Croatian Digital Thesis Repository
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Production and testing of skis for alpine skiing
No full textSkijaška industrija bez obzira na klimatske promjene doživljava i dalje svoj rast i razvoj. Radi se na poboljšanju svojstava samih skija, brzini proizvodnje skija, te na materijalima primijenjenim za konstrukciju skija. Jedna skupina tih materijala su preprezi koji se upotrebljavaju kao strukturni sloj skije i skijama daju određena mehanička svojstva, kao što su savojna i uvojna čvrstoća. Preprezi također utječu i na skraćivanje vremena proizvodnje samih skija, te lakše i brže sklapanje skija.
U ovom radu je opisana konstrukcija skija, te su provedena ispitivanja s NEMpreg.ply6540 prepregom. Provedena su ispitivanja samog materijala, te sklapanja skija s tim materijalom i napravljeni su prototipi skija na kojima su također provedena ispitivanja.Ski industry, despite the climate changes, experiences further growth and development. Properties of the skis, production productivity and materials used in ski industry are still in the process of development. One of the materials that experience constant improvement are prepregs. Prepregs are used as a structural layer of the ski, and they provide certain mechanical properties such as torsional and bending strength. They also shorten the production time and make easier ski assembly.
This thesis describes construction of the skis and contains results of tests that were made with NEMpreg.ply6540 prepreg. Within the tests, prepreg material was tested, ski assembly was made with new prepreg, and prototypes of the skis were tested
Recycling aluminium from electrolytic capacitors in waste printed circuit boards
No full textBrzim razvojem tehnologije, elektronički i električni otpad (EE-otpad) je rastuća prijetnja koja
predstavlja značajan problem kontaminacije za čovječanstvo i okoliš.
Temeljni razlog nekontroliranog rasta količina elektroničkog otpada diljem svijeta je brz
napredak inovacija i niskih troškova proizvodnje elektroničke opreme. Zbog toga se moraju
odbaciti vrlo velike količine EE-otpada svake godine čije je zbrinjavanje veliki problem.
Za rješavanje ovog problema oko EE-otpada, metode gospodarenja EE-otpadom kao što su
ponovno korištenje, smanjenje i recikliranje otpada igraju ključnu ulogu. Ove tehnike također
pomažu u uspostavi kružnog gospodarstva.
U ovom diplomskom radu su prikazani potrebni zakoni i pravilnici za zbrinjavanje EE-otpada
te količina prikupljenog i obrađenog otpada u Republici Hrvatskoj u usporedbi s ostalim
zemljama Europske unije. U praktičnom dijelu prikazan je slijed tehnoloških postupaka
oporabe elektrolitskih kondenzatora u pogonu tvrtke koja je ovlaštena upravo za oporabu
takvog otpada. Tvrtka u kojoj je rađen praktičan dio rada, oporaba elektrolitskih kondenzatora
je Spectra-Media d.o.o., koja se nalazi u Donjoj Bistri, Krapinska ulica 62.Rapid development of technology, electronic and electrical waste (EE-waste) is a growing
threat that represents a serious contamination problem for humanity and the environment.
The root cause of uncontrolled waste increase of EE-waste around the world is the rapid
progress of innovation and low production costs of electronic equipment. Because of this, large
amounts of EE-waste must be discarded every year, the disposal of which is a huge problem.
To solve this EE-waste problem, EE-waste management methods such as reusing, reducing and
recycling play a key role. These methods also help to establish a circular economy.
This thesis deals with the necessary laws and regulations for the disposal of EE-waste and the
amount of collected and processed waste in the Republic of Croatia in comparison with other
countries of the European Union. In the practical part, the sequence of technological procedures
for the recovery of electrolytic capacitors in the company's plant, which is authorized for the
recycling of such waste, is presented. The company where the practical part was done is
Spectra-Media d.o.o., located in Donja Bistra, Krapinska Street 62
Weld inspection module for reactor pressure vessel head penetration pipes
No full textU završnom radu osmišljen je i konstruiran modul robotskog sustava Archer, tvrtke Inetec, koji služi za nerazorna ispitivanja stanja reaktorske kape u nuklearnoj elektrani. Modul se mora moći produljivati po potrebi, odnosno treba funkcionirati kao teleskopski mehanizam.
