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High-resolution miniature optical fiber sensors for turbulence detection and characterization
Get PDFBacterial nanocellulose biohybrid membranes and beads for potential cosmetics, food, and drug delivery applications
Get PDFBacterial nanocellulose is a promising biomaterial extensively used in functional foods and for drug delivery. Moreover, its characteristics can further be potentialized whether coupled with natural bio-extracts to endow antibacterial activity. Persea americana or avocado seed extracts are rich in phytochemicals and have demonstrated their antioxidant, antimicrobial and enzymatic activities, therefore encapsulating them into bacterial nanocellulose (BNC) may offer a potential release system of antibacterial avocado seed compounds. Accordingly, this study explores the in-depth insight into the influence of different bacterial nanocellulose producing strains (Komagataeibacter hansenii and Komagataeibacter xylinus) and cultivation conditions (static and dynamic cultivation, fermentation time) on the bacterial nanocellulose productivity and characteristics. The obtained bacterial nanocellulose membranes and beads were characterized in terms of chemical structure, morphology and crystallinity. More profitable and productive K. xylinus was further selected for encapsulation (up to 72.89 mg) of avocado seed extracts into bacterial nanocellulose membranes and beads in order to comprehensively evaluate the kinetic release profiles and determine their antibacterial activity against Escherichia coli and Staphylococcus aureus. Results of the study show that the bacterial nanocellulose and avocado seed extracts biohybrids represent a promising immediate (up to 17.39 mg in 1 h) and sustained (up to 35.04 mg in 48 h) release systems. Kinetic release modeling and cytotoxicity assessments confirmed controlled release behavior and biocompatibility for safe antibacterial applications in cosmetics, functional foods and drug delivery
Introduction of preventive vibration measurements with the SKF Quickcollect device and the system for continuous monitoring at critical points of paper machine
No full textPreventivno vzdrževanje strojev in izvajanje meritev vibracij sta v proizvodnem procesu zelo pomembna dejavnika, saj redno vzdrževanje in pravočasno odkritje napak lahko pomembno vpliva na uspešnost poslovanja podjetja ter znižanje stroškov vzdrževanja. S pravočasnimi ukrepi tako povečujemo razpoložljivost stroja, zmogljivost in kakovost.
V magistrskem delu sem v ta namen predstavil osnove merjenja in vrednotenja vibracij v industriji, s katerim lahko ugotavljamo številne nepravilnosti, ki se pojavijo tekom obratovanja (ali pa tudi mirovanja) stroja ali naprave. Na papirnem stroju smo v praksi uvedli tedensko izvajanje meritev vibracij na kritičnih napravah novega papirnega stroja, na podlagi katerih bo lahko podjetje v bodoče spremljalo in tudi analiziralo izmerjene vrednosti ter tako tudi bolje in ustrezno planiralo preventivno aktivnost. Z namenom hitrejšega izvajanja smo izdelali QR kode, v katerih se nahajajo podatki o vgrajenih ležajih, alarmnih vrednostih ter hitrosti obratovanja naprave. Izvedli smo primerjavo stroškov med uvedbo stalnega nadzora vibracij ter izvajanja meritev s strani zunanjega izvajalca ter podjetju predstavili glavne prednosti in slabosti obeh načinov. Z rednim izvajanjem meritev lahko pomembno zmanjšamo nenačrtovane izpade proizvodnje, povečamo varnost in učinkovitost delovanja stroja.Preventive maintenance of machines and performance of vibration measurements are very important factors in the production process, as regular maintenance and timely detection of errors can have a significant impact on the success of the company\u27s operations and the reduction of maintenance costs. By taking timely measures, we increase machine availability, capacity and quality.
