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Impact of UV-LED photoreactor design on N-nitrosopyrrolidine degradation
No full textU ovom radu detaljno su analizirani različiti parametri koji utječu na fotokemijsku razgradnju N-nitrozopirolidina (NPYR) i formiranje razgradnih produkata tijekom procesa fotolitičke i fotokatalitičke razgradnje. Ispitivani su parametri kao što su udaljenosti između stijenke fotoreaktora i izvora zračenja (d), valna duljina (λ) i broj LED traka (N). Također prisutnost fotokatalizatora TiO2, odnosno korištena valna duljina pokazali su se ključnima za brzinu reakcije i učinkovitost razgradnje NPYR-a. Rezultati su pokazali da manji d i veći N potiču bržu razgradnju NPYR-a, dok je veća konstanta brzine reakcije koja podrazumijeva bržu razgradnju uočena pri valnoj duljini od 365 nm u usporedbi s 272 nm. Fotolitička razgradnja NPYR-a brža je u usporedbi s fotokatalitičkom razgradnjom što rezultira i većim brojem razgradnih produkata. Ovi rezultati pružaju uvid u optimizaciju fotokemijskih procesa za obradu onečišćenih voda i očuvanje okoliša. Sveukupno, ovaj rad naglašava kompleksnost i važnost optimizacije parametara u fotokemijskim procesima radi postizanja učinkovite obrade vode.In this research, various parameters that influence the photochemical degradation of
N-nitrosopyrrolidine (NPYR) and the formation of degradation products during the photolytic and photocatalytic degradation process were analyzed. Parameters such as the distance between the photoreactor wall and the radiation source (d), wavelength (λ) and and number of LED strips (N) were examined. Additionally, the presence of the TiO2 photocatalyst and the wavelength used, proved to be crucial for the reaction rate and the efficiency of NPYR degradation. The results showed that lower d and higher N promote faster degradation of NPYR, while a higher reaction rate constant, indicating faster degradation, was observed at a wavelength of 365 nm compared to 272 nm. Photolytic degradation of NPYR is faster compared to photocatalytic degradation, which results in a higher number of degradation products. These results provide insight into the optimization of photochemical processes for the treatment of polluted water and environmental protection. Overall, this research highlights the complexity and importance of parameter optimization in photochemical processes to achieve efficient water treatment
Application of alternative fuels in power system of a cruise ship
No full textAlternativna goriva u pomorskoj industriji intenzivno se istražuju s ciljem smanjenja emisija stakleničkih plinova. Ovaj diplomski rad istražuje primjenu alternativnih goriva (vodika, amonijaka, ukapljenog prirodnog plina, metanola, biodizela i potpuno elektrificiranog sustava) u energetskom sustavu broda za kružna putovanja. Rezultati analize životnog ciklusa (eng. Life-Cycle Assessment, LCA) i analize cjeloživotnih troškova LCCA ( eng. Life-Cycle Cost Assessment, LCCA) različitih alternativnih goriva su uspoređeni s konvencionalnim energetskim sustavom kao referentnim scenarijem. LCA analizom izračunate su emisije ugljikovog dioksida (CO2), emisije sumpornih oksida (SOx), dušikovih oksida (NOx) i lebdećih čestica manjih od 2,5 mikrona (PM 2,5) dok LCCA analiza obuhvaća troškove vezane uz brodski energetski sustav kao i uvođenje ugljičnog poreza čije se kretanje cijena kroz godine predvidjelo Monte Carlo simulacijama. LCA rezultati pokazali su da primjena dizelskog goriva na promatranom brodu rezultira s najvećim CO2 emisijama, dok je čist biodizel istaknut kao ekološki najprihvatljivije gorivo među analiziranim gorivima prema ekološkim kriterijima. Analiza pokazuje da oba goriva, i dizel i čisti biodizel te biodizel u mješavini, daju loše rezultate kad su u pitanju SOx, NOx i PM 2,5 emisije. Metanol se ističe kao najbolji izbor za smanjenje PM 2,5 i SOx emisija, dok se vodik pokazuje najboljim kad je riječ o NOx emisijama. LCCA rezultati pokazali su da brod pogonjen ukapljenim prirodnim plinom ima najmanje troškove, dok se amonijak pokazao kao gorivo koje je ekonomski najneisplativije. Na temelju prosječnih vrijednosti cijena ugljičnog poreza tijekom proteklih 