Flow-pressure analysis of loop gas networks

This paper proposes a mathematical model underlying a computer program for flow-pressure analysis of loop gas pipe networks. The method is used on a test case with four nodes. The HAPN application for flow-pressure analyses of low pressure gas pipe networks is completely designed in object-oriented programming technology. The equations, which describe the physical flow-pressure conditions through every cross point are assumed to be continuous and the energy of every closed loop of analyzed network conserved. The system of non-linear equations was linearized by LTM (Linear Theory Method). The algorithm for numerical module LTM and the method for solution of sparse matrix are developed at the Faculty of Chemistry and Chemical Engineering, University of Maribor, Slovenia

Comparison of the performances of absorption refrigeration cycles

This paper compares the performance of absorption refrigeration cycles that are used for refrigeration temperatures below 0°C. Since the most common vapor absorption refrigeration systems use ammonia-water solution with ammonia as the refrigerant and water as the absorbent, research has been devoted to improvement of the performance of ammonia-water absorption refrigeration systems in recent years. In this paper the performances of the ammonia-water and possible alternative cycles as ammonia-lithium nitrate, ammonia-sodium thiocyanate, monomethylamine-water, R22-DMEU, R32-DMEU, R124-DMEU, R152a-DMEU,R125-DMEU, R134a-DMEU, trifluoroethanol (TFE)-tetraethylenglycol dimethylether (TEGDME), methanol-TEGDME and R134a-DMAC are compared in respect of the coefficient of performance (COP) and circulation ratio (f). The highest COP and the lowest f, were found as a function of the generator, condenser, absorber and evaporating temperature

Integracija Roma u redovni odgojno-obrazovni sustav u Međimurskoj županiji

Pitanje odgoja i obrazovanja Roma danas je sve češća tema. U samom startu odgojno-obrazovnog procesa Romi se susreću s brojnim izazovima. Njihov materinji jezik nije hrvatski jezik te se na početku svog školovanja teško privikavaju na nastavu na hrvatskom jeziku. Ta početna barijera proteže se kroz njihovo cijelo školovanje pa je to jedan od ključnih razloga zašto Romi ne postižu jednake obrazovne ishode kao i učenici većinskog stanovništva. Romi su u svojoj prošlosti naučili kako se nositi sa svakodnevnim problemima unatoč niskom stupnju formalnog obrazovanja pa iz tog razloga Romi obrazovanje ne smatraju važnim. Temeljni cilj odgoja i obrazovanja Roma u Republici Hrvatskoj jest osiguranje jednakih šansi, nediskriminacija, desegregacija, poticanje društvene integracije Roma, uz poštivanje prava manjina i prava na jednakost. Upravo zato, provedeno je istraživanje kojim se ispitalo kakvo je obrazovanje Roma u osnovnim školama te koje mjere bi se trebale poduzeti kako bi se ono dovelo na još uspješniji nivo. Istraživanje je provedeno u Međimurskoj županiji zato što je to županija koja bilježi najveći broj romskog stanovništva u Republici Hrvatskoj. Te je to ujedno i županija koja se uključila u brojne projekte kako bi obrazovanje Roma, a samim time i njihov cjelokupni život bio što uspješniji. Istraživanje je pokazalo kako učenici Romi prema mišljenju učitelja usvajaju osnovno znanje koje je dovoljno za prolazak u sljedeći razred. Iako ne postoji posebna prilagodba na razini plana i programa, učitelji u svakodnevnom radu nastavni sadržaj trebaju prilagođavati prema mogućnostima svakog pojedinog učenika. Međusobna suradnja između učenika Roma i učenika većinskog stanovništva jest zadovoljavajuća, dok suradnja s roditeljima još uvijek nije na nivou kojem bi trebala biti. Glavne mjere koje se trebaju poduzeti jesu: uključivanje romske djece što ranije u predškolski odgoj i obrazovanje te obrazovanje odraslih Roma. Napredak u odgojno-obrazovnom području Roma je vidljiv, ali se odvija puno sporije od očekivanog.The issue of Roma education is nowadays a common topic. From the early beginning of educational process, Roma face many challenges. Their mother tongue is not a Croatian language, hence at early schooling it is difficult to accustom to early language learning. Their initial barrier extends through the entire education making it the key reason why Roma do not achieve the same educational outcomes as the majority of population. Through the past Roma have learned to cope with everyday problems, despite having low formal education which is considered as not much important. The basic goal of Roma education in the Republic of Croatia is to achieve equal opportunities, non-discrimination and disaggregation. The other point is to foster their social integration with the respect of the rights of minorities and the right to equality. Above all mentioned, the research has been conducted to examine the Roma education in elementary school with the measures taken that bring it to a more successful level. The survey was conducted in Međimurje County which records the largest number of Roma population in the Republic of Croatia. At the same time it is a county that has participated in numerous projects that make Roma education and thus their overall life as successful as possible. According to the teachers, the research has shown that Roma students adopt basic knowledge that is sufficient to pass the class. Although there is no specific adjustment considering the level of the curriculum, teachers in their everyday work implement the teaching methods adapted to the capabilities of each individual student. On one hand mutual co-operation between Roma students and majority population students is satisfactory while on the other co-operation with parents is still not at the expected level. The key measures that need to be taken include: inclusion of Roma children in early pre-school education and adults in Roma education. In the field of education, progress is noticeable, but it is much slower than expected

