Boron carbide morphology changing under purification

Boron carbide synthesized by using coaxial magnetoplasma accelerator with graphite electrodes was purified by two different ways. XRD-investigations showed content changing and respectively powder purification. Moreover TEM-investigations demonstrated morphology changing of product under purification that was discussed in the work

Practical Results of a Five-level Flying Capacitor Inverter

This paper investigates the realization of a five-level Flying Capacitor Inverter. After a brief description of general Power Electronic Converters and an introduction to the advantages of Multilevel Inverters over conventional two-level Inverters the main focus is on the five-level Flying Capacitor Inverter. The Flying Capacitor Multilevel Inverter (FCMI) is a Multilevel Inverter (MI) where the capacitor voltage can be balanced using only a control strategy for any number of levels. After a general description of five-level FCMI topology, the simulation and experimental results are presented. The capacitor voltage is stabilized here with various output voltage amplitude values. The simulation and experimental results of five-level FCMI show that the voltage is stabilized on capacitors using the control strategy. A single-phase five-level FCMI model is currently being developed and constructed in the laboratory. Some of the experimental results are available

The plasma dynamic synthesis of aluminum nitride in system with gaseous and solid precursors

Aluminum nitride is widely-used material for semiconductor devices and ceramics production. Despite the large number of known ways to obtain AlN powder, the problem of synthesizing high-purity and nanosized product is still urgent. This paper shows results on plasma dynamic synthesis of aluminum nitride using system based coaxial magneto plasma accelerator. The influence of using gaseous or solid precursors on such characteristics of the final product as phase content and particle size distribution was investigated. According to X-Ray diffractometry AlN phase content is increased in the case of use of solid nitrogen-containing precursor (melamine) in comparison with the use of gaseous nitrogen. The particle sizes distribution histograms are built in accordance with the data of bright-field TEM-images and shown in this paper. The most of particles are less than 100 nm in both experiment but there are some differences, depended on the precursor type, that are also described

Development of Urban Electric Bus Drivetrain

The development of the drivetrain for a new series of urban electric buses is presented in the paper. The traction and design properties of several drive variants are compared. The efficiency of the drive was tested using simulation calculations of the vehicle rides based on data from real bus lines in Prague. The results of the design work and simulation calculations are presented in the paper

Boron carbide morphology changing under purification

Boron carbide synthesized by using coaxial magnetoplasma accelerator with graphite electrodes was purified by two different ways. XRD-investigations showed content changing and respectively powder purification. Moreover TEM-investigations demonstrated morphology changing of product under purification that was discussed in the work

On the impact of the plasma jet energy on the product of plasmadynamic synthesis in the Si-C system

Silicon carbide (SiC) nanoparticles can be used for ceramics reinforcement, creation of nanostructured ceramics, microelectromechanical systems. The paper presents the results of plasmadynamic synthesis of silicon carbide nanopowders. This method was realized by the synthesis in an electrodischarge plasma jet generated by a high-current pulsed coaxial magnetoplasma accelerator. Powdered carbon and silicon were used as precursors for the reaction. Four experiments with different energy levels (from 10.0 to 30.0 kJ) were carried out. The synthesized products were analysed by several modern techniques including X-ray diffractometry, scanning and transmission electron microscopy. According to analysis results all the products mainly composed of cubic silicon carbide (b-SiC) with a small amount of unreacted precursors. Silicon carbide particles have a clear crystal structure, a triangular shape and sizes to a few hundred nanometers. Comparison of the results of experiments with different energy levels made it possible to draw conclusions on ways to control product phase composition and dispersion. The silicon carbide content and particles sizes increase with increasing the energy level

Methods for quantitative assessment of femoral antroposcopic landmarks using hand-held laser scanner

Purpose : This study is focused on an innovative approach to the numerical assessment of gluteal tuberosity through 3D visualization and its use as sex discriminant.Materials and methods : The study was based on an aggregate of 40 right femora, male and female in equal proportion. The surface of tuberositas glutea femoris is captured in a 3D image, using a Hand-held Laser Scanner (FastSCAN). Afterwards, the assessment contains three ways. Firstly, the result is a 3D shape comprising two tetrahedrons with common base. Therefore, the volume of the roughness is approximately equal to the total of the volumes of these two tetrahedrons (volume). Secondly, several points /markers/ are placed on the surface of the roughness of the 3D image. After that we create two-dimensional shape which is a function of the three-dimensional one. The area of the formed shape is measured (area) as well as its greatest elevation (elevation). Thirdly, we assess the position angle of gluteal tuberosity (angle C). The results were processed with SPSS 17.0 using Discriminant Function Analysis.Results : If the predictors (volume, area, elevation and angle) are included in the model, than the percentage of cases classified correctly is 95%.Conclusion : This score coincides with world results based on various anthropometric indices of the femur