Current Asymmetry Research Articles

NEW METHODS OF SOFT COMPUTING IN REGIONAL DEVELOPMENT STRATEGY FORMATION

An urgent necessity in socio-economic regional development strategy specification is being substantiated for the purpose of reconstructing and adjusting the TEA (Types of Economic Activity) structure, which is able to speed up the development of GRP (Gross Regional Product), GS (Gross Surplus) per person and steadily grade current interregional differentiation and asymmetry. To reach the target a special algorithm for Soft Computing has been created. On the example of the selected region it was proved that the present economic system is not self-organized and it requires an efficient public management. If the regional management strategy is not optimally chosen then in the system some uncontrolled fluctuations can be observed, that may lead to an economic crisis and the collapse of the economy system. Mathematical models of optimization of strategies building of 3 types have been constructed and their effectiveness has been quantitatively researched. It is proved, that the dynamic management strategy with the maximizing of the objective function at the end of the period under investigation, turned out to be the most effective. It is established that public administration which is based on a scientifically grounded quantitative approach, using advanced mathematical models of Soft Computing, allows building a strong economic foundation, which will be the basis for a further rapid growth of the regional economy.

Investigation of the impact of insulator material on the performance of dissimilar electrode metal-insulator-metal diodes

The performance of thin film metal-insulator-metal (MIM) diodes is investigated for a variety of large and small electron affinity insulators using ultrasmooth amorphous metal as the bottom electrode. Nb2O5, Ta2O5, ZrO2, HfO2, Al2O3, and SiO2 amorphous insulators are deposited via atomic layer deposition (ALD). Reflection electron energy loss spectroscopy (REELS) is utilized to measure the band-gap energy (EG) and energy position of intrinsic sub-gap defect states for each insulator. EG of as-deposited ALD insulators are found to be Nb2O5 = 3.8 eV, Ta2O5 = 4.4 eV, ZrO2 = 5.4 eV, HfO2 = 5.6 eV, Al2O3 = 6.4 eV, and SiO2 = 8.8 eV with uncertainty of ±0.2 eV. Current vs. voltage asymmetry, non-linearity, turn-on voltage, and dominant conduction mechanisms are compared. Al2O3 and SiO2 are found to operate based on Fowler-Nordheim tunneling. Al2O3 shows the highest asymmetry. ZrO2, Nb2O5, and Ta2O5 based diodes are found to be dominated by Frenkel-Poole emission at large biases and exhibit lower asymmetry. The electrically estimated trap energy levels for defects that dominate Frenkel-Poole conduction are found to be consistent with the energy levels of surface oxygen vacancy defects observed in REELS measurements. For HfO2, conduction is found to be a mix of trap assisted tunneling and Frenkel-Poole emission. Insulator selection criteria in regards to MIM diodes applications are discussed.

REGULATION OF THE ASYMMETRY IN SPATIAL SOCIAL AND ECONOMIC DEVELOPMENT OF THE WEST KAZAKHSTAN REGION

Based on the research results, the scientific work indicates economic trends and issues in the territorial organization of the economy and population of West Kazakhstan region. Analysis of the spatial development in the economic sphere has shown that there is a territorial localization of the productive forces in the north of West Kazakhstan region. The typology of the West Kazakhstan administrative districts was formed according to their level and pace of socioeconomic and environmental development, from 1997 to 2011, on the basis of rank-scoring methodology. The results of this work demonstrate that the Northern administrative districts of West Kazakhstan region have a relatively high or an average level of social and economic development. A low level of social and economic development characterizes the administrative districts located to the south, west, southwest and southeast of West Kazakhstan region. These spatial differences reveal the current asymmetry in the level of social and economic development of the administrative districts, which determined the need for detecting major priorities in regulation of spatial social and economic development of the region. Thus, we propose the basic priorities for the spatial regulation of social and economic development of West Kazakhstan region within the framework of an effective intra-regional policy. The research results can be used by local government agencies to develop a regional management program for spatial social and economic development of West Kazakhstan region.

