Analysis of the uniform magnetic field free-electron laser with scalarized photons in the microwave-spectral region

The recently developed concept of scalarized photons (formally photons of any polarization) is used to analyze the spontaneous and stimulated emission in the uniform magnetic field free-electron laser in the microwave spectral region. In fact, this free-electron laser is the simplest of many other, wiggler and wiggler-free free-electron lasers whose analyses could be done with scalarized photons in the small signal regime and whose physical parameters can be conveniently chosen for radiation to be generated in the microwave spectral region. As to the uniform magnetic field free-electron laser, which is treated here in some detail, with the electron beam energy of up to 10 MeV and the uniform magnetic field of up to 4 Tesla, the radiation (occurring with the fundamental and higher harmonic frequencies) can cover easily a 10 to 10,000 GHz spectral region.     

Structural Steel ASTM A709—Behavior at Uniaxial Tests Conducted at Lowered and Elevated Temperatures, Short-Time Creep Response, and Fracture Toughness Calculation

This paper presents the temperature dependence of the mechanical properties of structural high-strength low-alloy (HSLA) ASTM A709 Gr50 steel (En10025: S355 JO; DIN: ST 52-3U). Engineering stress-strain diagrams at lowered and elevated temperatures are presented. Creep responses for selected constant stresses at selected temperatures are also presented and are fit with a rheological model. Additionally, a relation between impact toughness and fracture toughness is proposed and is validated using results from notch impact tests on a Charpy pendulum impact machine.     

On gas bubbles in industrial aluminium cells with prebaked anodes and their influence on the current distribution

The secondary current distribution in industrial aluminium cells with prebaked anodes was calculated, taking into account the gas bubbles. The input data were obtained on the basis of a physical model and data suggested in the literature. The bubbles were modelled in the following manner: (i) as very small bubbles dispersed in a homogeneous layer with higher electrical resistivity than the bulk of the electrolyte, (ii) as large bubbles modelled as discrete slabs with infinite resistivity, and (iii) as a combination of (i) and (ii). The bubble size and the number of bubbles, as well as the resistance of the homogeneous bubble layer, were varied to give an equivalent voltage drop in the range 0.1–0.4 V. Large bubbles (slabs) appeared to have a significant screening effect on the anodic current densities. The anodic current densities between slabs showed local maxima, sometimes reaching twice the value of the working current density (0.75 A cm^–2). The cathodic current densities had local minima underneath the large anodic bubbles, following their position at the anode. Underneath a bubble of 6.1 cm width, the cathodic current density decreased from 0.75 to 0.23 A cm^–2.     

On some qualitative properties for solutions of a certain two-dimensional fractional differential systems

By means of the modification of Medve?’s de-singular method and a result of two-dimensional linear integral inequalities, components-wise (not on some norm) upper bounds are obtained for solutions of a class of nonlinear two-dimensional systems of fractional differential equations. The uniqueness and continuous dependence of the solutions are also discussed here.     

Removal of antimicrobials using advanced wastewater treatment

Removal of numerous classes of pharmaceuticals from the municipal and industrial wastewater, using conventional wastewater treatment, is incomplete and several studies suggested that improvement of this situation would require the application of advanced treatment techniques. This is particularly important for the treatment of industrial effluents, released from pharmaceutical industries, which can contain rather high concentrations of antimicrobials. The aim of this work was to evaluate membrane bioreactors (MBRs), nanofiltration, reverse osmosis and ozonation, as well as their combinations, for the removal of antimicrobials from a synthetic wastewater which simulated highly contaminated industrial effluents. The study was performed using a mixture of four important classes of antimicrobials, including sulfonamides (SA), fluoroquinolones (FQ), macrolides (MAC) and trimethoprim (TMP). Performance of two different types of MBRs, Kubota and Zenon, was evaluated under different regimes regarding hydraulic retention time, total organic load and total nitrogen load. It was shown that elimination of SA in MBR treatment was very efficient, while the elimination of MAC, FQ, and TMP was incomplete. A mass balance of these contaminants in MBR suggested that microbial transformation represented the main mechanism, while only a small percentage was eliminated from the aqueous phase by adsorption onto sludge particles. Nanofiltration and reverse osmosis achieved high elimination rates however produced highly contaminated concentrate. High removal was achieved using ozonation, but further research is needed to characterize formed ozonation products.     

Scenario based techno-business analysis of service platforms and their service portfolios

This work focuses on techno-business analysis of service platforms and service portfolios. Service platform (SP) hosts services and enabling service functionality. Service providers deliver two main products: end-user services to their customers and enablers to other business actors. 3rd party service providers combine enablers with their own functionality, wrap them in end-user services and deliver them to their customers.