Selfish node detection in ad hoc networks based on fuzzy logic

Neural Computing and Applications - Generally, the ad hoc networks work correctly only if all nodes cooperate in the routing and forwarding of the packets. However, in some cases, selfish nodes are...     

Hydrothermal Preparation, Crystal Structures, Spectroscopic and Thermal Analyses of Cadmium(II) and Cobalt(II) Coordination Polymers With Pyridine-2,3-dicarboxylic Acid

Two novel 1D coordination polymers, [M(μ-2,3-pydc)(H₂O)₃]_n (M = Cd for 1 and Co for 2) (2,3-pydcH₂ = pyridine-2,3-dicarboxylic acid) have been hydrothermally synthesized. Both complexes were characterized by elemental analysis and by IR and UV–Vis spectroscopy. Their molecular and crystal structures were determined by X-ray crystal structure analysis and their thermal stability by TGA-DTA methods. Compound 1 crystallizes in the orthorhombic Pca2 space group, while compound 2 crystallizes in the triclinic P−1 space group. Polymeric chains of 1 and 2 are composed of M(II) ions bridged by pyridine-2,3-dicarboxylate ions (2,3-pydc) in N,O,O′ fashion. Distorted octahedral coordination geometry around the metal ions is completed by three water molecules. A wide range of hydrogen bonding (of the O–H···O type) is also present in the crystal structures. These interactions lead to formation of a 3D structure for 1 and 2D network for 2.     

The effect of agarose content on the morphology,phase evolution,and magnetic properties of CoFe2O4 nanoparticles prepared by sol‐gel autocombustion method

Hard‐magnetic CoFe₂O₄ nanoparticles were produced with the sol‐gel autocombustion route using agarose and citric acid as a neutral organic gel and combustion agent. For this purpose, the obtained gel is annealed at 800°C for 3 hours and then the spinel structure of the samples was confirmed by X‐ray diffraction (XRD). In addition, the existence of metal‐oxygen complexes in the gel and nanoparticles was investigated by Fourier transformation infrared (FTIR) spectra. Furthermore, FESEM images showed that semispherical and rod‐like particles were obtained by variation in agarose contents. For the rod‐like sample with 2.5 g agarose, the saturation magnetization and coercivity were measured equal to 71.7 emu/g and 10076.84 Oe, respectively.     

Development of ZrO2‐MgO nanocomposite powders by the modified sol‐gel method

The ZrO₂‐MgO nanocomposites were synthesized using a new sol‐gel method with sucrose and tartaric acid as a gel agent. The samples were characterized by thermal analysis (TG/DTA), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy‐dispersive X‐ray mapping (EDX mapping), and Ultraviolet‐visible spectroscopy (UV‐vis). The results showed that the cubic phase of ZrO₂‐MgO was formed in the presence of both gel agents. The average particle size of the samples synthesized with sucrose was lower (30 nm) than that of tartaric acid (50 nm). Finally, the formation mechanism and the optical properties of zirconia‐magnesia have been discussed.     

Acylation of Pyrroles and their Free (N‐H)‐Derivatives via Palladium‐Catalyzed Carbopalladation of Nitriles

An efficient regioselective synthesis of 2‐acylpyrroles via palladium‐catalyzed addition of pyrroles with benzonitriles and subsequent hydrolysis is developed. The direct acylation reaction of protected as well as (NH)‐free pyrroles proceeded smoothly to afford 2‐acylpyrrole scaffolds of high biological interest.

     

Effect of Phosphorous Inoculation on Creep Behavior of a Hypereutectic Al-Si Alloy

Creep behavior of Al-Si hypereutectic alloys inoculated with phosphorus was investigated using the impression creep testing. The results showed that at stress regimes of up to 400-450 MPa and temperatures up to 300 °C, no significant creep deformation occurred in both uninoculated and inoculated specimens; however, at temperatures above 300 °C, the inoculated alloys presented better creep properties. Creep data were used to calculate the stress exponent of steady-state creep rate, n, and creep activation energy, Q, for different additive conditions where n was found varied between 5 and 8. Owing to the fact that most alloys have lower values for n (4, 5), threshold stress was estimated for studied conditions. The creep governing mechanisms for different conditions are discussed here, with a particular attention to the effect of phosphorous addition on the microstructural features, including number of primary silicon particles, mean primary silicon spacing, and morphology and distribution of eutectic silicon.     

Non-Isothermal Kinetic Analysis of Oxidation of Pure Aluminum Powder Particles

Non-isothermal kinetic analysis of oxidation of aluminum powder particles (100–200 μm) was investigated by simultaneous thermogravimetry (TG) and differential thermal analysis under linear temperature programming (ranging from 25 to 1,400 °C) at different heating rates (10, 20 and 30 °C/min). In addition, the rate of oxidation reaction (rate of thermogravimetry; RTG) was obtained by the RTG curves. It was found that the oxidation of aluminum powders took place over several stages and the complete oxidation process did not occur even up to 1,400 °C. Among different stages, the temperature ranging from 1,000 to 1,150 °C was identified as the main stage for oxidation process. Hence, kinetic analysis of non-isothermal was determined to be carried out in this region only. Therefore, non-isothermal kinetic analysis of oxidation of pure aluminum powder particles was performed using isoconversional methods (Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Friedman ), Markworth and Coats–Redfern methods. Also, the empirical kinetic triplets [E _a , A, and f(α)] have been calculated.