Application of artificial neural networks in performance prediction of cement mortars with various mineral additives

The machine learning technique for prediction and optimization of building material performances became an essential feature in the contemporary civil engineering. The Artificial Neural Network (ANN) prognosis of mortar behavior was conducted in this study. The model appraised the design and characteristics of seventeen either building or high-temperature mortars. Seven different cement types were employed. Seventeen mineral additives of primary and secondary origin were embedded in the mortar mixtures. Cluster Analysis and Principal Component Analysis designated groups of similar mortars assigning them a specific purpose based on monitored characteristics. ANN foresaw the quality of designed mortars. The impact of implemented raw materials on the mortar quality was assessed and evaluated. ANN outputs highlighted the high suitability level of anticipation, i.e., 0.999 during the training period, which is regarded appropriate enough to correctly predict the observed outputs in a wide range of processing parameters. Due to the high predictive accuracy, ANN can replace or be used in combination with standard destructive tests thereby saving the construction industry time, resources, and capital. Good performances of altered cement mortars are positive sign for widening of economical mineral additives application in building materials and making progress towards achieved carbon neutrality by reducing its emission

Response surface method as a tool for heavy clay firing process optimization: Roofing tiles

Heavy clay samples collected in close vicinity of Toplička Mala Plana, Serbia, were surveyed to examine their possible use in heavy clay industry. The representative raw material, which contained the lowest content of clay minerals and the highest content of carbonates, was enriched with two more plastic clays. Chemical and mineralogical composition, as well as particle size distribution, were determined to distinct the samples. The samples in the form of tiles, hollow blocks and cubes were prepared following the usual practice in ceramic laboratories. The effect of process parameters, such as temperature (850-950 °C) and concentration of the added clays (both in the range of 0-10 wt.%), were investigated in terms of compressive strength, water ab­sorption, firing shrinkage, weight loss during firing and volume mass of cubes. The optimal conditions were determined by the response surface method, coupled with the fuzzy synthetic evaluation algorithm, using mem­bership trapezoidal function, and showed that these materials can be used for roofing tiles production

Importance of on-time decision making in energy sector based on perspectives case study new stavalj project

Expression "Development conditions and perspectives" became important for numerous analyses in various industrial and social areas. Several strategic documents and studies in last two decades analysed projects with topics on perspectives of future development in Serbia. Various tools are used for development of such documents, based on recent scientific and numerical solutions, thus providing reliable assessment for strategic decision making. Almost all analyses tried to implement the theories and practical experiences through the prism of "sustainable development", which included establishment of most important sitstainability parameters. Analysis and ranking presented in this paper considered the potential of the Stavalj coal deposit, near city of Sjenica in Serbia, and feasibility of construction project of new mine and thermal power plant. Basis for analysis was a hybrid assessment model which takes into account principles of sustainable development. The model incorporates quantified SWOT analysis, which applies to active underground mines in Serbia. Special attention was given to the parameters describing potential for development

Analytical modeling of activation procedure applied in α-alumina thermo-mechanical synthesis

The impact of the mechanical processing parameters on the alumina grain-size distribution affiliated characteristics and on the γ to α phase transformation rate was investigated. The moderation in the alumina samples behavior has been correlated to the granulometric and mineralogical changes induced by activation via an ultra-centrifugal mill. The assessment of the activation process variables influence on the final quality of the product parameters was conveyed in order to optimize the mechanical treatment of the alumina, which otherwise could be regarded as either energetically or economically unsustainable procedure. The Response Surface Method, Standard Score Analysis and Principal Component Analysis were applied as means of the mechanical activation optimization. The r 2 values obtained by developed models were in range from 0.816 to 0.988. The established mathematical models were able to precisely predict the quality parameters in a broad range of processing parameters. The Standard Score Analysis emphasized that the optimal output sample was obtained using a sieve mesh of 120μm set of processing parameters (SS=0.96). Diverse comparison analyses disclosed that the optimal set of activation process parameters could reduce the negative effect of γ-alumina samples immanent properties on the final score, and furthermore to enhance the rate of γ to α transition which would improve energetic and economic sustainability of the alumina phase transformation procedure. © 2015 Elsevier Ltd and Techna Group S.r.l

Numerical study of the hydrodynamics and mass transfer in the external loop airlift reactor

