449 research outputs found
Proposed reference models for atomic oxygen in the terrestrial atmosphere
A provisional Atomic Oxygen Reference model was derived from average monthly ozone profiles and the MSIS-86 reference model atmosphere. The concentrations are presented in tabular form for the altitude range 40 to 130 km
Quantum correlation measurements in interferometric gravitational wave detectors
Quantum fluctuations in the phase and amplitude quadratures of light set limitations on the sensitivity of modern optical instruments. The sensitivity of the interferometric gravitational-wave detectors, such as the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), is limited by quantum shot noise, quantum radiation pressure noise, and a set of classical noises. We show how the quantum properties of light can be used to distinguish these noises using correlation techniques. Particularly, in the first part of the paper we show estimations of the coating thermal noise and gas phase noise, hidden below the quantum shot noise in the Advanced LIGO sensitivity curve. We also make projections on the observatory sensitivity during the next science runs. In the second part of the paper we discuss the correlation technique that reveals the quantum radiation pressure noise from the background of classical noises and shot noise. We apply this technique to the Advanced LIGO data, collected during the first science run, and experimentally estimate the quantum correlations and quantum radiation pressure noise in the interferometer
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Exploring the impact of software requirements on system-wide goals: a method using satisfaction arguments and i* goal modelling
This paper describes the application of requirements engineering concepts to support the analysis of the impact of new software systems on system-wide goals. Requirements on a new or revised software component of a socio-technical system not only have implications on the goals of the subsystem itself, but they also impact upon the goals of the existing integrated system. In industries such as air traffic management and healthcare, impacts need to be identified and demonstrated in order to assess concerns such as risk, safety, and accuracy. A method called PiLGRIM was developed which integrates means-end relationships within goal modelling with knowledge associated with the application domain. The relationship between domain knowledge and requirements, as described in a satisfaction argument, adds traceability rationale to help determine the impacts of new requirements across a network of heterogeneous actors. We report procedures that human analysts follow to use the concepts of satisfaction arguments in a software tool for i* goal modelling. Results were demonstrated using models and arguments developed in two case studies, each featuring a distinct socio-technical system – a new controlled airspace infringement detection tool for NATS (the UK's air navigation service provider), and a new version of the UK’s HIV/AIDS patient reporting system. Results provided evidence towards our claims that the conceptual integration of i* and satisfaction arguments is usable and useful to human analysts, and that the PiLGRIM impact analysis procedures and tool support are effective and scalable to model and analyse large and complex socio-technical systems
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Computational alignment of goals and scenarios for complex systems
The purpose of requirements validation is to determine whether a large requirements set will lead to the achievement of system-related goals under different conditions - a task that needs automation if it is to be performed quickly and accurately. One reason for the current lack of software tools to undertake such validation is the absence of the computational mechanisms needed to associate scenario, system specification and goal analysis tools. Therefore, in this paper, we report first research experiments in developing these new capabilities, and demonstrate them with a non-trivial example associated with a Rolls Royce aircraft engine software component
Testing the equivalence principle: why and how?
Part of the theoretical motivation for improving the present level of testing
of the equivalence principle is reviewed. The general rationale for optimizing
the choice of pairs of materials to be tested is presented. One introduces a
simplified rationale based on a trichotomy of competing classes of theoretical
models.Comment: 11 pages, Latex, uses ioplppt.sty, submitted to Class. Quantum Gra
On the possibility of measuring relativistic gravitational effects with a LAGEOS-LAGEOS II-OPTIS-mission
In this paper we wish to preliminary investigate if it would be possible to
use the orbital data from the proposed OPTIS mission together with those from
the existing geodetic passive SLR LAGEOS and LAGEOS II satellites in order to
perform precise measurements of some general relativistic
gravitoelectromagnetic effects, with particular emphasis on the Lense-Thirring
effect.Comment: Abridged version. 16 pages, no figures, 1 table. First results from
the GGM01C Earth gravity model. GRACE data include
Upper limit map of a background of gravitational waves (Physical Review D - Particles, Fields, Gravitation and Cosmology (2007) 76, (082003))
This paper was published online on 29 October 2007 with a formatting error in the fiftieth affiliation in the author list.The affiliation should read as ‘‘University of Western Australia, Crawley, WA 6009, Australia.’’ The affiliation has beencorrected as of 4 March 2008. The affiliation is incorrect in the printed version of the journal
Improving astrophysical parameter estimation via offline noise subtraction for Advanced LIGO
The Advanced LIGO detectors have recently completed their second observation run successfully. The run lasted for approximately 10 months and led to multiple new discoveries. The sensitivity to gravitational waves was partially limited by laser noise. Here, we utilize auxiliary sensors that witness these correlated noise sources, and use them for noise subtraction in the time domain data. This noise and line removal is particularly significant for the LIGO Hanford Observatory, where the improvement in sensitivity is greater than 20%. Consequently, we were also able to improve the astrophysical estimation for the location, masses, spins, and orbital parameters of the gravitational wave progenitors
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