For this purpose I presented the basics of measuring and evaluating vibrations in industry, which can be used to identify many irregularities that occur during the operation (or standstill) of a machine or device. At the paper machine, we have implemented weekly vibration measurements on the critical devices of the new paper machine, based on which the company will be able to monitor and analyze the measured values in the future and appropriately plan preventive activities. In order to perform measurements faster we created QR codes that contain datas about the installed bearings, alarm values and device operating speed. We performed a cost comparison between the introduction of permanent vibration control and the performance of measurements by an external contractor, and presented the company with the main advantages and disadvantages of both methods. By regularly performing measurements, we can significantly reduce unplanned production downtime, increase safety and the efficiency of machine operation
Digitalni dvojček elektronskega sistema
No full textAs the market of electrified vehicles is rapidly growing, the requirements for new products are also increasing, meaning the required development and production times are getting increasingly shorter. Therefore, the major interest in current active research is how to optimize the development process. Within this master’s thesis, we developed the base framework for a digital twin for wiring harness development and cross section optimization. It allows engineering teams to develop a digital replica of the desired physical system, which can be the basis for further review and optimization analyses, already at the development stage.Optimizacija razvojnega procesa je trenutno eden izmed glavnih interesov trenutnih raziskav v mnogih industrijah. V okviru tega magistrskega dela smo razvili osnovno programsko okolje za izdelavo digitalnega dvojčka, ki ga lahko uporabimo med razvojem kabelskih snopov in optimizacijo prečnega preseka vodnikov. Ta omogoča inženirskim ekipam, da že v fazi razvoja razvijejo digitalno repliko želenega fizičnega sistema, ki je lahko osnova za nadaljnje preglede in optimizacijske analize
Energy efficiency impact on the value of operating and maintance costs of a multi-residental building
No full textMagistrsko delo obravnava energetsko učinkovitost večstanovanjskih stavb z analizo investicijskih stroškov in obratovalnih ter vzdrževalnih stroškov. Teoretični del zajema koncept energetske učinkovitosti, trende gradnje nizkoenergijskih in skoraj ničenergijskih hiš, relevantno zakonodajo, ter razlago pojmov obratovanja in vzdrževanje stavb. Praktični del vključuje primerjavo investicijskih stroškov in stroškov v času obratovanja stavbe za dva energetska nivoja na konkretnem primeru stavbe, s poudarkom na vplivu toplotnoizolacijskega materiala in stavbnega pohištva. Rezultati kažejo, da povečanje učinkovitosti izboljšuje ekonomičnost obratovanja in vzdrževanja stavbe, kljub višjim investicijskim stroškom. Z analizo ugotavljamo, da debelina in tehnične lastnosti materialov vplivajo na zmanjšanje stroškov ogrevanja ter predstavljajo ključne energetske rešitve za zmanjšanje stroškov ogrevanja večstanovanjskih stavb. Analiza, ki smo jo izvedli v aplikativnem delu je pokazala, da dodatno zniževanje toplotnih izgub v stavbi, ki že izpolnjuje pasivni standard, ni smiselno in skozi kazalce ekonomske upravičenosti investicije, niti upravičeno. Izkazala se je potreba po natančnem načrtovanju in gradnji energetsko učinkovitih stavb kot ključna prioriteta k trajnostnemu razvojuThe master thesis deals with the energy efficiency of multi-apartment buildings by analysing the investment costs and the operation and maintenance costs. The theoretical part covers the concept of energy efficiency, trends in the construction of low-energy and nearly zero-energy houses, relevant legislation, and an explanation of the concepts of building operation and maintenance. The practical part includes a comparison of the investment and lifetime costs for two energy levels in a concrete building example, focusing on the impact of thermal insulation materials and joinery. The results show that efficiency gains improve the economics of building operation and maintenance, despite higher investment costs. The analysis concludes that the thickness and technical properties of materials have an impact on the reduction of heating costs and represent key energy solutions to reduce heating costs in multi-apartment buildings. The analysis carried out in the applied part showed that further reduction of heat losses in a building already complying with the passive standard is not reasonable and, through the indicators of the economic viability of the investment, not justified. The need for careful planning and construction of energy efficient buildings has been demonstrated as a key priority for sustainable development
Impact of process parameters on the quality and stability of Echinacea purpurea extract
