Uncertainty Analyses in the Finite-Difference Time-Domain Method

Providing estimates of the uncertainty in results obtained by Computational Electromagnetic (CEM) simulations is essential when determining the acceptability of the results. The Monte Carlo method (MCM) has been previously used to quantify the uncertainty in CEM simulations. Other computationally efficient methods have been investigated more recently, such as the polynomial chaos method (PCM) and the method of moments (MoM). This paper introduces a novel implementation of the PCM and the MoM into the finite-difference time -domain method. The PCM and the MoM are found to be computationally more efficient than the MCM, but can provide poorer estimates of the uncertainty in resonant electromagnetic compatibility data

Opening of a trans-Pangaean marine corridor during the Early Jurassic: Insights from osmium isotopes across the Sinemurian–Pliensbachian GSSP, Robin Hood's Bay, UK

The Hispanic Corridor represents a significant phase of continental reorganisation of the Early Jurassic that eventually provided connectivity between the western Tethyan and eastern Pacific oceans along the Central Atlantic rift zone. Although the initiation of this marine corridor profoundly impacted oceanic circulation and marine faunal exchange patterns, the timing of its formation hitherto remains poorly constrained with estimates spanning both the Hettangian and Sinemurian. The Sinemurian–Pliensbachian Global Stratotype Section and Point (GSSP) at Robin Hood's Bay, UK, comprises a succession of well-exposed, immature organic-rich sediments, only previously characterised by strontium, oxygen and carbon isotope geochemistry. New Re and Os isotope profiling indicates substantial variation in seawater chemistry at this time. Initial osmium isotope data become increasing unradiogenic (0.40 to 0.20) across the boundary, providing evidence for a continual flux of unradiogenic Os into the oceans during the latest Sinemurian. The initial unradiogenic 187Os/188Os values indicate the occurrence of low-temperature hydrothermal activity associated with the formation of the Hispanic Corridor during the breakup of Pangaea. Therefore, combined with biogeography and faunal exchange patterns, the Os isotope data demonstrates that connectivity between the Eastern Pacific and Tethyan oceans initiated during the latest Sinemurian. As a result this study better constrains the timing of establishment of the Hispanic Corridor, which was previously limited to poorly defined biogeography

Efficient modelling of thin conducting sheets within the TLM method

The paper describes the use of recursive filters to efficiently model the transmission through thin conducting layers in the Transmission Line Matrix (TLM) method of numerical electromagnetic modelling. The technique is applicable where the layer may be many skin-depths thick but thin compared with the mesh size. The technique is validated against an analytical solution, and improved efficiency over other methods is demonstrated. The technique is also applicable to composite layers with complex structures which are not amenable to analytical solution

Collection of anthropometry from older and physically impaired persons: traditional methods versus TC2 3-D body scanner

With advances in technology it is now possible to collect a wide range of anthropometric data, to a high degree of accuracy, using 3D light-based body scanners. This gives the potential to speed up the collection of anthropometric data for design purposes, to decrease processing time and data input required, and to reduce error due to inaccuracy of measurements taken using more traditional methods and equipment (anthropometer, stadiometer and sitting height table). However, when the data collection concerns older and/or physically impaired people there are serious issues for consideration when deciding on the best method to collect anthropometry. This paper discusses the issues arising when collecting data using both traditional methods of data collection and a first use by the experimental team of the TC2 3D body scanner, when faced with a ‘non-standard’ sample, during an EPSRC funded research project into issues surrounding transport usage by older and physically impaired people. Relevance to industry: Designing products, environments and services so that the increasing ageing population, as well as the physically impaired, can use them increases the potential market. To do this, up-to-date and relevant anthropometry is often needed. 3D light-based bodyscanners offer a potential fast way of obtaining this data, and this paper discusses some of the issues with using one scanner with older and disabled people

