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The research focuses on the quality of colour reproduction when using different light sources, often used toilluminate scenes in a photo studio, and different types of fabrics as lighting shapers. With the latter, the lightcan be converted into softer and more diffuse light, but the properties of the fabrics used affect the colourimpression and thus the quality of the reproduced colours. This was evaluated by analysing the colour differences which were calculated from the colorimetric values of the colour patches of the X-Rite ColorCheckerPassport test chart. Test chart was photographed in a controlled environment and illuminated with differentcombinations of light sources and tested fabrics. The results confirmed that not all combinations of variablesare suitable for use if the goal of the photograph is to achieve high quality colour reproduction.

The spread of invasive alien plant species (IAPS) is a leading reason for worldwide environmental change due to their effects on biodiversity and humans. Some valued goods from IAPS have been produced, e.g. paper that consists of cellulose fibres from Japanese knotweed. Therefore, the aim of this study was to establish the usability of this paper grade as a printing substrate, since it does not have ideal optical properties as it is expected from commercial office paper. Because it is widely used, inkjet printing technology was employed. Print permanence is essential, especially when printing documents. However, typographic characteristics must be considered to make a text more legible. Two widely used typefaces (Arial and Times) were tested in three commonly used type sizes (8 pt, 10 pt, and 12 pt). The results showed that the paper made from Japanese knotweed could have valuable properties and suitable legibility, especially when using typefaces with a moderate counter size, high x-height, and minimal differences in the letter stroke width to obtain an appropriate typographic tonal density with an adequate type size. Even after exposure to light, the texts printed in a proper type size and stroke width remained visible.

Invasive alien plant species (IAPS) are one of the biggest challenges in European ecosystems, displacing local vegetation, destroying agricultural land, and causing billions of dollars of damage to the European economy every year. Many of them are removed daily and mainly burned. In this work, we investigated the possibilities of using plants as feedstock for paper production. Papers made from three invasive alien plants, i.e., Knotweed, Goldenrod, and Black locust, were studied and compared with commercial office paper. The study included testing of: (1) structural properties—basic physical properties, grammage, thickness, density and specific volume, moisture content, and ash content, (2) physical and dynamic mechanical properties—tensile strength, Clark stiffness, viscoelastic properties, (3) colorimetric properties of prints, (4) effect of UV light on ageing, and (5) study of cellulose fiber structure and morphology by microscopy. The results suggested that the paper produced can be used as commercial office paper, considering that the paper is slightly dyed. Such papers can also be used for special purposes that present a natural style and connection to nature. The papers produced can also be used for printing documents that are meant to be kept.

Tension in the yarn and its oscillations during the over-end unwinding of the yarn from stationary packages depend on the unwinding speed, the shape and the winding type of the package, the air drag coefficient, and also the coefficient of friction between the yarn and the package. The yarn does not leave the surface package immediately at the unwinding point. Instead, it first slides on the surface and then lifts off to form the balloon. The problem of simulating the unwinding process can be split into two smaller subproblems: the first task is to describe the motion of the yarn in the balloon; the second one is to solve the sliding motion. In spite of the seemingly complex form of the equations, they can be partially analytically solved as we show in the paper.

We study the motion of yarn modelled as a one-dimensional inelastic string. In textile production, the yarn is being withdrawn from cross-wound packages in warping and weft insertion. During unwinding, there appear forces in the yarn that are approximately proportional to the square of the unwinding velocity. The yarn tension is not constant, but it oscillates within some interval. This is especially noticeable in over-end unwinding from a static cross-wound package. Even when the yarn is not strongly stressed, so that the tension never exceeds a few percent of the breaking strength, the yarn can still break sometimes. The production process requires as large warping and weaving speeds as possible; therefore, it is necessary to improve our understanding of the cross-wound package unwinding and to find the necessary modifications of the yarn unwinding process. In addition to empirical tests, it has proved useful to study yarn unwinding by mathematical modelling and computer simulations. We state the equati...

