The British Geological Survey's new Geomagnetic Data Web Service

Increasing demand within the geomagnetism community for high quality real-time or near-real-time observatory data means there is a requirement for data producers to have a robust and scalable data processing infrastructure capable of delivering geomagnetic data products over the Internet in a variety of formats. We describe a new software system, developed at BGS, which will allow access to our geomagnetic data products both within our organisation's intranet and over the Internet. We demonstrate how the system is designed to afford easy access to the data by a wide range of software clients and allow rapid development of software utilizing our observatory data

Transport and magnetic anomalies due to A-site ionic size mismatch in La0.5_{0.5}Ca0.5−x_{0.5-x}Ba_{x}MnO3_3

We present results of electrical resistivity, magnetoresistance and ac and dc magnetic susceptibility on polycrystalline samples of the type La(0.5)Ca(0.5-x)Ba(x)MnO(3) synthesized under identical heat treatment conditions. The substitution of larger Ba ions for Ca results in a non- monotonic variation of the curie temperature as the system evolves from a charge ordered insulating state for x=0 to a ferromagnetic metallic state for x=0.5. An intermediate compositino, x=0.1, interestingly exhibits ferromagnetic. insulating behaviour with thermal hysteresis in ac chi around the curie tem- perature (120K). The x=0.2 and 0.3 compounds exhibit semiconducting like behavior as the temperature is lowered below 300K, with a broad peak in rho around 80-100K: These compositions exhibit a weak increase in rho as the temperature lowered below 30K, indicative of electron localization effects. These compositions also undergo ferromagnetic transitions below about 200 and 235K respectively, though these are non-hysteretic; above all, for these compositions, MR is large and conveniently measurable over the entire tempera- ture range of measurement below Tc. This experimental finding may be of interest from the application point of view. We infer that the A-site ionic-size mismatch plays a crucial role in the deciding these properties.Comment: 5 pages, 6 Figures, Resubmitted with extended abstract on 26 Nov, 199

Comparative analysis of FACTS controllers by tuning employing GA and PSO

Stability exploration has drawn more attention in contemporary research for huge interconnected power system. It is a complex frame to describe the behaviour of system, hence it can create an overhead for modern computer to analyse the power system stability. The preliminary design and optimization can be achieved by low order liner model. In this paper, the design problems of SMIB-GPSS and SMIB-MBPSS are considered to compare the performance of PSO and GA optimization algorithms. The performance of both optimization techniques are then compared further. Simulation results are presented to demonstrate the effectiveness of the proposed approach to improve the power system stability

A Novel Hybrid Approach for Stability Analysis of SMIB using GA and PSO

Stability exploration has drawn more attention in contemporary research for huge interconnected power system. It is a complex frame to describe the behaviour of system, hence it can create an overhead for modern computer to analyse the power system stability (PSS).The preliminary design and optimization can be achieved by low order liner model. This paper presents a hybrid approach for the stability analysis of single machine infinite bus system using generic power system stabilizer (GPSS) and proportional-integral-derivative

Composition of Jupiter irregular satellites sheds light on their origin

Irregular satellites of Jupiter with their highly eccentric, inclined and distant orbits suggest that their capture took place just before the giant planet migration. We aim to improve our understanding of the surface composition of irregular satellites of Jupiter to gain insight into a narrow time window when our Solar System was forming. We observed three Jovian irregular satellites, Himalia, Elara, and Carme, using a medium-resolution 0.8-5.5 micro m spectrograph on the National Aeronautics and Space Administration (NASA) Infrared Telescope Facility (IRTF). Using a linear spectral unmixing model we have constrained the major mineral phases on the surface of these three bodies. Our results confirm that the surface of Himalia, Elara, and Carme are dominated by opaque materials such as those seen in carbonaceous chondrite meteorites. Our spectral modeling of NIR spectra of Himalia and Elara confirm that their surface composition is the same and magnetite is the dominant mineral. A comparison of the spectral shape of Himalia with the two large main C-type asteroids, Themis (D 176 km) and Europa (D 352 km), suggests surface composition similar to Europa. The NIR spectrum of Carme exhibits blue slope up to 1.5 microm and is spectrally distinct from those of Himalia and Elara. Our model suggests that it is compositionally similar to amorphous carbon. Himalia and Elara are compositionally similar but differ significantly from Carme. These results support the hypotheses that the Jupiter irregular satellites are captured bodies that were subject to further breakup events and clustered as families based on their similar physical and surface compositions

Dynamic analysis of a pre-and-post ice impacted blade

The dynamic characteristics of an engine blade are evaluated under pre-and-post ice impact conditions using the NASA in-house computer code BLASIM. The ice impacts the leading edge of the blade causing severe local damage. The local structural response of the blade due to the ice impact is predicted via a transient response analysis by modeling only a local patch around the impact region. After ice impact, the global geometry of the blade is updated using deformations of the local patch and a free vibration analysis is performed. The effects of ice impact location, size and ice velocity on the blade mode shapes and natural frequencies are investigated. The results indicate that basic nature of the mode shapes remains unchanged after impact and that the maximum variation in natural frequencies occurs for the twisting mode of the blade