Browsing by Author "Vik, Michal"

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    Biotechnology in Textile Pre-treatment
    (Technická Univerzita v Liberci, 2011) Mfuywa, Siviwe Artwell; Vik, Michal
    The cellulases of the soft-rot fungus. Trichoderma reesei are the most studied and understood of all cellulolytic systems. Cellulases are used for modification of cellulosic fibres and fabrics, e.g. cotton, viscose and lyocell, yielding properties such as stonewashing, peach-skin and biofinishing effects. Cellulases are usually applied as multi-component enzyme systems and most of the commercial cellulases contain a variety of different activities. The cellulolytic system of T. reesei is composed of two cellobiohydrolases (CBHI and CBHII), at least six endoglucanases and two ?-glucosidases. Cellulases are known to act synergistically in the hydrolysis of crystalline cellulose. Endoglucanases randomly attack the amorphous regions in cellulosic substrates, whereas cellobiohydrolases can also act the crystalline regions of cellulose, releasing cellobiose from the ends of cellulose chain. In the present investigation, purified T. reesei cellulases CBHI, CBHII, EGI and EG II were used to treat different types of cotton fabrics in order to evaluate the effects of individual mono-component cellulases on cotton properties. By comparing the impact of mono-component cellulases on cotton twill and poplin woven fabrics and interlock knitted fabric; it became apparent that cellobiohydrolases and endoglucanases have different effects on the tested fabrics.
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    Color difference formulae evaluation by method of adjustment
    (Multi-Science Publishing Co. Ltd, 2014) Abbasi, Abdul Malik Rehan; Vik, Michal; Viková, Martina
    This experiment was carried out to test color difference formulae by method of adjustment. 6 different color centers (Red, Yellow, Green, Blue-Green, Blue and Violet) were chosen for this psychophysical experiment. 336 virtual sample pairs were prepared. The mean color difference was three CIELAB units. Each pair was assessed by a panel of 15 observers using psychophysical methods called Method of Adjustment. These visual data were used to test color-difference formulae: CIELAB, CMC, CIE94, DIN99d and CIE2000 with the help of simple statistical measures i.e., PF/3 and Stress. It was found that the visual results obtained from psychophysical method of adjustment show that CIE94 as well as DIN99d still perform well for small color differences.
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    COLOR PERCEPTION ESTIMATIONS OF METAMERIC PAIRS UNDER DIFFERENT ILLUMINANCE LEVELS
    (Technical University of Liberec, ) Mukthy, Azmary Akter; Vik, Michal; Viková, Martina; Technická univerzita v Liberci
    LEDs or light emitting diodes of the lighting class dominate both the indoor and outdoor lighting industries today due to their accuracy and consumer-friendly color temperature. In the context of color science, it is necessary to analyze both the spectral power distribution of lighting and the human characteristics of color perception under these lights. In this article, we provide estimates of the appearance of eleven metameric pairs under LEDs with four correlated color temperatures and six illuminance levels, using color difference formulas based on the CIELAB, CAM02-UCS, and CAM16-UCS models to verify our estimates. We followed ASTM D4086 standard visual methods for detecting metamerism and for estimating the magnitude of a metameric color difference. Our investigations found that color appearance models are more reliable than CIELAB in evaluating color difference under various LED conditions. CAM16-UCS more accurately predicted the color difference estimates between all three formulas. Our comparative study confirms that the variation in the estimates with the CCT and illuminance levels of the LED sources depends on the color appearance model used. The results also showed that in order to determine the color difference of metameric pairs, optimal conditions regarding the colorimetric properties of the samples and the variability of the observer should be considered separately. We noticed an increasing correlation trend with increasing illuminance. However, there was no such increase or decrease trend in CCTs. The trend of the STRESS change in the color appearance models showed the influence of the chromatic adaptation, but the establishment of adaptation patterns is far beyond the scope of this work. Although our research has had limitations on correlated color temperature and illuminance, we believe that it can be beneficial for the lighting application to ensure correct lighting decisions when assessing the color differences of metameric pairs.
