Thermal fluctuation levels of magnetic and electric fields in unmagnetized plasma: The rigorous relativistic kinetic theory

International Nuclear Information System (INIS)

Yoon, P. H.; Schlickeiser, R.; Kolberg, U.

2014-01-01

Any fully ionized collisionless plasma with finite random particle velocities contains electric and magnetic field fluctuations. The fluctuations can be of three different types: weakly damped, weakly propagating, or aperiodic. The kinetics of these fluctuations in general unmagnetized plasmas, governed by the competition of spontaneous emission, absorption, and stimulated emission processes, is investigated, extending the well-known results for weakly damped fluctuations. The generalized Kirchhoff radiation law for both collective and noncollective fluctuations is derived, which in stationary plasmas provides the equilibrium energy densities of electromagnetic fluctuations by the ratio of the respective spontaneous emission coefficient and the true absorption coefficient. As an illustrative example, the equilibrium energy densities of aperiodic transverse collective electric and magnetic fluctuations in an isotropic thermal electron-proton plasmas of density n e are calculated as |δB|=√((δB) 2 )=2.8(n e m e c 2 ) 1/2 g 1/2 β e 7/4 and |δE|=√((δE) 2 )=3.2(n e m e c 2 ) 1/2 g 1/3 β e 2 , where g and β e denote the plasma parameter and the thermal electron velocity in units of the speed of light, respectively. For densities and temperatures of the reionized early intergalactic medium, |δB|=6·10 −18 G and |δE|=2·10 −16 G result

Electric field fluctuations in liquid tellurium alloys a hint to bond character

NARCIS (Netherlands)

Paulick, C.A.; Brinkmann, R.; Elwenspoek, Michael Curt; von Hartrott, M.; Kiehl, M.; Maxim, P.; Quitmann, D.

1985-01-01

Atomic scale electric field fluctuations in liquid tellurium alloys are detected as they induce nuclear spin relaxation rate RQ in noble gas impurity atoms, via quadrupolar interaction. Results for Xe in liquid Ag, Ga, In, Tl, Ge, Sn---Te alloys are discussed, assuming that bonding in these alloys

Quantum fluctuations of the Coulomb potential as a source of flicker noise: the influence of external electric field

International Nuclear Information System (INIS)

Kazakov, Kirill A

2006-01-01

Fluctuations of the electromagnetic field produced by quantized matter in an external electric field are investigated. A general expression for the power spectrum of fluctuations is derived within the long-range expansion. It is found that in the whole measured frequency band, the power spectrum of fluctuations exhibits an inverse frequency dependence. A general argument is given showing that for all practically relevant values of the electric field, the power spectrum of induced fluctuations is proportional to the field strength squared. As an illustration, the power spectrum is calculated explicitly using a kinetic model with a relaxation-type collision term. Finally, it is shown that the magnitude of fluctuations produced by a sample generally has a Gaussian distribution around its mean value, and its dependence on the sample geometry is determined. In particular, it is demonstrated that for geometrically similar samples the power spectrum is inversely proportional to the sample volume. Application of the results obtained to the problem of flicker noise is discussed

Asymptotic behavior of correlation functions for electric potential and field fluctuations in a classical one-component plasma

NARCIS (Netherlands)

Suttorp, L.G.

1992-01-01

The correlations of the electric potential fluctuations in a classical one-component plasma are studied for large distances between the observation points. The two-point correlation function for these fluctuations is known to decay slowly for large distances, even if exponential clustering holds for

Conductance fluctuations and distribution at metal-insulator transition induced by electric field in disordered chain

International Nuclear Information System (INIS)

Senouci, Khaled

2000-08-01

A simple Kronig-Penney model for 1D mesoscopic systems with δ peak potentials is used to study numerically the influence of a constant electric field on the conductance fluctuations and distribution at the transition. We found that the conductance probability distribution has a system-size independent form with large fluctuations in good agreement with the previous works in 2D and 3D systems. (author)

Optimal designs of small CHP plants in a market with fluctuating electricity prices

International Nuclear Information System (INIS)

Lund, H.; Andersen, A.N.

2005-01-01

Combined Heat and Power production (CHP) are essential for implementation of the climate change response objectives in many countries. In an introduction period, small CHP plants have typically been offered fixed electricity prices, but in many countries, such pricing conditions are now being replaced by spot market prices. Consequently, new methodologies and tools for the optimisation of small CHP plant designs are needed. The small CHP plants in Denmark are already experienced in optimising their electricity production against the triple tariff, which has existed for almost 10 years. Consequently, the CHP plants have long term experience in organising when to switch on and off the CHP units in order to optimise their profit. Also, the CHP owners have long term experience in designing their plants. For instance, small CHP plants in Denmark have usually invested in excess capacity on the CHP units in combination with heat storage capacity. Thereby, the plants have increased their performance in order to optimise revenues. This paper presents the Danish experience with methodologies and software tools, which have been used to design investment and operation strategies for almost all small CHP plants in Denmark during the decade of the triple tariff. Moreover, the changes in such methodologies and tools in order to optimise performance in a market with fluctuating electricity prices are presented and discussed

Fatigue response of a PZT multilayer actuator under high-field electric cycling with mechanical preload

Science.gov (United States)

Wang, Hong; Wereszczak, Andrew A.; Lin, Hua-Tay

2009-01-01

An electric fatigue test system was developed for evaluating the reliability of piezoelectric actuators with a mechanical loading capability. Fatigue responses of a lead zirconate titanate (PZT) multilayer actuator with a platethrough electrode configuration were studied under an electric field (1.7 times that of the coercive field of PZT material) and a concurrent mechanical preload (30.0 MPa). A total of 109 cycles was carried out. Variations in charge density and mechanical strain under the high electric field and constant mechanical loads were observed during the fatigue test. The dc and the first harmonic (at 10 Hz) dielectric and piezoelectric coefficients were subsequently characterized using fast Fourier transformation. Both the dielectric and the piezoelectric coefficients exhibited a monotonic decrease prior to 2.86×108 cycles under certain preloading conditions, and then fluctuated. Both the dielectric loss tangent and the piezoelectric loss tangent also fluctuated after a decrease. The results are interpreted and discussed with respect to domain wall activities, microdefects, and other anomalies.

Tension moderation and fluctuation spectrum in simulated lipid membranes under an applied electric potential

DEFF Research Database (Denmark)

Loubet, Bastien; Lomholt, Michael Andersen; Khandelia, Himanshu

2013-01-01

, and bilayer thickness are investigated in detail. In particular, the least square fitting technique is used to calculate the fluctuation spectra. The simulations confirm a recently proposed theory that the effect of an applied electric potential on the membrane will be moderated by the elastic properties...

Evaluation of random temperature fluctuation problems with frequency response approach

International Nuclear Information System (INIS)

Lejeail, Yves; Kasahara, Naoto

2000-01-01

Since thermal striping is a coupled thermohydraulic and thermomechanical phenomenon, sodium mock-up tests were usually required to confirm structural integrity. Authors have developed the frequency response function to establish design-by-analysis methodology for this phenomenon. Applicability of this method to sinusoidal fluctuation was validated through two benchmark problems with FAENA and TIFFSS facilities under EJCC contract. This report describes the extension of the frequency response method to random fluctuations. As an example of application, fatigue strength of a Tee junction of PHENIX secondary piping system was investigated. (author)

Fluctuation-Response Relation and modeling in systems with fast and slow dynamics

Directory of Open Access Journals (Sweden)

G. Lacorata

2007-10-01

Full Text Available We show how a general formulation of the Fluctuation-Response Relation is able to describe in detail the connection between response properties to external perturbations and spontaneous fluctuations in systems with fast and slow variables. The method is tested by using the 360-variable Lorenz-96 model, where slow and fast variables are coupled to one another with reciprocal feedback, and a simplified low dimensional system. In the Fluctuation-Response context, the influence of the fast dynamics on the slow dynamics relies in a non trivial behavior of a suitable quadratic response function. This has important consequences for the modeling of the slow dynamics in terms of a Langevin equation: beyond a certain intrinsic time interval even the optimal model can give just statistical prediction.

Out-of-equilibrium fluctuation-dissipation relations verified by the electrical and thermoelectrical AC-conductances in a quantum dot

Energy Technology Data Exchange (ETDEWEB)

Crepieux, Adeline [Aix Marseille Univ., Universite de Toulon, CNRS, CPT, Marseille (France)

2017-09-15

The electrical and heat currents flowing through a quantum dot are calculated in the presence of a time-modulated gate voltage with the help of the out-of-equilibrium Green function technique. From the first harmonics of the currents, we extract the electrical and thermoelectrical trans-admittances and ac-conductances. Next, by a careful comparison of the ac-conductances with the finite-frequency electrical and mixed electrical-heat noises, we establish the fluctuation-dissipation relations linking these quantities, which are thus generalized out-of-equilibrium for a quantum system. It is shown that the electrical ac-conductance associated to the displacement current is directly linked to the electrical noise summed over reservoirs, whereas the relation between the thermoelectrical ac-conductance and the mixed noise contains an additional term proportional to the energy step that the electrons must overcome when traveling through the junction. A numerical study reveals however that a fluctuation-dissipation relation involving a single reservoir applies for both electrical and thermoelectrical ac-conductances when the frequency dominates over the other characteristic energies. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Dynamical interplay between fluctuations, electric fields and transport in fusion plasmas

International Nuclear Information System (INIS)

Hidalgo, C.; Pedrosa, M.A.; Goncalves, B.

2003-01-01

A view of recent experimental results and progress in the characterization of the statistical properties of electrostatic turbulence in magnetically confined devices is given. An empirical similarity in the scaling properties of the probability distribution function (PDF) of turbulent transport has been observed in the plasma edge region in fusion plasmas. The investigation of the dynamical interplay between fluctuation in gradients, turbulent transport and radial electric fields has shows that these parameters are strongly coupled both in tokamak and stellarator plasmas. The bursty behaviour of turbulent transport is linked with a departure from the most probable radial gradient. The dynamical relation between fluctuations in gradients and transport is strongly affected by the presence of sheared poloidal flows which organized themselves near marginal stability. These results emphasize the importance of the statistical description of transport processes in fusion plasmas as an alternative approach to the traditional way to characterize transport based on the computation of effective transport coefficients. (author)

Fluctuations and Photons

International Nuclear Information System (INIS)

Gupta, Sourendu

2007-01-01

In this talk I discuss measures of fluctuations, especially those leading to the proof that the quark gluon plasma indeed contains quarks. I discuss the quark mass dependence of the critical end point of QCD. Then I discuss probes of the QCD critical point. Non-gaussian behaviour of event-to-event fluctuations of conserved quantum numbers is one such probe. Another is due to the coupling of fluctuations in baryon number and electrical charge, giving rise to long range random fluctuations of local charge density which relax slowly. These fluctuations can scatter photons, giving rise to critical opalescence

Fluctuations and Photons

Science.gov (United States)

Gupta, Sourendu

2007-02-01

In this talk I discuss measures of fluctuations, especially those leading to the proof that the quark gluon plasma indeed contains quarks. I discuss the quark mass dependence of the critical end point of QCD. Then I discuss probes of the QCD critical point. Non-gaussian behaviour of event-to-event fluctuations of conserved quantum numbers is one such probe. Another is due to the coupling of fluctuations in baryon number and electrical charge, giving rise to long range random fluctuations of local charge density which relax slowly. These fluctuations can scatter photons, giving rise to critical opalescence.

Fluctuations and Photons

Energy Technology Data Exchange (ETDEWEB)

Gupta, Sourendu [Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

2007-02-15

In this talk I discuss measures of fluctuations, especially those leading to the proof that the quark gluon plasma indeed contains quarks. I discuss the quark mass dependence of the critical end point of QCD. Then I discuss probes of the QCD critical point. Non-gaussian behaviour of event-to-event fluctuations of conserved quantum numbers is one such probe. Another is due to the coupling of fluctuations in baryon number and electrical charge, giving rise to long range random fluctuations of local charge density which relax slowly. These fluctuations can scatter photons, giving rise to critical opalescence.

Integration scenarios of Demand Response into electricity markets: Load shifting, financial savings and policy implications

International Nuclear Information System (INIS)

Feuerriegel, Stefan; Neumann, Dirk

2016-01-01

Demand Response allows for the management of demand side resources in real-time; i.e. shifting electricity demand according to fluctuating supply. When integrated into electricity markets, Demand Response can be used for load shifting and as a replacement for both control reserve and balancing energy. These three usage scenarios are compared based on historic German data from 2011 to determine that load shifting provides the highest benefit: its annual financial savings accumulate to €3.110 M for both households and the service sector. This equals to relative savings of 2.83% compared to a scenario without load shifting. To improve Demand Response integration, the proposed model suggests policy implications: reducing bid sizes, delivery periods and the time-lag between market transactions and delivery dates in electricity markets. - Highlights: •Comparison of 3 scenarios to integrate Demand Response into electricity markets. •These are: optimize procurement, offer as control reserve, avoid balancing energy. •Ex post simulation to quantify financial impact and policy implications. •Highest savings from load shifting with a cost reduction of 3%. •Model suggests reducing bid sizes, delivery periods and time lags as policy issues.

Measurement of amplitude fluctuations in a rapid response photomultiplier

International Nuclear Information System (INIS)

Raimbault, P.

1961-01-01

In order to measure amplitude fluctuations in a rapid response photomultiplier, two independent random variables are introduced which determine the shape of the anode pulse. The energy of each pulse, which depends directly on the gain and the variance, is the first variable; amplitude fluctuations, functions of the first variable, depend as well on the pulse width which in turn constitutes the second variable. The results obtained on the variations of the maximum impulse, using a steep-edged pulse broadening circuit, and those obtained on the statistical variations of the gain, are compared to show that the variance relative to the maximum amplitude of the signal is greater than that of the gain. Within the limits of these fluctuations are shown the contribution of the secondary emission coefficient of the first dynode, and that of the mean secondary emission coefficient of the multiplier. (author) [fr

Concentration Fluctuations and Capacitive Response in Dense Ionic Solutions.

Science.gov (United States)

Uralcan, Betul; Aksay, Ilhan A; Debenedetti, Pablo G; Limmer, David T

2016-07-07

We use molecular dynamics simulations in a constant potential ensemble to study the effects of solution composition on the electrochemical response of a double layer capacitor. We find that the capacitance first increases with ion concentration following its expected ideal solution behavior but decreases upon approaching a pure ionic liquid in agreement with recent experimental observations. The nonmonotonic behavior of the capacitance as a function of ion concentration results from the competition between the independent motion of solvated ions in the dilute regime and solvation fluctuations in the concentrated regime. Mirroring the capacitance, we find that the characteristic decay length of charge density correlations away from the electrode is also nonmonotonic. The correlation length first decreases with ion concentration as a result of better electrostatic screening but increases with ion concentration as a result of enhanced steric interactions. When charge fluctuations induced by correlated ion-solvent fluctuations are large relative to those induced by the pure ionic liquid, such capacitive behavior is expected to be generic.

Linear response to long wavelength fluctuations using curvature simulations

Energy Technology Data Exchange (ETDEWEB)

Baldauf, Tobias; Zaldarriaga, Matias [School of Natural Sciences, Institute for Advanced Study, Princeton, NJ (United States); Seljak, Uroš [Physics Department, Astronomy Department and Lawrence Berkeley National Laboratory, University of California, Berkeley, CA (United States); Senatore, Leonardo, E-mail: baldauf@ias.edu, E-mail: useljak@berkeley.edu, E-mail: senatore@stanford.edu, E-mail: matiasz@ias.edu [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA (United States)

2016-09-01

We study the local response to long wavelength fluctuations in cosmological N -body simulations, focusing on the matter and halo power spectra, halo abundance and non-linear transformations of the density field. The long wavelength mode is implemented using an effective curved cosmology and a mapping of time and distances. The method provides an alternative, more direct, way to measure the isotropic halo biases. Limiting ourselves to the linear case, we find generally good agreement between the biases obtained from the curvature method and the traditional power spectrum method at the level of a few percent. We also study the response of halo counts to changes in the variance of the field and find that the slope of the relation between the responses to density and variance differs from the naïve derivation assuming a universal mass function by approximately 8–20%. This has implications for measurements of the amplitude of local non-Gaussianity using scale dependent bias. We also analyze the halo power spectrum and halo-dark matter cross-spectrum response to long wavelength fluctuations and derive second order halo bias from it, as well as the super-sample variance contribution to the galaxy power spectrum covariance matrix.

The role of fluctuation-induced transport in a toroidal plasma with strong radial electric fields

Science.gov (United States)

Roth, J. R.; Krawczonek, W. M.; Powers, E. J.; Hong, J. Y.; Kim, Y. C.

1981-01-01

Previous work employing digitally implemented spectral analysis techniques is extended to demonstrate that radial fluctuation-induced transport is the dominant ion transport mechanism in an electric field dominated toroidal plasma. Such transport can be made to occur against a density gradient, and hence may have a very beneficial effect on confinement in toroidal plasmas of fusion interest. It is shown that Bohm or classical diffusion down a density gradient, the collisional Pedersen-current mechanism, and the collisionless electric field gradient mechanism described by Cole (1976) all played a minor role, if any, in the radial transport of this plasma.

Fluctuation-driven directional flow of energy in biochemical cycle: Electric activation of Na,K ATPase

Science.gov (United States)

Yow Tsong, Tian

1998-03-01

Na,K ATPase is an ion pump which uses chemical bond energy of ATP to pump Na ion out of, and K ion into living cell thus maintaining ionic and osmotic balances of the cell. Both are uphill transport reactions. Surprisingly we have found that electric energy can also substitute chemical energy to fuel the pump activity. However, in this case only electric fields of certain waveforms, amplitudes, and frequencies are effective. Waveform, amplitude and frequency are three elements of signal. In other words, Na,K ATPase can recognize, process, and harvest energy from an oscillating or a fluctuating electric field to drive an endergonic reaction. The enzyme is a molecular transducer of electric signal. This report will describe electric activation experiment to define electric signal. Electric signal will then mixed with electric noise of broad power spectrum for experiment. Effect of white noise (WN) on the efficiency of Na,K ATPase will be investigated. It will be shown that WN of appropriate power level can improve the pump efficiency when a sub-optimal electric field is used. WN can also carry a sub-threshold signal to cross over the threshold. Stochastic resonance will be discussed in reference to these observations.

Feeble magnetic fields generated by thermal charge fluctuations in extended metallic conductors: Implications for electric-dipole moment experiments

International Nuclear Information System (INIS)

Lamoreaux, S.K.

1999-01-01

A simple formulation for calculating the magnetic field external to an extended nonpermeable conducting body due to thermal current fluctuations within the body is developed, and is applied to a recent experimental search for the atomic electric-dipole moment (EDM) of 199 Hg. It is shown that the thermal fluctuation field is only slightly smaller in magnitude than other noise sources in that experiment. The formulation is extended to permeable bodies, and the implications for general EDM experiments are discussed. copyright 1999 The American Physical Society

Fluctuations in Schottky barrier heights

International Nuclear Information System (INIS)

Mahan, G.D.

1984-01-01

A double Schottky barrier is often formed at the grain boundary in polycrystalline semiconductors. The barrier height is shown to fluctuate in value due to the random nature of the impurity positions. The magnitude of the fluctuations is 0.1 eV, and the fluctuations cause the barrier height measured by capacitance to differ from the one measured by electrical conductivity

Response functions of cold neutron matter: density, spin and current fluctuations

Energy Technology Data Exchange (ETDEWEB)

Keller, Jochen; Sedrakian, Armen [Institut fuer Theoretische Physik, Goethe-Universitaet, Frankfurt am Main (Germany)

2014-07-01

We study the response of a single-component pair-correlated baryonic Fermi-liquid to density, spin, and their current perturbations. A complete set of response functions is calculated in the low-temperature regime. We derive the spectral functions of collective excitations associated with the density, density-current, spin, and spin-current perturbations. The dispersion relations of density and spin fluctuations are determined and it is shown that the density fluctuations lead to exciton-like undamped bound states, whereas the spin excitations correspond to diffusive modes above the pair-breaking threshold. The contribution of the collective pair-breaking modes to the specific heat of neutron matter at subnuclear densities is computed and is shown to be comparable to that of the degenerate electron gas at not too low temperatures.

Effect of electric fields and fluctuations on confinement in a bumpy torus

International Nuclear Information System (INIS)

Hiroe, S.; Glowienka, J.C.; Hillis, D.L.

1986-06-01

In order to understand the relationships between confinement and space potential (electric field) and between confinement and density fluctuations, plasma parameters in the ELMO Bumpy Torus Scale (EBT-S) have been measured systematically for a wide range of operating conditions. Present EBT plasma parameters do not show a strong dependence on the potential profile, but rather exhibit a correlation with the fluctuations. The plasma pressure profile is found to be consistent with the profile anticipated on the basis of the flute stability criterion for a marginally stable plasma. For a heating power of 100 kW, the stored energy density is found to be restricted to the range between 4.5 x 10 13 eV-cm -3 and 7 x 10 13 eV-cm -3 . The lower limit remains constant regardless of heating power and pertains to plasmas lacking an equilibrium and/or stability. The upper limit increases with heating power and is found to result from the onset of instabilities. In between the two limits is a plasma that is in an equilibrium state and is marginally stable. Operational trajectories exist that take the EBT plasma from one limit to the other

Optimal operation strategies of compressed air energy storage (CAES) on electricity spot markets with fluctuating prices

DEFF Research Database (Denmark)

Lund, Henrik; Salgi, Georges; Elmegaard, Brian

2009-01-01

on electricity spot markets by storing energy when electricity prices are low and producing electricity when prices are high. In order to make a profit on such markets, CAES plant operators have to identify proper strategies to decide when to sell and when to buy electricity. This paper describes three...... plants will not be able to achieve such optimal operation, since the fluctuations of spot market prices in the coming hours and days are not known. Consequently, two simple practical strategies have been identified and compared to the results of the optimal strategy. This comparison shows that...... independent computer-based methodologies which may be used for identifying the optimal operation strategy for a given CAES plant, on a given spot market and in a given year. The optimal strategy is identified as the one which provides the best business-economic net earnings for the plant. In practice, CAES...

Fluctuations of local electric field and dipole moments in water between metal walls.

Science.gov (United States)

Takae, Kyohei; Onuki, Akira

2015-10-21

We examine the thermal fluctuations of the local electric field Ek (loc) and the dipole moment μk in liquid water at T = 298 K between metal walls in electric field applied in the perpendicular direction. We use analytic theory and molecular dynamics simulation. In this situation, there is a global electrostatic coupling between the surface charges on the walls and the polarization in the bulk. Then, the correlation function of the polarization density pz(r) along the applied field contains a homogeneous part inversely proportional to the cell volume V. Accounting for the long-range dipolar interaction, we derive the Kirkwood-Fröhlich formula for the polarization fluctuations when the specimen volume v is much smaller than V. However, for not small v/V, the homogeneous part comes into play in dielectric relations. We also calculate the distribution of Ek (loc) in applied field. As a unique feature of water, its magnitude |Ek (loc)| obeys a Gaussian distribution with a large mean value E0 ≅ 17 V/nm, which arises mainly from the surrounding hydrogen-bonded molecules. Since |μk|E0 ∼ 30kBT, μk becomes mostly parallel to Ek (loc). As a result, the orientation distributions of these two vectors nearly coincide, assuming the classical exponential form. In dynamics, the component of μk(t) parallel to Ek (loc)(t) changes on the time scale of the hydrogen bonds ∼5 ps, while its smaller perpendicular component undergoes librational motions on time scales of 0.01 ps.

Non-linear Membrane Properties in Entorhinal Cortical Stellate Cells Reduce Modulation of Input-Output Responses by Voltage Fluctuations

Science.gov (United States)

Fernandez, Fernando R.; Malerba, Paola; White, John A.

2015-01-01

The presence of voltage fluctuations arising from synaptic activity is a critical component in models of gain control, neuronal output gating, and spike rate coding. The degree to which individual neuronal input-output functions are modulated by voltage fluctuations, however, is not well established across different cortical areas. Additionally, the extent and mechanisms of input-output modulation through fluctuations have been explored largely in simplified models of spike generation, and with limited consideration for the role of non-linear and voltage-dependent membrane properties. To address these issues, we studied fluctuation-based modulation of input-output responses in medial entorhinal cortical (MEC) stellate cells of rats, which express strong sub-threshold non-linear membrane properties. Using in vitro recordings, dynamic clamp and modeling, we show that the modulation of input-output responses by random voltage fluctuations in stellate cells is significantly limited. In stellate cells, a voltage-dependent increase in membrane resistance at sub-threshold voltages mediated by Na+ conductance activation limits the ability of fluctuations to elicit spikes. Similarly, in exponential leaky integrate-and-fire models using a shallow voltage-dependence for the exponential term that matches stellate cell membrane properties, a low degree of fluctuation-based modulation of input-output responses can be attained. These results demonstrate that fluctuation-based modulation of input-output responses is not a universal feature of neurons and can be significantly limited by subthreshold voltage-gated conductances. PMID:25909971

Review of electric discharge microplasmas generated in highly fluctuating fluids: Characteristics and application to nanomaterials synthesis

International Nuclear Information System (INIS)

Stauss, Sven; Terashima, Kazuo; Muneoka, Hitoshi; Urabe, Keiichiro

2015-01-01

Plasma-based fabrication of novel nanomaterials and nanostructures is indispensible for the development of next-generation electronic devices and for green energy applications. In particular, controlling the interactions between plasmas and materials interfaces, and the plasma fluctuations, is crucial for further development of plasma-based processes and bottom-up growth of nanomaterials. Electric discharge microplasmas generated in supercritical fluids represent a special class of high-pressure plasmas, where fluctuations on the molecular scale influence the discharge properties and the possible bottom-up growth of nanomaterials. This review discusses an anomaly observed for direct current microplasmas generated near the critical point, a local decrease in the breakdown voltage. This anomalous behavior is suggested to be caused by the concomitant decrease of the ionization potential due to the formation of clusters near the critical point, and the formation of extended electron mean free paths caused by the high-density fluctuation near the critical point. It is also shown that in the case of dielectric barrier microdischarges generated close to the critical point, the high-density fluctuation of the supercritical fluid persists. The final part of the review discusses the application of discharges generated in supercritical fluids to synthesis of nanomaterials, in particular, molecular diamond—so-called diamondoids—by microplasmas generated inside conventional batch-type and continuous flow microreactors

Characterization of Alfvenic fluctuations in the magnetopause boundary layer

International Nuclear Information System (INIS)

Rezeau, L.; Morane, A.; Perraut, S.; Roux, A.; Schmidt, R.

1989-01-01

The European Space Agency GEOS 2 spacecraft happened to cross the magnetopause several times, at various local times. Intense electric and magnetic fluctuations, in the ultralow-frequency (ULF) range (0-10 Hz) have been detected during each such crossing, with a peak at the magnetopause and still large amplitudes in the adjacent magnetosheath and magnetopause boundary layer. By applying spectral analysis and correlations to the electric and magnetic fluctuations, and a minimum variance analysis to the magnetic fluctuations, the authors investigate the nature of these fluctuations which appear as short-lasting bursts in the spacecraft frame. Having reviewed possible interpretations, they show that the observed electric and magnetic signatures are consistent with small-scale (L ∼ ion Larmor radius) Alfvenic field-aligned structures passing by the spacecraft at high speed. It is suggested that these structures correspond to nonlinear Alfvenic structures

Nonequilibrium fluctuations in a resistor.

Science.gov (United States)

Garnier, N; Ciliberto, S

2005-06-01

In small systems where relevant energies are comparable to thermal agitation, fluctuations are of the order of average values. In systems in thermodynamical equilibrium, the variance of these fluctuations can be related to the dissipation constant in the system, exploiting the fluctuation-dissipation theorem. In nonequilibrium steady systems, fluctuations theorems (FT) additionally describe symmetry properties of the probability density functions (PDFs) of the fluctuations of injected and dissipated energies. We experimentally probe a model system: an electrical dipole driven out of equilibrium by a small constant current I, and show that FT are experimentally accessible and valid. Furthermore, we stress that FT can be used to measure the dissipated power P = R I2 in the system by just studying the PDFs' symmetries.

General description of magnetic fluctuations in TEXT

International Nuclear Information System (INIS)

Kim, Y.J.

1989-01-01

The magnetic fluctuations in TEXT (R = 1m, a = 0.26m, ohmically heated tokamak with a full poloidal limiter) have been extensively measured with magnetic probes in the shadow of the limiter with an instrumental range of f -1 (m rms p (f > 50kHz) at the limiter radius is found to be of order 10 -5 T, which is too small to produce significant transport directly. Over the range of discharge parameters in TEXT, the B rms p (f > 50kHz) is observed to have a strong q a dependence (q a -2.2 ) and also a density dependence (n eo -0.8 ). Furthermore, the magnetic fluctuations show a significant correlation with edge electrostatic density fluctuations measured by Langmiur probe inside the limiter radius, and extending along magnetic field lines. Phase variation of the correlated components suggests k double-prime/k perpendicular ∼ 0.005. The B p rms (f >50kHz) is also found to be little dependent on parallel electric field E double-prime. Magnetic fluctuations in both low and high frequency ranges have been characterized by their response to gas puffing, pellet injection, impurity injection, and the effect of an ergodic magnetic limiter. The behavior of magnetic fluctuations with electron cyclotron resonance heating (ECRH) has been also investigated in detail

On the motion of electrons in the slow electric field fluctuations observed by Viking

International Nuclear Information System (INIS)

Hultqvist, B.

1991-01-01

Results are presented of calculations of the motion of electrons in slow, large-amplitude fluctuations of the electric field, which have been observed by means of the Swedish satellite Viking. The E component seen by the ionospheric electrons, entering the acceleration region from below, is assumed to vary along the path of the electrons along the magnetic field lines in the way that Viking recorded along its more or less horizontal path through, or above, the acceleration region. Although this is a simplified model, it is expected to illustrate the effect of the E parallel fluctuations on the cold electrons, which enter the acceleration region more realistically than in the earlier, highly simplified model used by hultqvist (1988). The results of the calculations show that temporal variations of E parallel of the kind observed by Viking easily can bring the electrons to the top of an acceleration region, which extends 1,000-10,000 km along the magnetic field lines, with energies in the range 100 eV to several keV, as have been observed

Quantum fluctuations

International Nuclear Information System (INIS)

Reynaud, S.; Giacobino, S.; Zinn-Justin, J.

1997-01-01

This course is dedicated to present in a pedagogical manner the recent developments in peculiar fields concerned by quantum fluctuations: quantum noise in optics, light propagation through dielectric media, sub-Poissonian light generated by lasers and masers, quantum non-demolition measurements, quantum electrodynamics applied to cavities and electrical circuits involving superconducting tunnel junctions. (A.C.)

Fluctuations of order parameters in the high Tc superconductors

International Nuclear Information System (INIS)

Das, M.P.; Saif, A.G.

1987-07-01

Recently we have proposed a phenomenological approach in terms of two coexisting macroscopic order parameters corresponding to the superconducting and insulating states and have discussed the electrodynamical responses of the superconducting ceramics. In this paper we discuss the fluctuations of the order parameters both in the static and in the dynamical situations in the mean field approach and obtain results for the electrical conductivity which possesses anomalies as in granular materials. (author). 22 refs

Control of the electromagnetic drag using fluctuating light fields

Science.gov (United States)

Pastor, Víctor J. López; Marqués, Manuel I.

2018-05-01

An expression for the electromagnetic drag force experienced by an electric dipole in a light field consisting of a monochromatic plane wave with polarization and phase randomly fluctuating is obtained. The expression explicitly considers the transformations of the field and frequency due to the Doppler shift and the change of the polarizability response of the electric dipole. The conditions to be fulfilled by the polarizability of the dipole in order to obtain a positive, a null, and a negative drag coefficient are analytically determined and checked against numerical simulations for the dynamics of a silver nanoparticle. The theoretically predicted diffusive, superdiffusive, and exponentially accelerated dynamical regimes are numerically confirmed.

Wavenumber-frequency Spectra of Pressure Fluctuations Measured via Fast Response Pressure Sensitive Paint

Science.gov (United States)

Panda, J.; Roozeboom, N. H.; Ross, J. C.

2016-01-01

The recent advancement in fast-response Pressure-Sensitive Paint (PSP) allows time-resolved measurements of unsteady pressure fluctuations from a dense grid of spatial points on a wind tunnel model. This capability allows for direct calculations of the wavenumber-frequency (k-?) spectrum of pressure fluctuations. Such data, useful for the vibro-acoustics analysis of aerospace vehicles, are difficult to obtain otherwise. For the present work, time histories of pressure fluctuations on a flat plate subjected to vortex shedding from a rectangular bluff-body were measured using PSP. The light intensity levels in the photographic images were then converted to instantaneous pressure histories by applying calibration constants, which were calculated from a few dynamic pressure sensors placed at selective points on the plate. Fourier transform of the time-histories from a large number of spatial points provided k-? spectra for pressure fluctuations. The data provides first glimpse into the possibility of creating detailed forcing functions for vibro-acoustics analysis of aerospace vehicles, albeit for a limited frequency range.

Fluctuations of two-time quantities and non-linear response functions

International Nuclear Information System (INIS)

Corberi, F; Lippiello, E; Sarracino, A; Zannetti, M

2010-01-01

We study the fluctuations of the autocorrelation and autoresponse functions and, in particular, their variances and covariance. In a first general part of the paper, we show the equivalence of the variance of the response function to the second-order susceptibility of a composite operator, and we derive an equilibrium fluctuation-dissipation theorem beyond linear order, relating it to the other variances. In a second part of the paper we apply the formalism in the study of non-disordered ferromagnets, in equilibrium or in the coarsening kinetics following a critical or sub-critical quench. We show numerically that the variances and the non-linear susceptibility obey scaling with respect to the coherence length ξ in equilibrium, and with respect to the growing length L(t) after a quench, similar to what is known for the autocorrelation and the autoresponse functions

Similar simulation study on the characteristics of the electric potential response to coal mining

Science.gov (United States)

Niu, Yue; Li, Zhonghui; Kong, Biao; Wang, Enyuan; Lou, Quan; Qiu, Liming; Kong, Xiangguo; Wang, Jiali; Dong, Mingfu; Li, Baolin

2018-02-01

An electric potential (EP) can be generated during the failure process of coal and rock. In this article, a similar physical model of coal rock was built and the characteristics of the EP responding to the process of coal mining were studied. The results showed that, at the early mining stage, the structure of coal rock strata were stable in the simulation model, the support stress of overlying coal rock strata was low and the maximum subsidence was little, while the EP change was less. With the advancement of the working face, the support stress of the overlying coal rock strata in the mined-out area changed dramatically, the maximum subsidence increased constantly, the deformation and destruction were aggravated, and cracks expanded continuously. Meanwhile, the EP response was significant with fluctuation. When significant macro damage appeared in coal rock strata, the EP signal fluctuation was violent. The overlying coal rock strata were influenced by gravity and mining activity. During the mining process, the crack growth and the friction, together with slip between coal and rock particles, resulted in the response of EP. The change in EP was closely related to the damage state and stress distribution of the coal rock strata. EP monitoring has the advantages of accurate reflection and strong anti-interference in the field. Therefore, with further study, an EP monitoring method could be applied for monitoring and early warning of coal and rock dynamic disaster, and risk evaluation in the future. The strength of the EP and its fluctuation degree could serve as the key discrimination indexes.

Fluctuations and thermodynamic response functions in a Lennard-Jones solid

International Nuclear Information System (INIS)

Li, M.; Johnson, W.L.

1992-01-01

Thermodynamic response functions of a nearest-neighbor Lennard-Jones solid--heat capacity, thermal-expansion coefficient, compressibility, and elastic constants--are calculated directly from fluctuations using molecular-dynamics simulations. The algorithm used is the earlier Parrinello-Rahman molecular dynamics modified to take into account symmetry and rotation invariance of the system under investigation. The convergence is very fast and results are in good agreement with existing Monte Carlo and molecular-dynamics results

Pulsed Neutron Scattering Studies of Strongly Fluctuating solids, Final Report

Energy Technology Data Exchange (ETDEWEB)

Collin Broholm

2006-06-22

The conventional description of a solid is based on a static atomic structure with small amplitude so-called harmonic fluctuations about it. This is a final technical report for a project that has explored materials where fluctuations are sufficiently strong to severely challenge this approach and lead to unexpected and potentially useful materials properties. Fluctuations are enhanced when a large number of configurations share the same energy. We used pulsed spallation source neutron scattering to obtain detailed microscopic information about structure and fluctuations in such materials. The results enhance our understanding of strongly fluctuating solids and their potential for technical applications. Because new materials require new experimental techniques, the project has also developed new techniques for probing strongly fluctuating solids. Examples of material that were studied are ZrW2O8 with large amplitude molecular motion that leads to negative thermal expansion, NiGa2S4 where competing interactions lead to an anomalous short range ordered magnet, Pr1- xBixRu2O7 where a partially filled electron shell (Pr) in a weakly disordered environment produces anomalous metallic properties, and TbMnO3 where competing interactions lead to a magneto-electric phase. The experiments on TbMnO3 exemplify the relationship between research funded by this project and future applications. Magneto-electric materials may produce a magnetic field when an electric field is applied or vise versa. Our experiments have clarified the reason why electric and magnetic polarization is coupled in TbMnO3. While this knowledge does not render TbMnO3 useful for applications it will focus the search for a practical room temperature magneto-electric for applications.

Manipulating lightcone fluctuations in an analogue cosmic string

Directory of Open Access Journals (Sweden)

Jiawei Hu

2018-02-01

Full Text Available We study the flight time fluctuations in an anisotropic medium inspired by a cosmic string with an effective fluctuating refractive index caused by fluctuating vacuum electric fields, which are analogous to the lightcone fluctuations due to fluctuating spacetime metric when gravity is quantized. The medium can be realized as a metamaterial that mimics a cosmic string in the sense of transformation optics. For a probe light close to the analogue string, the flight time variance is ν times that in a normal homogeneous and isotropic medium, where ν is a parameter characterizing the deficit angle of the spacetime of a cosmic string. The parameter ν, which is always greater than unity for a real cosmic string, is determined by the dielectric properties of the metamaterial for an analogue string. Therefore, the flight time fluctuations of a probe light can be manipulated by changing the electric permittivity and magnetic permeability of the analogue medium. We argue that it seems possible to fabricate a metamaterial that mimics a cosmic string with a large ν in laboratory so that a currently observable flight time variance might be achieved.

Manipulating lightcone fluctuations in an analogue cosmic string

Science.gov (United States)

Hu, Jiawei; Yu, Hongwei

2018-02-01

We study the flight time fluctuations in an anisotropic medium inspired by a cosmic string with an effective fluctuating refractive index caused by fluctuating vacuum electric fields, which are analogous to the lightcone fluctuations due to fluctuating spacetime metric when gravity is quantized. The medium can be realized as a metamaterial that mimics a cosmic string in the sense of transformation optics. For a probe light close to the analogue string, the flight time variance is ν times that in a normal homogeneous and isotropic medium, where ν is a parameter characterizing the deficit angle of the spacetime of a cosmic string. The parameter ν, which is always greater than unity for a real cosmic string, is determined by the dielectric properties of the metamaterial for an analogue string. Therefore, the flight time fluctuations of a probe light can be manipulated by changing the electric permittivity and magnetic permeability of the analogue medium. We argue that it seems possible to fabricate a metamaterial that mimics a cosmic string with a large ν in laboratory so that a currently observable flight time variance might be achieved.

Effects of the amplitude and frequency of salinity fluctuations on antioxidant responses in juvenile tongue sole, Cynoglossus semilaevis

Energy Technology Data Exchange (ETDEWEB)

Khairnar, S.A.; Tian, X.; Dong, S.; Fang, Z.; Solanki, B.V.; Shanthanagouda, H.A.

2016-11-01

To understand the tolerance of tongue sole, Cynoglossus semilaevis, to varying salinities, the effects of the amplitude (2, 4, 6 and 8 g/L) and frequency (2, 4 and 8 days) of salinity fluctuations on the activities of antioxidant responses, including acidic phosphatase (ACP), alkaline phosphatase (AKP), catalase (CAT) and superoxide dismutase (SOD) from antioxidant system in liver, muscle, gills and kidney were investigated in this study. The results showed that the antioxidant responses of tongue sole were highly tissue-specific during the varying salinity fluctuations. In all tissues, ACP and AKP activity was found to be highest at moderate salinity fluctuations compared to the control, low and high salinity treatments (p<0.05). SOD and CAT activities had significant effect due to salinity fluctuations in all tissues (p<0.05), except in hepatic and renal tissues. Variations in branchial SOD activity proved that salinity fluctuations had greater impact on tongue sole at moderate and high fluctuating salinities compared to the control and low fluctuating salinities, whereas the branchial CAT activities showed contrasting trend. Further, cortisol levels were significantly affected in lower and higher salinity fluctuations. However, plasma cortisol levels remained low in moderate salinity fluctuations and control (p<0.05). Taken together, the results indicated that salinity fluctuations could effectively stimulate and enhance the antioxidant enzyme activity in the liver, kidney, gills and muscle of the juvenile tongue sole, thus effectively eliminating the excessive reactive oxygen species and minimizing the body damage in tongue sole or could be for any other euryhaline teleosts. (Author)

An analog model for quantum lightcone fluctuations in nonlinear optics

International Nuclear Information System (INIS)

Ford, L.H.; De Lorenci, V.A.; Menezes, G.; Svaiter, N.F.

2013-01-01

We propose an analog model for quantum gravity effects using nonlinear dielectrics. Fluctuations of the spacetime lightcone are expected in quantum gravity, leading to variations in the flight times of pulses. This effect can also arise in a nonlinear material. We propose a model in which fluctuations of a background electric field, such as that produced by a squeezed photon state, can cause fluctuations in the effective lightcone for probe pulses. This leads to a variation in flight times analogous to that in quantum gravity. We make some numerical estimates which suggest that the effect might be large enough to be observable. - Highlights: ► Lightcone fluctuations, quantum fluctuations of the effective speed of light, are a feature of quantum gravity. ► Nonlinear dielectrics have a variable speed of light, analogous to the effects of gravity. ► Fluctuating electric fields create the effect of lightcone fluctuations in a nonlinear material. ► We propose to use squeezed light in a nonlinear material as an analog model of lightcone fluctuations. ► Variation in the speed of propagation of pulses is the observational signature of lightcone fluctuations.

Option value of electricity demand response

Energy Technology Data Exchange (ETDEWEB)

Sezgen, Osman; Goldman, C.A. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720 (United States); Krishnarao, P. [Citigroup Energy Inc., 1301 Fannin St, Houston, TX 77002 (United States)

2007-02-15

As electricity markets deregulate and energy tariffs increasingly expose customers to commodity price volatility, it is difficult for energy consumers to assess the economic value of investments in technologies that manage electricity demand in response to changing energy prices. The key uncertainties in evaluating the economics of demand-response technologies are the level and volatility of future wholesale energy prices. In this paper, we demonstrate that financial engineering methodologies originally developed for pricing equity and commodity derivatives (e.g., futures, swaps, options) can be used to estimate the value of demand-response technologies. We adapt models used to value energy options and assets to value three common demand-response strategies: load curtailment, load shifting or displacement, and short-term fuel substitution-specifically, distributed generation. These option models represent an improvement to traditional discounted cash flow methods for assessing the relative merits of demand-side technology investments in restructured electricity markets. (author)

Option value of electricity demand response

International Nuclear Information System (INIS)

Sezgen, Osman; Goldman, C.A.; Krishnarao, P.

2007-01-01

As electricity markets deregulate and energy tariffs increasingly expose customers to commodity price volatility, it is difficult for energy consumers to assess the economic value of investments in technologies that manage electricity demand in response to changing energy prices. The key uncertainties in evaluating the economics of demand-response technologies are the level and volatility of future wholesale energy prices. In this paper, we demonstrate that financial engineering methodologies originally developed for pricing equity and commodity derivatives (e.g., futures, swaps, options) can be used to estimate the value of demand-response technologies. We adapt models used to value energy options and assets to value three common demand-response strategies: load curtailment, load shifting or displacement, and short-term fuel substitution-specifically, distributed generation. These option models represent an improvement to traditional discounted cash flow methods for assessing the relative merits of demand-side technology investments in restructured electricity markets. (author)

Measurement of amplitude fluctuations in a rapid response photomultiplier; Mesure des fluctuations d'amplitude d'un photo multiplicateur a reponse rapide

Energy Technology Data Exchange (ETDEWEB)

Raimbault, P [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1961-07-01

In order to measure amplitude fluctuations in a rapid response photomultiplier, two independent random variables are introduced which determine the shape of the anode pulse. The energy of each pulse, which depends directly on the gain and the variance, is the first variable; amplitude fluctuations, functions of the first variable, depend as well on the pulse width which in turn constitutes the second variable. The results obtained on the variations of the maximum impulse, using a steep-edged pulse broadening circuit, and those obtained on the statistical variations of the gain, are compared to show that the variance relative to the maximum amplitude of the signal is greater than that of the gain. Within the limits of these fluctuations are shown the contribution of the secondary emission coefficient of the first dynode, and that of the mean secondary emission coefficient of the multiplier. (author) [French] Pour etudier les fluctuations d'amplitude d'un photomultiplicateur a reponse rapide, on introduit deux variables aleatoires independantes qui determinent la forme de l'impulsion anodique. L'energie de chaque impulsion, directement fonction du gain et de sa variance, est la premiere variable; les fluctuations d'amplitude, fonctions de la premiere variable, dependent egalement de la largeur de l'impulsion qui, elle, constitue la deuxieme variable. Les resultats obtenus sur les variations de l'amplitude maximale, a l'aide d'un circuit elargisseur d'impulsions a front raide, et les resultats des variations statistiques du gain sont compares pour mettre en evidence le fait que la variance relative a l'amplitude maximale du signal est plus grande que celle du gain. Dans la mesure de ces fluctuations, sont mises en evidence la contribution du coefficient d'emission secondaire de la premiere dynode et celle du coefficient d'emission secondaire moyen du multiplicateur. (auteur)

Risk hedging against the fuel price fluctuation in energy service business

International Nuclear Information System (INIS)

Bannai, Masaaki; Tomita, Yasushi; Ishida, Yasushi; Miyazaki, Takahiko; Akisawa, Atsushi; Kashiwagi, Takao

2007-01-01

Energy service business, or energy service company (ESCO), is expanding among industrial users as a means of energy saving. The ESCO business normally tends to become a long-term operation. During the operation, fluctuations of fuel and electricity costs significantly impact on the stability of the profit from ESCO business. Therefore, it is essential to reduce the risk of fuel and electricity cost fluctuations. Generally, a transaction called ''financial derivative'' is used as a measure of hedging against the fuel price fluctuation. In the case of ESCO business, it is necessary to manage the risk of both electricity and fuel price fluctuations because the variation in electricity price strongly affects the profit from ESCO as that in fuel price does. In this paper, the stabilization of the ESCO profit using financial derivatives was discussed by quantitative analyses of the actual data from existing plants. Case studies revealed that the appropriate volume of the fuel derivative implementation was less than a half of the fuel consumption at the ESCO facilities, and it ranged from 5% to 50%. (author)

Ongoing activity in temporally coherent networks predicts intra-subject fluctuation of response time to sporadic executive control demands.

Science.gov (United States)

Nozawa, Takayuki; Sugiura, Motoaki; Yokoyama, Ryoichi; Ihara, Mizuki; Kotozaki, Yuka; Miyauchi, Carlos Makoto; Kanno, Akitake; Kawashima, Ryuta

2014-01-01

Can ongoing fMRI BOLD signals predict fluctuations in swiftness of a person's response to sporadic cognitive demands? This is an important issue because it clarifies whether intrinsic brain dynamics, for which spatio-temporal patterns are expressed as temporally coherent networks (TCNs), have effects not only on sensory or motor processes, but also on cognitive processes. Predictivity has been affirmed, although to a limited extent. Expecting a predictive effect on executive performance for a wider range of TCNs constituting the cingulo-opercular, fronto-parietal, and default mode networks, we conducted an fMRI study using a version of the color-word Stroop task that was specifically designed to put a higher load on executive control, with the aim of making its fluctuations more detectable. We explored the relationships between the fluctuations in ongoing pre-trial activity in TCNs and the task response time (RT). The results revealed the existence of TCNs in which fluctuations in activity several seconds before the onset of the trial predicted RT fluctuations for the subsequent trial. These TCNs were distributed in the cingulo-opercular and fronto-parietal networks, as well as in perceptual and motor networks. Our results suggest that intrinsic brain dynamics in these networks constitute "cognitive readiness," which plays an active role especially in situations where information for anticipatory attention control is unavailable. Fluctuations in these networks lead to fluctuations in executive control performance.

Fluctuations of the peak current of tunnel diodes in multi-junction solar cells

International Nuclear Information System (INIS)

Jandieri, K; Baranovskii, S D; Stolz, W; Gebhard, F; Guter, W; Hermle, M; Bett, A W

2009-01-01

Interband tunnel diodes are widely used to electrically interconnect the individual subcells in multi-junction solar cells. Tunnel diodes have to operate at high current densities and low voltages, especially when used in concentrator solar cells. They represent one of the most critical elements of multi-junction solar cells and the fluctuations of the peak current in the diodes have an essential impact on the performance and reliability of the devices. Recently we have found that GaAs tunnel diodes exhibit extremely high peak currents that can be explained by resonant tunnelling through defects homogeneously distributed in the junction. Experiments evidence rather large fluctuations of the peak current in the diodes fabricated from the same wafer. It is a challenging task to clarify the reason for such large fluctuations in order to improve the performance of the multi-junction solar cells. In this work we show that the large fluctuations of the peak current in tunnel diodes can be caused by relatively small fluctuations of the dopant concentration. We also show that the fluctuations of the peak current become smaller for deeper energy levels of the defects responsible for the resonant tunnelling.

Price-elastic demand in deregulated electricity markets

OpenAIRE

Siddiqui, Afzal S.

2003-01-01

The degree to which any deregulated market functions efficiently often depends on the ability of market agents to respond quickly to fluctuating conditions. Many restructured electricity markets, however, experience high prices caused by supply shortages and little demand-side response. We examine the implications for market operations when a risk-averse retailer's end-use consumers are allowed to perceive real-time variations in the electricity spot price. Using a market-equilibrium mo...

Pore Pressure Response to Groundwater Fluctuations in Saturated Double-Layered Soil

Directory of Open Access Journals (Sweden)

Hongwei Ying

2015-01-01

Full Text Available Analytical solutions are developed for one-dimensional consolidation of double-layered saturated soil subjected to groundwater fluctuations. The solutions are derived by an explicit mathematical procedure using Duhamel’s theorem in conjunction with a Fourier series, when groundwater fluctuation is described by a general time-dependent function and assumed to be the pore water pressure variations at the upper boundary. Taking as an example the harmonic groundwater fluctuation, the relevant response of the excess pore water pressure is discussed in detail, and the main influencing factors of the excess pore pressure distribution are analyzed. A dimensionless parameter θ has been introduced because it significantly affects the phase and the amplitude of excess pore pressures. The influences of the coefficients of permeability and compressibility of soil on the excess pore pressure distribution are different and cannot be incorporated into the coefficient of consolidation in double-layered soil. The relative permeability ratio of two clayey soils also plays an important role on the curves of the distributions of the excess pore pressures. The effects of the thickness of the soil layer on the excess pore pressure distribution should be considered together with the dimensionless parameter θ and the permeability and compressibility of the double-layered soil system.

Ordinary mode reflectometry. Modification of the scattering and cut-off responses due to the shape of localized density fluctuations

International Nuclear Information System (INIS)

Fanack, C.; Boucher, I.; Heuraux, S.; Leclert, G.; Clairet, F.; Zou, X.L.

1996-01-01

Ordinary wave reflectometry in a plasma containing a localized density perturbation is studied with a 1-D model. The phase response is studied as a function of the wavenumber and position of the perturbation. It is shown that it strongly depends upon the perturbation shape and size. For a small perturbation wavenumber, the response is due to the oscillation of the cut-off layer. For larger wavenumbers, two regimes are found: for a broad perturbation, the phase response is an image of the perturbation itself; for a narrow perturbation, it is rather an image of the Fourier transform. For tokamak plasmas it turns out that, for the fluctuation spectra usually observed, the phase response comes primarily from those fluctuations that are localized at the cut-off. Results of a 2-D numerical model show that geometry effects are negligible for the scattering by radial fluctuations. (author)

Spin fluctuation and small polaron conduction dominated electrical ...