Computational steering in realitygrid

The RealityGrid project (http://www.realitygrid.org) aims both to enable the discovery of new materials through integrated experiments and to understand the behaviour of physical systems based on the properties of their microscopic components using diverse simulation methods spanning many time and length scales. A central theme of RealityGrid is the facilitation of distributed and collaborative steering of parallel simulation codes and simultaneous on-line, high-end visualisation. In this paper, we review the motivations for computational steering and introduce the RealityGrid steering library and associated software. We then outline the capabilities of the library and describe the service-oriented architecture of the latest implementation, in which the steering controls of the application are exposed through an OGSI-compliant Grid service

Search for Primordial Black Holes with SGARFACE

The Short GAmma Ray Front Air Cherenkov Experiment (SGARFACE) uses the Whipple 10 m telescope to search for bursts of $\gamma$ rays. SGARFACE is sensitive to bursts with duration from a few ns to $\sim$20 $\mu$s and with $\gamma$-ray energy above 100 MeV. SGARFACE began operating in March 2003 and has collected 2.2 million events during an exposure time of 2267 hours. A search for bursts of $\gamma$ rays from explosions of primordial black holes (PBH) was carried out. A Hagedorn-type PBH explosion is predicted to be visible within 60 pc of Earth. Background events were caused by cosmic rays and by atmospheric phenomena and their rejection was accomplished to a large extent using the time-resolved images. No unambiguous detection of bursts of $\gamma$ rays could be made as the remaining background events mimic the expected shape and time development of bursts. Upper limits on the PBH explosion rate were derived from the SGARFACE data and are compared to previous and future experiments. We note that a future array of large wide-field air-Cherenkov telescopes equipped with a SGARFACE-like trigger would be able to operate background-free with a 20 to 30 times higher sensitivity for PBH explosions.Comment: 18 pages, 30 figures, accepted by Astroparticle Physics, corrected author list and Section 2.

Effect of logic family on radiated emissions from digital circuits

Radiated emissions were measured for simple digital circuits designed to operate with various logic families. Emissions in the near and far field were found to depend both on the circuit layout and the choice of logic family. However, the difference in peak emissions between any two logic families was found to be independent of circuit layout. The greatest difference in peak emissions was between high-speed 74ACT logic and low-speed 4000 CMOS logic devices, with a mean value of approximately 20 dB. Emissions from a more complex circuit were compared with the measurements on simple loop circuits. Test circuits were used to measure the propagation delay, the rise and fall times, the maximum operating frequency and the transient switching currents between two successive logic gates for each logic family. Empirical formulas have been derived that relate relative peak emissions to these switching parameters. It is hoped that these will assist designers to assess the effect of choice of logic family on electromagnetic compatibility

Variation of theanine, phenolic, and methylxanthine compounds in 21 cultivars of Camellia sinensis harvested in different seasons

This is the first study to use chemometric methods to differentiate among 21 cultivars of Camellia sinensis from China and between leaves harvested at different times of the year using 30 compounds implicated in the taste and quality of tea. Unique patterns of catechin derivatives were observed among cultivars and across harvest seasons. C. sinensis var. pubilimba (You 510) differed from the cultivars of C. sinensis var. sinensis, with higher levels of theobromine, (+)-catechin, gallocatechin, gallocatechin gallate and theasinensin B, and lower levels of (−)-epicatechin, (−)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG), respectively. Three cultivars of C. sinensis var. sinensis, Fuyun 7, Qiancha 7 and Zijuan contained significantly more caffeoylquinic acids than others cultivars. A Linear Discriminant Analysis model based on the abundance of 12 compounds was able to discriminate amongst all 21 tea cultivars. Harvest time impacted the abundance of EGC, theanine and afzelechin gallate

Dilepton Spectra from Decays of Light Unflavored Mesons

The invariant mass spectrum of the $e^{+}e^{-}$ and $\mu ^{+}\mu ^{-}$ pairs from decays of light unflavored mesons with masses below the $\phi (1020)$-meson mass to final states containing along with a dilepton pair one photon, one meson, and two mesons are calculated within the framework of the effective meson theory. The results can be used for simulations of the dilepton spectra in heavy-ion collisions and for experimental searches of dilepton meson decays.Comment: 73 pages, 19 figures, 3 tables, REVTeX, new references adde