Towards the Development of a Risk Model for Unmanned Vessels Design and Operations

An unmanned merchant vessel seems to be escaping from the stage of idea exploration. Once the concept proofs its safety, it may become a part of maritime reality. Although the safety aspect of such a ship has been addressed by a handful of scholars, the problem remains open. This is mainly due to lack of knowledge regarding actual operational circumstances and design of unmanned ships, which are yet to be developed. In the attempt of bridging this gap, the risk analysis associated with unmanned ships needs to be carried out, where all relevant hazards and consequences are assessed and quantified in systematic manner. In this paper we present the results of a first step of such analysis, namely the hazard analysis associated with the unmanned ships. The list of hazards covers various aspects of unmanned shipping originating from both design and operational phases of vessel’s life. Subsequently the hazards and related consequences are organized in a casual manner, resulting in the development of a structure of a risk model

Weak inter-band coupling in Mg10^{10}B2_{2}: a specific heat analysis

The superconducting state of Mg$^{10}$B$_{2}$ is investigated by specific heat measurements in detail. The specific heat in the normal state is analyzed using a recently developed computer code. This allows for an extraction of the electronic specific heat in the superconducting state with high accuracy and a fair determination of the main lattice features. One of the two investigated samples shows a hump in the specific heat at low temperatures within the superconducting state, accompanied by an unusual low value of the small gap, $\Delta_{\pi}(0)=1.32 meV$, pointing to a very weak inter-band coupling. This sample allows for a detailed analysis of the contribution from the $\pi$-band to the electronic specific heat in the superconducting state. Therefore the usual analysis method is modified, to include the individual conservation of entropy of both bands. From analyzing the deviation function $D(t)$ of MgB$_{2}$, the theoretically predicted weak inter-band coupling scenario is confirmed.Comment: major revision

Absolute physical calibration in the infrared

We determine an absolute calibration for the Multiband Imaging Photometer for Spitzer 24 μm band and recommend adjustments to the published calibrations for Two Micron All Sky Survey (2MASS), Infrared Array Camera (IRAC), and IRAS photometry to put them on the same scale. We show that consistent results are obtained by basing the calibration on either an average A0V star spectral energy distribution (SED), or by using the absolutely calibrated SED of the Sun in comparison with solar-type stellar photometry (the solar analog method). After the rejection of a small number of stars with anomalous SEDs (or bad measurements), upper limits of ~1.5% root mean square (rms) are placed on the intrinsic infrared (IR) SED variations in both A-dwarf and solar-type stars. These types of stars are therefore suitable as general-purpose standard stars in the IR. We provide absolutely calibrated SEDs for a standard zero magnitude A star and for the Sun to allow extending this work to any other IR photometric system. They allow the recommended calibration to be applied from 1 to 25 μm with an accuracy of ~2%, and with even higher accuracy at specific wavelengths such as 2.2, 10.6, and 24 μm, near which there are direct measurements. However, we confirm earlier indications that Vega does not behave as a typical A0V star between the visible and the IR, making it problematic as the defining star for photometric systems. The integration of measurements of the Sun with those of solar-type stars also provides an accurate estimate of the solar SED from 1 through 30 μm, which we show agrees with theoretical models

Extended Emission by Dust in the Dwarf Galaxy UGC 10445

We present Spitzer Space Telescope images of the isolated dwarf galaxy UGC 10445. The galaxy is detected at all photometric bands (3.6-160um) as well as in the Multiband Imaging Photometer for Spitzer (MIPS) spectral energy distribution mode (55-95um). We derive a star formation rate of 0.25 M_sun/yr based on H-alpha and infrared flux densities. There is over 10^6 solar masses of cold dust (T~18K) in the galaxy, represented by 160um emission, that extends to a larger radius than the ultraviolet (UV), optical and near-infrared light. Such extended emission has been seen previously only in dwarf galaxies in cluster environments. We suggest the source of heating for this dust is UV light originating in star forming complexes. To produce the large quantity of dust requires a higher rate of star formation in the past than is observed currently.Comment: 11 pages, 5 pages, accepted to ApJ, color high res figures available upon reques