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.

Changes in muscle sympathetic nerve activity and vascular responses evoked in the spinotrapezius muscle of the rat by systemic hypoxia.

Responses evoked in muscle sympathetic nerve activity (MSNA) by systemic hypoxia have received relatively little attention. Moreover, MSNA is generally identified from firing characteristics in fibres supplying whole limbs: their actual destination is not determined. We aimed to address these limitations by using a novel preparation of spinotrapezius muscle in anaesthetised rats. By using focal recording electrodes, multi-unit and discriminated single unit activity were recorded from the surface of arterial vessels. This had cardiac- and respiratory-related activities expected of MSNA, and was increased by baroreceptor unloading, decreased by baroreceptor stimulation and abolished by autonomic ganglion blockade. Progressive, graded hypoxia (breathing sequentially 12, 10, 8% O2 for 2 min each) evoked graded increases in MSNA. In single units, mean firing frequency increased from 0.2 ± 0.04 in 21% O2 to 0.62 ± 0.14 Hz in 8% O2, while instantaneous frequencies ranged from 0.04–6 Hz in 21% O2 to 0.09–20 Hz in 8% O2. Concomitantly, arterial pressure (ABP), fell and heart rate (HR) and respiratory frequency (RF) increased progressively, while spinotrapezius vascular resistance (SVR) decreased (Spinotrapezius blood flow/ABP), indicating muscle vasodilatation. During 8% O2 for 10 min, the falls in ABP and SVR were maintained, but RF, HR and MSNA waned towards baselines from the second to the tenth minute. Thus, we directly show that MSNA increases during systemic hypoxia to an extent that is mainly determined by the increases in peripheral chemoreceptor stimulation and respiratory drive, but its vasoconstrictor effects on muscle vasculature are largely blunted by local dilator influences, despite high instantaneous frequencies in single fibres.

Non Classical Design in MOSFETs for Improving OTA gain-bandwidth trade off

In this paper, gain-bandwidth (GB) trade-off associated with analog device/circuit design due to conflicting requirements for enhancing gain and cutoff frequency is examined. It is demonstrated that the use of a nonclassical source/drain (S/D) profile (also known as underlap channel) can alleviate the GB trade-off associated with analog design. Operational transconductance amplifier (OTA) with 60 nm underlap S/D MOSFETs achieve 15 dB higher open loop voltage gain along with three times higher cutoff frequency as compared to OTA with classical nonunderlap S/D regions. Underlap design provides a methodology for scaling analog devices into the sub-100 nm regime and is advantageous for high temperature applications with OTA, preserving functionality up to 540 K. Advantages of underlap architecture over graded channel (GC) or laterally asymmetric channel (LAC) design in terms of GB behavior are demonstrated. Impact of transistor structural parameters on the performance of OTA is also analyzed. Results show that underlap OTAs designed with spacer-to-straggle ratio of 3.2 and operated below a bias current of 80 microamps demonstrate optimum performance. The present work provides new opportunities for realizing future ultra wide band OTA design with underlap DG MOSFETs in silicon-on-insulator (SOI) technology. Index Terms—Analog/RF, double gate, gain-bandwidth product, .

The back 2 activity trial: education and advice versus education and advice plus a structured walking programme for chronic low back pain.:education and advice versus education and advice plus a structured walking programme for chronic low back pain

BACKGROUND: Current evidence supports the use of exercise-based treatment for chronic low back pain that encourages the patient to assume an active role in their recovery. Walking has been shown it to be an acceptable type of exercise with a low risk of injury. However, it is not known whether structured physical activity programmes are any more effective than giving advice to remain active.