Zadatak je započet određivanjem ulaznih mjera, prostora u koji se modul ugrađuje i potrebnog produljenja modula. Pronađena su zatim patentna rješenja kako bi se odbio uvid u postojeće mehanizme. Uslijedila je izrada funkcijske dekompozicije gdje se pokazalo koje sve funkcije modul mora obuhvatiti te kako su one međusobno povezane. Za svaku funkciju dano je nekoliko konstrukcijskih rješenja u morfološkoj matrici. Odabirom različiti rješenja za svaku pojedinu funkciju, izrađena su različita konceptualna rješenja te je ocjenjivanjem prema traženim tehnološkim karakteristikama odabrano najbolje koje će ići u daljnju razradu.
Odabranom konceptu dane su gabaritne mjere kako bi obuhvatio glavnu funkciju teleskopskog pomicanja. Nakon detaljnije razrade, pronađeni su standardni dijelovi, a ostali dijelovi konstruirani su Inventoru-u. CAD modeli su spojeni u sklop te je prikazan spoj modula s Archer-om i reaktorskom kapom.In this thesis, the module of Archer robotic system was designed. Archer, designed by INETEC company, is used for non-destructive inspections of nuclear reactor vessel head. Its module should be able to prolongate as needed, it should function as a telescopic mechanism.
Work has begun by determination of input measurement for installation space and of demanded prolongation. Then, patent solutions were found to gain ideas of existing mechanisms. Functional decomposition was made afterwards which showed all functions and their connections the module has to contain. Every function was given several design solutions put in a morphological table. Choosing different solutions for every function, various concepts were made. Every concept was graded depending on wanted technological characteristics and the best concept for further development was chosen.
The chosen concept was given overall dimensions for is demanded functions. After detailing, standard parts were chosen and other parts were made in CAD program Inventor. CAD models were joined in one assembly with both Archer and nuclear reactor vessel head
The project of a high-temperature heat pump using waste heat
No full textU radu je napravljen pregled literature te su prikazane dostupne tehnologije korištenja otpadnih voda kao izvora topline za dizalice topline. Također, raspravljeni su osnovni izazovi u implementaciji ovog obnovljivog tipa energije u praksi.
Za stvarne podatke o protocima i temperaturama otpadnih voda na izlazu iz Centralnog pročistača otpadnih voda grada Zagreba razvijen je cjelogodišnji model rada dizalice topline otpadna voda – voda s priključkom na daljinski sustav grijanja četvrte generacije. Rezultati proračuna pokazali su da bi se korištenjem otpadnih voda kao toplinskog spremnika za dizalice topline moglo grijati približno 50 000 stanova/kućanstava u Zagrebu. Ta brojka nikako nije zanemariva i potvrđuje da otpadne vode kriju značajan toplinski potencijal kad bi se koristile u sustavu s dizalicama topline. Upotreba takvog sustava doprinijela bi i do uštede primarne energije za visoki iznos od približno 67 % i do smanjenja emisija ugljikovog dioksida približno 78 % u usporedbi s grijanjem putem toplane.The paper provides a review of the literature and presents the available technologies for utilizing wastewater as a heat source for heat pumps. Additionally, it discusses the main challenges in implementing this renewable energy type in practice.
