Iskanje po katalogu digitalne knjižnice

Opis: Magistrsko delo je eksperimentalne narave. Modelirali smo TPMS celico gyroida in znotraj celice oblikovali avksetično geometrijo. Geometrija je izdelana iz bolj togega PLA filamenta, ostanek celice pa iz elastičnega TPU filamenta. Nato je bil izveden 3D-tisk več vzorcev, vključno z vzorci z majhnimi variacijami, kar je omogočilo primerjavo vpliva različnih sprememb geometrije. Mehansko testiranje je izvedeno tako, da so bili vzorci stisnjeni med dvema ploščama, pri čemer smo beležili sile stiskanja in istočasno snemali za nadaljnjo analizo z DIC programom. Pri analizi rezultatov smo primerjali SEA, CFE in Poissonovo število.
Ključne besede: avksetična struktura, 3D-tiskanje, PLA filament, TPU filament, TPMS celica, gyroid, SEA, CFE, Poissonovo število
Objavljeno v DKUM: 22.08.2024; Ogledov: 63; Prenosov: 10
Celotno besedilo (3,38 MB)

Opis: Varovanje objektov in premoženja je sestavljeno iz mehanskih, tehničnih in fizičnih elementov varovanja. Osnovni namen varovanja objekta in premoženja je preprečevanje škodnih dogodkov na varovanih območjih zaradi požara, vloma oz. ropa in varovanje premoženja pred poškodovanjem, odtujitvijo ali uničenjem. Tudi v sedanjem času kvalitetna mehanska zaščita ustrezno zagotavlja in dopolnjuje varnost objekta in premoženja. Mnogokrat jo uporabimo za dodatno zaščito objektov, ki so že varovani s sistemi tehničnega varovanja. Z razvojem materialov in metod 3D tiska se povečuje varnostna problematika kopij fizičnih ključev. Z razvojem programske opreme, s katero se ustvarja 3D modele za tisk, se povečuje tveganje rekonstrukcije ključev iz slikovnega gradiva, to velja tako za slike samega ključa kot tudi slike ključavnice. To predvsem velja za mehanske ključavnice s cilindričnim jedrom, ki uporabljajo le profil ključa za odklepanje. Iz slike ključa lahko torej ustvarimo 3D model ključa, ki je funkcionalna replika. Bolj kot je preprost mehanizem ključavnice, hitrejša in enostavnejša je izdelava replike, ki v najenostavnejših primerih traja le par minut. To je v celoti odvisno od vrste tiskalnika in tehnike oz. ločljivosti tiskanja. Najbolj popularen in ugoden material je PLA zaradi nizkega tališča, visoke toplotne odpornosti, nizkega toplotnega raztezanja, dobrega oprijema plasti; še posebej zaradi trdnosti pa je idealen material za ta namen. Preprečevanje podvajanja ključev bo zahtevalo prilagoditev varnosti, ki temelji na izključno mehanskih ključavnicah.
Ključne besede: 3D tiskanje, fizični ključi, podvajanje, polimlečna kislina, diplomske naloge
Objavljeno v DKUM: 06.05.2024; Ogledov: 278; Prenosov: 75
Celotno besedilo (1,06 MB)

Opis: Tissue engineering (TE) is an interdisciplinary field that aims towards replacement, healing or reconstruction of damaged tissue and organs. Incurable diseases are currently treated with organ transplantation, that have the disadvantages of insufficient donors, immune response, and organ rejection after transplantation. TE imitate the functions of extracellular matrix (ECM) to develop biocompatible/biodegradable scaffolds with appropriate features which are utilized to provide mechanical support, cellular infiltration, migration, and tissue formation, and to mimic the biochemical and biophysical cues of cells. Several fabrication methods have been introduced to mimic the 3D structure of ECM and 3D printing is one of the additive manufacturing techniques, widely used in TE because of its feasibility to build complex tissue constructs and control over fabrication and cell distribution. The polysaccharide-peptide conjugate has gained enormous interest in recent years owing to its biocompatibility, degradability, flexibility, and structural matching to natural proteoglycans. In this context, we reported here on investigation of biocompatibility with HUVECs, surface modification of 3D printed PCL scaffolds with an amine group and chemically crosslinked oxidized HA-amino acid/peptide conjugates (OHACs) was used to develop a novel biomaterial for use as a tissue engineered vascular graft. Modified polysaccharides were characterized with respect to their chemical structure, charge, UV and fluorescence properties and cytotoxicity. The successful conjugation was demonstrated by XPS, and a decrease in the free amine peaks on the surface was observed after conjugation. In addition, the water contact angle measurements showed improved wetting, an indication that the conjugation to the PCL-A surface was successful. Finally, the biocompatibility of the novel scaffolds was characterized by the MTS and the live- dead assay. In both assays, proliferation of cells was observed after 7 days and cell spreading on the surface was detected by phalloidin staining of actin filaments. In conclusion, it was possible to prepare surface-active scaffolds by combining the advantages of biocompatibility and mechanical strength of polysaccharides and polyesters, respectively.
Ključne besede: 3D tiskanje, karboksimetilceluloza, hialuronska kislina, polikaprolakton, kemija karbodiimida, kemija Shiffove baze, endotelizacija 3D printing, carboxymethyl cellulose, hyaluronic acid, polycaprolactone, carbodiimide chemistry, shiff-base chemistry, endothelialization
Objavljeno v DKUM: 06.10.2023; Ogledov: 522; Prenosov: 50
Celotno besedilo (7,97 MB)

