EAGLEView: A surface and grid generation program and its data management

An old and proven grid generation code, the EAGLE grid generation package, is given an added dimension of a graphical interface and a real time data base manager. The Numerical Aerodynamic Simulation (NAS) Panel Library is used for the graphical user interface. Through the panels, EAGLEView constructs the EAGLE script command and sends it to EAGLE to be processed. After the object is created, the script is saved in a mini-buffer which can be edited and/or saved and reinterpreted. The graphical objects are set-up in a linked-list and can be selected or queried by pointing and clicking the mouse. The added graphical enhancement to the EAGLE system emphasizes the unique capability to construct field points around complex geometry and visualize the construction every step of the way

Impedance of a sphere oscillating in an elastic medium with and without slip

The dynamic impedance of a sphere oscillating in an elastic medium is considered. Oestreicher's formula for the impedance of a sphere bonded to the surrounding medium can be expressed simply in terms of three lumped impedances associated with the displaced mass and the longitudinal and transverse waves. If the surface of the sphere slips while the normal velocity remains continuous, the impedance formula is modified by adjusting the definition of the transverse impedance to include the interfacial impedance.Comment: 10 pages, 2 figure

Stochastic Stokes' drift of a flexible dumbbell

We consider the stochastic Stokes drift of a flexible dumbbell. The dumbbell consists of two isotropic Brownian particles connected by a linear spring with zero natural length, and is advected by a sinusoidal wave. We find an asymptotic approximation for the Stokes drift in the limit of a weak wave, and find good agreement with the results of a Monte Carlo simulation. We show that it is possible to use this effect to sort particles by their flexibility even when all the particles have the same diffusivity.Comment: 12 pages, 1 figur

Standard comparison test procedures for initiator output

Standard test procedures for initiators of explosive device

The Effect of Retro-Cueing on an ERP Marker of VSTM Maintenance

Previous research has found that Contralateral Delay Activity (CDA) is correlated with the number of items maintained in Visual Short Term Memory from one visual field (VF) (Vogel & Machizawa, 2004). CDA is usually elicited by a to-be-remembered array after a prospective cue (pro-cue) signalling the relevant side of the visual display, and is interpreted as a putative electrophysiological signature of WM maintenance. Attention can also be directed to the contents of VSTM, after the presentation of a visual array, using a retroactive cue (retro-cue) (Nobre, Griffin, & Rao, 2008). Because retro-cueing directs attention within a memory trace, potentially reducing the load of items to be maintained, we hypothesised that this would significantly attenuate the CDA. Participants were initially presented with a spatial pro-cue which reduced the number of to-be-remembered items to one side. After a delay, a memory array of either four (low load) or eight (high load) items was displayed. A retro-cue then cued participants to one location within the relevant VF, further reducing the load of to-be-remembered items; or provided no information, requiring participants to hold all items in the relevant VF. At the end of the trial, participants performed a same/different judgement on a test stimulus. Retro-cues significantly improved VSTM performance. Unexpectedly, the CDA was found to be abolished by the presentation of both spatially predictive and neutral cues, independently of the VSTM load participants had to maintain

Thin-film flow in helically wound rectangular channels with small torsion

Laminar gravity-driven thin-film flow down a helically-wound channel of rectangular cross-section with small torsion in which the fluid depth is small is considered. Neglecting the entrance and exit regions we obtain the steady-state solution that is independent of position along the axis of the channel, so that the flow, which comprises a primary flow in the direction of the axis of the channel and a secondary flow in the cross-sectional plane, depends only on position in the two-dimensional cross-section of the channel. A thin-film approximation yields explicit expressions for the fluid velocity and pressure in terms of the free-surface shape, the latter satisfying a non-linear ordinary differential equation that has a simple exact solution in the special case of a channel of rectangular cross-section. The predictions of the thin-film model are shown to be in good agreement with much more computationally intensive solutions of the small-helix-torsion Navier–Stokes equations. The present work has particular relevance to spiral particle separators used in the mineral-processing industry. The validity of an assumption commonly used in modelling flow in spiral separators, namely that the flow in the outer region of the separator cross-section is described by a free vortex, is shown to depend on the problem parameters

The Stochastic Dynamics of Rectangular and V-shaped Atomic Force Microscope Cantilevers in a Viscous Fluid and Near a Solid Boundary