Indian Academy of Sciences (India)

Administrator

temperature regime (20 K < T < 53 K), shows a minima near 53 K and increases with T ... Manganite nanoparticles; resistivity; spin fluctuation; electron–phonon interaction; electron– ... the low-doped regime because of the series of structural,.

Ferroelectric glass of spheroidal dipoles with impurities: polar nanoregions, response to applied electric field, and ergodicity breakdown

International Nuclear Information System (INIS)

Takae, Kyohei; Onuki, Akira

2017-01-01

Using molecular dynamics simulation, we study dipolar glass in crystals composed of slightly spheroidal, polar particles and spherical, apolar impurities between metal walls. We present physical pictures of ferroelectric glass, which have been observed in relaxors, mixed crystals (such as KCN x KBr 1−x ), and polymers. Our systems undergo a diffuse transition in a wide temperature range, where we visualize polar nanoregions (PNRs) surrounded by impurities. In our simulation, the impurities form clusters and their space distribution is heterogeneous. The polarization fluctuations are enhanced at relatively high T depending on the size of the dipole moment. They then form frozen PNRs as T is further lowered into the nonergodic regime. As a result, the dielectric permittivity exhibits the characteristic features of relaxor ferroelectrics. We also examine nonlinear response to cyclic applied electric field and nonergodic response to cyclic temperature changes (ZFC/FC), where the polarization and the strain change collectively and heterogeneously. We also study antiferroelectric glass arising from molecular shape asymmetry. We use an Ewald scheme of calculating the dipolar interaction in applied electric field. (paper)

Equilibrium fluctuation energy of gyrokinetic plasma

International Nuclear Information System (INIS)

Krommes, J.A.; Lee, W.W.; Oberman, C.

1985-11-01

The thermal equilibrium electric field fluctuation energy of the gyrokinetic model of magnetized plasma is computed, and found to be smaller than the well-known result (k)/8π = 1/2T/[1 + (klambda/sub D/) 2 ] valid for arbitrarily magnetized plasmas. It is shown that, in a certain sense, the equilibrium electric field energy is minimum in the gyrokinetic regime. 13 refs., 2 figs

The Spectrum of Wind Power Fluctuations

Science.gov (United States)

Bandi, Mahesh

2016-11-01

Wind is a variable energy source whose fluctuations threaten electrical grid stability and complicate dynamical load balancing. The power generated by a wind turbine fluctuates due to the variable wind speed that blows past the turbine. Indeed, the spectrum of wind power fluctuations is widely believed to reflect the Kolmogorov spectrum; both vary with frequency f as f - 5 / 3. This variability decreases when aggregate power fluctuations from geographically distributed wind farms are averaged at the grid via a mechanism known as geographic smoothing. Neither the f - 5 / 3 wind power fluctuation spectrum nor the mechanism of geographic smoothing are understood. In this work, we explain the wind power fluctuation spectrum from the turbine through grid scales. The f - 5 / 3 wind power fluctuation spectrum results from the largest length scales of atmospheric turbulence of order 200 km influencing the small scales where individual turbines operate. This long-range influence spatially couples geographically distributed wind farms and synchronizes farm outputs over a range of frequencies and decreases with increasing inter-farm distance. Consequently, aggregate grid-scale power fluctuations remain correlated, and are smoothed until they reach a limiting f - 7 / 3 spectrum. This work was funded by the Collective Interactions Unit, OIST Graduate University, Japan.

Fuel Cells for Balancing Fluctuation Renewable Energy Sources

DEFF Research Database (Denmark)

Mathiesen, Brian Vad

2007-01-01

In the perspective of using fuel cells for integration of fluctuating renewable energy the SOFCs are the most promising. These cells have the advantage of significantly higher electricity efficiency than competing technologies and fuel flexibility. Fuel cells in general also have the advantage of...... with hydrogen production or electric cars, and on the other hand using biomass and bio fuels [11]. Fuel cells can have an important role in these future energy systems.......In the perspective of using fuel cells for integration of fluctuating renewable energy the SOFCs are the most promising. These cells have the advantage of significantly higher electricity efficiency than competing technologies and fuel flexibility. Fuel cells in general also have the advantage...... flexibility, such as SOFCs, heat pumps and heat storage technologies are more important than storing electricity as hydrogen via electrolysis in energy systems with high amounts of wind [12]. Unnecessary energy conversions should be avoided. However in future energy systems with wind providing more than 50...

Genetic evolution, plasticity, and bet-hedging as adaptive responses to temporally autocorrelated fluctuating selection: A quantitative genetic model.

Science.gov (United States)

Tufto, Jarle

2015-08-01

Adaptive responses to autocorrelated environmental fluctuations through evolution in mean reaction norm elevation and slope and an independent component of the phenotypic variance are analyzed using a quantitative genetic model. Analytic approximations expressing the mutual dependencies between all three response modes are derived and solved for the joint evolutionary outcome. Both genetic evolution in reaction norm elevation and plasticity are favored by slow temporal fluctuations, with plasticity, in the absence of microenvironmental variability, being the dominant evolutionary outcome for reasonable parameter values. For fast fluctuations, tracking of the optimal phenotype through genetic evolution and plasticity is limited. If residual fluctuations in the optimal phenotype are large and stabilizing selection is strong, selection then acts to increase the phenotypic variance (bet-hedging adaptive). Otherwise, canalizing selection occurs. If the phenotypic variance increases with plasticity through the effect of microenvironmental variability, this shifts the joint evolutionary balance away from plasticity in favor of genetic evolution. If microenvironmental deviations experienced by each individual at the time of development and selection are correlated, however, more plasticity evolves. The adaptive significance of evolutionary fluctuations in plasticity and the phenotypic variance, transient evolution, and the validity of the analytic approximations are investigated using simulations. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Nonlinear response in runoff magnitude to fluctuating rain patterns.

Science.gov (United States)

Curtu, R; Fonley, M

2015-03-01

The runoff coefficient of a hillslope is a reliable measure for changes in the streamflow response at the river link outlet. A high runoff coefficient is a good indicator of the possibility of flash floods. Although the relationship between runoff coefficient and streamflow has been the subject of much study, the physical mechanisms affecting runoff coefficient including the dependence on precipitation pattern remain open topics for investigation. In this paper, we analyze a rainfall-runoff model at the hillslope scale as that hillslope is forced with different rain patterns: constant rain and fluctuating rain with different frequencies and amplitudes. When an oscillatory precipitation pattern is applied, although the same amount of water may enter the system, its response (measured by the runoff coefficient) will be maximum for a certain frequency of precipitation. The significant increase in runoff coefficient after a certain pattern of rainfall can be a potential explanation for the conditions preceding flash-floods.

Analyses of demand response in Denmark[Electricity market

Energy Technology Data Exchange (ETDEWEB)

Moeller Andersen, F.; Grenaa Jensen, S.; Larsen, Helge V.; Meibom, P.; Ravn, H.; Skytte, K.; Togeby, M.

2006-10-15

Due to characteristics of the power system, costs of producing electricity vary considerably over short time intervals. Yet, many consumers do not experience corresponding variations in the price they pay for consuming electricity. The topic of this report is: are consumers willing and able to respond to short-term variations in electricity prices, and if so, what is the social benefit of consumers doing so? Taking Denmark and the Nord Pool market as a case, the report focuses on what is known as short-term consumer flexibility or demand response in the electricity market. With focus on market efficiency, efficient allocation of resources and security of supply, the report describes demand response from a micro-economic perspective and provides empirical observations and case studies. The report aims at evaluating benefits from demand response. However, only elements contributing to an overall value are presented. In addition, the analyses are limited to benefits for society, and costs of obtaining demand response are not considered. (au)

Earthworm responses to Cd and Cu under fluctuating environmental conditions: a comparison with results from laboratory exposures

International Nuclear Information System (INIS)

Spurgeon, David J.; Svendsen, Claus; Lister, Lindsay J.; Hankard, Peter K.; Kille, Peter

2005-01-01

Laboratory toxicity tests are usually conducted under stable ambient conditions, while exposures in ecosystems occur in a fluctuating climate. To assess how climate influences the toxicity of Cu and Cd for the earthworm Lumbricus rubellus, this study compared effects for life-cycle parameters (survival, reproduction), cellular status (lysosomal membrane stability), gene expression (transcript of the metal binding protein metallothionein-2) and tissue metal concentration measured under outdoor conditions, with the same responses under constant conditions as measured by Spurgeon et al. [Spurgeon, D.J., Svendsen, C., Weeks, J.M., Hankard, P.K., Stubberud, H.E., Kammenga, J.E., 2003. Quantifying copper and cadmium impacts on intrinsic rate of population increase in the terrestrial oligochaete Lumbricus rubellus. Environmental Toxicology and Chemistry 22, 1465-1472]. Both metals were found to significantly influence earthworm reproduction, compromise lysosomal membrane stability and induce MT-2 gene expression in the outdoor system. Comparison with physiological and life-cycle responses in the laboratory indicated similar response patterns and effect concentrations for Cu. For Cd, lysosomal membrane stability and MT-2expression showed comparable responses in both exposures. Juvenile production rate, however, gave different dose response relationships, with the EC- 50 in the outdoor test approximately half that in the laboratory test. A difference in Cd accumulation was also seen. Overall, however, the comparison indicated only a marginal effect of environmental fluctuations typical for northern temperate Europe on earthworm sensitivity to the two metals. - Comparative analysis of life-cycle, physiological and molecular responses to Cu and Cd indicate similar responses under static and fluctuating climate regimes

Management of fluctuations in wind power and CHP comparing two possible Danish strategies

International Nuclear Information System (INIS)

Lund, H.; Clark, W.W.

2002-01-01

Both CHP (combined heat and power production) and wind power are important elements of Danish energy policy. Today, approximately 50% of both the Danish electricity and heat demand are produced in CHP and more than 15% of the electricity demand is produced by wind turbines. Both technologies are essential for the implementation of Danish climate change response objectives, and both technologies are intended for further expansion in the coming decade. Meanwhile, the integration of CHP and wind power is subject to fluctuations in electricity production. Wind turbines depend on the wind, and CHP depends on the heat demand. This article discusses and analyses two different national strategies for solving this problem. One strategy, which is the current official government policy known as the export strategy, proposes to take advantage of the Nordic and European markets for selling and buying electricity. In this case, surplus electricity from wind power and CHP simply will be sold to neighbouring countries. Another strategy, the self-supply strategy, runs the CHP units to meet both demand and the fluctuations in the wind scheduling. In this case, investments in heat storages are necessary and heat pumps have to be added to the CHP units. Based on official Danish energy policy and energy plans, this article quantifies the problem for the year 2015 in terms of the amount of surplus electricity, and investments in heat pumps, etc. needed to solve the problem are calculated. Based on these results between the two different strategies, the conclusion is that the self-supply strategy is recommended over the official export strategy. (author)

Decoupling Analysis on Pressure Fluctuation and Needle Valve Response for High Pressure Common Rail Injector

Directory of Open Access Journals (Sweden)

Hao Wang

2017-01-01

Full Text Available In the process of multiple injections, the influence of different injections makes the controlling of cycle fuel injection quantity more difficult. The high pressure common rail (HPCR simulation model is established in AMESim environment. Through the method of combining numerical simulation and experiment test, it is found that the strong coupling of pressure fluctuation and needle valve response is the fundamental reason, which leads to the fluctuation of main injection fuel quantity (MIFQ with dwell time (DT. The result shows that the largest fluctuation quantity is 3.6mm3 when the reference value of main injection is 60.0mm3. Non-damping LC hydraulic system model is also established. Through the analysis of the model, reducing the length-diameter ratio of internal oil duct and the delivery chamber volume are decoupling methods to the strong coupling.

Consumer responses to time varying prices for electricity

International Nuclear Information System (INIS)

Thorsnes, Paul; Williams, John; Lawson, Rob

2012-01-01

We report new experimental evidence of the household response to weekday differentials in peak and off-peak electricity prices. The data come from Auckland, New Zealand, where peak residential electricity consumption occurs in winter for heating. Peak/off-peak price differentials ranged over four randomly selected groups from 1.0 to 3.5. On average, there was no response except in winter. In winter, participant households reduced electricity consumption by at least 10%, took advantage of lower off-peak prices but did not respond to the peak price differentials. Response varied with house and household size, time spent away from home, and whether water was heated with electricity. - Highlights: ► Seasonal effects in winter. ► High conservation effect from information. ► Higher peak prices no effect on peak use. ► Low off-peak prices encourage less conservation off-peak.

Escape routes, weak links, and desynchronization in fluctuation-driven networks

DEFF Research Database (Denmark)

Schäfer, Benjamin; Matthiae, Moritz; Zhang, Xiaozhu

2017-01-01

Shifting our electricity generation from fossil fuel to renewable energy sources introduces large fluctuations to the power system. Here, we demonstrate how increased fluctuations, reduced damping, and reduced intertia may undermine the dynamical robustness of power grid networks. Focusing...... on fundamental noise models, we derive analytic insights into which factors limit the dynamic robustness and how fluctuations may induce a system escape from an operating state. Moreover, we identify weak links in the grid that make it particularly vulnerable to fluctuations. These results thereby not only...

Effects of magnetic geometry, fluctuations, and electric fields on confinement in the Advanced Toroidal Facility

International Nuclear Information System (INIS)

Isler, R.C.; Aceto, S.; Baylor, L.R.; Bigelow, T.S.; Bell, G.L.; Bell, J.D.; Carreras, B.A.; Colchin, R.J.; Crume, E.C.; Dominguez, N.; Dory, R.A.; Dunlap, J.L.; Dyer, G.R.; England, A.C.; Gandy, R.F.; Glowienka, J.C.; Hanson, G.R.; Harris, J.H.; Hiroe, S.; Horton, L.D.; Jernigan, T.C.; Ji, H.; Langley, R.A.; Lee, D.K.; Likin, K.M.; Lyon, J.F.; Ma, C.H.; Morimoto, S.; Murakami, M.; Okada, H.; Qualls, A.L.; Rasmussen, D.A.; Rome, J.A.; Sato, M.; Schwelberger, J.G.; Shats, M.G.; Simpkins, J.E.; Thomas, C.E.; Uckan, T.; Wade, M.R.; Wilgen, J.B.; Wing, W.R.; Yamada, H.; Zielinski, J.J.

1992-01-01

Recent experiments in the Advanced Toroidal Facility (ATF) [Fusion Technol. 10, 179 (1986)] have been directed toward investigations of the basic physics mechanisms that control confinement in this device. Measurements of the density fluctuations throughout the plasma volume have provided indications for the existence of theoretically predicted dissipative trapped electron and resistive interchange instabilities. These identifications are supported by results of dynamic configuration scans of the magnetic fields during which the magnetic well volume, shear, and fraction of confined trapped particles are changed continuously. The influence of magnetic islands on the global confinement has been studied by deliberately applying error fields which strongly perturb the nested flux-surface geometry, and the effects of electric fields have been investigated by means of biased limiter experiments

Electronic zero-point fluctuation forces inside circuit components

Science.gov (United States)

Leonhardt, Ulf

2018-01-01

One of the most intriguing manifestations of quantum zero-point fluctuations are the van der Waals and Casimir forces, often associated with vacuum fluctuations of the electromagnetic field. We study generalized fluctuation potentials acting on internal degrees of freedom of components in electrical circuits. These electronic Casimir-like potentials are induced by the zero-point current fluctuations of any general conductive circuit. For realistic examples of an electromechanical capacitor and a superconducting qubit, our results reveal the possibility of tunable forces between the capacitor plates, or the level shifts of the qubit, respectively. Our analysis suggests an alternative route toward the exploration of Casimir-like fluctuation potentials, namely, by characterizing and measuring them as a function of parameters of the environment. These tunable potentials may be useful for future nanoelectromechanical and quantum technologies. PMID:29719863

Size effects in many-valley fluctuations in semiconductors

International Nuclear Information System (INIS)

Sokolov, V.N.; Kochelap, V.A.

1995-08-01

We present the results of theoretical investigations of nonhomogeneous fluctuations in submicron active regions of many-valley semiconductors with equivalent valleys(Ge, Si-type), where the dimension 2d of the region is comparable to or less than the intervalley diffusion relaxation length L iv . It is shown that for arbitrary orientations of the valley axes (the crystal axes) with respect to lateral sample surfaces, the fluctuation spectra depend on the bias voltage applied to the layer in the region of weak nonheating electric fields. The new physical phenomenon is reported: the fluctuation spectra depend on the sample thickness, with 2d iv the suppression of fluctuations arises for fluctuation frequencies ω -1 iv , τ -1 iv is the characteristic intervalley relaxation time. (author). 43 refs, 5 figs

Electronic zero-point fluctuation forces inside circuit components.

Science.gov (United States)

Shahmoon, Ephraim; Leonhardt, Ulf

2018-04-01

One of the most intriguing manifestations of quantum zero-point fluctuations are the van der Waals and Casimir forces, often associated with vacuum fluctuations of the electromagnetic field. We study generalized fluctuation potentials acting on internal degrees of freedom of components in electrical circuits. These electronic Casimir-like potentials are induced by the zero-point current fluctuations of any general conductive circuit. For realistic examples of an electromechanical capacitor and a superconducting qubit, our results reveal the possibility of tunable forces between the capacitor plates, or the level shifts of the qubit, respectively. Our analysis suggests an alternative route toward the exploration of Casimir-like fluctuation potentials, namely, by characterizing and measuring them as a function of parameters of the environment. These tunable potentials may be useful for future nanoelectromechanical and quantum technologies.

Price-elastic demand in deregulated electricity markets

Energy Technology Data Exchange (ETDEWEB)

Siddiqui, Afzal S.

2003-05-01

The degree to which any deregulated market functions efficiently often depends on the ability of market agents to respond quickly to fluctuating conditions. Many restructured electricity markets, however, experience high prices caused by supply shortages and little demand-side response. We examine the implications for market operations when a risk-averse retailer's end-use consumers are allowed to perceive real-time variations in the electricity spot price. Using a market-equilibrium model, we find that price elasticity both increases the retailers revenue risk exposure and decreases the spot price. Since the latter induces the retailer to reduce forward electricity purchases, while the former has the opposite effect, the overall impact of price responsive demand on the relative magnitudes of its risk exposure and end-user price elasticity. Nevertheless, price elasticity decreases cumulative electricity consumption. By extending the analysis to allow for early settlement of demand, we find that forward stage end-user price responsiveness decreases the electricity forward price relative to the case with price-elastic demand only in real time. Moreover, we find that only if forward stage end-user demand is price elastic will the equilibrium electricity forward price be reduced.

Fluctuation Reduction in a Si Micromechanical Resonator Tuned to Nonlinear Internal Resonance

Science.gov (United States)

Strachan, B. Scott; Czaplewski, David; Chen, Changyao; Dykman, Mark; Lopez, Daniel; Shaw, Steven

2015-03-01

We describe experimental and theoretical results on an unusual behavior of fluctuations when the system exhibits internal resonance. We study the fundamental flexural mode (FFM) of a Si microbeam. The FFM is electrically actuated and detected. It is resonantly nonlinearly coupled to another mode, which is not directly accessible and has a frequency nearly three times the FFM frequency. Both the FFM and the passive mode have long lifetimes. We find that the passive mode can be a ``sink'' for fluctuations of the FFM. This explains the recently observed dramatic decrease of these fluctuations at nonlinear resonance. The re-distribution of the vibration amplitudes and the fluctuations is reminiscent of what happens at level anti-crossing in quantum mechanics. However, here it is different because of interplay of the dependence of the vibration frequency of the FFM on its amplitude due to internal nonlinearity and the nonlinear resonance with the passive mode. We study both the response of the system to external resonant driving and also the behavior of the system in the presence of a feedback loop. The experimental and theoretical results are in good agreement.

Effects of confinement on the dielectric response of water extends up to mesoscale dimensions

DEFF Research Database (Denmark)

De Luca, Sergio; Kannam, Sridhar Kumar; Todd, B.D.

2016-01-01

of confined water under the influence of external electric fields along with the dipolar fluctuations at equilibrium. The confinement induces a strong anisotropic effect which is evident up to 100 nm channel width, and may extend to macroscopic dimensions. The root-mean-square fluctuations of the total...... dimensions. Consistent with dipole moment fluctuations, the effect of confinement on the dielectric response also persists up to channel widths considerably beyond 100 nm. When an electric field is applied in the perpendicular direction, the orientational relaxation is 3 orders of magnitude faster than...

A summary of demand response in electricity markets

International Nuclear Information System (INIS)

Albadi, M.H.; El-Saadany, E.F.

2008-01-01

This paper presents a summary of demand response (DR) in deregulated electricity markets. The definition and the classification of DR as well as potential benefits and associated cost components are presented. In addition, the most common indices used for DR measurement and evaluation are highlighted, and some utilities' experiences with different demand response programs are discussed. Finally, the effect of demand response in electricity prices is highlighted using a simulated case study. (author)

Hyper-Ramsey spectroscopy with probe-laser-intensity fluctuations

Science.gov (United States)

Beloy, K.

2018-03-01

We examine the influence of probe-laser-intensity fluctuations on hyper-Ramsey spectroscopy. We assume, as is appropriate for relevant cases of interest, that the probe-laser intensity I determines both the Rabi frequency (∝√{I } ) and the frequency shift to the atomic transition (∝I ) during probe-laser interactions with the atom. The spectroscopic signal depends on these two quantities that covary with fluctuations in the probe-laser intensity. Introducing a simple model for the fluctuations, we find that the signature robustness of the hyper-Ramsey method can be compromised. Taking the Yb+ electric octupole clock transition as an example, we quantify the clock error under different levels of probe-laser-intensity fluctuations.

Electrical Resistivity Imaging of Tidal Fluctuations in the Water Table at Inwood Hill Park, Manhattan

Science.gov (United States)

Kenyon, P. M.; Kassem, D.; Olin, A.; Nunez, J.; Smalling, A.

2005-05-01

Inwood Hill Park is located on the northern tip of Manhattan and has been extensively modified over the years by human activities. In its current form, it has a backbone of exposed or lightly covered bedrock along the Hudson River, adjacent to a flat area with two tidal inlets along the northern shore of Manhattan. The tidal motions in the inlets are expected to drive corresponding fluctuations in the water table along the borders of the inlets. In the Fall of 2002, a group of students from the Department of Earth and Atmospheric Sciences at the City College of New York studied these fluctuations. Electrical resistivity cross sections were obtained with a Syscal Kid Switch 24 resistivity meter during the course of a tidal cycle at three locations surrounding the westernmost inlet in the park. No change was seen over a tidal cycle at Site 1, possibly due to the effect of concrete erosion barriers which were located between the land and the water surrounding this site. Measurements at Site 2 revealed a small, regular change in the water table elevation of approximately 5 cm over the course of a tidal cycle. This site is inferred to rest on alluvial sediments deposited by a small creek. The cross sections taken at different times during a tidal cycle at Site 3 were the most interesting. They show a very heterogeneous subsurface, with water spurting between blocks of high resistivity materials during the rising portion of the cycle. A small sinkhole was observed on the surface of the ground directly above an obvious plume of water in the cross section. Park personnel confirmed that this sinkhole, like others scattered around this site, is natural and not due to recent construction activity. They also indicated that debris from the construction of the New York City subways may have been dumped in the area in the past. Our conclusion is that the tidal fluctuations at Site 3 are being channeled by solid blocks in the construction debris, and that the sinkholes currently

Temporal structure of aggregate power fluctuations in large-eddy simulations of extended wind-farms

NARCIS (Netherlands)

Stevens, Richard Johannes Antonius Maria; Meneveau, Charles

2014-01-01

Fluctuations represent a major challenge for the incorporation of electric power from large wind-farms into power grids. Wind-farm power output fluctuates strongly in time, over various time scales. Understanding these fluctuations, especially their spatio-temporal characteristics, is particularly

Molecules with an induced dipole moment in a stochastic electric field.

Science.gov (United States)

Band, Y B; Ben-Shimol, Y

2013-10-01

The mean-field dynamics of a molecule with an induced dipole moment (e.g., a homonuclear diatomic molecule) in a deterministic and a stochastic (fluctuating) electric field is solved to obtain the decoherence properties of the system. The average (over fluctuations) electric dipole moment and average angular momentum as a function of time for a Gaussian white noise electric field are determined via perturbative and nonperturbative solutions in the fluctuating field. In the perturbative solution, the components of the average electric dipole moment and the average angular momentum along the deterministic electric field direction do not decay to zero, despite fluctuations in all three components of the electric field. This is in contrast to the decay of the average over fluctuations of a magnetic moment in a Gaussian white noise magnetic field. In the nonperturbative solution, the component of the average electric dipole moment and the average angular momentum in the deterministic electric field direction also decay to zero.

[Effect of Transcutaneous Acupoint Electrical Stimulation on Hemodynamic Fluctuation Caused by Loosing Tourniquet in Elderly Patients Undergoing Knee Joint Replacement].

Science.gov (United States)

Liang, Han-Sheng; Feng, Yi

2017-12-25

To observe the effect of transcutaneous acupoint electrical stimulation (TAES) on hemodynamic fluctuation caused by loosing tourniquet in the elderly patients undergoing knee joint replacement. A total of 60 ASA (America Society Anesthesiologist) I or II elderly patients for elective knee joint replacement surgery were randomly divided into control group (30 cases) and TAES group (30 cases). Patients of both groups were treated by intravenous anesthesia, and monitored with bispectral index (BIS, between 45－60) for anesthesia depth, stroke volume variation (SVV) for fluid management, mean arterial pressure (MAP) and cardiac index (CI) for hemodynamic fluctuation evaluation, and with analgesia nociception index (ANI, between 50－70) for remifentanil dosage adjustment. TAES (2 Hz/100 Hz, 8－20 mA) was applied to bilateral Xinshu (BL 15), Feishu (BL 13), Neiguan (PC 6) and Hegu (LI 4) acupoints for 30 min first (followed by anesthesia induction and operation), and given continuously until 15 min after tourniquet loosing. Patients of the control group were only given with electrodes attachment without electrical stimulation. The levels of MAP, CI, and arterial blood pH, PaCO 2 , PaO 2 , base excess (BE) and lactic acid (Lac) 1 min before, and 5 and 15 min after tourniquet loosing, and the dosages of remifentanil and ephedrine after tourniquet loosing were recorded. The changed levels of MAP, CI and blood Lac at 5 min after tourniquet loosing (relevant to the baseline levels), and blood Lac content at 15 min after tourniquet loosing (relevant to 5 min after tourniquet loosing) were significantly lower in the TAES group than in the control group ( P 0.05). TAES has a positive effect on hemodynamics fluctuation caused by loosing tourniquet in the aged patients undergoing knee joint replacement.

Edge fluctuation studies in Heliotron J

International Nuclear Information System (INIS)

Mizuuchi, T.; Chechkin, V.V.; Ohashi, K.; Sorokovoy, E.L.; Chechkin, A.V.; Gonchar, V.Yu.; Takahashi, K.; Kobayashi, S.; Nagasaki, K.; Okada, H.; Yamamoto, S.; Sano, F.; Kondo, K.; Nishino, N.; Kawazome, H.; Shidara, H.; Kaneko, S.; Fukagawa, Y.; Morita, Y.; Nakazawa, S.; Nishio, S.; Tsuboi, S.; Yamada, M.

2005-01-01

Low frequency and small-scale fluctuations of density and potential near the last closed flux surface are investigated by using Langmuir probes for the second harmonic ECH plasmas in a helical-axis heliotron device, Heliotron J. The existence of a plasma layer with a radial electric field shear was indicated near the last closed flux surface. Near this layer, the reversal of phase velocity and de-correlation of the fluctuations were observed. On the other hand, it is suggested that a considerable fraction of the fluctuation induced particle flux is carried off through the intermittent events. Preliminary analyses to classify the PDFs of the ion-saturation current fluctuation as stable Levy distributions demonstrate that the Levy index decreases from the inner to the outer region of edge plasma, suggesting that the PDFs near the boundary region of Heliotron J are nearly Gaussian, whereas at the outer regions of plasma they become strongly non-Gaussian

Carbon Dioxide Fluctuations Are Associated with Changes in Cerebral Oxygenation and Electrical Activity in Infants Born Preterm.

Science.gov (United States)

Dix, Laura Marie Louise; Weeke, Lauren Carleen; de Vries, Linda Simone; Groenendaal, Floris; Baerts, Willem; van Bel, Frank; Lemmers, Petra Maria Anna

2017-08-01

To evaluate the effects of acute arterial carbon dioxide partial pressure changes on cerebral oxygenation and electrical activity in infants born preterm. This retrospective observational study included ventilated infants born preterm with acute fluctuations of continuous end-tidal CO 2 (etCO 2 ) as a surrogate marker for arterial carbon dioxide partial pressure, during the first 72 hours of life. Regional cerebral oxygen saturation and fractional tissue oxygen extraction were monitored with near-infrared spectroscopy. Brain activity was monitored with 2-channel electroencephalography. Spontaneous activity transients (SATs) rate (SATs/minute) and interval between SATs (in seconds) were calculated. Ten-minute periods were selected for analysis: before, during, and after etCO 2 fluctuations of ≥5  mm Hg. Thirty-eight patients (mean ± SD gestational age of 29 ± 1.8 weeks) were included, with 60 episodes of etCO 2 increase and 70 episodes of etCO 2 decrease. During etCO 2 increases, brain oxygenation increased (regional cerebral oxygen saturation increased, fractional tissue oxygen extraction decreased; P carbon dioxide partial pressure that may be harmful to the neonatal brain. Copyright © 2017 Elsevier Inc. All rights reserved.

Superconductivity and spin fluctuations

International Nuclear Information System (INIS)

Scalapino, D.J.

1999-01-01

The organizers of the Memorial Session for Herman Rietschel asked that the author review some of the history of the interplay of superconductivity and spin fluctuations. Initially, Berk and Schrieffer showed how paramagnon spin fluctuations could suppress superconductivity in nearly-ferromagnetic materials. Following this, Rietschel and various co-workers wrote a number of papers in which they investigated the role of spin fluctuations in reducing the Tc of various electron-phonon superconductors. Paramagnon spin fluctuations are also believed to provide the p-wave pairing mechanism responsible for the superfluid phases of 3 He. More recently, antiferromagnetic spin fluctuations have been proposed as the mechanism for d-wave pairing in the heavy-fermion superconductors and in some organic materials as well as possibly the high-Tc cuprates. Here the author will review some of this early history and discuss some of the things he has learned more recently from numerical simulations

Fluctuation analysis of rotational spectra

International Nuclear Information System (INIS)

Doessing, T.; Bracco, A.; Broglia, R.A.; Matsuo, M.

1996-01-01

The compound state rotational degree of freedom is ''damped'' in the sense that the electric quadrupole decay of a single quantum state with angular momentum I exhibits a spectrum of final states all having spin I-2. In actual experiments, the cascade of γ-rays associated with each of the members of the ensemble of compound nuclei uses each of the ''discrete'' transitions many more times than the ''continuum'' transitions. Relatively large and small fluctuations in the recorded coincidence spectrum ensue, respectively. The analysis of the fluctuations will be shown to be instrumental to gain insight into the phenomenon of rotational damping. For this purpose, two- and higher-fold coincidence spectra emitted from rotating nuclei are analyzed with respect to the count fluctuations. The coincidences from consecutive γ-rays emitted from discrete rotational bands generate ridges in the E γ1 .E γ2 spectrum, and the fluctuation analysis of the ridges is based upon the ansatz of a random selection of transition energies from band to band. This ansatz is supported by a cranked mean-field calculation for the nucleus 168 Yb, as well as by analyzing resolved bands in 168 Yb and its neighbors. The fluctuation analysis of the central valley (E γ1 =E γ2 ) is based upon the ansatz of fluctuations in the intensity of the transitions of Porter-Thomas type superposed on a smooth spectrum of transition energies. This ansatz is again supported by a mixed-band calculation. The mathematical treatment of count fluctuations is formulated in general (orig.)

Demand Response in Europe's Electricity Sector: Market barriers and outstanding issues

International Nuclear Information System (INIS)

Eid, Cherrelle

2015-01-01

In October 2014, Europe's drive for sustainability has been further continued with the set objectives for 2030, aiming for 40% emission reduction compared to 1990 levels and at least a 27% share of renewable energy sources. For the longer term, the European Commission (EC) targets a zero CO_2 emitting electricity sector in 2050. Those objectives for the electricity sector have a large impact on the expected development of electricity generation, but also on the evolution of demand. To meet those objectives, a larger share of electricity supply will come from intermittent sources like wind turbines and solar panels. In an electric system that is largely based on renewable electricity sources, it is desired to have higher electricity consumption in moments when more renewable electricity is being produced, and a lower consumption in times of lower renewable production. Demand response is related to the adaptability of the electricity demand to the availability of supply. The development of demand response is rooted in the need for carbon emission reductions and for efficient use of installed generation capacities with the growth of power consumption. In addition to providing flexibility to the electric system, demand response could be a direct source of revenue to households and businesses. In 2013, in the United States, businesses and homeowners earned over $2.2 billion in revenues from demand response together with other avoided investment in grid infrastructure and power plants. This source of direct revenue could also be made available in Europe and would release financial benefits to local economies (SEDC, 2014). The reliability improvements as well as the economic and sustainability potential coming from a more responsive electricity demand are fully acknowledged. However, demand response is still immaturely developed in Europe. If Europe wants to make a step forward to a more sustainable electricity sector, the development of demand response is an inevitable

Demand Response Within Current Electricity Wholesale Market Design

OpenAIRE

Ramos Gutierrez, Ariana Isabel; De Jonghe, Cedric; Six, Daan; Belmans, Ronnie

2013-01-01

The introduction of intermittent energy resources calls for the ability to modulate consumption patterns according to electricity availability. This paper provides a brief overview of the main electricity market design characteristics and places demand response within the framework of the existing timeline of market operation. The main differences between electricity markets lie in the price formation mechanisms where some markets pay-as- cleared and some pay- as- bid for the electricity tran...

Simulating radial diffusion of energetic (MeV electrons through a model of fluctuating electric and magnetic fields

Directory of Open Access Journals (Sweden)

T. Sarris

2006-10-01

Full Text Available In the present work, a test particle simulation is performed in a model of analytic Ultra Low Frequency, ULF, perturbations in the electric and magnetic fields of the Earth's magnetosphere. The goal of this work is to examine if the radial transport of energetic particles in quiet-time ULF magnetospheric perturbations of various azimuthal mode numbers can be described as a diffusive process and be approximated by theoretically derived radial diffusion coefficients. In the model realistic compressional electromagnetic field perturbations are constructed by a superposition of a large number of propagating electric and consistent magnetic pulses. The diffusion rates of the electrons under the effect of the fluctuating fields are calculated numerically through the test-particle simulation as a function of the radial coordinate L in a dipolar magnetosphere; these calculations are then compared to the symmetric, electromagnetic radial diffusion coefficients for compressional, poloidal perturbations in the Earth's magnetosphere. In the model the amplitude of the perturbation fields can be adjusted to represent realistic states of magnetospheric activity. Similarly, the azimuthal modulation of the fields can be adjusted to represent different azimuthal modes of fluctuations and the contribution to radial diffusion from each mode can be quantified. Two simulations of quiet-time magnetospheric variability are performed: in the first simulation, diffusion due to poloidal perturbations of mode number m=1 is calculated; in the second, the diffusion rates from multiple-mode (m=0 to m=8 perturbations are calculated. The numerical calculations of the diffusion coefficients derived from the particle orbits are found to agree with the corresponding theoretical estimates of the diffusion coefficient within a factor of two.

Characterisation of work function fluctuations for high-precision experiments

Energy Technology Data Exchange (ETDEWEB)

Kahlenberg, Jan; Bickmann, Edward; Heil, Werner; Otten, Ernst W.; Schmidt, Christian; Wunderle, Alexander [Johannes Gutenberg-Universitaet Mainz (Germany); Babutzka, Martin; Schoenung, Kerstin [Karlsruher Institut fuer Technologie (Germany); Beck, Marcus [Johannes Gutenberg-Universitaet Mainz (Germany); Helmholtz-Institut Mainz (Germany)

2016-07-01

For a wide range of high-precision experiments in physics, well-defined electric potentials for achieving high measurement accuracies are required. An accurate determination of the electric potential is crucial for the measurement of the neutrino mass (KATRIN) as well as the measurement of the e{sup -} anti ν{sub e} correlation coefficient a in free neutron decay (aSPECT). Work function fluctuations on the electrodes lead to uncertainties in the distribution of the electric potential. For aSPECT, the electric potential has to be known at an accuracy of 10 mV. However, due to the patch effect of gold, work function fluctuations of several 100 meV can occur. Therefore, the work function distributions of the gold-plated electrodes have been measured using a Kelvin probe. Furthermore, the change of work function distributions over time as well as the influence of relative humidity on the work function measurement have been investigated. For aSPECT, the work function distributions of the gold-plated electrodes have been measured using a Kelvin probe. Due to the patch effect of gold, work function fluctuations of up to 160 meV occur. This would lead to a significant uncertainty of the potential barrier, which should be known at an accuracy of 10 mV. Furthermore, the change of work function distributions over time as well as the influence of relative humidity on the work function measurement have been investigated.

Electric response in superfluid helium

Czech Academy of Sciences Publication Activity Database

Chagovets, Tymofiy

2016-01-01

Roč. 488, May (2016), s. 62-66 ISSN 0921-4526 R&D Projects: GA ČR GP13-03806P Institutional support: RVO:68378271 Keywords : superfluid helium * electric response * second sound * ions in He II Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.386, year: 2016

Growth of floating-leaved and submerged plants in artificial co-cultured microcosms: morphological responses to various water fluctuation regimes

International Nuclear Information System (INIS)

Cao, Q.J.

2015-01-01

Hydrocharis dubia can alternate between a rooted floating-leaved and a free-floating form, so given increasingly frequent precipitation extremes, it is not expected to be more negatively impacted by rapid water fluctuations than by gradual ones and may adapt water fluctuations by alteration of life forms. However, the opposite may be true for Nymphoides peltata, with only a rooted floating-leaved form. We designed an experiment combining six water depth treatments (constant shallow, constant deep, and two rapidly and two gradually fluctuating treatments) with three speciescombinations (N. peltata H. dubia, N. peltata Ceratophyllum demersum, and H. dubia C. demersum) to investigate plant responses to depth fluctuations and their co-cultured species. The total mass of N. peltata was considerably lower in the rapidly- than in the gradually-fluctuating treatments. However, total mass of H. dubia in the rapidly-fluctuating treatments was similar to or higher than in the gradually-fluctuating ones. Rapid fluctuations had a negative impact on the growth of C. demersum than gradual fluctuating. The floating-leaved species demonstrated divergent adaptive strategies to different water fluctuation patterns. In addition to expanding leaf blades, H. dubia can adapt to changing water depths by changing its life form. However, N. peltata, which mainly relies on morphological plasticity, such as petiole elongation, to adapt to water rise may reduce its abundance in communities subjected to increasingly frequent floods. The growth of submerged C. demersum, either co-occurring with H. dubia or with N. peltata, may be repressed by high flooding rates. (author)

Effect of increased ionization on the atmospheric electric field

International Nuclear Information System (INIS)

Boeck, W.L.

1980-01-01

This study is a review of atmospheric electrical theory with the purpose of predicting the atmospheric electrical effects of increased ionization caused by radioactive inert gases. A time-independent perturbation model for the global atmospheric electric circuit precdicts that the electric field at the sea surface would be reduced to about 76% of its unperturbed value by a surface 85 Kr concentration of 3 nCi/m 3 . The electric field at a typical land station is predicted to be about 84% of its unperturbed value. Some scientists have suggested that the atmospheric electric field is part of a closed electrical feedback loop. The present model does not include such a closed feedback loop and may underestimate the total effects. This model is also useful for interpreting atmospheric electrical responses to natural fluctuations in the cosmic-ray component of background radiation

An electricity generation planning model incorporating demand response

International Nuclear Information System (INIS)

Choi, Dong Gu; Thomas, Valerie M.

2012-01-01

Energy policies that aim to reduce carbon emissions and change the mix of electricity generation sources, such as carbon cap-and-trade systems and renewable electricity standards, can affect not only the source of electricity generation, but also the price of electricity and, consequently, demand. We develop an optimization model to determine the lowest cost investment and operation plan for the generating capacity of an electric power system. The model incorporates demand response to price change. In a case study for a U.S. state, we show the price, demand, and generation mix implications of a renewable electricity standard, and of a carbon cap-and-trade policy with and without initial free allocation of carbon allowances. This study shows that both the demand moderating effects and the generation mix changing effects of the policies can be the sources of carbon emissions reductions, and also shows that the share of the sources could differ with different policy designs. The case study provides different results when demand elasticity is excluded, underscoring the importance of incorporating demand response in the evaluation of electricity generation policies. - Highlights: ► We develop an electric power system optimization model including demand elasticity. ► Both renewable electricity and carbon cap-and-trade policies can moderate demand. ► Both policies affect the generation mix, price, and demand for electricity. ► Moderated demand can be a significant source of carbon emission reduction. ► For cap-and-trade policies, initial free allowances change outcomes significantly.

Energy flux due to electromagnetic fluctuations during guide field magnetic reconnection

International Nuclear Information System (INIS)

Kuwahata, Akihiro; Inomoto, Michiaki; Ono, Yasushi; Yanai, Ryoma

2016-01-01

Large electromagnetic fluctuations inside the current sheet and large reconnection electric fields are observed during fast magnetic reconnection in the presence of a guide field. The fluctuations transport 2.5% of the dissipated magnetic energy from the reconnection region. Although the energy gains of the ions and electrons are approximately 60% and 12%, respectively, of the dissipated magnetic energy after the fast reconnection, the energy of fluctuations is not comparable to their energy gains. The fluctuations do not directly contribute to the energy conversion but might cause the fast reconnection leading to the rapid release of magnetic energy. (author)

Modeling auditory-nerve responses to electrical stimulation

DEFF Research Database (Denmark)

Joshi, Suyash Narendra; Dau, Torsten; Epp, Bastian

2014-01-01

μs, which is large enough to affect the temporal coding of sounds and hence, potentially, the communication abilities of the CI listener. In the present study, two recently proposed models of electric stimulation of the AN [1,2] were considered in terms of their efficacy to predict the spike timing...... for anodic and cathodic stimulation of the AN of cat [3]. The models’ responses to the electrical pulses of various shapes [4,5,6] were also analyzed. It was found that, while the models can account for the firing rates in response to various biphasic pulse shapes, they fail to correctly describe the timing......Cochlear implants (CI) directly stimulate the auditory nerve (AN), bypassing the mechano-electrical transduction in the inner ear. Trains of biphasic, charge balanced pulses (anodic and cathodic) are used as stimuli to avoid damage of the tissue. The pulses of either polarity are capable...

Time-of-use based electricity demand response for sustainable manufacturing systems

International Nuclear Information System (INIS)

Wang, Yong; Li, Lin

2013-01-01

As required by the Energy Policy Act of 2005, utility companies across the U.S. are offering TOU (time-of-use) based electricity demand response programs. The TOU rate gives consumers opportunities to manage their electricity bill by shifting use from on-peak periods to mid-peak and off-peak periods. Reducing the amount of electricity needed during the peak load times makes it possible for the power grid to meet consumers' needs without building more costly backup infrastructures and help reduce GHG (greenhouse gas) emissions. Previous research on the applications of TOU and other electricity demand response programs has been mainly focused on residential and commercial buildings while largely neglected industrial manufacturing systems. This paper proposes a systems approach for TOU based electricity demand response for sustainable manufacturing systems under the production target constraint. Key features of this approach include: (i) the electricity related costs including both consumption and demand are integrated into production system modeling; (ii) energy-efficient and demand-responsive production scheduling problems are formulated and the solution technique is provided; and (iii) the effects of various factors on the near-optimal scheduling solutions are examined. The research outcome is expected to enhance the energy efficiency, electricity demand responsiveness, and cost effectiveness of modern manufacturing systems. - Highlights: • We propose a TOU based demand response approach for manufacturing systems. • Both electricity consumption and demand are integrated into the system modeling. • Energy-efficient and demand-responsive production scheduling problems are formulated. • The meta-heuristic solution technique is provided. • The effects of various factors on the scheduling solutions are examined

Universal conductance fluctuations in disordered metals

International Nuclear Information System (INIS)

Lee, P.A.

1987-01-01

The author argues that observed and theoretical fluctuations in the electrical conductance of disordered metals, induced by variations in the magnetic field or the chemical potential, are not time-dependent noise but that the conductance is a deterministic albeit fluctuating function for a given realization of the impurity configuration. A method is constructed for representing the sensitivity of the conductance of a given metal to a small change in the impurity configuration as a function of such variables as sample size, impurities per unit volume, and mean free path. The sensitivity helps explain the size of 1/f noise due to defect motion in disordered metals

Spin fluctuations and the

Directory of Open Access Journals (Sweden)

V.M. Loktev

2008-09-01

Full Text Available We analyze the spectral properties of a phenomenological model for a weakly doped two-dimensional antiferromagnet, in which the carriers move within one of the two sublattices where they were introduced. Such a constraint results in the free carrier spectra with the maxima at k=(± π/2 , ± π/2 observed in some cuprates. We consider the spectral properties of the model by taking into account fluctuations of the spins in the antiferromagnetic background. We show that such fluctuations lead to a non-pole-like structure of the single-hole Green's function and these fluctuations can be responsible for some anomalous "strange metal" properties of underdoped cuprates in the nonsuperconducting regime.

The Fluctuation Niche in Plants

Directory of Open Access Journals (Sweden)

Jaume Terradas

2009-01-01

Full Text Available Classical approaches to niche in coexisting plants have undervalued temporal fluctuations. We propose that fluctuation niche is an important dimension of the total niche and interacts with habitat and life-history niches to provide a better understanding of the multidimensional niche space where ecological interactions occur. To scale a fluctuation niche, it is necessary to relate environmental constrictions or species performance not only to the absolute values of the usual environmental and ecophysiological variables but also to their variances or other measures of variability. We use Mediterranean plant communities as examples, because they present characteristic large seasonal and interannual fluctuations in water and nutrient availabilities, along an episodic-constant gradient, and because the plant responses include a number of syndromes coupled to this gradient.

The Fluctuation Niche in Plants

International Nuclear Information System (INIS)

Terradas, J.; Penuelas, J.; Lloret, F.; Penuelas, J.

2009-01-01

Classical approaches to niche in coexisting plants have undervalued temporal fluctuations. We propose that fluctuation niche is an important dimension of the total niche and interacts with habitat and life-history niches to provide a better understanding of the multidimensional niche space where ecological interactions occur. To scale a fluctuation niche, it is necessary to relate environmental constrictions or species performance not only to the absolute values of the usual environmental and eco physiological variables but also to their variances or other measures of variability. We use Mediterranean plant communities as examples, because they present characteristic large seasonal and inter annual fluctuations in water and nutrient availabilities, along an episodic-constant gradient, and because the plant responses include a number of syndromes coupled to this gradient.

Vehicle-to-Grid Power in Danish Electric Power Systems

DEFF Research Database (Denmark)

Pillai, Jayakrishnan Radhakrishna; Bak-Jensen, Birgitte

2009-01-01

The integration of renewable energy systems is often constrained by the variable nature of their output. This demands for the services of storing the electricity generated from most of the renewable energy sources. Vehicle-to-grid (V2G) power could use the inherent energy storage of electric...... vehicles and its quick response time to balance and stabilize a power system with fluctuating power. This paper outlines the use of battery electric vehicles in supporting large-scale integration of renewable energy in the Danish electric power systems. The reserve power requirements for a high renewable...... energy penetration could be met by an amount of V2G based electric vehicles less than 10% of the total vehicle need in Denmark. The participation of electric vehicle in ancillary services would earn significant revenues to the vehicle owner. The power balancing services of electric vehicles...

Stimuli-Responsive Polymer-Clay Nanocomposites under Electric Fields

Science.gov (United States)

Piao, Shang Hao; Kwon, Seung Hyuk; Choi, Hyoung Jin

2016-01-01

This short Feature Article reviews electric stimuli-responsive polymer/clay nanocomposites with respect to their fabrication, physical characteristics and electrorheological (ER) behaviors under applied electric fields when dispersed in oil. Their structural characteristics, morphological features and thermal degradation behavior were examined by X-ray diffraction pattern, scanning electron microscopy and transmission electron microscopy, and thermogravimetric analysis, respectively. Particular focus is given to the electro-responsive ER characteristics of the polymer/clay nanocomposites in terms of the yield stress and viscoelastic properties along with their applications. PMID:28787852

The power to choose. Demand response in liberalized electricity markets

International Nuclear Information System (INIS)

2003-01-01

Highly volatile electricity prices are becoming a more frequent and unwanted characteristic of modern electricity wholesale markets. But low demand elasticity, mainly the result of a lack of incentives and consumers' inability to control demand, means that consumer behaviour is not reflected in the cost of energy. This study analyses the impact of price-responsive demand and shows how pricing, policy and technology can be used to inform consumer behaviour and choice. Informed choice and market-based valuation of electricity supply will ensure liberalized markets are competitive, efficient, less volatile and able to provide long term security of supply. Significant benefits will occur even if only 5% of customers become responsive to price-incentives and information. And customers will respond to well designed programs, thereby developing a role in ensuring efficient price formulation for electricity. This study analyses the economic, efficiency and security benefits and identifies the changes in electricity tariffs and the network infrastructure needed to achieve greater demand response

Effects of pulsed electric field on ULQ and RFP plasmas

International Nuclear Information System (INIS)

Watanabe, M.; Saito, K.; Suzuki, T.

1997-01-01

Dynamo activity and self-organization processes are investigated using the application of pulsed poloidal and toroidal electric fields on ULQ and RFP plasmas. Synchronized to the application of the pulsed electric fields, the remarkable responses of the several plasma parameters are observed. The plasma has a preferential magnetic field structure, and the external perturbation activates fluctuation to maintain the structure through dynamo effect. This process changes the total dissipation with the variation of magnetic helicity in the system, showing that self organization accompanies an enhanced dissipation. (author)

Reduced dielectric response in spatially varying electric fields

DEFF Research Database (Denmark)

Hansen, Jesper Schmidt

2015-01-01

relations between the flux and the gradient of the polarization. Comparison between the theory and molecular dynamics simulations confirms this effect. The effect is significant for small length scale electric field variations and the inclusion of the flux is thus important in nanoscale modeling......In this paper, the dynamical equation for polarization is derived. From this the dielectric response to a spatially varying electric field is analyzed showing a reduced response due to flux of polarization in the material. This flux is modeled as a diffusive process through linear constitutive...

Resistance and resistance fluctuations in random resistor networks under biased percolation.

Science.gov (United States)

Pennetta, Cecilia; Reggiani, L; Trefán, Gy; Alfinito, E

2002-06-01

We consider a two-dimensional random resistor network (RRN) in the presence of two competing biased processes consisting of the breaking and recovering of elementary resistors. These two processes are driven by the joint effects of an electrical bias and of the heat exchange with a thermal bath. The electrical bias is set up by applying a constant voltage or, alternatively, a constant current. Monte Carlo simulations are performed to analyze the network evolution in the full range of bias values. Depending on the bias strength, electrical failure or steady state are achieved. Here we investigate the steady state of the RRN focusing on the properties of the non-Ohmic regime. In constant-voltage conditions, a scaling relation is found between /(0) and V/V(0), where is the average network resistance, (0) the linear regime resistance, and V0 the threshold value for the onset of nonlinearity. A similar relation is found in constant-current conditions. The relative variance of resistance fluctuations also exhibits a strong nonlinearity whose properties are investigated. The power spectral density of resistance fluctuations presents a Lorentzian spectrum and the amplitude of fluctuations shows a significant non-Gaussian behavior in the prebreakdown region. These results compare well with electrical breakdown measurements in thin films of composites and of other conducting materials.

