Članak je usmjeren na procjenu mogućnosti novčane potpore nabavke instalacija solarnih kolektora u Poljskoj od vlade ili lokalnih pokrovitelja te posebni fondovi utemeljeni u tu svrhu. Analizirani su ...troškovi i dobit kao rezultat primjene solarnih instalacija u procesima zagrijavanja po zahtjevima, proračuna povratka investicije, uzimajući u obzir cijene računa ostalih, tj. više drugih usporednih energija. Sadašnji kolektori ustrojeni su od metala (bakra, aluminija, Al-Mg legure). Rabljenje ovih materijala je u svezi energetskim zahtjevima i proizvodnom tehnologijom. Utjecaji ekonomije ovisni su o solarnim uređajima.
Mineralne i geotermalne vode Hrvatske predstavljaju izuzetno značajan prirodni resurs Republike Hrvatske kojem treba posvetiti bitno više pažnje i istraživanja a poglavito iznaći optimalne oblike ...korištenja prvenstveno u gospodarstvu, energetici, zdravstvu i turizmu. Korištenje ovoga obnovljivog resursa treba kontinuirano pratiti s obzirom na očekivani gospodarski razvitak i učinke koji se time mogu postići uvažavajući podatak da su geotermalni gradijenti hrvatskog prostora znatno viši od europskog prosjeka. S obzirom na sirovinski potencijal i zahtjeve za sve većim količinama mineralnih sirovina Varaždinska županija ima perspektivu razvoja na vlastitim resursima. Međutim, postojeće mineralne sirovine, iako nisu brojne, parcijalno su istražene, nepoznata im je količina, kvaliteta i kompletna primjena. Cilj ovog rada jest skrenuti pozornost na spektar primjene mineralnih sirovina geotermalnih voda koji bi mogao biti znatno širi, nego što je do sada utvrđeno, stoga bi trebalo izvršiti regionalna istraživanja mineralnih sirovina s ciljem izdvajanja perspektivnih područja s najkvalitetnijom sirovinom, te ispitivanja mogućnosti njihove primjene.
The abundance of easily accessible information disenables systematization into meaningful wholes. It is becoming one of the major issues of the general education system. One of the solutions for ...educating new generations is the synthesiological approach. It requires a selection of available information and allows the creation of new, general knowledge. In it, general system theory plays an important role. By synthesiological approach, inputs and outputs from technical systems are analysed: information, energy, and matter. More thoroughly are examined the definitions of these sources. The conclusion is given that each mentioned source can be defined by the other two. The designed equation shows that their sum on the input and output has to be a constant. The states and order of these sources is described in the context of the Big Bang theory. The conclusion is reached that these three sources make a triunity. Systems that have material input, as well as systems without it, which are, however, widely present, such as computer systems and electromagnetic resonance, are considered. A general framework is offered regarding how to implement this knowledge into all levels of contemporary education.
In this study, an alternative approach based on the integral method was proposed to estimate the values of boron diffusion coefficients in the Fe2B layers grown at the surface of Armco iron. The set ...of differential algebraic equations (DAE) system was obtained to estimate the value of activation energy for boron diffusion when pack-boriding of Armco iron in the range of 1123 to 1273 K taking into account the boride incubation time. The present model has been validated by making a comparison between the experimental value of Fe2B layer thickness obtained at 1253 K for 5 h and the predicted results by using two different approaches. A good agreement was observed between these two set of data.
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A mixture of phosphoric and sulfuric acid was used to investigate the dissolution kinetics of phosphate ore by Differential Reaction Calorimetry (DRC). The effect of the solid-to-iquid ratio, ...concentration, stirring speed, particle size and temperature of the reaction is examined. It was established that the dissolution rate increased with stirring speed and particle size. However, rising the olid-to-iquid ratio, temperature and concentration decreased the dissolution rate. It was determined that the dissolution rate fits in the first order of the pseudo-homogeneous reaction model. Two negative values of apparent activation energies were found in the range of 25 to 60?C. The experimental data were tested by graphical and statistical methods and it was found that the following models were best fitted for the experimental data and an empirical equation for the process was developed. -ln (1 ? x) = 2,2 E-09((S/L)0.75C -0.461G0.447(SS) 0.471exp (2671/T)t. T? 40?C -ln (1 ? x) = 2,2 E-09((S/L)0.75C -0.461G0.447(SS) 0.471exp (6959/T)t. T > 45?C
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V oskrbi planinskih postojank v Triglavskem narodnem parku z električno energijo je prišlo v zadnjih dvajsetih letih do izrazitega prehoda iz fosilnih virov na obnovljive vire energije. V poletju ...2012 so imele vse preučevane postojanke nameščene sončne celice, nekatere tudi vetrne generatorje. Na podlagi analize energetske oskrbe postojank, upoštevajoč njihove potrebe po energiji, električno oskrbo in toplotno oskrbo, smo izdelali tipizacijo. Za postojanke, ki za proizvodnjo električne energije še vedno uporabljajo fosilna goriva, smo predlagali ukrepe in izpostavili prednostne naloge.