No full textV diplomskem delu smo raziskovali vpliv procesnih parametrov na kakovost in obstojnost ekstrakta ameriškega slamnika. Želeli smo pridobiti stabilne ekstrakte ter izolirati čim višje vsebnosti polifenolov in polisaharidov. Najprej smo izvedli sejalno analizo, s katero smo določili mediansko zrno, najpogosteje zastopano zrno in koeficient zrnatosti, ter ugotovili, da je bila zrnatost neenakomerna. V laboratoriju smo izvajali vročo in hladno maceracijo ter ultrazvočno ekstrakcijo. Uporabljali smo pet različnih topil: destilirano vodo, absolutni etanol ter mešanice etanol:voda (70:30), etanol:voda (50:50) ter etil acetat:voda (70:30). Ko smo izvedli vse ekstrakcije, smo pričeli z analiznim delom, kjer smo s spektrofotometričnimi metodami določili vsebnosti totalnih fenolov in proantocianidinov ter antioksidativno aktivnost ekstraktov in ugotovili, da je imel ekstrakt, pridobljen z vročo maceracijo in topilom etanol:voda (70:30), najvišji izkoristek, najvišjo vsebnost totalnih fenolov in najvišjo antioksidativno aktivnost. Najnižji izkoristek pa je imel ekstrakt, ki smo ga pridobili z ultrazvočno ekstrakcijo, kjer smo kot topilo uporabili absolutni etanol. Prav tako je imel ta ekstrakt tudi najnižjo vsebnost totalnih fenolov in proantocianidinov. Večinoma so ekstrakti pokazali visoke vsebnosti fenolnih spojin. Etanolni ekstrakti so pokazali višje vsebnosti fenolnih spojin, prisotnost vode pa je povečala ekstrakcijo proantocianidinov, kar je potrdilo naši hipotezi. Kot predvidevano smo najvišje izkoristke dobili pri vroči maceraciji. Kasneje smo izvedli mikroenkapsulacijo in pridobljenim formulatom določili antioksidativno delovanje ter ugotovili, da je bila učinkovitost precej nizka.In the thesis the influence of process parameters on the quality and stability of purple coneflower (Echinacea purpurea) were investigated. The aim was to obtain stable extracts and isolate the highest possible polyphenols and polysaccharides contents. First, a sieve analysis was carried out to determine the median grain, the most commonly represented grain and the coefficient of grain size, and it was found that the grain size was uneven. Hot and cold maceration and ultrasonic extraction were performed. Five different solvents were used: distilled water, absolute ethanol and ethanol:water (70:30), ethanol:water (50:50) and ethyl acetate:water (70:30) mixtures. After the extractions, the analytical part was followed by the determination of the total phenolic and proanthocyanidin contents and antioxidant activity of the extracts by spectrophotometric methods. The extract obtained by hot maceration with ethanol:water (70:30) solvent had the highest yield, the highest total phenolic content and antioxidant activity. However, the extract obtained by ultrasonic extraction using absolute ethanol as solvent had the lowest yield. This extract had the lowest total phenols and proanthocyanidins content. Most of the extracts showed high contents of phenolic compounds. Ethanol extracts resulted higher phenolic compounds and the presence of water increased the extraction of proanthocyanidins, which confirmed our hypothesis. As expected, the highest yields were obtained with hot maceration. Subsequently, microencapsulation was conducted and the antioxidant activity of the resulting formulations was determined and the value was found to be quite low
Predictive analytics for hardened metal workpieces straightening
No full textV industriji se kovinski obdelovanci pogosto toplotno obdelujejo z namenom poboljšanja njihovih mehanskih lastnosti, pri čemer pa se pojavljajo neželene deformacije njihove geometrije. Zaradi dosežene visoke trdote (60 HRC ali več) klasični pristopi ravnanja z upogibanjem in valjanjem niso učinkoviti, saj se material poruši. V ta namen smo se v okviru doktorske raziskave ukvarjali z analizo vpliva plastičnih površinskih deformacij na spremembe geometrije kaljenih kovinskih obdelovancev.
Izveden je bil laboratorijski eksperiment, v katerem smo na podlagi nadzorovanega vnosa površinskih plastičnih deformacij, visokoresolucijskega zajema geometrije obdelovancev, merjenja pospeškov ter zajema zvoka ravnalnih udarcev (udarci, ki plastično deformirajo površino obdelovanca) pripravili bazo podatkov s 3063 vzorci. Dodatno smo zajemali zvočne odzive nadzorovanih udarcev, ki ne deformirajo površine obdelovanca. Z uporabo U-Net nevronske mreže smo razvili model za napovedovanje spremembe geometrije kaljenega kovinskega obdelovanca glede na vnesene plastične površinske deformacije. V nadaljevanju smo predlagali novo arhitekturo globoke konvolucijske mreže za regresijo, ki omogoča dva vhoda različnih podatkovnih tipov in dimenzij (zvok ravnalnega udarca in reprezentacija geometrije obdelovanca z vključenimi podatki o ravnalnih udarcih) ter večdimenzionalni izhod (napovedana sprememba geometrije obdelovanca). Prav tako smo z uporabo globoke nevronske mreže razvili model, ki izključno na podlagi zvoka nadzorovano izvedenih udarcev, ki ne deformirajo površine obdelovanca, učinkovito napove geometrijo kovinskega obdelovanca. Uspešnost razvitih napovednih modelov smo ocenili z relativno absolutno napako (angl. relative absolute error (RAE)), povprečno kvadratno napako (angl. root mean squared error (RMSE)) in relativno kvadratno napako (angl. relative squared error (RSE)).