Mathematical modeling can be used to simulate the unwinding of yarn from packages of different shapes. This method can be applied to design packages that can sustain high unwinding velocities at low and steady tension in the yarn. In the case of conic packages the angular velocity of unwinding depends not only on the winding angle as is the case for cylindric packages, but also on the apex angle. We will show that the dimensionless angular velocity depends very little on the apex angle. The apex angle, however, also determines the effective radius of the package at the lift-off point, therefore the angular velocity can be proportionally higher. We will compare unwinding from a cylindrical and a conic package with equal smallest radius and show that unwinding from the conic package is faster due to higher average radius of the package at the lift-off point.

EXTENDED ABSTRACT:The paper has always been and it remains to be the primary information carrier though only 0.1 % of the total information is recorded on this media. The paper production industry has a great impact on the environment which is mostly due to the use of raw materials (wood of conifers and deciduous trees), fillers (CaCO 3), additional materials (dyes, glue, binders, retentionaids), and chemicals (acids and bases). However, the greatest impact on the environmentis caused by the extensive water consumption. To produce 1 ton of paper up to 60 m3 of freshwater are necessary. The water is not the only resource needed in the production cycle. Besides, the consumption of electrical energy (approximately 10,000 MJ/t pap), waste paper (paper represents 35 % of waste), and air pollution (paper production and transport) should be taken into consideration. In spite of the above mentioned environmental threats the paper still remains an important element of the everyday life and the use of modern information technology (personal computers, telefax, Internet) has increased its demand and consumption. It is important that the paper is produced from natural materials which are later released into environment without significant environmental consequences. The technology of paper recycling and re-use is widely known and a must of any responsible and professional social environment. Digitisation has increased the consumption of electrical energy as a consequence of production, use and reprocessing of different devices. Unlike a written record, a digital record has no permanent value and the electromagnetic field has a negative effect on the digital records. Digital records have to be constantly updated and adjusted to the computer software and hardware. A book and its content represent a treasure and an invaluable part of the cultural heritage. To use a book it is necessary to learn the alphabet whereas to read digital records we need to be computer and information literate. Negative effects of digitisation have affected the production of paper as the demand for graphic paper (newsprint, writing, printing paper) has decreased. The demand for raw materials, products and semi-manufactured products has decreased, too. Consequently, the level of investments in modernisation of equipment and in new production lines has been equally reduced. The proportion of employees directly or indirectly involved in the paper making and paper processing industry has been diminished. In the European Union paper and paper processing industry employ 1.9 million people in 200,000 enterprises representing 6.5 % of turnover in the production sector or 80 billion EUR or 16 billion EUR of the value added per year. The EU is expected to prevent the decline of paper and paper related industry (graphic, construction, logistic) which would endanger the production – consumption cycle. After all, dismissals can ruin the social equilibrium. However, the paper production is faced with a difficult situation caused by digitisation. The competitiveness of the global market has an impact on the labour force costs, raw materials and energy products. Besides, production costs within the European Union are not competitive because of the EU Regulations and Directives which affect the price of raw materials, semi products and energy products. All these facts led to the decrease of workforce and the loss of market leading position and competitiveness.

"The phenomenon of paper coating cracking when folded was studied. Coating mixtures were compared according to their composition, applied on different base paper, to find which combinations of the constituents of the base paper and the paper coating results in a lower tendency towards fold cracking of the coating layer. It was shown that the appropriate selection of pigments (calcium carbonate, kaolin) and binders (starch, latex), whose elastic behavior extensively influences the deformation of paper under physical and mechanical stress, is of central importance. The choice of the base paper plays a significant role as well, it should have the longest and the most numerous cellulose fibers possible in order to avoid fiber breaks and inter- and intra-fiber connections. The content of inorganic substances has the greatest negative effect on deteriorating the physical-mechanical properties of the studied label papers, leading to the deposition of inorganic substances at the joints between the cellulose fibers and reducing their bonding."