Wrocław University of Technology

About: Wrocław University of Technology is a education organization based out in Wrocław, Poland. It is known for research contribution in the topics: Laser & Fuzzy logic. The organization has 13115 authors who have published 31279 publications receiving 338694 citations.

Measurement of the group dispersion of the fundamental mode of holey fiber by white-light spectral interferometry

Abstract: We present a new method for measuring the group dispersion of the fundamental mode of a holey fiber over a wide wavelength range by white-light interferometry employing a low-resolution spectrometer. The method utilizes an unbalanced Mach-Zehnder interferometer with a fiber under test placed in one arm and the other arm with adjustable path length. A series of spectral signals are recorded to measure the equalization wavelength as a function of the path length, or equivalently the group dispersion. We reveal that some of the spectral signals are due to the fundamental mode supported by the fiber and some are due to light guided by the outer cladding of the fiber. Knowing the group dispersion of the cladding made of pure silica, we measure the wavelength dependence of the group effective index of the fundamental mode of the holey fiber. Furthermore, using a full-vector finite element method, we model the group dispersion and demonstrate good agreement between experiment and theory.

Analysis of Neighbourhoods in Multi-layered Dynamic Social Networks

Abstract: Social networks existing among employees, customers or other types of users of various IT systems have become one of the research areas of growing importance. Data about people and their interactions that exist in social media, provides information about many different types of relationships within one network. Analysing this data one can obtain knowledge not only about the structure and characteristics of the network but it also enables to understand the semantic of human relations. Each social network consists of nodes – social entities and edges linking pairs of nodes. In regular, one-layered networks, two nodes – i.e. people are connected with a single edge whereas in the multi-layered social networks, there may be many links of different types for a pair of nodes. Most of the methods used for social network analysis (SNA) may be applied only to one-layered networks. Thus, some new structural measures for multi-layered social networks are proposed in the paper. This study focuses on definitio...

The role of Lewis acidic centers in stabilized zirconium dioxide

Abstract: The physico-chemical properties of ZrO 2 , MgO and admixtured (stabilized) zirconium dioxide are presented. The synthesis of stabilized ZrO 2 was conducted in a low-temperature process. The catalysts obtained on the basis of zirconium dioxide were monophase materials of a regular structure. The lattice parameter of the materials did not differ much from the standard value. The character of the surface active centers was being changed as a result of the admixturing. Synthesized monophase materials of catalytic properties, Zr-Mg-O and Zr-Mg-Y-O, have many strong Lewis centers at surfaces. There appeared not only the stabilization of the regular polymorphous structure of ZrO 2 , but also a modification of catalytic properties of the materials when the basic admixture (MgO and Y 2 O 3 ) was being introduced to basic zirconium dioxide. The authors present a mechanism of alcohol or aldehyde condensation to ketone at the surface of the materials with the participation of Lewis acidic centers.