Power electronics solution to dust emissions from thermal power plants

Thermal power stations emit significant amounts of fly ash and ultra fine particles into the atmosphere. Electrostatic precipitators (ESP) or electro filters remove flying ashes and fine particles from the flue gas before passing the gas into the chimney. Maximum allowable value of dust is 50 mg/m3 and it requires that the efficiency of the ESPs better than 99 %, which calls for an increase of active surface of the electrodes, hence increasing the filter volume and the weight of steel used for the filter. In previous decades, electrostatic precipitators in thermal power plants were fed by thyristor controlled, single phase fed devices having a high degree of reliability, but with a relatively low collection efficiency, hence requiring large effective surface of the collection plates and a large weight of steel construction in order to achieve the prescribed emission limits. Collection efficiency and energy efficiency of the electrostatic precipitator can be increased by applying high frequency high voltage power supply (HF HV). Electrical engineering faculty of the University of Belgrade (ETF) has developed technology and HF HV equipment for the ESP power supply. This solution was subjected to extensive experimental investigation at TE Morava from 2008 to 2010. High frequency power supply is proven to reduce emission two times in controlled conditions while increasing energy efficiency of the precipitator, compared to the conventional thyristor controlled 50Hz supply. Two high frequency high voltage unit AR70/1000 with parameters 70 kV and 1000 mA are installed at TE Morava and thoroughly testes. It was found that the HF HV power supply of the ESP at TE Morava increases collection efficiency so that emission of fine particles and flying ashes are halved, brought down to only 50 % of the emissions encountered with conventional 50 Hz thyristor driven power supplies. On the basis of this study, conclusion is drawn that the equipment comprising HF HV supplies are the best solution for new ESP installations, as well as for the reconstruction of existing facilities. The paper describes the topology of the HF HV power supply, power management and controls, and brings the most important details of the implementation. It is found that the HF HV solution achieves several significant improvements over the conventional thyristor system. It is possible to provide more precise control of the ESP parameters such as the output voltages and currents. It is also possible to make a rapid increase or decrease in voltage and to effectuate a very fast response to load changes. Due to this advantages it is possible to suppress the supply quickly in the case of sparking, reducing the spark energy and the quantity of ionized gasses produced by the electric arc. Reduction in the spark energy is up to 10 times compared to conventional thyristors solution. This means that the erosion of the electrode system is significantly reduced, and that the quality of the collection plates is preserved for much longer periods. At the same time, lower quantity of ionized gasses produced by the spark contribute to much shorter deionization intervals, required to quit sparking and evacuate charged particles in order to reinstate the voltage and proceed with the operation. In addition, HF HV power supply provides a significant reduction in size and weight of the complete ESP installation, hence reducing the tons of steel that has to be built in. Therefore, the HF HV power supply may be the key instrument to reducing the cost of the dedusting ecological equipment. Besides, size and weight reduction leads to cost savings of installation and maintenance. According to estimates, savings in steel may reach 30%, contributing to the overall cost savings of roughly 20%. Within this paper, in addition to describing the AR70/1000 unit topology and principles of operation, the paper presents the results and measurements obtained during extensive experimental investigations wherein performances of 50 Hz based thyristor units with T/R sets are compared to HF HV power supply

The effects of nitrogen nutrition and glutenin composition on the gluten quality in wheat genotypes

