Fuel distribution measurements in a model low NOx double annular combustor using laser induced fluorescence

Planar laser induced fluorescence (PLIF) was employed in a three sector, low NOx double annular combustor in order to characterise the combusting fuel spray. Naphthalene was employed as a fluorescent agent in odourless kerosene in order to determine the behavior of the light fractions in the fuel vapour, and the light to medium fractions in the fuel spray, while 2,5 di-phenyl oxizol (ppo) was employed to determine the behavior of the heavy fractions in the fuel spray. Counter-swirl air blast atomizing fuel injectors employing a nominal fuel spray included cone angle of 90 deg were employed to inject the kerosene fuel into the double annular combustor. Radial and axial measurements were performed on the combusting spray. Spatial variations in fuel spray placement were observed, together with radial anisotropy

The optical characterisation of spray and soot formation in a diesel engine

Laser sheet drop-sizing (LSD) measurements of a Diesel spray and simultaneous laser induced incandescence/Mie scattering measurements of soot have been performed in an optically accessible, common rail, 1.9 litre, turbo-charged, direct injection Diesel engine. The diesel fuel injectors employed in this study were prototype five hole injectors, supplied by R. Bosch. An oxygenated surrogate Diesel fuel with an estimated cetane number of 54 was employed in order to reduce the amount of soot formed during combustion. The prototype five-hole injector employed produced spray jets that were distinguishable in terms of the liquid volume fraction, drop-size distribution and spray penetration distance produced. The soot volume fraction formed during combustion was found to be correlated with drop-size distribution, and local soot particle size distribution was observed to be inversely correlated with local soot volume fraction

Comparison of Achilles tendon loading between male and female recreational runners

Recreational running is an activity with multiple reported health benefits for both sexes, however, chronic injuries caused by excessive and/or repetitive loading of the Achilles tendon are common. Males have been identified as being at an increased risk of suffering an injury to the Achilles tendon and as such, knowledge of differences in loading between the sexes may provide further information to better understand why this is the case. The aim of the current investigation was to determine whether gender differences in the Achilles tendon load exist in recreational runners. Fifteen male (age 26.74 ± 5.52 years, body height 1.80 ± 0.11 m and body mass 74.22 ± 7.27 kg) and fifteen female (age 25.13 ± 6.39 years, body height 1.68 ± 0.12 m and body mass 67.12 ± 9.11 kg) recreational runners volunteered to take part in the current investigation. Participants completed 10 trials running at 4.0 m•s-1 ±5% striking a force platform (1000 Hz) with their right foot. Ankle joint kinematics were synchronously recorded (250 Hz) using an optoelectric motion capture system. Ankle joint kinetics were computed using Newton-Euler inverse-dynamics. Net external ankle joint moments were then calculated. To estimate Achilles tendon kinetics the plantarflexion moment calculated was divided by an estimated Achilles tendon moment arm of 0.05 m. Differences in Achilles tendon kinetics were examined using independent sample t-tests (p<0.05). The results indicate that males were associated with significantly (p<0.05) greater Achilles tendon loads than females. The findings from this study support the notion that male recreational runners may be at greater risk of Achilles tendon pathology

2.5-D/3-D resistivity modelling in anisotropic media using Gaussian quadrature grids

We present a new numerical scheme for 2.5-D/3-D direct current resistivity modelling in heterogeneous, anisotropic media. This method, named the ‘Gaussian quadrature grid' (GQG) method, cooperatively combines the solution of the Variational Principle of the partial differential equation, Gaussian quadrature abscissae and local cardinal functions so that it has the main advantages of the spectral element method. The formulation shows that the GQG method is a modification of the spectral element method but does not employ the constant elements or require the mesh generator to match the Earth's surface. This makes it much easier to deal with geological models having a 2-D/3-D complex topography than using traditional numerical methods. The GQG technique can achieve a similar convergence rate to the spectral element method. We show it transforms the 2.5-D/3-D resistivity modelling problem into a sparse and symmetric linear equation system that can be solved by an iterative or matrix inversion method. Comparison with analytic solutions for homogeneous isotropic and anisotropic models shows that the error depends on the Gaussian quadrature order (abscissa number) and the subdomain size. The higher the order or the smaller the subdomain size that is employed, the more accurate are the results obtained. Several other synthetic examples, both homogeneous and inhomogeneous, incorporating sloping, undulating and severe topography, are presented and found to yield results comparable to finite element solutions involving a dense mes

Effect of postactivation potentiation on fifty-meter freestyle in national swimmers