Najuspešnejši model za napovedovanje oblike obdelovanca je imel na testnih podatkih odlično zmogljivost napovedovanja, saj so povprečne vrednosti RAE znašale 0,0499, RMSE 0,0129 in RSE 0,0040. Pri vključitvi zvoka v napovedovalni model so vrednosti RAE znašale 0,0739, RMSE 0,0185 in RSE 0,0075. Pri napovedi oblike obdelovanca samo iz zvoka pa so povprečne vrednosti RAE znašale 0,7439, RMSE 0,1744 in RSE 0,5638.In industry, metal workpieces are often heat-treated to improve their mechanical properties, but it also leads to undesirable deformations of their geometry. Due to the high hardness achieved (60 HRC or more), conventional straightening processes like bending and rolling treatment are not effective, since failure of the material occurs. In this regard, the influence of plastic surface deformation on the geometry changes of hardened metal workpieces was analyzed as part of the doctoral thesis.
A laboratory experiment was carried out, creating a database of 3063 samples based on controlled input of plastic surface deformations, high-resolution acquisition of the workpiece geometry, acceleration measurements, and acoustic detection of straightening strikes (strikes that plastically deform the workpiece surface). In addition, we captured the sounds of controlled strikes that do not permanently deform the surface of the workpiece. Using a U-Net neural network, we developed a model to predict the geometry change of a hardened metal workpiece as a function of the applied plastic surface deformations. In addition, we proposed a novel deep convolutional network architecture for regression that allows two inputs of different data types and dimensions (the sound of the straightening strike and the representation of the workpiece geometry with the straightening strike data contained in it) and a multidimensional output (the predicted change in the workpiece geometry). We have also developed a deep neural network model that effectively predicts the geometry of a metal workpiece based only on the sound of controlled strikes that do not deform the surface of the workpiece.
The performance of the developed prediction models was evaluated using the relative absolute error (RAE), root mean square error (RMSE), and relative squared error (RSE). The best model for predicting the shape of the workpiece had excellent prediction performance on the test data, with average RAE, RMSE, and RSE values of 0.0499, 0.0129, and 0.0040, respectively.
When sound was included in the prediction model, the RAE, RMSE, and RSE values were 0.0739, 0.0185, and 0.0075, respectively, but when the shape of the workpiece was predicted using sound alone, the average RAE, RMSE, and RSE values were 0.7439, 0.1744, and 0.5638, respectively
Simulation of flow and thermal conditions in the model of a fuel element rack in a spent nuclear fuel pool
Get PDFV diplomski nalogi je bila izvedena numerična analiza tokovnih in temperaturnih razmer v gorivnem elementu, nameščenem v bazenu za izrabljeno jedrsko gorivo. Simulacije so bile izvedene v programu za računsko dinamiko tekočin ANSYS Fluent, kjer so bile gorivne palice modelirane kot porozni medij z vgrajenim virom toplote. Analiza je obsegala tri sklope: primerjavo različnih hladilnih pristopov (prisilna, naravna in kombinirana konvekcija), preučitev vpliva poroznosti ter preučitev vpliva postopnega zmanjšanja pretoka hladilna vode na temperaturne razmere v modelu. Rezultati prikazujejo spremembo hitrosti pretoka in temperature s spreminjanjem hladilnih pristopov, poroznosti ali masnega toka.In this thesis, a numerical analysis of flow and temperature conditions in a fuel assembly located in a spent nuclear fuel pool was carried out. The simulations were performed using the computational fluid dynamics software ANSYS Fluent, where the fuel rods were modeled as a pourous medium with an embedded heat source. The anlysis consisted of three parts: a comparison of different cooling approaches (forced, natural and combined convection), an investigation on the influence of porosity and an examination of the impact of a gradual reduction in coolant flow on the temparature conditions in the model. The results show changes in flow velocity and temperature with variations in cooling approaches, porosity or mass flow rate
