Aerodynamic performance of a bypass engine with fan nozzle exit area change by warped chevrons

Variation of the bypass nozzle exit area enables optimization of the turbofan engine operating cycle over a wider range of operational conditions resulting in improved thrust and/or fuel consumption. Two mechanisms for varying the nozzle area have been investigated. The first uses an array of chevrons which when closed, form a full body of revolution and when warped/curved, increase the exit area while forming a serrated trailing edge. The second technique incorporates an axially translating section of the nacelle shroud and uses the change in the nozzle boat-tail radial location with the axial location as a means to vary the nozzle exit area. To analyse the effects on a typical rotor/stator stage, computational fluid dynamics simulations of the NASA Rotor 67, Stator 67A stage integrated into a custom-built nacelle were performed. Nozzles with 8, 12, and 16 chevrons were simulated to evaluate the impact of the variation in geometry upon the nacelle wake and local forces. Gross thrust of the nacelle and the turbulent kinetic energy (TKE) variation through the wake is compared. The chevron nozzle attains a nearly 2 per cent maximum thrust improvement over the translating nozzle technique. The chevron nozzle also has significantly lower (nearly 8 per cent) peak TKE levels in the jet plume.

Numerical Investigation of Optimal Pin Actuator Location on a Supersonic Projectile

The flowfield around a supersonic projectile using a pin actuator control method has been predicted using computational fluid dynamics. It has been predicted using both viscous and inviscid methods for a number of positions. Both methods showed that an optimal longitudinal position exists. However, the inviscid model over-predicted the lateral acceleration due to the difference in shock formation around the pin between the two approaches. The optimal location was predicted independent of solver, however the higher-fidelity solver predicted lower achievable lateral accelerations. This is due to the viscous interactions caused by the pin. The effect of projectile orientation has shown that shielding the pin leads to reduced effectiveness due to the wake of the fin enveloping the pin. When the pin is exposed to onset flow, the forces achieved are increased. There is also an increase in the achievable forces and moments with increasing Mach number.

Observation of plasma density dependence of electromagnetic soliton excitation by an intense laser pulse

The experimental evidence of the correlation between the initial electron density of the plasma and electromagnetic soliton excitation at the wake of an intense (10(19) W/cm(2)) and short (1 ps) laser pulse is presented. The spatial distribution of the solitons, together with their late time evolution into post-solitons, is found to be dependent upon the background plasma parameters, in agreement with published analytical and numerical findings. The measured temporal evolution and electrostatic field distribution of the structures are consistent with their late time evolution and the occurrence of multiple merging of neighboring post-solitons. (C) 2011 American Institute of Physics. [doi:10.1063/1.3625261]

The Battle of the Somme in Ulster memory and identity

One of the enduring illusions about Northern Ireland is that its society can be conceptualized through a binary distinction between protestant and catholic. unionist and nationalist. It is increasingly apparent that these broad domains are themselves fractured and diverse and that otherness is often conceived from within rather than without. Northern Ireland can also be viewed as a laboratory for identity formation as unionists and loyalists strive to reconcile themselves with the fundamental political changes that have followed in the wake of the Peace Process. This paper considers one aspect of the contestation of belonging that increasingly characterizes unionism. It examines the competition for the ownership of the mythology of the Battle of the Somme ( 1916), long a key event in the unionist narrative. In particular, the paper addresses the ways in which paramilitary organizations are using the Somme to legitimate their own activities but also to distance the loyalist working classes from the former hegemonic Britishness of official unionism and the sectarianism of the Orange Order. The analysis concludes that loyalist identity is being conceptualized thorough a narrative of betrayal from within and at an intensely localized scale.

TheShifting Sands of Uncertainty: Risk Construction and BSE/vCJD

It is more than a decade since scientists in the UK put forward evidence of a link between the emergence of a new variant of Creutzfeldt-Jakob Disease (vCJD) in humans, and a diminishing epidemic of Bovine Spongiform Encephalopathy, or BSE, in cattle. In the wake of this anniversary, the paper revisits two scientific narratives of risk, forged at different points along the developmental pathway of BSE science, including a series of advisory reports provided to the UK government between 1989 and 1994, and a symposium held in 2001 to assess the impact of the Phillips Inquiry. While the primary pathology of BSE became apparent relatively early on, uncertainties remain about the origins of BSE and its human variant, vCJD. The paper examines the handling of this sensitivity, and its communication, within these key documents, noting changes in patterns of uncertainty construction over time.