METHODS/DESIGN: The proposed study will test the feasibility of using a pedometer-driven walking programme, as an adjunct to a standard education and advice session in participants with chronic low back pain. Fifty adult participants will be recruited via a number of different sources. Baseline outcome measures including self reported function; objective physical activity levels; fear-avoidance beliefs and health-related quality of life will be recorded. Eligible participants will be randomly allocated under strict, double blind conditions to one of two treatments groups. Participants in group A will receive a single education and advice session with a physiotherapist based on the content of the 'Back Book'. Participants in group B will receive the same education and advice session. In addition, they will also receive a graded pedometer-driven walking programme prescribed by the physiotherapist. Follow up outcomes will be recorded by the same researcher, who will remain blinded to group allocation, at eight weeks and six months post randomisation. A qualitative exploration of participants' perception of walking will also be examined by use of focus groups at the end of the intervention. As a feasibility study, treatment effects will be represented by point estimates and confidence intervals. The assessment of participant satisfaction will be tabulated, as will adherence levels and any recorded difficulties or adverse events experienced by the participants or therapists. This information will be used to modify the planned interventions to be used in a larger randomised controlled trial.

DISCUSSION: This paper describes the rationale and design of a study which will test the feasibility of using a structured, pedometer-driven walking programme in participants with chronic low back pain.

TRIAL REGISTRATION: [ISRCTN67030896].

Comparison of Experimental PIV Data and CFD Simulations for Flow in a Diesel Particulate Filter Inlet Diffuser

Flow maldistribution of the exhaust gas entering a Diesel Particulate Filter (DPF) can cause uneven soot distribution during loading and excessive temperature gradients during the regeneration phase. Minimising the magnitude of this maldistribution is therefore an important consideration in the design of the inlet pipe and diffuser, particularly in situations where packaging constraints dictate bends in the inlet pipe close to the filter, or a sharp diffuser angle. This paper describes the use of Particle Image Velocimetry (PIV) to validate a Computational Fluid Dynamic (CFD) model of the flow within the inlet diffuser of a DPF so that CFD can be used with confidence as a tool to minimise this flow maldistribution. PIV is used to study the flow of gas into a DPF over a range of steady state flow conditions. The distribution of flow approaching the front face of the substrate was of particular interest to this study. Optically clear diffusing cones were designed and placed between pipe and substrate to allow PIV analysis to take place. Stereoscopic PIV was used to eliminate any error produced by the optical aberrations caused by looking through the curved wall of the inlet cone. In parallel to the experiments, numerical analysis was carried out using a CFD program with an incorporated DPF model. Boundary conditions for the CFD simulations were taken from the experimental data, allowing an experimental validation of the numerical results. The CFD model incorporated a DPF model, the cement layers seen in segmented filters and the intumescent matting that is commonly used to pack the filter into a metal casing. The mesh contained approximately 580,000 cells and used the realizable ?-e turbulence model. The CFD simulation predicted both pressure drop across the DPF and the velocity field within the cone and at the DPF face with reasonable accuracy, providing confidence in the use the CFD in future work to design new, more efficient cones.

Simple method for the rapid simultaneous screening of photocatalytic activity over multiple positions of self-cleaning films

An intelligent ink, previously shown to be capable of rapidly assessing photocatalytic activity, was simply applied via a felt-pen onto a commercially available piece of Activ (TM) self-cleaning glass. The ink, comprising of redox dye resazurin and the sacrificial electron donor glycerol within an aqueous hydroxy ethyl cellulose (HEC) polymer media, was photocatalytically degraded in a two-step process. The key initial stage was the photo-reductive conversion of resazurin to resorufin, whereby a colour change from blue to pink occurred. The latter stage was the subsequent photo-reduction of the resorufin, where a slower change from pink to colourless was seen. Red and green components of red-green-blue colour extracted from flat-bed scanner digital images of resazurin ink coated photocatalytic films at intervals during the photocatalysis reaction were inversely proportional to the changes seen via UV-visible absorption spectroscopy and indicative of reaction kinetics. A 3 x 3 grid of intelligent ink was drawn onto a piece of Activ (TM) and a glass blank. The photocatalysis reaction was monitored solely by flat-bed digital scanning. Red-green-blue values of respective positions on the grid were extracted using a custom-built program entitled RGB Extractor (c). The program was capable of extracting a number of 5 x 5 pixel averages of red-green-blue components simultaneously. Allocation of merely three coordinates allowed for the automatic generation of a grid, with scroll-bars controlling the number of positions to be extracted on the grid formed. No significant change in red and green components for any position on the glass blank was observed; however, the Activ (TM) film displayed a homogenous photo-reduction of the dye, reaching maxima in red and minima in green components in 23 +/- 3 and 14 +/- 2 min, respectively. A compositionally graded N-doped titania film synthesised in house via a combinatorial APCVD reaction was also photocatalytically tested by this method where 247 positions on a 13 x 19 grid were simultaneously analysed. The dramatic variation in photocatalysis observed was rapidly quantified for all positions (2-3 hours) allowing for correlations to be made between thicknesses and N : Ti% compositions attained from Swanepoel and WDX analysis, respectively. N incorporation within this system was found to be detrimental to film activity for the photocatalysis reaction of intelligent ink under 365 nm light.