Electric moments in molecule interferometry

International Nuclear Information System (INIS)

Eibenberger, Sandra; Gerlich, Stefan; Arndt, Markus; Tuexen, Jens; Mayor, Marcel

2011-01-01

We investigate the influence of different electric moments on the shift and dephasing of molecules in a matter wave interferometer. Firstly, we provide a quantitative comparison of two molecules that are non-polar yet polarizable in their thermal ground state and that differ in their stiffness and response to thermal excitations. While C 25 H 20 is rather rigid, its larger derivative C 49 H 16 F 52 is additionally equipped with floppy side chains and vibrationally activated dipole moment variations. Secondly, we elucidate the role of a permanent electric dipole momentby contrasting the quantum interference pattern of a (nearly) non-polar and a polar porphyrin derivative. We find that a high molecular polarizability and even sizeable dipole moment fluctuations are still well compatible with high-contrast quantum interference fringes. The presence of permanent electric dipole moments, however, can lead to a dephasing and rapid degradation of the quantum fringe pattern already at moderate electric fields. This finding is of high relevance for coherence experiments with large organic molecules, which are generally equipped with strong electric moments.

Fluctuations and correlations of conserved charges near the QCD critical point

International Nuclear Information System (INIS)

Fu Weijie; Wu Yueliang

2010-01-01

We study the fluctuations and correlations of conserved charges, such as the baryon number, the electric charge and the strangeness, at the finite temperature and the nonzero baryon chemical potential in an effective model. The fluctuations are calculated up to the fourth-order and the correlations to the third-order. We find that the second-order fluctuations and correlations have a peak or valley structure when the chiral phase transition takes place with the increase of the baryon chemical potential; the third-order fluctuations and correlations change their signs during the chiral phase transition; and the fourth-order fluctuations have two maxima and one minimum. We also depict contour plots of various fluctuations and correlations of conserved charges in the plane of temperature and the baryon chemical potential. It is found that higher-order fluctuations and correlations of conserved charges are superior to the second-order ones to be used to search for the critical point in heavy ion collision experiments.

Designing a New Electricity Consumer

DEFF Research Database (Denmark)

Pallesen, Trine; Jenle, Rasmus Ploug

The paper reports on a smart grid experiment for the making of a new retail electricity market integrating fluctuating electricity generation into electricity systems. An outline of design challenges faced by the market engineers when dealing with different and lacking conceptions of consumers...

Fuel-efficiency of hydrogen and heat storage technologies for integration of fluctuating renewable energy sources

DEFF Research Database (Denmark)

Mathiesen, Brian Vad; Lund, Henrik

2005-01-01

This paper presents the methodology and results of analysing the use of different energy storage technologies in the task of integration of fluctuating renewable energy sources (RES) into the electricity supply. The analysis is done on the complete electricity system including renewable energy...... sources as well as power plants and CHP (Combined heat and power production). Emphasis is put on the need for ancillary services. Devices to store electricity as well as devices to store heat can be used to help the integration of fluctuating sources. Electricity storage technologies can be used...... to relocate electricity production directly from the sources, while heat storage devices can be used to relocate the electricity production from CHP plants and hereby improve the ability to integrate RES. The analyses are done by advanced computer modelling and the results are given as diagrams showing...

Fast temporal fluctuations in single-molecule junctions.

Science.gov (United States)

Ochs, Roif; Secker, Daniel; Elbing, Mark; Mayor, Marcel; Weber, Heiko B

2006-01-01

The noise within the electrical current through single-molecule junctions is studied cryogenic temperature. The organic sample molecules were contacted with the mechanically controlled break-junction technique. The noise spectra refer to a where only few Lorentzian fluctuators occur in the conductance. The frequency dependence shows qualitative variations from sample to sample.

Modelling the Aggregated Dynamic Response of Electric Vehicles

DEFF Research Database (Denmark)

Ziras, Charalampos; Hu, Junjie; You, Shi

2017-01-01

There is an increasing interest in the use of electric vehicles (EVs) for providing fast frequency reserves due to their large installed capacity and their very fast response. Most works focus on scheduling and optimization and usually neglect their aggregated dynamic response, which...

Thermal and active fluctuations of a compressible bilayer vesicle

Science.gov (United States)

Sachin Krishnan, T. V.; Yasuda, Kento; Okamoto, Ryuichi; Komura, Shigeyuki

2018-05-01

We discuss thermal and active fluctuations of a compressible bilayer vesicle by using the results of hydrodynamic theory for vesicles. Coupled Langevin equations for the membrane deformation and the density fields are employed to calculate the power spectral density matrix of membrane fluctuations. Thermal contribution is obtained by means of the fluctuation dissipation theorem, whereas active contribution is calculated from exponentially decaying time correlation functions of active random forces. We obtain the total power spectral density as a sum of thermal and active contributions. An apparent response function is further calculated in order to compare with the recent microrheology experiment on red blood cells. An enhanced response is predicted in the low-frequency regime for non-thermal active fluctuations.

Resistance Fluctuations in GaAs Nanowire Grids

Directory of Open Access Journals (Sweden)

Ivan Marasović

2014-01-01

Full Text Available We present a numerical study on resistance fluctuations in a series of nanowire-based grids. Each grid is made of GaAs nanowires arranged in parallel with metallic contacts crossing all nanowires perpendicularly. Electrical properties of GaAs nanowires known from previous experimental research are used as input parameters in the simulation procedure. Due to the nonhomogeneous doping, the resistivity changes along nanowire. Allowing two possible nanowire orientations (“upwards” or “downwards”, the resulting grid is partially disordered in vertical direction which causes resistance fluctuations. The system is modeled using a two-dimensional random resistor network. Transfer-matrix computation algorithm is used to calculate the total network resistance. It is found that probability density function (PDF of resistance fluctuations for a series of nanowire grids changes from Gaussian behavior towards the Bramwell-Holdsworth-Pinton distribution when both nanowire orientations are equally represented in the grid.

Force fluctuations assist nanopore unzipping of DNA

International Nuclear Information System (INIS)

Viasnoff, V; Chiaruttini, N; Muzard, J; Bockelmann, U

2010-01-01

We experimentally study the statistical distributions and the voltage dependence of the unzipping time of 45 base-pair-long double-stranded DNA through a nanopore. We then propose a quantitative theoretical description considering the nanopore unzipping process as a random walk of the opening fork through the DNA sequence energy landscape biased by a time-fluctuating force. To achieve quantitative agreement fluctuations need to be correlated over the millisecond range and have an amplitude of order k B T/bp. Significantly slower or faster fluctuations are not appropriate, suggesting that the unzipping process is efficiently enhanced by noise in the kHz range. We further show that the unzipping time of short 15 base-pair hairpins does not always increase with the global stability of the double helix and we theoretically study the role of DNA elasticity on the conversion of the electrical bias into a mechanical unzipping force.

Which electricity market design to encourage the development of demand response?

OpenAIRE

Vincent Rious, Fabien Roques and Yannick Perez

2012-01-01

Demand response is a cornerstone problem in electricity markets under climate change constraint. Most liberalized electricity markets have a poor track record at encouraging the deployment of smart meters and the development of demand response. In Europe, different models are considered for demand response, from a development under a regulated regime to a development under competitive perspectives. In this paper, focusing on demand response and smart metering for mid-size and small consumers,...

Which electricity market design to encourage the development of demand response?

OpenAIRE

Rious , Vincent; Perez , Yannick; Roques , Fabien

2015-01-01

International audience; Demand response is a cornerstone problem in electricity markets under climate change constraints. Most liberalized electricity markets have a poor track record at encouraging the deployment of smart meters and the development of demand response. In Europe, different models are considered for demand response, from a development under a regulated regime to a development under competitive perspectives. In this paper focusing on demand response and smart metering for mid-­...

Analysis of water-level fluctuations in Wisconsin wells

Science.gov (United States)

Patterson, G.L.; Zaporozec, A.

1987-01-01

More than 60 percent of the residents of Wisconsin use ground water as their primary water source. Water supplies presently are abundant, but ground-water levels continually fluctuate in response to natural factors and human-related stresses. A better understanding of the magnitude, duration, and frequency of past fluctuations, and the factors controlling these fluctuations may help anticipate future changes in ground-water levels.

Interferometric investigation of turbulently fluctuating temperature in an LMFBR outlet plenum geometry

International Nuclear Information System (INIS)

Bennett, R.G.; Golay, M.W.

1975-01-01

A novel optical technique is described for the measurement of turbulently fluctuating temperature in a transparent fluid flow. The technique employs a Mach-Zehnder interferometer of extremely short field and a simple photoconductive diode detector. The system produces a nearly linear D.C. electrical analog of the turbulent temperature fluctuations in a small, 1 mm 3 volume. The frequency response extends well above 2500 Hz, and can be improved by the choice of a more sophisticated photodetector. The turbulent sodium mixing in the ANL 1 1 / 15 -scale FFTF outlet plenum is investigated with a scale model outlet mixing plenum, using flows of air. The scale design represents a cross section of the ANL outlet plenum, so that the average recirculating flow inside the test cell is two dimensional. The range of the instrument is 120 0 F above the ambient air temperature. The accuracy is generally +-5 0 F, with most of the error due to noise originating from building vibrations and room noise. The power spectral density of the fluctuating temperature has been observed experimentally at six different stations in the flow. A strong 300 Hz component is generated in the inlet region, which decays as the flow progresses along streamlines. The effect of the inlet Reynolds number and the temperature difference between the inlet flows on the power spectral density has also been investigated. Traces of the actual fluctuating temperature are included for the six stations

Scattering of electromagnetic waves by anomalous fluctuations of a magnetized plasma

Science.gov (United States)

Pavlenko, V. N.; Panchenko, V. G.

1990-04-01

Fluctuations and scattering of transverse electromagnetic waves by density fluctuations in a magnetized plasma in the presence of parametric decay of the pump wave are investigated. The spectral density of electron-density fluctuations is calculated. It is shown that the differential scattering cross-section has sharp maxima at the ion-acoustic and lower-hybrid frequencies when parametric decay of the lower-hybrid pump wave occurs. We note that scattering at the ion-acoustic frequency is dominant. When the pump-wave amplitude tends to the threshold strength of the electric field the scattering cross-section increases anomalously, i.e. there is critical opalescence.

Benefits and challenges of electrical demand response: A critical review

DEFF Research Database (Denmark)

O'Connell, Niamh; Pinson, Pierre; Madsen, Henrik

2014-01-01

and challenges of demand response. These benefits include the ability to balance fluctuations in renewable generation and consequently facilitate higher penetrations of renewable resources on the power system, an increase in economic efficiency through the implementation of real-time pricing, and a reduction...... in generation capacity requirements. Nevertheless, demand response is not without its challenges. The key challenges for demand response centre around establishing reliable control strategies and market frameworks so that the demand response resource can be used optimally. One of the greatest challenges...... for demand response is the lack of experience, and the consequent need to employ extensive assumptions when modelling and evaluating this resource. This paper concludes with an examination of these assumptions, which range from assuming a fixed linear price–demand relationship for price responsive demand...

Density, potential and temperature fluctuations in Wendelstein 7-AS and ASDEX

International Nuclear Information System (INIS)

Balbin, R.; Hidalgo, C.; Carlson, A.; Endler, M.; Giannone, L.; Herre, G.; Niedermeyer, H.; Rudyj, A.; Theimer, G.

1992-01-01

Measurements of ion saturation current, floating potential and temperature fluctuations in Wendelstein 7-AS stellarator (W7-AS) and ASDEX tokamak have been carried out. A reciprocating Langmuir probe with an array of 19 graphite tips has been used to obtain the radial profiles of these fluctuations in W7-AS and ASDEX. In both devices, a reversal of the radial electric field and an associated velocity shear layer at the plasma boundary have been observed. At the radial position where the phase velocity the poloidal direction of the fluctuations goes to zero, the normalised ion saturation current fluctuation level of 0.2 is the same for edge plasma parameters of similar temperatures and densities. A spatial crosscorrelation between floating potential and ion saturation current fluctuations has been observed in both machines and this feature can be explained in terms of turbulent eddies. A comparison of fluctuations in a tokamak and stellarator therefore shows many features in common. (orig.)

A non-commutative formula for the isotropic magneto-electric response

International Nuclear Information System (INIS)

Leung, Bryan; Prodan, Emil

2013-01-01

A non-commutative formula for the isotropic magneto-electric response of disordered insulators under magnetic fields is derived using the methods of non-commutative geometry. Our result follows from an explicit evaluation of the Ito derivative with respect to the magnetic field of the non-commutative formula for the electric polarization reported in Schulz-Baldes and Teufel (2012 arXiv:1201.4812v1). The quantization, topological invariance and connection to a second Chern number of the magneto-electric response are discussed in the context of three-dimensional, disordered, time-reversal or inversion symmetric topological insulators. (paper)

Density, potential and temperature fluctuations in Wendelstein 7-AS and ASDEX

Energy Technology Data Exchange (ETDEWEB)

Balbin, R; Hidalgo, C [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain); Carlson, A; Endler, M; Giannone, L.; Niedermeyer, H; Rudyj, A; Theimer, G [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

1993-12-31

Measurements of density, potential and temperature fluctuations in Wendelstein 7-AS stellarator (W7-AS) and ASDEX tokamak have been carried out. The properties of plasma fluctuations in a tokamak and stellarator can then be compared. A reciprocating Langmuir probe with an array of 19 graphite tips has been used to measure the radial profiles of fluctuations in the ion saturation current and floating potential in W7-AS and ASDEX. In both devices, a reversal in radial electric field and an associated velocity shear layer at the plasma boundary have been observed and in both cases the normalized ion saturation current fluctuation level decreases monotonically moving towards the plasma centre and through the shear layer. At the radial position where the phase velocity in the poloidal direction of the fluctuations goes to zero, the normalized ion saturation current fluctuation level of 0.25 are similar for edge plasma parameters of similar temperatures and densities. A spatial crosscorrelation between fluctuations in floating potential and ion saturation current has been observed in both machines. (author) 6 refs., 4 figs.

Frequency-dependent transient response of an oscillating electrically actuated droplet

International Nuclear Information System (INIS)

Dash, S; Kumari, N; Garimella, S V

2012-01-01

The transient response of a millimeter-sized sessile droplet under electrical actuation is experimentally investigated. Under dc actuation, the droplet spreading rate increases as the applied voltage is increased due to the higher electrical forces induced. At sufficiently high dc voltages, competition between the electrical actuation force, droplet inertia, the retarding surface tension force and contact line friction leads to droplet oscillation. The timescale for the droplet to attain its maximum wetted diameter during step actuation is analyzed. Systematic experiments are conducted over a frequency range of 5–200 Hz and actuation voltages of 40–80 V rms to determine the dependence of droplet oscillation on these parameters. The response of the droplet to different actuation frequencies and voltages is determined in terms of its contact angle and contact radius variation. The frequency of the driving force (equal to twice the frequency of the applied electrical signal) determines the mode of oscillation of the droplet which, together with its resonance characteristics, governs whether the droplet contact angle and contact radius vary in phase or out of phase with each other. In addition to the primary frequency response at the electrical forcing frequency, the droplet oscillation exhibits sub-harmonic oscillation at half of the forcing frequency that is attributed to the parametric nature of the electrical force acting on the triple contact line of the droplet. (paper)

Dynamical critical scaling of electric field fluctuations in the greater cusp and magnetotail implied by HF radar observations of F-region Doppler velocity

Directory of Open Access Journals (Sweden)

M. L. Parkinson

2006-03-01

Full Text Available Akasofu's solar wind ε parameter describes the coupling of solar wind energy to the magnetosphere and ionosphere. Analysis of fluctuations in ε using model independent scaling techniques including the peaks of probability density functions (PDFs and generalised structure function (GSF analysis show the fluctuations were self-affine (mono-fractal, single exponent scaling over 9 octaves of time scale from ~46 s to ~9.1 h. However, the peak scaling exponent α0 was a function of the fluctuation bin size, so caution is required when comparing the exponents for different data sets sampled in different ways. The same generic scaling techniques revealed the organisation and functional form of concurrent fluctuations in azimuthal magnetospheric electric fields implied by SuperDARN HF radar measurements of line-of-sight Doppler velocity, vLOS, made in the high-latitude austral ionosphere. The PDFs of vLOS fluctuation were calculated for time scales between 1 min and 256 min, and were sorted into noon sector results obtained with the Halley radar, and midnight sector results obtained with the TIGER radar. The PDFs were further sorted according to the orientation of the interplanetary magnetic field, as well as ionospheric regions of high and low Doppler spectral width. High spectral widths tend to occur at higher latitude, mostly on open field lines but also on closed field lines just equatorward of the open-closed boundary, whereas low spectral widths are concentrated on closed field lines deeper inside the magnetosphere. The vLOS fluctuations were most self-affine (i.e. like the solar wind ε parameter on the high spectral width field lines in the noon sector ionosphere (i.e. the greater cusp, but suggested multi-fractal behaviour on closed field lines in the midnight sector (i.e. the central plasma sheet. Long tails in the PDFs imply that "microbursts" in ionospheric convection occur far more frequently, especially on open field lines, than can be

Current fluctuation of electron and hole carriers in multilayer WSe{sub 2} field effect transistors

Energy Technology Data Exchange (ETDEWEB)

Ko, Seung-Pil; Shin, Jong Mok; Jang, Ho-Kyun; Jin, Jun Eon; Kim, Gyu-Tae, E-mail: gtkim@korea.ac.kr [School of Electrical Engineering, Korea University, Seoul 02481 (Korea, Republic of); Kim, Yong Jin; Kim, Young Keun [Department of Materials Science and Engineering, Korea University, Seoul 02481 (Korea, Republic of); Shin, Minju [School of Electrical Engineering, Korea University, Seoul 02481 (Korea, Republic of); IMEP-LAHC, Grenoble INP-MINATEC, 3 Parvis Louis Neel, 38016 Grenoble (France)

2015-12-14

Two-dimensional materials have outstanding scalability due to their structural and electrical properties for the logic devices. Here, we report the current fluctuation in multilayer WSe{sub 2} field effect transistors (FETs). In order to demonstrate the impact on carrier types, n-type and p-type WSe{sub 2} FETs are fabricated with different work function metals. Each device has similar electrical characteristics except for the threshold voltage. In the low frequency noise analysis, drain current power spectral density (S{sub I}) is inversely proportional to frequency, indicating typical 1/f noise behaviors. The curves of the normalized drain current power spectral density (NS{sub I}) as a function of drain current at the 10 Hz of frequency indicate that our devices follow the carrier number fluctuation with correlated mobility fluctuation model. This means that current fluctuation depends on the trapping-detrapping motion of the charge carriers near the channel interface. No significant difference is observed in the current fluctuation according to the charge carrier type, electrons and holes that occurred in the junction and channel region.

Beyond the linear fluctuation-dissipation theorem: the role of causality

International Nuclear Information System (INIS)

Lucarini, Valerio; Colangeli, Matteo

2012-01-01

In this paper we tackle the traditional problem of relating the fluctuations of a system to its response to external forcings and extend the classical theory in order to be able to encompass also nonlinear processes. With this goal, we try to build on Kubo's linear response theory and the response theory recently developed by Ruelle for nonequilibrium systems equipped with an invariant Sinai–Ruelle–Bowen (SRB) measure. Our derivation also sheds light on the link between causality and the possibility of relating fluctuations and response, both at the linear and nonlinear level. We first show, in a rather general setting, how the formalism of Ruelle's response theory can be used to derive in a novel way a generalization of the Kramers–Kronig relations. We then provide a formal extension at each order of nonlinearity of the fluctuation-dissipation theorem for general systems endowed with a smooth invariant measure. Finally, we focus on the physically relevant case of systems weakly perturbed from equilibrium, for which we present explicit fluctuation-dissipation relations linking the susceptibility describing the nth order response of the system with suitably defined correlations taken in the equilibrium ensemble

Evolution and current status of demand response (DR) in electricity markets: Insights from PJM and NYISO

International Nuclear Information System (INIS)

Walawalkar, Rahul; Fernands, Stephen; Thakur, Netra; Chevva, Konda Reddy

2010-01-01

In electricity markets, traditional demand side management programs are slowly getting replaced with demand response (DR) programs. These programs have evolved since the early pilot programs launched in late 1990s. With the changes in market rules the opportunities have generally increased for DR for participating in emergency, economic and ancillary service programs. In recent times, various regulators have suggested that DR can also be used as a solution to meet supply - demand fluctuations in scenarios with significant penetration of variable renewable sources in grid. This paper provides an overview of the evolution of the DR programs in PJM and NYISO markets as well as analyzes current opportunities. Although DR participation has grown, most of the current participation is in the reliability programs, which are designed to provide load curtailment during peak days. This suggests that there is a significant gap between perception of ability of DR to mitigate variability of renewables and reality of current participation. DR in future can be scaled to play a more dynamic role in electricity markets, but that would require changes both on technology as well as policy front. Advances in building technologies and energy storage combined with appropriate price signals can lead to enhanced DR participation. (author)

Role of adsorbates on current fluctuations in DC field emission

International Nuclear Information System (INIS)

Luong, M.; Bonin, B.; Long, H.; Safa, H.

1996-01-01

Field emission experiments in DC regime usually show important current fluctuations for a fixed electric field. These fluctuations are attributed to adsorbed layers (molecules or atoms), liable to affect the work function, height and shape of the potential barrier binding the electron in the metal. The role of these adsorbed species is investigated by showing that the field emission from a well desorbed sample is stable and reproducible and by comparing the emission from the same sample before and after desorption. (author)

Hawaiian Electric Company Demand Response Roadmap Project

Energy Technology Data Exchange (ETDEWEB)

Levy, Roger [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kiliccote, Sila [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2013-01-12

The objective of this project was to develop a “roadmap” to guide the Hawaiian Electric Company (HECO) demand response (DR) planning and implementation in support of the Hawaii Clean Energy Initiative (HCEI) 70% clean energy goal by 2030.

Profiling the regional wind power fluctuation in China

International Nuclear Information System (INIS)

Yu Dayang; Liang Jun; Han Xueshan; Zhao Jianguo

2011-01-01

As China starts to build 6 10-GW wind zones in 5 provinces by 2020, accommodating the wind electricity generated from these large wind zones will be a great challenge for the regional grids. Inadequate wind observing data hinders profiling the wind power fluctuations at the regional grid level. This paper proposed a method to assess the seasonal and diurnal wind power patterns based on the wind speed data from the NASA GEOS-5 DAS system, which provides data to the study of climate processes including the long-term estimates of meteorological quantities. The wind power fluctuations for the 6 largest wind zones in China are presented with both the capacity factor and the megawatt wind power output. The measured hourly wind output in a regional grid is compared to the calculating result to test the analyzing model. To investigate the offsetting effect of dispersed wind farms over large regions, the regional correlations of hourly wind power fluctuations are calculated. The result illustrates the different offsetting effects of minute and hourly fluctuations.

Disordered electrical potential observed on the surface of SiO2 by electric field microscopy

International Nuclear Information System (INIS)

GarcIa, N; Yan Zang; Ballestar, A; Barzola-Quiquia, J; Bern, F; Esquinazi, P

2010-01-01

The electrical potential on the surface of ∼300 nm thick SiO 2 grown on single-crystalline Si substrates has been characterized at ambient conditions using electric field microscopy. Our results show an inhomogeneous potential distribution with fluctuations up to ∼0.4 V within regions of 1 μm. The potential fluctuations observed at the surface of these usual dielectric holders of graphene sheets should induce strong variations in the graphene charge densities and provide a simple explanation for some of the anomalous behaviors of the transport properties of graphene.

Manifestly non-Gaussian fluctuations in superconductor-normal metal tunnel nanostructures

Energy Technology Data Exchange (ETDEWEB)

Laakso, Matti [Institut fuer Theorie der Statistischen Physik, RWTH Aachen University, Aachen (Germany); Low Temperature Laboratory, Aalto University, Espoo (Finland); Heikkilae, Tero [Low Temperature Laboratory, Aalto University, Espoo (Finland); Nazarov, Yuli [Kavli Institute of Nanoscience, Delft University of Technology, Delft (Netherlands)

2013-07-01

Recently, temperature fluctuation statistics has been studied in non-interacting islands and overheated single-electron transistors. We propose a mesoscopic setup which exhibits strong and manifestly non-Gaussian fluctuations of energy and temperature when suitably driven out of equilibrium. The setup consists of a normal metal island (N) coupled by tunnel junctions (I) to two superconducting leads (S), forming a SINIS structure, and is biased near the threshold voltage for quasiparticle tunneling, eV ∼ 2Δ. The fluctuations can be measured by monitoring the time-dependent electric current through the system, which makes the setup suitable for the realization of feedback schemes which allow to stabilize the temperature to the desired value.

Demand response offered by households with direct electric heating

International Nuclear Information System (INIS)

Kofod, C.; Togeby, M.

2004-01-01

The peak power balance in the Nordic power system is gradually turning to be very tight, especially in the electric area of southern Sweden and eastern Denmark. Power stations are closed and hardly any investments in new production are carried out. Demand response is considered essential when the formation of spot prices shall send the signal of needed investments in new capacity. Demand response which are based on individual preferences, and carried out automatically, can be one way to increase the volume of price elastic demand. Demand response need hourly metering for calculation and documentation of the decrease in demand, and controllability in order to meet the timing requirements. Within the EU SAVE project EFFLOCOM (2002 - 2004), a Danish demand response pilot project was established in 2003 including 25 single family homes with direct electrical heating. The system has been tested during the winter 2003/2004. The tested technologies include hourly metering, communication by GRPS as well as the Internet. GPRS is used for daily remote meter reading and automatic control of the electric heating including individual control of up to five zones. The system is designed for automatic activation when the Nord Pool hourly Elspot prices exceed preset levels. The system can also be used as regulating power. The EFFLOCOM Web Bite includes an interactive demonstrator of the system. The developed customer Web Bite is including the services: 1) Access to setting the limits for the maximum duration of interruption for up to five different control zones for two periods of the day and for three price levels. 2) Access to stop an actual interruption. 3) A report on the hourly, daily, weekly and monthly use of electricity and the saved bonus by demand response control. The report is updated daily. The goals of up to 5 kW controlled per house were fulfilled. Besides the demand response bonus the customers have also saved electricity. A customer survey did show that the

Electricity rationing and public response

International Nuclear Information System (INIS)

Souza, Leonardo Rocha; Soares, Lacir Jorge

2007-01-01

This paper studies the electricity load demand behavior during the 2001 rationing period, which was implemented because of the Brazilian energy crisis. The hourly data refers to a utility situated in the southeast of the country. We use the model proposed by Soares and Souza [Soares, L.J. and Souza, L.R. (2006), 'Forecasting electricity demand using generalized long memory', International Journal of Forecasting, 22, 17-28.], making use of generalized long memory to model the seasonal behavior of the load. The rationing period is shown to have imposed a structural break in the series, decreasing the load at about 20%. Even so, the forecast accuracy is decreased only marginally, and the forecasts rapidly readapt to the new situation. The structural break, as well as the forecast errors from this model, also permits verifying the public response to pieces of information released regarding the crisis. (Author)

Charging a Capacitor from an External Fluctuating Potential using a Single Conical Nanopore

Science.gov (United States)

Gomez, Vicente; Ramirez, Patricio; Cervera, Javier; Nasir, Saima; Ali, Mubarak; Ensinger, Wolfgang; Mafe, Salvador

2015-01-01

We explore the electrical rectification of large amplitude fluctuating signals by an asymmetric nanostructure operating in aqueous solution. We show experimentally and theoretically that a load capacitor can be charged to voltages close to 1 V within a few minutes by converting zero time-average potentials of amplitudes in the range 0.5–3 V into average net currents using a single conical nanopore. This process suggests that significant energy conversion and storage from an electrically fluctuating environment is feasible with a nanoscale pore immersed in a liquid electrolyte solution, a system characteristic of bioelectronics interfaces, electrochemical cells, and nanoporous membranes. PMID:25830563

Vibration Prediction Method of Electric Machines by using Experimental Transfer Function and Magnetostatic Finite Element Analysis

International Nuclear Information System (INIS)

Saito, A; Kuroishi, M; Nakai, H

2016-01-01

This paper concerns the noise and structural vibration caused by rotating electric machines. Special attention is given to the magnetic-force induced vibration response of interior-permanent magnet machines. In general, to accurately predict and control the vibration response caused by the electric machines, it is inevitable to model not only the magnetic force induced by the fluctuation of magnetic fields, but also the structural dynamic characteristics of the electric machines and surrounding structural components. However, due to complicated boundary conditions and material properties of the components, such as laminated magnetic cores and varnished windings, it has been a challenge to compute accurate vibration response caused by the electric machines even after their physical models are available. In this paper, we propose a highly-accurate vibration prediction method that couples experimentally-obtained discrete structural transfer functions and numerically-obtained distributed magnetic-forces. The proposed vibration synthesis methodology has been applied to predict vibration responses of an interior permanent magnet machine. The results show that the predicted vibration response of the electric machine agrees very well with the measured vibration response for several load conditions, for wide frequency ranges. (paper)

Modeling 100,000-year climate fluctuations in pre-Pleistocene time series

Science.gov (United States)

Crowley, Thomas J.; Kim, Kwang-Yul; Mengel, John G.; Short, David A.

1992-01-01

A number of pre-Pleistocene climate records exhibit significant fluctuations at the 100,000-year (100-ky) eccentricity period, before the time of such fluctuations in global ice volume. The origin of these fluctuations has been obscure. Results reported here from a modeling study suggest that such a response can occur over low-altitude land areas involved in monsoon fluctuations. The twice yearly passage of the sun across the equator and the seasonal timing of perihelion interact to increase both 100-ky and 400-ky power in the modeled temperature field. The magnitude of the temperature response is sufficiently large to leave an imprint on the geologic record, and simulated fluctuations resemble those found in records of Triassic lake levels.

BULK THERMODYNAMICS AND CHARGE FLUCTUATIONS AT NON-VANISHING BARYON DENSITY

International Nuclear Information System (INIS)

MIAO, C.; SCHMIDT, C.

2007-01-01

We present results on bulk thermodynamic quantities as well as net baryon number, strangeness and electric charge fluctuations in QCD at non-zero density and temperature obtained from lattice calculations with almost physical quark masses for two values of the lattice cut-off aT = 1/4 and 1/6. We show that with our improved p4fa3-action the cut-off effects are under control when using lattices with a temporal extent of 6 or larger and that the contribution to the equation of state, which is due to a finite chemical potential is small for μ q /T < 1. Moreover, at vanishing chemical potential, i.e. under conditions almost realized at RHIC and the LHC, quartic fluctuations of net baryon number and strangeness are large in a narrow temperature interval characterizing the transition region from the low to high temperature phase. At non-zero baryon number density, strangeness fluctuations are enhanced and correlated to fluctuations of the net baryon number. If strangeness is furthermore forced to vanish, as it may be the case in systems created in heavy ion collisions, strangeness fluctuations are significantly smaller than baryon number fluctuations

Smart electric storage heating and potential for residential demand response

OpenAIRE

Darby, S

2017-01-01

Low-carbon transition plans for temperate and sub-polar regions typically involve some electrification of space heating. This poses challenges to electricity system operation and market design, as it increases overall demand and alters the temporal patterns of that demand. One response to the challenge is to ‘smarten’ electrical heating, enabling it to respond to network conditions by storing energy at times of plentiful supply, releasing it in response to customer demands and offering rapid-...

Residential response to voluntary time-of-use electricity rates

Energy Technology Data Exchange (ETDEWEB)

Mostafa Baladi, S. [Laurits R. Christensen Associates, Inc. Ames, IA 50011-1070 (United States); Herriges, Joseph A. [Iowa State University, 280D Heady Hall, Department of Economics, Iowa State University, Ames, IA 50011-1070 (United States); Sweeney, Thomas J. [MidAmerican Energy, Des Moines, Iowa (United States)

1998-09-01

The response of residential households to voluntary Time-of-Use (TOU) electricity rates is estimated using data from a recent experiment at Midwest Power Systems of Iowa. The study`s design allows us to examine both the participation decision and the customer`s load pattern changes once the TOU rate structure was in effect. Substitution elasticities between on-peak and off-peak electricity usage are estimated and compared to those obtained in earlier mandatory programs, indicating whether program volunteers are more responsive to TOU pricing than the typical household. Attitudinal questionnaires allow us to examine the role of usage perceptions in program participation

Study of fluctuation and turbulance of JFT-2M

Energy Technology Data Exchange (ETDEWEB)

Toyama, Hiroshi; Hanada, Kazuaki; Yamagishi, Kenichi [Tokyo Univ. (Japan)] [and others

1998-01-01

In many improved containment modes, it is said that E x B shear flow formed by shear of radial electric field acts as a mechanism of fluctuation control. In order to understand the mechanism of these improved containment modes, it is necessary to investigate a cause and result relation between controls of fluctuation on formation of sheared flow and fluctuating magnetic wave by using geometrical optics approximation. In this study, the following articles were conducted: (1) to improve a reflectometer with fixed 1-ch frequency using at last fiscal year to one with 2-ch variable frequency to test density fluctuation ranging 0.98 to 3.1 x 10(exp 19)m(sup-3) in density, (2) to examine a relationship between runaway phase and scattering, to propose and application of complex spectrum for usable analytical method even to runaway phase, (3) to study density fluctuation at L-H transition by using this analytical method, and (4) to research cause and result relation of the L-H transition by measuring various plasma parameters by inserting a triple probe array into main plasma. (G.K.)

Study of fluctuation and turbulance of JFT-2M

International Nuclear Information System (INIS)

Toyama, Hiroshi; Hanada, Kazuaki; Yamagishi, Kenichi

1998-01-01

In many improved containment modes, it is said that E x B shear flow formed by shear of radial electric field acts as a mechanism of fluctuation control. In order to understand the mechanism of these improved containment modes, it is necessary to investigate a cause and result relation between controls of fluctuation on formation of sheared flow and fluctuating magnetic wave by using geometrical optics approximation. In this study, the following articles were conducted: 1) to improve a reflectometer with fixed 1-ch frequency using at last fiscal year to one with 2-ch variable frequency to test density fluctuation ranging 0.98 to 3.1 x 10(exp 19)m(sup-3) in density, 2) to examine a relationship between runaway phase and scattering, to propose and application of complex spectrum for usable analytical method even to runaway phase, 3) to study density fluctuation at L-H transition by using this analytical method, and 4) to research cause and result relation of the L-H transition by measuring various plasma parameters by inserting a triple probe array into main plasma. (G.K.)

Analysis of design floor response spectra and testing of the electrical systems

International Nuclear Information System (INIS)

Ambriashvili, Y.

1996-01-01

This report covers the following activities as foreseen according to the working plan of 'Atmoenergoproject': analysis of calculated floor response spectra used during the design of Kozloduy NPP and comparison with other spectra recommended for this NPP; analysis of floor response spectrum for the most important systems (reactor, main coolant loop, electrical systems); tests of main electrical systems and analysis of the results on seismic stability of those systems. Results of the response spectra analysis are given, some of the electrical systems are identified by the Kozloduy authorities to be analyzed in future according to the results of the test on seismicity

Hydrodynamical fluctuations in smooth shear flows

International Nuclear Information System (INIS)

Chagelishvili, G.D.; Khujadze, G.R.; Lominadze, J.G.

1999-11-01

Background of hydrodynamical fluctuations in a intrinsically/stochastically forced, laminar, uniform shear flow is studied. The employment of so-called nonmodal mathematical analysis makes it possible to represent the background of fluctuations in a new light and to get more insight into the physics of its formation. The basic physical processes responsible for the formation of vortex and acoustic wave fluctuation backgrounds are analyzed. Interplay of the processes at low and moderate shear rates is described. Three-dimensional vortex fluctuations around a given macroscopic state are numerically calculated. The correlation functions of the fluctuations of physical quantities are analyzed. It is shown that there exists subspace D k in the wave-number space (k-space) that is limited externally by spherical surface with radius k ν ≡ A/ν (where A is the velocity shear parameter, ν - the kinematic viscosity) in the nonequilibrium open system under study. The spatial Fourier harmonics of vortex as well as acoustic wave fluctuations are strongly subjected by flow shear (by the open character of the system) at wave-numbers satisfying the condition k ν . Specifically it is shown that in D k : The fluctuations are non-Markovian; the spatial spectral density of energy of the vortex fluctuations by far exceeds the white-noise; the term of a new type associated to the hydrodynamical fluctuation of velocity appears in the correlation function of pressure; the fluctuation background of the acoustic waves is completely different at low and moderate shear rates (at low shear rates it is reduced in D k in comparison to the uniform (non-shear) flow; at moderate shear rates it it comparable to the background of the vortex fluctuations). The fluctuation background of both the vortex and the acoustic wave modes is anisotropic. The possible significance of the fluctuation background of vortices for the subcritical transition to turbulence and Brownian motion of small macroscopic

Experimental and numerical study of impact of voltage fluctuate, flicker and power factor wave electric generator to local distribution

Science.gov (United States)

Hadi, Nik Azran Ab; Rashid, Wan Norhisyam Abd; Hashim, Nik Mohd Zarifie; Mohamad, Najmiah Radiah; Kadmin, Ahmad Fauzan

2017-10-01

Electricity is the most powerful energy source in the world. Engineer and technologist combined and cooperated to invent a new low-cost technology and free carbon emission where the carbon emission issue is a major concern now due to global warming. Renewable energy sources such as hydro, wind and wave are becoming widespread to reduce the carbon emissions, on the other hand, this effort needs several novel methods, techniques and technologies compared to coal-based power. Power quality of renewable sources needs in depth research and endless study to improve renewable energy technologies. The aim of this project is to investigate the impact of renewable electric generator on its local distribution system. The power farm was designed to connect to the local distribution system and it will be investigated and analyzed to make sure that energy which is supplied to customer is clean. The MATLAB tools are used to simulate the overall analysis. At the end of the project, a summary of identifying various voltage fluctuates data sources is presented in terms of voltage flicker. A suggestion of the analysis impact of wave power generation on its local distribution is also presented for the development of wave generator farms.

Anal sphincter responses after perianal electrical stimulation

DEFF Research Database (Denmark)

Pedersen, Ejnar; Klemar, B; Schrøder, H D

1982-01-01

By perianal electrical stimulation and EMG recording from the external anal sphincter three responses were found with latencies of 2-8, 13-18 and 30-60 ms, respectively. The two first responses were recorded in most cases. They were characterised by constant latency and uniform pattern, were...... not fatigued by repeated stimulation, were most dependent on placement of stimulating and recording electrodes, and always had a higher threshold than the third response. The third response was constantly present in normal subjects. It had the longest EMG response and the latency decreased with increasing...... stimulation to a minimum of 30-60 ms. This response represented the clinical observable spinal reflex, "the classical anal reflex". The latencies of the two first responses were so short that they probably do not represent spinal reflexes. This was further supported by the effect of epidural anaesthesia which...

Calibration-free absolute frequency response measurement of directly modulated lasers based on additional modulation.

Science.gov (United States)

Zhang, Shangjian; Zou, Xinhai; Wang, Heng; Zhang, Yali; Lu, Rongguo; Liu, Yong

2015-10-15

A calibration-free electrical method is proposed for measuring the absolute frequency response of directly modulated semiconductor lasers based on additional modulation. The method achieves the electrical domain measurement of the modulation index of directly modulated lasers without the need for correcting the responsivity fluctuation in the photodetection. Moreover, it doubles measuring frequency range by setting a specific frequency relationship between the direct and additional modulation. Both the absolute and relative frequency response of semiconductor lasers are experimentally measured from the electrical spectrum of the twice-modulated optical signal, and the measured results are compared to those obtained with conventional methods to check the consistency. The proposed method provides calibration-free and accurate measurement for high-speed semiconductor lasers with high-resolution electrical spectrum analysis.

Noise and fluctuations an introduction

CERN Document Server

MacDonald, D K C

2006-01-01

An understanding of fluctuations and their role is both useful and fundamental to the study of physics. This concise study of random processes offers graduate students and research physicists a survey that encompasses both the relationship of Brownian Movement with statistical mechanics and the problem of irreversible processes. It outlines the basics of the physics involved, without the strictures of mathematical rigor.The three-part treatment starts with a general survey of Brownian Movement, including electrical Brownian Movement and ""shot-noise,"" Part two explores correlation, frequency

An assessment of memristor intrinsic fluctuations: a measurement of single atomic motion

Science.gov (United States)

Borghetti, Julien; Yang, J. Joshua; Medeiros-Ribeiro, Gilberto; Williams, R. Stanley

2010-03-01

Memristors provides electrically tunable resistance for upcoming non-volatile memory and future neuromorphic computing. One of the key benefits of such a device is its scalability, which can be demonstrated from an architectural perspective as well as from a fundamental physics limit. 4D addressing schemes utilizing cross bar structures that can be stacked several layers high above the chip embodies unlimited addressing space. On the other limit, the basic operating principles of memristive devices allow one to reach storage of information in a single atom. In this report of nanoscale (sub 50nm) devices, we detect single atom fluctuations, which would then represent the ultimate limit for noise sources thus delineating the boundary conditions for circuit design. We show that electrically induced individual atom migrations do not affect the overall device atomic configuration until a critical bias where a single local fluctuation triggers a general atomic reconfiguration. This instability illustrates the robustness of the device non-volatility upon small electrical stress.

Duality and reciprocity of fluctuation-dissipation relations in conductors.

Science.gov (United States)

Reggiani, Lino; Alfinito, Eleonora; Kuhn, Tilmann

2016-09-01

By analogy with linear response, we formulate the duality and reciprocity properties of current and voltage fluctuations expressed by Nyquist relations, including the intrinsic bandwidths of the respective fluctuations. For this purpose, we individuate total-number and drift-velocity fluctuations of carriers inside a conductor as the microscopic sources of noise. The spectral densities at low frequency of the current and voltage fluctuations and the respective conductance and resistance are related in a mutually exclusive way to the corresponding noise source. The macroscopic variances of current and voltage fluctuations are found to display a dual property via a plasma conductance that admits a reciprocal plasma resistance. Analogously, the microscopic noise sources are found to obey a dual property and a reciprocity relation. The formulation is carried out in the frame of the grand canonical (for current noise) and canonical (for voltage noise) ensembles, and results are derived that are valid for classical as well as degenerate statistics, including fractional exclusion statistics. The unifying theory so developed sheds new light on the microscopic interpretation of dissipation and fluctuation phenomena in conductors. In particular, it is proven that for fermions, as a consequence of the Pauli principle, nonvanishing single-carrier velocity fluctuations at zero temperature are responsible for diffusion but not for current noise, which vanishes in this limit.

Dynamical critical scaling of electric field fluctuations in the greater cusp and magnetotail implied by HF radar observations of F-region Doppler velocity

Directory of Open Access Journals (Sweden)

M. L. Parkinson

2006-03-01

Full Text Available Akasofu's solar wind ε parameter describes the coupling of solar wind energy to the magnetosphere and ionosphere. Analysis of fluctuations in ε using model independent scaling techniques including the peaks of probability density functions (PDFs and generalised structure function (GSF analysis show the fluctuations were self-affine (mono-fractal, single exponent scaling over 9 octaves of time scale from ~46 s to ~9.1 h. However, the peak scaling exponent α₀ was a function of the fluctuation bin size, so caution is required when comparing the exponents for different data sets sampled in different ways. The same generic scaling techniques revealed the organisation and functional form of concurrent fluctuations in azimuthal magnetospheric electric fields implied by SuperDARN HF radar measurements of line-of-sight Doppler velocity, v_LOS, made in the high-latitude austral ionosphere. The PDFs of v_LOS fluctuation were calculated for time scales between 1 min and 256 min, and were sorted into noon sector results obtained with the Halley radar, and midnight sector results obtained with the TIGER radar. The PDFs were further sorted according to the orientation of the interplanetary magnetic field, as well as ionospheric regions of high and low Doppler spectral width. High spectral widths tend to occur at higher latitude, mostly on open field lines but also on closed field lines just equatorward of the open-closed boundary, whereas low spectral widths are concentrated on closed field lines deeper inside the magnetosphere. The v_LOS fluctuations were most self-affine (i.e. like the solar wind ε parameter on the high spectral width field lines in the noon sector ionosphere (i.e. the greater cusp, but suggested multi-fractal behaviour on closed field lines in the midnight sector (i.e. the central plasma sheet. Long tails in the PDFs imply that "microbursts" in ionospheric convection

Electrical field stimulation-induced excitatory responses of ...

African Journals Online (AJOL)

effect of the endothelium on electrical field stimulation (EFS)-induced excitatory responses of pulmonary artery segments from pulmonary hypertensive rats. Methods: Pulmonary hypertension was induced in rats with a single dose of monocrotaline (60 mg/kg) and 21 days later, arterial rings were set up for isometric tension ...

Rank-ordered multifractal analysis for intermittent fluctuations with global crossover behavior

International Nuclear Information System (INIS)

Tam, Sunny W. Y.; Chang, Tom; Kintner, Paul M.; Klatt, Eric M.

2010-01-01

The rank-ordered multifractal analysis (ROMA), a recently developed technique that combines the ideas of parametric rank ordering and one-parameter scaling of monofractals, has the capabilities of deciphering the multifractal characteristics of intermittent fluctuations. The method allows one to understand the multifractal properties through rank-ordered scaling or nonscaling parametric variables. The idea of the ROMA technique is applied to analyze the multifractal characteristics of the auroral zone electric-field fluctuations observed by the SIERRA sounding rocket. The observed fluctuations span across contiguous multiple regimes of scales with different multifractal characteristics. We extend the ROMA technique such that it can take into account the crossover behavior - with the possibility of collapsing probability distribution functions - over these contiguous regimes.

Systematics of the electric dipole response in stable tin isotopes

Science.gov (United States)

Bassauer, Sergej; von Neumann-Cosel, Peter; Tamii, Atsushi

2018-05-01

The electric dipole is an important property of heavy nuclei. Precise information on the electric dipole response provides information on the electric dipole polarisability which in turn allows to extract important constraints on neutron-skin thickness in heavy nuclei and parameters of the symmetry energy. The tin isotope chain is particularly suited for a systematic study of the dependence of the electric dipole response on neutron excess as it provides a wide mass range of accessible isotopes with little change of the underlying structure. Recently an inelastic proton scattering experiment under forward angles including 0º on 112,116,124Sn was performed at the Research Centre for Nuclear Physics (RCNP), Japan with a focus on the low-energy dipole strength and the polarisability. First results are presented here. Using data from an earlier proton scattering experiment on 120Sn the gamma strength function and level density are determined for this nucleus.

Systematics of the electric dipole response in stable tin isotopes

Directory of Open Access Journals (Sweden)

Bassauer Sergej

2018-01-01

Full Text Available The electric dipole is an important property of heavy nuclei. Precise information on the electric dipole response provides information on the electric dipole polarisability which in turn allows to extract important constraints on neutron-skin thickness in heavy nuclei and parameters of the symmetry energy. The tin isotope chain is particularly suited for a systematic study of the dependence of the electric dipole response on neutron excess as it provides a wide mass range of accessible isotopes with little change of the underlying structure. Recently an inelastic proton scattering experiment under forward angles including 0º on 112,116,124Sn was performed at the Research Centre for Nuclear Physics (RCNP, Japan with a focus on the low-energy dipole strength and the polarisability. First results are presented here. Using data from an earlier proton scattering experiment on 120Sn the gamma strength function and level density are determined for this nucleus.

Design of the electromagnetic fluctuations diagnostic for MFTF-B

International Nuclear Information System (INIS)

House, P.A.; Goerz, D.A.; Martin, R.

1983-01-01

The Electromagnetic Fluctuations (EMF) diagnostic will be used to monitor ion fluctuations which could be unstable in MFTF-B. Each probe assembly includes a high impedance electrostatic probe to measure potential fluctuations, and a group of nested, single turn loops to measure magnetic fluctuations in three directions. Eventually, more probes and loops will be added to each probe assembly for making more detailed measurements. The sensors must lie physically close to the plasma edge and are radially positionable. Also, probes at separate axial locations can be positioned to connect along the same magnetic field line. These probes are similar in concept to the rf probes used on TMX, but the high thermal load for 30-second shots on MFTF-B requires a water-cooled design along with temperature monitors. Each signal channel has a bandwidth of .001 to 150 MHz and is monitored by up to four different data channels which obtain amplitude and frequency information. This paper describes the EMF diagnostic and presents the detailed mechanical and electrical designs

Electric fields and monopole currents in compact QED

International Nuclear Information System (INIS)

Zach, M.; Faber, M.; Kainz, W.; Skala, P.

1995-01-01

The confinement in compact QED is known to be related to magnetic monopoles. Magnetic currents form a solenoid around electric flux lines between a pair of electric charges. This behaviour can be described by the dual version of Maxwell-London equations including a fluctuating string. We use a definition of magnetic monopole currents adjusted to the definition of the electric field strength on a lattice and get good agreement for field and current distributions between compact QED and the predictions of dual Maxwell-London equations. Further we show that the monopole fluctuations in the vacuum are suppressed by the flux tube. ((orig.))

Electrical resistivity dynamics beneath a fractured sedimentary bedrock riverbed in response to temperature and groundwater–surface water exchange

Directory of Open Access Journals (Sweden)

C. M. Steelman

2017-06-01

ice during the winter season. We show that surface electrical resistivity methods have the capacity to detect and resolve electrical resistivity transience beneath a fractured bedrock riverbed in response to porewater temperature and specific conductance fluctuations over a complete annual cycle.

Effects of limited spatial resolution on fluctuation measurements

International Nuclear Information System (INIS)

Bravenec, R.V.; Wootton, A.J.

1994-01-01

The finite sample volumes of fluctuation diagnostics distort the measurements not only by averaging the gross fluctuation parameters over the sample volumes, but more importantly (except for collective scattering), by attenuating the shorter wavelength components. In this work the response of various sample volume sizes and orientations to a model fluctuation power spectrum S(k,ω) are examined. The model spectrum is fashioned after observations by far-infrared scattering on TEXT. The sample-volume extent in the direction of propagation of the turbulence is shown to be the most critical - not only does it reduce the measured fluctuation amplitude and correlation length (as does an extent perpendicular to the propagation direction), but also reduces the measured mean frequency and increases the apparent average phase velocity of the fluctuations. The differing sizes, shapes, and orientations of the sample volumes among fluctuation diagnostics, as well as deliberate variations within a single diagnostic, provide information on the form of the underlying turbulence and can be exploited to refine the model

Electrostatic potential fluctuation induced by charge discreteness in a nanoscale trench

International Nuclear Information System (INIS)

Lee, Taesang; Kim, S. S.; Jho, Y. S.; Park, Gunyoung; Chang, C. S.

2007-01-01

A simplified two-dimensional Monte Carlo simulation is performed to estimate the charging potential fluctuations caused by strong binary Coulomb interactions between discrete charged particles in nanometer scale trenches. It is found that the discrete charge effect can be an important part of the nanoscale trench research, inducing scattering of ion trajectories in a nanoscale trench by a fluctuating electric field. The effect can enhance the ion deposition on the side walls and disperse the material contact energy of the incident ions, among others

Nematic liquid crystal in a cylindrical sample: Theoretical analysis of the electrical response

Science.gov (United States)

Gomes, O. A.; Yednak, C. A. R.; da Silva, B. V. H. V.; Teixeira-Souza, R. T.

2018-02-01

The electrical responses of a nematic liquid crystal sample confined between two cylindrical surfaces are investigated in the framework of elastic continuum theory. The responses are the result of the molecular reorientation induced by both the applied electric field and the cylindrical geometry of the sample. The nematic medium is considered as a parallel RC circuit since the capacitance and the resistance are under the same difference of potential. The electrical properties, including the total electric current, are determined from the molecular reorientation of the director. The elastic anisotropy has been shown to influence substantially the profile of the electrical current, capacitance, and resistance characterizing the equivalent circuit for the medium.

Electrostatic fluctuations measured in low temperature helical plasmas with low collisionality

International Nuclear Information System (INIS)

Takeuchi, M.; Ikeda, R.; Ito, T.; Toi, K.; Suzuki, C.; Matsunaga, G.

