HSDN‐GRA: A hybrid software‐defined networking‐based geographic routing protocol with multi‐agent approach

We propose in this paper a Hybrid Software‐Defined Networking‐based Geographical Routing Protocol (HSDN‐GRA) with a clustering approach. It takes into account three different criteria to select the best relay to send data: (1) the contact duration between vehicles, (2) the available load of each vehicle, (3) and the log of encountered communication errors embedded in each cluster head. The multi‐criteria strategy allows the selection of the most reliable vehicles by avoiding communication problems and ensuring connection availability. Once the hybrid control plane has found out the next eligible neighbor, the data plane will be in charge of dividing and sending data. To validate our approach, HSDN‐GRA has been modeled and implemented in JADE, a multi‐agent platform, to be compared to other multi‐agent based protocols. Simulation results show that HSDN‐GRA achieves good performance with respect to the average routing overhead, the packet drop rate, and the throughput.     

GrAFCI+ A fast generator-based algorithm for mining frequent closed itemsets

Knowledge and Information Systems - Mining itemsets for association rule generation is a fundamental data mining task originally stemming from the traditional market basket analysis problem....     

Microstructure investigation and thermal stability of 99.1% aluminum processed by equal channel angular extrusion

Microstructure evolution of 99.1% aluminum after equal-channel angular extrusion (ECAE) and subsequent heat-treatment was investigated. After deformation the samples were annealed at different temperatures. The deformed and annealed states were characterized by Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and microhardness tests. It was shown that the observed microstructure changes during subsequent annealing have to be associated with recovery and cells formation. The initial stages of recovery were investigated using weak-beam technique. The microstructure obtained after annealing for 1 h at 100 °C consists of some arrangements of the dislocations into sub-grain boundaries within the wide preexisting grains. Annealing at 300 °C led to the appearance of a duplex microstructure consisting of bands of slightly coarsened grains associated with refined grains. No growth of dislocation cells was observed up to 400 °C. In XRD measurements, the lattice parameter increase with subsequent heating. This indicates a continuous grain growth during annealing. This is due to the important increase of coherency length, D observed parallel to a substantial decrease of rms-strain, ε.     

Characterization of the kinetic and mechanistic differences between free-surface and bulk grain growth in WC-Co materials

The rate of grain growth at different high temperatures in the bulk and at the free surface of a WC-Co substrate was measured. The microstructure, phase evolution, and elemental composition at the free surface were characterized at various stages of the grain-growth process and compared to equivalent characteristics of the bulk. A dramatic difference in the rate of grain growth between the free surface and the bulk of the material was observed. Grains in the free surface grew at a much faster rate than those in the bulk. Since this fast rate of growth was found to coincide with the vaporization of the binder phase from the free surface, it is suggested that this increase in the rate of growth is related to a change in the growth mechanism from an interfacial reaction limited growth in the bulk to a surface diffusion rate limited growth at the free surface. The contact points between grains provide bridges for atomic transport from high free-energy regions (small grains) to low free-energy regions (large grains); hence, the contiguity of the material has a strong influence on the rate of growth.     

Structural,morphological and electrical properties of Cr2O3 nanoparticles

Chromium oxide (Cr₂O₃) nanoparticles have been prepared by chemical precipitation followed by calcination at high temperatures. The influence of calcination temperature on the particle size, microstructure, surface area and morphology was examined by X-ray diffraction, Fourier transform infrared, N₂ adsorption–desorption isotherms, transmission electron microscopy and thermal analysis techniques. The results indicate the formation of a nanosized single Cr₂O₃ phase. The particles possess high specific surface area and mesoporous structure, and their sizes increase with increasing the calcinations temperature. DC conductivity was measured in the temperatures range of 170–475 K. For the high temperature region, the conduction was found to be due to small polaron hopping of holes. While for the low temperatures region, the conduction was attributed to variable range hopping mechanism of holes. The temperature dependence of the AC conductivity and dielectric constant was investigated in the same temperature range at four test frequencies. In addition, the impedance spectra of these nanoparticles were investigated only at temperatures above 350 K.     

Cultured rat and purified human Pneumocystis carinii stimulate intra- but not extracellular free radical production in human neutrophils

The production of free radicals in human neutrophils was studied in both Pneumocystis carinii derived from cultures of L2 rat lung epithelial-like cells and Pneumocystis carinii purified from human lung. Using the cytochrome C technique, which selectively measured extracellular superoxide generation, hardly any free radical production was observed after stimulation with cultured rat-derived P. carinii. A chemiluminescence technique, which separately measured intra- and extracellular free radical production, was subsequently employed to differentiate the free radical generation. It was established that 1) P. carinii stimulated intra- but not extracellular free radical production in human neutrophils, 2) opsonized cultured rat-derived P. carinii stimulated human neutrophils to a strong intracellular response of superoxide production, and 3) opsonized P. carinii, purified from human lung also stimulated human neutrophils to produce intracellular free radicals.     

Mathematical modeling and computer simulation of the rotating impeller particle flotation process: Part II. Particle agglomeration and flotation

Effective removal of unwanted particles from a molten metal alloy by flotation relies on purging a gas into the melt through a rotating impeller. This device is commonly known as a rotary degasser. Unwanted particles in the melt attach to the rising gas bubbles and rise to the slag layer where they are removed from the metal bulk. In addition, the turbulence created by the rotating impeller causes the randomly distributed solid particles to agglomerate into relatively large clusters. These clusters float up or settle down due to the difference between their density and that of the melt. A mathematical model has been developed to describe the particle dynamics and particle agglomeration that occur during the rotary degassing of aluminum melts. While previous investigations addressed particle collisions in low intensity turbulent fields where the size of the colliding particles is smaller than the Kolmogorov length scale, this model is more encompassing as it considers both low intensity and high intensity turbulence. Consequently, this model is more representative of a typical industrial rotary degassing operation.     

In vitro attachment of Pneumocystis carinii from mouse and rat origin

Cigarette smoking has been shown to increase consequent to the acute administration of methadone. This suggests the possibility that differences in maintenance dose levels might be associated with differential smoking rates. It is of special concern that higher maintenance levels of methadone may lead to more cigarette smoking because of the putative beneficial effects of higher doses on illicit drug use, treatment retention, and the like. Two experiments were conducted to test the hypothesis that higher maintenance doses of methadone are related to more cigarette smoking. Smoking was measured by self-report and expired carbon monoxide, and the amounts were correlated with subjects' methadone dose levels. The results showed smoking rates of 85% and that self-reported smoking significantly correlated (r = -.52) with CO. Maintenance doses, however, were not correlated with smoking levels. This suggests that the acute effects of methadone on smoking are nullified as clients habituate to dose level, and that decisions regarding appropriate methadone dosage can be made on other grounds.