Asymmetric Brownian transport in a family of corrugated two-dimensional channels

Brownian dynamics simulations of passive particles along two-dimensional channels with curved midline and varying width are considered in this work. By considering finite-length channels formed by sinusoidal unit cells, it was found that axial asymmetry (e.g., non-zero midline) can induce asymmetric particle transport in the sense that the particle current is dependent on the transport direction (either left-to-right or right-to-left). Geometrically, this is caused by a combination of transient transport mechanism and non-uniform variation of the channel width, which produces the effect of a conical, diverging or converging, tube. Numerical results and theoretical predictions show that sinusoidal channels with curved midline and varying width can exhibit important levels of current asymmetry. In this way, this class of channels can be used as mass transport rectifiers where Brownian particles move preferentially in one direction than in the opposite direction. It is also shown that the transport asymmetry vanishes as the particle trajectories approach equilibrium conditions for sufficiently large channels.

Plasma current asymmetries during disruptions in JET

A key feature of disruptions during vertical displacement events, discovered in JET in 1996, is the toroidal variation in the measured plasma current Ip, i.e. the plasma current asymmetries, lasting for almost the entire current quench. The unique magnetic diagnostics at JET (full set of poloidal coils and saddle loops recorded either from two toroidally opposite or from four toroidally orthogonal locations) allow for a comprehensive analysis of asymmetrical disruptions with a large scale database. This paper presents an analysis of 4854 disruptions over an 18 year period that includes both the JET carbon (C) wall and the ITER-like (IL) wall (a mixed beryllium/tungsten first wall). In spite of the Ip quench time significantly increasing for the IL-wall compared to C-wall disruptions, the observed toroidal asymmetry time integral (∼ sideways force impulse), did not increase for IL-wall disruptions. The Ip asymmetry has a dominantly n = 1 structure. Its motion in the toroidal direction has a sporadic behaviour, in general. The distributions of the number of rotation periods are found to be very similar for both C- and IL-wall disruptions, and multi-turn rotation was sometimes observed. The Ip asymmetry amplitude has no degradation with rotation frequency for either the C- or IL-wall disruption. Therefore dynamic amplification remains a potentially serious issue for ITER due to possible mechanical resonance of the machine components with the rotating asymmetry.

Leptogenesis in \(A_4\) Flavor Symmetry Model by Renormalization Group Evolution

We study how leptogenesis can be implemented in the seesaw models with \(A_4\) flavor symmetry, which lead to the tri-bimaximalneutrino mixing matrix. By considering renormalzation groupevolution from a high energy scale of flavor symmetry breaking(the GUT scale is assumed) to the low energy scale of relevantphenomena, the off-diagonal terms in a combination of DiracYukawa-coupling matrix can be generated. As aresult, the flavored leptogenesis is successfully realized. Wealso investigate how the effective light neutrino mass \(|\langle m_{ee}\rangle |\) associated with neutrinoless double beta decaycan be predicted byimposing the experimental data on the low energy observables. Wefind a link between the leptogenesis and the neutrinoless doublebeta decay characterized by \(|\langle m_{ee}\rangle|\) through ahigh energy CP phase $\phi$, which is correlated with the lowenergy Majorana CP phases. It is shown that the predictions of \(|\langle m_{ee}\rangle|\) for some fixed parameters of the highenergy physics can be constrained by the current observation ofbaryon asymmetry.

Men are easier to read: Frontal alpha asymmetry reveals Neuroticism, but only in men

The relationship between EEG frontal alpha asymmetry and Big Five personality traits was investigated on a large student sample ( n = 208, 69 men). Alpha asymmetry is a widely used index of affective and motivational processes that is also related to both vulnerability and symptoms of mood and anxiety disorders. However, findings involving conceptually relevant personality traits such as behavioral inhibition and activation have been mixed. Furthermore, only a few studies have employed the Five-Factor Model. In the current sample asymmetry was negatively correlated with Neuroticism ( r = −.14, p < .05), but only for men (men r = −.34, p < .01; women r = −.04, p = .68). This distinction could not be explained by treating experimenter’s gender as a moderator of the relationship between personality and asymmetry. Taken together, these findings point towards possible gender-specific involvement of various underpinnings of Neuroticism (e.g. behavioral inhibition and worry).

