5,905 research outputs found
Tabulated Data From a Pressure-Distribution Investigation at Mach Number 2.01 of a 45 Deg Sweptback-Wing Airplane Model at Combined Angles of Attack and Sideslip
A pressure-distribution investigation of a wing-body combination has been conducted in the Langley 4- by 4-foot supersonic pressure tunnel at a Mach number of 2.01. The model configuration consisted of an ogive-circular-cylinder body (fineness ratio of approximately ii) and a wing with 45 deg of sweepback at the quarter-chord line, an aspect ratio of 4, and a taper ratio of 0.2. Data were obtained on high-, mid-, and low-wing configurations and for the body and wing alone for a range of angles of attack and yaw from 0 deg to 15 deg. The tabulated pressure coefficients are presented in this report
Development of a meteoroid penetration distributed transducer Third quarterly report
Impact calibration tests in development of meteoroid penetration distributed transduce
Intensive Medical Care and Cardiovascular Disease Disability Reductions
There is little empirical evidence to explain why disability declined among the elderly over the past 20 years. In this paper, we explore the role of improved medical care for cardiovascular disease on health status improvements over time. We show that the incidence of cardiovascular disease hospitalizations remained relatively constant between 1984 and 1999 at the same time that post-event survival improved and disability declined. We find that use of appropriate therapies, including pharmaceuticals such as beta-blockers, aspirin, and ace-inhibitors, and invasive procedures, explains up to 50% and 70% of the reductions in disability and death over time, respectively. Elderly patients living in regions with high use of appropriate medical therapies had better health outcomes than patients living in low-use areas. Finally, we estimate that preventing disability after an acute event can add as much as 3.7 years of quality-adjusted life expectancy, or $316,000 of value.
Clinical Pathways to Disability
This paper examines the pathways by which individuals transition from healthy to disabled. Because of the high prevalence and costs associated with disability, understanding these pathways is critical to developing interventions to prevent or minimize disability. We compare two estimates of disabling conditions: those observed in medical claims and conditions indicated by the disabled individual. A small number of conditions explain about half of incident disability: arthritis, infectious disease, dementia, heart failure, diabetes, and stroke. These conditions show up in medical claims and self reports. A large number of elderly also attribute disability to old age and various symptoms. Because so many of the most disabling conditions do not have clear medical treatments, the outlook for major reductions in disability might be limited.
Theoretical and experimental study of twisted and cambered delta wings designed for a Mach number of 3.5
Data are provided for the evaluation of the aerodynamic performance of a series of twisted and cambered delta wings designed for a Mach number of 3.5. Systematic force and pressure data are also presented for comparison with theory. Force tests were made at Mach numbers of 2.3, 3.0, 3.5, 4.0, and 4.6. Design lift coefficients of 0.0 and 0.1 were employed on the 55 deg and 68 deg sweep wings, and design lift coefficients of 0.0, 0.05, and 0.1 were employed on the 76 deg sweep wings. Pressure tests were conducted on the 55 deg and 76 deg sweep flat wings and on the 0.1 design lift coefficient 76 deg sweep wing. The results indicate that for the sweep angles tested, an increase in the zero-lift pitching-moment coefficient is the primary benefit of twist and camber at a Mach number of 3.5. Comparison of the experimental results with results obtained from several lift theories indicates that the Carlson-Middleton linear theory method gave the best overall agreement. The pressure data indicate, however, that there is a cancellation of error at high angle of attack where the lower surface pressures are significantly underpredicted over the inboard region of the wing and where the upper and lower surface pressures are overpredicted over the outboard region of the wing
Pressure and force data for a flat wing and a warped conical wing having a shockless recompression at Mach 1.62
A conical nonlinear flow computer code was used to design a warped (cambered) wing which would produce a supercritical expansion and shockless recompression of the crossflow at a lift coefficient of 0.457, an angle of attack of 10 deg, and a Mach number of 1.62. This cambered wing and a flat wing the same thickness distribution were tested over a range of Mach numbers from 1.6 to 2.0. For both models the forward 60 percent is purely conical geometry. Results obtained with the cambered wing demonstrated the design features of a supercritical expansion and a shockless recompression, whereas results obtained with the flat wing indicated the presence of crossflow shocks. Tables of experimental pressure, force, and moment data are included, as well as selected oil flow photographs
In Search of Environmental Sustainability at the Base of the Pyramid
This paper proposes a revision to Hart and Sharma’s 2004 model for corporate engagement with the base of the pyramid (BoP) by making the BoP community and the natural environment, not the firm, the central focus for engagement. The revised model proposes that core stakeholders must include the BoP community, the poor, weak, and illiterate, as they can benefit most from the community collective action model presented herein to address sustainability in the natural environment. These are the core stakeholders rather than fringe stakeholders, as indicated in the Hart and Sharma model. Our model recognizes the legitimacy of the firm as an enabler that possesses the power to help core stakeholders address the causes of environmental degradation that act as barriers to poverty alleviation and natural resource access
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