Surface Spectroscopic Studies of High-Temperature Superconductors

Applied Science

An Efficient Algorithm for Fault Location on Mixed Line-Cable Transmission Corridors

This paper presents a fault location algorithm that can be used to accurately locate the fault at any place along mixed line-cable transmission corridors. The algorithm is an impedance based line/cable parameter dependent algorithm. The fault location algorithm is derived using distributed line model, modal transformation theory and Discrete Fourier Transform. The algorithm can be used as an on-line, or off-line application in practice. The proposed solution has the ability to locate the fault whether it is on the overhead line or on the underground power cable. The paper presents the results of the initial algorithm testing through the use of ATP simulations. Some results are validated by experimental measurements.Electrical Sustainable EnergyElectrical Engineering, Mathematics and Computer Scienc

Comparative study of low-cost fluoride removal by layered double hydroxides, geopolymers, softening pellets and struvite

Excessive F- in drinking water due to natural and anthropogenic activities is a serious health hazard affecting humans worldwide. In this study, a comparative assessment was made of eight mineral-based materials with advantageous structural properties for F- uptake: layered-double-hydroxides (LDHs), geopolymers, softening pellets and struvite. These materials are considered low-cost, for being either a waste or by-product, or can be locally-sourced. It can be concluded that Ca-based materials showed the strongest affinity for F- (Ca-Al-CO3 LDHs, slag-based geopolymer, softening pellets). The Langmuir adsorption capacity of Ca-Al-CO3 LDHs, slag-based geopolymer and softening pellets was observed to be 20.83, 5.23 and 1.20 mg/g, respectively. The main mechanism of F- uptake on Ca-Al-CO3 LDHs, Mg-Al-Cl LDHs, slag-based geopolymers and softening pellets was found to be sorption at low initial F- concentrations (<10 mg/L) whereas precipitation as CaF2 is proposed to play a major role at higher initial F- concentrations (>20 mg/L). Although the softening pellets had the highest Ca-content (96-97%; XRF), their dense structure and consequent low BET surface area (2–3 m2/g), resulted in poorer performance than the Ca-based LDHs and slag-based geopolymers. Nevertheless, geopolymers, as well as struvite, were not considered to be of interest for application in water treatment, as they would need modification due to their poor stability and/or F- leaching.Sanitary EngineeringMaterials and EnvironmentWater Managemen

Chemical vapor deposition of silicon carbide on alumina ultrafiltration membranes for filtration of microemulsions

Worldwide, a considerable amount of oily wastewater is generated, with oil droplets from 2 to 200 nm that are difficult to separate because of their size and colloidal stability. This study presents a novel approach for effectively separating microemulsions via cubic silicon carbide (3C-SiC)-coated alumina (Al 2O 3) membranes fabricated based on low pressure chemical vapor deposition (LPCVD). SiC was deposited at a relatively low temperature at 860 °C on 100 nm Al 2O 3 membranes using two precursors: SiH 2Cl 2 and C 2H 2. With the increase in deposition time, up to 25 min, the pore size decreased from 41 nm to 33 nm, which is a smaller pore size of a SiC membrane than previously used for oil/water separation. The polycrystalline 3C-SiC-coated membranes showed improved hydrophilicity (water contact angle of 15°) and highly negatively charged surfaces (−65 mV). Microemulsion filtration experiments were carried out at a constant permeate flux (80 Lm −2 h −1) for six cycles with varying deposition time, pH, surfactant types, and pore sizes. The fouling of the SiC-coated membrane was, compared to the Al 2O 3 membrane, effectively mitigated due to the enhanced electrostatic repulsion and hydrophilicity. Surfactant adsorption mainly occurred when the surface charge of the microemulsion and the membranes were opposite. Therefore, the surface charge of the alumina membrane changed from positive to negative when soaked in negatively charged microemulsions, whereas SiC-coated membranes remained negatively charged regardless of surfactant type. The membrane fouling was alleviated when the membrane and oil droplets had the same charge. Lastly, the 62 nm SiC-coated membrane with 20 min coating time was the best choice for the filtration of the microemulsion, because of the high rejection of the oil droplets and low fouling tendency.Sanitary EngineeringComplex Fluid Processin