Tunable thermal emission at infrared frequencies via tungsten gratings

The author investigates the manipulation of thermal emission by using one-dimensional tungsten gratings with different groove depths. It is found that, by systematically increasing the depth of the groove, the linearly polarized emission at particular frequencies can be substantially enhanced to achieve that of the blackbody radiation limit, whereas the emission in other frequency ranges shows no noticeable changes. The results can provide useful insights into the design of thermovoltaic applications

Ethnic minority business in the uk: a review of research and policy development

Part of a series produced to support a ESRC/CRE/DTI/emda workshop on ethnic minority entrepreneurship. This paper comprised a review of research literature on ethnic minority enterprise and an overview of UK policy developments

Improving the efficiency of smaller transport aircraft

Considered apart from its propulsive system the high altitude airplane itself adapted to higher flight altitudes than those in current use. Scaling on the assumption of constant aircraft density indicates that this conclusion applies most importantly to smaller transport aircraft. Climb to 60,000 ft could save time and energy for trips as short as 500 miles. A discussion of the effect of winglets on aircraft efficiency is presented. A 10% reduction of induced drag below that of a comparable elliptic wing can be achieved either by horizontal or vertical wing tip extensions

Alfven wave transport effects in the time evolution of parallel cosmic-ray modified shocks

Some of the issues associated with a more complete treatment of Alfven transport in cosmic ray shocks are explored qualitatively. The treatment is simplified in some important respects, but some new issues are examined and for the first time a nonlinear, time dependent study of plane cosmic ray mediated shocks with both the entropy producing effects of wave dissipation and effects due to the Alfven wave advection of the cosmic ray relative to the gas is included. Examination of the direct consequences of including the pressure and energy of the Alfven waves in the formalism began

The spanwise distribution of lift for minimum induced drag of wings having a given lift and a given bending moment

The problem of the minimum induced drag of wings having a given lift and a given span is extended to include cases in which the bending moment to be supported by the wing is also given. The theory is limited to lifting surfaces traveling at subsonic speeds. It is found that the required shape of the downwash distribution can be obtained in an elementary way which is applicable to a variety of such problems. Expressions for the minimum drag and the corresponding spanwise load distributions are also given for the case in which the lift and the bending moment about the wing root are fixed while the span is allowed to vary. The results show a 15-percent reduction of the induced drag with a 15-percent increase in span as compared with results for an elliptically loaded wing having the same total lift and bending moment