Integration effects of pylon geometry on a high-wing transport airplane

An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine the installation effects of a series of pylons that had differing cross-sectional shapes on the pressure distributions and aerodynamic characteristics of a 1/24-scale high wing transport. The tests were conducted at Mach numbers at 0.70 and 0.80 at angles of attack from -3 degrees to 4 degrees with the pylons tested at various toe angles between 5 degrees inboard and 5 degrees outboard. Results of this study indicate that the installed drag was lowest for the pylons with a compression pylon type design which kept the flow under the wing in the pylon/wing junction comparable to the clean wing velocities

Natural laminar flow nacelle for transport aircraft

The potential of laminar flow nacelles for reducing installed engine/nacelle drag was studied. The purpose was twofold: to experimentally verify a method for designing laminar flow nacelles and to determine the effect of installation on the extent of laminar flow on the nacelle and on the nacelle pressure distributions. The results of the isolated nacelle tests illustrated that laminar flow could be maintained over the desired length. Installing the nacelles on wing/pylon did not alter the extent of laminar flow occurring on the nacelles. The results illustrated that a significant drag reduction was achieved with this laminar flow design. Further drag reduction could be obtained with proper nacelle location and pylon contouring

Aeropropulsive characteristics of isolated combined turbojet/ramjet nozzles at Mach numbers from 0 to 1.20

An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine the aeropropulsive performance characteristics (the aerodynamic quantities affected by propulsion) of 13 isolated combined turbojet/ramjet nozzle configurations. These configurations simulated the variable-geometry features of two nozzle designs designated as the multiple-expansion ramp nozzle (MERN) and the composite contour nozzle (CCN). Test data were obtained at static conditions and at Mach numbers of 0.60, 0.90, and 1.20 with jet exhaust simulated by high-pressure air. The results showed that the CCN had the higher performance over the Mach number range than the MERN, as indicated by the difference of thrust minus drag divided by ideal thrust. Increasing the ramjet throat area for the MERN resulted in an increase in performance that increased with Mach number. For the CCN at Mach numbers less than 1.20, increasing the ramjet throat area resulted in a loss in performance

Supersonic investigation of two dimensional hypersonic exhaust nozzles

An experimental investigation was conducted in the NASA Lewis 10 x 10 ft supersonic Wind Tunnel to determine the performance characteristics of 2D hypersonic exhaust nozzles/afterbodies at low supersonic conditions. Generally, this type of application requires a single expansion ramp nozzle (SERN) that is highly integrated with the airframe of the hypersonic vehicle. At design conditions (hypersonic speeds), the nozzle generally exhibits acceptable performance. At off-design conditions (transonic to mid-supersonic speeds), nozzle performance of a fixed geometry configuration is generally poor. Various 2-D nozzle configurations were tested at off-design conditions from Mach 2.0 to 3.5. Performance data is presented at nozzle pressure ratios from 1 to 35. Jet exhaust was simulated with high-pressure air. To study performance of different geometries, nozzle configurations were varied by interchanging the following model parts: internal upstream contour, expansion ramp, sidewalls, and cowl

Static Internal Performance of a Two-Dimensional Convergent-Divergent Nozzle with External Shelf

An investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to determine the internal performance of a two-dimensional convergent-divergent nozzle. The nozzle design was tested with dry and afterburning throat areas, which represent different power settings and three expansion ratios. For each of these configurations, three trailing-edge geometries were tested. The baseline geometry had a straight trailing edge. Two different shaping techniques were applied to the baseline nozzle design to reduce radar observables: the scarfed design and the sawtooth design. A flat plate extended downstream of the lower divergent flap trailing edge parallel to the model centerline to form a shelf-like expansion surface. This shelf was designed to shield the plume from ground observation (infrared radiation (IR) signature suppression). The shelf represents the part of the aircraft structure that might be present in an installed configuration. These configurations were tested at nozzle pressure ratios from 2.0 to 12.0

The effectiveness of rehabilitation interventions including outdoor mobility on older adults' physical activity, endurance, outdoor mobility and falls-related self-efficacy: systematic review and meta-analysis.

OBJECTIVE: To determine the effectiveness of community-based rehabilitation interventions which incorporate outdoor mobility on physical activity, endurance, outdoor mobility and falls-related self-efficacy in older adults. DESIGN: MEDLINE, Embase, CINAHL, PEDro and OpenGrey were searched systematically from inception to June 2021 for randomised controlled trials (RCTs) of community-based rehabilitation incorporating outdoor mobility on physical activity, endurance, outdoor mobility and/or falls-related self-efficacy in older adults. Duplicate screening, selection, extraction and appraisal were completed. Results were reported descriptively and with random-effects meta-analyses stratified by population (proactive [community-dwelling], reactive [illness/injury]). RESULTS: A total of 29 RCTs with 7,076 participants were identified (66% high bias for at least one domain). The outdoor mobility component was predominantly a walking programme with behaviour change. Rehabilitation for reactive populations increased physical activity (seven RCTs, 587 participants. Hedge's g 1.32, 95% CI: 0.31, 2.32), endurance (four RCTs, 392 participants. Hedges g 0.24; 95% CI: 0.04, 0.44) and outdoor mobility (two RCTs with 663 participants. Go out as much as wanted, likelihood of a journey) at intervention end versus usual care. Where reported, effects were preserved at follow-up. One RCT indicated a benefit of rehabilitation for proactive populations on moderate-to-vigorous activity and outdoor mobility. No effect was noted for falls-related self-efficacy, or other outcomes following rehabilitation for proactive populations. CONCLUSION: Reactive rehabilitation for older adults may include walking programmes with behaviour change techniques. Future research should address the potential benefit of a walking programme for proactive populations and address mobility-related anxiety as a barrier to outdoor mobility for both proactive and reactive populations

