Developing a grid computing system for commercial-off-the-shelf simulation packages

Today simulation is becoming an increasingly pervasive technology across major business sectors. Advances in COTS Simulation Packages and Commercial Simulation Software have made it easier for users to build models, often of large complex processes. These two factors combined are to be welcomed and when used correctly can be of great benefit to organisations that make use of the technology. However, it is also the case that users hungry for answers do not always have the time, or possibly the patience, to wait for results from multiple replications and multiple experiments as standard simulation practice would demand. There is therefore a need to support this advance in the use of simulation within today’s business with improved computing technology. Grid computing has been put forward as a potential commercial solution to this requirement. To this end, Saker Solutions and the Distributed Systems Research Group at Brunel University have developed a dedicated Grid Computing System (SakerGrid) to support the deployment of simulation models across a desktop grid of PCs. The paper identifies route taken to solve this challenging issue and suggests where the future may lie for this exciting integration of two effective but underused technologies

Growth and form of the mound in Gale Crater, Mars: Slope wind enhanced erosion and transport

Ancient sediments provide archives of climate and habitability on Mars. Gale Crater, the landing site for the Mars Science Laboratory (MSL), hosts a 5-km-high sedimentary mound (Mount Sharp/Aeolis Mons). Hypotheses for mound formation include evaporitic, lacustrine, fluviodeltaic, and aeolian processes, but the origin and original extent of Gale’s mound is unknown. Here we show new measurements of sedimentary strata within the mound that indicate ∼3° outward dips oriented radially away from the mound center, inconsistent with the first three hypotheses. Moreover, although mounds are widely considered to be erosional remnants of a once crater-filling unit, we find that the Gale mound’s current form is close to its maximal extent. Instead we propose that the mound’s structure, stratigraphy, and current shape can be explained by growth in place near the center of the crater mediated by wind-topography feedbacks. Our model shows how sediment can initially accrete near the crater center far from crater-wall katabatic winds, until the increasing relief of the resulting mound generates mound-flank slope winds strong enough to erode the mound. The slope wind enhanced erosion and transport (SWEET) hypothesis indicates mound formation dominantly by aeolian deposition with limited organic carbon preservation potential, and a relatively limited role for lacustrine and fluvial activity. Morphodynamic feedbacks between wind and topography are widely applicable to a range of sedimentary and ice mounds across the Martian surface, and possibly other planets

Extended BEG Model of Monhalogenated Methanes Physisorbed on Ionic Crystals

The 2D dielectric phases and phase transitions of adsorbed dipolar molecules are modeled using a dilute spin-one Ising model. This model is studied in the Blume–Emery–Griffiths formalism, using a mean-field approximation, where the interaction parameters are uniquely determined from the system interaction energies using an averaging procedure. The model is applied to four monhalogenated methane species physisorbed on MgO(1 0 0) and NaCl(1 0 0) surfaces using previous experimental and theoretical studies to estimate the interaction energy parameters. We find that temperature- and coverage-dependent antiferroelectric to ferroelectric, coverage-dependent ferroelectric up to ferroelectric down, reentrant ferroelectric to ferrielectric, and order-disorder dipole phase transitions can occur. Phase diagrams based on this model are presented

Fomalhaut's Debris Disk and Planet: Constraining the Mass of Formalhaut B from Disk Morphology

Following the optical imaging of exoplanet candidate Fomalhaut b (Fom b), we present a numerical model of how Fomalhaut's debris disk is gravitationally shaped by a single interior planet. The model is simple, adaptable to other debris disks, and can be extended to accommodate multiple planets. If Fom b is the dominant perturber of the belt, then to produce the observed disk morphology it must have a mass M(sub pl) 101.5AU, and an orbital eccentricity e(sub pl) = 0.11 - 0.13. These conclusions are independent of Fom b's photometry. To not disrupt the disk, a greater mass for Fom b demands a smaller orbit farther removed from the disk; thus, future astrometric measurement of Fom b's orbit, combined with our model of planet-disk interaction, can be used to determine the mass more precisely. The inner edge of the debris disk at a approximately equals 133AU lies at the periphery of Fom b's chaotic zone, and the mean disk eccentricity of e approximately equals 0.11 is secularly forced by the planet, supporting predictions made prior to the discovery of Fom b. However, previous mass constraints based on disk morphology rely on several oversimplifications. We explain why our constraint is more reliable. It is based on a global model of the disk that is not restricted to the planet's chaotic zone boundary. Moreover, we screen disk parent bodies for dynamical stability over the system age of approximately 100 Myr, and model them separately from their dust grain progeny; the latter's orbits are strongly affected by radiation pressure and their lifetimes are limited to approximately 0.1 Myr by destructive grain-grain collisions. The single planet model predicts that planet and disk orbits be apsidally aligned. Fomalhaut b's nominal space velocity does not bear this out, but the astrometric uncertainties are difficult to quantify. Even if the apsidal misalignment proves real, our calculated upper mass limit of 3 M(sub J) still holds. Parent bodies are evacuated from mean-motion resonances with Fom b; these empty resonances are akin to the Kirkwood gaps opened by Jupiter. The belt contains at least 3M(sub Earth) of solids that are grinding down to dust, their velocity dispersions stirred so strongly by Fom b that collisions are destructive. Such a large mass in solids is consistent with Fom b having formed in situ