2004-01-01

Electrostatic fluctuations have been measured by Langmuir probes from edge to core plasma region in low temperature helical plasmas which are produced by 2.45 GHz microwaves at very low field less than 0.1 T. The principal dimensionless parameters of the plasmas, that is, the normalized electron-ion collision frequency ν ei , and averaged plasma β φ and others are in the same range of them in high temperature plasmas, except the normalized gyro radius ρ s . The data on fluctuation characteristics from the dimensionally similar low temperature plasmas may give an important insight into the understanding of turbulent transport in high temperature plasmas. Dependences of fluctuation amplitudes on the radial electric field shear, ρ s and ν ei are investigated. Electrostatic fluctuations propagating in electron-diamagnetic drift direction have been observed in the plasma edge region and in ion-diamagnetic drift direction in the plasma core region. (authors)

Role of excited state solvent fluctuations on time-dependent fluorescence Stokes shift

Energy Technology Data Exchange (ETDEWEB)

Li, Tanping, E-mail: tanping@lsu.edu, E-mail: revatik@lsu.edu; Kumar, Revati, E-mail: tanping@lsu.edu, E-mail: revatik@lsu.edu [Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)

2015-11-07

We explore the connection between the solvation dynamics of a chromophore upon photon excitation and equilibrium fluctuations of the solvent. Using molecular dynamics simulations, fluorescence Stokes shift for the tryptophan in Staphylococcus nuclease was examined using both nonequilibrium calculations and linear response theory. When the perturbed and unperturbed surfaces exhibit different solvent equilibrium fluctuations, the linear response approach on the former surface shows agreement with the nonequilibrium process. This agreement is excellent when the perturbed surface exhibits Gaussian statistics and qualitative in the case of an isomerization induced non-Gaussian statistics. However, the linear response theory on the unperturbed surface breaks down even in the presence of Gaussian fluctuations. Experiments also provide evidence of the connection between the excited state solvent fluctuations and the total fluorescence shift. These observations indicate that the equilibrium statistics on the excited state surface characterize the relaxation dynamics of the fluorescence Stokes shift. Our studies specifically analyze the Gaussian fluctuations of the solvent in the complex protein environment and further confirm the role of solvent fluctuations on the excited state surface. The results are consistent with previous investigations, found in the literature, of solutes dissolved in liquids.

Public-policy responsibilities in a restructured electricity industry

Energy Technology Data Exchange (ETDEWEB)

Tonn, B.; Hirst, E.; Bauer, D.

1995-06-01

In this report, we identify and define the key public-policy values, objectives, and actions that the US electricity industry currently meets. We also discuss the opportunities for meeting these objectives in a restructured industry that relies primarily on market forces rather than on government mandates. And we discuss those functions that governments might undertake, presumably because they will not be fully met by a restructured industry on its own. These discussions are based on a variety of inputs. The most important inputs came from participants in an April 1995 workshop on Public-Policy Responsibilities and Electric Industry Restructuring: Shaping the Research Agenda. Other sources of information and insights include the reviews of a draft of this report by workshop participants and others and the rapidly growing literature on electric-industry restructuring and its implications. One of the major concerns about the future of the electricity industry is the fate of numerous social and environmental programs supported by today`s electric utilities. Many people worry that a market-driven industry may not meet the public-policy objectives that electric utilities have met in the past. Examples of potentially at-risk programs include demand-side management (DSM), renewable energy, low-income weatherization, and fuel diversity. Workshop participants represented electric utilities, public utility commissions (PUCs), state energy offices, public-interest groups, other energy providers, and the research community.

Dynamic Response Testing in an Electrically Heated Reactor Test Facility

Science.gov (United States)

Bragg-Sitton, Shannon M.; Morton, T. J.

2006-01-01

Non-nuclear testing can be a valuable tool in development of a space nuclear power or propulsion system. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Standard testing allows one to fully assess thermal, heat transfer, and stress related attributes of a given system, but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. The integration of thermal hydraulic hardware tests with simulated neutronic response provides a bridge between electrically heated testing and full nuclear testing. By implementing a neutronic response model to simulate the dynamic response that would be expected in a fueled reactor system, one can better understand system integration issues, characterize integrated system response times and response characteristics, and assess potential design improvements at a relatively small fiscal investment. Initial system dynamic response testing was demonstrated on the integrated SAFE-100a heat pipe cooled, electrically heated reactor and heat exchanger hardware, utilizing a one-group solution to the point kinetics equations to simulate the expected neutronic response of the system (Bragg-Sitton, 2005). The current paper applies the same testing methodology to a direct drive gas cooled reactor system, demonstrating the applicability of the testing methodology to any reactor type and demonstrating the variation in system response characteristics in different reactor concepts. In each testing application, core power transients were controlled by a point kinetics model with reactivity feedback based on core average temperature; the neutron generation time and the temperature feedback coefficient are provided as model inputs. Although both system designs utilize a fast spectrum reactor, the method of cooling the reactor differs significantly, leading to a variable system response that can be demonstrated and assessed in a non-nuclear test facility.

Conserved charge fluctuations at vanishing and non-vanishing chemical potential

Science.gov (United States)

Karsch, Frithjof

2017-11-01

Up to 6th order cumulants of fluctuations of net baryon-number, net electric charge and net strangeness as well as correlations among these conserved charge fluctuations are now being calculated in lattice QCD. These cumulants provide a wealth of information on the properties of strong-interaction matter in the transition region from the low temperature hadronic phase to the quark-gluon plasma phase. They can be used to quantify deviations from hadron resonance gas (HRG) model calculations which frequently are used to determine thermal conditions realized in heavy ion collision experiments. Already some second order cumulants like the correlations between net baryon-number and net strangeness or net electric charge differ significantly at temperatures above 155 MeV in QCD and HRG model calculations. We show that these differences increase at non-zero baryon chemical potential constraining the applicability range of HRG model calculations to even smaller values of the temperature.

Controlling Electricity Consumption by Forecasting its Response to Varying Prices

DEFF Research Database (Denmark)

Corradi, Olivier; Ochsenfeld, Henning Peter; Madsen, Henrik

2013-01-01

electricity consumption using a one-way price signal. Estimation of the price-response is based on data measurable at grid level, removing the need to install sensors and communication devices between each individual consumer and the price-generating entity. An application for price-responsive heating systems......In a real-time electricity pricing context where consumers are sensitive to varying prices, having the ability to anticipate their response to a price change is valuable. This paper proposes models for the dynamics of such price-response, and shows how these dynamics can be used to control...... is studied based on real data, before conducting a control by price experiment using a mixture of real and synthetic data. With the control objective of following a constant consumption reference, peak heating consumption is reduced by nearly 5%, and 11% of the mean daily heating consumption is shifted....

Critical Fluctuations in Spatial Complex Networks

Science.gov (United States)

Bradde, Serena; Caccioli, Fabio; Dall'Asta, Luca; Bianconi, Ginestra

2010-05-01

An anomalous mean-field solution is known to capture the nontrivial phase diagram of the Ising model in annealed complex networks. Nevertheless, the critical fluctuations in random complex networks remain mean field. Here we show that a breakdown of this scenario can be obtained when complex networks are embedded in geometrical spaces. Through the analysis of the Ising model on annealed spatial networks, we reveal, in particular, the spectral properties of networks responsible for critical fluctuations and we generalize the Ginsburg criterion to complex topologies.

Power fluctuation reduction methodology for the grid-connected renewable power systems

Science.gov (United States)

Aula, Fadhil T.; Lee, Samuel C.

2013-04-01

This paper presents a new methodology for eliminating the influence of the power fluctuations of the renewable power systems. The renewable energy, which is to be considered an uncertain and uncontrollable resource, can only provide irregular electrical power to the power grid. This irregularity creates fluctuations of the generated power from the renewable power systems. These fluctuations cause instability to the power system and influence the operation of conventional power plants. Overall, the power system is vulnerable to collapse if necessary actions are not taken to reduce the impact of these fluctuations. This methodology aims at reducing these fluctuations and makes the generated power capability for covering the power consumption. This requires a prediction tool for estimating the generated power in advance to provide the range and the time of occurrence of the fluctuations. Since most of the renewable energies are weather based, as a result a weather forecast technique will be used for predicting the generated power. The reduction of the fluctuation also requires stabilizing facilities to maintain the output power at a desired level. In this study, a wind farm and a photovoltaic array as renewable power systems and a pumped-storage and batteries as stabilizing facilities are used, since they are best suitable for compensating the fluctuations of these types of power suppliers. As an illustrative example, a model of wind and photovoltaic power systems with battery energy and pumped hydro storage facilities for power fluctuation reduction is included, and its power fluctuation reduction is verified through simulation.

Emergency management in the Swedish electricity market: The need to challenge the responsibility gap

International Nuclear Information System (INIS)

Palm, Jenny

2008-01-01

A secure energy supply is a basic need of society. Along with electricity market deregulation, a responsibility gap has arisen, where private energy companies lack economic incentives to invest in an electricity distribution grid that is secured to the level desired by society. This article discusses the emergency management strategies of municipal authorities for securing the electricity supply, according to a networked, or 'governance', control and direction structure, and how this influences the relationship between electricity companies and Swedish municipalities. The Swedish electricity system has traditionally developed in a monopoly context. Since electricity market deregulation, the responsibility for electricity supply security has become unclear; field studies of Swedish municipalities indicate that all actors still seem to be seeking to find their proper roles in the deregulated market. Municipalities still expect to exercise influence over private energy company decisions regarding prioritization of emergency power deliveries. Energy companies vacillate between emphasizing their need to regard economic factors and their sense of responsibility for providing a secure electricity supply to vital municipal functions (even though municipalities may lack contracts specifying this)

Use of demand response in electricity markets

DEFF Research Database (Denmark)

Singh, Sri Niwas; Østergaard, Jacob

2010-01-01

Demand response (DR) can provide sufficient measure, if implemented successfully, to provide economic, secure and stable supply to the customers even under the variability of the generated output from renewable energy source such as wind and solar. However, there are several issues to be analyzed...... before DR implementation. This paper critically examines the present practices of the DR in the various electricity markets existing in the world including Europe. The prospect of DR in various market levels such as day-ahead (spot) market, hour-ahead market, real time/regulating market and ancillary...... market is analyzed. This paper also addresses the key issues and challenges in the implementation of DR in the electricity markets....

Battery prices and capacity sensitivity: Electric drive vehicles

DEFF Research Database (Denmark)

Juul, Nina

2012-01-01

, the prices at which the electric drive vehicles become of interest to the power system are found. Smart charge, including the opportunity to discharge (vehicle-to-grid) is used in all scenarios. Analyses show that the marginal benefits decrease the larger the battery. For very high battery prices, large......The increase in fluctuating power production requires an increase in flexibility in the system as well. Flexibility can be found in generation technologies with fast response times or in storage options. In the transport sector, the proportion of electric drive vehicles is expected to increase over...... the next decade or two. These vehicles can provide some of the flexibility needed in the power system, in terms of both flexible demand and electricity storage. However, what are the batteries worth to the power system? And does the value depend on battery capacity? This article presents an analysis...

Electric Water Heater Modeling and Control Strategies for Demand Response

Energy Technology Data Exchange (ETDEWEB)

Diao, Ruisheng; Lu, Shuai; Elizondo, Marcelo A.; Mayhorn, Ebony T.; Zhang, Yu; Samaan, Nader A.

2012-07-22

Abstract— Demand response (DR) has a great potential to provide balancing services at normal operating conditions and emergency support when a power system is subject to disturbances. Effective control strategies can significantly relieve the balancing burden of conventional generators and reduce investment on generation and transmission expansion. This paper is aimed at modeling electric water heaters (EWH) in households and tests their response to control strategies to implement DR. The open-loop response of EWH to a centralized signal is studied by adjusting temperature settings to provide regulation services; and two types of decentralized controllers are tested to provide frequency support following generator trips. EWH models are included in a simulation platform in DIgSILENT to perform electromechanical simulation, which contains 147 households in a distribution feeder. Simulation results show the dependence of EWH response on water heater usage . These results provide insight suggestions on the need of control strategies to achieve better performance for demand response implementation. Index Terms— Centralized control, decentralized control, demand response, electrical water heater, smart grid

Modeling of demand response in electricity markets : effects of price elasticity

International Nuclear Information System (INIS)

Banda, E.C.; Tuan, L.A.

2007-01-01

A design mechanism for the optimal participation of customer load in electricity markets was presented. In particular, this paper presented a modified market model for the optimal procurement of interruptible loads participating in day-ahead electricity markets. The proposed model considers the effect of price elasticity and demand-response functions. The objective was to determine the role that price elasticity plays in electricity markets. The simulation model can help the Independent System Operator (ISO) identify customers offering the lowest price of interruptible loads and load flow patterns that avoid problems associated with transmission congestion and transmission losses. Various issues associated with procurement of demand-response offerings such as advance notification, locational aspect of load, and power factor of the loads, were considered. It was shown that demand response can mitigate price volatility by allowing the ISO to maintain operating reserves during peak load periods. It was noted that the potential benefits of the demand response program would be reduced when price elasticity of demand is taken into account. This would most likely occur in actual developed open electricity markets, such as Nordpool. This study was based on the CIGRE 32-bus system, which represents the Swedish high voltage power system. It was modified for this study to include a broad range of customer characteristics. 18 refs., 2 tabs., 14 figs

Evaluation of the constant potential method in simulating electric double-layer capacitors

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhenxing; Laird, Brian B., E-mail: blaird@ku.edu [Department of Chemistry, University of Kansas, Lawrence, Kansas 66045 (United States); Yang, Yang; Olmsted, David L.; Asta, Mark [Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States)

2014-11-14

A major challenge in the molecular simulation of electric double layer capacitors (EDLCs) is the choice of an appropriate model for the electrode. Typically, in such simulations the electrode surface is modeled using a uniform fixed charge on each of the electrode atoms, which ignores the electrode response to local charge fluctuations in the electrolyte solution. In this work, we evaluate and compare this Fixed Charge Method (FCM) with the more realistic Constant Potential Method (CPM), [S. K. Reed et al., J. Chem. Phys. 126, 084704 (2007)], in which the electrode charges fluctuate in order to maintain constant electric potential in each electrode. For this comparison, we utilize a simplified LiClO{sub 4}-acetonitrile/graphite EDLC. At low potential difference (ΔΨ ⩽ 2 V), the two methods yield essentially identical results for ion and solvent density profiles; however, significant differences appear at higher ΔΨ. At ΔΨ ⩾ 4 V, the CPM ion density profiles show significant enhancement (over FCM) of “inner-sphere adsorbed” Li{sup +} ions very close to the electrode surface. The ability of the CPM electrode to respond to local charge fluctuations in the electrolyte is seen to significantly lower the energy (and barrier) for the approach of Li{sup +} ions to the electrode surface.

Evaluation of the constant potential method in simulating electric double-layer capacitors

International Nuclear Information System (INIS)

Wang, Zhenxing; Laird, Brian B.; Yang, Yang; Olmsted, David L.; Asta, Mark

2014-01-01

A major challenge in the molecular simulation of electric double layer capacitors (EDLCs) is the choice of an appropriate model for the electrode. Typically, in such simulations the electrode surface is modeled using a uniform fixed charge on each of the electrode atoms, which ignores the electrode response to local charge fluctuations in the electrolyte solution. In this work, we evaluate and compare this Fixed Charge Method (FCM) with the more realistic Constant Potential Method (CPM), [S. K. Reed et al., J. Chem. Phys. 126, 084704 (2007)], in which the electrode charges fluctuate in order to maintain constant electric potential in each electrode. For this comparison, we utilize a simplified LiClO 4 -acetonitrile/graphite EDLC. At low potential difference (ΔΨ ⩽ 2 V), the two methods yield essentially identical results for ion and solvent density profiles; however, significant differences appear at higher ΔΨ. At ΔΨ ⩾ 4 V, the CPM ion density profiles show significant enhancement (over FCM) of “inner-sphere adsorbed” Li + ions very close to the electrode surface. The ability of the CPM electrode to respond to local charge fluctuations in the electrolyte is seen to significantly lower the energy (and barrier) for the approach of Li + ions to the electrode surface

Calculation of gas gain fluctuations in uniform fields

CERN Document Server

Schindler, H; Veenhof, R

2010-01-01

Fluctuations of the charge amplification factor (gain) are a key element for assessing the performance of gas-based particle detectors In this report we present Monte Carlo calculations of electron avalanches based on the Magboltz program In terms of a simple model extracted from the simulation an intuitive explanation for the impact of the gas mixture and the electric field on the gain spectrum is proposed.

Inverse scattering problem in turbulent magnetic fluctuations

Directory of Open Access Journals (Sweden)

R. A. Treumann

2016-08-01

Full Text Available We apply a particular form of the inverse scattering theory to turbulent magnetic fluctuations in a plasma. In the present note we develop the theory, formulate the magnetic fluctuation problem in terms of its electrodynamic turbulent response function, and reduce it to the solution of a special form of the famous Gelfand–Levitan–Marchenko equation of quantum mechanical scattering theory. The last of these applies to transmission and reflection in an active medium. The theory of turbulent magnetic fluctuations does not refer to such quantities. It requires a somewhat different formulation. We reduce the theory to the measurement of the low-frequency electromagnetic fluctuation spectrum, which is not the turbulent spectral energy density. The inverse theory in this form enables obtaining information about the turbulent response function of the medium. The dynamic causes of the electromagnetic fluctuations are implicit to it. Thus, it is of vital interest in low-frequency magnetic turbulence. The theory is developed until presentation of the equations in applicable form to observations of turbulent electromagnetic fluctuations as input from measurements. Solution of the final integral equation should be done by standard numerical methods based on iteration. We point to the possibility of treating power law fluctuation spectra as an example. Formulation of the problem to include observations of spectral power densities in turbulence is not attempted. This leads to severe mathematical problems and requires a reformulation of inverse scattering theory. One particular aspect of the present inverse theory of turbulent fluctuations is that its structure naturally leads to spatial information which is obtained from the temporal information that is inherent to the observation of time series. The Taylor assumption is not needed here. This is a consequence of Maxwell's equations, which couple space and time evolution. The inversion procedure takes

Detrended fluctuation analysis made flexible to detect range of cross-correlated fluctuations

Science.gov (United States)

Kwapień, Jarosław; Oświecimka, Paweł; DroŻdŻ, Stanisław

2015-11-01

The detrended cross-correlation coefficient ρDCCA has recently been proposed to quantify the strength of cross-correlations on different temporal scales in bivariate, nonstationary time series. It is based on the detrended cross-correlation and detrended fluctuation analyses (DCCA and DFA, respectively) and can be viewed as an analog of the Pearson coefficient in the case of the fluctuation analysis. The coefficient ρDCCA works well in many practical situations but by construction its applicability is limited to detection of whether two signals are generally cross-correlated, without the possibility to obtain information on the amplitude of fluctuations that are responsible for those cross-correlations. In order to introduce some related flexibility, here we propose an extension of ρDCCA that exploits the multifractal versions of DFA and DCCA: multifractal detrended fluctuation analysis and multifractal detrended cross-correlation analysis, respectively. The resulting new coefficient ρq not only is able to quantify the strength of correlations but also allows one to identify the range of detrended fluctuation amplitudes that are correlated in two signals under study. We show how the coefficient ρq works in practical situations by applying it to stochastic time series representing processes with long memory: autoregressive and multiplicative ones. Such processes are often used to model signals recorded from complex systems and complex physical phenomena like turbulence, so we are convinced that this new measure can successfully be applied in time-series analysis. In particular, we present an example of such application to highly complex empirical data from financial markets. The present formulation can straightforwardly be extended to multivariate data in terms of the q -dependent counterpart of the correlation matrices and then to the network representation.

Mercury exposure may influence fluctuating asymmetry in waterbirds

Science.gov (United States)

Herring, Garth; Eagles-Smith, Collin A.; Ackerman, Joshua T.

2017-01-01

Variation in avian bilateral symmetry can be an indicator of developmental instability in response to a variety of stressors, including environmental contaminants. The authors used composite measures of fluctuating asymmetry to examine the influence of mercury concentrations in 2 tissues on fluctuating asymmetry within 4 waterbird species. Fluctuating asymmetry increased with mercury concentrations in whole blood and breast feathers of Forster's terns (Sterna forsteri), a species with elevated mercury concentrations. Specifically, fluctuating asymmetry in rectrix feather 1 was the most strongly correlated structural variable of those tested (wing chord, tarsus, primary feather 10, rectrix feather 6) with mercury concentrations in Forster's terns. However, for American avocets (Recurvirostra americana), black-necked stilts (Himantopus mexicanus), and Caspian terns (Hydroprogne caspia), the authors found no relationship between fluctuating asymmetry and either whole-blood or breast feather mercury concentrations, even though these species had moderate to elevated mercury exposure. The results indicate that mercury contamination may act as an environmental stressor during development and feather growth and contribute to fluctuating asymmetry of some species of highly contaminated waterbirds.

Enhanced electric and magnetic response of a THz sub-wavelength fiber excited by a localized source

DEFF Research Database (Denmark)

Atakaramians, Shaghik; Stefani, Alessio; Shardivov, Ilya V.

2017-01-01

the magnetic response of the coupled system when excited with an electric dipole oriented along the circumference of the fiber. This result introduces a new platform for achieving enhanced magnetic response, which is the fundamental building block for metamaterial devices. Here we investigate experimentally......Recently we have shown that a nanofiber excited by a localized electric source can have enhanced electric and magnetic response depending of the relative orientation of the source and the fiber [1]. We have demonstrated that the dielectric nanofiber can suppress the electric response and enhance...

Electrostatic fluctuations in soap films

International Nuclear Information System (INIS)

Dean, D.S.; Horgan, R.R.

2002-01-01

A field theory to describe electrostatic interactions in soap films, described by electric multilayers with a generalized thermodynamic surface-charging mechanism, is studied. In the limit where the electrostatic interactions are weak, this theory is exactly soluble. The theory incorporates in a consistent way, the surface-charging mechanism and the fluctuations in the electrostatic field that correspond to the zero-frequency component of the van der Waals force. It is shown that these terms lead to a Casimir-like attraction that can be sufficiently large to explain the transition between the common black film to a Newton black film

Microscopic origin of gating current fluctuations in a potassium channel voltage sensor.

Science.gov (United States)

Freites, J Alfredo; Schow, Eric V; White, Stephen H; Tobias, Douglas J

2012-06-06

Voltage-dependent ion channels open and close in response to changes in membrane electrical potential due to the motion of their voltage-sensing domains (VSDs). VSD charge displacements within the membrane electric field are observed in electrophysiology experiments as gating currents preceding ionic conduction. The elementary charge motions that give rise to the gating current cannot be observed directly, but appear as discrete current pulses that generate fluctuations in gating current measurements. Here we report direct observation of gating-charge displacements in an atomistic molecular dynamics simulation of the isolated VSD from the KvAP channel in a hydrated lipid bilayer on the timescale (10-μs) expected for elementary gating charge transitions. The results reveal that gating-charge displacements are associated with the water-catalyzed rearrangement of salt bridges between the S4 arginines and a set of conserved acidic side chains on the S1-S3 transmembrane segments in the hydrated interior of the VSD. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Grid Integration of Electric Vehicles in Open Electricity Markets

DEFF Research Database (Denmark)

congestion management scenario within electric distribution networks •optimal EV charging management with the fleet operator concept and smart charging management •EV battery technology, modelling and tests •the use of EVs for balancing power fluctuations from renewable energy sources, looking at power......Presenting the policy drivers, benefits and challenges for grid integration of electric vehicles (EVs) in the open electricity market environment, this book provides a comprehensive overview of existing electricity markets and demonstrates how EVs are integrated into these different markets...... of the technologies for EV integration, this volume is informative for research professors and graduate students in power systems; it will also appeal to EV manufacturers, regulators, EV market professionals, energy providers and traders, mobility providers, EV charging station companies, and policy makers....

Statistical fluctuations of the number of neutrons in a pile; Fluctuations statistiques du nombre de neutrons dans une pile

Energy Technology Data Exchange (ETDEWEB)

Raievski, V [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

The theory of the statistical fluctuations in a pile is extended to the space dependent case, and gives the fluctuations of the number of neutrons in a cell of the core or reflector of the pile. This number changes through elementary processes occurring at random, which are, capture, source, fission and scattering. Of all these processes, fission is the only one which changes more than one neutron at a time and so is responsible of the deviation of the fluctuations from a Poisson law. The importance of this deviation depends on the dimensions of the cell compared to the slowing down length. When the dimensions are small, the fluctuations close to a Poisson law. (author) [French] La theorie des fluctuations statistiques est etendue au cas local et donne les fluctuations du nombre de neutrons dans une cellule situee dans le coeur ou le reflecteur de la pile. Ce nombre evolue au cours du temps sous l'influence de phenomenes aleatoires qui sont la capture, la diffusion, les sources et les neutrons secondaires de fission. L'emission simultanee de plusieurs neutrons distingue ce phenomene des precedents qui n'affectent qu'un neutron individuellement. L'importance de ce phenomene sur la loi de fluctuation depend des dimensions de la cellule par rapport a la longueur de ralentissement. Quand ces dimensions sont petites, le caractere particulier de ce phenomene disparait. (auteur)

Observation of voltage fluctuations in a superconducting magnet during MHD power generation

International Nuclear Information System (INIS)

Smith, R.P.; Niemann, R.C.; Kraimer, M.R.; Zinneman, T.E.

1978-01-01

Fluctuating voltage signals on the potential taps of the ANL 5.0 T MHD Superconducting Dipole Magnet have been observed during MHD power generation at the U-25B Facility at the High Temperature Institute (IVTAN) Moscow, USSR. Various other thermodynamic and electrical parameters of the U-25B flow train have been recorded, and statistical analysis concerning correlations between the phenomena with a view of discerning causal interdependence is in progress. Voltage fluctuations observed at the magnet terminals are analyzed with special emphasis on magnet stability

Multiscale response of ionic systems to a spatially varying electric field

DEFF Research Database (Denmark)

Hansen, Jesper Schmidt

2017-01-01

In this paper the response of ionic systems subjected to a spatially varying electric field is studied. Following the Nernst-Planck equation, two forces driving the mass flux are present, namely, the concentration gradient and the electric potential gradient. The mass flux due to the concentratio...

Demand response in Indian electricity market

International Nuclear Information System (INIS)

Siddiqui, Md Zakaria; Maere d'Aertrycke, Gauthier de; Smeers, Yves

2012-01-01

This paper outlines a methodology for implementing cost of service regulation in retail market for electricity in India when wholesale market is liberalised and operates through an hourly spot market. As in a developing country context political considerations make tariff levels more important than supply security, satisfying the earmarked level of demand takes a back seat. Retail market regulators are often forced by politicians to keep the retail tariff at suboptimal level. This imposes budget constraint on distribution companies to procure electricity that it requires to meet the earmarked level of demand. This is the way demand response is introduced in the system and has its impact on spot market prices. We model such a situation of not being able to serve the earmarked demand as disutility to the regulator which has to be minimised and we compute associated equilibrium. This results in systematic mechanism for cutting loads. We find that even a small cut in ability of the distribution companies to procure electricity from the spot market has profound impact on the prices in the spot market. - Highlights: ► Modelling the impact of retail tariff in different states on spot prices of electricity in India. ► Retail tariffs are usually fixed below appropriate levels by states due to political reasons. ► Due to revenue constraint distribution utility withdraws demand from spot market in peak hours. ► This adversely affects the scarcity rent of generators and subsequently future investment. ► We show possibility of strategic behaviour among state level regulators in setting retail tariff.

The synthesis and the electric-responsiveness of hydrogels entrapping natural polyelectrolyte

International Nuclear Information System (INIS)

Sutani, Kouichi; Kaetsu, Isao; Uchida, Kumao

2001-01-01

A mixture of vinyl monomer, a natural polyelectrolyte--hyaluronic acid--and crosslinker was polymerized and crosslinked to entrap the natural polymer into the synthetic gel. The controlled release of the model drug from the obtained gel was studied under the on-off switching of electric field. It was proved that electric-responsive drug releases were possible using hyaluronic acid entrapping gel and the electro-responsiveness was greatly affected by various factors such as degree of swelling, crosslinking density, kind and composition of vinyl monomer and crosslinkers

The synthesis and the electric-responsiveness of hydrogels entrapping natural polyelectrolyte

Science.gov (United States)

Sutani, Kouichi; Kaetsu, Isao; Uchida, Kumao

2001-04-01

A mixture of vinyl monomer, a natural polyelectrolyte—hyaluronic acid—and crosslinker was polymerized and crosslinked to entrap the natural polymer into the synthetic gel. The controlled release of the model drug from the obtained gel was studied under the on-off switching of electric field. It was proved that electric-responsive drug releases were possible using hyaluronic acid entrapping gel and the electro-responsiveness was greatly affected by various factors such as degree of swelling, crosslinking density, kind and composition of vinyl monomer and crosslinkers.

Longitudinal fluctuations and decorrelation of anisotropic flow

Energy Technology Data Exchange (ETDEWEB)

Pang, Long-Gang [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Petersen, Hannah [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Qin, Guang-You [Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Roy, Victor [Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Wang, Xin-Nian [Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Nuclear Science Division MS70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2016-12-15

We investigate the decorrelation of 2nd and 3rd order anisotropic flow for charged particles in two different pseudo rapidity (η) windows by varying the pseudo rapidity gap, in an event-by-event (3+1)D ideal hydrodynamic model, with fluctuating initial conditions from A Multi-Phase Transport (AMPT) model. We visualize the parton distribution at initial state for Pb+Pb collisions at LHC and Au+Au collisions at RHIC, and demonstrate the longitudinal fluctuations originating from the asymmetry between forward and backward going participants, the fluctuations of the string length and the fluctuations due to finite number of partons at different beam energies. The decorrelation of anisotropic flow of final hadrons with large η gaps is found to originate from the spatial decorrelation along the longitudinal direction in the AMPT initial conditions through hydrodynamic evolution. The agreement between our results and recent CMS data in most centralities suggests that the string-like mechanism of initial parton production in AMPT model captures the initial longitudinal fluctuation that is responsible for the measured decorrelation of anisotropic flow in Pb+Pb collisions at LHC. Our predictions for Au+Au collisions at the highest RHIC energy show stronger longitudinal decorrelation than at LHC, indicating larger longitudinal fluctuations at lower beam energies.

Critical thermal limits affected differently by developmental and adult thermal fluctuations

DEFF Research Database (Denmark)

Salachan, Paul Vinu; Sørensen, Jesper Givskov

2017-01-01

the developmental and adult life stages. For developmental acclimation, we found mildly detrimental effects of high amplitude fluctuations for critical thermal minima, while the critical thermal maxima showed a beneficial response to higher amplitude fluctuations. For adult acclimation involving shifts between...... fluctuating and constant regimes, cold tolerance was shown to be dictated by developmental temperature conditions irrespective of the adult treatments, while the acquired heat tolerance was readily lost when flies developed at fluctuating temperature were shifted to a constant regime as adults. Interestingly......, we also found that effect of fluctuations at any life stage was gradually lost with prolonged adult maintenance suggesting a more prominent effect of fluctuations during developmental compared to adult acclimation in Drosophila melanogaster....

Electrical and optical response of a laser diode to transient ionizing radiation

International Nuclear Information System (INIS)

Baggio, J.; Brisset, C.; Sommer, J.L.; D'hose, C.; Lalande, P.; Leray, J.L.; Musseau, O.

1996-01-01

The authors have studied transient irradiation effects on the optical and electrical responses of a laser diode. The influence of dose rate, ranging from 10 9 to 10 12 rad(Si)/s, has been investigated through a complete experimental study. Dose rate vulnerability of the laser diode has been observed. Electrical and optical transient responses are determined by the dose rate, the diode structure, and its operating point

Electron temperature fluctuation in the HT-7 tokamak plasma observed by electron cyclotron emission imaging

International Nuclear Information System (INIS)

Xiao-Yuan, Xu; Jun, Wang; Yi, Yu; Yi-Zhi, Wen; Chang-Xuan, Yu; Wan-Dong, Liu; Bao-Nian, Wan; Xiang, Gao; Luhmann, N. C.; Domier, C. W.; Wang, Jian; Xia, Z. G.; Shen, Zuowei

2009-01-01

The fluctuation of the electron temperature has been measured by using the electron cyclotron emission imaging in the Hefei Tokamak-7 (HT-7) plasma. The electron temperature fluctuation with a broadband spectrum shows that it propagates in the electron diamagnetic drift direction, and the mean poloidal wave-number k-bar θ is calculated to be about 1.58 cm −1 , or k-bar θρ s thickapprox 0.34. It indicates that the fluctuation should come from the electron drift wave turbulence. The linear global scaling of the electron temperature fluctuation with the gradient of electron temperature is consistent with the mixing length scale qualitatively. Evolution of spectrum of the fluctuation during the sawtooth oscillation phases is investigated, and the fluctuation is found to increase with the gradient of electron temperature increasing during most phases of the sawtooth oscillation. The results indicate that the electron temperature gradient is probably the driver of the fluctuation enhancement. The steady heat flux driven by electron temperature fluctuation is estimated and compared with the results from power balance estimation. (fluids, plasmas and electric discharges)

Impacts of demand response and renewable generation in electricity power market

Science.gov (United States)

Zhao, Zhechong

This thesis presents the objective of the research which is to analyze the impacts of uncertain wind power and demand response on power systems operation and power market clearing. First, in order to effectively utilize available wind generation, it is usually given the highest priority by assigning zero or negative energy bidding prices when clearing the day-ahead electric power market. However, when congestion occurs, negative wind bidding prices would aggravate locational marginal prices (LMPs) to be negative in certain locations. A load shifting model is explored to alleviate possible congestions and enhance the utilization of wind generation, by shifting proper amount of load from peak hours to off peaks. The problem is to determine proper amount of load to be shifted, for enhancing the utilization of wind generation, alleviating transmission congestions, and making LMPs to be non-negative values. The second piece of work considered the price-based demand response (DR) program which is a mechanism for electricity consumers to dynamically manage their energy consumption in response to time-varying electricity prices. It encourages consumers to reduce their energy consumption when electricity prices are high, and thereby reduce the peak electricity demand and alleviate the pressure to power systems. However, it brings additional dynamics and new challenges on the real-time supply and demand balance. Specifically, price-sensitive DR load levels are constantly changing in response to dynamic real-time electricity prices, which will impact the economic dispatch (ED) schedule and in turn affect electricity market clearing prices. This thesis adopts two methods for examining the impacts of different DR price elasticity characteristics on the stability performance: a closed-loop iterative simulation method and a non-iterative method based on the contraction mapping theorem. This thesis also analyzes the financial stability of DR load consumers, by incorporating

The role of magnetic-field-aligned electric fields in auroral acceleration

International Nuclear Information System (INIS)

Block, L.P.; Faelthammar, C.G.

1990-01-01

Electric field measurements on the Swedish satellite Viking have confirmed and extended earlier observations on S3-3 and provided further evidence of the role of dc electric fields in auroral acceleration processes. On auroral magnetic field lines the electric field is strongly fluctuating both transverse and parallel to the magnetic field. The significance of these fluctuations for the auroral acceleration process is discussed. A definition of dc electric fields is given in terms of their effects on charged particles. Fluctuations below several hertz are experienced as dc by typical auroral electrons if the acceleration length is a few thousand kilometers. For ions the same is true below about 0.1 Hz. The magnetic-field-aligned (as well as the transverse) component of the electric field fluctuations has a maximum below 1 Hz, in a frequency range that appears as dc to the electrons but not to the ions. This allows it to cause a selective acceleration, which may be important in explaining some of the observed characteristics of auroral particle distributions. The electric field observations on Viking support the conclusion that magnetic-field-aligned potential drops play an important role in auroral acceleration, in good agreement with particle observations boht on Viking and on the DE satellites. They also show that a large part, or even all, of the accelerating potential drop may be accounted for by numerous weak (about a volt) electric double layers, in agreement with earlier observations on the S3-3 satellite and with an early theoretical suggestion by L. Block

Transverse eV Ion Heating by Random Electric Field Fluctuations in the Plasmasphere

Science.gov (United States)

Artemyev, A. V.; Mourenas, D.; Agapitov, O. V.; Blum, L.

2017-01-01

Charged particle acceleration in the Earth inner magnetosphere is believed to be mainly due to the local resonant wave-particle interaction or particle transport processes. However, the Van Allen Probes have recently provided interesting evidence of a relatively slow transverse heating of eV ions at distances about 2-3 Earth radii during quiet times. Waves that are able to resonantly interact with such very cold ions are generally rare in this region of space, called the plasmasphere. Thus, non-resonant wave-particle interactions are expected to play an important role in the observed ion heating. We demonstrate that stochastic heating by random transverse electric field fluctuations of whistler (and possibly electromagnetic ion cyclotron) waves could explain this weak and slow transverse heating of H+ and O+ ions in the inner magnetosphere. The essential element of the proposed model of ion heating is the presence of trains of random whistler (hiss) wave packets, with significant amplitude modulations produced by strong wave damping, rapid wave growth, or a superposition of wave packets of different frequencies, phases, and amplitudes. Such characteristics correspond to measured characteristics of hiss waves in this region. Using test particle simulations with typical wave and plasma parameters, we demonstrate that the corresponding stochastic transverse ion heating reaches 0.07-0.2 eV/h for protons and 0.007-0.015 eV/h for O+ ions. This global temperature increase of the Maxwellian ion population from an initial Ti approx. 0.3 eV could potentially explain the observations.

Stochastic approach and fluctuation theorem for charge transport in diodes

Science.gov (United States)

Gu, Jiayin; Gaspard, Pierre

2018-05-01

A stochastic approach for charge transport in diodes is developed in consistency with the laws of electricity, thermodynamics, and microreversibility. In this approach, the electron and hole densities are ruled by diffusion-reaction stochastic partial differential equations and the electric field generated by the charges is determined with the Poisson equation. These equations are discretized in space for the numerical simulations of the mean density profiles, the mean electric potential, and the current-voltage characteristics. Moreover, the full counting statistics of the carrier current and the measured total current including the contribution of the displacement current are investigated. On the basis of local detailed balance, the fluctuation theorem is shown to hold for both currents.

Multi-scale response of runoff to climate fluctuation in the headwater region of Kaidu River in Xinjiang of China

Science.gov (United States)

Bai, Ling; Chen, Zhongsheng; Xu, Jianhua; Li, Weihong

2016-08-01

Based on the hydrological and meteorological data in the headwater region of the Kaidu River during 1960-2009, the multi-scale characteristics of runoff variability were analyzed using the ensemble empirical mode decomposition method (EEMD), and the aim is to investigate the oscillation mode structure characteristics of runoff change and its response to climate fluctuation at different time scales. Results indicated that in the past 50 years, the overall runoff of Kaidu River in Xinjiang has showed a significant nonlinear upward trend, and its changes have obviously exhibited an inter-annual scale (quasi-3 and quasi-6-year) and inter-decadal scale (quasi-10 and quasi-25-year). Variance contribution rates of each component manifested that the inter-decadal change had been playing a more important role in the overall runoff change for Kaidu River, and the reconstructed inter-annual variation trend could describe the fluctuation state of the original runoff anomaly during the study period. The reconstructed inter-decadal variability effectively revealed that the runoff for Kaidu River changed over the years, namely the states of abundance and low water period appear alternately. In addition, we found that runoff has a positive correlation to precipitation and temperature at different time scales, but they are most significant and relevant at inter-decadal scale, indicating the inter-decadal scale is most suitable for investigating the responses of runoff dynamics to climate fluctuation. At the same time, the results also suggested that EEMD is an effective method to analyze the multi-scale characteristics of nonlinear and non-stationary signal.

Predicting the Response of Electricity Load to Climate Change

Energy Technology Data Exchange (ETDEWEB)

Sullivan, Patrick [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Colman, Jesse [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kalendra, Eric [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2015-07-28

Our purpose is to develop a methodology to quantify the impact of climate change on electric loads in the United States. We perform simple linear regression, assisted by geospatial smoothing, on paired temperature and load time-series to estimate the heating- and coolinginduced sensitivity to temperature across 300 transmission zones and 16 seasonal and diurnal time periods. The estimated load sensitivities can be coupled with climate scenarios to quantify the potential impact of climate change on load, with a primary application being long-term electricity scenarios. The method allows regional and seasonal differences in climate and load response to be reflected in the electricity scenarios. While the immediate product of this analysis was designed to mesh with the spatial and temporal resolution of a specific electricity model to enable climate change scenarios and analysis with that model, we also propose that the process could be applied for other models and purposes.

Ocean acidification alters the photosynthetic responses of a coccolithophorid to fluctuating ultraviolet and visible radiation.

Science.gov (United States)

Jin, Peng; Gao, Kunshan; Villafañe, Virginia E; Campbell, Douglas A; Helbling, E Walter

2013-08-01

Mixing of seawater subjects phytoplankton to fluctuations in photosynthetically active radiation (400-700 nm) and ultraviolet radiation (UVR; 280-400 nm). These irradiance fluctuations are now superimposed upon ocean acidification and thinning of the upper mixing layer through stratification, which alters mixing regimes. Therefore, we examined the photosynthetic carbon fixation and photochemical performance of a coccolithophore, Gephyrocapsa oceanica, grown under high, future (1,000 μatm) and low, current (390 μatm) CO₂ levels, under regimes of fluctuating irradiances with or without UVR. Under both CO₂ levels, fluctuating irradiances, as compared with constant irradiance, led to lower nonphotochemical quenching and less UVR-induced inhibition of carbon fixation and photosystem II electron transport. The cells grown under high CO₂ showed a lower photosynthetic carbon fixation rate but lower nonphotochemical quenching and less ultraviolet B (280-315 nm)-induced inhibition. Ultraviolet A (315-400 nm) led to less enhancement of the photosynthetic carbon fixation in the high-CO₂-grown cells under fluctuating irradiance. Our data suggest that ocean acidification and fast mixing or fluctuation of solar radiation will act synergistically to lower carbon fixation by G. oceanica, although ocean acidification may decrease ultraviolet B-related photochemical inhibition.

Historical costs of coal-fired electricity and implications for the future

International Nuclear Information System (INIS)

McNerney, James; Doyne Farmer, J.; Trancik, Jessika E.

2011-01-01

We study the cost of coal-fired electricity in the United States between 1882 and 2006 by decomposing it in terms of the price of coal, transportation cost, energy density, thermal efficiency, plant construction cost, interest rate, capacity factor, and operations and maintenance cost. The dominant determinants of cost have been the price of coal and plant construction cost. The price of coal appears to fluctuate more or less randomly while the construction cost follows long-term trends, decreasing from 1902 to 1970, increasing from 1970 to 1990, and leveling off since then. Our analysis emphasizes the importance of using long time series and comparing electricity generation technologies using decomposed total costs, rather than costs of single components like capital. By taking this approach we find that the history of coal-fired electricity suggests there is a fluctuating floor to its future costs, which is determined by coal prices. Even if construction costs resumed a decreasing trend, the cost of coal-based electricity would drop for a while but eventually be determined by the price of coal, which fluctuates while showing no long-term trend. - Research highlights: → 125-year history highlights the dominant determinants of coal-fired electricity costs. → Results suggest a fluctuating floor to future costs, determined by coal prices. → Analysis emphasizes importance of comparing technologies using decomposed total costs.

CRIT II electric, magnetic, and density measurements within an ionizing neutral stream

Science.gov (United States)

Swenson, C. M.; Kelley, M. C.; Primdahl, F.; Baker, K. D.

1990-01-01

Measurements from rocket-borne sensors inside a high-velocity neutral barium beam show a-factor-of-six increase in plasma density in a moving ionizing front. This region was colocated with intense fluctuating electric fields at frequencies well under the lower hybrid frequency for a barium plasma. Large quasi-dc electric and magnetic field fluctuations were also detected with a large component of the current and the electric field parallel to B(0). An Alfven wave with a finite electric field component parallel to the geomagnetic field was observed to propagate along B(0), where it was detected by an instrumented subpayload.

Reducing and measuring fluctuations in the MST RFP: Enhancement of energy confinement and measurement of the MHD dynamo

International Nuclear Information System (INIS)

Den Hartog, D.J.; Almagri, A.F.

1996-09-01

A three- to five-fold enhancement of the energy confinement time in a reversed-field pinch (RFP) has been achieved in the Madison Symmetric Torus (MST) by reducing the amplitude of tearing mode fluctuations responsible for anomalous transport in the core of the RFP. By applying a transient poloidal inductive electric field to flatten the current density profile, the fluctuation amplitude b/B decreases from 1.5% to 0.8%, the electron temperature T e0 increases from 250 eV to 370 eV, the ohmic input power decreases from 4.5 MW to approximately 1.5 MW, the poloidal beta β 0 increases from 6% to 9%, and the energy confinement time τ E increases from 1 ms to ∼5 ms in I φ = 340 kA plasmas with density n = 1 x 10 19 m -3 . Current profile control methods are being developed for the RFP in a program to eliminate transport associated with these current-gradient-driven fluctuations. In addition to controlling the amplitude of the tearing modes, we are vigorously pursuing an understanding of the physics of these fluctuations. In particular, plasma flow, both equilibrium and fluctuating, plays a critical role in a diversity of physical phenomena in MST. The key results: 1) Edge probe measurements show that the MHD dynamo is active in low collisionality plasmas, while at high collisionality a new mechanism, the 'electron diamagnetic dynamo,' is observed. 2) Core spectroscopic measurements show that the toroidal velocity fluctuations of the plasma are coherent with the large-scale magnetic tearing modes; the scalar product of these two fluctuating quantities is similar to that expected for the MHD dynamo electromotive force. 3) Toroidal plasma flow in MST exhibits large radial shear and can be actively controlled, including unlocking locked discharges, by modifying E r with a robust biased probe. 24 refs

Local Polar Fluctuations in Lead Halide Perovskite Crystals

Science.gov (United States)

Yaffe, Omer; Guo, Yinsheng; Tan, Liang Z.; Egger, David A.; Hull, Trevor; Stoumpos, Constantinos C.; Zheng, Fan; Heinz, Tony F.; Kronik, Leeor; Kanatzidis, Mercouri G.; Owen, Jonathan S.; Rappe, Andrew M.; Pimenta, Marcos A.; Brus, Louis E.

2017-03-01

Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the organic molecular cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles molecular dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH3 NH3 PbBr3 ) and all-inorganic (CsPbBr3 ) lead-halide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar organic cation. MD simulations indicate that head-to-head Cs motion coupled to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr3 .

Local Polar Fluctuations in Lead Halide Perovskite Crystals

Energy Technology Data Exchange (ETDEWEB)

Yaffe, Omer; Guo, Yinsheng; Tan, Liang Z.; Egger, David A.; Hull, Trevor; Stoumpos, Constantinos C.; Zheng, Fan; Heinz, Tony F.; Kronik, Leeor; Kanatzidis, Mercouri G.; Owen, Jonathan S.; Rappe, Andrew M.; Pimenta, Marcos A.; Brus, Louis E.

2017-03-01

Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the organic molecular cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles molecular dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH3NH3PbBr3) and all-inorganic (CsPbBr3) leadhalide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar organic cation. MD simulations indicate that head-tohead Cs motion coupled to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr3.

Study on Earthquake Response of High Voltage Electrical Equipment Coupling System with Flexible Busbar

Science.gov (United States)

Liu, Chuncheng; Qu, Da; Wang, Chongyang; Lv, Chunlei; Li, Guoqiang

2017-12-01

With the rapid development of technology and society, all walks of life in China are becoming more and more dependent on power systems. When earthquake occurs, the electrical equipment of substation is prone to damage because of its own structural features, top-heavy, and brittleness of main body. At the same time, due to the complex coupling of the soft electrical connection of substation electrical equipment, the negative impact can not be estimated. In this paper, the finite element model of the coupling system of the single unit of high voltage electrical equipment with the connecting soft bus is established and the seismic response is analysed. The results showed that there is a significant difference between the simple analysis for the seismic response of electrical equipment monomer and the analytical results of electrical equipment systems, and the impact on different electrical equipment is different. It lays a foundation for the future development of seismic performance analysis of extra high voltage electrical equipment.

Electronic and magnetic phase separation in EuB6. Fluctuation spectroscopy and nonlinear transport

International Nuclear Information System (INIS)

Amyan, Adham

2013-01-01

The main topics of this thesis are electrical, stationary, and time-resolved transport measurements on EuB 6 as well as the further development of measuring methods and analysis procedures of the fluctuation spectroscopy. The first part of this thesis was dedicated to the further development of the already known measuring methods under application of a fast data-acquisition card. The second part deals with the electrical transport properties of EuB 6 and the understanding of the coupling between charge and magnetic degrees of freedom. By means of resistance and nonlinear-transport measurements as well as fluctuation spectroscopy hypotheses of other scientists were systematically verified as well as new knowledge obtained. The magnetoresistance was studied as function of the temperature in small external magnetic fields between 1 mT and 700 mT. Measurements of the third harmonic resistance as function of the temperature show maxima at T MI and T C . Electrical-resistance fluctuations were measured without external magnetic field between 5 and 100 K as well in presence of a magnetic field between 18 K and 32 K. At constant temperature measurements of the spectral power density in external magnetic fields were performed in the temperature range from 18 K to 32 K. Highly resolving measurements of the thermal expansion coefficient showed a very strong coupling of the magnetic (polaronic) degrees of freedom to the crystal lattice.

Hydraulic Tomography for Estimating the Diffusivity of Heterogeneous Aquifers Based on Groundwater Response to Tidal Fluctuation in an Artificial Island in Taiwan

Directory of Open Access Journals (Sweden)

Jet-Chau Wen

2018-01-01

Full Text Available This study investigated the hydraulic properties of the heterogeneous aquifers of an artificial island (Yunlin Offshore Industrial Park in Taiwan. The research was based on the groundwater level response affected by tidal fluctuation using the hydraulic tomography (HT to analyze the hydraulic diffusivity (α. Specifically, the power spectrum ratio of groundwater and tidal fluctuations derived from the Gelhar solution was used to estimate α in homogeneous aquifers; this, however, could not be applied in the artificial island. Next, the spatial distribution of the groundwater level response affected by tidal fluctuation was analyzed and found to be irregular, proving the existence of hydrogeological heterogeneity in the artificial island. Furthermore, the results of the estimated α using the HT showed low error and high correlation, 0.41 m2/hr and 0.83, respectively, between the optimal estimated heterogeneous and reference α fields in the synthetic aquifer. Last, the HT was used in the real tested scenario. By comparing the predicted groundwater levels of the optimal estimated heterogeneous α field and the observed groundwater levels of the real aquifer, it was found that the correlation was higher than 0.99. Therefore, the HT can be used to obtain the optimal estimated heterogeneous α field in the artificial island.

Nonadiabatic electron response in the Hasegawa-Wakatani equations

International Nuclear Information System (INIS)

Stoltzfus-Dueck, T.; Scott, B. D.; Krommes, J. A.

2013-01-01

Tokamak edge turbulence is strongly influenced by parallel electron physics, which relaxes density and potential fluctuations towards electron adiabatic response. Beginning with the paradigmatic Hasegawa-Wakatani equations (HWEs) for resistive tokamak edge turbulence, a unique decomposition of the electric potential (φ) into adiabatic (a) and nonadiabatic (b) portions is derived, based on the requirement that a neither drive nor respond to the parallel current j ∥ . The form of the decomposition clarifies that, at perpendicular scales large relative to the sound radius, the electron adiabatic response controls the nonzonal φ, not the fluctuating density n. Simple energy balance arguments allow one to rigorously bound the ratio of rms nonzonal nonadiabatic fluctuations (b(tilde sign)) relative to adiabatic ones (ã). The role of the vorticity nonlinearity in transferring energy between adiabatic and nonadiabatic fluctuations aids intuitive understanding of self-sustained turbulence in the HWEs. When the normalized parallel resistivity is weak, b(tilde sign) becomes effectively slaved, allowing the reduction to an approximate one-field model that remains valid for strong turbulence. In addition to guiding physical intuition, the one-field reduction should greatly ease further analytical manipulations. Direct numerical simulation of the 2D HWEs confirms the convergence of the asymptotic formula for b(tilde sign)

Nanosecond electric pulses trigger actin responses in plant cells

International Nuclear Information System (INIS)

Berghoefer, Thomas; Eing, Christian; Flickinger, Bianca; Hohenberger, Petra; Wegner, Lars H.; Frey, Wolfgang; Nick, Peter

2009-01-01

We have analyzed the cellular effects of nanosecond pulsed electrical fields on plant cells using fluorescently tagged marker lines in the tobacco cell line BY-2 and confocal laser scanning microscopy. We observe a disintegration of the cytoskeleton in the cell cortex, followed by contraction of actin filaments towards the nucleus, and disintegration of the nuclear envelope. These responses are accompanied by irreversible permeabilization of the plasma membrane manifest as uptake of Trypan Blue. By pretreatment with the actin-stabilizing drug phalloidin, the detachment of transvacuolar actin from the cell periphery can be suppressed, and this treatment can also suppress the irreversible perforation of the plasma membrane. We discuss these findings in terms of a model, where nanosecond pulsed electric fields trigger actin responses that are key events in the plant-specific form of programmed cell death.

