Browsing by Author "Zemanová, Monika"

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    Analýza materiálových toků ve výrobním družstvu
    (2004-01-01) Zemanová, Monika
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    Partial discharges of nonwoven nanofibers composite
    (University of West Bohemia, Faculty of Electrical Engineering, Regional Innovation Centre for Electrical Engineering, Univerzitní 8, Pilsen, Czech Republic; Technical University of Liberec, Department of Machinery Construction, Laboratory of Nanofiber and Nanosurface Preparation, Studentská 1402/2, Liberec, Czech Republic, 2016-01-01) Pihera, Josef; Polanský, Radek; Zemanová, Monika; Prosr, Pavel; Chvojka, Jiří
    A promising technology of nanofibrous composites is studied nowadays as an alternative method to the well-known dielectric nanocomposites filled by various nanofillers like a metallic oxides, alumina, silica, carbon nanofibers or nanotubes. All of these nanofillers are known, more or less. The use is to improve some of the electrical, mechanical and thermal properties of nanocomposites. Unfortunately, its expensiveness and tendency to agglomeration remain as their main disadvantage. In the contrary, the nanofibers can be applied as a nonwoven fabric over the surface of the composite with no tendency to create the cluster agglomeration as the nanocomposites with nanoparticles. It was prepared experimental specimens of nonwoven nanofibers composites based on the modification of commonly used three-component mica-based electrical insulating material (epoxy, glass fibers and mica). The modification of these, well known, mica composites was done by incorporation of the nonwoven nanofibers layers (1, 2 and 3) to its structure always with different area density (1, 3 and 5 g/m2) of the nanofibers. The tested material was delivered in the form of resin-rich sheets on which the layers of the nanofibers made from Polyamide 6 were applied and specimens were subsequently cured using typical resin rich curing process. The influence of prepared modifications on the partial discharge characteristics and magnitudes of the resulting nanocomposites was studied. Partial discharges results show differences between the specimens' variations depending on nanofibers presence, the number of layers and surface density of nanofibers. The decreasing of the partial discharge activity is recognisable when the nanofabrics is incorporated into the composite. The obtained results proved that the nonwoven nanofibers based on Polyamide 6 seem to be a perspective material with certain resistance to partial discharge activity. © 2016 IEEE.
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    Řízení jakosti v podniku
    (Technická Univerzita v Liberci, 2006-01-01) Zemanová, Monika; Lubina, Jiří
    Building up of system of quality management is necessary in every sucessful company and it is concentred in every sphere of business, planning, production, supervision and economy. Severity of building up depends on level of actual system of management. In following period of maintaining and improving the analysis are compiled and records are evaluated. The object is to acquire the proof about function of system and also to acquire items for improving and for making decision. This analysis is done in Mona Styl, s.r.o., Jaroměř. It describes possibilities of uprising scrap. The object are headrests and it is done by Paret analysis. After the analyse has been done, the defects are explored and the improvement is designed. The improvements are compared with previous situation then.
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    Řízení jakosti v podniku
    (2006-01-01) Zemanová, Monika
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    The usage of nonwoven nanofibers for improving properties of electrical insulation
    (University of West Bohemia, Faculty of Electrical Engineering, Regional Innovation Centre for Electrical Engineering, Univerzitní 8, Pilsen, Czech Republic; University of West Bohemia, Faculty of Electrical Engineering, Department of Technologies and Measurement, Univerzitní 8, Pilsen, Czech Republic; Technical University of Liberec, Department of Machinery Construction, Laboratory of Nanofiber and Nanosurface Preparation, Studentská 1402/2, Liberec, Czech Republic, 2016-01-01) Polanský, Radek; Prosr, Pavel; Pihera, Josef; Džugan, Tomáš; Zemanová, Monika; Chvojka, Jiří
    The nonwovens and nanofibers as a new material for possible improving properties of electrical insulation are introduced in this paper. Nanofibers were used to modify a commonly used two-component like mica-based high voltage electrical insulating material. The tested material in the form of resin-rich sheets was modified using a various number of layers (1, 2 and 3) of the nanofibers made from Polyamide 6 (PA6) in the various surface densities (1, 2 and 3 g·m-2). Specimens were manufactured at increased temperature and pressure. The volume resistivity, voltage dependence of dissipation factor and mechanical properties were tested. The structure of the nanofibers was examined by scanning electron microscopy (SEM), the manufactured composites were analyzed under optical microscopy. Obtained results showed that composites with layers of nonwoven nanofibers are characterized by lower values of dissipation factor at electric field intensity greater than 5 kV/mm when the partial discharge activity starts to occur. Mechanical tests showed that while the Young's modulus of the modified composites notably increased (of about 27 - 43.5 %), flexural strength stayed on the same values as unmodified composites. © 2016 IEEE.