Near-field spatial imaging of a Ni-like Ag 140-angstrom x-ray laser

We measure the two-dimensional, near-field spatial distribution of a 140-Angstrom nickel-like silver x-ray laser at the output aperture with high magnification using a curved multilayer x-ray mirror to image the output onto an x-ray charge-coupled device camera. Lasing is created by illuminating silver slab targets with a pair of 75 ps laser pulses separated by 2.2 nsec from the Vulcan laser. The two-dimensional, high-resolution, spatial image shows the x-ray laser source size and its position relative to the target surface. A dramatic change in both the position and source size are observed for the refraction compensating curved target as compared with the flat targets.

A NOVEL LIFE-HISTORY IN AGLAOTHAMNION-DIAPHANUM-SP NOV (CERAMIACEAE, RHODOPHYTA) FROM BRITTANY AND THE BRITISH-ISLES

A diminutive species of Aglaothamnion (Ceramiaceae, Rhodophyta), A. diaphanum sp. nov., is described from Brittany (Atlantic France), the Isles of Scilly (off S.W. England) and western Ireland. Aglaothamnion diaphanum is confined to the sublittoral zone, where it grows almost exclusively on algae and sessile animals attached to hard substrata. Thalli are delicate, and branched distichously in one plane. The main axes are ecorticate but may form loose non-corticating rhizoidal filaments. The lateral branches bear a characteristic, regularly alternate distichous series of branchlets, the first of which is always adaxial. All vegetative cells are uninucleate. The majority of field-collected plants bear only bisporangia, but a few bisporangial plants also form spermatangia; some male plants and a single female specimen have been collected. The spermatangial branchlets consist of 3-5 spermatangial mother cells each bearing 2-4 spermatangia, which are constricted around a central nucleus. None of the U-shaped carpogonial branches showed any sign of fertilization, and the gametangia appear to be non-functional. The bisporangia are ovoid and contain two uninucleate spores separated by an oblique curved wall. The occurrence of bisporangia and the lack of adherent cortication distinguish A. diaphanum from two similar species, Aglaothamnion bipinnatum (P. Crouan et H. Crouan) Feldmann-Mazoyer and Aglaothamnion decompositum (J. Agardh) Halos. The life history in culture of French and Irish isolates of A. diaphanum consists of a series of bisporangial generations, a single plant of which also formed spermatangia. Apical cells of bisporophytes are haploid (n = c. 32), but the first division of meiosis, with chromosome pairing and crossing over, occurs in dividing bisporocytes. The germinating bispores are haploid. Endodiploidization may occur in the early stages of sporangium development, as in some phycomycete fungi, or in vegetative cells that subsequently give rise to bisporocytes. This is the first demonstration in the red algae of meiotic bisporangia on plants of which the apical cells, at least, are haploid.

More equitable systems for allocating general practice deprivation payments:financial consequences

The allocation of general practitioner (GP) deprivation payments has been a controversial topic since they were first proposed. It has recently been suggested that the current system could be made more equitable if the payments were allocated at enumeration districts and if there was a more graded relationship between Jarman score and funding. However, the implications of these changes on the distribution of deprivation payments have not been worked out.