Estimation of the local response to a forcing in a high dimensional system using the fluctuation-dissipation theorem

Directory of Open Access Journals (Sweden)

F. C. Cooper

2013-04-01

Full Text Available The fluctuation-dissipation theorem (FDT has been proposed as a method of calculating the response of the earth's atmosphere to a forcing. For this problem the high dimensionality of the relevant data sets makes truncation necessary. Here we propose a method of truncation based upon the assumption that the response to a localised forcing is spatially localised, as an alternative to the standard method of choosing a number of the leading empirical orthogonal functions. For systems where this assumption holds, the response to any sufficiently small non-localised forcing may be estimated using a set of truncations that are chosen algorithmically. We test our algorithm using 36 and 72 variable versions of a stochastic Lorenz 95 system of ordinary differential equations. We find that, for long integrations, the bias in the response estimated by the FDT is reduced from ~75% of the true response to ~30%.

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

Directory of Open Access Journals (Sweden)

H. Matsui

2012-03-01

Full Text Available In this event study, small-scale fluctuations in plasmaspheric plumes with time scales of ~10 s to minutes in the spacecraft frame are examined. In one event, plasmaspheric plumes are observed by Cluster, while IMAGE measured density enhancement at a similar location. Fluctuations in density exist in plumes as detected by Cluster and are accompanied by fluctuations in magnetic fields and electric fields. Magnetic fluctuations are transverse and along the direction of the plumes. The E/B ratio is smaller than the Alfvén velocity. Another similar event is briefly presented. We then consider physical properties of the fluctuations. Alfvén mode modulated by the feedback instability is one possibility, although non-local generation is likely. It is hard to show that the fluctuations represent a fast mode. Interchange motion is possible due to the consistency between measurements and expectations. The energy source could be a pressure or density gradient in plasmaspheric plumes. When more events are accumulated so that statistical analysis becomes feasible, this type of study will be useful to understand the time evolution of plumes.

Comparison of laser diode response to pulsed electrical and radiative excitations

International Nuclear Information System (INIS)

Baggio, J.; Rainsant, J.M.; D'hose, C.; Lalande, P.; Musseau, O.; Leray, J.L.

1996-01-01

The authors have studied the electrical and optical response of two laser diodes under transient irradiation. Both diodes exhibit a positive photocurrent, which adds to the bias current, and a decrease of the optical power until extinction when dose rate is increased. Direct carrier generation in the laser cavity is a second order phenomena. The diode overall response is driven by both the substrate photocurrent and the transient conduction of current confinement regions, which decrease the net current density in the cavity and switches-off the laser emission. This behavior is in good agreement with pulsed electrical characterizations and 2D simulations

Cascading of Fluctuations in Interdependent Energy Infrastructures. Gas-Grid Coupling

Energy Technology Data Exchange (ETDEWEB)

Chertkov, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lebedev, Vladimir [Russian Academy of Sciences (RAS), Moscow (Russian Federation). L.D. Landau Inst. for Theoretical Physics; Backhaus, Scott N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-09-05

The revolution of hydraulic fracturing has dramatically increased the supply and lowered the cost of natural gas in the United States driving an expansion of natural gas-fired generation capacity in many electrical grids. Unrelated to the natural gas expansion, lower capital costs and renewable portfolio standards are driving an expansion of intermittent renewable generation capacity such as wind and photovoltaic generation. These two changes may potentially combine to create new threats to the reliability of these interdependent energy infrastructures. Natural gas-fired generators are often used to balance the fluctuating output of wind generation. However, the time-varying output of these generators results in time-varying natural gas burn rates that impact the pressure in interstate transmission pipelines. Fluctuating pressure impacts the reliability of natural gas deliveries to those same generators and the safety of pipeline operations. We adopt a partial differential equation model of natural gas pipelines and use this model to explore the effect of intermittent wind generation on the fluctuations of pressure in natural gas pipelines. The mean square pressure fluctuations are found to grow linearly in time with points of maximum deviation occurring at the locations of flow reversals.

Fast-Response electric drives of Mechanical Engineering objects

Science.gov (United States)

Doykina, L. A.; Bukhanov, S. S.; Gryzlov, A. A.

2018-03-01

The article gives a solution to the problem of increasing the speed in the electrical drives of machine-building enterprises due to the application of a structure with ISC control. In this case, it is possible to get rid of the speed sensors. It is noted that in this case no circulating pulsations are applied to the input of the control system, caused by a non-identical interface between the sensor and the shaft of the operating mechanism. For detailed modeling, a mathematical model of an electric drive with distributed parameters was proposed. The calculation of such system was carried out by the finite element method. Taking into account the distributed characteristic of the system parameters allowed one to take into account the discrete nature of the electric machine’s work. The simulation results showed that the response time in the control circuit is estimated at a time constant of 0.0015, which is about twice as fast as in traditional vector control schemes.

Charge-Induced Fluctuation Forces in Graphitic Nanostructures

Directory of Open Access Journals (Sweden)

D. Drosdoff

2016-01-01

Full Text Available Charge fluctuations in nanocircuits with capacitor components are shown to give rise to a novel type of long-ranged interaction, which coexist with the regular Casimir–van der Waals force. The developed theory distinguishes between thermal and quantum mechanical effects, and it is applied to capacitors involving graphene nanostructures. The charge fluctuations mechanism is captured via the capacitance of the system with geometrical and quantum mechanical components. The dependence on the distance separation, temperature, size, and response properties of the system shows that this type of force can have a comparable and even dominant effect to the Casimir interaction. Our results strongly indicate that fluctuation-induced interactions due to various thermodynamic quantities can have important thermal and quantum mechanical contributions at the microscale and the nanoscale.

Global financial crisis making a V-shaped fluctuation in NO2 pollution over the Yangtze River Delta

Science.gov (United States)

Du, Yin; Xie, Zhiqing

2017-04-01

The Yangtze River Delta (YRD), China's main cultural and economic center, has become one of the most seriously polluted areas in the world with respect to nitrogen oxides (NOx), owing to its rapid industrialization and urbanization, as well as substantial coal consumption. On the basis of nitrogen dioxide (NO2) density data from ozone monitoring instrument (OMI) and ground-based observations, the effects of industrial fluctuations due to the financial crisis on local NO2 pollution were quantitatively assessed. The results were as follows. (1) A distinct V-shaped fluctuation of major industrial products, thermal generating capacity, electricity consumption, and tropospheric NO2 densities was associated with the global financial crisis from May 2007 to December 2009, with the largest anomalies 1.5 times more than standard deviations at the height of the crisis period from November 2008 to February 2009. (2) Among all industrial sectors, thermal power plants were mainly responsible for fluctuations in local NO2 pollution during the crisis period. Thermal generating capacity had its greatest decrease of 12.10% at the height of the crisis compared with that during November 2007-February 2008, leading to local tropospheric NO2 density decreasing by 16.97%. As the crisis appeased, thermal generating capacity increased by 29.63% from November 2009 to February 2010, and tropospheric NO2 densities correspondingly increased by 30.07%. (3) Among all industrial sectors in the YRD, the thermal power sector has the greatest coal consumption of about 65.96%. A decline in thermal power of about 10% can induce a decrease of about 30% in NOx emissions and NO2 densities, meaning that a relative small fluctuation in industrial production can lead to a large decrease in tropospheric NO2 densities over industrially developed areas like the YRD region. Since electricity is mainly obtained from local coal-burning thermal plants without NOx-processing equipment, installing NOx

Effects of limited spatial resolution on fluctuation measurements (invited)

International Nuclear Information System (INIS)

Bravenec, R.V.; Wootton, A.J.

1995-01-01

The finite sample volumes of fluctuation diagnostics distort the measurements not only by averaging the gross fluctuation parameters over the sample volumes, but more importantly (except for collective scattering), by attenuating the shorter wavelength components. In this work, the response of various sample volume sizes and orientations to a model fluctuation power spectrum S(k,ω) are examined. The model spectrum is fashioned after observations by far-infrared scattering on TEXT. The sample-volume extent in the direction of propagation of the turbulence is shown to be the most critical---not only does it reduce the measured fluctuation amplitude and increase the correlation length (as does an extent perpendicular to the propagation direction), but it also reduces the measured mean frequency and increases the apparent average phase velocity of the fluctuations. The differing sizes, shapes, and orientations of the sample volumes among fluctuation diagnostics, as well as deliberate variations within a single diagnostic, provide information on the form of the underlying turbulence and can be exploited to refine the model

Global fluctuations of cerebral blood flow indicate a global brain network independent of systemic factors.

Science.gov (United States)

Zhao, Li; Alsop, David C; Detre, John A; Dai, Weiying

2017-01-01

Global synchronization across specialized brain networks is a common feature of network models and in-vivo electrical measurements. Although the imaging of specialized brain networks with blood oxygenation sensitive resting state functional magnetic resonance imaging (rsfMRI) has enabled detailed study of regional networks, the study of globally correlated fluctuations with rsfMRI is confounded by spurious contributions to the global signal from systemic physiologic factors and other noise sources. Here we use an alternative rsfMRI method, arterial spin labeled perfusion MRI, to characterize global correlations and their relationship to correlations and anti-correlations between regional networks. Global fluctuations that cannot be explained by systemic factors dominate the fluctuations in cerebral blood flow. Power spectra of these fluctuations are band limited to below 0.05 Hz, similar to prior measurements of regional network fluctuations in the brain. Removal of these global fluctuations prior to measurement of regional networks reduces all regional network fluctuation amplitudes to below the global fluctuation amplitude and changes the strength and sign of inter network correlations. Our findings support large amplitude, globally synchronized activity across networks that require a reassessment of regional network amplitude and correlation measures.

Non-equilibrium concentration fluctuations in binary liquids with realistic boundary conditions.

Science.gov (United States)

Ortiz de Zárate, J M; Kirkpatrick, T R; Sengers, J V

2015-09-01

Because of the spatially long-ranged nature of spontaneous fluctuations in thermal non-equilibrium systems, they are affected by boundary conditions for the fluctuating hydrodynamic variables. In this paper we consider a liquid mixture between two rigid and impervious plates with a stationary concentration gradient resulting from a temperature gradient through the Soret effect. For liquid mixtures with large Lewis and Schmidt numbers, we are able to obtain explicit analytical expressions for the intensity of the non-equilibrium concentration fluctuations as a function of the frequency ω and the wave number q of the fluctuations. In addition we elucidate the spatial dependence of the intensity of the non-equilibrium fluctuations responsible for a non-equilibrium Casimir effect.

Fluctuations of the charge on a dust grain in a plasma

International Nuclear Information System (INIS)

Cui, C.; Goree, J.

1994-01-01

A dust grain in a plasma acquires an electric charge by collecting electron and ion currents. These currents consist of discrete charges, causing the charge to fluctuate around an equilibrium value (Q). Electrons and ions are collected at random intervals and in a random sequence, with probabilities that depend on the grain's potential. The authors developed a model for these probabilities and implemented it in a numerical simulation of the collection of individual ions and electrons, yielding a time series Q(t) for the grain's charge. Electron emission from the grain is not included, although it could be added easily to the method. They obtained the power spectrum and the rms fluctuation level, as well as the distribution function of the charge. Most of the power in the spectrum lies at frequencies much lower than 1/τ, the inverse charging time. The rms fractional fluctuation level varies as 0.5 |left-angle N right-angle | -1/2 , where left-angle N right-angle = left-angle Q right-angle/e is the average number of electron charges on the grain. This inverse square-root scaling means that fluctuations are most important for small grains. They also show that very small grains can experience fluctuations to neutral and positive polarities, even in the absence of electron emission

Multiscale response of ionic systems to a spatially varying electric field

Directory of Open Access Journals (Sweden)

Jesper Schmidt Hansen

2017-05-01

Full Text Available In this paper the response of ionic systems subjected to a spatially varying electric field is studied. Following the Nernst-Planck equation, two forces driving the mass flux are present, namely, the concentration gradient and the electric potential gradient. The mass flux due to the concentration gradient is modelled through Fick's law, and a new constitutive relation for the mass flux due to the potential gradient is proposed. In the regime of low screening the response function due to the potential gradient is closely related to the ionic conductivity. In the large screening regime, on the other hand, the response function is governed by the charge-charge structure. Molecular dynamics simulations are conducted and the two wave vector dependent response functions are evaluated for models of a molten salt and an ionic liquid. In the low screening regime the response functions show same wave vector dependency, indicating that it is the same underlying physical processes that govern the response. In the screening regime the wave vector dependency is very different and, thus, the overall response is determined by different processes. This is in agreement with the observed failure of the Nernst-Einstein relation.

Core fluctuations and current profile dynamics in the MST reversed-field pinch

International Nuclear Information System (INIS)

Brower, D.L.; Ding, W.X.; Lei, J.

2003-01-01

First measurements of the current density profile, magnetic field fluctuations and electrostatic (e.s.) particle flux in the core of a high-temperature reversed-field pinch (RFP) are presented. We report three new results: (1) The current density peaks during the slow ramp phase of the sawtooth cycle and flattens promptly at the crash. Profile flattening can be linked to magnetic relaxation and the dynamo which is predicted to drive anti-parallel current in the core. Measured core magnetic fluctuations are observed to increases four-fold at the crash. Between sawtooth crashes, measurements indicate the particle flux driven by e.s. fluctuations is too small to account for the total radial particle flux. (2) Core magnetic fluctuations are observed to decrease at least twofold in plasmas where energy confinement time improves ten-fold. In this case, the radial particle flux is also reduced, suggesting core e.s. fluctuation-induced transport may play role in confinement. (3) The parallel current density increases in the outer region of the plasma during high confinement, as expected, due to the applied edge parallel electric field. However, the core current density also increases due to dynamo reduction and the emergence of runaway electrons. (author)

Physiological response of Crocosphaera watsonii to enhanced and fluctuating carbon dioxide conditions.

Directory of Open Access Journals (Sweden)

Mary R Gradoville

Full Text Available We investigated the effects of elevated pCO2 on cultures of the unicellular N2-fixing cyanobacterium Crocosphaera watsonii WH8501. Using CO2-enriched air, cultures grown in batch mode under high light intensity were exposed to initial conditions approximating current atmospheric CO2 concentrations (∼ 400 ppm as well as CO2 levels corresponding to low- and high-end predictions for the year 2100 (∼ 750 and 1000 ppm. Following acclimation to CO2 levels, the concentrations of particulate carbon (PC, particulate nitrogen (PN, and cells were measured over the diurnal cycle for a six-day period spanning exponential and early stationary growth phases. High rates of photosynthesis and respiration resulted in biologically induced pCO2 fluctuations in all treatments. Despite this observed pCO2 variability, and consistent with previous experiments conducted under stable pCO2 conditions, we observed that elevated mean pCO2 enhanced rates of PC production, PN production, and growth. During exponential growth phase, rates of PC and PN production increased by ∼ 1.2- and ∼ 1.5-fold in the mid- and high-CO2 treatments, respectively, when compared to the low-CO2 treatment. Elevated pCO2 also enhanced PC and PN production rates during early stationary growth phase. In all treatments, PC and PN cellular content displayed a strong diurnal rhythm, with particulate C:N molar ratios reaching a high of 22:1 in the light and a low of 5.5:1 in the dark. The pCO2 enhancement of metabolic rates persisted despite pCO2 variability, suggesting a consistent positive response of Crocosphaera to elevated and fluctuating pCO2 conditions.

Impact Responses and Parameters Sensitivity Analysis of Electric Wheelchairs

Directory of Open Access Journals (Sweden)

Song Wang

2018-06-01

Full Text Available The shock and vibration of electric wheelchairs undergoing road irregularities is inevitable. The road excitation causes the uneven magnetic gap of the motor, and the harmful vibration decreases the recovery rate of rehabilitation patients. To effectively suppress the shock and vibration, this paper introduces the DA (dynamic absorber to the electric wheelchair. Firstly, a vibration model of the human-wheelchair system with the DA was created. The models of the road excitation for wheelchairs going up a step and going down a step were proposed, respectively. To reasonably evaluate the impact level of the human-wheelchair system undergoing the step–road transition, evaluation indexes were given. Moreover, the created vibration model and the road–step model were validated via tests. Then, to reveal the vibration suppression performance of the DA, the impact responses and the amplitude frequency characteristics were numerically simulated and compared. Finally, a sensitivity analysis of the impact responses to the tire static radius r and the characteristic parameters was carried out. The results show that the DA can effectively suppress the shock and vibration of the human-wheelchair system. Moreover, for the electric wheelchair going up a step and going down a step, there are some differences in the vibration behaviors.

Quantum critical scaling and fluctuations in Kondo lattice materials

Science.gov (United States)

Yang, Yi-feng; Pines, David; Lonzarich, Gilbert

2017-01-01

We propose a phenomenological framework for three classes of Kondo lattice materials that incorporates the interplay between the fluctuations associated with the antiferromagnetic quantum critical point and those produced by the hybridization quantum critical point that marks the end of local moment behavior. We show that these fluctuations give rise to two distinct regions of quantum critical scaling: Hybridization fluctuations are responsible for the logarithmic scaling in the density of states of the heavy electron Kondo liquid that emerges below the coherence temperature T∗, whereas the unconventional power law scaling in the resistivity that emerges at lower temperatures below TQC may reflect the combined effects of hybridization and antiferromagnetic quantum critical fluctuations. Our framework is supported by experimental measurements on CeCoIn5, CeRhIn5, and other heavy electron materials. PMID:28559308

Statistical fluctuations of the number of neutrons in a pile

International Nuclear Information System (INIS)

Raievski, V.

1958-01-01

The theory of the statistical fluctuations in a pile is extended to the space dependent case, and gives the fluctuations of the number of neutrons in a cell of the core or reflector of the pile. This number changes through elementary processes occurring at random, which are, capture, source, fission and scattering. Of all these processes, fission is the only one which changes more than one neutron at a time and so is responsible of the deviation of the fluctuations from a Poisson law. The importance of this deviation depends on the dimensions of the cell compared to the slowing down length. When the dimensions are small, the fluctuations close to a Poisson law. (author) [fr

Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

Science.gov (United States)

Wang, Mo-Zhu; Liu, Zheng-Yuan; Luo, Fang-Li; Lei, Guang-Chun; Li, Hong-Li

2016-01-01

Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii) and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm) of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm) were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions. PMID:26735689

Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

Science.gov (United States)

Wang, Mo-Zhu; Liu, Zheng-Yuan; Luo, Fang-Li; Lei, Guang-Chun; Li, Hong-Li

2016-01-01

Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii) and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm) of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm) were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions.

Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

Directory of Open Access Journals (Sweden)

Mo-Zhu Wang

Full Text Available Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions.

Management of surplus electricity-production from a fluctuating renewable-energy source

DEFF Research Database (Denmark)

Lund, Henrik; Münster, E.

2003-01-01

The paper discusses and analyses different national strategies for solving a surplus production problem in Denmark, caused by electricity production from turbines and CHP.......The paper discusses and analyses different national strategies for solving a surplus production problem in Denmark, caused by electricity production from turbines and CHP....

Electric field induced dewetting at polymer/polymer interfaces

NARCIS (Netherlands)

Lin, Z.Q.; Kerle, T.; Russell, T.P.; Schäffer, E.; Steiner, U

2002-01-01

External electric fields were used to amplify interfacial fluctuations in the air/polymer/polymer system where one polymer dewets the other. Two different hydrodynamic regimes were found as a function of electric field strength. If heterogeneous nucleation leads to the formation of holes before the

On the Minimization of Fluctuations in the Response Times of Autoregulatory Gene Networks

Science.gov (United States)

Murugan, Rajamanickam; Kreiman, Gabriel

2011-01-01

The temporal dynamics of the concentrations of several proteins are tightly regulated, particularly for critical nodes in biological networks such as transcription factors. An important mechanism to control transcription factor levels is through autoregulatory feedback loops where the protein can bind its own promoter. Here we use theoretical tools and computational simulations to further our understanding of transcription-factor autoregulatory loops. We show that the stochastic dynamics of feedback and mRNA synthesis can significantly influence the speed of response of autoregulatory genetic networks toward external stimuli. The fluctuations in the response-times associated with the accumulation of the transcription factor in the presence of negative or positive autoregulation can be minimized by confining the ratio of mRNA/protein lifetimes within 1:10. This predicted range of mRNA/protein lifetime agrees with ranges observed empirically in prokaryotes and eukaryotes. The theory can quantitatively and systematically account for the influence of regulatory element binding and unbinding dynamics on the transcription-factor concentration rise-times. The simulation results are robust against changes in several system parameters of the gene expression machinery. PMID:21943410

Observations of Pc5 micropulsation-related electric field oscillations in equatorial ionosphere

Science.gov (United States)

Reddy, C. A.; Ravindran, Sudha; Viswanathan, K. S.; Murthy, B. V. Krishna; Rao, D. R. K.; Araki, T.

1994-01-01

A 54.95-MHz coherent backscatter radar, an ionosonde and the magnetometer located at Trivandrum in India (8.5 deg N, 77 deg E, 0.5 deg N dip angle) recorded large-amplitude ionospheric fluctuations and magnetic field fluctuations associated with a Pc5 micropulsation event, which occurred during an intense magnetic storm on 24 March 1991 (A(sub p) = 161). Simultaneous 100-n T-level fluctuations are also observed in the H-component at Brorfelde, Denmark (55.6 deg N gm) and at Narsarsuaq, Greenland (70.6 deg N gm). Our study of the above observations shows that the E-W electric field fluctuations in the E- and F-regions and the magnetic field fluctuations at Thumba are dominated by a near-sinusoidal oscillation of 10 min during 1730-1900 IST (1200-1330 UT), the amplitude of the electric field oscillation in the equatorial electrojet (EEJ) is 0.1-0.25 mV/m and it increases with height, while it is about 1.0 mV/m in the F-region, the ground-level H-component oscillation can be accounted for by the ionospheric current oscillation generated by the observed electric field oscillation in the EEJ and the H-component oscillations at Trivandrum and Brofelde are in phase with each other. The observations are interpreted in terms of a compressional cavity mode resonance in the inner magnetosphere and the assoicated ionospheric electric field penetrating from high latitudes to the magnetic equator.

Are topological charge fluctuations in QCD instanton dominated?

International Nuclear Information System (INIS)

Edwards, Robert G.; Heller, Urs M.

2002-01-01

We consider a recent proposal by Horvath et al. to address the question of whether topological charge fluctuations in QCD are instanton dominated via the response of fermions using lattice fermions with exact chiral symmetry, the overlap fermions. Considering several volumes and lattice spacings, we find strong evidence for chirality of a finite density of low-lying eigenvectors of the overlap-Dirac operator in the regions where these modes are peaked. This result suggests instanton dominance of topological charge fluctuations in quenched QCD

Are Topological Charge Fluctuations in QCD Instanton Dominated?

International Nuclear Information System (INIS)

Edwards, Robert G.; Heller, Urs M.

2001-01-01

We consider a recent proposal by Horvath et al. to address the question whether topological charge fluctuations in QCD are instanton dominated via the response of fermions using lattice fermions with exact chiral symmetry, the overlap fermions. Considering several volumes and lattice spacings we find strong evidence for chirality of a finite density of low-lying eigenvectors of the overlap-Dirac operator in the regions where these modes are peaked. This result suggests instanton dominance of topological charge fluctuations in quenched QCD

The origin of fluctuations and cross-field transport in idealized magnetic confinement systems

International Nuclear Information System (INIS)

Riviere, A.C.; Ashby, D.E.T.F.; Cordey, J.G.; Edlington, T.; Rusbridge, M.G.

1981-01-01

The study of plasma fluctuations and confinement in idealized systems such as octupoles and levitrons has contributed to the understanding of cross-field transport processes. The linear theory of plasma instabilities that cause fluctuations can predict growth rates and wavelengths around lines of force. However, the theoretical prediction of cross-field transport coefficient is restricted to quasilinear estimates which usually far exceed the measured values. A general view of the results from octupole and levitron experiments shows that under collisional conditions the diffusion coefficient scales in the same way as classical collisional diffusion. Agreement is closely approached in many cases, sometimes even in the presence of fluctuations. Under collisionless conditions, Bohm diffusion scaling is found in the few cases where the scaling law has been determined. There is also experimental and theoretical evidence that long-wavelength low-frequency electric fields (convection cells) can be generated nonlinearly from high-frequency fluctuations and can contribute to cross-field transport. (author)

Response strategies for electric utilities to an uncertain climate

International Nuclear Information System (INIS)

Delcambre, J.; Wilson, O.

1995-01-01

The precautionary principle is being applied by legislators in formulating policy responses to the predictions of an enhanced greenhouse effect. Global commitments have been made under the Framework Convention on Climate Change to take measures aimed at stabilizing atmospheric concentrations of greenhouse gases. Electricity production from fossil fuels is a significant global source of carbon dioxide and a focus for emission reduction efforts. The decisions of policy-makers will impact on the electricity sector. However, the size and structure of this sector imply that substantial impositions cannot be placed on it in the short term without severe economic and social consequences. What is required of policy-makers is a pragmatic approach, since there are no simple or unique solutions. A rational attitude to energy use must be fostered which recognizes the special role of electricity in a modern economy

Novel gas sensor with dual response under CO(g) exposure: Optical and electrical stimuli

Science.gov (United States)

Rocha, L. S. R.; Cilense, M.; Ponce, M. A.; Aldao, C. M.; Oliveira, L. L.; Longo, E.; Simoes, A. Z.

2018-05-01

In this work, a lanthanum (La) doped ceria (CeO2) film, which depicted a dual gas sensing response (electric and optical) for CO(g) detection, was obtained by the microwave-assisted hydrothermal (HAM) synthesis and deposited by the screen-printing technique, in order to prevent deaths by intoxication with this life-threatening gas. An electric response under CO(g) exposure was obtained, along with an extremely fast optical response for a temperature of 380 °C, associated with Ce+4 reduction and vacancy generation. A direct optical gap was found to be around 2.31 eV from UV-Vis results, which corresponds to a transition from valence band to 4f states. Due to the anomalous electron configuration of cerium atoms with 4f electrons in its reduced state, they are likely to present an electric conduction based on the small polaron theory with a hopping mechanism responsible for its dual sensing response with a complete reversible behaviour.

Niche partitioning among frugivorous fishes in response to fluctuating resources in the Amazonian floodplain forest.

Science.gov (United States)

Correa, Sandra Bibiana; Winemiller, Kirk O

2014-01-01

In response to temporal changes in the quality and availability of food resources, consumers should adjust their foraging behavior in a manner that maximizes energy and nutrient intake and, when resources are limiting, minimizes dietary overlap with other consumers. Floodplains of the Amazon and its lowland tributaries are characterized by strong, yet predictable, hydrological seasonality, seasonal availability of fruits, seeds, and other food resources of terrestrial origin, and diverse assemblages of frugivorous fishes, including morphologically similar species of several characiform families. Here, we investigated how diets of frugivorous fishes in the Amazon change in response to fluctuations in food availability, and how this influences patterns of interspecific dietary overlap. We tested predictions from classical theories of foraging and resource competition by estimating changes in diet breadth and overlap across seasons. We monitored fruiting phenology to assess food availability, and surveyed local fish populations during three hydrological seasons in an oligotrophic river and an adjacent oxbow lake in the Colombian Amazon. We analyzed stomach contents and stable isotope data to evaluate temporal and interspecific relationships for dietary composition, breadth, and overlap. Diets of six species of characiform fishes representing three genera changed according to seasonal fluctuations in food availability, and patterns of diet breadth and interspecific overlap during the peak flood pulse were consistent with predictions of optimal foraging theory. During times of high fruit abundance, fishes consumed items to which their functional morphological traits seemed best adapted, potentially enhancing net energy and nutritional gains. As the annual flood pulse subsided and availability of forest food resources in aquatic habitats changed, there was not a consistent pattern of diet breadth expansion or compression. Nonetheless, shifts in both diet composition and

Magnetic fluctuations associated with density fluctuations in the tokamak edge

International Nuclear Information System (INIS)

Kim, Y.J.; Gentle, K.W.; Ritz, C.P.; Rhodes, T.L.; Bengtson, R.D.

1989-01-01

Electrostatic density and potential fluctuations occurring with high amplitude near the edge of a tokamak are correlated with components of the fluctuating magnetic field measured outside the limiter radius. It has been established that this turbulence is associated with fluctuations in current as well as density and potential. The correlation extends for substantial toroidal distances, but only if the probes are displaced approximately along field lines, consistent with the short coherence lengths poloidally but long coherence lengths parallel to the field which are characteristic for this turbulence. Furthermore, the correlation can be found only with density fluctuations measured inside the limiter radius; density fluctuations behind the limiter have no detectable magnetic concomitant for the toroidally spaced probes used here. (author). Letter-to-the-editor. 12 refs, 3 figs

Effects of environmental temperature fluctuations on the parameters of a thermoelectric battery

International Nuclear Information System (INIS)

Kozlov, Yu.F.; Oganov, E.P.

1980-01-01

A numerical analysis is presented for the effects of lags on the output parameters of a radioisotope thermoelectric battery under conditions of diurnal temperature variation in the environment. Allowance for the inertial effects causes a phase shift and change in amplitude of the variations in the thermal and electrical parameters. The amplitude of the temperature fluctuations in the hot junctions is substantially reduced, while the output electrical power increases. The data provide a more rigorous basis for choosing the parameters of radioisotope batteries during design. 9 refs

Quantum electric-dipole liquid on a triangular lattice.

Science.gov (United States)

Shen, Shi-Peng; Wu, Jia-Chuan; Song, Jun-Da; Sun, Xue-Feng; Yang, Yi-Feng; Chai, Yi-Sheng; Shang, Da-Shan; Wang, Shou-Guo; Scott, James F; Sun, Young

2016-02-04

Geometric frustration and quantum fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets. Geometric frustration and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogues of quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19 with geometric frustration represents a promising candidate for the proposed electric-dipole liquid. We present a series of experimental lines of evidence, including dielectric permittivity, heat capacity and thermal conductivity measured down to 66 mK, to reveal the existence of an unusual liquid-like quantum phase in BaFe12O19, characterized by itinerant low-energy excitations with a small gap. The possible quantum liquids of electric dipoles in frustrated dielectrics open up a fresh playground for fundamental physics.

Personalities influence spatial responses to environmental fluctuations in wild fish.

Science.gov (United States)

Villegas-Ríos, David; Réale, Denis; Freitas, Carla; Moland, Even; Olsen, Esben M

2018-06-11

1.Although growing evidence supports the idea that animal personality can explain plasticity in response to changes in the social environment, it remains to be tested whether it can explain spatial responses of individuals in the face of natural environmental fluctuations. This is a major challenge in ecology and evolution as spatial dynamics link individual- and population-level processes. 2.In this study we investigated the potential of individual personalities to predict differences in fish behaviour in the wild. Specifically, our goal was to answer if individual differences in plasticity of space use to sea surface temperature could be explained by differences in personality along the reactive-proactive axis. 3.To address this question we first conducted repeated standard laboratory assays (i.e. open-field test, novel object test and mirror-stimulation test) to assess the personality type of 76 wild-caught Atlantic cod (Gadus morhua). Next, we released the fish back into the sea and monitored their spatial behaviour over large temporal (16 months) and spatial (a whole fjord) scales, using high-resolution acoustic tracking. 4. We demonstrate that 1) cod personality traits are structured into a proactive-reactive syndrome (proactive fish being more bold, exploratory and aggressive), 2) mean depth use of individuals is mainly driven by sea temperature and 3) personality is a significant predictor of home range changes in the wild, where reactive, but not proactive, individuals reduced their home range as sea temperature increased. 5. These findings expand our understanding of the ecological consequences of animal personality and the mechanisms shaping spatial dynamics of animals in nature. This article is protected by copyright. All rights reserved. © 2018 The Authors Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

Near resonant absorption by atoms in intense, fluctuating fields: [Progress report

International Nuclear Information System (INIS)

1989-01-01

During the present grant period preparations for photon echo studies of the role of phase fluctuations of an optical driving field resonant with the 1 S 0 - 3 P 1 transition in 174 Yb are moving forward. This experimental study emphasizes the role of fluctuations as a decorrelating mechanism on a phased array of excited atoms. Improvements in laser stabilization and in the quality of the fluctuation spectrum have been carried out and the first spectroscopic measurements will be carried out during this grant year. In response to an important recent theoretical study we have also applied the phase fluctuation synthesizing capability to the study of the atomic sodium resonance fluorescence line profile, driven by a phase fluctuating laser. The measured fluctuations in the fluorescence, characterized in terms of the standard deviation of the fluorescence intensity, have an unexpected and strong dependence on detuning of the driving laser

Quantum fluctuations from thermal fluctuations in Jacobson formalism

Energy Technology Data Exchange (ETDEWEB)

Faizal, Mir [University of British Columbia-Okanagan, Irving K. Barber School of Arts and Sciences, Kelowna, BC (Canada); University of Lethbridge, Department of Physics and Astronomy, Lethbridge, AB (Canada); Ashour, Amani; Alcheikh, Mohammad [Damascus University, Mathematics Department, Faculty of Science, Damascus (Syrian Arab Republic); Alasfar, Lina [Universite Clermont Auvergne, Laboratoire de Physique Corpusculaire de Clermont-Ferrand, Aubiere (France); Alsaleh, Salwa; Mahroussah, Ahmed [King Saud University, Department of Physics and Astronomy, Riyadh (Saudi Arabia)

2017-09-15

In the Jacobson formalism general relativity is obtained from thermodynamics. This is done by using the Bekenstein-Hawking entropy-area relation. However, as a black hole gets smaller, its temperature will increase. This will cause the thermal fluctuations to also increase, and these will in turn correct the Bekenstein-Hawking entropy-area relation. Furthermore, with the reduction in the size of the black hole, quantum effects will also start to dominate. Just as the general relativity can be obtained from thermodynamics in the Jacobson formalism, we propose that the quantum fluctuations to the geometry can be obtained from thermal fluctuations. (orig.)

Probability distribution functions for intermittent scrape-off layer plasma fluctuations

Science.gov (United States)

Theodorsen, A.; Garcia, O. E.

2018-03-01

A stochastic model for intermittent fluctuations in the scrape-off layer of magnetically confined plasmas has been constructed based on a super-position of uncorrelated pulses arriving according to a Poisson process. In the most common applications of the model, the pulse amplitudes are assumed exponentially distributed, supported by conditional averaging of large-amplitude fluctuations in experimental measurement data. This basic assumption has two potential limitations. First, statistical analysis of measurement data using conditional averaging only reveals the tail of the amplitude distribution to be exponentially distributed. Second, exponentially distributed amplitudes leads to a positive definite signal which cannot capture fluctuations in for example electric potential and radial velocity. Assuming pulse amplitudes which are not positive definite often make finding a closed form for the probability density function (PDF) difficult, even if the characteristic function remains relatively simple. Thus estimating model parameters requires an approach based on the characteristic function, not the PDF. In this contribution, the effect of changing the amplitude distribution on the moments, PDF and characteristic function of the process is investigated and a parameter estimation method using the empirical characteristic function is presented and tested on synthetically generated data. This proves valuable for describing intermittent fluctuations of all plasma parameters in the boundary region of magnetized plasmas.

Study on Stochastic Optimal Electric Power Procurement Strategies with Uncertain Market Prices

Science.gov (United States)

Sakchai, Siripatanakulkhajorn; Saisho, Yuichi; Fujii, Yasumasa; Yamaji, Kenji

The player in deregulated electricity markets can be categorized into three groups of GENCO (Generator Companies), TRNASCO (Transmission Companies), DISCO (Distribution Companies). This research focuses on the role of Distribution Companies, which purchase electricity from market at randomly fluctuating prices, and provide it to their customers at given fixed prices. Therefore Distribution companies have to take the risk stemming from price fluctuation of electricity instead of the customers. This entails the necessity to develop a certain method to make an optimal strategy for electricity procurement. In such a circumstance, this research has the purpose for proposing the mathematical method based on stochastic dynamic programming to evaluate the value of a long-term bilateral contract of electricity trade, and also a project of combination of the bilateral contract and power generation with their own generators for procuring electric power in deregulated market.

Effective response of nonlinear cylindrical coated composites under external AC and DC electric field

International Nuclear Information System (INIS)

Yu-Yan, Shen; Xiao-Gang, Chen; Wei, Cui; Yan-Hua, Hao; Qian-Qian, Li

2009-01-01

This paper uses the perturbation method to study effective response of nonlinear cylindrical coated composites. Under the external AC and DC electric field E a (1 + sin ωt), the local potentials of composites at all harmonic frequencies are induced. An effective nonlinear response to composite is given for the cylindrical coated inclusions in the dilute limit. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Improving the principles of short-term electric load forecasting of the Irkutsk region

Directory of Open Access Journals (Sweden)

Kornilov Vladimir

2017-01-01

Full Text Available Forecasting of electric load (EL is an important task for both electric power entities and large consumers of electricity [1]. Large consumers are faced with the need to compose applications for the planned volume of EL, and the deviation of subsequent real consumption from previously announced leads to the appearance of penalties from the wholesale market. In turn, electricity producers are interested in forecasting the demand for electricity for prompt response to its fluctuations and for the purpose of optimal infrastructure development. The most difficult and urgent task is the hourly forecasting of EL, which is extremely important for the successful solution of problems of optimization of generating capacities, minimization of power losses, dispatching control, security assessment of power supply, etc. Ultimately, such forecasts allow optimizing the cash costs for electricity and fuel or water consumption during generation. This paper analyzes the experience of the branch of JSC "SO UPS" Irkutsk Regional Dispatch Office of the procedure for short-term forecasting of the EL of the Irkutsk region.

Study of the thermal and suprathermal electron density fluctuations of the plasma in the Focus experiment

International Nuclear Information System (INIS)

Jolas, A.

1981-10-01

An experiment on Thomson scattering of ruby laser light by the electrons of a plasma produced by an intense discharge between the electrodes of a coaxial gun in a gas at low pressure has been carried out. It is shown that the imploding plasma is made up of layers with different characteristics: a dense plasma layer where the density fluctuations are isotropic and have a thermal level, and a tenuous plasma layer where the fluctuations are anisotropic, and strongly suprathermal. The suprathermal fluctuations are attributed to microscopic instabilities generated by the electric current circulating in the transition zone where the magnetic field penetrates the plasma [fr

Fluctuations on the magnetic response of superconducting thin films of Nb and MgB2 - Percolation limit of vortex mobility

International Nuclear Information System (INIS)

Colauto, F.; Orgiani, P.; Xi, X.X.; Kang, W.N.; Choi, E.M.; Kim, H.J.; Lee, S.I.; Patino, E.; Blamire, M.G.; Ortiz, W.A.

2007-01-01

Application of a magnetic field of sufficient intensity orthogonal to superconducting thin films may produce dendritic patterns, where penetrated and Meissner regions coexist. The dendritic mode can be detected by AC-susceptibility measurements, since fingers penetrated by the magnetic field act as intergranular material. Measurements of the AC-susceptibility have the conventional shape for smaller values of magnitude and frequency of the excitation field. However, for frequencies in the vicinity of 1 kHz and AC-fields around 3 Oe and above, the curve deviates from its canonical behavior and fluctuates, the excursion becoming wider as the amplitude is increased. In this contribution we present results of a systematic study conducted to determine the threshold between smooth and fluctuating regimes of the magnetic response of the film, which is interpreted as the percolation limit of vortex mobility throughout the sample

Evidence for pressure-tuned quantum structural fluctuations in KCuF3

Science.gov (United States)

Yuan, S.; Kim, M.; Seeley, J.; Lal, S.; Abbamonte, P.; Cooper, S. L.

2012-02-01

Frustrated magnetic systems are currently of great interest because of the possibility that these materials exhibit novel ground states such as orbital and spin liquids. We provide evidence in the orbital-ordering material KCuF3 for pressure-tuned quantum melting of a static structural phase to a phase that dynamically fluctuates even near T ˜ 0K.[1] Pressure-dependent Raman scattering measurements show that applied pressure above P* ˜ 7kbar reverses a low temperature structural distortion in KCuF3, resulting in the development of a φ ˜ 0 fluctuational (quasielastic) response near T ˜ 0K. This pressure-induced fluctuational response is temperature independent and exhibits a characteristic fluctuation rate that is much larger than the temperature, γ >> KBT, consistent with quantum fluctuations of the CuF6 octahedra. We show that a previous developed model of pseudospin-phonon coupling qualitatively describes both the temperature- and pressure-dependent evolution of the Raman spectra of KCuF3. Work supported by the U.S. Department of Energy under Award No. DE-FG02-07ER46453 and by the National Science Foundation under Grant NSF DMR 08-56321. [4pt] [1] S. Yuan et al., arXiv:1107.1433 (2011).

Cascading of fluctuations in interdependent energy infrastructures: Gas-grid coupling

International Nuclear Information System (INIS)

Chertkov, Michael; Backhaus, Scott; Lebedev, Vladimir

2015-01-01

Highlights: • Fracturing and low cost of gas stimulated significant recent expansion of the natural gas networks. • Power system operators transition to gas as the main supply, also facing new reliability challenges. • Natural gas-fired generators vary burn-rates to balance fluctuating output of wind generation. • Impact of the gas-generator variations is seen in diffusive jitter of pressure within the gas network. • Fluctuating pressure impacts both reliability of natural gas deliveries and safety of pipeline operations. - Abstract: The revolution of hydraulic fracturing has dramatically increased the supply and lowered the cost of natural gas in the United States driving an expansion of natural gas-fired generation capacity in many electrical grids. Unrelated to the natural gas expansion, lower capital costs and renewable portfolio standards are driving an expansion of intermittent renewable generation capacity such as wind and photovoltaic generation. These two changes may potentially combine to create new threats to the reliability of these interdependent energy infrastructures. Natural gas-fired generators are often used to balance the fluctuating output of wind generation. However, the time-varying output of these generators results in time-varying natural gas burn rates that impact the pressure in interstate transmission pipelines. Fluctuating pressure impacts the reliability of natural gas deliveries to those same generators and the safety of pipeline operations. We adopt a partial differential equation model of natural gas pipelines and use this model to explore the effect of intermittent wind generation on the fluctuations of pressure in natural gas pipelines. The mean square pressure fluctuations are found to grow linearly in time with points of maximum deviation occurring at the locations of flow reversals.

Observations of Pc5 micropulsation-related electric field oscillations in the equatorial ionosphere

Directory of Open Access Journals (Sweden)

C. A. Reddy

1994-05-01

Full Text Available A 54.95-MHz coherent backscatter radar, an ionosonde and the magnetometer located at Trivandrum in India (8.5°N, 77°E, 0.5°N dip angle recorded large-amplitude ionospheric fluctuations and magnetic field fluctuations associated with a Pc5 micropulsation event, which occurred during an intense magnetic storm on 24 March 1991 (Ap=161. Simultaneous 100-nT-level fluctuations are also observed in the H-component at Brorfelde, Denmark (55.6°N gm and at Narsarsuaq, Greenland (70.6°N gm. Our study of the above observations shows that the E-W electric field fluctuations in the E- and F-regions and the magnetic field fluctuations at Thumba are dominated by a near-sinusoidal oscillation of 10 min during 1730-1900 IST (1200-1330 UT, the amplitude of the electric field oscillation in the equatorial electrojet (EEJ is 0.1-0.25 mV m-1 and it increases with height, while it is about 1.0 mV m-1 in the F-region, the ground-level H-component oscillation can be accounted for by the ionospheric current oscillation generated by the observed electric field oscillation in the EEJ and the H-component oscillations at Trivandrum and Brorfelde are in phase with each other. The observations are interpreted in terms of a compressional cavity mode resonance in the inner magnetosphere and the associated ionospheric electric field penetrating from high latitudes to the magnetic equator.

Constraints on Stable Equilibria with Fluctuation-Induced (Casimir) Forces

International Nuclear Information System (INIS)

Rahi, Sahand Jamal; Kardar, Mehran; Emig, Thorsten

2010-01-01

We examine whether fluctuation-induced forces can lead to stable levitation. First, we analyze a collection of classical objects at finite temperature that contain fixed and mobile charges and show that any arrangement in space is unstable to small perturbations in position. This extends Earnshaw's theorem for electrostatics by including thermal fluctuations of internal charges. Quantum fluctuations of the electromagnetic field are responsible for Casimir or van der Waals interactions. Neglecting permeabilities, we find that any equilibrium position of items subject to such forces is also unstable if the permittivities of all objects are higher or lower than that of the enveloping medium, the former being the generic case for ordinary materials in vacuum.

Constraints on stable equilibria with fluctuation-induced (Casimir) forces.

Science.gov (United States)

Rahi, Sahand Jamal; Kardar, Mehran; Emig, Thorsten

2010-08-13

We examine whether fluctuation-induced forces can lead to stable levitation. First, we analyze a collection of classical objects at finite temperature that contain fixed and mobile charges and show that any arrangement in space is unstable to small perturbations in position. This extends Earnshaw's theorem for electrostatics by including thermal fluctuations of internal charges. Quantum fluctuations of the electromagnetic field are responsible for Casimir or van der Waals interactions. Neglecting permeabilities, we find that any equilibrium position of items subject to such forces is also unstable if the permittivities of all objects are higher or lower than that of the enveloping medium, the former being the generic case for ordinary materials in vacuum.

Propagation of disturbances as voltage fluctuations in transmission networks

Directory of Open Access Journals (Sweden)

Albert Hermina

2016-08-01

Full Text Available Significant changes occurred in the power system in Romania in recent years by reducing the power used in the system, the number of classic power sources in operation as well as by implementing renewable energy sources, have determined short circuit power reduction (node rigidity in the points where disturbing users are connected, that in the absence of adequate measures, result in disturbances above acceptable levels. The paper analyzes two power systems areas in which are connected users that cause voltage fluctuation. Disturbances as voltage fluctuations resulting in these nodes may exceed the acceptable values and can spread in the transmission network affecting power quality over large system areas. The analysis conducted reveals the influence of short circuit power in nodes where these users are connected and highlights the fact that in some cases (e.g. lines out of operation for maintenance, shutdown of classic units in the area the disturbances in the transmission network sent to the users at lower voltages may have values above those allowed. Technical Code of existing power transmission network makes no reference to voltage fluctuations, as a rule, in the electricity transmission network was considered that this phenomenon should not exist.

Charge fluctuations in high-electron-mobility transistors: a review

International Nuclear Information System (INIS)

Green, F.

1993-01-01

The quasi-two-dimensional carrier population, free to move within a near-perfect crystalline matrix, is the key to remarkable improvements in signal gain, current density and quiet operation. Current-fluctuation effects are central to all of these properties. Some of these are easily understood within linear-response theory, but other fluctuation phenomena are less tractable. In particular, nonequilibrium noise poses significant theoretical challenges, both descriptive and predictive. This paper examines a few of the basic physical issues which motivate device-noise theory. The structure and operation of high-electron-mobility transistor are first reviewed. The recent nonlinear fluctuation theory of Stanton and Wilkins (1987) help to identify at least some of the complicated noise physics which can arise when carriers in GaAs-like conduction bands are subjected to high fields. Simple examples of fluctuation-dominated behaviour are discussed, with numerical illustrations. 20 refs., 9 figs

Comparing electricity, heat and biogas storages’ impacts on renewable energy integration

DEFF Research Database (Denmark)

Østergaard, Poul Alberg

2012-01-01

-inclusive 100% renewable energy scenario developed for the Danish city Aalborg based on wind power, bio-resources and low-temperature geothermal heat. The article investigates the system impact of different types of energy storage systems including district heating storage, biogas storage and electricity......Increasing penetration of fluctuating energy sources for electricity generation, heating, cooling and transportation increase the need for flexibility of the energy system to accommodate the fluctuations of these energy sources. Controlling production, controlling demand and utilising storage...... options are the three general categories of measures that may be applied for ensuring balance between production and demand, however with fluctuating energy sources, options are limited, and flexible demand has also demonstrated limited perspective. This article takes its point of departure in an all...

Ionospheric response to variable electric fields in small-scale auroral structures

Directory of Open Access Journals (Sweden)

B. S. Lanchester

1998-10-01

Full Text Available High time and space resolution optical and radar measurements have revealed the influence of electric fields on E-region electron density profiles in small-scale auroral structures. Large electric fields are present adjacent to auroral filaments produced by monoenergetic electron fluxes. The ionisation profiles measured within and beside the auroral filaments show the effects of plasma convection due to electric fields as well as the consequences of the response time to large and dynamic fluxes of energetic electrons. Without high-resolution optical measurements, the interpretation of the radar data is limited.Key words. Auroral ionosphere · Ionosphere-magnetosphere interactions · EISCAT

Ionospheric response to variable electric fields in small-scale auroral structures

Directory of Open Access Journals (Sweden)

B. S. Lanchester

Full Text Available High time and space resolution optical and radar measurements have revealed the influence of electric fields on E-region electron density profiles in small-scale auroral structures. Large electric fields are present adjacent to auroral filaments produced by monoenergetic electron fluxes. The ionisation profiles measured within and beside the auroral filaments show the effects of plasma convection due to electric fields as well as the consequences of the response time to large and dynamic fluxes of energetic electrons. Without high-resolution optical measurements, the interpretation of the radar data is limited.

Key words. Auroral ionosphere · Ionosphere-magnetosphere interactions · EISCAT

ANALYSIS OF GROSS REGIONAL PRODUCT FLUCTUATIONS AND ELECTRIC POWER CONSUMPTION IN 2005- 2014. RESERVES FOR DECREASING ELECTRIC POWER PRICES

Directory of Open Access Journals (Sweden)

Suslov N. I.

2016-09-01

Full Text Available In this work we considered the trajectories of change in indicators characterizing the status of economics and power industry: gross regional product, electric power consumption, industrial production, energy prices and costs of delivering electric power to consumers in Russian regions for the last 10 years. Low global commodity prices and sanctions led to a sharp decrease of equipment import, which resulted in an acute problem of import substitution. The level of tariffs of natural monopolies is of great importance for industrial development. The goal of this work was to analyze possibilities for reducing electric power prices by changing the institutional and economic conditions of management. We analyzed not only the official information from Rosstat, but also government regulations, figures given in the official government publication «The Rossiyskaya Gazeta» as well as articles and interviews on economic problems of the electric power industry over the recent years published in «The Kommersant» newspaper. High tariffs of network marketing companies for electric energy transmission, state regulation of heating prices, financing the construction of new capacities by charging the payment in power provision contracts, high price of electric power of nuclear power plants lead to an annual increase in electric power prices for end users. In this work we considered possible solutions to limit the growth of electric power prices.

Electrical impedance spectroscopy for measuring the impedance response of carbon-fiber-reinforced polymer composite laminates

KAUST Repository

Almuhammadi, Khaled

2017-02-16

Techniques that monitor the change in the electrical properties of materials are promising for both non-destructive testing and structural health monitoring of carbon-fiber-reinforced polymers (CFRPs). However, achieving reliable monitoring using these techniques requires an in-depth understanding of the impedance response of these materials when subjected to an alternating electrical excitation, information that is only partially available in the literature. In this work, we investigate the electrical impedance spectroscopy response at various frequencies of laminates chosen to be representative of classical layups employed in composite structures. We clarify the relationship between the frequency of the electrical current, the conductivity of the surface ply and the probing depth for different CFRP configurations for more efficient electrical signal-based inspections. We also investigate the effect of the amplitude of the input signal.

Investigation of low-frequency fluctuations in the edge plasma of ASDEX

Energy Technology Data Exchange (ETDEWEB)

Rudyj, A; Carlson, A; Giannone, L.; Niedermeyer, H [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany, F.R.); Bengtson, R D; Ritz, Ch P [Texas Univ., Austin, TX (USA); Kraemer, M [Bochum Univ. (Germany, F.R.); Tsois, N [NRS Demokritos, Attiki (Greece)

1989-01-01

Density fluctuations in the edge plasma of tokamaks in the frequency range up to a few 100 kHz have been reported for many years. The fluctuations are easily observed with Langmuir probes and are also visible in the H/sub {alpha}/ emission at locations with sufficient neutral gas density. High speed cine films taken on ASDEX show fluctuating stripes aligned approximately parallel to the magnetic field. It has been shown that these fluctuations, which are electrostatic, cause a major part if not all of the particle transport at the plasma edge. The mechanism driving these instabilities is however not yet clear. Langmuir probe measurements and optical observations were performed on ASDEX and a comparison was made with magnetic fluctuation measurements in order to further clarify the mechanism responsible for the edge turbulence. 5 refs., 3 figs.