Verification of the mathematical model of pulverized coal combustion in swirl burners

Prikazan je matematički model sagorevanja ugljenog praha u ložištu sa vrtložnim gorionicima. Model se zasniva na dvojednačinskom k-ε simulacionom modelu jednofaznog turbulentnog strujanja, a koji uzima u obzir prisustvo čvrste faze putem PSI-Cell metode. Disperzna faza se tretira Lagranževskim stohastičko - determinističkim modelom. Prenos toplote zračenjem se tretira pomoću metode Šest flukseva. Devolatilizacija uglja, kao i homogene i heterogene reakcije su modelirane skupa koristeći model globalnog sagorevanja uz upotrebu sopstvenih podataka o kinetici reakcije. Model se verifikuje poređenjem računskih i eksperimentalnih rezultata pri sagorevanju polidisperznog ugljenog praha u dva eksperimentalna ložišta. Zaključeno je da se ovaj model može sa uspehom iskoristiti za predviđanje, optimizaciju i projektovanje vrtložnih gorionika za različite geometrijske, strujne i temperaturske granične uslove kao i ugljeve različitog kvaliteta.Mathematical model of pulverized coal combustion in furnaces with swirl burners is presented. The model is based on two equation k-ε single phase turbulent flow simulation model, considering presence of the solid phase via PSI-Cell method. Disperse phase is treated by Lagrangian Stochaistic Deterministic model. The radiation heat transfer is treated via Six-Flux method. Coal devolatilization, homogeneous and heterogeneous reactions are modeled together via global combustion model using own reaction kinetics data. Model was verified comparing computational and experimental results for combustion of polydisperse pulverized coal in two experimental furnaces. It is concluded that the model can be successfully used for prediction optimization of parameters and design of swirl burners, for different burner geometries, flow and temperature boundary conditions and coals of different rank

Torrefaction – the process for biofuels production by using different biomasses

ArticleTorrefaction process is a mild pyrolysis, where biomass material is converted into solid fuel with higher heating value. The results of torrefaction at different temperatures in a range from 220 to 400 °C for three varied materials, oak wood, mixed wood and dehydrated, granulated sewage sludge are presented. The torrefaction process started with warm up stage, which took place for 30 minutes, after that sample was torrefied for 2 hours at constant temperature. The process continued with cool down stage. The energy demands were covered by electric power, while the flue gasses were not integrated in the process. The influence of the operating temperatures are analysed in order to determine optimal operation parameters to get the torrefied biomass with highest calorific value. Furthermore, the optimal operation time according to the largest increase in calorific value for each material is evaluated. The results of calorific value, mass drop and chemical compositions such as elemental analyses are also presented. Results show that heating values increase with raising temperature for both wood samples. The heating values for sewage sludge increases to approximately 320 °C, after that temperature are unchangeable. Torrefied oak wood samples were more fragile at higher temperatures in comparison to raw or torrefied oak wood samples at lower temperatures. At torrefied sewage sludge samples the changes in fragility are not detected due to pre-prepared granulates of sludge