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    Color Performance, Durability and Handle of Inkjet-Printed and UV-Cured Photochromic Textiles for Multi-Colored Applications
    (2019-07) Seipel, Sina; Yu, Junchun; Viková, Martina; Vik, Michal; Koldinská, Marie; Havelka, Antonín; Nierstrasz, Vincent A.
    The development and design of novel functional and smart textile materials such as textile sensors and multi-colored systems based on photochromic dyes necessitate controls of color intensities, switching speeds, and material durability. Precise control and synchronization of dye kinetics are important for multi-colored photochromic applications especially. However, durability towards abrasion and washing should not be compromised on if we aim to design reliable future textile products. In this study, two different commercial photochromic dyes - a naphthopyran and a spirooxazine-based dye - have been applied on PET fabric by inkjet printing and UV-LED curing. The photochromic textiles' color behavior, fastness to abrasion and washing, and handle are evaluated using spectrophotometry, scanning electron microscopy, and Kawabata evaluation system. Despite a decrease in color performance after washing, the photochromic inkjet print is effective and barely influences the textile structure. Reduced rigidity of the host matrix promoted higher color yields and faster dye kinetics, but also improved durability towards abrasion and washing. In order to synchronize kinetics of the different dye types for multi-colored applications, distinct curing conditions are preferable, which, however, result in varying print durability. In the design of multi-colored photochromic textiles, dye kinetics, and durability have to be balanced.
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    Comparison of the photochromic behaviour of dyes in solution and on polyester fabric applied by supercritical carbon dioxide
    (IOP PUBLISHING LTD, DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND, 2018) Abate, M. T.; Seipel, S.; Viková, Martina; Vik, Michal; Ferri, A.; Jinping, G.; Chen, G.; Nierstrasz, V. A.
    Photochromic textiles are of considerable interest for smart and functional textile applications due to their remarkable dynamic colour changing effect when irradiated with light of a certain wavelength. The use of resource efficient processes, such as digital inkjet printing and supercritical carbon dioxide (scCO(2)) dyeing techniques enables an economic production of those high-end functional products with high material costs. In this study, photochromic polyester fabric has been prepared by applying two commercially important photochromic dyes from spirooxazine (SO) and naphthopyran (NP) dye classes using scCO(2)-dyeing technique. The properties of scCO(2) dyed photochromic fabrics were compared with the properties of the same dyes in a non-polar solvent, hexane. UV-Vis spectroscopy and a specially designed online colour measurement system capable of simultaneous UV irradiation and colour measurement were used to evaluate the photochromic colour behaviour. Both photochromic dye types embedded in textile as well as in solution showed significant reversible colour changing properties when exposed to UV light and revert to their original non-coloured form when the UV light is removed. The scCO(2) dyed polyester fabrics exhibited similar trends of colour build-up as in solution, while contrasting behaviour was observed in terms of colour changing rates compared to their behaviour in solution.
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    Copper electroless plating of cotton fabrics after surface activation with deposition of silver and copper nanoparticles
    (Elsevier Ltd, 2020-02) Ali, Azam; Baheti, Vijay; Vik, Michal; Militký, Jiří
    In this work, surface metallization of cotton fabrics was performed by electroless plating using a shorter route than is conventional. The fabric surface was activated by deposition of silver and copper nanoparticles, and then a thin layer of copper was coated using electroless plating. The performance of coated fabrics was compared in terms of electrical conductivity, electromagnetic interference (EMI) shielding, Joule heating and antibacterial properties with another sample coated with conventional electroless plating. The orthogonal array testing strategy was adopted to optimize the various factors of the electroless plating bath. The samples prepared by electroless plating of copper showed greater performance for the fabric first deposited with silver particles than those first deposited with copper particles or conventionally treated. Samples of copper electroplating over silver had surface resistivity of 20 Ω, EMI shielding of 75.53 dB and Joule heating of 83.1 °C. Moreover, samples with modified electroless plating showed better attachment of the metal layer and therefore longer durability.
