Role of Ce-Mn substitution on structural, electrical and magnetic properties of W-type strontium hexaferrites

W-type hexaferrites with nominal composition Sr_1−xCe_xCo₂Mn_yFe_16−yO₂₇ (x = 0.00, 0.02, 0.04, 0.06 & y = 0.0, 0.2, 0.4, 0.6) has been synthesized by the chemical co-precipitation method. The effect of substitution of Ce at Sr & Mn at Fe site on the structural, magnetic and electrical properties has been investigated. The XRD patterns confirm single W-type hexaferrite phase and various parameters such as lattice constants (a & c), cell volume (V), crystallite size (D), X-ray density (d_x), bulk density (d_b) and porosity (P) were calculated from XRD data. The crystallite size is found in the range of 22.5-30 nm and this size is small enough to obtained suitable signal-to-noise ratio in high density recording media. The magnetic properties such as saturation magnetization, remanence, squareness ratio and coercivity were calculated from hysteresis loops and were observed to increase with increase in Ce-Mn concentration up to a certain substitution level. The resistivity showed interesting behavior with temperature, showing metal-to-semiconductor transition temperature. The increase in saturation and remanence suggest that the synthesized materials can be used in the high density recording media.     

Modeling DBPs formation in drinking water in residential plumbing pipes and hot water tanks

Disinfection byproducts (DBPs) in municipal supply water are a concern because of their possible risks to human health. Risk assessment studies often use DBP data in water distribution systems (WDS). However, DBPs in tap water may be different because of stagnation of the water in plumbing pipes (PP) and heating in hot water tanks (HWT). This study investigated occurrences and developed predictive models for DBPs in the PP and the HWT of six houses from three municipal water systems in Quebec (Canada) in a year-round study. Trihalomethanes (THMs) in PP and HWT were observed to be 1.4-1.8 and 1.9-2.7 times the THMs in the WDS, respectively. Haloacetic acid (HAAs) in PP and HWT were observed to be variable (PP/WDS = 0.23-2.24; HWT/WDS = 0.53-2.61). Using DBPs occurrence data from these systems, three types of linear models (main factors; main factors, interactions and higher orders; logarithmic) and two types of nonlinear models (three parameters Logistic and four parameters Weibull) were investigated to predict DBPs in the PP and HWT. Significant factors affecting DBPs formation in the PP and HWT were identified through numerical and graphical techniques. The R² values of the models varied between 0.77 and 0.96, indicating excellent predictive ability for THMs and HAAs in the PP and the HWT. The models were found to be statistically significant. The models were validated using additional data. These models can be used to predict DBPs increase from WDS (water entry point of house) to the PP and HWT, and could thereby help gain a better understanding of human exposure to DBPs and their associated risks.     

Simulation and experimental study on distortion of butt and T-joints using WELD PLANNER

This paper investigates the capability of linear thermal elastic numerical analysis to predict the welding distortion that occurs due to GMAW process. Distortion is considered as the major stumbling block that can adversely affect the dimensional accuracy and thus lead to expensive corrective work. Hence, forecast of distortion is crucially needed and ought to be determined in advance in order to minimize the negative effects, improve the quality of welded parts and finally to reduce the production costs. In this study, the welding deformation was simulated by using relatively new FEM software WELD PLANNER developed by ESI Group. This novel Welding Simulation Solution was employed to predict welding distortion induced in butt and T-joints with thickness of 4 mm. Low carbon steel material was used for the simulation and experimental study. A series of experiments using fully automated welding process were conducted for verification purpose to measure the distortion. By comparing between the simulation and experimental results, it was found out that this program code offered fast solution analysis time in estimating weld induced distortion within acceptable accuracy.     

Synthesis of polypyrrole nanoparticles in natural rubber–polystyrene blend via emulsion polymerization

Nanoparticles of polypyrrole (PPy) in 40/60 wt % natural rubber (NR)–polystyrene (PS) blends were synthesized by emulsion polymerization using ferric sulfate [Fe₂ (SO₄)₃], sodium dodecyl sulfate (SDS), and n‐amyl alcohol as the oxidant, surfactant, and cosurfactant, respectively. The NR/PS/PPy blends were characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis, thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). FESEM micrographs showed that NR/PS/PPy blends were homogeneous, and PPy nanoparticles were well distributed throughout the binary matrix of NR/PS. The size of PPy particles in the blends was in the range of 26–80 nm. The electrical conductivities of the pellets prepared from NR/PS/PPy blends increased as the composition of PPy nanoparticles was increased, which were in the range of 8.9 × 10^?8 – 2.89 × 10^?4 S/cm. Thermal stability of the blends increased as the content of PPy was increased, as shown by TGA thermograms. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Adaptation and evaluation of the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) for use as an effective tool to characterize drinking source water quality

Protecting drinking source water quality is a critical step in ensuring a safe supply of drinking water. Increasingly, drinking source water protection programs rely on the active participation of various stakeholders with differing degrees of water science knowledge. A drinking source water quality index presents a potential communication and analysis tool to facilitate cooperation between diverse interest groups as well as represent composite water quality. We tested the effectiveness of the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) in capturing expert assessments of drinking water quality. In cooperation with a panel of drinking water quality experts we identified a core set of parameters to reflect common source water concerns. Drinking source water target values were drafted for use in the index corresponding to two basic treatment levels. Index scores calculated using the core parameter set and associated source water target values were strongly correlated with expert assessments of water quality. We recommend a modified index calculation procedure to accommodate parameters measured at different frequencies within any particular study period. The resulting drinking source water CCME WQI provides a valuable means of monitoring, communicating, and understanding surface source water quality.     

Weakly Nonlinear Stability Analysis of an Electro-Osmotic Thin Film Free Surface Flow

The flow of a thin incompressible fluid driven by an electro-osmotic force due to an applied electric field is analyzed. Linear stability of the film flow system is analyzed by solving the pertinent Orr-Sommerfeld eigenvalue problem. Applying long-wave theory, a nonlinear evolution equation for the local film thickness is obtained and the numerical investigation of the evolution equation in the supercritical stable region is carried to analyze the transient development of nonlinear waves incorporating various effects.     

Performance management of small water treatment plant operations: a decision support system

A decision support system (DSS) is developed to optimise the performance of different operations of small water treatment systems to improve day‐to‐day decisions. The support system includes a data management system, knowledge‐based system, performance assessment of different unit processes, fault tree analyses, preventive and corrective actions and event tree analysis (ETA). Performance assessment identifies the critical events (failures) and fault tree analysis identifies the interrelationships between the critical events and the root causes. Fault trees are developed based on the information obtained from events of waterborne outbreaks, responses to questionnaires by the participating smaller utilities, state‐of‐the‐art literature review and personal communication with the operators. ETA is used to identify the potential health outcomes which are further integrated with the quantitative microbial risk assessment. The developed DSS is advanced to an automated user friendly program that can be used by treatment plant operators to assess system performance.     

Water mains renewal planning framework for small to medium sized water utilities: a life cycle cost analysis approach

For the last few decades, concerns have repeatedly been raised about deteriorating water mains in Canada. Small to medium sized water utilities are generally impacted more due to lack of technical and financial resources. This paper presents a user-friendly life cycle cost (LCC) analysis-based decision support tool to help these utility managers to prioritize water mains rehabilitation or replacement (R/R) strategies. The deterioration curves for water mains of different materials and sizes have been developed based on their likelihood of failure. The proposed model is implemented for the water supply network of City of Kelowna (Canada). It compares the costs of various R/R scenarios for each pipe over its life cycle and suggests the most cost-effective decision to the managers to efficiently allocate their limited resources.