Fiber‐reinforced nanocomposite seismic isolators: Design and manufacturing

Fiber‐reinforced elastomeric isolator (FREI) is a new generation of seismic isolation device in which steel plates are replaced by fiber reinforcement. The essential characteristic of the elastomeric isolator is a very large ratio of the vertical to horizontal stiffness. This is somehow provided in FREI by resembling to steel reinforced elastomeric isolators (SREI). In this work, a comparative experimental analysis is presented to evaluate the performance of fiber‐reinforced nanocomposite elastomeric isolator (FRNEI) with FREI. FRNEI was manufactured based on nanocomposite rubber compound. The results clearly indicate an increase of 20% in the ratio of the vertical to horizontal stiffness for FRNEI when compared with FREI. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Copper chloride modified copper electrode: Application to electrocatalytic oxidation of methanol

Copper chloride modified copper (CCMC) electrode was prepared as a new electrode. For the preparation of the modified electrode, the polished copper electrode was placed in 0.1 M CuCl₂ solution for 20 s. In this step, a layer of copper (I) chloride was formed at the surface of copper electrode. Then, the electrode was placed in 0.1 M NaOH and the electrode potential was cycled between −250 and 1000 mV (vs. SCE) at a scan rate of 50 mV s⁻¹ for 5 cycles in a cyclic voltammetry regime until a featureless voltammogram was obtained. Surface physical characteristics of the modified electrode were studied by scanning electron micrographs (SEM). Results showed that considerable amounts of microcrystals have been formed on the copper surface during the modification. Surface elemental analysis of electrode were performed by energy dispersive X-ray (EDX) technique. The results showed that in addition to copper and chloride elements, there is also oxygen at the surface of CCMC electrode. This indicates that a layer of (ClCu)₂O was formed at the surface of the modified electrode. The electrocatalytic activity of the modified electrode for the oxidation of methanol, in aqueous basic solution was studied by using cyclic voltammetry. Results showed that, copper chloride modified electrode can improve the activity of Cu towards the oxidation of this small organic molecule, showing the possibility of attaining good electrocatalytic anodes for fuel cells. The modified electrode shows a stable and linear response in the concentration range of 5 × 10⁻³ to 8 × 10⁻² M with a correlation coefficient of 0.9958.     

AQM controller design for TCP networks based on a new control strategy

When the network suffers from congestion, the core or edge routers signal the incidence of congestion through the active queue management (AQM) to the sources. The time-varying nature of the network dynamics and the complex process of retuning the current AQM algorithms for different operating points necessitate the development of a new AQM algorithm. Since the non-minimum phase characteristics of the network dynamics restrict direct application of the proportional-integral-derivative (PID) controller, we propose a compensated PID controller based on a new control strategy addressing the phase-lag and restrictions caused by the delay. Based on the unstable internal dynamics caused by the non-minimum phase characteristics, a dynamic compensator is designed and a PID controller is then allowed to meet the desired performance objectives by specifying appropriate dynamics for the tracking error. Since the controller gains are obtained directly from the dynamic model, the designed controller does not require to be tuned over the system operating envelop. Moreover, simulation results using ns2 show improvements over previous works especially when the range of variation of delay and model parameters are drastic. Simplicity, low computational cost, self-tuning structure and yet considerable improvement in performance are exclusive features of the proposed AQM for the edge or core routers.     

Compatibilized Polypropylene/Ethylene–Propylene–Diene-Monomer/Polyamide6 ternary blends: Effect of twin screw extruder processing parameters

Polypropylene (PP)/Polyamide6 (PA6)/Ethylene–Propylene–Diene-Monomer (EPDM) (70/15/15) ternary polymer blends compatibilized with Maleic-anhydride grafted EPDM (EPDM-g-MA) were prepared by melt blending using a twin screw extruder (TSE). Effect of TSE processing parameters including barrel temperature, screw speed and blending sequence on the mechanical properties of ternary polymer blends was investigated by application of Taguchi experimental design methodology. Three different levels of barrel temperature (220 °C, 230 °C, 240 °C), screw speed (90 rpm, 120 rpm, 150 rpm) and blending sequence (nominated as: S1, S2 and S3) were selected. The response variables were tensile properties and impact strength of the prepared samples which are directly affected by the blend microstructure. Investigation of the statistical–mathematical analysis results performed by the software depicted that the optimum processing conditions for the ternary blends investigated here, to achieve balanced tensile and impact properties, are 220 °C, 150 rpm and S2 blending sequence.     

Salep‐g‐poly(sodium acrylate)/alumina superabsorbent hydrogel composite as a smart material: Irradiation synthesis and investigation of its swelling behavior

A novel environmentally sensitive superabsorbent composite was synthesized via the gamma (γ)‐irradiation graft copolymerization of sodium acrylate onto a homogeneous blend of natural salep and alumina in an aqueous medium. The reaction parameters (i.e., acrylic acid amount, neutralization percentage, alumina/salep weight ratio, and γ‐irradiation total dose) affecting the water absorbency of the hydrogel composite were optimized by using a systematic method in order to achieve a composite with as high a swelling capacity as possible. FTIR spectroscopy was used to confirm the structure of the final product. Morphology of the synthesized composite was examined by scanning electron microscopy. The swelling behavior of the optimum superabsorbent composite was measured in various environments, and the results showed excellent on–off switching behaviors which made this novel smart composite material a nominee that can potentially be used in agriculture, pharmaceutics, and biosensors. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Evaluation of the Effects of Rotary Degassing Process Variables on the Quality of A357 Aluminum Alloy Castings

Metallurgical and Materials Transactions B - The effects of rotary degassing process variables on the melt and casting quality have been investigated using reduced pressure test results and quality...     

Novel Nanoporous Superabsorbent Hydrogel Based on Poly(acrylic acid) Grafted onto Salep: Synthesis and Swelling Behavior

Hydrogels of poly(acrylic acid) grafted onto salep with excellent water absorption and water retention abilities under neutral conditions were successfully synthesized for the first time and employed for different applications. The effect of reaction variables to achieve maximum swelling capacity was investigated. In our procedure, ammonium persulfate (APS) as a water‐soluble initiator and methylenebisacrylamide (MBA) as a suitable crosslinking agent were used and the best synthesis conditions described. The structure of the final product was confirmed by Fourier‐transform infrared (FTIR) spectroscopy, scanning electron microscopy SEM and TGA analysis and a mechanism for superabsorbent hydrogel formation was also suggested. The study of the surface morphology of hydrogels using SEM showed a highly nanoporous and cellular structure for the sample obtained under optimized condition. Furthermore, several factors which influence the water uptake of hydrogels, such as pH of water, sensitivity to salt solutions and solvent mixtures were examined.     

Phase equilibrium studies in the “MnO”-Al2O3-SiO2 system

Phase relations and the liquidus surface in the system “MnO”-Al₂O₃-SiO₂ at manganese-rich alloy saturation have been investigated in the temperature range from 1373 to 1773 K. This system contains the primary-phase fields of tridymite and cristobalite (SiO₂); mullite (3Al₂O₃·2SiO₂); corundum (Al₂O₃); galaxite (MnO·Al₂O₃); manganosite (MnO); tephroite (2MnO·SiO₂); rhodonite (MnO·SiO₂); spessartine (3MnO·Al₂O₃·SiO₂); and the compound MnO·Al₂O₃·2SiO₂.