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Evaluation of Analyte Vapour Diffusion in Polymer-Nanostructured Carbon Composite
No full textPreviously polymer-nanostructured carbon composite (PNCC) electrical resistance response, when the composite is exposed to different volatile organic compounds (VOC), has been investigated and determined. As PNCC electrical resistance change is a result of VOC molecule diffusion in the composite and subsequent swelling, then analyte diffusion behaviour evaluation is essentially important.
According to classical analyte diffusion theory into polymers, diffusion behaviour can vary from Fickian to non-Fickian type diffusion depending on the structure of the polymer (amorphous-rubbery, amorphous-glassy or crystalline). Diffusion type indirectly characterizes mobility of polymer segmental unit. Rapid PNCC response to VOC and fast electrical resistance recovery can be enabled by choosing polymer matrix with high segmental unit mobility. To determine analyte diffusion type into the composite and correlate diffusion characteristics with PNCC electrical resistance change, experimental setup has been build with possibility to register simultaneously the PNCC sample mass, length and electrical resistance change.
VOC diffusion characteristics (diffusion velocity and type) into the composite sample depending on used nanostructured filler material (carbon black nanoparticles or carbon nanotubes), filler content, matrix material structural state as well as type of analyte have been evaluated
Comparison of Lugers’ Start Elements on a Sliding Track and an Iced Start Ramp
No full textThe aim of this study was to determine whether there are significant differences in timing of start elements that lugers perform on a sliding track and an iced start ramp built for training purposes. Male and female lugers with different competitive experience performed starts on the start ramp and on the luge track. Timing of start elements was measured from high-speed video records and compared between start facilities. Most of the athletes showed different timing of start phases at the track and the ramp. These differences partially arise from a necessity to assume a riding position in-time on the track. Though training on the start ramp does not represent exactly start performance on a luge track, it is a convenient way for practicing technical elements of the start
Algorithm of Nodal Prices Determination for Inhomogeneous Networks
No full textIn paper using possibility of algorithm of nodal prices determination for inhomogeneous networks taking into account carrying capacity of the lines is considered. In this case, active power distribution is also affected by reactive power, respectively, it influence on nodal prices.
For illustration of the offered method, a specific EPS was used. The nodal prices determination algorithm for inhomogeneous EPS was offered. The results of experiments for a specific EPS model bears witness of validity of advanced theory. The offered method allows improving principle of concurrent energy market participants’ price bids introduction
Linear and Weakly Nonlinear Instability of Slightly Curved Shallow Mixing Layers
No full textThe paper is devoted to linear and weakly nonlinear stability analysis of shallow mixing layers. The
radius of curvature is assumed to be large. Linear stability problem is solved numerically using collocation
method based on Chebyshev polynomials. It is shown that for stably curved mixing layers curvature has a
stabilizing effect on the flow. Weakly nonlinear theory is used to derive an amplitude evolution equation for the
most unstable mode. It is shown that the evolution equation in this case is the Ginzburg-Landau equation with
complex coefficients. Explicit formulas for the calculation of the coefficients of the Ginzburg-Landau equation
are derived. Numerical algorithm for the computation of the coefficients is described in detail
ERP as a Tool For Sustainable Logistics Management
No full textIn recent years, consumers and governments have been pressing companies to reduce the environmental impact of their activities. This study aim is to investigate the most important tools and concepts of ERP systems that help in supply chain information sharing, cooperation and cost optimization to reduce the environmental impact of firm’s activity. Study summarizes the results of analysis based on literature review and case study. These results can be used to measure the potential monetary value of such issues, and minimize logistic system influence on environmental performance
Influence of Hydrogen Content and Sputtering Characteristics on the Properties of ZnO:Al Transparent Conductive Layers Deposited on Polymer Substrate
No full textZnO:Al layers were deposited on a 100 μm thick PET (polyethylene terephthalate) film by magnetron sputtering of a ZnO/Al2O3 2 wt.% planar ceramic target in an Ar/H2 atmosphere at (0.3-0.6) Pa pressure. RF (13.56 MHz), DC and pulsed DC power sources were used separately. The PET film was fixed on a rotating water-cooled drum. The investigation shows that the properties of ZnO layers depend mainly on the type of power source, the power level applied to the target and the concentration of hydrogen in the gas mixture. For all types of sources, the resistivity of the ZnO layers decreased when the sputtering power was reduced. Adding H2 to the Ar gas initially caused a relatively rapid decrease of the resistivity of the ZnO layers. The optimum concentrations of hydrogen in the gas mixture were approximately 1 vol. % and (10-12) vol. % for the RF- and DC-sources, respectively. Further increasing the hydrogen content in the gas mixture led to a slow increase of the resistivity. Unbalancing the magnetron allowed an additional reduction of the resistivity of the Al and H co-doped ZnO films. As a result, ZnO:Al layers with resistivities of 7.0 x 10-4 Ω.cm (RF-source) and 1.2 x 10-3 Ω.cm (DC-source) were obtained on the PET film . The best 350-400 nm thick layers had an optical transmittance of 82-83% for λ of 360-600 nm and a surface resistivity of 18-16 Ω/sq. The layers had a wurtzite structure, with the preferred c-axis orientation normal to the surface of the film. They were crack-free and had good adhesion to the substrate
Velocity Curves of Lugers` Starts Performed on Inced Start Ramps
No full textLugers` starts were analyzed in order to determine typical velocity curves that describe athletes` motion on the iced start ramp
Factors Infliencing Company’s Sustainable Performance: Case from Latvia
No full textThe operations and development of an enterprise as an economic entity depends on various factors, identification and evaluation of which is crucial for any enterprise. In the opinion of the authorsss the enterprise’s performance is influenced by factors which can be grouped into three blocks: macroeconomic factors, demand factors and structure of industry sector. The authorsss present the conceptual model of factors influencing enterprise's performances and analyze factors' interactions and manifestations of their impact. Besides, classification of factors according to the way of their manifestation, as well as according to the environment, which maintains or initiates influence of the factor are offered
The Concept Map Based Assessment System: Functional Capabilities, Evolution and Experimental Results
No full textThe paper is devoted to the concept map-based intelligent assessment system that promotes students’ knowledge self-assessment and supports teachers in improvement of study courses through systematic assessment and analysis of students’ knowledge on the basis of concept maps. During the last five years, both the system’s functionality and knowledge assessment approach were improved persistently, and at the moment, certain level of maturity is reached in both directions. The paper focuses on general principles of functioning of the last prototype, tasks provided, teachers’ and students’ support, scoring and adaptation mechanisms. At the end of the paper, retrospection of the system’s evolution and evaluation results is provided
Passengers Patterns Behavioural Issues Analysis in Decision Making of Sustainable Public Transport System Development
No full textThe quality of transport service is one of the parameters in the organising the sustainable transport system,
which is quite complex to be measured as well as to be improved, in comparison with such parameters like
time and price of tickets. However quality of transport service and passengers behaviour is one of the key
factors in transport system development and long term planning