Operating characteristics of an inlet model tested with a 0.5m powered fan at high angles of attack

An inlet model designed for high angle of attack capability, coupled to a .508 m tip diameter turbofan simulator, was tested in the NASA-Lewis Research Center's 9-by 15-ft low speed wind tunnel. The test variables were: tunnel velocity, 0 to 75 m/s; inlet angle of attack, 0 to 120 deg; and fan face corrected airflow per unit area, 75 to 200 kg/s sqm. The inlet flow separation boundaries, the fan face total pressure recovery and distortion characteristics, and the fan blade vibratory stresses were determined. The recovery, distortion, and stress levels showed no abrupt changes at the onset of separation, but became gradually more unfavorable as the size and intensity of the separation increased as induced by increasingly severe operating conditions. Performance characteristics for a large scale model of the inlet were estimated from these test results

Automated tester permits precise calibration of pressure transducers from 0 to 1050 psi

Automated portable checker allows last-minute calibration of pressure transducers before testing. It uses a pressure console and equipment that can produce test pressures of 0-1050 psi. The console can be connected to other apparatus for measurement and visual display of the electrical output

Parameters of CO2 bands near 3.6 microns

The intensities, widths, and positions of lines of three CO2 bands near 2750/cm were determined. The results are in general agreement with other measured and estimated values

Poverty and inequality in Britain: 2006

This Commentary provides an update on trends in poverty and inequality in Great Britain, based on the latest official government statistics. It uses the same approach to measuring incomes and poverty in Great Britain as the government employs in its Households Below Average Income (HBAI) publication

Characteristics of an anechoic chamber for fan noise testing

Acoustical and mechanical design features of NASA Lewis Research Center's engine fan noise facility are described. Acoustic evaluation of the chamber, which is lined with an array of stepped wedges, is described. Results from the evaluation in terms of cut-off frequency and non-anechoic areas near the walls are detailed. Fan models are electrically driven to 20,600 RPM in either the inlet mode or exhaust mode to facilitate study of both fore and aft fan noise. Inlet noise characteristics of the first fan tested are discussed and compared to full-scale levels. Turbulence properties of the inlet flow and acoustic results are compared with and without a turbulence reducing screen over the fan inlet

NASA's rotorcraft icing research program

The objective of the NASA aircraft icing research program is to develop and make available icing technology to support the needs and requirements of industry for all weather aircraft designs. While a majority of the technology being developed is viewed to be generic (i.e., appropriate to all vehicle classes), vehicle specific emphasis is being placed on the helicopter due to its unique icing problems. In particular, some of the considerations for rotorcraft icing are indicated. The NASA icing research program emphasizes technology development in two key areas: ice protection concepts and icing simulation (analytical and experimental). The NASA research efforts related to rotorcraft icing in these two technology areas will be reviewed

VSTOL tilt nacelle aerodynamics and its relation to fan blade stresses

A scale model of a VSTOL tilt nacelle with a 0.508 m single stage fan was tested in a low speed wind tunnel to ascertain inlet aerodynamic and fan aeromechanical performance over the low speed flight envelope. Fan blade stress maxima occurred at discrete rotational speeds corresponding to integral engine order vibrations of the first flatwise bending mode. Increased fan blade stress levels coincided with internal boundary layer separation but became severe only when the separation location had progressed to the entry lip region of the inlet

Ethnic parity in labour market outcomes for benefit claimants

A significant gap exists in the UK between the employment rate for Ethnic Minorities and that for Whites. From a policy perspective, it is important to know whether this gap is due to differences in the characteristics of White and Ethnic Minority groups (which reduce the employability of Ethnic Minority groups relative to Whites) or whether it results from some form of discriminatory behaviour in the labour market. In this paper, we use administrative data to estimate ethnic differences in employment and benefit receipt amongst individuals who began claiming a Jobcentre Plus benefit in 2003. In contrast to much of the previous UK literature, we use a number of different quantitative techniques to estimate this gap, and show that in a lot of cases the estimates obtained are very sensitive to the techniques used. We argue that for the questions we are interested in and the data we have, propensity score matching methods are the most robust approach to estimating ethnic parity. We compare this preferred approach with estimates derived using alternative approaches commonly used in the literature (generally regression-based techniques) to determine the extent to which more straightforward methods are able to replicate those produced by matching. In many cases, it turns out not to be possible to calculate satisfactory quantitative estimates even with matching techniques: the characteristics of Whites and Ethnic Minorities are simply too different before the Jobcentre Plus intervention to reliably estimate the parameters of interest. Moreover, for a number of the groups, results seem to be very sensitive to the methodology used. This calls into question previous results based on simple regression techniques, which are likely to hide the fact that observationally different ethnic groups are de facto being compared on the basis of parametric extrapolations. Two groups for which it was possible to calculate reasonably reliable results are incapacity benefit (IB) and income support (IS). For these groups we find that large and significant raw penalties almost always disappear once we appropriately control for pre-inflow background and labour market characteristics. There is also a good degree of consistency across methodologies

Sub-femtosecond electron bunches created by direct laser acceleration in a laser wakefield accelerator with ionization injection

In this work, we will show through three-dimensional particle-in-cell simulations that direct laser acceleration in laser a wakefield accelerator can generate sub-femtosecond electron bunches. Two simulations were done with two laser pulse durations, such that the shortest laser pulse occupies only a fraction of the first bubble, whereas the longer pulse fills the entire first bubble. In the latter case, as the trapped electrons moved forward and interacted with the high intensity region of the laser pulse, micro-bunching occurred naturally, producing 0.5 fs electron bunches. This is not observed in the short pulse simulation.Comment: AAC 201