Fault tolerant motor drive system with redundancy for critical applications

Some of the recent research activities in the area of electric motor drives for critical applications (such as aerospace and nuclear power plants) are focused on looking at various motor and drive topologies. This paper presents a motor drive system, which provides an inverter topology for three-phase motors, and also proposes an increased redundancy. The paper develops a simulation model for the complete drive system including synthetic faults. In addition, the hardware details including the implementation of DSP based motor controller, inverter module, and brushless PM motor system are provided and some experimental results are presented.N. Ertugrul, W. Soong, G. Dostal and D. Saxo

The minimum wage in Germany: what brought the state in?

A statutory minimum wage has been introduced in Germany, in the face of business opposition but abetted by union support. The political coalition in favour of minimum wage regulation brought together the centre-left and the centre-right with the argument that regulation is needed to prevent disfunctional interaction between low wages and the social security system. Thus the dualization which characterises Germany’s inegalitarian form of coordinated capitalism has provoked a corrective political response. The paper traces the long path to government intervention and assesses why employers were unable, or unwilling, to pre-empt intervention by maintaining the coverage of collective bargaining. It is argued that market liberalization has had a paradoxical effect on employer power: intense domestic as well as international competition has reduced employers’ capacity to act strategically to fend off regulation by the government

Evidence of silicate immiscibility within flood basalts from the Central Atlantic Magmatic Province

Publisher's Version/PDFThe role silicate-liquid immiscibility plays in the formation of macro-scale, bimodal volcanic/plutonic igneous complexes, and Fe-Ti oxide deposits is debated as the rock compositions produced by immiscibility are similar to those produced by other petrological processes. Within the flows of the North Mountain basalt of the Central Atlantic Magmatic Province are centimeter-thick granophyre layers. The granophyre layers are a mixture of mafic (i.e., ilmenite, magnetite, ferroaugite, plagioclase, stilpnomelane, ferrorichterite) and felsic (i.e., sanidine, quartz) minerals and highly siliceous (>75 wt% SiO[subscript 2]) mesostases. Petrological modeling indicates that the siliceous mesostasis + sanidine + quartz [plus or minus] ferrorichterite represents a Si-rich silicate immiscible melt whereas the ferroaugite + plagioclase + stilpnomelane represent the Fe-rich silicate immiscible liquid. The identification of naturally occurring silicate-liquid immiscibility at scales greater than micron level is an important observation which may be useful in identifying volcanic and plutonic rocks which formed by macro-scale silicate-liquid immiscibility.The role silicate-liquid immiscibility plays in the formation of macro-scale, bimodal volcanic/plutonicigneous complexes, and Fe-Ti oxide deposits is debated as the rock compositions produced by immiscibilityare similar to those produced by other petrological processes. Within the flows of the North Mountain basaltof the Central Atlantic Magmatic Province are centimeter-thick granophyre layers. The granophyre layersare a mixture of mafic (i.e., ilmenite, magnetite, ferroaugite, plagioclase, stilpnomelane, ferrorichterite) andfelsic (i.e., sanidine, quartz) minerals and highly siliceous (&gt;75 wt% SiO2) mesostases. Petrologicalmodeling indicates that the siliceous mesostasis&nbsp;+ sanidine&nbsp;+ quartz&nbsp;&plusmn; ferrorichterite represents a Si-richsilicate immiscible melt whereas the ferroaugite&nbsp;+ plagioclase&nbsp;+ stilpnomelane represent the Fe-rich silicateimmiscible liquid. The identification of naturally occurring silicate-liquid immiscibility at scales greaterthan micron level is an important observation which may be useful in identifying volcanic and plutonicrocks which formed by macro-scale silicate-liquid immiscibility</p

Full characterization of vibrational coherence in a porphyrin chromophore by two-dimensional electronic spectroscopy

In this work we present experimental and calculated two-dimensional electronic spectra for a 5,15-bisalkynyl porphyrin chromophore. The lowest energy electronic Qy transition couples mainly to a single 380 cm–1 vibrational mode. The two-dimensional electronic spectra reveal diagonal and cross peaks which oscillate as a function of population time. We analyze both the amplitude and phase distribution of this main vibronic transition as a function of excitation and detection frequencies. Even though Feynman diagrams provide a good indication of where the amplitude of the oscillating components are located in the excitation-detection plane, other factors also affect this distribution. Specifically, the oscillation corresponding to each Feynman diagram is expected to have a phase that is a function of excitation and detection frequencies. Therefore, the overall phase of the experimentally observed oscillation will reflect this phase dependence. Another consequence is that the overall oscillation amplitude can show interference patterns resulting from overlapping contributions from neighboring Feynman diagrams. These observations are consistently reproduced through simulations based on third order perturbation theory coupled to a spectral density described by a Brownian oscillator model

Array of time-of-flight diamond detectors for particle discrimination in laser driven p-11B fusion experiments

