Dual AC-drive system with a reduced switch count

A dual current-regulated pulsewidth-modulated voltage-source inverter based on multiple two-phase PWM inverters, also called a B4 topology, requiring a dual AC-drive system with reduced switch count is proposed. The drive utilizes a total of only eight switches to produce two sets of three-phase or two-phase sinusoidal output currents that can be employed to feed three-phase or two-phase induction motors. A suitable control strategy of this new scheme is shown to minimize the single-phase current now through the DC-link capacitors, which is a common problem in reduced-switch-count topologies. In order to verify the performance of the motor drive system, an application on traction of an electric vehicle is carried out. Results show that the AC current through the DC link can be minimized, and when utilizing two-phase motors on the proposed dual drive, the reduced voltage gain problem, also common in B4 topologies feeding three-phase motors, can be solved     

Subjective Well-being Across the Lifespan in Europe and Central Asia

Using data from the Integrated Values Survey (IVS), the Life in Transition Survey (LiTS), and the Russia Longitudinal Monitoring Survey (RLMS), we analyse the relation between age and subjective well-being in the World Bank’s Europe and Central Asia (ECA) region and compare it to that in Western Europe. Although our results generally confirm previous studies’ findings of a U-shaped relation between subjective well-being and age for most of the lifecycle, we also find that well-being in ECA declines again after the 70s, giving rise to an S-shape relation across the entire lifespan. When controlling for socio-demographic characteristics, this pattern generally remains robust for most of our cross-sectional and panel analyses. Hence, despite significant heterogeneity in the pattern of well-being across the lifespan within the ECA region, we do not observe high levels of cross-country or cross-cohort variation.     

Tracing the Origin and Evolution of Geochemical Characteristics of Waters from the Candiota Coal Mine Area (Southern Brazil): Part I

This work correlates surface and ground water composition to the substrata, and traces how water chemistry evolves at Brazil’s largest coal mine, the Candiota Mine. The water is dominated by SO₄, Fe, Ca, and Mg. A pH range of 2.7–3 in the pit lakes is attributed through chemical models to concomitant pyrite oxidation and carbonate dissolution along with slow hydrolysis of aluminosilicate minerals and buffering provided by several iron oxy-hydroxide species. The Fe deficit of the surface water relative to the expected values is mainly due to precipitation of Fe sulfate salts, hydroxysulfates, and oxyhydroxides in the waste piles and their runoff. A progressive decrease in oxygen partial pressure with increased lake depth leads to destabilization of the iron oxyhydroxides/hydroxysulfates formed near the surface, which explains their absence from the lake sediment. Although interacting with similar rock types, the groundwater has a significantly different composition than the surface water, with less salinity and a pH of 5–6.5, due to limited oxygen and its evolution in a nearly closed system that stabilizes at higher pH values, which is controlled by carbonate/bicarbonate buffering.     

Assessment of the generation of chlorinated byproducts upon Fenton-like oxidation of chlorophenols at different conditions

Homogeneous Fenton-like (H(2)O(2)/Fe(3+)) oxidation proved to be highly efficient in the degradation of monochlorophenols but some important issues need to be considered depending on the operating conditions. When using the stoichiometric amount of H(2)O(2) and a dose of Fe(3+) in the range of 10-20mg/L, complete breakdown of 4-CP up to CO(2) and short-chain acids was achieved. Nevertheless, when substoichiometric amounts of H(2)O(2) or lower concentrations of iron were used, significant differences between the TOC measured and the calculated from the identified species were found. These differences were attributed to condensation byproducts, including chlorinated species, formed by oxidative coupling reactions. PCBs, dioxins and dichlorodiphenyl ethers were identified. A solid residue was also formed consisting mainly in carbon, oxygen and chlorine including also Fe. The occurrence of these highly toxic species must be carefully considered in the application of Fenton oxidation to wastewaters containing chlorophenols. The possibility of reducing costs by lowering the H(2)O(2) dose below the stoichiometric one needs to take this into account.     

Adaptive directional stratification for controlled estimation of the probability of a rare event

Within the structural reliability context, the aim of this paper is to present a new accelerated Monte-Carlo simulation method, named ADS, Adaptive Directional Stratification, and designed to overcome the following industrial constraints: robustness of the estimation of a low structural failure probability (less than 10⁻³), limited computational resources and complex (albeit often monotonic) physical model. This new stochastic technique is an original variant of adaptive accelerated simulation method, combining stratified sampling and directional simulation and including two steps in the adaptation stage (ADS-2). First, we theoretically study the properties of two possible failure probability estimators and get the asymptotic and non-asymptotic expressions of their variances. Then, we propose some improvements for our new method. To begin with, we focus on the root-finding algorithm required for the directional approach: we present a stop criterion for the dichotomic method and a strategy to reduce the required number of calls to the costly physical model under monotonic hypothesis. Lastly, to overcome the limit involved by the increase of the input dimension, we introduce the ADS-2⁺ method which has the same ground as the ADS-2 method, but additionally uses a statistical test to detect the most significant inputs and carries out the stratification only along them. To conclude, we test the ADS-2 and ADS-2⁺ methods on academic examples in order to compare them with the classical structural reliability methods and to make a numerical sensitivity analysis over some parameters. We also apply the methods to a flood model and a nuclear reactor pressurized vessel model, to practically demonstrate their interest on real industrial examples.     

