Search results for "Medium"

COMPUTATIONAL HOMOGENIZATION OF POLYCRYSTALLINE MATERIALS WITH PORES: A THREE-DIMENSIONAL GRAIN BOUNDARY FORMULATION

2012

In this study, the influence of porosity on the elastic effective properties of polycrystalline materials is investigated using a 3D grain boundary micro mechanical model. The volume fraction of pores, their size and distribution can be varied to better simulate the response of real porous materials. The formulation is built on a boundary integral representation of the elastic problem for the grains, which are modeled as 3D linearly elastic orthotropic domains with arbitrary spatial orientation. The artificial polycrystalline morphology is represented using 3D Voronoi Tessellations. The formulation is expressed in terms of intergranular fields, namely displacements and tractions that play …

Mediju (medium) dinamika Vidzemes reģionālo laikrakstu portālu kriminālziņās no 2018. gada 1.jūlija līdz 2019. gada 1. janvārim

2019

Maģistra darba “Mediju (medium) dinamika Vidzemes reģionālo laikrakstu portālu kriminālziņās no 2018. gada 1. jūlija līdz 2019. gada 1. janvārim” mērķis – izpētīt, kā reģionālo laikrakstu portāli vēsta kriminālziņas, raugoties no medium teorētiskās perspektīvas. Darba teorētiskais pamats balstīts mediju teorijās, kas aplūko konkrēti medium perspektīvu, kriminoloģijas un žurnālistikas teorijās, kas apraksta, kā tiek interpretēti kriminālie notikumi žurnālistikas un policijas jomās, un medijpratības teorijās, sniedzot pamatu tam, kā novērtēt policijas un žurnālistikas jomu speciālistu komunikācijas lietpratību no medium perspektīvas. Pētījuma metodoloģiju veido trīs datu vākšanas un analīzes …

Sponge‐Like Behaviour in Isoreticular Cu(Gly‐His‐X) Peptide‐Based Porous Materials

2015

We report two isoreticular 3D peptide-based porous frameworks formed by coordination of the tripeptides Gly-L-His-Gly and Gly-L-His-L-Lys to Cu(II) which display sponge-like behaviour. These porous materials undergo structural collapse upon evacuation that can be reversed by exposure to water vapour, which permits recovery of the original open channel structure. This is further confirmed by sorption studies that reveal that both solids exhibit selective sorption of H2 O while CO2 adsorption does not result in recovery of the original structures. We also show how the pendant aliphatic amine chains, present in the framework from the introduction of the lysine amino acid in the peptidic backbo…

“Coupling interfaces for communication transceivers over power lines”

2010

Coupling circuit for power line communications

2013

A coupling interface couples a transceiver to one or more capacitive voltage dividers of a power transmission system. The coupling interface includes a first signal path including an adjustable inductance configured to form a resonance circuit with a capacitance associated with the one or more capacitive voltage dividers. The coupling interface may include a second signal path including an adjustable inductance configured to form a resonance circuit with the capacitance associated with the one or more capacitive voltage dividers.

Model of line to shield power line communication system on a Medium Voltage network

2010

In this paper a complete model of a power line communication (PLC) system on a Medium Voltage (MV) network is presented in the case of a line-ground configuration. A simple and friendly Simulink (R) software is used to develop the model. A distributed parameter MV cable model in line-ground configuration is considered together with the power transformers, the signal coupling networks and the receiving and transmitting line coupling interface of a ST7540 FSK powerline transceiver. The performances of the complete PLC communication system are evaluated for different line lengths by means of the attenuation computed as ratio between the received and transmitted voltage signals.

Power Line Communication in Medium Voltage Systems: Characterization of MV Cables

2008

The aim of this paper is to illustrate the development of a theoretical and experimental study on the characterization of medium voltage (MV) cables in the frequency range 25-200 kHz. Two transmission line configurations, line-ground and line-line, were considered in order to evaluate the main parameters, such as the characteristic impedance and the attenuation constant alpha. A simplified model of the line-ground configuration is proposed which allows one to evaluate the characteristic impedance and the attenuation constant by means of geometrical dimensions. The model was verified by experimental measurements on commonly used MV cables, RG7H1R, with an aluminium core of different sections…

Simulation of a Power Line Communication System in Medium and Low Voltage Distribution Networks

2011

The aim of the paper is to study the influence of the power transformer on signal transmission in the case of a power line communication (PLC) system in a overhead Medium Voltage (MV) power network. A model of the PLC system was carried out by means of the Simulink® software. A distributed parameter MV overhead line, two power transformers, the signal coupling networks and the receiving and transmitting line coupling interface of a ST7540 FSK powerline transceiver were included in the model. The performances of the complete PLC communication system are evaluated for different line lengths by means of the attenuation computed as ratio between the received and transmitted voltage signals.

Comparison of Post-Weld Treatment of High-Strength Steel Welded Joints in Medium Cycle Fatigue

2010

This paper presents a comparison of three post-weld treatments for fatigue life improvement of welded joints. The objective is to determine the most suitable post-weld treatment for implementation in mass production of certain crane components manufactured from very high-strength steel. The processes investigated are: burr grinding, TIG dressing and ultrasonic impact treatment. The focus of this investigation is on the so-called medium cycle area, i.e. 10 000-500 000 cycles and very high stress ranges. In this area of fatigue design, the use of very high strength steel becomes necessary, since the stress range can exceed the yield-strength of ordinary structural steel, especially when consi…

Measurement of Low Concentration of Nanosized Objects Suspended in a Liquid Medium

2018

The new optical scheme of refractometer with temperature stabilisation 10-2 °C is developed, which allows measuring a refractive index of the sample with accuracy not worse than 10-5; dependence of refraction index on concentration of SiO2 nanoparticles in liquid suspension is obtained within the framework of the research.