Interface modes of two-dimensional composite structures

The surface modes of a composite consisting of aligned metallic wires with square cross sections are investigated, on the basis of photonic band structure calculations. The effective long-wavelength dielectric response function is computed, as a function of the filling fraction. The dependence of the optical absorption on the shape of the wires and the polarization of light is discussed, and the effect of sharp corners analyzed. The effect of the interaction between the wires on the localization of surface plasmons is also addressed.Comment: 12 pages, 4 figures, to appear in Surf. Sc

Effective electronic response of a system of metallic cylinders

The electronic response of a composite consisting of aligned metallic cylinders in vacuum is investigated, on the basis of photonic band structure calculations. The effective long-wavelength dielectric response function is computed, as a function of the filling fraction. A spectral representation of the effective response is considered, and the surface mode strengths and positions are analyzed. The range of validity of a Maxwell-Garnett-like approach is discussed, and the impact of our results on absorption spectra and electron energy-loss phenomena is addressed.Comment: 15 pages, 6 figures, to appear in Phys. Rev.

Association of the First 1,000 Days Systems-Change Intervention on Maternal Gestational Weight Gain

Objective: To examine the associations of a clinical and public health systems-change intervention on the prevalence of excess gestational weight gain among high-risk, low-income women. Methods: In a quasi-experimental trial, we compared the prevalence of excess gestational weight gain among women before (n=643) and after (n=928) implementation of the First 1,000 Days program in two community health centers in Massachusetts. First 1,000 Days is a systematic program starting in early pregnancy and lasting through the first 24 months of childhood to prevent obesity among mother-child pairs. The program includes enhanced gestational weight gain tracking and counseling, screening for adverse health behaviors and sociocontextual factors, patient navigation and educational materials to support behavior change and social needs, and individualized health coaching for women at high risk for excess gestational weight gain based on their prepregnancy body mass index (BMI) or excess first-trimester weight gain. The primary outcome was gestational weight gain greater than the 2009 Institute of Medicine (now known as the National Academy of Medicine) guidelines according to prepregnancy BMI. Results: Among 1,571 women in the analytic sample, mean (SD) age was 30.0 (5.9) years and prepregnancy BMI was 28.1 (6.1); 65.8% of women started pregnancy with BMIs of 25 or higher, and 53.2% were Hispanic. We observed a lower prevalence (55.8-46.4%; unadjusted odds ratio [OR] 0.69, 95% CI 0.49-0.97), similar to results in a multivariable analysis (adjusted OR 0.69, 95% CI 0.49-0.99), of excess gestational weight gain among women with prepregnancy BMIs between 25 and 29.9. Among women who were overweight at the start of pregnancy, the lowest odds of excess gestational weight gain were observed among those with the most interaction with the program's components. Program enrollment was not associated with reduced excess gestational weight gain among women with prepregnancy BMIs of 30 or higher. Conclusions: Implementation of a systems-change intervention was associated with modest reduction in excess gestational weight gain among women who were overweight but not obese at the start of pregnancy

Crisis resolution and home treatment in the UK: A survey of model fidelity using a novel review methodology

Crisis resolution teams (CRTs) provide treatment at home to people experiencing mental health crises, as an alternative to hospital admission. Previous UK research, based on self‐report surveys, suggests that a loosely specified model has resulted in wide variations in CRTs’ service delivery, organization and outcomes. A fidelity scale (developed through evidence review and stakeholder consensus) provided a means of objectively measuring adherence to a model of good practice for CRTs, via one‐day fidelity reviews of UK crisis teams. Reviews included interviews with service users, carers, staff and managers, and examination of data, policies, protocols and anonymized case notes. Of the 75 teams reviewed, 49 (65%) were assessed as being moderate fidelity and the rest as low fidelity, with no team achieving high fidelity. The median score was 122 (range: 73–151; inter‐quartile range: 111–132). Teams achieved higher scores on items about structure and organization, for example ease of referral, medication and safety systems, but scored poorly on items about the content of care and interventions. Despite a national mandate to implement the CRT model, there are wide variations in implementation in the UK and no teams in our sample achieved overall high fidelity. This suggests that a mandatory national policy is not in itself sufficient to achieve good quality implementation of a service model. The CRT Fidelity Scale provides a feasible and acceptable means to objectively assess model fidelity in CRTs. There is a need for development and testing of interventions to enhance model fidelity and facilitate improvements to these services