Opis: Al(OH)3 nanoparticles (ATH NPs) and phosphorylated cellulose nanofibrils (PCNFs) were used as user-friendly and comfortable coating components on flame-retardant fabric to improve its thermophysiological comfort and high-intensive heat protection properties. The effect of the PCNF imprinting and its attachment after the post-printing of a hydrophobic polyacrylate (AP) on the same (back side) or the other (front) side of the fabric, with and without the addition of ATH NPs, was considered, to maintain the front side (facing the wearer) as hydrophilic while keeping the back side (facing the outside) hydrophobic. The amount of coatings applied and their patterning were studied, varied with the ATH NPs’ concentration (1.7, 3.3 and 6.7 wt%) and screen mesh size used (60 and 135), based on the coating’ mass, fabric’s air permeability, thickness and microstructure. The reduced moisture build-up (55%), increased the water vapour (13%) and heat (12%) transfer from the skin, were assessed by applying PCNF under the AP, being more pronounced in the case of using a 135 mesh-sized screen, given the smaller, more densely distributed, thinner and imprinted pattern coatings. These effects were further improved by the addition of nanoporous ATH NPs, which allowed more homogeneous spreading of the moisture and its faster transport. Such a treatment also shifted the fabric’s degradation temperature towards higher values (up to 15°C), retained up to 30% of high-heat flux (21 kW/m2), prolonged the time to ignition by 11 s and reduced the total heat released by up to 60%, thereby providing better protection when exposed to the heat, due to the presence of the phosphorous (PCNF) promoted generation of an Al2O3 char acting as a barrier layer, while also reducing the production of heat and generation of smoke by 75%.
Ključne besede: tekstilna tehnologija, ognjevaren tekstil, Al(OH)3 nanodelci, celulozni nanofibrili, tiskanje tekstilij, optične lastnosti, termofiziološko udobje, toplotna zaščita, flame-retardant textile, Al(OH)3 nanoparticles, phosphorylated cellulose nanofibrils, screen-printing, thermophysiological comfort, heat protection
Objavljeno v DKUM: 12.07.2023; Ogledov: 455; Prenosov: 14
Celotno besedilo (2,91 MB)
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Opis: Zaključno delo govori o razvoju prezračevalnega sistema z možnostjo upravljanja le-tega s pomočjo telefona, tablice ali računalnika. Delo zajema metode kot so 3D modeliranje, načrtovanje vezja, Programiranje v C jeziku, programiranje v HTML in Javascript jezikih, sestava vezja oz. spajkanje ter montažo sistema. V začetku smo podrobneje analizirali podobne sisteme, ki so ponujeni na trgu in glede na to opredelili zahteve za naš sistem z namenom, da bi bil le-ta boljši. Sledila je izbira ustreznih komponent, ki so na voljo na trgu, nato pa načrtovanje in izdelava strojnih in elektronskih delov ter montažo teh v smiselno zaključeno celoto. Na koncu sledi analiza našega oz. lastnega sistema v kateri ugotavljamo ali sistem v celoti izpolnjuje v začetku postavljene zahteve in glede na to podamo rezultate. Sledi še opis in rešitev večjih težav, ki jih je pomembno izpostaviti in pa zaključni komentar z nekaj idejami za nadgradnjo.
Ključne besede: razvoj, prezračevalni sistem, rekuperacija toplote, Wi-Fi, upravljanje na daljavo, 3D modeliranje, 3D tiskanje, načrtovanje, vezja, mikrokrmilnik, programiranje, C, C++, HTML, Javascript, CSS, spletna stran, Websocket
Objavljeno v DKUM: 08.11.2022; Ogledov: 1043; Prenosov: 157
Celotno besedilo (2,28 MB)
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