A year-round operational model of a wastewater-to-water heat pump system, connected to a fourth-generation district heating network, was developed based on real data on flow rates and temperatures of wastewater at the outlet of the Central Wastewater Treatment Plant in Zagreb. The calculation results indicate that using wastewater as a thermal reservoir for heat pumps could provide heating for approximately 50 000 apartments/households in Zagreb. This figure is significant and confirms that wastewater holds substantial thermal potential when integrated with heat pump systems. The implementation of such system would contribute to significant primary energy savings of approximately 67% and reduction in carbon dioxide emissions by around 78% compared to heating via thermal power plant
Synthesis and characterization of tetrahydropyrrolo[3,4- b]indole alkyne, a precursor of hybrid molecules with potential antimalarial activity
No full textMalarija je po život opasna zarazna bolest uzrokovana parazitima roda Plasmodium koji se prenose ubodom zaraženih
komaraca roda Anopheles. Unatoč značajnom napretku u kontroli i liječenju bolesti, malarija i dalje predstavlja
ozbiljnu javnozdravstvenu prijetnju, osobito u tropskim i supstropskim područjima. Rezistencija na postojeće lijekove
je u porastu, zbog čega je istraživanje novih načina liječenja malarije nužno. Ovaj rad obuhvaća sintezu i
karakterizaciju derivata tricikličkog prstena tetrahidropirolo[3,4-b]indola s propargilnom esterskom skupinom kao
ishodišne molekule u sintezi novih hibridnih molekula s potencijalnim antimalarijskim djelovanjem. U svrhu priprave
takvog derivata, modificirani su i kondenzirani indolski prsten i aminokiselina L-fenilalanin, pri čemu je pripravljen
N-tosil nitroindol u dva sintetska koraka. Propargilni ester aminokiseline je pripravljen u tri koraka (5), zatim je
amino- skupina spoja 5 prevedena u izocijanidnu skupinu u dva koraka (7). Izocijanidom modificiran propargilni ester
L-fenilalanina 7 korišten je u dearomatizaciji prethodno pripravljenog N-tosil nitroindola (2) pri čemu je sintetiziran
konačni produkt s karakterističnim tetrahidropirolo[3,4-b]indolskim prstenom (8). Strukture svih sintetiziranih spojeva
potvrđene su standardnim spektroskopskim metodama (1H i 13C NMR). Dobivena molekula će se u budućim
istraživanjima koristiti kao alkinski prekursor u klik-reakciji s azidima 4-amino-7-klorokinolinskih derivata, pri čemu
će nastati hibridi s triazolskom poveznicom potencijalnog antimalarijskog djelovanja.Malaria is a life-threatening infectious disease caused by Plasmodium parasites, transmitted through the bites of
infected Anopheles mosquitoes. Despite significant progress in disease control and treatment, malaria remains a
serious public health threat, particularly in tropical and subtropical regions. The increasing resistance to existing drugs
poses a major challenge, emphasizing the necessity for the synthesis of new antimalarial agents. This thesis
encompasses the synthesis and characterization of tetrahydropyrrolo[3,4-b]indole tricyclic ring derivatives with a
propargyl ester group as a starting molecule for the synthesis of new hybrid compounds with potential antimalarial
activity. To prepare such a derivative, modifications were made to the indole ring and the amino acid L-phenylalanine,
leading to the synthesis of N-tosyl nitroindole in two synthetic steps. The propargyl ester of the amino acid 5 was
synthesized in three steps, after which the amino group was converted into an isocyanide group in two steps. The
obtained isocyanide-modified propargyl ester of L-phenylalanine 7 was then used in the dearomatization of the
previously synthesized N-tosyl nitroindole (2), resulting in the synthesis of the final product featuring a characteristic
tetrahydropyrrolo[3,4-b]indole ring (8)
Removal of carbendazim from aqueous solution by sorption on different low-cost sorbents : diploma thesis
No full textU današnje vrijeme, razvijena poljoprivredna proizvodnja predstavlja veliki ekološki problem zbog značajne uporabe pesticida koji ispiranjem iz tla mogu dospjeti u vodne ekosustave. Zbog štetnog djelovanja na žive organizme i ljudsko zdravlje, ostatke pesticida je nužno ukloniti iz voda. Stoga je u ovom radu ispitana mogućnost pročišćavanja vode onečišćene fungicidom karbendazimom (c o =0,992 mg/L) sorpcijom na različitim low-cost sorbensima – prirodnom zeolitu klinoptilolitu, njegovom modificiranom natrijevom obliku, željezovom obliku te sumporom impregniranom obliku, kao i nusproizvodima prerade voća – košticama maslina, trešanja i višanja. Pri danim eksperimentalnim uvjetima, najveći kapacitet (0,064 mg/g) pokazao je natrijev oblik prirodnog zeolita