Investigation of low-frequency fluctuations in the edge plasma of ASDEX

International Nuclear Information System (INIS)

Rudyj, A.; Carlson, A.; Giannone, L.; Niedermeyer, H.; Bengtson, R.D.; Ritz, Ch.P.; Kraemer, M.; Tsois, N.

1989-01-01

Density fluctuations in the edge plasma of tokamaks in the frequency range up to a few 100 kHz have been reported for many years. The fluctuations are easily observed with Langmuir probes and are also visible in the H α emission at locations with sufficient neutral gas density. High speed cine films taken on ASDEX show fluctuating stripes aligned approximately parallel to the magnetic field. It has been shown that these fluctuations, which are electrostatic, cause a major part if not all of the particle transport at the plasma edge. The mechanism driving these instabilities is however not yet clear. Langmuir probe measurements and optical observations were performed on ASDEX and a comparison was made with magnetic fluctuation measurements in order to further clarify the mechanism responsible for the edge turbulence. 5 refs., 3 figs

The role of electric field shear stabilization of turbulence in the H-mode to VH-mode transition in DIII-D

International Nuclear Information System (INIS)

Burrell, K.H.; Osborne, T.H.; Groebner, R.J.; Rettig, C.L.

1993-01-01

VH-mode plasma exhibit energy confinement times up to 2.4 times the DIII-D/JET H-mode scaling relation and up to 3.9 times the value given by ITER89-P L-mode scaling. If this confinement improvement can be exploited in reactor plasmas, smaller prototype reactors with significantly lower unit cost can be produced. Accordingly, understanding and optimizing the confinement improvement is of significant interest. One of the possible explanations for this bulk confinement improvement is stabilization of turbulence by shear in the radial electric field, similar to the present explanation for the confinement improvement at the extreme plasma edge at the L to H transition. Preliminary measurements have shown that the region of the plasma where the electric field gradient is steepest broadens when the plasma goes from H-mode to VH-mode. More recent measurements have confirmed this broadening and have shown that the change in the electric field gradient occurs prior to the change in the thermal transport. In addition, transport analysis shows that the electric field shear increases in the same region between magnetic flux coordinate p=0.6 and 0.9 where the local thermal transport decreases. Furthermore, far infra-red (FIR) scattering measurements have detected density fluctuations in the region around p=0.8 which could be responsible for enhanced transport and which disappear at the time that the electric shear increases. These fluctuations appear as bursts of density fluctuations in the 0.5 to 1.5 MHz range. The time between bursts increases as the electric field shear increases. Once these bursts disappear, the major change in confinement takes place in most discharges. When isolated bursts occur, the heat and angular momentum pulse connected with the burst are detectable on the plasma profile diagnostics. (author) 13 refs., 4 figs

Design of Fast Response Smart Electric Vehicle Charging Infrastructure

Energy Technology Data Exchange (ETDEWEB)

Chung, Ching-Yen; Chynoweth, Joshua; Qiu, Charlie; Chu, Chi-Cheng; Gadh, Rajit

2013-11-25

The response time of the smart electrical vehicle (EV) charging infrastructure is the key index of the system performance. The traffic between the smart EV charging station and the control center dominates the response time of the smart charging stations. To accelerate the response of the smart EV charging station, there is a need for a technology that collects the information locally and relays it to the control center periodically. To reduce the traffic between the smart EV charger and the control center, a Power Information Collector (PIC), capable of collecting all the meters power information in the charging station, is proposed and implemented in this paper. The response time is further reduced by pushing the power information to the control center. Thus, a fast response smart EV charging infrastructure is achieved to handle the shortage of energy in the local grid.

Resilience of electricity grids against transmission line overloads under wind power injection at different nodes.

Science.gov (United States)

Schiel, Christoph; Lind, Pedro G; Maass, Philipp

2017-09-14

A steadily increasing fraction of renewable energy sources for electricity production requires a better understanding of how stochastic power generation affects the stability of electricity grids. Here, we assess the resilience of an IEEE test grid against single transmission line overloads under wind power injection based on the dc power flow equations and a quasi-static grid response to wind fluctuations. Thereby we focus on the mutual influence of wind power generation at different nodes. We find that overload probabilities vary strongly between different pairs of nodes and become highly affected by spatial correlations of wind fluctuations. An unexpected behaviour is uncovered: for a large number of node pairs, increasing wind power injection at one node can increase the power threshold at the other node with respect to line overloads in the grid. We find that this seemingly paradoxical behaviour is related to the topological distance of the overloaded line from the shortest path connecting the wind nodes. In the considered test grid, it occurs for all node pairs, where the overloaded line belongs to the shortest path.

Energy-environment policy goals and instruments and electricity demand response. A framework for the analysis

International Nuclear Information System (INIS)

Rio, Pablo del; Hernandez, F.

2004-01-01

The environment and energy realms have traditionally been two major focus of attention of EU and Member State (MS) policy. This attention has intensified in recent years as a response to, both, internal and external events and strategies (i.e., the Kyoto Protocol). In this context, the EU and its MS have set ambitious goals in the environmental and energy contexts and are already implementing packages of policies and measures. Both policies interact. Although there might be conflicts between both, there are also mutually reinforcing effects with significant policy implications. Actually, as stated in the Amsterdam Treaty, environmental protection is one of the major goals of energy policy (together with 'security of supply' and 'competitive energy systems'). On the other hand, the energy sector is instrumental in the success of environmental policy. In this context, a wide array of measures are currently being implemented in the EU and its MS which have a more or less direct impact on the electricity market. Particularly, Demand Side Management (DSM) activities, promotion of electricity from renewable energy sources (RES-E) and measures aimed at the mitigation of Greenhouse Gas (GHG) emissions are arguably three major instruments which have the potential to contribute to energy and environmental goals. The effectiveness and impact of there measures depends to a large extent on the demand response in the electricity market. Some of there measures affect the electricity demand curve, while others do not have a direct impact on the demand curve but affect the quantity of electricity demand by displacing the electricity supply curve. In turn, the effectiveness of energy and environmental policies may be different when electricity demand response varies (i.e., different elasticity demand). This paper entails an initial effort to provide a theoretical framework for the analysis of the interactions between electricity demand response and the above mentioned energy

Linear Response of Field-Aligned Currents to the Interplanetary Electric Field

DEFF Research Database (Denmark)

Weimer, D. R.; R. Edwards, T.; Olsen, Nils

2017-01-01

Many studies that have shown that the ionospheric, polar cap electric potentials (PCEP) exhibit a “saturation” behavior in response to the level of the driving by the solar wind. As the magnitude of the interplanetary magnetic field (IMF) and electric field (IEF) increase, the PCEP response...... of the field-aligned currents (FAC) with the solar wind/magnetosphere/ionosphere system has a role. As the FAC are more difficult to measure, their behavior in response to the level of the IEF has not been investigated as thoroughly. In order to resolve the question of whether or not the FAC also exhibit...... saturation, we have processed the magnetic field measurements from the Ørsted, CHAMP, and Swarm missions, spanning more than a decade. As the amount of current in each region needs to be known, a new technique is used to separate and sum the current by region, widely known as R0, R1, and R2. These totals...

Non extensive statistical physics applied in fracture-induced electric signals during triaxial deformation of Carrara marble

Science.gov (United States)

Cartwright-Taylor, Alexis; Vallianatos, Filippos; Sammonds, Peter

2014-05-01

indices (q-values) for electric current fluctuations in the brittle and semi-brittle regimes (c. 1.5 and 1.8 respectively), implying an increase in interactions between microcracks in the semi-brittle regime. We interpret this non-Gaussian behaviour as a 'superstatistical' superposition of local Gaussian fluctuations that combine to produce a higher-order overall distribution; i.e. the measured electric current is driven to varying, temporary, local equilibria during deformation. This behaviour is analogous to the self-organising avalanche-like behaviour of fracture events, suggesting that the observed behaviour of measured electric current is a direct response to the microcracking events themselves and supporting the idea of a fracture-generated electrification mechanism in the crust. Our results have implications for the earthquake preparation process and the application of Tsallis statistical physics to the analysis of electric earthquake precursors. This research has been funded by the European Union (European Social Fund) and Greek national resources under the framework of the "THALES Program: SEISMO FEAR HELLARC" project of the "Education & Lifelong Learning" Operational Programme.

Rocket measurements within a polar cap arc: Plasma, particle, and electric circuit parameters

International Nuclear Information System (INIS)

Weber, E.J.; Ballenthin, J.O.; Basu, S.; Carlson, H.C.; Hardy, D.A.; Maynard, N.C.; Smiddy, M.; Kelley, M.C.; Fleischman, J.R.; Sheehan, R.E.; Pfaff, R.F.; Rodriguez, P.

1989-01-01

An instrumented rocket payload was launched into a polar cap F layer aurora to investigate the energetic particle, plasma, and electric circuit parameters of a Sun-aligned arc. On-board instruments measured energetic electron flux, ion composition and density fluctuations, electron density and temperature, electron density fluctuations, and ac and dc electric fields. Real-time all-sky imaging photometer measurements of the location and motion of the aurora, were used to determine the proper geophysical situation for launch. Comparison of the in situ measurements with remote optical measurements shows that the arc was produced by fluxes of low-energy (< 1 keV) electrons. Field-aligned potentials in the arc inferred from the electron spectra had a maximum value of approximately 300 V, and from the spectral shape a parent population of preaccelerated electrons characteristic of the boundary plasma sheet or magnetosheath was inferred. Electric field components along and across the arc show sunward flow within the arc and duskward drift of the arc consistent with the drift direction and speed determined from optical imaging. Thus this arc is drifting duskward under the influence of the convection electric field. Three possible explanations for this (field-aligned currents, chemistry, and transport) are considered. Finally, ionospheric irregularity and electric field fluctuations indicate two different generation mechanisms on the dawnside and duskside of the arc. On the duskside, parameters are suggestive of an interchange process, while on the dawnside, fluctuation parameters are consistent with a velocity shear instability

Studies of Fluctuation Processes in Nuclear Collisions

Energy Technology Data Exchange (ETDEWEB)

Ayik, Sakir [Tennessee Technological Univ., Cookeville, TN (United States). Dept. of Physics

2016-04-14

The standard one-body transport approaches have been extensively applied to investigate heavy-ion collision dynamics at low and intermediate energies. At low energies the approach is the mean-field description of the time-dependent Hartree-Fock (TDHF) theory. At intermediate energies the approach is extended by including a collision term, and its application has been carried out mostly in the semi-classical framework of the Boltzmann-Uhling-Uhlenbeck (BUU) model. The standard transport models provide a good understanding of the average properties of the collision dynamics in terms of the effective interactions in both low and intermediate energies. However, the standard models are inadequate for describing the fluctuation dynamics of collective motion at low energies and disassembling of the nuclear system into fragments at intermediate energies resulting from the growth of density fluctuations in the spinodal region. Our tasks have been to improve the standard transport approaches by incorporating fluctuation mechanisms into the description. There are mainly two different mechanisms for fluctuations: (i) Collisional fluctuations generated by binary nucleon collisions, which provide the dominant mechanism at intermediate energies, and (ii) One-body mechanism or mean-field fluctuations, which is the dominant mechanism at low energies. In the first part of our project, the PI extended the standard transport model at intermediate energies by incorporating collisional mechanism according to the “Generalized Langevin Description” of Mori formalism. The PI and his collaborators carried out a number of applications for describing dynamical mechanism of nuclear multi fragmentations, and nuclear collective response in the semi-classical framework of the approach, which is known as the Boltzmann-Langevin model. In the second part of the project, we considered dynamical description at low energies. Because of the effective Pauli blocking, the collisional dissipation and

What is demand response? Contributing to secure security-of-supply at the electricity markets

International Nuclear Information System (INIS)

Grenaa Jensen, Stine; Skytte, Klaus; Togeby, Mikael

2004-01-01

There is a common understanding that demand response can reduce the total costs of electricity reliability. There has especially been a growing interest in the electricity market where high spot prices in peak periods and blackouts have recently been seen. It is not easy from the existing literature to find a common definition of demands response. Often the term demand response is used broadly without looking at the time dimension. However, it does not make sense to talk about demand response without talking about when, for how long the energy is used or saved, and at which costs. This paper surveys these subjects and set up a systematic grouping of the different characteristics of demand response. It especially looks at the time dimension. (au)

Mercury exposure may influence fluctuating asymmetry in waterbirds.

Science.gov (United States)

Herring, Garth; Eagles-Smith, Collin A; Ackerman, Joshua T

2017-06-01

Variation in avian bilateral symmetry can be an indicator of developmental instability in response to a variety of stressors, including environmental contaminants. The authors used composite measures of fluctuating asymmetry to examine the influence of mercury concentrations in 2 tissues on fluctuating asymmetry within 4 waterbird species. Fluctuating asymmetry increased with mercury concentrations in whole blood and breast feathers of Forster's terns (Sterna forsteri), a species with elevated mercury concentrations. Specifically, fluctuating asymmetry in rectrix feather 1 was the most strongly correlated structural variable of those tested (wing chord, tarsus, primary feather 10, rectrix feather 6) with mercury concentrations in Forster's terns. However, for American avocets (Recurvirostra americana), black-necked stilts (Himantopus mexicanus), and Caspian terns (Hydroprogne caspia), the authors found no relationship between fluctuating asymmetry and either whole-blood or breast feather mercury concentrations, even though these species had moderate to elevated mercury exposure. The results indicate that mercury contamination may act as an environmental stressor during development and feather growth and contribute to fluctuating asymmetry of some species of highly contaminated waterbirds. Environ Toxicol Chem 2017;36:1599-1605. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Electrical effects in superfluid helium. I. thermoelectric effect in Einstein's capacitor

International Nuclear Information System (INIS)

Ledenyov, D.O.; Ledenyov, V.O.; Ledenyov, O.P.

2014-01-01

The Einstein's ideas about the thermodynamical fluctuational nature of some electrical phenomena and the difference of electrical potentials U in a capacitor at temperature T were proposed in 1906-1907. On base of these ideas we explain the experimental results, which were recently observed under the action of the second sound standing wave in the electrical capacitors which take placed in the superfluid Sup>4He and in the torsional mechanical resonator. The Einstein's approach, based on the interrelation of thermal, mechanical and electrical fluctuations, allows to obtain the quantitative results, coinciding with the experimental data for the correlations of the alternate low temperatures difference in second sound wave and alternate electric potentials difference between the capacitor plates in superfluid helium at as well as in the rotating mechanical oscillator

Molecular dynamics simulation of the response of bi-disperse polyelectrolyte brushes to external electric fields

International Nuclear Information System (INIS)

Zhang Fen; Ding Huan-Da; Duan Chao; Tong Chao-Hui; Zhao Shuang-Liang

2017-01-01

Langevin dynamics simulations have been performed to investigate the response of bi-disperse and strong polyacid chains grafted on an electrode to electric fields generated by opposite surface charges on the polyelectrolyte (PE)-grafted electrode and a second parallel electrode. Simulation results clearly show that, under a negative external electric field, the longer grafted PE chains are more strongly stretched than the shorter ones in terms of the relative change in their respective brush heights. Whereas under a positive external electric field, the grafted shorter chains collapse more significantly than the longer ones. It was found that, under a positive external electric field, the magnitude of the total electric force acting on one shorter PE chain is larger than that on one longer PE chain, or vice versa. The effects of smeared and discrete charge distributions of grafted PE chains on the response of PE brushes to external electric fields were also examined. (paper)

Optimal and Learning-Based Demand Response Mechanism for Electric Water Heater System

Directory of Open Access Journals (Sweden)

Bo Lin

2017-10-01

Full Text Available This paper investigates how to develop a learning-based demand response approach for electric water heater in a smart home that can minimize the energy cost of the water heater while meeting the comfort requirements of energy consumers. First, a learning-based, data-driven model of an electric water heater is developed by using a nonlinear autoregressive network with external input (NARX using neural network. The model is updated daily so that it can more accurately capture the actual thermal dynamic characteristics of the water heater especially in real-life conditions. Then, an optimization problem, based on the NARX water heater model, is formulated to optimize energy management of the water heater in a day-ahead, dynamic electricity price framework. A genetic algorithm is proposed in order to solve the optimization problem more efficiently. MATLAB (R2016a is used to evaluate the proposed learning-based demand response approach through a computational experiment strategy. The proposed approach is compared with conventional method for operation of an electric water heater. Cost saving and benefits of the proposed water heater energy management strategy are explored.

To the theory of fluctuations in a non-equilibrium plasma with taking into account the particle collisional interaction

International Nuclear Information System (INIS)

Puchkov, V.A.

1998-01-01

A method for calculation of non-equilibrium fluctuations in a totally ionized stable plasma with taking into account the particle collisions is proposed. The spectrum of high-frequency fluctuations of the electric field is calculated by the developed method. The formula obtained for the spectrum takes into consideration both the Coulomb collisions and influence of collective effects on the collisions and is applicable for stable arbitrary distributions of electrons and ions

Singlet ground-state fluctuations in praseodymium observed by muon spin relaxation in PrP and PrP0.9

International Nuclear Information System (INIS)

Noakes, D R; Waeppling, R; Kalvius, G M; Jr, M F White; Stronach, C E

2005-01-01

Muon spin relaxation (μSR) in the singlet ground-state compounds PrP and PrP 0.9 reveals the unusual situation of a Lorentzian local field distribution with fast-fluctuation-limit strong-collision dynamics, a case that does not show motional narrowing. Contrary to publications by others, where PrP 0.9 was asserted to have vacancy-induced spin-glass freezing, no spin-glass freezing is seen in PrP 0.9 or PrP down to ≤100mK. This was confirmed by magnetization measurements on these same samples. In both compounds, the muon spin relaxation rate does increase as temperature decreases, demonstrating increasing strength of the paramagnetic response. A Monte Carlo model of fluctuations of Pr ions out of their crystalline-electric-field singlet ground states into their magnetic excited states (and back down again) produces the strong-collision-dynamic Lorentzian relaxation functions observed at each individual temperature but not the observed temperature dependence. This model contains no exchange interaction, and so predicts decreasing paramagnetic response as the temperature decreases, contrary to the temperature dependence observed. Comparison of the simulations to the data suggests that the exchange interaction is causing the system to approach magnetic freezing (by mode softening), but fails to complete the process

Monitoring of interaction of low-frequency electric field with biological tissues upon optical clearing with optical coherence tomography.

Science.gov (United States)

Peña, Adrián F; Doronin, Alexander; Tuchin, Valery V; Meglinski, Igor

2014-08-01

The influence of a low-frequency electric field applied to soft biological tissues ex vivo at normal conditions and upon the topical application of optical clearing agents has been studied by optical coherence tomography (OCT). The electro-kinetic response of tissues has been observed and quantitatively evaluated by the double correlation OCT approach, utilizing consistent application of an adaptive Wiener filtering and Fourier domain correlation algorithm. The results show that fluctuations, induced by the electric field within the biological tissues are exponentially increased in time. We demonstrate that in comparison to impedance measurements and the mapping of the temperature profile at the surface of the tissue samples, the double correlation OCT approach is much more sensitive to the changes associated with the tissues' electro-kinetic response. We also found that topical application of the optical clearing agent reduces the tissues' electro-kinetic response and is cooling the tissue, thus reducing the temperature induced by the electric current by a few degrees. We anticipate that dcOCT approach can find a new application in bioelectrical impedance analysis and monitoring of the electric properties of biological tissues, including the resistivity of high water content tissues and its variations.

Evaluation of Electric Power Procurement Strategies by Stochastic Dynamic Programming

Science.gov (United States)

Saisho, Yuichi; Hayashi, Taketo; Fujii, Yasumasa; Yamaji, Kenji

In deregulated electricity markets, the role of a distribution company is to purchase electricity from the wholesale electricity market at randomly fluctuating prices and to provide it to its customers at a given fixed price. Therefore the company has to take risk stemming from the uncertainties of electricity prices and/or demand fluctuation instead of the customers. The way to avoid the risk is to make a bilateral contact with generating companies or install its own power generation facility. This entails the necessity to develop a certain method to make an optimal strategy for electric power procurement. In such a circumstance, this research has the purpose for proposing a mathematical method based on stochastic dynamic programming and additionally considering the characteristics of the start-up cost of electric power generation facility to evaluate strategies of combination of the bilateral contract and power auto-generation with its own facility for procuring electric power in deregulated electricity market. In the beginning we proposed two approaches to solve the stochastic dynamic programming, and they are a Monte Carlo simulation method and a finite difference method to derive the solution of a partial differential equation of the total procurement cost of electric power. Finally we discussed the influences of the price uncertainty on optimal strategies of power procurement.

Numerical Investigation on a Prototype Centrifugal Pump Subjected to Fluctuating Rotational Speed

Directory of Open Access Journals (Sweden)

Yu-Liang Zhang

2014-01-01

Full Text Available The rotational speed of pumps often encounters fluctuation in engineering for some reasons. In this paper, in order to study the transient response characteristic of a prototype centrifugal pump subjected to fluctuating rotational speed, a closed-loop pipe system including the pump is built to accomplish unsteady flow calculations in which the boundary conditions at the inlet and the outlet of the pump are not required to be set. The external performance results show that the head’s responsiveness to the fluctuating rotational speed is very good, while the flow rate’s responsiveness is slightly delayed. The variation tendencies of the static pressures at the inlet and the outlet of the pump are almost completely opposite, wherein the variation tendency of the static pressure at the outlet is identical with that of the rotational speed. The intensity of the turbulence energy in each impeller channel is relatively uniform in the transient flow calculations, while, in the quasi-steady flow calculation, it becomes weaker in a channel closed to the volute tongue. The nondimensional flow rate and head coefficients are dependent on the rotational speed, and their variation tendencies are opposite to that of the fluctuating rotational speed as a whole.

The effect of longitudinal fluctuations in (3+1)D viscous hydrodynamics

Energy Technology Data Exchange (ETDEWEB)

Pang, Long-Gang; Karpenko, Yuri [FIAS, Frankfurt (Germany); Petersen, Hannah [FIAS, Frankfurt (Germany); ITP, Goethe University, Frankfurt (Germany); GSI, Darmstadt (Germany); Huovinen, Pasi [ITP, University of Wroclaw (Poland); Wang, Xin-Nian [CCNU, Wuhan (China); LBNL, Berkeley (United States)

2016-07-01

The energy density fluctuations of the quark gluon plasma (QGP) in the transverse plane are studied in detail and found to be important to explain the high order harmonic flow v{sub n} at RHIC and LHC. However, the energy density fluctuations along longitudinal direction (space-time rapidity η{sub s}) have not been fully investigated yet, even though they should exist as well. Previous studies show that the longitudinal fluctuations strongly depend on the initial entropy deposition mechanisms. In this work AMPT initial conditions are used where HIJING introduces longitudinal fluctuations originating from the asymmetry between forward and backward going participants, string length fluctuations and finite number of partons at different collision energies. The longitudinal fluctuations have been found to be responsible for the de-correlation of anisotropic flow and twist of event planes along rapidity. We study the effect of longitudinal fluctuations on the QGP expansion in both transverse and longitudinal direction within CLVisc, a (3+1)D viscous hydrodynamic code parallelized on GPU using OpenCL, to check whether the anisotropic flow is affected by longitudinal fluctuations and to determine appropriate shear viscosity over entropy density coefficients η/s in comparison with experiments at RHIC and LHC.

Market-based Demand Response via Residential Plug-in Electric Vehicles in Smart Grids

OpenAIRE

Rassaei, Farshad; Soh, Wee-Seng; Chua, Kee-Chaing

2015-01-01

Flexibility in power demand, diverse usage patterns and storage capability of plug-in electric vehicles (PEVs) grow the elasticity of residential electricity demand remarkably. This elasticity can be utilized to form the daily aggregated demand profile and/or alter instantaneous demand of a system wherein a large number of residential PEVs share one electricity retailer or an aggregator. In this paper, we propose a demand response (DR) technique to manage vehicle-to-grid (V2G) enabled PEVs' e...

Observations of Pc5 micropulsation-related electric field oscillations in the equatorial ionosphere

Directory of Open Access Journals (Sweden)

C. A. Reddy

Full Text Available A 54.95-MHz coherent backscatter radar, an ionosonde and the magnetometer located at Trivandrum in India (8.5°N, 77°E, 0.5°N dip angle recorded large-amplitude ionospheric fluctuations and magnetic field fluctuations associated with a Pc5 micropulsation event, which occurred during an intense magnetic storm on 24 March 1991 (A_p=161. Simultaneous 100-nT-level fluctuations are also observed in the H-component at Brorfelde, Denmark (55.6°N gm and at Narsarsuaq, Greenland (70.6°N gm. Our study of the above observations shows that the E-W electric field fluctuations in the E- and F-regions and the magnetic field fluctuations at Thumba are dominated by a near-sinusoidal oscillation of 10 min during 1730-1900 IST (1200-1330 UT, the amplitude of the electric field oscillation in the equatorial electrojet (EEJ is 0.1-0.25 mV m^-1 and it increases with height, while it is about 1.0 mV m^-1 in the F-region, the ground-level H-component oscillation can be accounted for by the ionospheric current oscillation generated by the observed electric field oscillation in the EEJ and the H-component oscillations at Trivandrum and Brorfelde are in phase with each other. The observations are interpreted in terms of a compressional cavity mode resonance in the inner magnetosphere and the associated ionospheric electric field penetrating from high latitudes to the magnetic equator.

Terrestrial water load and groundwater fluctuation in the Bengal Basin

NARCIS (Netherlands)

Burgess, W.G.; Shamsudduha, M.; Taylor, R.G.; Zahid, A.; Ahmed, K.M.; Mukherjee, A.; Lapworth, D.J.; Bense, V.F.

2017-01-01

Groundwater-level fluctuations represent hydraulic responses to changes in groundwater storage due to aquifer recharge and drainage as well as to changes in stress that include water mass loading and unloading above the aquifer surface. The latter 'poroelastic' response of confined aquifers is a

Examining demand response, renewable energy and efficiencies to meet growing electricity needs

International Nuclear Information System (INIS)

Elliot, N.; Eldridge, M.; Shipley, A.M.; Laitner, J.S.; Nadel, S.; Silverstein, A.; Hedman, B.; Sloan, M.

2007-01-01

While Texas has already taken steps to improve its renewable energy portfolio (RPS), and its energy efficiency improvement program (EEIP), the level of savings that utilities can achieve through the EEIP can be greatly increased. This report estimated the size of energy efficiency and renewable energy resources in Texas, and suggested a range of policy options that might be adopted to further extend EEIP. Current forecasts suggest that peak demand in Texas will increase by 2.3 per cent annually from 2007-2012, a level of growth which is threatening the state's ability to maintain grid reliability at reasonable cost. Almost 70 per cent of installed generating capacity is fuelled by natural gas in Texas. Recent polling has suggested that over 70 per cent of Texans are willing support increased spending on energy efficiency. Demand response measures that may be implemented in the state include incentive-based programs that pay users to reduce their electricity consumption during specific times and pricing programs, where customers are given a price signal and are expected to moderate their electricity usage. By 2023, the widespread availability of time-varying retail electric rates and complementary communications and control methods will permanently change the nature of electricity demand in the state. At present, the integrated utilities in Texas offer a variety of direct load control and time-of-use, curtailable, and interruptible rates. However, with the advent of retail competition now available as a result of the structural unbundling of investor-owned utilities, there is less demand response available in Texas. It was concluded that energy efficiency, demand response, and renewable energy resources can meet the increasing demand for electricity in Texas over the next 15 years. 4 figs

Fluctuations on the magnetic response of superconducting thin films of Nb and MgB{sub 2} - Percolation limit of vortex mobility

Energy Technology Data Exchange (ETDEWEB)

Colauto, F. [Depto. de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil); Orgiani, P.; Xi, X.X. [Pennsylvania State University, Department of Physics, University Park, PA (United States); Kang, W.N.; Choi, E.M.; Kim, H.J.; Lee, S.I. [Pohang University of Science and Technology, Department of Physics, Pohang (Korea, Republic of); Patino, E.; Blamire, M.G. [University of Cambridge, Department of Metallurgy and Materials Sciences, Cambridge (United Kingdom); Ortiz, W.A. [Depto. de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil)], E-mail: wortiz@df.ufscar.br

2007-09-01

Application of a magnetic field of sufficient intensity orthogonal to superconducting thin films may produce dendritic patterns, where penetrated and Meissner regions coexist. The dendritic mode can be detected by AC-susceptibility measurements, since fingers penetrated by the magnetic field act as intergranular material. Measurements of the AC-susceptibility have the conventional shape for smaller values of magnitude and frequency of the excitation field. However, for frequencies in the vicinity of 1 kHz and AC-fields around 3 Oe and above, the curve deviates from its canonical behavior and fluctuates, the excursion becoming wider as the amplitude is increased. In this contribution we present results of a systematic study conducted to determine the threshold between smooth and fluctuating regimes of the magnetic response of the film, which is interpreted as the percolation limit of vortex mobility throughout the sample.

Causal electric charge diffusion and balance functions in relativistic heavy-ion collisions

Science.gov (United States)

Kapusta, Joseph I.; Plumberg, Christopher

2018-01-01

We study the propagation and diffusion of electric charge fluctuations in high-energy heavy-ion collisions using the Cattaneo form for the dissipative part of the electric current. As opposed to the ordinary diffusion equation this form limits the speed at which charge can propagate. Including the noise term in the current, which arises uniquely from the fluctuation-dissipation theorem, we calculate the balance functions for charged hadrons in a simple 1+1-dimensional Bjorken hydrodynamical model. Limiting the speed of propagation of charge fluctuations increases the height and reduces the width of these balance functions when plotted versus rapidity. We also estimate the numerical value of the associated diffusion time constant from anti-de Sitter-space/conformal-field theory.

Statistical fluctuations in reactors (1960); Fluctuations statistiques dans les piles (1960)

Energy Technology Data Exchange (ETDEWEB)

Raievski, V [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

The theory of space dependent fluctuations is developed, taking into account the effect of delayed neutrons. The 'diffusion equation' or Fokker-Planck equation is worked out in the case of age and two group theory, but the first one because of in physical significance is used in this report. The theory is applied to the study of the spectral density of fluctuations and fluctuations of counting rate and current flowing through the charge resistor of an ionisation chamber, the effect of the entrance capacity is discussed. The space dependent theory shows that the fluctuations in the core and reflector of a near critical pile obey to the same law. The spectral densities in the core and reflector are similar, there is no sensible attenuation of high frequency fluctuations in the reflector. Compared to the space independent theory, this theory give better agreement with experience, one can use the simple space independent theory but in checking with experiment it is necessary to introduce numerical factors given by the space dependent theory. (author) [French] La theorie des fluctuations statistiques est developpee dans le cas spatial en tenant compte des neutrons retardes, et dans le cadre de la theorie de l'age vitesse. L'equation d'evolution de la probabilite est egalement etablie dans le cadre de la theorie a deux groupes. Ces considerations sont appliquees a l'etude de la densite spectrale des fluctuations et aux fluctuations des taux de comptage et du courant circulant dans la resistance de charge du detecteur. On etudie en particulier l'effet de la constante de temps introduite par la capacite d'entree. Cette theorie etablit que les fluctuations dans le coeur et le reflecteur suivent la meme loi pour une pile critique, il en est de meme pour la densite spectrale meme a frequence elevee. Par rapport a la theorie d'ensemble, la theorie spatiale donne des coefficients numeriques ou facteurs de forme, qui permettent d'obtenir un bon accord entre la theorie et l

Out-of-time-order fluctuation-dissipation theorem

Science.gov (United States)

Tsuji, Naoto; Shitara, Tomohiro; Ueda, Masahito

2018-01-01

We prove a generalized fluctuation-dissipation theorem for a certain class of out-of-time-ordered correlators (OTOCs) with a modified statistical average, which we call bipartite OTOCs, for general quantum systems in thermal equilibrium. The difference between the bipartite and physical OTOCs defined by the usual statistical average is quantified by a measure of quantum fluctuations known as the Wigner-Yanase skew information. Within this difference, the theorem describes a universal relation between chaotic behavior in quantum systems and a nonlinear-response function that involves a time-reversed process. We show that the theorem can be generalized to higher-order n -partite OTOCs as well as in the form of generalized covariance.

Transitions in optimal adaptive strategies for populations in fluctuating environments

Science.gov (United States)

Mayer, Andreas; Mora, Thierry; Rivoire, Olivier; Walczak, Aleksandra M.

2017-09-01

Biological populations are subject to fluctuating environmental conditions. Different adaptive strategies can allow them to cope with these fluctuations: specialization to one particular environmental condition, adoption of a generalist phenotype that compromises between conditions, or population-wise diversification (bet hedging). Which strategy provides the largest selective advantage in the long run depends on the range of accessible phenotypes and the statistics of the environmental fluctuations. Here, we analyze this problem in a simple mathematical model of population growth. First, we review and extend a graphical method to identify the nature of the optimal strategy when the environmental fluctuations are uncorrelated. Temporal correlations in environmental fluctuations open up new strategies that rely on memory but are mathematically challenging to study: We present analytical results to address this challenge. We illustrate our general approach by analyzing optimal adaptive strategies in the presence of trade-offs that constrain the range of accessible phenotypes. Our results extend several previous studies and have applications to a variety of biological phenomena, from antibiotic resistance in bacteria to immune responses in vertebrates.

Pressure-induced americium valence fluctuations revealed by electrical resistivity

Czech Academy of Sciences Publication Activity Database

Kolomiets, A. V.; Griveau, J.C.; Heathman, S.; Shick, Alexander; Wastin, F.; Faure, P.; Klosek, V.; Genestier, C.; Baclet, N.; Havela, L.

2008-01-01

Roč. 82, č. 5 (2008), 57007/1-57007/5 ISSN 0295-5075 R&D Projects: GA MŠk OC 144; GA ČR GA202/07/0644 Grant - others:EU(XE) RITA -CT-2006-026176 Institutional research plan: CEZ:AV0Z10100520 Keywords : electrical conductivity * strong electron interactions * electronic structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.203, year: 2008

Blood flow response to electrically induced twitch and tetanic lower-limb muscle contractions.

NARCIS (Netherlands)

Janssen, T.W.; Hopman, M.T.E.

2003-01-01

OBJECTIVES: To compare the effect of electric stimulation (ES)-induced twitch with tetanic leg muscle contractions on blood flow responses and to assess blood flow responses in the contralateral inactive leg. DESIGN: Intervention with within-subject comparisons. SETTING: University research

Electricity distribution. Price control, reliability and customer services: response to OFFER

International Nuclear Information System (INIS)

1994-02-01

This document presents the views of the National Consumer Council to a recent consultation paper from OFFER, the body responsible for regulation of the United Kingdom electric power industry. The financial performance of the Regional Electricity Companies (RECs) is reviewed by examining how it relates to the prices paid by domestic consumers. A critical analysis is presented of OFFER's notion of the revision of the existing price control mechanism for the distribution businesses within the RECs. Standards of performance, debt and consumer disconnection are also examined. (UK)

1/f Fluctuations in ion implanted metal semiconductor contacts

International Nuclear Information System (INIS)

Stojanovic, M.; Marjanovic, N.; Radojevic, B.

1998-01-01

Ion implanted Metal-Semiconductor contacts is the most widely used structures in electrical devices. Weather complete devices or some parts are of interest, properties of metal-semiconductor junction strongly influence the quality and external characteristic of electronic devices. That is the reason why special attention is paid to the investigation of factor (noise for example) that could influence given junction. Low frequency 1/f fluctuations (noise) are constantly present in metal-semiconductor junction, so measurement of their level as well as the dependence on factors such as temperature must be taken into account in detailed analysis of electrical characteristics of devices such as contact, nuclear detector with surface barrier etc. In this paper we present the results of low frequency noise level measurements on TiN-Ti-Si structures produced by As + ion implantation. (author)

Modeling the response of a standard accretion disc to stochastic viscous fluctuations

Science.gov (United States)

Ahmad, Naveel; Misra, Ranjeev; Iqbal, Naseer; Maqbool, Bari; Hamid, Mubashir

2018-01-01

The observed variability of X-ray binaries over a wide range of time-scales can be understood in the framework of a stochastic propagation model, where viscous fluctuations at different radii induce accretion rate variability that propagate inwards to the X-ray producing region. The scenario successfully explains the power spectra, the linear rms-flux relation as well as the time-lag between different energy photons. The predictions of this model have been obtained using approximate analytical solutions or empirically motivated models which take into account the effect of these propagating variability on the radiative process of complex accretion flows. Here, we study the variation of the accretion rate due to such viscous fluctuations using a hydro-dynamical code for the standard geometrically thin, gas pressure dominated α-disc with a zero torque boundary condition. Our results confirm earlier findings that the time-lag between a perturbation and the resultant inner accretion rate variation depends on the frequency (or time-period) of the perturbation. Here we have quantified that the time-lag tlag ∝f-0.54 , for time-periods less than the viscous time-scale of the perturbation radius and is nearly constant otherwise. This, coupled with radiative process would produce the observed frequency dependent time-lag between different energy bands. We also confirm that if there are random Gaussian fluctuations of the α-parameter at different radii, the resultant inner accretion rate has a power spectrum which is a power-law.

Temperature, density and potential fluctuations by a swept Langmuir probe in Wendelstein 7-AS

Energy Technology Data Exchange (ETDEWEB)

Giannone, L.; Niedermeyer, H; Endler, M; Theimer, G; Rudyj, A; Verplancke, Ph [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Balbin, R; Hidalgo, C [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain)

1994-12-31

Numerous experiments using a Langmuir probe to investigate the magnitude of temperature fluctuations and their contribution to heat transport in the edge region of tokamak plasmas have been carried out. Sweeping the voltage applied to a tip fast enough to ensure that the ion saturation current, floating potential and electron temperature may be assumed to be constant during the sweep is experimentally more difficult than alternative schemes but this disadvantage is compensated by the ability to measure all three of these quantities at one spatial location. Sweep frequencies up to 600 kHz have been employed to obtain the current-voltage characteristic. A radial scan in the vicinity of the velocity shear layer on W7-AS stellarator was performed. Inside and outside the shear layer the normalised magnitude of the temperature fluctuations was found to be approximately 30% larger than the magnitude of the electron density fluctuations, approaching a value of 0.12 and 0.09 respectively at a radial position 1 cm inside the shear layer. An increase in the coherency of the temperature, floating potential and density fluctuations between tips with a poloidal separation of 2 mm was also measured as the shear layer was crossed. Heat conduction produced by correlated temperature and poloidal electric field fluctuations is therefore possible. An increasing coherence of temperature and floating potential fluctuations leads to an increase in the coherence of temperature and plasma potential fluctuations as the shear layer was crossed. (author) 7 refs., 3 figs.

Turbulent fluctuations and radial transport in the scrape-off layer of the ASDEX tokamak

Energy Technology Data Exchange (ETDEWEB)

Endler, M [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85740 Garching (Germany); Giannone, L. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85740 Garching (Germany); McCormick, K [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85740 Garching (Germany); Niedermeyer, H [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85740 Garching (Germany); Rudyj, A [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85740 Garching (Germany); Theimer, G [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85740 Garching (Germany); Tsois, N [NCSR ` Demokritos` , Athens (Greece); ASDEX Team

1995-04-01

Electrostatic fluctuations have been measured in the scrape-off layer of ASDEX by Langmuir probes and by observation of H{sub {alpha}} light with high poloidal and temporal resolution. It was demonstrated that these fluctuations contribute a significant, if not dominant, fraction of the ``anomalous`` radial particle transport. A model for an instability mechanism specific to the SOL is presented including density, temperature and electric potential fluctuations. From this model mixing length estimates for the radial transport and resulting density and pressure gradients in the SOL are derived and compared to measurements in the mid-plane and in the divertor of ASDEX. In spite of several simplifications in the model a quantitative agreement up to factors of 1-3 and a qualitative agreement for variations of discharge parameters is achieved between the model predictions and the measurements. ((orig.)).

Turbulent fluctuations and radial transport in the scrape-off layer of the ASDEX tokamak

International Nuclear Information System (INIS)

Endler, M.; Giannone, L.; McCormick, K.; Niedermeyer, H.; Rudyj, A.; Theimer, G.; Tsois, N.

1995-01-01

Electrostatic fluctuations have been measured in the scrape-off layer of ASDEX by Langmuir probes and by observation of H α light with high poloidal and temporal resolution. It was demonstrated that these fluctuations contribute a significant, if not dominant, fraction of the ''anomalous'' radial particle transport. A model for an instability mechanism specific to the SOL is presented including density, temperature and electric potential fluctuations. From this model mixing length estimates for the radial transport and resulting density and pressure gradients in the SOL are derived and compared to measurements in the mid-plane and in the divertor of ASDEX. In spite of several simplifications in the model a quantitative agreement up to factors of 1-3 and a qualitative agreement for variations of discharge parameters is achieved between the model predictions and the measurements. ((orig.))

Nonlinear quenching of current fluctuations in a self-exciting homopolar dynamo

Science.gov (United States)

Hide, R.

In the interpretation of geomagnetic polarity reversals with their highly variable frequency over geological time it is necessary, as with other irregularly fluctuating geophysical phenomena, to consider the relative importance of forced contributions associated with changing boundary conditions and of free contributions characteristic of the behaviour of nonlinear systems operating under fixed boundary conditions. New evidence -albeit indirect- in favour of the likely predominance of forced contributions is provided by the discovery reported here of the possibility of complete quenching by nonlineax effects of current fluctuations in a self-exciting homopolar dynamo with its single Faraday disk driven into rotation with angular speed y(τ) (where τ denotes time) by a steady applied couple. The armature of an electric motor connected in series with the coil of the dynamo is driven into rotation' with angular speed z(τ) by a torque xf (x) due to Lorentz forces associated with the electric current x(τ) in the system (just as certain parts of the spectrum of eddies within the liquid outer core are generated largely by Lorentz forces associated with currents generated by the self-exciting magnetohydrodynamic (MHD) geodynamo). The discovery is based on bifurcation analysis supported by computational studies of the following (mathematically novel) autonomous set of nonlinear ordinary differential equations: dx/dt = x(y - 1) - βzf(x), dy/dt = α(1 - x²) - κy, dz/dt = xf (x) -λz, where f (x) = 1 - ɛ + ɛσx, in cases when the dimensionless parameters (α, β, κ, λ, σ) are all positive and 0 ≤ ɛ ≤ 1. Within those regions of (α, β, κ, λ, σ) parameter space where the applied couple, as measured by α, is strong enough for persistent dynamo action (i.e. x ≠ 0) to occur at all, there are in general extensive regions where x(τ) exhibits large amplitude regular or irregular (chaotic) fluctuations. But these fluctuating régimes shrink in size as increases

Electron quantum interferences and universal conductance fluctuations

International Nuclear Information System (INIS)

Benoit, A.; Pichard, J.L.

1988-05-01

Quantum interferences yield corrections to the classical ohmic behaviour predicted by Boltzmann theory in electronic transport: for instance the well-known ''weak localization'' effects. Furthermore, very recently, quantum interference effects have been proved to be responsible for statistically different phenomena, associated with Universal Conductance Fluctuations and observed on very small devices [fr

Current-Fluctuation Mechanism of Field Emitters Using Metallic Single-Walled Carbon Nanotubes with High Crystallinity

Directory of Open Access Journals (Sweden)

Norihiro Shimoi

2017-12-01

Full Text Available Field emitters can be used as a cathode electrode in a cathodoluminescence device, and single-walled carbon nanotubes (SWCNTs that are synthesized by arc discharge are expected to exhibit good field emission (FE properties. However, a cathodoluminescence device that uses field emitters radiates rays whose intensity considerably fluctuates at a low frequency, and the radiant fluctuation is caused by FE current fluctuation. To solve this problem, is very important to obtain a stable output for field emitters in a cathodoluminescence device. The authors consider that the electron-emission fluctuation is caused by Fowler–Nordheim electron tunneling and that the electrons in the Fowler–Nordheim regime pass through an inelastic potential barrier. We attempted to develop a theoretical model to analyze the power spectrum of the FE current fluctuation using metallic SWCNTs as field emitters, owing to their electrical conductivity by determining their FE properties. Field emitters that use metallic SWCNTs with high crystallinity were successfully developed to achieve a fluctuating FE current from field emitters at a low frequency by employing inelastic electron tunneling. This paper is the first report of the successful development of an inelastic-electron-tunneling model with a Wentzel–Kramers–Brillouin approximation for metallic SWCNTs based on the evaluation of FE properties.

Comparative analyses of seven technologies to facilitate the integration of fluctuating renewable energy sources

DEFF Research Database (Denmark)

Mathiesen, Brian Vad; Lund, Henrik

2009-01-01

An analysis of seven different technologies is presented. The technologies integrate fluctuating renewable energy sources (RES) such as wind power production into the electricity supply, and the Danish energy system is used as a case. Comprehensive hour-by-hour energy system analyses are conducted...... of a complete system meeting electricity, heat and transport demands, and including RES, power plants, and combined heat and power production (CHP) for district heating and transport technologies. In conclusion, the most fuel-efficient and least-cost technologies are identified through energy system...

Electrical response of relaxing dielectrics compressed by arbitrary stress pulses

International Nuclear Information System (INIS)

Lysne, P.C.

1983-01-01

The theoretical problem of the electric response of biased dielectrics and piezoelectrics subjected to planar stress pulse loading is considered. The materials are taken to exhibit dielectric relaxation in the sense that changes in the polarization induced by electric fields do not occur instantaneously with changes in the fields. While this paper considers arbitrary stress pulse loading of the specimen, examples that are amenable to projectile impact techniques are considered in detail. They are shock reverberation, thin pulse, and ramp loading experiments. It is anticipated that these experiments will play a role in investigations of dielectric relaxation caused by shock induced damage in insulators

Empowering Variable Renewables - Options for Flexible Electricity Systems

Energy Technology Data Exchange (ETDEWEB)

Chandler, Hugo [Renewable Energy Unit, International Energy Agency, Paris (France)

2008-07-01

A flexible electricity system is one that can respond reliably, and rapidly, to large fluctuations in supply and demand. Flexibility is already present in all power systems, in order to manage fluctuations in demand, and it is crucial for high performance and economic and reliable operation. This paper looks at measures to increase flexibility. but careful cost/benefit analysis is essential, and specific national and regional circumstances will influence the choice of option(s).

Influence of temperature fluctuations on equilibrium ice sheet volume

Science.gov (United States)

Bøgeholm Mikkelsen, Troels; Grinsted, Aslak; Ditlevsen, Peter

2018-01-01

Forecasting the future sea level relies on accurate modeling of the response of the Greenland and Antarctic ice sheets to changing temperatures. The surface mass balance (SMB) of the Greenland Ice Sheet (GrIS) has a nonlinear response to warming. Cold and warm anomalies of equal size do not cancel out and it is therefore important to consider the effect of interannual fluctuations in temperature. We find that the steady-state volume of an ice sheet is biased toward larger size if interannual temperature fluctuations are not taken into account in numerical modeling of the ice sheet. We illustrate this in a simple ice sheet model and find that the equilibrium ice volume is approximately 1 m SLE (meters sea level equivalent) smaller when the simple model is forced with fluctuating temperatures as opposed to a stable climate. It is therefore important to consider the effect of interannual temperature fluctuations when designing long experiments such as paleo-spin-ups. We show how the magnitude of the potential bias can be quantified statistically. For recent simulations of the Greenland Ice Sheet, we estimate the bias to be 30 Gt yr-1 (24-59 Gt yr-1, 95 % credibility) for a warming of 3 °C above preindustrial values, or 13 % (10-25, 95 % credibility) of the present-day rate of ice loss. Models of the Greenland Ice Sheet show a collapse threshold beyond which the ice sheet becomes unsustainable. The proximity of the threshold will be underestimated if temperature fluctuations are not taken into account. We estimate the bias to be 0.12 °C (0.10-0.18 °C, 95 % credibility) for a recent estimate of the threshold. In light of our findings it is important to gauge the extent to which this increased variability will influence the mass balance of the ice sheets.

The neuronal response to electrical constant-amplitude pulse train stimulation: additive Gaussian noise.

Science.gov (United States)

Matsuoka, A J; Abbas, P J; Rubinstein, J T; Miller, C A

2000-11-01

Experimental results from humans and animals show that electrically evoked compound action potential (EAP) responses to constant-amplitude pulse train stimulation can demonstrate an alternating pattern, due to the combined effects of highly synchronized responses to electrical stimulation and refractory effects (Wilson et al., 1994). One way to improve signal representation is to reduce the level of across-fiber synchrony and hence, the level of the amplitude alternation. To accomplish this goal, we have examined EAP responses in the presence of Gaussian noise added to the pulse train stimulus. Addition of Gaussian noise at a level approximately -30 dB relative to EAP threshold to the pulse trains decreased the amount of alternation, indicating that stochastic resonance may be induced in the auditory nerve. The use of some type of conditioning stimulus such as Gaussian noise may provide a more 'normal' neural response pattern.

Adaptation to Temporally Fluctuating Environments by the Evolution of Maternal Effects.

Directory of Open Access Journals (Sweden)

Snigdhadip Dey

2016-02-01

Full Text Available All organisms live in temporally fluctuating environments. Theory predicts that the evolution of deterministic maternal effects (i.e., anticipatory maternal effects or transgenerational phenotypic plasticity underlies adaptation to environments that fluctuate in a predictably alternating fashion over maternal-offspring generations. In contrast, randomizing maternal effects (i.e., diversifying and conservative bet-hedging, are expected to evolve in response to unpredictably fluctuating environments. Although maternal effects are common, evidence for their adaptive significance is equivocal since they can easily evolve as a correlated response to maternal selection and may or may not increase the future fitness of offspring. Using the hermaphroditic nematode Caenorhabditis elegans, we here show that the experimental evolution of maternal glycogen provisioning underlies adaptation to a fluctuating normoxia-anoxia hatching environment by increasing embryo survival under anoxia. In strictly alternating environments, we found that hermaphrodites evolved the ability to increase embryo glycogen provisioning when they experienced normoxia and to decrease embryo glycogen provisioning when they experienced anoxia. At odds with existing theory, however, populations facing irregularly fluctuating normoxia-anoxia hatching environments failed to evolve randomizing maternal effects. Instead, adaptation in these populations may have occurred through the evolution of fitness effects that percolate over multiple generations, as they maintained considerably high expected growth rates during experimental evolution despite evolving reduced fecundity and reduced embryo survival under one or two generations of anoxia. We develop theoretical models that explain why adaptation to a wide range of patterns of environmental fluctuations hinges on the existence of deterministic maternal effects, and that such deterministic maternal effects are more likely to contribute to

Applying Psychology to Economic Policy Design: Using Incentive Preserving Rebates to Increase Acceptance of Critical Peak Electricity Pricing

OpenAIRE

Letzler, Robert

2007-01-01

This project extends the idea that policy makers should address problems by improving economic incentives. This project adds that presenting incentives in a way that reflects how people make decisions can sometimes improve consumers’ responses to the incentives and policy outcomes. This paper uses behavioral economics to propose ways to increase electricity policy effectiveness. The cost of generating power fluctuates enormously from hour to hour but most customers pay time-invariant prices f...

Turning the wind into hydrogen: The long-run impact on electricity prices and generating capacity

International Nuclear Information System (INIS)

Green, Richard; Hu, Helen; Vasilakos, Nicholas

2011-01-01

Hydrogen production via electrolysis has been proposed as a way of absorbing the fluctuating electricity generated by wind power, potentially allowing the use of cheap electricity at times when it would otherwise be in surplus. We show that large-scale adoption of electrolysers would change the shape of the load-duration curve for electricity, affecting the optimal capacity mix. Nuclear power stations will replace gas-fired power stations, as they are able to run for longer periods of time. Changes in the electricity capacity mix will be much greater than changes to the pattern of prices. The long-run supply price of hydrogen will thus tend to be insensitive to the amount produced. - Research Highlights: → Hydrogen production from electrolysis may offset intermittent wind generation. → The generation capacity mix will change in response to changed demand patterns. → The long-run equilibrium supply curve for hydrogen will be quite flat. → The production cost will be very sensitive to fuel prices paid by generators.