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    Design pro osoby s kataraktou
    (Technická Univerzita v Liberci, 2011) Šmídková, Yveta; Vik, Michal
    Práce se zabývá studií rozlišování barev u skupiny osob s kataraktou - šedým zákalem. Měření rozlišování barev se provádělo pomocí FM 100 Hue testu. Vyhodnocovalo se procentuální zlepšení vnímání barev před a po operaci katarakty a porovnávaly se výsledky rozlišování barev mezi osobami s kataraktou a osobami bez katarakty. Dále se pro zvolené skupiny osob s kataraktou určily oblasti, ve kterých byly barvy rozlišovány s nejmenší úspěšností. Výsledky se také porovnávaly s charakteristikami vad vnímání barev. Simulace sníženého vnímání barev se uskutečnila pomocí počítačového programu Color Vision Filter. Navržené postupy programu umožňují podle výsledků FM 100 Hue testu přetransformovat scénu do barev, jak je vidí testovaná osoba. Získané znalosti je možné dále využít pro specifický design určený osobám se sníženým vnímáním barev.
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    Design pro osoby s vadami barvocitu
    (Technická Univerzita v Liberci, 2010) Kašparová, Markéta; Vik, Michal
    Tato bakalářská práce se zabývá vnímáním barev. Především se zaměřuje na osoby postižené šedým zákalem. Teoretická část se zabývá popisem orgánu sloužícího k pozorování a vnímání barev. Dále se zaměřuje na popisu onemocnění zvaného katarakta. Třetí část teoretické části bakalářské práce se věnuje barvocitu a historii o vnímání barev. Praktická část je zaměřena na zjištění, jak vidí pacienti postižení šedým zákalem před a po operaci. V této části najdete popis prováděného testu. Hlavní část praktické části této bakalářské práce je zaměřena na simulaci vidění pacientů pomocí programu Photoshop. Naleznete zde i pokus o návrhy úprav tohoto programu a samotný pokus o realizaci simulace.
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    Digitalizace barevného vzhledu historických textilií
    (Technická Univerzita v Liberci, 2013) Bendová, Mária; Vik, Michal
    Cieľom diplomovej práce je poukázať na digitalizáciu historických textílii ako na ?kultúrne dedičstvo?. V prvej časti tejto práce sú popísane základné teoretické poznatky vzťahujúce sa ku skúmanej problematike v oblasti kolorimetrie so zameraním na digitálne systémy záznamu obrazových dát. Teória sa predovšetkým orientuje v oblasti farebných modelov, miešaniu farieb a vzniku farebného vnemu, kde sa podieľajú tri základné faktory. Ďalej je v práci popísaná správa farieb pre zariadenia a taktiež bezkontaktné meranie pri digitalizácii alebo pred samotným reštaurovaním diela a stručný prehľad o historických textíliách a ich reštaurovaní. V experimentálnej časti sa diplomová práca zaoberá vplyvom osvetlenia na kolorimetrické parametre finálneho obrazového záznamu vzniknutom na snímači, pri opakovanom meraní. Detailné popísanie použitých zariadení a podmienok za akých bolo hodnotenie prevádzané. A následná kolorimetrická analýza výskytu jednotlivých odtieňov v systéme CIE LAB na historických textíliách. V úplnom závere diplomovej práce sa nachádza vyhodnotenie výsledkov.
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    EVALUATION OF COLOR-DIFFERENCE FORMULAE USING CRT COLORS
    (Technická Univerzita v Liberci, 2010) Abbasi, Abdul Malik Rehan; Vik, Michal
    This research work was carried out to test color difference formulae by method of adjustment. 6 different color centers (Red, Yellow, Green, Blue-Green, Blue and Violet) were chosen for this psychophysical experiment. 336 virtual sample pairs were prepared. The mean color difference was DECIELAB three units. Each pair was assessed by a panel of 5 observers using psychophysical methods called Method of Adjustment. These visual data were used to test color-difference formulae: CMC, CIE94, DIN99d and CIE2000 together with basic CIELAB, with the help of simple statistical measures to fit i.e., PF/3, Stress and Wrong Decision Criteria. In the second step, the Lightness parametric factor kL was optimized for CMC, CIE94, DIN99d and CIE2000 with kC=kH=1. It was found that the visual results obtained from psychophysical method of adjustment showed that CIE94 being as a simplest linear transformation of CIELAB as well as DIN99d being as a logarithmic transformation perform very well for small color differences for both, original form and optimized form.