s učinkovitošću uklanjanja od 64,42 %. Međutim, ostatne koncentracije karbendazima bile su u rasponu od 0,353 mg/L do 0,933 mg/L, što je iznad dopuštenih graničnih vrijednosti od 0,5 µg/L za ukupne te 0,1 µg/L za pojedinačne pesticide u vodi za ljudsku potrošnju. Stoga, kako bi se postigla zadovoljavajuća obrada pesticidima onečišćenih voda, buduća istraživanja treba usmjeriti na odgovarajuću modifikaciju postojećih materijala kao i na kombinaciju više metoda obrade, uključujući adsorpciju, napredne oksidacijske procese ili membranske tehnike.Nowadays, developed agricultural production represents a significant ecological problem due to the extensive use of pesticides, which can leach from soil into aquatic ecosystems. Due to their harmful effects on living organisms and human health, it is necessary to remove pesticide residues from water. Therefore, this study examined the treatment of water contaminated with the fungicide carbendazim (c o =0.992 mg/L) through sorption on various low-cost sorbents – natural zeolite clinoptilolite, its modified sodium form, iron form, and sulphur-impregnated form, as well as fruit processing by-products – olive, cherry, and sour cherry pits. Under the given experimental conditions, the sodium form of natural zeolite showed the highest capacity (0.064 mg/g) with a removal efficiency of 64.42%. However, the residual concentrations of carbendazim ranged from 0.353 mg/L to 0.933 mg/L, which is above the permissible limit values of 0.5 µg/L for total and 0.1 µg/L for individual pesticides in water for human consumption. Therefore, in order to achieve a satisfactory treatment of pesticide-contaminated water, future research should be focused on the appropriate modification of existing materials as well as a combination of several treatment methods, including adsorption, advanced oxidation processes or membrane techniques
Development and evaluation of the method from the determination of tiopronin in pharmaceutical preparations using the sequential injection technique with a spectrophotometric detector : diploma thesis
No full textPrimjenom slijedne analize injektiranjem uz spektrofotometrijski detektor razvijena je i vrednovana nova kinetička metoda za određivanje tiopronina (N-2-merkaptopropionil-glicin, MPG) u farmaceutskim pripravcima. Metoda se temelji na redoks-reakciji u kojoj tiopronin reducira žuti bis(batokuproindisulfonato)kuprat(II) kompleks u stabilan bis(batokuproindisulfonato)kuprat(I) kompleks, karakteristične žuto-narančaste boje, s apsorpcijskim maksimumom pri valnoj duljini od 483 nm. Apsorbancija formiranog kompleksa kontinuirano se mjerila pomoću UV-Vis spektrofotometra, pri čemu su se mjerenja izvodila u triplikatu. Univarijantnom metodom optimizirani su kemijski i protočni parametri sustava, na osnovu čega je konstruirana krivulja umjeravanja za određivanje linearnog dinamičkog područja metode. Regresijskom analizom dobivena je jednadžba pravca y = 5897x + 0,0176, s linearnim rasponom koncentracija analita od 8,0 × 10 -7 do 6,0 × 10 -5 mol L -1 . Određene su granica dokazivanja od 2,54 × 10 -7 mol L -1 i granica određivanja od 8,48 × 10 -7 mol L -1 . Metoda je vrednovana u pogledu točnosti, iskoristivosti i preciznosti, uključujući ponovljivost, učestalost i doseg reakcije. Točnost metode potvrđena je iskoristivošću između 100,70 i 110,81 %. Ponovljivost je bila zadovoljavajuća, uz relativno standardno odstupanje od 4,66 %. U jednom satu moguće je provesti 12 analiza u triplikatu, što daje ukupno 36 analiza. Reakcijski doseg je 90,50 %. Osim acetilsalicilne kiseline i visokih koncentracija borne kiseline, niti jedna od uobičajenih pomoćnih tvari u farmaceutskim proizvodima ne interferira. Razvijena metoda uspješno je primijenjena za određivanje tiopronina u farmaceutskom pripravku Captimer ® , a dobiveni rezultati pokazali su visoku korelaciju sa standardnom farmakopejskom metodom.Using sequential injection analysis with a spectrophotometric detector, a new kinetic method for the determination of tiopronin (N-2-mercaptopropionyl-glycine, MPG) in pharmaceutical preparations was developed and validated. The method is based on a redox reaction in which tiopronin reduces the yellow bis(bathocuproinedisulfonate)cuprate(II) to a stable bis(bathocuproinedisulfonate)cuprate(I), characterized by a yellow-orange color, with an absorption maximum at a wavelength of 483 nm. The absorbance of the formed complex was continuously measured using a UV-Vis spectrophotometer, with measurements performed in triplicate. The chemical and flow parameters of the system were optimized using the univariate method, based on which a calibration curve was constructed to determine the linear dynamic range