An overview of the quiet short-haul research aircraft program

An overview of the Quiet Short Haul Research Aircraft (QSRA) Program is presented, with special emphasis on its propulsion and acoustic aspects. A description of the NASA technical participation in the program including wind tunnel testing, engine ground tests, and advanced aircraft simulation is given. The aircraft and its systems are described and, measured performance, where available, is compared to program goals. Preliminary data indicate that additional research and development are needed in some areas of which acoustics is an example. Some of these additional research areas and potential experiments using the QSRA to develop the technology are discussed. The concept of the QSRA as a national flight research facility is explained

Wind data from the 250-foot /76.2-meter/ tower at Wallops Island, Virginia

Statistical evaluation of sampled wind data from anemometers mounted on meteorological tower on Wallops Islan

The Djelk Ranger Program: an outsider’s perspective

This report is the result of a ten-day general conceptualisation research trip in May 2003 into an Indigenous community to study the Djelk Ranger program operating under the Bawinanga Aboriginal Corporation (BAC). During this visit I spent time with several different groups of Rangers and visited several sustainable wildlife harvesting sites which are described here. The Djelk Ranger program established by the BAC is built on the extensive knowledge and skills that already exist within this Indigenous community. The success of the ventures mentioned in this report is built on a unique blend of formal legal institutional mechanisms and customary law and socio-cultural conventions. Cooperative community-based wildlife resource management and aquaculture has the potential to deliver sustainable and cost effective development benefits for Indigenous landowners. Greater recognition of the valuable land management and biodiversity conservation roles undertaken by Indigenous people in these circumstances would seem appropriate, and it would be desirable for these roles to be reflected in more formal and sustained income arrangements than the current CDEP project funding. The opportunities for economic development in Indigenous communities, and some of the challenges that these communities face are demonstrated in the Djelk Ranger program initiative. The BAC is an impressive institution for its commitment to learning, communication, cultural integration, and economic development. There is clearly a need for such adaptive and flexible institutions to provide a bridge between cultures and protect the interests of remote Indigenous communities

Selective Laser Sintering of Polymer Nanocomposites

This paper describes the fabrication and characterization of polymer nanocomposite (PNC) materials for use in the selective laser sintering (SLS) process. PNC materials are of great interest generally because of their excellent physical properties, and offer excellent potential in rapid manufacturing of structural polymeric parts. Three different nano additive materials have been used: cerium oxide IV, yttrium stabilized zirconia, and layered Hectorite clay. These materials have been used to reinforce PA6 polymer using solution blending and spray drying to create powder with particle sizes in the range of 5-40 µm. The mechanical properties and microstructure of the PNC materials have been evaluated and the results compared to those of unfilled polymer.Mechanical Engineerin

All their eggs in one basket: a rocky reef nursery for the longnose skate (Raja rhina Jordan & Gilbert, 1880) in the southern California Bight

Skates (family Rajidae) are oviparous and lay tough, thick-walled eggs. At least some skate species lay their eggs in spatially restricted nursery grounds where embryos develop and hatch (Hitz, 1964; Hoff, 2007). After hatching, neonates may quickly leave the nursery grounds (Hoff, 2007). Egg densities in these small areas may be quite high. As an example, in the eastern Bering Sea, a site <2 km2 harbored eggs of Alaska skate (Bathyraja parmifera) exceeding 500,000/km2. All skate nursery grounds have been identified over soft sea floors (Lucifora and García, 2004; Hoff, 2007)

Effects of different vibration frequencies, amplitudes and contraction levels on lower limb muscles during graded isometric contractions superimposed on whole body vibration stimulation

Background: Indirect vibration stimulation, i.e., whole body vibration or upper limb vibration, has been investigated increasingly as an exercise intervention for rehabilitation applications. However, there is a lack of evidence regarding the effects of graded isometric contractions superimposed on whole body vibration stimulation. Hence, the objective of this study was to quantify and analyse the effects of variations in the vibration parameters and contraction levels on the neuromuscular responses to isometric exercise superimposed on whole body vibration stimulation. Methods: In this study, we assessed the 'neuromuscular effects' of graded isometric contractions, of 20%, 40%, 60%, 80% and 100% of maximum voluntary contraction, superimposed on whole body vibration stimulation (V) and control (C), i.e., no-vibration in 12 healthy volunteers. Vibration stimuli tested were 30 Hz and 50 Hz frequencies and 0.5 mm and 1.5 mm amplitude. Surface electromyographic activity of the vastus lateralis, vastus medialis and biceps femoris were measured during V and C conditions with electromyographic root mean square and electromyographic mean frequency values used to quantify muscle activity and their fatigue levels, respectively. Results: Both the prime mover (vastus lateralis) and the antagonist (biceps femoris) displayed significantly higher (P < 0.05) electromyographic activity with the V than the C condition with varying percentage increases in EMG root-mean-square (EMGrms) values ranging from 20% to 200%. For both the vastus lateralis and biceps femoris, the increase in mean EMGrms values depended on the frequency, amplitude and muscle contraction level with 50 Hz-0.5 mm stimulation inducing the largest neuromuscular activity. Conclusions: These results show that the isometric contraction superimposed on vibration stimulation leads to higher neuromuscular activity compared to isometric contraction alone in the lower limbs. The combination of the vibration frequency with the amplitude and the muscle tension together grades the final neuromuscular output.Peer reviewe