, Nov. 200

WISE J163940.83-684738.6: A Y Dwarf identified by Methane Imaging

We have used methane imaging techniques to identify the near-infrared counterpart of the bright WISE source WISEJ163940.83-684738.6. The large proper motion of this source (around 3.0arcsec/yr) has moved it, since its original WISE identification, very close to a much brighter background star -- it currently lies within 1.5" of the J=14.90+-0.04 star 2MASS16394085-6847446. Observations in good seeing conditions using methane sensitive filters in the near-infrared J-band with the FourStar instrument on the Magellan 6.5m Baade telescope, however, have enabled us to detect a near-infrared counterpart. We have defined a photometric system for use with the FourStar J2 and J3 filters, and this photometry indicates strong methane absorption, which unequivocally identifies it as the source of the WISE flux. Using these imaging observations we were then able to steer this object down the slit of the FIRE spectrograph on a night of 0.6" seeing, and so obtain near-infrared spectroscopy confirming a Y0-Y0.5 spectral type. This is in line with the object's near-infrared-to-WISE J3--W2 colour. Preliminary astrometry using both WISE and FourStar data indicates a distance of 5.0+-0.5pc and a substantial tangential velocity of 73+-8km/s. WISEJ163940.83-684738.6 is the brightest confirmed Y dwarf in the WISE W2 passband and its distance measurement places it amongst the lowest luminosity sources detected to date.Comment: Accepted for publication in The Astrophysical Journal, 20 September 201

Building an end user focused THz based ultra high bandwidth wireless access network: The TERAPOD approach

The TERAPOD project aims to investigate and demonstrate the feasibility of ultra high bandwidth wireless access networks operating in the Terahertz (THz) band. The proposed TERAPOD THz communication system will be developed, driven by end user usage scenario requirements and will be demonstrated within a first adopter operational setting of a Data Centre. In this article, we define the full communications stack approach that will be taken in TERAPOD, highlighting the specific challenges and aimed innovations that are targeted

Chromospherically Active Stars. VI. HD 136901 = UV CrB: A Massive Ellipsoidal K Giant Single-Lined Spectroscopic Binary

The variable star HD 136901 = UV CrB is a chromospherically active K2 III single-lined spectroscopic binary with an orbital period of 18.665 days. It has modest-strength Ca H and K emission and UV features, while H-alpha is a strong absorption feature containing little or no emission. The inclination of the system is 53 + or - 12 deg. The v sin i of the primary is 42 + or - 2 km/s, resulting in a minimum radius of 15.5 + or - 0.8 solar. When compared with the Roche lobe radius, this results in a mass ratio of 2.90 or larger. Additional constraints indicate that the secondary has a mass between 0.85 and 1.25 solar. Thus, the mass of the primary is at least 2.5 solar and probably is in the range 2.5-4 solar

Substellar Companions to Main Sequence Stars: No Brown Dwarf Desert at Wide Separations

We use three field L and T dwarfs which were discovered to be wide companions to known stars by the Two Micron All-Sky Survey (2MASS) to derive a preliminary brown dwarf companion frequency. Observed L and T dwarfs indicate that brown dwarfs are not unusually rare as wide (Delta >1000 A.U.) systems to F-M0 main-sequence stars (M>0.5M_sun, M_V<9.5), even though they are rare at close separation (Delta <3 A.U.), the ``brown dwarf desert.'' Stellar companions in these separation ranges are equally frequent, but brown dwarfs are >~ 10 times as frequent for wide than close separations. A brown dwarf wide-companion frequency as low as the 0.5% seen in the brown dwarf desert is ruled out by currently-available observations.Comment: ApJL, in pres