Intelligent and independent processes for overcoming big graphs

Poor locality as a natural property of graph data structures causes enormous amount of network traffic in large-scale distributed graph processing systems. Moreover, data transmission through the network is one of the most expensive operations in a distributed system. Therefore, reduction of network usage is highly required by a new graph computational model. In this paper, increasing the degree of machine independency has been considered a key factor of network traffic reduction. The proposed system benefits from a three-layered computational model to perfectly leverage the power of local information as much as possible. Moreover, this model simultaneously takes the advantages of both message-based and shared-state communication paradigms. Vertices can read and update values of others in the lowest layer directly, while they must send messages in other layers. By the use of memorization techniques, the proposed model introduces a new kind of intelligence that has encouraging effects on removing useless communications. Distinctive results of our experiments confirm significant improvements of the proposed model in relation to the previous systems like Pregel, GPS, and Blogel, as well as ExPregel. The results also show that the overhead of making processes independent along with intelligent is negligible in comparison with the cost of additional network communications.     

Cryptanalysis of an iterated halving-based hash function: CRUSH

Iterated Halving has been suggested as a replacement to the Merkle?Damga?rd (MD) construction in 2004 anticipating the attacks on the MDx family of hash functions. The CRUSH hash function provides a specific instantiation of the block cipher for Iterated Halving. The authors identify structural problems with the scheme and show that they can trivially identify collisions and second preimages on many equal-length messages of length ten blocks or more. The cost is ten decryptions of the block cipher, this being less than the generation of a single digest. In addition, these attacks can be used to differentiate CRUSH from a random oracle in O(1). The authors show that the complexity of finding a preimage in the unpadded CRUSH with the length encoding is negligible and extend this attack on CRUSH with the length encoding in cost O(2/sup 32/). This attack is a multi-preimage attack, since the attacker can produce a large number of messages for a given message digest for the cost of O(2/sup 32/). Hence, this attack can be used as a multi-collision and a multisecond- preimage as well. They show that if the attacker knows the last 64-bits of the message digest in advance, he can do the time-consuming part of the attack off-line. The authors show that even if Iterated Halving is repaired, the construction has practical issues that means it is not suitable for general deployment.     

Cathodic electrodeposition of Y(OH)3 and Y2O3 nanostructures from chloride bath. Part II: Effect of the bath temperature on the crystal structure,composition and morphology

Ultra-fine nanoparticles, mono-dispersed nanospheres and nanorods of Y(OH)₃ and Y₂O₃ were successfully prepared via electrodeposition from chloride bath at different temperatures of 10, 25, 40 and 80 °C followed by heat-treatments at 600 °C in dry air atmosphere. Thermal behavior of the hydroxide samples was investigated by differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The structural and morphological characteristics of the products were determined by X-ray diffraction (XRD), FT-IR, scanning and transmission electron microscopy (SEM and TEM). Effects of bath temperature on the mechanism of base electrogeneration and deposit formation on the cathode surface were proposed and discussed. The results showed that the crystal structure, composition and morphology of the products are mainly affected by the temperature of electrodeposition bath.     

The Ablation and Oxidation Behaviors of SiC Coatings on Graphite Prepared by Slurry Sintering and Pack Cementation

SiC coatings were generated on graphite using slurry sintering (SS) and pack cementation (PC). The samples’ ablation features were assessed by an oxyacetylene torch. The rates of mass ablation of the PC–SiC and SS–SiC coatings were approximated 2.17?×?10^?3 and 9.52?×?10^?3 g s^?1, respectively, decreased by 84.1 and 29.6% compared to the uncoated samples. It was mainly attributed to the formation of a SiO₂ layer on the surface. The continuous SiO₂ molten film formed via the PC–SiC oxidation generates a sealing mechanism which can be an obstacle against the oxygen diffusion and hinder more ablation. This is while discontinuous SiO₂ film formed from the thin SS–SiC cannot protect the graphite effectively. The non-isothermal oxidation test shows that without the SiC coating, the sample weight is lost largely from 25 to 1500 °C, and its weight loss was 2.2% after the TGA. However, after coating, the samples possessed excellent oxidation protection and weight losses of SS–SiC and PC–SiC coatings are down to 1.3 and 0.6%, respectively. The more oxidation of the graphite substrate occurred due to the formation of macrocracks in the coating during the TGA and also the formation of holes on SiO₂ glass layer owing to release of CO or CO₂.     