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    Image processing technique for cotton color grading
    (Fiber Society, 2018) Khan, Nayab; Vik, Michal; Yildirim, Bekir; Farooq, Assad
    Cotton color measurement is very important property which plays important role in determining the cotton grade. Although other physical properties like length, strength, fineness and maturity are also very important in determining the cotton color grade, in aesthetic property cotton color is very important. There are different methods used to measure the cotton color in cotton growing countries globally. Use of HVI (High Volume Instrument) is a common practice for cotton color measurement along with other physical properties. But, the final color grade mostly awarded on the basis of visual inspection. There is a strong disagreement between the visual color grading and instrumental color grading.
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    Kolorimetrická analýza systému uspořádání barev podle p. J. Hejzlara - ÚBOK
    (Technická Univerzita v Liberci, 2013) Očovská, Lucia; Vik, Michal
    Práca je zameraná na rozbor farieb z katalógu, ktorý zostavil pán PhDr. Jozef Hejzlar. Katalóg vznikol pod záštitou Ústavu bytovej a odevnej kultúry (ÚBOK) v Prahe. Základným princípom práce je porovnávanie hodnôt nameraných zo vzoriek Hejzlarovho katalógu a nameraných zo vzoriek pantone ale i porovnanie Kubelka - Munkovou funkciou. Taktiež nosným prvkom je zaistenie princípu miešania farieb podľa pána Hejzlara, na základe vyhodnotenia grafov z nameraných kariet. V práci sa pozrieme na výskyt farebných tónov za posledných 30 rokov 20st. po súčasnosť. Výskyt tónov si priblížime pomocou grafu, v ktorom získame lepší prehľad o používaní farieb v trendoch od roku 1969 až po rok 1990.
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    Komplementární kolorimetrie roztoků
    (Technická Univerzita v Liberci, 2012) Valapková, Barbora; Vik, Michal
    The bachelor work is engaged in study of transmission and absorption spectra of disperse dyes and olive oils. Dyes were measuremed at different concentrations while differences were observed between the total and regular transmission. The measurement was used in several devices which are then compared to their match.
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    Laboratory analysis of the main properties and a color stability of a coating layers under the UV loading
    (Technical University of Liberec, Dept. of Design of Machine Elements and Mechanisms, Studentská 2, Liberec 1, Czech Republic; Technical University of Liberec, Dept. of Material Engineering, Studentská 2, Liberec 1, Czech Republic, 2017-02-15) Kulhavý, Petr; Kaniová, Eva; Fliegel, Vítězslav; Vik, Michal
    For individual components as well as for the final products is need to determine their resistance and other mechanical properties, which can be changing due to the various conditions and simultaneously we try to get still closer to the real operating conditions.Currently, given the need to guarantee a perfect quality of the product throughout its entire life cycle, it is necessary to assess the protective layers that are in direct contact with the material itself or with the future products.This article presents the results of testing individual components of the selected materials and their resistance to the UV rays. These were some samples of a prelacquered sheet and a powder coated plate after their forming, next by pigment colored concrete cubes, artificial wood and a prototype sample of the translucent material Licrete.Compared to a conventional climate tests such as heat, cold, humidity or the salt chambers, the colored protection layers were subjected to a strong UV rays. Subsequently was evaluated the change of the colors, brightness and where it was possible also the adhesion parameters and thickness of the coated layer. The measurement wasn't focused only on the adhesion and color stability, but also to a violation of microstructure due to high temperatures caused by the UV ray. The selected specimens were tested in a device which simulates solar radiation and then were them evaluated the changes of a colors and on the surface structure.