of the method. Regression analysis yielded the equation y = 5897x + 0.0176, with a linear range of analyte concentrations from 8.0 × 10 -7 to 6.0 × 10 -5 mol L -1 . The limits of detection and quantification were determined as 2.54 × 10 -7 mol L -1 and 8.48 × 10 -7 mol L -1 , respectively. The method was evaluated in terms of accuracy, efficiency, and precision, including reproducibility, analysis frequency and reaction yield. The accuracy of the method was confirmed with efficiency ranging from 100.70% to 110.81%. The reproducibility was satisfactory, with a relative standard deviation of 4.66%. In one hour, 12 triplicate analyses can be performed, resulting in a total of 36 analyses. The reaction yield was 90.50%. Apart from acetylsalicylic acid and high concentrations of boric acid, none of the commonly present excipients in pharmaceutical products interfered with the method. The developed method was successfully applied for the determination of tiopronin in the pharmaceutical preparation Captimer®, and the obtained results showed a high correlation with the standard Pharmacopoeial method
Design of greenhouse dehumidification system
No full textProblemu prekomjerne vlage u staklenicima do sada se najčešće pristupalo otvaranjem prozora i grijanjem vanjskog zraka. Međutim, ova metoda je energetski vrlo intenzivna i nije uvijek učinkovita, posebno u situacijama kada je vanjski zrak već zasićen vlagom. Takvi slučajevi najčešće se javljaju u proljeće i ranu jesen, kada ventilacija i grijanje ne mogu učinkovito smanjiti vlagu unutar staklenika. U tim periodima biljke su izložene dugotrajnim uvjetima visoke vlage, što negativno utječe na njihov rast i zdravlje. Povećava se rizik od razvoja gljivičnih oboljenja, smanjuje kvaliteta usjeva te dolazi do gubitka prinosa. Alternativa navedenom su monoblok klima jedinice koje kondenziraju vlagu i dogrijavaju zrak, no vrlo visoki investicijski troškovi čine ovu tehnologiju neodrživom za većinu kultura uzgajanih u staklenicima. Ovaj rad opisuje koncept uređaja s tekućim desikantom koji može u potpunosti zamijeniti klasične metode grijanja i ventilacije, osiguravajući učinkovito odvlaživanje tijekom cijele godine uz znatno niže investicijske troškove od monoblok jedinica. Predloženi sustav također je energetski učinkovitiji u usporedbi s postojećim tehnologijama. Opis koncepta slijedi dimenzioniranje najbitnijih komponenti i izvedba prototipa. Rezultati dobivenim preliminarnim mjerenjima potvrđuju ispravnost odabranih modela pri dimenzioniranju i opravdavaju nastavak istraživanja i razvoja ovog projekta.The problem of excessive humidity in greenhouses has so far been most often addressed by opening windows and heating the outside air. However, this method is very energy-intensive and not always effective, especially in situations where the outside air is already saturated with moisture. Such cases most often occur in spring and early autumn, when ventilation and heating cannot effectively reduce the humidity inside the greenhouse. During these periods, plants are exposed to long-term conditions of high humidity, which negatively affects their growth and health. The risk of developing fungal diseases increases, crop quality decreases and yield losses occur. An alternative to the above are monoblock air conditioning units that condense moisture and reheat the air, but very high investment costs make this technology unviable for most crops grown in greenhouses. This paper describes the concept of a device with a liquid desiccant that can completely replace classic heating and ventilation methods, ensuring effective dehumidification throughout the year with significantly lower investment costs than monoblock units. The proposed system is also more energy efficient compared to existing technologies. The description of the concept is followed by the sizing of the key components and the development of a prototype. The results obtained from preliminary measurements confirm the correctness of the selected models for sizing and justify the continuation of research and development of this project
Measurement systems in industry and laboratory
No full textOvaj rad se bavi analizom mjernih sustava u industrijskoj proizvodnji i laboratorijima, s ciljem
ocjene njihove pouzdanosti i utjecaja na kvalitetu proizvoda. Kroz rad se analizira važnost
pravilnog odabira i ispitivanja mjernih sustava za osiguravanje točnih, preciznih i stabilnih
rezultata. Obrađuju se osnovne vrste analiza mjernih sustava: analiza tipa 1, analiza linearnosti
i sustavnog pomaka, procjena ponovljivosti i obnovljivosti rezultata mjerenja (engl. GR&R)
ukrižena, ugniježđena i proširena analiza te analiza atributivnog mjernog sustava.