18 godina i njihove stope promjene može se predvidjeti njihov budući trend kretanja. Prema rezultatima simulacije, očekuje se kretanje cijene poreza između 220 i 600 €/t CO2 za 2050. godinu.Alternative fuels in the maritime industry are intensively researched with the aim of reducing greenhouse gas emissions. This thesis explores the application of alternative fuels (hydrogen, ammonia, liquefied natural gas, methanol, biodiesel, and fully electrified systems) in the energy system of cruise ships. Life-Cycle Assessment (LCA) and Life-Cycle Cost Assessment (LCCA) analyses of various alternative fuels are compared with a conventional energy system as the reference scenario. LCA analysis investigates carbon dioxide (CO2) emissions, sulfur oxides (SOx), nitrogen oxides (NOx), and particulate matter less than 2,5 microns (PM 2,5), while LCCA includes costs related to the ship's energy system and the introduction of a carbon tax, whose price fluctuations over the years were predicted through Monte Carlo simulations. LCA results indicate that using diesel fuel in the observed ship results in the highest CO2 emissions, while pure biodiesel is highlighted as the most environmentally acceptable fuel among those studied in terms of CO2 emissions. Research shows that both diesel and pure biodiesel, as well as biodiesel blends, perform poorly in terms of SOx, NOx, and PM 2,5 emissions. Methanol emerges as the best choice for reducing PM 2,5 and SOx emissions, while hydrogen is the best option for NOx emissions. LCCA results indicate that a ship powered by liquefied natural gas has the lowest costs, while ammonia is economically the least viable fuel. Based on average carbon tax prices over the past 18 years and their rate of change, future trends can be predicted. According to simulation results, the carbon tax price is expected to fluctuate between 220 and 600 €/t CO2 by the year 2050
Irrigation of basil and beans with RO retentate
No full textOtpadne vode iz tekstilne industrije predstavljaju veliku opasnost za okoliš te su u pravilu zagađene širokim spektrom tvari čije uklanjanje nije jednostavno. Cilj ovog rada bio je simulirati postrojenje za obradu tekstilnih otpadnih voda (TOV) koristeći hibridni ultrafiltracijsko (UF) – reverzno osmotski (RO) proces, ali s naglaskom na zatvaranje vodenog kruga, odnosno da se sve struje iz membranskog procesa oporabe ili koriste za određene svrhe. Realni uzorci TOV-a prvo su podvrgnuti ultrafiltraciji te je skupljan permeat. Taj permeat je potom obrađivan reverznom osmozom te je retentat korišten za navodnjavanje biljaka bosiljka i graha. Rezultati pokazuju da je UF, kao prva membranska operacija, uspješno smanjila vrijednosti mutnoće, kemijske potrošnje kisika te spektralnog apsorpcijskog koeficijenta. S druge strane, RO je neophodna membranska operacija ukoliko se želi značajno smanjiti vrijednost električne vodljivosti te koncentracija raznih iona u obrađivanim vodama. Analiziranjem voda, biljnog materijala i tla, zaključuje se da su RO retentati te RO retentati razrijeđeni s vodovodnom vodom u omjeru 50:50 sigurni za razvoj biljaka u pogledu koncentracija klorida, nitrata, amonijevih kationa, sulfata, željeza i mangana te pH vrijednosti. U biljkama navodnjavanim TOV-om uočene su veće koncentracije dušika, fosfora i kalija u odnosu na iste biljke navodnjavane vodovodnom vodom, no primjenom razrijeđenih RO retentata u biljkama je utvrđena slična koncentracija navedenih tvari kao u biljkama navodnjavanih vodovodnom vodom. U tlu navodnjavanom TOV-om uočene su značajno veće koncentracije sumpora i fosfora u odnosu na tlo navodnjavano vodovodnom vodom. Primjenom razrijeđenih i nerazrijeđenih RO retentata vrijednosti koncentracija navedenih elemenata niže su nego kod uzorka tla navodnjavanog TOV-om.Textile wastewater (TWW) poses a major threat to the environment and is usually contaminated with a variety of substances that are difficult to remove. The aim of this work was to simulate a textile wastewater treatment plant using a hybrid ultrafiltration (UF) – reverse osmosis (RO) process, with the primary objective of closing the water cycle so that all process streams from the membrane process