Permeability of silicone polymers to ammonia and hydrogen sulfide

Permeability coefficients, P?, for NH₃ AND H₂S in 11 different types of silicone membranes were measured in the temperature range from 10.0 to 55.0°C and at pressures up to 115 psig (～ 7.8 atm). The values of P? for NH₃ and H₂S in different silicone polymers decrease considerably as the bulkiness of the functional groups in the side and backbone chains of these polymers increases. the substitution of Si? O bonds with stifer Si? C bonds in the backbone chains also results in a considerable decrease in gas permeability. the values of P? for NH₃ and H₂S increse exponentially with incresing δp, the pressure difference across the membrancs. The temperature dependence of NH₃ and H₂S varies greatly: P? can increase, decrease, or pass through a minimum with increasing temperature, depending on the nature of the silicone polymer. The temperature dependence of P? is also affected in some cases by Δp. The permeability behavior of silicone polymers to NH₃ and H₂S is compared with that to other penetrant gases, and the factors which might affect this behavior are discussed.     

Fault section estimation in power system using Hebb’s rule and continuous genetic algorithm

In this paper a new approach for fault section estimation (FSE) in electrical power system is presented. We propose a procedure to obtain objective function (required for fault section estimation) using the Hebb’s learning rule. The continuous genetic algorithm (CGA) optimization method is then employed to estimate the fault section making use of the objective function. The Hebb’s learning law used in this paper gives, linear algebraic equations, to represent the targets in terms of the status of relays and circuit breakers (CBs). This gives a simple objective function, which leads to reduction in time required by the CGA to identify fault section. The CGA gives an advantage of requiring less storage than binary genetic algorithm (GA). Also the CGA is inherently faster than binary GA.The proposed approach is tested on various systems, and is found to give correct results in all cases. Simulation results for two illustrations have been presented in this paper. The results show that the proposed approach can find the solution efficiently even in case of multiple faults or in case of failure of relays/circuit breakers. A comparison with artificial neural network (ANN) approach is also presented.     

Coupled circuit–field formulation for analysis of parallel operation of converters with interphase transformer

This paper deals with the coupled circuit–field analysis of an interphase transformer (IPT) required for two three-pulse controlled converters operating in parallel for the typical low voltage high current electrolysis application. Two-dimensional nonlinear transient finite element (FE) model of the IPT is coupled with external power electronic circuit comprised of switching thyristors. Output current is maintained constant at 6000 A by implementing current feedback control system. The resulting system of transient nonlinear equations is solved by backward Euler and Newton–Raphson methods, and analyzed under balanced, unbalanced and short circuit conditions. The results obtained from short circuit condition are verified with experimental results and design values, making them helpful for design purpose.     

Probing Site Symmetry Around Eu3+ in Nanocrystalline ThO2 Using Time Resolved Emission Spectroscopy

ThO₂:Eu³⁺ nanoparticles were synthesized at 300°C by combustion route using urea as a fuel and characterized by thermogravimetric/differential thermal analysis, X‐ray diffraction, transmission electron microscopy, and photoluminescence techniques. To investigate the effect of annealing temperature, as synthesized powder were heated further at 500°C, 700°C, and 900°C. It was observed that extent of asymmetry around Eu³⁺ at 700°C/900°C is very high as compared to as‐prepared or 500°C annealed sample. Based on the time resolved emission spectroscopic investigations, it was inferred that two different types of Eu³⁺ ions were present in the ThO₂ nanoparticles. In ThO₂ structure, Eu³⁺ ions occupy two sites; cubic (O_h) and noncubic (<C_2v) as can be confirmed from our emission studies. Short‐lived species T₁ (~1.3–3.4 ms) predominates at higher annealing temperature arises because of Eu³⁺ ions occupying noncubic (<C_2v) sites without inversion symmetry, whereas long‐lived species T₂ (~4.6–6.6 ms) can be ascribed to Eu³⁺ ions occupying cubic sites (O_h) with inversion symmetry.     

Use of Iodized Salt in Processed Foods in Select Countries Around the World and the Role of Food Processors

Executive Summary: The Micronutrient Initiative (MI) issued the Institute of Food Technologists (IFT) a project to assess the extent to which iodized salt is used in processed foods, as well as food processors’ level of knowledge on iodine nutrition. Iodine is an essential micronutrient required by the body that is found in a limited number of foods, thus many individuals require additional sources of iodine to meet their daily requirement. Without these additional sources, a range of disorders referred to as iodine deficiency disorders (IDD), including mental impairment, may become present, with over 2 billion people worldwide at risk due to insufficient iodine nutrition. IDD is especially damaging during the early stages of pregnancy and in early childhood. In their most severe form, IDD includes cretinism, stillbirth, and miscarriage, and increased infant mortality. Since 1994 the World Health Organization (WHO) and the United Nations Children's Fund (UNICEF) have recommended universal salt iodization (USI) as a safe, cost‐effective, and sustainable strategy to ensure sufficient intake of iodine by all individuals. However, USI has in practice tended to focus only on table salt and not all salt destined for human consumption. Recent trends, particularly in industrialized countries, show that individuals are consuming the majority of their salt through processed foods, in which iodized salt is generally not used, rather than through iodized table salt. Additionally, recent initiatives to encourage reduced sodium consumption have prompted many consumers to reduce their intake of iodized table salt. While these trends in sodium consumption are more frequently observed in industrialized countries, they are expanding into many developing countries where iodine deficiency is also a concern. Thus countries which focus on iodization of table salt alone may not achieve optimal iodine nutrition of their population. This report provides an overview of the 2 Phases of this project. Phase I was to conduct an environmental scan/desk review of processed food consumption patterns in 39 countries selected by MI (see Table 1 ). Phase II was to conduct an electronic survey of food processors and detailed telephone interviews with a small sample of select company representatives from 16 countries (see Table 2 ). Per the scope of work, IFT conducted a desk review to determine the types and level of processed food consumption in the 39 countries of interest, as well as to identify suppliers of the major processed foods consumed and the use of salt as an ingredient in those products. Whenever possible, IFT also gathered information on the sodium content of widely consumed processed foods and the sources of salt currently used in these products; the types of processed foods and extent to which they are consumed by different socioeconomic groups; if iodized salt was used in processed foods; and whether or not there are policies in place to influence dietary salt reduction and how these efforts are implemented. For Phase II, IFT reached out to food company representatives to determine their use of iodized salt in processed food products; their sources of salt; their awareness of iodine nutrition and salt as a fortification vehicle; and their interest in learning more about salt iodization. For the purposes of this project, processed foods are considered to be all food products that have undergone a change of character or been altered from their original form.

Table 1–. Preselected countries (from MI) for Phase I of the iodized salt in processed foods project.

Correlation between the structural and electrical transport properties of SnO2 films

Transparent and conducting thin films of tin oxide have been deposited by spray pyrolysis on Corning 7059 substrates. The films were investigated by X-ray diffraction and Seebeck measurements to study the structural and electrical transport properties. The films were polycrystalline and the oxide phase observed was SnO₂ in cassiterite structure. The films were preferentially oriented along [200]. Trap densities along [310] and [101] have been calculated for the first time. Assigning the traps mainly to the grain boundaries, the grain-boundary barrier height was calculated and compared with that obtained from the Seebeck measurements. A good agreement between these values was observed. The agreement was the best for films deposited under optimum deposition conditions.