Također se analizira važnost mjerne nesigurnosti u laboratorijskim okruženjima putem Monte
Carlo metode, GUM (engl. Guide to the expression of uncertainty in measurement) te Bayesove
metode.
Za svaku od navedenih analiza mjernih sustava je dan primjer kroz koji je metoda objašnjena,
analizirane su utjecajne komponente na mjerni sustav te analizirani dani rezultati.This thesis addresses the analysis of measurement systems in industrial production and
laboratories, with the aim of assessing their reliability and impact on product quality. The paper
analyzes the importance of proper selection and testing of measurement systems to ensure
accurate, precise, and stable results. It covers the basic types of measurement system analyses:
Type 1 analysis, linearity and systematic shift analysis, the evaluation of repeatability and
reproducibility of measurement results (GR&R) – crossed, nested, and expanded analysis, and
analysis of attribute measurement systems.
Additionally, the paper examines the importance of measurement uncertainty in laboratory
environments through the Monte Carlo method, GUM (Guide to the Expression of Uncertainty
in Measurement), and Bayesian methods.
For each of the mentioned measurement system analyses, an example is provided through which
the method is explained, the influencing components on the measurement system are analyzed,
and the given results are discussed
Numerical modelling of a drop test of a composite battery case
No full textDa bi ispunili sve postavljene zahtjeve, kompoziti, kao osnovni materijal, kućišta i ostali dijelovi baterije podvrgavaju se različitim ispitivanjima u skladu s relevantnim normama. U ovom radu opisana su tlačna ispitivanja kompozitnih materijala, njihovo ponašanje pri udarnom opterećenju, kao i norme koje se odnose na testove pada kućišta baterije, s obzirom na to da su takve situacije moguće tijekom životnog vijeka proizvoda.
U svrhu što bolje simulacije stvarnih uvjeta testa pada (eng. drop test), ispitane su različiti načini pada kućišta baterije. Za najnepovoljniji slučaj pada analizirani su utjecaji broja slojeva u kompozitu, orijentacije slojeva te njihov raspored na naprezanja i oštećenje. Promjenom broja slojeva, orijentacije vlakana i promjenom debljine je postignuto smanjenje vrijednosti maksimalnih naprezanja i oštećenja.In order to meet all the specified requirements, composites used as the base material, battery case, and other battery components are subjected to various tests in accordance with the relevant standards. This thesis describes the compression testing of composite materials, their behaviour under impact loading, as well as the standards related to battery housing drop tests, considering that such scenarios may occur during the product’s service life.
To better simulate real-life conditions during drop tests, various battery case drop scenarios were examined. For the most critical case, the effects of the number of composite layers, fibre orientation, and layer arrangement on stress and damage were analysed. By applying optimization techniques, a reduction in stress values was achieved. Furthermore, by adjusting the number of layers, fibre orientation, and thickness, a reduction in both maximum stress values and damage was achieved