The detection of radiation emission in laser induced plasma experiments is an helpful method for gaining information on the physics of laser-matter interaction. Time-of-Flight (TOF) approach is a powerful and effective method to obtain timely spectra of particles accelerated from laser-generated plasma. To this respect, diamond-based detectors are very attractive due to their interesting features such as fast signal collection time, signal proportional to the energy deposited by the incident radiation, blindness to visible radiation, high radiation hardness and low leakage current at room temperature operation. Unfortunately, they cannot supply discrimination on the species of the incoming ions, but only their energies. This may be overcome using specific filtering foils to exploit the different stopping powers of ions of different species and energies. In this work we describe the method to distinguish particles using an array of TOF diamond detectors. A first prototype array, consisting of 2×2 diamond detectors, nominally identical and featuring by aluminum filters of different thicknesses, was developed and preliminary tested at PALS facility in Prague

Impact of the COVID-19 pandemic on timeliness and equity of measles, mumps and rubella vaccinations in North East London: a longitudinal study using electronic health records.

OBJECTIVES: To quantify the effect of the COVID-19 pandemic on the timeliness of, and geographical and sociodemographic inequalities in, receipt of first measles, mumps and rubella (MMR) vaccination. DESIGN: Longitudinal study using primary care electronic health records. SETTING: 285 general practices in North East London. PARTICIPANTS: Children born between 23 August 2017 and 22 September 2018 (pre-pandemic cohort) or between 23 March 2019 and 1 May 2020 (pandemic cohort). MAIN OUTCOME MEASURE: Receipt of timely MMR vaccination between 12 and 18 months of age. METHODS: We used logistic regression to estimate the ORs (95% CIs) of receipt of a timely vaccination adjusting for sex, deprivation, ethnic background and Clinical Commissioning Group. We plotted choropleth maps of the proportion receiving timely vaccinations. RESULTS: Timely MMR receipt fell by 4.0% (95% CI: 3.4% to 4.6%) from 79.2% (78.8% to 79.6%) to 75.2% (74.7% to 75.7%) in the pre-pandemic (n=33 226; 51.3% boys) and pandemic (n=32 446; 51.4%) cohorts, respectively. After adjustment, timely vaccination was less likely in the pandemic cohort (0.79; 0.76 to 0.82), children from black (0.70; 0.65 to 0.76), mixed/other (0.77; 0.72 to 0.82) or with missing (0.77; 0.74 to 0.81) ethnic background, and more likely in girls (1.07; 1.03 to 1.11) and those from South Asian backgrounds (1.39; 1.30 to 1.48). Children living in the least deprived areas were more likely to receive a timely MMR (2.09; 1.78 to 2.46) but there was no interaction between cohorts and deprivation (Wald statistic: 3.44; p=0.49). The proportion of neighbourhoods where less than 60% of children received timely vaccination increased from 7.5% to 12.7% during the pandemic. CONCLUSIONS: The COVID-19 pandemic was associated with a significant fall in timely MMR receipt and increased geographical clustering of measles susceptibility in an area of historically low and inequitable MMR coverage. Immediate action is needed to avert measles outbreaks and support primary care to deliver timely and equitable vaccinations

Time evolution of stimulated Raman scattering and two-plasmon decay at laser intensities relevant for shock ignition in a hot plasma

Laser–plasma interaction (LPI) at intensities 1015–1016 W cm2 is dominated by parametric instabilities which can be responsible for a significant amount of non-collisional absorption and generate large fluxes of high-energy nonthermal electrons. Such a regime is of paramount importance for inertial confinement fusion (ICF) and in particular for the shock ignition scheme. In this paper we report on an experiment carried out at the Prague Asterix Laser System (PALS) facility to investigate the extent and time history of stimulated Raman scattering (SRS) and two-plasmon decay (TPD) instabilities, driven by the interaction of an infrared laser pulse at an intensity 1:2 1016 W cm2 with a 100 mm scalelength plasma produced from irradiation of a flat plastic target. The laser pulse duration (300 ps) and the high value of plasma temperature (4 keV) expected from hydrodynamic simulations make these results interesting for a deeper understanding of LPI in shock ignition conditions. Experimental results show that absolute TPD/SRS, driven at a quarter of the critical density, and convective SRS, driven at lower plasma densities, are well separated in time, with absolute instabilities driven at early times of interaction and convective backward SRS emerging at the laser peak and persisting all over the tail of the pulse. Side-scattering SRS, driven at low plasma densities, is also clearly observed. Experimental results are compared to fully kinetic large-scale, two-dimensional simulations. Particle-in-cell results, beyond reproducing the framework delineated by the experimental measurements, reveal the importance of filamentation instability in ruling the onset of SRS and stimulated Brillouin scattering instabilities and confirm the crucial role of collisionless absorption in the LPI energy balance

Invariant-mass and [gamma]-ray spectroscopy using secondary, radioactive ion beams

Coulomb excitation of secondary beams (5 < Z < 20) at energies around 250 .1 MeV was explored at GSI. For low-lying states, 7-ray spectroscopy was utilized, while high-lying excitations were investigated by means of invariant-mass spectroscopy