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    Měření optických vlastností turbidních médií se zaměřením na predikci prodyšnosti textilií
    (Technická Univerzita v Liberci, 2007) Křelinová, Anna; Vik, Michal
    Diplomová práce je zaměřena na nalezení vztahu mezi měřením prodyšnosti textilií a jejich světelnou propustností. Teoretická část se zabývá teorií turbidních médií, jejich měřením pomocí optiky a vzduchu. Dále pak chybami, které se při měření mohou vyskytnout. Obsahuje také přehled charakteristik měřené sady tkanin a podrobnější informace o měřících přístrojích. V experimentální části je popsána metodika měření prodyšnosti a světelné propustnosti. Je provedeno porovnání vzájemného vtahu mezi naměřenými hodnotami. Na základě výsledků je navržena konstrukce jednoduchého měřícího přístroje pro bezkontaktní měření prodyšnosti pomocí optických metod.
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    Měření optických vlastností zubních náhrad
    (Technická Univerzita v Liberci, 2016) Hošic, Dušan; Vik, Michal
    Tato bakalářská práce má za úkol analýzu spektrálních dat u kompozitních materiálů pomocí měřících systémů. Porovnání a vyhodnocení jednotlivých metod měření. Práce se zabývá problematikou zubních náhrad a jejich vzhledem. V teoretické části se věnuje vnímání barev lidským okem a barevným prostorům. Práce popisuje metody bělení zubů, jejich výhody a nevýhody. Dále se věnuje formulaci potencionální aplikace pro inteligentní telefony.
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    Měření prodyšnosti vojenských oděvních materiálů
    (Technická Univerzita v Liberci, 2006) Vacek, Jiří; Vik, Michal
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    Mikrospektrofotometrie
    (Technická Univerzita v Liberci, 2006) Votýpková, Jana; Vik, Michal
    Subject of this diploma work is research of possible use of mikrospectofotometry in forensic analysis and for identification of fibres. In the first part of the diploma work there are information about existing and experience of criminology, describe a acceptation word inkling and microinkling and introduce with methods used in field of criminologist. More describe with individual parts of microscope and describe individual display methods, which were use in experimentation. Finally theoretic parts of diploma, there is describe actual condition in field of micospectrofotometry. In the experimental part, there is projected and realized an experiment, which evalute use microspectrophotometry of identificatoin of fibers5
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    Photochromic Polypropylene Filaments: Impacts of Mechanical Properties on Kinetic Behaviour
    (2019) Periyasamy, Aravin Prince; Vikova, Martina; Vik, Michal
    Spiro [2H-indole-2,3'-[3H]naphth [2,1-b][1,4]oxazine],1,3-dihydro-1,3,3-trimethy-6'-(1-piperidinyl) was incorporated onto polypropylene and photochromic polypropylene multifilaments produced through the mass coloration technique. Subsequently the polypropylene (PP) filaments were doped with a different concentration of photochromic pigment, and after producing the filaments different drawing ratios were applied. The photochromic colour build was found to be maximum with the highest concentration of dyes as well as with the lowest drawing ratio. Also the colour differences for L*, a*, b* and Delta E* were analysed with respect to the different concentrations and drawing ratios of the filament. The filaments generally showed good stability of photocoloration during the colour measurement till five cycles. The results for the optical density were reduced by increasing the fineness of the filament. In this experimental work, the impact of the drawing ratio on the optical and mechanical properties of these multifilaments were investigated.
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    Posudky barevných rozdílů na hranici barevného prostoru zobrazovaného LCD monitorem
    (Technická Univerzita v Liberci, 2012) Bartůňková, Erika; Vik, Michal
    Cílem práce je provést studii vizuálního hodnocení barevných rozdílů na souboru čtyř barevných center vybraných z hranič Experimentální část se zabývá vizuálními posudky barevných rozdílů sledovaných na LCD monitoru. Je zde detailně popsáno, jak se provádělo hodnocení barevných diferencí, jaké byly v experimentu použity přístroje, a za jakých podmínek bylo vizuální hodnocení prováděno. V závěru práce jsou popsány výsledky vizuálních testů, které sloužili k porovnání predikčních schopností vybraných rovnic a vzájemnému porovnání shody jednotlivých pozorovatelů.