Developments in steady and unsteady aerodynamics for use in aeroelastic analysis and design

A review is given of seven research projects which are aimed at improving the generality, accuracy, and computational efficiency of steady and unsteady aerodynamic theory for use in aeroelastic analysis and design. These projects indicate three major thrusts of current research efforts: (1) more realistic representation of steady and unsteady subsonic and supersonic loads on aircraft configurations of general shape with emphasis on structural-design applications, (2) unsteady aerodynamics for application in active-controls analyses, and (3) unsteady aerodynamics for the frequently critical transonic speed range. The review of each project includes theoretical background, description of capabilities, results of application, current status, and plans for further development and use

Strike Three: Umpires' Demand for Discrimination

We explore umpires' racial/ethnic preferences in the evaluation of Major League Baseball pitchers. Controlling for umpire, pitcher, batter and catcher fixed effects and many other factors, strikes are more likely to be called if the umpire and pitcher match race/ethnicity. This effect only exists where there is little scrutiny of umpires' behavior -- in ballparks without computerized systems monitoring umpires' calls, at poorly attended games, and when the called pitch cannot determine the outcome of the at-bat. If a pitcher shares the home-plate umpire's race/ethnicity, he gives up fewer runs per game and improves his team's chance of winning. The results suggest that standard measures of salary discrimination that adjust for measured productivity may generally be flawed. We derive the magnitude of the bias generally and apply it to several examples.

Strike Three: Umpires' Demand for Discrimination

We explore how umpires' racial/ethnic preferences are expressed in their evaluation of Major League Baseball pitchers. Controlling for umpire, pitcher, batter and catcher fixed effects and many other factors, strikes are more likely to be called if the umpire and pitcher match race/ethnicity. This effect only exists where there is little scrutiny of umpires' behavior – in ballparks without computerized systems monitoring umpires' calls, at poorly attended games, and when the called pitch cannot determine the outcome of the at-bat. If a pitcher shares the home-plate umpire's race/ethnicity, he gives up fewer hits, strikes out more batters, and improves his team's chance of winning. The general implication is that standard measures of salary discrimination that adjust for measured productivity may be flawed. We derive the magnitude of the bias generally and apply it to several examples.strategic interactions, worker evaluation, wage equations, economics of sports

Development of a carbon fibre composite active mirror: Design and testing

Carbon fibre composite technology for lightweight mirrors is gaining increasing interest in the space- and ground-based astronomical communities for its low weight, ease of manufacturing, excellent thermal qualities and robustness. We present here first results of a project to design and produce a 27 cm diameter deformable carbon fibre composite mirror. The aim was to produce a high surface form accuracy as well as low surface roughness. As part of this programme, a passive mirror was developed to investigate stability and coating issues. Results from the manufacturing and polishing process are reported here. We also present results of a mechanical and thermal finite element analysis, as well as early experimental findings of the deformable mirror. Possible applications and future work are discussed.Comment: Accepted by Optical Engineering. Figures 1-7 on http://www.star.ucl.ac.uk/~sk/OEpaper_files

Impact of fire on leaf nutrients, arthropod fauna and herbivory of native and exotic eucalypts in Kings Park, Perth, Western Australia

The vegetation of Kings Park, near the centre of Perth, Western Australia, once had an overstorey of Eucalyptus marginata (jarrah) or Eucalyptus gomphocephala (tuart), and many trees still remain in the bushland parts of the Park. Avenues and roadsides have been planted with eastern Australian species, including Eucalyptus cladocalyx (sugar gum) and Eucalyptus botryoides (southern mahogany), both of which have become invasive. The present study examined the effect of a recent burn on the level of herbivory on these native and exotic eucalypts. Leaf damage, shoot extension and number of new leaves were measured on tagged shoots of saplings of each tree species in unburnt and burnt areas over an 8-month period. Leaf macronutrient levels were quantified and the number of arthropods on saplings was measured at the end of the recording period by chemical knockdown. Leaf macronutrients were mostly higher in all four species in the burnt area, and this was associated with generally higher numbers of canopy arthropods and greater levels of leaf damage. It is suggested that the pulse of soil nutrients after the fire resulted in more nutrient-rich foliage, which in turn was more palatable to arthropods. The resulting high levels of herbivory possibly led to reduced shoot extension of E. gomphocephala, E. botryoides and, to a lesser extent, E. cladocalyx. This acts as a negative feedback mechanism that lessens the tendency for lush, post-fire regrowth to outcompete other species of plants. There was no consistent difference in the levels of the various types of leaf damage or of arthropods on the native and the exotic eucalypts, suggesting that freedom from herbivory is not contributing to the invasiveness of the two exotic species