Tunable Enhancement of High Harmonic Emission from Laser Solid Interactions

Coherent wake emission is a unique source of extreme ultraviolet radiation and has been recently shown to provide the basis for intense attosecond light. Here we present a novel scheme, supported by particle-in-cell simulations, demonstrating that enhancement and spectral control of the coherent wake emission signal can be achieved by modifying the interaction plasma density ramp. Significant tunable enhancement of harmonic emission is verified experimentally, with factors of > 50 in relative signal increase achieved in a narrow band of harmonics at the cutoff frequency.

High-energy electron beam production by femtosecond laser interactions with exploding-foil plasmas

The interaction of an ultraintense, 30-fs laser pulse with a preformed plasma was investigated as a method of producing a beam of high-energy electrons. We used thin foil targets that are exploded by the laser amplified spontaneous emission preceding the main pulse. Optical diagnostics show that the main pulse interacts with a plasma whose density is well below the critical density. By varying the foil thickness, we were able to obtain a substantial emission of electrons in a narrow cone along the laser direction with a typical energy well above the laser ponderomotive potential. These results are explained in terms of wake-field acceleration.

'Mining money': science, legal technologies & working the borderlands of global finance

This paper explores the roles of science and market devices in the commodification of ‘nature’ and the configuration of flows of speculative capital. It focuses on mineral prospecting and the market for shares in ‘junior’ mining companies. In recent years these companies have expanded the reach of their exploration activities overseas, taking advantage of innovations in exploration methodologies and the liberalisation of fiscal and property regimes in ‘emerging’ mineral rich developing countries. Recent literature has explored how the reconfiguration of notions of ‘risk’ has structured the uneven distribution of rents. It is increasingly evident that neoliberal framing of environmental, political, social and economic risks has set in motion overflows that multinational mining capital had not bargained for (e.g. nationalisation, violence and political resistance). However, the role of ‘geological risk’ in animating flows of mining finance is often assumed as a ‘technical’ given. Yet geological knowledge claims, translated locally, designed to travel globally, assemble heterogeneous elements within distanciated regimes of metrology, valuation and commodity production. This paper explores how knowledge of nature is enrolled within systems of property relations, focusing on the genealogy of the knowledge practices that animate contemporary circuits of speculative mining finance. It argues that the financing of mineral prospecting mobilises pragmatic and situated forms of knowledge rather than actuarially driven calculations that promise predictability. A Canadian public enquiry struck in the wake of scandal associated with Bre-X’s prospecting activities in Indonesia is used to glean insights into the ways in which the construction of a system of public warrant to underpin financial speculation is predicated upon particular subjectivities and the outworking of everyday practices and struggles over ‘value’. Reflection on practical investments in processes of standardisation, rituals of verification and systems of accreditation reveal much about how the materiality of things shape the ways in which regional and global financial circuits are integrated, selectively transforming existing social relations and forms of knowledge production.

Analysis of the 3D zone of flow establishment from a ship’s propeller

In the present study an experimental investigation of the time-averaged velocity and turbulence intensity distributions from a ship’s propeller, in “bollard pull” condition (zero speed of advance), is reported. Previous studies have focused mainly on the velocity profile of not a rotating ship propeller but a plain jet. The velocity profile of a propeller is investigated experimentally in this study.
The velocity measurements were performed in laboratory by using a Laser Doppler Anemometry (LDA). The measurements demonstrated two-peaked ridges velocity profile with a low velocity core at the centre within the near wake. The two-peaked ridges combined to be one-peaked ridge at 3.68 diameters downstream indicating the end of the zone of flow establishment. The study
provides useful information from a rotating ship’s propeller rather than a simplified plain jet to researchers investigating flow velocity generated from a propeller and probably resulting local scouring.