Modelling of flow conditions in the partial model of the reactor pressure vessel lower plenum
Get PDFV diplomski nalogi so bile simulirane tokovne razmere v modelu dela spodnjega planuma tlačne reaktorske posode v tlačnovodni jedrski elektrarni. Simulacije so bile opravljene s pomočjo računskega programa FIRE M. Za diplomsko nalogo so bili pripravljeni različni modeli z različnimi razporeditvami odprtin v podpornih ploščah. Rezultati so pokazali, da nesimetričnost razporeditve odprtin v spodnji kovani plošči nima bistvenega vpliva na homogenost hitrostnega polja.In the diploma thesis, flow conditions in the model of the lower stratum of the pressure reactor vessel in a pressurized water nuclear power plant were simulated. The simulations were performed using the FIRE M computational program. For the diploma thesis, various models with different arrangements of openings in the support plates were prepared. The results showed that the asymmetry of the arrangement of openings in the lower forged plate does not significantly affect the homogeneity of the velocity field
Peridinamično modeliranje utrujanja v večplastnih kovinskih kompozitih
Get PDFIn additive manufacturing, tooling is frequently built from laminated metal composites (LMCs) that stack dissimilar metals to shorten production times. Accurately predicting fatigue-crack growth in these unequal-strength laminates is difficult—particularly across joints where property mismatches steer crack paths. This work combines experiments and simulations to study fatigue-crack growth in an LMC formed by laser-melting AISI 316L powder onto high-strength structural steel S960. Crack growth was modeled with a linearized bond-based peridynamics (PD) formulation, with interfacial bonds tuned to the measured elastic-modulus gradient, and coupled to the Kinetic Theory of Fracture (KTF). Unlike conventional S–N–based approaches, KTF parameters were calibrated directly from measured crack-length–versus-cycles (a-N) data. Material behavior in the base metals and through the transition zone was characterized via tensile tests, hardness mapping, and nanoindentationfatigue-crack growth data came from cyclic tests on compact-tension (CT) specimens. The model reproduced the observed differences in crack-growth rates between homogeneous and bimaterial specimens, and KTF parameter transferability across loads and geometries was confirmed for homogeneous samples. A key outcome is a practical calibration workflow for KTF within a nonlocal PD framework, enabling predictive simulation of fatigue-crack growth across multilayer metallic joints.V aditivni proizvodnji se orodja pogosto izdelujejo iz laminiranih kovinskih kompozitov (angl. Laminated Metal Composites - LMC), ki združujejo različne kovine, da se skrajša čas proizvodnje. Natančno napovedovanje rasti utrujenostnih razpok v teh laminatih z neenako trdnostjo je zahtevno, zlasti na spojih, kjer te neenakosti vplivajo na potek razpok. To delo združuje eksperimente in simulacije za preučevanje rasti utrujenostnih razpok v LMC, oblikovanem z laserskim taljenjem prahu AISI 316L na visokotrdno konstrukcijsko jeklo S960. Rast razpok je bila modelirana z linearizirano formulacijo vezno osnovane peridinamike (PD), pri čemer so bile vezi naterialnem spoju prilagojene izmerjenemu gradientu elastičnega modula in sklopljene s kinetično teorijo loma (angl. Kinetic Theory of Fracture-KTF). Za razliko od konvencionalnih pristopov na podlagi S–N krivulj so bili parametri KTF kalibrirani neposredno iz izmerjenih podatkov o dolžini razpok v odvisnosti od ciklov (a-N). Obnašanje materiala v osnovnih kovinah in prehodni coni je bilo karakterizirano s preskusi natezne trdnosti, merjenjem trdote in nanoindentacijopodatki o rasti utrujenostnih razpok so bili pridobljeni iz cikličnih preskusov na kompaktnih napetostnih (CT) vzorcih. Model je reproduciral opazovane razlike v hitrosti rasti razpok med homogenimi in bimaterialnimi vzorci, prenosljivost parametrov KTF med obremenitvami in geometrijami pa je bila potrjena za homogene vzorce. Ključni rezultat je praktični kalibracijski potek za KTF v nelokalnem PD okviru, ki omogoča numerično napovedovanje rasti utrujenostnih razpok v večplastnih kovinskih spojih