High-Efficiency Modified Fresnel Reflectors for Solar-Energy Concentration

A study has been made of the Fresnel reflector and two variations of this reflector for use as solar-energy collectors. One variation is the conical Fresnel reflector in which the serrations are located on the inner surface of a cone. It is shown that this reflector can have a collection efficiency of 1.00 for any rim angle, if the proper cone angle is selected. Equations are developed for the design of the second variation which consists of a reflector plane that is not perpendicular to the incoming light rays. Segments of this reflector can be used to form a pyramidal collector which combines the desired flatness of the Fresnel reflector with the high efficiency of the conical Fresnel reflector. This collector can have an efficiency which is very close to 1.00 when a sufficient number of reflective sides are used

Communication system features dual mode range acquisition plus time delay measurement

Communication system combines range acquisition system and time measurement system for tracking high velocity aircraft and spacecraft. The range acquisition system uses a pseudonoise code to determine range and the time measurement system reduces uncontrolled phase variations in the demodulated signal

Some Torsional-damping Measurements of Laminated Beams as Applied to the Propeller Stall-flutter Problem

The structural damping in the torsion mode of vibration of a series of untwisted, laminated thin beams simulating propeller blades is presented. The number of lamination were varied, as well as the bonding material and the method of joining lamination. Application of the data to the calculation of the minimum flutter speed of thin propeller blades indicates that appreciable gains in the minimum flutter speed may be obtained for laminated blades using a Cycleweld bond

Wind-Tunnel Measurements of Effect of Dive-Recovery Flaps at Transonic Speeds on Models of a Seaplane and a Transport

The effects of wing-lower-surface dive-recovery flaps on the aero- dynamic characteristics of a transonic seaplane model and a transonic transport model having 40 deg swept wings have been investigated in the Langley 16-foot transonic tunnel. The seaplane model had a wing with an aspect ratio of 5.26, a taper ratio of 0.333, and NACA 63A series airfoil sections streamwise. The transport model had a wing with an aspect ratio of 8, a taper ratio of 0.3, and NACA 65A series airfoil sections perpendicular to the quarter-chord line. The effects of flap deflection, flap longitudinal location, and flap sweep were generally investigated for both horizontal-tail-on and horizontal-tail-off configurations. Model force and moment measurements were made for model angles of attack from -5 deg to 14 deg in the Mach number range from 0.70 to 1.075 at Reynolds numbers of 2.95 x 10(exp 6) to 4.35 x 10(exp 6). With proper longitudinal location, wing-lower-surface dive-recovery flaps produced lift and pitching-moment increments that increased with flap deflection. For the transport model a flap located aft on the wing proved to be more effective than one located more forward., both flaps having the same span and approximately the same deflection. For the seaplane model a high horizontal tail provided added effectiveness for the deflected-flap configuration

Several Methods for Reducing the Drag of Transport Configurations at High Subsonic Speeds

Results of investigations of several promising methods for alleviating the drag rise of transport configurations at high subsonic speeds are reviewed briefly. The methods include a wing leading-edge extension, a fuselage addition, and additions on the wing. Also, results are presented for a complete, improved transport configuration which incorporates the fuselage and wing additions and show that the improved configuration could have considerably higher cruise speeds than do current designs

Can we manage coastal ecosystems to sequester more blue carbon?

© The Ecological Society of America To promote the sequestration of blue carbon, resource managers rely on best-management practices that have historically included protecting and restoring vegetated coastal habitats (seagrasses, tidal marshes, and mangroves), but are now beginning to incorporate catchment-level approaches. Drawing upon knowledge from a broad range of environmental variables that influence blue carbon sequestration, including warming, carbon dioxide levels, water depth, nutrients, runoff, bioturbation, physical disturbances, and tidal exchange, we discuss three potential management strategies that hold promise for optimizing coastal blue carbon sequestration: (1) reducing anthropogenic nutrient inputs, (2) reinstating top-down control of bioturbator populations, and (3) restoring hydrology. By means of case studies, we explore how these three strategies can minimize blue carbon losses and maximize gains. A key research priority is to more accurately quantify the impacts of these strategies on atmospheric greenhouse-gas emissions in different settings at landscape scales