The objective of this study was to investigate the hydrodynamics and the gas-liquid mass transfer coefficient of an external-loop airlift reactor (ELAR). The ELAR was operated in three cases: different inlet velocities of fluids, different alcohols solutions (water, 0.5% methanol, 0.5% ethanol, 0.5% propanol and 0.5% butanol) and different concentration of methanol in solutions (0%, 0.5%, 1%, 2% and 5%). The influence of superficial gas velocity and various diluted alcohol solutions on hydrodynamics and the gas-liquid mass transfer coefficient of the ELAR was studied. Experimentally, the gas hold-up, liquid velocities and volumetric mass transfer coefficient values in the riser and the downcomer were obtained from the literature source. A computational fluid dynamics (CFD) model was developed, based on two-phase flow, investigating different liquids regarding surface tension, assuming the ideal gas flow, applying the finite volume method and Eulerian-Eulerian model. The volumetric mass transfer coefficient was determined using the CFD and artificial neural network model. The effects of liquid parameters and gas velocity on the characteristics of the gas-liquid mass transfer were simulated. These models were compared with the appropriate experimental results. The CFD model successfully simulates the influence of different alcohols regarding the number of C-atoms on hydrodynamics and mass transfer

Protok granulisanog materijala u statičkoj mešalici, DEM/CFD pristup

The mixing process greatly influence the quality of the intermediate and/or the final product, moreover, the parameters of the mixing process and the design of used equipment have a strong impact on mixing efficiency, the quality and the price of the product. In this article, Discrete Element Method is used for modeling of granular flow in multiple static mixer applications (Komax and Ross configurations were utilized). Computational Fluid Dynamic method was chosen for fluid flow modeling, using Eulerian multiphase model. Coupling of these two methods provides reliable, sufficiently correct and adequate results of proposed model compared to experimental measurements. The aim of this article is to predict the behavior of granules in different mixer configuration and to optimize parameters of the mixing process taking into account the duration of the mixing process and the quality of mixture, as well as the price of final product.Proces mešanja veoma utiče na kvalitet krajnjeg poluproizvoda i/ili krajnjeg proizvoda, a parametri procesa mešanja i dizajn opreme veoma utiču na efikasnost mešanja, kvalitet proizvoda i cenu proizvoda. U ovom radu, prikazana je upotreba metode diskretnih elemenata (engl. Discrete Element Method - DEM) na modelovanje mešanja granula u različitim konfiguracijama statičkih mešača (korišćene su različite Komax i Ross konfiguracije za mešanje). Za modelovanje protoka fluida primenjena je metoda računske dinamike fluida (engl. Computational Fluid Dynamic - CFD), korišćenjem Ojlerovog višefaznog modela. Povezivanjem rezultata ove dve metode dobija se pouzdan, dovoljno tačan i adekvatan model koji daje rezultate koji odgovaraju eksperimentalnim merenjima. Praćene su i analizirane trajektorije, brzine i ubrzanja čestica, u cilju procene kvaliteta procesa mešanja. Dobro poznati kriterijum za kvalitet mešanja, pod nazivom relativna standardna devijacija (RSD) je korišćen za ovu svrhu. Optimizacija dimenzija i parametara mešanja u statičkoj mešalici je izvedena korišćenjem matematičkog modeliranja. Cilj ovog rada je bio da se predvidi ponašanje granulamog materijala u različitim konfiguracijama mešalica i da optimizuje parametre procesa uzimajući u obzir trajanje procesa mešanja, kvalitet mešavine i cenu finalnog proizvoda mešanja. U istraživanju je primećeno da su Komax elementi primenljiviji, u poređenju sa Ross elementima, posebno kada je visina instalacije mala. Međutim, upotreba Ross je finansijski prihvatljivija, zbog njegove jednostavnije geometrije. Dodatna pregrada sa kvadratnim otvorima, koja se postavlja na izlazu iz statičke mešalice, koristi se da bi se umirilo kretanje granula na obodu cevi, kao i da smanji segregaciju granula