Numerical modelling of electromagnetic loads on fusion device structures

In magnetic confinement fusion devices, during abnormal operations (disruptions) the plasma begins to move rapidly towards the vessel wall in a vertical displacement event (VDE), producing plasma current asymmetries, vessel eddy currents and open field line halo currents, each of which can exert potentially damaging forces upon the vessel and in-vessel components. This paper presents a methodology to estimate electromagnetic loads, on three-dimensional conductive structures surrounding the plasma, which arise from the interaction of halo-currents associated to VDEs with a magnetic field of the order of some Tesla needed for plasma confinement. Lorentz forces, calculated by complementary formulations, are used as constraining loads in a linear static structural analysis carried out on a detailed model of the mechanical structures of a representative machine.

On the SET/RESET current asymmetry in electrochemical metallization memory cells

Abstractmagnified imageIn this Letter we discuss the SET/RESET current asymmetry of the bipolar resistive switching in electrochemical metallization cells based on an analytical switching model. The model is based on the growth and dissolution of a metallic filament. It accounts for the controllability of the low resistive state and the RESET current by tuning the SET current. Based on this model a possible physical explanation for the SET/RESET asymmetry is presented. (© 2014 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Dune-associated sand fluxes at the nearshore termination of a banner sand bank (Helwick Sands, Bristol Channel)

Sand dunes typically migrate in opposing directions along the two sides of sand banks, reflecting a circulation driven by tidal current asymmetry, but it has been less clear how this pattern is distorted where banks intersect the coastline. The nearshore end of Helwick Sands, a banner bank in the Bristol Channel, was surveyed three times over three years, twice with a high-resolution multibeam echo-sounder. In both multibeam surveys, an unusual geometry was found over the crest of the bank, whereby dunes connect continuously with the dunes on the flanks, despite the flank dunes migrating in opposite directions. The crestal dunes thus appear to realign rapidly. We suggest that this morphological behaviour arises here because of vigorous wave-driven transport and because surface waves propagate almost exactly parallel to the crestal dunes. Sand transported parallel to the crestal dunes ensures that efficient reconnection occurs with dunes migrating along the flanks, particularly at low tide when wave currents are more strongly felt at the bed.Dunes were tracked between the surveys to assess the bedload transport fluxes associated with dune migration. Fluxes on the two flanks of the bank were found to be similar. The coarse-scale pattern of deposition and erosion was calculated from divergence of the fluxes using the continuity relation. That pattern differs strongly compared with the deposition/erosion pattern derived more directly from the bathymetry change between successive surveys. This implies that the dune-associated fluxes fail to represent all the sediment movements in this shallow area; significant contributions from storm wave-assisted transport, suspended load and/or sand transport during the reversed tide also probably affect transport flux besides dune-associated bedload.

The effect of bias current asymmetry on the flux-flow steps in the grain boundary YBaCuO long Josephson junctions

The current-voltage characteristics and critical current versus magnetic field dependence of long 24°[001]-tilt YBa2Cu3O7−δ bicrystal grain-boundary junctions are studied both experimentally and theoretically. For the opposite magnetic field directions, the flux-flow steps with significantly different height and slope are observed. It is demonstrated that the most probable reason of this discrepancy is recently predicted asymmetry of spatial bias current distribution due to crystallographic anisotropy of bicrystal substrates [Kupriyanov et al., JETP Lett. 95, 289 (2012)].

2D finite element analysis and force calculations for induction motors with broken bars

In this paper an ABC transient model of the three phase induction motor is developed that depends on self- and mutual inductance calculations based on accurate finite element analysis (FEA). This model can represent both healthy and broken bars’ conditions. The effects of that type of fault on the stator current, rotor bar currents distribution, the forces exerted on the rotor bars, the motor speed and motor torque are studied. It was observed that broken bar faults will cause fluctuations in the stator peak current and in the motor speed and torque. It was found that the asymmetry in the rotor bar currents will lead to asymmetrical distribution of the radial and tangential forces affecting the bars. The asymmetry in the tangential forces causes the fluctuations in the motor torque, while the asymmetry in the radial forces will increase the mechanical stresses on the rotor shaft.

Conduction processes in metal–insulator–metal diodes with Ta2O5 and Nb2O5 insulators deposited by atomic layer deposition

Metal–insulator–metal diodes with Nb2O5 and Ta2O5 insulators deposited via atomic layer deposition are investigated. For both Nb2O5 and Ta2O5, the dominant conduction process is established as Schottky emission at small biases and Frenkel–Poole emission at large biases. Fowler–Nordheim tunneling is not found to play a role in determining current versus voltage asymmetry. The dynamic dielectric constants are extracted from conduction plots and found to be in agreement with measured optical dielectric constants. Trap energy levels at ϕT ≈ 0.62 and 0.53 eV below the conduction band minimum are estimated for Nb2O5 and Ta2O5, respectively.