Growth and formation of inverse GaP and InP opals

Opals consist of an ordered array of SiO2 spheres. This leads to a modulation of the refractive index and hence photonic stop bands behaviour over the visible/IR range of the electro-magnetic spectrum. The exact position of the stop bands depends on the size of the silica spheres. However, the refractive index contrast between the SiO2 spheres and air spaces is not great enough to open up a full photonic band gap (PBG), only the pseudogap. To increase the contrast the air spaces are filled with a material of high refractive index such as InP or GaP. To further increase the contrast the SiO2 is removed leaving a III-V framework as the inverse opal structure. By use of MOCVD we have been able to infill opals with InP and GaP to such a level that has supported the inversion of the composite forming a structure of air holes within a III-V lattice. XRD and Raman confirmed the quality of the III-V infill, while the extent of the infill was studied by SEM and reflectance measurements

Superconductivity induced by spark erosion in ZrZn2

We show that the superconductivity observed recently in the weak itinerant ferromagnet ZrZn2 [C. Pfleiderer et al., Nature (London) 412, 58 (2001)] is due to remnants of a superconducting layer induced by spark erosion. Results of resistivity, susceptibility, specific heat and surface analysis measurements on high-quality ZrZn2 crystals show that cutting by spark erosion leaves a superconducting surface layer. The resistive superconducting transition is destroyed by chemically etching a layer of 5 microns from the sample. No signature of superconductivity is observed in rho(T) of etched samples at the lowest current density measured, J=675 Am-2, and at T < 45 mK. EDX analysis shows that spark-eroded surfaces are strongly Zn depleted. The simplest explanation of our results is that the superconductivity results from an alloy with higher Zr content than ZrZn2.Comment: Final published versio

Strain Evolution Measurement at the Microscale of a Dual Phase Steel Using Digital Image Correlation

Digital Image Correlation (DIC) together with in-situ tensile testing has been used to measure in DP1000 steel the evolution of plastic strains at the microstructure scale. Interrupted tensile tests were performed on specially designed samples and scanning-electron micrographs were taken at regular applied strain intervals. Patterns defined by the microstructural features of the material have been used for the correlation carried out using LAVision software. The full field strain maps produced by DIC show a progressive localisation of deformation into bands at about 45o with respect to the loading direction. Plastic strains as high as 130% have been measured within the ferrite phase

Enhancement of quasiparticle recombination in Ta and Al superconductors by implantation of magnetic and nonmagnetic atoms

The quasiparticle recombination time in superconducting films, consisting of the standard electron-phonon interaction and a yet to be identified low temperature process, is studied for different densities of magnetic and nonmagnetic atoms. For both Ta and Al, implanted with Mn, Ta and Al, we observe an increase of the recombination rate. We conclude that the enhancement of recombination is not due to the magnetic moment, but arises from an enhancement of disorder.Comment: 4 pages, 4 figure

Diversity and inclusion depend on effective engagement It is everyone’s business to ensure that progress is maintained

Purpose – Highlights some of the things that can be done to ensure that organizations embed diversity and inclusion. Design/methodology/approach – Considers the need for effective engagement, the importance of performance indicators for diversity and inclusion and the key role of sharing stories. Discusses, too, how critical race theory could help to bring about improvements. Findings – Advances the view that a transformational process that supports employees with the knowledge and sustainable skills needed to improve business performance via ethical means will form a significant part of future-proofing organizations. Practical implications – Argues that, to achieve this organizations have to drive home the message that diversity and inclusion are everyone’s business. Social implications – Advances the view that a unified approach to diversity and inclusion, which is embedded in the business ethics of the organization, can have a sustainable positive impact on the health and well-being of individuals, business and society. Originality/value – Considers diversity and inclusion from diverse perspectives and draws conclusions that can help organizations to perform better in these areas