Worms and viruses and botnets, oh my! Rational responses to emerging Internet threats

No longer satisfied with compromising and controlling individual computers, a new breed of hackers have set their sights on virtual networks of zombie systems, which they use in concert to accomplish various nefarious deeds. Beware the botnet.     

Paste Residence Time in a Spouted Bed Dryer. III: Effect of Paste Properties and Quality Interactions

The aim of this study was to evaluate the effects of paste properties on residence time during drying in a spouted bed dryer with inert bodies. The effect of paste solids content, surface tension, and viscosity on the residence time distribution and the mean residence times were studied using factorial experimental designs. The inert bodies used were glass and polyethylene beads. The mean residence times varied from 13.6 to 16.3 and 12.2 to 17.7 min for drying on glass and polyethylene beads, respectively. The analysis of variance showed that mean residence times significantly depended on solids content and surface tension for glass beads and also on viscosity for polyethylene beads. The residence time distributions for all conditions studied fitted well to the perfect mixing cell when applying the continuous stirred vessels in series model analysis. The powder density, flowability, and particle size depended on paste properties and inert type.     

Ceramics from mining by-products and alumina production wastes

The possibility of obtaining chemically stable ceramics in plastic molding from pastes based on comprehensive use of mining by-products (plagioporphyry, quartz-biotite shale), alumina production wastes (red mud), and polymineral clay was demonstrated. The mechanism of enhancing paste sintering on addition of finely disperse grog-flux and increasing the alkali resistance of the material (to 95%) in molding of the crystalline hematite-anorthite-quartz system was examined. __________ Translated from Steklo i Keramika, No. 2, pp. 17–20, February, 2007.     

Exact formulas for wave impedance and propagation constants ofhomogeneous, lossy dielectric and/or magnetic materials

Calculations of propagation constants for lossy materials are performed under the approximations of low loss (or high conductivity). To improve the understanding and better predict the analysis of such materials, exact formulation for wave impedance and propagation constants of homogeneous, lossy, dielectric/magnetic materials are proposed. Formulation is based on dielectric and/or magnetic loss tangent of the material     

Electron diffraction study of enzyme-hydrolyzed cotton samples

An electron diffraction study on continuously and repeatedly enzyme-hydrolyzed cotton samples was carried out. The electron diffraction pattern on repeatedly enzyme-treated sample reveals a cellulose I pattern with the absence of the 101 plane. This confirms that enzymatic hydrolysis of cotton fibers proceeds preferentially along the 101 plane, being a clevage plane.     

The use of reflectors in venetian blinds to enhance irradiance in greenhouses

Using a venetian blind as a basis, we describe and analyse novel forms of high-gain, nonfocussed sunlight concentrators and test experimental versions. Generally, midday winter light passing mainly through the roof of an E-W single-span greenhouse is reflected downwards to the floor through the use of conventional and modified reflecting louvres in a venetian-blind assembly suspended from the greenhouse apex. Experimentally, in a 7.3-m wide compartment, a 2-m deep conventional louvre assembly produced approximately an 18% gain in the southern half of the house, but a 4% loss in the northern half. A modified louvre assembly, which directs light to both halves of the house, gave, without readjustment of the louvre angle, 16% in the southern half and in the northern half. Under diffuse light conditions the blind was shown to produce an average 2% loss across the house. As a percentage of light received by the plant, as opposed to external irradiance, an average of 20% gain over the whole house width is predicted under sunny conditions if better manufacturing techniques are employed.Reasonable agreement with theoretical calculations of irradiance is also shown, and a theoretical analysis shows that full irradiance enhancement before and after midday, when oblique sunlight is incident on the reflector, will still be generally obtained.