Prospects for charged current deep-inelastic scattering off polarized nucleons at a future electron-ion collider

We present a detailed phenomenological study of charged-current-mediated deep-inelastic scattering off longitudinally polarized nucleons at a future Electron-Ion Collider. A new version of the event generator package DJANGOH, extended by capabilities to handle processes with polarized nucleons, is introduced and used to simulate charged current deep-inelastic scattering including QED, QCD, and electroweak radiative effects. We carefully explore the range of validity and the accuracy of the Jacquet-Blondel method to reconstruct the relevant kinematic variables from the measured hadronic final state in charged current events, assuming realistic detector performance parameters. Finally, we estimate the impact of the simulated charged current single-spin asymmetries on determinations of helicity parton distributions in the context of a global QCD analysis at next-to-leading order accuracy.

An improved three‐phase reactive power measurement algorithm using walsh functions transform

AbstractThis paper proposes an improved algorithm for three‐phase power component measurement using the Walsh function (WF), which takes into account the advantages offered by the algorithm in the analysis of nonlinear load problems to improve the accuracy and reliability of measurement. In the pricing of electricity based on the value of the integral of the load active power measured using a kilowatt‐hour meter, the electric utility loses some revenue for the energy delivered to current harmonic generating customers and customers whose load causes current asymmetry. An improved algorithm based on the WF for measuring the active and reactive power of a network with linear and or nonlinear and sinusoidal or nonsinusoidal network is developed and tested, and the result compared with IEEE standard 1459–2000 which is based on fast Fourier transformation. The method does not require phase shifting of the phase current signals by π/2 with respect to the voltage signals. The proposed algorithm enables reactive power measurement for proper electricity billing to the consumer with nonlinear loads. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

Effects of Tidal Range Variability and Local Morphology on Hydrodynamic Behavior and Salinity Structure in the Caeté River Estuary, North Brazil

Tidal influence and local morphology on circulation and salt transport are investigated in the Caeté river estuary, a well-mixed estuary along the north coast of Brazil. Velocity, temperature, and salinity data were collected in three different locations along the estuary’s main channel, over three single, 13 h tidal cycles. The aim of this study was to investigate the relationship between tidal distortion and salinity by using classical methods of comparison of three cross-channel circulation characteristics, as well as computation of salt flux and vertical mixing. Findings indicate a flood-ebb asymmetry in currents, due to the distinct funneling morphology of the estuary, with shallow marginal areas being dominant towards the estuary head, while both stratification and shear dominate near the estuary mouth. The tidal currents enhanced vertical diffusion in the mid- and lower reaches, explaining the prevailing weakly stratified conditions, while the dominant well-mixed conditions in the upper estuary are a result of a combination of stronger flood currents and negligible vertical saline gradient. The predominant downstream salt transport supports the conclusion that there is little accumulation of salt in the Caeté river estuary. In addition, findings indicate that tidal correlation and Stokes drift are important components in the upper estuary, while tidal correlation played an important role in the middle estuary, with fluvial discharge most important in the lower estuary.

NUMERICAL SIMULATION OF TIDAL CIRCULATION IN THE PICHAVARAM MANGROVE ESTUARY

A vertically averaged numerical model is developed using the Surface water Modeling System (SMS) for t he Pichavaram Mangrove Estuary to study the tidal characteristics which en ables the simulation of the whole water circulation within the water body. The Pichavaram mangrove ecosystem is a complex network of creeks, mangroves and mud flats housed between t he Vellar and Coleroon rivers, 15 km north of Chidambaram, Tamil Nadu, Ind ia. A portion of the Coleroon river drains into the mangroves, and tidal flow is through the Coleroon mouth and a small inflow from an inlet in the north. The reduction of freshwater flow over the years has led to a degradation of the mangroves and changes in sedimen tation patterns. The results are calibrated against data collected previously. From the simulated results it is noticed that the tflow from the Coleroon mouth dominates the ent ire system. The maximum flood and ebb tide speed reached 0.777 ms -1 and 0.468 ms -1 during monsoon and post monsoon periods, respectiv ely. The tide showed a pronounced asymmetry in mangroves and a 12% increas e in total depth of water with a maximum increase i n water level of about 5 cm is noticed between monsoon and post monsoon cond itions. The dominance of ebb tide is noticed due to friction in the mangrove forest, which has resulted in slower flood current and greater tidal asymmetry in the waterway.

