Synchrotron-based X-ray tomographic microscopy is an ideal technique for studying the formation of materials at elevated temperatures. To exploit the state-of-the-art capabilities at the tomographic microscopy and coherent radiology experiments (TOMCAT) beam line of the Swiss Light Source has been developed. Powered by two diode lasers, it provides controlled localized heating to examine materials and their dynamics in real time. This paper details the experimental set-up and provides multiple proofs-of-concept for ultra-fast data acquisition that illustrate the versatility of using this laser-based heating system to explore in situ many elevated temperature phenomena in a variety of materials.
COBISS.SI-ID: 21280998
Wireless optical communication is viable technology for high data rate communication links between optical ground stations and satellites. However, clouds offer significant attenuation and from time to time even complete blockage of the link. The hybrid network of optical and radio frequency links is proposed to improve network availability. In this paper, the performance of communication system at different optical wavelengths has been analysed under different weather conditions. The Mie scattering approach, as well as visibility approach was used. Different cloud-specific attenuation analysis has been performed for different RF bands in satellite communications.
COBISS.SI-ID: 25872679
Radio signal propagation prediction plays an essential role in planning of modern broadband mobile radio networks. While less accurate statistical models predict only path loss, more precise ray tracing techniques enable also computation of mean delay and delay spread, which are significant for the 4G network planning. In this paper, an open-source solution for propagation prediction with a ray tracing method in the open urban and rural areas is presented. A computationally efficient procedure is implemented, which combines tessellation and improved shooting and bouncing ray approach. Simulation results show that by applying a tessellation optimization technique the processing time is reduced by half.
COBISS.SI-ID: 26354215
A set of simulations at various frequencies was performed for tunnels with standard cross-sectional shapes, dimensions, material properties and in addition with presence of obstacles preventing radio wave propagation along tunnel. We found out that the signal frequency and dimension of the tunnel cross section have considerable impact on path loss, while the tunnel cross shape and the transmitter and receiver position have only a marginal impact. The results were evaluated by four-slope empirical path loss simulation model and compared with measurements, performed in two different tunnels. The comparison of simulation results and measurements confirmed the adequacy of the simulation model for performing the path loss calculation and communication range determination in different tunnels and corridors.
COBISS.SI-ID: 25990439
New aspect of Cooperative and distributed communication systems, which represent an important shift of the classical historic role of the physical layer functionality is given in this scientific contribution. Traditionally, the physical layer is viewed in a point-to-point communication perspective. All communication tasks related to the information transfer in a more complicated multiple-source and multiple-node network were delegated to upper layers. Cooperative and distributed systems can be viewed as the physical layer coding and processing algorithms aware and actively utilizing the knowledge of the network topology. It was shown that even the simplest bidirectional relay communication scenario brings a substantial throughput improvement.
COBISS.SI-ID: 25954599