Integracija Roma u redovni odgojno-obrazovni sustav u Međimurskoj županiji

Pitanje odgoja i obrazovanja Roma danas je sve češća tema. U samom startu odgojno-obrazovnog procesa Romi se susreću s brojnim izazovima. Njihov materinji jezik nije hrvatski jezik te se na početku svog školovanja teško privikavaju na nastavu na hrvatskom jeziku. Ta početna barijera proteže se kroz njihovo cijelo školovanje pa je to jedan od ključnih razloga zašto Romi ne postižu jednake obrazovne ishode kao i učenici većinskog stanovništva. Romi su u svojoj prošlosti naučili kako se nositi sa svakodnevnim problemima unatoč niskom stupnju formalnog obrazovanja pa iz tog razloga Romi obrazovanje ne smatraju važnim. Temeljni cilj odgoja i obrazovanja Roma u Republici Hrvatskoj jest osiguranje jednakih šansi, nediskriminacija, desegregacija, poticanje društvene integracije Roma, uz poštivanje prava manjina i prava na jednakost. Upravo zato, provedeno je istraživanje kojim se ispitalo kakvo je obrazovanje Roma u osnovnim školama te koje mjere bi se trebale poduzeti kako bi se ono dovelo na još uspješniji nivo. Istraživanje je provedeno u Međimurskoj županiji zato što je to županija koja bilježi najveći broj romskog stanovništva u Republici Hrvatskoj. Te je to ujedno i županija koja se uključila u brojne projekte kako bi obrazovanje Roma, a samim time i njihov cjelokupni život bio što uspješniji. Istraživanje je pokazalo kako učenici Romi prema mišljenju učitelja usvajaju osnovno znanje koje je dovoljno za prolazak u sljedeći razred. Iako ne postoji posebna prilagodba na razini plana i programa, učitelji u svakodnevnom radu nastavni sadržaj trebaju prilagođavati prema mogućnostima svakog pojedinog učenika. Međusobna suradnja između učenika Roma i učenika većinskog stanovništva jest zadovoljavajuća, dok suradnja s roditeljima još uvijek nije na nivou kojem bi trebala biti. Glavne mjere koje se trebaju poduzeti jesu: uključivanje romske djece što ranije u predškolski odgoj i obrazovanje te obrazovanje odraslih Roma. Napredak u odgojno-obrazovnom području Roma je vidljiv, ali se odvija puno sporije od očekivanog.The issue of Roma education is nowadays a common topic. From the early beginning of educational process, Roma face many challenges. Their mother tongue is not a Croatian language, hence at early schooling it is difficult to accustom to early language learning. Their initial barrier extends through the entire education making it the key reason why Roma do not achieve the same educational outcomes as the majority of population. Through the past Roma have learned to cope with everyday problems, despite having low formal education which is considered as not much important. The basic goal of Roma education in the Republic of Croatia is to achieve equal opportunities, non-discrimination and disaggregation. The other point is to foster their social integration with the respect of the rights of minorities and the right to equality. Above all mentioned, the research has been conducted to examine the Roma education in elementary school with the measures taken that bring it to a more successful level. The survey was conducted in Međimurje County which records the largest number of Roma population in the Republic of Croatia. At the same time it is a county that has participated in numerous projects that make Roma education and thus their overall life as successful as possible. According to the teachers, the research has shown that Roma students adopt basic knowledge that is sufficient to pass the class. Although there is no specific adjustment considering the level of the curriculum, teachers in their everyday work implement the teaching methods adapted to the capabilities of each individual student. On one hand mutual co-operation between Roma students and majority population students is satisfactory while on the other co-operation with parents is still not at the expected level. The key measures that need to be taken include: inclusion of Roma children in early pre-school education and adults in Roma education. In the field of education, progress is noticeable, but it is much slower than expected

