Intermediate temperature oxidation in silicon nitride yttria ceramics

Silicon nitride billets with both 4% and 8% Y₂O₃ additives have been subjected to oxidation treatments for up to 300 h, in air, in the temperature range 700 to 1000° C. Flexure strength and weight gain measurements together with both scanning and transmission electron microscopy and X-ray diffraction studies were conducted on these billets in an effort to understand the oxidation process. It appears that the degradation phenomena is associated with both the formation of phases outside the Si₃N₄-Si₂ON₂-Y₂Si₂O₇ compatibility triangle of the system Si₃N₄-SiO₂-Y₂O₃ and with the decomposition of W-containing phases at and near the grain boundaries.     

Electrical,mechanical, and thermal properties of exfoliated graphite/phenolic resin composite bipolar plate for polymer electrolyte membrane fuel cell

Exfoliated graphite (EG) was synthesized from natural flake graphite by acid treatment followed by microwave irradiation. A maximum expanded volume of 560 mL/g was achieved for this exfoliation of graphite. EG/phenolic resin composite bipolar plates for polymer electrolyte membrane fuel cell were fabricated with a high loading of EG by compression molding. The composites possess low density, high electrical conductivity, high thermal stability, and high compressive strength. The composite bipolar plates were also characterized by X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and so on. The composite prepared with 50 wt% of EG has shown the desired properties for bipolar plate as per the US Department of Energy (DOE‐2015) targets. As a result, the EG–resin composites can be used as bipolar plates for polymer electrolyte membrane fuel cell applications. POLYM. ENG. SCI., 55:917–923, 2015. © 2014 Society of Plastics Engineers     

Effect of N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine antioxidant on the adhesion properties of (zinc oxide)‐filled (epoxidized natural rubber 25)‐based pressure‐sensitive adhesives

The effect of antioxidant, namely, N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine (IPPD), on the adhesion properties of epoxidized natural rubber (ENR 25)‐based pressure‐sensitive adhesive was investigated. The concentration of the IPPD was varied from 0 to 5 parts by weight per hundred parts of rubber (phr). Coumarone‐indene resin, zinc oxide, toluene, and polyethylene terephthalate were used as the tackifier, filler, solvent, and substrate, respectively. A Lloyd Adhesion Tester operating at different testing rates (10–60 cm/min) was used to determine the loop tack, peel strength, and shear strength at 60‐µm and 120‐µm coating thicknesses. Results indicate that adhesion properties increase with IPPD up to 2 phr of content, after which it decreases with further addition of the antioxidant. This observation is attributed to the culmination of wettability and compatibility at the optimum IPPD concentration. The 60‐µm coated sample consistently shows higher adhesion strength than that of 120‐µm coated sample. Loop tack and peel strength increase with testing rate up to 30 cm/min. However, shear strength increases with increasing testing rate in the testing rate investigated in this study. J. VINYL ADDIT. TECHNOL., 21:111–115, 2015. © 2014 Society of Plastics Engineers     

High-voltage DMOS integrated circuits using floating-gate protection technique

An efficient low power protection scheme for thin gate oxide of high voltage (HV) DMOS transistor is presented. To prevent gate-oxide breakdown and protect HV transistor, the voltage controlling its gate must be within 5 V from the HV supply. Thus signals from the low voltage domain must be level shifted to control the gate of this transistor. Usually this level shifting involves complex circuits that reduce the speed besides requiring of large power and area. In this paper, a simple and efficient protection technique for gate-oxide breakdown is achieved by connecting a capacitor divider structure to the floating-gate node of HV transistor to increase its effective gate oxide thickness. Several HV circuits, including: positive and negative HV doublers and level-up shifters suitable for ultrasound sensing systems are built successfully around the proposed technique. These circuits were implemented with 0.8 μm CMOS/DMOS HV DALSA process. Simulation and experimental results prove the good functionality of the designed HV circuits using the proposed protection technique for voltages up to 200 V.     

Stochastic modeling and generation of synthetic sequences of hourly global solar irradiation at Quetta, Pakistan

Using hourly global radiation data at Quetta, Pakistan for 10 yr, an Autoregressive Moving Average (ARMA) process is fitted. Markov Transition Matrices have also been developed. These models are used for generating synthetic sequences for hourly radiations in MJ/m² and that the generated sequences are compared with the observed data. We found the MTM approach relatively better as a simulator compared to ARMA modeling.     

Olive mills effluent (OME) wastewater post-treatment using activated clay

Olive mill effluent (OME) wastewater embodies a challenge for environmental scientists and engineers. It is characterized by high values of COD, BOD, and phenolic content. A series of treatment steps composed of settling, centrifugation, and filtration was consecutively used to condition OME wastewater. The filtrate was then subjected to a post-treatment process, namely adsorption on activated clay. The dynamic response of phenols concentration, pH, and COD, using different concentrations of activated clay, showed a peak at which maximum adsorption capacity was achieved. The maximum adsorption capacity for the tested concentrations of activated clay was reached in less than 4 h. It is thought that adsorption of phenols and organics is reversible and mainly due to hydrophobic interactions. The maximum removal of phenols was about 81%, while it reached about 71% for organic matter.     

Integrating Collaborative and Reclusive Methods for Effective Recommendations: A Fuzzy Bayesian Approach

Collaborative filtering (CF), the most successful and widely used technique, recommends items based on the preferences of similar users. The main potentials of CF are its cross‐genre recommendation ability, and that it is completely independent of representation of the items being recommended. However, CF suffers from sparsity and cold start problems. On the other hand, a highly effective variant of content‐based filtering (CBF), reclusive methods (RMs) based on the preference of the single individual for whom recommendations to be made, provides a methodology that considers uncertainty and the multivalued nature of item features as well as user preferences in a content‐based framework using fuzzy logic approaches. The adoption of RM paradigm has several advantages when compared to CF such as sparsity and new item problem, but it suffers from overspecialization and limited content analysis. In view of the complementary nature of CF and RM, we develop a hybrid recommender system (RS) that helps in alleviating aforementioned problems in each approach. First, we propose fuzzy naïve Bayesian classifier based CF (FNB‐CF) and RM (FNB‐RM) for handling correlation‐based similarity problems. To overcome individual weaknesses of FNB‐CF and FNB‐RM, we develop a hybrid RS, FNB‐CF‐RM. Effectiveness of our proposed hybrid RS is demonstrated through experimental results using the MovieLens and IMDb data sets.     

Engineering the system of communication for safer surgery

Communication failures are a leading cause of error in surgery. Researchers and practitioners have therefore developed different interventions to improve communications, such as team briefing and pre-operative patient checklists. These different methods have clear merit. However, they have only dealt with portions of a complex system. Consequently, disparate interventions of varying kinds may not integrate and build an effective system of communication. We argue that a new view of communication is needed to improve safety in surgery; the view that communication is more fundamentally as a property of the whole system of work rather than confined to interpersonal exchanges. Rather than simply add an intervention to the system, interventions should integrate into the system. To achieve this, we propose a practical strategy to re-engineer the system of communication for surgery. This demands an analysis of the immediate informational needs within the system of interest, and an account of the wider system and those ergonomic and human factors shaping the performance of communicators. We illustrate the application of the method and refer to potential improvements in safety.