Application of different turbulence models for improving construction of small-scale boiler fired by solid fuel

Due to the rapid progress in computer hardware and software, CFD became a powerful and effective tool for implementation turbulence modeling in defined combustion mathematical models in the complex boiler geometries. In this paper the commercial CFD package, ANSYS FLUENT was used to model fluid flow through the boiler, in order to define velocity field and predict pressure drop. Mathematical modeling was carried out with application of Standard, RNG, and Realizable k-epsilon turbulence model using the constants presented in literature. Three boilers geometry were examined with application of three different turbulence models with variants, which means consideration of 7 turbulence model arrangements in FLUENT. The obtained model results are presented and compared with data collected from experimental tests. All experimental tests were performed according to procedures defined in the standard SRPS EN 303-5 and obtained results are presented in this paper for all three examined geometries. This approach was used for improving construction of boiler fired by solid fuel with heat output up to 35 kW and for selection of the most convenient construction

Spektrofotometrijsko određivanje tioktinske kiseline u vodi i farmaceutskim preparatima

A spectrophotometric method is described for the assay of thioctic acid. The method is based on the reaction between the drug and palladium(II) chloride. In this reaction, a yellow-colored, water soluble product with a 1:1 stoichiometric ratio and an absorption maximum at 365 nm was formed. The stability of the formed complex depends on various factors (pH, reaction time, concentration of reagents, ionic strength). Based on these findings, a new method is suggested for the spectrophotometric determination of thioctic acid in pharmaceutical formulations. This method is simple, sensitive and reproducible.Opisana je jednostavna spektrofotometrijska metoda za brzo i tačno određivanje tioktinske kiseline u vodi, injekcionim rastvorima i tabletama. Spektrofotometrijska merenja su izvođena u Britton-Robinson-ovim puferima pri različitim pH vrednostima (2,00-6,00) i konstantnoj jonskoj sili. Sastav, konstanta stabilnosti, molarna apsorptivnost kompleksa su određene različitim metodama. Utvrđen je 1:1 sastav nagrađenog kompleksa i molarna apsorptivnost 4.2x103 l mol-1 cm-1. Relativna standardna devijacija iznosi od 3,10 do 3,76%,{to odgovara propisanim analitičkim standardima

Apolipoprotein B gene polymorphisms in patients from Serbia with ischemic cerebrovascular disease

The plasma concentration of apoB has recently been reported to be the best lipid predictor of coronary heart disease. The possible associations of genetic markers in the apolipoprotein B gene (XbaI, EcoRI, MspI, Ins/Del, and 4311 A/G polymorphisms) were evaluated in patients with ischemic cerebrovascular disease (ICVD) and controls of equivalent BMI. The odds ratio for ICVD in the X+X+ genotype was 2.22, 95% CI 1.24-3.96 (P<0.05), while that for ICVD in the Ins/Ins genotype was 2.82, 95% CI 1.57-5.06 (P<0.05). The patients had significantly higher frequency of the 4311A allele compared to the controls (P<0.01). Our results support the assumption that apoB gene polymorphisms may contribute to the extent of cerebrovascular disease risk

Načini korišćenja poljoprivrednog zemljišta brdsko-planinskog područja jugozapadne Srbije

In order to raise primary agricultural production to an economically viable level, the Republic of Serbia adopted the number of documents, strategies and laws regulating important issues related to agriculture and rural areas. This documentation would create conditions for achieving the economic, ecological and social goals of sustainable development adopted by the United Nations for the period 2015–2030. When it comes to the development of rural areas of Serbia, the main goals would be to: 1/ stop the migration of the rural population by creating the prerequisites for the modernization of primary agricultural production to increase the production of health-safe and functional food in areas where sustainable and organic agriculture can be organized 2/ production of health-safe and functional organic food. The holders of these projects, with the help of scientists from the Faculty of Agriculture in Zemun, increased the volume of primary plant and animal production on surfaces that were neglected for many years and covered with perennial weeds.Da bi podigli primarnu poljoprivrednu proizvodnju na ekonomski isplativ nivo u Republici Srbiji je usvojen značajan broj dokumenata, strategija i zakona kojima se regulišu značajna pitanja vezana za poljoprivredu i ruralna područja. Ovom dokumentacijom stvorili bi se uslovi za ostvarivanje ekonomskih, ekoloških i socijalnih ciljeva održivog razvoja usvojine od Ujedinjenih nacija za period 2015–2030. Kada je u pitanju razvijanje ruralnih područja u Srbiji, osnovni ciljevi bili bi: kako da se zaustavi migracija seoskog stanovništva stvaranjem preduslova da se osavremenjavanjem primarne poljoprivredne proizvodnje, povećanjem zdravstveno bezbedne i funkcionalne hrane u predelima gde se može organizovati održiva i organska poljoprivreda, i proizvoditi organska zdravstveno bezbedna hrana. Nosioci ovih projekata, uz pomoć naučnih radnika Poljoprivrednog fakulteta u Zemunu, povećali su obim primarne biljne i stočarske proizvodnje na površinama koje su bile duži niz godina zapuštene i obrasle višegodišnjim korovima

Land use regimes of agricultural soils in mountainous areas of southwest Serbia

In order to raise primary agricultural production to an economically viable level, the Republic of Serbia adopted the number of documents, strategies and laws regulating important issues related to agriculture and rural areas. This documentation would create conditions for achieving the economic, ecological and social goals of sustainable development adopted by the United Nations for the period 2015–2030. When it comes to the development of rural areas of Serbia, the main goals would be to: 1/ stop the migration of the rural population by creating the prerequisites for the modernization of primary agricultural production to increase the production of health-safe and functional food in areas where sustainable and organic agriculture can be organized 2/ production of health-safe and functional organic food. The holders of these projects, with the help of scientists from the Faculty of Agriculture in Zemun, increased the volume of primary plant and animal production on surfaces that were neglicted for many years and covered with perennial weeds

Application of different turbulence models for improving construction of small-scale boiler fired by solid fuel

Due to the rapid progress in computer hardware and software, CFD became a powerful and effective tool for implementation turbulence modeling in defined combustion mathematical models in the complex boiler geometries. In this paper the commercial CFD package, ANSYS FLUENT was used to model fluid flow through the boiler, in order to define velocity field and predict pressure drop. Mathematical modeling was carried out with application of Standard, RNG, and Realizable k-ε turbulence model using the constants presented in literature. Three boilers geometry were examined with application of three different turbulence models with variants, which means consideration of 7 turbulence model arrangements in FLUENT. The obtained model results are presented and compared with data collected from experimental tests. All experimental tests were performed according to procedures defined in the standard SRPS EN 303-5 and obtained results are presented in this paper for all three examined geometries. This approach was used for improving construction of boiler fired by solid fuel with heat output up to 35 kW and for selection of the most convenient construction

Paroxysmal hemicrania: A case report

Paroxysmal hemicrania (PH) is one of the trigeminai autonomie cephalgias (TACs), a group of primary headache disorders characterized by unilateral trigeminal distribution pain that occurs in association with prominent ipsilateral cranial autonomy features. The TACs are relatively rare, which is likely to be why they are poorly recognized in primary care. TACs will thus be referred to neurologists eventually, offering an excellent opportunity to diagnose and treat these patients. PH responds in a dramatic and absolute fashion to indomethacin. The importance of recognizing these syndromes is underscored by their excellent but highly selective response to treatment. This is the case report of our patient with PH and the review of current knowledge about pathophysiology of TACs, as well as differential diagnosis of other entities from this headache group