can be reused or utilised for other purposes. Real samples of TWW were first treated with the UF process and the UF permeate was collected. This permeate was then treated with the RO and the RO retentate was collected as it was used as irrigation water for basil and beans. The results show that UF was the first membrane operation to successfully reduce the values for turbidity, chemical oxygen demand, and spectral apsorption coefficient. On the other hand, RO is the necessary membrane operation when it comes to significantly reducing the values of electrical conductivity and the concentration of various ions in the treated water. Analysis of the water, plant material and soil showed that all RO retentates and all RO retentates diluted 50:50 with tap water were harmless to plant development in terms of chloride, nitrate, ammonia, sulphate, iron, and manganese concentrations and pH. Plants irrigated with TWW were found to have higher concentrations of nitrogen, phosphorus and potassium than plants irrigated with tap water, but when diluted RO retentates were used, these plants had similar concentrations of these substances to the plants irrigated with tap water. In the soil irrigated with TWW, sulphur and phosphorus concentrations were found to be much higher than in the soil irrigated with tap water. When using diluted and undiluted RO retentates, the concentration values of the mentioned elements were lower compared to the soil samples irrigated with TWW
Preparation and characterization of polysaccharide films via layer-by-layer method
No full textTanki filmovi istražuju se kao sustavi za dostavu lijekova, poput kemoterapeutika. Njihova primjena u obliku premaza za implantate ili samostalnih sustava za dostavu lijekova omogućuje kontrolirano i ciljano otpuštanje kemoterapeutika izravno na mjestu tumora, čime se potencijalno smanjuje toksičnost i poboljšava terapijska učinkovitost. Fitinska kiselina, prirodni antioksidans, prepoznata je po svojoj ulozi u prevenciji i liječenju različitih patoloških stanja i karcinoma. Međutim, potrebno je pripremiti pogodne sustave za njezinu dostavu. Zbog velikog broja hidroksilnih skupina fitiska kiselina posjeduje mogućnost stvaranja stabilnih kompleksa s prirodnim polimerima koji mogu poslužiti kao sustavi za dostavu fitinske kiseline. Biorazgradljivost, biokompatibilnost, antimikrobna svojstva i stabilnost polielektrolitnih kompleksa kitozana i alginata (CA) čine ih pogodnima za biomedicinske primjene. Fizikalnim umreživanjem CA polielektrolitnih kompleksa fitinskom kiselinom moguće je postići antitumorska svojstva tih materijala. Stoga je cilj ovoga rada razviti stabilne tanke filmove na osnovi polielektrolitnih kompleksa kitozan-alginat umreženih fitinskom kiselinom primjenom metode sloj-po-sloj. U ovom radu, ispitan je utjecaj koncentracije otopine fitinske kiseline (0,1, 0,5 i 1,0 mas.%) i vremena umreživanja (3,5 i 7 min) na režim rasta i svojstva dobivenih tankih filmova. Tanki filmovi karakterizirani su ATR-FTIR spektroskopijom kako bi se potvrdilo umreživanje fitinskom kiselinom i ispitala učinkovitost procesa ispiranja tankih filmova nakon pripreme. Morfologija površine i presjeka nakon loma ispitane su SEM analizom. Kapaciteti apsorpcije tankih filmova ispitani su u otopinama fosfatnog pufera (pH 6 i 8) te u fosfatom puferiranoj otopini soli (pH 7,4) tijekom 24 sata. ATR-FTIR spektroskopija potvrdila je umreživanje polielektrolitnog kompleksa CA fitinskom kiselinom, a izostanak apsorpcijskih vrpci otapala ukazao je na dostatnost procesa ispiranja. Iako su svi slojevi pokazali strukturnu homogenost, razlike u koncentraciji fitinske kiseline i vremenu umreživanja dovele su do razlike u mehanizmima rasta i posljedično u morfologiji presjeka tankih filmova. Ispitivanjem fizikalnih svojstava pri fiziološkim uvjetima potvrđena je stabilnost tankih filmova koji su maksimalni kapacitet apsorpcije postigli unutar tri sata.Thin films are being investigated as drug delivery systems, particularly for chemotherapeutic agents. Their application as implant coatings or standalone drug delivery systems enables controlled and targeted release of chemotherapeutics directly at the tumor