Cilj članka je procjena povratka ulaganja (PU) i ušteda troškova za predloženo rabljenje solarnih sustava stanovanja utemeljenih pod pokroviteljstvom vlade. Članak daje prijedloge za solarne ...energetske sisteme za različite upotrebe, jednostavni izračun termina povratka ulaganja sa i bez subvencioniranja. Dijelovi za klimatske uvjete, kemijski sastav absorbera i strukturalnih elemenata napravljeni od bakra, odnosno aluminija i Al-Mg legura igraju veliku ulogu u procjeni termina povratka investicije za solarne panele.
The reaction mechanism of MoS2-Fe2O3 aluminothermic reduction in the presence of lime using microwave-assisted combustion synthesis method was surveyed. Achieving technical feasibility in one-step ...production of ferromolybdenum along with sulfur removing in solid form are the main features of this novel process. Simultaneous Preliminary thermoanalytical investigations DSC/TGA and X-ray diffraction experiments during the heating process of 0.42MoS2 +1.14Al + 0.29Fe2O3 +0.84CaO demonstrated four key sequential endothermic and exothermic reactions at 420, 540, 660, and 810?C. The most noteworthy reactions involve evaporation of moisture and volatile matter, molybdenite roasting, simultaneous production of lateral compounds such as CaMoO4 and CaSO4, aluminum melting transition, and final termite reaction. Kinetics procedure of the system was conducted using a classical model-free approach by Kissinger?Akahira?Sunose (KAS) method. In this study, the activation energy was determined about 106.4 (kJ.mol-1) for thermite reaction in the temperature range of 810 to 918?C.
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Učinkovit način eksploatacije blokova kamena ostvaruje se kombiniranjem lančane sjekačice i dijamantne žične pile zbog mogućnosti korištenja prednosti jednog ili drugog stroja. Lančane sjekačice se ...koriste za izradu horizontalnih i vertikalnih rezova, a primjenu su našle u površinskoj i podzemnoj eksploataciji u slabo do srednje abrazivnim i mekim do srednje tvrdim stijenama. Učinkovitost lančane sjekačice pri eksploataciji arhitektonskog kamena ovisi o pravilnom izboru radnih veličina stroja, reznih elemenata te uvjeta i načina eksploatacije u određenoj vrsti stijene. Iako su lančane sjekačice tehnološki napredovale, one još uvijek rade uz određene nedostatke. Dosadašnjim istraživanjima ustanovljeno je da sjekačice ne rade pri optimalnim radnim veličinama, a postojeće konstrukcije lanca nisu dovoljno optimalne. U radu su prikazane postojeće metode za određivanje učinka lančanih sjekačica, a na temelju dosadašnjih istraživanja izložene su smjernice za daljnja istraživanja.
A systematic study of the stacking fault energy (?SF) for the dilute Al-based alloys (Al23X, Al47X and Al71X, where X = Al, Ag, Be, Ca, Cd, Co, Cu, Cr, Fe, Ga, Ge, Hf, In, K, La, Li, Mn, Mg, Ni, Na, ...Pb, Sc, Sn, Sr, Si, Ti, V, Zn, and Zr) has been performed by means of first-principles calculations. Alias shear deformation is adopted in the present investigations. The presently calculated ?SF for Al is in favorable accordance with experimental and other theoretical data. For the targeted elements, the calculations indicate that Na, Si, K, Ca, Sc, Ga, Ge, Sr, Zr, In, Sn, La, Hf, and Pb, in any concentration we considered, decrease the ?SF of Al, while Ag, Be, Cd, Co, Cu, Cr, Fe, Li, Mn, Mg, Ni, Ti, V, and Zn increase the ?SF of Al, when the concentration of alloying elements is 1.39 at. % in the system. With increasing concentration of alloying elements, Li, Mg, V, Ti, and Cd change from increasing the ?SF of Al to decreasing it, based on present investigations. Among the alloying elements, which decrease the ?SF of Al, La decreases the ?SF most significantly. It is also found that the ?SF of Al-X generally decreases with the increase of equilibrium volume. The results obtained in the present work provide an insight into the design of Al based alloys.
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