The effect of nitrogen nutrition treatments on the gluten content and some quality parameters of eight winter wheat cultivars has been studied. Six different nitrogen rates were applied (0, 60, 90, 120, 150 and 180 kg N ha-1) to wheat cultivars chosen according to the structure of their high molecular weight glutenin subunits (HMW-GS) at the Glu-D1 locus. Four genotypes with HMW-GS 2 + 12 and another four with HMW-GS 5 + 10 were used in the study. The analysis of gluten quality involved the wet gluten content and rheological properties determined by the sensory and instrumental methods (“Instron 4301”). It was determined that in all the cultivars the wet gluten content increased significantly (P < 0.05) in parallel with N rate increase. The cultivars reacted differently regarding their wet gluten rheological properties. Libellula, a cultivar with poor bread making quality (HMW-GS 2 + 12), did not react to different N rates. Sremica, a cultivar with excellent bread making quality (HMW-GS 5 + 10), reduced its gluten quality as the N rate increased. The values obtained by the instrumental method “Instron 4301” at 90% wet gluten compression varied widely (from 0.002 to 0.041 kN). The increase of N fertilizer rate was significantly positively correlated (r2 = 0.811) with the wet gluten content and strength in the cultivars with HMW-GS 5+10

Types of geochemical associations in the Borov Dol - Shopur area interpretation of the data of primary and secondary haloes

The paper presents statistical calculations of the results of geochemical investigations of the primary and secondary dispersion haloes carried out on an area of some 40 km^2 in the Borov Dol - Shopur region (the Buchim ore district). Sampling was carried out on 500 x 200 spacing by research workers from IMGRE Moscow and the Buchim mine. The results obtained were first interpreted by the Geoscan method and the cluster analysis method (discussed in this paper), as well as the factor analysis of Kaiser method. Based on complex statistical calculations, correlation dependencies and classification of individual elements according to variogramas, factor distributions and dendograms, the types and geochemical associations distinguished are grouped us tollows: 1. Based on cluster analysis the following were distinguished: a) according to primary dispersion haloes (Pb, Zn, Sn). [(Ga, Ag) Vb]. (Ni, Co, Cr), [(Ti, Zr, Y) Nb]; b) according to secondary dispersion haloes [(Ni, Cr, Co) Mn]; [(Ti, V) Sc]; [(Vb, Nb) Ag]; (W, Ga); (Cu, Y) Mo; (Pb, Zn, Sn); 2. Based on data of factor analysis the following were distinguished: a) according to primary haloes [(Zr, Y. B, Ti) Nb]; (Sr); (Pb, Zn, Sn); (Ga, Ag, Vb); (B, Mn, Ni) Co, Cr b) according to secondary haloes: [(Ni, Cr. Co) Mn]; [(Vb, W, Nb) Ag, Ga)J; [(Ti, V) Sc)]; (Pb, Zn, Sn); (Cu, Y, Mo). Particular mention should be made of the (Pb, Zn, Sn) geochemical association which is clearly defined in both groups as well as (Cu, Y, Mo) as n characteristic association for the secondary dispersion haloes