Low-loss metamaterial electromagnetically induced transparency based on electric toroidal dipolar response

Energy Technology Data Exchange (ETDEWEB)

Li, Hai-ming; Liu, Shao-bin, E-mail: lsb@nuaa.edu.cn; Liu, Si-yuan; Ding, Guo-wen; Yang, Hua; Yu, Zhi-yang; Zhang, Hai-feng [Key Laboratory of Radar Imaging and Microwave Photonics, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016 (China); Wang, Shen-yun [Research Center of Applied Electromagnetic, Nanjing University of Information Science and Technology, Nanjing, 210044 (China)

2015-02-23

In this paper, a low-loss and high transmission analogy of electromagnetically induced transparency based on electric toroidal dipolar response is numerically and experimentally demonstrated. It is obtained by the excitation of the low-loss electric toroidal dipolar response, which confines the magnetic field inside a dielectric substrate with toroidal geometry. The metamaterial electromagnetically induced transparency (EIT) structure is composed of the cut wire and asymmetric split-ring resonators. The transmission level is as high as 0.88, and the radiation loss is greatly suppressed, which can be proved by the surface currents distributions, the magnetic field distributions, and the imaginary parts of the effective permeability and permittivity. It offers an effective way to produce low-loss and high transmission metamaterial EIT.

Inward transport of a toroidally confined plasma subject to strong radial electric fields

Science.gov (United States)

Roth, J. R.; Krawczonek, W. M.; Powers, E. J.; Hong, J.; Kim, Y.

1977-01-01

The paper aims at showing that the density and confinement time of a toroidal plasma can be enhanced by radial electric fields far stronger than the ambipolar values, and that, if such electric fields point into the plasma, radially inward transport can result. The investigation deals with low-frequency fluctuation-induced transport using digitally implemented spectral analysis techniques and with the role of strong applied radial electric fields and weak vertical magnetic fields on plasma density and particle confinement times in a Bumpy Torus geometry. Results indicate that application of sufficiently strong radially inward electric fields results in radially inward fluctuation-induced transport into the toroidal electrostatic potential well; this inward transport gives rise to higher average electron densities and longer particle confinement times in the toroidal plasma.

Synergistic responses of superficial chemistry and micro topography of titanium created by wire-type electric discharge machining.

Science.gov (United States)

Kataoka, Yu; Tamaki, Yukimichi; Miyazaki, Takashi

2011-01-01

Wire-type electric discharge machining has been applied to the manufacture of endosseous titanium implants as this computer associated technique allows extremely accurate complex sample shaping with an optimal micro textured surface during the processing. Since the titanium oxide layer is sensitively altered by each processing, the authors hypothesized that this technique also up-regulates biological responses through the synergistic effects of the superficial chemistry and micro topography. To evaluate the respective in vitro cellular responses on the superficial chemistry and micro topography of titanium surface processed by wire-type electric discharge, we used titanium-coated epoxy resin replica of the surface. An oxide layer on the titanium surface processed by wire-type electric discharge activated the initial responses of osteoblastic cells through an integrin-mediated mechanism. Since the mRNA expression of ALP on those replicas was up-regulated compared to smooth titanium samples, the micro topography of a titanium surface processed by wire-type electric discharge promotes the osteogenic potential of cells. The synergistic response of the superficial chemistry and micro topography of titanium processed by wire-type electric discharge was demonstrated in this study.

Behavioral aspects of regulation: A discussion on switching and demand response in Turkish electricity market

International Nuclear Information System (INIS)

Sirin, Selahattin Murat; Gonul, Mustafa Sinan

2016-01-01

Electricity sector has been transformed from state-owned monopolistic utilities to competitive markets with an aim to promote incentives for improving efficiency, reducing costs and increasing service quality to customers. One of the cardinal assumptions of the liberalized and competitive electricity markets is the rational actor, and decision-makers are assumed to make the best decisions that maximize their utility. However, a vast literature on behavioral economics has shown the weakness of economic theory in explaining and predicting individuals’ decision-making behavior. This issue is quite important for competition in electricity markets in which consumers’ preferences have a significant role. Despite its importance, this issue has almost been neglected in Turkey, which has taken major steps in electricity sector restructuring. Therefore, this paper aims to examine switching and demand response behavior in Turkish electricity market by using multiple correspondence and panel data analysis, and findings are discussed in light of the neoclassical and behavioral economics literature. Analyses’ results show that consumers’ switching and demand response behavior is consistent with the neoclassical literature to some extent; however, behavioral factors are also affecting consumers’ decisions. Furthermore, there are systemic problems that hinder effective functioning of the electricity market and restrict competition. - Highlights: • Behavioral economics can provide insights for consumer’ decisions. • Switching and demand response behavior is examined by econometric methods. • Results is consistent with the neoclassical literature to some extent • However, behavioral factors are also affecting consumers’ decisions.

Fluctuations and structure of amphiphilic films; Fluctuations et structure de films d`amphiphiles

Energy Technology Data Exchange (ETDEWEB)

Gourier, CH

1996-07-01

This thesis is divided in three parts.The first part exposes in a theoretical point of view, how the fluctuations spectrum of an amphiphilic film is governed by its properties and its bidimensional characteristics.The measurements of fluctuations spectra of an interface are accessible with the measurement of intensity that interface diffuses out of the specular angle, we present in the second chapter the principles of the X rays diffusion by a real interface and see how the diffuse diffusion experiments allow to determine the fluctuations spectrum of an amphiphilic film. The second part is devoted to the different experimental techniques that have allowed to realize the study of fluctuation as well as the structural study.The third part is devoted to experimental results concerning the measurements of fluctuations spectra and to the study of the structure of amphiphilic films. We show that it is possible by using an intense source of X rays (ESRF: European Synchrotron Radiation Facility) to measure the water and amphiphilic films fluctuations spectra until molecular scales. The last chapter is devoted to the structural study and film fluctuations made of di-acetylenic molecules. (N.C.)

Fluctuation and dissipation in nonequilibrium quantum field theory

International Nuclear Information System (INIS)

Ramos, Rudnei O.

1994-01-01

The nonequilibrium dynamics of a scalar field is studied using perturbation theory and a real time finite temperature formulation. The evolution equation for the scalar field is explicitly obtained, and terms responsible for noise (fluctuations) and dissipation are identified and studied in the high temperature limit. (author)

Electric potential calculation in molecular simulation of electric double layer capacitors

International Nuclear Information System (INIS)

Wang, Zhenxing; Laird, Brian B; Olmsted, David L; Asta, Mark

2016-01-01

For the molecular simulation of electric double layer capacitors (EDLCs), a number of methods have been proposed and implemented to determine the one-dimensional electric potential profile between the two electrodes at a fixed potential difference. In this work, we compare several of these methods for a model LiClO 4 -acetonitrile/graphite EDLC simulated using both the traditional fixed-charged method (FCM), in which a fixed charge is assigned a priori to the electrode atoms, or the recently developed constant potential method (CPM) (2007 J. Chem. Phys . 126 084704), where the electrode charges are allowed to fluctuate to keep the potential fixed. Based on an analysis of the full three-dimensional electric potential field, we suggest a method for determining the averaged one-dimensional electric potential profile that can be applied to both the FCM and CPM simulations. Compared to traditional methods based on numerically solving the one-dimensional Poisson’s equation, this method yields better accuracy and no supplemental assumptions. (paper)

Influence of thermal fluctuations on ligament break-up: a fluctuating lattice Boltzmann study

Science.gov (United States)

Xue, Xiao; Biferale, Luca; Sbragaglia, Mauro; Toschi, Federico

2017-11-01

Thermal fluctuations are essential ingredients in a nanoscale system, driving Brownian motion of particles and capillary waves at non-ideal interfaces. Here we study the influence of thermal fluctuations on the breakup of liquid ligaments at the nanoscale. We offer quantitative characterization of the effects of thermal fluctuations on the Plateau-Rayleigh mechanism that drives the breakup process of ligaments. Due to thermal fluctuations, the droplet sizes after break-up need to be analyzed in terms of their distribution over an ensemble made of repeated experiments. To this aim, we make use of numerical simulations based on the fluctuating lattice Boltzmann method (FLBM) for multicomponent mixtures. The method allows an accurate and efficient simulation of the fluctuating hydrodynamics equations of a binary mixture, where both stochastic viscous stresses and diffusion fluxes are introduced. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No 642069.

Experimental investigation into the fault response of superconducting hybrid electric propulsion electrical power system to a DC rail to rail fault

Science.gov (United States)

Nolan, S.; Jones, C. E.; Munro, R.; Norman, P.; Galloway, S.; Venturumilli, S.; Sheng, J.; Yuan, W.

2017-12-01

Hybrid electric propulsion aircraft are proposed to improve overall aircraft efficiency, enabling future rising demands for air travel to be met. The development of appropriate electrical power systems to provide thrust for the aircraft is a significant challenge due to the much higher required power generation capacity levels and complexity of the aero-electrical power systems (AEPS). The efficiency and weight of the AEPS is critical to ensure that the benefits of hybrid propulsion are not mitigated by the electrical power train. Hence it is proposed that for larger aircraft (~200 passengers) superconducting power systems are used to meet target power densities. Central to the design of the hybrid propulsion AEPS is a robust and reliable electrical protection and fault management system. It is known from previous studies that the choice of protection system may have a significant impact on the overall efficiency of the AEPS. Hence an informed design process which considers the key trades between choice of cable and protection requirements is needed. To date the fault response of a voltage source converter interfaced DC link rail to rail fault in a superconducting power system has only been investigated using simulation models validated by theoretical values from the literature. This paper will present the experimentally obtained fault response for a variety of different types of superconducting tape for a rail to rail DC fault. The paper will then use these as a platform to identify key trades between protection requirements and cable design, providing guidelines to enable future informed decisions to optimise hybrid propulsion electrical power system and protection design.

Demand Response in U.S. Electricity Markets: Empirical Evidence

OpenAIRE

Cappers, Peter

2009-01-01

Empirical evidence concerning demand response (DR) resources is needed in order to establish baseline conditions, develop standardized methods to assess DR availability and performance, and to build confidence among policymakers, utilities, system operators, and stakeholders that DR resources do offer a viable, cost-effective alternative to supply-side investments. This paper summarizes the existing contribution of DR resources in U.S. electric power markets. In 2008, customers enrolled in ...

Structural Fluctuations and Thermophysical Properties of Molten II-VI Compounds

Science.gov (United States)

Su, Ching-Hua; Zhu, Shen; Li, Chao; Scripa, R.; Lehoczky, Sandra L.; Kim, Y. W.; Baird, J. K.; Lin, B.; Ban, Heng; Benmore, Chris

2003-01-01

The objectives of the project are to conduct ground-based experimental and theoretical research on the structural fluctuations and thermophysical properties of molten II-VI compounds to enhance the basic understanding of the existing flight experiments in microgravity materials science programs as well as to study the fundamental heterophase fluctuation phenomena in these melts by: 1) conducting neutron scattering analysis and measuring quantitatively the relevant thermophysical properties of the II-VI melts (such as viscosity, electrical conductivity, thermal diffusivity and density) as well as the relaxation characteristics of these properties to advance the understanding of the structural properties and the relaxation phenomena in these melts and 2) performing theoretical analyses on the melt systems to interpret the experimental results. All the facilities required for the experimental measurements have been procured, installed and tested. It has long been recognized that liquid Te presents a unique case having properties between those of metals and semiconductors. The electrical conductivity for Te melt increases rapidly at melting point, indicating a semiconductor-metal transition. Te melts comprise two features, which are usually considered to be incompatible with each other: covalently bound atoms and metallic-like behavior. Why do Te liquids show metallic behavior? is one of the long-standing issues in liquid metal physics. Since thermophysical properties are very sensitive to the structural variations of a melt, we have conducted extensive thermophysical measurements on Te melt.

Structural Fluctuation and Thermophysical Properties of Molten II-VI Compounds

Science.gov (United States)

2003-01-01

The objectives of the project is to conduct ground-based experimental and theoretical research on the structural fluctuations and thermophysical properties of molten II-VI compounds to enhance the basic understanding of the existing flight experiments in microgravity materials science programs and to study the fundamental heterophase fluctuations phenomena in these melts by: 1) Conducting neutron scattering analysis and measuring quantitatively the relevant thermophysical properties of the II-VI melts such as viscosity, electrical conductivity, thermal diffusivity and density as well as the relaxation characteristics of these properties to advance the understanding of the structural properties and the relaxation phenomena in these melts and 2) Performing theoretical analyses on the melt systems to interpret the experimental results. All the facilities required for the experimental measurements have been procured, installed and tested. A relaxation phenomenon, which shows a slow drift of the measured thermal conductivity toward the equilibrium value after cooling of the sample, was observed for the first time. An apparatus based on the transient torque induced by a rotating magnetic field has been developed to determine the viscosity and electrical conductivity of semiconducting liquids. Viscosity measurements on molten tellurium showed similar relaxation behavior as the measured diffusivity. Neutron scattering experiments were performed on the HgTe and HgZnTe melts and the results on pair distribution showed better resolution than previous reported.

Queues and Lévy fluctuation theory

CERN Document Server

Dębicki, Krzysztof

2015-01-01

The book provides an extensive introduction to queueing models driven by Lévy-processes as well as a systematic account of the literature on Lévy-driven queues. The objective is to make the reader familiar with the wide set of probabilistic techniques that have been developed over the past decades, including transform-based techniques, martingales, rate-conservation arguments, change-of-measure, importance sampling, and large deviations. On the application side, it demonstrates how Lévy traffic models arise when modelling current queueing-type systems (as communication networks) and includes applications to finance. Queues and Lévy Fluctuation Theory will appeal to graduate/postgraduate students and researchers in mathematics, computer science, and electrical engineering. Basic prerequisites are probability theory and stochastic processes.

Frequency Inertia Response Control of SCESS-DFIG under Fluctuating Wind Speeds Based on Extended State Observers

Directory of Open Access Journals (Sweden)

Dongyang Sun

2018-04-01

Full Text Available Insufficient frequency regulation capability and system inertia reduction are common problems encountered in a power grid with high wind power penetration, mainly due to the reason that the rotor energy in doubly fed induction generators (DFIGs is isolated by the grid side converters (GSCs, and also due to the randomness and intermittence of wind power which are not as stable as traditional thermal power sources. In this paper, the frequency inertia response control of a DFIG system under variable wind speeds was investigated. First, a DFIG system topology with rotor-side supercapacitor energy storage system (SCESS-DFIG was introduced. Then a control strategy for frequency inertia response of SCESS-DFIG power grid under fluctuating wind speed was designed, with two extended state observers (ESOs which estimate the mechanical power captured by the DFIG and the required inertia response power at the grid frequency drops, respectively. Based on one inconstant wind speed model and the SCESS-DFIG system model adopting the control strategy established, one power grid system consisting of three SCESS-DFIGs with different wind speed trends and a synchronous generator was simulated. The simulation results verified the effectiveness of the SCESS-DFIG system structure and the control strategy proposed.

Small Signal Stability Improvement of Power Systems Using Optimal Load Responses in Competitive Electricity Markets

DEFF Research Database (Denmark)

Hu, Weihao; Su, Chi; Chen, Zhe

2011-01-01

Since the hourly spot market price is available one day ahead in Denmark, the price could be transferred to the consumers and they may shift some of their loads from high price periods to the low price periods in order to save their energy costs. The optimal load response to an electricity price...... price is proposed. A 17-bus power system with high wind power penetrations, which resembles the Eastern Danish power system, is chosen as the study case. Simulation results show that the optimal load response to electricity prices is an effective measure to improve the small signal stability of power...... for demand side management generates different load profiles and may provide an opportunity to improve the small signal stability of power systems with high wind power penetrations. In this paper, the idea of power system small signal stability improvement by using optimal load response to the electricity...

Spontaneous magnetic fluctuations and collisionless regulation of the Earth's plasma sheet

Science.gov (United States)

Moya, P. S.; Espinoza, C.; Stepanova, M. V.; Antonova, E. E.; Valdivia, J. A.

2017-12-01

Even in the absence of instabilities, plasmas often exhibit inherent electromagnetic fluctuations which are present due to the thermal motion of charged particles, sometimes called thermal (quasi-thermal) noise. One of the fundamental and challenging problems of laboratory, space, and astrophysical plasma physics is the understanding of the relaxation processes of nearly collisionless plasmas, and the resultant state of electromagnetic plasma turbulence. The study of thermal fluctuations can be elegantly addressed by using the Fluctuation-Dissipation Theorem that describes the average amplitude of the fluctuations through correlations of the linear response of the media with the perturbations of the equilibrium state (the dissipation). Recently, it has been shown that solar wind plasma beta and temperature anisotropy observations are bounded by kinetic instabilities such as the ion cyclotron, mirror, and firehose instabilities. The magnetic fluctuations observed within the bounded area are consistent with the predictions of the Fluctuation-Dissipation theorem even far below the kinetic instability thresholds, with an enhancement of the fluctuation level near the thresholds. Here, for the very first time, using in-situ magnetic field and plasma data from the THEMIS spacecraft, we show that such regulation also occurs in the Earth's plasma sheet at the ion scales and that, regardless of the clear differences between the solar wind and the magnetosphere environments, spontaneous fluctuation and their collisionless regulation seem to be fundamental features of space and astrophysical plasmas, suggesting the universality of the processes.

Study of thermal - hydraulic sensors signal fluctuations in PWR

International Nuclear Information System (INIS)

Hennion, F.

1987-10-01

This thesis deals with signal fluctuations of thermal-hydraulic sensors in the main coolant primary of a pressurized water reactor. The aim of this work is to give a first response about the potentiality of use of these noise signals for the functionning monitoring. Two aspects have been studied: - the modelisation of temperature fluctuations of core thermocouples, by a Monte-Carlo method, gives the main characteristics of these signals and their domain of application. - the determination of eigenfrequency in the primary by an acoustic representation could permit the monitoring of local and global thermo-hydraulic conditions [fr

Assessing long-term effects of demand response policies in wholesale electricity markets

International Nuclear Information System (INIS)

Cepeda, Mauricio; Saguan, Marcelo

2014-05-01

This paper deals with the practical problems related to long-term issues in electricity markets in the presence of demand response development. Different policies have been implemented around the world aiming to develop demand response potential. Externalities, in particular the CO_2 externality, have been one of the key elements in the debate on the effectiveness of different policies regarding demand response development. Policy makers have several options to deal with this externality. The most direct one is to correct the externality by setting a CO_2 price at a level that corresponds to the cost to society of the corresponding CO_2 emissions. One alternative solution could be to subsidize carbon-free technologies as demand response. In this paper we examine potential long-term impacts of these two policies. We rely on a long-term market simulation model that characterizes expansion decisions in a competitive regime. We test for each policy two different scenarios regarding the possibility of internalization of the CO_2 externality. The results show that differences in development policies affect both investments and social costs in the wholesale electricity market and confirm previous findings that a market-driven development of demand response with the internalization of the CO_2 externality is the most efficient approach. (authors)

The electric dipole response of neutron rich tin isotopes

Energy Technology Data Exchange (ETDEWEB)

Horvat, Andrea; Aumann, Thomas; Rossi, Dominic; Schindler, Fabia [Institut fuer Kernphysik, TU Darmstadt (Germany); Boretzky, Konstanze [GSI Helmholzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Johansen, Jacob [Aarhus University (Denmark); Schrock, Philipp [The University of Tokyo (Japan); Collaboration: R3B-Collaboration

2016-07-01

Studies of the dipole response in medium heavy and heavy neutron rich nuclei reveal valuable information about the isospin dependence of the nuclear equation of state. Therefore an experimental campaign investigating both the electric dipole response via Coulomb excitation and neutron removal along the tin isotope chain ({sup 124-134}Sn) has been carried out at the R3B (Reactions with Relativistic Radioactive Beams) setup at GSI (Helmholtzzentrum fuer Schwerionenforschung) for which the analysis is ongoing. The E1 response was induced via relativistic Coulomb scattering by a lead target in inverse kinematics, and calls for a kinematically complete determination of all reaction products in order to reconstruct the excitation energy by means of the invariant mass method. The goal is to obtain the Coulomb excitation cross section up to the adiabatic cut-off energy, covering the giant dipole resonance (GDR) range.

Local electric stimulation causes conducted calcium response in rat interlobular arteries

DEFF Research Database (Denmark)

Salomonsson, Max; Gustafsson, Finn; Andreasen, Ditte

2002-01-01

microscope. Local electrical pulse stimulation (200 ms, 100 V) was administered by means of an NaCl-filled microelectrode (0.7-1 M(Omega)) juxtaposed to one end of the vessel. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured with an image system at a site approximately 500 microm from......The purpose of the present study was to investigate the conducted Ca(2+) response to local electrical stimulation in isolated rat interlobular arteries. Interlobular arteries were isolated from young Sprague-Dawley rats, loaded with fura 2, and attached to pipettes in a chamber on an inverted...

Managing electrical demand through difficult periods: California's experience with demand response

International Nuclear Information System (INIS)

Wikler, G.; Ghosh, D.Ph.D.

2010-01-01

This paper provides a brief overview of California's electricity situation and the relevance of Demand Response (DR) in addressing some of the challenges faced by the State's electricity system. It then discusses California's experience with DR, market rules that influence what role DR plays and attempts to integrate wholesale-retail level program offerings in the State, and some of the key drivers that are likely to enhance the role of DR. Lastly, the paper identifies some of the key challenges facing implementers of DR programs and discusses how many of those challenges could potentially be overcome. (authors)

Transition countries in the light of electricity production

International Nuclear Information System (INIS)

Kolin, I.

2000-01-01

The fall of the Berlin Wall in 1989 could be closely considered as the beginning of transition in many countries. during this period, lasting for about ten years, unavoidable fluctuations and stoppages caused degradation of electricity production and economic decline as well. This can be mathematically evaluated by means of equation for electricity production, valid before the fall of the Berlin Wall. However, electricity decrease has not been the same in all the countries. Therefore, in order to investigate and evaluate the transition process in the light of electricity production, eight transition states, including croatia, are analysed and mutually compared. (author)

Probe branes thermalization in external electric and magnetic fields

International Nuclear Information System (INIS)

Ali-Akbari, M.; Ebrahim, H.; Rezaei, Z.

2014-01-01

We study thermalization on rotating probe branes in AdS 5 ×S 5 background in the presence of constant external electric and magnetic fields. In the AdS/CFT framework this corresponds to thermalization in the flavour sector in field theory. The horizon appears on the worldvolume of the probe brane due to its rotation in one of the sphere directions. For both electric and magnetic fields the behaviour of the temperature is independent of the probe brane dimension. We also study the open string metric and the fluctuations of the probe brane in such a set-up. We show that the temperatures obtained from open string metric and observed by the fluctuations are larger than the one calculated from the induced metric

Some fundamental aspects of fluctuations and coherence in charged-particle beams in storage rings

International Nuclear Information System (INIS)

Chattopadhyay, S.

1984-01-01

A conceptual survey and exposition is presented of some fundamental aspects of fluctuations and coherence, as well as the interplay between the two, in coasting charged-particle beams - both continuous and bunched - in storage rings. A detailed study is given of the spectral properties of the incoherent phase-space Schottky fluctuations, their propagation as waves in the beam, and the analytic complex coherent beam electromagnetic response or transfer function. The modification or distortion of these by collective interactions is examined in terms of simple regeneration mechanisms. Collective or coherent forces in the beam-storage-ring system are described by defining suitable impedance functions or propagators, and a brief discussion of the coherent collective modes and their stability is provided, including a general and rigorous description of the Nyquist stability criterion. The nature of the critical fluctuations near an instability threshold is explored. The concept of Landau damping and its connection with phase-mixing within the beam is outlined. The important connection between the incoherent fluctuations and the beam response, namely the Fluctuation-Dissipation relation, is revealed. A brief discussion is given of the information degrees of freedom, and effective temperature of the fluctuation signals. Appendices provide a short resume of some general aspects of various interactions in a charged-particle beam-environment system in a storage ring and a general introduction to kinetic theory as applied to particle beams. (orig.)

On spurious detection of linear response and misuse of the fluctuation-dissipation theorem in finite time series

Science.gov (United States)

Gottwald, Georg A.; Wormell, J. P.; Wouters, Jeroen

2016-09-01

Using a sensitive statistical test we determine whether or not one can detect the breakdown of linear response given observations of deterministic dynamical systems. A goodness-of-fit statistics is developed for a linear statistical model of the observations, based on results for central limit theorems for deterministic dynamical systems, and used to detect linear response breakdown. We apply the method to discrete maps which do not obey linear response and show that the successful detection of breakdown depends on the length of the time series, the magnitude of the perturbation and on the choice of the observable. We find that in order to reliably reject the assumption of linear response for typical observables sufficiently large data sets are needed. Even for simple systems such as the logistic map, one needs of the order of 106 observations to reliably detect the breakdown with a confidence level of 95 %; if less observations are available one may be falsely led to conclude that linear response theory is valid. The amount of data required is larger the smaller the applied perturbation. For judiciously chosen observables the necessary amount of data can be drastically reduced, but requires detailed a priori knowledge about the invariant measure which is typically not available for complex dynamical systems. Furthermore we explore the use of the fluctuation-dissipation theorem (FDT) in cases with limited data length or coarse-graining of observations. The FDT, if applied naively to a system without linear response, is shown to be very sensitive to the details of the sampling method, resulting in erroneous predictions of the response.

The fluctuation-dissipation theorem for stochastic kinetics—Implications on genetic regulations

Energy Technology Data Exchange (ETDEWEB)

Yan, Ching-Cher Sanders [Institute of Chemistry, Academia Sinica, 128, Section 2, Academia Road, Nankang, Taipei 115, Taiwan (China); Hsu, Chao-Ping, E-mail: cherri@chem.sinica.edu.tw [Institute of Chemistry, Academia Sinica, 128, Section 2, Academia Road, Nankang, Taipei 115, Taiwan (China); Genome and Systems Biology Degree Program, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 106, Taiwan (China)

2013-12-14

The Fluctuation-Dissipation theorem (FDT) connects the “memory” in the fluctuation in equilibrium to the response of a system after a perturbation, which has been a fundamental ground in many branches of physics. When viewing a cell as a stochastic biochemical system, the cell's response under a perturbation is related to its intrinsic steady-state correlation functions via the FDT, a theorem we derived and present in this work. FDT allows us to use the noise to derive dynamic response and infer dynamic properties in the system. We tested FDT's validity with gene regulation models and found that it is limited to the linear response. For an indirect regulation pathway where unknown components may exist, FDT still works within the linear response region. Thus, FDT may be used for systems with partial knowledge, and it is potentially possible to identify the existence of unobserved components. With FDT, the dynamic response can be composed of steady-state measurements without the complete detailed knowledge for the regulation or kinetics. The response function derived can give important insights into the dynamics and time scales of the system.

Fluctuating Thermodynamics for Biological Processes

Science.gov (United States)

Ham, Sihyun

Because biomolecular processes are largely under thermodynamic control, dynamic extension of thermodynamics is necessary to uncover the mechanisms and driving factors of fluctuating processes. The fluctuating thermodynamics technology presented in this talk offers a practical means for the thermodynamic characterization of conformational dynamics in biomolecules. The use of fluctuating thermodynamics has the potential to provide a comprehensive picture of fluctuating phenomena in diverse biological processes. Through the application of fluctuating thermodynamics, we provide a thermodynamic perspective on the misfolding and aggregation of the various proteins associated with human diseases. In this talk, I will present the detailed concepts and applications of the fluctuating thermodynamics technology for elucidating biological processes. This work was supported by Samsung Science and Technology Foundation under Project Number SSTF-BA1401-13.

Institutional and programmatic suggestions for satisfying public policy responsibilities in a retail competitive electric industry

Energy Technology Data Exchange (ETDEWEB)

Tonn, B.E.; Schweitzer, M. [Oak Ridge National Lab., TN (United States)

1997-01-01

The emergence of retail competition in the US electric power industry places at risk various environmental and social programmes such as demand side management, low income programmes and renewable energy. This paper presents institutional and programmatic suggestions for satisfying these kinds of public policy responsibilities in a disintegrated industry. Suggestions include customer owned electricity franchises, electricity facility siting marketplaces, electric industry foresight councils, model systems programmes, integrated social services programmes, collaborative electric service programmes, ISO standards and portfolio standards. These recommendations would be funded by a national transmission charge, a state level distribution charge and franchise level sales taxes, to be paid by transmission organizations, distribution organizations and electricity consumers, respectively. (author)

The temporal spectrum of adult mosquito population fluctuations: conceptual and modeling implications.

Directory of Open Access Journals (Sweden)

Yun Jian

Full Text Available An improved understanding of mosquito population dynamics under natural environmental forcing requires adequate field observations spanning the full range of temporal scales over which mosquito abundance fluctuates in natural conditions. Here we analyze a 9-year daily time series of uninterrupted observations of adult mosquito abundance for multiple mosquito species in North Carolina to identify characteristic scales of temporal variability, the processes generating them, and the representativeness of observations at different sampling resolutions. We focus in particular on Aedes vexans and Culiseta melanura and, using a combination of spectral analysis and modeling, we find significant population fluctuations with characteristic periodicity between 2 days and several years. Population dynamical modelling suggests that the observed fast fluctuations scales (2 days-weeks are importantly affected by a varying mosquito activity in response to rapid changes in meteorological conditions, a process neglected in most representations of mosquito population dynamics. We further suggest that the range of time scales over which adult mosquito population variability takes place can be divided into three main parts. At small time scales (indicatively 2 days-1 month observed population fluctuations are mainly driven by behavioral responses to rapid changes in weather conditions. At intermediate scales (1 to several month environmentally-forced fluctuations in generation times, mortality rates, and density dependence determine the population characteristic response times. At longer scales (annual to multi-annual mosquito populations follow seasonal and inter-annual environmental changes. We conclude that observations of adult mosquito populations should be based on a sub-weekly sampling frequency and that predictive models of mosquito abundance must include behavioral dynamics to separate the effects of a varying mosquito activity from actual changes in the

Thermodynamic theory of equilibrium fluctuations

International Nuclear Information System (INIS)

Mishin, Y.

2015-01-01

The postulational basis of classical thermodynamics has been expanded to incorporate equilibrium fluctuations. The main additional elements of the proposed thermodynamic theory are the concept of quasi-equilibrium states, a definition of non-equilibrium entropy, a fundamental equation of state in the entropy representation, and a fluctuation postulate describing the probability distribution of macroscopic parameters of an isolated system. Although these elements introduce a statistical component that does not exist in classical thermodynamics, the logical structure of the theory is different from that of statistical mechanics and represents an expanded version of thermodynamics. Based on this theory, we present a regular procedure for calculations of equilibrium fluctuations of extensive parameters, intensive parameters and densities in systems with any number of fluctuating parameters. The proposed fluctuation formalism is demonstrated by four applications: (1) derivation of the complete set of fluctuation relations for a simple fluid in three different ensembles; (2) fluctuations in finite-reservoir systems interpolating between the canonical and micro-canonical ensembles; (3) derivation of fluctuation relations for excess properties of grain boundaries in binary solid solutions, and (4) derivation of the grain boundary width distribution for pre-melted grain boundaries in alloys. The last two applications offer an efficient fluctuation-based approach to calculations of interface excess properties and extraction of the disjoining potential in pre-melted grain boundaries. Possible future extensions of the theory are outlined.

Manipulation of positron orbits in a dipole magnetic field with fluctuating electric fields

Science.gov (United States)

Saitoh, H.; Horn-Stanja, J.; Nißl, S.; Stenson, E. V.; Hergenhahn, U.; Pedersen, T. Sunn; Singer, M.; Dickmann, M.; Hugenschmidt, C.; Stoneking, M. R.; Danielson, J. R.; Surko, C. M.

2018-01-01

We report the manipulation of positron orbits in a toroidal dipole magnetic field configuration realized with electric fields generated by segmented electrodes. When the toroidal circulation motion of positrons in the dipole field is coupled with time-varying electric fields generated by azimuthally segmented outer electrodes, positrons undergo oscillations of their radial positions. This enables quick manipulation of the spatial profiles of positrons in a dipole field trap by choosing appropriate frequency, amplitude, phase, and gating time of the electric fields. According to numerical orbit analysis, we applied these electric fields to positrons injected from the NEPOMUC slow positron facility into a prototype dipole field trap experiment with a permanent magnet. Measurements with annihilation γ-rays clearly demonstrated the efficient compression effects of positrons into the strong magnetic field region of the dipole field configuration. This positron manipulation technique can be used as one of essential tools for future experiments on the formation of electron-positron plasmas.

Neutral Beam Source and Target Plasma for Development of a Local Electric Field Fluctuation Diagnostic

Science.gov (United States)

Bakken, M. R.; Burke, M. G.; Fonck, R. J.; Lewicki, B. T.; Rhodes, A. T.; Winz, G. R.

2016-10-01

A new diagnostic measuring local E-> (r , t) fluctuations is being developed for plasma turbulence studies in tokamaks. This is accomplished by measuring fluctuations in the separation of the π components in the Hα motional Stark spectrum. Fluctuations in this separation are expected to be Ẽ / ẼEMSE 10-3EMSE 10-3 . In addition to a high throughput, high speed spectrometer, the project requires a low divergence (Ω 0 .5°) , 80 keV, 2.5 A H0 beam and a target plasma test stand. The beam employs a washer-stack arc ion source to achieve a high species fraction at full energy. Laboratory tests of the ion source demonstrate repeatable plasmas with Te 10 eV and ne 1.6 ×1017 m-3, sufficient for the beam ion optics requirements. Te and ne scalings of the ion source plasma are presented with respect to operational parameters. A novel three-phase resonant converter power supply will provide 6 mA/cm2 of 80 keV H0 at the focal plane for pulse lengths up to 15 ms, with low ripple δV / 80 keV 0.05 % at 280 kHz. Diagnostic development and validation tests will be performed on a magnetized plasma test stand with 0.5 T field. The test chamber will utilize a washer-stack arc source to produce a target plasma comparable to edge tokamak plasmas. A bias-plate with programmable power supply will be used to impose Ẽ within the target plasma. Work supported by US DOE Grant DE-FG02-89ER53296.

Strategy for improved frequency response of electric double-layer capacitors

Science.gov (United States)

Wada, Yoshifumi; Pu, Jiang; Takenobu, Taishi

2015-10-01

We propose a strategy for improving the response speed of electric double-layer capacitors (EDLCs) and electric double-layer transistors (EDLTs), based on an asymmetric structure with differently sized active materials and gate electrodes. We validate the strategy analytically by a classical calculation and experimentally by fabricating EDLCs with asymmetric Au electrodes (1:50 area ratio and 7.5 μm gap distance). The performance of the EDLCs is compared with that of conventional symmetric EDLCs. Our strategy dramatically improved the cut-off frequency from 14 to 93 kHz and this improvement is explained by fast charging of smaller electrodes. Therefore, this approach is particularly suitable to EDLTs, potentially expanding the applicability to medium speed (kHz-MHz) devices.

Analysis of residential, industrial and commercial sector responses to potential electricity supply constraints in the 1990s

Energy Technology Data Exchange (ETDEWEB)

Fisher, Z.J.; Fang, J.M.; Lyke, A.J.; Krudener, J.R.

1986-09-01

There is considerable debate over the ability of electric generation capacity to meet the growing needs of the US economy in the 1990s. This study provides new perspective on that debate and examines the possibility of power outages resulting from electricity supply constraints. Previous studies have focused on electricity supply growth, demand growth, and on the linkages between electricity and economic growth. This study assumes the occurrence of electricity supply shortfalls in the 1990s and examines the steps that homeowners, businesses, manufacturers, and other electricity users might take in response to electricity outages.

Introducing a demand-based electricity distribution tariff in the residential sector: Demand response and customer perception

International Nuclear Information System (INIS)

Bartusch, Cajsa; Wallin, Fredrik; Odlare, Monica; Vassileva, Iana; Wester, Lars

2011-01-01

Increased demand response is essential to fully exploit the Swedish power system, which in turn is an absolute prerequisite for meeting political goals related to energy efficiency and climate change. Demand response programs are, nonetheless, still exceptional in the residential sector of the Swedish electricity market, one contributory factor being lack of knowledge about the extent of the potential gains. In light of these circumstances, this empirical study set out with the intention of estimating the scope of households' response to, and assessing customers' perception of, a demand-based time-of-use electricity distribution tariff. The results show that households as a whole have a fairly high opinion of the demand-based tariff and act on its intrinsic price signals by decreasing peak demand in peak periods and shifting electricity use from peak to off-peak periods. - Highlights: → Households are sympathetic to demand-based tariffs, seeing as they relate to environmental issues. → Households adjust their electricity use to the price signals of demand-based tariffs. → Demand-based tariffs lead to a shift in electricity use from peak to off-peak hours. → Demand-based tariffs lead to a decrease in maximum demand in peak periods. → Magnitude of these effects increases over time.

Fluctuation-Driven Transport in Biological Nanopores. A 3D Poisson–Nernst–Planck Study

Directory of Open Access Journals (Sweden)

Marcel Aguilella-Arzo

2017-03-01

Full Text Available Living systems display a variety of situations in which non-equilibrium fluctuations couple to certain protein functions yielding astonishing results. Here we study the bacterial channel OmpF under conditions similar to those met in vivo, where acidic resistance mechanisms are known to yield oscillations in the electric potential across the cell membrane. We use a three-dimensional structure-based theoretical approach to assess the possibility of obtaining fluctuation-driven transport. Our calculations show that remarkably high voltages would be necessary to observe the actual transport of ions against their concentration gradient. The reasons behind this are the mild selectivity of this bacterial pore and the relatively low efficiencies of the oscillating signals characteristic of membrane cells (random telegraph noise and thermal noise.

Methods of Using a Magnetic Field Response Sensor Within Closed, Electrically Conductive Containers

Science.gov (United States)

Woodward, Stanley E.; Taylor, Bryant D.

2010-01-01

Magnetic field response sensors are a class of sensors that are powered via oscillating magnetic fields, and when electrically active, respond with their own magnetic fields with attributes dependent upon the magnitude of the physical quantity being measured. A magnetic field response recorder powers and interrogates the magnetic sensors [see Magnetic-Field-Response Measurement- Acquisition System, NASA Tech Briefs Vol. 30, No, 6 (June 2006, page 28)]. Electrically conductive containers have low transmissivity for radio frequency (RF) energy and thus present problems for magnetic field response sensors. It is necessary in some applications to have a magnetic field response sensor s capacitor placed in these containers. Proximity to conductive surfaces alters the inductance and capacitance of the sensors. As the sensor gets closer to a conductive surface, the electric field and magnetic field energy of the sensor is reduced due to eddy currents being induced in the conductive surface. Therefore, the capacitors and inductors cannot be affixed to a conductive surface or embedded in a conductive material. It is necessary to have a fixed separation away from the conductive material. The minimum distance for separation is determined by the desired sensor response signal to noise ratio. Although the inductance is less than what it would be if it were not in proximity to the conductive surface, the inductance is fixed. As long as the inductance is fixed, all variations of the magnetic field response are due to capacitance changes. Numerous variations of inductor mounting can be utilized, such as providing a housing that provides separation from the conductive material as well as protection from impact damage. The sensor can be on the same flexible substrate with a narrow throat portion of the sensor between the inductor and the capacitor, Figure 1. The throat is of sufficient length to allow the capacitor to be appropriately placed within the container and the inductor

Influence of temperature fluctuations on equilibrium ice sheet volume

Directory of Open Access Journals (Sweden)

T. B. Mikkelsen

2018-01-01

Full Text Available Forecasting the future sea level relies on accurate modeling of the response of the Greenland and Antarctic ice sheets to changing temperatures. The surface mass balance (SMB of the Greenland Ice Sheet (GrIS has a nonlinear response to warming. Cold and warm anomalies of equal size do not cancel out and it is therefore important to consider the effect of interannual fluctuations in temperature. We find that the steady-state volume of an ice sheet is biased toward larger size if interannual temperature fluctuations are not taken into account in numerical modeling of the ice sheet. We illustrate this in a simple ice sheet model and find that the equilibrium ice volume is approximately 1 m SLE (meters sea level equivalent smaller when the simple model is forced with fluctuating temperatures as opposed to a stable climate. It is therefore important to consider the effect of interannual temperature fluctuations when designing long experiments such as paleo-spin-ups. We show how the magnitude of the potential bias can be quantified statistically. For recent simulations of the Greenland Ice Sheet, we estimate the bias to be 30 Gt yr−1 (24–59 Gt yr−1, 95 % credibility for a warming of 3 °C above preindustrial values, or 13 % (10–25, 95 % credibility of the present-day rate of ice loss. Models of the Greenland Ice Sheet show a collapse threshold beyond which the ice sheet becomes unsustainable. The proximity of the threshold will be underestimated if temperature fluctuations are not taken into account. We estimate the bias to be 0.12 °C (0.10–0.18 °C, 95 % credibility for a recent estimate of the threshold. In light of our findings it is important to gauge the extent to which this increased variability will influence the mass balance of the ice sheets.

Non-Gaussian conductivity fluctuations in semiconductors

International Nuclear Information System (INIS)

Melkonyan, S.V.

2010-01-01

A theoretical study is presented on the statistical properties of conductivity fluctuations caused by concentration and mobility fluctuations of the current carriers. It is established that mobility fluctuations result from random deviations in the thermal equilibrium distribution of the carriers. It is shown that mobility fluctuations have generation-recombination and shot components which do not satisfy the requirements of the central limit theorem, in contrast to the current carrier's concentration fluctuation and intraband component of the mobility fluctuation. It is shown that in general the mobility fluctuation consist of thermal (or intraband) Gaussian and non-thermal (or generation-recombination, shot, etc.) non-Gaussian components. The analyses of theoretical results and experimental data from literature show that the statistical properties of mobility fluctuation and of 1/f-noise fully coincide. The deviation from Gaussian statistics of the mobility or 1/f fluctuations goes hand in hand with the magnitude of non-thermal noise (generation-recombination, shot, burst, pulse noises, etc.).

Fluctuations in quantum chaos

International Nuclear Information System (INIS)

Casati, G.; Chirikov, B.V.

1996-01-01

Various fluctuations in quantum systems with discrete spectrum are discussed, including recent unpublished results. Open questions and unexplained peculiarities of quantum fluctuations are formulated [ru

Electric circuit theory applied electricity and electronics

CERN Document Server

Yorke, R

1981-01-01

Electric Circuit Theory provides a concise coverage of the framework of electrical engineering. Comprised of six chapters, this book emphasizes the physical process of electrical engineering rather than abstract mathematics. Chapter 1 deals with files, circuits, and parameters, while Chapter 2 covers the natural and forced response of simple circuit. Chapter 3 talks about the sinusoidal steady state, and Chapter 4 discusses the circuit analysis. The fifth chapter tackles frequency response of networks, and the last chapter covers polyphase systems. This book will be of great help to electrical

D.C. electrical conductivity measurements on ADP single crystals ...

Indian Academy of Sciences (India)

Unknown

Impurity added ADP crystals; density; electrical conductivity measurements. 1. Introduction ... determined by the intrinsic defects caused by thermal fluctuations in the ... beaker (corning glass vessel) and allowed to equilibrate at the desired ...

Investigation of the spatial variability and possible origins of wind-induced air pressure fluctuations responsible for pressure pumping

Science.gov (United States)

Mohr, Manuel; Laemmel, Thomas; Maier, Martin; Zeeman, Matthias; Longdoz, Bernard; Schindler, Dirk

2017-04-01

The exchange of greenhouse gases between the soil and the atmosphere is highly relevant for the climate of the Earth. Recent research suggests that wind-induced air pressure fluctuations can alter the soil gas transport and therefore soil gas efflux significantly. Using a newly developed method, we measured soil gas transport in situ in a well aerated forest soil. Results from these measurements showed that the commonly used soil gas diffusion coefficient is enhanced up to 30% during periods of strong wind-induced air pressure fluctuations. The air pressure fluctuations above the forest floor are only induced at high above-canopy wind speeds (> 5 m s-1) and lie in the frequency range 0.01-0.1 Hz. Moreover, the amplitudes of air pressure fluctuations in this frequency range show a clear quadratic dependence on mean above-canopy wind speed. However, the origin of these wind-induced pressure fluctuations is still unclear. Airflow measurements and high-precision air pressure measurements were conducted at three different vegetation-covered sites (conifer forest, deciduous forest, grassland) to investigate the spatial variability of dominant air pressure fluctuations, their origin and vegetation-dependent characteristics. At the conifer forest site, a vertical profile of air pressure fluctuations was measured and an array consisting of five pressure sensors were installed at the forest floor. At the grassland site, the air pressure measurements were compared with wind observations made by ground-based LIDAR and spatial temperature observations from a fibre-optic sensing network (ScaleX Campaign 2016). Preliminary results show that at all sites the amplitudes of relevant air pressure fluctuations increase with increasing wind speed. Data from the array measurements reveal that there are no time lags between the air pressure signals of different heights, but a time lag existed between the air pressure signals of the sensors distributed laterally on the forest floor

The value of online information for demand response in Walrasian electricity markets

NARCIS (Netherlands)

F.N. Claessen (Felix); B.J. Liefers (Bart); M. Kaisers (Michael); J.A. La Poutré (Han)

2015-01-01

textabstractSmart energy systems integrate renewables and demand response. Most European electricity markets coordinate the resulting time-varying flexibility in demand and supply by organising day-ahead trade with Walrasian mechanisms, using simultaneous call auctions and sealed bids. These

Anode spot patterns and fluctuations in an atmospheric-pressure glow discharge in helium

International Nuclear Information System (INIS)

Arkhipenko, V I; Safronau, Y A; Simonchik, L V; Tsuprik, I M; Callegari, Th

2013-01-01

Oscillations of the main parameters (voltage on electrodes, potential, light intensity and discharge current) in a dc atmospheric-pressure glow discharge in helium are investigated in a range of currents from milliamperes to several amperes. It is established that these oscillations are connected with the existence of anode spots. In the case of a single spot, fluctuations of discharge light intensity are observed when the supply voltage exceeds the breakdown voltage for the interelectrode gap. At the same time, voltage fluctuations have the form of relaxation oscillations with a frequency that depends on the electrical parameters of the external circuit. With an increase in discharge gap and current, the number of spots increases. They form a stable structure, and the fluctuations of current and voltage stay harmonic. The brightness of the spots seems to be determined by the frequency of their blinking. The amplitude of current fluctuation increases with the increase in discharge current and can be up to 15% of its average value. The frequency of current oscillations, which is about 0.75 MHz at a current of 0.5 A, depends weakly on the discharge gap (it varies within ±10% for the gap interval from 1 to 10 mm). The oscillation frequency is maximal (about 0.85 MHz) at a current of about 0.4 A. At higher currents (2–4 A, depending on the discharge gap), the fluctuations disappear when a contraction of the anode region into one anode spot occurs. (paper)

Load variation effects on the pressure fluctuations exerted on a Kaplan turbine runner

International Nuclear Information System (INIS)

Amiri, K; Cervantes, M J; Mulu, B; Raisee, M

2014-01-01

Introduction of intermittent electricity production systems like wind power and solar systems to electricity market together with the consumption-based electricity production resulted in numerous start/stops, load variations and off-design operation of water turbines. The hydropower systems suffer from the varying loads exerted on the stationary and rotating parts of the turbines during load variations which they are not designed for. On the other hand, investigations on part load operation of single regulated turbines, i.e., Francis and propeller, proved the formation of rotating vortex rope (RVR) in the draft tube. The RVR induces oscillating flow both in plunging and rotating modes which results in oscillating force with two different frequencies on the runner blades, bearings and other rotating parts of the turbine. The purpose of this study is to investigate the effect of transient operations on the pressure fluctuations on the runner and mechanism of the RVR formation/mitigation. Draft tube and runner blades of the Porjus U9 model, a Kaplan turbine, were equipped with pressure sensors. The model was run in off-cam mode during different load variation conditions to check the runner performance under unsteady condition. The results showed that the transients between the best efficiency point and the high load happens in a smooth way while transitions to/from the part load, where rotating vortex rope (RVR) forms in the draft tube induces high level of fluctuations with two frequencies on the runner; plunging and rotating mode of the RVR

Load variation effects on the pressure fluctuations exerted on a Kaplan turbine runner

Science.gov (United States)

Amiri, K.; Mulu, B.; Raisee, M.; Cervantes, M. J.

2014-03-01

Introduction of intermittent electricity production systems like wind power and solar systems to electricity market together with the consumption-based electricity production resulted in numerous start/stops, load variations and off-design operation of water turbines. The hydropower systems suffer from the varying loads exerted on the stationary and rotating parts of the turbines during load variations which they are not designed for. On the other hand, investigations on part load operation of single regulated turbines, i.e., Francis and propeller, proved the formation of rotating vortex rope (RVR) in the draft tube. The RVR induces oscillating flow both in plunging and rotating modes which results in oscillating force with two different frequencies on the runner blades, bearings and other rotating parts of the turbine. The purpose of this study is to investigate the effect of transient operations on the pressure fluctuations on the runner and mechanism of the RVR formation/mitigation. Draft tube and runner blades of the Porjus U9 model, a Kaplan turbine, were equipped with pressure sensors. The model was run in off-cam mode during different load variation conditions to check the runner performance under unsteady condition. The results showed that the transients between the best efficiency point and the high load happens in a smooth way while transitions to/from the part load, where rotating vortex rope (RVR) forms in the draft tube induces high level of fluctuations with two frequencies on the runner; plunging and rotating mode of the RVR.

Electric Boiler and Heat Pump Thermo-Electrical Models for Demand Side Management Analysis in Low Voltage Grids

DEFF Research Database (Denmark)

Diaz de Cerio Mendaza, Iker; Bak-Jensen, Birgitte; Chen, Zhe

2013-01-01

The last fifteen years many European countries have integrated large percentage of renewable energy on their electricity generation mix. In Denmark the 21.3% of the electricity consumed nowadays is produced by the wind, and it has planned to be the 50% by 2025. In order to front future challenges...... on the power system control and operation, created by this unstable way of generation, Demand Side Management turns to be a promising solution. The storage capacity from thermo-electric units, like electric boilers and heat pumps, allows operating them with certain freedom. Hence they can be employed under...... certain coordination, to actively respond to the power system fluctuations. The following paper presents two simple thermo-electrical models of an electrical boiler and an air-source CO2 heat pump system. The purpose is using them in low voltage grids analysis to assess their capacity and flexibility...

The Control of Switched Reluctance Motor in Electric Vehicle

Directory of Open Access Journals (Sweden)

Zheng Liu

2014-05-01

Full Text Available The control of SRM was discussed: current chopping control, angle position control. This paper presents an inverter circuit and a fuzzy sliding mode control method to minimize the torque fluctuation and noise of the SRM. Based on the experimental results, Using the inverter circuit and fuzzy sliding mode control method can effectively minimize the torque fluctuation and noise of the SRM, For the switched reluctance motor applications in electric vehicles to provide a theoretical basis.

