NUMERICAL ANALYSIS OF TUBULAR INDUCTION MOTOR WITH COMPOSITE ROTOR

ABSTRACT

A numerical solution is presented for the fields and forces in tubular induction motor having a rotor consisting of alternate rings of copper and steel mounted on a solid steel core when excited by a sinusoidally distributed current sheet. The edge effect due to the finite length of the current sheet and the inhomogeneity in the rotor material are taken into consideration.

The numerical solution of the field problem is obtained using the finite difference technique. The field equations are formulated in terms of the magnetic vector potential. The corresponding difference equations are derived for the different media, different surface boundaries and the different corner nodes.

The magnetic vector potential distribution, the flux density distribution and the generated force for different values of copper to steel ratio in the rotor are computed. The computed results are compared with the experimental results published by the authors [ 4 ].     

HIGH-TEMPERATURE DRYING-CUM-PARBOILING OF PADDY

Alternate methods of parboiling of paddy, in place of conventional steam-parboiling, for obtaining improved hydration ability in the parboiled rice were explored. Ratnachudi variety, a medium-grained, tall indica, high-amylose rice, was used. The paddy was soaked in warm water to a saturation moisture level (ca 30%, w.b.). The soaked paddy was dried by either exposing it to very hot air (150°—200°C) or by roasting it in hot sand (250°—300°C) for a few minutes. It was observed that under appropriate high-temperature conditions paddy got simultaneously dried and parboiled by both the above treatments. Parboiled rice so produced was examined for appearance (translucence, color), milling breakage, alkali degradation pattern and starch retrogradation. It was found to be quite comparable to normal steam-parboiled rice in all respects, except that it showed the desirable property of improved hydration ability due to lowering of starch retrogradation. Possible development of the technique into commercial process is indicated.     

Physicochemical characteristics and renneting properties of camels' milk: A comparison with goats', ewes' and cows' milks

A great variability in physicochemical and microscopic characteristics of individual milk has been observed leading to the presence of differences in kinetics of the renneting reaction and in drainage ability. Furthermore, this study shows that casein concentration, total calcium content and mean diameter of casein micelles are the principal variables explaining the major part of the variation in the renneting properties. Finally, several relationships between coagulation characteristics, drainage ability and some compositional parameters of these kinds of milk were highlighted.     

TOCOPHEROLS AND PHOSPHOLIPIDS ENHANCE THE OXIDATIVE STABILITY OF BORAGE AND EVENING PRIMROSE TRIACYLGLYCEROLS

The effect of individual phospholipids and tocopherols as well as their combinations on the oxidative stability of borage and evening primrose triacylglycerols (TAG) was investigated. Based on conjugated dienes (CD) and 2-thiobarbituric acid reactive substances (TBARS) formed in borage and evening primrose TAG, the antioxidant effectiveness of phosphatidylcholine (PC), was higher than that of phosphotidylethanolamine (PE) in borage TAG while the reverse was observed for evening primrose TAG. Meanwhile, a synergistic effect between tocopherols and phospholipids in both borage and evening primrose TAG was noted. The most effective combination in borage TAG was that of PC and α-tocopherol, while PE with α-tocopherol exerted the best effects in evening primrose TAG. Therefore, the antioxidant effectiveness of phospholipids may vary depending on their fatty acid composition, nature of the functional groups and the chemical composition of the lipid system in which they are examined. The results also demonstrate the importance of minor components of vegetable oils on their oxidative stability.     

EFFECTS OF CETYLPYRIDINIUM CHLORIDE, LACTIC ACID AND SODIUM BENZOATE ON POPULATIONS OF LISTERIA MONOCYTOGENES AND STAPHYLOCOCCUS AUREUS ON BEEF

The effects of cetylpyridinium chloride (CPC), lactic acid (LA) and sodium benzoate (SB) on the Listeria monocytogenes and Staphylococcus aureus populations on beef were evaluated. Samples of longissimus dorsi beef muscle inoculated with L. monocytogenes and S. aureus were dipped into 0.5, 2.0 and 0.3% of CPC, LA and SB, respectively, or an equal mix of any two solutions for 15 s at 35C ± 1. CPC demonstrated 1.93 and 2.15 log reductions of L. monocytogenes and S. aureus, respectively, on the fifth day of refrigerated storage, whereas LA reduced L. monocytogenes and S. aureus by 1.72 and 0.99 log, respectively. Results indicated that the single intervention of CPC and LA solutions were more effective than mixed solutions of these decontaminants to reduce the pathogens of concern on beef.     

