An aeronautical mobile satellite experiment

The various activities and findings of a NASA/FAA/COMSAT/INMARSAT collaborative aeronautical mobile satellite experiment are detailed. The primary objective of the experiment was to demonstrate and evaluate an advanced digital mobile satellite terminal developed at the Jet Propulsion Laboratory under the NASA Mobile Satellite Program. The experiment was a significant milestone for NASA/JPL, since it was the first test of the mobile terminal in a true mobile satellite environment. The results were also of interest to the general mobile satellite community because of the advanced nature of the technologies employed in the terminal

Anaerobic digestion and gasification of seaweed

The potential of algal biomass as a source of liquid and gaseous biofuels is a highly topical theme, with over 70 years of sometimes intensive research and considerable financial investment. A wide range of unit operations can be combined to produce algal biofuel, but as yet there is no successful commercial system producing such biofuel. This suggests that there are major technical and engineering difficulties to be resolved before economically viable algal biofuel production can be achieved. Both gasification and anaerobic digestion have been suggested as promising methods for exploiting bioenergy from biomass, and two major projects have been funded in the UK on the gasification and anaerobic digestion of seaweed, MacroBioCrude and SeaGas. This chapter discusses the use of gasification and anaerobic digestion of seaweed for the production of biofuel

Distributed space-frequency coding for cooperative diversity over broadband relay channels with DF relaying

Multipath fading is one of the main challenges in transmission over wireless broadband relay channels due to frequency selectivity, which may deteriorate the received signal. Exploiting the extra source of multipath diversity, aside from cooperative (user) diversity, is important when coping with these wireless channel limitations. In this correspondence, we propose a new distributed space-frequency code (SFC) for broadband fading relay channels that can exploit both the spatial and multipath diversities in a distributed fashion. An upper bound for pairwise error probability (PEP) is derived, and from this PEP bound, we show that the proposed code achieves a diversity of order NL, where N is the number of relay nodes, and L is the channel memory length. The decode-and-forward (DF) protocol and erroneous decoding at the relay nodes are considered. Moreover, it is shown that the proposed code structure achieves the maximum coding gain among the linearly coded systems over channels with uniform power delay profiles

Characterization of low temperature creep properties of crack sealants using bending beam rehometry

The purpose of this research was to develop performance guidelines for the selection of hot-poured bituminous crack sealants at low temperature. In this part of the research, the creep behavior of crack sealant at low temperature is measured and performance criteria for material selection were developed. Because various pavement and State agencies are well acquainted with and own the Bending BeamRheometer (BBR), which was developed during the Strategic Highway Research Program (SHRP), an attempt was made to utilize the same setup to test hot-poured bituminous-based crack sealants. Testing conducted in this research project indicated that the standard BBR was inappropriate for testing soft bituminous-based hot-poured crack sealant, even at -40\ub0C. The measured deflection exceeded the BBR limit, for some sealants, after only a few seconds of loading. To address this issue, the moment of inertia of the tested beam was increased by doubling its thickness (from 6.35mm to 12.7mm). For the new beam dimensions, it was found that only 4% of the beam center deflection is due to shear, a value deemed acceptable for sealant evaluation and comparison.Cette recherche avait pour but de d\ue9velopper des lignes directrices de performance pour la s\ue9lection des scellants \ue0 fissures bitumineux coul\ue9s \ue0 chaud destin\ue9s aux applications \ue0 basses temp\ue9ratures. Dans cette partie de notre recherche, le comportement de fluage du scellant \ue0 fissures \ue0 basses temp\ue9rature est mesur\ue9, et les crit\ue8res de performance pour la s\ue9lection du mat\ue9riau sont mis au point. Comme divers services des chauss\ue9es et organismes d?\ue9tat sont d\ue9j\ue0 bien familiaris\ue9s avec le rh\ue9om\ue8tre de flexion (RF) qui a \ue9t\ue9 mis au point dans le cadre du Programme strat\ue9gique de recherche routi\ue8re du Canada, et en sont propri\ue9taires, on a tent\ue9 d?utiliser la m\ueame installation dans le but de mettre \ue0 l?essai les scellants \ue0 fissures bitumineux coul\ue9s \ue0 chaud. Les essais men\ue9s lors de ce projet de recherche ont indiqu\ue9 que le RF standard s?est r\ue9v\ue9l\ue9 inad\ue9quat pour tester le scellant \ue0 fissures bitumineux coul\ue9 \ue0 chaud mall\ue9able (\uab mou \ubb), m\ueame \ue0 une temp\ue9rature de -40 \ub0C. La d\ue9flexion mesur\ue9e d\ue9passait le seuil du RF avec certains scellants, au bout de seulement quelques secondes de mise en charge. Pour r\ue9soudre ce probl\ue8me, on a augment\ue9 le moment d'inertie de la poutre test\ue9e en doublant son \ue9paisseur (de 6,35 mm \ue0 12,7 mm). Pour les nouvelles dimensions de poutre, on a d\ue9couvert que seulement 4 % de la flexion de la poutre en son milieu est attribuable \ue0 l'effort tranchant, valeur jug\ue9e acceptable aux fins de l'\ue9valuation et de la comparaison.Peer reviewed: NoNRC publication: Ye