Nonlinear quenching of current fluctuations in a self-exciting homopolar dynamo

Directory of Open Access Journals (Sweden)

R. Hide

1997-01-01

Full Text Available In the interpretation of geomagnetic polarity reversals with their highly variable frequency over geological time it is necessary, as with other irregularly fluctuating geophysical phenomena, to consider the relative importance of forced contributions associated with changing boundary conditions and of free contributions characteristic of the behaviour of nonlinear systems operating under fixed boundary conditions.  New evidence -albeit indirect- in favour of the likely predominance of forced contributions is provided by the discovery reported here of the possibility of complete quenching by nonlineax effects of current fluctuations in a self-exciting homopolar dynamo with its single Faraday disk driven into rotation with angular speed y(τ (where τ denotes time by a steady applied couple.  The armature of an electric motor connected in series with the coil of the dynamo is driven into rotation' with angular speed z(τ by a torque xf (x due to Lorentz forces associated with the electric current x(τ in the system (just as certain parts of the spectrum of eddies within the liquid outer core are generated largely by Lorentz forces associated with currents generated by the self-exciting magnetohydrodynamic (MHD geodynamo.   The discovery is based on bifurcation analysis supported by computational studies of the following (mathematically novel autonomous set of nonlinear ordinary differential equations: dx/dt = x(y - 1 - βzf(x, dy/dt = α(1 - x² - κy, dz/dt = xf (x -λz,          where f (x = 1 - ε + εσx, in cases when the dimensionless parameters (α, β, κ, λ, σ are all positive and 0 ≤ ε ≤ 1. Within those regions of (α, β, κ, λ, σ parameter space where the applied couple, as measured by α, is strong enough for persistent dynamo action (i.e. x ≠ 0 to occur at all, there are in general extensive regions where x(τ exhibits large amplitude regular or irregular (chaotic fluctuations.  But these fluctuating r

Electric discharge microplasmas generated in highly fluctuating fluids: Characteristics and application to the synthesis of molecular diamond

Science.gov (United States)

Stauss, Sven

2014-10-01

Plasma-based fabrication of novel nanomaterials and nanostructures is paramount for the development of next-generation electronic devices and for green energy applications. In particular, controlling the interactions between plasmas and materials interfaces, and the plasma fluctuations are crucial for further development of plasma-based processes and bottom-up growth of nanomaterials. Discharge microplasmas generated in supercritical fluids represent a special class of high-pressure plasmas, where fluctuations on the molecular scale influence the discharge properties and the possible bottom-up growth of nanomaterials. In the first part of the talk, we will discuss an anomaly observed for microplasmas generated near the critical point, a local decrease in the breakdown voltage, which has been observed for both molecular and monoatomic gases. This anomalous behavior is suggested to be caused by the concomitant decrease of the ionization potential due to the formation of clusters near the critical point, and the formation of extended electron mean free paths induced by the high-density fluctuation near the critical point. We will also show that when generating microplasma discharges close to the critical point, that the high-density fluctuation of the supercritical fluid persists. In the second part of the presentation, we will first introduce the basic properties of diamondoids and their potential for application in many different fields - biotechnology, medicine, opto- and nanoelectronics - before discussing their synthesis by microplasmas generated inside both conventional batch-type and continuous flow reactors, using the smallest diamondoid, adamantane, as a precursor and seed. Finally we show that one possible growth mechanism of larger diamondoids from smaller ones consists in the repeated abstraction of hydrogen terminations and the addition of methyl radicals. Supported financially in part by Grant No. 23760688 and Grant No. 21110002 from the Ministry of

Fluorescence fluctuation spectroscopy (FFS)

CERN Document Server

Tetin, Sergey

2012-01-01

This new volume of Methods in Enzymology continues the legacy of this premier serial with quality chapters authored by leaders in the field. This volume covers fluorescence fluctuation spectroscopy and includes chapters on such topics as Förster resonance energy transfer (fret) with fluctuation algorithms, protein corona on nanoparticles by FCS, and FFS approaches to the study of receptors in live cells. Continues the legacy of this premier serial with quality chapters authored by leaders in the field Covers fluorescence fluctuation spectroscopy Contains chapters on such topics as Förster resonance energy transfer (fret) with fluctuation algorithms, protein corona on nanoparticles by FCS, and FFS approaches to the study of receptors in live cells.

Economic demand response model in liberalised electricity markets with respect to flexibility of consumers

DEFF Research Database (Denmark)

Sharifi, Reza; Anvari-Moghaddam, Amjad; Fathi, S. Hamid

2017-01-01

Before restructuring in the electricity industry, the primary decision-makers of the electricity market were deemed to be power generation and transmission companies, market regulation boards, and power industry regulators. In this traditional structure, consumers were interested in receiving...... electricity at flat rates while paying no attention to the problems of this industry. This attitude was the source of many problems, sometimes leading to collapse of power systems and widespread blackouts. Restructuring of the electricity industry however provided a multitude of solutions to these problems....... The most important solution can be demand response (DR) programs. This paper proposes an economic DR model for residential consumers in liberalized electricity markets to change their consumption pattern from times of high energy prices to other times to maximize their utility functions. This economic...

Electric signalling in fruit trees in response to water applications and light-darkness conditions.

Science.gov (United States)

Gurovich, Luis A; Hermosilla, Paulo

2009-02-15

A fundamental property of all living organisms is the generation and conduction of electrochemical impulses throughout their different tissues and organs, resulting from abiotic and biotic changes in environmental conditions. In plants and animals, signal transmission can occur over long and short distances, and it can correspond to intra- and inter-cellular communication mechanisms that determine the physiological behaviour of the organism. Rapid plant and animal responses to environmental changes are associated with electrical excitability and signalling. The same molecules and pathways are used to drive physiological responses, which are characterized by movement (physical displacement) in animals and by continuous growth in plants. In the field of environmental plant electrophysiology, automatic and continuous measurements of electrical potential differences (DeltaEP) between plant tissues can be effectively used to study information transport mechanisms and physiological responses that result from external stimuli on plants. A critical mass of data on electrical behaviour in higher plants has accumulated in the last 5 years, establishing plant neurobiology as the most recent discipline of plant science. In this work, electrical potential differences were monitored continuously using Ag/AgCl microelectrodes, which were inserted 15mm deep into sapwood at various positions in the trunks of several fruit-bearing trees. Electrodes were referenced to an unpolarisable Ag/AgCl microelectrode, which was installed 5cm deep in the soil. Systematic patterns of DeltaEP during day-night cycles and at different conditions of soil water availability are discussed as alternative tools to assess early plant stress conditions. This research relates to the adaptive response of trees to soil water availability and light-darkness cycles.

Risk management and participation planning of electric vehicles in smart grids for demand response

International Nuclear Information System (INIS)

Nezamoddini, Nasim; Wang, Yong

2016-01-01

Demand response (DR) can serve as an effective tool to better balance the electricity demand and supply in the smart grid. It is defined as 'the changes in electricity usage by end-use customers from their normal consumption patterns' in response to pricing and incentive payments. This paper focuses on new opportunities for DR with electric vehicles (EVs). EVs are potential distributed energy resources that support both the grid-to-vehicle and vehicle-to-grid modes. Their participation in the time-based (e.g., time-of-use) and incentive-based (e.g., regulation services) DR programs helps improve the stability and reduce the potential risks to the grid. Smart scheduling of EV charging and discharging activities also supports high penetration of renewables with volatile energy generation. This paper proposes a novel stochastic model from the Independent System Operator's perspective for risk management and participation planning of EVs in the smart grid for DR. The risk factors considered in this paper involve those caused by uncertainties in renewables (wind and solar), load patterns, parking patterns, and transmission lines' reliability. The effectiveness of the model in response to various settings such as the area type (residential, commercial, and industrial), the EV penetration level, and the risk level has been investigated. - Highlights: • We identify new opportunities for demand response (DR) using electric vehicles (EVs). • We integrate EVs in both grid-to-vehicle and vehicle-to-grid modes in smart grids. • EV participation for both time- and incentive-based DR programs are modelled. • We consider uncertainties in renewables, load, parking, and transmission lines. • Model case studies are demonstrated in residential, commercial, and industrial areas.

Electrical connection for aluminium conductors in automotive applications : Prestudy of available solutions for electrical connection methods of aluminium cables

OpenAIRE

Hamedi, Emilia

2017-01-01

Due to increasing weight of electrical component and wiring harnesses in a vehicle contrary to the demand of light constructed vehicles as well as the constantly increasing and fluctuating price of copper compared to aluminium’s stable and far lower price, the use of aluminium conductors as an alternative have been promoted.  This thesis work lay theoretical research of the available methods used for electrical connection of aluminium conductors in order to increase the knowledge about the av...

Electric stimulus duration alters network-mediated responses depending on retinal ganglion cell type

Science.gov (United States)

Im, Maesoon; Werginz, Paul; Fried, Shelley I.

2018-06-01

Objective. To improve the quality of artificial vision that arises from retinal prostheses, it is important to bring electrically-elicited neural activity more in line with the physiological signaling patterns that arise normally in the healthy retina. Our previous study reported that indirect activation produces a closer match to physiological responses in ON retinal ganglion cells (RGCs) than in OFF cells (Im and Fried 2015 J. Physiol. 593 3677-96). This suggests that a preferential activation of ON RGCs would shape the overall retinal response closer to natural signaling. Recently, we found that changes to the rate at which stimulation was delivered could bias responses towards a stronger ON component (Im and Fried 2016a J. Neural Eng. 13 025002), raising the possibility that changes to other stimulus parameters can similarly bias towards stronger ON responses. Here, we explore the effects of changing stimulus duration on the responses in ON and OFF types of brisk transient (BT) and brisk sustained (BS) RGCs. Approach. We used cell-attached patch clamp to record RGC spiking in the isolated rabbit retina. Targeted RGCs were first classified as ON or OFF type by their light responses, and further sub-classified as BT or BS types by their responses to both light and electric stimuli. Spiking in targeted RGCs was recorded in response to electric pulses with durations varying from 5 to100 ms. Stimulus amplitude was adjusted at each duration to hold total charge constant for all experiments. Main results. We found that varying stimulus durations modulated responses differentially for ON versus OFF cells: in ON cells, spike counts decreased significantly with increasing stimulus duration while in OFF cells the changes were more modest. The maximum ratio of ON versus OFF responses occurred at a duration of ~10 ms. The difference in response strength for BT versus BS cells was much larger in ON cells than in OFF cells. Significance. The stimulation rates preferred by

Magnetogastrographic detection of gastric electrical response activity in humans

International Nuclear Information System (INIS)

Irimia, Andrei; Richards, William O; Bradshaw, L Alan

2006-01-01

The detection and characterization of gastric electrical activity has important clinical applications, including the early diagnosis of gastric diseases in humans. In mammals, this phenomenon has two important features: an electrical control activity (ECA) that manifests itself as an electric slow wave (with a frequency of 3 cycles per minute in humans) and an electrical response activity (ERA) that is characterized by spiking potentials during the plateau phase of the ECA. Whereas the ECA has been recorded in humans both invasively and non-invasively (magnetogastrography-MGG), the ERA has never been detected non-invasively in humans before. In this paper, we report on our progress towards the non-invasive detection of ERA from the human stomach using a procedure that involves the application of principal component analysis to MGG recordings, which were acquired in our case from ten normal human patients using a Superconducting QUantum Interference Device (SQUID) magnetometer. Both pre- and post-prandial recordings were acquired for each patient and 20 min of recordings (10 min of pre-prandial and 10 min of post-prandial data) were analysed for each patient. The mean percentage of ECA slow waves that were found to exhibit spikes of suspected ERA origin was 41% and 61% for pre- and post-prandial recordings, respectively, implying a 47% ERA increase post-prandially (P < 0.0001 at a 95% confidence level). The detection of ERA in humans is highly encouraging and points to the possible use of non-invasive ERA recordings as a valuable tool for the study of human gastric disorders

2D image of local density and magnetic fluctuations from line-integrated interferometry-polarimetry measurements.

Science.gov (United States)

Lin, L; Ding, W X; Brower, D L

2014-11-01

Combined polarimetry-interferometry capability permits simultaneous measurement of line-integrated density and Faraday effect with fast time response (∼1 μs) and high sensitivity. Faraday effect fluctuations with phase shift of order 0.05° associated with global tearing modes are resolved with an uncertainty ∼0.01°. For physics investigations, local density fluctuations are obtained by inverting the line-integrated interferometry data. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of the polarimetry data. Reconstructed 2D images of density and magnetic field fluctuations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved.

2D image of local density and magnetic fluctuations from line-integrated interferometry-polarimetry measurements

International Nuclear Information System (INIS)

Lin, L.; Ding, W. X.; Brower, D. L.

2014-01-01

Combined polarimetry-interferometry capability permits simultaneous measurement of line-integrated density and Faraday effect with fast time response (∼1 μs) and high sensitivity. Faraday effect fluctuations with phase shift of order 0.05° associated with global tearing modes are resolved with an uncertainty ∼0.01°. For physics investigations, local density fluctuations are obtained by inverting the line-integrated interferometry data. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of the polarimetry data. Reconstructed 2D images of density and magnetic field fluctuations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved

Atmospheric Electricity Effects of Eastern Mediterranean Dust Storms

Science.gov (United States)

Katz, Shai; Yair, Yoav; Yaniv, Roy; Price, Colin

2016-04-01

We present atmospheric electrical measurements conducted at the Wise Observatory (WO) in Mizpe-Ramon (30035'N, 34045'E) and Mt. Hermon (30024'N, 35051'E), Israel, during two massive and unique dust storms that occurred over the Eastern Mediterranean region on February 10-11 and September 08-12, 2015. The first event transported Saharan dust from Egypt and the Sinai Peninsula in advance of a warm front of a Cyprus low pressure system. In the second event, dust particles were transported from the Syrian desert, which dominates the north-east border with Iraq, through flow associated with a shallow Persian trough system. In both events the concentrations of PM10 particles measured by the air-quality monitoring network of the Israeli Ministry of the Environment in Beer-Sheba reached values > 2200 μg m-3. Aerosol Optical Thickness (AOT) obtained from the AERONET station in Sde-Boker reached values up to 4.0. The gradual intensification of the first event reached peak values on the February 11th > 1200 μg m-3 and an AOT ~ 1.8, while the second dust storm commenced on September 8th with a sharp increase reaching peak values of 2225 μg m-3 and AOT of 4.0. Measurements of the fair weather vertical electric field (Ez) and of the vertical current density (Jz) were conducted continuously with a 1 minute temporal resolution. During the February event, very large fluctuations in the electrical parameters were measured at the WO. The Ez values changed between +1000 and +8000 V m-1 while the Jz fluctuated between -10 and +20 pA m-2 (this is an order of magnitude larger compared to the fair weather current density of ~2 pA m-2. In contrast, during the September event, Ez values registered at WO were between -430 and +10 V m-1 while the Jz fluctuated between -6 and +3 pA m2. For the September event the Hermon site showed Ez and Jz values fluctuating between -460 and +570 V m-1 and -14.5 and +18 pA m-2 respectively. The electric field and current variability, amplitude and the

Fluctuation dynamics in geoelectrical data: an investigation by using multifractal detrended fluctuation analysis

International Nuclear Information System (INIS)

Telesca, Luciano; Colangelo, Gerardo; Lapenna, Vincenzo; Macchiato, Maria

2004-01-01

We analyzed fluctuations in the time dynamics of nonstationary geoelectrical data, recorded in a seismic area of southern Italy, by means of the multifractal detrended fluctuation analysis (MF-DFA). The multifractal character of the signal depends mostly on the different long-range properties for small and large fluctuations. The time variation of indices, denoting the departure from monofractal behaviour, reveals an enhancement of the multifractality of the signal prior seismic occurrences

Imports, exports, and Alberta's transmission system impact on price fluctuation

International Nuclear Information System (INIS)

Johnson, K.

2002-01-01

The roles, responsibilities and objectives of ESBI, a private for-profit company, appointed by the Alberta Government to be the Independent Transmission Administrator in the province, is sketched, prior to a discussion of price volatility in electricity, Alberta interconnections, intertie issues, the economic theory and the reality impact on prices. Given that imports and exports constitute a relatively small proportion of total generation or load in Alberta, price volatility is considered to have been only minimally affected by imports/exports. In contrast, transmission constraints, i.e. the limits on physical capacity of the existing transmission system to accommodate all desired transactions, have significant impact on imports/exports. Factors underlying constraints and price volatility such as uncertainty of generation dispatch, leading to reduced interest to invest, which in turn leads to scarce capacity for imports/exports, and the actions required to reduce uncertainty and address other issues such as congestion management, tariff design and the creation of regional transmission organizations, are also discussed to provide further clarification of the issues. It is suggested that these and other related issues need to be resolved to provide the clarity around transmission access and the tools required to manage price fluctuations

Prediction of Francis Turbine Prototype Part Load Pressure and Output Power Fluctuations with Hydroelectric Model

Science.gov (United States)

Alligné, S.; Nicolet, C.; Béguin, A.; Landry, C.; Gomes, J.; Avellan, F.

2017-04-01

The prediction of pressure and output power fluctuations amplitudes on Francis turbine prototype is a challenge for hydro-equipment industry since it is subjected to guarantees to ensure smooth and reliable operation of the hydro units. The European FP7 research project Hyperbole aims to setup a methodology to transpose the pressure fluctuations induced by the cavitation vortex rope from the reduced scale model to the prototype generating units. A Francis turbine unit of 444MW with a specific speed value of ν = 0.29, is considered as case study. A SIMSEN model of the power station including electrical system, controllers, rotating train and hydraulic system with transposed draft tube excitation sources is setup. Based on this model, a frequency analysis of the hydroelectric system is performed for all technologies to analyse potential interactions between hydraulic excitation sources and electrical components. Three technologies have been compared: the classical fixed speed configuration with Synchronous Machine (SM) and the two variable speed technologies which are Doubly Fed Induction Machine (DFIM) and Full Size Frequency Converter (FSFC).

Optimal pricing of default customers in electrical distribution systems: Effect behavior performance of demand response models

International Nuclear Information System (INIS)

Yusta, J.M.; Khodr, H.M.; Urdaneta, A.J.

2007-01-01

The response of a non-linear mathematical model is analyzed for the calculation of the optimal prices for electricity assuming default customers under different scenarios and using five different mathematical functions for the consumer response: linear, hyperbolic, potential, logarithmic and exponential. The mathematical functions are defined to simulate the hourly changes in the consumer response according to the load level, the price of electricity, and also depending on the elasticity at every hour. The behavior of the optimization model is evaluated separately under two different objective functions: the profit of the electric utility and the social welfare. The optimal prices as well as the served load are calculated for two different operation schemes: in an hourly basis and also assuming a single constant price for the 24 h of the day. Results obtained by the optimization model are presented and compared for the five different consumer load functions. (author)

Strain fluctuations and elastic constants

Energy Technology Data Exchange (ETDEWEB)

Parrinello, M.; Rahman, A.

1982-03-01

It is shown that the elastic strain fluctuations are a direct measure of elastic compliances in a general anisotropic medium; depending on the ensemble in which the fluctuation is measured either the isothermal or the adiabatic compliances are obtained. These fluctuations can now be calculated in a constant enthalpy and pressure, and hence, constant entropy, ensemble due to recent develpments in the molecular dynamics techniques. A calculation for a Ni single crystal under uniform uniaxial 100 tensile or compressive load is presented as an illustration of the relationships derived between various strain fluctuations and the elastic modulii. The Born stability criteria and the behavior of strain fluctuations are shown to be related.

Electric fields in the magnetosphere

International Nuclear Information System (INIS)

Falthammar, C.G.

1989-01-01

Electric field measurements on the satellites GEOS-1, GEOS-2, ISEE-1, and Viking have extended the empirical knowledge of electric fields in space so as to include the outer regions of the magnetosphere. While the measurements confirm some of the theoretically expected properties of the electric fields, they also reveal unexpected features and a high degree of complexity and variability. The existence of a magnetospheric dawn-to-dusk electric field, as expected on the basis of extrapolation from low altitude measurements, is confirmed in an average sense. However, the actual field exhibits large spatial and temporal variations, including strong fields of inductive origin. At the magnetopause, the average (dawn-to-dusk directed) tangential electric field component is typically obscured by irregular fluctuations of larger amplitude. The magnetic-field aligned component of the electric field, which is of particular importance for ionosphere-magnetosphere coupling and for auroral acceleration, is even now very difficult to measure directly. However, the data from electric field measurements provide further support for the conclusion, based on a variety of evidence, that a non-vanishing magnetic-field aligned electric field exists in the auroral acceleration region

Do the seagull terms really survive for the electric polarizability of the nucleon?

International Nuclear Information System (INIS)

Saito, S.

1998-01-01

The seagull terms for the electric polarizability of the nucleon are shown indeed to vanish, if one introduces fluctuations around the Skyrmion configuration, and the origin of the electric polarizability cannot after all be attributed to the seagull terms in the Skyrme model. (orig.)

The Application of Le Chatelier – Brown Principle for Interpretation of the Results of the LongLasting Fluctuations of the Electric Strength in Minor Volumes of Electrolytes

Directory of Open Access Journals (Sweden)

K. V. Glagolev

2015-01-01

Full Text Available The paper discusses a Le Chatelier – Brown principle to describe a balanced state in various physical problems. The Le Chatelier – Brown principle applications are demonstrated in problems of chemical thermodynamics, mechanics, electrodynamics as well as in descriptions of biosphere processes. The paper defines an inverse correlation for the Kullback's measure values of fluctuations of the electric strength in minor volumes of electrolytes on the density of entropy production in the environment. It shows that influence of dissipative processes on isolated electrolytic cell can be described using the Le Chatelier – Brown principle. The correlation coefficient of Kullback's measure values and density of entropy production in transformation of the Sun radiation into the Earth surface thermal radiation is calculated.

Estimating deficit probabilities with price-responsive demand in contract-based electricity markets

International Nuclear Information System (INIS)

Galetovic, Alexander; Munoz, Cristian M.

2009-01-01

Studies that estimate deficit probabilities in hydrothermal systems have generally ignored the response of demand to changing prices, in the belief that such response is largely irrelevant. We show that ignoring the response of demand to prices can lead to substantial over or under estimation of the probability of an energy deficit. To make our point we present an estimation of deficit probabilities in Chile's Central Interconnected System between 2006 and 2010. This period is characterized by tight supply, fast consumption growth and rising electricity prices. When the response of demand to rising prices is acknowledged, forecasted deficit probabilities and marginal costs are shown to be substantially lower

Harvesting electrical energy from torsional thermal actuation driven by natural convection.

Science.gov (United States)

Kim, Shi Hyeong; Sim, Hyeon Jun; Hyeon, Jae Sang; Suh, Dongseok; Spinks, Geoffrey M; Baughman, Ray H; Kim, Seon Jeong

2018-06-07

The development of practical, cost-effective systems for the conversion of low-grade waste heat to electrical energy is an important area of renewable energy research. We here demonstrate a thermal energy harvester that is driven by the small temperature fluctuations provided by natural convection. This harvester uses coiled yarn artificial muscles, comprising well-aligned shape memory polyurethane (SMPU) microfibers, to convert thermal energy to torsional mechanical energy, which is then electromagnetically converted to electrical energy. Temperature fluctuations in a yarn muscle, having a maximum hot-to-cold temperature difference of about 13 °C, were used to spin a magnetic rotor to a peak torsional rotation speed of 3,000 rpm. The electromagnetic energy generator converted the torsional energy to electrical energy, thereby producing an oscillating output voltage of up to 0.81 V and peak power of 4 W/kg, based on SMPU mass.

The theory of electromagnetic wave scattering by density fluctuations in nonequilibrium plasma

International Nuclear Information System (INIS)

Pavlenko, V.N.; Panchenko, V.G.

1993-01-01

Scattering of electromagnetic waves by density fluctuations in a magnetized plasma in the presence of the external pump field is investigated. The spectral density of electron density fluctuations is calculated. The pump wave is supposed to decay into a lower hybrid wave and low frequency oscillations (ion-acoustic wave, modified convective cell and ion-cyclotron wave with ion-temperature anisotropy). When the pump wave amplitude tends to the threshold strength of the electric field, the scattering cross section increases anomalously, i.e. there is the critical opalescence. The differential scattering cross section dependence on the pump amplitude and ion temperature anisotropy is obtained in the region above the parametric instability threshold. For characteristic parameters of fusion and space plasmas it is shown that the pump field terms considerably surmount the thermal noise contribution to the scattering cross section

State Regulatory responses to acid rain: Implications for electric utility operations

International Nuclear Information System (INIS)

Nagelhout, M.

1990-01-01

This article discusses the state regulatory responses to acid rain legislation and how this will affect electric utility operations. Topics discusses include planning and fuel procurement practices, least-cost planning, long-term supply contracts, fuel mix, cogeneration and small power production, qualifying facility contracts, avoided costs, environmental impact, lobbying expense, bill inserts, and forecasting models

Social Corporate Responsibility regarding Household Consumer Satisfaction with the Electric Power Supply Services

Directory of Open Access Journals (Sweden)

Maria-Ana Georgescu

2014-02-01

Full Text Available The issue of the practical manifestation of corporate social responsibility towards consumers is highly important to the socio-economic reality in Romania. The present paper is the result of an investigation carried out in this field and it is distinguished by two aspects. The first aspect is its target audience used for research - household consumers of electricity, who can be called "vulnerable", captive consumers. The second aspect is the specificity of the electricity market. The aim of the research was to study the relationship between corporate social responsibility, instantiated by the quality of services provided by S.C. Electrica S.A. – Electrica Distribution and Supply South Transylvania and the consumers' loyalty towards the company, in case other electricity suppliers emerge. A subsidiary aspect was the generation of a database having an impact on customer retention. We have carried out some quantitative research, based on the survey method, having a sample of 521 household consumers from the Mures County. The study we carried out proves that consumer satisfaction, their degree of satisfaction under different aspects, is a way of gaining their trust on this particular market. Those consumers with a higher degree of trust in the company are more loyal. This will result in reducing migration to another electricity supplier, in the future, when all household consumers become eligible.

Instability and electrical response of small laminar coflow diffusion flames under AC electric fields: Toroidal vortex formation and oscillating and spinning flames

KAUST Repository

Xiong, Yuan; Chung, Suk-Ho; Cha, Min

2016-01-01

Dynamical and electrical responses of a small coflow diffusion flame were investigated by applying a high-voltage alternating current (AC), to a fuel jet nozzle. High-speed imaging and electrical diagnostics were adopted to capture flame dynamics and electrical signals, such as voltage (V ), frequency (f ) and current (I ). In the V -f domain of 0-5kV and 0-5kHz, AC-driven instabilities, resulting in various flame modes such as an oscillation, pinch-off and spinning of flames were identified. Characteristic frequency of each mode was determined and a visualization of near-nozzle flow structures suggested a close causality of initial counter-rotating vortices (inner and outer toroidal vortices - ITV and OTV), to the other observed flame. An axisymmetric ITV shedding was identified within oscillating and pinch-off modes, while asymmetric ITV shedding was identified with the spinning mode. Integrated electric power over several AC periods correlated well with variation in the flame surface area for these instabilities, demonstrating that measured electric power is a potential indicator of combustion instabilities in electric-field-assisted combustion.

Instability and electrical response of small laminar coflow diffusion flames under AC electric fields: Toroidal vortex formation and oscillating and spinning flames

KAUST Repository

Xiong, Yuan

2016-06-24

Dynamical and electrical responses of a small coflow diffusion flame were investigated by applying a high-voltage alternating current (AC), to a fuel jet nozzle. High-speed imaging and electrical diagnostics were adopted to capture flame dynamics and electrical signals, such as voltage (V ), frequency (f ) and current (I ). In the V -f domain of 0-5kV and 0-5kHz, AC-driven instabilities, resulting in various flame modes such as an oscillation, pinch-off and spinning of flames were identified. Characteristic frequency of each mode was determined and a visualization of near-nozzle flow structures suggested a close causality of initial counter-rotating vortices (inner and outer toroidal vortices - ITV and OTV), to the other observed flame. An axisymmetric ITV shedding was identified within oscillating and pinch-off modes, while asymmetric ITV shedding was identified with the spinning mode. Integrated electric power over several AC periods correlated well with variation in the flame surface area for these instabilities, demonstrating that measured electric power is a potential indicator of combustion instabilities in electric-field-assisted combustion.

Interband coherence response to electric fields in crystals: Berry-phase contributions and disorder effects

Science.gov (United States)

Culcer, Dimitrie; Sekine, Akihiko; MacDonald, Allan H.

2017-07-01

In solid state conductors, linear response to a steady electric field is normally dominated by Bloch state occupation number changes that are correlated with group velocity and lead to a steady state current. Recently it has been realized that, for a number of important physical observables, the most important response even in conductors can be electric-field induced coherence between Bloch states in different bands, such as that responsible for screening in dielectrics. Examples include the anomalous and spin-Hall effects, spin torques in magnetic conductors, and the minimum conductivity and chiral anomaly in Weyl and Dirac semimetals. In this paper we present a general quantum kinetic theory of linear response to an electric field which can be applied to solids with arbitrarily complicated band structures and includes the interband coherence response and the Bloch-state repopulation responses on an equal footing. One of the principal aims of our work is to enable extensive transport theory applications using computational packages constructed in terms of maximally localized Wannier functions. To this end we provide a complete correspondence between the Bloch and Wannier formulations of our theory. The formalism is based on density-matrix equations of motion, on a Born approximation treatment of disorder, and on an expansion in scattering rate to leading nontrivial order. Our use of a Born approximation omits some physical effects and represents a compromise between comprehensiveness and practicality. The quasiparticle bands are treated in a completely general manner that allows for arbitrary forms of the spin-orbit interaction and for the broken time reversal symmetry of magnetic conductors. We demonstrate that the interband response in conductors consists primarily of two terms: an intrinsic contribution due to the entire Fermi sea that captures, among other effects, the Berry curvature contribution to wave-packet dynamics, and an anomalous contribution caused

Cone restraining and head-only electrical stunning in broilers: Effects on physiological responses and meat quality

NARCIS (Netherlands)

Lambooij, E.; Reimert, H.G.M.; Verhoeven, M.T.W.; Hindle, V.A.

2014-01-01

Two experiments were conducted to evaluate a new electrical stunning system for broilers. The objective of the first experiment was to evaluate the behavioral, neural, and physiological responses of 27 broilers after head-only electrical stunning while their bodies were restrained in cone-shaped

Electrical resistivity response due to elastic-plastic deformations

International Nuclear Information System (INIS)

Stout, R.B.

1987-01-01

The electrical resistivity of many materials is sensitive to changes in the electronic band configurations surrounding the atoms, changes in the electron-phonon interaction cross-sections, and changes in the density of intrinsic defect structures. These changes are most directly dependent on interatomic measures of relative deformation. For this reason, a model for resistivity response is developed in terms of interatomic measures of relative deformation. The relative deformation consists of two terms, a continuous function to describe the recoverable displacement between two atoms in the atomic lattice structure and a functional to describe the nonrecoverable displacement between two atoms as a result of interatomic discontinuities from dislocation kinetics. This model for resistivity extends the classical piezoresistance representation and relates electric resistance change directly to physical mechanisms. An analysis for the resistivity change of a thin foil ideally embedded in a material that undergoes elastic-plastic deformation is presented. For the case of elastic deformations, stress information in the material surrounding the thin foil is inferred for the cases of pure strain coupling boundary conditions, pure stress coupling boundary conditions, and a combination of stress-strain coupling boundary conditions. 42 refs., 4 figs

Potential Analysis of Electric Vehicle (EV) Grid Integration

DEFF Research Database (Denmark)

Wu, Qiuwei; Nielsen, Arne Hejde; Østergaard, Jacob

2011-01-01

Electric vehicles (EVs) have been considered as distributed energy resources (DER) to handle the fluctuation from renewable energy resources (RES), especially the wind power. The intelligent management of EV charging and discharging can achieve the goal of providing up and down regulating power...

Control voltage and power fluctuations when connecting wind farms

Science.gov (United States)

Berinde, Ioan; Bǎlan, Horia; Oros Pop, Teodora Susana

2015-12-01

Voltage, frequency, active power and reactive power are very important parameters in terms of power quality. These parameters are followed when connecting any power plant, the more the connection of wind farms. Connecting wind farms to the electricity system must not cause interference outside the limits set by regulations. Modern solutions for fast and automatic voltage control and power fluctuations using electronic control systems of reactive power flows. FACTS (Flexible Alternating Current Transmision System) systems, established on the basis of power electronic circuits ensure control of electrical status quantities to achieve the necessary transfer of power to the power grid. FACTS devices can quickly control parameters and sizes of state power lines, such as impedance line voltages and phase angles of the voltages of the two ends of the line. Their use can lead to improvement in power system operation by increasing the transmission capacity of power lines, power flow control lines, improved static and transient stability reserve.

Control voltage and power fluctuations when connecting wind farms

International Nuclear Information System (INIS)

Berinde, Ioan; Bălan, Horia; Oros, Teodora Susana

2015-01-01

Voltage, frequency, active power and reactive power are very important parameters in terms of power quality. These parameters are followed when connecting any power plant, the more the connection of wind farms. Connecting wind farms to the electricity system must not cause interference outside the limits set by regulations. Modern solutions for fast and automatic voltage control and power fluctuations using electronic control systems of reactive power flows. FACTS (Flexible Alternating Current Transmision System) systems, established on the basis of power electronic circuits ensure control of electrical status quantities to achieve the necessary transfer of power to the power grid. FACTS devices can quickly control parameters and sizes of state power lines, such as impedance line voltages and phase angles of the voltages of the two ends of the line. Their use can lead to improvement in power system operation by increasing the transmission capacity of power lines, power flow control lines, improved static and transient stability reserve

Control voltage and power fluctuations when connecting wind farms

Energy Technology Data Exchange (ETDEWEB)

Berinde, Ioan, E-mail: ioan-berinde@yahoo.com; Bălan, Horia, E-mail: hbalan@mail.utcluj.ro; Oros, Teodora Susana, E-mail: teodoraoros-87@yahoo.com [Technical University of Cluj-Napoca, Romania, Faculty of Electrical Engineering, Department of Power Engineering and Management (Romania)

2015-12-23

Voltage, frequency, active power and reactive power are very important parameters in terms of power quality. These parameters are followed when connecting any power plant, the more the connection of wind farms. Connecting wind farms to the electricity system must not cause interference outside the limits set by regulations. Modern solutions for fast and automatic voltage control and power fluctuations using electronic control systems of reactive power flows. FACTS (Flexible Alternating Current Transmision System) systems, established on the basis of power electronic circuits ensure control of electrical status quantities to achieve the necessary transfer of power to the power grid. FACTS devices can quickly control parameters and sizes of state power lines, such as impedance line voltages and phase angles of the voltages of the two ends of the line. Their use can lead to improvement in power system operation by increasing the transmission capacity of power lines, power flow control lines, improved static and transient stability reserve.

Fluctuations in phenylalanine concentrations in phenylketonuria: a review of possible relationships with outcomes.

Science.gov (United States)

Cleary, Maureen; Trefz, Friedrich; Muntau, Ania C; Feillet, François; van Spronsen, Francjan J; Burlina, Alberto; Bélanger-Quintana, Amaya; Giżewska, Maria; Gasteyger, Christoph; Bettiol, Esther; Blau, Nenad; MacDonald, Anita

2013-12-01

Fluctuations in blood phenylalanine concentrations may be an important determinant of intellectual outcome in patients with early and continuously treated phenylketonuria (PKU). This review evaluates the studies on phenylalanine fluctuations, factors affecting fluctuations, and if stabilizing phenylalanine concentrations affects outcomes, particularly neurocognitive outcome. Electronic literature searches of Embase and PubMed were performed for English-language publications, and the bibliographies of identified publications were also searched. In patients with PKU, phenylalanine concentrations are highest in the morning. Factors that can affect phenylalanine fluctuations include age, diet, timing and dosing of protein substitute and energy intake, dietary adherence, phenylalanine hydroxylase genotype, changes in dietary phenylalanine intake and protein metabolism, illness, and growth rate. Even distribution of phenylalanine-free protein substitute intake throughout 24h may reduce blood phenylalanine fluctuations. Patients responsive to and treated with 6R-tetrahydrobiopterin seem to have less fluctuation in their blood phenylalanine concentrations than controls. An increase in blood phenylalanine concentration may result in increased brain and cerebrospinal fluid phenylalanine concentrations within hours. Although some evidence suggests that stabilization of blood phenylalanine concentrations may have benefits in patients with PKU, more studies are needed to distinguish the effects of blood phenylalanine fluctuations from those of poor metabolic control. © 2013.

Stopping coal-fired electricity imports on smog days : a review of the OPA's proposed 250 MW demand response program

International Nuclear Information System (INIS)

Gibbons, J.

2006-01-01

This paper proposed an alternative to importing coal-fired electricity from the Ohio Valley on smog alert days in Ontario. It was suggested that the Ontario Power Authority (OPA) should pay large electricity consumers to shift some of their consumption from peak to off-peak hours. It was observed that demand response programs which pay consumers to shift demands to off-peak hours can provide multiple benefits to Ontario, including reduced air pollution on smog-alert days, a reduction in the spot price of electricity and reduced price volatility. In addition, demand response programs reduce the risk of blackouts and brownouts, as well as the need for new electricity generation and transmission infrastructure. It was noted that the Independent Electricity System Operator (IESO) and the OPA are planning to introduce demand response programs for the summer of 2006. However, the IESO's emergency load reduction program will be operated only during emergency situations to avoid the need for voltage reductions, while the OPA proposes to introduce a non-emergency demand response program which will be activated during most smog-alert days. Various amendments to the proposed program were suggested in this paper, including the establishment of price parity with coal-fired electricity imports; the provision of notification by 3 PM of the need for demand reductions the following day; no capping on the quantity of demand reductions that the OPA will purchase at a lower cost than electricity imports; and that the OPA's proposed Capacity Building Demand Response Program should proceed as quickly as possible without a pre-determined MW cap. 4 refs., 6 figs

Rats with decreased brain cholecystokinin levels show increased responsiveness to peripheral electrical stimulation-induced analgesia.

Science.gov (United States)

Zhang, L X; Li, X L; Wang, L; Han, J S

1997-01-16

Using the P77PMC strain of rat, which is genetically prone to audiogenic seizures, and also has decreased levels of cholecystokinin (CCK), we examined the analgesic response to peripheral electrical stimulation, which is, in part, opiate-mediated. A number of studies have suggested that CCK may function as an antagonist to endogenous opiate effects. Therefore, we hypothesized that the P77PMC animals would show an enhanced analgesic response based on their decreased CCK levels producing a diminished endogenous opiate antagonism. We found that the analgesic effect on tail flick latency produced by 100 Hz peripheral electrical stimulation was more potent and longer lasting in P77PMC rats than in control rats. Moreover, the potency of the stimulation-produced analgesia correlated with the vulnerability to audiogenic seizures in these rats. We were able to block the peripheral electrical stimulation-induced analgesia (PSIA) using a cholecystokinin octapeptide (CCK-8) administered parenterally. Radioimmunoassay showed that the content of CCK-8 in cerebral cortex, hippocampus and periaqueductal gray was much lower in P77PMC rat than in controls. These results suggest that low CCK-8 content in the central nervous system of the P77PMC rats may be related to the high analgesic response to peripheral electrical stimulation, and further support the notion that CCK may be endogenous opiate antagonist.

Impact of diurnal temperature fluctuations on larval settlement and growth of the reef coral Pocillopora damicornis

Science.gov (United States)

Jiang, Lei; Sun, You-Fang; Zhang, Yu-Yang; Zhou, Guo-Wei; Li, Xiu-Bao; McCook, Laurence J.; Lian, Jian-Sheng; Lei, Xin-Ming; Liu, Sheng; Cai, Lin; Qian, Pei-Yuan; Huang, Hui

2017-12-01

Diurnal fluctuations in seawater temperature are ubiquitous on tropical reef flats. However, the effects of such dynamic temperature variations on the early stages of corals are poorly understood. In this study, we investigated the responses of larvae and new recruits of Pocillopora damicornis to two constant temperature treatments (29 and 31 °C) and two diurnally fluctuating treatments (28-31 and 30-33 °C with daily means of 29 and 31 °C, respectively) simulating the 3 °C diel oscillations at 3 m depth on the Luhuitou fringing reef (Sanya, China). Results showed that the thermal stress on settlement at 31 °C was almost negated by the fluctuating treatment. Further, neither elevated temperature nor temperature fluctuations caused bleaching responses in recruits, while the maximum excitation pressure over photosystem II (PSII) was reduced under fluctuating temperatures. Although early growth and development were highly stimulated at 31 °C, oscillations of 3 °C had little effects on budding and lateral growth at either mean temperature. Nevertheless, daytime encounters with the maximum temperature of 33 °C in fluctuating 31 °C elicited a notable reduction in calcification compared to constant 31 °C. These results underscore the complexity of the effects caused by diel temperature fluctuations on early stages of corals and suggest that ecologically relevant temperature variability could buffer warming stress on larval settlement and dampen the positive effects of increased temperatures on coral growth.

Amplitude and phase fluctuations of Van der Pol oscillator under external random forcing

Science.gov (United States)

Singh, Aman K.; Yadava, R. D. S.

2018-05-01

The paper presents an analytical study of noise in Van der Pol oscillator output subjected to an external force noise assumed to be characterized by delta function (white noise). The external fluctuations are assumed to be small in comparison to the average response of the noise free system. The autocorrelation function and power spectrum are calculated under the condition of weak nonlinearity. The latter ensures limit cycle oscillations. The total spectral power density is dominated by the contributions from the phase fluctuations. The amplitude fluctuations are at least two orders of magnitude smaller. The analysis is shown to be useful to interpretation microcantilever based biosensing data.

Intermittent electron density and temperature fluctuations and associated fluxes in the Alcator C-Mod scrape-off layer

Science.gov (United States)

Kube, R.; Garcia, O. E.; Theodorsen, A.; Brunner, D.; Kuang, A. Q.; LaBombard, B.; Terry, J. L.

2018-06-01

The Alcator C-Mod mirror Langmuir probe system has been used to sample data time series of fluctuating plasma parameters in the outboard mid-plane far scrape-off layer. We present a statistical analysis of one second long time series of electron density, temperature, radial electric drift velocity and the corresponding particle and electron heat fluxes. These are sampled during stationary plasma conditions in an ohmically heated, lower single null diverted discharge. The electron density and temperature are strongly correlated and feature fluctuation statistics similar to the ion saturation current. Both electron density and temperature time series are dominated by intermittent, large-amplitude burst with an exponential distribution of both burst amplitudes and waiting times between them. The characteristic time scale of the large-amplitude bursts is approximately 15 μ {{s}}. Large-amplitude velocity fluctuations feature a slightly faster characteristic time scale and appear at a faster rate than electron density and temperature fluctuations. Describing these time series as a superposition of uncorrelated exponential pulses, we find that probability distribution functions, power spectral densities as well as auto-correlation functions of the data time series agree well with predictions from the stochastic model. The electron particle and heat fluxes present large-amplitude fluctuations. For this low-density plasma, the radial electron heat flux is dominated by convection, that is, correlations of fluctuations in the electron density and radial velocity. Hot and dense blobs contribute only a minute fraction of the total fluctuation driven heat flux.

Dynamical study of the radial structure of the fluctuations measured by a reciprocating Langmuir probe in Tore Supra

International Nuclear Information System (INIS)

Devynck, P.; Antar, G.; Wang, G.; Garbet, X.; Gunn, J.; Pascal, J.Y.

1999-01-01

The fluctuations in the Scrape Off Layer (S.O.L.) of Tore Supra are studied with a movable Langmuir probe biased to ion saturation current. The probe system consists of three probes separated poloidally (0.68 cm between two nearby probes). The probe has no magnetic connection to the mid plane limiter on which the plasma is leaning, but the radial profile of the ion saturation current fluctuations displays a dip at the limiter position. At the same location the ion saturation current displays a dip at the limiter position. At the same location the ion saturation current displays an inflexion point. A correlation analysis technique is developed to study the radial behaviour of the fluctuations. It reveals that this dip is associated with a reduction of the poloidal velocity of the fluctuations with no sign reversal. In the dip the mean poloidal correlation length of the fluctuations is also reduced. These observations are consistent with a reduction of the fluctuations by a shear of the radial electric field created at the limiter surface. The autocorrelation time is also calculated. It increases slightly in the dip and is found to be sensitive to both the convection time and lifetime of the turbulent structures, because these quantities are of the same order. (authors)

Dynamical charge fluctuation at FAIR energy

International Nuclear Information System (INIS)

Ghosh, Somnath; Mukhopadhyay, Amitabha

2015-01-01

The Compressed Baryonic Matter (CBM) experiment to be held at the Facility for antiproton and ion research (FAIR) is being designed to investigate the baryonic matter under extreme thermodynamic conditions. The hot and dense matter produced in this experiment will be rich in baryon number. It would be worthwhile to examine how the signatures proposed for identifying and characterizing a baryon free QGP like state behave in a baryon rich environment. Event-by-event fluctuation of net electrical charge and/or baryon number is one such indicator of the formation of the QGP, used and tested in RHIC and LHC heavy-ion experiments. One starts by defining the net charge Q = (N + - N - ) and the total charge N ch = (N + + N - ) where the quantities N + and N - are respectively, the multiplicities of positively and negatively charged particles

Comparison of membrane electroporation and protein denature in response to pulsed electric field with different durations.

Science.gov (United States)

Huang, Feiran; Fang, Zhihui; Mast, Jason; Chen, Wei

2013-05-01

In this paper, we compared the minimum potential differences in the electroporation of membrane lipid bilayers and the denaturation of membrane proteins in response to an intensive pulsed electric field with various pulse durations. Single skeletal muscle fibers were exposed to a pulsed external electric field. The field-induced changes in the membrane integrity (leakage current) and the Na channel currents were monitored to identify the minimum electric field needed to damage the membrane lipid bilayer and the membrane proteins, respectively. We found that in response to a relatively long pulsed electric shock (longer than the membrane intrinsic time constant), a lower membrane potential was needed to electroporate the cell membrane than for denaturing the membrane proteins, while for a short pulse a higher membrane potential was needed. In other words, phospholipid bilayers are more sensitive to the electric field than the membrane proteins for a long pulsed shock, while for a short pulse the proteins become more vulnerable. We can predict that for a short or ultrashort pulsed electric shock, the minimum membrane potential required to start to denature the protein functions in the cell plasma membrane is lower than that which starts to reduce the membrane integrity. Copyright © 2013 Wiley Periodicals, Inc.

Demand response in liberalized electricity markets - the Nordic case

International Nuclear Information System (INIS)

Bjoerndal, Mette; Lund, Arne-Christian; Rud, Linda

2005-01-01

The liberalization of the Nordic electricity markets started with the deregulation of the Norwegian market, and the later inclusion of Sweden, Denmark and Finland in The Nord Pool area has provided a truly international marketplace, where prices are quoted for all the Nordic countries except Iceland. The structure of the Norwegian supply side was a favorable starting point for the liberalization process with many independent (hydropower) producers and, following the Energy Act of 1991, the vertical separation of competitive production on the one hand and regulated transmission / distribution one the other hand (implemented as a requirement of separation of financial accounts). Moreover, since the mid 1990s (unregulated) retail competition has provided market based price-signals to customers, even to individual households. In this paper we will focus on the potential benefits of demand flexibility in order to enhance the performance of the electricity market in attaining optimal operation and development of the electricity system. These benefits will depend on the price elasticity of the demand. However, whether it is possible to act on price changes also depends on the information provided to and from the customers. Especially for short run flexibility, this may require two way communication devises for larger customer groups, which raises questions like who is to pay for the investments needed, and who will benefit from them. Demand response also depends on the marginal signals resulting from the different contracts offered to the customers. Today this includes ''variable'' price, spot price (based on Nord Pool Elspot) and fixed price contracts. Customer flexibility depends on the possibility of substitution for instance to other fuels / alternative energy provisions. Finally, flexibility will differ between customer classes, for instance households, industry, power intensive industry etc. In this paper we investigate demand response and customer flexibility in

Electric vehicles and renewable energy in the transport sector - energy system consequences. Main focus: Battery electric vehicles and hydrogen based fuel cell vehicles

DEFF Research Database (Denmark)

Nielsen, L.H.; Jørgensen K.

2000-01-01

The aim of the project is to analyse energy, environmental and economic aspects of integrating electric vehicles in the future Danish energy system. Consequences of large-scale utilisation of electric vehicles are analysed. The aim is furthermore toillustrate the potential synergistic interplay...... between the utilisation of electric vehicles and large-scale utilisation of fluctuating renewable energy resources, such as wind power. Economic aspects for electric vehicles interacting with a liberalisedelectricity market are analysed. The project focuses on battery electric vehicles and fuel cell...... vehicles based on hydrogen. Based on assumptions on the future technical development for battery electric vehicles, fuel cell vehicles on hydrogen, and forthe conventional internal combustion engine vehicles, scenarios are set up to reflect expected options for the long-term development of road transport...

Emergent dynamics of spiking neurons with fluctuating threshold

Science.gov (United States)

Bhattacharjee, Anindita; Das, M. K.

2017-05-01

Role of fluctuating threshold on neuronal dynamics is investigated. The threshold function is assumed to follow a normal probability distribution. Standard deviation of inter-spike interval of the response is computed as an indicator of irregularity in spike emission. It has been observed that, the irregularity in spiking is more if the threshold variation is more. A significant change in modal characteristics of Inter Spike Intervals (ISI) is seen to occur as a function of fluctuation parameter. Investigation is further carried out for coupled system of neurons. Cooperative dynamics of coupled neurons are discussed in view of synchronization. Total and partial synchronization regimes are depicted with the help of contour plots of synchrony measure under various conditions. Results of this investigation may provide a basis for exploring the complexities of neural communication and brain functioning.

Hadronic Correlations and Fluctuations

Energy Technology Data Exchange (ETDEWEB)

Koch, Volker

2008-10-09

We will provide a review of some of the physics which can be addressed by studying fluctuations and correlations in heavy ion collisions. We will discuss Lattice QCD results on fluctuations and correlations and will put them into context with observables which have been measured in heavy-ion collisions. Special attention will be given to the QCD critical point and the first order co-existence region, and we will discuss how the measurement of fluctuations and correlations can help in an experimental search for non-trivial structures in the QCD phase diagram.

Electric dipole response of {sup 208}Pb and constraints on the symmetry energy

Energy Technology Data Exchange (ETDEWEB)

Tamii, A. [Research Center for Nuclear Physics, Osaka University, 10-1 Mihogaoka, Ibaraki 567-0047 (Japan)

2014-05-02

The electric dipole (E1) response of {sup 208}Pb has been precisely determined by measuring polarized proton inelastic scattering at very forward angles including zero degrees. The electric dipole polarizability, that is defined as the inverse energy-weighted sum rule of the E1 reduced transition strength, has been extracted as α{sub D} = 20.1 ±0.6 fm{sup 3}. A constraint band has been extracted in the plane of the symmetry energy (J) and its slope parameter (L) at the saturation density.

Bi-stability resistant to fluctuations

Science.gov (United States)

Caruel, M.; Truskinovsky, L.

2017-12-01

We study a simple micro-mechanical device that does not lose its snap-through behavior in an environment dominated by fluctuations. The main idea is to have several degrees of freedom that can cooperatively resist the de-synchronizing effect of random perturbations. As an inspiration we use the power stroke machinery of skeletal muscles, which ensures at sub-micron scales and finite temperatures a swift recovery of an abruptly applied slack. In addition to hypersensitive response at finite temperatures, our prototypical Brownian snap spring also exhibits criticality at special values of parameters which is another potentially interesting property for micro-scale engineering applications.

Electricity price and Southern California's water supply options

Energy Technology Data Exchange (ETDEWEB)

Dale, Larry [Lawrence Berkeley National Laboratory, Camilla Dunham Whitehead, Andre Fargeix, Golden Gate Economics, 1 Cycltron Road, Berkeley, CA 94720 (United States)

2004-11-01

This paper evaluates the impact of fluctuating electricity prices on the cost of five options to increase the water supply to urban areas in Southern California-new surface storage, water purchases, desalination, wastewater recycling, and conservation.We show that the price of electricity required to produce and transport water influences the cost of water supply options and may alter the decision makers economic ranking of these options. When electricity prices are low, water purchase is the cost effective option. When prices exceed US$ 86/MWh, conservation of electricity and water through installation of high efficiency clothes washers is the most effective option.

Analysis of the Robustness of Australia Economy and Energy Supply/Demand Fluctuation

Directory of Open Access Journals (Sweden)

Aslani Alireza

2017-10-01

Full Text Available Energy has a strategic role in social and economic development of the countries. Due to the high dependency of energy supply to fossil fuels, fluctuations in prices and supply have macro/micro-economics effects for both energy exporters and importers. Therefore, understanding economic stability based on energy market changes is an important subject for policy makers and researchers. As the competitiveness of Australia products/services has high dependency on energy prices, analyzing the relationships of economics robustness with fossil fuel fluctuations is important for the policy makers and researchers. In this paper, the researchers investigate the effects of energy changes on Australian economics. In this regard, first, the impact of oil price on macro-economic parameters is discussed. After that, the main issues related to energy economics including resilience of the energy sector, energy policies, economics analysis of the energy sector, electricity markets are discussed.

Fluctuating ideal-gas lattice Boltzmann method with fluctuation dissipation theorem for nonvanishing velocities.