A chemiometric approach for phosphate inhibition of copper corrosion in aqueous media

The inhibition of copper corrosion in aqueous media by inorganic phosphates has been studied using a chemiometric approach (experimental and simplex designs). To achieve the objective, four steps were recognized. When submitted to aqueous aggressive media, the anion nature and its concentration were the important variables for the explanation of the mass loss variation. The most corrosive experimental conditions were: anion: chloride (Cl⁻); concentration: [Cl⁻] = 1 mol/l; exposure time: 24 h. In the second step, two inorganic phosphates, Na₃PO₄ and Na₅P₃O₁₀, are tested as copper corrosion inhibitors when the material is submitted to the severe conditions. The chemical structure was found to be the most influent factor. However, %IE varies between 25% and 56%. Then, we recognized a passivating treatment by submitting copper to inhibitor solution before immersion in the aggressive medium. Three parameters were studied: inhibitor structure, chemical concentration and passivation time (tp). We concluded that tp is the most influent experimental factor. The best passivating conditions are: inhibitor: Na₅P₃O₁₀; inhibitor concentration: [Inhibiteur] = 10⁻² mol/l and passivation time: 3 h. The inhibition efficiency was 89%. To increase %IE, a simplex design was also performed starting by the above obtained conditions and using the polyphosphate (Na₅P₃O₁₀) as inhibitor. The optimum experimental conditions for phosphate inhibition of copper corrosion in aqueous media are: inhibitor: Na₅P₃O₁₀, [Na₅P₃O₁₀] = 0.017 mol/l and passivation time tp = 2.17 h. Under these conditions an inhibition efficiency of 98% was reached.     

An agent based system for activity monitoring on network – ABSAMN

Computer network as a force drags its customers to share more and more resources while on the other hand managing such network recourses is a challenging job for an IT professional and perhaps becoming difficult humanly. In this paper, we have proposed an agent based system for activity monitoring on network (ABSAMN) for the monitoring of resources over a network, suitable for network of networks; commonly known as CAN (campus area network). Multi-agent system is a system composed of several agents, collectively capable of achieving goals that are difficult to achieve by an individual agent or monolithic system. We propose the use of multi-agent system to ensure proper system operation by watching for inconsistencies in user activities, node level activity, internet monitoring, and system configuration. The system is fully autonomous and once initialized with the given rules and domain knowledge ABSAMN manages resources on its own with the help of mobile agents. We have evaluated this architecture on the university campus having seven labs equipped with 20–300 number of PCs in various labs. Results were very promising and support the implementation of the solution.     

Robust H ∞ output feedback control with pole placement constraints for uncertain discrete-time fuzzy systems

This paper investigates the problem of multi-objective control for a class of uncertain discrete-time fuzzy systems. The state-space Takagi–Sugeno T–S fuzzy model with linear fractional parameter uncertainties is adopted. Based on a linear matrix inequality approach and via so-called dynamic parallel distributed compensation, a fuzzy full-order dynamic output feedback controller is developed such that the L ₂ gain performance from the exogenous input signals to the controlled output is less than or equal to some prescribed value and, for all admissible uncertainties, the closed-loop poles of each local system are within a pre-specified sub-region of complex plane. Two numerical examples are provided to illustrate the effectiveness of the proposed design method.     

A diversity combining DS/CDMA system with convolutional encodingand Viterbi decoding

Averaged diversity combining is applied to an asynchronous DS/CDMA system using convolutional encoding and Viterbi decoding. A cyclic redundancy check (CRC) code is included in the scheme to trigger retransmission requests. Multiple received packets are combined on a bit by bit basis to form a single, more reliable packet. The error correcting decoder operates on the combined packet, as opposed to the most recently received individual packet (e.g., as in a type-I hybrid ARQ protocol), substantially increasing the probability of acceptance with each additional transmission. We show that the proposed technique allows a significant increase in the CDMA system capacity, throughput, and reliability     

The Effect of Rotation on Two-Dimensional Problem of a Fiber-Reinforced Thermoelastic with One Relaxation Time

In this article, the Lord–Shulman (L–S) theory with one relaxation time and coupled theory are applied to study the influence of reinforcement on the total deformation of a rotating thermoelastic half-space and the interaction with each other. The problem of a thermal shock has been solved numerically using normal mode analysis. Numerical results for the temperature, displacement, and thermal stress components are given and illustrated graphically for both L–S and coupled theories.     