site, thereby potentially reducing systemic toxicity and enhancing therapeutic efficacy. Phytic acid, a natural antioxidant, has been recognized for its role in the prevention and treatment of various pathological conditions and cancers. However, the development of suitable delivery systems is required to realize its full therapeutic potential. Due to its high density of hydroxyl groups, phytic acid has the capacity to form stable complexes with natural polymers, which can serve as carriers for its delivery. The biodegradability, biocompatibility, antimicrobial properties, and stability of chitosan–alginate (CA) polyelectrolyte complexes make them suitable for biomedical applications. Physical cross-linking of CA polyelectrolyte complexes with phytic acid may result in antitumor properties of the resulting materials. The aim of this study was to develop stable thin films based on chitosan–alginate polyelectrolyte complexes cross-linked with phytic acid using layer-by-layer assembly (LbL). The effect of phytic acid solution concentration (0.1, 0.5, and 1.0 wt%) and cross-linking time (3,5 and7 minutes) on the growth regime and properties of the resulting thin films was investigated. Thin films were characterized by ATR-FTIR spectroscopy to confirm cross-linking with phytic acid and to assess the effectiveness of the rinsing process after film preparation. Surface and cross-sectional morphology following fracture were examined using SEM analysis. The absorption capacity of the thin films was evaluated in phosphate buffer solutions (pH 6 and 8) and in phosphate-buffered saline (PBS, pH 7.4) over a period of 24 hours. ATR-FTIR spectroscopy confirmed successful cross-linking of the CA polyelectrolyte complex with phytic acid, and the absence of solvent absorption bands indicated the adequacy of the rinsing process. While all films exhibited structural homogeneity, variations in phytic acid concentration and cross-linking time resulted in differences in growth mechanisms, thereby affecting the morphology of the film cross-sections. Evaluation of film physical properties under physiological conditions confirmed their stability, with maximum apsorption capacity reached within three hours
Feedforward neural network for credit risk assesment
No full textCilj ovog diplomskog rada je primjena umjetnih neuronskih mreža u određivanju kreditnog rizika. U uvodu diplomskog rada objašnjena je problematika zadane teme, dana je definicija kredita te su navedeni svi programski paketi koji su korišteni u radu. U drugom poglavlju razrađena je teorija umjetnih neuronskih mreža. Zatim slijedi analiza dobivenih podataka o klijentima i kreditima od banke, kao i priprema istih za ulaz u unaprijednu neuronsku mrežu. U programskom jeziku Python 3 definirana je optimalna unaprijedna neuronska mreža pomoću paketa Keras (TensorFlow). Parametri mreže i njena struktura detaljno su opisani u četvrtom poglavlju rada, nakon čega slijedi analiza dobivenih izlaza mreže. U zaključku rada navedene su prednosti i mane korištene unaprijedne mreže, kao i moguća poboljšanja s ciljem dobivanja preciznijih predviđanja kreditnih rizika.The aim of this thesis is to present the work of artificial neural networks application in credit score determining. In the introduction, the problems of the given assignment are explained, the definition of loan is given, and all software packages used in the paper are listed. In the second chapter, the theory of artificial neural networks is elaborated. This is followed by an analysis of the data obtained on clients and loans from the bank, as well as preprocessing the same data so it can be later used as input for the feedforward neural network. In the Python 3 programming language, the optimal feedforward neural network is defined using the Keras package (TensorFlow). The parameters of the neural network and its structure are described in detail in the fourth chapter of the paper, followed by the analysis of the obtained network outputs. The paper concludes with the advantages and disadvantages of the feedforward network that is used, as well as possible improvements in order toto obtain more accurate credit score forecasts
