Theory of hydrogen in liquid and solid metals

A method for calculating the interatomic forces between isolated hydrogens and their host metal atoms is outlined. The method uses a semiempirical, molecular-orbital approach for a suitable cluster of atoms, with the empirical parameters fitted to experimental potential energy curves for diatomic molecules. Parameters suitable for hydrogen in liquid or solid Li and Na are given. The method is applied to the calculation of solvation energies of hydrogen in liquid Li and Na, where satisfactory agreement with experiment is obtained. Detailed potential energy surfaces are also found for H in solid Na and estimates are made of local mode frequencies, the stability of the tetrahedral sites, lattice relaxation, and effective charges, and atomic radii. Neither the anionic nor the protonic limit is appropriate. It has not proved possible to describe the potential energy surfaces in terms of a sum of twobody and volume-dependent terms alone

Using the markstrat business simulation to develop strategic management behaviours

It is well understood that experiential learning provides an incentive and impetus for accelerated learning, especially in humanities and business-focussed studies. ICT-based synthetic and virtual environments can provide a rich and varied context within which to achieve this. Specifically, this paper attempts to provide empirical, survey-based analysis of the application of a business simulation game, MarkStrat, on undergraduate and postgraduate programmes in this vein. The paper subsequently posits the pedagogic benefit of using such business simulation games for the development of strategic management behaviours across student sample populations and derives subsequent results to highlight associated learning behaviours

INTERSTITIAL MUONS AND HYDROGEN IN DIAMOND AND SILICON

The authors have calculated self-consistent total-energy surface for hydrogen present interstitially as H+, H0 and H2 in crystalline silicon and diamond. The dissimilarities of the two materials are more evident than their similarities, for they show molecular hydrogen to be the stable form in silicon, and atomic hydrogen to be the stable form in diamond in the absence of impurities. The energy surfaces for H0 and H+ are complex, with minima too small to trap the atoms when zero-point energy is taken into account. They discuss their results in relation to other theories and to the normal and anomalous muonium ( mu +e-) experiments

Editorial: Embodied cognition over the lifespan. Theoretical issues and implications for applied settings

The editorial introduces The Special Topic on Embodied Cognition over the Lifespan and in Applied Settings. The Topic aimed at gathering evidence on the role of EC in development, adulthood, and aging, and to shed light on the applied fields benefiting from this approach

DIMENSION CHANGES DUE TO ALIGNED VK-CENTERS AND H-CENTERS IN IONIC-CRYSTALS

When anisotropic defects are aligned, the dimensions of the host crystal parallel and perpendicular to the defect axis are changed, an effect observed previously for H centres and Vk centres in KCl. The authors have calculated the effect for H centres and Vk centres in several crystal structures. The contribution from long-range Coulomb interactions has been obtained in all cases, with less-detailed estimates of short-range repulsion and covalency effects in special cases. The predictions are in good agreement with experiment for H centres in KCl, but agree only poorly for Vk centres in the same host. The discrepancy appears to arise from modifications of the local repulsive forces near the defect. Measurements of dimension changes show great promise for studies of such interatomic forces

The knowledge management kaleidoscope: Keeping stakeholders and their expectations in focus

information systems field. Over many years the roots and foundations of the definition of knowledge and its constructs have upheld the view that knowledge is an amorphous entity to be harnessed in its abundance. This developmental paper argues that knowledge is context sensitive and reliant upon an inter-relationship between stakeholders, their expectations, and associated organisational cultural factors which are modified by the lens of organisational context. By using the systems dynamics concept of the Eroding Goals systems archetype, a conceptual model- the Knowledge Management Kaleidoscope - is developed to explain and describe these components as an alternative model of identifying knowledge

Interstitial muons and hydrogen in crystalline silicon

We have calculated self-consistent total energy surfaces for H+, H° and H2 present interstitially in crystalline Si. We conclude molecular hydrogen is the stable form consistent with the lack of observed electrical and optical activity. Both H+ and H° have complex surfaces, with some features sensitive to lattice distortion. The local minima are too small to give localised states when zero-point energy is included. We discuss our results in relation to earlier theories and to experiments on “normal” and “anomalous” muonium [μ+e-]

Robocrystallographer: Automated crystal structure text descriptions and analysis

Our ability to describe crystal structure features is of crucial importance when attempting to understand structure-property relationships in the solid state. In this paper, the authors introduce robocrystallographer, an open-source toolkit for analyzing crystal structures. This package combines new and existing open-source analysis tools to provide structural information, including the local coordination and polyhedral type, polyhedral connectivity, octahedral tilt angles, component-dimensionality, and molecule-within-crystal and fuzzy prototype identification. Using this information, robocrystallographer can generate text-based descriptions of crystal structures that resemble descriptions written by human crystallographers. The authors use robocrystallographer to investigate the dimensionalities of all compounds in the Materials Project database and highlight its potential in machine learning studies

Blast mines: physics, injury mechanisms and vehicle protection.

Since World War II, more vehicles have been lost to land mines than all other threats combined. Anti-vehicular (AV) mines are capable of disabling a heavy vehicle, or completely destroying a lighter vehicle. The most common form of AV mine is the blast mine, which uses a large amount of explosive to directly damage the target. In a conventional military setting, landmines are used as a defensive force-multiplier and to restrict the movements of the opposing force. They are relatively cheap to purchase and easy to acquire, hence landmines are also potent weapons in the insurgents armamentarium. The stand-offnature of its design has allowed insurgents to cause significant injuries to security forces in current conflicts with little personal risk. As a result, AV mines and improvised explosive devices (IEDs) have become the most common cause of death and injury to Coalition and local security forces operating in Iraq and Afghanistan. Detonation of an AV mine causes an explosive, exothermic reaction which results in the formation of a shockwave followed by a rapid expansion of gases. The shockwave is mainly reflected by the soillair interface and fractures the soil cap overthe mine. The detonation products then vent through the voids in the soil, resulting in a hollow inverse cone which consists of the detonation gases surrounded by the soil ejecta. It is the combination of the detonation products and soil ejecta that interact with the target vehicle and cause injury to the vehicle occupants. A number of different strategies are required to mitigate the blast effects of an explosion. Primary blast effects can be reduced by increasing the standoff distance between the seat of the explosion and the crew compartment. Enhancement of armour on the base of the vehicle, as well as improvements in personal protection can prevent penetration of fragments. Mitigating tertiary effects can be achieved by altering the vehicle geometry and structure, increasing vehicle mass, as well as developing new strategies to reduce the transfer of the impulse through the vehicle to the occupants. Protection from thermal injury can be provided by incorporating fire resistant materials into the vehicle and in personal clothing. The challenge for the vehicle designer is the incorporation of these protective measures within an operationally effective platform.Published versio