A novel method of harmonic assessment generated by three-phaseAC-DC converters under unbalanced supply conditions

A three-phase converter is fully analyzed, and the performance of the converter is evaluated under both balance and unbalanced supply situations. It is observed that the level of imbalance in the supply voltage increases the harmonic content of the input current and decreases the power factor of the converter. This situation worsens toward the lower output region of the converter. The nature of the analysis has been kept very general so that future related work can be incorporated     

The effect of evaporation losses in the analysis of counterflow cooling towers

In Merkel's method for the thermal design of counterflow cooling towers, the variation of the water flow from the tower inlet to outlet (due to evaporation losses) is neglected, which does not lead to a convervative design. In this analysis, the water evaporation losses are included in the energy balance and a new technique for the thermal design of cooling towers is developed. A comparison of the present analysis with the Merkel solution indicates that the error in the Merkel method may reach 12%, depending on the design conditions. The present solution is recommended where more accurate results are needed.     

CHROMATOGRAPHIC SEPARATION AND CHARACTERIZATION OF MONO-, DI- AND TRIAROMATIC HYDROCARBONS IN GAS OIL

A simple procedure is described for separation of aromatic hydrocarbons into mono-, di- and trinuclear types in Iraqi gas oil. This is accomplished by elution through an alumina adsorption column under standardized conditions. Characterization is performed by UV-absorption and ratio matching method. The method can be used also for investigating aromatic hydrocarbon structures of other petroleum fractions.     

Optimising deproteinisation methods and effect of deproteinisation on structural and functional characteristics of flaxseed gum

In the current study, deproteinisation rate (DPR) and carbohydrate loss ratio (CLR) in flaxseed gum (FSG) were compared as indexes by using four different deproteinised methods, that is sodium chloride (NaCl), trichloroacetic acid (TCA), hydrochloric acid (HCl) and calcium chloride (CaCl₂). In addition, the effect of deproteinisation on physicochemical, functional and structural characteristics (FTIR, ¹H NMR and SEM analysis) of deproteinised flaxseed gum (DFSG) was further examined. The results revealed that HCl and TCA methods had better ability of deproteinisation (97.83% and 96.21%) but resulted in higher CLR (27.66% and 24.19%), while CaCl₂ method excelled over the NaCl method in DPR (94.7% and 88.6%) and CLR (4.90% and 4.21%), respectively. Flaxseed gum showed significant functional properties even after deproteinisation and exhibited resolved resonances for both ring and anomeric protons in ¹H NMR spectra. The characteristic groups in FTIR spectra were retained after deproteinisation.     

Rice bran nutraceutics: A comprehensive review

Agro-industry yields ample quantity of several byproducts with considerable importance. These byproducts are mostly under-utilized, often used as animal feed or rejected as waste; hence their true potential is not harnessed. The use of such superfluous resources is of not only economic significance but also a form of commercial recycling. Rice bran is an important byproduct of rice milling industry with a global potential of 29.3 million tons annually. It is gaining great attention of the researchers due to its nutrient-rich composition, easy availability, low cost, high antioxidant potential, and promising effects against several metabolic ailments. Bioactive components of rice bran, mainly γ-oryzanol, have been reported to possess antioxidant, anti-inflammatory, hypocholesterolemic, anti-diabetic, and anti-cancer activities. Rice bran oil contains appreciable quantities of bioactive components and has attained the status of “Heart oil” due to its cardiac-friendly chemical profile. Nutraceutics have successfully been extracted from rice bran using several extraction techniques such as solvent extraction, supercritical fluid extraction, microwave-, and ultrasonic-assisted extraction. Current paper is an attempt to highlight bioactive moieties of rice bran along with their extraction technologies and health benefits.     

Starch gelatinization using sodium silicate: FTIR,DSC, XRPD,and NMR studies

The chemical and physical modifications of native maize starch subjected to treatment with aqueous Na silicate have been investigated. The application of FTIR, DSC, XRPD, and NMR analysis is discussed herein with respect to the interaction of Na silicate with starch in relation to gelatinization. XRPD results indicate that Na silicate, in the ionized form, disrupts the molecular structure of starch in a manner similar to thermally induced starch gelatinization. In addition, Na silicate forms new CO–O–SiO₂Na moieties with the amylopectin starch component. This was ascertained by the detection of the in‐plane vibration of the –Si–O as a distinctive FTIR band at 580–600 cm⁻¹ and the appearance of a new carboxyl group (–COOH) NMR chemical shift at 168 ppm for the amylopectin/Na silicate system. DSC analysis showed two adjacent endothermic transitions at 192 and 198°C for starch/amylopectin treated with Na silicate whereas amylose treated with Na silicate did not show any new endothermic/or exothermic transitions.     

Failure investigation on rear water wall tube of boiler

This paper presents failure investigation on the SA210-A1 rear water wall tube by visual site inspection, tube wall thickness measurements and microscopic examination. The rear water wall tube has failed with wide open burst and was situated at the boiler nose lower bent region. On-site wall thickness measurements were performed on all the rear water wall tubes located at the same level of the ruptured tube. The tubes were observed to have experienced significant wall thinning. Microscopic examinations on the failed rupture region and some distance away region of the as-received tubes are also conducted in order to support in determining the failure mechanism and failure root cause. Failure mechanisms are discussed and the findings obtained from the site inspection, wall thickness measurements, microscopic examinations and creep analyses may finally reveal the failure mechanism and main root cause of the failure. The failure mechanism is identified as a result of the combination of the significant localized wall thinning of the rear water wall tube due to fly-ash erosion and a thermally activated process of creep problem due to increasing of temperatures.