Bridge carrier for a 140 t bridge crane
No full textU ovom radu prikazan je postupak dimenzioniranja i konstruiranja mosta granika nosivosti 140 tona za precizno rukovanje teretom, dodatno opremljenog s pomoćnim vitlom nosivosti 15 tona. Nakon uvodnog razmatranja postojećih mogućih konstrukcijskih rješenja, kreće se u detaljan proračun kutijastih nosača mosta te mehanizma za vožnju granika. Nakon proračuna slijedi konstrukcijska razrada mosta ganika uz mehanizam za vožnju.This paper presents the procedure which goes into dimensioning and design of a overhead crane bridge with a lifting capacity of 140 tons for precise handling, additionally equipped with an auxiliary hoist with a lifting capacity of 15 tons. An introductory review of already existing possible solutions is followed up by a detailed calculation of box girders an the travel mechanism of the crane. The calculations are followed by the design elaboration of the overhead crane bridge along with the travel mechanism
Increasing the productivity of manufacturing processes in glass manufacturing
No full textU prvom dijelu rada, opisan je nastanak Vitke proizvodnje i pristup implementaciji istih u proizvodne sustave. Potpuno prediktivno održavanje (TPM) i Ukupna učinkovitost opreme (OEE) navode se kao dva ključna alata u poduzećima za praćenje produktivnosti sa ciljem definiranja gubitaka u procesu i eliminaciju istih. Nadalje, dat je osvrt Manufacturing Execution System-a (MES) kao digitalnog rješenja za praćenje proizvodnje. U praktičnom dijelu rada, analizirana je proizvodna linija prerade stakla u poduzeću Press Glass. Iskorišteni su TPM i OEE alati za prepoznavanje i grupiranje gubitaka koji su bili temelj za unapređenje MES sustava čime se omogućilo praćenje proizvodnje i njenih gubitaka u realnom vremenu. Konačno, na temelju prikupljenih podataka, predložena su poboljšanja procesa proizvodnje.In the first part of the paper, the origin of Lean manufacturing and the approach to their implementation in production systems are described. Total Productive Maintenance (TPM) and Overall Equipment Efficiency (OEE) are listed as two key tools in companies to monitor productivity with the aim of defining process losses and eliminating them. Furthermore, a review of the Manufacturing Execution System (MES) as a digital solution for production monitoring is given. In the practical part of the paper, the production line of glass processing in the company Press Glass is analyzed. TPM and OEE tools were used to identify and group losses, which were the basis for the improvement of the MES system, which enabled the monitoring of production and its losses in real time. Finally, based on the collected data, improvements to the production process are proposed
TBM modeli predviđanja napredovanja. Usporedba napredovanja predviđenog u natječaju i u stvarnosti. Projekt: Anneberg–Skanstull tunel (Stockholm, Švedska) : diplomski rad
No full textThe most widely used prediction model for hard rock is the Colorado School of Mines (CSM) model, which was used for tender prediction in the Anneberg - Skanstull Tunnel (AST) project. However, during the construction phase, the TBM penetration rate was lower than predicted in the model. Intact rock strength is usually the first rock mechanic parameter obtained from geological investigation for tunnelling projects. This is one of the key parameters used in the Tunnel Boring Machine (TBM) prediction model. The most common rock mechanic test for intact rock strength determination is the Uniaxial Compressive Strength (UCS). After core sampling from the tunnel, new UCS values were obtained, analysed, filtered, and implemented in the CSM model to generate new penetration rates for different lithologies.Za stijene visoke čvrstoće, najčešće korišteni TBM model predviđanja je Colorado School of Mines (CSM), koji je i korišten u natječaju za izradu Anneberg-Skanstull tunela (AST). Međutim, tijekom konstrukcije tunela, uočeno je sporije napredovanje nego što je predviđeno u modelu. Svojstva stijena obično su prva informacija dobivena iz geoloških istraživanja kod izrade tunela. Ovo je jedan od ključnih parametara korištenih kod izrade modela za predviđanje napredovanja stroja za bušenje tunela (eng. TBM). Najčešća metoda ispitivanja stijenske mase je Jednoosna Tlačna Čvrstoća (eng. UCS). Nakon jezgrovanja u tunelu, nove UCS vrijednosti su dobivene, analizirane i uvrštene u CSM model s ciljem generiranja novih stopa napredovanja za druge litologije
