In this work we wanted to determine how students of Graphic engineering and design perceived online learning a year after the transition from traditional to online classes. The goal was to better ...understand problems, challenges, and good sides of online learning in this study field, and determine factors that impede knowledge transfer. The students' responses were collected via an anonymous online survey, which consisted of a series of questions that covered: conditions in which online classes are attended, communication channels, problems and how they are dealt with, understanding and motivation. The biggest challenges for our students were to sustain their attention and concentration during classes despite the distractors in their environments, and to keep their motivation despite the lack of direct interaction, social isolation, and too much computer time. Their technological and digital literacy were of great use in adapting to the online platforms and applications, as well as in solving technical problems that prevented them from following the classes. Even though online courses allow students to be more flexible and potentially combine work and study, most of our students do not think that their attendance and engagement in the studies increased in the last period. It is also undisputed that our students were dealing with a lot of stress and anxiety and that their emotional state highly influenced their perception of online learning. Hence, we firmly believe that apart from making online courses more engaging and interactive, it is of utmost importance to find a proper way to motivate and psychologically support students in the online learning environment, especially in times that require a high degree of resilience.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
It is known that gloss has a significant impact on colour measurement. The UV varnish used for surface finishing, spot effects, as well as special effects, such as 3D effects and formation of ...Braille, has a pronounced gloss effect. In this work, a comparison of the spectrophotometer measurement geometry influence on the colour measurement of an unprinted PVC sample covered with UV varnish was done. UV varnish was applied successively in layers, and patches with different number of varnish layers, from 1 to 12, were formed. Two spectrophotometers with different measurement geometries were used for the measurement: Konica Minolta CM-2600d with d/8 measurement geometry, with spectral reflection included and excluded, and different measurement aperture 3 and 8 mm, and X-Rite eXact with 45/0 measurement geometry. By comparing the measurements, it was estab-lished that there is a significant difference in the measured values between different measuring device geometries on the given samples, and that the number of UV varnish layers has a significant influence on this differenc
A new colorimetric method for determining the color of a printed sample using electrophotography is presented. As a trade-off solution between colorimeter and spectrophotometer, this method aims to ...increase accuracy with respect to the colorimeter and simplify the system with respect to the spectrophotometer. The method is based on estimation of the spectrum of electromagnetic radiation in the visible range. This was performed by interpolating over the measured values of the spectral power radiation of proposed LED sources. Six LED sources were used, with dominant wavelengths at 400 nm, 457 nm, 517 nm, 572 nm, 632 nm and 700 nm at the transmitting side. On the receiving side there is a wideband detector in charge of recording the optical power at the above-mentioned wavelengths. Colorimetric capabilities of the proposed method were compared with spectrophotometric results, and good match was achieved. Reflectance spectrums obtained by the proposed method for printed samples doesn’t deviate significantly from those recorded by a commercial spectrophotometer. Also, the calculations of color differences don’t deviate from the tolerance threshold.
The paper presents research related to thermochromic inks printed on textile materials. These types of materials are smart materials, they act as packaging indicators, and we use them to develop a ...software application on mobile devices. That application identifies the most significant changes in parameters of the goods contained in the packaging, such as temperature changes during the storage and transport (goods packaged in packaging that is sensitive to heat), or such as pharmaceuticals and frozen food, etc. This paper aims to demonstrate the possibility of connecting thermochromic materials and Augmented Reality technology through the development of an application for identifying thermochromic materials changes. The tested samples were printed on the textile with a screen printing technique with conventional and thermochromic leuco inks on various textile materials. The Augmented Reality platform Vuforia was used for developing a software application for mobile devices. The application was developed for the iOS mobile platform. The result of the research is the functional application that actively monitors and displays changes in thermochromic materials due to temperature changes, which identifies the effect of heat on the goods in textile packaging.
The paper presents the distance learning concept development by visualizing the work process of graphics machines. The basic goal is realized through the application development that includes ...machines simulations and their elements. A large number of simulations and explanations of the work process are included in the knowledge base. The concept is expanded to learning how to program machines so that the future operator can master significant knowledge that will enable him to engage in the production process quickly. The paper presents concrete types of machines for different printing techniques and machines for making packaging prototypes. For the realization of objects visualizations, modern software tools were used, which finally provided good quality.
