Single-phase power line conditioning with unity power factor under distorted utility voltage

The paper proposes a control method of a single-phase active power line conditioner (APLC) aimed at correcting the power factor of linear and non-linear loads supplied by distorted voltage utility. The method, that is based on the single-phase p-q theory and utilizes a third-order sinusoidal signal integrator, gets utility unity power factor and, at the same time, overcomes the shortcomings of the solutions pursuing utility sinusoidal current, namely the possible onset of un-damped resonance phenomena and the reduction in the energy delivery capabilities; moreover, the method makes the power factor correction robust against the supply distortion. The excellent performance of the method is substantiated by testing it by means of a hardware-in-the-loop setup

Symmetry in concurrent games

Abstract—Behavioural symmetry is introduced into concurrent games. It expresses when plays are essentially the same. A characterization of strategies on games with symmetry is provided. This leads to a bicategory of strategies on games with symmetry. Symmetry helps allay the perhaps overly-concrete nature of games and strategies, and shares many mathematical features with homotopy. In the presence of symmetry we can consider monads for which the monad laws do not hold on the nose but do hold up to symmetry. This broadening of the concept of monad has a dramatic effect on the types concurrent games can support and allows us, for example, to recover the replication needed to express and extend traditional game semantics of programming languages. I

The parallel intensionally fully abstract games model of PCF

International audienceWe describe a framework for truly concurrent game semantics of programming languages, based on Rideau and Winskel's concurrent games on event structures. The model supports a notion of innocent strategy that permits concurrent and non-deterministic behaviour, but which coincides with traditional Hyland-Ong innocent strategies if one restricts to the deterministic sequential case. In this framework we give an alternative interpretation of Plotkin's PCF, that takes advantage of the concurrent nature of strategies and formalizes the idea that although PCF is a sequential language, certain sub-computations are independent and can be computed in a parallel fashion. We show that just as Hyland and Ong's sequential interpretation of PCF, our parallel interpretation yields a model that is intensionally fully abstract for PCF

The Yellow Coral Dendrophyllia cornigera in a Warming Ocean

Ocean warming is expected to impinge detrimentally on marine ecosystems worldwide up to impose extreme environmental conditions capable to potentially jeopardize the good ecological status of scleractinian coral reefs at shallow and bathyal depths. The integration of literature records with newly acquired remotely operated vehicle (ROV) data provides an overview of the geographic distribution of the temperate coral Dendrophyllia cornigera spanning the eastern Atlantic Ocean to the whole Mediterranean Sea. In addition, we extracted temperature values at each occurrence site to define the natural range of this coral, known to maintain its physiological processes at 16\ub0C. Our results document a living temperature range between 3c7\ub0C and 17\ub0C, suggesting that the natural thermal tolerance of this eurybathic coral may represent an advantage for its survival in a progressively warming ocean

An Algebraic Algorithm for Motor Voltage Waveform Prediction in Dual-LCI Drives With Interconnected DC-Links

Load-commutated inverters (LCI's) are often used to supply dual-three-phase synchronous motors in high-power variable-speed applications. A pair of LCIs is used in this arrangement to feed the two motor three-phase winding sets. In order to cope with inter-harmonic issues, a drive configuration with an interconnection of the two LCI dc-links has been proposed. In this paper, such a drive design is shown to produce an increased voltage stress on motor windings compared with traditional configurations. The problem is investigated in the paper by proposing an algebraic algorithm capable of predicting the steady-state voltage waveform applied to the motor terminals and arising between the star points of the two winding sets. Unlike conventional dynamic simulations, the proposed approach gives practically instantaneous results, making it possible to quickly investigate a wide number of possible operating conditions. Furthermore, it requires a limited knowledge of system parameters, which are often hardly available. Its reliability and accuracy are assessed by comparison with measurements on a test drive system and examples are given of the method application to the sizing of motor insulation system

Two and Three Dimensional Incommensurate Modulation in Optimally-Doped Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta}

X-ray scattering measurements on optimally-doped single crystal samples of the high temperature superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ reveal the presence of three distinct incommensurate charge modulations, each involving a roughly fivefold increase in the unit cell dimension along the {\bf b}-direction. The strongest scattering comes from the well known (H, K$\pm$ 0.21, L) modulation and its harmonics. However, we also observe broad diffraction which peak up at the L values complementary to those which characterize the known modulated structure. These diffraction features correspond to correlation lengths of roughly a unit cell dimension, $\xi_c$$\sim$20 $\AA$ in the {\bf c} direction, and of $\xi_b$$\sim$ 185 $\AA$ parallel to the incommensurate wavevector. We interpret these features as arising from three dimensional incommensurate domains and the interfaces between them, respectively. In addition we investigate the recently discovered incommensuate modulations which peak up at (1/2, K$\pm$ 0.21, L) and related wavevectors. Here we explicitly study the L-dependence of this scattering and see that these charge modulations are two dimensional in nature with weak correlations on the scale of a bilayer thickness, and that they correspond to short range, isotropic correlation lengths within the basal plane. We relate these new incommensurate modulations to the electronic nanostructure observed in Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ using STM topography.Comment: 8 pages, 8 figure

Detecting filamentary pattern in the cosmic web : a catalogue of filaments for the SDSS

International audienceThe main feature of the spatial large-scale galaxy distribution is its intricate network of galaxy filaments. This network is spanned by the galaxy locations that can be interpreted as a three-dimensional point distribution. The global properties of the point process can be measured by different statistical methods, which, however, do not describe directly the structure elements. The morphology of the large-scale structure, on the other hand, is an important property of the galaxy distribution. Here, we apply an object point process with interactions (the Bisous model) to trace and extract the filamentary network in the presently largest galaxy redshift survey, the Sloan Digital Sky Survey (SDSS). We search for filaments in the galaxy distribution that have a radius of about 0.5 h −1 Mpc. We divide the detected network into single filament

Structural Fluctuations in the Spin Liquid State of Tb2Ti2O7

High resolution X-ray scattering measurements on single crystal Tb2Ti2O7 reveal finite structural correlations at low temperatures. This geometrically frustrated pyrochlore is known to exhibit a spin liquid, or cooperative paramagnetic state, at temperatures below ~ 20 K. Parametric studies of structural Bragg peaks appropriate to the Fd$\bar{3}$m space group of Tb2Ti2O7 reveal substantial broadening and peak intensity reduction in the temperature regime 20 K to 300 mK. We also observe a small, anomalous lattice expansion on cooling below a density maximum at ~ 18 K. These measurements are consistent with the development of fluctuations above a cooperative Jahn-Teller, cubic-tetragonal phase transition at very low temperatures.Comment: 5 pages, 4 figures, submitted for publicatio