Multielementary (Cd, Cu, Pb, Zn, Ni) Stable Isotopic Exchange Kinetic (SIEK) method to characterize polymetallic contaminations

A new method is proposed to precisely and simultaneously quantify the exchangeable pool of metals in soils and to describe its reactivity at short- and long-term. It is based on multielementary Stable Isotopic Exchange Kinetics (multi-SIEK), first validated by a comparison between two monoelementary radioactive ((109)Cd*, (65)Zn*) IEK experiments, a mono- ((106)Cd) and multi- ((62)Ni, (65)Cu, (67)Zn, (106)Cd, (204)Pb) SIEK. These experiments were performed on a polluted soil located near the Zn smelter plant of Viviez (Lot watershed, France). The IEK results obtained for Cd and Zn were consistent across the experiments. (109)Cd*, (65)Zn* IEK, and multi-SIEK were then applied on 3 non- and moderate impacted soils that also provided consistent results for Cd and Zn. Within these experimental conditions, it can be concluded that no competition occurs between Cd, Zn, and the other metals during SIEK. Multi-SIEK results indicate that the isotopically exchangeable pool of Ni, Zn, and Cu are small (E(Ni), E(Zn), and E(Cu) values up to 17%) whatever the pollution degree of the soils considered in this study and whatever the duration of the interaction. On the contrary, Cd displays the highest E values (from 35% to 61% after 1 week), and E(Pb) displays a maximum value of 26% after 1 week. The multi-SIEK provides useful information on metal sources and reactivity relationship. Ni would be located in stable pedogenic phases according to its very low enrichment factor. The low E(Zn) and E(Cu) are consistent with location of Zn and Cu in stable phases coming from tailings erosion. Though Pb enrichments in soils may also be attributed to tailings particles, its larger exchangeable pool suggests that the Pb-bearing phases are more labile than those containing Zn and Cu. The high mobility of Cd in upstream soils indicates that it has been mostly emitted as reactive atmospheric particles during high temperature ore-treatment.     

Age-dependent models for evaluating risks and costs of surveillanceand maintenance of components

To determine in a quantitative way how surveillance and maintenance activities are reflected in component reliability, some age-dependent models to determine risks and associated economic costs are presented which explicitly consider how activities affect the component age as a function of the maintenance effectiveness. The models are based on reliability parameters such as demand-failure probability, standby failure rate, aging rate, and degradation rate. Also introduced are the concept of `characteristic function of maintenance' that states the relationship between maintenance effectiveness, its period, and the age setback. Several sensitivity analyses are performed on the reliability parameters and the maintenance effectiveness that allow establishment of important differences among activities with regard to their risks and costs. These models are: (1) important in maintenance improvement, particularly within the reliability centered maintenance (RCM) methodology; (2) useful in finding a degradation vs maintenance effectiveness relationship. They are used in assessing maintenance effectiveness within a program based on RCM at Cofrentes Nuclear Power Plant (Spain), where several policies of integrating surveillance and maintenance activities are analyzed     

Chromogranin A inhibits dopamine release from rat striatal slices

Chromogranin A (CGA), a prohormone and a protein component of endocrine and neural secretory granules, neuritic plaques in Alzheimer's disease and Lewy bodies in Parkinson's disease, inhibited the release of dopamine (DA) from perfused rat striatal slices. Dopamine release was stimulated by a pulse of high potassium (40mM) medium introduced at 20 minutes (K1) and 55 minutes (K2) following equilibration. The ratio of K2/K1 was 0.80+/-0.04 in control tissues, but fell significantly to 0.26+/-0.08 when 100nM purified CGA was added prior to the second potassium pulse. This reduction in DA release was equivalent to that seen when calcium was excluded from the buffer (0.19+/-0.05). Pancreastatin, a centrally active peptide product of CGA, had no effect on stimulated DA release (0.77+/-0.06), although it, as well as the other treatments, did reduce basal DA release. It is likely that the parent molecule itself, CGA, or an as yet unidentified product is responsible for inhibition of K-stimulated striatal DA release.     

Polarisation independent intensity modulation setup based on serial polarisation diversity arrangement for header rewriting in label swapping networks

A practically independent intensity modulation arrangement is demonstrated based on two standard LiNbO/sub 3/ electro-optical modulators (EOM) in a serial polarisation diversity (SPD) structure. Polarisation reduction from the typical values over 30-50 dB to levels <0.5 dB has been achieved. This technique has a potential application in header rewriting in subcarrier multiplexed label swapping networks.