Folate and vitamin B-12: friendly or enemy nutrients for the elderly

In the UK vitamin B-12, deficiency occurs in approximately 20% of adults aged >65 years. This incidence is significantly higher than that among the general population. The reported incidence invariably depends on the criteria of deficiency used, and in fact estimates rise to 24% and 46% among free-living and institutionalised elderly respectively when methylmalonic acid is used as a marker of vitamin B-12 status. The incidence of, and the criteria for diagnosis of, deficiency have drawn much attention recently in the wake of the implementation of folic acid fortification of flour in the USA. This fortification strategy has proved to be extremely successful in increasing folic acid intakes pre-conceptually and thereby reducing the incidence of neural-tube defects among babies born in the USA since 1998. However, in successfully delivering additional folic acid to pregnant women fortification also increases the consumption of folic acid of everyone who consumes products containing flour, including the elderly. It is argued that consuming additional folic acid (as 'synthetic' pteroylglutamic acid) from fortified foods increases the risk of 'masking' megaloblastic anaemia caused by vitamin B-12 deficiency. Thus, a number of issues arise for discussion. Are clinicians forced to rely on megaloblastic anaemia as the only sign of possible vitamin B-12 deficiency? Is serum vitamin B-12 alone adequate to confirm vitamin B-12 deficiency or should other diagnostic markers be used routinely in clinical practice? Is the level of intake of folic acid among the elderly (post-fortification) likely to be so high as to cure or 'mask' the anaemia associated with vitamin B-12 deficiency?.

High-Order Harmonics from Bow Wave Caustics Driven by a High-Intensity Laser

We propose a new mechanism of high-order harmonic generation during an interaction of a high-intensity laser pulse with underdense plasma. A tightly focused laser pulse creates a cavity in plasma pushing electrons aside and exciting the wake wave and the bow wave. At the joint of the cavity wall and the bow wave boundary, an annular spike of electron density is formed. This spike surrounds the cavity and moves together with the laser pulse. Collective motion of electrons in the spike driven by the laser field generates high-order harmonics. A strong localization of the electron spike, its robustness to oscillations imposed by the laser field and, consequently, its ability to produce high-order harmonics is explained by catastrophe theory. The proposed mechanism explains the experimental observations of high-order harmonics with the 9 TW J-KAREN laser (JAEA, Japan) and the 120 TW Astra Gemini laser (CLF RAL, UK) [A. S. Pirozhkov, et al., arXiv:1004.4514 (2010); A. S. Pirozhkov et al, AIP Proceedings, this volume]. The theory is corroborated by high-resolution two- and three-dimensional particle-in-cell simulations.

Mitigation of Fatigue Damage in Self-Healing Vascular Materials

The fatigue response of an epoxy matrix containing vasculature for the delivery of liquid healing agents is investigated. The release of a rapidly curing, two-part epoxy healing chemistry into the wake of a propagating crack reduces the rate of crack extension by shielding the crack tip from the full range of applied stress intensity factor. Crack propagation is studied for a variety of loading conditions, with the maximum applied stress intensity factor ranging from 62 to 84% of the quasi-static fracture toughness of the material. At the highest level of applied load, the rate of mechanical damage is so fast that the healing agents do not fully mix and polymerize, and the effect of healing is minimal. The self-healing response is most effective at impeding the slower propagating cracks, with complete crack arrest occurring at the lowest level of applied load, and reductions of 79–84% in the rate of crack extension at intermediate loads.

The rebirth of dependence– offering an alternative understanding of the financial crisis

Purpose – This article aims to contribute to the re-evaluation of the global market system using a Marxist inspired theory of development, dependency.

Design/methodology/approach – This article draws on dependency theory as an alternative means of understanding global relationships. Building on existing literature, it modifies dependency to encapsulate technological developments and trends in the global market.

Findings – Re-evaluating the global market and the relationships that underpin it, through an alternative theory, highlights the fragility of markets and associated relationships. Increasingly, nation states are becoming irrelevant. This presents a problem as the main actors in the global market today are “above” inter-state relations, yet the organs that regulate their behaviour still are grounded in inter-state rhetoric. The relationship between development and underdevelopment remains.

Research limitations/implications – The financial crisis has propagated a wealth of interest in the relationships between states, between multi-national corporations (MNCs) and between MNCs and state. Using this broad theory of modified dependency, it can be applied to a range of different relationships. In the wake of financial crisis, there is the opportunity to raise awareness of these ingrained issues and initiate discussions at national, regional and international levels to alleviate some of the conditions of dependence.

Practical implications – Regardless of the work of national governments and NGOs to instigate development in lesser-developed regions through policy and regulations, unless there is a conscientious commitment from MNCs operating in that region to contribute to development, the result will be the development of underdevelopment and the underdevelopment of development. CSR can help alleviate the conditions of the dependence on capital generated by MNCs, but this is not a solution to an ingrained problem, capitalism.

Originality/value – This article introduces a modified theory of dependency for the first time. It applies the theory to the financial crisis and to the continent of Africa. It considers the role that CSR can play in alleviating the conditions of dependence.