DEM analysis of the granular flow in the static mixers

Statičke mešalice se koriste za mešanje pre glavnog procesa mešanja, čime se značajno smanje vreme mešanja i potrošnja energije. U ovom radu, prikazana je upotreba metode diskretnih elemenata (engl. Discrete Element Method - DEM) na modelovanje mešanja granula u različitim konfiguracijama statičkih mešača (korišćene su različite Komax i Ross konfiguracije za mešanje). Za modelovanje protoka fluida primenjena je metoda numeričke mehanike fluida (engl. Computational Fluid Dynamic - CFD), korišćenjem Ojlerovog dvofaznog modela. Povezivanjem rezultata ove dve metode dobija se pouzdan, dovoljno tačan i adekvatan model koji daje rezultate koji odgovaraju eksperimentalnim merenjima. Statičke mešalice se široko koriste u industiji prerade hrane, farmaceutskoj ili hemijskoj industriji. Ovaj tip mešalice se koristi uglavnom kao predmešač, pre glavnog mešanja, pri čemu se značajno smanjuje vreme mešanja i štedi energija. Za potrebe ovog rada, napravljene su statičke mešalice tipa Ross i Komax od providnog pleksiglasa, dizajnirane u CAD paketu, napravljene korišćenjem CNC glodalice. Pošto su napravljeni elementi bili prozirni, praćenje procesa mešanja granula je bilo i vizuelno. Praćene su i analizirane trajektorije, brzine i ubrzanja čestica, u cilju procene kvaliteta procesa mešanja. Glavni cilj ovog članka je da određivanje ponašanja granula koje se gravitaciono transportuju u različitim konfiguracijama mešalica i odabir najbolje konfiguracije mešalice, uzimajući u obzir ukupnu trajektoriju granule, broj elemenata za mešanje i kvalitet dobijene smeše. Rezultati numeričke simulacije statičkih mešalica upoređeni su sa eksperimentalnim rezultatima, a kvalitet mešanja ispitivan je kriterijumom relativne standardne devijacije. Uticaji tipa mešalice i broja elemenata za mešanje na proces mešanja su proučavani analizom varijanse (ANOVA).Static mixer is used for premixing action before the main mixing process, for significant reduction of mixing time and energy consumption. In this article, the novel numerical approach called Discrete Element Method is used for modeling of granular flow in multiple static mixer applications, while the Computational Fluid Dynamic method was chosen for fluid flow modeling. The main aim of this article is to predict the behaviour of granules being gravitationally transported in different mixer configuration and to choose the best configuration of the mixer taking into account the total particle path, the number of mixing elements and the quality of the obtained mixture. The results of the numerical simulations in the static mixers were compared to experimental results, the mixing quality is examined by relative standard deviation criterion. The effects of the mixer type and the number of mixing elements on mixing process were studied using analysis of variance (ANOVA)

DEM analysis of the granular flow in the static mixers

Statičke mešalice se koriste za mešanje pre glavnog procesa mešanja, čime se značajno smanje vreme mešanja i potrošnja energije. U ovom radu, prikazana je upotreba metode diskretnih elemenata (engl. Discrete Element Method - DEM) na modelovanje mešanja granula u različitim konfiguracijama statičkih mešača (korišćene su različite Komax i Ross konfiguracije za mešanje). Za modelovanje protoka fluida primenjena je metoda numeričke mehanike fluida (engl. Computational Fluid Dynamic - CFD), korišćenjem Ojlerovog dvofaznog modela. Povezivanjem rezultata ove dve metode dobija se pouzdan, dovoljno tačan i adekvatan model koji daje rezultate koji odgovaraju eksperimentalnim merenjima. Statičke mešalice se široko koriste u industiji prerade hrane, farmaceutskoj ili hemijskoj industriji. Ovaj tip mešalice se koristi uglavnom kao predmešač, pre glavnog mešanja, pri čemu se značajno smanjuje vreme mešanja i štedi energija. Za potrebe ovog rada, napravljene su statičke mešalice tipa Ross i Komax od providnog pleksiglasa, dizajnirane u CAD paketu, napravljene korišćenjem CNC glodalice. Pošto su napravljeni elementi bili prozirni, praćenje procesa mešanja granula je bilo i vizuelno. Praćene su i analizirane trajektorije, brzine i ubrzanja čestica, u cilju procene kvaliteta procesa mešanja. Glavni cilj ovog članka je da određivanje ponašanja granula koje se gravitaciono transportuju u različitim konfiguracijama mešalica i odabir najbolje konfiguracije mešalice, uzimajući u obzir ukupnu trajektoriju granule, broj elemenata za mešanje i kvalitet dobijene smeše. Rezultati numeričke simulacije statičkih mešalica upoređeni su sa eksperimentalnim rezultatima, a kvalitet mešanja ispitivan je kriterijumom relativne standardne devijacije. Uticaji tipa mešalice i broja elemenata za mešanje na proces mešanja su proučavani analizom varijanse (ANOVA).Static mixer is used for premixing action before the main mixing process, for significant reduction of mixing time and energy consumption. In this article, the novel numerical approach called Discrete Element Method is used for modeling of granular flow in multiple static mixer applications, while the Computational Fluid Dynamic method was chosen for fluid flow modeling. The main aim of this article is to predict the behaviour of granules being gravitationally transported in different mixer configuration and to choose the best configuration of the mixer taking into account the total particle path, the number of mixing elements and the quality of the obtained mixture. The results of the numerical simulations in the static mixers were compared to experimental results, the mixing quality is examined by relative standard deviation criterion. The effects of the mixer type and the number of mixing elements on mixing process were studied using analysis of variance (ANOVA)

Application of discrete element method for the transportat of seed in screw conveyor