Effect of postactivation potentiation (PAP) on fifty meters freestyle in national swimmers. 2013.- The purpose of this study was to examine the effect of PAP on 50m freestyle in national-level swimmers. Four warm-ups were compared: A traditional race-specific warm-up (RSWU), upper body PAP (UBPAP), lower body PAP (LBPAP) and combined PAP warm-up (CPAP). Eighteen (10 men, 8 women) national-level swimmers participated in this study, which included seven separate testing sessions. Participants' 3 repetition maximum (3RM) of the pull-up (PU) was established in session 1. In session 2, rest periods for muscle enhancement of the upper body were determined using a medicine-ballthrow test 4, 8 and 12 minutes post UBPAP stimulus (1 x 3RM of the PU). In session 3, swimmers performed a counter movement jump 4, 8 and 12 minutes post LBPAP stimulus (1x5 jumps to a box whilst carrying 10% of the participants' body weight). The 50m freestyle tests were performed on sessions 4 to 7, preceded by each warm-up protocol and corresponding rest periods. A repeated measures ANOVA (p<0.05) and Bonferroni post hoc test revealed that RSWU elicited faster swimming times than UBPAP (29.00 ± 2.05 vs. 29.36 ± 1.88s p=0.046). Additionally, when data were split into gender, in the male group the UBPAP elicited significantly slower times than RSWU (27.51 ± 1.06 vs. 28.01 ± 1.17s p=0.047) and CPAP (27.49 ± 1.12 vs. 28.01 ± 1.17s p=0.02). These findings suggest individualized PAP warm-up may be a valuable tool to enhance performance in sprint events, particularly in male swimmers. However, the PU may not be an appropriate PAP stimulus on its own

The effect of shoe toe box shape and volume on forefoot interdigital and plantar pressures in healthy females

Ill-fitting footwear can be detrimental to foot health with the forefoot being an area for most discomfort. Studies on footwear have primarily examined sports or orthopaedic prescription shoes and little is known about the effects that everyday flat shoes have on the forefoot. The aim of this study was to investigate the effect of toe box shape in a popular slip-on pump on dorsal and plantar pressures with particular interest around the forefoot in a healthy female population

The influence of different force and pressure measuring transducers on lower extremity kinematics measured during walking

The examination of synchronous three dimensional (3-D) kinetics and kinematics of walking in laboratory based analyses typically requires participants/patients to make foot contact with a force or pressure measuring device. However it has been proposed that this may lead to targeting whereby participants modify their natural gait pattern in order to ensure contact with the device. This study aimed to determine the extent to which an embedded force plate (EFP) and two different pressure mats PMs affect natural gait kinematics. Male participants (n=12, age 24.23 SD 4.22 y, height 1.74m SD 0.10, mass 75.78 SD 6.90kg) walked at a velocity of 1.25 m.s-1 along a 22m walkway in four different conditions. 1. EFP, 2. FootScan (FS) PM, 3.Matscan (MS) PM, 4.No device (ND). 3-D angular kinematic parameters were collected using an eight camera motion analysis system.Differences in kinematics were examined using repeated measures ANOVAs. Significant differences were observed in hip abduction, knee flexion/extension and knee abduction between various conditions and may warrant consideration in future research. No significant differences were reported at the ankle joint in any conditions. Comparing the PMs no significant differences were observed, however significant differences between the MS and the EFP and ND conditions were identified. The research supports the efficacy of collecting gait kinematics at the ankle joint and in most variables measured at the knee and hip joints

Influence of surface on impact shock experienced during a fencing lunge

The purpose of this study was to investigate the effect of sports surface on the magnitude of impact shock experienced during a lunge movement. Thirteen experienced, competitive fencers (age 32.4 +/- 4.6 years; Height 178.4 +/- 7.2 cm; Mass 74.4 +/- 9.1 kg) performed ten lunges on four different surfaces: concrete with an overlaid vinyl layer (COVL); wooden sprung court surface (WSCS); metallic carpet fencing piste overlaid on the WSCS and: aluminium fencing piste overlaid on the WSCS. An accelerometer measured accelerations along the longitudinal axis of the tibia at 1000Hz. The results identified a significantly (P < 0.05) larger impact shock magnitude was experienced during a lunge on the COVL (14.88 +/- 8.45g) compared to the WSCS (11.61 +/- 7.30g), WSCS with metallic carpet piste (11.14 +/- 6.38g) and WSCS with aluminium piste (11.95 +/- 7.21g). Furthermore, the two types of piste used had no significant effect the impact shock magnitude measured when overlaid on the WSCS compared to the WSCS on its own. The results of this investigation suggest that occurrences of injuries related to increased levels of impact shock, may be reduced through the utilization of a WSCS as opposed to a COVL surface, during fencing participation

A realist analysis of treatment programmes for sex offenders with intellectual disabilities

Background: The resources used in treatment for sex offenders with intellectual disabilities have had much research attention, but less has been written about how participants are expected to respond (programme mechanisms). Methods: A realist evaluation of seven programmes from the UK, Canada, USA, Switzerland and Germany was conducted. In semi‐structured interviews, programme designers elucidated how they are intended to work. The data analysis was driven by the realist concern to expose programme mechanisms and intended outcomes. Results: Two main outcomes are increasing risk management capacities and cultivating prosocial identities. These are achieved through developing insights into a person's risks, work on (sexual) self‐regulation skills, sexual boundaries and personal values and by developing meaningful social roles and positive relationships. Conclusions: Over time, there have been changes to some of the treatment resources used. However, there were little differences in terms of the intended programme mechanisms and outcomes, which remained surprisingly consistent