Microbial degradation of xenobiotics under aerobic conditions
No full textMnoga znanstvena otkrića omogućila su bolju kvalitetu života i dovela do povećane proizvodnje ksenobiotika koji se najčešće nepravilno odlažu te su jedan od glavnih uzročnika loše kakvoće okoliša. Značajna skupina takvih tvari antropogenog podrijetla su farmaceutici. Kako oni imaju složenu strukturu i mehanizam djelovanja na različite vrste organizama, važno je pronaći nove i učinkovite načine uklanjanja ksenobiotika te pratiti njihov utjecaj na okoliš. U tu svrhu se sve više koriste ekonomični i okolišno prihvatljivi procesi poput biorazgradnje, koji koristi enzimske i metaboličke sposobnosti mikroorganizama za razgradnju organskih onečišćujućih tvari. U ovome radu proveden je proces biorazgradnje β-laktamskog antibiotika amoksicilina pomoću okolišne Gram-pozitivne bakterije Bacillus subtilis. Biorazgradnja amoksicilina provedena je u šaržnim i aerobnim uvjetima. Početne koncentracije amoksicilina iznosile su 278 mg L^-1 (Bs-1) i 658 mg L^-1 (Bs-2). Na temelju rezultata testova osjetljivosti, aktivnost bakterijske kulture Bacillus subtilis nije inhibirana djelovanjem navedenog antibiotika. Učinkovitost procesa biorazgradnje amoksicilina iznosila je 99,7 %.Many scientific discoveries have enabled a better quality of life and led to increased production of xenobiotics, most of which are improperly disposed of and are a major cause of poor environmental quality. An important group of such substances of anthropogenic origin are pharmaceuticals. Since they have a complex structure and mechanism of action on different types of organisms, it is important to find new and effective methods for disposing of xenobiotics and monitoring their impact on the environment. To this end, economical and environmentally sound methods such as biodegradation, which utilises the enzymatic and metabolic capabilities of microorganisms to degrade organic pollutants, are increasingly being used. In this work, the process of biodegradation of the β-lactam antibiotic amoxicillin was carried out using the environmentally occurring Gram-positive bacterium Bacillus subtilis. The biodegradation of amoxicillin was carried out in a batch process and under aerobic conditions. The initial concentrations of amoxicillin were 278 mg L^-1 (Bs-1) and 658 mg L^-1 (Bs-2). According to the results of the susceptibility tests, the activity of the Bacillus subtilis bacterial culture was not affected by the mentioned antibiotic. The efficiency of the biodegradation process of amoxicillin was 99.7 %
Seismic Calculation for a Dry-stacked Tower in the Italian Province of Rovigo : Master's Thesis
No full textU ovom radu prikazana je primjena razvijenog numeričkog modela s ciljem analize ponašanja građevinske konstrukcije pod djelovanjem potresa. Za potrebe istraživanja uzet je u obzir značajan potresni događaj koji se desio 1979. godine u mjestu Petrovac, smještenom u Crnoj Gori. Istraživanje je usmjereno na temeljitu analizu suhozidane konstrukcije. Analitički proračuni temelje se na primjeni kombinirane metode konačno-diskretnih elemenata. Kroz provedeno istraživanje dobiveni su rezultati koji prikazuju krajnja stanja konstrukcije, uključujući fazu potpunog kolapsa.This study presents the application of a developed numerical model aimed at analyzing the behavior of a building structure under the influence of an earthquake. For the purpose of this research, a significant seismic event that occurred in 1979 in Petrovac, located in Montenegro, has been taken into consideration. The research is focused on an in-depth analysis of dry-stone masonry construction. Analytical calculations are based on the application of a combined finite-discrete element method. Through the conducted research, results have been obtained that depict the ultimate states of the construction, including the phase of complete collapse