Pužni transporteri imaju široku primenu u prehrambenoj industriji, građevinskim i rudarskim kompanijima, u hemijskoj, poljoprivrednoj i prerađivačkoj industriji, uglavnom za podizanje i / ili transport rasutih materijala na kratkim i srednjim rastojanjima. Uprkos njihovoj očiglednoj jednostavnosti, poboljšanje transportnih parametara je veoma zahtevan zadatak i inženjeri obično moraju da se oslanjaju na podatke dobijene empirijskim istraživanjima. U ovom radu, ispitivano je petnaest horizontalnih pužnih transportera sa konstantnim korakom pužnice, različite dužine, sa modifikovanom geometrijom. Ovi puževi su ispitivani radi mogućnosti pomoćnog mešanja tokom transporta materijala. Sva ispitivanja su rađena eksperimentalno i numerički, pomoću metode diskretnih elemenata (Discrete Element Method - DEM). Uticaji dužine puža, kao i predložene modifikacije geometrije u dizajnu pužne spirale, ipitivani su radi pomoćnog mešanja, tokom transporta granulisanog materijala kroz pužni transporter. Pomoćno mešanje (koje se koristi se za poboljšanje finalnog procesa mešanja) je postignuto tokom transporta materijala. Geometrija pužnog transportera se menja dodavanjem tri komplementarne spirale orijentisane u istom ili suprotnom smeru od pužne spirale. Čestice materijala se transportuju padaju dole sa vrha spirale do sledeće slobodne površine, i taj segment spirale je korišćen za dodatnu akciju mešanje. Prema eksperimentima i DEM analizema trajektorija čestice se povećava, sa primenjenim modifikacijama transportera, a ovakva geometrija može se koristiti za povećanje kvaliteta finalnog mešanja.Fifteen horizontal single-pitch screw conveyors with modified geometry and the different lengths were investigated for premixing action, during the transport of materials. All investigations were performed experimentally and numerically, by using Discrete Element Method (DEM). The influences of screw length, observed geometry variations and different types of screw design, on the performances of the screw conveyor-mixer during material transport were explored. The auxiliary mixing action was achieved during the transport of the material. The geometry of the screw conveyor is changed by adding three complementary helices oriented in the same or the opposite direction from screw blades. The particles of the material being transported tumble down from the top of the helix to the next free surface, and that segment of helix was used for additional mixing action. According to DEM analysis, particle path length is increased, and the improved geometry could be determined for increasing the quality of mixing

Application of discrete element method for the transportat of seed in screw conveyor

Pužni transporteri imaju široku primenu u prehrambenoj industriji, građevinskim i rudarskim kompanijima, u hemijskoj, poljoprivrednoj i prerađivačkoj industriji, uglavnom za podizanje i / ili transport rasutih materijala na kratkim i srednjim rastojanjima. Uprkos njihovoj očiglednoj jednostavnosti, poboljšanje transportnih parametara je veoma zahtevan zadatak i inženjeri obično moraju da se oslanjaju na podatke dobijene empirijskim istraživanjima. U ovom radu, ispitivano je petnaest horizontalnih pužnih transportera sa konstantnim korakom pužnice, različite dužine, sa modifikovanom geometrijom. Ovi puževi su ispitivani radi mogućnosti pomoćnog mešanja tokom transporta materijala. Sva ispitivanja su rađena eksperimentalno i numerički, pomoću metode diskretnih elemenata (Discrete Element Method - DEM). Uticaji dužine puža, kao i predložene modifikacije geometrije u dizajnu pužne spirale, ipitivani su radi pomoćnog mešanja, tokom transporta granulisanog materijala kroz pužni transporter. Pomoćno mešanje (koje se koristi se za poboljšanje finalnog procesa mešanja) je postignuto tokom transporta materijala. Geometrija pužnog transportera se menja dodavanjem tri komplementarne spirale orijentisane u istom ili suprotnom smeru od pužne spirale. Čestice materijala se transportuju padaju dole sa vrha spirale do sledeće slobodne površine, i taj segment spirale je korišćen za dodatnu akciju mešanje. Prema eksperimentima i DEM analizema trajektorija čestice se povećava, sa primenjenim modifikacijama transportera, a ovakva geometrija može se koristiti za povećanje kvaliteta finalnog mešanja.Fifteen horizontal single-pitch screw conveyors with modified geometry and the different lengths were investigated for premixing action, during the transport of materials. All investigations were performed experimentally and numerically, by using Discrete Element Method (DEM). The influences of screw length, observed geometry variations and different types of screw design, on the performances of the screw conveyor-mixer during material transport were explored. The auxiliary mixing action was achieved during the transport of the material. The geometry of the screw conveyor is changed by adding three complementary helices oriented in the same or the opposite direction from screw blades. The particles of the material being transported tumble down from the top of the helix to the next free surface, and that segment of helix was used for additional mixing action. According to DEM analysis, particle path length is increased, and the improved geometry could be determined for increasing the quality of mixing