Radio direction finding for maritime search and rescue

Melbourne, VI

A Pattern Based Approach to Defining the Dynamic Infrastructure of UML 2.0

The 2U Consortium has recently submitted a proposal for the definition of the UML 2.0 infrastructure. This uses an innovative technique of rapidly “stamping out” the definition using a small number of patterns commonly found in software architecture. The patterns, their instantiation, and any further language details are described using precise class diagrams and OCL, this enables the definition to be easily understood. The main focus of the 2U approach is on the static part of the definition. A further concern when modelling software, using languages such as the UML, is describing the dynamic behaviour of the system over time. The contribution of this paper is to provide a template that can be used to “stamp out” the dynamic part of the UML 2.0 infrastructure. We argue for the suitability of the dynamic template because it makes little commitment to concrete abstractions and can, therefore, be used to support a broad spectrum of behavioural languages

Gravitational waves from Sco X-1: A comparison of search methods and prospects for detection with advanced detectors

The low-mass X-ray binary Scorpius X-1 (Sco X-1) is potentially the most luminous source of continuous gravitational-wave radiation for interferometers such as LIGO and Virgo. For low-mass X-ray binaries this radiation would be sustained by active accretion of matter from its binary companion. With the Advanced Detector Era fast approaching, work is underway to develop an array of robust tools for maximizing the science and detection potential of Sco X-1. We describe the plans and progress of a project designed to compare the numerous independent search algorithms currently available. We employ a mock-data challenge in which the search pipelines are tested for their relative proficiencies in parameter estimation, computational efficiency, robust- ness, and most importantly, search sensitivity. The mock-data challenge data contains an ensemble of 50 Scorpius X-1 (Sco X-1) type signals, simulated within a frequency band of 50-1500 Hz. Simulated detector noise was generated assuming the expected best strain sensitivity of Advanced LIGO and Advanced VIRGO ($4 \times 10^{-24}$ Hz$^{-1/2}$). A distribution of signal amplitudes was then chosen so as to allow a useful comparison of search methodologies. A factor of 2 in strain separates the quietest detected signal, at $6.8 \times 10^{-26}$ strain, from the torque-balance limit at a spin frequency of 300 Hz, although this limit could range from $1.2 \times 10^{-25}$ (25 Hz) to $2.2 \times 10^{-26}$ (750 Hz) depending on the unknown frequency of Sco X-1. With future improvements to the search algorithms and using advanced detector data, our expectations for probing below the theoretical torque-balance strain limit are optimistic.Comment: 33 pages, 11 figure