Marine area governance and management in the Gulf of Maine : a case study

This case study provides a description and evaluation of marine area governance and management in the Gulf of Maine. On the advice of the Oversight Committee, we began the study at a broad level by identifying marine resources, uses of the resources, existing management regimes, and conflicts among users of the resources. The results of these initial reviews are collected in the tables in Appendix A. The Oversight Committee also suggested that we develop a chronology of important events relating to marine area governance and management in the Gulf of Maine, which is included as Appendix B. As is clear from even a quick scan of the material in Appendix A, almost every conceivable use of the marine environment occurs in the Gulf of Maine at some scale. However, some of these uses are more problematic than others in terms of the governance and management problems they engender. Rather than take a broadbrush approach that might not have done justice to any of the region's many ocean resources and uses, we decided to focus the case study on one or more of its most difficult and consequential governance and management issues. The initial survey enabled us to focus in on a subset of resources, use conflicts, and governance issues, namely those associated mainly with marine fisheries governance and management. Several considerations support the argument for a focus on fisheries governance and management. The marine fisheries are a regional-scale resource and industry, due to the mobility of the fish stocks, the geographic distribution of the users of the resource, and the fact that governance institutions have been designed to have regionwide authority. Thus fisheries mismanagement has the potential to inflict widespread social detriment and significant economic losses. Indeed, the net cost of depleted groundfish stocks under the current management structure, relative to the condition of stocks in an optimally managed fishery, has been estimated at about $139 million annually, or just under one-fifth the landed value of the entire Gulf of Maine commercial catch. Other ocean resources with potentially regional impacts, such as offshore energy, are not being pursued in the Gulf of Maine region at levels that pose significant concerns. Consequently, non-fishery resource management problems in the Gulf of Maine are, for the most part, local in scale, of comparatively minor economic significance, and not unique to the region. There is no evidence, for example, of "system-wide degradation of marine environmental quality in the Gulf of Maine. . . . The Gulf as a whole remains relatively clean, although the deep central basins appear to be accumulating several pollutants, including PAHs and PCBs" (GOMCME 1994; see also Dow and Braasch 1996 and Gould, Clark, and Thurberg 1994). Given that most pollutants of concern are concentrated in inshore waters near urban areas and in the mouths of industrialized rivers, it is not at all clear that they could be dealt with more effectively or efficiently at the regional level. In sum, our focus on fisheries reflects our judgment that the greatest net benefits might be obtained from improvements in the governance and management of these marine resources within the Gulf of Maine region.This case study was produced for the purposes of the Committee on Marine Area Governance and Management of the National Research Council (NRC), Agreement No. DOT -3830-96-002

The Diffusions Coefficient of Hemoglobin in Pure Water Solution

Carbon monoxide hemoglobin prepared from beef blood by the method of Marshall and Welker (J. Am. Chem. Soc., 35, 820. 1913) was allowed to diffuse from a water solution of constant concentration into pure pater contained in a thin flat cell of optical glass

Trimethylplatinum(IV) complexes of anionic N/O and O/O donor ligands: synthesis, NMR and fluxional behaviour

Reaction of pentane-2,4-dione, pyridine-2-carboxylic acid or pyridine-2,6-dicarboxylic acid with trimethylplatinum(IV) gives dimeric complexes of general formulae fac-[PtMe₃L]₂, in which the ionised ligand acts in a chelating and a bridging fashion. High-resolution solid-state ¹⁹ ;Pt NMR data shows that the two platinum atoms are equivalent ; the chemical shielding anisotropy and the principal components of the shielding tensor are reported. The complexes are soluble in co-ordinating solvents, yielding monomeric species of general formulae fac-[PtMe₃L(solvent)], which are fluxional. The pyridine adducts, fac-[PtMe₃L(py)] (L = pentane-2,4-dionato or pyridine-2-carboxylato), are also stereochemically non-rigid. The energetics of the dynamic processes have been studied by standard ¹H NMR band shape analysis techniques ; ΔG ‡ (298 K) is in the range 69–86 kJ mol⁻¹. Solid-state ¹³C, and solution-state ¹³C and ¹⁹;Pt NMR data are also reported

Extended BEG model of halogenated methanes physisorbed on ionic crystals

The 2D dielectric phases and phase transitions of adsorbed dipolar molecules are modeled using a dilute spin-one Ising model. This model is studied in the Blume-Emery-Griffiths formalism, using a mean-field approximation, where the interaction parameters are related to system interaction energies using a unique averaging procedure. The model is applied to four halogenated methane species physisorbed on MgO(100) and NaCl(100) surfaces using previous experimental and theoretical studies to estimate the interaction energy parameters. We find that temperature- and coverage-dependent antiferroelectric to ferroelectric, coverage-dependant ferroelectric up to ferroelectric down, reentrant ferroelectric to ferroelectric, and order-disorder dipole phase transitions can occur. Phase diagrams based on this model are presented

The effect of language-specific characteristics on English and Japanese speakers' ability to recall number information

The current paper presents two experiments investigating the effect of presence versus absence of compulsory number marking in a native language on a speaker’s ability to recall number information from photos. In Experiment 1, monolingual English and Japanese adults were shown a sequence of 110 photos after which they were asked questions about the photos. We found that the English participants showed a significantly higher accuracy rate for questions testing recall for number information when the correct answer was ‘2’ (instead of ‘1’) than Japanese participants. In experiment 2, English and Japanese adults engaged in the same task as in Experiment 1 with an addition that explored reasons for the results found in Experiment 1. The results of Experiment 2 were in line with the results of Experiment 1, but also suggested that the results could not be attributed to differences in guessing patterns between the two groups or the type of linguistic constructions used in the test situations. The current study suggests that native language affects speakers’ ability to recall number information from scenes and thus provides evidence for the Whorfian hypothesis