Edinburgh Napier University

About: Edinburgh Napier University is a education organization based out in Edinburgh, United Kingdom. It is known for research contribution in the topics: Population & Health care. The organization has 2665 authors who have published 6859 publications receiving 175272 citations.

Eddy and deep chlorophyl maximum response to wind-shear in the lee of Gran Canaria

Abstract: The physical and biological properties of the warm wake of Gran Canaria were examined during a survey carried out in June 1998. The sampling region was dominated by the presence of a warm triangular region downwind the island and an anticyclonic eddy spun off the island. Convergent and divergent frontal regions were generated by the wind shear zones extending along either side of the sheltered region of the warm wake. With increasing distance from shore, evidence of convergent/divergent frontal regions weakened, but the influence of the eddy increased. Both structures, frontal regions and the eddy, clearly altered the vertical phytoplankton biomass distribution as indicated by chlorophyll-fluorescence. Downwelling on the convergent boundary moved the 26.2 kg m � 3 isopycnal and its associated deep chlorophyll maximum (DCM) below the 1% light zone. Upwelling at the divergent boundary not only elevated the DCM with its associated isopycnal but also, because of the increased light levels, allowed a shift in the DCM to higher (deeper) density surfaces (26.4 kg m � 3 ). However, the highest integrated chlorophyll occurred in the

Progressing socio‐cultural impact evaluation for festivals

Abstract: The research project reported in this paper set out to advance the knowledge base of socio‐cultural festival evaluation and, through industry and academic liaison, produce a robust, comprehensive set of indicators. The purpose of this paper is threefold: first, to offer a summary of the synthesis of literature relating to methodologies for evaluating the socio‐cultural effects of festivals; second, to identify the emerging themes resulting from the existing literature; and third, as part of an evaluation of stakeholder perception, to present a comparative rating of a UK‐wide cross‐section of festival leaders (n = 60) of core impacts and their significance. The methods adopted were based on a comprehensive review of secondary literature in relation to the evaluation of socio‐cultural impacts of festivals, followed by telephone interviews with a sample of UK festival directors. Keywords: festivals and events; socio‐cultural benefits and disbenefits; indicators; festival directors; aggregative synthesis Abst...

Trust-aware and cooperative routing protocol for IoT security

Abstract: The resource-constrained nature of IoT objects makes the Routing Protocol for Low-power and Lossy Networks (RPL) vulnerable to several attacks. Although RPL specification provides encryption protection to control messages, RPL is still vulnerable to internal attackers and selfish behaviours. To address the lack of robust security mechanisms in RPL, we design a new Metric-based RPL Trustworthiness Scheme (MRTS) that introduces trust evaluation for secure routing topology construction. Extensive simulations show that MRTS is efficient in terms of packet delivery ratio, energy consumption, nodes’ rank changes, and throughput. In addition, a mathematical modelling analysis shows that MRTS meets the requirements of consistency, optimality, and loop-freeness and that the proposed trust-based routing metric has the isotonicity and monotonicity properties required for a routing protocol. By using game theory concepts, we formally describe MRTS as a strategy for the iterated Prisoner’s Dilemma and demonstrate its cooperation enforcement characteristic. Both mathematical analysis and evolutionary simulation results show clearly that MRTS, as a strategy, is an efficient approach in promoting the stability and the evolution of the Internet of Things network.

The influence of particle-size distribution on critical state behavior of spherical and non-spherical particle assemblies

Abstract: This paper presents an investigation into the effects of particle-size distribution on the critical state behavior of granular materials using discrete element method (DEM) simulations on both spherical and non-spherical particle assemblies. A series of triaxial test DEM simulations examine the influence of particle-size distribution (PSD) and particle shape, which were independently assessed in the analyses presented. Samples were composed of particles with varying shapes characterized by overall regularity (OR) and different PSDs. The samples were subjected to the axial compression through different loading schemes: constant volume, constant mean effective stress, and constant lateral stress. All samples were sheared to large strains to ensure that a critical state was reached. Both the macroscopic and microscopic behaviors in these tests are discussed here within the framework of the anisotropic critical state theory. It is shown that both OR and PSD may affect the response of the granular assemblies in terms of the stress–strain relations, dilatancy, and critical state behaviors. For a given PSD, both the shear strength and fabric norm decrease with an increase in OR. The critical state angle of shearing resistance is highly dependent on particle shape. In terms of PSD, uniformly distributed assemblies mobilize higher shear strength and experience more dilative responses than specimens with a greater variation of particle sizes. The position of the critical state line in the e–p′ space is also affected by PSD. However, the effects of PSD on critical strength and evolution of fabric are negligible. These findings highlight the importance of particle shape and PSD that should be included in the development of constitutive models for granular materials.

Numerical modelling of the shelf break ecosystem: reproducing benthic and pelagic measurements

Abstract: A coupled pelagic-benthic biogeochemical model, embedded in a turbulence-closure formulation is employed for the Goban Spur shelf-break area (northeast Atlantic). Our main objectives are to examine the impact of in situ atmospheric conditions on ecosystem dynamics, to reproduce biogeochemical distributions in the water column and the sediments, and to derive a nitrogen budget for the area. Given a data set of atmospheric forcing conditions at 3-h intervals, the model successfully explains the time evolution of the temperature field. Most biochemical water column properties are reasonably well simulated, both in timing and in magnitude. Some of the short-term variability, apparent in the data, can be reproduced, suggesting that this may result from variability in the in situ atmospheric forcing. In summer, intermittent mixing events generate increased ammonium and nitrate concentrations in the upper water column, consistent with observations. These short-term nutrient injections substantially increase euphotic zone production, mainly by stimulating new production. The model also reproduces a set of benthic nutrient profiles, measured on two occasions, both qualitatively and quantitatively. The results suggest that there is a significant variability in benthic properties. A tentative nitrogen budget for the Goban Spur shelf break area is proposed. The sediments account for about 7% of organic nitrogen respiration; about 42% occurs in the euphotic zone, and the remaining 50% takes place in the water column below the euphotic zone. About 3% of the annual primary production of organic nitrogen is denitrified in the sediments and is replenished from lateral sources in the model. Nitrification mainly takes place in the water column below the euphotic zone (66%); sedimentary nitrification and ammonium oxidation in the euphotic zone both account for 17%. Over the year, only 55% of euphotic zone nitrogen assimilation is based on the in situ regenerated inorganic nitrogen, the remainder is mainly supplied by mixing from below the euphotic zone, either in the form of nitrate (72%) or ammonium (28%). The implications of these nitrogen pathways in the euphotic zone on the measured f-ratio are discussed.