9,632 research outputs found
Working Effectively with People who are Blind or Visually Impaired
This brochure on peoples who are blind or visually impaired and The Americans with Disabilities Act (ADA) is one of a series on human resources practices and workplace accommodations for persons with disabilities edited by Susanne M. Bruyère, Ph.D., CRC, SPHR, Director, Program on Employment and Disability, School of Industrial and Labor Relations – Extension Division, Cornell University
The effect of advance ratio on the aerodynamics of revolving wings
Recent studies have demonstrated that a quasi-steady
model closely matches the instantaneous force produced
by an insect wing during hovering flight. It is not clear,
however, if such methods extend to forward flight. In this
study we use a dynamically scaled robotic model of the
fruit fly Drosophila melanogaster to investigate the forces
produced by a wing revolving at constant angular velocity
while simultaneously translating at velocities appropriate
for forward flight. Because the forward and angular
velocities were constant wing inertia was negligible, and
the measured forces can be attributed to fluid dynamic
phenomena. The combined forward and revolving motions
of the wing produce a time-dependent free-stream velocity
profile, which suggests that added mass forces make a
contribution to the measured forces. We find that the
forces due added mass make a small, but measurable,
component of the total force and are in excellent
agreement with theoretical values. Lift and drag
coefficients are calculated from the force traces after
subtracting the contributions due to added mass. The lift
and drag coefficients, for fixed angle of attack, are not
constant for non-zero advance ratios, but rather vary
in magnitude throughout the stroke. This observation
implies that modifications of the quasi-steady model are
required in order to predict accurately the instantaneous
forces produced during forward flight. We show that the
dependence of the lift and drag coefficients upon advance
ratio and stroke position can be characterized effectively
in terms of the tip velocity ratio – the ratio of the
chordwise components of flow velocity at the wing tip due
to translation and revolution. On this basis we develop a
modified quasi-steady model that can account for the
varying magnitudes of the lift and drag coefficients.
Our model may also resolve discrepancies in past
measurements of wing performance based on translational
and revolving motion
Employment Considerations for People who have Diabetes
This brochure on Diabetes and the Americans with Disabilities Act (ADA) is one of a series on human resources practices and workplace accommodations for persons with disabilities edited by Susanne M. Bruyère, Ph.D., CRC, SPHR, Director, Program on Employment and Disability, School of Industrial and Labor Relations – Extension Division, Cornell University. Cornell University was funded in the early 1990’s by the U.S. Department of Education National Institute on Disability and Rehabilitation Research as a National Materials Development Project on the employment provisions (Title I) of the ADA (Grant #H133D10155). These updates, and the development of new brochures, have been funded by Cornell’s Program on Employment and Disability, the Pacific Disability and Business Technical Assistance Center, and other supporters
An aid to the development of Botswana's resources: Section on hydrology
The author has identified the following significant results. It is proved that FCC's can be used for a simple estimate of the total evaportranspiring area of the Okavango Delta, sufficiently accurate for preliminary inputs for the development of mathematical model of the surface hydrology of the delta. The color coded matrix has shown as interesting inverse correlation with an array on the same grid prepared by ecologists from air photography study, for percent liable to flood
Working Effectively with People who are Blind or Visually Impaired
This brochure on peoples who are blind or visually impaired and The Americans with Disabilities Act (ADA) is one of a series on human resources practices and workplace accommodations for persons with disabilities edited by Susanne M. Bruyère, Ph.D., CRC, SPHR, Director, Program on Employment and Disability, School of Industrial and Labor Relations – Extension Division, Cornell University. Cornell University was funded in the early 1990’s by the U.S. Department of Education National Institute on Disability and Rehabilitation Research as a National Materials Development Project on the employment provisions (Title I) of the ADA (Grant #H133D10155). These updates, and the development of new brochures, have been funded by Cornell’s Program on Employment and Disability
Sizing-stiffened composite panels loaded in the postbuckling range
Stiffened panels are widely used in aircraft structures such as wing covers, fuselages, control surfaces, spar webs, bulkheads, and floors. The detailed sizing of minimum-weight stiffened panels involves many considerations. Use of composite materials introduces additional complexities. Many potential modes of failure exist. Analyses for these modes are often not trivial, especially for those involving large out-of-plane displacements. Accurate analyses of all potential failure modes are essential. Numerous practical constraints arise from manufacturing/cost considerations and from damage tolerance, durability, and stiffness requirements. The number of design variables can be large when lamina thicknesses and stacking sequence are being optimized. A significant burden is placed on the sizing code due to the complex analyses, practical constraints, and number of design variables. On the other hand, sizing weight-efficient panels without the aid of an automated procedure is almost out of the question. The sizing code postbuckled Open-Stiffener Optimum Panels (POSTOP) has been developed to aid in the design of minimum-weight panels subject to the considerations mentioned above. Developed for postbuckled composite panels, POSTOP may be used for buckling resistant panels and metallic panels as well. The COPES/CONMIN optimizer is used in POSTOP although other options such as those in the ADS system could be substituted with relative ease. The basic elements of POSTOP are shown. Some of these elements and usage of the program are described
Design and analysis of a stiffened composite fuselage panel
The design and analysis of stiffened composite panel that is representative of the fuselage structure of existing wide bodied aircraft is discussed. The panel is a minimum weight design, based on the current level of technology and realistic loads and criteria. Several different stiffener configurations were investigated in the optimization process. The final configuration is an all graphite/epoxy J-stiffened design in which the skin between adjacent stiffeners is permitted to buckle under design loads. Fail safe concepts typically employed in metallic fuselage structure have been incorporated in the design. A conservative approach has been used with regard to structural details such as skin/frame and stringer/frame attachments and other areas where sufficient design data was not available
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