SUPERCRITICAL CARBON DIOXIDE TREATMENT TO INACTIVATE AEROBIC MICROORGANISMS ON ALFALFA SEEDS

The supercritical carbon dioxide (SC-CO₂) process involves pressurizing CO₂ in a chamber which generates liquid phase of carbon dioxide. Pressurized liquid CO₂ has a strong extraction capability of organic and inorganic compounds. The recent studies have also demonstrated that antimicrobial effect of SC-CO₂ due extraction some cellular components of microorganisms. The efficacy of a supercritical carbon dioxide treatment on alfalfa seeds contaminated with Escherichia coli K12 was tested at 2000, 3000, and 4000 psi at 50C. Samples were treated for 15, 30, and 60 min at each pressure. After pummeling the seed samples in 0.1% peptone water, the initial and final Escherichia coli and total aerobic bacteria on the seeds were determined by plating on 3M Petri Films. After 48 h of incubation at 37 C, the colonies were enumerated. Treated seeds were evaluated in terms of germination characteristics. For aerobic plate count, the effect of pressure in the range of 2000–4000 psi was not statistically significant (p > 0.05) even though 85.6% inactivation was achieved at 4000 psi for 60 min. For E. coli, the reductions for 2000, 3000, and 4000 psi treatments for 15 min were 26.6, 68.1, and 81.3%, respectively. As the time was increased from 15 to 60 min at 4000 psi, the percent E. coli reduction increased from 81.3% to 92.8%. The percent germination for all treatments was over 90%. There was no significant difference (p > 0.05) in the germination rate of treated and untreated seeds. Supercritical carbon dioxide treatments demonstrated a reduction of E. coli K12 and total aerobic counts without affecting the germination characteristics of alfalfa seeds (p < 0.05). This study was a step in the direction of improving safety of alfalfa seeds used to produce fresh sprouts, which have been the cause of several outbreaks.     

ANTIOXIDANT ACTIVITY OF BENE HULL OIL COMPARED WITH SESAME AND RICE BRAN OILS DURING THE FRYING PROCESS OF SUNFLOWER OIL

The antioxidant activity of Bene hull oil (BHO) was compared with that of sesame oil (SEO) and rice bran oil (RBO) during the frying process of sunflower oil (SFO) at 180C. The ratio between the polyunsaturated and saturated fatty acids and calculated oxidizability were statistically greater for the SFO (4.26 and 6.48, respectively), followed by the SEO (3.18 and 6.27, respectively), RBO (1.53 and 4.37, respectively) and BHO (0.37 and 1.67, respectively). Peroxide and acid values of the oils studied ranged from 0.34 to 3.07 mEq/kg and from 0.19 to 5.20 mg/g, respectively. Total tocopherols and phenolics contents of the SEO (1093.28 and 1042.43 mg/kg, respectively) were significantly higher than those of the SFO (740.27 and 38.68 mg/kg, respectively), BHO (573.41 and 276.67 mg/kg, respectively), and RBO (832.98 and 67.98 mg/kg, respectively). In total, based on the conjugated diene value and carbonyl value measurements during the frying process, the BHO showed an antioxidant activity higher than those of the SEO and RBO at the level of 2%, and the levels higher than 2% of the antioxidative oils caused to decrease the oxidative stability of the SFO, indicating the pro-oxidant effect of the oils added at these levels.

PRACTICAL APPLICATIONS

This research introduces the oil obtained from the hull of Bene, a species of pistachio growing wild in Iran, as a new source of vegetable oil for human nutrition with antioxidant activity significantly higher than sesame and rice bran oils, which are considered as very stable and antioxidative vegetable oils because of the presence of very strong indigenous antioxidants, during the frying process.     

基于机器学习的维吾尔文文本分类研究

随着Internet上维吾尔文信息的迅速发展,维吾尔文文本分类成为处理和组织这些大量文本数据的关键技术。研究维吾尔文文本分类相关技术和方法,针对维吾尔文文本在向量空间模型（VSM）表示下的高维性,采用词干提取和IG相结合的方法对表示空间进行降维。采用基于机器学习的分类算法（kNN和Na?ve Bayes）对维吾尔文文本语料进行了分类实验并分析了实验结果。     

Fatigue crack growth in fibre metal laminates under selective variable-amplitude loading

To extend the predictive capability of existing crack growth models for fibre metal laminates under constant amplitude fatigue loading to variable-amplitude loading, further research on variable-amplitude fatigue mechanisms in fibre metal laminates is necessary. In response to this need, an experimental study into the effects of multiple overloads, underloads and various block-loading sequences on crack growth in the fibre metal laminate Glare was investigated. Crack growth retardation effects were observed in the tests; however, the magnitude of these effects was lower than seen in monolithic aluminium because of fibre bridging. As a result, predictions of the observed behaviour were attempted using an existing constant-amplitude fatigue crack growth model for Glare in combination with a linear damage accumulation law.