Effect of carbon steel microstructures and molecular structure of two new Schiff base compounds on inhibition performance in 1 M HCl solution by EIS

In this investigation, attempts have been made to study the inhibitive effect of N,N′-ortho-phenylen acetyle acetone imine (S1) and 4-[(3-{[1-(2-hydroxy phenyl) methylidene] amino} propyl] ethanemidol]-1,3-benzenediol (S2) in the concentration range of 50–400 ppm for mild steel with two different microstructures resulted from two different heat treatments (annealed (A) and quenched and tempered (Q&T)) in 1 M hydrochloric acid by ac impedance spectroscopy. The tests were conducted in acid solutions in the absence and presence of different concentrations of S1 and S2 Schiff bases for both microstructures. A sole time constant was observed from Bode-phase angle plots in the presence of inhibitors which reveals that the action of inhibitors is through adsorption on the surface. The charge transfer resistance and inhibition efficiency increases with the increase in Schiff bases concentration for both microstructures. The perlite samples in the absence of inhibitors in 1 M hydrochloric acid indicated slightly less corrosion than martensite ones, which was because of more protective oxide layers. Furthermore in the presence of S1 and S2, these samples showed better adsorption than martensite one. Schiff base S1 showed a better inhibition against corrosion in comparison with S2. Both S1 and S2 adsorbed on steel surface according to a Langmuir adsorption isotherm model. The associated Gibbs free energies for S1 on both microstructures are more than S2.     

Synthesis and characterization of new polyurethanes: influence of monomer composition

Different polyurethanes (PU) were synthesized from polycaprolactone diol, 1.6-hexamethylene diisocyanate and bis(2-hydroxyethyl)terephthalate, using a two- and one-step methods providing regular and random distributions of starting monomers in the polyurethane chains. Even with an identical molar monomer composition, the properties of obtained PU are different depending on the method of synthesis. The chemical structure of PU was characterized by ¹H and ¹³C NMR spectroscopy, as well as by FTIR and UV–Visible spectroscopy. The thermo-mechanical and hydrophilic properties of synthesized PU were also studied demonstrating the influence of aromatic ring in the macromolecular chain.     

Post operative psychosis

The dimerization of the variable fragment of the Bence-Jones protein Au was examined in phosphate buffers at pH 6.8-6.9 And ionic strength of 0.1 M or 0.2 M at 20 degrees C. The dimerization constant was about 1 X 10(5) M-1. The reaction enthalpy was positive and the process was entropy driven. The association and dissociation rate constants were 9 X 10(6) M-1 s-1 and 1.5 X 10(2) s-1 respectively. Temperature-jump experiments exhibited the presence of two isomers of the dimer, which are present at equilibrium in a ratio of about 1:1. Isomerization occurred with a half-life of about 0.1 s.     

Vapour side corrosion in a ME desalination plant at Jebel Dhana

Jebel Dhana, from the Abu Dhabi Water and Electricity Authority (ADWEA), operates two 2 MGD multi-effect thermo-compression distillers commissioned in 1996. Tube failures were first reported approximately 16 months after commissioning. The initial tube failures were from the upper rows, but more recent failures were apparently randomly distributed throughout the tube bundle. Ten tubes were removed and their corrosion morphology was examined macroscopically and microscopically. The corrosion products were analysed by X-ray, EDAX, and EPMA techniques. The copper nickel alloy tubes were found to have suffered from vapour side corrosion; however, there was no sign of any copper oxide deposition, as has often been seen in failed tubes from MSF distillers. The failures took two forms: corrosion fatigue cracking, and pitting corrosion. The corrosion fatigue was in the form of a circumferential crack at a flat portion of the tube in the centre of a tube span. It was believed that the flat surface had developed as a result of fretting against a neighbouring tube, and had been worn away to the point of failure. Unfortunately, the position of the tubes in the tube bundle had not been identified during their removal, but it is suspected that the damaged tube had been in the top row, with the flattened portion directly below one of the two vapour inlet pipes. The other tubes sampled showed pitting corrosion. Some of the pitting had perforated the tube walls whilst others showed pitting on the outer surface only. Some of the pits contained corrosion products whilst others were free of them. This pitting corrosion is attributed to the formation of carbonic acid in the presence of oxygen (air). A weak acid is formed due to the dissolution of CO₂ in the condensing water vapour. The gas concentration varies within the tube bundle, due to the vapour phase, allowing the gas concentration to increase in specific areas of the tube bundle, causing the non-uniformity of attack. There was no immediate tie-up between the pitting corrosion and the two steam inlet pipes due to the unknown position of the sampled tubes within the tube bundle. It is recommended that the oxygen level be reduced by ensuring that the distiller vessels are as air-tight as possible, thus reducing the tendency towards pitting corrosion.