Adhesion Improvement of Bio-Based Epoxy in Environmentally Friendly and High-Performance Natural Fiber-Reinforced Composites

Developing robust bio-based epoxy against petroleum-derived epoxy is necessary for environmentally friendly and high-performance natural fiber-reinforced composites. A bio-based vanillin epoxy (VE) is synthesized from the lignin-derived vanillin, and a thermoset resin is prepared after mixing it with a 4,4′-diaminodiphenyl methane (DDM) hardener. Further, it is infused in high-cellulose-containing alkali-treated jute fiber (TJF) mats through a simple approach to enhance the adhesion between the VE-DDM and TJF. Bio-based VE-DDM resin shows better compatibility with TJF than petroleum-derived bisphenol A diglycidyl ether (DGEBA) epoxy. The bio-based VE-DDM/TJF composite demonstrates the T_gis ≈165 °C, tensile strength is ≈83.12 ± 3.80 MPa, and Young's modulus is ≈2.86 ± 0.10 GPa with excellent flexural strength (138.72 ± 3.81 MPa) and flexural modulus (8.01 ± 0.11 GPa). It also shows merits regarding hydrophobicity, reduced water absorption ability, durability, and chemical resistance in an acidic medium. The natural fiber-reinforced VE composites pave the way to produce environmentally friendly and high-performance composites for structural applications.     

Photo Catalytic Behavior of some Pharmacosiderite Titanium Analogs

New titanosilicates of various framework topologies were synthesized using TEAOH template. This Ivanyukite (Na2[Ti4O2(OH)2(SiO4)3]•6H2O) and Sitinakite (H4.04Na1.64O8.84SiTi2) zeolites were synthesized hydrothermally and considered to be under Pharmacosiderite phases. Various conditions were investigated (i.e temperature, aging time and alkalinity), and the success was examined by using XRD, IR and SEM technologies. Due to the large effect of dyes on pollution and their toxicity, Malachite green dye used. The photocatalytic effect of the prepared zeolites were studied in the decomposition of dye, and it was found with high photocatalytic activity may approach 96%.     

Asymmetric Channel Junctionless Field-Effect Transistors: a MOS Structure Biosensor

Silicon - In this work, we carried out simulations to demonstrate the effects of using asymmetric channel thickness in conventional double gate junctionless field- effect transistors (DG JLFETs) by...     

Crystallization and Ability of Hydroxyapatite Formation in Some Trivalent Oxides Containing Na-Ca-Silicate Glass-Ceramics

The formation of glass-ceramics based on Na₂O–CaO-silicates containing P₂O₅ with minor additives of some trivalent oxides (e.g. La, In, Ga, and Al), has been investigated. Different crystalline phases including sodium-orthosilicate containing lanthanum, or aluminum were formed together with Na₂Ca₂Si₃O₉, NaInSi₂O₆, and Na₃Ga₂Si₃O₁₀. The nature and mechanism of HA formed in the glass-ceramics are considered. In general, the presence of trivalent oxides in the glass-ceramics progressively reduced the ability to form a calcium phosphate layer on the surfaces of the materials. The addition of In₂O₃ decreased the crystallization of the hydroxyapatite layer. However, in the presence of either Ga₂O₃ or Al₂O₃ only the amorphous calcium phosphate layer was formed after the immersion of the crystallized specimens in the SBF solution.