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1.
High potential of sub-Mediterranean dry grasslands for sheep epizoochory
Mitja Kaligarič, Jožica Brecl, Sonja Škornik, 2016, original scientific article

Abstract: There is a general decline of grasslands across Europe due to habitat loss and degradation. Ensuring plant dispersal thus becomes a key process for preserving grassland patches in all scales. We examined diaspore dispersal by sheep epizoochory in the pastures of the North Adriatic Karst (NW Slovenia) and determined the qualitative and quantitative features of diaspores in fur. We recorded 25,650 diaspores of 141 plant taxa (with 107 taxa and 23,350 diaspores determined to species level), using three different methods: (i) the “whole-coat method”, (ii) the “part-of-thecoat method” and (iii) a “seedling emergence method”. A comparison of these techniques revealed that the “wholecoat method” provided the highest number of diaspores and plant species. All diaspores were clustered into five emergent groups based on seven functional traits (diaspore weight, length, width, height, volume, specific weight and the diaspore surface structure). Our research revealed that sheep represent an important dispersal vector, since about half of the plant species recorded in the pastures were found as diaspores in fur. This study contributes to knowledge about the modes of seed dispersal in seminatural grasslands. Taking into account that livestock play a key role in vegetation dynamics, understanding their effects on seed dispersal is essential for conservation and restoration of these species-rich grassland communities.
Keywords: community assembly, diaspore traits, plant dispersal, seedling emergence method, transhumance
Published: 03.04.2017; Views: 528; Downloads: 314
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2.
Position control with parameter adaptation for a nano-robotic cell
Gregor Škorc, Jure Čas, Simon Brezovnik, Riko Šafarič, 2011, original scientific article

Abstract: This paper describes the development of a nano-assembly system, built up using linear piezo motors. The so-called nano-robotic cell is based on an X/Y manipulator, supported by three serving tables, movable within a Z axis, and aposition controlled using two different types of a bang-bang control methods. The presented application has been developed as a stand-alone application with the LabVIEW Real Time software package, a PCI-7356 servo controller card and a TMCM-090 stepper driver. Our experiments focused on two major problems present during the construction of nano-robotic assembly cells. The first one is a nonlinear characteristic of a linear piezo motor, which makes the use of classical control methods very limited. The second problem appears when a nano-robotic cell needs a bigger working space and at the same time, production demands that the manipulator moves more often over longer distances. In order to position in nano-resolution, the motors have to run at higher resolutions with smaller speeds. Therefore, long distance moves slow down the entire production process. Experiments on this system have shown that positioning within the nano-scale is possible, using a simple control method such as the bang-bang control method. Although positioning using this method is possible, certain limitations and weaknesses exists, making this simple method useless in nano-scale if higher speeds and longer move distances are needed. Certain changes in the basic control algorithm are proposed, which will ensure that the bangbang control method becomes useful within higher speeds and over longer distances. All recommendations are supported and backed- up by practical experimental results.
Keywords: nanorobotske celice, nanopozicioniranje, histerezni krmilnik, proizvodnja MEMS, realno-časovni LabView, nano-robot cells, nano-positioning, bang-bang controller, MEMS assembly, LAbVIEW, real time
Published: 10.07.2015; Views: 926; Downloads: 107
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3.
Electrokinetic investigation of polyelectrolyte adsorption and multilayer formation on a polymer surface
Stefan Köstler, Volker Ribitsch, Karin Stana-Kleinschek, Georg Jakopic, Simona Strnad, 2005, original scientific article

Abstract: Self assembled polyelectrolyte layers of poly(sodium 4-styrenesulfonate) (PSS), and poly(diallyldimethylammonium chloride) (PDADMAC) were deposited on planar poly(ethylene terephthalate) (PET) substrates using the layer-by-layer technique. Charged functional groups were generated on the polymer substrates by means of a surface modification procedure prior to polyelectrolyte adsorption. The layers were characterised concerning their electrokinetic properties. The build-up of multilayer architectures could be followed by changes of the zeta-potential versus pH curves. An increase of coating density with increasing layer number was found. The electrokinetic properties of the PET substrates were not recognised anymore if more then four layers were applied. If PSS formed the outermost layer these assemblies were very stable against shear forces while if PDADMAC formed the outermost layer the films were partially destroyed by high shear forces.
Keywords: textile materials, polyelectrolyte multilayers, layer-by-layer assembly, zeta-potential, ellipsometry, polymer substrate, layer stability
Published: 01.06.2012; Views: 1659; Downloads: 65
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