From its beginnings, up to a few years ago, additive manufacturing technology was able to produce models or prototypes which have limited use, because of materials mechanical properties. With ...advancement and invention of new materials, this is changing. Now, it is possible to create 3D prints that can be used as final products or functional tools, using technology and materials with low environmental impact. The goal of this study was to examine opportunities for production of paper embossing tools by fused deposition modelling (FDM) 3D printing. This study emphasises the use of environmentally friendly poly-lactic acid (PLA) materials in FDM technology, contrary to the conventional method using metal alloys and acids. Embossing of line elements and letters using 3D printed embossing tools was done on six different types of paper. Embossing force was applied using SHIMADZU EZ-LX Compact Tabletop Testing Machine. Each type of paper was repeatedly embossed using different values of embossing force (in 250 N increments, starting at 1000 N) to determine the optimal embossing force for each specific paper type. When determined, the optimal embossing force was used on ten samples for each paper type. Results of embossing were analysed and evaluated. The analysis consisted of investigating the effects of the applied embossing force and characteristics such as paper basis weight, paper structure, surface characteristic and fibre direction of the paper. Results show that paper characteristics determine the embossing force required for achieving a good embossing result. This means that with the right amount of embossing force, letters and borderlines can be equally well formed by the embossing process regardless of paper weight, surface characteristics, etc. Embossing tools produced in this manner can be used in case of the embossing elements that are not complex. The reason for this is the limitation of FDM technology and lack of precision needed for fine details. However, if the form is simple enough, results of pleasing quality can easily be achieved.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Manufacturing of the embossing tools customary implies use of metals such as zinc, magnesium, copper, and brass. In the case of short run lengths, a conventional manufacturing process and the ...material itself represent a significant cost, not only in the terms of material costs and the need for using complex technological systems which are necessary for their production, but also in the terms of the production time. Alternatively, 3D printing can be used for manufacturing similar embossing tools with major savings in production time and costs. However, due to properties of materials used in the 3D printing technology, expected results of embossing by 3D printed tools cannot be identical to metal ones. This problem is emphasized in the case of long run lengths and high accuracy requirement for embossed elements. The objective of this paper is primarily focused on investigating the influence of the printing speed on reproduction quality of the embossing tools printed with FDM (Fused Deposition Modelling) technology. The obtained results confirmed that printing speed as a process parameter affects the reproduction quality of the embossing tools printed with FDM technology: in the case of deposition rate of 90 mm/s was noted the poorest dimensional accuracy in relation to the 3D model, which is more emphasised in case of circular and square elements. Elements printed with the highest printing speed have a greater dimensional accuracy, but with evident cracks on the surface.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This study presents statistical evaluation of the dot area and line width on thermally developed CtP flexo printing plates using image analysis software PerfectEye v4.03. The aim of the study was to ...determine whether the dot area and line width when different processing parameters are applied (different main exposure time and different number of rotations of developing drum during developing process) were statistically different from each other or not. Image analysis of dots and lines were performed with a VipTronic Vipdens measuring device using CCD camera and a PerfectEye image analysis software. The shape data, dot area and line width were compared by applying one way ANOVA (analysis of variance) method followed by post hoc Tukey's test using the software SPSS (Statistical Package for Social Science) and independent sample T-test with a 0.05 significance level. Statistical analysis revealed that the difference between the dot area and line width for different processing conditions are significant with a 95% confidence level.
This paper reports the impact of screen-printed PEDOT:PSS conductive ink on the optical properties of polyester fabric and colourimetric properties of yellow screen printing ink printed in a ...different number of layers. Yellow was chosen as one of four process colours which should theoretically suffer the most prominent changes from PEDOT:PSS overprinting. The study found that PEDOT:PSS ink significantly impacts the optical properties of the fabric and yellow ink, especially regarding the lightness and b-coordinate of the yellow ink. The acid treatment of samples, to increase PEDOT:PSS conductivity, also affected the optical characteristics through partial neutralization of the changes in the b-coordinate, especially when the sample was printed with a larger number of layers of the yellow ink and a smaller number of layers of PEDOT:PSS ink. Samples with two layers of yellow and one layer of PEDOT:PSS ink showed good conductivity results even without acid treatment, while the base colour appeared slightly darker. This change in the lightness can be compensated to some extent, proving that the aforementioned combination of PEDOT:PSS and base ink layers are the best when aspects, such as optical characteristics, conductivity, the complexity of production, production time, and limitations of the use of substrate materials are taken into account. This study provides useful insights for optimizing the printing process of PEDOT:PSS conductive inks over screen printed fabrics for various applications, including wearable electronics and smart textiles.
A machine learning-based application for estimating a reflected electromagnetic spectrum is presented in this article. Since the results of the spectrum estimation by our previously implemented cubic ...Hermite interpolation method had some drawbacks, and in line with the increasing application of machine learning in sensor technology, the new hypothesis is put forward, based on the assumption that better predictions could be achieved by introducing artificial neural networks. The input data of such networks consist of six measured values, which represent the intensities of reflected light at specific wavelengths, while the output is formed out of 36 points, which are used to predict the shape of the spectral curve in the range of 380-730 nm (to obtain a resolution of 10 nm). Colorimetric capabilities of the proposed method are compared with a commercial spectrophotometer and with our previously obtained results using the cubic Hermite interpolation. The machine learning-based method has proven to be an intelligent solution for the spectrum estimation, and the drawbacks from the previously used method were reduced significantly.
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