Impact and mitigation of disruptions with the ITER-like wall in JET

Disruptions are a critical issue for ITER because of the high thermal and magnetic energies that are released on short timescales, which results in extreme forces and heat loads. The choice of material of the plasma-facing components (PFCs) can have significant impact on the loads that arise during a disruption. With the ITER-like wall (ILW) in JET made of beryllium in the main chamber and tungsten in the divertor, the main finding is a low fraction of radiation. This has dropped significantly with the ILW from 50–100% of the total energy being dissipated during disruptions in CFC wall plasmas, to less than 50% on average and down to just 10% for vertical displacement events (VDEs). All other changes in disruption properties and loads are consequences of this low radiation: long current quenches (CQs), high vessel forces caused by halo currents and toroidal current asymmetries as well as severe heat loads. Temperatures close to the melting limit have been locally observed on upper first wall structures during deliberate VDE and even at plasma currents as low as 1.5 MA and thermal energy of about 1.5 MJ only. A high radiation fraction can be regained by massive injection of a mixture of 10% Ar with 90% D2. This accelerates the CQ thus reducing the halo current and sideways impulse. The temperature of PFCs stays below 400 °C. MGI is now a mandatory tool to mitigate disruptions in closed-loop operation for currents at and above 2.5 MA in JET.

Dissimilar-electrodes-induced asymmetric characteristic and diode effect of current transport in zinc oxide tunnel junctions

Based on the first principles simulations and quantum transport calculations, effects of dissimilar electrodes and interfaces on the current transport and relevant electrical properties in ZnO tunnel junctions as well as the mechanism of current asymmetric characteristic adjustment have been investigated. Our results show that the potential energy, built-in electric field, electron transmission probability, current, etc. in ZnO tunnel junctions can be tailored by adopting asymmetric electrode combinations. By adopting dissimilar electrodes to fabricate different potential barriers, we have performed manipulations on current transport in ZnO tunnel junctions and realized the enhancement and even the reversal of the current asymmetric characteristic. We also demonstrate that it is the different potential energy levels of the dissimilar electrodes in asymmetric tunnel junctions playing an important role in the adjustment of current asymmetry, which is innovative and different from the mechanism of current asymmetry adjustment through strain-induced piezopotential reversal. This investigation exhibits a novel and significant method for controlling or modifying the performances of electronic devices by utilizing dissimilar electrodes.

Does an ecological advantage produce the asymmetric lineage ratio in a harvester ant population?

In dependent-lineage harvester ant populations, two lineages interbreed but are genetically distinct. The offspring of a male and queen of the same lineage are female reproductives; the offspring of a male and queen of different lineages are workers. Geographic surveys have shown asymmetries in the ratio of the two lineages in many harvester ant populations, which may be maintained by an ecological advantage to one of the lineages. Using census data from a long-term study of a dependent-lineage population of the red harvester ant, Pogonomyrmex barbatus, we identified the lineage of 130 colonies sampled in 1997–1999, ranging in age from 1 to 19 years when collected, and 268 colonies sampled in 2010, ranging in age from 1 to 28 years when collected. The ratio of lineages in the study population is similar across an 11-year interval, 0.59 J2 in 1999 and 0.66 J2 in 2010. The rare lineage, J1, had a slightly but significantly higher number of mates of the opposite lineage than the common lineage, J2, and, using data from previous work on reproductive output, higher male production. Mature colonies of the two lineages did not differ in nest mound size, foraging activity, or the propensity to relocate their nests. There were no strong differences in the relative recruitment or survivorship of the two lineages. Our results show no ecological advantage for either lineage, indicating that differences between the lineages in sex ratio allocation may be sufficient to maintain the current asymmetry of the lineage ratio in this population.Electronic supplementary materialThe online version of this article (doi:10.1007/s00442-013-2690-z) contains supplementary material, which is available to authorized users.