Control of elasticity in cast elastomeric shock/vibration isolators

Elasticity is determined by isolators physical dimensions and by type of elastomer used. Once elastomer is selected and cast between two concentric tubes of device, isolator elasticity will remain fixed. Isolators having same dimensions can be built to different elasticity requirements using same elastomer

Rotational joint assembly for the prosthetic leg

A rotational joint assembly for a prosthetic leg has been devised, which enables an artificial foot to rotate slightly when a person is walking, running or turning. The prosthetic leg includes upper and lower tubular members with the rotational joint assembly interposed between them. The assembly includes a restrainer mechanism which consists of a pivotably mounted paddle element. This device applies limiting force to control the rotation of the foot and also restores torque to return the foot back to its initial position

On the performance of densified DVB-H single frequency networks

The broadcasting of TV programmes to mobile phones can be enabled by the newly developed technology called Digital Video Broadcasting-Handheld (DVB-H). Because of the scarcity and cost of frequency resources, frequency reuse needs to be considered when rolling out DVB-H networks. By simulcasting the same content from several transmitters, a Single Frequency Network (SFN) can provide good coverage and good frequency efficiency. In this paper, the performance of densified DVB-H SFN networks is analysed in terms of the coverage probability under different coverage requirements with and without frequency reuse. A dichotomy searching approach is used to determine the optimal cell radius for a cell in a densified DVB-H SFN for a given network topology. Based on the optimal cell radius map and a SFN gain map generated from the simulation results, guidelines are proposed on how to avoid the potential pitfalls in configuring the parameters of a densified DVB-H SFN network and optimise its parameters in terms of minimising the cost of the network for a range of predefined network parameters

Biomass production and nitrogen dynamics in an integrated aquaculture/agriculture system

A combined aquaculture/agriculture system that brings together the three major components of a Controlled Ecological Life Support System (CELSS) - biomass production, biomass processing, and waste recycling - was developed to evaluate ecological processes and hardware requirements necessary to assess the feasibility of and define design criteria for integration into the Kennedy Space Center (KSC) Breadboard Project. The system consists of a 1 square meter plant growth area, a 500 liter fish culture tank, and computerized monitoring and control hardware. Nutrients in the hydrophonic solution were derived from fish metabolites and fish food leachate. In five months of continuous operation, 27.0 kg of lettuce tops, 39.9 kg of roots and biofilm, and 6.6 kg of fish (wet weights) were produced with 12.7 kg of fish food input. Based on dry weights, a biomass conversion index of 0.52 was achieved. A nitrogen budget was derived to determine partitioning of nitrogen within various compartments of the system. Accumulating nitrogen in the hypoponic solution indicated a need to enlarge the plant growth area, potentially increasing the biomass production and improving the biomass conversion index

Surface behaviour for materials processing

The surface behaviour of minerals containing rare earth elements was investigated using zeta potential measurements. The rare earth fluorcarbonate mineral, parisite and a rare earth enriched phosphate mineral, apatite were measured under water and collector aqueous conditions, which are similar to those found under froth flotation. Firstly, the iso electric point of parisite was measured at pH 5.6 in water, this is within the range of reported IEP values of another rare earth fluorcarbonate mineral, bastnäsite. Bastnäsite currently sources over half of the world’s rare earth elements and has well studied surface behaviour. The surface behaviour of parisite under collector and supernatant conditions was similar to bastnäsite, indicating that parisite could be processed using the same froth flotation regimes as bastnäsite. Secondly, the iso electric point of rare earth enriched apatite was measured at pH 3.8, which is consistent with the values of apatite non-rare earth enriched apatite in the literature. The surface behaviour of non-rare earth enriched apatite from the literature and the enriched apatite measured here is similar under common reagent conditions. This suggests apatite processing could be applied to rare earth enriched apatite deposits. The first evidence of nanobubbles at the surface of the carbonate mineral, dolomite and rare earth fluorcarbonate mineral, synchysite were also reported. The nanobubbles were measured using non-contact atomic force microscopy, and produced using the gas oversaturation method of heating the liquid. Nanobubble density on dolomite was increased by collector conditions with 0.656 bubbles per µm2, compared to 0.342 nanobubbles per µm2 under water conditions. Investigating the contact angle of the nanobubbles on dolomite indicated that the reagents effected the pinning of the nanobubbles and not their surface tension. Nanobubbles on the synchysite sample in collector conditions had an average contact angle of 24 degrees, in line with previous studies. The presence of nanobubbles on synchysite under collector conditions demonstrates that the surface is hydrophobic. Finally, nanobubbles at the surface of patterned and unpatterned chemical vapour deposition monolayer graphene were investigated. High-speed atomic force microscopy was used to image nanobubbles produced using solvent exchange. Nanobubbles were found on patterned graphene, not on the underlying SiO2 substrate. This links to the increased hydrophobicity of graphene compared to SiO2. The patterning of the graphene reduced the nanobubbles’ lateral size and increased the contact angle, consistent with previous results of nanobubbles on patterning. These are the first reported results of nanobubbles constrained by chemically patterned graphene.Natural Environment Research Council (NERC

Prosthesis coupling

A coupling for use in an apparatus for connecting a prosthesis to the bone of a stump of an amputated limb is described which permits a bio-compatible carbon sleeve forming a part of the prosthesis connector to float so as to prevent disturbing the skin seal around the carbon sleeve. The coupling includes a flexible member interposed between a socket that is inserted within an intermedullary cavity of the bone and the sleeve. A lock pin is carried by the prosthesis and has a stem portion which is adapted to be coaxially disposed and slideably within the tubular female socket for securing the prosthesis to the stump. The skin around the percutaneous carbon sleeve is able to move as a result of the flexing coupling so as to reduce stresses caused by changes in the stump shape and/or movement between the bone and the flesh portion of the stump

Owens, Moke C. (2)

159th ASF Band; Fort Leonard Wood, MOhttps://dh.howard.edu/prom_corres/1112/thumbnail.jp

Continuous hydroponic wheat production using a recirculating system

Continuous crop production, where plants of various ages are growing simultaneously in a single recirculating nutrient solution, is a possible alternative to batch production in a Controlled Ecological Life Support System. A study was conducted at John F. Kennedy Space Center where 8 trays (0.24 sq m per tray) of Triticum aestivum L. Yecora Rojo were grown simultaneously in a growth chamber at 23 C, 65 percent relative humidity, 1000 ppm CO2, continuous light, with a continuous flow, thin film nutrient delivery system. The same modified Hoagland nutrient solution was recirculated through the plant trays from an 80 L reservoir throughout the study. It was maintained by periodic addition of water and nutrients based on chemical analyses of the solution. The study was conducted for 216 days, during which 24 trays of wheat were consecutively planted (one every 9 days), 16 of which were grown to maturity and harvested. The remaining 8 trays were harvested on day 216. Grain yields averaged 520 g m(exp -2), and had an average edible biomass of 32 percent. Consecutive yields were unaffected by nutrient solution age. It was concluded that continual wheat production will work in this system over an extended period of time. Certain micronutrient deficiencies and toxicities posed problems and must be addressed in future continuous production systems