Integracija Roma u redovni odgojno-obrazovni sustav u Međimurskoj županiji

Pitanje odgoja i obrazovanja Roma danas je sve češća tema. U samom startu odgojno-obrazovnog procesa Romi se susreću s brojnim izazovima. Njihov materinji jezik nije hrvatski jezik te se na početku svog školovanja teško privikavaju na nastavu na hrvatskom jeziku. Ta početna barijera proteže se kroz njihovo cijelo školovanje pa je to jedan od ključnih razloga zašto Romi ne postižu jednake obrazovne ishode kao i učenici većinskog stanovništva. Romi su u svojoj prošlosti naučili kako se nositi sa svakodnevnim problemima unatoč niskom stupnju formalnog obrazovanja pa iz tog razloga Romi obrazovanje ne smatraju važnim. Temeljni cilj odgoja i obrazovanja Roma u Republici Hrvatskoj jest osiguranje jednakih šansi, nediskriminacija, desegregacija, poticanje društvene integracije Roma, uz poštivanje prava manjina i prava na jednakost. Upravo zato, provedeno je istraživanje kojim se ispitalo kakvo je obrazovanje Roma u osnovnim školama te koje mjere bi se trebale poduzeti kako bi se ono dovelo na još uspješniji nivo. Istraživanje je provedeno u Međimurskoj županiji zato što je to županija koja bilježi najveći broj romskog stanovništva u Republici Hrvatskoj. Te je to ujedno i županija koja se uključila u brojne projekte kako bi obrazovanje Roma, a samim time i njihov cjelokupni život bio što uspješniji. Istraživanje je pokazalo kako učenici Romi prema mišljenju učitelja usvajaju osnovno znanje koje je dovoljno za prolazak u sljedeći razred. Iako ne postoji posebna prilagodba na razini plana i programa, učitelji u svakodnevnom radu nastavni sadržaj trebaju prilagođavati prema mogućnostima svakog pojedinog učenika. Međusobna suradnja između učenika Roma i učenika većinskog stanovništva jest zadovoljavajuća, dok suradnja s roditeljima još uvijek nije na nivou kojem bi trebala biti. Glavne mjere koje se trebaju poduzeti jesu: uključivanje romske djece što ranije u predškolski odgoj i obrazovanje te obrazovanje odraslih Roma. Napredak u odgojno-obrazovnom području Roma je vidljiv, ali se odvija puno sporije od očekivanog.The issue of Roma education is nowadays a common topic. From the early beginning of educational process, Roma face many challenges. Their mother tongue is not a Croatian language, hence at early schooling it is difficult to accustom to early language learning. Their initial barrier extends through the entire education making it the key reason why Roma do not achieve the same educational outcomes as the majority of population. Through the past Roma have learned to cope with everyday problems, despite having low formal education which is considered as not much important. The basic goal of Roma education in the Republic of Croatia is to achieve equal opportunities, non-discrimination and disaggregation. The other point is to foster their social integration with the respect of the rights of minorities and the right to equality. Above all mentioned, the research has been conducted to examine the Roma education in elementary school with the measures taken that bring it to a more successful level. The survey was conducted in Međimurje County which records the largest number of Roma population in the Republic of Croatia. At the same time it is a county that has participated in numerous projects that make Roma education and thus their overall life as successful as possible. According to the teachers, the research has shown that Roma students adopt basic knowledge that is sufficient to pass the class. Although there is no specific adjustment considering the level of the curriculum, teachers in their everyday work implement the teaching methods adapted to the capabilities of each individual student. On one hand mutual co-operation between Roma students and majority population students is satisfactory while on the other co-operation with parents is still not at the expected level. The key measures that need to be taken include: inclusion of Roma children in early pre-school education and adults in Roma education. In the field of education, progress is noticeable, but it is much slower than expected