Using a thermodynamic approach based upon the fluctuation-dissipation theorem we quantify the stochastic dynamics of rectangular and V-shaped microscale cantilevers immersed in a viscous fluid. We show that the stochastic cantilever dynamics as measured by the displacement of the cantilever tip or by the angle of the cantilever tip are different. We trace this difference to contributions from the higher modes of the cantilever. We find that contributions from the higher modes are significant in the dynamics of the cantilever tip-angle. For the V-shaped cantilever the resulting flow field is three-dimensional and complex in contrast to what is found for a long and slender rectangular cantilever. Despite this complexity the stochastic dynamics can be predicted using a two-dimensional model with an appropriately chosen length scale. We also quantify the increased fluid dissipation that results as a V-shaped cantilever is brought near a solid planar boundary.Comment: 10 pages, 15 images, corrected equation (8

Acoustic waves: should they be propagated forward in time, or forward in space?

The evolution of acoustic waves can be evaluated in two ways: either as a temporal, or a spatial propagation. Propagating in space provides the considerable advantage of being able to handle dispersion and propagation across interfaces with remarkable efficiency; but propagating in time is more physical and gives correctly behaved reflections and scattering without effort. Which should be chosen in a given situation, and what compromises might have to be made? Here the natural behaviors of each choice of propagation are compared and contrasted for an ordinary second order wave equation, the time-dependent diffusion wave equation, an elastic rod wave equation, and the Stokes'/ van Wijngaarden's equations, each case illuminating a characteristic feature of the technique. Either choice of propagation axis enables a partitioning the wave equation that gives rise to a directional factorization based on a natural "reference" dispersion relation. The resulting exact coupled bidirectional equations then reduce to a single unidirectional first-order wave equation using a simple "slow evolution" assumption that minimizes effect of subsequent approximations, while allowing a direct term-to-term comparison between exact and approximate theories.Comment: 12 pages, v2 correcte

Review 3: Community engagement for health via coalitions, collaborations and partnerships (on-line social media and social networks) – a systematic review and meta-analysis

BACKGROUND: This report describes the methods and findings of a systematic review on community engagement (CE) for health via online social media and social networks. It is the third and final review of a programme of work on the use and effectiveness of CE in interventions that target health outcomes. Social networks are one of many forms of CE. Our first two reviews suggested that the extent and particular processes of CE may be linked to effects on people’s health. The emergence of online, electronic peer-to-peer social network sites (e.g. Facebook) and online social media tools (e.g. Twitter) have increased exponentially in recent years, and existing evidence on their effectiveness is ambiguous. AIMS: We aim to evaluate the effectiveness of online social media/social networks on: the extent of CE across designs, delivery and evaluation; the types of health issues and populations that have been studied; their effectiveness in improving health and wellbeing and reducing health inequalities; and any particular features that account for heterogeneity in effect size estimates across studies. METHODS: Systematic review methods were applied to comprehensively locate and assess the available research evidence. The search strategy employed previously run searches used for Reviews 1 and 2 of this project (described elsewhere). The included studies were descriptively analysed and the findings were synthesised using three components: framework synthesis, meta-analysis and qualitative component analysis (QCA). RESULTS: A total of 11 studies were included in the review, none of which was set in the UK. The community was not explicitly involved in identifying the health need for any of the 11 studies. No studies demonstrated a high level of CE, where participants were involved in the three measured elements: design, delivery and evaluation. Framework analysis indicated that peer delivery of the intervention was the predominant type of CE. Two processes of CE were reported – bidirectional communication and the use of facilitators – but none of the studies evaluated these processes. Professional facilitators were used more often in healthy eating/physical activity studies. Peer facilitators were used more often in youth-focused interventions and professional facilitators were utilised more frequently for interventions targeting older populations. Studies focusing on women only may incorporate peer or professional facilitators to aid intervention delivery. Peer or professional facilitators were used slightly more consistently in interventions targeting minority ethnic groups. Meta-analyses and meta-regression showed no evidence of beneficial effects on any outcomes. There was moderate (I 2 = 25≤50) to high (I 2 = ≥50) heterogeneity between studies for primary outcomes, suggesting the existence of potential moderators. None of the tested study characteristics explained the variation in effect sizes. The QCA demonstrated that including a facilitator in online social media/social networking interventions showed higher effect sizes for studies that focused on topics other than healthy eating and physical activity. CONCLUSIONS: The results from this study suggest that CE is not utilised across the design or evaluation of health interventions, and the type of CE undertaken with intervention delivery focuses on peer interactions alone. This suggests that there is very little co-creation of knowledge or building of social capital occurring in evaluated health intervention studies using online social media/networking