Node counting in wireless ad-hoc networks

We study wireless ad-hoc networks consisting of small microprocessors with limited memory, where the wireless communication between the processors can be highly unreliable. For this setting, we propose a number of algorithms to estimate the number of nodes in the network, and the number of direct neighbors of each node. The algorithms are simulated, allowing comparison of their performance

Classification of Low Dimensional Lie Super-Bialgebras

A thorough analysis of Lie super-bialgebra structures on Lie super-algebras osp(1|2) and super-e(2) is presented. Combined technique of computer algebraic computations and a subsequent identification of equivalent structures is applied. In all the cases Poisson-Lie brackets on supergroups are found. Possibility of quantizing them in order to obtain quantum groups is discussed. It turns out to be straightforward for all but one structures for super-E(2) group.Comment: 15 pages, LaTe

Characterisation of oil sludges from different sources before treatment: high-field nuclear magnetic resonance (NMR) in the determination of oil and water content

Oil sludges are wastes from the oil industry containing complex mixtures of oil hydrocarbons, water, sediments, and heavy metals. These wastes are of main importance for the petroleum industry since it is estimated that more than a billion tons have been stored worldwide. There are several types of oil sludges, but the oil tank bottom sludges are the most studied. Therefore, it is necessary to analyse a variety of oil sludges to establish a detail characterisation, with fast and reliable methods before selecting a suitable treatment. Five sludges were analysed in this study: an oil drilling, oil refinery, oil-water separator, and two waste engine oil sludges. This is a rare report detailing the use of high-field (500 MHz) nuclear magnetic resonance (NMR) to determine oil and water contents in oil sludges, which are more commonly analysed by low-field NMR (below 100 MHz). The proposed NMR procedure was validated by the analysis of oil-water calibration standards (experimental errors < 15%). There was a good agreement among the data obtained from the 1D proton spectra and the Carr-Purcell- Meiboom-Gill (CPMG) T2 decays (percentage differences < 5%). The T2 decays data showed that all sludges had only two components attributed to oil and water, and their relative ratios were determined. The sediment content was determined by the oven-drying method, and the oil hydrocarbon fractions and trace elements were assessed. The oil sludges presented different ranges in the oil, water, sediment and heavy metals contents. The higher presence of C10-C18 aliphatic fractions in the oil from the sludges was an indicator of the potential to be reused as diesel fuel. The sludges had potentially toxic elements (PTEs) values under the limit of the landfilling standards established by the European Union, except for the WSS sludge. Ca and Fe had the highest concentrations in all sludges, which are characteristic of these wastes. The techniques used in this study can be an alternative for a rapid characterisation of the oil sludges, so their most appropriate treatment can be established

Quality of wholemeal wheat bread enriched with green coffee beans

Scientific studies have revealed that bioactive components of coffee play a preventive role against various degenerative diseases. Green coffee, in particular, is characterized by its unique composition and properties. The objective of this work was to investigate the influence of green coffee (Coffea arabica) beans (GCB) addition on the quality and antioxidant properties (AA) of the wholemeal bread. For bread preparation, flour form GCB, and wholemeal wheat flour, type 2000 were used. Wholemeal wheat flour was replaced with GCB flour at 1 to 5% levels. Loaf volume, texture, color and sensory properties of bread were determined. Furthermore, total phenolic content and antioxidant activity were evaluated. The results showed that bread supplementation with GCB had little influence on the bread volume. The highest volume of bread was obtained with 3 and 4% of GCB flour. The texture properties of bread crumb (hardness, elasticity, cohesiveness and chewiness) were slightly changed as a result of the GCB addition. The lightness of bread crumb decreased with the GCB addition (average from 46.3 to 42.6). Besides, the addition of GCB significantly enriched wheat bread with hydrophilic phenolic compounds. The phenolic compounds were highly bioaccessible in vitro. Moreover, the GCB addition enhanced antiradical activity of bread

The Big Occulting Steerable Satellite (BOSS)

Natural (such as lunar) occultations have long been used to study sources on small angular scales, while coronographs have been used to study high contrast sources. We propose launching the Big Occulting Steerable Satellite (BOSS), a large steerable occulting satellite to combine both of these techniques. BOSS will have several advantages over standard occulting bodies. BOSS would block all but about 4e-5 of the light at 1 micron in the region of interest around the star for planet detections. Because the occultation occurs outside the telescope, scattering inside the telescope does not degrade this performance. BOSS could be combined with a space telescope at the Earth-Sun L2 point to yield very long integration times, in excess of 3000 seconds. If placed in Earth orbit, integration times of 160--1600 seconds can be achieved from most major telescope sites for objects in over 90% of the sky. Applications for BOSS include direct imaging of planets around nearby stars. Planets separated by as little as 0.1--0.25 arcseconds from the star they orbit could be seen down to a relative intensity as little as 1e-9 around a magnitude 8 (or brighter) star. Other applications include ultra-high resolution imaging of compound sources, such as microlensed stars and quasars, down to a resolution as little as 0.1 milliarcseconds.Comment: 25pages, 4 figures, uses aaspp4, rotate, and epsfig. Submitted to the Astrophysical Journal. For more details see http://erebus.phys.cwru.edu/~boss