Uticaj azotne ishrane i gluteninske strukture na kvalitet glutena pšenice

The effect of nitrogen nutrition treatments on the gluten content and some quality parameters of eight winter wheat cultivars has been studied. Six different nitrogen rates were applied (0, 60, 90, 120, 150 and 180 kg N ha-1) to wheat cultivars chosen according to the structure of their high molecular weight glutenin subunits (HMW-GS) at the Glu-D1 locus. Four genotypes with HMW-GS 2 + 12 and another four with HMW-GS 5 + 10 were used in the study. The analysis of gluten quality involved the wet gluten content and rheological properties determined by the sensory and instrumental methods ('Instron 4301'). It was determined that in all the cultivars the wet gluten content increased significantly (P lt 0.05) in parallel with N rate increase. The cultivars reacted differently regarding their wet gluten rheological properties. Libellula, a cultivar with poor bread making quality (HMW-GS 2 + 12), did not react to different N rates. Sremica, a cultivar with excellent bread making quality (HMW-GS 5 + 10), reduced its gluten quality as the N rate increased. The values obtained by the instrumental method 'Instron 4301' at 90% wet gluten compression varied widely (from 0.002 to 0.041 kN). The increase of N fertilizer rate was significantly positively correlated (r2 = 0.811) with the wet gluten content and strength in the cultivars with HMW-GS 5+10.Ispitivan je uticaj azotne ishrane na sadržaj i kvalitativna svojstva glutena osam sorti ozime pšenice. Primenjene doze azota su bile: 0, 60, 90, 120, 150 i 180 kg N ha-1. Sorte su odabrane u skladu sa strukturom njihovih visokomolekularnih gluteninskih subjedinica (HMW-GS) na Glu-D1 lokusu. Odabrane su četiri sorte sa HMW-GS 2+12 i četiri sorte sa HMW-GS 5+10. Analize su obuhvatale sadržaj i reološka svojstva glutena određena senzornom i instrumntalnom ('Instron 4301') metodom. Utvrđeno je da se paralelno, sa povećavanjem nivoa N-ishrane značajno (P lt 0.05), povećavao i sadržaj vlažnog glutena kod svih sorti. Sorte su različito reagovale u pogledu njihovih reoloških svojastava. Sorta Libelula, sa slabim pekarskim kvalitetom i strukturom (HMW-GS 2+12), nije reagovala na različite doze azota. Kod sorte Sremica, odličnog pekarskog kvaliteta i strukturom (HMW-GS 5+10), sa povećavanjem doza azota pogoršana su reoloških svojstava glutena. Rezultati dobijeni instrumentalnom 'Instron 4301' metodom, pri (90%) kompresiji vlažnog glutena varirali su od (0,002 do 0,041 kN). Povećavanje primenjenih doza azota bilo je u značajnoj pozitivnoj korelaciji (r2 = 0.811) sa sadržajem i jačinom glutena kod sorti sa HMW-GS 5+10 strukturom

A Novel Approach of Determining the Risks for the Development of Hyperinsulinemia in the Children and Adolescent Population Using Radial Basis Function and Support Vector Machine Learning Algorithm

Hyperinsulinemia is a condition with extremely high levels of insulin in the blood. Various factors can lead to hyperinsulinemia in children and adolescents. Puberty is a period of significant change in children and adolescents. They do not have to have explicit symptoms for prediabetes, and certain health indicators may indicate a risk of developing this problem. The scientific study is designed as a cross-sectional study. In total, 674 children and adolescents of school age from 12 to 17 years old participated in the research. They received a recommendation from a pediatrician to do an OGTT (Oral Glucose Tolerance test) with insulinemia at a regular systematic examination. In addition to factor analysis, the study of the influence of individual factors was tested using RBF (Radial Basis Function) and SVM (Support Vector Machine) algorithm. The obtained results indicated statistically significant differences in the values of the monitored variables between the experimental and control groups. The obtained results showed that the number of adolescents at risk is increasing, and, in the presented research, it was 17.4%. Factor analysis and verification of the SVM algorithm changed the percentage of each risk factor. In addition, unlike previous research, three groups of children and adolescents at low, medium, and high risk were identified. The degree of risk can be of great diagnostic value for adopting corrective measures to prevent this problem and developing potential complications, primarily type 2 diabetes mellitus, cardiovascular disease, and other mass non-communicable diseases. The SVM algorithm is expected to determine the most accurate and reliable influence of risk factors. Using factor analysis and verification using the SVM algorithm, they significantly indicate an accurate, precise, and timely identification of children and adolescents at risk of hyperinsulinemia, which is of great importance for improving their health potential, and the health of society as a whole

Observations of transits of the southern exoplanets WASP 4b and WASP 46b by using a 40 cm telescope

Abstract. We present photometric observations of transits of the southern exoplanets WASP 4b and WASP 46b using a 40 cm telescope. The obtained values of the orbital inclination, relative stellar radius and relative planet radius are well within the ranges of the previous solutions of the targets. The only exception is the bigger planet radius of WASP 4b that was necessary to reproduce the deeper transit observed by the TriG filter. Our data have a good time resolution and may be used for refinement of the ephemerides of WASP 4b and WASP 46b. The presented results confirmed that small telescopes can be used successfully for the study of exoplanets orbiting stars brighter than 13 mag